The pressure at the top of the distillation tower cannot be stabilized

The conditions provided are still limited, and the description isn’t very clear. I think you have overlooked the impact of feed rate, temperature, and composition on the equilibrium of the tower! ! ! I’m not sure if your tower is a production tower; generally, a temporary interruption in reflux doesn’t require shutting off the feed completely, right? ! If nothing else works, production can be stopped first; the tower should still have some capacity left! In this way, you’ll be able to adjust more steadily! ! ! :loveliness:

Please explain in detail whether the reflux of your distillation column is of the self-reflux type If that’s the case, it might be because improper pressure release at the top of the tower by the workers created a sudden vacuum, resulting in no pressure difference and thus no backflow. In that case, based on your operations, vaporization will occur, causing the liquid level in the top condenser to rise. At this point, the reflux will increase, leading to excessive cooling; the pressure at the top of the tower will drop as more condensation takes place. You can then check whether the pressure difference between the middle and lower sections of the tower is increasing. Your approach is basically correct, but be sure to take into account the properties of the materials in your tower; if it’s a high-boiling component, it’s better to choose to reduce the reflux.

In my opinion, you shouldn’t use full reflux from the start. When the pressure at the top of the tower drops unpredictably, it’s necessary to reduce the reflux rate; only in this way can the tower pressure rise more quickly. If you use full reflux, the pressure at the top of the tower will certainly drop faster. The greater the amount of steam at the bottom of the tower, the more chaotic the conditions inside the tower become, and over time this will definitely lead to liquid flooding in the tower. It is recommended that when making adjustments, you first reduce the reflux rate, stop product extraction, and increase the steam supply at the bottom of the tower accordingly. This post was last edited by bingyu252 on 2008-1-11 09:49

I believe that the interruption in feed disrupts the material balance inside the tower; even with full reflux, the pressure first rises and then falls. I have encountered similar incidents where the return pump stopped working, resulting in a disruption in the return flow. As long as the return extraction is turned off and full return flow is allowed for a while, balance is restored.

Thank you all for your advice. I forgot to mention that my tower is of the self-reflux type – it’s a product tower from which the product is taken from the top, and the reflux rate can only be adjusted by controlling the discharge rate. If I stop taking product out, then it’s no longer possible to adjust the reflux rate, unless I use the amount of condensation or steam. I think what the expert on floor 3 said is correct: \"The negative pressure created results in no pressure difference at that moment, hence no reflux.\" But please, experts, could you explain this statement? After there was no backflow for a moment, the backflow volume increased significantly. Why does the tower pressure decrease slowly as the full backflow time progresses? At that time, I wanted to restore the tower pressure. In my understanding, the pressure in the tower drops instantly, which leads to an increase in the amount of vaporization (many heavy components vaporize due to the drop in pressure). However, the cooling capacity remains unchanged; it seems that this cooling capacity is only sufficient to cool the large amount of vapor that is generated at that moment, without achieving a condensation effect. Once a new equilibrium is established, the high level of vaporization results in high levels of condensation, and consequently, a large amount of fluid flows back. Is that so? I would like to ask the experts again: if there is no reflux at that moment, is it necessary to shut down the feed and discharge systems in order to carry out a full reflux operation?

Also, the feed to the interrupt tower affects the balance of the tower. I think this statement is correct as well, but I’m not sure how to explain it theoretically. By stopping the feed, it’s as if a certain amount of steam is removed; since the feed is in liquid form, it needs to be vaporized, and for that heat is required, right? I don’t know either how the over-cooling issue mentioned on the 3rd floor comes about. When I was operating before, I hardly ever paid attention to the pressure difference in the middle and lower sections; now that I think about it, it is indeed something that should be taken into consideration. What I focused on more was the temperature in the middle and upper sections. I’m not sure what information the pressure differences in various areas can reveal I would appreciate some guidance from experts.

It was correct for the poster to turn off the extraction, but there was no need to turn off the feeding. More steam can be used to increase the pressure. I think that decrease in pressure is probably caused by excessive venting. As the pressure decreases, more vapor may be directly vented from the top of the tower, resulting in no reflux. Although a decrease in pressure should result in an increase in the volume of rising gas, this rising gas still has to overcome the backflow within the tower, which leads to large pressure differences being generated along the way. Interrupting the feed definitely affects the equilibrium of the tower, because with the steam volume remaining unchanged, stopping the feed is equivalent to increasing the amount of steam.