Storage tank reflux and pressure issues
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This post was last edited by TDI5 on 2010-10-26 at 12:57. The aniline storage tank is equipped with low-pressure nitrogen at the top to provide a protective seal, keeping the tank under a slight positive pressure. There is a circulation pump at the bottom of the tank to enable self-circulation within it. The tank is insulated with a low-pressure steam jacket, and the pressure at the top of the tank is maintained through the combined effect of the evaporation of the material inside the tank and protective nitrogen gas. Once, when the circulation pump at the bottom of the tank was stopped, it was observed that the pressure at the top of the tank dropped suddenly. What could be the reason for this? Is there any relationship between the pump’s self-circulation and the pressure at the top of the tank? It is a benzidine; it has a relatively high freezing point, so a jacket is needed for heat retention. As a supplementary note, after the pump stopped, there was no significant change in the temperature reading of the storage tank. But the pressure has clearly decreased.
Let me try to answer this. The circulation pump does work on the fluid inside the tank, helping to maintain a certain temperature for that fluid. When the circulation pump stops, the temperature of the fluid in the tank drops, and there is a certain relationship between the pressure of the material and its temperature; a decrease in temperature leads to a decrease in pressure, which is what causes the phenomenon you mentioned.
Does the bottom circulation pump act as an agitator? When the pump stops, no hot fluid is circulated to the top of the tower, causing the temperature to drop suddenly; as a result, aniline vapor condenses and the pressure plummets. I don’t understand why heating and maintaining a constant temperature is necessary; is the freezing point of aniline very high?