1. By evaporation method:
Natural Evaporation: Refers to the evaporation of a solution below its boiling point, such as the process of salt production from seawater. In this case, since the solvent only vaporizes at the surface of the solution, the rate of solvent vaporization is low.
Boiling Evaporation: Heat the solution to its boiling point, causing it to evaporate while in a boiling state. Evaporation operations in industry are generally of this nature.
2. By heating method:
Direct heat source heating involves mixing fuel with air to create a high-temperature flame and flue gas, which are then directly injected through a nozzle into the solution being evaporated to heat the solution and vaporize the solvent.
Indirect heat source heating transfers heat to the solution being evaporated through the container walls. That is to say,Shell and Tube Heat ExchangerHeat transfer process in progress.
3. By operating pressure:
It can be divided into atmospheric, pressurized, and vacuum (depressurized) evaporation operations. Clearly, for heat-sensitive materials such as antibiotic solutions and juices, evaporation should be conducted under vacuum. For high-viscosity materials, it is advisable to use pressurized high-temperature heat sources for evaporation (such as thermal oil, molten salt, etc.).
4. By effectiveness grade:
The process can be divided into single-effect and multi-effect evaporation. If the secondary steam produced by the evaporation is directly condensed without reuse, 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, the evaporation process is referred to as multi-effect evaporation.
