h i g h l i g h t s A laboratory scale methodology for assess the coal for its feasibility for UC... more h i g h l i g h t s A laboratory scale methodology for assess the coal for its feasibility for UCG. A comparative study of Indian lignite and hard coal is conducted. Gas calorific value of lignite is 170 kJ/mol and that of hard coal is 69 kJ/mol. Two coals differ significantly in their spalling behavior. Lignite char is found to be ten times more reactive than hard coal char.
Underground Coal Gasification is a process of gasifying coal in-situ to produce syn-gas. The gas ... more Underground Coal Gasification is a process of gasifying coal in-situ to produce syn-gas. The gas thus produced, passes through the outflow channel that leads to the production well. As explained in part-I of this paper (Samdani et al., 2014), cavity growth between injection and production wells happens in two distinct phases. This paper presents an unsteady state model for cavity growth and gas production in phase-II wherein, the growth occurs mostly in horizontal direction towards the production well through the outflow channel. This phase of UCG lasts much longer than phase-I, in which growth takes place in vertical direction till the cavity hits the overburden. In the model for phase-II, the outflow channel is divided in small sections along its length and each section includes three subzones i.e. rubble zone, void zone and roof at the top. A compartment model is developed to reduce the complexity caused by non-ideal flow patterns and changing sizes of different subzones inside the outflow channel. The subzones and the sections are linked appropriately, for mass and energy flow, to give overall performance during Phase-II of UCG. The proposed approach combines chemical reactions, heat and mass transfer effects, spalling characteristic and complex flow patterns to achieve meaningful results. In all, seven gas species, three solid species and eleven reactions are included. The simulation results such as variation in solid density, dynamics of different zones, exit gas quality are presented. The model is validated by comparing the predicted exit gas quality and that observed during similar laboratory scale experiments. Finally the results are also compared with field scale experiments. This model along with the Phase-I model provides a complete modeling solution for UCG process.
h i g h l i g h t s A laboratory scale methodology for assess the coal for its feasibility for UC... more h i g h l i g h t s A laboratory scale methodology for assess the coal for its feasibility for UCG. A comparative study of Indian lignite and hard coal is conducted. Gas calorific value of lignite is 170 kJ/mol and that of hard coal is 69 kJ/mol. Two coals differ significantly in their spalling behavior. Lignite char is found to be ten times more reactive than hard coal char.
Underground Coal Gasification is a process of gasifying coal in-situ to produce syn-gas. The gas ... more Underground Coal Gasification is a process of gasifying coal in-situ to produce syn-gas. The gas thus produced, passes through the outflow channel that leads to the production well. As explained in part-I of this paper (Samdani et al., 2014), cavity growth between injection and production wells happens in two distinct phases. This paper presents an unsteady state model for cavity growth and gas production in phase-II wherein, the growth occurs mostly in horizontal direction towards the production well through the outflow channel. This phase of UCG lasts much longer than phase-I, in which growth takes place in vertical direction till the cavity hits the overburden. In the model for phase-II, the outflow channel is divided in small sections along its length and each section includes three subzones i.e. rubble zone, void zone and roof at the top. A compartment model is developed to reduce the complexity caused by non-ideal flow patterns and changing sizes of different subzones inside the outflow channel. The subzones and the sections are linked appropriately, for mass and energy flow, to give overall performance during Phase-II of UCG. The proposed approach combines chemical reactions, heat and mass transfer effects, spalling characteristic and complex flow patterns to achieve meaningful results. In all, seven gas species, three solid species and eleven reactions are included. The simulation results such as variation in solid density, dynamics of different zones, exit gas quality are presented. The model is validated by comparing the predicted exit gas quality and that observed during similar laboratory scale experiments. Finally the results are also compared with field scale experiments. This model along with the Phase-I model provides a complete modeling solution for UCG process.
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