CATALYTIC EFFECTS OF ASH COMPONENTS IN LOW RANK COAL-GASIFICATION .1. GASIFICATION WITH CARBON-DIOXIDE

This work investigates the influence of catalytically effective ash components on coal gasification. A lignite, whose ash did not contain aluminium, was deashed with hydrochloric acid. Calcium, sodium, potassium, and iron were then replaced in the lignite according to their original percentages, both individually and in combination with each other. Gasification was carried out in a differential circulation apparatus at normal pressure and 1173 K. Changes in the mass of the specimen were directly registered by a spring balance, and the rate of carbon conversion was determined. The conversion rate for ash-containing lignite was 30-50 times higher than that for deashed lignite. The rate of conversion when sodium and potassium were used in combination was considerably higher than the sum of the conversion rates when these elements were used alone. When the lignite was impregnated with the sodium-calcium combination, the conversion rate of the ash-containing lignite was attained at more than 60% carbon conversion; this is in good agreement with the dependence on coal conversion. When the lignite was impregnated with all four components, the rate of conversion was higher, within the range of low carbon conversion, than that achieved by impregnation with sodium and calcium. However, the conversion rate of the ash-containing original lignite was only attained at higher carbon conversion. © 1990.