Liquid hammer problem in feed pipelines
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Recently, liquid slugging occurred in our feed line from the benzene column to the toluene column. Possible reasons: the stop valve is installed at the bottom of the benzene column, not near the feed inlet, which results in a large pressure difference. After moving the feed inlet downward, the liquid slugging phenomenon persisted but was significantly reduced. However, according to my analysis, at our operating pressures (feed pressure of 6.2 Bar gauge pressure, with column pressure also around 6 Bar), the bubble point of the feed should be around 200 degrees; yet the temperature measured at the feed inlet was 130 degrees, which is far below 200 degrees, so flash evaporation should not occur. Moreover, if flash evaporation were indeed the cause, then after moving the feed inlet downward, the pressure difference across the feed plate would remain roughly the same (with a total column pressure drop of 0.2 Bar), but the temperature would increase, making flash evaporation more likely. Yet in reality, the liquid slugging problem was reduced. I’m confused – is it really liquid hammer caused by flashing? If not, what other reasons could there be? Everyone, please help me analyze it~
Check whether the selected transport pump is appropriate; is the head sufficient?
Reply to 2# cyl5410: I went up there yesterday to check the pressure at the feed inlet; it was 6.2 bar. The pressure at the bottom of the tower is 6.2 bar, so it should be sufficient, right?
Let’s discuss this together; no one is answering
There must be some part of the pipeline where gas entrapment is occurring
It’s best to start by controlling the pump flow rate when feeding material, rather than setting it at a high level right away; you can increase it later
I think it is still caused by material flashing: 1. The feed manual valve is located at the bottom of the benzene tower; due to an expansion section in the pipeline before feeding, material flashing and vaporization occur. 2. By moving the feed location lower, the higher pressure at the bottom helps to suppress vaporization, thus improving the situation. Solutions: 1. Adjust the process parameters, such as the temperature at the bottom of the benzene tower or the pressure above it. 2. If possible, install flow control orifice plates near the feed location to limit vaporization
1. Check whether there is a large liquid seal in the feed pipeline; if so, verify whether it is reasonable； 2. Check whether the insulation of the pipelines is intact, especially in areas near the tower ； 3. Check whether there are reducers or devices such as flow-limiting orifice plates in the feed pipeline; if so, verify whether their placement is appropriate ； 4. Check whether the pipes are blocked; it’s best to have the opportunity to disassemble them and clean them under pressure ； That’s about all I can think of; more details will be added below. . . . .