biodiesel lecture

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 mainly hydrocarbons with some other elements such as sulphur, oxygen and nitrogen

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

Kerosine (paraffin oil): A mixture of hydrocarbons containing 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 oil It 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 is similar to kerosene and is lighter than diesel number 2. While diesel number 2 is sold most of the time, diesel number 1 is sold during winter in very cold climates because it doesn’t cloud or gel as easily as diesel number 2.

Diesel fuel is ignited in an internal combustion engine cylinder by the heat of air under high compression in contrast to motor gasoline, which is ignited by electrical spark.

Definition of Biodiesel

“A fuel comprised of mono-alkyl-ester of long chain fatty acids derived from vegetable oils or animal fat designated B100”

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

fuelfactsheets/MSDS.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 current commercial production

Sensitive to water and free fatty acids

Typical alcohol to oil ratio varies between 6:1 and 10:1 (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 acid content 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

Base Reactor

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 typical examples of superacids

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

Many types of heterogeneous catalysts, such as alkaline earth metal oxides, various alkaline metal compounds supported on alumina or zeolite can catalyze transesterification reactions. The order of activity among alkaline earth oxide catalysts is BaO > SrO > CaO > MgO

Heterogeneous Esterfip-H Process 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 Enzyme and Base Catalysis

Catalyst BaseEnzyme

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 (<1 million 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 takes 4-8 h to reach completion

Higher temperature will decrease reaction times but this requires pressure vessel because boiling point of methanol is 148F (65oC)

High shear mixing and co-solvent use accelerates reaction rates

Supercritical fluidsCo-solvent systems

Non-Catalytic Conversions

Non-Catalytic ConversionSupercritical Methanol

Oil/fat

Biodiesel

High pressure & temperature reactor

Alcohol

Glycerine

Alcohol

Separator

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 generate an oil-rich one-phase system.

This reaction is 95% complete in ten minutes at 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 double bonds). A conventional commercial refinery hydrotreating catalyst is used in the process and hydrogen is the only other input.

Feedstocks: canola oil, soya oil, yellow grease, animal tallow and tall 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 specific gravity of SuperCetane is similar to regular diesel while its viscosity is similar to biodiesel. It is 97% biodegradable as compared 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 cracking with esterification. This process is being patented by the

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

ConocoPhillips/Tyson Renewable Diesel

The production technology for renewable diesel uses a thermal depolymerization process to co-process animal fat with hydrocarbon feedstock.

The fuel is chemically equivalent to the diesel produced from hydrocarbon feedstocks and can be transported directly through existing pipelines to distribution terminals.

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. The biodiesel fuel enters the top of the percolator and trickles 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.pdfhttp://www.fapc.okstate.edu/factsheets/fapc149.pdfhttp://www.fapc.okstate.edu/factsheets/fapc150.pdfhttp://www.uidaho.edu/bioenergy/biodieselED/

publication/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 Production Facilities 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 Desmet Ballestra North America

Location*

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

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

How much competition or potential competition exists in a 200 mile radius?* Chris Mitchell – Biodiesel Product Manager

Desmet Ballestra North America

Feedstock Sourcing*

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

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

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

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


Glycerin Outlet*

Where are the closest potential buyers of glycerin?

What quality of crude glycerin (H2O, MeOH, soap, FFA, salt etc) will they purchase, and at what price relative to USP grade refined glycerin?

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

Do you need to install your own glycerin refinery?


Process Plant Size*

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

How does local feedstock availability limit plant size?

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

How much equity and debt financing is available to build the plant, and how much capacity can that buy?* Chris Mitchell – Biodiesel Product Manager Desmet

Ballestra North America

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 installed with sufficient length of track?

At what frequency are rail switches possible, and how will 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 (to meet fire protection demand)?

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

Does the plant have natural gas supply available?


Land*

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

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

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

Any environmental & construction permitting issues? * Chris Mitchell – Biodiesel Product Manager Desmet


Infrastructure*

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

Does the site already feedstock tanks to reduce feedstock (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 highly flammable liquid (methanol) & corrosive material (sodium methoxide).

