Coke Formation in Reactor Systems
Coke Formation in Reactor Systems
(OP)
I have a project to install new heat transfer equipment in a paraffin dehydrogenation reaction loop (UOP Pacol Process) with a end of run reaction temperature of about 920F. I have recieved the recommendation that we should sulfide our substantial amount of new metal at start-up to reduce catalyzed coke formation. This recommendation is being challenged by operations, and now I must formulate some response to the question of what the consequences are if we forego sulfiding. Previous projects in this unit and in our other Pacol units have generally sulfided metal prior to putting into service so I have no reference points for not sulfiding.
The current process has some cracking products (CH4, C2's, C3's, etc) in the recycle H2, and our heat exchanger has a low density carbon build-up that must be cleaned every few years to reduce pressure drop and restore heat transfer. I have recieved some good but conflicting opinions from engineers in other units where I have worked that have coke formation histories (ethylene and hydrotreating units). One area of uncertainty is catalyzed vs thermal mechanisms since it is reasonable to believe that a one time sulfiding will not have any effect on thermal decomposition.
Can anyone point me to some literature on this subject?
thanks,
sshep
The current process has some cracking products (CH4, C2's, C3's, etc) in the recycle H2, and our heat exchanger has a low density carbon build-up that must be cleaned every few years to reduce pressure drop and restore heat transfer. I have recieved some good but conflicting opinions from engineers in other units where I have worked that have coke formation histories (ethylene and hydrotreating units). One area of uncertainty is catalyzed vs thermal mechanisms since it is reasonable to believe that a one time sulfiding will not have any effect on thermal decomposition.
Can anyone point me to some literature on this subject?
thanks,
sshep





RE: Coke Formation in Reactor Systems
If in-situ sulfiding is a problem for Operations, this can generally be done off-site as well by companies like Eurecat.
RE: Coke Formation in Reactor Systems
I would love to give you a differnt opinion but since my limited experience in oil was actually with UOP I would also say sulfide the bare metal to avoid catalyzed coke formation from "active sites" in the metal.
I would also comment that not doing it is certainly more risky than doing it and having the operators complain that you are wasting there time for a couple of weeks. Donuts can always buy your way out of that.
I don't know of any book that comments on it but you might look in the oil & gas journals for articles. I know it was often a subject of discussion at UOP when the temps reached the 900F mark.
Goodluck
StoneCold
RE: Coke Formation in Reactor Systems