Corrosion by Aqueous Piperazine at 40-150 °C in Pilot Testing of CO2 Capture

Corrosion data from two pilot plant activities of CO2 capture are presented. The pilot plant used 5 m (30 wt %) of aqueous piperazine (PZ) and the advanced stripper (PZAS). 316L stainless steel experienced high corrosion at high temperatures, and the corrosion rate showed strong dependence on temperature. The unexpected vulnerability of 316L was due to the uniquely high operating temperature of PZAS. PZ degradation also had an effect on 316L corrosion. 304 stainless steel and 2205 duplex stainless steel performed well at all temperatures and can be good alternative construction materials for PZAS. Fluid velocity played a bigger role in carbon steel corrosion than temperature because carbon steel corrosion in PZ depends on protective siderite films. Stagnant fluid in the sumps allowed for the formation of compact, protective films, while high-velocity flow might inhibit such film formation. Selective dissolution of Ni from Ni-based alloys into PZ occurred in narrow gaps between alloy and washers. Such localized corrosion can make these alloys not ideal at the joints in pipelines.