ENGINEERING ASPECTS OF BIODIESEL PRODUCTION PROCESSfapc.biz/files/biodiesel/biodiesellecture.pdf · ENGINEERING ASPECTS OF BIODIESEL PRODUCTION PROCESS Nurhan Turgut Dunford Oklahoma

ENGINEERING ASPECTS OF

BIODIESEL PRODUCTION PROCESS

Nurhan Turgut Dunford

Oklahoma State University

Department of Biosystems and Agricultural Engineering

Outline Introduction Transesterification Esterification Homogeneous catalysis Heterogeneous catalysis Enzymatic conversion Conversion without a catalyst Lipid hydrotreating Planning for production Site selection

Petroleum

A naturally occurring oil that contains mainlyhydrocarbons with some other elements such assulphur, oxygen and nitrogen

Gasoline: A mixture of hydrocarbons containing 5-8carbon atoms, boiling point 40-180oC

Kerosine (paraffin oil): A mixture of hydrocarbonscontaining 11-12 carbon atoms, boiling point 160-250oC

Diesel oil: A mixture of hydrocarbons containing 13-25 carbon atoms, boiling point 220-350oC

Petroleum Diesel

A fuel derived from the distillation of crude oilIt is heavier than gasoline but lighter than engine oil

and heavy oils.Diesel fuel is generally separated into two fuels: diesel

number 1 and diesel number 2. Diesel number 1 issimilar to kerosene and is lighter than diesel number2. While diesel number 2 is sold most of the time,diesel number 1 is sold during winter in very coldclimates because it doesn’t cloud or gel as easily asdiesel number 2.

Diesel fuel is ignited in an internal combustion enginecylinder by the heat of air under high compression incontrast to motor gasoline, which is ignited byelectrical spark.

Definition of Biodiesel

“A fuel comprised of mono-alkyl-ester of longchain fatty acids derived from vegetable oils oranimal fat designated B100”

Biodiesel safety:http://www.biodieselcommunity.org/safety/http://www.biodiesel.org/pdf_files/fuelfactsheets/M

SDS.pdf

Why Biodiesel?

Can be used in existing diesel engines without modification. Can be blended in at any ratio with petroleum diesel. Similar Btu/gal as petroleum diesel. Also eliminates the huge cost of revamping the nationwide

fuel distribution infrastructure. Reduces CO2 emission.

Average Density and Heating Value of Biodiesel and Diesel Fuel

Fuel Density, g/cm3 Net Heating Value Avg., Btu/gal. % Difference vs.No. 2 Diesel Avg.

No. 2 Diesel 0.850 129,500 Biodiesel (B100) 0.880 118,296 8.65 % B20 Blend (B20) 0.856* 127,259* 1.73 %* B2 Blend (B2) 0.851* 129,276* 0.17 %*

* Calculated Values from those of No. 2 Diesel and Biodiesel (B100)

Triacylglyceride

C

C

C

H

H

H

H

H

H

H

H

OH

OH

OH

+

HOOCR

HOOCR’

HOOCR”

+ 3H2O

GLYCEROL FATTY ACIDS TRIGLYCERIDES WATER

Fatty Acid Molecular Structure

Saturated Fatty Acids

Monounsaturated Fatty Acids

Polyunsaturated Fatty Acids

R - COOH + R1- OH R – COO - R1 + H2O

Fatty Acid Alcohol Catalyst Ester/biodiesel Water

Esterification

Methanol safety:http://www.biodiesel.org/resources/reportsdatabase/reports/gen/20060401_GEN-370.pdf

Transesterification

R1, R2, R3 are hydrocarbon chains on fatty acids and

R’ is the alkyl group on an alcohol molecule

Triacylglyceride Alcohol Esters/Biodiesel Glycerine

Homogeneous CatalysisAcid or Base Catalysis

Alcohol/catalyst

Oil/fat

Reactor Separator

Alcohol Recovery

Glycerine + Water+Alcohol

Alcohol

Biodiesel

Water

BiodieselDryer

Wash Column

Glycerine

Glycerine Recovery

Glycerine + Water

Glycerine + Alcohol

Homogeneous Catalyst Options

Base Catalysts: NaOH, KOH, Na/K-Methoxide

Acid Catalysts: H2SO4, H3PO4, CaCO3

Lipase Enzymes

Base Catalyzed Conversions

Base catalyzed processes dominate currentcommercial production

Sensitive to water and free fatty acids

Typical alcohol to oil ratio varies between 6:1 and10:1 (mole ratio)

Typical catalyst concentrations (w/w, %)

NaOH/KOH 0.3-1.4%

Na-Methoxide 0.5% or less

Acid Catalyzed Conversions

Direct esterification, oils with high free fatty acidcontent or for making esters from soap stock

Requires water removal Requires high alcohol:free fatty acid ratio, i.e.

