Co-combustion studies for potential application of sawdust or its low temperature char as co-fuel with coal

Globally there is an increasing trend towards the co-combustion of coal and biomass for production of energy. Disadvantage in power plant operation in India arising from the high ash content of coals recommends the potential use of biomass as a co-fuel. Co-combustion of biomass with pulverized coal is an important area under the clean energy development program and the renewable energy development program in India and in some other countries also. Biomass blending with coal still demands investigation for possible application in existing pulverized fuel fired boiler. Basically a comparative assessment of the combustion performance for two types of binary blends viz. 'coal-sawdust (SD)' and 'coal-SD char' have been done in this study using a Thermogravimetric analyzer (TGA) and a Drop Tube Furnace (DTF), based on which judicial selection of blends may be made possible. Blends of either of the above fuels showed better performance in terms of major TGA-reactivity indices, ignition index and DTF-burn out efficiency as compared to coal-based performance (as bench mark). Activation energy for co-combustion in TGA showed synergistic effect. Between the two options of blend types, 'coal-SD char' appeared to be superior to the other one. Based on the fuel characteristics as well operational issues, use of SD-char may also be considered as preferred option.