Metallic Heat Exchangers for Coal Gasification

摘要

A high-temperature corrosion program is being conducted to evaluate the corrosion behavior of selected metallic alloys and coatings in mixed-gas atmospheres for application in heat recovery systems of coal gasification schemes. The experiments conducted with internally air-cooled specimens have established three key variables, namely the gas temperature, metal temperature, and gas chemistry. In addition, the alloy chemistry and exposure time have a strong influence on the corrosion scale morphologies and metal recession rates. The results showed that the scale growth in carbon steel and low- to medium-chromium steels is predominantly linear with time. Selection of these materials will be primarily based upon acceptable corrosion wastage rate. On the other hand, high-chromium alloys can develop thin oxide scales resulting in negligible wastage via corrosion, but are susceptible to accelerated corrosion in mixed-gas atmospheres. 6 references, 12 figures, 4 tables. (ERA citation 09:045307)