METHOD AND APPARATUS FOR A DUAL MODE BURNER YIELDING LOW NOx EMISSION

Abstract

A method and apparatus for a burner adapted to heat a furnace or other environment of use. In particular, a burner for providing a fuel gas in combination with an oxidant to effect controlled reaction of the fuel gas in a manner to reduce NOx emissions is described. Combustion of the fuel gas is shifted from the burner combustor to a location outside the burner once the temperature within the furnace/radiant tube has reached a sufficient level to complete combustion of the fuel gas.

What is claimed is: 
     
         1 . A method of operating a burner comprising:
 providing a burner including a combustion chamber, a combustor outlet, a movable fuel tube, and a fuel tube movement device coupled to the movable fuel tube;   supplying the burner with fuel and oxidant, the fuel being supplied such that the fuel enters the movable fuel tube;   igniting the fuel and oxidant mixture in the combustion chamber;   heating a space exterior to the combustion chamber to a temperature at or above an auto-ignition temperature of a mixture of the fuel and oxidant; and   activating the fuel tube movement device to move the movable fuel tube in a direction toward the combustor outlet to extinguish the flame in the combustion chamber such that combustion occurs in the space exterior to the combustion chamber in the absence of a flame in the combustion chamber.   
     
     
         2 . The method of  claim 1  wherein the movable fuel tube includes a first end and a second end, the first end being disposed near the combustion chamber. 
     
     
         3 . The method of  claim 2  wherein the fuel tube movement device is coupled to the movable fuel tube near the first end. 
     
     
         4 . The method of  claim 2  wherein the fuel tube movement device is coupled to the movable fuel tube near the second end. 
     
     
         5 . The method of  claim 1  further comprising a fixed fuel tube fixedly mounted within the burner, the movable fuel tube being at least partially disposed within the fixed fuel tube, the movable fuel tube being movable with respect to the fixed fuel tube. 
     
     
         6 . The method of  claim 5  further comprising a collar disposed between the fixed fuel tube and the movable fuel tube. 
     
     
         7 . The method of  claim 1  wherein the burner includes a nozzle assembly disposed near the combustion chamber. 
     
     
         8 . The method of  claim 7  wherein the nozzle assembly includes an opening for receiving a portion of the fuel tube movement device. 
     
     
         9 . The method of  claim 1  wherein the fuel tube movement device is an electrical device. 
     
     
         10 . The method of  claim 1  wherein the fuel tube movement device is a pneumatic device. 
     
     
         11 . A burner comprising:
 a combustion chamber terminating at a combustor outlet;   a movable fuel tube, the movable fuel tube including a first end disposed near the combustion chamber; and   a fuel tube movement device coupled to the movable fuel tube for moving the fuel tube toward and away from the combustor outlet.   
     
     
         12 . The burner of  claim 11  wherein the fuel tube movement device is coupled to the movable fuel tube near the first end. 
     
     
         13 . The burner of  claim 11  wherein the movable fuel tube includes a second end, and the fuel tube movement device is coupled to the movable fuel tube near the second end. 
     
     
         14 . The burner of  claim 11  further comprising a fixed fuel tube fixedly mounted within the burner, the movable fuel tube being at least partially disposed within the fixed fuel tube, the movable fuel tube being movable with respect to the fixed fuel tube. 
     
     
         15 . The burner of  claim 14  further comprising a collar disposed between the fixed fuel tube and the movable fuel tube. 
     
     
         16 . The burner of  claim 11  further comprising a nozzle assembly disposed near the combustion chamber. 
     
     
         17 . The burner of  claim 16  wherein the nozzle assembly includes an opening for receiving a portion of the fuel tube movement device. 
     
     
         18 . The burner of  claim 11  wherein the fuel tube movement device is an electrical device. 
     
     
         19 . The burner of  claim 11  wherein the fuel tube movement device is a pneumatic device. 
     
     
         20 . The burner of  claim 11  further comprising a sensor for detecting the presence of a flame in the combustion chamber.