Volatilization of Arsenic in Coal during Isothermal Oxy-Fuel Combustion

Arsenic volatilization characteristics of SJS bituminous coal were carried out in a customized isothermal thermogravimetric experimental system at 600–1400 °C under different oxy-fuel atmospheres. The mineralogical and morphological characterization of ash samples were analyzed using XRD and SEM instruments. Different from conventional nonisothermal mass loss curves by TG analyzer, the isothermal mass loss curves of coal did not show a clear process of moisture removal and devolatilization. With the increase of combustion temperature, the isothermal mass loss curve of SJS coal shifted to the left gradually and the burnout time shortened at the same time, whereas the mass loss curves of arsenic showed different tendencies at <900 °C and >900 °C stages. At the <900 °C stage, the effect of O 2 dominated. A higher O 2 ratio led to the larger volatile proportion of arsenic, irrespective of CO 2 content. At the >900 °C stage, the volatilization of arsenic was delayed in oxy-fuel condition but with a higher release rate; thus the volatility ratio of arsenic in oxy-fuel combustion was even larger than that of conventional air/flue gas combustion.