Manufacture of Ethyl Acrylate From Glycerol (2012)

MANUFACTURE OF ETHYL ACRYLATE

FROM GLYCEROL

A Plant Design Presented to

The Faculty of the Chemical Engineering

In Partial Fulfilment of the

Requirements for the Degree of

Bachelor of Science in Chemical Engineering

Prepared by:

Ada, Mark Neil C.

Banta, Mhadel A.

Fonte, Ver Jeneth F.

Judilla, Agnes Dorothy D.

Pagasartonga, Mon Eric P.

October 2012

APPROVAL SHEET

In partial fulfillment of the requirement for the Degree of Bachelor of

Science in Chemical Engineering, this thesis entitled, “Manufacture of Ethyl

Acrylate from Glycerol” proposed and submitted by Mark Neil C. Ada, Mhadel

A. Banta, Ver Jeneth F. Fonte, Agnes Dorothy D. Judilla and Mon Eric P.

Pagasartonga is hereby recommended for approval by

Engr. Jerry G. Olay Panelist

Engr. Merlinda A. Palencia, Ph.D. Panelist

Engr. Renato C. Ong Adviser

Chemical Engineering Department Adamson University

Accepted and approved as partial compliance of the requirement for the

Degree of Bachelor of Science in Chemical Engineering.

Engr. Jerry G. Olay Chairperson

Chemical Engineering Department Adamson University

Letter of Transmittal

September 24, 2012

Engr. Renato C. Ong

Ch. E. Department

Sir:

In compliance to the requirements leading to the Degree of Bachelor of Science in

Chemical Engineering, the endorsement hereby take the pleasure in transmitting

this plant design entitled “Manufacture of Ethyl Acrylate from Glycerol”.

Respectfully yours,

Mark Neil C. Ada Mhadel A. Banta

Ver Jeneth F. Fonte Agnes Dorothy D. Judilla

Mon Eric P. Pagasartonga

ACKNOWLEDGMENT

This Plant Design is a combined effort of the group and several others who,

in one way or another, contributed to the completion of this requirement.

Therefore, it is only fitting that we acknowledge some of these people.

Firstly, this Plant Design could not have been accomplished without the

supervision of Engr. Renato Ong. He consistently encouraged and challenged us to

work with our best endeavors throughout the academic program. For all your

effort and patience, we thank you.

We would also like to give our deepest gratitude to all the authors

mentioned in the bibliography section. The collected knowledge from these

references made this Plant Design possible.

To Engr. Jerry Olay, the chairperson of the Chemical Engineering

Department; and to all the faculty members, including Dr. Merlinda Palencia, Dr.

Erickson Roque, Engr. Sherrie Mae Medez, and Engr. Albert Evangelista, we send

our sincerest appreciation to each of you for all the guidance. Furthermore, to

Engr. Mike Lester Raypan, our personal friend, we deeply appreciate every advice

and all the help we received throughout the research and design process.

We are, of course, forever grateful for the unending love and support of our

families and personal friends. Regardless of how long and tedious the entire

process took, these people were behind us all the way. The grace and heart

everyone has shown us especially through the down times served as our

inspiration to keep pushing forward.

Also, we extend our gratitude to our ChE friends: Engr. Raymond Kenneth

Dionisio, Engr. Kim Marie Barias, Engr. Leanna Mamorno, Khenbert Tecon, and

Edrian Bautista, for their earlier work, and the support they have given since.

Moreover, to our colleagues: Pinky Atregenio, Chessyrr Baylon, Camille

Candelaria, Shienah Ricarte, Rose Ann Suapero, and John Christopher Emalada;

for always being with us in the countless hours of waiting, for all the shared

laughter that kept our sanity, and simply for the company in the past few years,

and hopefully for many more years in the future, from the bottom of our hearts,

thank you.

Lastly, and most important of all, to God, who never failed to pull us when

everyone else cannot push anymore, we thank You with our entirety.

TABLE OF CONTENTS

CHAPTER 1 Product Description

I. Introduction 2

II. Product Profile 6

III. Raw Materials Profile 10

CHAPTER 2 Review of Related Literature

I. Introduction 35

II. Lists of Related Literatures 40

III. Summary of Related Literature

A. Process Description 49

B. Product Literature 72

C. Raw Material Literature 77

D. Design and Equipment Literature 97

CHAPTER 3 Process Description

I. Introduction 130

II. Process Flow Diagram 136

III. Detailed Process Description 137

CHAPTER 4 Plant Capacity Determination

I. Introduction 160

II. Supply and Demand Analysis 164

III. Raw Material Availability 169

IV. Conclusion 170

CHAPTER 5 Mass and Energy Balance

I. Introduction 174

II. Overall Mass & Energy Balance Diagram 176

III. Summary of Basis, Assumptions and Equations 177

IV. Mass Balance per Equipment 188

V. Energy Balance per Equipment 216

CHAPTER 6 Equipment Design

I. Introduction 244

II. Summary of Assumptions and Design Equations 246

III. Equipment Design

1. Dehydration Reactor 279

2. Shell and Tube Heat Exchanger 292

3. Absorption Column 309

4. Esterification Reactor 338

5. Pervaporator 354

CHAPTER 7 Cost Estimation

I. Introduction 375

II. Estimation of Capital Investment 380

III. Estimation of Product Cost 381

CHAPTER 8 Economic Evaluation

I. Introduction 436

II. Analysis and Interpretation

A. Rate of Return on Investment 437

B. Net Present Worth 438

C. Break-even Point Analysis 439

III. Conclusion 440

IV. Detailed Computations 441

APPENDICES 444

Appendix A: References for Product and Raw Material Description

Appendix B: References for Review of Related Literature

Appendix C: References for Process Description

Appendix D: References for Plant Capacity Determination

Appendix E: References for Mass and Energy Balance

Appendix F: References for Equipment Design

Appendix G: References for Cost Estimation

Appendix H: References for Economic Evaluation

1

CHAPTER I

PRODUCT

DESCRIPTION

2

CHAPTER I

PRODUCT DESCRIPTION

I. INTRODUCTION

Acrylic esters make the main product derived from acrylic acid and

traditionally produced by using propylene as raw material. They account for 55%

of global demand. About half of the crude acrylic acid is processed to purified

(glacial) acrylic acid, which is further processed both on-site (captive use) and by

external downstream users. The other half of crude acrylic acid is transformed into

various acrylate esters at the production sites. Identical to glacial acrylic acid,

these acrylic esters serve as commercial products, which are further processed

both on-site and by external downstream users.

Currently, the trend of using sustainable materials for production is

increasing in popularity due to the changes in global climate and as fossil sources

for hydrocarbons run short. For this reason, the production of fuel from renewable

sources such as biodiesel production is developing fast. In the biodiesel industry,

the biodiesel is produced through the transesterification of natural oils where one

mole of such oil yields three moles of hydrocarbon chains and one mole of

glycerol. The hydrocarbon chains are used as biodiesel fuels and the by-product is

glycerol. Due to the increasing awareness of climate change, these industries are

projected to increase, thus increasing in the glycerol production. However, the

3

demand for glycerol is not increasing with the same tendency. This causes the

price for glycerol to decrease, making it an interesting carbon source for

intermediates.

It is known that crude oil price is increasing. In connection to that, the

propylene price increases as well, since it is mainly crude oil based. This can lead

to increasing prices for acrylic acid production. On the other hand, glycerol prices

are decreasing. The reason: Glycerol is not an important intermediate. It is mostly

used in small amounts for cosmetics and for the food industry. Global glycerol

demand is not increasing so fast as the bio-diesel production. The use of glycerol

produced during the bio-diesel process has potential to be an environmentally

carbon source for the production of acrylic acid. Moreover, the economical

valorisation of glycerol makes the bio-diesel production more attractive. Replacing

propylene by glycerol would be an indirect step for improving the sustainability in

environmental care.

The manufacturing process of acrylic acid from glycerol involves first the

dehydration of glycerol to acrolein in phase gas, in the presence of solid catalysts

such as sulfated zirconia has been developed. These catalysts deactivate slowly so

as to permit long reaction cycles and low reactor volumes. The dehydration of

glycerol to acrolein takes place in the gas phase and can be expressed as:

4

That means, for each mole of glycerol, one mol of acrolein and two moles

of water (steam) are formed. In the case of the dehydration of glycerol, the

reaction is carried out in the presence of a solvent. The reaction takes place in a

catalyst fix bed, heated up by an oven with a heat homogenization system to

assure the heat homogenization. The gaseous products coming out from the reactor

are condensed in a glass reflux heat exchanger. The liquid is collected in a

continuously glass cooled double-coated flask. A sample can be taken for the

analysis, or the condensate can be transferred to the product flask.

The next process is the oxidation of acrolein which produces the product,

acrylic acid. This takes place in another catalyst fixed bed. The catalyst used is

vanadium-molybdenum oxide.

Technical Grade Acrylic Acid which usually has a purity of about 95%.

Technical acrylic acid is suitable for the production of commodity acrylate esters.

Acrylic Acid and its esters (which include methyl, ethyl, n-butyl, and 2-ethylhexyl

acrylate) are among the most versatile monomers for providing performance

properties to a wide variety of polymers. Major markets for the commodity esters

include surface coating, adhesive and sealants, textiles, plastic additives, and paper

treatment.

5

Acrylic esters may also be used in solutions and emulsions; the ethyl ester

is used in water-based paints and binders in non-woven fabrics; methyl ester as the

copolymer component of acrylic fibres; the butyl ester in the water-based paints

and adhesives; and the 2-ethylhexyl ester, used like the butyl ester as well as for

stick-on labels and sealants. Co-polymers and blends of methyl methacrylate,

butyl acrylate and ethyl hexyl acrylate are used in acrylic gloss paints where the

acrylates typically represent between 20 and 30 percent (dry basis) of the

formulation.

6

II. PRODUCT PROFILE

Acrylic acid and its esters have served, for more than 30 years, as an

essential building block in the production of some of our most commonly used

industrial and consumer products. One of its esters, ethyl acrylate, is used in the

production of polymers including resins, plastics, rubber, and denture material. It

is a clear liquid with an acrid penetrating odor. The human nose is capable of

detecting this odor at a thousand times lower concentration than is considered

harmful if continuously exposed for some period of time. Acrylic acid and its

esters readily combine with themselves or other monomers which are used in the

manufacture of various plastics, coatings, adhesives, elastomers, as well as floor

polishes, and paints.

A. PRODUCT IDENTIFICATION

Product Name Ethyl Acrylate

IUPAC Ethyl propenoate

Molecular Formula C5H8O2

Molecular Weight 100.12 g/mole

Specific gravity 0.922 (20°C)

Melting point -72°C

7

Boiling point 99.5 °C

Viscosity 0.55 Pa⋅s (25 °C)

Surface tension 25.2 mN/m (20°C)

Vapor pressure 29.3 mmHg (20°C)

Vapor density 3.45

Solubility in water 1.5 g/100g (25 °C)

B. PRODUCT COMPOSITION

SUBSTANCE CONCENTRATION BY WEIGHT

Ethyl acrylate 98%

Acrylic acid 1%

Ethanol 1%

C. HAZARD IDENTIFICATION

Physical State and Appearance Liquid

Color Colorless to Light Yellow

8

Odor Penetrating Lachrymator (Strong)

Incompatibility with various

substances

Product may react violently with water to

emit toxic gases or it may become self-

reactive under conditions of shock or

increase in temperature or pressure.

Corrosivity Non-corrosive in presence of glass.

Stability Stable

D. PRODUCT TRANSPORT, HANDLING AND STORAGE

Handling

Keep locked up Keep container dry. Keep

away from heat. Keep away from sources

of ignition. Keep away from direct sunlight

or strong incandescent light. Ground all

equipment containing material. Do not

ingest. Do not breathe

gas/fumes/vapour/spray. Never add water

to this product Avoid shock and friction. In

case of insufficient ventilation, wear

suitable respiratory equipment. If ingested,

9

seek medical advice immediately and show

the container or the label. Avoid contact

with skin and eyes.

Storage

Flammable materials should be stored in a

separate safety storage cabinet or room.

Keep away from heat. Keep away from

sources of ignition. Keep container tightly

closed. Keep in a cool, well-ventilated

place. Ground all equipment containing

material. A refrigerated room would be

preferable for materials with a flash point

lower than 37.8°C (100°F).

E. PRODUCT SAFETY

(Refer to Appendix, Material Safety and Data Sheet)

F. APPLICATION

Use as main raw material in production of acrylic latex paint.

10

III. RAW MATERIALS PROFILE

• GLYCEROL

Glycerol is the common name of propane-triol. It is a sweet tasting, highly

viscous colorless and odorless liquid with no known toxic properties. Glycerol has

many direct utilization fields, such as cosmetics, lubricants or explosives, and

other applications. Glycerol is a side-product of bio-diesel production. Natural oils

are triglycerides. The transesterification of one mole of such an oil yields three

moles of hydrocarbon chains and one mole of glycerol. The hydrocarbon chains

are used as bio-diesel fuels. Due to the developments in the bio-diesel industry, the

glycerol production is also increasing. Since the demand for glycerol is not

increasing with the same tendency, the glycerol price is decreasing, which makes

it an interesting carbon source for intermediates.

A. RAW MATERIAL IDENTIFICATION

Raw Material Name Glycerol

Synonyms

1, 2, 3-propanetriol

Glycerine

Glycol alcohol

Chemical Family Alcohol

11

Molecular Formula C3H5(OH)3

Structural Formula

Molecular Weight 92.10 g/mol

Density 1.261 g/cm³

Specific gravity 1.261

Melting point 17.8 °C (64.2°F)

Boiling point 290 °C (554°F)

Solubility Partially soluble in water

Appearance Clear oily liquid

Color colorless

Odor odorless

Surface tension 64.00 mN/m at 20 °C

http://en.wikipedia.org/wiki/File:SaponificationGeneral.svg

12

B. RAW MATERIAL COMPOSITION

SUBSTANCE CONCENTRATION BY WEIGHT

Glycerol <60%

Water >40%

C. HAZARD IDENTIFICATION

Physical State Liquid (viscous)

Stability stable

Flammability Slight

Incompatibility Reactive with oxidizing agents

D. STABILITY AND REACTIVITY

Stability Stable under ordinary conditions of use and

storage.

Hazardous Decomposition

Products

Toxic gases and vapor may be released if

involved in a fire. Glycerin decomposes

upon heating above 290°C, forming

13

corrosive gas (acrolein).

Hazardous Polymerization Will not occur.

Incompatibilities

Strong oxidizers. Can react violently with

acetic anhydride, calcium oxychloride,

chromium oxides and alkali metal

hydrides.

Conditions to Avoid Heat, flames, ignition sources and

incompatibles.

E. HANDLING AND STORAGE

Handling

Crude glycerol is shipped to

refiner/manufacturing plants in standard

tank cars or tank wagons.

Storage

Glycerol solidifies at lower temperatures,

and should be kept warm during

transportation and storing. Large storage

tanks should contain a heated loop from a

boiler or other heat source. Also, the boiler

room should be heated to prevent the

14

glycerol from gelling in the fuel lines, fuel

filters, and the boiler itself.

F. RAW MATERIAL SAFETY


G. APPLICATION

Glycerol is used as the major raw material for the manufacture of acrylic

acid and thus converting the acrylic acid to ethyl acrylate.

15

• AIR

Air is mainly composed of nitrogen, oxygen, and argon, which together

constitute the major gases of the atmosphere. The remaining gases are often

referred to as trace gases. Dry air contains roughly (by volume) 78.09% nitrogen,

20.95% oxygen, 0.93% argon, 0.039% carbon dioxide, and small amounts of other

gases. Air also contains a variable amount of water vapor, on average around 1%.

While air content and atmospheric pressure varies at different layers, air suitable

for the survival of terrestrial plants and terrestrial animals is currently only known

to be found in Earth's troposphere and artificial atmospheres.


Raw Material Name Air

Appearance and Odor Colorless and odorless gas

Vapor Density @ 70°F 1.2 kg/m3 (0.0749 lb/ft3)

Specific Gravity Not applicable

Molecular Weight 28.97

Solubility in Water (v/v) 0.0292

Vapor Pressure Gas, ambient

http://en.wikipedia.org/wiki/Nitrogen

http://en.wikipedia.org/wiki/Oxygen

http://en.wikipedia.org/wiki/Argon

http://en.wikipedia.org/wiki/Carbon_dioxide_in_the_Earth%27s_atmosphere

http://en.wikipedia.org/wiki/Water_vapor

http://en.wikipedia.org/wiki/Atmospheric_pressure

http://en.wikipedia.org/wiki/Terrestrial_plant

http://en.wikipedia.org/wiki/Terrestrial_animal

http://en.wikipedia.org/wiki/Troposphere

16

Freezing Point -216.2°C (-357.2°F)

Boiling Point (1 atm) -194.3°C (-317.8°F)

Specific Volume (ft3/lb): 13.8 (for Nitrogen)


COMPONENT COMPOSITION BY MOLE

Nitrogen 79%

Oxygen 21%

C. STABILITY AND REACTIVITY

Stability

Normally stable in gaseous state. Air which

contains excess oxygen may present the

same hazards as liquid oxygen and could

react violently with organic materials such

as oil and grease.

Materials with which Substance

is Incompatible

Fuels may form explosive mixtures with

air.

Hazardous Polymerization Will not occur

17

Conditions to Avoid

Contact with incompatible materials.

Avoid exposing cylinders to extremely

high temperatures, which could cause the

cylinders to rupture.

D. HANDLING AND STORAGE

Handling

Protect cylinders against physical damage.

Store in cool, dry, well-ventilated, fireproof

area, away from flammable or combustible

materials and corrosive atmospheres. Store

away from heat and ignition sources and

out of direct sunlight. Do not allow area

where cylinders are stored to exceed 52°C.

Storage

Use only DOT or ASME code containers.

Store containers away from heavily

trafficked areas and emergency exits.

Cylinders should be stored in dry, well-

ventilated areas away from sources of heat.

Cylinders should be stored upright and be

firmly secured to prevent falling or being

knocked over.

18

E. RAW MATERIAL SAFETY


F. APPLICATION

Air serves as a reactant in the process of converting acrolein to acrylic acid

(oxidation process).

19

• ETHYL ALCOHOL

Ethyl alcohol is classified as a primary alcohol, meaning that the carbon its

hydroxyl group attaches to has at least two hydrogen atoms attached to it as well.

Many ethanol reactions occur at its hydroxyl group. Ethanol is often abbreviated

as EtOH, using the common organic chemistry notation of representing the ethyl

group (C2H5) with OH. Ethanol has widespread use as a solvent of substances

intended for human contact or consumption, including scents, flavorings,

colorings, and medicines. In chemistry, it is both an essential solvent and a

feedstock for the synthesis of other products.


Raw Material Name Ethanol

Appearance Colorless clear liquid

Odor Mild, pleasant

Specific Gravity 0.790

Molecular Formula C2H5OH


Solubility Miscible

http://en.wikipedia.org/wiki/Hydroxyl

20

Vapor Pressure 59.3 mmHg @ 20°C

Vapor Density 1.59

Melting Point -114.1°C

Boiling Point 78°C


COMPONENT CONCENTRATION BY WEIGHT

Ethanol 100%


Stability Stable

Conditions of Instability Excess heat, incompatible materials,

water/moisture


is Incompatible

Strong oxidizing agents, acids, alkali

metals, ammonia, hydrazine, peroxides,

acid anhydrides, silver oxide, acid

chlorides.

21


Products

Carbon monoxide, carbon dioxide,

irritating and toxic fumes and gases.

Polymerization Will not occur


Handling

Wash thoroughly after handling. Use only

in a well-ventilated area. Ground and bond

containers when transferring material. Use

spark-proof tools and explosion proof

equipment. Avoid contact with eyes, skin

and clothing. Keep container tightly closed.

Avoid contact with heat, sparks and flame.

Avoid ingestion and inhalation. Do not

pressurize, cut, weld, braze, solder, drill,

grind, or expose empty containers to heat,

sparks or open flames.

Storage

Keep away from heat, sparks and flame.

Keep away from the source of ignition.

Store in a tightly closed container. Keep

from oxidizing materials. Store in a cool,

22

well-ventilated area away from

incompatible substances.


(Refer to Appendix, Material Safety and Data Sheet) F. APPLICATION

Ethanol is used as a reactant in the esterification process of acrylic acid

yielding to ethyl acrylate and water.

23

• TUNGSTATED ZIRCONIA

Tungstated Zirconia is a heterogeneous catalyst which is composed of

Zirconium Oxide (Zirconia) and Tungsten Oxide. Zirconia serves as the carrier of

the Tungsten Oxide which is the more active component in the system. This

catalyst will be used in the dehydration process of glycerol.


Zirconium Oxide

Raw Material Name Zirconium Oxide

Appearance Powdered solid

Odor Odorless

Color White

Taste Tasteless



Solubility

Insoluble in cold water, hot water. Slightly

soluble in Hydrochloric acid, Nitric Acid.

Slowly soluble in HF.

24

Melting Point 2680°C

Boiling Point 4300°C

Tungsten Oxide

Raw Material Name Tungsten Oxide

Appearance Powdered solid

Odor Odorless

Color yellow to yellow-green



Solubility Insoluble in cold water

Melting Point 1473°C


25



Zirconium Oxide

(CAS 1314-23-4) ≥90%

Tungsten Oxide

(CAS 1314-35-8) ≤10%

C. HANDLING AND STORAGE

Raw Material Name Zirconium Oxide

Handling Do not breathe dust.

Storage

Keep away from incompatibles such as

oxidizing agents. Keep container tightly

closed. Keep container in a cool, well-

ventilated area.

Raw Material Name Tungsten Oxide

Handling Keep away from heat. Keep away from

26

sources of ignition. Empty containers;

evaporate the residue under a fume hood.

Do not ingest. Do not breathe dust. Avoid

contact with eyes. Wear suitable protective

clothing. In case of insufficient ventilation,

wear suitable respiratory equipment. If

ingested, seek medical advice immediately.

Storage

Keep container dry. Keep in a cool place.

Ground all equipment containing material.

Keep container tightly closed. Keep in a

cool, well-ventilated place.

D. RAW MATERIAL SAFETY


E. APPLICATION

Tungstated Zirconia serves as a catalyst in the process of dehydration of

glycerol to acrolein.

27

• VANADIUM-MOLYBDENUM OXIDE

Vanadium-Molybdenum Oxide Catalyst is a type of heterogeneous catalyst

which is composed of Vanadium (IV) Oxide and Molybdenum Trioxide. This

catalyst will be used for the oxidation process of acrylic acid.


Vanadium (IV) Oxide

Raw Material Name Vanadium (IV) Oxide

Appearance crystalline powder

Odor odorless

Color blue



Solubility Insoluble in water

Melting Point 1967 oC

28

Molybdenum Trioxide

Raw Material Name Molybdenum Trioxide

Appearance yellow solid

Odor odorless



Solubility in water 2.055 g/100 mL (70 °C)

Melting Point 795 °C

Boiling Point 1155 °C



Vanadium(IV) Oxide

(CAS 12036-21-4)

≤16%

Molybdenum Trioxide

(CAS 1313-27-5)

≥84%

29

C. HANDLING AND STORAGE

Raw Material Name Vanadium(IV) Oxide

Handling

Open and handle container with care.

Wash thoroughly after use. Store away

from halogens. Do not get in eyes, on skin

or clothing. Do not breathe dust, vapor,

mist, gas.

Storage Keep container tightly closed. Store in a

cool, dry, well-ventilated area.

Raw Material Name Molybdenum Trioxide

Handling

Protect from physical damage. Containers

of this material may be hazardous when

empty since they retain product residues

(dust, solids); observe all warnings and

precautions listed for the product.

Storage Keep in a tightly closed container.

Store in a cool, dry, ventilated area away

30

from sources of heat, moisture and

incompatibilities.

D. RAW MATERIAL SAFETY

(Refer to Appendix, Material Safety and Data Sheet) E. APPLICATION

Vanadium-Molybdenum Oxide Catalyst serves as a catalyst in the process

of oxidation of acrolein to acrylic acid.

31

• SULFURIC ACID

Sulfuric acid is a highly corrosive strong mineral acid. It is a very important

commodity chemical. The historical name for this acid is oil of vitriol. It is a

viscous liquid and is soluble in water at all concentrations. The corrosiveness of it

is mainly due to its strong acidic nature, strong dehydrating property and if

concentrated strong oxidizing property. Principal uses include lead-acid batteries

for cars and other vehicles, mineral processing, fertilizer manufacturing, oil

refining, wastewater processing and chemical synthesis.


Raw Material Name Sulfuric acid

Appearance Colorless to slightly yellow liquid

Odor with pungent odor

Specific Gravity 1.834 (20 °C)

Molecular Formula H2SO4


Solubility Miscible in water

Viscosity 26.7 cP (20°C)

32

Melting Point 10.31°C



COMPONENT CONCENTRATION

Sulfuric acid 18 M (98 %wt)


Stability Stable


is Incompatible

Oxidizers, Acids, Metals, Bases, Alkalis,

Reducing agents, Water, Organics, Metal

carbides. Product is water reactive.


Products SOx, Hydrogen Gas

Polymerization Will not occur

33


Handling Keep container tightly closed in a cool,

well-ventilated place.

Storage

Store in a secure area suitable for toxic

material.

Keep locked up and out of the reach of

children. Never add water to this product.



F. APPLICATION

Sulphuric acid is used as a catalyst in the process of esterification of acrylic

acid to the product ethyl acrylate.

34

CHAPTER II

REVIEW OF

RELATED LITERATURE

35

CHAPTER II

REVIEW OF RELATED LITERATURE

I. INTRODUCTION

Biodiesel is made through a catalyzed chemical reaction

(transesterification) between oils or fats and an alcohol (usually methanol). It has

showed its importance as renewable and clean source of fuel for diesel engines.

Common feedstocks are pure vegetable oil (e.g., soybean, canola, sunflower),

rendered animal fats, or waste vegetable oils. Strong bases such as sodium

hydroxide (NaOH) or potassium hydroxide (KOH) are commonly used as

catalysts.

As the biodiesel industry is rapidly expanding, a glut of crude glycerol is

being created. Crude glycerol is the major by-product of the biodiesel industry. In

general, for every 100 pounds of biodiesel produced, approximately 10 pounds of

crude glycerol are created. Because this glycerol is expensive to purify for use in

food, pharmaceutical, or cosmetics industries, biodiesel producers must seek

alternative methods for its disposal.

Glycerol itself can not be burnt as a fuel, because at high temperatures it

polymerizes and partially oxidizes to toxic acrolein. Besides it is also very difficult

to use the glycerol coming from biodiesel production for its traditional uses in

pharmacy and cosmetic since it does not have the required purity.

36

As a growing concern in the abundance of waste glycerol and the lack of

areas to dispose this large waste stream, combustion of glycerol may be one of the

simplest solutions. Clean combustion of glycerol is not possible because of its

properties. In particular, burning of it will produce acrolein which is the thermal

decomposition product of glycerol and is toxic at very low concentrations.

With the increasing expansion of biomass as raw material in general, and

biodiesel production in particular, glycerol is expected to become a major

chemical platform for future biorefineries since it has emerged as an important

organic building block. However, developing selective glycerol based catalytic

processes is a major challenge. Thus, a high number of patents and research papers

are being published nowadays.

The dehydration of glycerol into acrolein has been known since the

nineteenth century. Acrolein or acrylic aldehyde is used as intermediate for the

production of many useful compounds as acrylic acid, acrylic acid esters, super

absorber polymers and detergents. A sustainable and cost efficient dehydration of

glycerol to acrolein could offer an alternative for the current commercial catalytic

petrochemical process based on the reaction of propylene over a Bi/Mo-mixed

oxide catalyst. In addition, direct synthesis of acrylonitrile and acrylic acid from

glycerol is an attractive approach since both compounds are useful chemicals as

raw materials for various synthetic resins, paints, fibbers etc.

37

Gas-phase catalytic oxidation of acrolein to acrylic acid has been given

attention since late 1960s being concerned with the development of the two-step

process fro production of acrylic acid from propene via acrolein as an

intermediate. Acrylic acid is a versatile chemical that can be esterified, aminated

or otherwise modified and polymerised to complex molecular arrangements to suit

requirements. This characteristic enables a broad range of reactions for providing

performance characteristics to a range of polymers.

A high purity form (often referred to as glacial acrylic acid) is produced by

a second distillation or crystallisation that reduces aldehyde impurities (especially

furfural) which inhibit polymerisation. Different grades of glacial acrylic acid are

available with flocculants requiring higher purity levels than dispersants and some

other applications while a technical grade of acrylic acid may be produced by a

simple distillation to produce a grade of acid suitable for the manufacture of

acrylic esters, but unsuitable for polymerisation.

The esters are produced by reacting acrylic acid with alcohols especially

ethanol, methanol and butanol that may be saponified, converted to other esters or

amides by aminolysis. Acrylates are derivatives of acrylic acid (such as methyl

and ethyl acrylate) whose properties have been sufficiently modified to enable of

acrylic acid to be used in different media as emulsion and solution polymers. As

emulsions, these products may be used as coatings, finishes and binders leading to

applications in paints, adhesives, and polishes with solutions used for industrial

38

coatings. Two-third of the world's production of acrylic acid is used to produce

acrylic esters (acrylates) primarily for use in emulsions and solution polymers for

latex-based paints, coatings, adhesives and textiles.

Ethyl and methyl acrylates are manufactured on a continuous basis by

passing acrylic acid and a small excess of the alcohol in a reactor bed at elevated

temperature extracted at a yield of about 90 to 95 percent. Acrylic esters may be

polymerised, catalysed by heat and oxidising agents in solution or emulsion

methods to form long-chain thermoplastic resins. Broadly, acrylic ester polymers

are colourless, insoluble in aliphatic hydrocarbons and resistant to alkali, mineral

oils and water so that with good resistance to degradation, adhesion and electrical

properties, they are widely used.

Researches show varieties of glycerol transformations and processing that

include the manufacture of ethyl acrylate. There are three major processes involve

in this conversion, the dehydration of glycerol into acrolein, oxidation to form

acrylic acid and esterification to produce ethyl acrylate. Synthesis of acrylic acid

from glycerol represents an economic advantage since the latter does not

contribute to global warming.

Acrylates are used in a broad range of applications directly as a resin, or as

solution or emulsion. The following provides an indication of typical applications

with the market share expressed as a percentage of all acrylic acid applications as

acrylic acid. Surface coatings, such as paints, represent the largest application for

39

acrylic esters at about 19 per cent of the market. Demand, that was motivated by

the convenience of water-based paints especially the superior acrylic-based

emulsions, is now being driven by regulations and interests to reduce atmospheric

release of volatile organic compounds (VOCs) used as solvents in traditional

(alkyd-based) surface coatings. This sector is growing at 3 to 5 per cent per year

with faster growth for newer more sophisticated applications.

Extensive research is applied to acrylic chemistry and with a very broad

range of alternative processes, this activity has become specialised with patents

and proprietary knowledge. There are now more manufacturers of specialty acrylic

esters (that do not themselves manufacture acrylic acid) than there are

manufacturers of the acid. The esters are generally produced near major traditional

markets and suppliers of acrylic acid.

40

II. LISTS OF RELATED LITERATURES

BOOKS

• Gavin T. et al. (2008). Chemical Engineering Design Principles, Practice and

Economics of Plant and Process Design. 2nd Ed. U.S.: Elsevier, Inc.

• Geankoplis, Christie J. (1993). Transport Processes and Unit Operations. 3rd

Ed. Prentice-Hall International, Inc.

• McCabe. W. et al. (2001). Unit Operations of Chemical Engineering. 6th Ed.

New York: McGraw-Hill

• Octave L. et al. (1999). Chemical Reaction Engineering. 3rd Ed. John Wiley &

Son, Inc.

• Perry, R. and Green, D. (2008). Perry’s Chemical Engineers’ Handbook. 8th

Ed. New York: McGraw-Hill

• Shah, R. et al. (2003). Fundamentals of Heat Exchanger Design. John Wiley &

Sons.

• Treybal, Robert E. (1981). Mass-Transfer Operations. 3rd Ed. New York:

McGraw-Hill

• Ullman’s (2004). Processes and Process Engineering. Wiley-VCH, Vol. 3.

ENCYCLOPEDIA

• Kirk-Othmer (1999). Concise Encylopedia of Chemical Technology. 4th Ed.

New York: John Wiley & Sons, Inc.

41

INTERNET

• Acrylic Acid. Retrieved from www.chemsystems.com

• Acrylic Acid manufacture in Western Australia

Retrieved from http://www.chemlink.com.au/acryful.htm

• Acrylic Acid Production: Separation and Purification. Lin, Stephany et al.

http://www.owlnet.rice.edu/~ceng403/gr2499/aagrp4.html

• Acrylic Acid Production via the Catalytic Partial Oxidation of Propylene:

Separation Design

http://www.owlnet.rice.edu/~ceng403/gr21099/acrylicacid2.htm

• Compilation of Henry’s Law Constant for Inorganic and Organic Species of

Potential Importance in Environmental Chemistry

http://www.mpch-mainz.mpg.de/~sander/res/henry.html

• Ethanol

http://www.chemeurope.com/en/encyclopedia/Ethanol.html

• Gases of the Air

Retrieved from http://scifun.chem.wisc.edu/chemweek/pdf/airgas.pdf

• Method for Production of Acrylic Acid

http://www.patentstorm.us/patents/7332624/fulltext.html

• Pervaporation An Overview

http://www.cheresources.com/content/articles/separation-

technology/pervaporation-an-overiew

42

• Production of Acrylic Acid

http://sbioinformatics.com/design_thesis/Acrylic_Acid/Acrylic-2520Acid.htm

• Sulfuric Acid

http://www.chemeurope.com/en/encyclopedia/Sulfuric_acid.html

• The Mechanism for the Esterification Reactor

http://www.chemguide.co.uk/physical/catalysis/esterify.html

• Turbine & High Efficiency Axial Flow Agitators

http://www.feldmeier.com/cutsheets/turbine_agitator.pdf

JOURNALS

• Alvarez, M et al. (2007). Evaluation of Liquid-Liquid Extraction Process for

Separating Acrylic Acid Produced from Renewable Sugars.

• Chai, Song-Hai et al. (2007). Sustainable Production of Acrolein: Gas-phase

Dehydration of Glycerol over Nb2O5 Catalyst. Journal of Catalysis 250: 342-

349.

• Chengwang, Z. Acrylic Acid: Raw material cost pushed prices of acrylic acid

and esters.

• Cortes-Jacome, M.A. et al. (2006). Generation of WO3-ZrO2 Catalysts from

Solid Solutions of Tungsten in Zirconia. Journal of Solid State Chemistry 179:

2663-2673.


