I have a question regarding the pressure at the top and bottom of an atmospheric pressure tower
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The pressure at the top of the atmospheric tower and the feed section in our unit are almost the same. Is it normal? Where is the pressure at the bottom of the tower? Is it on the residue extraction line?
Not much of a difference; on the wall of the residue extraction column
The pressure at the top of a vacuum distillation column is not very different from the pressure on the wall of the column where the residue is extracted. In contrast, the pressure at the top of an atmospheric distillation column differs significantly from the pressure on the wall of its vaporization section. Under normal operating conditions, the pressure throughout an atmospheric distillation column decreases as one moves upward; in other words, the vapor pressure in such a column decreases as it rises, resulting in a pyramid-shaped distribution of pressures. The internal return flow in the liquid phase decreases as one moves downward along the tower height, forming an inverted pyramid shape. If the pressure at the top of the atmospheric tower and that in the feed section are similar, then your operation will be unstable, with large fluctuations in the various stages, and the reflux levels in each section won’t be properly adjusted
It has been explained in great detail upstairs: there is still a significant pressure difference between the top of the tower and the feed section. Of course, the unit of pressure is very important; if it’s expressed in MPA, you can imagine just how large this difference is. If the pressures are the same, then there might be a problem with the trays
The explanation on the 3rd floor is quite accurate; the pressure in the feed section of a atmospheric pressure tower is slightly higher than the pressure at the top of the tower. In my plant, the pressure in the feed section is 1.1 bar, while it is 0.8 bar at the top of the tower. The bottom pressure gauge is generally installed on the extraction line at the bottom of the tower.
My unit maintains a pressure of 0.8 kilograms at the top of the tower, while the pressure in the feed section is 0.83 kilograms. It’s only 0.03 kilograms short – is that normal? How to carry out maintenance?
This shouldn’t be a maintenance issue; rather, it should be an operational one. The low internal reflux leads to an imbalance between the gas and liquid phases.