Reduction of NOx in combustion flue gas

Abstract

A method of decreasing the concentration of nitrogen oxides in flue gases emitted into the atmosphere from combustion systems that burn carbonaceous materials which involves pretreating carbonaceous material particles with vanadium, titanium and ammonia. In the case of coal particles, vanadium, titanium dioxide and ammonium acetate are used to coat the coal particles. The vanadium and titanium dioxide are applied as substantially uniform coatings on the surfaces of the coal particles by incorporating the vanadium and titanium dioxide in emulsions or suspensions.

1 . A method of reducing NO x  emissions in combustion systems that burn carbonaceous materials which method comprises the steps of: 
 a) providing a source of carbonaceous material particles;    b) substantially uniformly distributing vanadium on the surfaces of the carbonaceous material particles;    c) substantially uniformly distributing a source of titanium on the surfaces of the carbonaceous material particles;    d) distributing a source of ammonia on the surfaces of the carbonaceous material particles; and    e) combusting the carbonaceous material particles treated in steps b), c) and d) in a combustor.    
   
   
       2 . A method of reducing NO x  emissions in combustion systems that burn carbonaceous materials according to  claim 1 , wherein steps b) and c) are combined in a single step in which the titanium and ammonia are combined together and distributed on the surfaces of the carbonaceous material particles.  
   
   
       3 . A method of reducing NO x  emissions in combustion systems that burn carbonaceous materials according to  claim 1 , wherein at least one of the vanadium, source of titanium and source of ammonia is incorporated into at least one of an emulsion, slurry, suspension and solution prior to being distributed onto the surfaces on the carbonaceous material.  
   
   
       4 . A method of reducing NO x  emissions in combustion systems that burn carbonaceous materials according to  claim 1 , wherein the carbonaceous material comprises at least one of coal, coal fines, coke, coke breeze, coke fines, revert materials and mixtures thereof.  
   
   
       5 . A method of reducing NO x  emissions in combustion systems that burn carbonaceous materials according to  claim 4 , wherein the carbonaceous material is coal.  
   
   
       6 . A method of reducing NO x  emissions in combustion systems that burn carbonaceous materials according to  claim 1 , wherein the amount of vanadium incorporated is from about 0.01 to about 20 ppm of carbonaceous material.  
   
   
       7 . A method of reducing NO x  emissions in combustion systems that burn carbonaceous materials according to  claim 5 , wherein the amount of vanadium incorporated is from about 0.01 to about 20 ppm of carbonaceous material.  
   
   
       8 . A method of reducing NO x  emissions in combustion systems that burn carbonaceous materials according to  claim 5 , wherein the source of titanium comprises titanium dioxide.  
   
   
       9 . A method of reducing NO x  emissions in combustion systems that burn carbonaceous materials according to  claim 8 , wherein the amount of titanium dioxide incorporated is from about 0.01 to about 0.2 wt. % of the carbonaceous material.  
   
   
       10 . A method of reducing NO x  emissions in combustion systems that burn carbonaceous materials according to  claim 5 , wherein the source of ammonia comprises ammonium acetate.  
   
   
       11 . A method of reducing NO x  emissions in combustion systems that burn carbonaceous materials according to  claim 10 , wherein the amount of ammonium acetate incorporated is from about 0.05 to about 0.6 wt. % of the carbonaceous material.  
   
   
       12 . A method of reducing NO x  emissions in combustion systems that burn carbonaceous materials according to  claim 1 , wherein the combustor comprises a furnace.  
   
   
       13 . A method of reducing NO x  emissions in combustion systems that burn carbonaceous materials according to  claim 1 , wherein the combustor comprises a boiler.  
   
   
       14 . A carbonaceous material which is treated so as to reduce NO x  emissions when combusted in a combustor, said carbonaceous material comprising: 
 particles of carbonaceous material in which the surfaces of the individual particles are substantially uniformly coated with vanadium and a source of titanium.    
   
   
       15 . A carbonaceous material according to  claim 14 , where the particles of carbonaceous material are further coated with a source of ammonia.  
   
   
       16 . A carbonaceous material according to  claim 14 , wherein the particles of carbonaceous material comprises coal particles.  
   
   
       17 . A carbonaceous material according to  claim 14 , wherein the amount of vanadium coated on the carbonaceous material particles is from about 0.01 to about 20 ppm based on the carbonaceous material.  
   
   
       18 . A carbonaceous material according to  claim 14 , wherein the source of titanium comprises titanium dioxide.  
   
   
       19 . A carbonaceous material according to  claim 18 , wherein the amount of titanium dioxide coated on the carbonaceous material particles is from about 0.01 to about 0.2 wt. % based on the carbonaceous material.  
   
   
       20 . A carbonaceous material according to  claim 14 , wherein a sufficient amount of ammonia is coated on the carbonaceous material particles so as to provide one molecule of ammonia for each molecule of NO x  that will be produced during combustion of the carbonaceous material.