Study of the corrosion effect of CO₂stream with SO₂and NO₂on a phosphate coated steel tube

Abstract

To mitigate global warming and climate change, many countries are investing massively on the development of CCS technology, which is assumed to be the key technology to reduce CO2 emissions. CCS technology is comprised of the capture, transport, and storage processes. During the capture process, impurities other than CO2 are inevitably flowed into the CO2 stream. In the present study, corrosion characteristics of a phosphate coated tube for CO2 transportation was investigated with a CO2 stream composed of CO2, H2O, SO2, and NO2. The test specimen was a phosphate coated steel tube, which was filled with CO2 stream with the impurities mentioned above. SEM-EDS analysis is conducted to investigate the corrosion behavior. The results showed that although the H2O concentration did not exceed the solubility limit, corrosion occurred in the specimen, which has an inflow of SO2 or NO2. This suggests that the SO2, NO2 and H2O concentration should be strictly controlled. These results suggest that the SO2 and NO2 concentration should be controlled below 175ppm and 65ppm, respectively.