I'm plant engineer at a sour gas plant. It uses mole sieves to dry the gas. The regeneration gas heater for the mole sieve unit is experiencing a build up of iron sulphide materials -specifically Troilite, Greigite, and Pyrrhotite which are corrosion products - on the process side of the heater. The heater ran fan fine for about 30 years. Subsequentlly after a new gas stream entered the plant this heater experienced high skin temperatures and the above mentioned corrosion products were found on the inside of the tubes. The new gas has been analyzed several times onsite for trace sulphur and found to be very high in COS - about 250 ppm. I've found literature that says COS is corrosive - but so far only in flue gases and on copper. So - I'm looking for literature on non flue gas corrosion of steel by COS in a high temperature (say 300 C) in the absence of water. This might be too specific but any pointers would be of help.

I cannot give you tech papers on COS. But I know that calorised tubes are your only answer to corrosion.