Journal articles: 'Underground coal gasification'

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Green, Michael. "Recent developments and current position of underground coal gasification." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 232, no. 1 (July 23, 2017): 39–46. http://dx.doi.org/10.1177/0957650917718772.

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Underground coal gasification is a conversion and extraction process, for the production of useful synthetic product gas from an in-situ coal seam, to use in power generation, heat production or as a chemical feedstock. While many variants of the underground coal gasification process have been considered and over 75 trials performed throughout the world, the recent work has tended to focus on the control of the process, its environmental impact on underground and surface conditions and its potential for carbon capture and storage. Academic research has produced a set of mathematical models of underground coal gasification, and the European Union-supported programme has addressed the production of a decarbonised product gas for carbon capture and storage. In recent years, significant progress has been made into the modelling of tar formation, spalling, flows within the cavity and the control of minor gasification components, like BTEX and phenols, from underground coal gasification cavities (BTEX refers to the chemicals benzene, toluene, ethylbenzene and xylene). The paper reviews the most recent underground coal gasification field trial and modelling experience and refers to the pubic concern and caution by regulators that arise when a commercial or pilot-scale project seeks approval. It will propose solutions for the next generation of underground coal gasification projects. These include the need to access deeper coal seams and the use of new techniques for modelling the process.

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Wei, Minghui, Yilin He, Aihua Deng, and Qiuyang Tao. "Research on Temperature Simulation of Underground Coal Gasification Wellbore." Academic Journal of Science and Technology 8, no. 3 (December 28, 2023): 81–89. http://dx.doi.org/10.54097/7et0jy56.

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This study aims to integrate the theoretical distribution calculation of temperature and pressure during the gasification process through the derivation of heat conduction, thermal radiation and pressure control theory in the underground coal gasification process, and analyze the temperature of the underground coal gasification process through finite element modeling. Field influencing factors and pressure changes over time. It is of great significance to obtain the relevant parameters of the gasification chamber in the underground coal gasification process.

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Petrovic, David, Dusko Djukanovic, Dragana Petrovic, and Igor Svrkota. "Contribution to creating a mathematical model of underground coal gasification process." Thermal Science 23, no. 5 Part B (2019): 3275–82. http://dx.doi.org/10.2298/tsci180316155p.

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Underground coal gasification, as an auto thermal process, includes processes of degasification, pyrolysis, and the gasification itself. These processes occur as a result of a high temperature and the management of coal combustion during addition of gasification agent. Air, water vapor mixed with air, air or water vapor enriched with oxygen, or pure oxygen, may be used as gasification agents. Resulting gas that is extracted in this process may vary in chemical composition, so it is necessary to adjust it. That is the reason why it is necessary to develop a mathematical model of the underground gasification process prior to any operations in coal deposit, in order to obtain as much accurate prediction of the process as possible. Numerical calculation provides prediction of gas mixture?s chemical composition, which enables calculation of gas components? energy contents and total energy content of the gas in predicted underground coal gasification process. It is one of the main criteria in the economic assessment of underground coal gasification process. This paper, based on available data on researches in this area, provides a contribution to creation of mathematical model of underground coal gasification.

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Kačur, Ján, Marek Laciak, Milan Durdán, and Patrik Flegner. "Investigation of Underground Coal Gasification in Laboratory Conditions: A Review of Recent Research." Energies 16, no. 17 (August 28, 2023): 6250. http://dx.doi.org/10.3390/en16176250.

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The underground coal gasification (UCG) technology converts coal into product gas and provides the option of environmentally and economically attractive coal mining. Obtained syngas can be used for heating, electricity, or chemical production. Numerous laboratory coal gasification trials have been performed in the academic and industrial fields. Lab-scale tests can provide insight into the processes involved with UCG. Many tests with UCG have been performed on ex situ reactors, where different UCG techniques, the effect of gasification agents, their flow rates, pressures, and various control mechanisms to improve gasification efficiency and syngas production have been investigated. This paper provides an overview of recent research on UCG performed on a lab scale. The study focuses on UCG control variables and their optimization, the effect of gasification agents and operating pressure, and it discusses results from the gasification of various lignites and hard coals, the possibilities of steam gasification, hydrogen, and methane-oriented coal gasification, approaches in temperature modeling, changes in coal properties during gasification, and environmental risks of UCG. The review focuses on laboratory tests of UCG on ex situ reactors, results, and the possibility of knowledge transfer to in situ operation.