43

• Deleplanque, J. et al. (2010). Production of Acrolein and Acrylic Acid through

Dehydration and Oxydehydration of Glycerol with Mixed Oxide Catalysts.

Catalysis Today 157: 351-358.

• El-Zanati, E. et al. (2006). Modeling and Simulation of Butanol Separation

from Aqueous Solutions Using Pervaporation. Journal of Membrane Science

280 (2006) 278–283.

• Fan, X. et al. (2010). Glycerol (Byproduct of Biodiesel Production) as a Source

for Fuels and Chemicals - Mini Review. The Open Fuels & Energy Science

Journal, Vol. 3, 17-22.

• Guerrero-Perez, M.O. et al. (2009). Recent Inventions in Glycerol

Transformations and Processing. Recent Patents on Chemical Engineering,

Vol. 2, No. 1.

• Kaszonyi, A. et al. (2009). Bioglycerol: A New Platform Chemical. 44th

International Petroleum Conference, Bratislava, Slovak Republic, September

21-22, 2009.

• Kim, Y.T. et al. (2010). Gas-phase Dehydration of Glycerol over ZSM-5

Catalysts. Microporous and Mesoporous Materials 131: 28-36.

• Kraai, G. et al. (2008). Kinetic Studies on the Rhizomucor miehei lipase

catalyzed Esterification Reaction of Oleic acid with 1-butanol in a Biphasic

System. Biochemical Engineering Journal 41 (2008) 87–94.

44

• Kujawski, W. (2000). Application of Pervaporation and Vapor Permeation in

Environmental Protection. Polish Journal of Environmental Studies Vol. 9, No.

1 (2000), 13-26

• Lipnizki, F. et al (1999). Simulation and Process Design of Pervaporation

Plate-and-Frame Modules to Recover Organic Compounds from Waste Water.

Institution of Chemical Engineers Trans IChemE, Vol 77, Part A, May 1999.

• Tao, L.Z. et al. (2010). Sustainable Production of Acrolein: Acidic Binary

Metal Oxide Catalysts for Gas-phase Dehydration of Glycerol. Catalysis

Today 158: 310-316.

• Tichy, Josef (1997). Oxidation of Acrolein to Acrylic Acid over Vanadium-

Molybdenum Oxide Catalysts. Applied Catalysts A: General 157: 363-385.

• Ulgen, A. and Hoelderich, W. (2009). Conversion of Glycerol to Acrolein in

the Presence of WO3/ZrO2 Catalysts. CatalLett 131:122-128

• Wang, F. et al. (2009). Catalytic Dehydration of Glycerol over Vanadium

Phosphate Oxides in the Presence of Molecular Oxygen. Journal of Catalysis

268, 260-267.

PATENTS

• AlArifi, S. et al. (2011). Synthesis of Acrylic or Methacrylic Acid/Acrylate or

Methacrylate Ester Polymers Using Pervaporation.

European Patent Number 2325214

United States Patent Number 2011/0124829

45

• Bunning, D. et al. (1991). Process for Producing Acrylic Ester.

United States Patent Number 4999452

• Diefenbacher, A. et al. (2009). Process for Preparing Acrylic Acid.


• Dubois, Jean-Luc (2010). Method for Preparing Acrylic Acid from Glycerol.


• Dubois, Jean-Luc (2010). Process for Manufacturing Acrolein from Glycerol.


• Dubois, J.L. et al. (2008). Method for Producing Acrylic Acid from Glycerol.


• Dubois, J.L. et al. (2008). Process for Dehydrating Glycerol to Acrolein.




• Elder, J. et al. (2003). Process for Preparing and Purifying Acrylic Acid From

Propelyne Having Improved Capacity.

US Patent Number 6639106

• Figueras, F. et al. (2006). Tungsten Catalysts.

United States Patent Number 2006 /0091045

• Hammon, U. et al. (1993). Catalytic Gas-phase Oxidation of Acrolein to

Acrylic Acid.

46


• Hecquet, G. et al. (2000). Process for the Manufacture of Acrylic Acid from

Acrolein by a Redox Reaction and Use of a Solid Mixed Oxide Composition as

Redox System in the said reaction.


• Hego, M. et al. (1998). Process and Apparatus for Purification of a Gas

Stream Containing Acrolein.


• Hershberger, B.L., et al. (2005). Method of Producing Ethyl Acrylate.


• Ishidoya, M. et al. (1992). Resin Composition for Use as Paint.


• Ishii, Y. et al. (2006). Method for Purification of Acrylic Acid.

Unites States Patent Number 7048834

• Jones, L. et al. (1994). Process for the Production of Plasticizers and

Polyolesters.


• Kang, S. et al. (2009). Method for Producing (Meth) Acrylic Acid.


• Kang, S. et al. (2008). Method for Producing (Meth) Acrylic Acid.


47

• Krabetz, R. et al. (1986). Production of Acrylic Acid by Oxidation of Acrolein.


• Kautter, C.T. et al. (1969). Esterification of Acrylic Acid.


• Neher, A. et al. (1995). Process for the Production of Acrolein.


• Rezkallah, Areski (2008). Method for Purification of Glycerol.


• Ruppel, W. et al. (1998). Catalytic Gas-Phase Oxidation of Acrolein to Acrylic

Acid.


• Sato, T. et al. (1982). Process for Preparing and Recovering Acrylic Acid.


• Shidhar, Srinivasan (1995). Process for the Removal of Water from Acrylic

Acid.


• Soohoo, T. et al. (2007). Membrane-assisted Fluid Separation Apparatus and

Method.


• Tanimoto, M. et al. (2011). Process for Producing Acrolein and/or Acrylic

Acid.

48


• Tanimoto, M. et al. (2010). Process for Producing Acrolein and Acrylic Acid.


• Yukawa, Yoshiyuki (2009). Water-Based Paint Compositions.


OTHER REFERENCES

• Alzate, Javier Fontalvo (2006). Design and Performance of Two-Phase Flow

Pervaporation and Hybrid Distillation Processes.

• Arda, Ulgen (2009). Conversion of Glycerol to the Valuable Intermediates of

Acrolein and Allyl Alcohol in the Presence of Heterogeneous Catalysts.

• Gott, Paige (2009). Variation in the Chemical Composition of Crude Glycerin.

• Prieto, Sergio Sabater (2007). Optimization of the Dehydration of Glycerol to

Acrolein and a Scale up in a Pilot Plant.

• Pyle, Denver J. (2008). Use of Biodiesel-Derived Crude Glycerol for the

Production of Omega-3 Polyunsaturated Fatty Acids by the Microalga

Schizochytriumlimacinum.

• US outlook for Acrylic Acid & Derivatives with forecast to 2006-2011 (THE

FREEDONIA GROUP, INC.)

• Xu, Weihua (2001). Design and Development of a Pervaporation Membrane

Separation Module.

49

III. SUMMARY OF RELATED LITERATURE

A. PROCESS DESCRIPTION

Dehydration of Glycerol to Acrolein

Conversion of glycerol to acrolein has been known since the nineteenth

century and there are several recent patents describing this process, but the

majority of them describe as the dehydration of glycerol to form acrolein. Acrolein

is a highly toxic material with extreme lachrymatory properties. At room

temperature acrolein is liquid with volatility and flammability somewhat similar to

acetone. It is usually synthesized on the site of production to minimize the storage

and transportation because of the flammability, reactivity and toxicity of acrolein.

According to Guerrero-Perez et al. in “Recent Inventions in Glycerol

Transformations and Processing” from Recent Patents on Chemical Engineering,

2009, Vol. 2, No.1, dehydration of glycerol to acrolein is normally performed over

acid catalysts. Glycerol can be supplied to the reactor in liquid or in gas phase but

it was found that acrolein yields were lower in liquid phase than in gas phase. As

by Y.T. Kim et al. in their work entitled “Gas-phase dehydration of glycerol over

ZSM-5 catalysts” from Microporous and Mesoporous Materials 131(2010), they

include to the study the information that high glycerol conversion and selectivity

for acrolein can be modulated in the gas-phase reaction. In the invention of Dubois

of US Patent 2010/0168471 with title “Method for Preparing Acrylic Acid from

Glycerol”, he stated that “the use of an aqueous solution of glycerol has a

50

drawback of producing a stream containing not only the acrolein produced and

the by-products, but also a large quantity of water, originating partly from the

glycerol solution, and partly from the water produced by the dehydration

reactor.”

There are different types of catalysts that can be incorporated in the

dehydration process. The best catalysts that would yield acrolein over 70%,

discussed by A. Kaszonyi et al. in the “Bioglycerol: A new Platform Chemical”

from the paper released by the 44th International Petroleum Conference (Slovak

Republic, September 21-22, 2009), are the most acidic catalysts with Hammett

acidity constants H0 between -10 and -16. The catalysts at lower acidity will

relatively easily deactivate and acrolein yield will be below 60%. Supported by

Dubios et al. from US Patent 2008/0214880 with invention title “Process for

Dehydrating Glycerol to Acrolein”, they claimed that the process is accompanied

by “a strongly acidic solid catalyst with Hammett acidity H0 of between -9 and -

18 and preferably between -10 and -16.”

A. Ulgen and W. Hoelderich describe the “Conversion of Glycerol to

Acrolein in the Presence of WO3/ZrO2 Catalysts” (CatalLett, 2009, 131:122-128).

They reported that with their collaboration with Arkema, they found out that

WO3/ZrO2 catalysts yields 73-80% of acrolein. Among the various solid-acid

catalysts studied by S. Prieto in his dissertation entitled “Optimization of the

Dehydration of Glycerol to Acrolein and a Scale up in a Pilot Plant”, such as

51

HZSM5, H Beta Zeolite, Phosphated zirconia and WO3/ZrO2. He found out that

experiments carried out with the WO3/ZrO2 catalyst are the most promising. The

data on his experiments is as follows.

Tungsten zirconia catalysts based from US Patent 2006/0091045 (Figueras

et al.) provide an alternative to reactions which are catalyzed by means of acid

sites and they are deactivated to a lesser extent. With high melting point at 3003

K, low thermal conductivity and high resistance to corrosion, Zirconium oxides or

zirconia (ZrO2) is widely used as catalyst. M.A. Cortes-Jacome et al. on Journal of

Solid State Chemistry 179 (2006) discussed on their study with title “Generation

of WO3-ZrO2 catalysts from solid solutions of tungsten in zirconia” that zirconia

modified with sulphate, phosphate, heteropolyacids HPA, tungsten and

molybdenum has emerged as an alternative catalysts to substitute chlorinated

alumina and liquid acid catalysts because zirconia based catalysts can be

regenerated easily. Among those different modifications, tungsten oxide dispersed

on zirconia seems to be the most stable. Prieto reported that tungsten zirconia

52

catalysts offer inherent advantages from the standpoint of industrial application,

such as higher stability under high-temperature treatments, lower deactivation

rates during catalysis, and easier regeneration.

Reaction of the dehydration of glycerol to acrolein is given in this mechanism.

Summary of the above mechanism is given below

Aqueous glycerol which is the major by-product during the biodiesel

production is supplied to the reactor. US Patent 2010/0168471 discussed that

dehydration reaction is carried at a temperature of between 150 °C and 500 °C,

preferably between 250 °C and 350 °C, and at a pressure between 1 and 5 bar,

preferably between 1 and 3 bar. Ulgen et al. stated that at temperatures higher than

240 °C, glycerol is extensively converted. The acrolein selectivity, however,

53

shows a maximum at 280 °C. At lower temperatures the intermolecular

dehydration, yielding oligomers of glycerol, is thermodynamically favoured over

the desired intramolecular dehydration forming acrolein. At temperatures higher

than 280 °C, the formation of CO and CO2 is possible. These two reasons are

responsible for the selectivity decrease of acrolein. That is also supported by the

fact that the untrapped product mass increased with rising temperatures, from 0.1

wt% at 240 °C to 2.0 wt% at 320 °C. In the mini review “Glycerol as a Source for

Fuels and Chemicals” conducted by X. Fan et al., they reported that a study has

been conducted showing lower pressures are effective for rapid removing the more

volatile products from the catalyst sites thus achieving a long catalysts service life.

Prieto included in his study that when the glycerol solution reaches 200 °C,

the mixture is completely evaporated. Between 104 and 200 °C, the system is a

mixture of liquid and vapor. The molar composition of the vapour fraction, y1, can

be obtained by reading on the condensation curve, and the molar composition of

the liquid fraction, x1, by reading on the vaporization curve. The dehydration of

glycerol leads to acrolein as a main product. He concluded that the glycerol

conversion has the following findings:

• Increases with the temperature because the dehydration of glycerol to

acrolein is endothermic. However, the kinetic can limit the process.

• Decreases when concentrated glycerol solutions are used.

54

• Decreases when high glycerol solution feed flows are used. That is

expected because faster feed flows achieve lower residence times.

While the selectivity of acrolein have these

• Increases with the temperature until approximately 280 - 285 °C, and then

decreases a little.

• Decreases with the glycerol concentration.

• Increases with the glycerol solution feed flow.

“An approach for finding an optimum working point can be determined. To

get a complete glycerol conversion it is better to work at high temperatures.

Around 280 °C the acrolein production is the highest. However, at higher

temperatures, close to 300 °C, the formation of acrolein decreases a little, and the

formation of by-products increases with the temperature. Therefore, a

temperature, around 285 °C will be appropriate to produce the highest amount of

acrolein at a complete glycerol conversion and to minimize the formation of by-

products. The glycerol concentration should be not too high because at high

glycerol concentrations, the glycerol conversion and acrolein selectivity

decreases.”

According to the US Patent 5387720, “gas phase reaction is preferable

since it enables a degree of conversion of the glycerol of close to 100% to be

obtained. A proportion of about 10% of the glycerol is converted into acetol,

which is present as the major by-product in the acrolein solution.”

55

Prieto also reported that “An appropriate feed flow could be the minimal

flow, which produces complete conversion or close to 100 % and high acrolein

selectivity, but not too high to avoid the formation of acetol.”

“In the previous analysis, it was predicted that a temperature near 280 °C

achieves the highest acrolein selectivity at complete glycerol conversion. Now, the

optimization results can be examined with temperatures between 274 and 290 °C.

However, the solutions, which achieve the highest selectivity for acrolein, show

that the optimal temperature is around 275 - 280 °C. Keeping in mind the kinetic

effect over the reaction, high temperatures will favor the reaction. However, over

290 °C neither complete glycerol conversion nor high acrolein selectivity is

reached. The explanation to this effect could be due to the boiling point of pure

glycerol. Over 290 °C pure glycerol burns, which leaves less glycerol to be

converted into acrolein and, of course, less acrolein to be produced. This effect

can explain why at high temperatures the reaction works not so well, even being

an endothermic reaction. The effect of the glycerol burning has to be also taken in

account.”

56

Removal of Water-Rich Stream by Absorption

Absorption is further utilized to achieve high purity of acrolein coming

from the stream produced in the dehydration reactor. According from the work of

Jean-Luc Dubois entitled Method for Preparing Acrylic Acid from Glycerol (US

Patent No. 2010/0168471),

“The invention relates to a method for preparing acrylic acid from an

aqueous glycerol solution, comprising a first step of dehydration of the glycerol to

acrolein, in which an intermediate step is implemented, consisting in at least

partly condensing the water and heavy by-product present in the stream issuing

from the first dehydration step.”

“The solution provided by the invention constitutes an optimization

between the quantity of water fed to the first stage dehydration reactor and the

quantity of water introduced into the second stage oxidation reactor. The solution

consists in at least partly condensing the water present in the stream issuing from

the dehydration reaction of the aqueous glycerol solution, to prevent the second

stage catalyst from being deactivated too rapidly, on the other hand, and to

prevent the acrylic acid solution produced from being too dilute, on the other.”

“In the method according to the invention, the expression at least partly

condensing means that 20% to 95%, preferably 40% to 90%, of the water present

57

in the stream issuing from the first step is removed in the intermediate step before

being sent to the second stage reactor.”

“The partial condensation unit may be an absorption column optionally

coupled to an evaporator, a heat exchanger, a condenser, a dephlegmator, and

any apparatus well known to a person skilled in the art, serving to carry out a

partial condensation of an aqueous stream.”

“The acrolein-rich stream, stripped of the heavy by-products and most of

the water, is sent to the oxidation reactor where the acrolein can then be oxidized

to acrylic acid with a controlled and higher partial pressure. The productivity of

the reactor is thereby improved.”

“The method according to the invention, even though it requires an

additional unit associated with the intermediate step, has the advantage of using

an economical raw material and of being able to optimize the two reaction stages

separately. This increase the acrylic acid productivity and selectivity. The method

remains demonstrably economical.”

Purification of acrolein is described in the US Patent No. 5770021 entitled

“Process and Apparatus for Purification of a Gas Stream Containing Acrolein”,

“This process includes cooling the reaction mixture in a cooling tower,

where it is brought into contact with condensing liquid, an effluent gas containing

58

predominantly non-condensable and acrolein being recovered at the top of the

tower.”

“Accordingly, the present invention provides a process for the purification

of acrolein present in a feed gas stream including acrolein, water, by-products

and inert gases, originating particularly from the first reactor, which process

comprises, in a first stage, fractionating the feed gas stream into a gaseous

effluent and a liquid stream in a cooling column operating such that the

temperature of the liquid stream at the bottom of the column is lower than or

equal to the condensation temperature of the feed gas stream, the difference in the

temperature not exceeding 20°C, preferably not exceeding 10°C; and then, in a

second stage, condensing the gaseous effluent at a temperature that is lower the

20°C to give a liquid fraction and a purified gaseous fraction.”

“As used herein, the term “inert gases” is intended to mean all of the

gaseous compounds that remain in the gaseous phase from the beginning to the

end of the production process of the invention and that are found in the purified

gaseous fraction after condensation stage. In this respect, the inert gases in the

mixture to be purified may, in what follows, be occasionally called “non-

condensable” since they are not condensed under the temperature and pressure

conditions used in the process of invention. The inert gases generally include

nitrogen, oxygen, and other gases from air.”

59

“The circulation of the gaseous stream in the column counter-currentwise

to a cold liquid result in condensation of the water and other condensable

components that may be present. The condensed liquid flows back down under

gravity to the bottom of the column. The gases at the top of the column are

depleted in impurities and include acrolein and non-condensable gases. The

temperature of the gases at the top of the column preferably ranges from 30° to

60°C, and still more preferably from 50° to 60°C.”

“The temperature of the liquid stream at the bottom of the column is

preferably less that 20°C, and more preferably less than 10°C, lower than the

condensation temperature of the feed gas stream. Preferably, the temperature of

the liquid stream at the bottom of the column is substantially equal to the

condensation temperature of the gaseous mixture introduced into the column to

reduce to a minimum condensation of acrolein and degradation; in most cases it is

lower than 100°C. The condensation temperature of the gaseous mixture

originating from the catalytic dehydration of glycerol preferably ranges from 70°

to 90°C, at a pressure of approximately 1.2x105 Pa.”

“The cooling column preferably operates at a pressure ranging from 105 to

3x105 Pa. The recycled stream generally contains organic acids and preferably

less than 2%, more preferably less than 1.5%, by weight of acrolein and at least

90% by weight of water.”

60

Oxidation of Acrolein to Acrylic Acid

Acrylic acid is used as a precursor for a wide variety of chemicals in the

polymers and textile industries. Direct synthesis of acrylic acid from glycerol is an

attractive approach since it is useful as raw material for various synthetic resins,

paints, fiber etc. The process involves two steps, a dehydration of glycerol to

acrolein which was mentioned earlier followed by gas-phase catalytic oxidation

carried out with an oxide catalyst. Oxidation of acrolein to acrylic acid has been

known since late 1960s attached with the manufacture of acrylic acid from

propylene but Prieto reported that crude oil is still the main propylene source and

we cannot afford to utilize more crude oil due to its scarcity. Using raw material

like glycerol will be an alternative also it has the advantage of being renewable

meeting the criteria connected to the concept of “green chemistry”.

According to J. Tichy in his work refer to “Oxidation of acrolein to acrylic

acid over vanadium-molybdenum oxide catalysts”, he reported that “oxidation of

acrolein proceeds favourably with a stoichiometric excess of oxygen, and the

reaction temperature should not exceed 573 K or else it will yield an undesirable

radical reaction”. He also believed that among the recommended catalysts, the

most efficient system for the conversion of acrolein to acrylic acid involve oxide

systems based on Mo-V, Mo-Co, V-Sb and heteropolyacids. US Patent

20100168471 also suggested the catalysts made of formulations containing Mo

61

and/or V and/or W and/or Cu and/or Sb and/or Fe should be used in the catalytic

reaction.

The present invention (US 5264625) based on the patent made by

Hammon, et. Al, “Catalytic Gas-phase Oxidation of Acrolein to Acrylic Acid”,

aims to provide a process for the catalytic gas-phase oxidation of acrolein to

acrylic acid in an fixed bed reactor having contacting tubes, at elevated

temperature on catalytically active oxides with a conversion of acrolein for a

single pass of ≥95%.

“We have found that this object is highly achieved wherein the reaction

temperature in the flow direction along the contacting tubes (along the reaction

axis) in a first reaction zone before the starting reaction gases containing the

reactants enter the contacting tubes is from 260° to 300°C until a methacrolein

conversion of a ≥95% has been reached, with the proviso that the reaction

temperature in this secondary reaction zone is not lower than 240°C.”

Conversion of crude glycerol to acrylic acid via acrolein as its intermediate

step is shown in this stoichiometric reactions.

62

Oxidation reaction from acrolein to acrylic acid.

Based on the US Patent 20100168471, oxidation reaction takes place at

temperature of between 200 °C and 350 °C, preferably from 250 °C to 320 °C and

under the pressure of between 1 and 5 bar. The reaction is carried out in the

presence of molecular oxygen which may be in the form of air having a content of

between 3 to 20% by volume, with regard to the incoming stream and optionally

in the presence of inert gases such as N2. The inert gases necessary for the method

may be optionally consist in full or in part of gases obtained at the top of the

absorption column.

US Patent 5264625 described the oxidation process is highly exothermic. It

is therefore required to control the reaction temperature in order to obtain a highly

selective conversion of acrolein to acrylic acid. Industrial production of acrylic

acid is at present carried out by vapour phase catalytic oxidation of acrolein.

A tandem reaction of dehydration and oxidation process of converting

glycerol to acrylic acid was made by Prieto. He said that the experiment ran

successfully and acrolein was completely converted to acrylic acid.

63

“In the Figure 4.23, the experiment ran successfully. No acrolein was

found anymore. That means a complete oxidation to acrylic acid took place. Other

by-products, like acetic acid and propionic acid were also observed. Due to the

oxidation, acetaldehyde and propanal were oxidized to their correspondent acids.

It is important to mention that mass loss was observed during the reaction. In the

Figure 4.23, after the first hour of the reaction no products were found. Almost a

mass loss of 100 % in carbon mass was observed. This can be explained due to the

amount of oxygen used in the reaction (see section 4.4.3.2 and Figure 4. 24). The

percentage of mass loss decreases with the reaction time, as long as acrylic acid

and other by-products such acetic and propionic acid, were formed. At the

stationary-state around 25 % of mass loss was found. Around 40 % of acrylic

64

acid, 10 % of acetic acid and 3 % of propionic acid were found. The 25 % of mass

loss should be due to the burning of compounds on the catalytic particles.”

“For the oxidation reaction, the reaction temperature in the oxidation

catalyst increases gradually during 140 minutes, and after that, it remains

constant at 310 °C. This means that the oxidation reaction is taking place. The

higher the reaction temperature in the oxidation catalytic bed, the higher is the

formation of acrylic acid. Once the temperature is stabilized at 310 °C, the

formation of acrylic acid remains also constant at around 40 %. After 300

minutes, when the oxygen flow was switched off, the temperature of the oxidation

catalytic bed dropped to 286 °C. That means, that no exothermic reaction was

taking place and in consequence no acrylic acid was formed.”

65

Esterification of Acrylic Acid to form Ethyl Acrylate

Various acrylic esters are useful chemicals. Esterification of acrylic acid

with alcohol has commercially been performed by using liquid catalysts such as

sulfuric acid, hydrofluoric acid, and para-toluenesulfonic acid; however these are

toxic, corrosive and often hard to remove from the solution.

From US Patent 20050107629 – Method for Producing Ethyl Acrylate by

Rohm and Haas Company: “The present invention is directed to a continuous

process for producing ethyl acrylate and for recovering acrylic acid, ethyl

acrylate, ethanol and water from an esterification reactor mixture containing

acrylic acid, ethyl acrylate, ethanol, water and acid catalyst.”

“This invention relates to a method for combining acrylic acid and ethanol,

and processing the reaction products to produce ethyl acrylate in improved yield.

Fresh crude acrylic acid, ethanol, and esterification catalyst are fed to the

esterification reactor. Typical components of the bottoms stream comprise acrylic

acid, at 60 to 90% and acrylic acid dimer (AOPA), at 10 to 40%. The acrylic acid

from the bottoms stream comprises from 5% to 15% of the total acrylic acid fed to

the esterification reactor. The molar ratio of acrylic acid to ethanol is from 1 to

66

1.1 to 1 to 1.5, preferably from 1 to 1.1 to 1 to 1.2. The esterification reactor

temperature is maintained at from 85° C. to 105° C., at reactor pressures from

220-320 mm Hg. At least one heat exchanger may be used to control the

temperature of esterification reactor.”

According to US Patent 3458561 (Esterification of Acrylic Acid), “the

minimum temperature at which the esterification is achieved depends upon the

boiling point of the formed acrylic acid ester, of the azeotrope formed from the

acrylic acid ester and water, respectively, as well as whether one uses

subatmospheric pressure, atmospheric pressure, or super-atmospheric pressure.

In general, temperature between 70 to180 °C is employed.”

“This invention relates to a novel process for esterifying acrylic acid, more

specifically this method pertains to a novel combination of variables which results

in the obtention of acrylic acid esters in high yields by a simplified and more

economical esterification which combination also includes the ester product

recovery. A number of processes are known which are directed to the conversion

of acrylic acid and an alcohol to the corresponding acrylic ester in the presence of

an esterification catalyst. However, the following problems exist: (a) ethyl

acrylate, ethanol and water form an azeotrope boiling at 77.1° C, at a pressure of

760 mm. Of mercury, which azeotope at a rather great expense can be processed

further to recover the ester product; (b) the polymerization tendency of acrylic

67

acid and its ester reduces to a considerable degree the alternatives which may be

taken when carrying out the esterification reaction.”

“Esterification of acrylic acid is possible in a liquid as well as in a gas

phase. Of primary importance as an esterification catalyst is sulfuric acid and/ or

a sulfonic acid. In respect to the amounts at which these catalysts have been

utilized, the catalyst should be used in amounts such as about 0.01% sulphuric

acid per mole of acrylic acid. In order to achieve the desired reaction, the

reduction of the formation of a ternary azeotrope of the ester, alcohol and water

and obtaining only the ester-water mixture, contrary to the heretofore recognized

methods, exceptionally large amounts of acid are necessary such as from 5 to 50%

by weight of sulfuric acid or 10 to 80% by weight of the above describe sulfonic

acid. Preferably an amount of the acid is chosen, which comprises 7 to 35% by

weight of the sulfuric acid or 20 to 70% by weight of the sulfonic acid on the basis

of the reboiler contents. Considering the esterification speed and conversion and

avoiding at the same time the formation of undesirable side reactants, the best

results are obtained when using in the reboiler from 10 to 25% by weight of

sulfuric acid or 30 to 50% by weight one of the aforementioned sulfonic acid with

a residence time of 3 hours.”

The reaction of acrylic acid and alcohol is as follows:

68

From US Patent No. 20050107629, “Reacting the acrylic acid and ethanol

to yield ethyl acrylate in a conversion of at least 90% on acrylic acid, and yielding

the esterification reaction mixture comprising ethyl acrylate, acrylic acid, ethanol

and water.”

From Biochemical Engineering Journal 41 (2008) 87–94 by G.N. Kraai et

al., “In esterification reactions, a batch reactor equipped with four baffles and a

six-bladed turbine impeller is used.”

From Turbine & High Efficiency Axial Flow Agitators,

http://www.feldmeier.com/cutsheets/turbine_agitator.pdf, “The speed range for

commercially available turbine agitator is 63 to 73 rpm.”

69

Purification of Ethyl Acrylate by Pervaporation

Among the different membrane separation technologies, pervaporation is

presently considered as a process unit with high potential to recover organic

compounds from aqueous organic mixtures using hydrophobic membranes. This

application is of particular interest to the chemical industry since integration of

pervaporation into waste water treatment includes the opportunity to recover

organic compounds to a standard that both water and organic compounds could be

reused without additional processing. Hence this approach might offer both

environmental and economical benefits to industry. Pervaporation is characterized

by the evaporation of water from permeate side. In vacuum pervaporation, the heat

required for evaporation is supplied from the feed side. Consequently, there will

be a temperature gradient in direction of the feed.

A major problem in the esterification of polyacrylic or methacrylic acid is

removing water from the reaction mixture during its production due to the

presence of an azeotropic water-alcohol mixture. Sometimes the boiling points of

alcohol and water are very close and sometimes some crosslinking reaction occurs

at high temperature. The extraction of water from the reaction mixture using a

traditional technique such as distillation is a non-economical method.

Pervaporation is an energy efficient and high selective extraction process for the

extraction of volatile products and for the dehydration of organic chemicals. The

productivity and conversion rate can be significantly increased.

70

From EP 2325214A1, the present invention relates to the synthesis of ethyl

acrylate by esterification of acrylic acid with alcohol assisted by the pervaporation

technique for extracting water.

“A major problem in the esterification of polyacrylic or methacrylic acid is

removing water from the reaction mixture during its production due to the

presence of an azeotropic water-alcohol mixture. Sometimes the boiling points of

alcohol and water are very close and sometimes some crosslinking reaction

occurs at high temperature. The extraction of water from the reaction mixture

using a traditional technique such as distillation is a non-economical method.”

“The object of the present inventions is further solved by a use of a

membrane in the production of acrylate ester, for extracting water produced

during esterification of acrylic acid with alcohol in the presence of an acid as

catalyst. In one embodiment of the use, the membrane comprises or is made of

polyvinylalcohol modified and crosslinked with a crosslinking agent at 2-6 weight-

%, preferably at 2-5 weight-%, using different technique. In one embodiment of

the use, the membrane has a thickness of about 5-200υm, preferably of about 22-

55 υm, most preferably of about 25 υm. The method according to the invention

allows for the production of copolymers and terpolymers at controlled

composition (0-99 %mole). The pervaporation apparatus employed in this

invention is similar to that used by different authors, such as Bing Cao et al.”

71

“Pervaporation is an energy efficient and highly selective extraction

process for the extraction of volatile products and for the dehydration of organic

chemicals. The productivity and conversion rate can be significantly increased

when the reaction is coupled with pervaporation, i. e., a pervaporation reactor.

Techno-economic studies revealed that pervaporation reactors have good market

potential in process industries.”

“The combination of an esterification reaction of polyacrylic or

polymethacrylic acid with a pervaporation process increases the conversion of

reversible reactions, such as esterification, by removing selectively the water

formed from the reacting mixture. Thus, the yield of the conversion is greatly

enhanced.”

“An esterification reaction between an alcanol and a carboxylic acid in the

presence of a catalyst is a reversible reaction, and a high industrial conversion

can be achieved by adding a large excess of acid. A water selective pervaporation

membrane can be used in the esterification reactor. This can shift the equilibrium

to the right, thus reducing excess reactants.”

72

B. PRODUCT LITERATURE

Ethyl acrylate is an organic compound primarily used in the preparation of

various polymers. Ethyl acrylate can be prepared by several industrial methods.

Acrylonitrile can be reacted with ethanol using sulfuric acid as a catalyst to

produce ethyl acrylate. It may also be prepared from acetylene, carbon monoxide

and ethanol. Ethyl acrylate is used to form paint coatings that is resistant to water,

sunshine, and weather. These coatings retain flexibility even at low temperatures.

EA is also used in industrial finishes and coatings for cans and coils. Fabrics gain

texture and durability when ethyl acrylate is added during their manufacture. Ethyl

acrylate also imparts dirt resistance, improves abrasion, and binds pigments to

fabric. Paper is coated with ethyl acrylate to make it water-resistant. Magazines,

books, business paper, frozen food packaging, and folding boxboards have such

coatings, making them resistant to water, grease, and oil. Ethyl acrylate is also

used in adhesives for envelopes, labels, and decals. Caulk, glazing, and various

sealants also contain Ethyl acrylate. Leather products, such as automotive

upholstery, furniture, clothing, and shoes contain EA so that top coatings do not

migrate. Ethyl acrylate is also used as a fragrance additive in various soaps,

detergents, creams, lotions, perfumes, and as a synthetic fruit essence. Ethyl

acrylate is also found in such household items as nail mending kits and in medical

items that assist with the binding of tissues, sealing wounds, etc.

http://en.wikipedia.org/wiki/Sulfuric_acid

http://en.wikipedia.org/wiki/Acetylene

http://en.wikipedia.org/wiki/Carbon_monoxide

73

Acrylic esters make the main product derived from acrylic acid. They

account for 55% of global demand. About half of the crude acrylic acid is

processed to purified (glacial) acrylic acid, which is further processed both on-site

(captive use) and by external downstream users. The other half of crude acrylic

acid is transformed into various acrylate esters at the production sites. Identical to

glacial acrylic acid, these acrylic esters serve as commercial products, which are

further processed both on-site and by external downstream users. Glacial acrylic

acid is used in the manufacture of super absorbing polymers (SAP), which account

for 32% of the global demand for acrylic acid. Acrylic acid and basic alkyl esters

(methyl, ethyl, butyl and 2-ethylhexyl esters) are used for the manufacture of

polymer dispersions, adhesives, super absorbent polymers, flocculants, detergents,

varnishes, fibres and plastics as well as chemical intermediates.

“Greater attention is now paid to environmental protection and energy

saving. Research organizations and production enterprises are developing and

disseminating various environmental protection and energy saving technologies.

The radiation curing technology takes special acrylic esters as major raw

materials and UV rays or electron beams as initiators to polymerize acrylic esters

into polymer films. Compared with conventional polymerization methods, this

technology does not use chemical initiators, polymerization takes place at normal

temperature and no heat is used. Initiators are saved and energy consumption is

reduced.

74

“Acrylic esters and derivatives represent about 65 per cent of the market

for acrylic acid in the USA, slightly higher than in Australia.”

