Soybean oil refining process：
1. Hydration Degumming & Alkali Refining Deacidification Process
Neutralization: The crude oil is output by the oil feed pump from the oil tank, and enters the crude oil heat exchanger to recover part of heat after metering and then is heated to the required temperature by the heater. After that, the oil is mixed with the metered phosphoric acid or citric acid from phosphate tank in the gas mixture (M401), and enters the conditioning tank (R401) to change the non-hydratable phospholipids in oil into the hydratable phospholipids. Add the alkali for neutralization, and the alkali quantity and alkali solution concentration depend on the quality of the crude oil. Through the heater, the neutralized oil is heated to the temperature (90℃) suitable for centrifugal separation to remove the phospholipids, FFA and other impurities in the crude oil. Then the oil goes to the washing process. Washing: About 500ppm soap is still in the neutralized oil from the separator. To remove the remained soap, add about 5~8% hot water into the oil, with water temperature 3~5 ℃ higher than the oil generally. To achieve more stable washing effect, add phosphoric acid or citric acid when washing. The re-mixed oil and water in the mixer is heated to 90-95℃ by the heater, and then enters the wash separator to separate the remaining soap and most water. The water with soap and oil enters into oil separator to separate out oil in the water. Further catch the oil outside, and the waste water is discharged to the sewage treatment station. Vacuum drying stage: There is still moisture in the oil from the wash separator, and the moisture will affect the stability of the oil. So the oil at 90℃ should be sent to vacuum drier to remove the moisture,then the dehydrated oil goes to the decoloring process. Finally, pump out the dry oil by canned pump.
2. Continuous Refining Decoloring Process
The main function of decoloring process is to remove oil pigment, residual soap grain and metal ions. Under negative pressure, the mechanical mixing method combined with steam mixing will improve the decoloring effect. The degummed oil firstly enters into the heater to be heated to the appropriate temperature (110℃), then goes to the bleaching earth mixing tank. The bleaching earth is delivered from the low bleaching box to the temporary tank by wind. The bleaching earth is added by automatic metering and is interlockingly controlled with the oil. The oil mixed with the bleaching earth overflows into the continuous decolorizer, which is stirred by non-powered steam. The decolored oil enters into the two alternate leaf filters to be filtered. Then the filtered oil enters the decolored oil storage tank through the security filter. The decolored oil storage tank is designed as the vacuum tank with the nozzle inside, so as to prevent the decolored oil contacting with the air and influencing its peroxide value and color reversion.
Continuous Decoloring Process Features:
1. The oil fully contacting with the decolorant can improve the decolorization efficiency and reduce the usage of decolorant;
2. The continuous and uniform material flows will balance the decoloring time and avoid the recovery of grease oxidation and acid value.
3. The special mixing structure of decoloring tower won’t cause the material dead area, which can avoid the adsorbent sedimentation and pipe blockage.
4. The continuous airtight efficient filtration equipment has realized the automation of cake discharge and reduced the labor intensity.
5. The advanced drying technology can reduce the oil content in filter cake.
3. Continuous Refining Deodorizing Process
The qualified decolored oil enters into the spiral plate heat exchanger to recover most of the heat, and next goes to high pressure steam heat exchanger to be heated to the process temperature (240-260℃) and then enters the deodorization tower. The upper layer of combined deodorization tower is the packing structure which is mainly used to remove the odor producing components such as free fatty acid (FFA); the bottom layer is the plate tower which is mainly for achieving the hot decoloring effect and reducing the peroxide value of the oil to zero. Oil from the deodorization tower enters into the heat exchanger to recover most of the heat and makes further heat exchange with crude oil, and then is cooled to 80-85℃ through the cooler. Add the required antioxidant and flavor agent, and then cool the oil below 50℃ and store it. Such volatiles as FFA from the deodorizing system are separated by the packing catcher, and the separated liquid is FFA at low temperature (60-75℃). When the liquid level in the temporary tank is too high, the oil will be sent to the FFA storage tank.
4. Automatic Control System
Our company has applied the automatic control system with advancedness, security, reliability into the pretreatment, extraction, refining and fractionation in large oil plants. For its application in automatic control system, it can control the production in the entire workshop and monitor the operational status of each device by controlling the computer terminals in the room. One person only can operate the entire workshop, with efficient production management. It has reduced the production cost greatly and improved the management efficiency.