High-temperature fast pyrolysis of coal: An applied basic research using thermal gravimetric analyzer and the downer reactor

The study explored the influence of temperature and particle size on the high-temperature fast pyrolysis behaviors of Shenmu(Yulin) coal through thermal gravimetric analyzer and the downer reactor. Results of TG-FTIR show that the thermal hysteresis causing by high heating rate make TG and DTG curves shift to high-temperature zone. The infrared spectra reveal that the release characteristics of typical products and functional groups are consistent with the weight loss curve. Moreover, experimental results of the downer reactor reveal that the content of coal-char and coal-tar decreased and coal-gas increased with the increment of temperature. Better syngas can be obtained at 900 °C. The yield of coal-char firstly increases and then decreases with the decrease of particle size and the coal-tar is opposite. More importantly, during the pyrolysis process of 35–60 mesh coal, the largest amount of coal-char and the smallest amount of coal-tar are not only obtained, but high-quality syngas is also obtained. Through the characterization of coal-tar, it is found that coal-tar is mainly composed of aromatic compounds, and the content can reach more than 50%. Moreover, the change of infrared absorption intensity of O–H, CO and C–O groups in coal-char varies with the change in pyrolysis parameters.