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Kreinin, E. V., and A. Yu Zorya. "Underground coal gasification problems." Solid Fuel Chemistry 43, no. 4 (August 2009): 215–18. http://dx.doi.org/10.3103/s0361521909040053.

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Saik, Pavlo, Volodymyr Falshtynskyi, Vasyl Lozynskyi, Roman Dychkovskyi, Mykhailo Berdnyk, and Edgar Cabana. "Substantiating the operating parameters for an underground gas generator as a basic segment of the mining energy-chemical complex." IOP Conference Series: Earth and Environmental Science 1156, no. 1 (April 1, 2023): 012021. http://dx.doi.org/10.1088/1755-1315/1156/1/012021.

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Abstract This paper presents the main aspects of changing the coal mining technology based on the introduction of underground coal gasification technology for the mining-geological conditions of the occurrence of State Enterprise “Lvivvuhillia” coal seams on the example of “Chervonohradska” mine. When conducting analytical studies using the “Material-heat balance of underground coal gasification” software, predictive quantitative-qualitative indicators of the injected blast mixture and gasification products have been determined depending on the structure and elemental composition of the coal seam, host rocks, water saturation of the seam, and water inflow into the gasification channel. The heat energy loss of an underground gas generator during the gasification of thin and ultra-thin coal seams has been revealed. The heat and energy capacity of the underground gas generator has been determined depending on the type of supply of the injected blast mixture to the combustion face “mirror” and the performance indicators of the gas generator segment within the mining energy-chemical complex taking into account the quantitative-qualitative indicators of generator gas and liquid chemical raw material of the condensate.

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Petrovic, David, Lazar Kricak, Milanka Negovanovic, Stefan Milanovic, Jovan Markovic, Nikola Simic, and Ljubisav Stamenic. "Valorization of non-balanced coal reserves in Serbia for underground coal gasification." Thermal Science 23, no. 6 Part B (2019): 4067–81. http://dx.doi.org/10.2298/tsci190725390p.

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In the name of a better and safer energy future, it is our responsibility to focus our knowledge and activities to save on imported liquid and gas fossil fuels, as well as coal on which energy security of Serbia is based. The rationalization in the use of available energy resources certainly positively affects economy and the environment of a country. This paper indicates motivations for the application of the underground coal gasification process, as well as surface gasification for Serbia. The goal is to burn less coal, while simultaneously utilizing more gas from the onsite underground coal gasification, or by gasification in various types of gas generators mounted on the surface. In both cases, from the obtained gas, CO2, NOx, and other harmful gases are extracted in scrubbers. This means that further gas combustion byproducts do not pollute the atmosphere in comparison with traditional coal combustion. In addition, complete underground coal gasification power requirements could be offset by the onsite solar photovoltaic power plant, which furthermore enhances environmental concerns of the overall coal utilization.

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Durdán, Milan, Marta Benková, Marek Laciak, Ján Kačur, and Patrik Flegner. "Regression Models Utilization to the Underground Temperature Determination at Coal Energy Conversion." Energies 14, no. 17 (September 1, 2021): 5444. http://dx.doi.org/10.3390/en14175444.

