Foaming in amine systems has been discussed in many forums and can be a serious problem. The quality of the amine is a key factor in foaming. A common cause of foaming is hydrocarbon carryover into the amine contactor that will aggravate foaming. The lean amine should be 10 deg F hotter than the incoming sour gas to prevent condensing hydrocarbon in the amine contactor. Heat stable salts should be less than 2% to limit corrosion. Corrosion products like iron sulfide will put small particulates into the amine that will stabilize foam. High pressure amine contactors will usually foam before lower pressure contactors using the same lean amine stream.

My preference is to filter 100% of the lean amine stream and have a carbon bed to remove soluble contaminants that treats a minimum of 30% of the amine circulation rate.