Patent ID: 9091441
Filing Date: 2015-07-28
Classification: F23D,F23L,Y02E

Abstract:
1. A method of modifying operation of a burner, comprising (A) providing a burner having at least two concentric conduits, wherein a stream of air mixed with particulate solid carbonaceous fuel can be conveyed through an innermost conduit of said burner, and wherein one or more streams of air other than the air mixed with said fuel can be conveyed through a central conduit surrounding the innermost conduit, and wherein said fuel and air can be combusted in a stable flame at said burner, (B) determining the maximum air-to-fuel mass ratio of the stream of air mixed with fuel that is fed through said burner above which combustion of said fuel with air as the only source of oxygen for said combustion cannot be maintained in a stable flame at said burner, (C) inserting through said burner a lance the outlet end of which is positioned to eject gas into the base of a flame at said burner and the inlet end of which is connected to a source of gaseous oxidant comprising more than 21 vol. % oxygen, (D) feeding through said innermost conduit a stream of air mixed with said particulate solid fuel at an air-to-fuel ratio above said maximum, and feeding through said central conduit said one or more streams of air other than the air mixed with said fuel, (E) feeding gaseous oxidant comprising more than 21 vol. % oxygen through the outlet end of said lance, and (F) combusting said fuel and air fed in step (D) with said oxidant fed in step (E) in a stable flame at said burner, wherein said oxidant is fed into the base of said flame at a mass flow rate that maintains said stable flame.