What causes the reverse temperature in the pre-tower?
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This post was last edited by Small and on 2017-9-9 22:49. In triple-column distillation, extraction water is added to the pre-column in order to remove the light components from crude methanol. Under normal conditions, the temperature at the bottom of the column is higher than that at the top, and the pressure is slightly positive; so why does it sometimes happen that the temperature at the bottom of the column is lower than that at the top?
No one answered, so I’ll throw out an idea to stimulate discussion. The reason should be related to the extraction water.
This post was last edited by Small and on 2017-9-10 at 12:34. Extracting water is generally added to the top of the tower or into the reflux tank. An inverted tower temperature is a clear indication that there is an excess of extracting water; by gradually reducing the amount of extracting water, the temperature difference caused by this inversion will diminish over time, until normal conditions are restored. Temperature inversion does not affect the removal of light components in the pre-tower, but it increases energy consumption downstream, as well as the difficulty and cost of the distillation process. Excess water leads to increased steam consumption and more wastewater that needs to be treated, thereby invisibly raising costs. Although it is not a major issue, analyzing the reasons and understanding the changes in the material composition under constant temperature and pressure conditions can enhance the operators’ awareness of the entire distillation system.
It must be tough for you to provide this kind of self-explanatory knowledge dissemination
Hehehe, there’s no other way; without popularity, one has to do this first. Maybe it’s necessary to share some content that interests people
These are all old problems; they can be found with just a search, so I’m too lazy to look at them :)
This post was last edited by Small and on 2017-9-11 at 17:54. It’s indeed an old issue, but many supervisors still don’t understand it or aren’t clear as to why it happens. Back then I organized a class discussion to conduct educational talks, and ten years have passed in the blink of an eye; sadly, I find that many people still can’t grasp simple issues. I don’t understand the reason for this either—it’s a problem with leadership. To put it in more colloquial terms: all problems stem from poor management. Strengthen learning so that everything is stored in one’s mind, and one knows how to handle situations properly when they arise.
This is because there is a high amount of CO2 in the non-condensable gas, and the reflux liquid contains a lot of water; when the CO2 in the non-condensable gas dissolves in water, a large amount of heat is generated. As a result, the temperature at the top of the tower is relatively high. I came to this conclusion after working on distillation for several years. Hehe