LIQUEFACTION OF COALS AND MACERAL CONCENTRATES IN A FLOWING-SOLVENT REACTOR

A flowing-solvent liquefaction reactor with a continuous solvent sweep through a fixed bed of coal has been developed. The reactor is heated by computer-controlled direct electrical resistance heating, allowing the application of variable heating rates between 0.1 and 10 K/s to t emperatures up to 450-degrees-C and holding times at peak temperature between zero and 1600 s. In contrast to liquefaction experiments using closed (batch) reactors, where products remain within the reactor for the duration of the experiment, solubilised liquefaction products are continuously swept out of the reaction zone, thus minimising the prob ability of secondary reactions. The apparatus has been proved by perfo rming liquefaction experiments on a selection of European and American coals and maceral concentrates. Conversion data indicate that, unlike in microbomb experiments performed under similar conditions, high tem perature, long residence time runs in the flowing solvent reactor show no increase in solid residue. Preliminary size exclusion chromatograp hy results have shown that, in contrast with trends observed in microb omb reactors, products from the flowing-solvent reactor increase in mo lecular mass with increasing reaction temperature and time. The work h as been extended to cover the pyrolysis and liquefaction of maceral gr oup concentrates, showing detailed differences between the behaviour o f the lithotypes under different sets of reaction conditions.