Why is the pressure at the top of the distillation tower higher than the pressure at the bottom of the tower?
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In a newly installed distillation column, under normal conditions the pressure at the top of the column should be lower than that at the bottom. However, the situation is a bit chaotic right now – the pressure at the top is actually higher than that at the bottom. It should be noted first that there is nothing wrong with the pressure gauge, as occasionally the pressure at the top of the tower can be lower than the pressure at the bottom of the tower. I would like to ask the experts here: how can this be explained? What is the cause of it?
There are probably too many light-component substances; you can change the feed inlet
When a distillation column is first started up, there are likely to be many difficult-to-condense gases inside the column; appropriate methods can be used to remove these gases from the top of the column
How is the condensation of the light components at the top of the tower? There could be air resistance at the top of the tower, as well as insufficient exhaust or condensation.
Pay attention to the relative positions of the two differential pressure transmitters and the pressure guiding tubes; generally, it is the difference in height (liquid column) between the sampling port and the transmitters that has an impact. Consider whether the relative positions are the same, whether there are differences in density, whether one of them is filled with liquid while the other contains non-condensable gases, and also the measurement accuracy of the instruments. This kind of situation is common in actual production; whether it is a positive pressure difference or a negative pressure difference, as long as it remains stable, there’s no need to worry about it.
Too much non-condensable gas accumulates at the top of the tower and isn’t discharged; coupled with a low load at the bottom of the tower and feed components that are too light, the pressures at the top and bottom of the tower reverse.
The opening of the top extraction valve is too small or it is malfunctioning; the amount of water used for cooling the top condenser is insufficient or the temperature is too high; there is a high level of non-condensable gases in the condenser that are not being removed in time; and the pressure gauge is malfunctioning due to the accumulation of fluid.
This post was last edited by a2963008000 on 2011-12-2 at 13:53. This is not normal; a fault needs to be ruled out. According to the principle, in a distillation column, whether it is a tray column or a packed column, due to the resistance posed by the reflux stream, the pressure at the bottom of the column should normally be higher than that at the top. Even if the non-condensate effect at the tower top is poor and the outlet valve at the tower top is small, the pressure at the bottom of the tower should still be high. The pressure buildup at the top of the tower occurs only for a short period while the system is in operation; over time, it returns to normal. In this way, the rate at which the temperature of the distillation tower increases slows down, and this problem will not occur.