“Acrylates are used in a broad range of applications directly as a resin, or

as solution or emulsion. The following provides an indication of typical

applications with the market share expressed as a percentage of all acrylic acid

applications as acrylic acid (ie. including the previously described polyacrylic

acids).”

“Surface coatings, such as paints, represent the largest application for

acrylic esters at about 19 per cent of the market. Demand, that was motivated by

the convenience of water-based paints especially the superior acrylic-based

emulsions, is now being driven by regulations and interests to reduce atmospheric

release of volatile organic compounds (VOCs) used as solvents in traditional

(alkyd-based) surface coatings. This sector is growing at 3 to 5 per cent per year

with faster growth for newer more sophisticated applications (such as UV

radiation-curable polymers).”

“The Australian surface coating industry is dominated by ICI Australia,

Wattyl and Taubmans using emulsions made by companies such as Rohm and

Haas and BASF from imported ethyl and other acrylic esters. The paint industry in

Australia, like in other developed countries, is growing at about 2 per cent per

year.”

75

“Adhesives and sealants are the second largest application for a broad

range of esters that represents about 15 per cent of acrylic acid applications.

Though this sector is closely related to the variable and slower growing

construction sector, like the surface coating sector it has been stimulated by

concerns about VOCs. This sector has been growing at 4 to 6 per cent per year in

most markets and faster in Asian textile-producing regions with growing

construction sectors.”

“Textiles represent about 11 per cent of the market for acrylic esters in the

USA of which about 90 per cent is used as emulsions for use in non-woven fabrics

and textile treatment, and only 10 per cent for textile fibres. Growth in the USA

has been about 2 per cent but substantially faster in some Asian countries.”

“A range of acrylic esters are used to produce plastic forms and sheets

representing about 8 per cent of the market that is growing at about 3 per cent.”

Demand has increased for acrylic acid derivatives, specifically ethyl

acrylates used in the production of surface coatings. Still, the growth is being

limited by the current global inventory of crude acrylic acid. Due to growing

demand for acrylic acid derivatives led by SAPs, many of the major producers

have responded by expanding plants and building new production facilities at key

sites throughout the world.

76

2005 2006 2007 2008

China,

People's Republic 12,630 3,004 204,234 49,296

Indonesia

(Includes West Irian) 566,880 248,345 417,487 643,563

Japan

(Excludes Okinawa) 143,065 106,540 738,500 235,582

Korea,

Rep. of (South) 1,547,700 1,631,096 1,400,716 1,026,230

Malaysia

(Federation of Malaya) 1,572,684 1,913,767 7,425,932 6,851,514

Singapore 1,373,245 1,674,298 1,457,535 4,571,053

South Africa,

Rep. of 326,445 650,925 23,550 -

Table 2.1. Countries that Produce Ethyl Acrylate (kg)

COUNTRIES

YEAR

77

C. RAW MATERIAL LITERATURE

• Glycerol

Glycerol, propane-1, 2, 3-triol, glycerin, a trihyhdric alcohol, is a clear,

water-white, viscous, sweet-tasting hygroscopic liquid at ordinary room

temperatures above its melting point. Glycerol occurs naturally in combined form

as glycerides in all animal and vegetable fats and oils, and is recovered as a by-

product when these oils are saponified in the process of manufacturing soap, when

the fats are split in the production of fatty acids, or when fats are esterified with

methanol in the production of methyl esters.

The uses of glycerol number in thousands, with large amounts going into

the manufacture of drugs, cosmetics, toothpaste, methane foam, synthetic resins

and ester gums. Tobacco processing and foods also consume large amounts either

as glycerol or glycerides.

Glycerol was introduced by Sergio Sabater Prieto to his work Optimization

of the Dehydration of Glycerol to Acrolein and a Scale up in a Pilot Plant.

“Glycerol is the common name of propane-triol. It is a sweet tasting,

highly viscous colorless and odorless liquid with no known toxic properties.”

“Glycerol has many direct utilization fields, such as cosmetics, lubricants

or explosives, and other 1300 applications, but not enough market possibilities to

take all the glycerol from diesel production.”

78

“Glycerol is a side-product of bio-diesel production. Natural oils are

triglycerides. The transesterification of one mole of such an oil yields three moles

of hydrocarbon chains and one mole of glycerol. The hydrocarbon chains are used

as bio-diesel fuels. Due to the developments in the bio-diesel industry, the glycerol

production is also increasing. Since the demand for glycerol is not increasing with

the same tendency, the glycerol price is decreasing, which makes it an interesting

carbon source for intermediates.”

“The dehydration of glycerol to acrolein is an adequate reaction with

interesting economic and environmental aspects.”

“Bio-diesel is produced from agricultural products and not from crude oil.

Glycerol is formed as a by-product during the transesterification process, which is

the key step for the production of bio-diesel.”

“The use of glycerol produced during the bio-diesel process has potential

to be an environmentally carbon source for the production of acrylic acid.

Moreover, the economical valorisation of glycerol makes the bio-diesel production

more attractive. Replacing propylene by glycerol would be an indirect step for

improving the sustainability in environmental care.”

“It is known that crude oil price is increasing. In connection to that, the

propylene price increases as well, since it is mainly crude oil based. On the other

hand, glycerol prices are decreasing. The reason: Glycerol is not an important

79

intermediate. It is mostly used in small amounts for cosmetics and for the food

industry. Global glycerol demand is not increasing so fast as the bio-diesel

production. The following diagram compares the price evolution of propylene and

different qualities of glycerol.”

In the thesis made by Denver J. Pyle with title “Use of Biodiesel-Derived

Crude Glycerol for the Production of Omega-3 Polyunsaturated Fatty Acids by

the Microalga Schizochytriumlimacinum”, the crude glycerol produced during the

biodiesel production process is impure and of little economic value.

“The impurities include methanol and soaps. Biodiesel producers use

excess methanol to drive the chemical transesterification and do not recover the

entire methanol. Therefore, it is present in the glycerol layer. Also, free fatty acids

present in the initial feedstock can react with the base to form soaps that are

soluble in the glycerol layer. In addition to methanol and soaps, crude glycerol

also contains a variety of elements such as calcium, magnesium, phosphorous, or

sulfur.”

“It has been reported that glycerol makes up anywhere from 65% to 85%

(w/w) of the crude glycerol streams (Gonzalez-Pajuelo et al., 2005; Mu et al.,

2006). The remaining weight in the crude glycerol streams is mainly methanol and

soaps. The wide range of the purity values can be attributed to different glycerol

purification methods used by the biodiesel producers and the different feedstocks

used in biodiesel production. For example, Thompson and He (2006) have

80

characterized the glycerol produced from various biodiesel feedstocks. It was

found that the crude glycerol from any feedstock is generally between 60 and 70 %

(wt) glycerol. Mustard seed feedstocks had a lower level (62%) of glycerol, while

soy oil feedstock had 67.8 % glycerol and waste vegetable had the highest level

(76.6 %) of glycerol.”

According to US Patent 2008/0249338 (Method for Purification of

Glycerol), aside from glycerol, crude glycerol from biodiesel production typically

contains methanol, water, inorganic salts and salts of fatty acids.

“Levels of inorganic salts typically are from 5% to 50%. Levels of

inorganic salts are from 1% to 5%. These levels typically are expressed together

in terms of total cation concentration, which usually is from 0.2% to 5%. Crude

glycerol contains water, and may also be diluted further with water to reduced

load on the column and aid in the separation, so that typical water levels can be

from 5% to 40%. In some embodiments of the invention, glycerol concentration in

the crude glycerol introduced into the resin bed is at least 20%, alternatively at

least 30%, alternatively at least 40%, alternatively at least 50%, alternatively at

least 60%, alternatively at least 70%, alternatively at least 75%.

81

• Air

The air around us is a mixture of gases, mainly nitrogen and oxygen, but

containing much smaller amounts of water vapor, argon, and carbon dioxide, and

very small amounts of other gases. Air also contains suspended dust, spores, and

bacteria. Because of the action of wind, the percent composition of air varies only

slightly with altitude and location.

Air retrieved from http://scifun.chem.wisc.edu/chemweek/pdf/airgas.pdf

“The amount of water in the air varies tremendously with location,

temperature, and time. In deserts and at low temperatures, the content of water

vapor can be less than 0.1% by volume. In warm, humid zones, the air may

contain over 6% water vapor.”

“Air is the commercial source for many of the gases it contains. It is

separated into its components by fractional distillation of liquefied air. Before air

is liquefied, water vapor and carbon dioxide are removed, because these

substances solidify when cooled and would clog the pipes of the air liquefaction

plant. The dry, CO2-free air is compressed to about 200 atmospheres. This

compression causes the air to become warm, and the heat is removed by passing

the compressed air through radiators. The cooled, compressed air is then allowed

to expand rapidly. The rapid expansion causes the air to become cold, so cold that

82

some of it condenses. By the alternate compressing and expanding of air, most of

it can be liquefied.”

“Nearly all commercial oxygen (over 95%) is produced by fractional

distillation of liquid air. It boils at -183EC. Oxygen is the third highest-volume

chemical produced in the U.S., and most of this product is more than 99.5% pure.

Oxygen is paramagnetic, that is, it is attracted to a magnet. Liquid oxygen is pale

blue. The major commercial uses of oxygen are in metal manufacturing (30%),

metal fabricating (33%), and in health services (13%). In the steel industry,

oxygen is passed through impure molten iron in a blast furnace to oxidize and

remove impurities such as carbon, sulfur, phosphorus, and silicon. Oxygen is also

used as the oxidant in torch cutting of steel. In this process, the steel is heated by

an oxygen-acetylene flame, and a stream of hot oxygen is directed at the hot steel.

The hot steel is oxidized by the hot oxygen and erodes away, severing the steel.

Oxygen is also used extensively in the chemical industry, such as in the production

of nitric acid, HNO3, from ammonia, NH3.”

Oxygen occurs mainly as an element in the atmosphere. It makes up 20.948

percent of the atmosphere. It also occurs in oceans, lakes, rivers, and ice caps in the form

of water. Nearly 89 percent of the weight of water is oxygen. Oxygen is also the most

abundant element in the Earth's crust. Its abundance is estimated at about 45 percent in

the earth.

83

Oxygen also reacts with many compounds. Combustion is one of the

examples, that is, it helps other compounds to burn. Another is oxidation. From

the term itself, it is the addition of oxygen to a compound yielding another kind of

compound.

The process of oxidation of acrolein to form acrylic acid was done with the

aid of a catalyst. The best suited catalyst used is a multi-metal oxide which in the

case of this process is the vanadium-molybdenum oxide catalyst.

Oxygen occurs in all kinds of minerals. Some common examples include

the oxides, carbonates, nitrates, sulfates, and phosphates. Oxides are chemical

compounds that contain oxygen and one other element. Calcium oxide, or lime or

quicklime (CaO), is an example. Carbonates are compounds that contain

oxygen, carbon, and at least one other element. Sodium carbonate, or soda, soda

ash, or sal soda (Na2CO3), is an example. It is often found in detergents and

cleaning products.

Nitrates, sulfates, and phosphates also contain oxygen and other elements.

The other elements in these compounds are nitrogen, sulfur, or phosphorus plus

one other element. Examples of these compounds are potassium nitrate, or

saltpeter (KNO3); magnesium sulfate, or Epsom salts (MgSO4); and calcium

phosphate (Ca3(PO4)2).

84

• Tungstated Zirconia Catalyst

Prieto discussed the effect of tungsten zirconia in his dissertation entitled

Optimization of the Dehydration of Glycerol to Acrolein and a Scale up in a Pilot

Plant.

“Tungsten zirconia materials are very attractive, environmentally friendly

solid acids. Although less active than their sulfate-promoted counterparts,

tungston zirconia catalysts offer inherent advantages over the former from the

standpoint of industrial application, such as higher stability under high-

temperature treatments, lower deactivation rates during catalysis, and easier

regeneration7. A minimum level of WOx is required to stabilize the tetragonal

phase of the zirconia support on annealing in air at high temperatures (typically

973 – 1173 K) needed to produce catalytically active materials. Iglesia and co-

workers reported that the acid activity of WOx-ZrO2 materials is a unique

function of the tungsten surface density rather than the W loading or calcinations

temperature independently. When this parameter is considered, a maximum in the

catalyst activity is found at intermediate values of the tungsten density. It has been

proposed that strong Brönsted acid sites responsible for the high catalytic activity

of WOx-ZrO2 develop on reduction of W+6 species in the presence of H2 or other

reductants, such alkanes or alcohols, to compensate the excess of negative charge

in the polyoxotungstated domains. These types of acid sites are termed temporary

acid sites, in opposition to the permanent acidity present in calcined WOx-ZrO2

85

samples. By themselves, the latter acid sites cannot account for the observed

catalytic activity. At tungsten coverages well below the monolayer, isolated

monotungstate species predominate on the zirconia surface. These species are

difficult to reduce and thus do not allow the formation of catalytically active

Brönsted acid sites. In contrast, highly reducible three-dimensional WO3

crystallites coexist with the two-dimensional amorphous polytungstates at

coverages exceeding the monolayer, resulting a decreasing accessibility to the

active WOx species. Thus, the occurrence of a maximum in the catalytic activity at

intermediate WOx surface densities represents a compromise between the

accessibility to the surface WOx species and their reducibility.”

Ulgen et al. Conversion of Glycerol to Acrolein in the Presence of

WO3/ZrO2 Catalysts discussed that “ZrO2 powder and WO3/ZrO2 pellets with 19

wt% WO3 were kindly provided by St. GobainNorpro, Ohio, USA. WO3/ZrO2

powders with five different WO3 contents (between 2.11 and 15.43 wt% WO3)

were obtained from Daiichi KKK, Japan, via Arkema CRRA, France. In these

cases there is nothing disclosed about the method of preparation. These Daichii

KKK catalysts were used without prior modification.”

“Several homemade catalysts have been prepared according to the

following impregnation method recipe, which was conducted under ambient

atmosphere. A certain amount of ammonium (para) tungstate (Sigma Aldrich,

Germany) and 200 mL of water were heated to 80°C and stirred 2 h, yielding a

86

clear solution. Into this solution, ZrO2 (Provided by St. Gobain/Norpro, Ohio,

USA) was added and stirred for another 4 h. After evaporation of the water, the

remaining slurry was placed in a ceramic bowl and dried 6 h at 110°C followed

by calcination at 600°C for 6 h. Both drying and calcination steps were conducted

in a box shaped programmable oven (Nabertherm N 7 with a Logotherm S 19

Program Controller, Tmax = 1,000°C) under ambient pressure and atmosphere

without addition of any gases.”

“The obtained powder was formed to pellets under 10 tons for 20 min,

which was then crushed and sieved. A fraction of 0.5–1.0 mm particle size was

used for the characterisation and screening experiments.”

Figueras, F. et al. Tungsten Catalyst with US Patent No. 2006/0091045

stated that “Zirconia oxide or zirconia (ZrO2) is a solid which used in catalysis.

Amongst the physical properties which make it suitable for this application is its

high melting point (3003 K), low thermal conductivity and high resistance to

corrosion by acids.”

“With regard to the chemical properties, zirconia is an amphoteric support,

as in alumina, that can be used in oxidation and reduction reactions.

Crystallization and sintering of the crystallites by means of calcination are not

desirable for use as a support.”

87

“Zirconia can be synthesized by various means, such as precipitation in an

aqueous solution of zirconium salts, such as ZrOCl3·8H2O,

ZrO(NO3)·2H2O,ZrCl4, or the sol-gel method.”

“Tungsten/Zirconia (W-ZrO2) catalysts have been known for some time

and provide an alternative to reactions which are catalyzed by means of acid sites.

The advantage which these solids have compared with sulphates is that they are

deactivated to a lesser extent. They have been describes by Hino and Arata as

strong acid catalysts. The definition as a superacid which was initially adopted

has been downgraded and it is now commonly accepted that they are strong acids

which are capable of isomerising linear paraffins into isoparaffins at

approximately 523 K. Since the acid sites have not been able to be identified, these

solids are characterized by a chemical composition and a method of preparation.”

88

• Vanadium-Molybdenum Oxide Catalyst

Josef Tichy in his work entitled, Oxidation of Acrolein to Acrylic acid over

Vanadium-Molybdenum Oxide Catalysts accounted that,

“The first reports published in scientific literature which claim the

advantages of vanadium-molybdenum oxide catalysts in the oxidation of acrolein

to acrylic acid are due to Kitahara et al. [1,2]. The authors undertook extensive

research into the catalyst pre-treatment, the weight ratio of constituents, type of

support, magnitude of particles, amount of the active components coated, and the

way of preparation. On the basis of the results obtained they chose as the most

favorable catalyst one containing the components MoO3, V205, and Al203 in the

molar ratio of 8:1:0.4 coated on spongy aluminum with a 17.8 wt% content of the

active constituents. With the acrolein concentration of 3.4 vol%, molar ratio of

oxygen to acrolein equal to 1.65, that of water to acrolein equal to 16.5, the time

factor of 1.64 s, and the temperature of 573 K it was possible to achieve the

acrolein conversion degree of 97.3% and the yield of acrylic acid equal to 85.7%

with the catalyst mentioned. According to the author’s experience, the optimum

oxidation degree of the catalytically effective components was attained when the

catalyst was preliminarily exposed to action of air at temperature of 573 K and

finally stabilized in reduction atmosphere by action of the starting reaction

mixture at 673 K.”

89

“With the aim of improving the properties of vanadium-molybdenum oxide

catalyst and shortening the lengthy process necessary for establishing the

stationary state, the paper [3] suggests the use of ethylenediamine as the reducing

agent directly in its preparation, using SiO2 in the form of aerosil for the support.

The preparation started from two solutions, namely

hexaammoniumheptamolybdate solution and ammonium vanadate solution with

three fold molar amount of ethylenediamine with respect to vanadium. The

solutions were mixed and aerosol was added thereto. The suspension thus

obtained was concentrated at 353 K to give a paste. For perfect homogeneity it is

recommended to use a spray drier. Calcination at 453 K and annealing in air at

573 K gave the optimum catalyst with the molar ratio of Mo:V = 5:1 and with the

content of active constituent on support equal to 30 wt.%. With the catalyst thus

prepared it was possible to obtain 100% conversion of acrolein and 96% yield of

acrylic acid from a gaseous mixture of the following composition (vol%): acrolein

4, oxygen 6.6, steam 25, and nitrogen 64.4. Oxides of carbon and CH3COOH

being determined as the reaction side products. The catalyst specific surface

determined by the BET method from nitrogen adsorption was 57 m2g-1. The

catalyst is blue in color, and amorphous according to the X-ray diffraction. The

crystallization takes place at temperatures above 600 K, but it is accompanied by

a color change to yellow and a substantial loss of activity due to the oxidation of

V4+ to V5+.”

90

• Ethyl Alcohol

Ethanol is miscible (mixable) in all proportions with water and with most

organic solvents. It is useful as a solvent for many substances and in making

perfumes, paints, lacquer, and explosives. Alcoholic solutions of non-volatile

substances are called tinctures; if the solute is volatile, the solution is called a

spirit.

Commercial Alcohols have grown to be the largest manufacturer and

supplier of industrial grade alcohol (ethyl alcohol or ethanol). The uses of the

product include industrial applications (such as solvents, detergents, paints,

printing inks, photo-chemical applications, latex processing, dyes, etc.), the

beverage market, medicinal, pharmaceutical and food products.

Because of ethanol's ease of production and because exposure to low

amounts does negligible harm, it has widespread use as a solvent for substances

intended for human contact or consumption, including scents, flavorings,

colorings, and medicines. In chemistry it is both an essential solvent and a

feedstock for the synthesis of other products. Because it burns cleanly, ethanol has

a long history as a fuel, including as a fuel for internal combustion engines.

“Under acid-catalyzed conditions, ethanol reacts with carboxylic acids to

produce ethyl esters and water:”

RCOOH + HOCH2CH3 → RCOOCH2CH3 + H2O

http://www.chemeurope.com/en/encyclopedia/Carboxylic_acid.html

http://www.chemeurope.com/en/encyclopedia/Ester.html

http://www.chemeurope.com/en/encyclopedia/Carboxylic_acid.html

http://www.chemeurope.com/en/encyclopedia/Ester.html

91

“For this reaction to produce useful yields it is necessary to remove water

from the reaction mixture as it is formed.”

“Ethanol can also form esters with inorganic acids. Diethyl sulfate and

triethyl phosphate, prepared by reacting ethanol with sulfuric and phosphoric

acid respectively, are both useful ethylating agents in organic synthesis. Ethyl

nitrite, prepared from the reaction of ethanol with sodium nitrite and sulfuric acid,

was formerly a widely-used diuretic.”

(http://www.chemeurope.com/en/encyclopedia/Ethanol.html)

As a reactive chemical, ethanol in common with all alcohols reacts with

acids to produce esters. Examples include ethyl acrylate, which is used as a

reactive diluent in specialised coatings, and ethyl acetate, which is a widely used

solvent in paint and coating formulations. Ethanol is used in the production of

ethylamines, which in turn are reactive industrial chemicals used in downstream

speciality applications including agrochemicals and pharmaceuticals. It can also be

used to make ethoxypropanol, an increasingly used glycol ether solvent in coating

formulations (CEFIC, 2003).

“The relationship of the introduced amounts of acrylic acid and alcohol in

reference to the reboiler content, depends, in general, upon the available

equipment, the amount of the sulfuric acid in the reboiler, and the esterification

temperature.”


http://www.chemeurope.com/en/encyclopedia/Phosphoric_acid.html


http://www.chemeurope.com/en/encyclopedia/Organic_synthesis.html

http://www.chemeurope.com/en/encyclopedia/Sodium_nitrite.html


http://www.chemeurope.com/en/encyclopedia/Diuretic.html

92

“Esterification of acrylic acid with the necessary amount of ethanol can,

for example, be conducted by adding from one half to twice the amount of acrylic

acid, based on the weight of the reboiler content, when employing about 20% by

weight of p-toluene sulfonic acid in the reboiler, which is at a temperature of 140°

and at a pressure of 760 mmHg.” (US Patent No.3458561)

According the the “Method of Producing Ethyl Acrylate”

(US2005/0107629), the invention relates to a method for combining acrylic acid

(AA) and ethanol, and processing the reaction products to produce ethyl acrylate

(EA).

“Feeding to the esterification reactor acrylic acid and ethanol, in a molar

ratio of from 1 to 1.1 to 1.5, and the acid catalyst; wherein at least a portion of the

acrylic acid is derived from a bottoms stream from a crude acrylic acid distillation

column, said bottoms stream comprising from 60 to 90% acrylic acid.”

93

• Sulfuric Acid

Sulfuric acid, H2SO4, is a strong mineral acid. It is soluble in water at all

concentrations. It was once known as oil of vitriol. Sulfuric acid has many

applications, and is one of the top products of the chemical industry. Principal uses

include ore processing, fertilizer manufacturing, oil refining, wastewater

processing, and chemical synthesis.

“Sulfuric acid is a very important commodity chemical, and indeed, a

nation's sulfuric acid production is a good indicator of its industrial strength. The

major use (60% of total production worldwide) for sulfuric acid is in the "wet

method" for the production of phosphoric acid, used for manufacture

of phosphate fertilizers as well as trisodium phosphate for detergents.”

“Sulfuric acid is used for a variety of other purposes in the chemical

industry. For example, it is the usual acid catalyst for the conversion of

cyclohexanoneoxime to caprolactam, used for making nylon. It is used for

making hydrochloric acid from salt via the Mannheim process.”

(http://www.chemeurope.com/en/encyclopedia/Sulfuric_acid.html)

Conversion of carboxylic acid and an alcohol to form its corresponding

ester is done with the presence of an acidic catalyst. Usually, sulfuric acid is used

as a catalyst in the esterification process.

http://www.chemeurope.com/en/encyclopedia/Hydrogen.html

http://www.chemeurope.com/en/encyclopedia/Sulfur.html

http://www.chemeurope.com/en/encyclopedia/Sulfur.html

http://www.chemeurope.com/en/encyclopedia/Chemical_industry.html

http://www.chemeurope.com/en/encyclopedia/Fertilizer.html

http://www.chemeurope.com/en/encyclopedia/Oil_refinery.html

http://www.chemeurope.com/en/encyclopedia/Wastewater_processing.html

http://www.chemeurope.com/en/encyclopedia/Wastewater_processing.html

http://www.chemeurope.com/en/encyclopedia/Chemical_synthesis.html


http://www.chemeurope.com/en/encyclopedia/Phosphate.html

http://www.chemeurope.com/en/encyclopedia/Fertilizer.html

http://www.chemeurope.com/en/encyclopedia/Trisodium_phosphate.html

http://www.chemeurope.com/en/encyclopedia/Nylon.html

http://www.chemeurope.com/en/encyclopedia/Hydrochloric_acid.html

http://www.chemeurope.com/en/encyclopedia/Salt.html


94

“Esterification of acrylic acid is possible in a liquid as well as in a gas

phase. Of primary importance as an esterification catalyst is sulfuric acid and/or

a sulfonic acid, e.g., p-toluene sulfonic acid. In respect to the amount at which

these catalysts have been utilized, German Patent No. 1,006,843 and published

German Patent application No. 1,161,259 teach, for example, that the catalyst

should be used in amounts such as about 0.01% sulfuric acid per mole acrylic

acid.” (US Patent No.3458561)

The sulfuric acid is employed in an amount sufficient to both catalyze the

reaction and to serve as a dehydrating agent or desiccant for the by-product water.

Accordingly, the sulfuric acid should be employed in an amount greater than about

0.05 moles per mole of carboxylic acid to be esterified and preferably above 0.1

moles and of sulfuric acid per mole of carboxylic acid, which is sufficient to both

catalyze the dehydrate the water. Most desirably, from about 0.1 to about 0.5

moles of sulfuric acid and most preferably about 0.2 moles will be employed per

mol of carboxylic acid. The reaction is carried out at elevated temperatures,

conveniently reflux conditions. With methanol as the alcohol and a carboxylic acid

having from about 6 to about 22 carbon atoms a temperature will be on the order

of about 70° to about 100° C. However, temperatures on the order at about 40° to

about 120° C. and more preferably 60° to about 80° C. will be employed. The

specific temperature employed will be determined however by the specific alcohol

employed and specific carboxylic acid to be esterified. In the laboratory reflux

95

periods of about 1 to 2 hours were sufficient to provide yields of methyl

isooctanoate in the methanol esterification of isooctanoic acid employing about

1.5 to about 2 moles of methanol per mole of isooctanoic acid which provided the

ester of greater than 99% purity. In contrast, in reactions not using an excess

of sulfuric acid (only a catalytic amount) time periods of reflux of about 10 hours

or more were required to provide about an 80% yield of ester of lower purity even

with a seven molar excess of methanol. Again, the reaction period will depend on

the specific alcohol employed and specific acid to be esterified. Generally reaction

periods will not need to exceed about 4 hours and the reaction will be complete

(about 90% yield) usually within 1 to about 3 hours employing the preferred levels

of carboxylic acid, alcohol and sulfuric acid. After completion of

the esterification the sulfuric acid layer is removed and any unesterified acid is

removed as the sodium salt by an alkaline aqueous wash. The ester may be dried

by azeotropic distillation with an aliphatic hydrocarbon solvent such as heptane.

The unreacted carboxylic acid in the aqueous alkaline wash can be recovered by

acidification with an acid, preferably spent sulfuric acid, from

the esterification step.

It has now been discovered that the use of a significant excess

of sulfuric acid in the reaction provides unexpectedly high yields of the desired

ester and the ester is of high purity. The sulfuric acid not only acts as a catalyst for

the reaction but the excess acid further unites with, dessicates, removes or

96

immobilizes the water of reaction by forming a second phase, resulting in an

increased yield of the ester, in excess of 90% of the acid being converted to the

ester. The ester further is of high purity of about 99%. While the present invention

is applicable to any esterification of a carboxylic acid with an alcohol, it is of

particular interest to the esterification of longer chain carboxylic acids such as the

branched acids having about 6 to about 22 carbon atoms with lower alkyl alcohols

containing from 1 to about 4 carbon atoms, which esters may be subsequently

converted to diketones which are useful as metal extractants.

97

D. DESIGN AND EQUIPMENT LITERATURE

• Fixed-Bed Catalytic Reactor

Synthesis of glycerol to acrolein may take place in a fixed bed reactor,

fluidized bed or moving fluidized bed reactor, or in a modular configuration.

Among the following reactors, fixed-bed or packed-bed reactor is the most

appropriate to use.

“A fixed-bed reactor typically is a cylindrical vessel that is uniformly

packed with catalyst pellets. Non-uniform packing of catalyst may cause

channeling that could lead to poor heat transfer, poor conversion, and catalyst

deactivation due to hot spots. The bed is loaded by pouring and manually packing

the catalyst or by sock loading. As discussed earlier, catalysts may be regular or

shaped porous supports, uniformly impregnated with the catalytic ingredient or

containing a thin external shell of catalyst. Catalyst pellet sizes usually are in the

range of 0.1 to 1.0 cm (0.039 to 0.39 in).” (Perry’s Chemical Engineer’s

Handbook 8th Edition)

“Packed-bed reactors are easy to design and operate. The reactor typically

contains a manhole for vessel entry and openings at the top and bottom for

loading and unloading catalyst, respectively. A metal support grid is placed near

the bottom, and screens are placed over the grid to support the catalyst and

prevent the particles from passing through. In some cases, inert ceramic balls are

98

placed above and below the catalyst bed to distribute the feed uniformly and to

prevent the catalyst from passing through, respectively. One has to guard the bed

from sudden pressure surges as they can disturb the packing and cause

maldistribution and bypassing of feed.” (Perry’s Chemical Engineer’s Handbook

8th Edition)

There are two basic types of fixed-bed reactors: those in which the solid is a

reactant and those in which the solid is a catalyst. Many examples of the first type

can be found in the extractive metallurgical industries.

In the chemical process industries, the designer will normally be concerned

with the second type: catalytic reactors. Industrial fixed-bed catalytic reactors

range in size from small tubes, a few centimeters diameter, to large-diameter

packed beds. Fixed-bed reactors are used for gas and gas-liquid reactions. Heat

transfer rates in large-diameter packed beds are poor, and where high heat transfer

rates are required, fluidized beds should be considered.

Fixed-bed reactors for industrial syntheses are generally operated in a

stationary mode over prolonged production runs, and design therefore concentrates

on achieving an optimum stationary operation. According to several experiments

that had been conducted (Deleplanque, J. et al. and US Patent 5264625), most of

them uses vertical fixed-bed reactor.

99

Ullman reported that the “Stability, dynamics, and control of fixed-bed

reactors with strongly exothermic reactions has been studied in great detail since

the early 1970s. The numerous publications could give the impression that this is a

particular critical reactor type with a large potential risk. In fact, the opposite is

true. Compared to a liquid-phase reactor of the same size, a fixed-bed reactor

with a gas-phase reaction contains a mass of reactants several orders of

magnitude smaller. There is therefore no danger of runaway exothermic reaction

due to reactants accumulating in the reactor, especially as the heat capacity of the

catalyst mass additionally damps the uncontrolled temperature rise.”

“Nevertheless, instabilities can arise in fixed-bed reactors, particularly

with strong exothermic reactions, and can lead to excess temperature that can

damage the catalyst and the reactor construction materials.”

“Fixed-bed reactors for industrial syntheses are generally operated over a

long production period with almost constant operating parameters. The task of

process control engineering is simply to keep these parameters optimal. In

contrast, for supply or disposal plants that have several users or suppliers in the

production network, there are frequent changes of feed material and throughput

which require fast, automatic reaction control. Examples are fixed-bed reactors

for synthesis gas production or off-gas treatment.”

US Patent 2010/0204502 A1 “The process according to the invention may

be carried out in the gas phase or in the liquid phase, preferably in the gas phase.

100

When the dehydration reaction is carried out in the gas phase, various process

technologies may be used, namely fixed-bed process, fluidized-bed process or

circulating fluidized-bed process. The dehydration of glycerol may also be carried

out in the liquid phase in a conventional reactor for a liquid phase reaction, but

also in a catalytic distillation type reactor. The contact time is the ratio of the

volume of the catalyst bed to the volume of gaseous reactants conveyed per

second. The average temperature and pressure conditions in a bed may vary

depending on the nature of the catalyst, the nature of the catalyst bed and the size

of the catalyst. It is possible to use, as the support, any material such as silica,

alumina, titanium oxide, silicon carbide, silica/alumina mixture, silicates, borates

or carbonates on condition that these products are stable under the reaction

condition to which the catalyst will be subjected.”

Sabater Prieto Sergio reported that the “The design of the reactor consists

in the determination of the appropriate dimensions to carry out the dehydration of

glycerol in a large scale. In practice, it is necessary to carry out the determination

of the catalytic volume, which will be placed in the reactor.”

“Therefore, it is necessary to know the dimensions of the catalytic fix-bed

for the pilot scale apparatus before the determination of the reactor dimensions. It

is necessary to know the behaviour of the reaction in the lab scale apparatus. In

this way, the glycerol conversion is the main factor, as well as, the glycerol

solution flow.”

101

“By plotting the glycerol conversion versus the ratio, volume of catalyst /

pure glycerol flow, a curve was obtained. At high conversion increases, until it

reaches a 100% conversion.”

“The objective of this curve is to determine the break point, when the

glycerol conversion reaches 100%. At this point of conversion, there is a ratio,

volume of catalyst/glycerol flow (Vcat/Fglycerol). By choosing a certain scale up

factor for the production, which means, a scale factor, for pumped glycerol, the

catalytic volume for the scale up can be calculated. It can be observed that the

break point for the glycerol conversion is found approximately at a Vcat/Fglycerol =

0.5 – 0.6. This is the smallest ratio, or in other words, the highest feed flow for a

constant catalytic bed, which can be used to obtain a 100% glycerol conversion.”

102

• Multitubular Fixed-Bed Catalytic Reactor

Catalytic fixed-bed reactors are the most important type of reactor for the

synthesis of large scale basis chemicals. In these reactors, the reaction take place

in the form of a heterogeneous catalyzed gas reaction on the surface of catalysts

that are arranged as so-called fixed bed in the reactor.

Oxidation process can be operated using a multitubular fixed-bed catalytic

reactor. Advantages of using multitubular fixed-bed are that it is easy scalability

and preferably employed for large-scale industrial implementations. According to

Perry’s Chemical Engineer’s Handbook (R. Perry and D. Green), multitubular

reactor are designed for highly endothermic reactors because it allows uniform

distribution of heat.

