Abstract: A combustion apparatus includes: a combustion device operable to produce flue gas having large particulate ash entrained therein; an outlet duct coupled in flow communication with the combustion device so as to receive the flue gas; a screen positioned at least partially in the outlet duct downstream of the combustion device, the screen effective to trap large particulate ash while permitting flow of the flue gas therethrough; and apparatus operable to remove large particulate ash from the screen while at least a portion of the screen remains inside the duct.

Abstract: A staged-coal injection procedure for coal-fired boilers used in power generation. The procedure includes the steps of combusting a first type of coal in a first zone of a furnace; and combusting a second type of coal in a second zone of the furnace. The second zone is at a position separate from the first zone.

Abstract: The invention provides a method which includes the step of locating a burner of a low NOx boiler that produces a disproportionately high quantity of unburned carbon. The air-to-fuel ratio at the burner is then increased to decrease the percentage of unburned carbon attributable to the burner. The air-to-fuel ratio at a second burner of the low NOx boiler is reduced to maintain a substantially constant total air-to-fuel ratio in the low NOx boiler.

Abstract: A low NOx gas combustor includes an air injection mechanism to create a combustion air path. A set of arc-shaped gas injector arrays are formed in an annular configuration. Each arc-shaped gas injector array injects an arc-shaped stream of gas that intersects with the combustion air path to produce a fuel rich flame segment that is separated from an adjacent fuel rich flame segment from an adjacent arc-shaped gas injector array by an air rich zone. The interaction between the fuel rich flame segment and the air rich zone results in low NOx combustion of the gas.

Abstract: A method to reduce waterwall corrosion in a low NO.sub.x boiler includes the steps of locating a waterwall area of a low NO.sub.x boiler where oxidizing conditions exist and deposition of FeS is likely. The combustion air input at the waterwall area is biased to reduce FeS deposition on the waterwall. The biased combustion air input increases the oxidation rate of FeS.sub.2 so as to reduce FeS deposition on the waterwall. The biased combustion air input may be achieved by increasing the air-to-fuel ratio of one burner while reducing the air-to-fuel ratio of another burner, such that the overall air-to-fuel ratio in the low NO.sub.x boiler is substantially constant.