In-Furnace Reduction Of Nitrogen Oxide By Mixed Fuels Involving A Biomass Derivative

Abstract

A method of reducing nitrogen oxide emissions formed during fuel combustion by introducing biomass ash into a combustion chamber.

1 . A method of reducing nitrogen oxide emissions formed during combustion of a primary fuel, comprising the steps of: 
 providing a combustion chamber with a main combustion zone where the primary fuel and an oxidizer are introduced, and a reburn zone;    introducing a supplemental reburning fuel into the reburn zone to create an oxygen-deficient, fuel-rich combustion zone; and    injecting biomass ash into the reburn zone to reduce nitrogen oxide emissions.    
     
     
         2 . The method of  claim 1 , further comprising a diverting step, wherein a portion of the oxidizer is introduced into the combustion chamber downstream of the reburn zone.  
     
     
         3 . The method of  claim 1  wherein the reburning fuel comprises at least one of gaseous, liquid and solid fuels.  
     
     
         4 . The method of  claim 1 , wherein flue gas formed during combustion is recirculated and introduced with the reburning fuel.  
     
     
         5 . The method of  claim 3 , wherein the gaseous fuel comprises at least one of natural gas, CH 4 , and C 2 H 6 , and other gaseous hydrocarbon fuels.  
     
     
         6 . The method of  claim 3 , wherein the liquid fuel comprises at least one of fuel oil, and other liquid hydrocarbon fuels.  
     
     
         7 . The method of  claim 3 , wherein the solid fuel comprises coal.  
     
     
         8 . The method of  claim 1 , wherein the biomass ash is derived from at least one of plant matter, biologically derived solid waste, crop residues, municipal solid waste, forest residues, urban wood waste, pine bark, sludge from a pulping process, and pulp mill waste.  
     
     
         9 . The method of  claim 1 , wherein a temperature in the reburn zone is about 1,100° C.  
     
     
         10 . The method of  claim 1 , wherein a stoichiometric ratio in the reburn zone is about 0.95.  
     
     
         11 . The method of  claim 3 , wherein the reburning fuel and the biomass ash are introduced together into the combustion chamber.  
     
     
         12 . The method of  claim 1 , wherein the primary fuel is coal.  
     
     
         13 . A method of reducing nitrogen oxide emissions formed during combustion of a primary fuel, comprising the steps of: 
 providing a combustion chamber with a main combustion zone where fuel and an oxidizer are introduced; and    injecting biomass ash into a substoichiometric region of the combustion chamber to reduce nitrogen oxide emissions.    
     
     
         14 . The method of  claim 13 , wherein the substoichiometric (fuel-rich) region is created by at least one of providing a portion of the oxidizer into the combustion chamber at a location downstream of the main combustion zone, and controlled separation and mixing of the oxidizer and the primary fuel introduced by a burner into the combustion chamber.  
     
     
         15 . The method of  claim 13 , further comprising the step of providing a reburn zone within the combustion chamber, and introducing a supplemental reburning fuel into the reburn zone, the reburning fuel comprising at least one of gaseous, liquid and solid fuels.  
     
     
         16 . The method of  claim 13 , wherein flue gas formed during combustion is recirculated and introduced with the reburning fuel.  
     
     
         17 . The method of  claim 16 , wherein the gaseous fuel comprises at least one of natural gas, CH 4 , and C 2 H 6 , and other gaseous hydrocarbon fuels.  
     
     
         18 . The method of  claim 16 , wherein the liquid fuel comprises at least one of fuel oil, and other liquid hydrocarbon fuels.  
     
     
         19 . The method of  claim 16 , wherein the solid fuel comprises coal.  
     
     
         20 . The method of  claim 13 , wherein the biomass ash is derived from at least one of plant matter, biologically derived solid waste, crop residues, municipal solid waste, forest residues, urban wood waste, pine bark, sludge from a pulping process, and pulp mill waste.  
     
     
         21 . The method of  claim 13 , wherein a temperature in the reburn zone is about 1,100° C.  
     
     
         22 . The method of  claim 13 , wherein a stoichiometric ratio in the reburn zone is about 0.95.  
     
     
         23 . The method of  claim 16 , wherein the reburning fuel and the biomass ash are introduced together into the combustion chamber.  
     
     
         24 . The method of  claim 13  wherein the primary fuel is coal.