Fats and Oils Quality, Characteristics, Extraction and Refining Overview

Transcription

1 Fats and Oils Quality, Characteristics, Extraction and Refining Overview Prepared By: Ralph Turner, P.E. Prepared For Presentation To: Farm, Manchester NH

2 Resume Registered Professional Engineer 25 Years in Energy Related Fields - Design and Construction 10 Years in Energy Conservation 10 Years in Alaska Petrochemical 5 years in Biodiesel nationwide Owner s Technical Representative on the design and construction of a 45,000,000 gpy Biodiesel Plant in Erie, PA Co-Owner Laughing Stock Farm 12 Acre Certified Organic Mixed Vegetable Farm Located in Freeport, Maine. Developed Triglyceride Burner Fuel system for heating 12,500 sf of Greenhouses. Winter growers of specialty vegetables vegetables grown year round since 2003 using triglyceride burner fuel for heat. Chair ASTM Sub P Working Group Standard Specification for Triglyceride Burner Fuels. 2

3 Preface Historically meal (for human and animal food), lecithin, tocopherols, and food grade fats and oils have been the primary economic drivers of production. Until recently fats and oils have been in surplus, and considered a relatively low value byproduct. Only recently have energy uses of fats and oils begun to be economically viable. Food value of fats and oils is still far above the energy value of fats and oils. Industrial and technical value of fats and oils is still above the energy value of fats and oils. Animal feeds value of fats and oils tends to remain below the energy value of fats and oils. 3

4 Fats and Oils Quality Oil Quality is the physical and chemical properties of fats or oils that are necessary for any specific purpose as stated in a product specification or certificate of analysis. 4

5 Measurement of Fats and Oils Quality Organizations that maintain standard specifications and test methods: American Oil Chemist Society (AOCS) Fats and Protein Research Council (FPRC) National Renderers Association (NRA) American Society for Testing Materials (ASTM) Proctor and Gamble 5

6 Yellow Grease Specification (Example) Yellow grease is made up of restaurant greases (fats and oils from cooking). Another source could be from rendering plants producing lower quality tallow. Yellow Grease Specs - Guaranteed Analysis: Titer AOCS Tr 1a-64 T 31 C Min. Free Fatty Acid AOCS Ca 5a-40 15% Max. FAC Color AOCS Cc 13a 39 Max. M.I.U. 2% Max. Moisture AOCS Ca 2c-25 1% Max. Insoluable AOCS Ca 3a-46 Unsaponifiable AOCS Ca 6a-40 Information from Darling International 6

7 Biodiesel - ASTM D6751 Specification Example 7

8 Major Factors Affecting Oil Quality Pre-Process Factors Growing Season Temperature, Moisture, Sunlight. Soil Fertility and Nutrients. Post Harvest Storage Conditions - Temperature, Moisture, etc. Post-Process Factors Heat - Thermal degradation from pressing or cooking. Moisture - Hydrolysis from contact with water in pressing, cooking, and storage. Air Contact - Oxidation from contact with air during pressing, cooking, and storage 8

9 What Makes It A Fat Vs. An Oils Fats and Oils include all vegetable and animal oils and fats. Per the American Oil Chemist Society (AOCS) the definition of an oil is a triglyceride that is mostly liquid at 68 deg F. A fat is mostly solid at 68 deg F. Some common examples include: Cooking oils like soy, canola, and corn oil. Edible fats like some tallow and lard. Some less common examples include: Choice white, yellow, and brown grease. Non-edible rendered animal fats. 9

10 Fats and Oils Molecular Composition Animal fats and vegetable oils are triglycerides. They consist of three fatty acids attached to a glycerin backbone. Oils tend to contain more unsaturated fatty acids. Fats contain more saturated fatty acids. 10

11 Fatty Acids Molecular Composition 11

12 Free Fatty Acid Free fatty acids are the single most important contributor to quality degradation in fats and oils. Fatty acids are acids because they meet the Bronsted/Lowry definition of an acid as a compound which donates a hydrogen ion (H+) to another compound called a base. When fatty acids dissociate from the glycerin backbone exposing the hydrogen ion (radical) they become free fatty acids. Because of the activity of the hydrogen ion (radical) and the weak double carbon bonds, free fatty acids readily combine and recombine in unpredictable and indefinable ways to form extremely complex polymer networks. 12

