Method for producing ashless coal

Abstract

Provided is a method for producing ashless coal, said method comprising a slurry preparation step in which a slurry is prepared by mixing coal and a solvent, the coal that is included in the slurry is dewatered, and the temperature of the slurry is increased. The slurry preparation step comprises a preparation/dewatering step and a preparation/temperature increase step. In the preparation/dewatering step, preparation of the slurry and dewatering of the coal are performed by mixing coal and a liquid solvent that is circulated during a circulation step. In the preparation/temperature increase step, the slurry is prepared and the temperature of the slurry is increased by mixing the slurry with solvent vapor that is circulated during the circulation step.

1 . A method for producing ashless coal, the method comprising:
 mixing coal and a solvent to prepare a slurry, and performing a dehydration of the coal contained in the slurry and a temperature increase of the slurry;   heating the slurry to extract a solvent-soluble component of the coal, to obtain an extracted slurry;   separating the extracted slurry into a solution containing the solvent-soluble component of the coal and a solid-content concentrated liquid having concentrated therein a solvent-insoluble component of the coal;   evaporating and separating the solvent from the solution to obtain ashless coal; and   circulating the solvent to a slurry preparation,   wherein the slurry preparation comprises:   mixing liquid solvent of the circulating step with the coal to prepare the slurry and dehydrate the coal; and   mixing vapor solvent of the circulating step with the slurry to increase the temperature increase of the slurry.   
     
     
         2 . The method according to  claim 1 , wherein, during the mixing of the vapor solvent with the slurry, a concentration of the slurry is adjusted to be an inlet concentration suitable to extract the solvent-soluble component of the coal. 
     
     
         3 . The method according to  claim 1 , wherein, during the mixing of the vapor solvent with the slurry, a temperature of the slurry is increased to an inlet temperature suitable for mixing the coal with the solvent. 
     
     
         4 . The method according to  claim 1 , wherein the vapor solvent of the circulating step and the slurry are mixed by a venturi scrubber. 
     
     
         5 . The method according to  claim 1 , further comprising:
 feeding coal, to be mixed with the solvent to prepare the slurry, by way of a coal feed line; and   flowing a purge gas into the coal feed line to thereby discharge a vapor produced in the mixing step from the coal feed line.   
     
     
         6 . The method according to  claim 2 , wherein, during the mixing of the vapor solvent with the slurry, a temperature of the slurry is increased to an inlet temperature suitable for mixing the coal with the solvent.