EFFECT OF GASIFIER ENVIRONMENT ON MATERIALS PERFORMANCE

The main purpose of this paper is to review existing knowledge on meta l alloy behaviour in contact with highly reducing syngas in coal gasif ication plants, presently close to commercialization. A secondary purp ose is to compare laboratory and plant corrosion data. Present commerc ial practice indicates that most metal alloys will be used as heat exc hangers to evaporate steam at 350-450 degrees C. Smaller but significa nt future applications may be superheaters or hot-gas clean-up equipme nt exposed at 500-600 degrees C. The alloys will probably be in contac t with non-equilibrium gases quenched from much higher gasification te mperatures in the range 1000-1500 degrees C. Under these conditions th e formation of chromiarich protective oxide scares is rarely observed. The growth rate of less protective oxide/sulfide scales varies consid erably with temperature, gas composition and alloy composition. For mo st applications, available Fe-Cr-Ni alloys can be found to provide ade quate service life, provided carburization after long exposures can be avoided.