Biodiesel extraction

In brief about biodiesel extraction

1. EXTRACTION OF BIOFUELS FROM CROP PLANTS

2. BIODIESEL Biodiesel -  a mixture of monoalkyl long chain(methyl, ethyl, or propyl ) fatty esters derived from organic sources such as vegetable oil , animal fat, plants, organic wastes - based diesel fuel . Biodiesel is typically made by chemically reacting  lipids  with an  alcohol  producing  fatty acid esters .

3. Biodiesel – Crops & Yields Oil Content US gal/acre Liters oil/ha Kg oil/ha Crop 50% - 55% 151 1413 1188 Castor beans 70% 287 2689 2260 Coconut 12% 18 172 145 Corn (maize) 13% - 15% 35 325 273 Cotton 30% - 35% 202 1892 1590 Jatropha 35% 635 5950 5000 Palm oil 36% 113 1059 890 Peanuts 37% 127 1190 1000 Rapeseed 15% 48 446 375 Soybean 32% 102 952 800 Sunflower Source : www.journeyforever.com – Jan. 2007 – This data is compiled from a wide variety of sources. The yield figures are most useful as comparative estimates, crop yields vary widely.

4. Oil feedstock Waste vegetable oil (WVO) Animal fats including tallow, lard, yellow grease, chicken fat, and fish oil. Algae, which can be grown using waste materials such as sewage Oil from halophytes such as  Salicornia bigelovii , which can be grown using saltwater in coastal areas. Sewage Sludge – The sewage-to- biofuel field is attracting interest from major companies like Waste Management and start ups like Info Spi .

5. What makes a fuel different from others are - Its cetane number and heat of combustion. The viscosity of a fuel is important because it influences the atomization of the fuel being inserted into the engine combustion chamber. The biodiesel fuel property of having the viscosity much closer to diesel ,which burns cleaner. Observing the physical properties of biodiesel fuel, it is liquid which can be different in color , from golden and dark brown, all depending on the production feedstock. It is immiscible with water, has a high boiling point and low vapor pressure. The flash point of biodiesel is considerably higher than that of petroleum diesel. Biodiesel fuel has a density of ~ 0.88 g/cm³, which is less than that of water. Studying the chemical properties of biodiesel fuel, its calorific value is about 37.27 MJ/L, which is 9% lower than regular petrodiesel . It has practically no sulfur content, and is frequently used as an additive to Ultra-Low Sulfur Diesel (ULSD) fuel. Biodiesel fuel has an effect on copper-based materials and as well as zinc, tin, lead, and cast iron. However, the stainless steels and aluminum are not affected by bio fuel.

6. How Should Oilseeds Be Processed before Pressing? Extraneous material should first be removed from the harvested crop such as small stones are removed prior to crushing and extraction. The seed should also be passed over a magnet to remove metal pieces . Processors sometimes heat the seeds prior to processing to increase the oil yield. Use an integrated steam kettle to heat the oilseeds. The seeds are sometimes crushed and extruded before the final pressing to further enhance oil extraction. The material left after extracting the oil is referred to as “cake” or "meal ." {"Cake" is the official term when the oil is extracted mechanically; "meal" is the term used when oil is extracted using a solvent}. Some seeds, such as soybeans, must be cooked before being pressed to destroy anti-nutritional factors in the cake. Cooking makes the cake suitable for animal feed.

7. EXPELLER CRUDE OIL SEEDS

8. EDIBLE OILS Coconut oil Colza oil, (canola oil) Corn oil, Hemp oil Mustard oil Palm oil Peanut oil Radish oil Rapeseed oil Ramtil oil Rice bran oil Safflower oil  Soybean oil Sunflower oil Tigernut oil "great potential as a biodiesel fuel." Tung oil,

9. NON EDIBLE OILS Copaiba, an oleoresin tapped from species   Copaifera . Jatropha oil Jojoba oil, from the  Simmondsia chinensis Milk bush Nahor oil, pressed from the kernels of  Mesua ferrea Paradise oil, from the seeds of  Simarouba glauca Petroleum nut oil, Pittosporum resiniferum Pongamia oil (also known as Honge oil), Castor oil Cottonseed oil Salicornia oil, from the seeds of  Salicornia bigelovii a halophyte (salt-loving plant) flax oil

