In the forced circulation evaporation process, how is the circulation flow rate of the circulation pump determined?
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What is its relationship with evaporation rate? . ? What impact does the selected circulation flow rate have on the heater?
It seems that the flow rate is determined based on the superheat at the heater outlet, in order to prevent the heated mother liquor from vaporizing inside the pipes
What should the excess temperature at the heater outlet be? Is around 1~2 degrees okay?
This one has an experienced calculation formula
Could you give a general idea of the empirical calculation formula? Thank you! !
This is not an empirical formula; there are rigorous theoretical calculations. The circulation flow rate and heat exchange area are in an inverse parabolic relationship. By identifying the inflection point, the economically optimal point is determined, which simultaneously meets the process requirements. Will I talk nonsense?
Could you tell me which standard mentions it? Thank you!
The flow rate of the liquid in the evaporator is 2 to 3 m/s
There are certain differences in the flow rates of different materials, and the differences between various circulation processes are even greater. The flow rate for forced circulation is generally 1.5–2 m/s; in the case of rising film circulation, the flow rate is not taken into account, only the circulation volume. Design considerations can be drawn from those of thermal siphon reboilers. Rising film and falling film circulation both involve calculating the circulation volume based on parameters such as the fluid’s density, viscosity, surface tension, and the structure of the heat exchanger; sometimes approximate empirical values are also used.