1. Hydration Degumming
The key of the physical refining of rice bran oil is to remove the colloidal substance in the oil as much as possible. The colloidal substance not only affects the quality of the product, but also forms the grease stain on the surface of the packing under the action of high temperature, which affects the normal operation of the equipment. In general, the amount of phosphorus oil hydration degumming oil must be ≤30mg/kg. The crude oil was first heated to 80-85¡æ, 0.3% oil added, the concentration of 85% phosphoric acid, rapid mixing 30min. Then add the temperature of 90-95¡æ, 8% of oil, 5% concentration of salt solution slowly stirring 15min after standing precipitation 2h, release the oil feet.
First, the degummed oil temperature to 75-78¡æ, adding temperature of 90-95¡æ, 8% of oil, the concentration of 5% alum solution stir slowly after 15min precipitation precipitation 2h release oil feet. And then the oil temperature rose to 75-78¡æ, adding temperature of 90-95¡æ, 8% of the amount of oil slowly stirring 15min after standing static precipitation 2h, release oil feet back.
Dry degumming before the hydraulic oil degumming oil must be reduced to 0.5% or less. Hydration degumming oil drying is carried out in a continuous packing desolvent dehydrator, the drying vacuum is -0.09Mpa and the oil inlet temperature is 105-110¡æ.
4. Dry Degumming
Drying oil heated to 85¡æ, by adding a fixed amount of 85% of the consumption of edible phosphoric acid, the amount of 0.1% by weight of oil, the rapid mixing by knife mixer after mixing into the leaf filter. And then the residual phospholipids and metal ions are removed to obtain dry degumming oil by filtering waste white clay after decolorization. In general, the dry degumming of oil phosphorus content ≤10mg/kg.
70% of the dry degummed oil was heated to 110¡æ and decolorized into a bleaching tower. 30% of the oil into the oil-soil mixer and mixed with white clay mixture, by vacuum bleaching decolorization tower. Decolorization tower for the two-tier structure, steam mixing. Decolorization vacuum degree of -0.09Mpa, oil decolorization in the decolorization time of 30min, clay dosage of 2% is appropriate. If the decolorization effect is not good, can add a little activated carbon with the use.
Leaf filter operating pressure 0.2-0.3Mpa, bleaching oil by the bag filter into the vacuum decolorization oil temporary storage tank. In general, the color of oil containing phosphorus ≤5mg/kg, color Y35, R6 or so. If the phosphorus content of excessive reasons must be identified before proceeding to the next process.
Decolorization oil by oil-oil heat exchanger, the last heater to 250-260¡æ into the deacidification tower deacidification. The deacidification tower is a structured packing tower. The oil flows downward from the top surface of the packing under the action of gravity, and comes into full contact with the saturated steam injected from the bottom to achieve the purpose of deacidification by stripping. The flow time of the oil in the tower is 5min, the direct steam consumption is 2% of the oil weight and the vacuum absolute pressure is less than or equal to 200Pa. The deacidified oil flows into the delayed decolorization tank under the action of gravity.
8. Delay Decolorization
In the high temperature, high vacuum conditions, deacidified oil chlorophyll, carotenoids and other heat-sensitive pigment is decomposed to remove. Delay decolorization tank for the horizontal tank, the internal divided into four cells, the internal flow of oil in order. Time decolorization temperature of 240-245¡æ, vacuum absolute pressure ≤200Pa, time 60min or so. The oil overflows to the deodorization tower under gravity.
Deodorization tower for the structure of packing tower, the oil from the top of the filler surface under the action of gravity down, with the bottom of the spray into the full contact steam saturated to achieve the purpose of stripping deodorization. Oil flow time in the tower is about 15-20min, deodorization temperature ≥230¡æ, direct steam consumption of about 1% of the weight of the vacuum, vacuum ≤200Pa. The deodorized oil withdrawn from the bottom of the column was cooled to below 40¡æ by an oil-oil heat exchanger and finally a condenser. In general, deodorized oleic acid value ≤0.2mgKOH/g, color Y20, R2 or so.
The deodorized and deodorized mixed fatty acids were collected by a structured packing trap and then passed to a fatty acid recycling tank where the mixed fatty acids were cooled to 60-70¡æ. The cooled mixed fatty acids are pumped by a fatty acid circulating pump into the top distributor of the capture tower. Fatty acid flows from top to bottom on the surface of the filler, and comes into contact with a high-temperature mixed fatty acid vapor flowing from the bottom to the top. The heat exchange takes place and the mixed fatty acid vapor becomes liquid and is trapped. Generally, the mixed fatty acid has an acid number between 150 and 190 mgKOH/g.
Deodorized oil by the plate heat exchanger and frozen liquid heat transfer, the oil temperature dropped to 22-25¡æ after the pump into the stainless steel crystallization tank, in the stirring effect, the use of coil cooling fluid circulation to slowly cooling to 18¡æ to form crystals. Crystallization time of about 3h. Crystallization oil pressure into the crystal tank, constant temperature 18¡æ under the conditions of crystal filter 3h, too wax oil.
The dewaxed oil is pumped into the stainless steel degreasing tank and slowly cooled down to 3¡æ by using the jacket cooling liquid circulation under the slow stirring with the scraper device. 3¡æ incubation under constant temperature 6h filter was defatted rice bran oil.
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