10. How Should the Oil Be Processed before Making Biodiesel? Crude oil contains solid material and gums that should be removed from the oil before processing it for biodiesel. The University of Idaho biodiesel laboratory removes impurities by allowing the oil to settle for at least two weeks . This process removes some gums and virtually all of the solids (such as seed coats and dirt). The gums and solids can be drained off the bottom of the tank, or the oil can be decanted off the top, leaving gums and solids behind as a sludge-type material at the bottom. However, small-scale biodiesel producers may benefit from additional degumming processes because this can enhance the quality and yield of the final biodiesel product. Some seeds (such as soybeans) contain more gums than other seeds. The gums can make it more difficult to separate the glycerin at the end of the transesterification process . In addition, because gums contain phosphorous, too much left in the biodiesel can cause it to fail the  ASTM fuel standard specification.

11. Water degumming - Degumming is accomplished by mixing small quantities of water (2 to 3 percent) with the heated oil . The water combines with the gums and precipitates out after the mixture settles for approximately one hour. The water can then be drained off the bottom of the oil. Acid degumming - Gums can also be removed from oil using an acid degumming process. A small amount of citric or phosphoric acid to dissolve the non-water soluble gums. Removing all the water from the oil before further processing is important because the presence of water will hydrolize some of the oil to fatty acids, which will form soap rather than biodiesel. Removing the water can be accomplished by heating the oil to 120° Celsius (248° Fahrenheit) for approximately two hours to boil off the water. Use of a vacuum, if available, permits faster removal of water and allows for gentler heating for prolonged shelf life of the biodiesel

12. A method of producing fuel from plants or other sources could potentially allow us to decrease our dependence on fossil fuels. Energy crops, so-called, include wheat, corn, soybean and sugarcane . Biofuels burn cleaner than fossil fuels, release fewer pollutants and greenhouse gases, such as carbon dioxide, into the atmosphere. They are sustainable and energy companies mix them with gasoline. Biofuels generally fall into two categories, Bioalcohol and Biodiesel. BIOALCOHOL such as ethanol, is created by engineers from yeast and bacteria to break down starch from corn and other plants. BIODIESEL, is created in refineries that use existing oil in crops These kinds of vegetable oils are then treated with alcohol to convert them to biodiesel.

13. Production methods Supercritical process Ultra and high-shear in-line and batch reactors Ultrasonic reactor method Lipase-catalyzed method

14. Supercritical process An alternative, catalyst-free method for transesterification uses   supercritical  methanol at high temperatures and pressures in a continuous process . In the supercritical state, the oil and methanol are in a single phase, and reaction occurs spontaneously and rapidly. The process can tolerate water in the feedstock, free fatty acids(FAA) are converted to methyl esters instead of soap, so a wide variety of feedstocks can be used.High temperatures and pressures are required, but energy costs of production are similar or less than catalytic production routes.

15. Ultra and high-shear in-line OR batch reactor. Ultra and High Shear in-line or batch reactors allow production of biodiesel continuously, semi- continuously, and in batch-mode . This drastically reduces production time and increases production volume. The reaction takes place in the high-energetic shear zone of the Ultra- and High Shear mixer by reducing the droplet size of the immiscible liquids such as oil or fats and methanol. Therefore, the smaller the droplet size the larger the surface area the faster the catalyst can react.

16. Ultrasonic reactor method U ltrasonic waves cause the reaction mixture to produce and collapse bubbles constantly. This cavitation simultaneously provides the mixing and heating required to carry out the transesterification process. Thus , using an ultrasonic reactor for biodiesel production drastically reduces the reaction time, reaction temperatures, and energy input. Hence the process of transesterification can run inline. Industrial scale ultrasonic devices allow for the industrial scale processing of several thousand barrels per day.

17. Lipase-catalyzed method Use of enzymes as a catalyst for the transesterification . Researchers have found that very good yields could be obtained from crude and used oils using  lipases . The use of lipases makes the reaction less sensitive to high free fatty-acid content, which is a problem with the standard biodiesel process. One problem with the lipase reaction is that methanol cannot be used because it inactivates the lipase catalyst after one batch. However, if methyl acetate is used instead of methanol, the lipase is not in-activated and can be used for several batches, making the lipase system much more cost effective.

