Process for operating a coal-fired furnace with reduced slag formation

Abstract

There is provided a process for operating a coal-fired furnace to generate heat. The process has the steps of a) providing the coal to the furnace and b) combusting the coal in the presence of a first slag-reducing ingredient and a second slag-reducing ingredient in amounts effective to reduce slag formation in the furnace. The first slag-reducing ingredient and the second slag-reducing ingredient are different substances. The first slag-reducing ingredient is selected from the group consisting of magnesium carbonate, magnesium hydroxide, magnesium oxide, magnesium sulfate, and combinations thereof. The second slag-reducing ingredient is selected from the group consisting of copper acetate, copper nitrate, aluminum nitrate, aluminum oxide, aluminum hydroxide, and ammonium phosphate. There is also provided a method for reducing slag formation in a coal-fired furnace.

What is claimed is: 
     
         1 . A process for operating a coal-fired furnace to generate heat, comprising:
 a) providing the coal to the furnace; and   b) combusting the coal in the presence of a first slag-reducing ingredient and a second slag-reducing ingredient in amounts effective to reduce slag formation in the furnace,   wherein the first slag-reducing ingredient is selected from the group consisting of magnesium carbonate, magnesium hydroxide, magnesium sulfate, magnesium oxide, and combinations thereof, and wherein the second slag-reducing ingredient is selected from the group consisting of copper acetate, copper nitrate, aluminum nitrate, aluminum oxide, aluminum hydroxide, ammonium phosphate, and combinations thereof.   
     
     
         2 . The process of  claim 1 , wherein the first slag-reducing ingredient is magnesium hydroxide. 
     
     
         3 . The process of  claim 1 , wherein the second slag-reducing ingredient is selected from the group consisting of copper acetate, copper nitrate, and a combination thereof. 
     
     
         4 . The process of  claim 1 , wherein the first and second slag-reducing ingredients are added to the coal at up to about 2000 ppm by weight based upon the weight of the coal as received. 
     
     
         5 . The process of  claim 1 , wherein the first and second slag-reducing ingredients are present at about 100 to about 1000 ppm by weight based upon the weight of the coal as received. 
     
     
         6 . The process of  claim 1 , wherein the ratio of the first slag-reducing ingredient to the second slag-reducing ingredient ranges from about 95:5 to about 60:40. 
     
     
         7 . The process of  claim 1 , wherein the ratio of the first slag-reducing ingredient to the second slag-reducing ingredient ranges from about 90:10 to about 80:20. 
     
     
         8 . The process of  claim 1 , wherein rate of formation of slag is reduced by a factor of about 10 to about 100 compared to the presence of the first slag-reducing ingredient alone. 
     
     
         9 . A method for reducing slag formation in a coal-fired furnace, comprising combusting coal in the furnace in the presence of a first slag-reducing ingredient and a second slag-reducing ingredient in amounts effective to reduce slag formation in the furnace, wherein the first slag-reducing ingredient is selected from the group consisting of magnesium carbonate, magnesium hydroxide, magnesium sulfate, magnesium oxide, and combinations thereof, and wherein the second slag-reducing ingredient is selected from the group consisting of copper acetate, copper nitrate, aluminum nitrate, aluminum oxide, aluminum hydroxide, ammonium phosphate, and combinations thereof. 
     
     
         10 . The method of  claim 9 , wherein the first slag-reducing ingredient is magnesium hydroxide. 
     
     
         11 . The method of  claim 9 , wherein the second slag-reducing ingredient is selected from the group consisting of copper acetate, copper nitrate, and a combination thereof. 
     
     
         12 . The method of  claim 9 , wherein the second slag-reducing ingredient is present at up to about 2000 ppm by weight based upon the weight of the coal as received. 
     
     
         13 . The method of  claim 9 , wherein the second slag-reducing ingredient is present at from about 100 ppm to about 1000 ppm by weight based upon the weight of the coal as received. 
     
     
         14 . The method of  claim 9 , wherein the ratio of the first slag-reducing ingredient to the second slag-reducing ingredient ranges from about 95:5 to about 60:40. 
     
     
         15 . The method of  claim 9 , wherein the ratio of the first slag-reducing ingredient to the second slag-reducing ingredient ranges from about 90:10 to about 80:20. 
     
     
         16 . The method of  claim 9 , wherein rate of formation of slag is reduced by a factor of about 10 to about 100 compared to the presence of the first slag-reducing ingredient alone.