Why is the reflux ratio increased after reducing the feed to the distillation tower?
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When a distillation column needs to reduce its feed rate, both the top and bottom outputs decrease, but why does the reflux flow increase? Isn’t it sufficient to maintain the reflux ratio while ensuring quality? Simulations using Aspen showed that such a large reflux flow rate is not necessary to meet the quality requirements. I don’t know how to solve it
It’s not done in practice, right? It’s all at a normal reflux ratio; there’s not much adjustment needed
We have carried out operations to increase the reflux volume; when we asked the technician, he said it would result in a dry plate
This depends on the flexibility of the tower operation; both the amount of gas and liquid are within certain ranges, which must be maintained
As the feed amount decreases, the amount of product at the top of the tower drops as well, and the load on the top of the tower is reduced. To maintain circulation of the liquid phase at the top, it is common to increase the reflux rate; in practice, the actual reflux ratio is much higher than the designed value； From another perspective, top reflux pumps generally have minimum flow requirements; the flow rate at the pump outlet must be kept above the minimum value specified on the performance curve. When the amount of product is low, the reflux flow rate is increased.
Just proceed according to the actual operations
It seems that your feed temperature is lower than the reflux temperature
There isn’t any; the reflux temperature is low
If the bottom temperature of the tower is not adjusted after reducing the flow rate, too much vapor will flow toward the top of the tower, which in turn causes the liquid level in the reflux tank to rise and requires an increase in the reflux volume