1997 Volume 76 Issue 4 Pages 297-304
The effects of solvent/coal ratio on slurry viscosity and liquefaction reaction of Victorian brown coal were investigated using a solvent derived from the primary hydrogenation of the two-stage brown coal liquefaction (BCL) process. The liquefaction reaction was carried out in the presence of iron/sulfur catalyst with an autoclave of 5 L. The amount of catalyst added was 3 wt% on moisture and ash free (maf) coal as Fe, and the S/Fe atomic ratio was 1.2. The slurry viscosity was measured under N2 pressure with a high temperature and pressure viscometer.
The distillate yield (b.p.<420°C) and hydrogen efficiency increased and the C1-C4 yield decreased with a decrease in the solvent/coal (maf) ratio ranging from 3.0 to 1.7. The effects of the ratio was large at high temperature (460°C) compared to that at low temperature (430°C). The slurry viscosity increased with the decrease in the ratio and decreased monotonically as temperature increased.
These results show that the solvent/coal ratio of the feed slurry in the brown coal liquefaction process should be small when the slurry can be transported by a pump for the liquefaction because it improves the efficiencies of processing, hydrogen consumption and distillate yield.