To increase coal utilization, it is essential to reduce CO_2 emission by developing moreefficient coal fining systems, such as gas turbines, than the conventional PCF systems. Inorder to fire coals in gas turbines, however, coal should be ash-free. As a fundamentalstudy for producing Ash- free coal, coal extraction and filtration tests were performed usingseveral kinds of coals and organic solvents.High temperature was required to extract a considerable amount of coal, and at the hightemperature, thermal decomposition of coal could not be avoided. In that temperature,NMP (N-methylpyrrolidone) was unable to be recovered due to the coal-solvent linkage,and a part of tetralin was changed to naphthalene by hydrogen transfer to coal. 1-MN(1-methylnaphthalene) could be preferable as an extraction solvent from industrial point ofview.Several hundred ppm of ash metals were remained in extracted coal. Major metallicelements remained in extracted coal were Si and Fe. It was suggested that organo-metalliccompounds, such as organo-Si compounds, were dissolved into solvent.
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