Contoh Report Writing

1

CHAPTER I

LITERATURE STUDY: PROCESS BACKGROUND AND SELECTION

1.1 INTRODUCTION OF ACRYLONITRILE

Acrylonitrile is liquid at normal temperatures and pressure and has a faint

characteristic odour. It is one of the most important intermediates in processing of

basic hydrocarbon products to polymer end-products, as illustrated in Figure 1.3.

The chemical formula for acrylonitrile is CH2 = CH C = N. Acrylonitrile has several

synonyms and tradenames including propenenitrile, vinyl cyanide, cyanoethylene,

Acrylon, Carbacryl, Fumigrain, and Ventox. Lewis structure of acrylonitrile is

shown in Figure 1.1 below.

Figure 1.1: Lewis Structure of Acrylonitrile (Source: Wikipedia Foundation Inc.,

2010).

Figure 1.2: Chemical Structure of Acrylonitrile (Source: Wikipedia Foundation Inc.,

2010).

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1.1.1 PHYSICAL AND CHEMICAL PROPERTIES OF ACRYLONITRILE

Selected physical and chemical properties of acrylonitrile are presented in Table 1.1.

Acrylonitrile is relatively volatile with a vapour pressure of 13.3 kPa (1.9 psi) at 25C

(77F) and a boiling point of 77.3C (171.1F). It readily ignites and can form

explosive mixtures with air. In addition, acrylonitrile polymerizes explosively in the

presence of strong alkalinity. Acrylonitrile is photochemically reactive and has an

estimated atmospheric residence time 5.6 days. Atmospheric residence time

represents the time required for a quantity of an individual chemical to be reduced to

1/e (37 percent) of its original value.

Table 1.1: Physical and Chemical Properties of Acrylonitrile

Property Value

Molecular weight 53.06

Boiling point, C 77.3

Freezing point, C - 83.55 + 0.05

Critical pressure, kPa 3536

Critical temperature, C 246

Density at 20 C, g/cm3 0.806

Viscosity, mPa s (or cP) 0.34

Vapour density (theoretical) 1.83 (air = 1.0)

Dielectric constant at 33.5 MHz 38

Dipole moment, cm

(liquid phase) 1.171 x 10-29

(vapour phase) 1.294 x 10-29

Vapour pressure, kPa

8.7 C 6.7

23.6 C 13.3

45.5 C 33.3

64.7 C 66.7

77.3 C 101.3

Explosive limits in air, vol 96 3.05 17.0 + 0.5

Heat of formation of vapour, kJ/mol 185.02

Latent heat of fusion, kJ/mol 6635

Source: U.S Environmental Protection Agency (EPA), 1984.

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Furthermore, the reactions of acrylonitrile which is known as reactive

compound, occurred at its two chemically active sites namely, the nitrile group and

the carbon carbon double bond. Since, acrylonitrile is one of the most important

chemicals in polymer industries, it is readily polymerizes in the absence of

hydroquinone inhibitor, strictly when exposed to light. Theoretically, polymerization

reaction is initiated by free radicals, redox catalysts, or bases and can be carried out

in the liquid, solid, or gas phase. For example, there are two types of products

formed particularly in liquid phase polymerization, which are known as

homopolymers as well as copolymers. Table 1.2 below shows various types of

acrylonitrile reactions by nitrile and carbon carbon double bond categories.

Table 1.2: Various Types of Acrylonitrile Reactions.

Reaction of Nitrile Group Reaction of Carbon Carbon Double

Bond Group

Hydration with sulphuric acid to

form acrylamide sulphate

(C3H5NO.H2SO4), which can

further be converted to

acrylamide (C3H5NO) by

neutralization with base.

Complete hydrolysis to form

acrylic acid.

Partial hydrolysis to form

acrylamide (qv) by using copper

based catalysts.

Diels Alder addition to dienes

to form cyclic products.

Hydrogenation over metal

catalysts to give propionitrile

(C3H5N) and propylamine

(C3H9N).

Hydrodimerization to produce

adiponitrile (C6H8N2).

