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How To Choose Multi-effect Evaporator?

Jan 16, 2018

How to choose multi-effect evaporator?


Select multi-effect evaporator mainly from the efficiency, lack of steam condenser selection, process to choose. Finally determine the heating area of the evaporator to decide.


Select multi-effect evaporator need to pay attention to three points:


1, efficiency:


The main consideration is the size of the amount of processing, the boiling point of the material being boiled rise, the number of equipment.


2, lack of steam condenser choice:


When the steam must be recovered, it is best to use indirect condensers, such as tube type and spiral plate type heat exchangers. When there is no need to recover the spent steam, it is better to use direct condensers, such as direct air condensers, water jet pumps to condense Wait.


3, process:


When operated downstream, the pressure in the after-effect evaporation chamber is lower than the previous efficiency and the pump power required to deliver the solution in between is small.


In addition, because the after-effect evaporation temperature is low, so the pre-effective solution into the after-effect, it will flash out part of the steam, so the raw steam consumption is relatively small. However, downstream processes, the concentration of high after-effects, low temperature, high viscosity, heat transfer rate. Reverse operation and the downstream operation is the opposite, the former effective temperature, high concentration, low afterglow temperature, low concentration, so that the heat transfer rate close to each effect, but the required efficiency of pump power over large, steam consumption and more . Not suitable for handling heat sensitive materials, nor is it suitable for materials with increased corrosiveness as the temperature and concentration increase. In addition, according to the specific circumstances of materials using advection, mixed flow.


4, heating area:


Determine the evaporator heating area through the material balance, heat balance, heat transfer calculation and the use of the form of the process and other factors considered after the decision.


Multi-effect evaporator to use points, can be divided into common multi-effect evaporation system, forced circulation multi-effect evaporator, forced circulation evaporator is the use of more than one external circulation evaporator and then add an external circulation pump. Forced circulation evaporator can be applied to crystallization in the evaporation process, and is non-heat-sensitive materials.