Metallic Components in Coal-Gasification Fuel Gas Paths

Gasification systems offer the potential to generate electricity from coal much more efficiently and with substantially less environmental impact (i.e. lower CO2, SOx, NOx and particulate emissions) than conventional pulverised fuel combustion systems. There is a wide variety of gasification processes and fuel gas path options that continue to be investigated. However, the hot fuel gas path environments produced by all these gasification systems have the potential to be extremely aggressive for materials during plant operation and downtime periods. This paper reports on a series of tests carried out to investigate the performance of candidate materials for two types of component in hot fuel gas path environments i.e. the fuel gas cooler and metallic filter elements. One series of laboratory tests was carried out for up to 3000 hours at temperatures in the range 450-550 deg C in which materials were exposed to gases that simulate both oxygen and air-blown gasification systems. The materials in these tests were exposed both bare and with a coverage of the appropriate deposit for the type of gasification system. A second series of test was carried out to investigate the downtime corrosion behaviour of candidate heat-exchanger materials in which materials covered with a deposit were exposed to humid atmospheres. [This is an unrefereed preprint].