Chemical composition of fuels and emissions from a coal plus tire combustion experiment in a power station

Medium-sulfur bituminous coal and a mixture of 95 wt.% coal plus 5 wt.% tire-derived fuel (TDF) in the form of shredded automotive tires were combusted in a stoker boiler under the same conditions. This paper presents quantitative chemical compositions of the fuels and of the gaseous and particulate emissions. The coal + TDF mixture is considerably richer in Zn than the pure coal as a result of the high Zn content of the shredded tires (similar to 1 wt.% Zn). Atmospheric emissions of Zn increased from 15 g/h to nearly 2.4 kg/h when coal + TDF was combusted. Similarly, emissions of most other metals and metalloids, as well as those of HCl increased when TDF (similar to 3000 ppm Cl) was added. The enhanced metal emissions might be due to formation of gaseous metal chloride species in the stack gases. On the other hand, emissions of CO decreased slightly, whereas those of NO(x), SO(2), and total particulate matter remained virtually unchanged. These results help in assessing the environmental impact of energy recovery from scrap tires in stoker boilers. (c) 2006 Elsevier Ltd. All rights reserved.