US Patent 7104787 Apparatus for radiant tube exhaust gas entrainment

A radiant tube burner system comprises a novel flue gas recirculating assembly for reducing nitrous oxides emissions. In the burner system, the combustion air conduit running to the radiant tube burner intersects the exhaust conduit at a location between the radiant tube and the eventual exhaust outlet. A venturi is formed at this intersection. The venturi is configured to suction a portion of the flue gas from the exhaust conduit into the combustion air flow. The assembly includes a may be interposed along the exhaust conduit mounted directly between the radiant tube and a downstream section of the exhaust conduit.