Patent ID: 6951454
Filing Date: 2005-10-04
Classification: F23D

Abstract:
1. In combination with the boundary wall of a boiler furnace, a combustion zone established within the furnace, at least one burner port formed in the boundary wall and fronting the combustion zone, a dual fuel burner facing the combustion zone through the burner port, and comprising: an elongated supply pipe having an inlet end and an outlet end, and defining a conduit for conveying natural gas therethrough; an injector connected to the outlet end of the supply pipe, the injector having a chamber communicating with the conduit, the chamber having a longitudinal axis and an end wall, wherein the diameter of the injector along the longitudinal axis prior to the end wall is substantially the same as the diameter of the elongated supply pipe; a plurality of peripheral flow directing openings extending through the end wall in a circumferentially spaced array about the chamber axis, each opening having a longitudinal axis inclined at a first acute angle greater than zero with respect to the chamber axis, and each being further inclined, in a direction toward an adjacent peripheral opening, at a second acute angle greater than zero for inducing swirling motion to the natural gas being injected into the combustion zone; a first sleeve member concentrically spaced about the supply pipe and the injector to form an inner annular passageway for conveying a mixture of primary air and pulverized coal separately from the natural gas and into the combustion zone; a swirler connected to the outlet end of the supply pipe, the swirler having a plurality of vanes positioned upstream of the injector; a second sleeve member concentrically spaced about the first sleeve member to form an outer annular passageway for conveying secondary air to the combustion zone; and a plurality of circumferentially spaced vanes mounted within the outer annular passageway for inducing swirling motion to the secondary air discharging from the outer annular passageway into the combustion zone.