Urea-based mixing process for increasing combustion efficiency and reduction of nitrogen oxides (NOx)

Abstract

A method for increasing combustion process and furnace efficiency and for reducing NOx formation, including the steps of: providing a furnace with a plurality of secondary air injection ducts, asymmetrically positioned in an opposing manner; injecting fuel with primary air through a first stage prior to injection of a second air; injecting secondary air through the plurality of reagent injection ducts; providing a staged combustion system including a furnace with asymmetrical injection ports introducing at least one reagent to the reactor by asymmetrical injection at predetermined, spaced apart locations; controlling the asymmetrical injection to produce a high velocity mass flow and a turbulence resulting in dispersion of the at least one reagent into the reaction system, wherein one of the at least one reagents is an NH3-producing compound; thereby providing increased reaction efficiency and reduced NOx formation in the combustion process.

What is claimed is:  
     
         1 . A method for increasing combustion process and furnace efficiency and for reducing NOx formation, comprising the steps of: 
 providing a staged combustion system including a furnace with asymmetrical injection ports introducing at least one reagent to the reactor by asymmetrical injection at predetermined, spaced apart locations;    injecting fuel with primary air through a first stage prior to injection of a second air;    injecting secondary air and nitrogenous agent through the plurality of injection ducts;    controlling the asymmetrical injection of secondary air to produce a turbulence resulting in dispersion of the at least one nitrogenous agent into the reaction system, thereby providing increased reaction and reactor efficiency and reduced NOx formation in the reaction process.    
     
     
         2 . The method according to  claim 1 , further including the step of adding additional reagents in stages, spaced apart in location and time.  
     
     
         3 . The method according to  claim 1 , wherein the nitrogenous agent is selected from the group consisting of urea, urea analogs, ammonia, cyanuric acid, ammonium carbamate, ammonium carbonate, mixtures of ammonia and ammonium bicarbonate, one or more of the hydrolysis products of urea or mixtures or complexes thereof, compounds which produce ammonia as a byproduct, ammonium formate, ammonium oxalate, hexamethylenetetramine, ammonium salts of organic acids, 5- or 6- membered heterocyclic hydrocarbons having at least one cyclic nitrogen, hydroxy amino hydrocarbons, amino acids, proteins, monoethanolamine, guanidine, guanidine carbonate, biguanidine, guanylurea sulfate, melamine, dicyandiamide, calcium cyanamide, biuret, 1,1′-azobisformamide, methylol urea, methylol urea-urea condensation product, dimethylol urea, methyl urea, dimethyl urea, and combinations thereof  
     
     
         4 . The method according to  claim 1 , wherein the nitrogenous agent is selected from the group consisting of solid urea, liquid urea, urea in aqueous solution, and combinations thereof.  
     
     
         5 . The method according to  claim 1 , wherein the at least one reagent is introduced at a plurality of injection ducts, asymmetrically positioned in an opposing manner;  
     
     
         6 . The method according to  claim 1 , wherein two reagents, a first reagent and a second reagent, are introduced to the system in a sequential manner with the first reagent being introduced prior to the second reagent.  
     
     
         7 . The method according to  claim 1 , the velocity of the injected reagent is such that the ratio of the velocity to the reactor width is between about 2 sec −1  to about 150 sec −1 ; 
 thereby increasing combustion efficiency and furnace efficiency via swirl, peripheral turbulence, and rotation-induce turbulence of the reactor.    
     
     
         8 . The method of  claim 1 , wherein the temperature of the injected reagent is between about 40 and about 460 degrees centigrade.  
     
     
         9 . The method of  claim 8 , wherein the temperature of the injected reagent is between about 76 and about 340 degrees centigrade.  
     
     
         10 . The method of  claim 1 , wherein the system has at least two levels of secondary air injection ducts.  
     
     
         11 . The method of  claim 10 , wherein the system has at least three levels of secondary air injection ducts.  
     
