Vacuum pumping
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In a vacuum distillation tower, should the vacuum pump be used to create a vacuum before feeding the material, or after feeding it? Why?
After the feed to the vacuum tower is heated in the vacuum furnace
Is there any difference in evacuating before feeding the material?
I’ve never done decompression, but that’s what I think. The material for vacuum distillation is constant residue, which also requires heating for distillation. So, when vacuuming is performed before raising the feed temperature, not much can be removed, which can lead to too high a negative pressure in the vacuum tower. At the same time, raising the feed temperature at this stage can cause large fluctuations in the load on the vacuum pump, as well as wasting energy from the vacuum pump. When vacuuming is done after raising the feed temperature, the vacuum pump can quickly reach its designed operating conditions and function stably.
Of course, vacuum pumping starts after heating with the material added
Vacuum is applied before feeding; in the absence of a gas phase, this can cause the tower to collapse