The conventional refining process of soybean oil edible oil includes degumming, deacidification, decolorization and deodorization, and the decolorization section is one of the important sections affecting the refining effect.
Soybean oil refinery plant is the main equipment in soybean oil processing process. Usually the soybean oil refinery plant is used to refine the crude oil by removing substances that may have an effect on the quality of soybean oil and harmful impurities that may do harm to people’s health. In order to achieve this goal, soybean oil refinery plant needs to go through a series processing procedures such as degumming, neutralization, bleaching, and deodorization.
Generally speaking, the methods of soybean oil refining can be divided into chemical refining and physical chemical refining according to the differences in the selection of raw materials and the different ways of operation. These two soybean oil refining methods seem to exist alone, but in actual operation, they cannot be completely separated. Sometimes both physical and chemical refining methods are used in the same soybean oil refining process. Therefore, soybean oil refining is a more flexible process, so it is necessary to pay attention to the changes of the oil in operation and accordingly adopts the most suitable oil refining method based on the proper technical conditions and economic conditions.
Physical refining of soybean oil:
In physical refining, soybean oil is distilled to remove free fatty acids. Alkaline treatment is completely avoided. This reduces waste water and eliminates soap production. This process is becoming more and more popular.
Chemical refining of soybean oil:
In chemical refining, soybean oil is treated with caustic soda to separate free fatty acids from the oil. This is a traditional process that works with all oils. A by-product of alkali refining is soap stock, which is used to make low-quality laundry soap. Alternatively, the soapstock can be treated with acid to recover fatty acids. Wastewater from soybean oil refineries requires extensive treatment. This can be avoided by alternating physical refining processes.
Main Steps of Soybean Oil Refinery Plant:
1. Degumming is the first step in soybean oil refinery plant. In this step gums in crude oil are removed by hydration with the help of phosphoric acid.
2. In this step, free fatty acids are neutralized by using sodium hydroxide and convert them into soap. Additional impurities are also removed by adsorption on soap.
3. During bleaching process, unwanted pigments are adsorbed physically and oil will become much clearer.
4. Deodorization machine is used to remove unacceptable odors by steam distillation during soybean oil refinery plant, the odoriferous compound are stripped off with the help of live injected steam into heated oil under high vacuum pressure.