Top circulation or cold reflux is used respectively to control the temperature at the top of the fractionation tower; regarding the efficiency of diesel and gasoline separation, which of the following statements is correct?
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Top circulation or cold reflux is used to control the temperature at the top of the distillation tower. Regarding the efficiency of separating gasoline from diesel, which of the following statements is correct? A. Top circulation yields a better separation effect. B. Cold reflux yields a better separation effect. C. It’s impossible to determine. D. The effects are the same. The answer given for this question is B; I don’t understand the difference between A and B
If option B is chosen, then there’s no point in setting up a top circulation oil system.
If only the separation efficiency is considered, cold reflux is better; however, taking into account factors such as tower pressure drop, product yield, and heat removal, top circulation is more appropriate.
Simple cold reflux features high separation precision, but the downside is higher energy consumption. By adopting a top-loop cooling reflux configuration, it is possible to take advantage of both the advantages and disadvantages: low-temperature heat can be recovered, reducing energy consumption; the amount of cooling reflux is also reduced, allowing separation precision to be controlled and thus lowering the energy consumption of the system.
Due to differences in components, mass and heat transfer in the top circulation are inferior to those in cold recirculation.
How can the heat recovered through top circulation be meaningless?