Method for operating pulverized-coal-fired boiler facility

Abstract

Provided is a method for operating a pulverized coal-fired boiler facility, wherein upgraded low-grade coal can be safely used as fuel and an existing facility needs little remodeling. The present invention relates to a method for operating a pulverized coal-fired boiler facility ( 100 ) that uses upgraded brown coal as fuel. Boiler exhaust gas taken out of an exhaust gas duct ( 31 ) is added to air from a primary air fan ( 10 ) to prepare mixed gas with an oxygen concentration of less than 12% in a volume ratio, the mixed gas is caused to separately flow to a carrier gas duct ( 33 ) that goes through a GAH ( 8 ) and a bypass carrier gas duct ( 34 ) that bypasses the GAH ( 8 ), and thereafter the mixed gas is supplied to a mill ( 21 ).

1 . A method for operating a pulverized-coal-fired boiler facility that uses an upgraded low-grade coal as a fuel, comprising:
 preparing a mixed gas having an oxygen concentration of less than 12% by volume by the addition of a boiler exhaust gas to air; and   supplying the mixed gas to a coal pulverizer.   
     
     
         2 . The method for operating a pulverized-coal-fired boiler facility according to  claim 1 , wherein
 the mixed gas flow is divided and flows into a carrier gas path that passes through a gas heater and a bypass carrier gas path that bypasses the gas heater, and   the mixed gas is then supplied to the coal pulverizer.   
     
     
         3 . The method for operating a pulverized-coal-fired boiler facility according to  claim 1 , further comprising extracting the boiler exhaust gas from the exhaust gas path disposed downstream of a desulfurization tower. 
     
     
         4 . The method for operating a pulverized-coal-fired boiler facility according to  claim 2 , further comprising extracting the boiler exhaust gas from the exhaust gas path disposed downstream of a desulfurization tower.