System and method for reducing emissions from a boiler

Abstract

A system and method for reducing emissions from a boiler. A boiler generally has a combustion area. The system further includes a fuel pipe for delivering fuel. The system further includes a conduit. A bore extends through the conduit. The bore of the conduit is in fluid communication with the fuel pipe and the combustion area of the boiler. A pre-ignition source is positioned in the conduit. The pre-ignition source operates to pre-ignite at least a portion of the fuel flowing through the conduit.

1 . A system for reducing emissions in a boiler having a combustion area, comprising:
 a fuel pipe operable to deliver fuel;   a conduit having a bore extending there through, the bore being in fluid communication with the fuel pipe and the combustion area of the boiler; and   a pre-ignition source positioned in the conduit and operable to pre-ignite at least a portion of the fuel flowing through the conduit.   
     
     
         2 . The system of  claim 1 , wherein the fuel comprises carbonaceous fuel. 
     
     
         3 . The system of  claim 2 , wherein the fuel comprises pulverized coal. 
     
     
         4 . The system of  claim 3 , wherein the pre-ignition source continually pre-ignites at least a portion of the fuel flowing through the conduit during regular operation of the boiler 
     
     
         5 . The system of  claim 4 , wherein the ignition source operates throughout a boiler load range. 
     
     
         6 . The system of  claim 1 , further comprising:
 a first pre-ignition conduit defining a first bore extending there through, the first pre-ignition conduit being disposed in the bore of the conduit, the pre-ignition source being positioned in the bore of the first pre-ignition conduit;   wherein at least a portion of the fuel flowing through the conduit is entrained in the bore of the first pre-ignition conduit.   
     
     
         7 . The system of  claim 6 , further comprising:
 a second pre-ignition conduit defining a second bore extending there through, the second pre-ignition conduit being disposed in the bore of the conduit,   wherein at least a portion of the fuel flowing through the conduit is entrained in the bore of the second pre-ignition conduit.   
     
     
         8 . The system of  claim 6 , further comprising:
 a third pre-ignition conduit defining a third bore extending there through, the third pre-ignition conduit being disposed in the bore of the conduit;   wherein at least a portion of the fuel flowing through the conduit is entrained in the bore of the third pre-ignition conduit.   
     
     
         9 . The system of  claim 3 , wherein between 10% and 50% of the fuel flowing through the conduit is pre-ignited in the conduit. 
     
     
         10 . The system of  claim 3 , wherein at least a portion of the fuel flowing through the conduit is pre-ignited under substoichiometric conditions. 
     
     
         11 . The system of  claim 10 , wherein ratio of air to fuel is between 0.1 and 0.4. 
     
     
         12 . A method for reducing emissions in a boiler having a combustion area, comprising the steps of:
 providing a fuel pipe operable to deliver fuel;   providing a conduit having a bore extending there through, the bore being in fluid communication with the fuel pipe and the combustion area of the boiler;   providing a pre-ignition source positioned in the conduit,   delivering fuel from the fuel pipe to the combustion area of the boiler through the conduit;   pre-igniting at least a portion of the fuel flowing through the conduit.   
     
     
         13 . The method of  claim 12 , further comprising the step of:
 operating the pre-ignition source to pre-ignite fuel throughout a boiler load range.   
     
     
         14 . A method for reducing emissions in a boiler having a first fuel elevation and a second fuel elevation, each of the first fuel elevation and second fuel elevation comprising a nozzle operable to deliver fuel to a combustion area of the boiler, comprising the steps of:
 delivering fuel to the combustion zone of the boiler through the nozzles associated with the first fuel elevation and the second fuel elevation;   pre-igniting at least a portion of the fuel delivered through the nozzles associated with the first fuel elevation and the second fuel elevation prior to delivering the fuel through the nozzles associated with the first fuel elevation and the second fuel elevation.   
     
     
         15 . The method of  claim 14 , wherein each nozzle is in fluid communication with a conduit,
 wherein fuel delivered through the nozzles associated with the first fuel elevation and the second fuel elevation flows through the conduit before it flows through the nozzles associated with the first fuel elevation and the second fuel elevation, and   wherein the fuel is pre-ignited in the conduit.   
     
     
         16 . The method of  claim 15 , wherein the pre-ignition of fuel continues during regular operation of the boiler.