The feed is cut off catalytically – why does the slurry volume increase?
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Why does the amount of slurry increase after the catalytic cracking unit stops feeding reactants, requiring a large amount of slurry to be discharged? Why is there still a large quantity of slurry produced when no feed is being supplied?
I don’t think there will be a large amount of slurry; it’s likely that the temperature of the distillation tower drops rapidly, causing the liquid level at the bottom of the tower to rise. To maintain a normal liquid level, it’s necessary to increase the amount of slurry that is removed from the tower!
The components that are discharged are not all oil slurry; by stopping the feed, the temperature of the distillation tower drops, and the middle-phase components cool down, which leads to an increase in the liquid level in the distillation tower. This increases the amount of liquid that is discharged in order to control the liquid level
For a tower, it is a space for the exchange between the gas phase and the liquid phase. Although the feed is cut off, due to the absence of vapor-phase components, as the liquid-phase load increases, the liquid-phase components move downward, and thus the liquid level also rises! Furthermore, after stopping the feed, since a large amount of catalyst is present in the reaction gas stream and needs to be removed through slurry washing, it is necessary to increase the amount of slurry at this time to ensure effective washing and prevent a large quantity of catalyst from entering the upper sections of the tower and clogging the trays
It can be understood as the reaction feed being cut off, resulting in the distillation column losing its heat supply; coupled with the fact that the three reflux streams continued to operate, the liquid phase was pushed to the bottom of the column. As mentioned on floor 3, “not all of the components separated out are oil slurry.” At this point, the distillation tower has lost its ability to separate the fractions.
There is another very important reason: after the feed is cut off, the pressure in the reaction increases due to an increase in the amount of slurry
Is there a line from the crude oil to the bottom of the tower, enabling reflux? Another issue is insufficient heat, which results in an increase in light components.
The views expressed by those upstairs are all valid. There is another reason: many units have feed oil return lines, and after the reaction mixture is separated, the feed oil returns to the distillation unit via these return lines, causing the levels in the reprocessing tanks and at the bottom of the towers to rise. It is necessary to discharge this excess fluid, but at this point what is discharged is not just the oil slurry component.
When we cut the feed oil in a short period of time and send it back to the line, we don’t change anything in the distillation tower; instead, we send it back to the feed oil tank
Hehe, everyone has already explained it in great detail; I’ve learned a lot
Well, it would be best to restore feeding and improve the crude oil tank in a short period of time. :lol