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Quick pyrolysis of a massive coal sample via rapid infrared heating

Xu, Shipei, Zeng, Xi, Han, Zhennan, Cheng, Jiguang, Wu, Rongcheng, Chen, Zhaohui, Masĕk, Ondřej, Fan, Xianfeng, Xu, Guangwen
Applied energy 2019 v.242 pp. 732-740
coal, heat, hydrogen, oils, pyrolysis, temperature, China
There are few studies about pyrolysis with the a massive sample at high heating rates to obtain liquid and gas products. This study adopted a newly designed small fixed bed reactor mounted with infrared heating to minimize secondary reactions to volatiles and further to investigate the pyrolysis of Xinjiang Naomaohu coal in terms of pyrolysis products characterization at different temperatures and heating rates. Infrared heating has good penetrability to heat the inner layer of the sample at a quick rate of up to 1723 °C/min in the particle bed. For the tested reactor at 700 °C, raising the heating rate decreased the yields of gas and char and increased the yield of tar. The realized tar yield was higher than that in Gray-King (G-K) assay at heating rates above 18 °C/min. For the heating rate of 667 °C/min at the pyrolysis temperature of 700 °C, the obtained maximum yield of tar was 134% of the G-K assay oil yield. Overall, increasing the heating rate decreased char yield and increased the production of total volatiles. At higher heating rates, the tar became heavier, while at higher pyrolysis temperatures, it produced more light tar. The extraction rate of hydrogen from coal was found to be subject to a linear relationship with pyrolysis gas yield.