Product and process to reduce mercury emission

Abstract

In a method to decrease emission of mercury, a factor is selected to control a combustion process to generate a flue gas comprising fly ash with enhanced unburned carbon; the combustion process is controlled according to a factor selected from reburning fuel, flue gas temperature, OFA injection, coal particle size, LNB flow, LNB design, combustion zone air, stoichiometric ratio of fuel, fuel/air mixing in a primary combustion zone and fuel/air mixing in a secondary combustion zone to produce the flue gas comprising fly ash with enhanced unburned carbon and to vaporize mercury; and the flue gas is allowed to cool to collect fly ash with enhanced unburned carbon with absorbed mercury. A system to decrease emission of mercury; comprises a combustion zone that is controlled to generate a flue gas comprising fly ash with enhanced unburned carbon and that produces vaporized mercury; and a post combustion zone to cool the flue gas to collect fly ash with enhanced unburned carbon with absorbed mercury.

1 - 18 . (canceled)  
     
     
         19 . A system to decrease emission of mercury; comprising: 
 a combustion zone that is controlled to generate a flue gas comprising fly ash with enhanced unburned carbon and that produces vaporized mercury; and    a post combustion zone to cool the flue gas to collect fly ash with enhanced unburned carbon with absorbed mercury.    
     
     
         20 - 25 . (canceled)  
     
     
         26 . A composition comprising fly ash with absorbed in situ produced carbon.  
     
     
         27 . The composition according to  claim 26 , comprising fly ash with at least greater than 10 weight percent absorbed in situ produced unburned carbon.  
     
     
         28 . The composition according to  claim 26 , comprising fly ash with 12 to 30 weight percent absorbed in situ produced unburned carbon.  
     
     
         29 . The composition according to  claim 26 , comprising fly ash with 14 to 18 weight percent absorbed in situ produced unburned carbon.  
     
     
         30 . The composition according to  claim 26 , comprising fly ash with absorbed unburned carbon formed in situ by controlling a combustion process according to a factor selected from reburning fuel, OFA injection, coal particle size, LNB flow, LNB design, stoichiometric ratio of fuel, fuel/air mixing in a primary combustion zone and fuel/air mixing in a secondary combustion zone.  
     
     
         31 . The composition according to  claim 26 , wherein the absorbed carbon is enhanced unburned carbon with absorbed mercury  
     
     
         32 . A method to decrease emission of mercury, comprising: selecting a factor to control a combustion process to generate a flue gas comprising fly ash with enhanced in situ-formed unburned carbon, wherein the factor is selected from the group consisting of reburning fuel, OFA injection, coal particle size, LNB flow, LNB design, stoichiometric ratio of fuel, fuel/air mixing in a primary combustion zone and fuel/air mixing in a secondary combustion zone; controlling the combustion process according to a the factor to produce the flue gas comprising fly ash with enhanced unburned carbon and to vaporize mercury; and 
 allowing the flue gas to cool to collect fly ash with enhanced unburned carbon with absorbed mercury.    
     
     
         33 . The method of  claim 32 , comprising forming the fly ash with enhanced unburned carbon by fuel staging comprising firing the furnace in a main burner in the combustion zone in the presence of unlimited air and injecting additional fuel for reburning in a fuel rich subsequent combustion zone.  
     
     
         34 . The method of  claim 32 , comprising forming the fly ash with enhanced unburned carbon by fuel staging comprising: firing the furnace in a main burner in the combustion zone in the presence of unlimited air; injecting additional fuel for reburning in a fuel rich subsequent combustion zone; and subsequently applying overfire air to burn out remaining combustibles.  
     
     
         35 . The method of  claim 32 , comprising forming the fly ash with enhanced unburned carbon by fuel staging comprising: firing the furnace in a main burner in the combustion zone in the presence of unlimited air; injecting additional fuel for reburning in a fuel rich subsequent