Mid-section reflux
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The side draw and mid-stage reflux from the fractionation tower are drawn from the oil collection tank at the same tray level. What impact do the amount of mid-stage reflux and the temperature difference have on the amount of side draw?
Under normal circumstances, mid-section reflux is not used to adjust product quality; changing the amount of mid-section reflux can alter the thermal balance of the entire column or the amount of top reflux, so the amount of mid-section reflux and the temperature are generally not adjusted. . If, under special circumstances, the midstream reflux flow increases, then the product extracted via the side stream will be lighter, as more light components cool down. The liquid level in the oil collection tank is regulated by using differential pressure to control the flow rate of the downcomer. So I think this issue needs to be considered comprehensively, including the depth of your response, the back pressure, and whether the backflow rate remains unchanged. Simply speaking, it is difficult to establish a relationship between the backflow volume and either the production volume on your side or the liquid level in the oil collection tank.
A high reflux flow rate in the middle section, along with a low reflux temperature, can affect the side-product, causing it to have a lower density. Generally, the temperature is adjusted to prevent excessive fluctuations in the reflux flow rate