The issue of component variation in distillation columns
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This post was last edited by slw1212 on 2021-3-10 20:21. In a distillation column for binary systems, with no changes in the feed rate or composition, the column operates in a steady state. An increase in the amount of product taken from the top of the column, as well as an increase in the steam flow, leads to an increase in the amount of product obtained from both the top and bottom of the column. After a new equilibrium is established, the concentration of the light components at the top of the column decreases. I would like to ask how the concentration of the light components in the bottom of the tower will change – will it increase?
For a distillation tower, two types of balance need to be considered: heat balance and material balance. The amount of product taken from the top of the tower has increased; since the light components are enriched at the top of the tower, the amount of light components at the bottom of the tower decreases. But the draw rate from the bottom of your tower should not increase (with the feed remaining unchanged and the top of the tower expanding, the draw rate from the bottom of the tower should decrease). ）
Thank you, I have some issues with my description. Does that mean the yield from the tower bottom decreases, and how does the concentration of the light components at the tower bottom change?
If the feed rate remains unchanged and both the top and bottom outputs are increased, the tower won’t be empty – how can there still be a steady state?
Observe the changes in the reboiler temperature (in correlation with pressure); an increase in reboiler temperature indicates a decrease in light components, while a decrease indicates an increase in light components.
With the feed composition and feed rate remaining unchanged, increasing the vapor at the bottom of the tower reduces the light components there. The best approach is to increase the reflux flow slightly within the range acceptable for the tower load; this will improve the yield