1. According to the EVAPORATOR method: natural evaporation: that is, the solution temperature is lower than the boiling point of steam, such as seawater salt, in this case, since the solvent only evaporates on the surface of the solution, the solvent evaporation rate is low. Boiling Evaporation: Heat a solution to its boiling point to evaporate it. Industrial evaporation operations are basically of this type.
2. According to the heating method: direct heat source heating is the process of mixing fuel and air, so that the high-temperature flame and smoke generated by combustion are directly injected into the evaporation solution through the nozzle to heat the solution, so that the solvent evaporates. An indirect heat source heats the walls of the vessel until the solution evaporates. That is, the heat transfer process in the interlayer heat exchanger.
3. According to the operating pressure: it can be divided into atmospheric pressure, atmospheric pressure and vacuum (vacuum) evaporation operation. Obviously, for heat-sensitive materials, such as antibiotic solutions, fruit juices, etc., it should be done under reduced pressure. High-viscosity materials should be heated and evaporated under pressure with a high-temperature heat source (such as heat transfer oil, molten salt, etc.).
4. According to the number of effects: it can be divided into single-effect evaporation and multi-effect evaporation. If the secondary vapor produced by evaporation is no longer used for direct condensation, it is called single-effect evaporation. If secondary steam is used as low-efficiency heating steam, and multiple evaporators are connected in series, the evaporation process is multi-effect evaporation.
5. According to the condition of the solution staying in the EVAPORATOR, the commonly used zonal heat transfer falling film evaporators can be roughly divided into two categories: circulation type and one-way type.
Circulating evaporator In this EVAPORATOR the solution is circulated through the evaporator. Due to the different reasons of circulation, it can be divided into natural circulation and forced circulation.