Distillation simulation
Thread Content
When doing distillation simulation, what are the methods to reduce the tower top temperature without changing the tower pressure?
Haha, try to find ways to improve the purity of the top product, such as increasing the number of trays and increasing the reflux ratio.
What you said above makes sense, but it also depends on the specific material system you want to separate. If the top of the tower has already reached azeotrope, then you cannot rely on this method to reduce the temperature at the top of the tower. LZ, please tell me what is the system of matter that needs to be separated? Why lower the tower top temperature? And why can't the tower pressure be changed? It will be clearer if we talk about it more specifically.
When methanol is rectified, there is too much ethanol in the top product. Now the number of plates and the reflux ratio are relatively large. The tower pressure is given and generally cannot be changed.
Set up a mid-section reflux at the top of the tower. If it already exists, increase the mid-section reflux to remove heat.
A side line is added to the middle and lower part of the distillation tower to extract ethanol from the side line. Simply lowering the temperature is meaningless, as ethanol still cannot be distinguished. However, reducing pressure should be beneficial to separation (if the reflux ratio remains unchanged).
There is nothing you can do except increase the reflux and increase the number of trays. When other conditions remain unchanged, lowering the temperature will lower the pressure. Although PV=nRT does not apply in mixtures, you will know if you think about it: As the temperature decreases, the saturated vapor pressure of the system decreases.