Addition of halogens to produce

dihalopropionitrile.

Cyanoethylation by acrylonitrile

of alcohols, aldehydes, esters,

amides, nitriles, amines,

sulphides, sulfones, and halides.

Source: John J.McKetta and William A.Cunningham, 1982.

On the other hand, Table 1.3 and Table 1.4 show the descriptions of

thermodynamic data and azeotropes of acrylonitrile respectively. Moreover, Table

1.5 shows the solubilities of acrylonitrile in water for different values of temperature.

Last but not least, Table 1.6 shows acrylonitrile vapour pressure over aqueous

solutions at 25 C.

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Table 1.3: Thermodynamic Data.

Property Value

Autoignition temperature, C 481

Flash point, C 0

Flammability limits in air, 25 C vol%

lower 3.0

upper 17.0

Free energy of formation, Gg , 25 C, kJ/mol 195

Enthalpy of formation, 25 C, kJ/mol

Hg 180

Hl 147

Heat of combustion of liquid, 25 C, kJ/mol 1761.47

Heat of vaporization, 25 C, kJ/mol 32.65

Molar heat capacity of liquid, kJ/(kg - K) 2.09

Molar heat capacity of vapour of 50 C , kJ/(kg - K) 1.204

Molar heat of fusion, kJ/mol 6.61

Entropy of vapour, kJ/mol 274.06


Table 1.4: Azeotropes of Acrylonitrile.

Azeotrope Boiling point, C Acrylonitrile concentration,

wt%

Water 71.0 88

Isopropyl alcohol 71.6 56

Benzene 73.3 47

Methanol 61.4 39

Carbon tetrachloride 66.2 21

Tetrachlorosilane 51.2 11

Chlorotrimethylsilane 57.0 7


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Table 1.5: Solubilities of Acrylonitrile in Water.

Temperature, C Acrylonitrile in water, wt% Water in acrylonitrile, wt%

-50 0.4

-30 1.0

0 7.1 2.1

10 7.2 2.6

20 7.3 3.1

30 7.5 3.9

40 7.9 4.8

50 8.4 6.3

60 9.1 7.7

70 9.9 9.2

80 11.1 10.9


Table 1.6: Acrylonitrile Vapour Pressure over Aqueous Solutions at 25 C.

Acrylonitrile, wt% Vapour pressure, kPa

1 1.3

2 2.9

3 5.3

4 6.9

5 8.4

6 10.0

7 10.9


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Figure 1.3: Pathways from Basic Hydrocarbons to Polymers (Source: Sami Matar and Lewis F. Hatch, 2000).

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1.2 PROCESS BACKGROUND

The task is to design and setting a chemical plant for the production of 100 000

matrix tonne acrylonitrile per year in Malaysia.

1.3 SYNTHESIS OF ACRYLONITRILE

The acrylonitrile can be synthesized by three major routes, which are listed as

follows:

1. Propylene route.

2. Acetylene route.

3. Ethylene route.

The general descriptions as well as brief explanation for each route mentioned

above are discussed in the following sub sections.

1.3.1 PROPYLENE ROUTE

Nowadays, most of acrylonitrile produced via the propylene route, specifically

ammoxidation of propylene. Chemically, ammoxidation is a catalytic oxidative

reaction of activated methyl-groups with ammonia, NH3 to form a nitrile group. On

the other hand, the term ammoxidation is also used to describe the oxidative

amination reaction occurred during that particular process. Acrylonitrile is then

produced from propylene ammoxidation, with the following chemical equation:

H2C=CHCH2 + NH3 + 1.5 O2 H2C=CHCN + 3 H2O

In history, there are basically six types of processes in production of

acrylonitrile, which are also discussed briefly in the following sub sections.

1.3.1.1 SOHIO PROCESS

This kind of process is introduced in nearly 1957 and developed by Sohio

researchers (The Standard Oil Company) lead by John D. Rockefeller. The

company is determined to be a specialist petroleum company and it became part of

the British Petroleum Company P.I.C in 1987.

