Drying equipment in the light chemical industry and the food industry drying method

Drying operation is one of the widely used unit operations in the chemical industry, light industry and food industry. The purpose of drying operation is to remove moisture or solvents from certain raw materials, semi-finished products and finished products. As far as the light chemical food industry is concerned, the purpose is to make the material easy to package, transport, storage, processing and use. Such as milk powder, egg powder, instant coffee and other foods, when the water content is reduced to 1 cast-5 casting can be stored at room temperature for more than a year. Such as salt, washing powder and other particles, when the water content in..2% -0.5%, the material is not easy to block, more convenient to use. Food in the drying process, must also preserve the food vitamins, protein and other nutrients. Therefore, the quality of the drying operation directly affects the use quality and appearance of the product.

Drying equipment can effectively make the solid materials in the light chemical and food industry dry, remove a large amount of uncombined water in the material, and then use heating drying method to remove the residual part of the water (including uncombined water and combined water).

There are three types of drying methods in light chemical industry and food industry:

1. Mechanical dewetting method

When the material with more water, you can first use pressing, centrifugal filtration and other mechanical separation methods to remove a large amount of water.

2. Absorption and dewetting method

with some kind of balanced water vapor partial pressure is very low desiccant (such as: CaCl, silica gel, etc.) and wet materials coexist, so that the water in the material have been transferred into the gas phase of the desiccant. Due to the limited dehumidification capacity of desiccant (hygroscopic agent), it is only used to remove trace moisture in materials, and it is rarely used in light chemical industry and food industry production.

3. Heating and drying method

This is a commonly used drying method in the light chemical industry and food industry. It uses heat energy to heat the water in the materials and vaporized materials. Therefore, removing water requires a certain amount of calories consumed. For example, when air is used to dry the material, the air is heated in advance and sent to the dryer, which will transfer the heat to the material. At the same time, the moisture in the material is vaporized, the water vapor formed, and takes out the dryer with the air. After heating and drying, the material can remove the combined moisture in the material, reaching the water content required in the light chemical industry and food production process.