Flame retaining nozzle tip

Abstract

A flame retaining nozzle tip for a burner for a pulverized fuel fired furnace receiving a primary stream of pulverized fuel and primary transport and combustion air for discharge into the combustion zone of the furnace comprises a hollow, open-ended, choke or body having an inlet end of generally polygonal flow cross-section for receiving the stream and an outlet end of generally rounded cross-section for accelerating and discharging the stream into the furnace. The outlet end of the choke has a flow cross-sectional area that is less than that of the inlet end to provide choking action. An elongated center element is mounted in coaxial alignment with a central axis of the choke body extending between the inlet and outlet ends. A plurality of swirl vanes are mounted around the central axis and are angularly disposed relative to the general flow direction with inner edges of the vanes spaced equilaterally around and connected to the central element and outer edges connected to the inside surfaces of the choke body. The vanes cause the stream of primary air and pulverized fuel to rotate rapidly around the central axis as the stream passes through the outlet end.

Dependencies are inferred from the claim text.