Experimental And Numerical Study Of Combustion Characteristic Of Single Char Particle In O₂/CO₂and O₂/H₂O Atmospheres

The global warming caused by the CO2resulted from mineral fuel combustion isgradually threatening the environment of human, and the CO2emission reduction should becarried out imminently. As a novel combustion, the Oxy-steam combustion can overcomethe problems presented in Oxy-fuel combustion which is on the behalf of O2/CO2. In thispaper, it is devoted to study the combustion characteristic of single char particle in O2/H2Oand O2/CO2atmospheres by using mainly numerical simulation and experiment method.During the simulation of the steady combustion of single char particle in O2/H2O andO2/CO2quiescent atmospheres, it’s found that the content of CO produced from char burnincrease with increasing oxygen concentration. And in O2/H2O atmospheres the content ofH2reached its maximum when the oxygen concentration is0.3. However, when the oxygenconcentration continues to increase, the content of H2on the particle surface reduced andchanged little in the gas phase. With the increasing of ambient temperature, the content ofCO, H2declined and on the contrary, the content of CO2and temperature rises. However,when the ambient temperature is in the range of1273K to1373K, the content of CO, H2produced from char burn barely changed and the char mass consumption rate rises inO2/H2O atmospheres.The experimental research of the ignition process of coal char in O2/H2O, O2/N2andO2/CO2atmospheres is used by STA. The results showed that increasing oxygenconcentration can accelerate the process of ignition and combustion of coal char. Thecomparison between experiment and simulation results show the weight loss rate of charreached maximum in O2/H2O atmospheres, middle in O2/N2atmospheres and minimum inO2/CO2atmospheres with the same oxygen concentration. The results obtained fromnumerical study of unsteady ignition process of single char particle in O2/H2O, O2/N2andO2/CO2atmospheres revealed that an increasing in oxygen concentration can accelerate thereaction rate, and it is conducive to fire. Meanwhile, the content of CO, CO2and H2on theparticle surface increases. With the same oxygen concentration, the char mass consumptionrate in O2/H2O atmospheres is higher than it in O2/CO2and O2/N2.