Thermogravimetric assessment of combustion characteristics of blends of a coal with different biomass chars

In connection to future energy demand and fossil fuel crisis particularly in India, biomass is gaining its importance for possible use as co-fuel. In India varieties of biomass products are available which do have tremendous potentiality for co-combustion with pulverized coal. Based on the emerging need, detailed investigations are felt necessary to examine the compatibility of different kind of biomass with coal and to select suitable blend composition(s) before utilizing those biomass products in utility operation as co-fuels. This study elaborates the lab scale findings of combustion experiments in DSC-TGA apparatus with a typical Indian coal, two biomass samples and low temperature biomass chars (300 and 450 degrees C) as well as with 'blends of low temperature chars and coal'. Conventional TGA parameters, activation energy and ignition index of different blends were estimated which provided elaborate information on their basic combustion features. Results of non-isothermal combustion studies in general depict that blends containing less than 50% biomass char are better performing as compared those with higher biomass char content. Lowering of activation energy and improvement of reactivity in major combustion zone were also observed in the coal/biomass-char blends. Improvement of ignition index of the blends of coal with 300 degrees C chars over expected weighted mean values was noticed. Such attempts may help to identify appropriate biomass-type, blend proportion for a given coal and to derive some specific advantages with respect to particular combustion practice. (C) 2009 Elsevier B.V. All rights reserved.