Abstract: A method for burning a fuel, containing chemically bound nitrogen, in a two-stage, rich-lean combustion process, including; introducing the fuel and at least one stream of primary air into a primary combustion region at a fuel-air ratio above the stoichiometric ratio and in a manner to intimately mix the fuel and air and establish a stabilized flame adjacent the upstream end of the primary combustion region, maintaining the flame in the primary combustion region for a period of time sufficient to produce a combustion product mixture containing less than a predetermined amount of NO.sub.x pollutants and abruptly terminating the primary combustion region while introducing at least one stream of secondary air into the secondary region in an amount sufficient to reduce the overall fuel-air ratio below the stoichiometric ratio and in a manner to prevent backflow of the secondary air into the primary combustion region.

Abstract: A method for burning a fuel, containing chemically bound nitrogen, in a two-stage, rich-lean combustion process, including: introducing the fuel and at least one stream of primary air into a primary combustion region at a fuel-air ratio above the stoichiometric ratio and in a manner to intimately mix the fuel and air and establish a stabilized flame adjacent the upstream end of the primary combustion region, maintaining the flame in the primary combustion region for a period of time sufficient to produce a combustion product mixture containing less than a predetermined amount of NO.sub.x pollutants and abruptly terminating the primary combustion region while introducing at least one stream of secondary air into the secondary region in an amount sufficient to reduce the overall fuel-air ratio below the stoichiometric ratio and in a manner to prevent backflow of the secondary air into the primary combustion region.

Abstract: A method for burning a fuel, containing chemically bound nitrogen, in a two-stage, rich-lean combustion process, including; introducing the fuel and at least one stream of primary air into a primary combustion region at a fuel-air ratio above the stoichiometric ratio and in a manner to intimately mix the fuel and air and establish a stabilized flame adjacent the upstream end of the primary combustion region, maintaining the flame in the primary combustion region for a period of time sufficient to produce a combustion product mixture containing less than a predetermined amount of NO.sub.x pollutants and abruptly terminating the primary combustion region while introducing at least one stream of secondary air into the secondary region in an amount sufficient to reduce the overall fuel-air ratio below the stoichiometric ratio and in a manner to prevent backflow of the secondary air into the primary combustion region.

Abstract: New combustors which produce lower emissions, particularly lower emissions of nitrogen oxides and CO, are provided. The combustors are provided with a first combustion region that is cylindrical, short and of small diameter and an adjacent downstream second combustion region comprising an abrupt enlargement in diameter to provide a relatively larger capacity than the first combustion region. A first stream of air is introduced, either radially, axially, or tangentially, into the first combustion region and the amount of said air is varied in accordance with fuel flow to the first combustion region. A second stream of air is introduced tangentially into the first combustion region. A third stream of air is introduced tangentially into the second combustion region. In preferred embodiments of the invention the air stream pressure drop across an air assist fuel nozzle is varied in accordance with fuel flow to the nozzle.

Abstract: New combustors which produce lower emissions, particularly lower emissions of nitrogen oxides and CO, are provided. The combustors are provided with a first combustion region that is cylindrical, short and of small diameter and an adjacent downstream second combustion region comprising an abrupt enlargement in diameter to provide a relatively larger capacity than the first combustion region. A first stream of air is introduced, either radially, axially, or tangentially, into the first combustion region and the amount of said air is varied in accordance with fuel flow to the first combustion region. A second stream of air is introduced tangentially into the first combustion region. A third stream of air is introduced tangentially into the second combustion region. In preferred embodiments of the invention the air stream pressure drop across an air assist fuel nozzle is varied in accordance with fuel flow to the nozzle.

Abstract: A combustor is provided having a variable dome valve on the upstream end of the flame tube thereof for controlling admission of a stream of combustion air to said flame tube.

Abstract: A variable valve is provided for mounting on the end of a tubular conduit for controlling fluid flow through said conduit. Said valve is particularly well adapted to be employed as a dome valve on the upstream end of a flame tube of a combustor for controlling admission of a stream of combustion air to said flame tube.

Abstract: New combustors, and methods of operating same, which produce lower emissions, particularly lower emissions of nitrogen oxides.