Apparatus for spheroidizing pulverized coals

Abstract

The present invention relates to high-density coal-water mixed fuel and a producing method thereof and aims to reduce an amount of dispersant to be used in the coal-water mixed fuel having the good fluidity with the increased density and obtain the a coal-water mixed fuel from pulverized coals produced by dry milling at low cost. According to this invention, in case of obtaining the high-density coal-water mixed fuel such as a CWM by mixing the pulverized coals ground to provide a predetermined particle size distribution, water and the dispersant, the hydrophilic colloid which causes the protective effect with respect to the pulverized coals is added and mixed preferably before adding the dispersant so that the high-density coal-water mixed fuel which includes the hydrophilic colloid and a reduced amount of a surface active agent used can be provided. An amount of the hydrophilic colloid to be added is less than 1 wt % of the entire CWM and larger than an amount for causing reciprocal aggregation with the pulverized coals, or more preferably it is in the order from ppm to ppt. Further, when the pulverized coals are rubbed together and the angles thereof are shaved off for production from the pulverized coals, the pulverized coals are spheroidized without extremely being minimized from their original particle size, and superfine particles in the coal particles are generated, thereby enabling adjustment to provide a preferable particle size distribution as the CWM.

What is claimed is:  
     
         1 . A high-density coal-water mixed fuel obtained by mixing pulverized coals produced by grinding a coal so as to provide a predetermined particle size distribution, water and dispersant, including hydrophilic colloid causing the protective effect with respect to the pulverized coals.  
     
     
         2 . A high-density coal-water mixed fuel according to    claim 1   , wherein an amount of the hydrophilic colloid is less than 1 wt % of the water in the high-density coal-water mixed fuel and larger than an amount for causing reciprocal aggregation with the pulverized coals.  
     
     
         3 . A high-density coal-water mixed fuel according to    claim 1   , wherein an amount of the hydrophilic colloid is equal to or less than 1 ppm and equal to or more than 10 −4  ppt of the water in the high-density coal-water mixed fuel.  
     
     
         4 . A high-density coal-water mixed fuel according to    claim 1   , wherein an amount of the hydrophilic colloid is equal to or less than 1 ppb and equal to or more than 1 ppt of the water in the high-density coal-water mixed fuel.  
     
     
         5 . A method for producing the high-density coal-water mixed fuel obtained by mixing pulverized coals produced by grinding a coal so as to provide a predetermined particle size distribution, water and dispersant, including adding and mixing hydrophilic colloid causing the protective effect with respect to the pulverized coals.  
     
     
         6 . A method for producing the high-density coal-water mixed fuel according to    claim 5   , wherein the hydrophilic colloid is added to a mixture of the pulverized coals and the water and the dispersant is thereafter added to the mixture.  
     
     
         7 . A method for producing the high-density coal-water mixed fuel according to    claim 5    or    6   , wherein the pulverized coals obtained by dry milling are further abraded so as to be pushed and rubbed together so that the pulverized coals are spheroidized by scraping off their angles and superfine particles are generated.  
     
     
         8 . A method for producing the high-density coal-water mixed fuel according to    claim 5   , wherein an amount of the hydrophihc colloid is less than 1 wt % of the water in the high-density coal-water mixed fuel and larger than an amount for causing reciprocal aggregation with the pulverized coals.  
     
     
         9 . A method for producing the high-density coal-water mixed fuel according to    claim 5   , wherein an amount of the hydrophilic colloid is equal to or less than 1 ppm and equal to or more than 10 −4  ppt of the water of the high-density coal-water mixed fuel.  
     
     
         10 . A method for producing the high-density coal-water mixed fuel according to    claim 5   , wherein an amount of the hydrophilic colloid is not more than 1 ppb and not less than 1 ppt of the water in the high-density coal-water mixed fuel.  
     
     
         11 . A method for producing the high-density coal-water mixed fuel comprising the steps of: obtaining pulverized coals having a particle size substantially equal to or less than a predetermined value by dry-milling a coal by a mill; and using a spheroidizing apparatus for pushing and rubbing the pulverized coals to rub the pulverized coals together in order to spheroidize the pulverized coals by scraping off their angles and generate superfine particles.  
     
     
         12 . A method for producing the high-density coal-water mixed fuel according to    claim 11   , wherein the spheroidizing apparatus comprises first and second members having a small gap between their opposed surfaces, the first and second members are opposed to each other with a fixed gap therebetween and capable of relative motion, and the pulverized coals held between the opposed surfaces are pushed and rubbed to be abraded together so that angles of the pulverized coals are scraped off for spheroidization and superfine particles are generated.