Study on the thermal conversion characteristics of demineralized coal char under pressurized O₂/H₂O atmosphere

The pressurized O₂/H₂O combustion technology can achieve nearly zero CO₂ emissions during coal-fired power generation. In order to explore the influence of pressurized O₂/H₂O conditions on the thermal conversion characteristics of pulverized coal, Zhundong demineralized coal was used as raw material to prepare pyrolyzed char at 0.5 MPa and then the O₂/H₂O combustion experiments with different H₂O concentration (0–40%), temperature (850-1000℃) and residence time (100–250 s) were carried out under the same pressure by a pressurized horizontal furnace. The carbon transformation, pore structure, carbon skeleton structure, and surface functional group structure of char under different experimental conditions were obtained by weighing method, Nitrogen adsorption test, Raman, and X-ray photoelectron spectroscopy methods, respectively. In addition, the reactivity of char was tested by thermogravimetric analyzer and micro fluidized bed reaction analyzer (MFBRA) to explore the relationship between the char structure and reactivity.