Combustion of Carbonizate with Biowaste from Birch Processing: Thermal Analysis

Abstract

New approaches to thermal energy generation are necessary for reasons of resource conservation and environmental protection. One option is to convert coal-fueled boilers to mixtures based on coal and biomass or to mixtures with more efficient nontraditional fuels. However, that entails expansion of experimental resources and research. In the present work, the main stages in the combustion of carbonizates, biomass, and their mixtures are analyzed and the main stages in the combustion of such mixtures with nonisothermal heating are determined, taking account of synergy between the components. Carbonizate obtained by gasification of Chernogorsky coal, birch shavings, and their mixtures are subjected to thermal analysis in an oxidative medium, with heating at 20°C/min. The basic combustion characteristics are established: the ignition temperature of the volatiles and coke residue; the temperature at which combustion ends; the maximum rate of mass loss and the corresponding temperature; and the combustion index, which permits comparison of the combustibility of different fuels. The ignition temperature is 45% higher for the carbonizates than for birch shavings; the combustion index is lower by a factor of 25. The total combustion time is greater for the mixture than for individual fuels. The most energy-efficient fuel mixture is identified. Adding biomass to carbonizates may improve not only the combustion characteristics of the carbonizates but the environmental characteristics, thanks to the low ash content and the minimal sulfur and nitrogen content in the biomass waste.