Pyrophoric Iron Sulfide in Caustic Tower

“Can pyrophoric iron sulfide form in a caustic tower”?  A survey of AIChE Ethylene Producer’s Conference Proceedings did not reveal any reports of iron sulfide concerns with respect to the caustic tower area, but a more extensive inquiry found that at least two ethylene plants have experienced issues with pyrophoric iron sulfide in the caustic tower. A study of research literature shows that the caustic tower environment is amenable to the formation of pyrophoric iron sulfide. The internal structure of the caustic tower and preliminary decontamination actions are determining factors in the level of concern for pyrophoric fires during turnaround.