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Our project has an amine FCCU and amine sweetening and SRU, but sulfur recovery will be in service 1 year after FCCu start up. There is a problem with feedstock of SRU that must be sent to acid flare (with 32 m length). What can we do with this stream with 80%wt h2s witout sending it to flare?
 
Answers
10/02/2011 A: Lindsay McRae, Pall Corporation, Lindsay_McRae@pall.com
1) Use sweet crude only for first year to minimise amount of S to treat.
2) Send off gas from amine regenerator to fuel gas network - but that may well put RFG off spec for SOX emissions from the fired heaters/furnaces. If this stream is a small % of total RFG stream then you might be able to get away with it temporarily. But the SOX emissions will increase for sure.
3) Shut the FCC for a year until the new Sulphur plant is built. ( Don't laugh - FCC unit shutdown happens if S plant burns down and there is no way to treat H2S from FCC , SWS or from hydroteaters).
Note: It is unlikely such a stream will be permitted to be sent to flare. That is a major environmental & safety hazard. When Sulphur plants trip and H2S sent to flare, that usually will often trip complete shutdown depending where you are in the world and what the local environmental legislation allows. In some cases, where sulphur plant is inoperable for some reason (like due to fire in Klaus reactors), refineries have been known to shutdown & operate as fuel terminals importing all products from sister refineries or buying product on open market until Sulphur plant is operable again. Without meeting envionmental license requirements, most refineries these days just cannot operate. So it can be a case of 'the tail wagging the dog'. Sulphur plant operation can dictate the FCCU operation. Good luck with that.
28/12/2010 A: Hubert Mueller, Bayernoil, guhumueller@web.de
There are a few possibilities to make use of the H2S stream temporarily until you get your SRU on stream but you have to be very careful because of the H2S is extremely poisonous and you have to decide if the heating value of the stream is high enough to compensate for the danger you are adding to your complete plant by f.e. firing the H2S. Another aspect is your operating permit, does it allow the use of the H2S stream other than in the SRU.
You can simply leave the H2S in your fuel gas system with all the problems and dangers of a much higher poisonous concentration of H2S all over the plant. Think also about contaminations by using fuel gas for blanketing. And think of the smell!!!
Another possibility would be to fire the stream by special separated burners in a large heater including all safety precautions necessary like for the firing of normal fuel gas. The danger of higher corrosion in the flue gas system needs to be carefully considered.
Again once more you may be faced with a lot of problems following these possibilities and you need to decide very, very carefully.
24/12/2010 A: keith bowers, B and B Consulting, kebowers47@gmail.com
There is a process that uses anhydrous ammonia reacting with wet H2S to make ammonium thiosulfate for use in fertilizer.
You could also purify and liquefy the H2S for use as reagent in making mercaptans and similar sulfur based compounds. Penwalt Chemicals is a key player in that use.