According to the evaporation method:
Natural evaporation: The solution evaporates at a temperature below its boiling point, such as seawater salt production. In this case, the solvent only vaporizes on the solution surface, resulting in a low vaporization rate.
Boiling evaporation: The solution is heated to its boiling point, causing it to evaporate while boiling. Industrial evaporation operations are primarily of this type.
According to the heating method:
Direct heat source heating: This involves mixing fuel with air, burning it to produce a high-temperature flame and flue gas, which is then directly injected into the solution to be evaporated through a nozzle to heat the solution and vaporize the solvent.
Indirect heat source heating: Heat is transferred to the solution being evaporated through the container wall. This is the heat transfer process that takes place in a partitioned heat exchanger.
According to operating pressure: Evaporation can be divided into atmospheric pressure, pressurized, and depressurized (vacuum) evaporation operations. Obviously, for heat-sensitive materials, such as antibiotic solutions and fruit juices, depressurization should be used. High-viscosity materials should be evaporated using pressurized high-temperature heat sources (such as heat transfer oil and molten salt).
According to the number of effects: Evaporation can be divided into single-effect and multi-effect evaporation. If the secondary steam produced by evaporation is directly condensed and not reused, it is called single-effect evaporation. If the secondary steam is used as the heating steam for the next effect, and multiple evaporators are connected in series, this evaporation process is called multi-effect evaporation.
