連続装置によるビクトリア褐炭の液化 (III)

溶剤/褐炭比とガス流量の液化反応に及ぼす影響

抄録

The effects of solvent/coal ratio (S/C) and gas flow rate (GFR) on liquefaction reaction of Victorian brown coal were investigated using a process development unit (PDU) with three stirred tank reactors. For all experiments, the iron/sulfur catalyst (Fe₂O₃, S/Fe atomic ratio 1.2) was added 3wt.% as Fe and H2 gas was fed 10wt.% on moisture and ash free (maf) coal. The S/C (maf) ratio by weight in the feed slurry ranged from 2.0 to 3.0 and the gas in the gas-liquid separator was circulated to the first reactor to increase the GFR in the reactors.
The distillate yield (b. p.<420°C) and hydrogen efficiency increased with a decrease in the S/C at lower GFR condition without gas circulation. An increase in the GFR by the gas circulation markedly improved the distillate yield and hydrogen efficiency, effectively converting the heavier fraction derived from the coal to the distillate. This GFR effect was considerably greater than that of the S/C, and the S/C effects disappeared at higher GFR conditions. These results were explained by higher contents of the catalyst and heavy fraction in the liquid phase in the reactors under the conditions of lower S/C and higher GFR because the amounts of the added catalyst and fed H2 were fixed constant to the coal in the feed slurry. The increase in the GFR markedly accelerated the vaporization of solvent fraction and concentrated the catalyst and heavy fraction in the remaining liquid phase in the reactors. Thus, at higher GFR conditions, the actual residence time of the liquid phase in the reactors was prolonged and the liquefaction reaction was markedly enhanced.