It can be divided into atmospheric, pressurized, and vacuum evaporation operations. Obviously, for heat sensitive materials such as antibiotic solutions, fruit juices, etc., they should be processed under reduced pressure. High viscosity materials should be evaporated using a pressurized high-temperature heat source for heating (such as heat transfer oil, molten salt, etc.)

It can be divided into single effect and multi effect evaporation. If the secondary steam generated by evaporation is directly condensed and no longer used, it is called single effect evaporation. If the secondary steam is used as the next heating steam and multiple evaporators are connected in series, this evaporation process is called multi effect evaporation.

Direct heat source heating refers to the evaporation process of mixing fuel with air, causing the high-temperature flame and smoke generated by its combustion to be directly sprayed into the evaporated solution through a nozzle to heat the solution and vaporize the solvent.

Evaporators are divided into three types according to operating pressure: normal pressure, pressurized, and depressurized. According to the movement of the solution in the evaporator, it can be divided into: ① circulating type. Boiling solution passes through the heating surface multiple times in the heating chamber, such as central circulation tube type, hanging basket type, external heating type, Levin type, and forced circulation type One way type. The boiling solution passes through the heated surface in the heating chamber at once without circulating flow, and the concentrated solution is discharged, such as rising film, falling film, stirring film, and centrifugal film Direct contact type. The heating medium directly contacts the solution for heat transfer, such as an immersed combustion evaporator. During the operation of the evaporation device, a large amount of heating steam needs to be consumed. To save heating steam, a multi effect evaporation device and a steam recompression evaporator can be used. Evaporators are widely used in departments such as chemical and light industries.