“As discussed earlier, heat management is an important issue in the design

of fixed-bed reactors. A series of adiabatic fixed beds with interbed cooling

(heating) may be used. For very highly exothermic (endothermic) reactions, a

multitubular reactor with catalyst packed inside the tubes and cooling (heating)

fluids on the shell side may be used. The tube diameter is typically greater than 8

times the diameter of the pellets (to minimize flow channeling), and the length is

limited by allowable pressure drop. The heat transfer required per volume of

catalyst may impose an upper limit on diameter as well. Multitubular reactors

require special procedures for catalyst loading that charge the same amount of

catalyst to each tube at a definite rate to ensure uniform loading, which in turn

103

ensures uniform flow distribution from the common header. After filling, each tube

is checked for pressure drop. In addition to the high surface area for heat

transfer/volume, the advantage of a multitubular fixed-bed reactor is its easy

scalability. A bench-scale unit can be a full-size single tube, a pilot plant can be

several dozen tubes, and a large-scale commercial reactor can have thousands of

tubes. Disadvantages include high cost and a limit on maximum size (tube length

and diameter, and number of tubes).”

According to Ullmans’ Processes and Process Engineering, the features of

this kind of reactor include temperature control with liquid or gaseous fluid n the

shell side space to improve heat transfer. Also this kind of reactor is practical in

the production of acrylic acid from acrolein. Reactions that are extremely

temperature-sensitive are carried out in reactors in which indirect heat exchange

occurs via a circulating heat transfer medium integrated in the fixed bed. The most

common arrangement is the multitubular fixed-bed reactor, in which the catalyst is

arranged in the tubes and the heat carrier circulates externally around the tubes.

The development of reactors in which the heat exchange surfaces are

integrated in the fixed bed to supply or remove the heat of reaction as close as

possible to the reaction site occurred in parallel with the development of

multistage adiabatic reactors with intermediate heating or cooling.

Ullman reported that the “multitubular fixed-bed reactor constitutes the

oldest and still predominant representative of the class of fixed-bed reactors. Here

104

the catalyst packing is located in the individual tubes of the tube bundle. The heat

transfer medium is circulated around the tube bundle and through an external

heat exchanger, in which the heat of reaction is supplied or removed. Whereas

with endothermic reactions, circulating gas can be used as heat transfer medium,

for strongly exothermic reactions exclusively liquid or boiling heat transfer

medium are used. Only in this way can the catalyst temperature be held in the

narrow temperature range necessary for selective reaction control.”

“Initially, the integration of heat exchange in the fixed bed was utilized to

ensure as isothermal a reaction control as possible, which is why the reactors of

this type are commonly termed “isothermal reactors”. They are characterized by

reaction tubes of 20-80 mm internal diameter and a carefully designed flow

control of the liquid heat transfer medium, with largely constant heat transfer

conditions throughout the tube bundle and maximum temperature changes of the

heat transfer medium in the tube bundle of a few degrees.”

“Because of the small mass storage capacity compared to liquid-phase

reactors, the danger of sudden reaction of accumulated reactants in gas-phase

multitube fixed-bed reactors is low. Leaving out the peculiarities of individual

cases, the following safety risk can be assumed for fixed-bed reactors:”

1. “Leaks which result in the release of large amounts of gas or vapour and

the formation of explosive clouds.

105

2. Leaks resulting in release of large amounts of liquid heat transfer media

(oils, salt melts).

3. Occurrence of ignitable or decomposable gas mixtures in the reactor.

4. Melting of the reactor due to a runaway reaction.”

According to US Patent No. 5264625, the process for the catalytic gas-

phase oxidation of acrolein to acrylic acid is suited using a multitubular fixed-bed

catalytic reactor.

“It is an object of the present invention to provide a process for the

catalytic gas-phase oxidation of acrolein to acrylic acid in a fixed-bed reactor

having contacting tubes, at elevated temperature on catalytically active oxides

with a conversion of acrolein for a single pass of ≥ 95%, which has a reaction

temperature program which is improved with respect to increased selectivity of

formation of acrylic acid”

“We have found that this object is achieved by a process for the catalytic

gas-phase oxidation of acrolein to acrylic acid in a fixed-bed reactor with

contacting tubes, at elevated temperature on catalytically active oxides with a

conversion of acrolein for a single pass of ≥ 95%, wherein the reaction



reactants enter the contacting tubes is from 260° to 300°C until an acrolein

106

conversion of from 20 to 40% is reached, and the reaction temperature is

subsequently reduced by a total of from 5° to 40°C, abruptly or successively in

steps or continuously along the contacting tubes until an acrolein conversion of a

≥ 95% has been reached, with the proviso that the reaction temperature in this

second reaction zone is not lower than 240°C.”

The use of multitubular fixed-bed reactor was also recommended in the

invention entitled “Catalytic Gas-Phase Oxidation of Acrolein to Acrylic Acid”

(US Patent No. 5739391). As stated in their invention,

“We have found theta this object is achieved by a process for the catalytic

gas-phase oxidation of acrolein to acrylic acid in a multiple contact tube fixed-bed

reactor through whose space surrounding the contact tubes only one heat-

exchange medium circuit is passed, at elevated temperature on catalytically active

multi-metal oxides with an acrolein conversion for a single pass of ≥ 95 mole%

and an acrylic formation selectivity of ≥ 90 mol%, which comprises firstly passing

the heat-exchange medium through the multiple contact tube fixed-bed reactor”

107

• Batch Stirred Tank Reactor

The batch reactor has the advantage of small instrumentation cost and

flexibility of operation (may be shut down easily and quickly). It has the

disadvantage of high labor and handling cost, often considerable shutdown time to

empty, clean out, and refill, and poorer quality control of the product. Hence we

may generalize to state that the batch reactor is well suited to produce small

amounts of material and to produce many different products from one piece of

equipment. On the other hand, for the chemical treatment of materials in large

amounts the continuous process is nearly always found to be more economical.

In the batch reactor, the reactants are initially charged into a container, are

well mixed, and are left to react for a certain period. The resultant mixture is then

discharged. This is an unsteady-state operation where composition changes with

time; however, at any instant the composition throughout the reactor is uniform.

“Stirred tanks are common gas-liquid reactors. Reaction requirements

dictate whether the gas and liquid are in a batch or continuous mode. For a

liquid-phase reaction with a long time constant, a batch mode may be used. The

reactor is filled with liquid, and gas is continuously fed into the reactor to

maintain pressure. If by-product gases form, these gases may need to be purged

continuously. If gas solubility is limiting, a higher-purity gas may be continuously

fed (and, if required, recycled). As the liquid residence time decreases, product

108

may be continuously removed as well.” (Perry’s Chemical Engineer’s Handbook

8th Edition)

“A basic stirred tank design is shown in Fig. 19-30. Height/diameter ratio

is H/D = 1 to 3. Heat transfer may be provided through a jacket or internal coils.

Baffles prevent movement of the mass as a whole. A draft tube can enhance

vertical circulation. The vapor space is about 20 percent of the total volume. A

hollow shaft and impeller increase gas circulation by entraining the gas from the

vapor space into the liquid. A splasher can be attached to the shaft at the liquid

surface to improve entrainment of gas. A variety of impellers is in use. The pitched

propeller moves the liquid axially, the flat blade moves it radially, and inclined

blades move it both axially and radially.” (Perry’s Chemical Engineer’s

Handbook 8th Edition)

“Gases may be dispersed in liquids by spargers or nozzles. However, more

intensive dispersion and redispersion are obtained by mechanical agitation. The

gas is typically injected at the point of greatest turbulence near the injector tip.

Agitation also provides the heat transfer and, if needed, keeps catalyst particles

(in a three-phase or slurry reactor) in suspension. Power inputs of 0.6 to 2.0

kW/m3 (3.05 to 10.15 hp/1000 gal) are suitable. Bubble sizes depend on agitation

as well as on the physical properties of the liquid. They tend to be greater than a

minimum size regardless of power input due to coalescence.” (Perry’s Chemical

Engineer’s Handbook 8th Edition)

109

“The reactor may be modeled as two ideal reactors, one for each phase,

with mass transfer between the phases. For example, if the gas has limited

solubility and is sparged through a liquid, the gas may be modeled as a PFR and

the liquid as a CSTR. Mass-transfer coefficients vary, e.g., as the 0.7 exponent on

the power input per unit volume (with the dimensions of the vessel and impeller

and the superficial gas velocity as additional factors).” (Perry’s Chemical

Engineer’s Handbook 8th Edition)

In esterification reactions, a batch reactor equipped with four baffles and a

six-bladed turbine impeller is used according to the Biochemical Engineering

Journal 41 (2008) 87–94 by G.N. Kraai et al.

Batch reactors are used widely in industry at all scales. Batch reactors are

tanks, commonly provided with agitation and a method of heat transfer (usually by

coils or external jacket). This type of reactor is primarily employed for relatively

slow reactions of several hours duration, since the downtime for filling and

emptying large equipment can be significant. Agitation is used to maintain

homogeneity and to improve heat transfer. Since residence time is uniform, a

batch reactor is preferred for better yields and to obtain a higher selectivity.

A “batch” of reactants is introduced into the reactor operated at the desired

conditions until the target conversion is reached. Batch reactors are typically tanks

in which stirring of the reactants is achieved using internal impellers, gas bubbles,

or a pump around loop where a fraction of the reactants is removed and externally

110

recirculated back to the reactor. Temperature is regulated via internal cooling

surfaces (such as coils or tubes), jackets, reflux condensers, or pump-around loop

that passes through an exchanger. Batch processes are suited to small production

rates, to long reaction times, to achieve desired selectivity, and for flexibility in

campaigning different products.

Stirred tank (agitated) reactors consist of a tank fitted with a mechanical

agitator and a cooling jacket or coils. They are operated as batch reactors or

continuously. Several reactors may be used in series. The stirred tank reactor can

be considered the basic chemical reactor, modelling on a large scale the

conventional laboratory flask. Tank sizes range from a few liters to several

thousand liters. They are used for homogeneous and heterogeneous liquid-liquid

and liquid-gas reactions, and for reactions that involve finely suspended solids,

which are held in suspension by the agitation. As the degree of agitation is under

the designer’s control, stirred tank reactors are particularly suitable for reactions

where good mass transfer or heat transfer is required.

When operated as a continuous process, the composition in the reactor is

constant and the same as the product stream, and, except for very rapid reactions,

this will limit the conversion that can be obtained in one stage.

The power requirements for agitation will depend on the degree of agitation

required and will range from about 0.2 kW/m3 for moderate mixing to 2 kW/m3

for intense mixing.

111

According to US Patent 20050107629 and US5324853 – Method for

producing Ethyl Acrylate: In producing ethyl acrylate and for recovering acrylic

acid, ethyl acrylate, ethanol and water from an esterification reactor mixture

containing acrylic acid, ethyl acrylate, ethanol, water, heavy ends, and acid

catalyst; the reaction vessel includes a mixing means which is capable of internally

recirculating at least 2.5 volumes of reactor liquid per minute. The said mixing

means comprising a reactor impeller and at least one baffle disposed about the side

wall of the reaction vessel. The mixing means further comprises a draft tube

disposed about the impeller. This draft tube is formed from either a flat sheet or

heat coils. The reactor impeller is capable of minimizing the internal recirculation

of said reaction mixture such that said reaction mixture from said lower region of

said reaction vessel is recirculated to said upper region before it returns to said

reactor impeller. The reaction vessel has a height to diameter ratio of less than 1.4.

The reactor impeller is either a pitched blade turbine or a hydrofoil type turbine.

Each baffle has a width greater than 1/12th of the diameter of reaction vessel;

whereby each baffle aids in minimizing surface turbulence and vortexing.

112

• Shell and Tube Heat Exchanger

“If larger flows are involved, a shell and tube exchanger is used, which is

the most important type of exchanger in use in the process industries. In these

exchangers the flow is continuous. Many tubes in parallel are used where one

fluid flows inside these tubes. The tubes, are arranged in a bundle, are enclosed in

a single shell and the other fluid flows outside the tubes in the shell side. The

simplest shell and tube exchanger is a 1 shell pass and 1 tube pass, or a 1-1

counterflow exchanger. The cold fluid enters and flows inside through all the

tubes in parallel in one pass. The hot fluid enters at the other end and flows

counterflow across the outside of the tubes. Cross baffles are used so that the fluid

is forced to flow perpendicular across the tube bank rather than parallel with it.

This added turbulence generated by this cross flow increases the shell-side heat-

transfer coefficient.” (Transport Processes and Unit Operations by C. Geankoplis,

3rd edition)

113

Shown above is a bundle of small-diameter tubes which are arranged

parallel to each other and reside inside a much larger-diameter tube called the

“shell”. The tubes are all manifold together at other end so that the “tube fluid”

enters the left side and is distributed equally among the tubes. At the right side, the

fluid exits from each tube, is mixed together in a second manifold, and then leaves

as a single stream. The second fluid, called the “shell fluid” flows in the space in

between the outside of tube. Baffle plates inside the shell force the shell fluid to

flow across the tubes repeatedly as the fluid moves along the length of the shell.

The shell and tube exchanger is by far the most common type of heat

transfer equipment used in the chemical and allied industries. The advantages of

this type are as follows:

1. The configuration gives a large surface area in a small volume;

2. Good mechanical layout: a good shape for pressure operation;

3. Uses well-established fabrication techniques;

4. Can be constructed from a wide range of materials;

5. Easily cleaned;

6. Well-established design procedures.

Essentially, a shell and tube exchanger consists of a bundle of tubes

enclosed in a cylindrical shell. The ends of the tubes are fitted into tube sheets,

which separate the shell-side and tube-side fluids. Baffles are provided in the shell

to direct the fluid flow and support the tubes.

114

The bundle of tubes in a shell and tube heat exchanger can be stacked in

one of the two different ways

The use of triangular pitch allows the tubes to be more tightly packed -

more tubes and therefore more area per unit volume of shell. This makes the shell

cheaper. On the other hand, the square pitch has the advantage that it is easier to

clean.

As described in the chapter 15: Heat-Exchange Equipment of Unit

Operations of Chemical Engineering, 6th ed. by McCabe W. et al.

“In an exchanger, the shell-side and tube-side heat transfer coefficients are

of comparable importance, and both must be large if a satisfactory overall

coefficient is to be attained. The velocity and turbulence of the shell-side liquid are

as important as those of the tube-side fluid. To promote crossflow and raise the

average velocity of the shell-side fluid, baffles are installed in the shell. In

construction, common practice is to cut away a segment having a height equal to

one-fourth the inside diameter of the shell. Such baffles are called 25 percent

baffles. The baffles are perforated to receive the tubes. To minimize leakage, the

clearances between baffles and shell and tubes should be small. The baffles are

115

supported by one or more guide rods, which are fastened between the tube sheets

by setscrews. To fix the baffles in place, short sections of tube are slipped over the

rod between the baffles. In assembling such an exchanger, it is necessary to do the

tube sheets, support rods, spacers, and baffles first and then to install the tubes.

The stuffing box provides for an expansion. This construction is practicable only

for small shells.”

“Shell diameters are standardized. For shells up to and including 23 in. the

diameters are fixed in accordance with the American Society for Testing and

Materials (ASTM) pipe standards. These shells are constructed of rolled plate.”

“The distance between the baffles (center to center) is the baffle pitch, or

baffle spacing. It should not be less than one-fifth the diameter of the shell or more

than the inside diameter of the shell”.

“Tubes are usually attached to the tube sheets by grooving the holes

circumferentially and rolling the tube ends into holes by means of a rotating

tapered mandrel, which stresses the metal of the tube beyond the elastic limit, so

the metal flows into the grooves. In high-pressure exchangers, the tubes are

welded or brazed to the tube sheet after rolling.”

116

• Tray Tower Absorption Column

Absorption is a process that refers to the transfer of a gaseous pollutant

from a gas phase to a liquid phase. The absorption process can be categorized as

physical or chemical. Physical absorption occurs when the absorbed compound

dissolves in the liquid; chemical absorption occurs when the absorbed compound

and the liquid react. Liquids commonly used as solvents include water, mineral

oils, non-volatile hydrocarbon oils, and aqueous solutions.

Gas absorbers are most often used to remove soluble inorganic

contaminants from an air stream. The design of an absorber used to reduce

117

gaseous pollutants from process exhaust streams involves many factors including

the pollutant collection efficiency, pollutant solubility in the absorbing liquid,

liquid-to-gas ratio, exhaust flow rate, pressure drop, and many construction details

of the absorbers such as packing, plates, liquid distributors, entrainment

separators, and corrosion-resistant materials.

In absorption, mass transfer of the gaseous pollutant into the liquid occurs

as a result of a concentration difference between the liquid and gas phase.

Absorption continues as long as a concentration difference exists where the

gaseous pollutant and liquid are not in equilibrium with each other. The

concentration difference depends on the solubility of the gaseous pollutant in the

liquid. Absorbers remove gaseous pollutants by dissolving them into a liquid

called the absorbent. In designing absorbers, optimum absorption efficiency can be

achieved by doing the following:

• Providing a large interfacial contact area

• Providing for good mixing between the gas and liquid phases

• Allowing sufficient residence, or contact, time between the phases

• Choosing a liquid in which the gaseous pollutant is very soluble

Solubility is a very important factor affecting the amount of a pollutant, or

solute that can be absorbed. Solubility is a function of both the temperature and, to

a lesser extent, the pressure of the system. As temperature increases, the amount of

118

gas that can be absorbed by a liquid decreases. From the ideal gas law: as

temperature increases, the volume of a gas also increases; therefore, at the higher

temperatures, less gas is absorbed due its larger volume. Pressure affects the

solubility of a gas in the opposite manner. By increasing the pressure of a system,

the amount of gas absorbed generally increases.

Solubility data are obtained at equilibrium conditions. This involves putting

measured amounts of a gas and a liquid into a closed vessel and allowing it to sit

for a period of time. Eventually, the amount of gas absorbed into the liquid will

equal the amount coming out of the solution. At this point, there is no net transfer

of mass to either phase, and the concentration of the gas in both the gaseous and

liquid phases remains constant. The gas-liquid system is at equilibrium.

Equilibrium conditions are important in operating an absorption tower. If

equilibrium were to be reached in the actual operation of an absorption tower, the

collection efficiency would fall to zero at that point since no net mass transfer

could occur. The equilibrium concentration, therefore, limits the amount of solute

that can be removed by absorption. The most common method of analyzing

solubility data is to use an equilibrium diagram. An equilibrium diagram is a plot

of the mole fraction of solute in the liquid phase, denoted as x, versus the mole

fraction of solute in the gas phase, denoted as y.

119

Under certain conditions, Henry’s law may also be used to express

equilibrium solubility of gas-liquid systems. Henry’s law is expressed as:

p = Hx

where: p = partial pressure of solute at equilibrium, Pa

x = mole fraction of solute in the liquid

H = Henry’s law constant, Pa/mole fraction

Henry’s law can be written in a more useful form bt dividing both equation

by the total pressure, PT, of the system. The left side of the equation becomes the

partial pressure divided the total pressure, which equals the mole fraction in the

gas phase, y. The equation will now become:

y = H’x

where: y = mole fraction of gas in equilibrium with liquid

H’ = Henry’s law constant, mole fraction in vapour per mole

fraction in liquid

x = mole fraction of the solute in equilibrium

The most widely used model for describing the absorption process is the

two-film, or double-resistance, theory, which was first proposed by Whitman in

1923. The model starts with the three-step mechanism of absorption. From this

mechanism, the rate of mass transfer was shown to depend on the rate of migration

120

of a molecule in either the gas or liquid phase. The two-film model starts by

assuming that the gas and liquid phases are in turbulent contact with each other,

separated by an interface area where they meet. This assumption may be correct,

but no mathematical expressions adequately describe the transport of a molecule

through both phases in turbulent motion.

Two-Film Theory

Therefore, the model proposes that a mass-transfer zone exists to include a

small portion (film) of the gas and liquid phases on either side of the interface. The

mass-transfer zone is comprised of two films, a gas film and a liquid film on their

respective sides of the interface. These films are assumed to flow in a laminar, or

121

streamline, motion. In laminar flow, molecular motion occurs by diffusion, and

can be categorized by mathematical expressions.

For gas absorption, the two devices most often used are the packed tower

and the plate tower. Both of these devices, if designed and operated properly, can

achieve high collection efficiencies for a wide variety of gases. Other scrubbing

systems can be used for absorption, but are limited to cases where the gases are

highly soluble. For example, spray towers, venturis, and cyclonic scrubbers are

designed assuming the performance is equivalent to one single equilibrium stage

(i.e., NOG = 1) (Perry 1973).

Tray towers and similar devices bring about stepwise contact of the liquid

and the gas and are therefore countercurrent multistage cascades. On each tray of a

sieve-tray tower, for example, the gas and liquid are brought into intimate contact

and separated and the tray thus constitutes a stage. It is convenient to use the

parallel flow as an arbitrary standard for design and for measurement of

performance of actual trays regardless of their method of operation. For this

purpose a theoretical, or ideal, tray is defined as one where the average

composition of all the gases leaving the tray is in equilibrium with the average

composition of all the liquid leaving the tray.

122

• Pervaporator

Pervaporation, in its simplest form, is an energy efficient combination of

membrane permeation and evaporation. It's considered an attractive alternative to

other separation methods for a variety of processes. For example, with the low

temperatures and pressures involved in pervaporation, it often has cost and

performance advantages for the separation of constant-boiling azeotropes.

Pervaporation is also used for the dehydration of organic solvents and the removal

of organics from aqueous streams.

In pervaporation, a multi-component liquid stream is passed across a

membrane that preferentially permeates one or more of the components. As the

feed liquid flows across the membrane surface, the preferentially permeated

components pass through the membrane and are removed as a permeate vapor.

Characteristics of the pervaporation process

The separation is carried out by running a feed stream of the liquid mixture

across a separation membrane under pervaporator conditions. By pervaporator

conditions, we mean that the vapor pressure of the component that it is desired to

123

separate into the permeate stream is maintained at a lower level on the permeate

side than on the feed side, and the pressure on the permeate side is such that the

permeate is in the gas phase as it emerges from the membrane. The process results,

therefore, in a permeate vapor stream enriched in the desired component and a

residue liquid stream depleted in that component.

In a first aspect, the process is carried out using multiple membrane

modules or elements arranged in series within a single tube, so that the residue

stream exiting the first module in the series forms the feed to the second module,

and so on, until the final or product residue stream is withdrawn from the last

module in the series.

To maintain adequate transmembrane flux, the feed solution under

treatment is heated within the tube as it passes from one module to the next. This

interstage heating or reheating is achieved by blocking the straight flow path from

the residue end of one module to the feed end of the next, and by heating the

outside surface of the tube. Instead of passing directly to the inlet of the next

module, the feed is directed in a flow path in the annular space between the inside

wall or surface of the tube and the outer casing or surface of the membrane

module that it has just exited. By forcing the stream to flow at least partially back

along the outside of the module, it is brought into heat exchanging contact with the

inside surface of the tube.

124

Simplified Pervaporation Process

The process divides the feed stream into a treated residue stream and a

permeate stream, either or both of which may be desired products of the process.

For example, if the feed solution is a dilute solution of ethanol in water, the

process of the invention may be used to form a more concentrated ethanol product

as the permeate stream. Likewise, if the feed solution is ethanol containing just a

few percent of water, the process of the invention may be used to dehydrate the

ethanol, forming a purified ethanol product as the residue stream.

The membrane modules or elements are housed in a tube. The tube serves

to house and support the membrane elements and provide a directed fluid flow. In

addition, the tube conducts heat to warm the feed solution as it passes along the

train of modules, and may provide a pressure-withstanding function if the pressure

125

conditions under which the separation process is carried out are substantially

different from the pressure outside the tube.

The outside of the tube may be heated in any appropriate manner.

Preferably, low grade steam is used if available.

The membrane used to perform the separation may be any type of

membrane capable of performing an appropriate separation under

pervaporation conditions. Suitable membranes include polymeric membranes,

inorganic membranes, such as ceramic membranes, and membranes containing

inorganic particles embedded in a polymeric matrix. For example, if the feed

solution is to be dehydrated, a hydrophilic membrane, such as a polyvinyl alcohol

membrane, may be used. If the feed solution is a mixture of olefins and paraffins,

a hydrophobic membrane, such as a fluorinated polyimide membrane, may be

used.

The membranes and modules may take any convenient cylindrical form,

such as flat sheets wound into spiral-wound modules, potted hollow fibers or

tubular membranes that will fit into the tube so as to leave an annular space

between the outer longitudinal surface of a membrane module and the inside

surface of the tube. The configuration of the process and apparatus of the

invention is not suitable for plate-and-frame modules, as these are usually

assembled in stacks, not housed in tubes or cylindrical pressure vessels.

126

The series includes at least two modules, and will typically include three,

four, five or six modules mounted end to end in the tube. The modules are

connected as described above such that a feed stream under treatment may enter

the feed end of the first module, flow through the modules in turn and exit as a

final residue stream from the residue end of the last module. The modules are also

connected by a permeate pipe or pipes, through which the collected permeate

stream from the series can flow.

The driving force for transmembrane permeation is the difference between

the vapor pressure of the feed liquid and the vapor pressure on the permeate side.

This pressure difference is generated at least in part by operating with the feed

liquid at above ambient temperature, usually above 30° C., and typically in the

range 30-120° C. Optionally, the permeate side may also be maintained under

vacuum to increase the driving force.

To heat the feed solution as it passes along the chain of modules, the feed

solution is prevented from flowing in a straight line immediately from the residue

end of one module to the feed of the next. Instead, the feed solution exiting the

residue end of a module is directed at least partially back along the outside of the

module it has just exited, into a reheating space or zone between the outer

longitudinal surface of that module and the inside surface of the tube. The reheated

residue solution is then directed out of the reheating space to the feed inlet end of

the next module.

127

Any solution that may be treated by pervaporation may be treated by the

process of the invention. Most commonly, the liquid to be treated will be a

solution of one or more organic components in water, or of water in an organic

solvent or solvent mixture, but solutions containing only organic or only inorganic

components may also be treated. Separation of aromatics from paraffins in an oil

refinery, removal of organic sulfur compounds from hydrocarbon mixtures,

dehydration of bioethanol, recovery of ethanol from fermentation broth, and

removal of volatile organic compounds (VOCs) from wastewater are typical

representative examples of separations in which the process of the invention can

be used to advantage.

The separation is carried out by running a feed stream of the liquid mixture

across a separation membrane under pervaporation conditions.

By pervaporation conditions, we mean that the vapor pressure of the component

that it is desired to separate into the permeate stream is maintained at a lower level

on the permeate side than on the feed side, and the pressure on the permeate side is

such that permeate is in the gas phase as it emerges from the membrane. The

process results, therefore, in a permeate vapor stream enriched in the desired

component or components and a residue liquid stream depleted in that component

or components.

Alternatively, the design can be simplified by permanently welding

end 203 to the body of the vessel or manufacturing as a unitary part of the body of

128

the vessel. The modules must then be loaded or unloaded from one end only, but

the manufacturing cost of the vessel may be reduced.

The tube or housing may be made of any convenient material. Housings are

usually made of metal, conforming to appropriate codes for the operating

conditions to which they are to be exposed. Pervaporation processes are not

usually operated at feed pressures substantially different from atmospheric,

although they may be operated at high temperatures, above 100° C. In the case that

the feed is introduced at ambient pressure, and 40° C., for example, a housing

made from a plastic may suffice, so long as the material has adequate thermal

conductivity. In the case that the feed is under high hydraulic pressure, or very hot,

a stainless or carbon steel housing, for example, may be needed. In general, we

prefer to use metal housings.

A feed port, 217, and a residue port, 218, are positioned near the ends of the

housing. One or both of the end plates or heads is fitted with, or adapted to accept,

permeate collection pipe,209, through which treated permeate is removed from the

processing train. Alternatively, a flanged permeate port to which the permeate

pipes are connected could be provided.

129

CHAPTER III

PROCESS DESCRIPTION

130

CHAPTER III

PROCESS DESCRIPTION

I. INTRODUCTION

Conversion of glycerol into valuable-added chemicals are appearing in

recent years as a result of glycerol availability since it is the main by-product in

the biodiesel production and in other processes concerning biomass as raw

material. A higher number of applications focus in transforming crude glycerol

into more valuable chemicals since it is a molecule rich in functionalities, with

three -OH groups. Thus, several factors, its low price, availability and its

functionalities, make glycerol very attractive as starting material for many

industrial processes.

“P. Sabatier 1918 has described the catalytic conversion of glycerol to

acrolein. In 1948, H.E. Hoyt et al. have patented a heterogeneous catalyzed

continuous process for the production of acrolein from glycerol. In that patent the

consistence of the catalyst material has been reported as diatomaceous earth

supported ortho-phosphoric acid, which has been mixed with a petroleum oil

fraction with a boiling point of about 300°- 400° C. The acrolein yield is claimed

to be 72.3 %.”

“A manufacturing process of acrolein by dehydration of glycerol in phase

gas, in the presence of solid catalysts having an acidity of Hammett H0 between -9

131

and -18 such as sulfated zirconia has been developed. These catalysts deactivate

slowly so as to permit long reaction cycles and low reactor volumes.” (Sergio

Sabater Prieto)

“Acrolein also can be prepared from glycerol using subcritical and

supercritical water as the reaction media. This method has shown a certain

potential for the dehydration of glycerol, although the conversion and acrolein

selectivity achieved are not significant enough for industrial application. The

addition of a mineral acid to the water is necessary to obtain high acrolein yields,

although the presence of an acid intensifies the corrosive effect. Thus, for an

attractive commercial process for the acrolein synthesis from glycerol in the near

future, low corrosive anions stable under this reaction conditions are needed.”

“Dehydration of glycerol has been performed in liquid phase with zeolites;

it was found that acrolein yields were lower in liquid phase than in gas phase. In

this sense, a recent patent claims that glycerol in water can be converted into

acrolein, olefins, and acetaldehyde catalyzed by zeolites in a continuous fluidized-

bed reactor. This reaction system allows better heat and mass transfer than fixed-

bed reactors, along with the possibility of performing continuous regeneration if

needed. The highest yield to acrolein was obtained at 350ºC with a ZSM5 zeolite-

based catalyst.” (Guerrero-Perez et al.)

132

Acrylic acid is manufactured from glycerol in two steps via acrolein in a

gas phase using special catalysts.

The first stage is the dehydration of glycerol to acrolein using a tungsten

zirconia catalyst is an endothermic reaction (at about 280°C). In the second stage,

oxidation of acrolein to acrylic acid, the acrolein gas is passed over a molybdenum

vanadium oxide catalyst is a strongly exothermic reaction (at about 300°C).

The crude acrolein coming from the first reactor is cooled to about 100°C.

Acrolein containing impurities will be absorbed in water in a purifying process

before continuing to the second reactor. In the oxidation process, the acrolein is

passed through multi-metal oxides in a multitube fixed-bed reactor at temperature

of about 300°C.

From the published US Patent by Jean-Luc Dubois entitled Method for

Preparing Acrylic Acid from Glycerol, Patent No.: US 2010/0168471 A1:

“Glycerol is produced by the methanolysis of vegetable oils at the same

time as the methyl esters which are employed in particular as motor fuels or fuels

in diesel and home-heating oil. It is a natural product, available in large

quantities, and can be stored and transported without difficulty. It has the

133

advantage of being a renewable raw material meeting the criteria associated with

the new concept of “green chemistry”. The development of glycerol has attracted

considerable research, and the preparation of acrylic acid is one of the

alternatives considered.”

“The invention related to a method of preparing acrylic acid from an


acrolein, carried out in the gas phase in the presence of a catalyst and under a

pressure of between 1 and 5 bar, and a second step of oxidation to acrylic acid.”

Acrylic acid is a corrosive chemical that is miscible in water, alcohol, and

esters and polymerizes readily in the presence of oxygen forming acrylic resins.

For this reason, the product is usually stabilized with polymerization inhibitors

such as methyl ethyl hydroquinone (MEHQ).

There are two grades of acrylic acid commercially available:

Technical Grade Acrylic Acid which usually has about 94 percent acrylic

acid content. Technical (also referred to as crude) acrylic acid is suited for the

production of commonly acrylate esters. Major markets for the commodity esters

include surface coatings, adhesives and sealants, textiles, plastic additives, and

paper treatment.

Glacial Grade Acrylic Acid is generally used to designate grades of the acid

with acrylic acid content between 98 to 99.7 percent; although in the literature of

134

many companies selling the product, glacial grade is typically listed as having 99.5

to 99.7 percent acrylic acid content. Glacial acrylic acid is suited for the

production of super absorbent polymers (fro disposable diapers), detergents, water

treatment and dispersants.

For esters, whose manufacture is normally integrated with an acrylic acid

plant, the purification step is undertaken after the esterification process. The

technical grade of the acid is therefore not traded. Acrylates are derivatives of

acrylic acid (such as methyl and ethyl acrylate) whose properties have been

sufficiently modified to enable of acrylic acid to be used in different media as

emulsion and solution polymers. As emulsions, these products may be used as

coatings, finishes and binders leading to applications in paints, adhesives, and

polishes with solutions used for industrial coatings. Two-third of the world's

production of acrylic acid is used to produce acrylic esters (acrylates) primarily for

use in emulsions and solution polymers for latex-based paints, coatings, adhesives

and textiles.

According to the Esterification of Acrylic Acid from US Patent No.

3458561, “The invention related to a novel process for esterifying acrylic acid. A

number of processes are known which are directed to the corresponding acylic

acid and an alcohol to the corresponding acrylic ester in the presence of an

esterification catalyst. Esterification of acrylic acid is possible in a liquid as well

135

as in gas phase. Of primary importance as an esterification catalyst is sulphuric

acid. ”

Acrylic esters may be polymerised, catalysed by heat and oxidising agents

in solution or emulsion methods to form long-chain thermoplastic resins. Broadly,

acrylic ester polymers are colourless, insoluble in aliphatic hydrocarbons and

resistant to alkali, mineral oils and water so that with good resistance to

degradation, adhesion and electrical properties, they are widely used.

Surface coatings, such as paints, represent the largest application for acrylic

esters at about 19 per cent of the market. Demand, that was motivated by the

convenience of water-based paints especially the superior acrylic-based emulsions,

is now being driven by regulations and interests to reduce atmospheric release of

volatile organic compounds (VOCs) used as solvents in traditional (alkyd-based)

surface coatings. This sector is growing at 3 to 5 per cent per year with faster

growth for newer more sophisticated applications (such as UV radiation-curable

polymers).

136

137

Preheated Crude Glycerol T = 180-350°C

• Glycerol <60% • Water >40%

T = 180-350°C P = 1-2 bar

III. DETAILED PROCESS DESCRIPTION EQUIPMENT NAME: Preheater

EQUIPMENT CODE: B-1

Preheater is a general term to describe any device designed to heat fluid

before another process with the primary objective of increasing the thermal

efficiency of the process. Also, the unit serves to impart latent heat to a fluid.