13 Soybean Oil Composition 13

14 Fatty Acid Profiles of Various Triglycerides Weight % of Fatty Acids in Fats and Oils 14

15 Oil Extraction Primary Oil Recovery Methods Hard Press Extraction Pros Low capital cost, small scale, provides high oil meal for niche cattle feeds. Cons poor oil and meal quality, high energy input, low recovery efficiency, not suitable for low oil content seed, high oil meal is detrimental for poultry feeds. Solvent Extraction Pros High quality oil and meal, low energy input, high recovery efficiency Cons High capital cost, high system complexity, higher environmental risk. Rendering only used for animal fats and not discussed here. 15

16 Typical Oil Contents Oil Bearing Material Oil Content % Canola 40 to 45 Coconut 65 to 68 Corn 3 to 6 Cottonseed 18 to 20 Olive 25 to 30 Palm 45 to 50 Peanut 45 to 50 Safflower 30 to 35 Soybean 18 to 20 Sunflower 35 to 45 16

17 Hard Press Extraction Procedure Seed (or beans) are dried (post harvest) for storage. Dried seed is preheated. Preheated seed is fed to press. Feed preheat, pressure, and press temperature are balanced for optimal oil removal. Heat removal is necessary for optimal quality. Cake is recovered in bins. Oil flows to sediment basin. Sediment (foots) are returned to press. Crude Oil is filtered and pumped to storage. Quality Optimal cake quality is 3-4% oil content. Typical small scale cake quality is 6-10% oil content. 17

18 Solvent Extraction Procedure Seeds (or beans) are dried (post harvest) for storage. Dried seed is crushed, conditioned and flaked. Flake is fed into the extractor. Solvent is percolated through flake. Miscella (solvent oil mixture) is collected in the sump. Solvent is recovered by distillation to a separate vessel. Meal and oil are transferred to storage. Quality Typical cake quality is 0.5 to 1% oil content. 18

19 Recovered Crude Oil Contents of recovered crude oil Triglycerides Free fatty acids Gums of phospholipids Crude lecithins Metal complexes; iron, copper, calcium, magnesium Peroxides and degradation polymers Color pigments Sterols, Tocopherols Meals Waxes Moisture Dirt 19

20 Crude Oil Treatment Edible fats and oils are usually designated as RBD and treated as follows: Refining Removal of Phosphatides (degumming) Neutralization and removal of FFA Removal of minor components. Bleaching Not normal for fuels Removal of colors Deodorizing Not normal for fuels Removal of aromatics objectionable to end user 20

21 Degumming Crude oils contain phosphatides in two forms: nonhydratable phosphatides (NHP) hydratable phosphatides (HP) Degumming is the treatment of crude oils with dilute acid solutions and water to remove phosphates, waxes, and other impurities that tend to settle over time and clog piping, pumping, and control systems. A dilute acid treatment is used to convert the nonhydratable phosphatides to hydratable phosphatides. Water is added to convert the hydratable phosphatides to hydrated gums which are insoluble in oil and readily separated as sludge by settling, filtering, and centrifuge. Degumming is followed by Caustic Refining as described below: 21

22 Caustic Refining The addition of a dilute alkali solution to bring about chemical and physical reactions that assist in the removal of unwanted constituents of the crude oil. Alkali combines with FFA to make soaps. The gums and some remaining NHP absorb alkali and coagulate, easing separation. Much of the other insoluble material is entrained in the soaps and coagulable material. 22

23 Process Flow Diagram 23

24 Variables Crude Oil Variables (From growing and storage conditions) FFA Defined by Standard Test Method Phosphorus Levels Defined by STM Process Variables (Set by the process operator) Temperature Acid and Caustic Concentrations Agitation Rate Dwell Time Quality (Determined by the skill of the process operator) See the next Slide 24

25 Soybean Oil Composition 25

26 Rhetorical Question If a farm can produce vegetable oils for fuel (which is a relatively low value product) can a few steps be added to allow the production of specialty salad and other food oils (which have a very high value) to maximize the farm revenue and profits? In other words, regardless of whether oil is worth more as food to society, can edible oil be worth more to the farmer on a small local or regional scale? Ralph Turner, PE 26