Experimental study on pore structure changing of gasified coal char under combustion

The combustion characters and pore structure changing of the gasified coal char obtained from the secondary cyclone of the Jincheng industrial gasifier were experimental studied at high temperature in a simulator of high-temperature entrained flow reactor. Gasified Chars were burned at the temperature of 1273 and 1573K, the oxygen contain of 5% and 20% and sampled along the reactor at different axial residence time. Automatic adsorption instrument (ASAP 2020) was employed to measure absorption isotherms of sampled chars. Cryogenic nitrogen absorption isotherms, parameters such as BET specific surface area, BJH pore volume and average pore diameter were measured and analyzed. Surface morphology of the char was further studied by scanning electron microscopy (SEM) and with fractal theory. The isotherms of char samples at different residence time were all type II. Higher temperature and more oxygen concentration both can improve the changing of char pore structure. The changing of specific surface areas during the combustion is consistent with the trends of reacting rates for chars. The char reacting rates in finial reacting period is mainly dominated by char intrinsic reactivity.