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BTC PTEC Biodiesel Workshop. August 7 – 8, 2006 Session 7 – Feed stock and biodiesel quality. Agenda for session. Feedstocks for biodiesel US and WA feedstocks Oil yields for different sources Comparison of feedstocks Feedstock preparation Feedstock quality issues and tests
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BTC PTEC Biodiesel Workshop August 7 – 8, 2006 Session 7 – Feed stock and biodiesel quality
Agenda for session • Feedstocks for biodiesel • US and WA feedstocks • Oil yields for different sources • Comparison of feedstocks • Feedstock preparation • Feedstock quality issues and tests • Comparison of biodiesel from different feedstocks • Evaluation of biodiesel quality
Feedstocks for biodiesel • Vegetable oils (most volume) • Soybean • Rapeseed • Palm • Animal fats (lower cost) • Rendering plants • Spent oils (lowest cost, so far) • Yellow and grey grease
Vegetable oil production in WA(Armstrong, 2005) • WA crops (millions of planted acres) • 2.3 in wheat • 0.337 in barley • 0.0077 in canola • 100,000 acres needed for a 5 million gallons/year canola/mustard biodiesel plant • Not promising due to • Closest crushing facility is in Montana • Low current market prices • Little experience with oil crops
Vegetable oil yeilds • US • Soybean oil (0.4 T oil/ha, 20% yield from seeds) • Canola and mustard oil (40% yield from seeds) • Europe • Rapeseed oil (0.5 T/ha, 40% yield from seeds) • Sunflower oil (0.5 T/ha) • Tropics • Palm oil (4 T/ha)
Comparison of feedstocks • Vegetable oil • Unrefined (high phospholipid content) un-degummed oils have separation problems in the process • Refined (better product) • Animal fats • Lower cost • Higher concentrations of saturated FA • Biodiesel products may have higher freezing points • Higher cetane numbers
Comparison of feedstocks • Spent oils • Trap grease (odor, moisture and color problems for this low cost feedstock) • Brown grease (FFA > 15%) • Yellow grease (FFA < 15%) • Cheaper
Feedstock preparation • Harvesting • Crushing and pressing to separate the oil • Filtration • Removal of gums (phosphatides – 1.5 to 2.5% and unsaponifiable matter – 1.6%) • Removal of free fatty acids (0.3 – 0.7%, soybean oil) • Bleaching and deodorizing
Feedstock quality issues • Free fatty acids (variable) • Phosphorus (may be 600 – 900 ppm in soybean oil • Sulfur (usually low, < 3 – 5 ppm in vegetable oil but may be higher in animal fats, 40 – 50 ppm) • Iodine value (level of saturation) • Water (variable) • Solids (should be filtered, 100 micron)
Feedstock quality tests • Fatty acids • Specific gravity • Refractive index • Iodine number • Saponification number • Color
Free fatty acid concentrations • Refined vegetable oil < 0.05% • Crude soybean oil 0.3 – 0.7% • Yellow grease 2 – 7% • Animal fat 5 – 30% • Trap grease 75 – 100%
Problems in feedstocks due to • Free fatty acids (can react with catalyst to make it ineffective) • Phosphorus (ASTM fuel limitation of 10 ppm) • Sulfur (ASTM fuel limitation of 15 ppm) • Water (can deactivate the catalyst interfere with the reaction and methanol recovery)
Processing High FFA Feedstocks • High FFA from animal stock and spent grease • Mainly acid catalyst to form esters (forms water) so that FFA <0.5%, followed by normal base catalyst transesterification • Or just do normal transesterification and live with results (loss of FFA and possible emulsion formation) for low FFA levels
Product quality tests • ASTM D6751 tests • BQ-9000 tests • Others • Physical properties • Iodine number
Product quality issues • Quality of the feedstock • Fatty acid composition • Contaminants (solids, moisture) • Processing • Chemicals used (nature and purity) • Completeness of reaction • Tri, di, mon glyceride products for incomplete reaction • Contaminants • Clean up steps (Water wash or Magnesol) • Post production • Filtration (5 micron)
Product quality • Glycerols (easily removed by washing) • Total glycerol < 0.24% • Free glycerol < 0.02% • Monoglycerols have low solubility in product • Alcohol • Biodiesel may have 4 – 5% alcohol • < 0.1% indirectly due to flash point limit • Small amounts will not affect engine • Catalyst • sulfated ash < 0.02% limit • Mostly removed with glycerin phase