Claims
- 1. Burner apparatus for controlled low NO.sub.x combustion, comprising first and second combustion zones, each filled with a porous high temperature resistant matrix, the void spaces of which provide sites at which substantially all of said combustion occurs, said second zone being downstream of said first zone; means for mixing fuel and a gaseous source of oxygen and providing the resultant combustible mixture to the input end of said first combustion zone to establish fuel-lean conditions therein; and means for feeding the combustion products from said first zone to said second zone and augmenting same with further oxygen and sufficient additional fuel to create fuel-rich burning conditions therein to complete the oxidation of the products from said first zone; and cooling means mounted in proximity to said input end of said first combustion zone, for maintaining the temperature of said combustible mixture at said input end below ignition temperature thereby limiting the flame produced by combustion in said porous matrix to the downstream side of said cooling means, said means being mounted to be non-intrusive with respect to the interior of said porous matrix, thereby presenting no interference with the flow of said combustible mixture through said matrix.
- 2. Burner apparatus in accordance with claim 1, wherein said cooling means comprises a generally toroidal hollow metal body surrounding and in thermal contact with the input end of said combustion zone, and means to circulate a coolant through said tube.
- 3. Apparatus in accordance with claim 2, wherein said coolant is water.
- 4. Apparatus in accordance with claim 2, wherein said coolant is air.
- 5. A combustion process for controlled low NO.sub.x combustion, comprising:
- flowing a combustible mixture of fuel and oxidant through two porous ceramic matrices arranged in series, the first of said matrices being an initial combustion zone for said gaseous mixture, and providing cooling to said mixture as it flows into the surface of said first matrix to maintain the mixture temperature at the said surface below the ignition temperature thereof, to preclude upstream flame-back from said first matrix, said cooling being effected by thermally contacting the input end of said first combustion zone with a cooling means which is mounted to be non-intrusive with respect to the interior of said porous matrix, thereby presenting no interference with the flow of said combustible mixture through said matrix, the combustion in said first matrix being under fuel-lean oxidizing conditions; and additional fuel and oxidant being added to the flow of combustion products from said first matrix to enable combustion in said second matrix under fuel-rich conditions.
- 6. Burner apparatus for controlled low NO.sub.x combustion, comprising first and second combustion zones, each being laterally bound by non-porous walls and being filled with a porous high temperature resistant matrix, the void spaces of which provide sites at which substantially all of said combustion occurs, said second zone being downstream of said first zone; means for mixing fuel and a gaseous source of oxygen and providing the resultant combustible mixture to the input end of said first combustion zone to establish fuel-lean conditions therein; and means for feeding the combustion products from said first zone to said second zone and augmenting same with further oxygen and sufficient additional fuel to create fuel-rich burning conditions therein to complete the oxidation of the products from said first zone; heat transfer by convection and radiation within the porous matrix element of said first zone preheating the incoming combustible mixture to yield a flame temperature which is higher than the theoretical adiabatic flame temperature for said mixture, thereby allowing a broader range of fuel/oxygen source mixtures to be combusted under fuel lean conditions, and heat transfer by radiation from the non-porous walls of said second zone resulting in an overall lower flame temperature for said second zone operating in said fuel-rich condition, and thereby minimizing the formation of thermal and prompt NO.sub.x.
RELATED APPLICATION
This application is a continuation-in-part of copending application Ser. No. 554,748, filed Jul. 18, 1990, abandoned, and of Ser. No. 670,286 filed Mar. 15, 1991.
US Referenced Citations (3)
Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
554748 |
Jul 1990 |
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