Production method of solid fuel

Abstract

Provided is a method that produces a solid fuel having a relatively high strength from a powder fuel. The method includes: blending a coal-derived powder fuel with a pulverized fuel having a greater mean particle diameter than the coal-derived powder fuel to obtain a mixture; compression-molding the mixture to obtain a solid fuel; and pulverizing a part of the solid fuel, in which the part of the pulverized solid fuel is used as the pulverized fuel in the blending. A blending proportion of the pulverized fuel with respect to the blending mixture is preferably at least 5 mass % and at most 50 mass %. A cohesive fine coal having a superior cohesive property to the coal-derived powder fuel is preferably further blended in the blending. A blending proportion of the cohesive fine coal with respect to the blending mixture is preferably at least 5 mass % and at most 30 mass %.

1 : A production method of a solid fuel, the method comprising:
 blending a coal-derived powder fuel with a pulverized fuel having a greater mean particle diameter than the coal-derived powder fuel, thereby obtaining a mixture;   compression-molding the mixture, thereby obtaining a solid fuel; and   pulverizing a part of the solid fuel,   wherein the part of the solid fuel pulverized in the pulverizing is used as the pulverized fuel in the blending.   
     
     
         2 : The production method according to  claim 1 , wherein a blending proportion of the pulverized fuel with respect to the mixture obtained by the blending is greater than or equal to 5% by mass and less than or equal to 50% by mass. 
     
     
         3 : The production method according to  claim 1 , wherein a cohesive fine coal having a superior cohesive property to the coal-derived powder fuel is further blended in the blending. 
     
     
         4 : The production method according to  claim 3 , wherein a blending proportion of the cohesive fine coal with respect to the mixture obtained by the blending is greater than or equal to 5% by mass and less than or equal to 30% by mass. 
     
     
         5 : The production method according to  claim 3 , further comprising:
 measuring a strength of the solid fuel; and   adjusting a blending proportion of the cohesive fine coal in the blending based on the measured strength,   wherein the adjusting is performed by increasing the blending proportion of the cohesive fine coal when the measured strength is less than a predetermined lower limit and decreasing the blending proportion of the cohesive fine coal when the measured strength is greater than a predetermined upper limit.   
     
     
         6 : The production method according to  claim 1 , further comprising:
 measuring a production amount of the solid fuel; and   adjusting a blending proportion of the pulverized fuel in the blending based on the measured production amount.   
     
     
         7 : The production method according to  claim 1 , wherein in the blending, the coal-derived powder fuel and the pulverized fuel are fed to a mixer using a conveyor scale. 
     
     
         8 : The production method according to  claim 1 , wherein a modified coal obtained by thermally dehydrating a low-rank coal in oil is used as the coal-derived powder fuel, and a powdered low-rank coal is used as the cohesive fine coal.