Experimental Model Development of Oxygen-Enriched Combustion Kinetics on Porous Coal Char and Non-Porous Graphite

Abstract

Abstract:The effect of oxygen-enriched air on low-rank coal char combustion was experimentally investigated. In this work, a coal-heating reactor equipped with a platinum wire mesh in the reaction chamber was used to analyze the combustion temperature, reaction time, and reaction kinetics. Increasing the oxygen content of the primary combustion air increased the combustion temperature and decreased the reaction time. As the oxygen content increased from 21% to 30%, the average temperature increased by 47.72 K at a setup temperature of 1673 K, and the reaction time decreased by 30.22% at the same temperature. The graphite sample exhibited similar trends in temperature and reaction time, although the degree of change was smaller because the pores produced during char devolatilization expanded the active surface available for oxidation of the char sample. A mathematical model was used to define the intrinsic kinetics of the reaction. As the oxygen content increased from 21% to 30%, the reaction rate of the low-rank coal char increased. These results were also compared with those of the graphite sample.

Thermal Behavior of Coal Used in Rotary Kiln and Its Combustion Intensification

“…The peak temperature is reduced from 906 K to 838 K, DTG max is increased from 15.72%/min to 18.86%/min, and burnout time is shortened from 7.45 min to 6.75 min when the oxygen content increased from 20% to 30%. Moreover, ignition temperature is also affected by oxygen-enrichment, decreasing from 757 K to 703 K. The presence of oxygen will reduce the force of the diffusion layer and oxygen-enrichment leads to faster reaction of fixed carbon and volatile material with oxygen to favorably enhance the combustion of coal [29]. The coal combustion process is easily regulated by oxygen content and can be obviously intensified by oxygen-enrichment.…”

Investigation of the apparent kinetics of air and oxy-fuel biomass combustion in a spout fluidised-bed reactor

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