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The underground coal gasification represents a technology capable of obtaining synthetic coal gas from hard-reached coal deposits and coal beds with tectonic faults. This technology is also less expensive than conventional coal mining. The cavity is formed in the coal seam by converting coal to synthetic gas during the underground coal gasification process. The cavity growth rate and the gasification queue’s moving velocity are affected by controllable variables, i.e., the operation pressure, the gasification agent, and the laboratory coal seam geometry. These variables can be continuously measured by standard measuring devices and techniques as opposed to the underground temperature. This paper researches the possibility of the regression models utilization for temperature data prediction for this reason. Several regression models were proposed that were differed in their structures, i.e., the number and type of selected controllable variables as independent variables. The goal was to find such a regression model structure, where the underground temperature is predicted with the greatest possible accuracy. The regression model structures’ proposal was realized on data obtained from two laboratory measurements realized in the ex situ reactor. The obtained temperature data can be used for visualization of the cavity growth in the gasified coal seam.

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Saik, P., V. Lozynskyi, D. Malachkevych, and O. Cherniaіeva. "To the issue of underground gasification of low-thickness unconditioned coal reserves." Collection of Research Papers of the National Mining University 71 (December 2022): 91–103. http://dx.doi.org/10.33271/crpnmu/71.091.

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Purpose. Formation of an innovative approach in the rational development of low-thickness unconditioned coal reserves with the establishment of their suitability for underground gasification technology and the study of mass and heat indicators of the gasification process on the example of the mine of PJSC "DTEK Pavlohradvuhillia" named after Heroiv Kosmosu. Methods. The possibility of implementing the technology of in situ underground coal gasification was based on analytical studies. On the basis of the work developed by the professor of the Department of Mining Engineering and Education of "Dnipro University of Technology" Dychkovskyi R.O "Methods for assessing the suitability of reserves for underground coal gasification" established the general coefficient of the suitability of coal reserves for gasification located within the minefield named after Heroiv Kosmosu and are promising for future development. The output parameters of combustible and ballast generator gases, and the chemical and energy efficiency of the gasification process were studied using the "MTB SPGV" software, which passed industrial approval both during laboratory and field tests. Findings. Current issues related to the application of a combination the technologies for the development of low-thickness non-conditional coal reserves, which allow significantly extend the life of the mining enterprise, are highlighted. In particular, after working out the productive areas of coal reserves, the orientation of production is aimed at the processing of reserves at the place of their occurrence by underground gasification technology. Criteria for the suitability of coal reserves were established, which allowed the establishment of the priority of coal seams gasification. Based on the change in the parameters of the fuel mixture, the output of combustible and ballast generator gases was investigated. Originality. It was established that when air and oxygen-enriched blowing is supplied to the underground gas generator, the output volume of combustible generator gases remains the same, the difference lies in the concentration of these gases in the initial mixture. This is due to the high content of nitrogen during air blowing, which does not enter into a chemical reaction with coal, and at temperatures in the reaction channel below 900°C, the output of CO decreases by 25-46%. Practical implications. The conditions of the mine named after Heroiv Kosmosu defined criteria for the suitability of coal for gasification. Two coal seams of the mine c12 and c7top are in conditions of sufficient suitability for underground coal gasification.

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Zha, Xiao Xiong, Hai Yang Wang, and Shan Shan Cheng. "Finite Element Analysis of the Subsidence of Cap Rocks during Underground Coal Gasification Process." Advanced Materials Research 859 (December 2013): 91–94. http://dx.doi.org/10.4028/www.scientific.net/amr.859.91.

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This paper discusses the possible surface subsidence and deformation of the overlying rock during the underground coal gasification (UCG) process, which is an important part of feasibility studies for UCG operations. First coal seam roof movement and surface subsidence in the shallow UCG process were simulated by a finite element model coupled with heat transfer module in COMSOL. Numerical results from this model were compared with and in good agreement to the existing studies. This was followed by the development of model for deeper coal seam cases. The comparison of the numerical results from two models shows that surface uneven settlement in deep underground coal gasification is only 7% of that in shallow underground coal gasification.

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Zhang, Zhizhen, Xiao Yang, Xiaoji Shang, and Huai Yang. "A Thermal-Hydrological-Mechanical-Chemical Coupled Mathematical Model for Underground Coal Gasification with Random Fractures." Mathematics 10, no. 16 (August 9, 2022): 2835. http://dx.doi.org/10.3390/math10162835.

