Method for increasing calorific value of low-grade coals

Abstract

To provide less expensive and non-polluting coals of which calorific values are increased by improving composition of coals having high moisture content and low fire power, such as peat and lignite, to thereby increase combustion calorie. Materials of coals are heated in a predetermined temperature range in an oxygen-free atmosphere while injecting inactive gas, and elements except for carbon in the atmosphere and in the coals are individually separated by thermal decomposition in the order from an element having a lower decomposition temperature at a temperature of 450 degrees C. or lower so as to obtain upgraded coals. Since the carbon composing the upgraded coals has strong activity, the upgraded coals have quality equivalent or greater than that of the coal of ordinary quality and demonstrate combustion efficiency that has been significantly improved from those of the materials before upgrading.

What is claimed is: 
     
         1 . A method for increasing calorific value of low-grade coals, comprising:
 putting materials of coals in an airtight chamber in an inert atmosphere;   as a first stage, keeping a temperature of the materials of the coals at from 100 to 150 degrees C. so that moisture content is vaporized sufficiently and the vaporized moisture content (vapor) is exhausted from the airtight chamber;   at the same time, injecting the same amount of inert gas as that of the exhausted vapor in the airtight chamber to always keep the inside of the airtight chamber airtight and in an inert atmosphere;   moreover, successively heating the coals having been in a fully dried state up to temperatures from 350 to 450 degrees C. to thermally decompose elements contained in the materials,   individually separating expected elements except for carbon in the atmosphere and in the organic material from bonding with carbon by thermal decomposition in the order from an element having a lower decomposition temperature at a temperature of 450 degrees C. or lower, and exhausting the elements each time of separation to outside of the atmosphere while keeping in an inert atmosphere;   at the same time, injecting the same amount of inert gas as that of the exhausted separated elements in the airtight chamber to always keep the inside of the airtight chamber airtight and in an inert atmosphere and   moreover, sealing the obtained upgraded coals in a bulk state in a cartridge while keeping in an inert atmosphere.   
     
     
         2 . The method for increasing calorific value of low-grade coals according to  claim 1 , wherein the coals are ground into ultra-fine grains in an inert atmosphere at a temperature of 450 degrees C. or lower in a process before the upgraded coals are put in the cartridge in a sealed state. 
     
     
         3 . The method for increasing calorific value low-grade coals according to  claim 1 , wherein the materials are one of peat and lignite.