Reaction characteristics of Shenmu coal pyrolysis volatiles with an iron-based oxygen carrier in a two-stage fixed-bed reactor
2022
Hu, Donghai | Huang, Jiejie | Zhao, Jiantao | Wang, Zhiqing | Yu, Zhongliang | Xiao, Haicheng | Bai, Hongcun | Li, Chunyu | Fang, Yitian
The reaction of volatiles with oxygen carriers (OCs) is a common issue in the chemical looping combustion of coal or chemical looping reforming of hot pyrolysis gas. A two-stage fixed-bed reactor was used to determine the characteristics of the reaction of pyrolysis volatiles of Shenmu coal with an Fe-based OC. The effects of the oxygen/carbon ratio (O/C, φ, 0–1.31) and temperature (750–900 °C) on the three-phase products (carbon deposition, tar, and gas) were systematically studied. The results showed that an increase in φ caused a decrease in the carbon content in tar, whereas carbon deposition and the gaseous carbon content increased. Moreover, the amount of reducing gases slowly decreased while CO₂ significantly increased, indicating that the increase in CO₂ mainly originates from the carbon in tar. Additionally, phenols decreased fast, but naphthalene decreased rapidly at φ > 0.63. Rise in temperature decreased carbon deposition, and tar substances, whereas increased the CO content, notably, naphthalene significantly decreased only when the temperature exceeded 800 °C. The reaction of volatiles with OCs consisted of volatiles complete oxidation, tar catalytic cracking, and carbon deposition oxidation, for which the effects of the O/C ratio and temperature were evaluated.
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