Upgrading coal and other carbonaceous fuels using a lean fuel gas stream from a pyrolysis step

摘要

A method for upgrading coal and other carbonaceous fuels includes subjecting the carbonaceous fuel to a pyrolyzing process, thereby forming upgraded carbonaceous fuel and a flow of lean fuel gases. Auxiliary fuel is combusted in an auxiliary fuel combustor to produce auxiliary fuel combustion gases, and the lean fuel gases are heated with the auxiliary fuel combustion gases. The heated lean fuel gases are combusted in a lean fuel combustor, thereby producing a gas stream of products of combustion, and at least a portion of the gas stream of products of combustion are directed to the pyrolyzer.

主权项

1. A method of upgrading coal and other carbonaceous fuels comprising:
subjecting the carbonaceous fuel to a pyrolyzing process, thereby forming upgraded carbonaceous fuel and a flow of lean fuel gases; directing the flow of lean fuel gases and a flow of primary combustion air into a lean fuel combustor; combusting the lean fuel gases in the lean fuel combustor, thereby producing a gas stream of products of combustion; introducing at least a portion of the gas stream into the flow of primary combustion air; and directing the remainder of the gas stream to the pyrolyzer, wherein at least about 60% of the heat provided to the pyrolyzer is provided by the combustion of the lean fuel gases from the pyrolyzer, with the remainder of the heat being provided by an auxiliary fuel combustor; wherein the temperature of the lean fuel gases being introduced into the lean fuel combustor is controlled to be above the ignition temperature of an air-fuel mixture in the lean fuel combustor.