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In this paper, in order to understand the development process and influencing factors of coal underground gasification, taking the two-dimensional underground gasification area of the plane as the simulation object, the characteristics of the multi-physical field coupling process of exudate mass heat transfer and combustion gasification reaction in the process of horizontal coal seam underground gasification are analyzed, and a two-dimensional mathematical model of thermal-hydrological-mechanical-chemical coupling of a porous medium is established. The temperature distribution of coal rock from the gasification point, the distribution of gas water vapor pressure and stress-strain, the temperature contour distribution of fractured coal rocks of different densities of heterogeneity, and the influence of different water-oxygen ratios and different fractured coal rocks on the gas components generated by the gasification reaction were studied. The results show that the tensile damage caused by the tensile strain volume expansion of the coal underground gasification center, the shear damage caused by the compression of the edge compressive strain volume, and the temperature conduction rate decrease with the increase in the coal rock fracture, but in the heterogeneous coal rock, the greater the fracture density, the faster the temperature conduction rate, which has a certain impact on the gasification combustion reaction. The ratio of CO2, H2 and CO in the case of simulating that the water-to-oxygen ratio is 1:2, 1:1, and 2:1 is 1:0.85:0.73, 1:1.1:0.97, and 1:1.76:1.33, respectively. At a water-oxygen ratio of 2:1, the concentration ratio is the most ideal, and the main gases, CO, CO2, and H2, are 32%, 21%, and 37%. Furthermore, the reaction rate increases with the increase of fracture density. The gas component concentration simulated in this paper has good consistency with the results of the previous experimental data, which has important guiding significance for the underground coal gasification project.

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Pivnyak, Gennadiy, Volodymyr Falshtynskyi, Roman Dychkovskyi, Pavlo Saik, Vasyl Lozynskyi, Edgar Cabana, and Oleksandr Koshka. "Conditions of Suitability of Coal Seams for Underground Coal Gasification." Key Engineering Materials 844 (May 2020): 38–48. http://dx.doi.org/10.4028/www.scientific.net/kem.844.38.

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Results of evaluating the suitability of certain sections of Western Donbas coal seams, based predominately on properties of coal material, for their further experimental development by means of underground gasification method are represented. Criteria to evaluate both expediency of underground gasification and specific conditions of that process are substantiated basing upon the methodology developed at the National Mining University (Dnipro, Ukraine) together with representatives from National University of Saint Augustine (Arequipa, Peru). The methodology has been industrially approved with the confirmation of its efficiency while developing technical documentation for underground gasification projects: “Project of experimental section of Pidzemgaz station of Pavlogradvuhillia association”, “Feasibility study of the expediency of the construction of Pidzemgaz station” FS 3858-PZ”, Synelnykovo deposit; “Project on experimental underground gas generator”, Monastyryshche deposit, FS of experimental module of UCG station of Solenovske coal-mining area, Donbas. Also, they contain the researches, which were conducted within the project GP – 489, financed by Ministry of Education and Science of Ukraine.

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Falshtynskyi, V., P. Saik, R. Dychkovskyi, V. Lozynskyi, and M. Demydov. "Aspects for implementing the cumulative energy systems during underground coal gasification." Collection of Research Papers of the National Mining University 69 (June 2022): 94–104. http://dx.doi.org/10.33271/crpnmu/69.094.

