Discussion on the equal area of the heating chambers in evaporator design
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On the side of the evaporator manufacturers, considerations such as ease of production and installation, along with other factors, lead to the use of a uniform size for the heating chamber. As a result, if there are slight errors in calculations, the evaporation rate can vary significantly. I’m not sure if this is correct, but it certainly makes debugging more difficult. When trying to increase the steam output, the pressure in the preceding stage rises, leading to the generation of secondary steam that cannot be processed by the subsequent stage, which in turn results in positive pressure conditions during operation. I would appreciate your opinions – wouldn’t it be possible to make the subsequent stage larger? Is it a non-scoring temperature difference?
Multi-effect evaporators are designed based on certain conditions; if these conditions are not met during actual operation, the equilibrium is disrupted and a new equilibrium needs to be established. If the capacity of one of the evaporators is insufficient, it may affect the operation of the entire evaporation process. The poster can consider either adjusting the operating parameters or modifying the equipment based on actual operation conditions.
In triple-effect evaporation, the last effect generally has a larger heat exchange area, which facilitates the use of secondary steam. The first two effects can have the same heat exchange area.
The design of evaporation relies mainly on experience; factors such as the selection of temperature difference gradients, the choice of heat transfer coefficients, and the effects of static pressure, liquid column height, and concentration on boiling point all influence the success or failure of the design. During operation, it is important to maintain stable control of parameters such as the liquid level and pressure in each stage; typically, the heating area for each stage is designed to be the same. There are also designs where the area gradually increases towards the back.
What was said upstairs is correct; there are many factors involved in evaporation, so it’s impossible to determine the temperature with such precision. Even by referring to relevant manuals regarding the properties of the material, there will still be some differences compared to the actual conditions in the customer’s facility. Therefore, I believe that increasing the evaporation area of the last stage will definitely help improve the amount of evaporation and the efficiency of the operation
When I do it, I usually set the area at the front to be similar, with the last stage being a bit larger