Is the initial distillation point of catalyzed diesel controllable?

The initial boiling point of light diesel can be adjusted by controlling the dry point of crude gasoline; however, it cannot be very high. Generally, the dry point of crude gasoline does not exceed 205 degrees, which is also the maximum temperature for the initial boiling point of light diesel. It is beyond doubt that raising the initial boiling point of light diesel increases gasoline production. For specific operations, appropriately increase the top temperature and slightly raise the stripping steam in the light fuel oil stripper to ensure good separation results. This post was last edited by chengkang on 2009-2-28 14:58.]

I think it’s to reduce overlap and achieve increased production. . .

If you want to increase production, use the diesel production method – a good way for small refineries to boost diesel output: http://bbs.hcbbs.com/thread-58287-1-1.html

In our workshop, the initial boiling point of light diesel is around 165 degrees, while that of gasoline is around 190 degrees. Do not allow the gasoline dry point to become too high in an attempt to blindly reduce overlap. There is definitely overlap between gasoline and diesel.

Yes, overlap between gasoline and diesel is inevitable; a fractionation tower is not a distillation tower, so it’s normal for there to be overlap.

As the initial distillation temperature of diesel increases, the temperature rises as well; gasoline production might increase, but it is also necessary to consider whether its dry point is within acceptable limits. In such a case, an increase in gasoline production may not occur

The diesel flash point and crude gasoline can indicate the distillation efficiency of the fractionation tower. When the diesel flash point is higher than the gasoline dry point, it is called voiding; otherwise, there is overlap. This is related to the tray design of the fractionation tower; from an operational perspective, increasing the agitation steam and stripping steam at the bottom of the tower, raising the temperature at which diesel is extracted, and properly controlling the tower top temperature as well as the temperature of the overhead stream returning to the tower all help to reduce overlap. In the past, when the processing volume of our unit was low, floating valve trays were used to achieve degassing. Now that the processing volume has increased and new trays have been installed, overlapping still occurs no matter how it’s adjusted. In any case, gasoline viscosity needs to be controlled. As long as the diesel flash point meets the requirements, that’s sufficient.

For example, if the boiling point of gasoline is 200 degrees, and the initial boiling point of diesel is also 200 degrees, then increasing production can be achieved. . . .

To increase the initial boiling point of diesel, it is necessary to raise the temperature at the top of the tower, lower the pressure in the distillation column, increase the dry point of the crude gasoline, raise the distillation temperature of diesel, increase the amount of stripping steam used in the diesel stripping tower, and elevate the flash point of diesel while reducing the amount of light components in it. However, this will result in an increase in the freezing point of diesel. If the freezing point of diesel is to remain unchanged, it is necessary to send the heavier components in diesel to the bottom of the tower, which increases the yield of sludge and reduces the overall yield of the plant. If this sludge is not removed in large quantities but instead reused in processing, it will increase the amount of coke generated during reactions, thereby limiting the processing capacity.

1. Appropriately increase the amount of steam used for diesel stripping. 2. Slightly raise the dry point of crude gasoline. 3. Properly separate heavy recycle oil from diesel. 4. Control the temperature at which diesel is extracted as well as the liquid level in the diesel stripping tower – that is, increase pressure at the top, reduce it at the bottom, and extract liquid from the middle