Diffusion Coatings for Corrosion-Resistant Components in Coal Gasification Systems Quarterly Technical Progress Report: Number 6 (open access)

Diffusion Coatings for Corrosion-Resistant Components in Coal Gasification Systems Quarterly Technical Progress Report: Number 6

Heat-exchangers, particle filters, turbines, and other components in integrated coal gasification combined cycle system must withstand the highly sulfiding conditions of the high temperature coal gas over an extended period of time. The performance of components degrades significantly with time unless expensive high alloy materials are used. Deposition of a suitable coating on a low cost alloy may improve is resistance to such sulfidation attack and decrease capital and operating costs. The alloys used in the gasifier service include austenitic and ferritic stainless steels, nickel-chromium-iron alloys, and expensive nickel-cobalt alloys. During this reporting period we conducted two exposure tests with coated and uncoated coupons. The first one was aborted after a short period, because of a leak in the pressure regulator of a CO/CO{sub 2}/H{sub 2} gas mixture gas cylinder that was used to prepare the simulated coal gas stream. Nevertheless, this run was very instructive as it showed that during the brief exposure when the concentration of H{sub 2}S increased to 8.6%, even specialty alloys such as HR160 and I800 were badly corroded, yet the sample of a SS405-steel that was coated with Ti/Ta showed no signs of corrosion. After replacing the pressure regulator, a second run was conducted …
Date: March 1, 2005
Creator: Krishnan, Gopala N.; Malhotra, Ripudaman; Alvarez, Esperanza; Lau, Kai-Hung & Sanjurjo, Angel
System: The UNT Digital Library