Coal for boiler fuel

Abstract

To provide a coal for a boiler fuel ( 10 ) used as a fuel for a coal-fired boiler, the coal for a boiler fuel comprising a reformed coal ( 10 ) comprising a raw coal ( 2 ) and calcium ion-exchanged on a raw coal ( 2 ). The raw coal ( 2 ) comprises a lignite or a subbituminous coal, and the amount of calcium is an equimolar amount relative to the molar amount of sulfur contained in the raw coal ( 2 ).

1 . A coal for a boiler fuel used as a fuel for a coal-fired boiler, the coal for a boiler fuel comprising a reformed coal, the reformed coal comprising a raw coal and calcium ion-exchanged on the raw coal, the raw coal comprising a lignite or a sub-bituminous coal, and an amount of the calcium being not less than an equimolar amount relative to a molar amount of sulfur in the raw coal. 
     
     
         2 . The coal for a boiler fuel according to  claim 1 , wherein the reformed coal further ion-exchanges iron, and an amount ratio of the iron being in a range from 0.1 to 5 wt % relative to a dry-weight of the raw coal. 
     
     
         3 . The coal for a boiler fuel according to  claim 1 , wherein the reformed coal includes ion-exchanged calcium in a range from 4 to 10 wt % relative to a dry-weight of the raw coal, and the coal for a boiler fuel comprises a mixed coal, the mixed coal being a mixture of a basic coal and the reformed coal, the basic coal comprising at least one kind from a bituminous coal, a subbituminous coal and a lignite, and an amount ratio of the reformed coal is in a range from 10 to 50 wt %. 
     
     
         4 . The coal for a boiler fuel according to  claim 1 , wherein the coal for a boiler fuel is treated with pyrolysis treatment. 
     
     
         5 . The coal for a boiler fuel according to  claim 4 , wherein the coal for a boiler fuel is further treated with deactivation treatment.