40:1 Requires large amount of catalyst (5-25%)

Homogeneous CatalysisTwo-Step Process

Alcohol/Acid catalyst

Oil/fat

Acid Reactor Separator

Alcohol Recovery

Glycerine + Alcohol + Water

Alcohol

Biodiesel

Water

BiodieselDryer

Wash Column

Glycerine

Glycerine Recovery

BaseReactor

Glycerine + Water

Alcohol + Base Catalyst

Glycerine + Alcohol

Alcohol + Catalyst

Heterogeneous Catalysis

Oil/fat

Alcohol

Glycerine

Glycerine

Glycerine

Biodiesel

Alcohol

Heteregeneous Catalysts

Sulfated zirconia and tungstated zirconia are typicalexamples of superacids

Sulfonic resins such as Nafion® NR50, sulphated zirconia(SZ), and tungstated zirconia (WZ), have sufficient acid sitestrength to catalyze biodiesel-forming transesterificationreactions as efficiently as sulfuric acid.

Many types of heterogeneous catalysts, such as alkalineearth metal oxides, various alkaline metal compoundssupported on alumina or zeolite can catalyzetransesterification reactions. The order of activity amongalkaline earth oxide catalysts is BaO > SrO > CaO > MgO

Heterogeneous Esterfip-HProcess Highlights

http://www.Axens.net Continuous technology based on solid catalyst High glycerol purity >98% Very high ester yield: close to 100% No waste production of low-value fatty acids No waste saline streams that require disposal Much lower catalyst requirements (per ton of FAME)

compared with other processes

Enzymatic Conversion

Lipases are used as catalyst Immobilized or free enzymes

Oil + Alcohol

Enzyme

Reactor

Separator

Biodiesel

Glycerine

Comparison of Enzymeand Base Catalysis

Catalyst Base Enzyme

Reaction temperature 60-70°C 30-4OoC

Free fatty acids Saponified products Methyl estersin raw materials (soap formation)

Water in raw materials Interference with No influencethe reaction

Yield of methyl esters Normal Higher

Recovery of glycerol Difficult Easy

Purification of methyl esters Repeated washing None

Catalyst cost Cheap Relativelyexpensive

Batch vs Continuous System

Batch process is better suited to smaller plants (<1million gallons/year)

Batch process provides operation flexibility Continuous process allows use of high volume

separation systems hence increases throughput

Transesterification Time

At ambient temperature (70F and 21oC) reaction takes4-8 h to reach completion

Higher temperature will decrease reaction times butthis requires pressure vessel because boiling point ofmethanol is 148F (65oC)

High shear mixing and co-solvent use acceleratesreaction rates

Supercritical fluidsCo-solvent systems

Non-Catalytic Conversions

Non-Catalytic ConversionSupercritical Methanol

Oil/fat

Biodiesel

High pressure & temperature reactor

Alcohol

Glycerine

AlcoholSeparator

Separator

350-400oC, 85-100 atm (1200-1500 psi), alcohol:oil 42:1 3-5 min reaction time

Non-Catalytic ConversionCo-Solvent Process

Biox ProcessUses an inert co-solvents (tetrahydrofuran,

MTBE-methyl tert-butyl ether, ) that generatean oil-rich one-phase system.

This reaction is 95% complete in ten minutesat ambient temperatures.

No catalyst is required.Alcohol

Oil

Phase Separation

Required density difference for phase separation 0.1

Specific GravityMethanol 0.79Biodiesel 0.88Soybean oil 0.92Catalyst 0.97Glycerine 1.28

“Good reaction” as much methanol as possible“Good phase separation” min. methanol

SuperCetane Several reactions occur in the process, including: hydrocracking

(breaking apart of large triglyceride molecules), hydrotreating(removal of oxygen), and hydrogenation (saturation of doublebonds). A conventional commercial refinery hydrotreating catalystis used in the process and hydrogen is the only other input.

Feedstocks: canola oil, soya oil, yellow grease, animal tallow andtall oil (a by-product of the kraft pulping process).

