Temperature issues at the top and bottom of the packed tower
Thread Content
Dear teachers: Our company uses packed towers for multiple distillation separation processes, and these towers operate under negative pressure. I would like to ask you all: since the temperature at the top of the tower corresponds to the boiling point of the substances at that vacuum level, how should the temperature at the bottom of the tower be set? Thank you!
The vapor phase temperature at the top of the tower is the dew point temperature of the lighter component at that pressure, while the liquid phase temperature at the top of the tower is the bubble point temperature of the lighter component at that pressure. The same bottom liquid phase temperature is the bubble point temperature of the heavy components at the bottom pressure. With multiple components like this, there is no issue with boiling point. The top temperature of the tower is easy to determine; however, to determine the temperature at the bottom of the tower, it is necessary to know the concentration of the heavy components and the pressure at that level.
This problem is really difficult; I am indeed dealing with similar issues. Do you mean setting the maximum temperature to the low boiling point, so that you can achieve a clean separation?
The temperature setting is part of the calculation; whether a clear separation can be achieved depends on factors such as the relative volatility at constant pressure. The number of theoretical plates is calculated based on the separation requirements, after which it is decided whether to use packing or something else