18. There are three basic routes to biodiesel production from oils and fats: Base catalyzed transesterification of the oil. Direct acid catalyzed transesterification of the oil. Conversion of the oil to its fatty acids and then to biodiesel.

19. The process used to convert oils to Biodiesel i.e the reaction of a triglyceride (fat/oil) with an alcohol to form esters and glycerol Schematic of the Transesterification process

20. The characteristics of the fat are determined by the nature of the fatty acids attached to the glycerine. The nature of the fatty acids can in turn affect the characteristics of the biodiesel. During the esterification process, the triglyceride is reacted with alcohol in the presence of a catalyst , usually a strong alkaline like sodium hydroxide. The alcohol reacts with the fatty acids to form the mono-alkyl ester, or biodiesel and crude glycerol. In most production methanol or ethanol is the alcohol used (methanol produces methyl esters, ethanol produces ethyl esters) and is base catalysed by either potassium or sodium hydroxide. Potassium hydroxide has been found to be more suitable for the ethyl ester biodiesel production, either base can be used for the methyl ester.

21. Mixing of alcohol and catalyst   The catalyst is typically sodium hydroxide (caustic soda) or potassium hydroxide (potash). It is dissolved in the alcohol using a standard agitator or mixer. Reaction. The alcohol/catalyst mix is then charged into a closed reaction vessel and the oil or fat is added. The system from here on is totally closed to the atmosphere to prevent the loss of alcohol. The reaction mix is kept just above the boiling point of the alcohol (around 160 °F) to speed up the reaction and the reaction takes place. Recommended reaction time varies from 1 to 8 hours, and some systems recommend the reaction take place at room temperature. Excess alcohol is normally used to ensure total conversion of the fat or oil to its esters. Care must be taken to monitor the amount of water and free fatty acids in the incoming oil or fat. If the free fatty acid level or water level is too high it may cause problems with soap formation and the separation of the glycerin by-product downstream.

22. Separation   Once the reaction is complete, two major products exist: glycerin and biodiesel. Each has a substantial amount of the excess methanol that was used in the reaction. The reacted mixture is sometimes neutralized at this step if needed. The glycerin phase is much more dense than biodiesel phase and the two can be gravity separated with glycerin simply drawn off the bottom of the settling vessel. In some cases, a centrifuge is used to separate the two materials faster.

23. Alcohol Removal   Once the glycerin and biodiesel phases have been separated, the excess alcohol in each phase is removed with a flash evaporation process or by distillation. In others systems, the alcohol is removed and the mixture neutralized before the glycerin and esters have been separated. In either case, the alcohol is recovered using distillation equipment and is re-used. Care must be taken to ensure no water accumulates in the recovered alcohol stream.

24. Glycerin Neutralization   The glycerin by-product contains unused catalyst and soaps that are neutralized with an acid and sent to storage as crude glycerin . In some cases the salt formed during this phase is recovered for use as fertilizer. In most cases the salt is left in the glycerin . Water and alcohol are removed to produce 80-88% pure glycerin that is ready to be sold as crude glycerin . In more sophisticated operations, the glycerin is distilled to 99% or higher purity and sold into the cosmetic and pharmaceutical markets.

25. Methyl Ester Wash   Once separated from the glycerin , the biodiesel is sometimes purified by washing gently with warm water to remove residual catalyst or soaps, dried, and sent to storage. In some processes this step is unnecessary. This is normally the end of the production process resulting in a clear amber-yellow liquid with a viscosity similar to petrodiesel . In some systems the biodiesel is distilled in an additional step to remove small amounts of color bodies to produce a colorless biodiesel.

26. Blends Blends of biodiesel and conventional hydrocarbon-based diesel are products most commonly distributed for use in the retail diesel fuel marketplace. Much of the world uses a system known as the "B" factor to state the amount of biodiesel in any fuel mix: 100% biodiesel is referred to as B100 20% biodiesel, 80% petrodiesel is labeled B20 5% biodiesel, 95% petrodiesel is labeled B5 2% biodiesel, 98% petrodiesel is labeled B2