WATER EFFECT ON STEEL UNDER SUPERCRITICAL CO_2 CONDITION

摘要

Rotated cage corrosion experiments (4 m/s) were performed with flat coupons of 2 carbon steels (38Mn6/C75, X65) and 3 Cr-containing steels (X20Crl3, X2CrNiMoN22-5-3 (1.4462) and XINiCrMoCu 25-20-5 (1.4539)) in the presence of supercritical carbon dioxide (scCO_2) and different amounts of water at 50, 80, 110 and 130°C. While water-free scCO_2 is non-corrosive for C-and Cr-containing steels, water mist saturated with SCCO_2 was corrosive for C-steels, however not for 13Cr or CrNi steels even up to 130°C. Droplets of water mist, saturated with scCO_2, caused localized attack when touching the C-steel surface. Water phases saturated with scCO_2 were very corrosive for C-steels in the whole range of 50 to 130°C (corrosion rates 5-15 mm/y and mesa-type localized attack). Under such conditions also the resistance of 13Cr steel was not acceptable (corrosion rates 0.3 to 0.8 mm/y). Even the austenitic-ferritic (1.4462) and the austenitic CrNi steel (1.4539) surpassed the target line of 0.1 mm/y at 110°C when contacted with water saturated with scCO_2.