Method of operating a coal burning facility

Abstract

Methods involve adding sorbent components, such as calcium oxide, alumina, and silica, as well as optional halogens as part of environmental control. Use of the sorbents leads to significant reductions in sulfur and mercury emissions that otherwise would result from burning coal. Use of the sorbents leads to production of waste coal ash that, while higher in mercury; is nevertheless usable as a commercial product because the mercury in the ash is non-leaching and because the coal ash has a higher cementitious nature by virtue of the increased content of the sorbent components in the ash. Thus, the methods involve adding powders having qualities that lead to the production of a cementitious coal ash while at the same time reducing emissions from a coal burning facility.

1 . Non-leaching coal ash having 200 ppb or more of total Hg and characterized by a concentration of mercury in the extract of less than 0.2 ppb when tested using the Toxicity Characteristic Leaching Procedure test Method 1311. 
     
     
         2 . Coal ash according to  claim 1 , comprising over 250 ppb of Hg. 
     
     
         3 . Coal ash according to  claim 1 , comprising 200-250 ppb Hg. 
     
     
         4 . Coal ash according to  claim 1 , comprising the combustion product of US Powder River Basin coal. 
     
     
         5 . A hydraulic cement product comprising Portland cement and 0.1-99% by weight of a coal ash according to  claim 1 . 
     
     
         6 . A cementitious mixture comprising a hydraulic cement product according to  claim 5  and aggregate. 
     
     
         7 . A concrete comprising the cementitious mixture of  claim 6 . 
     
     
         8 . A method of removing deposits from the boiler tubes in a coal burning furnace, comprising burning coal in the presence of sorbent in a furnace where fouling has caused bonded deposits on the boiler tubes from running without use of the sorbents, wherein burning coal in the presence of the sorbent also produces an ash that is more cementitious than ash produced from burning coal without the sorbent and that is non-leaching in mercury as characterized by a concentration of mercury in the extract of less than 0.2 ppb when tested using the Toxicity Characteristic Leaching Procedure test Method 1311. 
     
     
         9 . A method according to  claim 8 , wherein removing deposits from the boiler tubes increases the temperature of the water in the tubes. 
     
     
         10 . A method according to  claim 8 , wherein the boiler is part of an electricity generating facility, and use of the sorbent results in a higher amount of electricity generated per unit of coal burned. 
     
     
         11 . A method according to  claim 8 , wherein the sorbent comprises silica, alumina, and calcium oxide. 
     
     
         12 . A method of burning coal in a coal burning facility to produce heat energy and waste ash comprising combusting the coal in the presence of a sorbent, wherein:
 emissions of NOx and at least one of SOx and mercury are reduced by at least 20%, compared to burning coal without the added sorbent;   an ash is produced that is more highly cementitious than ash produced by burning the coal without the added sorbent; and   an ash is produced that is lower leaching in mercury than ash produced by burning the coal without the added sorbent.   
     
     
         13 . A method according to  claim 12 , wherein the ash is non-leaching in mercury as characterized by a concentration of mercury in the extract of less than 0.2 ppb when tested using the Toxicity Characteristic Leaching Procedure test Method 1311. 
     
     
         14 . A method according to  claim 12 , wherein the operator of the coal burning facility qualifies for tax credits under section 45 of the U.S. Internal Revenue Code. 
     
     
         15 . A method according to  claim 12 , wherein the sorbent comprises an aluminosilicate material. 
     
     
         16 . A method according to  claim 12 , wherein the sorbent comprises cement kiln dust. 
     
     
         17 . A method according to  claim 12 , wherein the sorbent comprises silica, alumina, and a halogen. 
     
     
         18 . A method according to  claim 12 , wherein the sorbent comprises a bromine compound. 
     
     
         19 . A method according to  claim 18 , wherein the sorbent comprises a bromide. 
     
     
         20 . A method according to  claim 18 , wherein the sorbent comprises calcium bromide.