Supercritical water gasification of Victorian brown coal: Experimental characterisation

Supercritical water gasification is an innovative thermochemical conversion method for converting wet feedstocks into hydrogen-rich gaseous products. The non-catalytic gasification characteristics of Victorian brown coal were investigated in supercritical water by using a novel immersion technique with quartz batch reactors. Various operating parameters such as temperature, feed concentration and reaction time were varied to investigate their effect on the gasification behaviour. Gas yields, carbon gasification efficiency and the total gasification efficiency increased with increasing temperature and reaction time, and decreasing feed concentration. The mole fraction of hydrogen in the product gases was lowest at 600 °C, and increased to over 30 % at a temperature of 800 °C. Varying parameters, especially reaction time, did not improve the coal utilisation for gas production significantly and the measured data showed a large deviation from the equilibrium level.