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 tower top. If I keep the temperature at the tower top within the specified range (70–90 degrees), by reducing the amount of reflux at the tower 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 and thereby affect 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. :dizzy:
Yield has nothing to do with fractional distillation. If it’s about improving product quality, such as the content of light oil. It is possible. Of course, there is also a limit value; you need to determine the relative volatility of your components. If you want to increase production, it’s sufficient to adjust the reflux ratio. But the problem it causes is a decline in quality. Production can also be increased by raising the power of the reboiler, but this leads to higher energy consumption. In a distillation tower, its packing has a reasonable operating range for vacuum level. Beyond this range, there is a conflict between filler efficiency and energy consumption. It’s a matter of balance, depending on your goals.
Doesn’t increasing the vacuum level improve the light oil yield?
Improving the vacuum level essentially means increasing the theoretical number of plates in the column, thereby achieving a better separation effect. Increasing the reflux ratio is another option, as is raising the number of trays; however, the problem is that energy consumption will increase. The key is whether you can accept your costs.
Increasing the proportion of heat extraction from the middle section appropriately to balance the pressure drop across the tower plates can improve the vacuum level in the gasification section. But I wonder why, sometimes, as the temperature at the top of the tower rises, the vacuum level also increases. If less reflux is used at the top of the tower, thereby raising that temperature, could that not also lead to an increase in the vacuum level? Wouldn’t this contradict the idea that an increase in the top temperature results in a greater vapor load, which in turn causes the temperature after cooling to rise and the vacuum level to drop?