PURPOSE: To restrict the adhesion and cohesion of powder particles after solid fuel is crushed and to prevent the powder particles from being adhered to and accumulated in equipment unit and pipings or the like by a method wherein the ashes in the boiler are mixed in the solid fuel at either one of the storage, supplying and crushing of the solid fuel in the combustion facility or at its upstream stage.

CONSTITUTION: Mixture including boiler ashes and solid fuel is crushed with a crusher machine 4, thereafter passed through a fuel-supplying line 5 and then supplied to the boiler combustion furnace 6. The discharged gas 7 generated in the boiler combustion furnace 6 is reacted with ammonia 9 in a denitrification reactor 8 and the nitrogen oxide contained in the discharged gas is converted to nontoxic nitrogen and water. Further, the discharged gas pass through a discharging gas line 14 after soot collected by an electrical dust collector 10 is removed, and then transmitted to the discharging gas denitrification device. A part of the collected soots and dusts is expelled out as boiler ashes 12 through a distributor 11 and the remaining boiler ashes pass through the circulation boiler ash line 13 and supplied to the mixing machine 2.