How can scaling and coking be prevented in the inlet and outlet pipelines of the standby slurry steam generator in catalytic units?
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In catalytic cracking units, due to design reasons, there are several meters of dead zones at the inlet and outlet pipelines of the standby slurry steam generator. Over time, scaling and coking tend to occur, and these issues cannot be resolved during steam purging operations when the unit is shut down. I would like to ask if anyone has encountered similar problems, and what effective measures can be taken to address this situation?
A cross-bar can be added at the base of the inlet flange and the base of the outlet flange to maintain the fluidity of the slurry.
The slurry steam generator can be switched regularly; just like our pumps, it is used at intervals
I don’t think it’s appropriate to switch to the slurry steam generator, unless there is a large pressure drop that causes coking and affects heat exchange efficiency. Responsible for being time-consuming, labor-intensive, increasing the workload, and introducing safety risks! Diesel can be injected at the inlet to replace it and prevent coking
I’ve never encountered that; as a backup for our unit’s slurry steam generator, we use a heat exchanger that operates with steam to heat the crude oil. Actually, what was said upstairs about adding a cross-line is quite good.
Try to inject it into the unit that is closest to the main pipe; if the oil slurry stays in the tee for a long time, some catalyst will deposit there, leading to coking.
A short cross-connected pipe of DN40 is installed in front of the inlet valve and behind the outlet valve; with the throttle valve set at 3-4 notches, coking has never occurred.
There is no need to change the equipment; physical methods can be used to prevent scaling in the pipes, which is simple and easy to implement. You can communicate at shcsb11@163.com
In 2013, the spare heat exchanger had a vertical pipe nearly 3 meters long at its inlet; due to lack of use over time, it became clogged with carbon deposits and wouldn’t function properly when put into use. There was also a line for heavy crude oil in front of the valve. We used the heavy residue oil line to pump in diesel, and it was quickly unblocked. Now it’s maintained in this way: there is a connection between heavy residue oil and diesel, and all of these can be handled with heat exchangers! I hope it helps you!