The residual oil in soybean meal is a key factor affecting the oil yield in soybean oil solvent extraction line. Factors affecting meal residual oil include equipment, technology, pre-treatment and personnel operations. Here is a brief analysis of some factors affecting meal residual oil:
1. Leaching time
When grease and solvent come into contact, according to the principle of similar miscibility, grease and solvent dissolve into each other. In this process, grease molecules are transferred to the solvent, and solvent molecules are also transferred to the grease until the concentrations of solutes in the two-phase solvents are exactly the same and a dynamic equilibrium is reached. In the leaching production process, we often use the countercurrent leaching method, that is, in the leaching equipment, the continuously entering oil is gradually leached with mixed oil of gradually dilute concentration, and finally, fresh solvent is used to leach the oil with very low residual oil, and almost all the grease in the oil is leached out. Theoretically, it is optimal for each leaching to reach a dynamic equilibrium state. However, due to equipment limitations, each leaching can only approach but not reach dynamic equilibrium. Therefore, the length of leaching time is particularly important here. In actual production, we can reduce the residual oil in the meal to a certain extent by appropriately reducing the operating speed of the leaching equipment, increasing the height of the material layer, and extending the leaching time.
2. Solvent ratio
The solvent ratio refers to the volume ratio of the solvent to the material used when extracting oil from the leached material.
When the solvent ratio is large, the concentration of the mixed oil produced during the leaching process is low, the concentration difference between the solvent and the oil in the mutual mass transfer process is large, and the mass transfer speed is faster, so the time required for leaching under the same conditions is shorter. On the contrary, when the solvent ratio is small, the mass transfer speed between the solvent and the oil will decrease, and the extraction time will be longer under the same conditions. In the actual production process, due to the influence of various factors such as equipment, environmental protection, and economic benefits, the solvent ratio cannot increase infinitely. Therefore, the solvent ratio needs to be controlled within a reasonable range, which can not only meet the needs of production and environmental protection, but also reduce production costs. If conditions permit, appropriately increasing the amount of fresh solvent spray can reduce the residual oil content of the meal to a certain extent.
3. Leaching temperature
The temperature of the leaching process is determined by the material temperature, solvent temperature and the ratio of their quantities. The temperature of the leaching process has a great influence on the speed and effect of leaching. When the temperature is higher, the disordered movement of molecules is strengthened, the viscosity of solvent and oil decreases, the resistance in the transfer process between oil molecules and solvent molecules decreases, the transfer speed of molecules is increased, the time required to achieve dynamic balance can be reduced, and theoretically the content of residual oil in the meal after leaching can be reduced. However, the leaching temperature is limited by the initial boiling point of the solvent and the initial boiling point of the mixed oil and cannot be increased arbitrarily. That is, the temperature of the leaching process must not exceed the boiling points of the solvent and the mixed oil. Otherwise, a large amount of solvent will vaporize, which will reduce the leaching solvent ratio and increase the pressure in the leaching equipment. In actual operation, the extractor only needs a slightly negative pressure state. According to the load of the exhaust gas treatment system and other conditions, increasing the leaching temperature within a certain range can also reduce the residual oil in the meal to a certain extent.
The above are several main factors that affect the residual oil in the meal during daily leaching operations. In addition, factors such as the type of leaching equipment, material pre-treatment process, moisture content and powder ratio are also very critical to the impact of meal residual oil. If you need to know more about the cooking oil leaching process and equipment, please contact us quickly!
