Diffusion Coatings for Corrosion-Resistant Components in Coal Gasification Systems

Krishnan, Gopala N. ; Malhotra, Ripudaman ; Alvarez, Esperanza ; Lau, Kai-Hung ; Perez-Mariano, Jordi ; Sanjurjo, Angel

SRI International

关键词: Coal Gasification;    Alloys;    Heat Recovery;    Silicon Nitrides;    Sulfidation;   

DOI  :  10.2172/891454
RP-ID  :  None
RP-ID  :  FC26-03NT41616
RP-ID  :  891454

美国|英语

来源: UNT Digital Library

【 摘 要 】

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 its 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 period, we conducted two 300-hour tests. In the first test, we exposed samples at 900 C under conditions simulating the high-temperature heat recovery unit (HTHRU). The second test was at 370 C, corresponding to the filter units following the HTHRU. The tests were showed the resilience of silicon nitride as a coating component, and the new coating procedures better penetrated the pores in sintered metal filter samples. Finally, we also received samples that were exposed in the Wabash River plant. Unfortunately, all these samples, that were prepared last year, were severely eroded and/or corroded.