The evaporator is a very important part of the four major components of refrigeration. The low-temperature condensed "liquid" passes through the evaporator to exchange heat with the outside air, and "gas" absorbs heat to achieve the effect of refrigeration.
Evaporators are divided into two categories: circulation type and film type.
It is mainly composed of heating chamber and evaporation chamber. The heating chamber provides the liquid with the heat required for evaporation, which promotes the boiling and vaporization of the liquid; the evaporation chamber completely separates the gas-liquid two phases. The vapor generated in the heating chamber has a large amount of liquid foam. After reaching the evaporation chamber with a larger space, these liquids are separated from the vapor by self-condensation or the action of a demister. Usually the demister is located at the top of the evaporation chamber.
The evaporator is divided into three types according to the operating pressure: normal pressure, pressurized and decompressed. According to the movement of the solution in the evaporator, it is divided into:
①Circular type. The boiling solution passes through the heating surface for many times in the heating chamber, such as central circulation tube type, hanging basket type, external heating type, Levin type and forced circulation type.
②One-way type. The boiling solution passes through the heating surface once in the heating chamber without circulating flow, that is, the concentrated liquid is discharged, such as rising film type, falling film type, stirring film type and centrifugal film type.
③Direct contact type. The heating medium is in direct contact with the solution to transfer heat, such as a submerged combustion evaporator. During the operation of the evaporation device, a large amount of heating steam is consumed. In order to save the heating steam, a multi-effect evaporation device and a vapor recompression evaporator can be used. Evaporators are widely used in chemical, light industry and other sectors.