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Purpose. An innovative approach formulation to the rational development of the potential of coal mines to expand the economic activity of mining enterprises based on the implementation of underground heat generators during coal gasification. Methods. Based on the conducted analytical and laboratory research, to study the possibility of introducing underground heat generators and cogeneration systems during gasification of coal at the site of its occurrence. The basis for conducting analytical studies is the experience of implementing the specified modules and cogeneration plants. The basis for laboratory research is a laboratory setup that allows modeling the behavior of thermochemical and geomechanical processes in the resulting gas generator, depending on the mining-geological conditions of the coal seam occurrence, methods and ways of supplying injected blast mixtures to the fire face mirror. Findings. Current issues of implementing the cumulative energy systemsbased on mining enterprises are highlighted. It has been determined that a possible basis for expanding the range of economic activity at a coal-mining enterprise is the implementation of underground gasification technology. The main products of the latter are producer gas, thermal energy and chemical raw materials. The parameters of changing the temperature field in the immediate bottom of the underground gas generator and the producer gas temperature at the outlet from the gas production borehole have been studied. On the basis of their changes, the technological schemes of the underground heat generator are proposed. This makes it possible to use technogenic thermal energy both in the process of coal gasification and at the stage of attenuation of an underground gas generator, as well as a scheme of a cogeneration system with heat accumulation from products of borehole underground coal gasification (BUCG). Originality. An innovative approach has been developed to the rational technogenic thermal energy development during coal gasification at the site of its occurrence. Practical implications. The implementation of cumulative energy systems based on underground heat generators during coal gasification at the site of its occurrence and the subsequent use of thermal technogenic environment allow creating compact energy modules that can satisfy the energy needs of a mining enterprise.

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Liu, Hong Tao, Hong Yao, Kai Yao, Feng Chen, and Guang Qian Luo. "Characteristics of "Three Zones" during Underground Coal Gasification." Advanced Materials Research 524-527 (May 2012): 56–62. http://dx.doi.org/10.4028/www.scientific.net/amr.524-527.56.

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According to the temperature, major chemical reactions and gas compositions, the gasification process along the tunnel of underground coal gasification is divided into three zones, i.e. oxidation zone, reduction zone and dry distillation zone. A model test in the laboratory was carried out by using large-scale coal blocks to simulate the coal seam. The characteristics of the “three zones”, and the relation between the temperature and gas composition were also quantitative studied. It provided the necessary basic knowledge for further studying the process of underground coal gasification, including predicting compositions of product gas, life-cycle analyzing, selecting optimistic control parameters and determining suitable gasification craft.

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Dubiński, Józef, and Marian Turek. "Basic Aspects Of Productivity Of Underground Coal Gasification Process." Archives of Mining Sciences 60, no. 2 (June 1, 2015): 443–53. http://dx.doi.org/10.1515/amsc-2015-0029.

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Abstract An analysis of conditions which enable attaining possibly highest productivity of industrial scale underground coal gasification technology is presented. The analysis was prepared basing on results obtained during an experimental gasification process conducted in workings of an active hard coal mine. Basic aspects determining application and productivity of the technology concern both general conditions, referring to the hard coal seam being gasified, and practical issues, which need to be considered in coal mine conditions. To present them, the technology of underground coal gasification and still commonly used classical longwall method of mining coal seams are compared.

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Konovsek, Damjan, Zdravko Praunseis, Jurij Avsec, Gorazd Bercic, Andrej Pohar, Simon Zavsek, and Milan Medved. "Underground coal gasification - the Velenje Coal Mine energy and economic calculations." Chemical Industry and Chemical Engineering Quarterly 23, no. 2 (2017): 269–77. http://dx.doi.org/10.2298/ciceq160504042k.

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Underground coal gasification (UCG) is a viable possibility for the exploitation of vast coal deposits that are unreachable by conventional mining and can meet the energy, economic and environmental demands of the 21st century. Due to the complexity of the process, and the site-specific coal and seam properties, it is important to acknowledge all the available data and past experiences, in order to conduct a successful UCG operation. Slovenia has huge unmined reserves of coal, and therefore offers the possibility of an alternative use of this domestic primary energy source. According to the available underground coal gasification technology, the energy and economic assessment for the exploitation of coal to generate electricity and heat was made. A new procedure for the estimation of the energy efficiency of the coal gasification process, which is also used to compare the energy analyses for different examples of coal exploitation, was proposed, as well as the technological schemes and plant operating mode in Velenje, and the use of produced synthetic coal gas (syngas). The proposed location for the pilot demonstration experiment in Velenje Coal Mine was reviewed and the viability of the underground coal gasification project in Velenje was determined.

