FCC Off gas contaminants

[Anonymous]

A Refinery located in Southamerica, well known by us, process their FCC Off in an Amine Treatment Unit (with MDEA) in order to remove the H2S present and then use it as refinery fuel gas. However, they have been having serious operational problems due to MDEA degradation and the heat stable salts (HSS) presence. We know that HSS formation is due to an irreversible reaction between strong acids anions (such as formate, acetate, thiosulfate, thiocyanate and chloride) and the amines molecules.
Does the concentration of these contaminants (strong acids anions) in the FCC off gas is known for you in some how?
Do you have any typical composition for the FCC off gas which shows this contaminants concentration?
and finally, Do you know how can these contaminantes be removed previously to the amine treatment?
Any information would be very usefull.
Many thanks in advance.

[Daniele Colle]

I don’t know of any way to remove these contaminants before MDEA treatments. I can only think that good water injection facilities at the MF OVHD or WGC discharge could help keeping some of them in the water boots instead of getting the contaminants in the offgas.
I believe you have to deal with the problem in the MDEA system.
We keep HSS in control by reclaiming outside the fence.

[suhas nehete]

If you are facing a lot of issue with this high acid anions water washing of the FCC off gas prior to  MDEA absorber should help in removal of these anions.

[Anonymous]

FCCU Standpipe:
If we got a little watr inside the standpiep do we need to apply dry out procdure for that protion?
 
thx  

[Author]

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