Crude

Norman – Can crude LPG contain RSH or are mercaptans only found in cracked materials. Our crude has a lot of H₂S, but can it have RSH also?

--Probakar, India

Probakar, RSH exists in virgin materials – often in very high concentrations. If you remove all H₂S, then the RSH can break down in the KOH dryer to form traces of H₂S and cause LPG to fail copper strip corrosion test. Methy mercaptans are easily extracted from LPG with caustic. Do not pay licensing fee to UOP, etc. for NaOH regeneration. This is all open-art and is no longer covered by U.S. patents.

In cracked materials, you may also have COS and disulfides. This is a different problem.

Do you remember when we did our pressure survey on your vacuum tower in a (-25° wind)?

--Norm