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Saik, Pavlo, and Mykhailo Berdnyk. "Mathematical model and methods for solving heat-transfer problem during underground coal gasification." Mining of Mineral Deposits 16, no. 2 (June 30, 2022): 87–94. http://dx.doi.org/10.33271/mining16.02.087.

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Purpose. A mathematical model development for heat transfer during underground coal gasification based on the transcendental equation solution by the Newton-Raphson method. Methods. The heat-transfer model development is based on the research into a temperature field with a variable size of the gasification zone when passing through the phase transformation boundary, which changes abruptly. The research on the coal seam T(x, t) temperature field and the displacement length of the phase transition boundary S(t) is based on the integration of the differential heat-transfer equation with the fulfillment of one-phase Stefan problem conditions. The proportionality factor (β), characterizing the ratio of the displacement length of the “generator gas – coal” phase transition boundary to the time of coal seam gasification, is determined by substituting the Boltzmann equation and using the Newton-Raphson method based on solving the obtained transcendental equation. Findings. The main problems related to laboratory research on the coal gasification process have been identified. A mathematical model of heat transfer during underground coal gasification for a closed georeactor system has been developed, taking into account the effective change in its active zones. Originality. A mathematical model of heat transfer during underground coal gasification at the phase transition boundary has been developed, under which the one-phase Stefan problem conditions are fulfilled. Dependences of the change in the underground gas generator temperature, taking into account the change in the active zones of chemical reactions along the length of the combustion face and the gasification column, have been revealed. In addition, the dependences of the change in the phase transition boundary of a “generator gas – coal” heterogeneous system have been determined, which characterize the displacement length of the phase transition boundary on time and reveal the relationship between the thermal conductivity coefficient, specific heat capacity, as well as bulk density of coal and its calorific value. Practical implications. A method has been developed to determine the displacement length of the phase transition boundary of a “generator gas – coal” heterogeneous system and its relationship between the time and temperature of gasification process. This makes it possible to predict in the future the change in the active zones of the underground gas generator along the length of the gasification column.

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STEPHENS, D. R., R. W. HILL, and I. Y. BORG. "Status of Underground Coal Gasification." Mineral Processing and Extractive Metallurgy Review 1, no. 3-4 (April 1985): 265–96. http://dx.doi.org/10.1080/08827508508952595.

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Kapusta, Krzysztof, Marian Wiatowski, Krzysztof Stańczyk, Renato Zagorščak, and Hywel Rhys Thomas. "Large-scale Experimental Investigations to Evaluate the Feasibility of Producing Methane-Rich Gas (SNG) through Underground Coal Gasification Process. Effect of Coal Rank and Gasification Pressure." Energies 13, no. 6 (March 13, 2020): 1334. http://dx.doi.org/10.3390/en13061334.

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An experimental campaign on the methane-oriented underground coal gasification (UCG) process was carried out in a large-scale laboratory installation. Two different types of coal were used for the oxygen/steam blown experiments, i.e., “Six Feet” semi-anthracite (Wales) and “Wesoła” hard coal (Poland). Four multi-day gasification tests (96 h continuous processes) were conducted in artificially created coal seams under two distinct pressure regimes-20 and 40 bar. The experiments demonstrated that the methane yields are significantly dependent on both the properties of coal (coal rank) and the pressure regime. The average CH4 concentration for “Six Feet” semi-anthracite was 15.8%vol. at 20 bar and 19.1%vol. at 40 bar. During the gasification of “Wesoła” coal, the methane concentrations were 10.9%vol. and 14.8%vol. at 20 and 40 bar, respectively. The “Six Feet” coal gasification was characterized by much higher energy efficiency than gasification of the “Wesoła” coal and for both tested coals, the efficiency increased with gasification pressure. The maximum energy efficiency of 71.6% was obtained for “Six Feet” coal at 40 bar. A positive effect of the increase in gasification pressure on the stabilization of the quantitative parameters of UCG gas was demonstrated.