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It is a single step, direct and heterogeneously - catalyzed process, namely

propylene ammoxidation. The raw materials are refinery grade of propylene with

more than 90% purity, refrigerant grade of ammonia with more than 99.5% purity, as

well as air as the source of oxygen. The raw materials are introduced near

stoichiometric ratio which is 1 / 1.06 / 8.4 for propylene / ammonia / air respectively

(U.S Pat. No: 4 296 046). The vapour - space ammoxidation reaction takes place in

a fluidized bed reactor at approximately 2 atm and 400 - 510C (750 - 950C) in the

presence of catalyst developed by Sohio. The catalyst developments for Sohio

process:

1. Catalyst A (1960): Bi2O3.MoO3.

2. Catalyst 21(1967): UO2.Sb2O3.

3. Catalyst 41(1972): Bi2O3.MoO3 with additives including Fe compounds.

4. Catalyst 49 (1977): Co62Ni22Fe33Bi3(MoO4)12O12.

The composition of this catalyst is described in the patent literature as 70

percent by weight P2O5:Bi2O3:MoO3 in a molar ratio of 1:9:24. The conversion of

propylene in the reactor is essentially complete. The reactions involve in this reactor

are shown below (U.S Pat. No: 4 296 046):

OH3CHCNCHO2

3NHHC1 222363 (Main reaction)

OHCOOHC

OHCOOHC

OHHCNONHHC

OHCNCHONHHC

2263

22263

22363

232363

3

1)5(

2

3

3

1)4(

23

13

23

22

(Side reaction)

The main reaction is highly exothermic with H = 760 kJ/mol, so an

efficient heat removal system is essential by using a set of immersed tubes with

internal boiler feed water circulation which is placed within the catalyst bed reactor.

The selectivity of the main reaction is roughly 86%, while the rest will be the

selectivity of all the side reaction, where propylene is the basis component for both

reactions. The conversion of propylene in both reactions is 98%.

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Generally, unreacted ammonia is then separated from the product stream

using sulphuric acid, H2SO4, resulting in an ammonium sulphate, (NH4)2SO4

solution. Waste gas is incinerated in a power plant. Acrylonitrile, acetonitrile, as well

as hydrogen cyanide (HCN) is separated by a series of separation processes from

the product stream before further being purified. The purified acrylonitrile is then

sent to storage tanks after stabilization.

1.3.1.2 BP (DISTILLERS) UGINE ROUTE

Propylene is oxidized on a Se/CuO catalyst to acrolein, which is then converted into

acrylonitrile in a second stage with NH3 and air over a MoO3 fixed-bed catalyst. This

two-step conversion leads to higher acrylonitrile selectivity of about 90% (based on

H2C=CHCHO). However, it had never been important commercially.

1.3.1.3 MONTEDISON UOP ROUTE

It is a single-step propylene conversion with Te-, Ce-, Mo-oxides catalyst on SiO2.

Propylene is then ammoxidized in a fluidized-bed at 420-460oC. As a result, one

thousand kilograms of acrylonitrile, 50 kg HCN, 25 kg Acetonitrile, and 425 kg

(NH4)2SO4 are obtained from 1200 kg propylene and 560 kg NH3. Further

development by UOP improved the acrylonitrile yield to over 80% at a propylene

conversion of about 95%.

1.3.1.4 SNAMPROGETTI / ANIC ROUTE

The process occurred in a fixed-bed catalyst based on Mo/V or Bi. An amount of

1260 kg of propylene is converted into 1000 kg acrylonitrile, 240 kg HCN, and 25 kg

acetonitrile at 440-470oC and 2 bars.

1.3.1.5 PROPANE ROUTE

This particular route required higher temperatures of 485-520oC, in which propane is

initially dehydrogenated to propene. It is developed by Monsanto, Power Gas, BP,

and ICI. The selectivity is 30%, markedly lower than with direct use of propene.

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1.3.1.6 LUMMUS ROUTE

The manufacturing process is based on propane or propene, NH3 and O2 in a salt

melt such as KCl-CuCl-CuCl2. This process has not been practiced commercially

but the starting of a demonstration plant in 1994 has been announced by BP.

