| CPC F23C 9/08 (2013.01) [F23C 3/002 (2013.01); F23C 6/042 (2013.01); F23C 7/06 (2013.01); F23C 9/006 (2013.01); F23D 14/24 (2013.01); F23D 14/66 (2013.01); F23L 15/04 (2013.01); F23C 2201/20 (2013.01); F23C 2900/03005 (2013.01); F23C 2900/09002 (2013.01); Y02E 20/34 (2013.01)] | 17 Claims |

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1. A staged recirculating burner, comprising:
a combustion tube including inside and outside helical fins forming opposing spiral pathways for combustion gases and products of combustion;
a combustion nozzle coupled to the combustion tube;
a gas tube running axially into the combustion tube;
a heat exchanger coupled to the combustion tube to heat the combustion gases provided to the combustion tube using the products of combustion from the combustion tube; and
wherein the gas tube runs axially through a central bore of the heat exchanger and into the combustion tube.
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