Underground coal gasification process studies for Australian bituminous coal

Chodankar, Chetan Ratnakar (2012). Underground coal gasification process studies for Australian bituminous coal PhD Thesis, School of Mechanical and Mining Engineering, The University of Queensland.

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Author Chodankar, Chetan Ratnakar
Thesis Title Underground coal gasification process studies for Australian bituminous coal
Formatted title
Underground Coal Gasification Process Studies for Australian Bituminous Coal
School, Centre or Institute School of Mechanical and Mining Engineering
Institution The University of Queensland
Publication date 2012
Thesis type PhD Thesis
Supervisor Alexander Klimenko
Bo Feng
Total pages 197
Total colour pages 37
Total black and white pages 160
Language eng
Subjects 0913 Mechanical Engineering
0904 Chemical Engineering
091501 Computational Fluid Dynamics
090405 Non-automotive Combustion and Fuel Engineering (incl. Alternative/Renewable Fuels)
091305 Energy Generation, Conversion and Storage Engineering
Formatted abstract
    The Underground Coal Gasification technology is a promising technology to recover energy content of coal reserves by gasifying coal in-situ. The recent successful UCG field trials have demonstrated the technical feasibility of the technology. The char reactivity of Australian Bituminous coal was studied with thermo-gravimetric analysis. The coal sample was pyrolysed and segregated in two sample size viz. 80-212 µm and 38-75 µm.The coal char was gasified with carbon dioxide at various temperatures (1073 - 1148 K) and partial pressures of reacting gas CO2 and N2. The experimental data of weight loss was used to determine the kinetic parameters for carbon dioxide gasification which are to be used in the numerical modelling of underground coal gasification. The data obtained from the experiments were interpreted with the Random Pore Model. The Unification approach was employed to predict the reactivity of the coal char.

    A novel approach aimed at modelling reactive flows through porous media is suggested. The Porous Conditional Moment Closure (PCMC) approach is proven to be adequate for modelling reactive transport through porous media with fixed pore structure. In coal gasification process, pore structure of coal affect by the gasification reactions. In this study, the parameters are obtained for the diffusive tracer distribution based on the pore size distribution given by the widely applied Random Pore Model (RPM), while coupling PCMC with RPM. Such coupling allows taking into account changes in pore structure caused by heterogeneous reactions and thus improves the accuracy of these key sub-models.

    A transient state Euler-Euler multiphase model for the UCG of steeply dipping coal seam was developed. The UCG process approximated a packed bed gasification process. The numerical results have been found to concur with the Lawrence Livermore National Laboratories experimental results. In this work the effect of injection rate was studied for product gas composition and reaction front propagation. The sensitivity of the reaction front location, product gas composition and propagation of thermal front is studied at various injection rates of gasification mixture.

    A new steady state computational fluid dynamic model for UCG channel model is developed in order to estimate the product gas quality. This model aimed deliver reliable and simple method to estimate syngas composition for various injection rates without involving sensitive parameters like cavity growth. This study also provides significant information about various reaction zones and the location of the reaction front inside the channel. The model provides important information on various zones and location of flame front while estimating the product gas composition, its gross calorific value and temperature distribution inside the gasification channel. It was found that, the air injection rate affects the peak temperature and location of the combustion front. It was also found out that increase in air injection rate results in movement of combustion zone downstream of gasifier channel. The product gas composition predicted with developed model is in good agreement with Centralia UCG trials.
Keyword ucg
Char Reactivity
Multiphase Flow

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Created: Thu, 09 May 2013, 21:35:19 EST by Mr Chetan Chodankar on behalf of Scholarly Communication and Digitisation Service