Propane is of particular interest because of a low advantage over propene. But, this

price difference is not likely to be great enough in the near future to dictate change.

1.3.2 ACETYLENE ROUTE

It is a homogeneously-catalyzed hydrocyanation in liquid phase or also known as

Nieuwland system. The catalyst used in this particular reaction is cuprous chloride in

hydrochloric acid (CuCl-NH4Cl). Commercially, the addition of HCN to acetylene

occurred at 80-90oC with a large excess of acetylene, slightly above atmospheric

pressure. The unreacted acetylene was recycled. The chemical equation is as

follows:

HCCH + HCN H2C=CHCN

The reactor effluent is allowed to be cooled and passed into water, whereby

the acrylonitrile is extracted. The acrylonitrile solution is stripped with steam and the

acrylonitrile is purified by passage through a series of columns, the last of which

operates under reduced pressure.

This kind of pathway was developed by Bayer and practiced commercially by

Cyanamid, duPont, Goodrich, Knapsack, and Monsanto.

1.3.3 ETHYLENE ROUTE

In this type of route, ethylene is first converted to ethylene oxide. Then, the process

of base catalyzed addition of HCN to ethylene oxide are occurred to form

intermediate compound of ethylene cyanohydrins, which was then hydrated either in

the liquid phase at 200 oC in the presence of alkali metal or alkaline earth salts. The

alternative condition is such that it also can occur in gas phase at 250 oC - 300 oC

over Al2O3. The route to acrylonitrile is illustrated in Figure 1.4. This kind of route

was developed by IG Farben and operated by UCC from 1952 and by Cyanamid

from 1970.

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H2C=CH2

O2CH2-CH2

OHCN

CH2-CH2

OH CN

-H2OH2C=CH-CN

ethylene ethylene oxide ethylene cyanohydrin

acrylonitrile

Figure 1.4: Ethylene Route to Acrylonitrile (Source: John J.McKetta and William

A.Cunningham, 1982.).

1.4 PROCESS SELECTION

The methodologies to select the best available technique among three routes

discussed in the previous section are by analyzing and comparing the processes

based on several main factors considered in designing a chemical plant. Note that,

for the propylene route method, our concern is towards the Sohio process

(ammoxidation of propylene). The factors are listed as follows:

1. Economical (price for raw material).

2. Environmental and Safety.

3. Nature of Process.

Table 1.7 shows the descriptions of comparison factors for process selection to

produce acrylonitrile. After analyzing and comparing the main factors above, we

decide to select the Sohio process as our route to produce acrylonitrile. This is

because of its substantial advantage in overall production costs, primarily due to

lower raw material costs. Although the catalyst is quite expensive as it is specially

developed by Sohio researchers, but then the beneficial will counter act the higher

cost of catalyst as it catalyzed the ammoxidation reaction with propylene conversion

of 98 % as well as acrylonitrile selectivity of 86 %. Besides that, all raw materials

could also be supplied by many chemical producers in Malaysia. Furthermore,

although it produces significant amounts of highly toxic species form, such as HCN,

acetonitrile and heavy nitrile, but the implementation of efficient treatments will

prevent issues regarding to environment, safety, and health problems. Last but not

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least, this particular process is also the latest process in acrylonitrile industry,

compared to others kind of route, in which the acetylene route is no longer practised

nowadays. On the other hand, although ethylene route able to produce high yield of

acrylonitrile, but the process has been abandoned after 1970 due to hazardous

properties of intermediate products and difficulties to remove its by products as

shown in Table 1.7.

Thus, in view of that situation, and with the factors, advantages, and reasons

discussed above, the Sohio process is selected as our route to produce our high

purities and quality of acrylonitrile.

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Table 1.7: Descriptions of Comparison Factors for Process Selection.

Types of Routes Comparison Factors

Economical

(price for raw material)

Environmental and

Safety

Nature of Process

Sohio process Propylene: RM 3960 per

tonne Cost and Freight

(CFR)

Ammonia: RM 993.19 /

tonne

Oxygen: from air source

Air and water

emissions.

