FLASH PYROLYSIS OF COALS .1. DEVOLATILIZATION OF A VICTORIAN BROWN COAL IN A SMALL FLUIDIZED-BED REACTOR

The devolatilization behaviour of finely-ground (< 0.2 mm) Loy Yang brown coal was investigated under rapid heating conditions using a small-scale fluidized-bed pyrolyser. The pyrolyser operated continuously, coal being fed at rates of 1-3 g/h directly into a bed of sand fluidized by nitrogen. Particle heating rates probably exceeded 104 °C/s. The yields of tar, C1-C3 hydrocarbons and total volatile matter are reported for a pyrolyser-temperature range of 435 to 900 °C. A maximum tar yield of 23% w/w (dry ash-free coal), 60% more than the Fischer assay, was obtained at 580 °C. Yields of C1-C3 hydrocarbons increased with increasing temperature, reaching 8% at 900 °C. Elemental analyses showed that the composition of the tar and char products was strongly dependent on pyrolysis temperature. The effects on the devolatilization behaviour of the coal produced by the moisture associated with the coal, by hydrogen, and by the replacement of the sand by a fluidized bed of petroleum coke were investigated. © 1979.