Biodiesel Production Manual

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Text of Biodiesel Production Manual

July 2004

NREL/SR-510-36244

Biodiesel Production TechnologyAugust 2002January 2004

J. Van Gerpen, B. Shanks, and R. PruszkoIowa State University

D. ClementsRenewable Products Development Laboratory

G. KnotheUSDA/NCAUR

National Renewable Energy Laboratory1617 Cole Boulevard, Golden, Colorado 80401-3393 303-275-3000 www.nrel.gov Operated for the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy by Midwest Research Institute Battelle Contract No. DE-AC36-99-GO10337

July 2004

NREL/SR-510-36244

Biodiesel Production TechnologyAugust 2002January 2004

J. Van Gerpen, B.Shanks, and R. PruszkoIowa State University

D. ClementsRenewable Products Development Laboratory

G. KnotheUSDA/NCAUR

NREL Technical Monitor: K. Shaine TysonPrepared under Subcontract No. ACO-2-35016-01

National Renewable Energy Laboratory1617 Cole Boulevard, Golden, Colorado 80401-3393 303-275-3000 www.nrel.gov Operated for the U.S. Department of Energy Office of Energy Efficiency and Renewable Energy by Midwest Research Institute Battelle Contract No. DE-AC36-99-GO10337

NOTICE This report was prepared as an account of work sponsored by an agency of the United States government. Neither the United States government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States government or any agency thereof. Available electronically at http://www.osti.gov/bridge Available for a processing fee to U.S. Department of Energy and its contractors, in paper, from: U.S. Department of Energy Office of Scientific and Technical Information P.O. Box 62 Oak Ridge, TN 37831-0062 phone: 865.576.8401 fax: 865.576.5728 email: mailto:reports@adonis.osti.gov Available for sale to the public, in paper, from: U.S. Department of Commerce National Technical Information Service 5285 Port Royal Road Springfield, VA 22161 phone: 800.553.6847 fax: 703.605.6900 email: orders@ntis.fedworld.gov online ordering: http://www.ntis.gov/ordering.htm This publication received minimal editorial review at NREL

Printed on paper containing at least 50% wastepaper, including 20% postconsumer waste

Biodiesel Production TechnologyBackground1. Basics of Biodiesel Production ................................................................................................................. 1 2. Basic Organic Chemistry .......................................................................................................................... 7 3. Biodiesel Specifications and Properties .................................................................................................. 22

Biodiesel Production Processes4. Types of Biodiesel Production Processes ............................................................................................... 30 Laboratory - Exercise 1.................................................................................................................. 41 5. Basic Plant Equipment and Operation ................................................................................................... 43 6. Chemical Plant Controls ......................................................................................................................... 48 7. Pretreatment of High Free Fatty Acid Feedstocks .................................................................................. 52 8. Patent Discussion .................................................................................................................................... 56 9. Patent List for Biodiesel.......................................................................................................................... 62 10. Post Reaction Processing ...................................................................................................................... 66 11. Treatment and Recovery of Side Streams............................................................................................. 75 Laboratory Exercise 2 ................................................................................................................. 78

Biodiesel Plant Logistics12. Feedstock Preparation ........................................................................................................................... 79 13. Feedstock Quality Issues....................................................................................................................... 90 14. Plant Safety ........................................................................................................................................... 92 15. Biodiesel Transportation and Storage ................................................................................................... 98 16. Product Quality ................................................................................................................................... 101 Laboratory Exercise 3 ............................................................................................................... 105

1. Basics of Biodiesel ProductionBiodiesel is an alternative fuel for diesel engines that is gaining attention in the United States after reaching a considerable level of success in Europe. Its primary advantages are that it is one of the most renewable fuels currently available and it is also non-toxic and biodegradable. It can also be used directly in most diesel engines without requiring extensive engine modifications. The purpose of this book is to describe and explain the processes and issues involved in producing this new fuel. The most cursory look at the literature relating to biodiesel will soon reveal the following relationship for prediction of biodiesel from fats and oils. 100 lbs of oil + 10 lbs of methanol 100 lbs of biodiesel + 10 lbs of glycerol This equation is a simplified form of the following transesterfication reaction. O || CH2 - O - C - R1 | | O | || CH - O - C - R2 + 3 CH3OH | (Catalyst) | O | || CH2 - O - C - R3 triglyceride methanol O || CH3 - O - C - R1 O || CH3 - O - C - R2 O || CH3 - O - C - R3 mixture of fatty esters CH2 - OH | CH - OH | CH2 - OH

