Combustion characteristics of single cylindrical RDF

As an approach to waste treatment and enemy utilization refuse derived fuel s (RDF) have been developed as an alternative fuel for power generation. Co mbustion tests of RDF conducted in fluidized bed combustors and stokers hav e shown significantly different combustion characteristics and air pollutio n emission levels. To explain the differences from the view point of reacti on mechanism of RDF, the combustion characteristics of a single RDF pellet (20 mm in diameter and 40 mm in length) made from municipal solid waste are investigated in an electric heating reactor (53 mm in inner diameter and 1 .000 mm in length). The weight loss and the temperature profiles of the RDF pellet were measured under two groups of heating conditions: constant heat ing rate condition and instantaneous heating condition. It is found that the combustion of RDF progressed in two stages. In the fir st stage, volatile matters are decomposed and then burnt in Ras phase, and the weight loss rate of RDF significantly depends on the heating rate. The temperature difference between the surface and the inner RDF is small and t hermal decomposition is the dominant process under smaller heating rate, Ho wever, considerable temperature difference between the surface and the inne r is observed, and the heat transfer in RDF is the dominant process under t he instantaneous heating condition. The ignition temperature of the RDF use d in this work is around 480 degrees C. In the secund stage, fixed carbon i s burnt in the solid phase, and the weight loss rate and the temperature pr ofile in RDF are strongly affected by oxygen concentrations in the ambient lias. At higher oxygen concentrations, the heat of combustion is accumulate d in RDF so that a high temperature peak is observed.