Abstract: As one of the key equipment of hydrogenation unit, the heat exchanger for heat high-pressure separation gas/mixed hydrogen has been in high temperature, high pressure and various corrosive environments for a long time. This heat exchanger has been repeatedly blocked by ammonium salt or under-deposit corrosion, resulting in unplanned shutdown of the unit. In this paper, the ammonium salt under-deposit corrosion and chloride stress corrosion of the heat exchanger (E1105) for heat high-pressure separation gas/mixed hydrogen unit containing high H₂S content were analyzed in detail. The material selection of the heat exchanger in this corrosive environment was studied, and the specific material technical requirements and corrosion test requirements were put forward.

Key words: ammonium salt crystallization, under-deposit corrosion, study on material selection, hydrogenation unit