+

glycerol

Figure 1. Transesterification Reaction where R1, R2, and R3 are long chains of carbons and hydrogen atoms, sometimes called fatty acid chains. There are five types of chains that are common in soybean oil and animal fats (others are present in small amounts): Palmitic: Stearic: Oleic: R = - (CH2)14 CH3 R = - (CH2)16 CH3 R = - (CH2)7 CH=CH(CH2)7CH3 16 carbons, (including the one that R is attached to.) (16:0) 18 carbons, 0 double bonds (18:0) 18 carbons, 1 double bond (18:1)

1

Table 1. Composition of Various Oils and Fats. Oil or fat 14:0 16:0 18:0 Soybean 6-10 2-5 Corn 1-2 8-12 2-5 Peanut 8-9 2-3 Olive 9-10 2-3 Cottonseed 0-2 20-25 1-2 Hi linoleic Safflower 5.9 1.5 Hi Oleic Safflower 4.8 1.4 Hi Oleic Rapeseed 4.3 1.3 Hi Erucic Rapeseed 3.0 0.8 Butter 7-10 24-26 10-13 Lard 1-2 28-30 12-18 Tallow 3-6 24-32 20-25 Linseed Oil 4-7 2-4 Yellow grease 2.43 23.24 12.96 16:1=3.79 (Typical)

18:1 20-30 19-49 50-65 73-84 23-35 8.8 74.1 59.9 13.1 28-31 40-50 37-43 25-40 44.32

18:2 50-60 34-62 20-30 10-12 40-50 83.8 19.7 21.1 14.1 1-2.5 7-13 2-3 35-40 6.97

18:3 5-11 trace trace trace

20:0

22:1

13.2 9.7 .2-.5 0-1 25-60 0.67

7.4

50.7

Data derived from Organic Chemistry, W.W. Linstromberg, D.C. Heath and Co., Lexington, MA, 1970.

Linoleic: Linolenic:

R = - (CH2)7 CH=CH-CH2-CH=CH(CH2)4CH3 18 carbons, 2 double bonds (18:2) R = - (CH2)7 CH=CH-CH2-CH=CH-CH2-CH=CH-CH2-CH3 18 carbons, 3 double bonds (18:3)

These chains are designated by two numbers separated by a colon. The first number designates the number of carbon atoms in the chain and the second number designates the number of double bonds. Note that the number of carbon atoms includes the carbon that is double bonded to the oxygen atom at one end of the fatty acid (called the carboxylic carbon). This is the end that the methanol attaches to when methyl esters are produced. Table 1 shows the percentages of each fatty acid chain present in common oils and fats. For simplicity, consider an oil such as soybean oil to consist of pure triolein. Triolein is a triglyceride in which all three fatty acid chains are oleic acid. This is near the actual number of carbons and hydrogens and gives a molecular weight that is near the value for soybean oil. If triolein is reacted with methanol, the reaction will be that shown in Figure 2. Note that weights for each of the compounds in the reaction are given. These are based on the fact that one molecule of triolein reacts with 3 molecules of methanol to produce 3 molecules of methyl oleate, the biodiesel product, and one mole of glycerol. Chemists typically multiply all the terms of this equation by a large number that corresponds to the number of molecules in a quantity equal to the molecular weight of the substance. This quantity is called a mole of the substance. To calculate the molecular weight of triolein, we count the number of carbons in the molecule (57) and multiply

2

O || CH2 - O - C - (CH2)7 CH=CH(CH2)7CH3 | | O | || CH - O - C -