Hazardous by

products.

Solids or liquid

wastes.

Propylene conversion

of 98 %.

Single step reaction.

Acrylonitrile selectivity

of 86 %.

Major by-product: HCN,

Acetonitrile which

beneficial for sale.

Acetylene route Usually HCN is not

selling due to its

hazardous properties.

HCN is hazardous

compound.

Old production process.

No longer practised.

Ethylene route

Ethylene: RM 3271.69 /

tonne

Ethylene oxide is

hazardous

compound as it is

extremely

flammable,

explosive, toxic, and

carcinogen.

After 1970, the process

had been abandoned.

High yield.

Major by-product:

Divinylacetylene and

methyl vinyl ketone,

which difficult to

remove.

Source: ICIS, 2010 and John J.McKetta and William A.Cunningham, 1982.

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1.5 DETAILS OF THE SOHIO PROCESS: PROCESS DESCRIPTION

In this particular section, the details of the Sohio process are discussed, which

covers process descriptions of acrylonitrile production and also a sketch of

designing plant in Process Flow Diagram (PFD).

The raw materials in this process are determined to be propylene as well as

ammonia, in which we decide to purchase them due to the fact that they are widely

available in local market with reasonable prices. On the other hand, the oxygen

supply for the ammoxidation reaction will be also purchased purely from the market

rather than retrieve from the surrounding air. A reasonable benefit of using pure

oxygen is that it can increase reaction rates thus will improve and reduce feedstock

consumption as well as lowering operating cost which thereafter reduce capital

costs especially for new plants. The reasons of not utilize the air surrounding for

reaction process is that the outside air is contaminated with pollutant such as dust or

particulate matter, in which leading to the requirement of purifying the air by filter

equipment. As a result, the operating cost will be sufficiently increased. If the air

filter is not used, then the particulate types of pollutant might give problems to

equipments such as heat exchanger and compressor. Apart from that, there is also

another problem to encounter in terms of environmental consideration by using

surrounding air. Most of air composition consists of nitrogen (79 vol%). The reaction

of nitrogen and oxygen in combustion process later (incineration) will produce

enormous nitrogen dioxide gas (NOx) which is considered as one of major air

pollution. Nitrogen oxides can cause a wide range of environmental and health

problem. This pollutant contributes to the formation of acid rain which therefore can

cause damage to the earth surface. For that reasons, the most preferable approach

is to choose purchased pure oxygen.

Table 1.8 shows more descriptions regarding to the feedstock of the

process.

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Table 1.8: Descriptions of Feedstock.

Feedstock Descriptions

Propylene The Chemical Grade propylene is available at 1 atm. The

component of the propylene will be as follows:

Propylene: 95.0 mol%

Propane: 4.7 mol%

Ethane: 0.3 mol%

Ammonia Ammonia with 99.5 wt% is available as a liquid at 25 psig.

Oxygen Pure oxygen will be purchased.

The catalyst used in order to enhance the rate of ammoxidation reaction in

heterogenous fluidized bed reactor is catalyst 41 which is contains molybdenum or

antimonium oxides mixed with transition metals such as Fe, Ni, Co, and V activated

by alkali and rare earth elements.

The feed of propylene and ammonia are in form of liquid phase whereas

oxygen is in vapour phase. Propylene must be in liquid phase due to the fact that, it

is a double bond and thus unstable and reactive compound, and hence it should be

stored under low pressure and temperature. Propylene (Stream 1) and ammonia

(Stream 2) is mixed by using a mixer (I - 4) together to reduce propylene reactivity

and then increasing the temperature by using a heater (E - 31). Then, the mixture of

propylene and ammonia is compressed (E - 35) before being introduced to reactor

for pressure regulation. On the other hand, oxygen (Stream 3) is heated by a heater

(E-5) and thus compressed by a compressor (E - 36). The reason for not feeding

propylene and ammonia together with stream containing oxygen is that if they were

introduced together the formation of an explosive composition could exist due to the

flammability properties of propylene and ammonia.

