Process for improving operation of large-scale combustors

Abstract

The heat output, e.g., megawatt product or steam generation, of a combustor is increased, preferably while plume is mitigated, by targeting treatment chemicals to locations in a furnace. The process improves heat output from the fuel in the region of the combustor optimum for heat recovery and also maintains good heat transfer characteristics for the heat exchange surfaces. The effectiveness of targeted in furnace injection, in-fuel introduction and in-furnace introduction of slag and/or corrosion and/or plume control chemicals are preferably determined, as are the effectiveness of targeted in furnace injection, in fuel introduction and in furnace introduction of combustion catalysts. Then, the effectiveness of various combinations of the above treatments are determined, and a treatment regimen employing one or more of the above treatments is selected. Preferred treatment regimens will contain at least two and preferably three of the treatments. Chemical utilization and boiler maintenance can improved as LOI carbon, slagging and/or corrosion are also controlled. In one preferred embodiment, the invention enables increasing by determining the positions for effective introduction of slag controlling chemical, introducing targeted slag controlling chemical treatment in an amount effective to reduce slag and introducing a combustion catalyst into the flame in an amount effective to improve combustion.

1 . A process for improving the operation of combustors, comprising: 
 burning a carbonaceous fuel in the presence of a combustion catalyst in the fuel or injected into the combustor apart from the fuel;    determining combustion conditions within a combustor that can benefit from targeted in-furnace treatment chemical;    locating introduction points on the furnace wall where introduction of targeted in-furnace treatment chemical could be accomplished; and,    based on the determinations of the previous step, introducing targeted in-furnace treatment chemical.    
   
   
       2 . A process according to  claim 1  wherein the combustion catalyst comprises a metal compound wherein the metal is selected from the group consisting of copper, iron, magnesium, calcium, cerium, barium, manganese, zinc and mixtures of any of these.  
   
   
       3 . A process according to  claim 1  wherein the combustion catalyst comprises calcium nitrate.  
   
   
       4 . A process according to  claim 1  wherein the concentration of the targeted treatment chemical in a slurry or solution is within the range of from about 1 to about 100%.  
   
   
       5 . A process according to  claim 1  wherein the combustion catalyst is introduced either in-fuel or in-furnace at a dosage rate of from about 0.2 to about 0.8 kg per 1000 kg of carbonaceous fuel burned in the combustor.  
   
   
       6 . A process according to  claim 1  wherein the targeted treatment chemical is introduced into the furnace at a dosage rate of from about 0.2 to about 0.5 kg per 1000 kg of carbonaceous fuel burned in the combustor.  
   
   
       7 . A process according to  claim 1  wherein the targeted treatment chemical comprises a slurry of magnesium oxide or magnesium hydroxide as a slag reducing chemical and a combustion catalyst.  
   
   
       8 . A process according to  claim 6  wherein targeted treatment chemical is introduced at more than one elevation.  
   
   
       9 . A process for improving the operation of combustors, comprising: 
 burning a carbonaceous fuel containing a combustion catalyst and a slag and/or corrosion controlling chemical;    determining combustion conditions within a combustor that can benefit from targeted in-furnace treatment chemical for control of slag and/or corrosion;    locating introduction points on the furnace wall where introduction of targeted in-furnace treatment chemical could be accomplished; and,    based on the determinations of the previous step, introducing targeted in-furnace treatment chemical.    
   
   
       10 . A process according to  claim 9  wherein the combustion catalyst is introduced at a dosage rate of from about 0.2 to about 0.8 kg per 1000 kg of carbonaceous fuel burned in the combustor.  
   
   
       11 . A process according to  claim 9  wherein targeted treatment chemical is a combustion catalyst.  
   
   
       12 . A process for reducing the opacity of plume released to the atmosphere from large-scale combustors, comprising: 
 determining the effectiveness of targeted in furnace injection of slag and/or corrosion and/or plume control chemicals;    determining the effectiveness of adding slag and/or corrosion and/or plume control chemicals to the fuel;    determining the effectiveness of adding combustion catalysts to the fuel;    determining the effectiveness of adding combustion catalysts to the furnace;    determining the effectiveness of targeted in furnace injection of combustion catalysts;    determining the effectiveness of various combinations of the above treatments; and    selecting a treatment regimen employing one or more of the above treatments.    
   
   
       13 . A process according to  claim 12 , wherein the combustion catalyst comprises a metal compound wherein the metal is selected from the group consisting of copper, iron, magnesium, calcium, cerium, barium, zinc and mixtures of any of these.  
   
   
       14 . A process according to  claim 12 , wherein the targeted treatment chemical is magnesium oxide or magnesium hydroxide in a vehicle.  
   
   
       15 . A process according to  claim 12 , wherein the selected treatment regimen comprises at least three of the above treatments.  
   
   
       16 . A process according to  claim 15 , wherein the combustion catalyst comprises a metal compound wherein the metal is selected from the group consisting of copper, iron, magnesium, calcium, cerium, zinc, zinc and mixtures of any of these.  
   
   
       17 . A process according to  claim 15 , wherein the targeted treatment chemical is a slurry of magnesium oxide or magnesium hydroxide.  
   
   
       18 . A process for improving the operation of combustors, comprising: 
 burning a carbonaceous fuel in the presence of a combustion catalyst comprising a composition of calcium, copper, barium, manganese or a mixture of these in the fuel or injected into the combustor apart from the fuel;    determining combustion conditions within a combustor that can benefit from targeted in-furnace treatment chemical;    locating introduction points on the furnace wall where introduction of targeted in-furnace treatment chemical could be accomplished; and,    based on the determinations of the previous step, introducing targeted in-furnace treatment chemical.    
   
   
       19 . A process for increasing heat output of a combustor burning carbonaceous fuel in a flame, comprises: 
 determining the positions for effective introduction of slag controlling chemical;    based on the determination of the previous step, introducing targeted slag controlling chemical treatment in an amount effective to reduce slag; and    introducing a combustion catalyst into the flame in an amount effective to improve combustion.    
   
   
       20 . A process according to  claim 19  wherein the slag controlling chemical comprises a slurry of magnesium oxide or magnesium hydroxide as a slag reducing chemical and combustion catalyst comprises a composition of calcium, copper, barium, manganese, or a mixture of any of these.