Glycerol conversion can be modulated in the gas-phase reaction and it was

found that acrolein yields were higher. The heated crude glycerol will be sent to

dehydration reactor. Heating is conducted to introduce the crude glycerol stream

already in the gaseous phase.

Crude Glycerol • Glycerol <60% • Water >40%

138

Prieto included in his study that “when the glycerol solution reaches 200

°C, the mixture is completely evaporated. Between 104 and 200 °C, the system is a

mixture of liquid and vapor” (Prieto, Sergio Sabater. Optimization of the

Dehydration of Glycerol to Acrolein and a Scale up in a Pilot Plant).Crude

glycerol solution is first sent to a preheater before sending to the dehydration

reactor. “The charge sent into the reactor may be preheated to a preheating

temperature of the order of around 180°C to 350°C.” (From US 2010/0204502)

139

T = 250-280°C P = 1-3 bar

EQUIPMENT NAME: Dehydration Reactor

EQUIPMENT CODE: R-1

Preheated crude glycerol is sent to a fixed bed reactor containing tungstated

zirconia, a dehydration catalyst, with temperature ranging from 250-280°C and

pressure of 1-3 bar. The glycerol undergoes dehydration reaction to produce the

acrolein and acetol, which is the major by-product of the reaction. Reaction of the

dehydration of glycerol to acrolein is given below.

Crude Glycerol (from B-1)

T = 180-350°C • Glycerol <60% • Water >40%

Crude Acrolein T = 250-280°C

• Acrolein (30-40%) • Acetol<5% • Water <60% • Inert gases (H2, O2)

140

At temperatures higher than 240 °C, glycerol is extensively converted. The

acrolein selectivity shows a maximum at 280 °C. At lower temperatures the

intermolecular dehydration, yielding oligomers of glycerol, is thermodynamically

favoured over the desired intramolecular dehydration forming acrolein. At

temperatures higher than 280 °C, the formation of CO and CO2 is possible. These

two reasons are responsible for the selectivity decrease of acrolein. (From Ulgen et

al. Conversion of Glycerol to Acrolein in the Presence of WO3/ZrO2 Catalysts)

By S. Prieto in his dissertation entitled “Optimization of the Dehydration of

Glycerol to Acrolein and a Scale up in a Pilot Plant”, he reported that tungsten

zirconia catalysts are the most promising because it offer inherent advantages from

the standpoint of industrial application, such as higher stability under high-

temperature treatments, lower deactivation rates during catalysis, and easier

regeneration.

“An approach for finding an optimum working point can be determined. To

get a complete glycerol conversion it is better to work at high temperatures.

Around 280 °C the acrolein production is the highest. However, at higher

temperatures, close to 300 °C, the formation of acrolein decreases a little, and the

formation of by-products increases with the temperature. Therefore, a

141

temperature, around 285 °C will be appropriate to produce the highest amount of

acrolein at a complete glycerol conversion and to minimize the formation of by-

products. The glycerol concentration should be not too high because at high

glycerol concentrations, the glycerol conversion and acrolein selectivity

decreases.”

Formation of acetol with acetone as an intermediate step is also considered

in the dehydration of glycerol to acrolein.

According to the US Patent 5387720, “gas phase reaction is preferable

since it enables a degree of conversion of the glycerol of close to 100% to be

obtained. A proportion of about 10% of the glycerol is converted into acetol,

which is present as the major by-product in the acrolein solution.”

142

T = 100-150°C P = 1-2 bar

EQUIPMENT NAME: Heat Exchanger

EQUIPMENT CODE: H-1

The gas stream from the dehydration reactor is sent to a heat exchanger

where it is cooled to a temperature of 100-150°C from a temperature of 250-280

°C before sending the said stream to a condensation unit where water-rich stream

with heavy by-product is removed from the crude acrolein stream.

Based from the invention made by Dubois (US 2010/0168471), “The gas

stream leaving the first reactor is cooled to 151°C in a heat exchanger.”

According to the invention based from the US Patent 5770021, Process and

Apparatus for Purification of a Gas Stream containing Acrolein, “In the first stage

of the process of the invention, the feed gas stream that typically originates from

Crude Acrolein (from R-1)

T = 250-280°C • Acrolein (30-40%) • Acetol<5% • Water <60% • Inert gases (H2, O2)

Cooled Crude Acrolein T = 250-280°C

• Acrolein (30-40%) • Acetol<5% • Water <60% • Inert gases (H2, O2)

143

the gas-phase oxidation of glycerol is preferably cooled from its production

temperature to a temperature ranging from 100 to 200°C and is introduced into

the bottom part of the cooling column”.

144

EQUIPMENT NAME: Absorption Column

EQUIPMENT CODE: A-1

In the first stage of the purification process, the feed gas stream that

typically originates from the gas-phase dehydration of glycerol to acrolein is

preferably cooled from its production temperature to a temperature ranging from

100° to 150°C and is introduced into the bottom part of the cooling column.

T = 50-60°C P = 1-2 bar

Cooled Crude Acrolein (from H-1)

T = 250-280°C • Acrolein (30-40%) • Acetol<5% • Water <60% • Inert gases (H2, O2)

Top Stream T = 50-60°C

• Acrolein (90-95%) • Inert gases (H2, O2) • Water

Bottom Stream • Water >90% • Acetol<10% • Acrolein <1.5%

Absorbing Solvent • Water (100%)

145

Accordingly, the gaseous effluent may be subjected to an absorption

operation and be carried out in an absorption column. The water circulates

countercurrentwise to the effluent with a mass flow rate preferably ranges from

0.005 to 0.05. (US Patent No. 5770021)

“The invention relates to a method for preparing acrylic acid from an


acrolein, in which an intermediate step is implemented, consisting in at least

partly condensing the water and heavy by-product present in the stream issuing

from the first dehydration step. The method according to the invention, even

though it requires an additional unit associated with the intermediate step, has the

advantage of using an economical raw material and of being able to optimize the

two reaction stages separately. The method remains demonstrably economical.”

(US Patent No. 2010/0168471)

Purification of acrolein is described in the US Patent No. 5770021 entitled

“Process and Apparatus for Purification of a Gas Stream Containing Acrolein”.

“The circulation of the gaseous stream in the column countercurrentwise to

a cold liquid results in condensation of the water and other condensable

components that may be present. The condensed liquid which includes acetol,

water and some part of acrolein flows back down under gravity to the bottom of

the column. The gases at the top of the column composed of acrolein, water and

146

non-condensable gases. The temperature of the gases at the top of the column

preferably ranges from 30° to 60°C, and still more preferably from 50° to 60°C.”

“The cooling column preferably operates at a pressure ranging from 105 to

3x105 Pa.”

“The bottom stream generally contains organic acids and preferably less

than 2%, more preferably less than 1.5%, by weight of acrolein and at least 90%

by weight of water.”

147

T = 180-250°C P = 1-2 bar

EQUIPMENT NAME: Preheater

EQUIPMENT CODE: B-2

Stream that exits at the top of the absorption column is sent to a preheater.

This equipment operates at temperature of 180°C to 250°C.

Acrolein from the absorption column is first sent to a preheater before

sending to the oxidation reactor. “The charge sent into the reactor may be

preheated to a preheating temperature of the order of around 180°C to 350°C.”

(From US 2010/0204502)

The acrolein from the absorption column will pass first to a preheater

before entering the oxidation reactor in order to reach the desired temperature

attainable in the reactor. Steam will serve as the heating medium.

Acrolein Stream (from A-1)

T = 50-60°C • Acrolein (90-95%) • Inert gases (H2, O2) • Water

Preheated Acrolein T = 180-250°C

• Acrolein (90-95%) • Inert gases (H2, O2) • Water

148

EQUIPMENT NAME: Oxidation Reactor

EQUIPMENT CODE: R-2

The heated stream mixture from the heat exchanger is then sent to a reactor

for the oxidation process. The oxidation reactor comprises of an oxidation catalyst,

vanadium-molybdenum oxide, at T = 250-300°C and P = 1-5 bar. The acrolein-

rich stream, stripped of the heavy by-products and most of the water, is sent to the

oxidation reactor where acrolein can then be oxidized to acrylic acid.

T = 250-300°C P = 1-5 bar

Preheated Acrolein (from B-2)

T = 180-250°C • Acrolein (90-95%) • Inert gases (H2, O2) • Water

Air

Crude Acrylic Acid T = 250-300°C

• Acrylic Acid (50-55%) • Acrolein <0.10% • Inert gases (N2, H2, O2) • Water <0.80%

149

According to J. Tichy in his work refer to “Oxidation of acrolein to acrylic

acid over vanadium-molybdenum oxide catalysts”, he reported that “oxidation of

acrolein proceeds favourably with a stoichiometric excess of oxygen, and the

reaction temperature should not exceed 573 K or else it will yield an undesirable

radical reaction”. He also believed that among the recommended catalysts, the

most efficient system for the conversion of acrolein to acrylic acid involve oxide

systems based on Mo-V, Mo-Co, V-Sb and heteropolyacids.

US Patent 20100168471 also suggested the catalysts made of formulations

containing Mo and/or V and/or W and/or Cu and/or Sb and/or Fe should be used

in the catalytic reaction.

Conversion of crude glycerol to acrylic acid via acrolein as its intermediate

step is shown in this stoichiometric reactions.

Oxidation reaction from acrolein to acrylic acid.

According from the two inventions (US Patent 5264525 and US Patent

5739391), “A process for the catalytic gas-phase oxidation of acrolein to acrylic

150

acid in a fixed-bed with contacting tubes, at elevated temperature on catalytically

active oxides with a conversion of acrolein for a single pass of ≥ 95%.”

“We have found that this object is highly achieved wherein the reaction



reactants enter the contacting tubes is from 260° to 300°C until a acrolein

conversion of a ≥95% has been reached, with the provision that the reaction

temperature in this secondary reaction zone is not lower than 240°C.”

Based on the US Patent 20100168471, “Oxidation reaction takes place at

temperature of between 200 °C and 350 °C, preferably from 250 °C to 320 °C and

under the pressure of between 1 and 5 bar. The reaction is carried out in the

presence of molecular oxygen which may be in the form of air having a content of

between 3 to 20% by volume, with regard to the incoming stream and optionally in

the presence of inert gases such as N2. The inert gases necessary for the method

may be optionally consist in full or in part of gases obtained at the top of the

absorption column”.

US Patent 5264625 entitled “Catalytic Gas-phase Oxidation of Acrolein to

Acrylic Acid” described the oxidation process is highly exothermic. It is therefore

required to control the reaction temperature in order to obtain a highly selective

conversion of acrolein to acrylic acid.

151

T = 90-100°C P = 1-2 bar

EQUIPMENT NAME: Dehumidifying Condenser

EQUIPMENT CODE: C-1

The gas effluent from the oxidation reactor is first sent to a condenser

where it is cooled to a temperature of 60-100°C from a temperature of 250-300°C.

The crude acrylic acid from the second reactor will pass through a

dehumidifying condenser where acrolein and other inert gases will separate from

the acrylic acid-water mixture. The acrylic acid and water will be condensed and

be sent to the esterification reactor.

Crude Acrylic Acid (from R-2)

T = 250-300°C • Acrylic Acid (50-55%) • Acrolein <0.10% • Inert gases (N2, H2, O2) • Water <0.80%

Condensate T = 100-150°C

• Acrylic Acid (80-85%) • Water (15-20%)

Uncondensed and inert gases • Acrolein <3% • Inert gases (N2, H2, O2)

152

Based from the invention made by Sridhar (US 005463121A), “The gas

stream leaving the reactor is cooled to 60-100°C in a heat exchanger before

undergo the pervaporation process.”

153

EQUIPMENT NAME: Esterification Reactor

EQUIPMENT CODE: R-3

Acrylic acid free of inert gases from the condenser and ethanol are fed to

the esterification reactor. “The minimum temperature at which the esterification is

achieved depends upon the boiling point of the formed acrylic acid ester and

water. In general, a reboiler temperature between 70 to 180°C with pressure of

760 mm of mercury, is employed. The novel esterification can be carried out by

T = 70-180 °C P = 0.3-0.6 bar

Ethanol

Crude Ethyl Acrylate T = 70-180°C

• Ethyl Acrylate (70-80%) • Water (20-25%) • Acrylic Acid <1.0% • Ethanol <0.50%

Condensate (from C-1)

T = 90-100°C • Acrylic Acid (80-85%) • Water (15-20%)

Sulfuric Acid Solution (Catalyst)

154

continuously introducing about equimolar amount of acrylic acid and alcohol in

the reboiler zone or “sump” of a reactor.”(US Patent No. 3458561)

The recommended catalyst in the reaction is Sulfuric Acid. “A number of

processes are known which are directed to the conversion of acrylic acid and an

alcohol to the corresponding acrylic ester in the presence of an esterification

catalyst. Considering the esterification speed and conversion and avoiding at the

same time the formation of undesirable side reactants, the best results are

obtained when using in the reboiler, from 10 to 25% by weight of sulfuric

acid.”(US Patent No. 3458561)

The reaction of acrylic acid and alcohol is as follows:

“Reacting the acrylic acid and ethanol to yield ethyl acrylate in a

conversion of at least 90% on acrylic acid, and yielding the esterification reaction

mixture comprising ethyl acrylate, acrylic acid, ethanol and water.”(US Patent

No. 20050107629)

155

T = 80-100°C P = 1-2 bar

EQUIPMENT NAME: Heat Exchanger

EQUIPMENT CODE: H-2

The gas effluent from the esterification reactor is first sent to a heat

exchanger where it is cooled to a temperature of 80-100°C from a temperature of

70-180°C.

The mixture of ethyl acrylate, water, acrylic acid and ethanol from the third

reactor reactor will pass counter-currently to the heat exchanger before entering

the ethyl acrylate purification process. Water will serve as the cooling medium.

Based from the invention made byAbdullah (EP 2 325 214 A1), “The step

of pervaporation is carried out at a temperature in the range of about 30°C to

about 100°C.”

Crude Ethyl Acrylate (from R-3)

T = 70-180°C • Ethyl Acrylate (70-80%) • Water (20-25%) • Acrylic Acid <1.0% • Ethanol <0.50%

Cooled Crude Ethyl Acrylate T = 80-100°C


156

EQUIPMENT NAME: Pervaporator

EQUIPMENT CODE: PV-1

This unit will separate water from the crude ethyl acrylate. The water will

pass through the membrane inside the unit and be separated leaving the ethyl

acrylate, ethanol and acrylic acid in the retained material stream. Pervaporation of

water will operate at 60-100 °C and atmospheric pressure.

T = 60-100°C P = 1-2 bar

Permeate • Water

Retained Material Stream T = 60-100°C

• Ethyl Acrylate (90-99%) • Acrylic Acid <1.0% • Ethanol <0.50%

Cooled Crude Ethyl Acrylate

(from H-2) T = 80-100°C


157

“Solvent dehydration is the most common application of pervaporation.

Transport rates of components through the membrane mixtures of components

with close boiling point and azeotropic mixture can be effectively separated.” (W.

Kujawski, Polish Journal of Environmental Studies Vol.9, No.1 (2000)).

The product from the third heat exchanger is sent to a pervaporator. Water

scrubbed, ethyl acrylate, acrylic acid, and ethanol goes to the bottom of the

column. Based from Polish Journal of Environmental Studies Vol.9, No.1 of W.

Kujawski, “Water is continuously extracted in a side pervaporation from the

mixture containing ester, acid and alcohol.”

According to the patent invented by Abdullah (EP 2 325 214 A1), “The

purification process allows for the production of ethyl acrylate at controlled

composition (0-99 mol-%)”

158

T = 10-15°C P = 1-2 bar

EQUIPMENT NAME: Condenser

EQUIPMENT CODE: C-2

The product from the pervaporator is sent to a condenser where it is cooled

to a temperature of 10-15°C from a temperature of 60-100°C until it reaches its

liquid state. The final product composes of ethyl acrylate with 90-99% purity.

Impurities present in the product are acrylic acid and ethanol.

Component Mole % Mass %

Ethyl Acrylate 98% 99%

Acrylic Acid 1% 0.60%

Ethanol 1% 0.40%

Retained Material Stream (from PV-1)

T = 60-100°C • Ethyl Acrylate (90-99%) • Acrylic Acid <1.0% • Ethanol <0.50% Ethyl Acrylate (Product)

T = 10-15°C • Ethyl Acrylate (90-99%) • Acrylic Acid <1.0% • Ethanol <0.50%

159

CHAPTER IV

PLANT CAPACITY

DETERMINATION

160

CHAPTER IV

PLANT CAPACITY DETERMINATION

I. INTRODUCTION

Acrylic acid has served, for more than 30 years, as an essential building

block in the production of some of our most commonly used industrial and

consumer products. Approximately two-thirds of the acrylic acid manufactured is

used to produce acrylic esters - methyl acrylates, butyl acrylates, ethyl acrylates,

and 2-ethylhexyl acrylates - which, when polymerized are ingredients in paints,

coatings, textiles, adhesives, plastics, and many other applications. The remaining

one-third of the acrylic acid is used to produce polyacrylic acid, or crosslinked

polyacrylic acid compounds, which have been successfully, used in the

manufacture of hygienic products, detergents, and wastewater treatment

chemicals.

The largest application for acrylates esters is the production of surface

coatings (48%), followed by adhesives and sealants (21%), plastic additives and

comonomers (12%), paper coatings, and textiles and surface coatings account for

55% of acrylates ester consumption. Acrylic acid and esters are perhaps the most

versatile series of monomers for providing performance characteristics to

thousands of polymer formulations.

161

Incorporation of varying percentages of acrylates monomers permits the

production of thousands of formulations for latex and solution copolymers,

copolymer plastics and cross-linkable polymer systems. Their performance

characteristics—which impart varying degrees of tackiness, durability, hardness

and glass transition temperatures—promote consumption in many end-use

applications.

The world acrylic acid business is characterized by the involvement of a

relatively few major players who have both globalized and set up a range of

strategic alliances, joint ventures and new integrated companies. According to the

leading suppliers of acrylic acid, the annual demand growth will stay at the level

of 5% in the coming years.

Glacial acrylic acid is used in the manufacture of super absorbing polymers

(SAP), which account for 32% of the global demand for acrylic acid. They predict

162

the following demand growth figures for various segments of acrylic acid

consumption: 3.6% per year for acrylates and 5% per year for super absorbent.

The global market is set to continue to grow in excess of 3%/year, pulled by Asia,

China, and India in particular. Exports of acrylic monomers from the US will

slow, as foreign additions to capacity come online, particularly in the Asia/Pacific

region. In spite of the recent economic woes of that region (which have caused the

delay or cancellation of some projects), capacity is expected to increase

significantly, eroding export markets for US producers.

The largest volume application for acrylics will continue to be in the

manufacture of paints and coatings. Acrylic monomers (both acrylate and

methacrylate types) are widely used as the base resin in coatings due to their

compatibility in reformulated products. The bulk of demand is concentrated in

architectural coatings, where product reformulation has nearly reached saturation

levels. Growth will therefore be greater in industrial and specialty coatings, an

area in which reformulation has lagged due to higher performance requirements.

Ethyl acrylate is used to form paint coatings that are resistant to water,

sunshine, and weather. These coatings retain flexibility even at low temperatures.

EA is also used in industrial finishes and coatings for cans and coils. Fabrics gain

texture and durability when ethyl acrylate is added during their manufacture. Ethyl

acrylate also imparts dirt resistance, improves abrasion, and binds pigments to

fabric. Paper is coated with ethyl acrylate to make it water-resistant. Magazines,

163

books, business paper, frozen food packaging, and folding boxboards have such

coatings, making them resistant to water, grease, and oil. Ethyl acrylate is also

used in adhesives for envelopes, labels, and decals. Caulk, glazing, and various

sealants also contain Ethyl acrylate. Ethyl acrylate is also used as a fragrance

additive in various soaps, detergents, creams, lotions, perfumes, and as a synthetic

fruit essence. Ethyl acrylate is also found in such household items as nail mending

kits and in medical items that assist with the binding of tissues, sealing wounds,

and ileostomy appliances.

164

II. SUPPLY AND DEMAND ANALYSIS

A. INTRODUCTION

Demand has increased for acrylic acid derivatives, specifically ethyl

acrylates used in the production of surface coatings. Still, the growth is being

limited by the current global inventory of crude acrylic acid. Due to growing

demand for acrylic acid derivatives led by SAPs, many of the major producers

have responded by expanding plants and building new production facilities at key

sites throughout the world.

The table below shows the percentage use of Ethyl Acrylate in surface

coatings, adhesives and sealants, plastic additives, paper coatings, and textiles.

Application % Consumption

Surface coatings 48

Adhesives and sealants 21

Plastic additives 12

Paper coatings, and textiles 19

Total 100

Table 4.1. Percent Consumption of Ethyl Acrylate

165

B. DEMAND ANALYSIS

In the Philippines, large percentage of ethyl acrylate is use in paint industry

particularly in the manufacture of water-based latex paints.

Acrylic acid and esters are perhaps the most versatile series of monomers

for providing performance characteristics to thousands of polymer formulations.

Incorporation of varying percentages of acrylates monomers permits the

production of thousands of formulations for latex and solution copolymers,

copolymer plastics and cross-linkable polymer systems.

The tables below show the plant capacity of some paint industries that uses

ethyl acrylate and the percent composition of paint.

Company Annual capacity, tons/yr

Nippon Paint Philippines, Inc.

(Cabuyao, Laguna) 30,000

Boysen Paint

(Trece Martires, Cavite) 818,776

Total 848,776

Table 4.2. Plant Capacity of Some Paint industries in the Philippines that uses Ethyl Acrylate

166

Paints are used to protect metals, timber, or plastered surfaces from the

corrosive effects of weather, heat, moisture or gases etc and to improve their

appearance.

The binder, or resin, is the actual film forming component of paint. It

imparts adhesion, binds the pigments together, and strongly influences such

properties as gloss potential, exterior durability, flexibility, and toughness. Binders

include synthetic or natural resins such as acrylics, polyurethanes, polyesters,

melamine resins, epoxy, or oils.

Components Percent by weight

Binder (Ethyl acrylate) 21

Pigment (coloring) 5

Extender (Calcium carbonate) 13

Dispersant 2

Rheology Modifier 1

Thickener 3

Auxiliary binder 3

Water 52

Total 100

Table 4.3. Percent Composition of Paint

167

C. SUPPLY ANALYSIS

There is no industry that produces Ethyl Acrylate in the Philippines. The

succeeding data is the importation of Ethyl Acrylate in the Philippines from year

2004 to 2008 acquired from the National Statistics Office of the Philippines.

YEAR

COUNTRIES

2005 2006 2007 2008

China,

People's Rep. Of

12,630 3,004 204,234 49,296

Indonesia

(Includes West Irian)

566,880 248,345 417,487 643,563

Japan

(Excludes Okinawa)

143,065 106,540 738,500 235,582

Korea,

Rep. of (South)

1,547,700 1,631,096 1,400,716 1,026,230

Malaysia

(Federation of Malaya)

1,572,684 1,913,767 7,425,932 6,851,514

Singapore 1,373,245 1,674,298 1,457,535 4,571,053

Table 4.4. Importation Data Ethyl Acrylate (in kilograms)

168

South Africa,

Rep. of

326,445 650,925 23,550 -

United States

of America

3,763,022 1,799,191 220 369,128

TOTAL 9,307,671 8,027,166 11,668,174 13,746,366

The table shows the top five countries that export Ethyl Acrylate in the

Philippines; United States of America, Singapore, Korea, Indonesia and Malaysia.

The average annual importation of Ethyl Acrylate amounts to 10,687,344 kg or

about 10,687.344 MT. The average annual percentage increase in importation

between 2005 and 2008 is 16.14%.

169

III. MAJOR RAW MATERIAL AVAILABILITY

The raw material to be used for the production of Ethyl Acrylate is crude

glycerol. Glycerol is known to be one of the by-products in the production of

Biodiesel. Every 1000 kg of biodiesel about 100 kg of raw glycerol are obtained.

The table below shows the annual production of Biodiesel based on the top three

Biodiesel-producing plants in the country.

Biodiesel Producers Annual Capacity,

L/yr

Glycerol Production,

MT/yr

(By-product)

Chemrez Technology Inc. 60,000,000 5,280

Senbel Fine Chemicals Inc. 36,000,000 3,168

Romtron Philippines 300,000 26.4

Mt. Holy Coco 4,000,000 352

TOTAL 100,300,000 8,826.40

*density of biodiesel ~ 0.88 kg/L

The total annual production of biodiesel is about 100,300,000 litres. Thus,

the annual crude glycerol production, based on the biodiesel production in the

country, is about 8,826.4 MT.

Table 4.5. Total Annual Coco-Biodiesel Production of the Biggest Biodiesel Plant in the Philippines

170

IV. CONCLUSION

To estimate the amount of Ethyl Acrylate produced using glycerol as the

major raw material, the equation below is used.

Molar mass of glycerol = 92.08 kg/kmol

Molar mass of ethyl acrylate = 100.08 kg/kmol

From Chapter 3:

Conversion of glycerol to acrolein = 90%

Conversion of acrolein to acrylic acid = 98%

Conversion of acrylic acid to ethyl acrylate = 99%

171

From Table 4.2: Annual Capacity of Nippon Paint Phil. Inc. = 30,000 tons/yr

From Table 4.3: Percent Composition of Ethyl Acrylate in Paint = 21%

Annual Demand of Ethyl Acrylate

Calculation of Glycerol needed based on the Ethyl Acrylate (EA) Demand:

The basis in determining the plant capacity of the proposed plant is based

on the annual Ethyl Acrylate demand of Nippon Plant Philippines, Inc. The

availability of the major raw material, glycerol is based on the annual production

of biodiesel in the Philippines. The annual demand of Ethyl Acrylate of Nippon

Paint amounts to about 6,300 tons. Based from the calculated amount of glycerol

above, we have concluded to source out from the two of the largest biodiesel

producers namely Chemrez Technology Inc. and Senbel Fine Chemicals Inc., with

an amount of 5,280 MT and 3,168 MT, respectively.

172

Since the availability of the major raw material from the two biodiesel

companies (8,448 MT glycerol) exceeds the amount needed (6,100 MT glycerol),

we aim to manufacture 5,700 MT annually of ethyl acrylate to supply the demand

of the local paint industry. The plant will operate at 24 hours daily in 300 days per

year.

173

CHAPTER V

MASS AND ENERGY

BALANCE

174

CHAPTER V

MASS AND ENERGY BALANCE

I. INTRODUCTION

In the successful operation of a manufacturing plant, the amount of product

to be produced in a certain amount of raw materials is needed in the study to

determine the feasibility of the project. Thus the material balance established

together with amount of energy consumption per amount of product or raw

materials will determine the cost of product.

All material balances are based upon the law of conservation of mass. By

this law, every unit of mass entering a system or process must subsequently leave

as mass. However, chemical and/or physical changes may have occurred in the

system so that the form of feed and products may be expected to change.

The law of entering equal to leaving generally applies on the material as

well as the energy balance. The amount of raw material supply to the reactor will

be equal to the product produce in each reactor, thus the balance between the

products and raw material is established through its chemical reaction.

In every balance, the second law of thermodynamics is applied which states

that the energy cannot be destroyed but can be exchanged, stored and transformed

into its different forms but the total amount do not change. The amount of heat

175

needed, water to be fed in each reactor was determined through energy balance

established by the chemical reaction in each reactor.

176

177

III. SUMMARY OF BASIS, ASSUMPTIONS AND EQUATIONS

A. MASS BALANCE

Glycerol Preheater (B – 1)

- Crude glycerol will be completely evaporated at 280°C.

(Ref:Optimization of the Dehydration of Glycerol to Acrolein and a Scale

up in a Pilot Plant, Sergio SabaterPrieto)

Dehydration Reactor (R – 1)

- 100% glycerol conversion

(Ref: Optimization of the Dehydration of Glycerol to Acrolein and a Scale

up in a Pilot Plant by Sergio SabaterPrieto

Process for Dehydrating Glycerol to Acrolein. United States Patent

Number 2008/0214880 by Dubois J.L. et.al.)

- 90% of glycerol will be dehydrated producing acrolein, the rest is

converted to acetone. All acetone formed will react with water

producing acetol.

(Ref: Process for Dehydrating Glycerol to Acrolein. United States Patent

Number 2008/0214880 by Duboi, J.L. et.al.)

178

Heat Exchanger (H – 1)

- The gaseous products from R-1 are cooled to 150°C.

(Ref: Process for Dehydrating Glycerol to Acrolein. United States Patent

Number 2008/0214880 by Dubois, J.L. et.al.)

Absorption Column (A – 1)

- All inert gases go to the top portion of the column.

- 90% of the entering water vapor is condensed.

- Bottom products consist of 1.5% acrolein.

(Ref: Process and Apparatus for Purification of a Gas Stream Containing

Acrolein. United States Patent Number 5770021 by Hegoet.al.)

Acrolein Preheater (B – 2)

- Preheater operates at temperature of 180°C to 250°C.

(Ref:Process for manufacturing Acrolein from Glycerol US Patent

2010/0204502 by Dubois et..al.)

Oxidation Reactor (R - 2)

- 98% of acrolein fed is converted to acrylic acid.

- All O2 from air will be consumed.

179

- Oxygen from feed will serve as the excess O2.

- Mass ratio of catalyst to acrolein is about 1:50.

(Ref: Catalytic Gas-phase Oxidation of Acrolein to Acrylic Acid. United

States Patent Number 5264625 by Hammon, U. et. al.)

Dehumidifying Condenser (C – 1)

- The gaseous products from R-2 are cooled to 90°C. All acrylic acid and

water are condensed.

Esterification Reactor (R – 3)

- 99% of acrylic acid fed is converted to ethyl acrylate.

(Ref: Method for Producing Ethyl Acrylate Patent No. 20050107629A1 by

Hershberger et. al.)

- Equimolar amounts of acrylic acid and alcohol is fed in the reactor.

- 36 N H2SO4 is added to make a concentration of 18% H2SO4 in the

reactor feed.

(Ref: Esterification of Acrylic Acid Patent No. 3458561 by

Kautteret.al.)

180

Heat Exchanger (H – 2)

- The crude ethyl acrylate from R-3 is cooled to 100°C.

(Ref: Esterification of Acrylic Acid Patent No. 3458561 by

Kautteret.al.

Synthesis of acrylic or methacrylic acid/acrylate or methacrylate

ester polymers using pervaporation, Patent No. 2 325 214 A1 by

SaadAIArifi, Abdullah)

Pervaporator (PV – 1)

- Ethyl acrylate content in the retentate is >98 mol%.

(Ref: Synthesis of acrylic or methacrylic acid/acrylate or methacrylate

ester polymers using pervaporation, Patent No. 2 325 214 A1 by

SaadAIArifi, Abdullah)

- Water is continuously extracted from the mixture containing ester, acid

and alcohol.

(Ref: Polish Journal of Environmental Studies Vol.9, No.1 by W. Kujawski)

181

Condenser (C – 2)

- The retentate from PV-1 is cooled to 15°C. Ethyl acrylate is in liquid

phase at 15°C and 1 atm.

(Ref: Ethyl acrylate MSDS, www.cameochemicals.com)

182

B. ENERGY BALANCE

Constants Used In Energy Balance

Code Equipment Constants

B – 1 Glycerol Preheater

From General Chemistry, 7th Edition, Kenneth Whitten et al. (2004):

From Standard Thermodynamic Properties of Chemical Substances (2000):

From Steam Table:

H – 1 Heat Exchanger


From Acrolein MSDS (Cameo Chemicals):

From (http://www.chemeo.com/cid/34-484-7):

From Unit Operations in Chemical Engineering, 7th Edition, Warren McCabe et al. (2004):

183

B - 2

Acrolein Preheater




From Steam Table:

R - 2

Oxidation Reactor



From Acrylic Acid MSDS (Cameo Chemicals):



184

From Optimization of the Dehydration of Glycerol to Acrolein by SabaterPrieto (2007):

C – 1 Dehumidifying Condenser




From ChE Handbook, 8th Edition:

From (http://www.sbioinformatics.com/design_thesis/Acrylic_Acid/Acrylic-2520acid_-2520Properties&uses.pdf):


R - 3 Esterification Reactor

From Ethyl Acrylate MSDS (Cameo Chemicals):


185


From Thermodynamic Properties of the Aqueous Sulfuric Acid System to 350 K, Frank Zeiknik:


From (http://www.sbioinformatics.com/design_thesis/Acrylic_Acid/Acrylic-2520acid_-2520Properties&uses.pdf):

From Steam Table:

H -2 Heat Exchanger




186

C - 2 Condenser




187

Basis for Calculation:

Plant Capacity: 5,700 MT/yr

Production Rate: 19,000 kg/day

Working days: 300 days/yr

Conversion:

Dehydration Reactor: 90% conversion of glycerol to acrolein

Oxidation Reactor: 98% conversion of acrolein to acrylic acid

Esterification Reactor: 99% conversion of acrylic acid to ethyl acrylate

Assumptions for losses:

Absorption Column: 1.5% acrolein is found at the bottom stream of the unit

Glycerol Requirement

Feed Requirement (60% Crude Glycerol)

188

IV. MASS BALANCE PER EQUIPMENT

GLYCEROL PREHEATER

Assumption:

• Complete evaporation at 250 °C (Prieto, Sergio Sabater,2007) page 81

Input:

Crude Glycerol (Liquid Phase) = 34,000.00 kg

Output:

Crude Glycerol (Gas Phase) = 34,000.00 kg

Crude Glycerol

T = 25°C

Vaporized Crude Glycerol

T = 280 °C

Glycerol 20,400.00 kg Water 13,600.00 kg --------------------- Total 34,000.00 kg

T = 280 °C

B-1


189

DEHYDRATION REACTOR

Input:

Vaporized Crude Glycerol = 34,000.00 kg

Tungstated Zirconia = 8,869.57 kg

-----------------------------

Total Input = 42,869.57 kg

Output:

Crude Acrolein = 34,000.00 kg

Tungstated Zirconia = 8,869.57 kg

-----------------------------

Total Output = 42,869.57 kg

Tungstated Zirconia (Catalyst) Zirconium Oxide 8,044.70 kg Tungsten Oxide 824.87 kg ---------------- 8,869.57 kg

Acrolein 11,173.92 kg Water 20,386.88 kg H2 89.48 kg O2 708.95 kg Acetol 1,640.77 kg --------------------- 34,000.00 kg


T = 280 °C

Crude Acrolein

T = 280 °C

T = 280 °C P=1-3 bar

R-1


Tungstated Zirconia 8,869.57 kg

190

Assumptions:

• 100% glycerol conversion.

