Online monitoring of the burning characteristics of single pulverized coal particle in O2/N2 and O2/CO2 environments

Abstract

The objective of this study is to compare the ignition and burning characteristics such as burnout times of volatiles and char, and ignition mechanism of single pulverized coal particle burning in air (O2/N2) and oxy (O2/CO2) environments. An entrained flow reactor with photo detector has been employed for this study. This technique involves online monitoring of radiation emission from an individual coal particle. Individual particles of sub-bituminous or lignite coal particle with size in the ranges of 106 - 125 micron and 180 - 212 micron particles have been injected into an air (O2/N2) or oxy (O2/CO2) environment inside an entrained flow reactor. The oxygen concentration in the ambient gas is varied between 10% to 50% by volume. The volatile and char burnout times have been obtained from time histories estimated from the radiation emitted by the particle. The results show an obvious increase in the burning rates of volatiles and char with increasing oxygen concentration. Further, when compared to N2 atmosphere, the burning rate and radiation intensity are found to be lower in CO2 atmosphere, especially at lower oxygen concentrations. An indication of the possible ignition mechanism has been outlined from the percentages of single and double peaks observed in the radiation emission histories. The complete experimental investigation shows that the burning rates of both volatiles and char are predominantly affected by the oxygen concentration, particle size and gas temperature. The theoretical results from a single particle model has been used to validate the trends and the combustion durations obtained from the present experimental study and is published as a separate manuscript.