Evaporator is a kind of desolvation and drying equipment for leaching meal commonly used in large, medium and small oil factories at home and abroad; it is also a key equipment for passivating anti-nutritional factors in meal. The steamer is mainly composed of cylinder, pre-delamination, air-permeable layer, desolvation layer, hot air layer, cold air layer, stirring device, transmission mechanism and automatic blanking door mechanism, and the wet meal is heated by direct steam and indirect steam. Distillation and desolvation drying.

   Its working principle is that the leaching meal contains about 25%-30% solvent. In order to recover the solvent, the solvent characteristics can be used to evaporate the solvent in the meal through indirect steam heating and direct steam stripping. After condensation, it can be reused. . In the process of heating and desolventizing, the urease activity in the meal is inactivated, and the protein is denatured and undergoes Maillard reaction during the heating process, so that the meal has a special fragrance. The moisture content of the meal after steam stripping will increase to about 16%, which cannot meet the product quality and storage requirements. Therefore, it must be dried and cooled to make the moisture and temperature of the soybean meal meet the product quality and storage requirements.

Steam off-line working process

  The leached wet meal falls into the pre-delamination through the wet meal scraper and the sealing auger. The pre-delamination function is to use the mixed steam in the lower layer and the indirect steam in the interlayer to preheat the wet meal and remove a small amount of solvent to prevent When the high-temperature direct steam or mixed steam in the lower layers contacts the low-temperature wet meal, too much water vapor will condense in the meal, resulting in the phenomenon of wet meal balling.

   The preheated meal enters the desolvation layer (self-steaming layer), and in the desolventization layer, the wet meal is in direct contact with the mixed gas of solvent vapor and water vapor steamed from the lower layer, and the wet meal is heated by the heat of the mixed steam. Heating, while also using the indirect steam in the bottom interlayer of the desolvation layer to heat, and the desolvation layer is provided with multiple layers to give full play to this self-steaming effect. The desolvated wet meal enters the direct steam layer (roasted meal layer), and there are a large number of small holes with a diameter of 3mm in the bottom interlayer of this layer, and direct steam is sprayed into the meal through these small holes to remove the solvent. In order to prevent the evaporated mixed gas from escaping from the discharge port, the discharge port is sealed with a closed valve. After passing through this layer, the solvent in the meal is completely removed, the temperature reaches above 100°C, and the moisture also increases to about 16-18%.

   The desolvated meal enters the baking layer. The purpose of this layer is to prevent further desolventization due to incomplete desolventization. It can also heat up the meal and remove water in vacuum to facilitate subsequent hot air drying and improve the color and flavor of the meal. In order to strengthen the process of solvent evaporation in the meal, measures such as direct steam, negative pressure and stirring are adopted. Direct steam not only plays the role of high-efficiency heat carrier and rapidly heats wet meal, but also reduces the concentration of solvent vapor on the surface of the material, thereby accelerating evaporation. The function of negative pressure is to reduce the partial pressure of solvent vapor on the surface of wet meal, which also strengthens the process of solvent removal. Stirring the meal layer during the evaporation process is beneficial to the uniform heating of the wet meal and the removal of the solvent in the meal layer. When the solvent content in the meal is large, stirring is very important in the initial stage of evaporation.