The impact of the mid-section reflux volume on operation
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In a vacuum distillation unit, when the distillation temperatures of the various side streams remain constant, what impact does the amount of mid-section reflux have on the operation?
Improving the quality of top products; the top temperature is affected
It can increase the side-stream distillate volume and raise the side-stream yield.
Increasing the side-stream reflux rate can enhance heat extraction, which in turn affects the operation of the entire system. Excessive heat extraction is not favorable for the thermal balance of the whole tower; therefore, under normal circumstances the mid-section reflux remains unchanged, unless there are significant changes in the processing volume~
Increasing the mid-section reflux can boost the amount of heat removed by the reflux; in the case of cold reflux at the tower top, it can also effectively regulate the temperature and pressure at the tower top. When controlling product quality, increasing the midstream reflux flow rate of the atmospheric side stream can adjust the quality of the product from the upstream side stream, such as the dry point and initial boiling point. As for what was said on the third floor: the intermediate section of our atmospheric and vacuum distillation unit is used to adjust the quality of the product. For the vacuum side stream, increasing the reflux from this intermediate section will actually reduce the amount of distillate produced. For the atmospheric side stream, increasing the mid-stage reflux will affect the product quality of the upper and lower side streams. I’m not sure what you mean by increasing the distillate volume – why would it increase? Which side line has been improved then?
This post was last edited by lxr0406 on 2010-12-25 09:33. As the people above have said, increasing the reflux rate can affect the quality of the product in the side streams, and it can also alter the thermal balance of the entire system. When the processing volume changes, the reflux at various stages should also be adjusted accordingly. However, in my setup, even when the processing volume changes, there is no need to adjust the reflux at the intermediate stages, and the distillation temperature does not change much either. I’m a bit confused; please help discuss this issue. Furthermore, what are the advantages and disadvantages of operating with high reflux rates and high reboiler temperatures, as compared to low reflux rates and low reboiler temperatures?