Additional comments from Chris Dean…..
Thanks Hedewandro for a very good question,
As previously mention the amount of COS produced is based on the feedstock. With only amine treatment for the LPG stream and/or PP Stream, it is difficult to reduce COS levels significantly or even at all. This could be confirmed by a SRU SME or from an amine supplier or treating licensor. To reduce COS significantly, catalytic treatment beds are used to produce polymer grade propylene as feedstock to polypropylene units.
You mention in the question that Coker LPG is sent to a propylene unit. Is this unit a PP splitter or does it have other treating facilities to produce polymer grade propylene? Most refineries will produce refinery grade propylene and some depending on location will produce chemical grade.
Just for information the typical COS spec is 0.5-1ppm for polymer grade propylene. Chemical and Refinery grades are negotiable due to the customer but COS does affect total sulfur.
Hope this helps