MATERIALS SELECTION IN HYDROTHERMAL OXIDATION PROCESSES

摘要

Results of a literature and an experience survey on materials selection in subcritical and supercritical water oxidation processes are presented in this paper. Some hydrothermal process environments with moderate pH levels and low levels of reactive halide ions were mild enough to allow the use of AISI 316 and similar stainless alloys. The engineering alloys most commonly utilized in hydrothermal oxidation processes were found to be alloys C-276 and 625. However, the corrosivity in some environments appeared to be beyond the limits of alloys C-276 and 625 and required materials with higher corrosion resistance. Titanium alloys such as Tl-Gr2, Ti-Gr9 and Ti-Grl2 had value in terms of their corrosion resistance under some cases of highly oxidizing conditions. For severe applications, noble metals such as Pt, Pt-Ir and Pt-Rh were used as liners and overlays to minimize corrosive attack. Newer developed alloys such as alloy C-4, C-22, 59, 686 and C-2000 haven't yet been evaluated in hydrothermal oxidation process environments. In addition to materials selection, design innovations were used to minimize conditions for corrosive attack in process equipment.