The current application of evaporators is very extensive, involving industries such as chemical, light industry, pharmaceutical, and food. Among them, evaporators are indispensable equipment for evaporation concentration and crystallization in the chemical industry. With the development of chemical industry technology, in order to meet the needs of different wastewater, industries, and materials, there are also more and more types of evaporators, and their working principles and operating methods are slightly different.

1、 Classify solutions based on their retention in the evaporator
1. Circulating evaporator
This type of evaporator allows the solution to circulate in the evaporator. The reasons and operations that cause loops are different, and can be divided into two categories: natural loops and forced loops. Natural circulation evaporators are divided into central circulation tube evaporators, suspended basket evaporators, Levin evaporators, and forced circulation evaporators.
2. One-way evaporator
The main feature of this type of evaporator is that the solution only passes through the heating chamber once in the evaporator, and the concentrated liquid is discharged without circulating flow. When the solution passes through the heating chamber, it flows in a film like manner on the tube wall, thus becoming a liquid film evaporator. According to different material flow directions, single pass evaporators are divided into rising film evaporators, falling film evaporators, and scraper evaporators.

2、 Classified by evaporation method
1. Natural evaporation: refers to the evaporation of a solution at a temperature below its boiling point, such as seawater drying salt. In this case, the solvent only vaporizes on the surface of the solution, resulting in a low rate of solvent vaporization.
2. Boiling evaporation: Heat the solution to boiling point and evaporate it in a boiling state. The evaporation operation in industry is basically of this type.

3、 Classified by evaporator operating pressure
Evaporators can be classified into atmospheric pressure, pressurized, and depressurized (vacuum) evaporation operations based on operating pressure.
Generally, 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 (such as heat transfer oil, molten salt, etc.).

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

5、 Classified by evaporation process mode
According to the process mode of evaporation, it can be divided into intermittent evaporation and continuous evaporation. Intermittent evaporation refers to the evaporation operation of feeding or discharging materials in batches. The characteristic of intermittent operation is that the concentration and boiling point of the solution in the evaporator change over time throughout the entire process, making intermittent evaporation a non steady state operation. Intermittent evaporation is usually suitable for small-scale and multi variety applications, while continuous evaporation is suitable for large-scale production processes.

Different types of evaporators are used in different environments and have their own advantages. There are many types of evaporators, and when choosing to use an evaporator, we need to consider the material situation on site, as well as the structure, operation, and maintenance of the evaporator to provide customers with a suitable evaporator.