• Ratio of mass of feed to mass of catalyst is 3.83.

(Sergio SabaterPrieto (2007). Optimization of the Dehydration of Glycerol to Acrolein and a Scale up in a Pilot Plant)

(Dubois, J.L. et al. (2008). Process for Dehydrating Glycerol to Acrolein. United States Patent Number 2008/0214880)

• 90% of glycerol is converted into acrolein, the rest to acetone. All acetone produced will then be converted to acetol.

(Dubois, J.L. et al. (2008). Process for Dehydrating Glycerol to Acrolein. United States Patent Number 2008/0214880)

Data:

Computations:

Feed: Crude Glycerol

Glycerol 20,400.00 kg

Water 13,600.00 kg

---------------------

34,000.00 kg

Component Molecular Weight

Glycerol 92.08

Acetol 74.06

Acrolein 56.04

Water 18.02

H2 2.02

O2 32.00

191

Reactions involved:

Acrolein Production:

Glycerol Acrolein

Acetone Production:

Glycerol Acetone

192

Acetol Production:

Acetone Acetol

Water Balance:

193

Amount of Catalyst:

Components:

Product: Crude Acrolein

Acrolein kg

Water kg

H2 kg

O2 kg

Acetol kg

---------------------

34,000.00 kg

194

HEAT EXCHANGER

Input:

Crude Acrolein = 34,000.00 kg

Output:

Cooled Crude Acrolein = 34,000.00 kg



Crude Acrolein

T = 280 °C

Cooled Crude Acrolein

T = 150 °C

T = 150 °C

H-1

195

ABSORPTION COLUMN

Input:

Cooled Crude Acrolein = 34,000.00 kg

Water = 16,000.00 kg

---------------------


Output:

Top Stream = 13,742.39 kg

Bottom Stream = 36,257.61 kg

------------------


Absorbing Solvent

T = 30°C



T = 150 °C

Bottom Stream

Water 16,000.00 kg

Top Stream

T = 60 °C

A-1

Acetol 1,640.77 kg Water 34,348.20 kg Acrolein 268.64 kg --------------------- 36,257.61 kg

Acrolein 10,905.28 kg Water 2,038.68 kg H2 89.48 kg O2 708.95 kg

--------------------- 13,742.39 kg

196

Assumptions:

• All inert gases go to the top portion of the column.

• 90% of the entering water vapor is condensed.

• Bottom products consist of 1.5% acrolein.

(Hugo et al. (1998) Process and Apparatus for Purification of a Gas Stream Containing Acrolein)

Data:

Computations:

Feed: Crude Acrolein

Acrolein 11,173.92 kg

Water 20,386.88 kg

H2 89.48 kg

O2 708.95 kg

Acetol 1,640.77 kg

---------------------

34,000.00 kg

Components Molecular Weight Boiling Point (°C)

Acetol 74.06 145

Acrolein 56.04 53

Water 18.02 100

197

Absorbing Solvent:

Henry’s constant for acetol in water is 0.43 atm/mole fraction.

Minimum liquid-to-gas ratio:

Converting to mass units:

198

Bottom Stream:

Solving equations 1 and 2,

Note:*condensed water vapour from the gaseous feed not included

Top Stream:

Acrolein Balance:

199

Top Product:

Acrolein kg

Water kg

H2 kg

O2 kg

---------------------

kg

200

ACROLEIN PREHEATER

Input:

Acrolein Stream = 13,742.39 kg

Output:

Heated Acrolein Stream = 13,742.39 kg

Acrolein Stream

T = 60 °C

Heated Acrolein Stream

T = 200 °C

T = 200 °C

B-2


--------------------- 13,742.39 kg


--------------------- 13,742.39 kg

201

OXIDATION REACTOR

Input:

Heated Acrolein Stream = 13,742.39 kg

Air Stream = 13,096.23 kg

Vanadium-Molybdenum Oxide = 218.11 kg

---------------------


Output:

Crude Acrylic Acid = 26,838.62 kg

Vanadium-Molybdenum Oxide = 218.11 kg

---------------------


Vanadium-Molybdenum Oxide 218.11 kg

Air Stream T=30 °C

N2 10,044.71 kg O2 3,051.52 kg

-------------------- 13,096.23 kg


--------------------- 13,742.39 kg

Acrylic Acid 13,738.70 kg Acrolein 218.10 kg Water 2,038.68 kg N2 10,044.71 kg O2 708.95 kg H2 89.48 kg

-------------------- 26,838.62 kg


T = 200 °C

Crude Acrylic Acid

T = 300 °C

Vanadium-Molybdenum Oxide (Catalyst)

Vanadium (IV) Oxide 34.90 kg Molybdenum Trioxide 183.21 kg ------------- 218.11 kg

T = 300 °C P =1-5 bar

R-2

202

Assumptions:

• 98% of acrolein is converted to acrylic acid.

• Mass ratio of catalyst to acrolein is 1:50.

(Hammon, U. et al. Catalytic Gas-phase Oxidation of Acrolein to Acrylic Acid. United States Patent Number 5264625)

Data:

Computations:

Feed: Acrolein Stream

Acrolein 10,905.28 kg

Water 2,038.68 kg

H2 89.48 kg

O2 708.95 kg

---------------------

13,742.39 kg


Acrylic Acid 72.04

Acrolein 56.04

Water 18.02

Air 28.84

N2 28.00

O2 32.00

203

Reaction Involved:

Acrylic Acid Production:

Acrolein Acrylic Acid

Amount of Catalyst:

Components:

204

Product: Crude Acrylic Acid

Acrylic Acid kg

Acrolein kg

Water 2,038.68 kg

N2 kg

O2 708.95 kg

H2 89.48 kg

--------------------

26,838.62 kg

205

DEHUMIDIFYING CONDENSER

Input:

Crude Acrylic Acid = 26,838.62 kg

Output:

Uncondensed Vapor and Inert Gases = 11,061.24 kg

Condensed Crude Acrylic Acid = 15,777.38 kg

--------------------


Uncondensed Vapor and Inert Gases

Acrolein 218.10 kg N2 10,044.71 kg O2 708.95 kg H2 89.48 kg ------------------- 11,061.24 kg

Crude Acrylic Acid

T = 300 °C

Condensed Crude Acrylic Acid

T = 90°C

Acrylic Acid 13,738.70 kg Acrolein 218.10 kg Water 2,038.68 kg N2 10,044.71 kg O2 708.95 kg H2 89.48 kg

-------------------- 26,838.62 kg

Acrylic Acid 13,738.70 kg Water 2,038.68 kg --------------------- 15,777.38 kg

T = 90°C

C-1

206

ESTERIFICATION REACTOR

Input:

Acrylic Acid = 13,738.70 kg

Ethanol Stream = 8,784.10 kg

Water = 2,038.68 kg

Sulfuric Acid Solution = 5,067.63 kg

---------------------


Output:

Crude Ethyl Acrylate = 24,561.48 kg

Sulfuric Acid Solution = 5,067.63 kg

---------------------


Crude Ethyl Acrylate

T = 140 °C

Ethanol Stream T = 25 °C

Ethanol 8,784.10 kg


T = 90°C

Sulfuric Acid Solution (Catalyst)

Sulfuric Acid 4,966.28 kg Water 101.35 kg ------------------------ 5,067.63 kg

Acrylic Acid 13,738.70 kg Water 2,038.68 kg --------------------- 15,777.38 kg

Ethyl Acrylate 18,895.35 kg Acrylic Acid 137.38 kg Water 5,440.91 kg Ethanol 87.84 kg --------------------- 24,561.48 kg

Sulfuric Acid Solution 5,067.63 kg

T = 140 °C

P = 0.3-0.6 bar

R-3

207

Assumptions:

• 99% of acrylic acid fed is converted to ethyl acrylate.

(Hershberger et al., Method for Producing Ethyl Acrylate Patent No. 20050107629A1)

• Equimolar amounts of acrylic acid and alcohol is fed in the reactor.

(Kautter et al., Esterification of Acrylic Acid Patent No. 3458561)

• 36 N H2SO4 is added to make a concentration of 18% H2SO4 in the reactor feed.

Data:

Computations:

Feed:


Acrylic Acid 72.04

Ethanol 46.06

Ethyl Acrylate 100.08

Water 18.02

208

Reaction involved:

Ethyl Acrylate Production:

Ethanol Acrylic Acid Ethyl Acrylate

Ethanol (EtOH) Balance:

209

Water (H2O) Balance:

Amount of Catalyst Added:

Basis: 1 Liter of Solution

210

Solving equations 1, 2 and 3,

Product: Crude Ethyl Acrylate

Ethyl Acrylate 18,895.35 kg

Acrylic Acid 137.38 kg

Water 5,440.91 kg

Ethanol 87.84 kg

---------------------

24,561.48 kg

211

HEAT EXCHANGER

Input:


Output:



T = 140 °C


T = 100 °C

T =100 °C

H-2



212

PERVAPORATOR

Input:

Cooled Crude Ethyl Acrylate = 24,561.48 kg

Output:

Permeate = 5,440.91 kg

Retentate = 19,120.57 kg

------------------------------


Retentate

T = 100 °C

Permeate

T = 100 °C


T = 100 °C

Water 5,440.91 kg

T = 100 °C

PV-1


Ethyl Acrylate 18,895.35 kg Acrylic Acid 137.38 kg Ethanol 87.84 kg --------------------- 19,120.57 kg

213

Assumptions:

• Ethyl acrylate content in the retained material stream is<99% by moles.

(SaadAIArifi, Abdullah, Synthesis of acrylic or methacrylic acid/acrylate or methacrylate ester polymers using pervaporation, Patent No. 2 325 214 A1)

• Water is continuously extracted from the mixture containing ester, acid and alcohol

(W. Kujawski, Polish Journal of Environmental Studies Vol.9, No.1)

Data:

Computations:

Feed:

Ethyl Acrylate (EA) = 18,895.35 kg

Acrylic Acid (AA) = 137.38 kg

Water = 5,440.91 kg

Ethanol (EtOH) = 87.84 kg


Ethyl Acrylate 100.08

Acrylic Acid 72.04

Ethanol 46.06

214

Top Stream:

Water (H2O) Balance:

Retentate:

Component Mole % Mass %

Ethyl Acrylate 98 99

Acrylic Acid 1 0.60

Ethanol 1 0.40

215

CONDENSER

Input:


Output:


Retentate

T = 100 °C

Ethyl Acrylate (Product)

T = 15 °C

T =15 °C

C-2



216

V. ENERGY BALANCE PER EQUIPMENT GLYCEROL PREHEATER

Glycerol:

Crude Glycerol (60% Glycerol Solution)

T = 25°C


T = 280 °C

B-1

Steam T = 300°C

217

Water:

218

Steam at 300oC

λ = 1404.60 kJ/kg

Steam Requirement:

219

DEHYDRATION REACTOR

Reactants:


COMPONENT MASS (kg) Cp (kJ/kg · K) mCp (kJ/K)

Glycerol 20,400.00 0.92 18,768.00

Water 13,600.00 1.88 25,568.00

∑mCp= 44,336.00


T = 280 °C

Crude Acrolein

T = 280 °C

T = 280 °C P=1-3 bar

R-1

220

Reaction:

Acrolein Production:

Glycerol Acrolein

Acetone Production:

Glycerol Acetone

COMPONENT MASS (kg) MW n(kmol) ΔHf

(kJ/kmol)

nΔHf(kJ)

Acrolein 11,173.92 56.04 199.39 -87,800.00 -17,506,602.95

Water 7,186.08 18.02 398.78 -241,800.00 -96,425,890.53

Glycerol 18,360.00 92.08 199.39 -597,000.00 -119,036,924.41


(kJ/kmol)

nΔHf(kJ)

Acetone 1,286.74 58.08 22.15 -216,690.00 -4,800,690.70

Glycerol 2,040.00 92.08 22.15 -597,000.00 -13,226,324.93

221

Acetol Production:

Acetone Acetol

Product:


(kJ/kmol)

nΔHf(kJ)

Acetol 1,640.77 74.06 22.15 -422,650.00 -9,363,662.03

Acetone 1,286.74 58.08 22.15 -216,690.00 -4,800,690.70

Water 399.23 18.02 22.15 -241,800.00 -5,356,993.92


Acrolein 11,173.92 1.27 14,190.88

Acetol 1,640.77 1.39 2,280.67

Water 20,386.85 1.88 38,327.29

H2 89.48 14.36 1,284.93

O2 708.95 0.92 652.23

∑mCp= 56,736.01

222

223

HEAT EXCHANGER


Acrolein 11,173.92 1.27 14,190.88

Acetol 1,640.77 1.39 2,280.67

Water 20,386.85 1.88 38,327.29

H2 89.48 14.36 1,284.93

O2 708.95 0.92 652.23

∑mCp= 56,736.01

T = 90 °C

Crude Acrolein

T = 280 °C


T = 150 °C

Cooling Water T = 28°C

T = 150 °C

H-1

224

Mass of Cooling Water:

225

ACROLEIN PREHEATER

Steam at 300oC

λ = 1,404.60 kJ/kg


Acrolein 10,905.28 1.27 13,849.70

Water 2,038.69 1.88 3,832.73

H2 89.48 14.36 1,284.93

O2 708.95 0.92 652.23

∑mCp= 19,619.60

Steam T = 300°C

Acrolein Stream

T = 60°C


T = 200°C

T = 200 °C

B-2

226

Steam Requirement:

227

OXIDATION REACTOR

Reactants:

Heated Acrolein


Acrolein 10,905.28 1.27 13,849.70

Water 2,038.69 1.88 3,832.73

H2 89.48 14.36 1,284.93

O2 708.95 0.92 652.23

∑mCp= 19,619.60

Air Stream T = 30°C


T = 200°C

Crude Acrylic Acid

T = 300°C

T = 280 °C P=1-5 bar

R-2

T = 90°C


228

Air

Reaction:

Acrylic Acid Production:

Acrolein Acrylic Acid


(kJ/kmol)

nΔHf(kJ)

Acrylic Acid 13,738.70 72.04 190.71 -372,200.00 -70,982,011.94

Acrolein 10,687.17 56.04 190.71 -87,800.00 -16,743,998.29

229

Product:



Acrylic Acid 13,738.70 1.36 18,684.63

Acrolein 218.10 1.27 276.99

Water 2,038.68 1.88 3,832.72

N2 10,044.71 1.07 10,747.84

O2 708.95 0.92 652.23

H2 89.48 14.36 1,284.93

∑mCp= 35,479.34

230

DEHUMIDIFYING CONDENSER

Uncondensed Vapor and Inert Gases (non-condensables):


Acrolein 218.10 1.27 276.99

N2 10,044.71 1.07 10,747.84

O2 708.95 0.92 652.23

H2 89.48 14.36 1,284.93

∑mCp= 12,961.99


T = 90°C

Crude Acrylic Acid

T = 300°C


T = 90 °C

C-1

Uncondensed Vapor and Inert Gases T = 90°C

Acrylic Acid Water T = 90 °C

231

Crude Acrylic Acid (condensables):

Acrylic Acid:

232

Water:

233


234

ESTERIFICATION REACTOR

Reactant:



Acrylic Acid 13,738.70 2.01 27,614.79

Water 2,038.68 4.18 8,521.68

∑mCp= 36,136.47

T = 90°C

Steam

at 200°C

Condensed Crude Acrylic

Acid

Ethanol Stream T = 25°C


Ethyl Acrylate Acrylic Acid Water Ethanol T = 140 °C

T = 140 °C

P=0.3-0.6 bar

R-3

Sulfuric Acid Solution (Catalyst) T=25°C

Sulfuric Acid

235

Reaction:

Ethyl Acrylate Formation:

Ethanol Acrylic Acid Ethyl Acrylate

COMPONENT MASS (kg) MW n(kmoles) ΔHf (kJ/kmol) nΔHf(kJ)

Ethyl Acrylate 18,895.33 100.08 188.80 -370,600.00 -69,970,108.24

Water 3,402.22 18.02 188.80 -241,800.00 -45,652,380.39

Acrylic Acid 13,601.31 72.04 188.80 -372,200.00 -70,272,191.82

Ethanol 8,696.26 46.06 188.80 -235,100.00 -44,387,553.76

Product:


Ethyl Acrylate 18,895.35 1.45 27,398.26

Water 5,440.90 1.88 10,228.88

Acrylic Acid 137.38 1.36 186.84

Ethanol 87.84 0.95 83.80

Sulfuric Acid 4,967.64 1.42 7,029.21

∑mCp= 44,926.99

236

Steam at 200oC

λ = 1,938.6 kJ/kg

Steam Requirement:

COMPONENT MASS (kg) ΔHvap (kJ/kg) mΔHvap (kJ)

Ethanol 87.84 855.00 75,103.20

Acrylic Acid 137.38 628.82 86,387.29

∑mΔHvap= 161,490.49

237

HEAT EXCHANGER

COMPONENT MASS(kg) Cp(kJ/kg.K) mCp(kJ/K)

Ethyl Acrylate 18,895.33 1.45 27,398.23

Acrylic Acid 137.38 1.36 186.84

Water 5,440.90 1.88 10,431.17

Ethanol 87.84 0.95 83.80

∑mCp= 37,897.75

T =75 °C



T = 100 °C


T = 100 °C

H-2

Ethyl Acrylate Acrylic Acid Water Ethanol T = 140 °C

238


239

CONDENSER

Acrylic Acid:

T =80 °C

Ethyl Acrylate Stream

Cooled Ethyl Acrylate (Final Product)

T = 15 °C


T = 25 °C

C-2 Ethyl Acrylate Acrylic Acid Ethanol T = 100 °C

240

Ethyl Acrylate:

241

Ethanol:

242


243

CHAPTER VI

EQUIPMENT DESIGN

244

CHAPTER VI

EQUIPMENT DESIGN

I. INTRODUCTION

In a manufacturing process, the equipment to be used must have

appropriate design considerations. In the design of the equipment, there are

several factors to be considered: the dimensional analysis, the choice of

materials, and the energy requirement. The dimensional analysis will

determine the capacity necessary to handle the required volume of the

materials involved. The choice of materials is an important consideration in

order to account for significant parameters like resistance to chemical

reactions, strength to loads, and stresses. The energy requirement will then

determine the power consumption of the equipment in specified operating

conditions.

For each unit operation, standard operating conditions need to be set

such as temperature and pressure in order to attain equilibrium as well as to

get the desired outcome or product. For these reasons, the equipment in

which certain processes take place has to be supplied with the necessary

energy and proper design.

In case of chemical reactions, it is necessary that the equipment

provide the proper environment, space, time, temperature and pressure. The

245

mechanism whereby energy maybe supplied or removed as required in

maintaining equilibrium must also be provided.

To establish limits of space for a reaction, the material used to confine

the chemicals involved must have significant strength at the extremes of

pressure and temperature that may be encountered. A temperature limitation

would be dictated by the highest temperature used in the equipment and

could be either the maximum temperature of the reaction or the temperature

required to produce the necessary temperature gradient to ensure adequate

heat flow.

For every equipment of a certain type, there applies a certain design

equation. There is a limitation to every type of equipment and certain

equations may not be applicable at all times. Therefore, thorough

understanding of the type and nature of the equipment as well as the

materials to be handled is necessary.

For this chapter, the equipments chosen to be designed are the

Dehydration Reactor, Absorption Column, Shell and Tube Heat Exchanger,

Pervaporator, and Esterification Reactor.

246

II. SUMMARY OF ASSUMPTIONS AND DESIGN EQUATIONS

1. DEHYDRATION REACTOR

A. Assumptions

A. Vessel Design:

(Ref: Optimization of the Dehydration of Glycerol to Acrolein and a Scale

up in a Pilot Plant by Prieto, Sergio Sabater)

From Material and Energy Balance:

Ratio:

(Ref: Chemical Engineering Design Principles, Practice and Economics of

Plant and Process Design by GavinTowler, 2nd edition,)

247

B. Catalytic Fixed Bed


C. For Height of Ceramic Balls Support (CBS)

- Mass of Ceramic Balls Support is 5% of the total weight of the catalyst

(Ref: Process for Manufacturing Acrolein from Glycerol by Dubois)

D. Shell Thickness

- Ej = Efficiency of Longitudinal Joints expressed as a function

= 0.8; Double V or U butt joint for ts=1/8 to 1/4 in

- c = Allowance for Corrosion (in)

=

(Ref: Process Equipment Design by Hesse and Rushton)

- Su = 655 MPa for S31000; Ultimate Stress of Material

(Ref: ChE Handbook, 8th Edition; Table 25-11)

248

- Fm = 1.0; material factor or grade of steel

- Fr = 1.06; stress relieving factor

- Fa = 1.12; radiographing factor

- Fs = 0.2; type of steel factor

(Ref: Process Equipment Design by Hesse and Rushton)

E. Insulation Design:

For Fire Clay:

(Ref: Perry’s Chemical Engineers’ Handbook, 8th Ed, p 2-459)

F. Pump Design:

- The mechanical, kinetic, and potential energies do not change

appreciably, and the velocity and static-head terms can be dropped.

-

-

(Ref: page 208 of Unit Operations of Chemical Engineering 5th Ed. by

McCabe and Smith)

249

-

(Ref: B-1 preheater)

B. Design Equations

• Volume of Reactor:

(Ref: Chemical Reaction Engineering, Octave Levenspiel, 3rd Edition)

• For Height of Ceramic Balls Support:

• For Maximum Internal Pressure (P)

P = ρgH + 14.7

250

• Shell Thickness (ts)

Using API-ASME design equation for Cylindrical Shells

(Ref: Process Equipment Design by Hesse and Rushton, Equation 4-3)

• Head Thickness ( th )

Using API-ASME design equation for Ellipsoidal Head


• Bottom Thickness; tb

For vessel with agitator,

tb = th

• Maximum Stress (S)


251

G. Pump Design:

Bernoulli Equation:

(Ref: Unit Operations of Chemical Engineering 5th Ed. by McCabe and

Smith, Equation 4.32, p. 78)

Equation for Blowers and Compressors:

(Ref: Unit Operations of Chemical Engineering 5th Ed. by McCabe and

Smith, Equation 8.23)

252

2. SHELL AND TUBE HEAT EXCHANGER

A. Assumptions

1. 1 batch per day will be used.

2. BASCO TYPE 500 Model 08072 Heat Exchanger with tube diameter of

5/8” will be used.

3. 1 tube pass will be used with a Rotated Square Pitch arrangement.

4. Using 70% pump efficiency for the tube side fluid.

B. Design Equations

Heat Exchanger Design:

Heat Transfer Equation

253

Tube Side:

Using BASCO TYPE 500 Heat Exchanger Model 08072 with tube Diameter of

5/8”

Number of Tubes = 76

Shell Diameter = 8-5/8”

Surface Area of 74.5ft2

Length of Tube

Rotated Square Pitch

Clearance

No. of tubes in center row

254

Shell Side:

Shell Diameter

Baffle Diameter

(Ref: Chemical Engineering Volume 6, 4th Edition by Coulson and

Richardson, Table 12-5 p. 651)

Baffle Spacing

(Ref: of Chemical Engineering by Coulson and Richardson, Table 12.5

p. 595)

Pump Design:

(Ref: Perry’s Chemical Engineering Handbook 8th Ed. By Perry et.al, p.10-

27)

255

3. ABSORPTION COLUMN

A. Assumptions

• The plate structure must be designed to support the hydraulic loads on the plate

during operation, and the loads imposed during construction and maintenance.

Typical design values used for these loads are:

- Hydraulic load: 600 N/m2 live load on the plate, plus 3000 N/m2 over the

downcomer seal area.

- Erection and maintenance: 1500 N concentrated load on any structural

member.

• Tray spacing must be specified to compute column diameter. As spacing is

increased, column height is increased but the column diameter is reduced. A

spacing of 24 in., which provides ease of maintenance, is optimal for wide

range of conditions; however, a smaller spacing may be desirable for small-

diameter columns with large number of stages; and larger spacing is frequently

used for large-diameter columns with a small number of stages.

• Foaming factor is 0.85.

• Fraction of flooding is taken as 0.80.

256

B. Design Equations

• Entrainment flooding capacity in tray tower

(Figure 6.24. Separation Process Principles by Henley and Seader 2nd ed.)

• Correcting for CF for surface tension, foaming tendency, and the ratio of vapor

hole area Ah to tray active area A according to the empirical relationship:

(Equation 6-42. Separation Process Principles by Henley and Seader 2nd ed.)

• Flooding velocity


257

• Column diameter


• Number of theoretical plates

(Equation 14-33. Perry’s Chemical Engineers’ Handbook 8th ed.)

• Overall tray efficiency

(Using Figure 14-9. Perry’s Chemical Engineers’ Handbook 8th ed.)

• Number of actual plates


• Relationship between angle subtended by chord, chord height and chord length

(Using Figure 11.34. Chemical Engineeering Design by R. Sinnott and G.

Towler)

258

• Relation between hole area and pitch

(Using Figure 11 .35. Chemical Engineeering Design by R. Sinnott and G.

Towler)

• Vessel design equation: API-ASME Code

for shell thickness

Internal pressure

for flanged and dished head

e = 1.0

Head thickness (for head with pressure on the concave side):

Bottom thickness (for head with pressure on the convex side)

259

4. ESTERIFICATION REACTOR

A. Assumptions

• For Vessel Volume (V)

Vapor Space = 20%

• Residence time = 3 hours

(Ref: Kautter et al., Esterification of Acrylic Acid Patent No.

3458561)

• For vessel diameter and height:

In esterification reactions, a batch reactor equipped with four baffles and

a six-bladed turbine impeller is used.

(Ref: G.N. Kraai et al. / Biochemical Engineering Journal 41 (2008)

87–94)

For V= 4 to 200 m3 with turbine mixer and 4 baffles

H/D = 0.75-1.5; where: H = 1.5D

(Ref: Ch.E. HB, p.18-13)

260

• Shell Thickness:

Material for Construction: S31600

For Stainless 316 or S31600, the recommended stress at 140°C (284°F)

is 15,776.71 psi

(Ref: Plant Design and Economics for Chemical Engineers by Peters

and Timmerhaus, 5th Edition, Table 12-10 p.555)

Corrosion Factor (C) = 1/16 in

e = 0.70; for Double-Welded Butt Joint if not radiographed

• n = rotational speed =63 rpm

(Ref: Turbine & High Efficiency Axial Flow Agitators,

http://www.feldmeier.com/cutsheets/turbine_agitator.pdf)

• KT for disk turbine with six blades:

KT = 5.75

(Ref: Unit Operations in Chemical Engineering, McCabe & Smith,

Table 9.2, p. 262)

• Motor Efficiency = 80%

261

• For Heating System:

F = Safety factor = 1.5

(Ref: Engineering Page: Typical Overall Heat Transfer Coefficients

retrieved from: http://www.engineeringpage.com/technology/

thermal/transfer.html)

Tube Type: 1” BWG

Inside Diameter of the Tube =

Distance of coil from the tank wall (dc) = 6in = 0.5 ft = 0.15 m

(Ref: ChE Handbook pg. 11-21)

• For Insulation Design:

Insulating Material: Calcium Silicate

Thermal Conductivity,

(Ref: Thermal Insulation Handbook, p. 8, Table 3.3.1)

262

B. Design Equations

• For Vessel Volume (V)

Using 20% allowance for vapor space:

• For Vessel Diameter and Height

(From Ch.E. HB, p.18-13)

H = 1.5D

• For Maximum Internal Pressure (P)

P = ρgH + 14.7

• Shell Thickness (ts)

Using ASME-UPV Code, design equation for cylindrical shells (from

Peters & Timmerhaus 5th Edition, Table 12-10 p. 544):

263

• Head Thickness ( th )

Using ASME-UPV Code, design equation for ellipsoidal head (from

Peters & Timmerhaus 5th Edition, Table 12-10 p. 544):

• Bottom Thickness; tb

For vessel with agitator,

tb = th

• Impeller Diameter; Da

(p. 241, Unit Operations of Chemical Eng’g by Mc Cabe and Smith 6th

edition)

31

=DDa

• Impeller width; W


edition)

51

=aD

W

264

• Impeller Length; L


edition)

41

=aD

L

• Distance from the vessel floor; E


edition)

att

a DDDD

3;31

== aa

att

DDEDE

DE

====3

3;31

3;

31

• Baffle Width, J;


edition)

123;

121

3;

121 a

at

DJDJ

DJ

===

• Depth of Liquid in Vessel, h:

265

• Power Consumption of impeller (P)

ρ⋅⋅⋅= 53

aT DnkP

• Heating System

Heating transfer area: From ChE Handbook p. 11-20, eq. 11-39

;

F = Safety factor = 1.5

From ChE Handbook 7th Ed pg. 11-21

Distance of coil from the tank wall (dc) = 6 in = 0.1524 m

266

267

5. PERVAPORATOR

A. Assumptions

Operating Pressure = 10 bar (from Berghof Filtration and Plant Engineering)

Pfeed side = Pretentate side = 1 atm

Ppermeate side = 0.1332 atm

(European Patent No. EP 2 325 214 A1, Synthesis of Acrylic or

Methacrylic acid/Acrylate or Methacrylate Ester Polymers Using

Pervaporation)

Membrane:

Material: Polyvinyl Alcohol (PVA)

Membrane Thickness = 25 µm

Nominal Pore Size = non-porous

(European Patent No. EP 2 325 214 A1, Synthesis of Acrylic or

Methacrylic acid/Acrylate or Methacrylate Ester Polymers Using

Pervaporation)

268

Modules:

Type of Module: Tubular (Page 16, Membrane Filtration Handbook)

Module Type = MO 63G_I10HD V Berghof HyperFlux Tubular Module

Material of Construction = Fiber Reinforced Plastic (FRP), Resin

Membrane Area/module = 12.2 m2

Module Length = Tube Length = 3 m

Outer Diameter of Module = 156.4 mm

Internal Diameter of Tube = 10.3 mm

No. of Tubes/module = 72

Tube Arrangement = Triangular Pitch

Module Connection = Parallel

Feed-Permeate Differential Pressure = -0.20...+10 bar

DUMMY:

Diameter = 156.4 mm

Length = 3 m

269

BEND (VICTAULIC CONNECTION NO. 3006305)

Diameter = 168.3 mm

Thickness = 3 mm

Center Distance = 458 mm

Length = 363 mm

Material = Stainless Steel 1.4571

PERMEATE CONNECTION (VICTAULIC-CLAMP WITH FLASH GAP

SEALING)

Diameter = 60.3 mm

Socket = 50 mm

Length 1 = 58 mm

Length 2 = 57 mm

Material = Polyvinyl Chloride-Unplasticised (PVC-U)

270

INLET-OUTLET CONNECTION (VICTAULIC-CLAMP WITH FLASH

GAP SEALING)

Diameter = 168.3 mm

Thickness = 3 mm

Length = 200 mm


STRAP

Clear Height = 230 mm

Inner Width = 163 mm

Thread Length = 80 mm

Thread = M8


SADDLE

Broadth = 20 mm

Bore = 10 mm

271

Height = 20 mm

Module Center Height = 90 mm

Length = 200 mm

Distance = 170 mm

Material = Polypropylene (PP)

(Ref: Berghof Filtration and Plant Engineering, HyperFlux Tubular

Module, retrieved from http://www.lindenfiltration.com

/uploads/2/8/7/6/2876985/tub_mod.pdf)

Viscosity of the Feed = 0.6406 cP

(Ref: Perry’s Chemical Engineering Handbook, Table 2-412, 8th Edition.)

Velocity is assumed to be 5 m/s to give a turbulent flow and a good mass transfer

based on page 1036 of Unit Operations of Chemical Engineering, 5th Ed.