Cetane number (a measure of ignition quality) of around 100 –which is comparable to commercial cetane additives. The specificgravity of SuperCetane is similar to regular diesel while itsviscosity is similar to biodiesel. It is 97% biodegradable ascompared to 45% for regular diesel.

http://www.nrcan.gc.ca/es/etb/cetc/cetc01/htmldocs/pdfs/supercetane_e.pdf

AVRO Diesel TM Process

(http://www.nrcan.gc.ca/es/etb/cetc/cetc01/htmldocs/pdfs/avro_diesel_e.pdf) combines mild thermal crackingwith esterification. This process is being patented by the

CANMET Energy Technology Centre – Ottawa.Feedstock: waste animal fats, cooking greases, and trapgrease that are 'too contaminated' for a conventionaltrans-esterification process, and produces clean diesel fuel.The process yields 65 to 75 wt%hydrocarbons/methyl-esters mixturessuitable for diesel fuel blending.

ConocoPhillips/TysonRenewable Diesel

The production technology for renewable diesel uses athermal depolymerization process to co-process animalfat with hydrocarbon feedstock.

The fuel is chemically equivalent to the diesel producedfrom hydrocarbon feedstocks and can be transporteddirectly through existing pipelines to distributionterminals.

Biodiesel DryWashTM

Adsorbent purification Magnesium Silicate (Magnesol D-Sol) Removes both particles and soluble impurities Excess methanol flash evaporated

http://www.dallasgrp.com/biodiesel.pdf

Ion Exchange Dry Wash

Ion exchange resin is used for biodiesel cleaning. Greenline & Rohm-Haas Corporation collaboration: Ion-

exchange resin known as Amberlite. Amberlite looks very much like coffee grounds and

functions much like coffee grounds in a percolator. Thebiodiesel fuel enters the top of the percolator andtrickles down through the cylinder of Amberlite.

The final product is pure and dry. The resin needs replacing at the rate of about 1 metric

ton for every 250,000 gallons of biodiesel processed.

http://www.greenlineindustries.com/ProcessDesc_1.htm

Technology Providers

Desmet Ballestra North America Westfalia Separator, Inc. Crown Irons Works Lurgi PSI

Reading Material

http://www.southeastdiesel.org/Photos/Library/Ag/Eng_AspectsCh1.pdf

http://www.fapc.okstate.edu/factsheets/fapc149.pdfhttp://www.fapc.okstate.edu/factsheets/fapc150.pdfhttp://www.uidaho.edu/bioenergy/biodieselED/publicati

on/01.pdf

University of Idaho-Questionshttp://www.uidaho.edu/bioenergy/top10q_s.htm

Questions

Define biodiesel What are the three components that are required for

making biodiesel? What are the advantages and disadvantages of using

ethanol instead of methanol for biodiesel production? What are the most common catalysts (acid and base)

used for biodiesel production? Name two reactions that are used for biodiesel

production and highlight differences Compare energy contents of biodisel and petroleum

diesel Name two biodiesel production techniques which do not

require a catalyst

Biodiesel ProductionFacilities in the US

Smallest capacity: 50,000 gallons/year, recycled cooking oilLargest capacity: 37.5 Million gallons/year, soybeanEarth Biofuels Inc, Durant, OK, 10 Million gallons/year, multifeed stockGreen Country Biodiesel Inc., Chelsea, OK, 2.5 Million gallons/year, soybean

Biodiesel Industry Expansion

Largest Capacity:100 Million gallons/yearSmallest Capacity: 250,000 gallons/yearADM, 85 Million gallons/year, canola oilBest Energy Solutions LLC, Tulsa, OK, 1 Million gallons/year

Planning*

Location

Biodiesel Marketing

Feedstock Sourcing

Glycerine Outlet

Process Plant Size

* Chris Mitchell – Biodiesel Product Manager DesmetBallestra North America

Location*

Minimizing the freight cost for feedstockand biodiesel will be critical to survive.

How much biodiesel can be sold in a 200mile radius?

How much competition or potentialcompetition exists in a 200 mile radius?


Feedstock Sourcing*

Do you have control of your own feedstock supply (as anoilseed crusher or animal fats renderer)?

If you are dependent on an external supply, how manypotential suppliers are within a 200 mile radius?

Can you sign a long-term contract with one of thesesuppliers to insure adequate feedstock?

Will the feedstock suppliers in the area deliver by truck orrail, and at what frequency?


Glycerin Outlet*

Where are the closest potential buyers of glycerin?

What quality of crude glycerin (H2O, MeOH, soap, FFA, saltetc) will they purchase, and at what price relative to USPgrade refined glycerin?

Will the glycerin refiners in the area want delivery by truckor rail, and at what frequency?

Do you need to install your own glycerin refinery?

* Chris Mitchell – Biodiesel Product Manager Desmet BallestraNorth America

Process Plant Size*

What plant size will meet the short and long termneeds of the local biodiesel market?

