METHOD FOR LOW NOx COMBUSTION OF SYNGAS / HUGH HYDROGEN FUELS

Abstract

A method is provided for achieving low NOx in the operation of a non-premixed combustion system by reacting a fuel-rich mixture to produce partial reaction products plus heat, transferring a portion of the heat to a bypass air stream, and passing the cooled partial reaction products into non-premixed contact and combustion with a stoichiometric portion of the heated bypass air stream. A supply of fuel and a supply of air is provided; and a fuel-rich mixture is formed and reacted to produce partial reaction products plus a heat of reaction. A portion of the heat of reaction is transferred to a bypass air stream and the cooled partial reaction products are passed into non-premixed contact and combustion with a stoichiometric portion of the heated bypass air stream.

1 . A method of achieving low NOx in operation of a non-premixed combustion system comprising:
 a) providing a supply of fuel comprising hydrogen gas;   b) providing a supply of air and splitting the supply of air into a first percentage of air and a second percentage of air;   c) forming a fuel-rich mixture of the fuel and the first percentage of air;   d) reacting the fuel-rich mixture to produce partial reaction products comprising a portion of reacted fuel and a portion of unreacted fuel plus a heat of reaction and transferring a portion of the heat of reaction to the second percentage of air thereby producing a heated second percentage of air and cooled partial reaction products; and   e) passing the cooled partial reaction products into non-premixed contact and combustion with a stoichiometric portion of the heated second percentage of air.   
     
     
         2 . The method of  claim 1  wherein the non-premixed contact and combustion of the cooled partial reaction products with a stoichiometric portion of the heated second percentage of air defines a reduced flame front temperature. 
     
     
         3 . The method of  claim 2  wherein the reduced flame front temperature is at least 200 degrees Celsius lower than that of the portion of unreacted fuel. 
     
     
         4 . The method of  claim 1  wherein the fuel comprises syngas. 
     
     
         5 . The method of  claim 1  wherein the fuel comprises from about 20 percent hydrogen to about 75 percent hydrogen. 
     
     
         6 . The method of  claim 1  wherein the fuel comprises from about 75 percent hydrogen to about 100 percent hydrogen. 
     
     
         7 . The method of  claim 1  wherein the amount of air in the fuel-rich mixture represents at least about twenty percent of the total supply of air. 
     
     
         8 . The method of  claim 1  wherein step (d) further comprises reacting the fuel-rich mixture in a backside-cooled catalytic reactor. 
     
     
         9 . The method of  claim 6  wherein step (d) further comprises reacting the fuel-rich mixture in a backside-cooled catalytic reactor and the second percentage of air provides backside cooling. 
     
     
         10 . A method of achieving low NOx in operation of a non-premixed combustion system comprising:
 a. obtaining a supply of fuel comprising hydrogen gas;   b. obtaining a supply of air and splitting the supply of air into a first percentage of air and a second percentage of air;   c. forming a fuel-rich mixture of the fuel and the first percentage of air;   d. reacting the fuel-rich mixture to produce partial reaction products consisting essentially of reacted fuel and remaining unreacted fuel plus a heat of reaction and transferring a portion of the heat of reaction to the second percentage of air thereby producing a heated second percentage of air and cooled partial reaction products; and   e. combusting the cooled partial reaction products on contact with a stoichiometric portion of the heated second percentage of air in a non-premixed flame such that a second portion of the heated second percentage of air bypasses the non-premixed flame thereby reducing heat liberated in the non-premixed flame.   
     
     
         11 . The method of  claim 10  wherein the non-premixed contact and combustion of the cooled partial reaction products with a stoichiometric portion of the heated second percentage of air defines a reduced flame front temperature. 
     
     
         12 . The method of  claim 11  wherein the reduced flame front temperature is at least 200 degrees Celsius lower than that of the portion of unreacted fuel. 
     
     
         13 . The method of  claim 11  wherein the fuel is syngas. 
     
     
         14 . The method of  claim 11  wherein the fuel comprises from 20 percent to 75 percent hydrogen. 
     
     
         15 . The method of  claim 11  wherein the fuel comprises from about 75 percent hydrogen to about 100 percent hydrogen. 
     
     
         16 . The method of  claim 11  wherein the amount of air in the fuel-rich mixture represents at least about twenty percent of the total supply of air. 
     
     
         17 . The method of  claim 11  wherein step (d) further comprises reacting the fuel-rich mixture in a backside-cooled catalytic reactor. 
     
     
         18 . The method of  claim 17  wherein step (d) further comprises reacting the fuel-rich mixture in a backside-cooled catalytic reactor and the second percentage of air provides backside cooling.