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Lozynskyi, Vasyl, Volodymyr Falshtynskyi, Pavlo Saik, Roman Dychkovskyi, Bakhyt Zhautikov, and Edgar Cabana. "USE OF MAGNETIC FIELDS FOR INTENSIFICATION OF COAL GASIFICATION PROCESS." Rudarsko-geološko-naftni zbornik 37, no. 5 (2022): 61–74. http://dx.doi.org/10.17794/rgn.2022.5.6.

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Underground coal gasification is an alternative method for mining coal from thin and ultra-thin seams, which enables conversion of solid fossil fuels into combustible gases at the site of coal occurrence. At the same time, in the case when the coal seam thickness is critically small for the effective course of thermochemical reactions, it is necessary to intensify the gasification process. This paper studies one of the possible methods to intensify the process of underground coal gasification due to the influence of magnetic fields on the injected blast supplied into the gas generator gasification channel. Research tests conducted on a bench setup confirm the effectiveness of injected blast activation in a magnetic field by creating magnetic field inhomogeneity by placing permanent magnets and a discrete solid magnetized phase in a special device. For the first time, the dependence of changing growth of carbon participation during the solid fuel gasification process on changing magnetic field strength in the range of 0-600 E has been determined. It has been proven that the injected blast magnetization can significantly intensify the underground gasification process by increasing the carbon participation share in the fuel, which may be of practical importance for increasing the yield of combustible components.

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Lozynskyi, Vasyl, Volodymyr Falshtynskyi, Arystan Kozhantov, Lina Kieush, and Pavlo Saik. "Increasing the underground coal gasification efficiency using preliminary electromagnetic coal mass heating." IOP Conference Series: Earth and Environmental Science 1348, no. 1 (May 1, 2024): 012045. http://dx.doi.org/10.1088/1755-1315/1348/1/012045.

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Abstract The purpose of this research is to explore the possibilities of using a high-frequency electromagnetic field for heating coal seams in the context of underground coal gasification. The research is based on mathematical models that take into account the physical parameters of the electromagnetic field. The methodology includes the calculation of thermal powers, exposure duration, temperature profiles and reaction rates. The research results indicate significant potential for using high-frequency electromagnetic field for coal seam pre-heating. Possibilities of using a high-frequency electromagnetic field for heating the mass in the context of underground coal gasification have been explored. The mathematical models developed and calculations performed broaden the understanding of heating processes in such systems. It has been determined that field parameters, such as frequency and power, influence the heating efficiency and temperature distribution. The obtained scientific results present new opportunities to increase the efficiency of underground coal gasification as an alternative energy source and will contribute to achieving a more efficient and sustainable future energy supply. The use of a high-frequency electromagnetic field can be useful when gasifying low-grade or low-thickness coal seams, when there is a need to intensify the gasification process.

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Saik, Pavlo, Roman Dychkovskyi, Vasyl Lozynskyi, Volodymyr Falshtynskyi, Edgar Cabana, and Leonid Hrytsenko. "Studying the features of the implementation of underground coal gasification technology in terms of Lvivvuhillia SE." E3S Web of Conferences 168 (2020): 00036. http://dx.doi.org/10.1051/e3sconf/202016800036.

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Topical issues of the possibilities for changes in the coal extraction technology in terms of Stepova mine of Lvivvuhillia SE have been highlighted. Analysis of the current state of mining operations has been carried out. Design solutions as for introduction of the coal gasification technology in the life cycle of the mining enterprise has been proposed on the basis of the analytical, experimental, and industrial studies; the technology has been described. Percentage ratio of the output of combustion generator gases (Н2, СО, СН4) has been identified; gas combustion value and efficiency of the process depending on certain changes in the blowing mixture composition supplied into the underground gas generator have been determined. Heat balance of the process of underground coal gasification has been studied making it possible to evaluate its energy balance. The algorithm to determine coal reserves in a mine pillar to be gasified has been proposed. Indices of the output of combustion generator gases from the gasification column have been defined. The relevant issues have been studied of ensuring the possibility of underground coal gasification technology when uncovering the mining extracted area for the underground gas generator operation.

