Key words: supercritical water, brown coal, conversion, sulfur and oxygen removal
Conversion of brown coal in sub- and supercritical water at 310÷460 °C and pressures up to 30 MPa in the cyclic pressurization and depressurization modes is studied. The temperature dependences of coal organic matter (COM) conversion, yield of volatile and condensed products are obtained. Temperature dependence of condensed substances yield has a maximum at 370 °C. At rising temperature the fraction of high-molecular substances in condensed products is increased. Cumulative conversion of COM into volatile and condensed products at heating to 460 °С was correspondingly 31.4 and 8.6 %. According to the data of mass-spectrometric analysis of volatile products, elemental analysis of initial coal, carbonaceous residue after conversion and condensed products, 82.3 % of oxygen and 74.7 % of sulfur are removed from COM. The main products of conversion of oxygen and sulfur containing groups are CO2 and H2S.
doi:10.1134/S1990793111080069