Patent ID: 7175423

Claim:
A method of reducing NOx emissions from a burner comprising the steps of: (a) injecting fuel from a fuel source into a burner throat via a fuel passageway; (b) injecting primary air from an ambient air source through a single connection into a primary combustion region located in the burner throat, the ratio of fuel to primary air being such as to create a fuel rich mixture of fuel and primary air; (c) inducing a swirling effect upon the mixture of fuel and primary air in the burner throat; (d) combusting the mixture of fuel and primary air; (e) passing the swirling mixture of fuel and primary air to a port block wherein, due to Coanda effect, at least part of the mixture of fuel and primary air remains adjacent a dish surface in the port block; (f) injecting secondary air from the same ambient air source as said primary air and through said single connection into a secondary combustion region located downstream from the primary combustion region in an amount at least sufficient to complete the combustion of the fuel; wherein the secondary air is injected through at least one secondary air jet diverging with respect to a centerline extending through the burner throat and wherein the air split ratio of primary air to secondary air is within the range 40/60 to 75/25; and further wherein an angle of divergence of the at least one secondary air jet is from about 15° to about 50°, and is less than an angle of divergence of said dish surface; (g) drawing products of combustion into a vortex created by the swirling mixture of fuel and air during the combustion process, thereby reducing NOx produced in the combustion process.