Why can’t the vapor at the top of the distillation tower be discharged?
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Why can’t the vapor at the top of the distillation tower be discharged? I would appreciate some guidance from everyone. The tower bottom volume is 4 cubic meters, with a loading capacity of 3.5 cubic meters; vacuum distillation is used. Initially, distillation at the tower top proceeded normally, but when only 1/4 of the liquid remained in the tower bottom, no more distillate could be obtained. The temperature at the tower top decreased, yet all operating conditions remained normal (temperature and vacuum levels were within normal ranges). Suspecting a blockage in the pipeline, I removed it only to find no blockage. Then we added another 3 cubic meters of material and continued with the distillation; this time, all 3 cubic meters plus whatever was left from the previous batch was distilled out. What caused only 1/4 of the material to be obtained as output?
If vacuum cannot be achieved, the vacuum level must be abnormal. There’s a contradiction here: the tower top temperature is decreasing, yet all operating conditions are normal (temperature and vacuum levels are normal). So, is the temperature actually normal or not?
The vacuum level has always been normal, and the temperature at the bottom of the tower is generally between 170 and 185 degrees. When only 1/4 of the liquid remains in the tank, no more product is discharged. This situation has occurred three times; after restarting the distillation process, it suddenly worked fine again, though we’re not sure why. So I can’t find the reason
The reboiler temperature is normal, while the top temperature has decreased, which indicates that there is no more evaporation taking place. Could it be that the remaining 1/4 consists of high-boiling-point components, and the reboiler temperature is not high enough to vaporize them? Is your vacuum level constant throughout the process, or what? Generally, changes in the amount of evaporation affect the vacuum level, unless the volume of vacuum pumping is much greater than the amount of evaporation
Also, what is the height of the tower? Is that intermittent distillation?
Thank you, it remains unchanged throughout the whole process; we’ve taken care of it now
Friends, thank you. It has been processed now
What is the heating method for the tower bottom, and where are the temperature measurement points located? Perhaps the temperature measurement point is located at a higher elevation; the temperature reading is accurate when the liquid level is high. When the level is low, the measurement point cannot detect the medium at that lower level, so the displayed temperature corresponds to the area above the liquid level, and the actual temperature of the liquid is not as high as that
Analyze the reasons for it; only then will posting this thread be meaningful