Low nox multi-fuel burner

Claim 1

A multi-fuel burning apparatus comprising: a first tubular conduit, defining a central passageway, opening in a burner port for discharge and combustion of fuel in a combustion chamber, means for supplying an air-conveyed solid carbonaceous fuel to the first tubular conduit for discharge and combustion in the combustion chamber, a liquid fuel assembly centrally extending within the first tubular conduit for discharge and combustion of a liquid fuel in the combustion chamber, a second tubular conduit concentrically disposed about the first tubular conduit and defining a central annular passageway for discharge and combustion of fuel in the combustion chamber, means for supplying air-conveyed pulverized coal to the central annular passageway, a first sleeve member having a portion thereof concentrically spaced about the second tubular conduit to form an inner annular passageway for delivery and supply of combustion air to the combustion chamber, a second sleeve member having a portion thereof concentrically spaced about the first sleeve member to form an outer annular passageway for delivery and supply of additional combustion air to the combustion chamber, means for separately controlling the amounts of combustion air to the first tubular conduit, the second tubular conduit, the inner annular passageway and the outer annular passageway for low NO x production, and wherein the control of combustion air is such that 5 to 10 percent of stoichiometric air is delivered to the central passageway, 15 to 30 percent to the central annular passageway, 22 to 35 percent to the inner annular passageway, and the remaining combustion air for complete combustion to the outer annular passageway.