Experiences with Refining Processes October 9, 2003
Why refining? What does it mean? Alkali vs. Physical refining Degumming process Bleaching Deodorization Quality control storage and loading Summary
Oil recources for vegetable oil Soybean Rapeseed Sunflower seed Cottonseed Palm Kernel Palm Olive Coconut Corn Groundnut
Soybean - Drying - Storage - Field damaged, wet harvest condition, mold, etc. can produce oil high in chlorophyll Rapid drying could activate phospholipase D as well as lipoxygenase Storage temperature > 40 C or a moisture content > 11% can activate enzymes Flaking - Hexane extraction - Extreme exposure of surface occurs Extended exposure to air can cause reactions from lipoxygenase and phospholipase D Can extract some of the products of reaction into the oil Cracking - The seeds are most vulnerable to cracking Desolventisation Dehulling Tempering - Enzyme activity continues during this process Crude oil - Peroxidation can occur during storage
Persistant organic pollution (POP) - Chlorinated pesticides (Aldrin, DDT, etc.) - Industrial chemicals (PCB, HCB, etc.) - Flame retardants (bromine compounds, etc.) - Unwanted by-products (dioxins, furans, PAH, etc.) Heavy metals (cadmium, lead, mercury, etc.) Mineral oil
Advantage / Disadvantage of physical or chemical refining process physical chemical advantages disadvantages advantages disadvantages Higher yields Less of chemicals Runs not stable with poor crude oil quality Less consumption of bleaching earth Lower yields Waste Less of waste Higher consumption of bleaching earth Stable process also for poor oil quality Waste water (sodium sulfat solution) Stable and low cost degumming process not for all kind of oil available Process is easier to run for not qualified workers Lower concentration of tocopherols in the destillat Use of destillat
The alkali neutralization process Dearation Degumming or conditioning (acid treatment) Neutralisation (first alkali treatment) Rerefining (second alkali treatment) Washing Vacuum drying Cooling
Undesirable components in crude oil Phospholipids Carbohydrates Proteins Traces of metals Free fatty acid Colour pigments Oxidation products of fatty acids Volatile components of the crude oil Soap
Process of miscella-ultrafiltration Crude miscella Filtration UF UF Hexane Destillation Destillation Hexane Full degummed oil Lecithin
Soft degumming process Crude oil Heating Mixing EDTA and water Holding Separation Gums Full degummed oil
Enzymax process Adjusting of the ph-buffer Enzyme reaction in the holding tanks Separation of the gums
Adjusting of the ph-buffer Crude oil Water degumming Drying Lecithin (crude) Heating 70 C Mixing Holding 5 minutes Citric-acid solution NaOH solution
Enzyme reaction in the holding tanks Cooling 60 C Recycled gums Enzyme solution Intensive mixing Holding 4 6 hours
Separation of gums 80% of gums back to the degumming-process Heating 70 C 20% of the gums to the toaster Separation Full degummed oil
Enzymax-process without recycling Cooling 45 C Heating 70 C Intensive mixing Enzyme solution Gums to the toaster Separation Holding 4 6 hours Fully degummed oil
Heat treatment process Seed Breaking Flaking Prepressing Extracting Heating 110 C Destillation Desolventizing Drying Water degumming Drying Cooling Lecithin Crude oil p<10mg/kg Meal
Conclusion Acid degumming processes options for normal crude oil quality Soft degumming an option for proper predegummed oil Enzymax process a very good option if the availability of the enzyme is given Heat treatment of seed should be a good option, the results with normal seed quality are excellent Ultrafiltration process needs development work
Continuous bleaching unit
Continuous bleaching unit with first stage of wet bleaching
Continuous bleaching unit with trysil-treatment
Counter current bleaching ÖHMI bleach
Counter current bleaching with Trysil-treatment
Bleaching earth consumption depends on: Kind of oil Qualityof thecrudeoil Specification of finished oil Physical or chemical refining Bleaching earth quality
Process and plant design is determined by: Plant capacity Shut-down and start-up operation Product changes Environmental and local conditions
Continuous Bleacher
Filter cycle Filling of the filter Precoatingbyturbidflow Clear filtration Emptying of the filter Blowing of the filter cake Removal of the filter cake
Process control Peroxide value Absorbance at 232 nm and 270 nm Colour (Lovibond) Chlorophyll < 30 ppb Metals Phosphorus Soap Residual bleaching earth
Deodorization process
Deodorization process with stripper
Possible reaction mechanisms for development of fishy flavor Trimethylamine Trimethylamine oxide + Hydroperoxide (oxidized oil or fatty acid) Formaldehyde + secondary amine (source of fishy odor)
Process control for refined oil Free fatty acid Peroxid number Water content Content of waxes Phosphorus Soap Dirt Taste Colour Chlorophyl Waxes PAH (heavy and light) Pesticides Heavy metals Tocopherols
Conclusion The oil after a proper process is stable and safe - free of pesticides, PAH, etc. - free of heavy metals - no odor, neutral taste - low chlorophyll content - high tocopherol content - meet the specifications We need for the process: - bleaching earth - steam - water - for poor qualities of crude oils in addition chemicals, enzymes