Hot Corrosion/erosion Testing of Materials for Application to Advanced Power Conversion Systems Using Coal-derived Fuels

Book excerpt: Pressurized fluidized bed combustion offers a potentially efficient technique for energy production by combusting coal in an environmentally acceptable manner. This program entails the operation of the Exxon Pressurized Fluidized Bed Coal Combustion Miniplant to provide a test site for the exposure of specimens of potential fireside heat exchanger alloys and gas turbine materials. The installation and shakedown phase of this program has been completed. Heat exchanger specimen probes and turbine blade materials were exposed to pressurized fluidized bed coal combustion conditions for tests of 17 hours and 100 hours. Temperature control of the 21 heat exchanger probes was excellent, and the probe specimens showed no visible signs of attack after 117 hours of exposure. With the aid of 4 methane injection nozzles in the off gas piping, the temperature at the turbine test section was maintained at 1550°F. During the shakedown tests the flue gas flow decreased to a lower level than intended because of refractory plugs in the pressure reducing station. Temperature at the turbine test section had to be lowered during the run to maintain 9 atm pressure in the combustor. This was accomplished by ceasing methane injection and eventually lowering the combustor temperature. The airfoil-shaped turbine specimens experienced a regular pattern of fly ash deposition.