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 The main work of the soybean leaching equipment is to extract the oil from the pretreated soybean meal in the extractor through the countercurrent circulating fresh solvent, and realize the separation and recovery of the solvent in the wet meal and mixed oil. The crude oil obtained by leaching is subjected to soybean oil refining equipment to remove impurities to obtain refined soybean oil. The working process of soybean oil leaching equipment can be divided into the following 5 stages.

　　 1. Soybean oil extraction

　　 Soybeans are called soybean meal after pretreatment, and then enter the soybean extractor and are sprayed and extracted by hot fresh solvent in countercurrent circulation to realize the separation of oil and meal. In the extraction process, the oil in the oil can be dissolved in the solvent to realize the process of oil transfer from the solid phase to the liquid phase. The driving force of mass transfer is mainly the difference in the concentration of oil in the solid and liquid phases, which is accomplished by means of molecular diffusion and convective diffusion.

　　2. Steaming, drying and cooling of the leached soybean meal

Soybean meal after leaching soybean oil contains about 25-30% of solvent. In order to recycle the solvent, the characteristics of the solvent are heated by indirect steam, and the solvent in the white cake is steamed and condensed by direct steam stripping. In the process of heating and desolventizing, the urease activity in the soybean meal is inactivated, and the protein is partially denatured and Maillard reaction occurs during the heating process, giving it a special fragrance.

The moisture content of soybean meal after steaming and de-steaming will rise to about 16%. This moisture does not meet the product quality requirements and storage requirements. It must be dried and cooled to make the soybean meal moisture and temperature meet the product quality and storage requirements. , To go through the steaming off, drying and cooling of the meal.

　　 3. Soybean mixed oil evaporated

　　The solvent content of the leached soybean mixed oil is about 70%. Taking advantage of the large difference in boiling point between the solvent and the oil in the mixed oil, the solvent component is vaporized and volatilized by heating, so that the oil component is concentrated. According to the principle that the boiling point of the mixed oil decreases with the decrease of the system pressure, the vacuum equipment is used to form a certain negative pressure in the evaporator, so that the solvent in the mixed oil can be evaporated at a relatively low operating temperature.

　　4, soybean mixed oil stripping

After two evaporations, the concentration of the mixed oil is 95-99%. The boiling point of the high-concentration mixed oil is quite high even under high vacuum, and the oil and its accompanying substances and pigments are easily decomposed under the high boiling point. Need to use steam stripping to further remove the solvent remaining in the oil.

　　 In the absence of water vapor, there is mainly solvent vapor pressure on the surface of the mixed oil. There is a gap between the solvent vapor pressure and the external pressure. Only the surface vaporizes, and the mixed oil is difficult to boil. If steam is introduced into the stripping tower, the vapor pressure volatilized on the mixed oil surface is mainly composed of the solvent partial pressure and the water vapor partial pressure, as long as the vapor partial pressure of the water vapor plus the solvent vapor partial pressure is equal to the external pressure The pressure mixed oil will boil, and the solvent molecules in the oil can volatilize from the mixed oil. That is, the introduction of water vapor reduces the partial pressure of the solvent vapor, thereby reducing the boiling point of the mixed oil.

　　The residual solvent in the oil after steam stripping can be reduced to below 50ppm.

　　 5. Solvent recovery in free gas

　　 The air enters the extractor with the feed, and enters the entire extraction equipment system to mix with the solvent vapor. This part of the air cannot be condensed into liquid, so it is called "free gas". The free gas from the extractor, water distribution tank, mixed oil tank, condenser, and solvent circulation tank is all collected in the air balance tank, and then enters the final condenser. After the solvent contained in the free gas is partially condensed and recovered, there is still uncondensed gas (tail gas), which still contains a small amount of solvent. The following three methods can be used for recovery and then discharged into the atmosphere.

　　①Return of the absorption tower: Free gas enters the absorption tower with packing, cool water is added from top to bottom of the tower, the solvent in the tail gas is absorbed again, the liquid enters the water separation tank for separation, and the tail gas is discharged into the atmosphere through the flame retarder.

　　②Recovery by refrigeration method: The tail gas from the condensation of free gas is condensed and recovered by low-temperature treatment. The recovered liquid enters the water distribution tank, and the tail gas is discharged into the atmosphere by the fan.

　　③ Paraffin oil absorption method: Free gas enters the bottom of the absorption tower and passes through the packing layer in the tower. The solvent in the gas is absorbed by the liquid paraffin sprayed from the top of the tower. The gas after absorption, exchange and desolventization is exhausted to the atmosphere by a fan. After absorbing the solvent, the paraffin oil mixture goes to the preheater for heating, and then to the desorption tower, where it is desorbed and desolvated by direct steam. The mixed gas after analysis is decondensed again for separation. After the parsed paraffin is cooled by the cooler, it is redistributed to the absorption tower to become a fresh paraffin absorption liquid, and the cycle works like this.

　　 The above is the working process of soybean oil extraction equipment in soybean extraction. Soybean oil content is low, the production efficiency of oil production by pressing method is low, and the residual oil rate is high. Therefore, when selecting the process, the factory often chooses the one-time leaching process of soybean extraction equipment to extract soybean oil. The production efficiency of leaching oil production is high, and the residual oil rate of leaching soybean meal is low, only about 1%. The quality of the leaching cake is high and rich. Protein can be used in livestock feed processing industry.