1. According to the evaporation method:
Natural evaporation: that is, the solution evaporates at a temperature lower than the boiling point, such as sea salt, in which case the solvent vaporization rate is low because the solvent is only vaporized on the surface of the solution.
Boiling evaporation: The solution is heated to boiling point and allowed to evaporate under boiling conditions. Industrial evaporation operations are basically such.
2. According to the heating method:
Direct heat source heating is an evaporation process in which a fuel is mixed with air to generate a high-temperature flame and flue gas which is directly injected into the evaporated solution through a nozzle to heat the solution and vaporize the solvent.
Indirect heat source heating The walls of the vessel are passed to the evaporated solution. That is, the heat transfer process performed in the partition wall heat exchanger.
3. According to the operating pressure points:
It can be divided into atmospheric pressure, pressurization and decompression (vacuum) evaporation operations. Obviously, heat sensitive materials such as antibiotic solutions, juices, etc. should be carried out under reduced pressure. High-viscosity materials should be heated by pressurized high-temperature heat source (such as heat transfer oil, molten salt, etc.).
4. By number of effects:
Can be divided into single effect and multi-effect evaporation. If the secondary vapor generated by evaporation is not directly utilized, it is called single-effect evaporation. If the secondary steam is used as the next heating steam and a plurality of evaporators are connected in series, the evaporation process is multi-effect evaporation.