A two-stage coal-water slurry high-pressure gas turbine combustion system employing a primary zone with a hot refractory wall and an internal slag removal system has been designed, built and tested. The molten ash is removed by aerodynamic means using a form of jet impaction, a method that promises to be more effective than the more conventional cyclonic approaches. The overall combustion system is extremely flexible and can be readily configured to operate either with a lean or a rich reaction (primary) zone. In both cases a lean secondary zone is used.
Results showing emission signatures of a number of coal-water slurry fuels operating with the combustor arranged in a rich primary zone configuration are presented. Petroleum based fuels show emission trends that are very similar to those previously published. Coal-water slurry combustion, however, results in emission signatures that cover only a relatively narrow fuel-air ratio range because of the limited combustion stability. NOx emissions have been obtained that meet EPA regulations for stationary gas turbines.
