Q & A > Question Details
In our regenerative caustic treatment system a disulfide stream is generated. Which is the best destination for this stream in the refinery (FCC, coke drum, hydrotreater, naphtha feed, others)?
27/05/2020 A: Morgan Rodwell, Fluor Canada Limited, morgan.rodwell@fluor.com
The disulfide stream from a caustic treater is most often routed to a hydroprocessing unit where the RSSR/RSSH molecule can be destroyed and the sulfur converted to H2S. Depending on what the source of the disulfides are (is this caustic treater handling lighter or heavier feed), it would be routed to a naphtha or distillate hydrotreater.
27/05/2020 A: Lindsay McRae, Pall Corporation, Lindsay_McRae@pall.com
Most refiners will send the disulphide oil stream to DHTU feed to dispose of it. However it is important that also no caustic solution from the extractive caustic treater should be sent back to DHTU otherwise DHTU catalyst may be poisoned by this caustic solution.

Pall Phasesep LL coalescer can effectively remove the caustic solution from the gasoline rinse / disulphide oil stream.

27/05/2020 A: Nagarathinam S Murthy, Ashphil Consultancy, Chennai, nssvdvr@gmail.com
Reliance has the patent to use DSO (Disulphide Oil) as anti coking additive in gas crackers. Also, it is an ideal replacement for DMDS used in HTs for presulphiding. Otherwise, the best option is to send the stream into HTs (normally VGO HT) with due care on sodium ingress typically seen with DSO disposal. The patent which I talked about earlier takes care of this aspect as well.
27/05/2020 A: Ralph Ragsdale, Ragsdale Refining Courses, ralph.ragsdale@att.net
Naphtha hydrotreater feed storage tank.