Severe fluctuations in the distillation tower
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The top pressure in the diesel upgrading distillation column is controlled at 0.150 MPa (with two-way control). Over the past two days, every other hour or so, the top pressure suddenly dropped to 0.143–0.145 MPa; subsequently, the top temperature dropped by about 10°C, while the bottom temperature decreased by 3–10°C. This was accompanied by a rapid drop in liquid level of 10%–30%, after which things gradually returned to normal. This phenomenon has occurred periodically, and now the situation is stable. Could anyone explain what’s causing this? Measures taken: increasing the bottom temperature； Reduce tower top reflux ； Reflux tank level ； Lowering the feed temperature and so on has had no effect; I would appreciate some advice from those with more experience. . .
Could it be that fluctuations in the steam supply at the bottom of the tower are causing a cycle of water vapor within the tower?
Do you mean fluctuations in the steam supply to the stripping tower? If so, that would refer to water in the feed to the distillation tower, but the feed to the distillation tower does not contain water. . .
It’s probably because water was carried from the stripping tower into the distillation tower; a too-low vapor temperature in the stripping tower can lead to the presence of water. What is your vapor temperature?
Around 280 degrees, with fluctuations of just those two or three days; it got better later. I’ll check the trend again when I go to work at night. . . It doesn’t seem to contain water. . .
Where are you from for hydrocracking? What are the system pressure and reaction temperature controls for you?
Around 80 Mpa; the inlet temperature of the refining reactor is 280 degrees, and the outlet temperature is 350 degrees. The inlet temperature of the reforming reactor is 300 degrees, with an outlet temperature of 350 degrees as well. . .