How to choose a multi-effect evaporator

How to choose a multi-effect evaporator

The selection of a multi-effect evaporator is mainly selected from the number of effects, the selection of the exhaust steam condenser, and the process. Finally, determine the heating area of ​​the evaporator.

　　 There are three points to note when choosing a multi-effect evaporator:

　　1, effect number:

　　 mainly consider the size of the processing capacity, the boiling point increase value of the evaporated material, and the number of equipment.

　　2. The choice of exhaust steam condenser:

When exhaust steam must be recovered, it is best to use indirect condensers, such as tube and spiral heat exchangers; when exhaust steam does not need to be recovered, it is best to use direct condensers, such as direct atmospheric condensers, water jet pump condensation Wait.

　　3. Process:

　　 When operating downstream, the pressure of the after-effect evaporation chamber is lower than that of the previous one, and the pump power required for the delivery of the solution between the effects is small.

　　 In addition, because the after-effect evaporation temperature is low, after the front-effect solution enters the after-effect, part of the steam will flash out, so the raw steam consumption is relatively small. However, in the downstream process, the after-effect concentration is high, the temperature is low, the viscosity is increased, and the heat transfer rate is small. The reverse operation is the opposite of the downstream operation. The front effect temperature is high, the concentration is high, the after effect temperature is low, and the concentration is low, so that the heat transfer rate of each effect is close, but the required efficiency of the feed pump is large and the steam consumption is large. . It is not suitable for processing heat-sensitive materials, nor is it suitable for materials with increased medium corrosivity as the temperature and concentration increase. In addition, it can adopt advection and mixed flow processes according to the specific conditions of the materials.

　　4. Heating area:

　　The heating area of the evaporator is determined by comprehensive consideration of factors such as material balance, heat balance, heat transfer calculation, and the adopted process form.

　　Multi-effect evaporator can be divided into general multi-effect evaporation system and forced circulation multi-effect evaporator. The forced circulation evaporator uses multiple external circulation evaporators and adds an external circulation pump. The forced circulation evaporator can be applied to the occasions where there is crystallization during the evaporation process and it is a non-heat sensitive material.