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

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

* Chris Mitchell – Biodiesel Product Manager, Desmet Ballestra North America

Safety*

Special Class 1, Division 1, Group D and Class 1, Division 2, Group D explosion proof electrical design is required as per NFPA-70 to minimize a source of ignition.


Quality*

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

Biodiesel leaving the facility should meet specs as agreed to with the buyer.

Biodiesel should also be transported in clean vessels.


Quality*

Biodiesel should be analyzed before being sent to storage.

A biodiesel plant should have a fully equipped lab with a qualified chemist that understands the chemistry and unit processes in the plant well enough to trouble-shoot feedstock & process issues and give the operations staff feedback.


Downtime*

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

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


Uptime*

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

The fixed costs of capital and semi-fixed costs of manpower need to be spread out upon a full production schedule 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 is for feedstock.

Producing your own feedstock to insure supply at a fair price, and minimizing the freight to deliver the feedstock to the biodiesel plant, are both critical factors in controlling profitability.

An alternative to controlling supply is to have a flexible process to handle multiple feedstock sources (such as soybean 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 gallon depending on technology and plant size.

Chemical consumptions, utility consumptions and maintenance costs (50-75% of the conversion cost) are more a function of the technology than plant size.

Selecting automated, continuous or semi-continuous process technology is a critical factor in controlling plant profitability.


Operating Costs*

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

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

Selecting a plant large enough to take advantage of economy of scale (capital & manpower) is a critical factor in controlling 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 total capital 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** are typically in the range of $1.75-$1.25 / annual gallon.Total capital costs for 10-15 mgy biodiesel plants** are typically in the range of $1.00-$0.75 / annual gallon.Total capital costs for 30-90 mgy biodiesel plants** are typically in the range of $0.75-$0.50 / annual gallon.

** Tank farm included / pretreatment not included.* Chris Mitchell – Biodiesel Product Manager, Desmet


Biodiesel Fuel SpecificationASTM D 6751-06

Property Method Min MaxFlash point, ºC ASTM D 93 130.0 –

Water & sediment, %vol ASTM D 2709 – 0.050

Kin. Viscosity (40ºC), mm²/s

ASTM D 445 1.9 6.0

Sulfated ash, %mass ASTM D 874 – 0.020

Sulfur, %mass ASTM D 5453 – 0.0015 (S15)

0.05 (S500)

Copper strip corrosion ASTM D 130 – No. 3

Cetane number ASTM D 613 47 –

Cloud point, ºC ASTM— ASTM D 2500 – Report

ASTM: American Society of Testing and Materials.

Biodiesel Fuel SpecificationASTM D 6751-06

Property Method Min MaxCarbon residue, %mass

ASTM D 4530

– 0.050

Acid no., mg KOH/g ASTM D 664 – 0.50

Free glycerin, %mass ASTM D 6584

– 0.020

Total glycerin, %mass ASTM D 6584

– 0.240

Phosphorus, %mass ASTM D 4951

– 0.001

Distillation temp., ºCAtm. equiv. temp., 90% recovered

ASTM D 1160

– 360

Sodium & potassium, combined, ppm

UOP 391 – 5

Biodiesel Quality Assurance

Testing in accordance with fuel specifications is time consuming and expensive

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

Biodiesel Quality AssuranceBQ-9000 Program

National Biodiesel Accreditation ProgramEndorsed by NBB & Canadian Renewable Fuels AssociationCooperative & voluntary program for accreditation of biodiesel producers & marketers Open to manufacturers, marketers & distributors of biodiesel & blends in the U.S. & CanadaCombines ASTM D 6751 standard with quality systems program 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 blended formulations

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

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/or biodiesel blends of B2 or greater

Successfully met accreditation requirements

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


Certified MarketerEntity undertaking to sell or

resell biodiesel or biodiesel blends

Successfully met accreditation requirements

Certified Marketers: Peter Cremer NA, Sprague Energy

biodiesel lecture

Documents

desmet ballestranorth

peter cremer

total capital

biodiesel

controlling

fatty acids

fixed costs

capital cost