When changing from a gasoline scheme to a diesel scheme, how should the distillation operations be adjusted?
Thread Content
When changing from a gasoline scheme to a diesel scheme, how should the distillation operations be adjusted? What should be noted
When switching from gasoline to diesel, the feed to the distillation tower becomes heavier; at this time, the most important thing to pay attention to is the level in the re-refining tank. It is necessary to lower the temperature at the top of the tower appropriately in order to control the amount of diesel produced
The top temperature can be reduced or cold reflux can be used to lower the dry point of gasoline; part of the gasoline components can be forced into diesel, thereby increasing the temperature in the middle section of the distillation tower and boosting the amount of diesel obtained. In the diesel scheme, the reaction temperature is low, which prevents a high liquid level in the fractionation tower; therefore, the bottom temperature and the temperature of the baffles are increased appropriately. Additionally, prevent excessive pressure drop in the fractionation tower.
Reduce the circulation volume of the distillation column bottom slurry, increase the load in the middle section, raise the amount of top circulation reflux and cold reflux, lower the temperature at the top of the distillation column, decrease the dry point of gasoline, and as a result the yield of diesel increases due to an increased amount of diesel obtained. Note that the diesel flash point will decrease.
Pay attention to the liquid level at the bottom of the tower; reduce the top temperature and force the heavier gasoline components into diesel. This not only increases the yield of diesel but also reduces its specific gravity as well as the sulfur content in gasoline
Based on the analysis of gasoline and diesel distillation ranges, it is necessary to reduce the temperature at the top of the distillation tower, increase the tower pressure, and lower the temperature at the bottom of the distillation tower, all while ensuring that the flash point of the diesel remains within acceptable limits
Switching from a gasoline-based scheme to a diesel-based one increases the density of the feed gas to the distillation tower; with the total reaction feed remaining unchanged, it is possible to raise the temperature of the oil slurry fed back into the tower in order to increase the load in the upper sections of the tower. Pay attention to the liquid level in the reprocessing tank, and increase the amount of oil reprocessed as appropriate. Appropriately reduce the tower top temperature to lower the gasoline yield, but pay attention to the diesel flash point.
Increase the top circulation reflux and cold reflux to lower the temperature at the top of the fractionation tower, increase the load in the middle section; pay attention to maintaining stable absorption levels and the pressure entering the tower. Reduce the amount of slurry returning to the tower and increase the amount returning to the bottom of the tower. Pay attention to the washing efficiency and increase the volume of oil reprocessing circulation
The reaction depth can be reduced slightly; while ensuring the product quality is satisfactory, efforts should be made to increase the extraction temperature and the temperature in the reverse column. Lowering the dry point of crude gasoline can improve the yield of diesel
If you do not need to control the diesel boiling point, you can also reduce the amount of steam used for diesel stripping accordingly.
Reduce the reaction depth, lower the top temperature of the tower, and make more use of catalysts to increase diesel production
Reduce the top circulation extraction temperature and increase the diesel extraction temperature