METHOD OF PREPARING LOW-SULPHUR LOW-ASH FUEL

摘要

1525909 Treating coal KELLER CORP 20 May 1977 [20 May 1976] 21382/77 Headings C5G and C5E Low-sulphur, low-ash fuel is prepared from coal and organic constituents are extracted from the coal by (a) comminuting the coal in the presence of C 1 -C 4 alcohol to a size such that a major part of the coal is minus 100 Tyler mesh, (b) forming a mixture of the resulting comminuted coal and the alcohol, the mixture containing at least 40 wt. per cent of the coal, (c) separating the mixture into 3 streams, namely a first underflow stream (comprising primarily a first slurry of high density solids), a first middling stream (comprising primarily a first slurry of the coal particles), and a first overflow stream (comprising primarily the alcohol, a liquor of constituents dissolved from the comminuted coal in the alcohol and colloidal constituents suspended in the alcohol and the liquor), (d) separating the first underflow into a second underflow (comprising a second viscous slurry of sulphur and solids that would form ash residue if burned with the coal) and a second overflow (comprising a dilute slurry of coal in the alcohol and the liquor of constituents dissolved from the comminuted coal in the alcohol), (e) separating the first middling stream into a third underflow (comprising a second slurry of high density solids), a second middling stream (comprising primarily a second slurry of the coal with only a minor proportion of the high density solids and the sulphur therein) and a third overflow (comprising primarily the alcohol, a liquor comprising constituents dissolved in the alcohol and colloidal constituents suspended in the alcohol and the liquor), (f) separating the first overflow into a fourth underflow and a fourth overflow, (g) refining the fourth overflow into respective desired organic constituents and the alcohol, and (h) forming a low-sulphur, low-ash fuel from the second middling stream. Step (h) may involve producing a thixotropic dispersion of coal in alcohol, pressuring the dispersion, heating the dispersion to 140 to 180‹ F. and flashing to atmospheric pressure to flash off and free the alcohol and organic gas including methane and to produce puffed coal particles that burn readily with a high efficiency and produce a hot flame with very little pollution.