Operating time: 110 min

(Time-Dependence of Pervaporation Performance for the Separation of

Ethanol/Water Mixtures through Polyvinyl Alcohol Membrane, by Gewei

Li, Wei Zhang, Juping Yang, Xinping Wang)

272

Type of Pump = centrifugal pump (Membrane Filtration Handbook, p. 38)

Material of Construction = stainless steel

(Perry’s Chemical Engineering Handbook 7th Edition, page 10-24)

B. Design Equations

1. Unit Operations of ChE, McCabe and Smith, Equation 29.48, p. 1040, 7th

Edition

Where:

J = permeate flux

= mass transfer coefficient

C1 = concentration of AA at retentate

Cs = concentration of AA at feed

273

2. Unit Operation of ChE, McCabe and Smith, Equation 30.55, p. 1041, 7th Ed.

Where:

Dv = diffusivity

T = temperature (K)

ro = radius of particles (cm)

μ’ = viscosity (cP)

3. Unit Operations of ChE, McCabe and Smith, Equation 3.8, p. 59, 5th Ed.

Where:

Nre = Reynolds Number

D = Diameter of Vessel

v = Velocity of fluid

µ = viscosity

274

4. Unit Operation of ChE, McCabe and Smith, Equation 3.10, p. 53, 7th Edition

Where:

NSc = Schmidt Number

µ = viscosity

ρ = density

Dv = diffusivity

5. Unit Operations of ChE, McCabe and Smith, Equation 17.71, p. 545, 7th Edition

Where:

NSh = Sherwood Number

Re = Reynolds Number

Sc = Schmidt Number

275

6. Unit Operations of ChE, McCabe and Smith, Equation 17.71, p. 545, 7th Edition

Where:



D = diameter of tube

Dv = diffusivity

7. Unit Operations of Chemical Engineering, McCabe and Smith, Equation 30.49,

p. 1037, 5th Edition:

Where:

u = permeate flux

Qm = membrane permeability

ΔP = transmembrane pressure

276

8. Transmembrane Pressure (ΔP):

Where:

= partial vapor pressure of more volatile component on feed side

= partial vapor pressure of more volatile component on permeate side

9. ChE Handbook 7th Edition, p. 10-23 Equation 10-50:

Where:

H = total dynamic head (Pa)

Q = capacity (m3/hr)

10. From Berghof Module Data Sheet:

277

11. From Berghof Module Data Sheet:

Where:

Pressure Drop along Module = (kPa)

v =Cross Flow Velocity (m/s)

L = Module Length (m)

278

III. EQUIPMENT DESIGN

279

SPECIFICATION SHEET IDENTIFICATION Date : Name Dehydration Reactor Code R-1 Unit/s required 1 FUNCTION To convert Glycerol to Acrolein OPERATION Continuous TYPE Fixed Bed Reactor VOLUMETRIC FLOWRATE 1.24 m3/hr MATERIAL HANDLED Glycerol, Water, Tungstated Zirconia

(catalyst) DESIGN DATA Pressure (P) 183.2 kPa Density (ρ) 1,141.7 kg/m3

Temperature 280oC Specifications Material of Construction S31600 Diameter 1.1 m Height (H) 4.3 m Head thickness (th) 3 mm Shell thickness (ts) 3 mm Bottom thickness (tb) 3 mm

Type of Joint Double V/U butt joint Joint Efficiency 80 %

Catalyst Bed Height 2 m Diameter 1.1 m

Catalyst Bed Support Material Alumina ceramic ball Diameter 1.1 m Height (above the catalyst) 0.12 m Height (bottom of the catalyst) 0.23 m

Insulation Design Outside Diameter 1.18 m Thickness 40 mm Insulating Material Fire Clay Thermal Conductivity 1.02

Compressor Design Compressor Type Centrifugal Compressor Power Requirement 1.5 HP

280

Fixed Bed Reactor

Inlet

th= 3 mm

th= 3 mm

ts= 3 mm

Hbed= 2 m

Hbed support= 0.12 m

Hbed support= 0.23 m

Catalyst Dump Flange

D = 1.1 m

Outlet

H = 4.3 m

281

Design Calculation

From Material & Energy Balance:

Feed:

Component Density (kg/m3) kg kgmol Glycerol 1,261.00 20,400.00 221.55

Water 1,000.00 13,600.00 755.56

TOTAL 34,000.00 977.10

Reaction Involved:

For acrolein:

glycerol acrolein

glycerol acetone

90% Conversion (1)

10% Convesion (2)

acetone acetol

282

For continuous process:

Calculation for space time

From Chemical Reaction Engineering, Octave Levenspiel, 3rd Edition

Derivation:

For reactor containing catalyst particle:

At steady state a material balance for reactant A gives

In symbols

In differential form

Thus

Elementary slice of solid catalyzed reactor

283

Where:

(Ref: Optimization of the Dehydration of Glycerol to Acrolein and a Scale up in a

Pilot Plant by Prieto, Sergio Sabater)

Based from the graph, to obtain a 100% conversion of glycerol should be equal

to 0.6

(Ref: Chemical Reaction Engineering, Octave Levenspiel, 3rd Edition)

284

For reaction (1)


For reaction (2)


285

With a safety factor of 20%:

For volume of catalyst: From Material and Energy Balance:

For volume of Ceramic Balls Support (CBS): (Ref: Process for Manufacturing Acrolein from Glycerol by Dubois)

(Ref:Chemical Engineering Design Principles, Practice and Economics of Plant

and Process Design by GavinTowler, 2nd edition)

286

Ratio:

For Catalytic Fixed Bed Height and Diameter:

For Height of Ceramic Balls Support (CBS): (Ref: Process for Manufacturing Acrolein from Glycerol by Dubois)

From Albright’s Chemical Engineering Handbook by Lyle F. Albright

287

Shell Thickness:

From Process Equipment Design by Hesse and Ruston, Equation 4-3


Where:

ts = Shell Thickness (in)

P = Maximum Allowable Working Pressure (psi)

D = Inside Diameter of the Shell before Corrosion Allowance is

added (in)

S = Maximum Allowable Working Stress (psi) using S31000

Ej = Efficiency of Longitudinal Joints expressed as a fraction

= 0.8; Double V or U butt joint for ts=1/8 to 1/4 in (Process

Equipment Design by Hesse and Ruston)

c = Allowance for Corrosion (in)

=

Maximum Stress (S)


Where:

Su = 655 MPa for S31000; Ultimate Stress of Material (ChE

Handbook, 8th Edition; Table 25-11)

Fm = 1.0; material factor or grade of steel

Fr = 1.06; stress relieving factor

Fa = 1.12; radiographing factor

Fs = 0.2; type of steel factor

288

For Maximum Internal Pressure:

289

Head and Bottom Thickness:


Using API-ASME design equation for Ellipsoidal Head

Insulation Design:


From ChE Handbook, 7th Ed, p 2-335

For a reactor with temperature of 280°C, the recommended insulation material is

Fire Clay with a thermal conductivity of

Di

Do

290

Compressor Design: Bernoulli Equation:

For blowers and compressors: (From page 208 of Unit Operations of Chemical Engineering 5th Ed. by McCabe and Smith)

In blowers and compressors the mechanical, kinetic, and potential energies do not change appreciably, and the velocity and static-head terms can be dropped. Also, on the assumption that the compressor is frictionless, and with this simplifications the equation becomes

291

Power requirement:

292

SPECIFICATION SHEET IDENTIFICATION Date Name Heat Exchanger Code H-1 Units required 1 FUNCTION To cool the Crude Acrolein OPERATION Continuous TYPE Shell and Tube Heat Exchanger DUTY 7,500,000 kJ/day

MATERIAL HANDLED Acrolein, Acetol, Water, Hydrogen, Oxygen

DESIGN DATA Shell Side Design Tube Side Design

Fluid Handled Water Fluid Handled Crude Acrolein Mass Flow rate 9.44 kg/s

Mass Flow rate 7.90 kg/s Volumetric Flow rate 0.0094 m3/s Velocity 0.2106 m/s Velocity 0.5935 m/s

Temperature 28°C 90°C Temperature 280°C 150°C Outer Diameter 16 mm

Bundle Diameter 204 mm Inside Diameter 14 mm Shell Diameter 219 mm Length of tubes 2 m Wall Thickness 3 mm Tube surface area 4.70 m2 Baffle Spacing 43.8 mm Number of tubes 76 Baffle Diameter 214 mm Tube Pitch 19.85 mm

Type of Joint Double-Welded Butt Joint Pressure Drop 21.9 kPa

Joint Efficiency 80 % Clearance 3.97 mm Shell Material G10200 Tube Material S50200 Pump Design Pump Type Centrifugal Power Requirement 4 HP

293

Shell and Tube Heat Exchanger

2 m

294

Tube Arrangement

Outside Diameter = 5/8 in = 15.88 mm

Using Rotated Square Pitch

(From Plant Design and Economics by Peter and Timmerhaus)

Tube Pitch, pt = 1.25 Do = 1.25 (15.88 mm) = 19.85 mm

Clearance = 0.25 Do = 0.25 (15.88 mm) = 3.97 mm

19.85 mm

3.97 mm

295

Design Calculations for Heat Exchanger


Amount of Heat, Q = 7,375,680.66 kJ/day

Cooling Water Mass Flow = 28,432.74 kg/day

Design Operation:

Operation: 1 Batch per Day

Operating Time: 1 hour

Heat Transfer Equation:

Logarithmic Mean Temperature Difference

Crude Acrolein Cooling Water

Temperature in (oC) 280 28

Temperature out (oC) 150 90

296

Overall Heat Transfer Coefficient

Overall Heat transfer coefficient of shell and tube heat exchanger

(Ref: Chemical Engineering Vol. 6, 4th Edition by Coulson and

Richardson, Table 12.1 p. 637)

Heat Transfer Area

297

Tube Side Design

Fluid Handled : Crude Acrolein

Mass Flow Rate : 34,000 kg/day

Mass Flow Rate

Volumetric Flow Rate (GPM)

For a Surface Area of = 4.7012 m2 ≈ 50.60 ft2

(Ref: Basco Type 500 Heat Exchangers Model 08072 Standard Straight Tube

Type)

Surface Area = 62.1 ft2

Number of tubes = 76

Tube Outside Diameter (Do) = 5/8” ≈ 15.88 mm

298

Shell Diameter = 8 5/8” ≈ 0.2191 m

Maximum Flow Rate (GPM) = 461 GPM

Using 5/8 in OD BWG 20,

Outside Diameter (Do) = 15.88 mm

Inside Diameter (Di) = 14.097 mm

Length of Tubing Required

Tube Side Velocity

From BASCO TYPE 500 HEAT EXCHANGERS

Velocity factor = 1.47 (for 5/8” tubing)

299

Pitch Type: Rotated Square Pitch

Tube Pitch, pt = 1.25 Do = 1.25 (15.88 mm) = 19.85 mm

Clearance = 0.25 Do = 0.25 (15.88 mm) = 3.97 mm

Pressure Drop

(Ref: Equation 12.18 p.666 Chemical Engineering Vol. 6, 4th Edition by

Coulson and Richardson)

Evaluating for Jf,

Viscosity of solution mostly Acrolein= 0.05632 Pa-s

(Ref: www.epa.gov/hpv/pubs/summaries/acriolein/c13462rs.pdf)

From Fig. 12.24 p. 668 of Chemical Engineering Vol. 6 4th Ed. By Coulson and

Richardson

0

300

Therefore:

301

Pump Design

Pressure Head

(Ref: p. 10-27 Perry’s Chemical Engineering Handbook 8th Ed. By Perry et.al)

302

Shell Side Design

Fluid Handled : Water

Mass Flow Rate : 28,432.74 kg/day

Mass Flow Rate

Bundle Diameter

Shell Diameter


Baffle Diameter and Spacing

(Ref: Chemical Engineering Volume 6, 4th Edition by Coulson and Richardson,

Table 12-5 p. 651)

303

Number of tubes in center row

Pressure Drop

(Ref: Chemical Engineering Vol. 6, 4th Edition by Coulson and Richardson)

Velocity, us


Velocity factor of shell = 10

304

Evaluating diameter, de, from Eq. 12.22 p. 672 of Chemical Engineering Vol. 6 4th

Ed. By Coulson and Richardson

Evaluating for Jf,

Viscosity of water at average temperature of 37.5oC= 0.704 mPa-s

(Ref: Perry’s ChE Handbook 8th Edition, T 2-313 p. 2-432)

From Fig. 12-30 p. 674 of Chemical Engineering Vol. 6 4th Ed. By Coulson

and Richardson

305

Therefore:

Using 5/8 in OD BWG 20,

Outside Diameter (Do) = 15.88 mm

Inside Diameter (Di) = 14.097 mm

Vtubes = NT x S x LT

D = 2.8905 m (superficial diameter for the flow of cooling water)

306

Shell Thickness

Material of Construction : G10200

Joint : Double Welded V-butt

Efficiency : 0.80

Corrosion Allowance : 1/16 in

From Process Equipment Design by Hesse and Rushton, Equation 4-3


Where:

ts = Shell Thickness (in)

P = Maximum Allowable Working Pressure (psi)

D = Inside Diameter of the Shell before Corrosion Allowance is

added (in)

S = Maximum Allowable Working Stress (psi) using G10200

e = Efficiency of Longitudinal Joints expressed as a fraction

307

= 0.8; Double V or U butt joint for ts=1/8 to 1/4 in (Process

Equipment Design by Hesse and Rushton)

c = Allowance for Corrosion (in)

=

Working Pressure = ρgh; h= superficial diameter

Pressure Head = Atmospheric Pressure + Working Pressure

= 101 325 Pa + 1000 kg/m3 (9.8 m/s2) (2.8905 m)

= 129 651.90 Pa = 18.8045 psi

From table 4-1 of Process Equipment Design by Hesse and Rushton,

Fs = 25% for temperatures up to 650 ºF

S =Su x Fm x Fa x Fr x Fs (Eq. 4-1 p.84 of PED by Hesse and Ruston)

Su = 65000 psi (G10200; ChE Handbook 8th ed p 25-32 table 25-8)

Fm = 1.0

Fr = stress relieving factor = 1.0

Fa = radiographing factor = 1.0

Fs = 0.25

308

Assuming stress relieving and radiographing factors are not employed:

S = 65,000 psi x 1.0 x 1.0 x 1.0 x 0.25

S = 16,250 psi

From Process Equipment Design by Hesse and Rushton, Equation 4-3


309

SPECIFICATION SHEET Item: Absorption Column Number required: 1 Code: A-1 Function: To purify acrolein from the dehydration reactor Operation: Continuous

Type: Tray column Cross flow

INTERNAL CONDITIONS Top Bottom Vapor to tray Crude acrolein Rate 3.9 m3/s 6.9 m3/s Density 1.2 kg/m3 0.68 kg/m3 Pressure 100 kPa 100 kPa Temperature 55°C to 60°C 140°C to 150°C Liquid from tray Water Rate 2.22 L/s 5.1 L/s Density 1000 kg/m3 1000 kg/m3 Temperature 25°C to 30°C 55°C to 60°C Viscosity 0.85 cP 0.50 cP OPERATING DATA Column diameter 1.5 m Tray space 600 mm Total trays in section 5 trays Column height 3.5 m Number of passes Single pass Downcomer type Segmental Weir height 100 mm Clearance height 90 mm Hole size 13 mm Ø Hole pitch 35 mm ∆ TECHNICAL/MECHANICAL DATA Tray type Sieve tray Tray material Stainless steel Tray thickness 6 mm Downcomer material Stainless steel Downcomer bar thickness 6 mm Support ring material Stainless steel Support ring thickness 6 mm Support ring width 50 mm

310

CONSTRUCTION AND MATERIALS Material of Construction: Stainless steel UNS S31600 Shell thickness: 4 mm Weld profile: Single U butt joint Welding efficiency: 70% Head type: Flanged and dished head Head thickness: 4 mm Bottom thickness: 7 mm PUMP DESIGN Pump type: Centrifugal Power requirement: 1.5 HP

311

Absorption Column

600 mm

3.5 m

Gas In

6 mm

4 mm

Gas Out Liquid

Liquid

Sieve tray

1.5 m

312

PLATE AREA

TOP VIEW OF ARRANGEMENT ON A TRAY

d = 13 mm

p = 35 mm

313

TYPICAL CROSS-FLOW PLATE (SIEVE)

314

MATERIALS HANDLED

Basis: 2 hours operation

Feed: 34,000 kg

Liquid properties (water)

Density, ρx

Viscosity, µx @30°C

Surface tension

315

Properties of Gas (acrolein stream)

316

TRAY-TOWER DESIGN

Diameter

“The overall height of the column will depend on the plate spacing. Plate

spacing from 0.15 m (6 in.) to 1 m (36 in.) are normally used. The spacing chosen

will depend on the column diameter and operating conditions. Close spacing is

used with small-diameter columns, and where head room is restricted; as it will be

when a column is installed in a building. For columns above 1 m diameter, plate

spacing of 0.3 to 0.6 m will normally be used, and 0.5 m (18 in.) can be taken as

an initial estimate. This would be revised, as necessary, when the detailed plate

design is made.”

(Chemical Engineeering Design by R. Sinnott and G. Towler)

317

estimate: for tray spacing = 24 in., from Fig. 6.24, CF = 0.39 ft/s

Fig.6.24 (Separation Process Principles by Henley and Seader 2nd ed.)

318

Correcting for CF for surface tension, foaming tendency, and the ratio of

vapor hole area Ah to tray active area A according to the empirical

relationship:


Solving for flooding velocity


319

Column diameter


Typically, the fraction of flooding, f, is taken as 0.80.

Tray spacing must be specified to compute column diameter. As spacing is

increased, column height is increased but the column diameter is reduced. A

spacing of 24 in., which provides ease of maintenance, is optimal for wide range

of conditions; however, a smaller spacing may be desirable for small-diameter

columns with large number of stages; and larger spacing is frequently used for

large-diameter columns with a small number of stages.

320

Tray spacing with their corresponding column diameter:

Tray Spacing Computed diameter

36 in. 1.3 m

24 in. 1.5 m

18 in. 1.8 m

12 in. 2.0 m

9 in. 2.3 m

6 in. 2.5 m

Column diameter = 1.5 m

Tray spacing = 24 in. (600 mm)

Number of Theoretical Plates


321

Henry’s law constant for acetol is 0.43 atm/mole fraction:

322

Tray Efficiency

“The O’Connell parameter for gas absorbers is ρL/KMμL, where ρL is the

liquid density, lb/ft3; μL is the liquid viscosity, cP; M is the molecular weight of the

liquid; and K = y°/x. “. (Perry’s Chemical Engineers’ Handbook 8th ed., p. 14-15)

According to the O’Connell graph for absorbers (Using Fig. 14-9. Perry’s

Chemical Engineers’ Handbook 8th ed.) the overall tray efficiency is estimated to

be 60 percent.

323

Number of Actual Plates


The required number of actual trays is 3/0.60 = 5 trays

Height of the Column

“The required height of a gas absorption tower for physical solvents

depends on (1) the phase equilibria involved; (2) the specified degree of removal

324

of the solute from the gas; and (3) the mass-transfer efficiency of the device. These

three considerations apply to both tray and packed towers. Items 1 and 2 dictate

the required number of theoretical stages (tray tower). Item 3 is derived from the

tray efficiency and spacing (tray tower). For tray towers, the approximate design

methods described below may be used in estimating the number of theoretical

stages, and the tray efficiencies and spacings for the tower.” (Perry’s Chemical

Engineers’ Handbook 8th ed., p. 14-9)

actual plates = 5 plates

tray spacing = 600 mm

tray thickness = 6 mm

height of the column = (5 x 600 mm) + (5 x 6 mm) = 3030 mm

Vapor space = 20%

height of the column = 3030 mm x 1.2 = 3600 mm

height of column = 3.5 m

325

PRIMARY TRAY CONSIDERATIONS

Number of Passes

“Trays smaller than 1.5-m (5-ft) diameter seldom use more than a single

pass; those with 1.5- to 3-m (5- to 10-ft) diameters seldom use more than two

passes. Four-pass trays are common in high liquid services with towers larger

than 5-m (16-ft) diameter.” (Perry’s Chemical Engineers’ Handbook 8th ed., p. 14-

29)

Number of passes: Single Pass

Tray Spacing

“Taller spacing between successive trays raises capacity, leading to a

smaller tower diameter, but also raises tower height. There is an economic

tradeoff between tower height and diameter. As long as the tradeoff exists, tray

spacing has little effect on tower economies and is set to provide adequate access.

326

In towers with larger than 1.5-m (5-ft) diameter, tray spacing is typically 600 mm

(24 in), large enough to permit a worker to crawl between trays. In very large

towers (>6-m or 20-ft diameter), tray spacings of 750 mm (30 in) are often used.

In chemical towers (as distinct from petrochemical, refinery, and gas plants), 450

mm (18 in) has been a popular tray spacing. With towers smaller than 1.5 m (5 ft),

tower walls are reachable from the manways, there is no need to crawl, and it

becomes difficult to support thin and tall columns, so smaller tray spacing

(typically 380 to 450 mm or 15 to 18 in) is favored. Towers taller than 50 m (160

ft) also favour smaller tray spacings (400 to 450 mm or 16 to 18 in).” (Perry’s

Chemical Engineers’ Handbook 8th ed., p. 14-29)

Tray spacing: Using 1.5 meter diameter, the tray spacing is 24 in. (600 mm)

Outlet Weir

“The outlet weir should maintain a liquid level on the tray high enough to

provide sufficient gas-liquid contact without causing excessive pressure drop,

downcomer backup, or a capacity limitation. Weir heights are usually set at 40 to

80 mm (1.5 to 3 in). In this range, weir heights have little effect on distillation

efficiency [Van Winkle, Distillation, McGraw-Hill, New York, 1967; Kreis and

Raab, IChemE Symp. Ser. 56, p. 3.2/63 (1979)]. In operations where long

residence times are necessary (e.g., chemical reaction, absorption, stripping)

327

taller weirs do improve efficiency, and weirs 80 to 100 mm (3 to 4 in) are more

common (Lockett, Distillation Tray Fundamentals, Cambridge University Press,

Cambridge, England, 1986).” (Perry’s Chemical Engineers’ Handbook 8th ed., p.

14-29)

Weir height: 4 in. (100 mm)

Downcomers

“A downcomer is the drainpipe of the tray. It conducts liquid from one tray

to the tray below. Due to the density difference, most of this gas disengages in the

downcomer and vents back to the tray from the downcomer entrance. Some gas

bubbles usually remain in the liquid even at the bottom of the downcomer, ending

on the tray below [Lockett and Gharani, IChemE Symp. Ser. 56, p. 2.3/43 (1979)].

The straight, segmental vertical downcomer (Fig. 14-23a) is the most common

downcomer geometry. It is simple and inexpensive and gives good utilization of

328

tower area for downflow.” (Perry’s Chemical Engineers’ Handbook 8th ed., p. 14-

31)

Figure 11.34. Relationship between angle subtended by chord, chord height

and chord length

(Ref: Chemical Engineeering Design by R. Sinnott and G. Towler)

329

Clearance under the Downcomer

“Restricting the downcomer bottom opening prevents gas from the tray

from rising up the downcomer and interfering with its liquid descent (downcomer

unsealing). A common design practice makes the downcomer clearance 13 mm

(0.5 in) lower than the outlet weir height (Fig. 14-25) to ensure submergence at

all times [Davies and Gordon, Petro/Chem Eng., p. 250 (November 1961)]. This

practice is sound in the froth and emulsion regimes, where tray dispersions are

liquid-continuous, but is ineffective in the spray regime where tray dispersions are

gas-continuous and there is no submergence. Also, this practice can be

unnecessarily restrictive at high liquid loads where high crests over the weirs

sufficiently protect the downcomers from gas rise.” (Perry’s Chemical Engineers’

Handbook 8th ed., p. 14-31)

Clearance height: 3.5 in. (90 mm)

330

Hole Sizes

“Small holes slightly enhance tray capacity when limited by entrainment

flood. Reducing sieve hole diameters from 13 to 5 mm (½ to 3/16 in) at a fixed hole

area typically enhances capacity by 3 to 8 percent, more at low liquid loads. Small

holes are effective for reducing entrainment and enhancing capacity in the spray

regime (QL < 20 m3/hm of weir). Hole diameter has only a small effect on

pressure drop, tray efficiency, and turndown. On the debit side, the plugging

tendency increases exponentially as hole diameters diminish. Smaller holes are

also more prone to corrosion. While 5-mm (3/16-in) holes easily plug even by scale

and rust, 13-mm (½ in) holes are quite robust and are therefore very common. The

small holes are only used in clean, noncorrosive services. Holes smaller than 5

mm are usually avoided because they require drilling (larger holes are punched),

which is much more expensive. For highly fouling services, 19- to 25-mm (¾ to 1-

in) holes are preferred.” (Perry’s Chemical Engineers’ Handbook 8th ed., p. 14-

31)

Hole size: 0.5 in. (13 mm)

331

Provisional Plate Design

Perforated Area

332

Figure 11 .35. Relation between hole area and pitch

(Ref: Chemical Engineeering Design by R. Sinnott and G. Towler)

From figure above, lp/dh = 2.7 (satisfactory, within 2.5 to 4.0), lp = 35 mm

333

Number of Holes

MATERIAL OF CONSTRUCTION

Using API-ASME Code

For Shell Thickness, tS

For stainless 316 or S31600:

334

The plate structure must be designed to support the hydraulic loads on the

plate during operation, and the loads imposed during construction and

maintenance. Typical design values used for these loads are:

Hydraulic load: 600 N/m2 live load on the plate, plus 3000 N/m2 over the

downcomer seal area.

Erection and maintenance: 1500 N concentrated load on any structural member.

335

Verify if Fa and Fr are mandatory

Radiographing and relieving may not be employed since 0.14 in. < 0.91 in.

336

For Flanged and Dished Head Thickness

• Head thickness (for head with pressure on the concave side)

• Bottom thickness (for head with pressure on the convex side)

337

Pump Design:

Power output (theoretical)


Power Requirement:

For a basis of 70% efficiency of the motor:

Power actual


338

SPECIFICATION SHEET IDENTIFICATION Date : Name Esterification Reactor Code R-3 Unit/s required 1 FUNCTION To convert Acrylic Acid to Ethyl Acrylate OPERATION Batch TYPE Stirred Tank CAPACITY 35 m3 MATERIAL HANDLED Acrylic Acid, Ethanol, Water, Sulfuric Acid DESIGN DATA Pressure (P) 147.8 kPa Density (ρ) 1,020.20 kg/m3

Temperature 140°C SPECIFICATIONS Material of Construction S31600 Diameter 3.1 m Height (H) 4.7 m Head thickness (th) 5 mm Shell thickness (ts) 5 mm Bottom thickness (tb) 5 mm Type of Joint Double-Welded Butt Joint Joint Efficiency 70 % IMPELLER DESIGN Impeller Type Turbine Impeller Diameter

(Da) 1 m

No. of Blades 6 Impeller Length (L) 0.3 m No. of Baffles 4 Impeller Width (W) 0.2 m Impeller Power Requirement

13 HP Impeller Height from Bottom (E)

1 m

Rotational Speed 63 rpm Width of Baffles (J) 0.3 m HEATING COIL DESIGN Heat Transfer Area

4.6 m2 Number of Turns 8

Temperature 200°C Diameter of the Coil 2.3 m Diameter of the Tube

1 in Distance between Coils

0.4 m

Length of the Coil 58.2 m Height of Coils 3.5 m

339

INSULATION DESIGN Outside Diameter 3.11 m Insulating Material Calcium Silicate Thickness 2 mm Thermal

Conductivity 0.05728 W/(m·K)

340

Esterification Reactor

341

Batch reactor equipped with four baffles using a 6-blade turbine impeller

Top view

Side View

Baffle

Blade

342

Design Calculations

For Reactor Volume:

(Ref: Kautter et al., Esterification of Acrylic Acid Patent No. 3458561)


Feed:

Component Density (kg/m3) kg

Acrylic acid 1,050 13,738.70

Ethanol 790 8,784.10

Water 1,000 2,146.28

Sulfuric Acid 1,840 4,967.64

TOTAL 29,636.72

343

With a vapor space of 20%:

For vessel diameter and height:

In esterification reactions, a batch reactor equipped with four baffles and a six-

bladed turbine impeller is used.

(Ref: G.N. Kraai et al. / Biochemical Engineering Journal 41 (2008) 87–94)

(Ref: Ch.E. HB, p.18-13)

For V= 4 to 200 m3 with turbine mixer and 4 baffles

H/D = 0.75-1.5;

Basis: H = 1.5D

Using cylindrical vessel,

344

For Maximum Internal Pressure:

Shell Thickness:

From Plant Design and Economics for Chemical Engineers by Peters and

Timmerhaus, 5th Edition, Table 12-10 p.555:

For Stainless 316 or S31600, the recommended stress at 140°C (284°F) is:

345

Using ASME-UPV Code, design equation for cylindrical shells (from Peters and

Timmerhaus 5th Edition, Table 12-10 p. 554):

Where:

tS = shell thickness (in)

P = maximum allowable working pressure (psi)

r = inside radius of the shell before corrosion allowance is added (in)

S = maximum allowable working stress (psi) using S31600

e = efficiency of joints expressed as a fraction

= 0.70; for Double-Welded Butt Joint if not radiographed (From Plant

Design and Economics for Chemical Engineers by Peters and Timmerhaus

5th Edition, Table 12-10 p. 555)

c = allowance for corrosion (in)

= 1/16 in

346

Head and Bottom Thickness:

Using ASME-UPV Code, design equation for ellipsoidal head (from Peters and

Timmerhaus 5th Edition, Table 12-10 p.554):

Impeller Design:

(Ref: Unit Operations by McCabe &Smith 6th Edition p.241)

Impeller Diameter; Da

Impeller width; W

347

Impeller Length; L

Distance vessel floor; E

Baffle Width, J;

Depth of Liquid in Vessel, h;

Volume of Impeller:

348

Power Consumption of Impeller:

From Turbine & High Efficiency Axial Flow Agitators,

http://www.feldmeier.com/cutsheets/turbine_agitator.pdf:

Speed range for commercially available turbine agitator is 63 to 73 rpm.

To compute for Reynolds Number:

n = rotational speed = 63 rpm = 1.05 rev/s

Da = impeller diameter = 1.03 m

NRe = 438,782.51

Since Re>104 ∴flow is turbulent

KT for disk turbine with six blades (table 9.2, McCabe & Smith p. 262)

KT = 5.75

349

For a motor efficiency of 80%,

Heating Coil Design:

(From ChE Handbook p. 11-20, eq. 11-39)

QF = UAΔTLM

; F = Safety factor = 1.5


Temperature of Feed:

350

°C

Steam T1 200

T2 200

Liquid t1 83

t2 140

(Ref: Engineering Page: Typical Overall Heat Transfer Coefficients retrieved

from: http://www.engineeringpage.com/technology/thermal/transfer.html)

351

From ChE Handbook 7th Ed pg. 11-21

Economical Diameter of the Tube for shop fabrication = 25.4 mm = 1 in BWG

Diameter of the Tube =

Length of coil:

From ChE Handbook pg. 11-21

Distance of coil from the tank wall (dc) = 6in = 0.5 ft = 0.15 m

352

Total Volume of Tank, VT:

353

Insulation Design:

From ChE Handbook, 8th Ed, p 2-459

For Calcium Silicate:

ri

ro

354

SPECIFICATION SHEET IDENTIFICATION Name of Equipment Pervaporator Equipment Code PV – 1 Number of Unit/s Required 1

Function To remove water from the Ethyl Acrylate product stream

Operation Continuous Type Tubular

Materials Handled Ethyl Acrylate, Acrylic Acid, Ethanol, Water

DESIGN DATA Capacity 14.39 m3/hr Operating Pressure 10 bar Transmembrane Pressure 0.25 bar Power Requirement 7 HP MEMBRANE DESIGN

Membrane Material Polyvinyl Alcohol (PVA) Thickness 25 µm Nominal Pore Size Non-Porous Total Membrane Area 381.3 m2

MODULE DESIGN

Module Type MO 63G_I10HD V Berghof HyperFlux Tubular Module

Material of Construction Fiber Reinforced Plastic (FRP), Resin Membrane Area/module 12.2 m2

Length 3 m Outer Diameter of Module 156.4 mm Internal Diameter of Tube 10.3 mm No. of Tubes/module 72 Tube Arrangement Triangular Pitch Total Number of Modules Required 32 Module Connection Parallel Module Arrangement 32 rows Feed-Permeate Differential Pressure -0.20...+10 bar Pressure Drop along Module 3.48 bar

355

MODULE CONNECTIONS DESIGN DUMMY Diameter 156.4 mm Length 3 m No. of Dummy Required 32 BEND VICTAULIC CONNECTION NO. 3006305 Diameter 168.3 mm Thickness 3 mm Center Distance 458 mm Length 363 mm Material Stainless Steel 1.4571 No. of Bends Required 32 PERMEATE CONNECTION VICTAULIC-CLAMP WITH FLASH GAP SEALING Diameter 60.3 mm Socket 50 mm Length 1 58 mm Length 2 57 mm

Material Polyvinyl Chloride-Unplasticised (PVC-U)

No. of Permeate Connections Required 64 INLET-OUTLET CONNECTION VICTAULIC-CLAMP WITH FLASH GAP SEALING Diameter 168.3 mm Thickness 3 mm Length 200 mm Material Stainless Steel 1.4571 No. of Inlet-Outlet Connection Required 128

MODULE FIXING PARTS DESIGN STRAP Clear Height 230 mm Inner Width 163 mm Thread Length 80 mm Thread M8 Material Stainless Steel 1.4301 No. of Strap Required 192 SADDLE Broadth 20 mm

356

Bore 10 mm Height 20 mm Module Center Height 90 mm Length 200 mm Distance 170 mm Material Polypropylene (PP) No. of Saddles Required 192

357

Cutaway of the MO 63G_I10HD V Berghof HyperFlux Tubular Module

One Unit Module Assembly Overview

358

359

Module Design: Using commercially available MO 63G_I10HD V Berghof HyperFlux Tubular Module from Berghof Filtration and Plant Engineering Data Sheets:

Dummy Design:

360

Inlet-/Outlet Connection Design:

Permeate Connection Design:

361

Bend Design:

Module Fixing Parts Design: Strap:

362

Saddle:

363

Detailed Computations:

Materials Handled:

Quantity (kg) Feed Permeate Retentate

Ethyl Acrylate 18895.35 0 18895.35

Acrylic Acid 137.38 0 137.38

Water 5548.51 5548.51 0

Ethanol 87.84 0 87.84

Total 24669.08 5548.51 19120.57

Temperature (°C) 100 100 100

Pressure (atm) 1 0.1332 1

Feed:

Substance Size (nm)

Molecular Weight (kg/kgmol)

Density (kg/m3)

Volume (m3)

Mass (kg) Mass Fraction (Xi)

Ethyl Acrylate

45 100.08 920 20.54 18895.35 0.7660

Acrylic Acid

35 72.04 1050 0.1308 137.38 0.0056

Water 0.275 18.02 1000 5.549 5548.51 0.2249 Ethanol 0.44 46.06 790 0.1112 87.84 0.003561 TOTAL 936.96 26.33 24669.08 1

364

Permeate:

Substance Size (nm)


Density (kg/m3)

Volume (m3)


Water 0.275 18.02 1000 5.549 5548.51 1

Retentate:

Substance Size (nm)


Density (kg/m3)

Volume (m3)


Ethyl Acrylate

45 100.08 920 20.54 18895.35 0.9882

Acrylic Acid

35 72.04 1050 0.1308 137.38 0.007185

Ethanol 0.44 46.06 790 0.1112 87.84 0.004594 TOTAL 920.12 20.78 19120.57 1

To solve for Diffusivity:

Unit Operation of ChE, McCabe and Smith, Equation 30.55, p. 1041, 7th Edition

Where: Dv = diffusivity

T = temperature (K)

= radius of particles (cm) = 45 nm ≈ 4.5x10-6 cm

μ’ = viscosity (cP) = 0.6406 cP

365

To solve for Reynolds Number:

Unit Operations of ChE, McCabe and Smith, Equation 3.8, p. 59, 5th Ed.

To solve for Schmidt Number:

Unit Operation of ChE, McCabe and Smith, Equation 3.10, p. 53, 7th Edition

7216.23

366

To solve for Sherwood Number (for high Schmidt Number)

Unit Operations of ChE, McCabe and Smith, Equation 17.71, p. 545, 7th Edition

48,157.45

To solve for Mass Transfer Coefficient (Kc):


Where:


D = diameter of tube

Dv = diffusivity

367

To solve for permeate flux (u):


Where: J = permeate flux


C1 = concentration of EA at retentate

Cs = concentration of EA at feed

For Cs (from material balance):

For C1:

368

Table: Conversion factors for Permeate flux

m/s m/h L/m2-h Gal/ft2-day

2.78 x 10-7 10-3 1 0.589

4.72 x 10-7 1.698 x 10-3 1.698 1

369

To solve for Permeability (Qm):

Unit Operations of Chemical Engineering, McCabe and Smith, Equation 30.49, p.

1037, 5th Edition:

Where:

J = permeate flux

Qm = membrane permeability

ΔP = transmembrane pressure

Transmembrane Pressure (ΔP):

Using Raoult’s Law:

At feed:

At permeate:

370

Permeability (Qm):

Unit Operations of Chemical Engineering, McCabe and Smith, Equation 30.49, p.

