Resolving the issue of secondary coking in reforming
Thread Content
During a minor refurbishment, severe coking occurred inside the second reactor, causing deformation of the Johnson mesh. The thickness of the coke layer reached 10 centimeters and it was very hard; in the end, it was necessary to cut through the mesh to remove the coke. The reactor thus turned into a coke tower. What caused this? Please analyze the reasons
The bed reaction temperature, hydrogen-to-oil ratio, space velocity, and feedstock could all be factors. The reaction temperature may be the main cause of deformation in Johnson nets.
The carbon buildup is most severe in that area of the second reactor. In places where there is the most carbon buildup, the flow of the catalyst must not be very smooth. As more and more carbon accumulates, could this cause problems during installation? Are the catalyst transfer pipes from the first reactor to the second reactor, as well as those from the second reactor to the third reactor, all smooth enough? Could there be uneven distribution of the catalyst? There’s also what was mentioned on the second floor regarding the reaction temperature; if it’s too high, you’ll notice that there might be a significant deviation in the readings from the thermocouple. Don’t you have any specifications regarding the reactor pressure difference? If it’s not allowed, then it should be measured regularly on a monthly basis, so as to better track and analyze any issues. If only one reactor is coked, it should not be greatly affected by the space velocity, hydrogen-to-oil ratio, or the feedstock. The reason should be sought within the second countermeasure itself.
Is it time to replace the catalyst? Is the hydrogen-to-oil ratio incorrect, or has a feedstock with a higher aromatic content been used?
It seems that Erfan is prone to coking, and the same is true for other factories
It’s been repaired, let me tell you all about it
Is it the central tube or the fan-shaped cylinder that is being cut? I’ve never heard of anything that, after being cut, returns to normal even after welding; usually problems arise again in a very short time.
The cleaning of coke must be thorough; it is best to use sandblasting for descaling. Because the remaining char is equivalent to seeds. If there is only secondary coking, it is generally a problem with sulfur injection. The coking that has occurred is mostly in Reactor 1 and Reactor 2.