. When the feed composition remains unchanged and the temperature at the top of the distillation column is too high, measures can be taken
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When the feed composition remains unchanged and the top temperature of the distillation column is too high, the following measures can be taken. A. Increase the reflux rate B. Reduce the bottom product withdrawal C. Lower the reflux temperature D. Reduce the steam volume at the bottom of the tower
Option A should be chosen. Reducing the draw rate at the bottom of the tower disrupts the material balance, which leads to an increase in the concentration of heavy components at the top of the tower and an elevation in the temperature there. Lowering the reflux temperature doesn’t have much effect. Reducing the amount of low-temperature steam in the tower will lead to a decline in separation efficiency
A or C is fine. Is this a question from the CPA exam?
The reflux temperature is not easy to lower; it is preferable to choose option D, which reduces the amount of vapor at the bottom of the tower.
Option D should be chosen; reducing the steam volume at the bottom of the tower causes the temperature of the entire tower to drop, including at the top as well. The reflux flow rate must be adjusted according to the feed composition; arbitrary adjustments will disrupt the material balance throughout the tower and increase energy consumption.
During production, the reflux temperature is reduced and the reflux flow rate is increased, while the bottom temperature of the tower is lowered. Temporary product specifications may show some non-conformities, but these are acceptable to ensure operational safety.
This post was last edited by taomaosheng on 2015-7-17 09:50. A: Meets the requirements; product quality improves while unit consumption increases. B: Theoretically feasible, right? C: Theoretically feasible. D: Meets the requirements; production volume decreases； Looking at the question more carefully, the temperature at the top of the distillation tower is too high, meaning the gas phase is superheated; therefore, it must be that there is too much steam at the bottom of the tower, so the answer is D
Premise? In this state, are both the bottom and top of the tower qualified? Theoretical question-setting operates under a different theoretical framework from actual production. From a theoretical perspective, the condition is such that both the top and bottom of the tower are within acceptable parameters; however, if steam consumption is reduced while the processing volume remains unchanged, then the product will not meet the standards. Therefore, D cannot be chosen – C can be selected instead. In practice, option D is usually chosen; it’s not considered acceptable in such a situation – reducing the steam amount immediately results in it no longer being acceptable