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Energies 2018, 11(2), 460; https://doi.org/10.3390/en11020460

Estimation of Effective Diffusion Coefficient of O2 in Ash Layer in Underground Coal Gasification by Thermogravimetric Apparatus

Beijing Advanced Innovation Center for Soft Matter Science and Engineering, and State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
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Received: 28 January 2018 / Revised: 14 February 2018 / Accepted: 14 February 2018 / Published: 22 February 2018
(This article belongs to the Special Issue Biomass Chars: Elaboration, Characterization and Applications Ⅱ)
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Abstract

Underground coal gasification (UCG) proceeds generally in the presence of an ash layer on coal (or char) surface. The ash layer increases the mass transfer resistance of O2 to the gasification surface, which may become the limiting step of whole process. This paper studies O2 diffusion in ash layer formed on cylindrical char samples using a specially designed one-dimension setup in a thermogravimetric apparatus (TGA). The effective internal diffusion coefficient (De) is found to increase with an increase in ash layer thickness, due to an increase in median pore diameter. Methods are established to correlate De with operating conditions and to estimate the role of internal diffusion resistance in overall mass transfer resistance. View Full-Text
Keywords: underground coal gasification; ash layer; effective diffusion coefficient; internal diffusion resistance underground coal gasification; ash layer; effective diffusion coefficient; internal diffusion resistance
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Lin, X.; Liu, Q.; Liu, Z. Estimation of Effective Diffusion Coefficient of O2 in Ash Layer in Underground Coal Gasification by Thermogravimetric Apparatus. Energies 2018, 11, 460.

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