Staged air, low NOX burner with internal recuperative flue gas recirculation

摘要

A gas-fired burner incorporating an air driven jet pump for mixing air, fuel, and recirculated flue gas with reduced heat loss from the recirculated flue gas is disclosed. The burner is configured for the staged introduction of combustion air to provide a fuel-rich combustion zone and a fuel-lean combustion zone. Internal flue gas channels deliver cooled flue gas to the primary fuel-rich combustion zone. A valve assembly may be provided to control the flow of flue gas. Secondary air channels concentrically arranged within the flue gas channels deliver superheated, staged air to the secondary fuel-lean combustion zone. Heat is transferred from the hot flue gas to the counterflowing cooler secondary air. The burner achieves reduced NO.sub.x emission levels in high temperature applications which use preheated combustion air with no or minimal loss in thermal efficiency from flue gas recirculation.