LOW NOx EMISSION BURNER FOR FIRING LIQUID FUELS AND METHOD OF OPERATION

Abstract

A liquid fuel or hybrid fuel burner and method of operating the burner are described. The combustion air and/or NOx reducing medium are introduced at more than one location in the burner. A portion of the combustion air and the NOx reducing medium can be injected into the primary combustion zone through the NOx reducing medium conduit which surrounds the liquid fuel injector which injects atomized liquid fuel into the primary combustion zone. Another portion of the combustion air and the NOx reducing medium can be introduced into the primary combustion zone through a passage in the burner tile surrounding the NOx reducing medium conduit.

What is claimed is: 
     
         1 . A liquid fuel or hybrid fuel burner comprising: 
 a plenum having a combustion air inlet and a NOx reducing medium inlet;   a burner tile connected to the plenum, the burner tile forming a primary combustion zone;   a NOx reducing medium conduit positioned in the plenum, the NOx reducing medium conduit comprising a NOx reducing medium conduit inlet and a NOx reducing medium conduit outlet, the NOx reducing medium conduit outlet positioned in the primary combustion zone;   a liquid fuel injector positioned in the NOx reducing medium conduit, the liquid fuel injector comprising an inlet and an outlet, the outlet positioned in the primary combustion zone;   a passage through the burner tile from the plenum to the primary combustion zone for combustion air and NOx reducing medium; and   a primary fuel gas conduit comprising a primary fuel gas inlet and a primary fuel gas outlet, the primary fuel gas outlet positioned in the primary combustion zone.   
     
     
         2 . The burner of  claim 1  wherein NOx reducing medium conduit further comprises a combustion air inlet located in the plenum. 
     
     
         3 . The burner of  claim 1  further comprising: 
 a secondary fuel gas conduit comprising a secondary fuel gas inlet and a secondary fuel gas outlet, the secondary fuel gas outlet positioned outside the burner tile. 
 
     
     
         4 . The burner of  claim 3  wherein the secondary fuel gas conduit is connected to the primary fuel gas conduit.  
     
     
         5 . The burner of  claim 1  wherein the NOx reducing medium conduit and the liquid fuel injector are in a concentric arrangement. 
     
     
         6 . The burner of  claim 1  further comprising a flame stabilization device in the primary combustion zone. 
     
     
         7 . The burner of  claim 6  wherein the flame stabilization device comprises an oil tile, a flame diffuser, a flame holder, a bluff body, or combinations thereof. 
     
     
         8 . The burner of  claim 1  wherein the passage through the burner tile surrounds the NOx reducing medium conduit.  
     
     
         9 . The burner of  claim 1  wherein the passage through the burner tile and the NOx reducing medium conduit are in a concentric arrangement.  
     
     
         10 . A method of reducing production of NOx gases at a burner comprising: 
 injecting a liquid fuel and an atomizing medium from a liquid fuel injector into a primary combustion zone defined by a burner tile forming an atomized liquid fuel;    injecting a first portion of NOx reducing medium into the primary combustion zone from a NOx reducing medium conduit surrounding the liquid fuel injector; and   injecting combustion air and a second portion of NOx reducing medium into the primary combustion zone through a passage in the burner tile, whereby the combustion air and the atomized liquid fuel react and produce a flame in the primary combustion zone.   
     
     
         11 . The method of  claim 10  further comprising: 
 passing a first portion of the combustion air into the NOx reducing medium conduit; and  
 wherein injecting the first portion of the NOx reducing medium into the primary combustion zone comprises injecting the first portion of the NOx reducing medium and the first portion of the combustion air into the primary combustion zone. 
 
     
     
         12 . The method of  claim 10  further comprising; 
       injecting primary fuel gas through a primary fuel gas outlet into the primary combustion zone wherein the combustion air and the primary fuel gas react and produce a flame inside the primary combustion zone. 
     
     
         13 . The method of  claim 10  further comprising; 
       injecting secondary fuel gas through a secondary fuel gas outlet into an area outside the burner tile wherein the combustion air from the passage and the secondary fuel gas react and produce a flame outside the primary combustion zone. 
     
     
         14 . The method of  claim 10  wherein the atomizing medium comprises steam, air, nitrogen, fuel gas, or combinations thereof. 
     
     
         15 . The method of  claim 10  further comprising;  
       stabilizing the flame with a flame stabilization device in the primary combustion zone. 
     
     
         16 . The method of  claim 15  wherein the flame stabilization device comprises an oil tile, a flame diffuser, a flame holder, a bluff body, or combinations thereof. 
     
     
         17 . The method of  claim 10  wherein injecting the combustion air and the second portion of NOx reducing medium into the primary combustion zone through the passage in the burner tile comprises introducing the combustion air and the second portion of NOx reducing medium into a plenum connected to the burner tile and wherein the combustion air and the second portion of NOx reducing medium pass from the plenum through the passage in the burner tile to the primary combustion zone. 
     
     
         18 . The method of  claim 10  wherein the passage in the burner tile surrounds the NOx reducing medium conduit. 
     
     
         19 . The method of  claim 10  wherein the first portion of NOx reducing medium, or the second portion of NOx reducing medium, or both comprise: flue gas from a combustion zone; flue gas from the exhaust of a heater, a boiler, or a furnace; steam; nitrogen; carbon dioxide; or combinations thereof. 
     
     
         20 . The method of  claim 10  further comprising: 
 monitoring at least one NOx value for the flame; and  
 adjusting a flowrate of the first portion of NOx reducing medium, the second portion of NOx reducing medium, or both based on the at least one NOx value.