How does local feedstock availability limit plantsize?

What minimum plant size is required to provide acompetitive conversion cost in the long-term?

How much equity and debt financing is available tobuild the plant, and how much capacity can that buy?


Plant Site Selection*

Transportation Proximity

Utility Connections

Specific Parcel of Land

Shared Infrastructure


Transportation Proximity*

Is the site adjacent to an active freight rail system?

Does the site, or can the site, have a rail siding installedwith sufficient length of track?

At what frequency are rail switches possible, and howwill the rail cars be moved for loading/unloading?

Is the site in close proximity to a highway?


Utility Connections*

Does the site have sufficient power supply available?

Does the site have sufficient water supply available (tomeet fire protection demand)?

Does the site have a sewer connection that can takethe plant waste water?

Does the plant have natural gas supply available?


Land*

Does the site have sufficient space for the processplant (with surrounding safe area), tank farm, utilitybuilding, office building, rail siding and truck route?

Does the site have sufficient extra space for a futurebiodiesel plant expansion or glycerine refinery?

Is the site long enough for the rail siding to hold asufficient number of cars?

Any environmental & construction permitting issues?


Infrastructure*

Does the site already have a process plant staff(management, marketing, purchasing, maintenance andquality control) that can be shared to offset conversioncosts?

Does the site already feedstock tanks to reducefeedstock (freight) costs?

Does the site already have utilities that can be shared?


Critical Parameters*

Safety

Quality

Downtime/Uptime

Operating Costs

Capital Costs


Safety*

Biodiesel plants use a considerable quantity of highlyflammable liquid (methanol) & corrosive material (sodiummethoxide).

The process plant must be designed as a hazardous areaenvironment with the hazardous areas within and adjacentto the process building defined by NFPA-497 (NFPA-National Fire Protection Association).

The methanol and sodium methoxide storage tanks mustbe designed in accordance with NFPA 30.

* Chris Mitchell – Biodiesel Product Manager, Desmet BallestraNorth America

Safety*

Special Class 1, Division 1, Group D and Class1, Division 2, Group D explosion proof electricaldesign is required as per NFPA-70 to minimize asource of ignition.


Quality*

All biodiesel leaving the facility must meet ASTM (AmericanSociety of Testing and Materials) specs at a minimum.

Biodiesel leaving the facility should meet specs as agreedto with the buyer.

Biodiesel should also be transported in clean vessels.


Quality*

Biodiesel should be analyzed before being sent tostorage.

A biodiesel plant should have a fully equipped lab with aqualified chemist that understands the chemistry and unitprocesses in the plant well enough to trouble-shootfeedstock & process issues and give the operations stafffeedback.


Downtime*

Plants are often stopped for lack of feedstock, biodieseland crude glycerine sales, sufficient storage or loading &unloading logistics.

Plants also suffer from quality problems which requiresignificant rework, and resultant loss of production time.


Uptime*

A biodiesel plant should operate a minimum of 8,000hours per year at its design rate (>90% uptime).

The fixed costs of capital and semi-fixed costs ofmanpower need to be spread out upon a full productionschedule to minimize conversion costs.


Total Operating Costs

11%

1%

1%

0%

0%

2%

85%

CHEMICALS

MANPOWER

UTILITIES

MAINTENANCE

TAXES & INSURANCE

DEPRECIATION

FEEDSTOCK

Operating Costs*

Approximately 85% of operating cost of a biodiesel plant isfor feedstock.

Producing your own feedstock to insure supply at a fairprice, and minimizing the freight to deliver the feedstock tothe biodiesel plant, are both critical factors in controllingprofitability.

An alternative to controlling supply is to have a flexibleprocess to handle multiple feedstock sources (such assoybean oil, poultry fat or yellow grease).


Conversion Costs (approximately $0.33/gallon)

$0.221

$0.030

$0.029

$0.010

$0.010

$0.031

CHEMICALS

MANPOWER

UTILITIES

MAINTENANCE

TAXES & INSURANCE

DEPRECIATION

Operating Costs*

Total conversion costs range from $0.30 to $0.50 per gallondepending on technology and plant size.

Chemical consumptions, utility consumptions andmaintenance costs (50-75% of the conversion cost) are morea function of the technology than plant size.

Selecting automated, continuous or semi-continuousprocess technology is a critical factor in controlling plantprofitability.


Operating Costs*

Total conversion costs range from $0.30 to $0.50 per gallondepending on technology and plant size.

Manpower, taxes, insurance and depreciation (25-50% ofconversion cost) are more a function of plant size thantechnology.