After the feed meet with the specification requirement of reaction to occur,

only then the permitted directly into heterogeneous fluidized bed reactor by a ratio

as stated in the literature study of Sohio process. A slight excess of ammonia forces

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the reaction closer to completion and also a slight excess of oxygen continually

regenerates the bed catalyst used in the reaction.

The selection of this type of reactor is based on the excellent uniformity of

temperatures. This is the achievable throughout the bed because of the motion of

the solid and the good heat exchange between solid and gas. The ease of adding

and removing solid is an additional advantage. Hence a fluidized bed reactor is of

value for a very exothermic reaction that cannot be adequately controlled with a

multi-tube reactor, or when catalyst must be removed and replaced frequently. For

a partial oxidation reaction, this kind of reactor also permits a method of readily

introducing oxygen and reactant at different locations in the reactor. A fluid-bed

reactor may be less expensive to construct than multi-tube reactor the same the

capacity, and heat exchange may be simpler than with the adiabatic multi-bed

reactor. However, the hydrodynamics of fluidized beds are complex, scale-up

procedures are still relatively empirical, solids-separation equipment must be

provided, and the catalyst must be attrition-resistant and not agglomerate.

The vapor-phase ammoxidation reaction takes place in a fluidized bed

reactor at approximately 200 kPa (2 atm) and 400-510C (750-950F) in the

presence of Catalyst 41. The conversion of propylene in the reactor is essentially

complete. The reactions involve in this reactor are also discussed in the literature

study of Sohio process.

The main reaction is highly exothermic with H = 760 kJ/mol, so an efficient

heat removal system is essential by using a set of immersed tubes with internal

boiler feed water circulation which is placed within the catalyst bed reactor. The

selectivity of the main reaction is roughly 86%, while the rest will be the selectivity of

all the side reaction, where propylene is the basis component for both reactions. The

conversion of propylene in both reactions is 98%.

As a result, the reactor effluent (Stream 6) consist of acrylonitrile, unreacted

compounds such as propylene and ammonia as well as other by products from

side reactions such as acetonitrile, hydrogen cyanide, water, carbon dioxide and

carbon monoxide. Before the reactor effluent stream is introduced into an absorber,

it is first cooled by a cooler (E - 7). The cooling process is beneficial in order to

prevent water from boiling and vaporizing. Water is used as a solvent in a counter -

17

current absorber for removal of inert gases and vents them to the incinerator prior to

release to the atmosphere.

The scrub bottom stream which contains acrylonitrile, unreacted propylene

and ammonia, acetonitrile, hydrogen cyanide, carbon dioxide, carbon monoxide,

and some water is then introduced to an in line acid base mixer (I - 5). Sulphuric

acid is also introduced into the in line mixer to permit neutralization of unreacted

ammonia to produce ammonium sulphate. This is due to the fact that ammonia is

hazardous, unstable, as well as gives toxic effects to the respiratory system, senses,

liver, kidneys and bladder observed in mammalian species from prolonged

inhalation exposures at above 100 ppm. Ammonium sulphate will be discharged

with wastewater rather than crystallizing and selling them for fertilizers industries.

This is because the equipment cost will be sufficiently increased by installing the

crystallizers unit. In addition, it is also consumed large amount of energy.

The neutralized crude (Stream 11) undergoes a series of separation to

obtain products and by product of the desired purity, as described below.

Separator 1 (E - 24) is used to separate the acrylonitrile crude from

acetonitrile and water where the crude is removed from the top of the separator

while the acetonitrile and water goes into the bottom recovery. The recovery bottom

(Stream 12) which comprises of acetonitrile and water are then entered into the

Distillation Column 1(E-17) for further purification process where the water is

removed from acetonitrile. The heavy bottom (Stream 13) from the Distillation

Column 1 is discharged to waste water treatment whereas the acetonitrile by-

product (Stream 14) will then pass to the incinerator. The acrylonitrile crude (Stream

15) exiting the first separator is allow to condensed by using a cooler (E-18) so that

it can be feed into distillation column 2 (E-19) as it is one of the requirement of

distillation column. The hydrogen cyanide and the light components are separated

from acrylonitrile at the top of the distillation column 2 based on the volatility

differences. For environmental purpose, stream 7, 16 and 14 are introduced into the

incinerator where the combustion process occurs.

