Increase the initial boiling point of catalytic cracking diesel

The initial boiling point is a cutting issue that has nothing to do with the reaction; it is mainly a matter of distillation adjustment. If the initial boiling point is too low, the operation involves the temperature in the upper middle section as well as reflux

Jinzi1973 posted on 2009-3-1 22:09: 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 steam used for stripping in the diesel stripper, 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 slurry and reduces the overall yield of the plant. If this slurry is not removed in large quantities but instead reused in processing, it will increase the amount of coke formed during reactions, thereby limiting the processing capacity.

Slightly increase the stripping steam in the gas column when the diesel flash point is not high. It is possible to reduce the backflow volume in the middle and lower sections; at the same time, to ensure a lower dry point of the diesel, the temperature of the diesel extraction stream can be lowered as well

Raising the initial distillation point of diesel has no relation to the reaction process; the pressure in the fractionation tower is also determined by the pressure of the reaction system, with no possibility for adjustment. The dry point of gasoline can be increased by raising the amount of stripping steam used.

It is related to the separation efficiency in the upper part of the distillation tower. Under normal conditions, the dry point of the crude vapor and the initial boiling point of light diesel should be separated; if there is overlap, the separation efficiency decreases. Salt formation in the distillation tower and improper design of the two diesel extraction points often lead to significant overlap between the initial boiling point of light diesel and the dry point of the crude vapor.

Increase the diesel extraction temperature and the top temperature of the tower, reduce the pressure at the top of the distillation column, and increase the amount of stripping steam used.

The temperature at the top of the tower should be higher; the coarse gas should be lifted as it dries out, and there must be sufficient steam in the diesel stripping tower

The dry point of crude gasoline increases, while the initial distillation point of diesel remains essentially unchanged; the overlap rate becomes higher

By increasing the diesel extraction temperature, the 95% point of the diesel exceeds the specified value, but the initial boiling point does not change much

The initial distillation temperature of diesel has little to do with the reaction; what’s crucial is the operation of the separation system. The tower top temperature directly determines the final boiling point of gasoline; meanwhile, increasing the reflux ratio reduces the overlap between gasoline and diesel

This is a distillation issue, and it can be achieved in practice.