On the relationship between vacuum degree and top temperature in improving the light oil yield of a vacuum distillation column
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To increase the yield of light oil in the vacuum distillation tower, is it true that the higher the vacuum level, the better? However, a higher vacuum level results in a higher temperature at the top of the tower. If the temperature at the tower top is controlled within the specified range (70–90 degrees), then by reducing the amount of reflux at the top, could the yield of light oil increase? If the temperature at the top of the tower is high, will it increase the load on the vacuum pump, thereby affecting the vacuum level? Also, why is it that the temperature at the top of the pressure reduction tower cannot be too high or too low? What impacts does this have on the yield and on the equipment? I’ve raised so many questions at once; thank you all for taking the time to offer your guidance. New poster here; not sure which forum section is appropriate. If this post appears elsewhere, please feel free to delete it – thank you very much for your understanding
The better the vacuum under reduced pressure, the higher the yield. Reflux at the tower top should be adjusted according to the load, keeping it within the specified range; too low a level increases the load, while too high a level affects both the yield and operational efficiency
This post was last edited by decem on 2011-5-11 at 12:36. Setting the reflux at the top of the tower too low results in an excessively high temperature there, which increases the load on the vacuum pump and thus affects the vacuum level. Then why, sometimes, does an increase in the top temperature also lead to an increase in the vacuum level? If less reflux is used at the top of the tower, thereby raising the top temperature, could that also increase the vacuum level? Wouldn’t this contradict the idea that an increase in the top temperature leads to an increased gas-phase load, a rise in temperature after cooling, and a decrease in vacuum level?
The prerequisite for increasing the top temperature is to maintain a constant vacuum level; if the temperature becomes too high and affects the vacuum level, it will have the opposite effect on increasing the yield
It is necessary to control the high vacuum level in the vacuum distillation tower; only under such conditions can the yield of the tower be increased. I believe the temperature at the top of the tower should not be too high, as no product is produced at that point – it’s only used for sending off waste oil. Raising the temperature at the top of the tower would increase the amount of waste oil, thereby raising the costs associated with reprocessing it. Therefore, it is advisable to set the extraction temperature at the side stream slightly higher, provided that the quality of the products obtained from the vacuum side stream remains satisfactory. This approach helps to increase the yield of light oils. However, the temperature at the top of the tower should be controlled through reflux mechanisms, so as to ensure that there isn’t an excessive amount of waste oil. This represents a balance point, and the key is to maintain this balance properly!