The recovery of these by-products depends on several factors such as

market conditions, plant location and energy costs however we prefer to incinerate

by-product rather than purify or sell it off to the market as the hydrogen cyanide and

acetonitrile has low demand in the market. Besides that, it also can minimize the

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amount and duration of hydrogen cyanide (very hazardous compound) by

incineration.

In addition, the beauty side of the process is such that major of all those

compounds are highly combustible. The incinerator is equipped with the energy

recovery facilities as the exhausted flue gas from the combustion process can be

utilized as fuel boilers to produce high pressure steam. Then, the high pressure

steam can be used to drive the steam turbine and hence the electrical generator

which supplies onsite power particularly for mechanical devices such as pump and

compressor. If the power is surplus, then it can be sold off and thus boost our profit

as well. In addition, the low pressure steam from the turbine can be used for heating

process in the plant, condensed and recycled back to the boiler feed water.

The bottom product of Distillation Column 2 is introduced to the Distillation

Column 3 (E-20) whereby the heavy ends stream (stream 18) from the product

column contains essentially no acrylonitrile. The acrylonitrile product (stream 19)

obtained from this separation process has a purity of 99%. Besides that, stream 13

and 18 are mixed together and then goes to the deep well pond prior to treatment

process. The wastewater treatment has it benefit as the treated water from the

treatment facilities can be recycled back to the plant and used as solvent for

absorption process.

19

E-4

E-5

P-3

I-4

P-8

E-7

P-9

P-10

P-11

P-13

P-15

I-5

P-18

E-17

P-19

E-18

P-20

E-19

P-21

P-23

P-24

E-20

P-25

Propylene

Ammonia

Catalysed Fluidized

Bed Reactor

Absorber

Sulphuric Acid

Separator

In-line

Acid Base Mixer

Mixer

Heater

Heater

Cooler

Water

DC 1

Cooler

DC 2

Incinerator

DC 3

Waste water

treatment

Acrylonitrile

Acetonitrile

Hydrogen

Cyanide (HCN)

Vent Gases

E-24

E-25

P-29

P-31

Compressor

6

7

8

10

15

12

14

16

17

19

P-22

P-32

P-22

18

13

E-26

Cooler

Heater

P-38

Oxygen

P-16

E-27

9

11

1

2

P-49

E-31

E-35

3P-3

E-36

4

5

E-37

Figure 1.5: Process Flow Diagram of Acrylonitrile Production.

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Table 1.9: Estimated Composition Stream Table.

Stream 1 Stream 2 Stream 3 Stream 4 Stream 5 Stream 6 Stream 7 Stream 8 Stream 9 Stream 10

Component Propylene feed

Ammonia feed

O2 feed Reactor effluent

Vent gases

Scrub water

Scrub bottom

Sulfuric acid

Neutralized crude

Acrylonitrile crude

C3H6 (propylene)

NH3 (ammonia)

O2 (oxygen)

C3H3N (acrylonitrile)

HCN (hydrogen cyanide)

C2H3N (acetonitrile)

H2O (water)

CO (carbon monoxide)

CO2 (carbon dioxide)

H2SO4 (sulphuric acid)

(NH4)2SO4 (ammonium sulphate)

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Stream 11 Stream 12 Stream 13 Stream 14 Stream 15 Stream 16 Stream 17

Component Recovery bottoms

Crude acetonitrile

Aqueous

residues

HCN byproduct

Interim acrylonitrile

Acrylonitrile product

Heavy impurities

C3H6 (propylene)

NH3 (ammonia)

O2 (oxygen)

C3H3N (acrylonitrile)

HCN (hydrogen cyanide)

C2H3N (acetonitrile)

H2O (water)

CO (carbon monoxide)

CO2 (carbon dioxide)

H2SO4 (sulphuric acid)

(NH4)2SO4 (ammonium sulphate)

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