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

摘要

A gas-fired burner 10 incorporating a mixing chamber 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 recirculating flue gas channels 80 deliver cooled flue gas to the primary fuel-rich combustion zone. A valve assembly 150 may be provided to control the flow of flue gas. Secondary air passages 40 concentrically arranged within the recirculating flue gas channels 80 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 NOx emission levels in high temperature applications which use preheated combustion air with no or minimal loss in thermal efficiency from flue gas recirculation. IMAGE