Increased efficiency of topping cycle PCFB power plants

Pressurized circulating fluidized bed (PCFB) power plants offer the power industry significantly increased efficiencies with reduced costs of electricity and lower emissions. When topping combustion is incorporated in the plant, these advantages are enhanced. In the plant, coal is fed to a pressurized carbonizer that produces a low-Btu fuel gas and char. After passing through a cyclone and ceramic barrier filter to remove gas-entrained particulates and a packed bed of emathelite pellets to remove alkali vapors. the fuel gas is burned in a topping combustor to produce the energy required to drive a gas turbine. The gas turbine drives a generator combustor, and a fluidized bed heat exchanger (FBHE). The carbonizer char is burned in the PCFB and the exhaust gas passes through its own cyclone, ceramic barrier filter, and alkali getter and supports combustion of the fuel gas in the topping combustor. Steam generated in a heat-recovery steam generator (HRSG) downstream of the gas turbine and in the FBHE associated with the PCFB drives the steam turbine generator that furnishes the balance of electric power delivered by the plant