     
         12 . The method of  claim 1 , wherein the velocity of the injected reagent is such that the ratio of the velocity to the reactor width is between about 3 sec −1  to about 60 sec −1 .  
     
     
         13 . A method for increasing combustion efficiency in a reactor and for reducing pollutants therein, comprising: 
 providing a reactor with a plurality of reagent injection ducts, asymmetrically positioned in an opposing manner;    injecting a first reagent through a first stage prior to injection of a second reagent;    injecting a second reagent through the plurality of reagent injection ducts;    wherein the velocity of the injected air is such that the penetration of the injected reagents is greater than the reactor width by at least about 1.5 widths;    thereby increasing furnace efficiency and reducing NOx via nitrogenous reduction and mixing and rotation of the combustion space.    
     
     
         14 . The method of  claim 13 , wherein the urea reagent is selected from the group consisting of urea, urea analogs, and the like, and combinations thereof.  
     
     
         15 . The method of  claim 13 , wherein the urea reagent is selected from solid urea, liquid urea, urea in aqueous solution, and combinations thereof.  
     
     
         16 . The method of  claim 13 , wherein the system has at least two levels of reagent introduction ducts for injection of the at least one reagent.  
     
     
         17 . The method of  claim 16 , wherein the system has at least three levels of reagent ducts for injection of the at least one reagent.  
     
     
         18 . A method for increasing combustion furnace efficiency and reducing NOx, comprising: 
 providing a reactor with a plurality of reagent injection ducts, asymmetrically positioned in an opposing manner;    injecting at least one nitrogenous agent through the ducts in the proximity of high-velocity secondary air in stages, wherein one of the at least one agents is urea;    wherein the velocity of the secondary air is such that the at least one injected reagent is dispersed and the combustion gas column rotates at least one half revolution prior to exiting the reactor;    thereby increasing reactor efficiency and reducing NOx via mixing and rotation of the reagents and gases in the reactor.    
     
     
         19 . The method of  claim 18 , wherein the urea reagent is selected from the group consisting of urea, urea analogs, and the like, and combinations thereof.  
     
     
         20 . The method of  claim 18 , wherein the urea reagent is selected from solid urea, liquid urea, urea in aqueous solution, and combinations thereof.  
     
     
         21 . The method of  claim 18 , wherein the system has at least two levels of reagent ducts for injection of the reagents.  
     
     
         22 . The method of  claim 18 , wherein the system has at least three levels of reagent ducts for injection of the reagents.  
     
     
         23 . A method for increasing combustion process and furnace efficiency and for reducing NOx formation, comprising the steps of: 
 providing a furnace with a plurality of secondary air injection ducts, asymmetrically positioned in an opposing manner, and a plurality of nitrogenous agent injectors in the proximity of the secondary air injection ducts;    injecting fuel with primary air through a first stage prior to injection of a second air;    injecting secondary air through the plurality of injection ducts;    injecting at least one reagent through the plurality of injectors;    controlling the asymmetrical injection of secondary air to produce a turbulence resulting in dispersion of the at least one nitrogenous agent into the reaction system,    thereby providing increased reaction and reactor efficiency and reduced NOx formation in the reaction process.    
     
     
         24 . A method for increasing combustion process and furnace efficiency and for reducing NOx formation, comprising the steps of: 
 providing a staged combustion system including a furnace with asymmetrical injection ports introducing at least one reagent to the reactor by asymmetrical injection at predetermined, spaced apart locations;    injecting fuel with primary air through a first stage prior to injection of a second air;    injecting secondary air through the plurality of reagent injection ducts;    controlling the asymmetrical injection to produce a high velocity mass flow and a turbulence resulting in dispersion of the at least one reagent into the reaction system, wherein one of the at least one reagents is an NH3-producing compound;    thereby providing increased reaction efficiency and reduced NOx formation in the reaction process.    
     
     
         25 . The method of  claim 24 , further including the step of injecting the NH3-producing compound after a catalyst to neutralize acids via non-reductive acid neutralization.