Selecting a plant large enough to take advantage ofeconomy of scale (capital & manpower) is a critical factor incontrolling plant profitability.


Capital Cost -- Process Building

3%10%

38%

3% 20%

12%

8%

6%

grading/concrete

structural/building

process equipment

equipment setting

piping

electrical

automation

insulation

Capital Costs*

Process equipment only accounts for 25-35% of totalcapital cost in a typical biodiesel plant.


Capital Cost -- Complete facility

10%

65%

4%

3%

18%

SITE WORK

PROCESS BUILDING

UTILITY BUILDING

OFFICE BUILDING

TANK FARM

Capital Costs*

Total capital costs for 1-5 mgy biodiesel plants** aretypically in the range of $1.75-$1.25 / annual gallon.Total capital costs for 10-15 mgy biodiesel plants** aretypically in the range of $1.00-$0.75 / annual gallon.Total capital costs for 30-90 mgy biodiesel plants** aretypically in the range of $0.75-$0.50 / annual gallon.

** Tank farm included / pretreatment not included.


Biodiesel Fuel SpecificationASTM D 6751-06

Report–ASTM D 2500Cloud point, ºC ASTM—

–47ASTM D 613Cetane numberNo. 3–ASTM D 130Copper strip corrosion

MaxMinMethodProperty

––

1.9–

130.0

0.0015 (S15)0.05 (S500)

ASTM D 5453Sulfur, %mass0.020ASTM D 874Sulfated ash, %mass

6.0ASTM D 445Kin. Viscosity (40ºC),mm²/s

0.050ASTM D 2709Water & sediment, %vol–ASTM D 93Flash point, ºC

ASTM: American Society of Testing and Materials.

Biodiesel Fuel SpecificationASTM D 6751-06

5–UOP 391Sodium & potassium,combined, ppm

360–ASTM D 1160Distillation temp., ºCAtm. equiv. temp., 90%recovered

0.001–ASTM D 4951Phosphorus, %mass

MaxMinMethodProperty

–

–

–

–

0.240ASTM D 6584Total glycerin, %mass

0.020ASTM D 6584Free glycerin, %mass

0.50ASTM D 664Acid no., mg KOH/g

0.050ASTM D 4530Carbon residue, %mass

Biodiesel Quality Assurance

Testing in accordance with fuelspecifications is time consuming andexpensive

In North America, the “BQ-9000”program helps assure quality inbiodiesel fuel

Biodiesel Quality AssuranceBQ-9000 Program

National Biodiesel Accreditation ProgramEndorsed by NBB & Canadian Renewable Fuels AssociationCooperative & voluntary program for accreditation ofbiodiesel producers & marketersOpen to manufacturers, marketers & distributors ofbiodiesel & blends in the U.S. & CanadaCombines ASTM D 6751 standard with quality systemsprogram including practices for storage, sampling, testing,blending, shipping, distribution & fuel management


National Biodiesel Accreditation Committee

(NABC) is a fully autonomous committee of NBBDesigned & implemented BQ-9000 programResponsible for developing improvements

Program objectives:Promote commercial success & acceptance of biodieselHelp assure biodiesel is produced to & maintained at industry

standard, ASTM D 6751Avoid redundant testing during production & distributionProvide mechanism to track biodiesel in distribution chainReduce probability of “out of spec” fuel reaching the market


Program AccreditationOpen to companies actively or planning to produce,

distribute or market biodiesel in “neat” or blendedformulations

Requires formal review & audit of capacity of applicantto produce or market biodiesel that meets ASTM D 6751standards

Once it is awarded, it is held for two yearsFollowing two-year period, company undergoes

recertification audit to extend accreditation


Accredited ProducerEntity engaged in production and/or

distribution & sale of biodiesel and/orbiodiesel blends of B2 or greater

Successfully met accreditationrequirements

Accredited Producers: AGP, Cargill, Eastman Chemical (AR Ops),Griffin Industries, Huish Detergents, Imperial Western Products,Johann Haltermann, Organic Fuels, Peter Cremer NA, SoyMorBiodiesel, West Central, World Energy Alternatives


Certified MarketerEntity undertaking to sell or

resell biodiesel or biodieselblends

Successfully met accreditationrequirements

Certified Marketers: Peter Cremer NA, SpragueEnergy

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ENGINEERING ASPECTS OF BIODIESEL PRODUCTION PROCESSfapc.biz/files/biodiesel/biodiesellecture.pdf · ENGINEERING ASPECTS OF BIODIESEL PRODUCTION PROCESS Nurhan Turgut Dunford Oklahoma