Comparison of Chars Obtained under Oxy-Fuel and Conventional Pulverized Coal Combustion Atmospheres

Abstract

The combustion of coal in conventional power plants produces large amounts of CO2 which contributes to the greenhouse effect. One of the ways to approach the CO2 emissions abatement is to burn the coal in an O2/CO2 atmosphere which eliminates the need of a separation step. In this study, two coals of different rank (a high volatile and a low volatile bituminous) have been burned in a drop tube reactor using O2/N2 and O2/CO2 mixtures with increasing oxygen content from 0 to 21%. Various oxygen concentrations have been selected for each set of experiments in order to follow both the progress of combustion and the influence of oxygen content in the devolatilization behavior of coal. Results show that a higher amount of O2 in CO2 than in N2 is needed to achieve similar burnout levels. Significant differences were found in the influence of oxygen content on the devolatilization behavior of the lower and higher rank coal. The limited amount of oxygen in the reacting atmosphere resulted in volatile release inhib...