Answers to questions on operations in distillation columns
Thread Content
In the operation of a distillation tower, why is the pressure in the reflux drum higher than the pressure at the top of the distillation tower? Seeking theoretical and practical explanations»
As long as the tower is operating properly, the tower pressure will definitely be higher than the pressure in the reflux tank; otherwise, the gas phase coming out of the top of the tower cannot enter the condenser
However, during operation, the pressure in the reflux tank is higher than that at the top of the tower. Why is this?
I really have never seen such a situation as you described; gas must flow from the high-pressure side to the low-pressure side, after all, pressure energy is what drives the flow of the medium.
Just now, I forgot to mention something. Is your gauge accurate? I’m very skeptical.
The pressure at the top of the tower must be higher than the pressure inside the reflux tank. I’ve really never seen such a situation before; it’s likely there’s a problem with the instruments! Check it once! !
The instruments are accurate; every distillation column shows the same pattern – the reflux drum is about ten to fifteen kPa higher than the top of the column.
Hey, it’s not a gauge issue. Once the gas at the top of the tower enters the heat exchanger, the pressure in the reflux tank becomes higher than that at the top of the tower. If there was a problem with the gauge, I wouldn’t have asked. The thing is, I’ve seen that all the distillation towers here work this way, except for those where there’s a compressor at the outlet of the tower top.
The pressure inside or at the top of the tower is definitely higher than that in the reflux tank; otherwise, the tower cannot function properly. Perhaps there is a problem with the installation location of the pressure gauge at the top of your tower; it is too close to the condenser. The moment the air flow enters the condenser, its volume decreases suddenly and the pressure drops, but this is a dynamic process. Your phenomenon is truly unexplainable.
That’s not true at all; it’s the pressure gauge on top of the reflux tank that shows the value, and it’s a remote reading – there’s an extra pressure of about ten to fifteen kilopascals. Every distillation tower is the same.
Is the pressure at the top of the tower related to the pressure in the tank? After the vapor at the top of the tower is condensed, it falls to the reflux tank due to gravity! As long as this gravity is greater than the pressure in the return tank, that’s sufficient!