Some Technology about Oil Mills
1. Fitlering
Crude Soybean oil usually will goes into the Chamber press filter to remove the impurity which takes from the extraction workshop, if the crude oil is with cleaner quality, it can go into the degumming section dirctly.
2. Degumming and Neutralization
The filtered crude oil will be pumped into the Multi-efficiency mixer at a controlled rate and be heated to about 90oC by the deodorized in a crude oil Economizer/Heat Exchanger as well as by steam in the Heater. A self-cleanning duplex-restrainer is installed in the oil line to protect the pump and the measuring instruments. Phosporic acid is injected at a controlled rate and intensively contracted with the oil in the Acid Mixer thereby precipitating gums which is mainly phospholipids and other hydrophilic colloid impurity. The reaction of the acid and oil occurs in the Reaction tank. The pump conveys the mixture after reaction to the heat exchanger to cool down before adding caustic. The acid conditioned and/or heated oil is reacted with caustic soda solution injected at a controlled rate in the reactin tank after the Caustic Mixer; the caustic neutralizes the free fatty acids and the excess mineral acid in the oil. Forming soap stock which is removed together with the excess caustic solution and the other impurities in the Separator
The neutralized oil contains small amounts of residual soap which must be minimized before further processing. The oil is therefore contacted with soft hot water in the high-speed Wash Mixer. With this way, almost all soap is dissolved in the water phase and removed from the oil in the Wash Separator. The washed oil contains about 0.4% of dissolved water. If the oil will go directly to bleaching, the wet oil can preferably be transferred to the bleaching section directly without removal of the dissolved water. However, if the oil is to be stored for some time before further processing, it should be protected against deterioration by drying and cooling before storage. In that case the oil from the washing stage is sprayed into a Vacuum Dryer where residual moisture is reduced to a minimum.
3. Bleaching
The neutralized oil at 90-110°C is sprayed into the bleach earth oil mixer. Here it is dried and mixed with bleaching earth. The bleaching earth is automatically dosed by the hermetic Earth Proportioning System directly from the Bleach Earth Feed Hopper into the Bleacher via a pipe located below the oil spray to prevent dust from entering the vacuum system. The Earth Dosing System is based on two automated butterfly valves with an intermediate dosing chamber. The valves are sequenced by an adjustable timer system in the control panel. Then the slurry comes into the Bleacher, which is equipped with three steam agitated compartments to ensure proper mixing and retention time so that the colour bodies and oxidizing materials, etc. in the oil are gradually absorbed by the earth. The oil/earth mixture is pumped through one of the Bleaching Filters followed by one of the alternating Polishing Filters where the earth and solid impurities are retained. The Bleaching Filters operate alternately so that one unit is always working while the other one is cleaned. The Bleaching Filter cleaning cycle consists of pressurizing the bleaching filter with steam until the main liquid volume has been discharged and then continuing the blowing of steam via the separator so that the cake is properly deoiled. The residual oil (heel) is then discharged to the Bleacher before opening the Bleaching Filter and vibrating off the dry cake onto a conveyor belt or cart. The Bleaching Filter is then closed and evacuated. The clean Bleaching Filter is filled and pressurized with bleached oil and pre-coated. It is maintained under circulation until the flow has been switched from the other Bleaching Filter.
4. Deodorization
Bleached oil enters the plant and is sprayed into the Deaerator where, with the aid of vacuum, air and moisture is removed. The Deaerator also serves a buffer tank between the bleaching and the deodorization section. The deaerated oil is then re-generatively heated by deodorized oil in the Economizer and then by high pressure steam in the Final Oil Heater to deodorization temperature. The temperature is maintained by automatic control of the steam pressure in the Steam Boiler. In the Final Oil Heater the oil is heated under vacuum and sparing conditions with sparing steam, which will improve heat transfer and start the stripping of the most volatile compounds.The hot oil enters the inner column of the Double Shell Packed Column (DSPC) section of the Deodorizer. The column is filled with special structured packing so that the oil is distributed into a thin film and is evenly agitated by stripping steam flowing counter currently from the bottom of the column. As a result, free fatty acids and other remaining volatile impurities in the oil are evaporated and removed with the steam. The residence time in the column is only a few minutes. This way, the bulk of the free fatty acids along with aldehydes, ketones etc. The oil are quickly stripped off before any heat induced permanent damage has been done. The deodorized oil is regeneratively cooled down in the Economizer under vacuum and sparging conditions. Some odoriferous compounds produced in the oil during hot conditions are promptly removed. Citric acid is injected in the oil in the Economizer. The steam in the holding trays and the Economizer is directed to form the stripping steam in the packed section of the Deodorizer. Citric acid can optionally also be added to the oil before the Deaerator. The oil is discharged by the Economiser Pump and cooled in the Crude oil Economiser. After final cooling in the Oil Cooler, the oil is passed into the Polishing Filter and sent to storage.
5. Electrical Control System
All the electric control system are adopted with famous brand, Excepting all the PLC Control system, we will equip all the system with flow chart simulation screen and double loop buttons.
