Some questions about distillation columns, seeking answers
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For example, now that the distillation endpoint of diesel is higher, it’s possible to increase the amount of reflux or lower the reflux temperature. But it seems to me that these two approaches are contradictory – increasing the reflux amount involves opening the reflux control valve, while lowering the reflux temperature involves closing it; isn’t that a contradiction? Please help!
The answer above is correct; it’s all about extracting heat, and there’s no contradiction
Yes, there is no contradiction. These two aspects need to be considered separately: increasing the circulation rate means that, with the cold end remaining unchanged, more heat can be extracted in effect. Similarly, lowering the return temperature achieves the same result
As long as it can achieve the purpose of lowering the temperature, that’s enough! There is no contradiction; to lower the temperature, one can increase the reflux rate, reduce the feed temperature, or lower the bottom temperature – generally, reflux adjustment is used