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?
* Chris Mitchell – Biodiesel Product Manager DesmetBallestra North America
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?
* Chris Mitchell – Biodiesel Product Manager DesmetBallestra North America
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?
* Chris Mitchell – Biodiesel Product Manager Desmet BallestraNorth America
Plant Site Selection*
Transportation Proximity
Utility Connections
Specific Parcel of Land
Shared Infrastructure
* Chris Mitchell – Biodiesel Product Manager Desmet BallestraNorth America
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?
* Chris Mitchell – Biodiesel Product Manager Desmet BallestraNorth America
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?
* Chris Mitchell – Biodiesel Product Manager Desmet BallestraNorth America
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?
* Chris Mitchell – Biodiesel Product Manager Desmet BallestraNorth America
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?
* Chris Mitchell – Biodiesel Product Manager Desmet BallestraNorth America
Critical Parameters*
Safety
Quality
Downtime/Uptime
Operating Costs
Capital Costs
* Chris Mitchell – Biodiesel Product Manager Desmet BallestraNorth America
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.
* Chris Mitchell – Biodiesel Product Manager, Desmet BallestraNorth America
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.
* Chris Mitchell – Biodiesel Product Manager, Desmet BallestraNorth America
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.
* Chris Mitchell – Biodiesel Product Manager, Desmet BallestraNorth America
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.
* Chris Mitchell – Biodiesel Product Manager, Desmet BallestraNorth America
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.
* Chris Mitchell – Biodiesel Product Manager, Desmet BallestraNorth America
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).
* Chris Mitchell – Biodiesel Product Manager, Desmet BallestraNorth America
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.
* Chris Mitchell – Biodiesel Product Manager, Desmet BallestraNorth America
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.
* Chris Mitchell – Biodiesel Product Manager, Desmet BallestraNorth America
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.
* Chris Mitchell – Biodiesel Product Manager, Desmet BallestraNorth America
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.
* Chris Mitchell – Biodiesel Product Manager, Desmet BallestraNorth America
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
Biodiesel Quality AssuranceBQ-9000 Program
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
Biodiesel Quality AssuranceBQ-9000 Program
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
Biodiesel Quality AssuranceBQ-9000 Program
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
Biodiesel Quality AssuranceBQ-9000 Program
Certified MarketerEntity undertaking to sell or
resell biodiesel or biodieselblends
Successfully met accreditationrequirements
Certified Marketers: Peter Cremer NA, SpragueEnergy