Abstract: An apparatus for introducing a high volume, low concentration non-condensable gas, which may contain sulfur into a chemical recovery steam generator furnace comprising: a plurality of gas inlet pipes, each gas inlet pipe having a source end and a nozzle end, in which the source end of the pipe is connected to a source of said high volume, low concentration non-condensable gas and the nozzle end of the pipe, which comprises a nozzle, vents to said chemical recovery steam generator furnace; a preheater positioned in close proximity to said pipe and upstream of said nozzle; a secondary air port with a source end and a furnace end, in which the source end of said port is connected to a source of such secondary air and the furnace end of said port vents to said chemical recovery steam generator furnace; wherein the area enclosed by said secondary air port is greater than the area of said nozzle and wherein said nozzle is positioned within the area enclosed by said secondary air port such that said pipe and said po

Abstract: An apparatus and method whereby fuel is burned in serially connected furnaces under controlled combustion temperature and airflow conditions so as to inhibit the formation of nitric oxides while achieving complete combustion of the fuel.