1037, 5th Edition:

To solve for Area of the Membrane:

Operating time: 110 min 1.83 h ; (from Time-Dependence of Pervaporation

Performance for the Separation of Ethanol/Water Mixtures through Polyvinyl

Alcohol Membrane, by Gewei Li, Wei Zhang, Juping Yang, Xinping Wang)

371

Module Design:

Using commercially available MO 63G_I10HD V Berghof HyperFlux Tubular

Module from Berghof Filtration and Plant Engineering:

ID = 0.0103 m

L = 3 m

l =

Amodule = 12.2 m2

To Solve for Number of Modules:

To solve for Pressure Drop along Module:

372

From Berghof HyperFlux Tubular Module Data Sheet:

where:

Pressure Drop along Module = [kPa]

v =Cross Flow Velocity [m/s]

L = Module Length [m]

373

TYPE OF PUMP:

Based on Membrane Filtration Handbook, the recommended pump for

operating pressures up to 15 bar is a centrifugal pump made of stainless steel. It is

also compatible with a wide range of capacities including .

To solve for Power Requirement:

From ChE Handbook 7th Edition, p. 10-23 Equation 10-50:

Where: H =

Q =

For a pump efficiency of 70%, the actual power is:

374

CHAPTER VII

COST ESTIMATION

375

CHAPTER VII

COST ESTIMATION

I. INTRODUCTION

A project to be feasible must present a process that yields a profit. The

different types of cost involved in manufacturing processes should be studied well

so that the proposal will be acceptable. It is very important to estimate the total

expenses and the total revenue for a project that has a small amount of investment

but has a large amount of profit thereafter. The main goal is to maximize the profit

but not at the expense of the quality. Large amount of capital is required to

purchase the necessary equipments, land and service facilities, as well as piping

and process controllers, for a plant to operate. Herewith, the cost estimation

presents the detailed estimation in establishing a feasible Ethyl Acrylate

Manufacturing Plant which uses glycerol as major raw material. Detailed

computations of investment cost and operational cost were shown here.

A. Total Capital Investment

For a plant capacity of 5,700 MT/year, operating at 24 hours a day and 300

days a year, Total Capital Investment amounts to about PhP 331.43 M. The Fixed

Capital Investment is determined from the Direct Capital Investment which

includes 15.95% (PhP 52.87 M) purchased equipment delivered, 7.50% (PhP

376

24.85 M) installation, 5.74% (PhP 19.03 M) instrumentation and control, 10.85%

(PhP 35.95 M) piping system, 2.87% (PhP 9.52 M) building, 1.75% (PhP 5.82 M)

electrical system, 1.60% (PhP 5.29 M) yard improvement and 11.17% (PhP 37.01

M) service facilities. The Fixed Capital Investment (FCI) which represents the

amount necessary for the complete cost and installation of the process equipment

is computed based on the five major equipments being designed in the previous

chapter, namely: dehydration reactor, heat exchanger, absorption column,

esterification reactor and pervaporator. It is assumed that the cost of these five

equipments represent 45.45 percent of the total equipment cost of the entire plant.

Also, the working capital that is necessary to finance the plant operations is

computed and added to the fixed capital investment to get the Total Capital

Investment.

Thus, in this design:

Fixed Capital Investment = PhP 266,474,677.25

Working Capital = PhP 64,952,672.24

Total Capital Investment = PhP 331,427,349.49

377

B. Total Production Cost

It is then necessary to determine the total production cost per kilogram of

the product to see if the given design will yield a considerable amount of profit.

The total production cost is determined from the manufacturing cost which

includes the variable production cost, fixed charges, and plant overhead cost, and

the general expenses.

Manufacturing Cost = PhP 45.73/kg EA

General Expenses = PhP 9.48/kg EA

Total Production Cost = PhP 55.21/kg EA

378

Equations:

Fixed Capital Investment (FCI) = Direct Production Cost + Indirect Production

Cost

(Plant Design and Economics for Chemical Engineers, Peters et. al., 5th ed.,

p.233)

Total Capital Investment = Fixed Capital Investment + Working Capital


p.232)

A. Manufacturing Cost = Direct Production Cost + Fixed Charges + Plant

Overhead Cost


p.262)

B. Total Production Cost = Manufacturing Cost + General Expenses


p.259)

C. Marshall and Swift Equipment Cost Index

From Chemical Engineering Journal, April 2012 issue

MSI for Process Equipment (4th Quarter 2011) = 1,597.70

379

MSI for Process Equipment (2002) = 1,104.20

From Plant Design and Economics for Chemical Engineers by Peters and

Timmerhaus, 5th Edition, Table 6-2, page 238

MSI for Process Equipment (2000) = 1,089.00

D. From Manila Bulletin, August 15, 2012

1 US$ = PhP 41.94 ≈ PhP 42.00

380

II. ESTIMATION OF CAPITAL INVESTMENT

Plant Capacity : 5,700 MT /yr

Plant Operation : 24 hrs /day

Dollar Exchange : US$ 1.00 ≈ PhP 42.00

% COST (PhP) EXHIBIT

A. Direct Costs

Purchased Equipment Delivered 15.95 52,871,959.77 A

Installation 7.50 24,849,821.09 B

Instrumentation and Control 5.74 19,033,905.52 C

Piping System 10.85 35,952,932.65 D

Building 2.87 9,516,952.76 E

Electrical System 1.75 5,815,915.58 F

Yard Improvement 1.60 5,287,195.98 G

Service Facilities 11.17 37,010,371.84 H

TOTAL DIRECT COSTS 57.43 190,339,055.18

B. Indirect Costs

Engineering and Supervision 5.26 17,447,746.73 I

Construction Expenses 6.54 21,677,503.51 J

Legal Expenses 0.64 2,114,878.39 K

Constructor’s Fee 3.51 11,631,831.15 L

Contingency 7.02 23,263,662.30 M

TOTAL INDIRECT COSTS 22.97 76,135,622.07

FIXED CAPITAL INVESTMENT 80.40 266,474,677.25

WORKING CAPITAL 19.60 64,952,672.24 N

TOTAL CAPITAL INVESTMENT 100.00 331,427,349.49

381

III. ESTIMATION OF PRODUCT COST

Plant Capacity : 5,700 MT /yr

Plant Operation : 24 hrs /day

Dollar Exchange : US$ 1.00 ≈ PhP 42.00

% COST PRODUCTION

(PhP/kg EA)

EXHIBIT

I. MANUFACTURING COST

A. Direct Production Cost AA

Raw Material 59.05 32.60

Operating Labor 0.66 0.37

Direct Supervisory and Clerical Labor 0.10 0.06

Utilities 9.09 5.02

Maintenance and Repair 5.08 2.80

Operating Supplies 0.76 0.42

Laboratory Charges 0.10 0.06

TOTAL DIRECT PRODUCTION

COST

74.85 41.32

B. Fixed Charges BB

Depreciation 1.77 0.9764

Local Taxes 2.12 1.17

Insurance 0.59 0.33

TOTAL FIXED CHARGES 4.48 2.47

C. Plant Overhead Cost 3.51 1.94 CC

MANUFACTURING COST 82.83 45.73

II. GENERAL EXPENSES DD

Administrative Cost 1.17 0.65

Distribution and Marketing 11.00 6.07

Research and Development 5.00 2.76

GENERAL EXPENSES 17.17 9.48

TOTAL PRODUCTION COST 100.00 55.21

382

EXHIBIT A

TOTAL COST OF PURCHASED EQUIPMENT

Schedule

Dehydration Reactor PhP 10,838,176.18 A-1

Heat Exchanger PhP 32,474.30 A-2

Absorption Column PhP 2,931,380.70 A-3

Esterification Reactor PhP 2,370,071.18 A-4

Pervaporator PhP 3,052,142.21 A-5

Total PhP 19,224,244.57

Assuming that the cost of five equipment is 45.45% of the Total equipment cost,

(Basis of Assumption: We designed 5 (1 unit of R-1, 1 unit of H-1, 1 unit of A-1, 1

unit of R-3 and 1 unit of PV-1) out of 11 or about 45.45 % of the total equipment

but most of them are the expensive ones)

Total Cost of Purchased Equipment (Delivered)

Using 25% delivery cost

383

SCHEDULE A-1

Equipment : DEHYDRATION REACTOR

Equipment Code : R-1

Type : Fixed Bed Reactor

Material of Construction : S31600

• From Equipment Design

Design Capacity

Diameter = 1.1 m

Height = 4.30 m

Mass of Catalyst Bed = 8,869.57 kg

Composition: 9.3 wt% WO3; 90.7 wt% ZrO2

• Present cost

Cost of Vessel (Packed):

For Stainless Steel:

For Diameter = 1.1 m

(PD & E Peters & Timmerhaus 5th Ed.; Figure 15-16; p. 796)

384

For Diameter= 1.1 m; Height = 4.30 m

Cost of Catalyst Bed:

For WO3:

For ZrO2:

(ProChem, Inc., Retrieved from http://www.prochemonline.com/)

Present FOB Cost of R-1 in Philippine Currency:

= PhP 10,838,176.18

385

SCHEDULE A-2

Equipment : HEAT EXCHANGER

Equipment Code : H-1

Type : Shell and Tube Heat Exchanger

Material of Construction

Shell : G10200

Tube : S50200


Tube Diameter = 0.016 m

Heating Surface = 4.70 m2

Present cost

For Tube Diameter = 0.016 m


For Carbon Steel Shell & Stainless Steel Tube:

Material Adjustment Factor = 1.70


386

For Heating Surface = 4.70 m2

Present FOB Cost of H-1 in Philippine Currency:

= PhP 32,474.30

387

SCHEDULE A-3

Equipment : ABSORPTION COLUMN

Equipment Code : A-1

Type : Tray Column


Tray : S31600

Column : S31600


Diameter = 1.5 m

Height = 3.5 m

No. of Trays = 5

Present cost

Cost of Column:

For Height = 3.5 m

Diameter = 1 m

388

For 316 Stainless Steel:

Material Adjustment Factor = 3.0


Cost of Trays:

For Sieve Tray (Stainless Steel):

Diameter = 1.5 m

For 5 trays:

Quantity Factor = 2.30


389

Present FOB Cost of A-1 in Philippine Currency:

= PhP 2,931,380.70

390

SCHEDULE A-4

Equipment : ESTERIFICATION REACTOR

Equipment Code : R-3

Type : Stirred Reactor

Material of Construction : S31600


Power Consumption = 13 HP

Present cost

For Double-arm sigma mixers:

Power Consumption = 13 HP

(PD & E Peters &Timmerhaus 5th Ed.; Figure 13-14; p. 627)

Present FOB Cost of R-3 in Philippine Currency:

= PhP 2,370,071.18

391

SCHEDULE A-5

Equipment : PERVAPORATOR

Equipment Code : PV-1

Type : Tubular


Membrane Material : Polyvinyl Alcohol

Module : Fiber Reinforced Plastic (FRP), Resin


Total Membrane Area = 381.30 m2

Present cost

For Membrane Area =1 m2

Typical investment in a complete system, including pumps, tubes,

membranes and controls

(Membrane Filtration Handbook; Table 37; p. 117)

392

Present FOB Cost of PV-1 in Philippine Currency:

=PhP 3,052,142.21

393

EXHIBIT B

Installation Cost

Installation of process equipment includes the cost of labor. The

foundations support platforms, constructions related expenses and other factors

related to the erection of the purchase equipment are part of the estimation of the

installation cost.

47% (Purchased Equipment Delivered) from P&T, Table 6-9, Fluid

Processing Plant, p. 251

Installation Cost = 0.47 (PhP 52,871,959.77)

= PhP 24,849,821.09

394

EXHIBIT C

Instrumentation and Control Cost

Instrumentation and control involves the installation labor cost and

purchase of auxiliary machines used for the control of equipment. Auxiliary

equipment involves the pressure and temperature and flow controller of the plant.



Instrumentation and Control Cost = 0.36 (PhP 52,871,959.77)

= PhP 19,033,905.52

395

EXHIBIT D

Piping (Installed)

The piping cost covers the cost of labor in its installation, cost of pipes,

valves, fittings and all other piping related requirement for the piping erection of

the facility.



Piping, Installed = 0.68 (PhP 52,871,959.77)

= PhP 35,952,932.65

396

EXHIBIT E

Buildings (Including Services)

Cost of buildings includes the cost of installation for the erection of

administrative offices the cost of plumbing, heating, lighting ventilation and other

similar services.



Buildings (Including Services) = 0.18 (PhP 52,871,959.77)

= PhP 9,516,952.76

397

EXHIBIT F

Electrical Systems (Installed)

The electrical system consists of four major components namely, power

wiring, lighting, transformation and service and instrument and control wiring.



Electrical Systems (Installed) = 0.11 (PhP 52,871,959.77)

= PhP 5,815,915.58

398

EXHIBIT G

Yard Improvement

Yard improvements includes the fencing, grading, roads, sidewalks,

railroad sidings, landscaping and any other similar items related to yard

improvements.



Yard Improvement = 0.10 (PhP 52,871,959.77)

= PhP 5,287,195.98

399

EXHIBIT H

Service Facilities

This includes the utilities for supplying steam, water, power, and fuel for

the chemical processes and operations. Waste disposal, fire protection and

miscellaneous service items such as shops, clinics or first aid quarters and

cafeterias require capital investment that are included under general heading of

service facilities.



Service Facilities = 0.70 (PhP 52,871,959.77)

= PhP 37,010,371.84

400

EXHIBIT I

Engineering and Supervision

The cost for construction design and engineering, including internal or

licensed software, computer-aided drafts, purchasing, accounting, travel, and the

plant supervisory services must be part of the capital investment.



Engineering and Supervision = 0.33 (PhP 52,871,959.77)

= PhP 17,447,746.73

401

EXHIBIT J

Construction Expenses

This includes construction labor and other construction related expenses,

construction tools and rentals, construction payroll, construction tariffs, insurance

and permits, miscellaneous equipment installation and other fees related to

construction process.



Construction Expenses = 0.41 (PhP 52,871,959.77)

= PhP 21,677,503.51

402

EXHIBIT K

Legal Expenses

Legal costs refer mostly to the processing of land purchase, equipment

purchase and construction contracts. Understanding and proving compliance with

the government, environmental and safety requirements constitute major sources

of legal cost.



Legal Expenses = 0.04 (PhP 52,871,959.77)

= PhP 2,114,878.39

403

EXHIBIT L

Contractor’s Fee

The contractor’s fee is the payment involve for the construction contract

and other related charges.



Contractor’s Fee = 0.22 (PhP 52,871,959.77)

= PhP 11,631,831.15

404

EXHIBIT M

Contingency

A contingency amount is included in the estimation of the project cost in

recognition of the fact of the occurrence in the unexpected events and charges that

inevitable increase the cost of the project. Events such as storms, flood,

transportation accidents, strikes, price changes, errors of the estimation and

unforeseen expenses may occur as such, it should have its own appropriation.



Contingency = 0.44 (PhP 52,871,959.77)

= PhP 23,263,662.30

405

EXHIBIT N

WORKING CAPITAL

The Working Capital for an Industrial plant consist of the total amount of

money invested in (1) Raw Materials (2) Finished Products (3) Cash on Hand for

Operating Expenses (4) Accounts Receivable (5) Accounts and Taxes Payable.

Working Capital = RAW MATERIALS + LABOR COST + UTILITIES

Schedule

Raw Material PhP 55,744,433.64 N-1

Labor PhP 627,210.00 N-2

Utilities

A. Water PhP 655,365.47 N-3

B. Steam PhP 6,886,730.34 N-4

C. Electricity PhP 1,038,932.79 N-5

Total PhP 64,952,672.24

TOTAL WORKING CAPITAL = PhP 64,952,672.24

406

SCHEDULE N-1

RAW MATERIAL

Raw material that is used in the process is one of the major costs in a

production operation. Raw materials refer in general to those materials that are

directly consumed in making the final product; this includes chemical reactants,

and constituents and additives included in the product.

Crude Glycerol

Price: PhP 9.03/kg glycerol

(PHP 12.90/kg for Refined Glycerol, assume price of raw glycerol is 30%

lower.)

Supplier: ChemSynergy Asia, Inc. (Manufacturer) – Philippines

Cost of Glycerol:

= PhP 27,631,800.00

Ethanol (99.9 wt %)

Price: PhP 35.56/kg ethanol

(Reference: Platts Energy News, Prices & Data; Lower domestic output

from Philippines pushes Asian ethanol prices higher, Retrieved from

http://www.

platts.com/RSSFeedDetailedNews/RSSFeed/Petrochemicals/7948330)

Cost of Ethanol:

= PhP 28,112,633.64

Total Raw Materials Cost = PhP 55,744,433.64

407

SCHEDULE N-2

Operating Labor

Estimating labor requirements as a function of plant capacity is based on

adding the various principal processing steps on the flow sheet. In this method, a

process step is defined as any unit operation or unit process, unit process, or

combination thereof that takes place in one or more units of grinding, extracting,

fermenting, filtering, distilling etc.

Plant Capacity per day = 19,000 kg Ethyl Acrylate

Using Fig. 6 – 9 Peters & Timmerhaus, 5th ed. (Line C: Large Equipment, highly

automated or fluid processing only):

Number of Process steps = 6

(Reference: http://www.nwpc.dole.gov.ph/pages/ncr/cmwr_table.html)

Operating Labor = PhP 627,210.00

408

SCHEDULE N-3

UTILITIES

The cost for utilities, such as steam, electricity and cooling water varies

widely depending on the amount needed plant location and source.

Water

Cost: PhP 20.16/m3 H2O

(Reference: http://122.54.214.222/waterrates/RatesTable.asp)

From Material Balance and Energy Balance:

Equipment Water Required/day

Heat Exchanger (H-1) 28,432.74 kg

Absorption Column (A-1) 16,000.00 kg

Oxidation Reactor (R-2) 184,972.63 kg

Condenser (C-1) 81,722.91 kg



Total 361,202.31 kg

409

SCHEDULE N-4

UTILITIES

Steam


Equipment Steam Required/day

Glycerol Preheater (B-1) 49,776.18 kg

Acrolein Preheater (B-2) 1,955.53 kg

Esterification Reactor (R-3) 1,040.17 kg

Total 52,771.88 kg

Depreciable Boiler Cost

For Steam capacity of 1 kg/s and pressure of 1,825 kPa:

(PD & E Peters & Timmerhaus 5th Ed.; Figure B-3; p. 892)

For Industrial Steam Generation,

(PD & E Peters & Timmerhaus 5th Ed.; Table 7-8; p. 310)

410

Power Generation Cost

For Capacity = 1 kg/s

(Efficiency = 60%)

(Reference: Hurst Boiler and Welding Company, Inc.)

Meralco Rate: PhP 10.8578/kw-hr (Industrial consumer)

(Reference: http://meralco.com.ph/pdf/newsandupdates/2012

/NW00112.pdf)

Fuel Cost

For Bunker C Fuel Oil:

(Reference: http://www.engineeringtoolbox.com/fuel-oil-combustion-

values-d_509.html)

411

(Reference: Pilipinas Shell Petroleum Corporation)


Then,

412

SCHEDULE N-5

Electricity


(Reference: http://meralco.com.ph/pdf/newsandupdates/2012

/NW00112.pdf)

1. Dehydration Reactor: P = 1.5 HP ≈ 1.1185 kW

Operating Time = 24 hrs/day

= PhP 26,232.01

2. Heat Exchanger: P = 4 HP ≈ 2.9828 kW


= PhP 69,955.16

3. Absorption Column: P = 1.5 HP ≈ 1.1185 kW

Operating Time = 24 hrs/ day

= PhP 26,232.01

413

4. Esterification Reactor: P = 13 HP ≈ 9.6941 kW


= PhP 227,354.25

5. Pervaporator: P = 7 HP ≈ 5.2199 kW


= PhP 122,421.52

Assuming that the Electricity Cost of five equipments is 45.45% of the Total

Electricity Cost,

414

EXHIBIT AA

DIRECT PRODUCTION COST

Cost (PhP) / kg EA Schedule

Raw Material PhP 32.60 AA-1

Operating Labor PhP 0.37 AA-2

Direct Supervisory and Clerical

Labor

PhP 0.06 AA-3

Utilities PhP 5.02 AA-4

Maintenance and Repair PhP 2.80 AA-5

Operating Supplies PhP 0.42 AA-6

Laboratory Charges PhP 0.06 AA-7

Total PhP 41.32

TOTAL DIRECT PRODUCTION COST = PhP 41.32/kg EA

415

SCHEDULE AA-1

Raw Material

Crude Glycerol

Price: PhP 9.03/kg glycerol

(PhP 12.90/kg for Refined Glycerol, assume price of raw glycerol is 30%

lower.) Supplier: ChemSynergy Asia, Inc. (Manufacturer) – Philippines

Cost of Glycerol:

= PhP 16.16/ kg EA

Ethanol (99.9 wt %)

Price: PhP 35.56/kg ethanol

(Reference: Platts Energy News, Prices & Data; Lower domestic output

from Philippines pushes Asian ethanol prices higher, Retrieved from

http://www.platts.com/RSSFeedDetailedNews/RSSFeed/Petrochemicals/794

8330)

Cost of Ethanol:

= PhP 16.44/ kg EA

Total Raw Materials Cost = PhP 32.60/ kg EA

416

SCHEDULE AA-2

Operating Labor

Plant Capacity per day = 19,000kg Ethyl Acrylate

Using Fig. 6 – 9 Peters & Timmerhaus, 5th ed. (Line C: Large Equipment,

highly automated or fluid processing only)

Number of Process steps = 6

(http://blog.pinoydeal.ph/pinoydeal/2011-minimum-wage-rates)

Operating Labor = PHP 0.37/kg EA

417

SCHEDULE AA-3

Direct Supervisory and Clerical Labor

In a manufacturing operation, a certain amount of direct supervisory and

clerical assistance is always required. The necessary amount of this type of labor is

closely related to the total amount of operating labor, complexity of the operation,

and product quality standards. The cost for direct supervisory and clerical labor

averages about 15 percent of the cost for operating labor.

15% (Operating Labor) from Peter and Timmerhaus, 5th Ed.

418

SCHEDULE AA-4

Utilities

A. Total Water Cost PhP 0.38/kg EA

B. Total Steam Cost PhP 4.03/kg EA

C. Total Electricity Cost PhP 0.6076/kg EA

Total Utilities Cost PhP 5.02/kg EA

A. Total Water Cost

Cost: PhP 20.16/m3 H2O

(Reference: http://122.54.214.222/waterrates/RatesTable.asp)

From Material and Energy Balance

Equipment Water Required/day


Absorption Column (A-1) 16,000.00 kg

Oxidation Reactor (R-2) 184,972.63 kg




Total 361,202.31 kg

419

420

B. Total Steam Cost

Cost: PhP 1.45/kg steam

(Steam Cost Computation, refer to page 298)

From Energy Balance:

Equipment Steam Required/day

Glycerol Preheater (B-1) 49,776.18 kg

Acrolein Preheater (B-2) 1,955.53 kg

Esterification Reactor (R-3) 1,040.17 kg

Total 52,771.88 kg

421

C. Total Electricity Cost


(Reference: http://meralco.com.ph/pdf/newsandupdates/2012/

NW00112.pdf)

1. Dehydration Reactor: P = 1.5 HP ≈ 1.1185 kW


= PhP 0.0153/kg EA

2. Heat Exchanger: P = 4 HP ≈ 2.9828 kW


= PhP 0.0409/kg EA

3. Absorption Column: P = 1.5 HP ≈ 1.1185 kW

Operating Time = 24 hrs/ day

= PhP 0.0153/kg EA

422

4. Esterification Reactor: P = 13 HP ≈ 9.6941 kW


= PhP 0.1330/kg EA

5. Pervaporator: P = 7 HP ≈ 5.2199 kW


= PhP 0.0716/kg EA

Assuming that the Electricity Cost of three equipments is 45.45% of the Total

Electricity cost,

423

SCHEDULE AA-5

MAINTENANCE AND REPAIR

Annual cost for equipment maintenance and repairs may range from 2% –

20% of the equipment cost. Charges for plant buildings average 3% - 4% of the

building cost. The total plant cost per year for maintenance and repairs ranges

from 2% to 10% of the fixed capital investment.

6% (Fixed Capital Investment) from Peter and Timmerhaus, 5th Ed.

424

SCHEDULE AA-6

Operating Supplies

In any manufacturing operation, many miscellaneous suppliers are needed

to keep the process functioning efficiently. These are not considered raw materials

or maintenance and repair material but as operating supplies. Some of these items

include charts, lubricants, test chemicals and custodial supplies. The annual cost

for these types is about 15% of the total cost of maintenance and repair.

15% (Maintenance and Repair) from Peter and Timmerhaus, 5th Ed.

425

SCHEDULE AA-7

Laboratory Charges

These include the costs of laboratory tests for control of operations and for

product quality control. This cost may be taken as 15% of the operating labor.

15% (Operating Labor) from Peter and Timmerhaus, 5th Ed.

426

EXHIBIT BB

FIXED CHARGES


Depreciation PhP 0.98 BB-1

Local Taxes PhP 1.17 BB-2

Insurance PhP 0.33 BB-3

Total PhP 2.47

TOTAL FIXED CHARGES = PhP 2.47/kg EA

427

SCHEDULE BB-1

Depreciation

The equipment, buildings and other material objects comprising a

manufacturing plant require an initial investment that must be paid back and this is

done by charging depreciation as a manufacturing expense. Depreciation rates are

very important in determining the amount of income tax.

Using Straight-Line Method:

Where: V = the original investment in the property at the start of the

recovery period

= the total purchase equipment cost delivered

= PhP 52,871,959.77

n = length of the straight-line recovery period

= 9.5 years, Manufacture of chemicals and allied products

(Table 7-8 of Peters and Timmerhaus 5th ed., p. 310)

428

SCHEDULE BB-2

Local Taxes

The magnitude of local property taxes depends on the particular locality of

the plant and the regional laws. Annual property taxes for plants in highly

populated areas are ordinarily in the range of 2% - 4% of the fixed capital

investment.

2.5% (Fixed Capital Investment) from Peter and Timmerhaus, 5th Ed.

429

SCHEDULE BB-3

Insurance

Insurance rate depends on the type of process being carried out in the

manufacturing operation and on the extent of available protection facilities. These

rates amount to about 0.7% of the fixed capital investment per year.

0.7% (Fixed Capital Investment) from Peter and Timmerhaus, 5th Ed.

430

EXHIBIT CC

PLANT OVERHEAD COST

In plant overhead costs, the expenditure required for routine plant services.

Non – manufacturing machinery, equipment, and buildings are necessary for many

of the general plant services, and the fixed charges and direct cost for these items

are part of the plant overhead cost.

60% (O.L. + Supervisory + M and R) from Peter and Timmerhaus, 5th Ed.

431

EXHIBIT DD

GENERAL EXPENSES

General expenses constitutes mainly of indirect cost on production. It

includes Administrative Costs, Product distribution and as well as expenses for

Research and development.

From Plant Design and Economics by Peters and Timmerhaus, General

expenses comprise for the 15-25% of the total product cost.


Administrative Cost PhP 0.65 DD-1

Distribution and Marketing PhP 6.07 DD-2

Research and Development PhP 2.76 DD-3

Total PhP 9.48

TOTAL GENERAL EXPENSES = PhP 9.48/kg EA

432

SCHEDULE DD-1

Administrative Cost

Salaries and wages for administrator, secretaries, accountants, computer

support staff, engineering and legal personnel are part of the administrative

expenses, along with cost for office supplies and equipment, outside

communications, administrative buildings and other overhead items related to

administrative activities.

20% (O.L. + Supervisory + M and R) from Peter and Timmerhaus, 5th Ed.

433

SCHEDULE DD-2

Distribution and Marketing Cost

Salaries, wages, supplies and other expenses for sales offices, commissions

and travelling expenses for sales representatives, shipping expenses, cost of

containers advertising expenses and technical sales services are included in this

category.

11% (Total Product Cost) from Peter and Timmerhaus, 5th Ed.

TPC = Manufacturing Cost + Administrative Cost + Distribution and

Marketing + Research and Development

434

SCHEDULE DD-3

Research and Development

Research and development costs include salaries and wages for all

personnel directly connected with this type of work, fixed and operating expenses

for all machinery and equipment involved, cost for materials and supplies and

consultant’s fee.

5% (Total Product Cost) from Peter and Timmerhaus, 5th Ed.

435

CHAPTER VIII

ECONOMIC

EVALUATION

436

CHAPTER VIII

ECONOMIC EVALUATION

I. INTRODUCTION

Whenever a new project is to be considered, it requires a commitment of

capital funds also known as investment. Whenever investment is to be made to a

certain project, it is important to evaluate the profitability of the project since the

main purpose of the investments is to generate income. Total profit alone cannot

be used as basis whether the project is profitable or not. If the goal of an

investment is to merely earn a profit, any investment that gives profit would be

acceptable regardless of how much and how long the return of the investment

would be. The objective of the profitability analysis is to give a measure of the

attractiveness or possibility of the project for possible course of action. It is

therefore important to consider the profitability analysis method to be used in

order to give a reliable measure of the economic feasibility of the project.

There are various methods that can be used in determining the profitability.

These methods are divided into those that consider the time value of money and

those that are not. Methods that do not consider the time value of money includes:

a) Rate of Return on Investment (ROI), b) Payback Period, c) Net Return. The

methods that consider the time value of money are a) Discounted Cash Flow Rate

of Return, and b) Net Present Worth. In this study, the methods used in

437

profitability analysis are the Rate of Return on Investment and Net Present Worth.

Break Even analysis is also presented on the latter part of this chapter.

II. Analysis and Interpretation

At present time, there is no existing plant of Ethyl Acrylate in the country.

For the purpose of economic evaluation of the project, the international market

price is considered. The international market price of ethyl acrylate (Reference:

ICIS Pricing) is US$ 1,810 per ton or nearly PhP 83.81 per kilogram. The Total

Production Cost (TPC) for the proposed Ethyl Acrylate plant is found to be PhP

55.21 per kilogram. Since the Total Production Cost is lower than the selling price

of the competitor, it is safe to say that the proposed plant will be profitable. Also,

because the product is imported, 10-15% additional cost will be added to the price.

A selling price of PhP 75.00 per kilogram of Ethyl Acrylate is therefore proposed.

It is 10.50% lower than the international market price.

A. Rate of Return on Investment

Using the Rate of Return on Investment as the first method of analysis, we

can be able to determine how fast the return on investment would be. Higher ROI

value is advantageous for the project. Also, the higher the value of ROI, the better

is the project because the faster will be the return on investment of the project.

For a capital investment of PhP 331.43 M and a selling price of PhP 75.00

per kilogram of Ethyl Acrylate, the expected net annual profit amounts to PhP

438

112.82 M. Current loan rate is 18.05% (Reference: Bangko Sentral ng Pilipinas).

In this case, the rate of return on investment is 34.04%, which means that the

project is still profitable but the investment cannot be recovered immediately in

one year of operation of the project.

B. Net Present Worth

In the second method of analysis which is the Net Present Worth method,

the profitability of the project can be evaluated by comparing the net present cash

inflows to the net present outflows. If the net present cash inflows or the net

present worth equivalent of annual profit is higher than the net present worth of

cash outflows or investments, then the net present worth of the project would be

higher than zero indicating that the project is economically profitable. The higher

the value of net present worth the better and more profitable the project is.

For this project, the estimated net annual profit is equal to PhP 112.82 M.

Using 20 years of operation of the plant and a minimum attractive rate of return

(MARR) of 12.50% (Reference: Bangko Sentral ng Pilipinas), the calculated net

present worth of the project is PhP 485.55 M. This is a positive value indicating

that the project is profitable because the net present worth equivalent of the annual

profit is significantly higher than the present worth of investment.

439

C. Break-even Point Analysis

To determine the rate of production of the plant capacity necessary in order

to have a profit, the break-even point analysis must be considered. The production

rate that would give a gross sales equivalent to total production cost is known as

the break-even point because the net profit zero.

The break-even point can be computed by dividing the total fixed cost by

the difference of selling price and total variable cost. From the previous chapter,

the fixed cost and variable cost (Total Direct Production Cost) amounts to PhP

13.89/kg EA and PhP 41.32/kg EA, respectively. Fixed cost comprises of Fixed

Charges, Plant Overhead Cost and General Expenses.

In this case, the calculated percent break-even point is about 41.23%. This

means that the plant should always operate at a production rate higher than

41.23% of the actual plant capacity (5,700 MT EA/yr), corresponding to 2,350 MT

EA/yr, in order to have a net profit. If the plant operated at a rate lower than 2,350

MT EA/yr, the plant will not be profitable on each operation.

440

III. Conclusion

The main objective of this work is to demonstrate the economic advantage

of using glycerol as a major raw material in producing ethyl acrylate.

Based on the analysis, the project would be profitable. This is evident since

the attained net present worth equivalent of the annual profit is a positive value.

Also, the project would yield a high rate of return on investment (34.04%) which

implies that the project is worth investing for.

In conclusion, this plant design would absolutely be economically feasible.

441

IV. Detailed Computations

A. Rate of Return on Investment

Profit Estimation (Z)

Using the equation presented by Peters & Timmerhaus in Plant Design and

Economics for Chemical Engineers:

Where: n = Plant Capacity, kg/yr

Z = Net annual profit, PhP/yr

TCI = Total capital investment

The proposed market price of Ethyl Acrylate is PhP 75.00/kg EA

Plant Capacity is 5,700,000 kg/yr

TPC =PhP 55.21/kg

TCI = PhP 331,427,349.49

442

B. Net Present Worth Calculation

From Bangko Sentral ng Pilipinas, the loan interest for long term period

(more than 5 years) is 12.50%. From Plant Design and Economics for ChE by

Peters & Timmerhaus

Where: PW = present worth equivalent of net annual profit

A = net annual profit

i = annual interest rate

n = period of operation = 20 years

Estimated net annual net profit is PhP 112,821,716.88

Initial investment is PhP 331,427,349.49

443

C. Break-even Point (BEP)

At break-even point, net annual profit (Z) = 0

Where: F = Fixed Cost, PhP/ yr

= Fixed Charges + Plant Overhead Cost + General Expenses

S = Selling Price, PhP/ kg = PhP 75.00/kg EA

V = Variable cost, PhP/kg

From Cost Estimation:

Fixed Charges = PhP 2.47/kg EA

Plant Overhead Cost = PhP 1.94/kg EA

General Expenses = PhP 9.48/kg EA

Variable Cost (Total Direct Cost) = PhP 41.32/kg EA

Documents

Manufacture of Ethyl Acrylate From Glycerol (2012)