Gasification Kinetics of Bituminous Coal Char in the Mixture of CO 2, H 2 O, CO, and H 2

Junwei Chen, Weibin Chen, Yang Jiao and Xidong Wang
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Junwei Chen: Department of Energy and Resources Engineering, College of Engineering, Peking University, Beijing 100871, China
Weibin Chen: Department of Energy and Resources Engineering, College of Engineering, Peking University, Beijing 100871, China
Yang Jiao: Department of Energy and Resources Engineering, College of Engineering, Peking University, Beijing 100871, China
Xidong Wang: Department of Energy and Resources Engineering, College of Engineering, Peking University, Beijing 100871, China

Energies, 2019, vol. 12, issue 3, 1-12

Abstract: The gasification kinetics of bituminous coal char was investigated in a mixture of CO 2 , H 2 O, CO, H 2 , and N 2 under isothermal conditions. In addition, the impacts of gasification temperature, gasification time, and gas composition on the gasification process were analyzed. As the experimental results suggest, there is a significant increase of the carbon conversion degree of bituminous coal char not just when gasification temperature and time increase, but also when H 2 and CO concentration decreases. The kinetics of bituminous coal char in the gasification process was successfully modeled as a shrinking unreacted core. It is concluded that the gasification of bituminous coal char is controlled by an internal chemical reaction in the early stage and diffusion in the later stage. The activation energies of bituminous coal char gasification for different stages were studied. Moreover, it is proposed for the first time, to our knowledge, that the diffusion-control step is significantly shortened with the decrease of the CO 2 /H 2 O ratio. As scanning-electron-microscopy results suggest, bituminous coal char gasified in CO 2 /H 2 O = 1/3 atmosphere has numerous inner pores (0–5 m). Therefore, in the process of gasification, the inner pores provide a gas channel that reduces the gas diffusion resistance and thus shortens the diffusion-control step. These results can serve as a reference for industrialized application of the technology of coal gasification direct reduced iron.

Keywords: direct-reduced iron; bituminous coal char; gasification; kinetics; inner pores (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2019
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