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The copyrolysis and cocombustion behaviors of Pingshuo coal and the biomasses (sawdust and rice straw) have been investigated using a thermogravimetric analyzer. The experimental results indicate that there exist synergetic effects between the biomasses and Pingshuo coal during their coconversion process. The initial temperature of volatile emission from Pingshuo coal and the temperature corresponding to the maximum conversion rate during the copyrolysis change with the biomass mixture ratio. Moreover, it can be deduced from the comparison between the experimental and the calculated DTG curves that the copyrolysis process is not the sum of Pingshuo coal and the biomass conversion. During their cocombustion process, the larger the mixture ratio of the biomass is, the lower the ignition temperature and the burnout temperature are, and the larger the combustion characteristic index is. In addition, the maximum combustion rate and the combustion performance are the best when the mixture ratio of the biomass is 70 wt % in the research. Moreover, the activation energy and the frequency factor of the copyrolysis and the cocombustion were calculated by the Coats–Redfern method and the first-order reaction model. The results show that the activation energy and the frequency factor change with the mixture ratio of the biomass, and the regularity was consistent with the above-mentioned conclusions. Therefore, it can be deduced that the addition of the biomass can facilitate the pyrolysis and the combustion of Pingshuo coal, and improve the utilization field of Pingshuo coal.

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The effect of pyrolysis conditions on char reactivity was studied in this paper. The char samples were prepared in a N2 atmosphere from the vitrinite constituents of two bituminous coals (YX and JJ) and their demineralized samples at different temperatures (800−1200 °C) and for different residence times. The effect of pyrolysis intensity on the carbon microstructure in the resulting char was characterized by the X-ray diffraction (XRD) technique. The reactivity of the char samples prepared under different pyrolysis conditions was measured by isothermal thermogravimetric analysis methods in an air atmosphere. The results show that the reactivity of the coal char decreases with increasing pyrolysis intensity and, when the pyrolysis temperature is high enough, the reactivity of the chars prepared from two coals and their demineralized samples tend to be the same. With increasing pyrolysis intensity, the growth of the carbon microstructure, accompanied by diminishing catalytic capability of minerals, results in the decrease in char reactivity.

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