1. According to evaporation method:
Natural evaporation: that is, the solution evaporates at a temperature lower than the boiling point, such as seawater drying salt. In this case, because the solvent only evaporates on the surface of the solution, the solvent evaporation rate is low.
Boiling evaporation: The solution is heated to the boiling point and evaporated in a boiling state. Industrial evaporation operations are basically of this type.
2. According to heating method:
Direct heat source heating is an evaporation process in which the fuel is mixed with air, and the high-temperature flame and flue gas generated by the combustion are directly sprayed into the evaporated solution through the nozzle to heat the solution and vaporize the solvent.
The indirect heat source heats the walls of the container to transfer the evaporated solution. That is, the heat transfer process carried out in the dividing wall heat exchanger.
3. According to operating pressure:
It can be divided into atmospheric, pressurized and reduced pressure (vacuum) evaporation operations. Obviously, for heat-sensitive materials, such as antibiotic solutions, fruit juices, etc., it should be carried out under reduced pressure. High-viscosity materials should be heated by a pressurized high-temperature heat source (such as heat transfer oil, molten salt, etc.) for evaporation
4. According to the number of points:
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-effect heating steam, and multiple evaporators are connected in series, this evaporation process is called multi-effect evaporation.