[Daniele Colle]

We have a normal SWS, reboiled with steam. 6 years ago we had to retube the reboiler on the run. We would have gone out of service with half of the refinery if we stopped the SWS for the 2 weeks that were needed for repair, thus we decided to run the steam directly to the stripper through the reboiler return (2 small outages to disconnect the old and connect the new pipe and vice-versa).
It worked well, but we obviously lost some capacity and we had issues with high pH in SWS bottoms (pH of around 9 in BFW system). If you use your SWS rundown in the desalters this can create some problems.

[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.

[Daniele Colle]

I would not consider LCO quench as a technology that reduces transfer line coking. LCO quench should mainly reduce gas yields in the FCC. Regarding transfer line coke, issues could be related to feed injection (poor atomization, feed too heavy), low velocity and cold spots in the OVHD line.
We had a run with 1 out of 8 feed injectors in a poor shape and we saw lots of coke buildup in the transfer line (none in the riser).

[Daniele Colle]

In the case of a VSS termination device I believe UOP would be the only source of information you can use. Their CFD studies should be reliable…

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