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Saik, Pavlo, and Dmytro Yankin. "DEVELOPMENT OF METHODOLOGY FOR RESEARCH IN HYDROGEN-ORIENTED UNDERGROUND COAL GASIFICATION TECHNOLOGY." NAUKOVYI VISNYK DONETSKOHO NATSIONALNOHO TEKHNICHNOHO UNIVERSYTETU, no. 1(12) (2024): 129–38. http://dx.doi.org/10.31474/2415-7902-2024-1-12-129-138.

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Purpose. Establishing correlations between analytical and laboratory research in underground coal gasification with a focus on hydrogen production. Methodology. Analysis of experience in conducting analytical and laboratory research in the field of underground coal gasification in situ. Analysis of the application specifics of the Darcy-Weisbach equation to establish optimal conditions for supplying steam-air mixture to the combustion face considering the relationship between the volumetric flow of the specified mixture through the controlled pipeline and its cross-sectional area. Results. The proposed algorithm for conducting research on underground coal gasification processes focuses on hydrogen production. Analytical formulas are provided to determine optimal parameters for supplying the blowing mixture to the combustion front via the controlled pipeline. An author's technological scheme of a laboratory setup for studying gasification processes and the peculiarities of researching it are presented. A diagram illustrating the relationship between blowing system parameters, which vary depending on the hydrogen raw material requirements, the energy capabilities of the system itself, and the parameters of the controlled pipeline, is provided. Originality: Scientifically grounded development of a methodology for conducting analytical and laboratory research on coal gasification process to determine parameters for supplying the blowing mixture through the controlled pipeline with a focus on hydrogen production. Practical implications: Practical implications: Conducting research according to the developed research methodology of underground coal gasification technology allows for a systematic and structured approach to assessing all aspects of the gasification process. The use of a clear research methodology helps to avoid subjectivity and simplifies the process of data collection and analysis. The research methodology ensures high reliability and accuracy of the obtained data, which is critical for making informed decisions. Effective use of the research methodology minimizes resource usage, such as time, costs, and equipment, by avoiding unnecessary duplications and unjustified expenses. Practical implications: Practical implications: Conducting research according to the developed research methodology of underground coal gasification technology allows for a systematic and structured approach to assessing all aspects of the gasification process. The use of a clear research methodology helps to avoid subjectivity and simplifies the process of data collection and analysis. The research methodology ensures high reliability and accuracy of the obtained data, which is critical for making informed decisions. Effective use of the research methodology minimizes resource usage, such as time, costs, and equipment, by avoiding unnecessary duplications and unjustified expenses. Keywords: underground coal gasification, hydrogen, methodology, analytical research, Darcy-Weisbach equation, laboratory research.

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Lozynskyi, Vasyl, Roman Dichkovskiy, Pavlo Saik, and Volodymyr Falshtynskyi. "Coal Seam Gasification in Faulting Zones (Heat and Mass Balance Study)." Solid State Phenomena 277 (June 2018): 66–79. http://dx.doi.org/10.4028/www.scientific.net/ssp.277.66.

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In this article, the mass and heat balance calculations of underground coal gasification process for thin coal seams in faulting zones of Lvivskyi coal basin (Ukraine) are defined. The purpose of the research is to establish regularities of heat and mass balance changes in faulting zones influence due to usage air and oxygen-enriched blast. A comprehensive methodology that included analytical calculations is implemented in the work. The output parameters of coal gasification products for the Lvivvyhillia coal mines are detailed. The heat balance is performed on the basis of the mass balance of underground coal gasification analytical results and is described in detail. Interpretations based on the conducted research and investigation are also presented. Conclusions regarding the implementation of the offered method are made on the basis of undertaken investigations. According to conducted research the technology of underground coal gasification can be carry out in the faulting zone of stable geodynamic and tectonic activity. The obtained results with sufficient accuracy in practical application will allow consume coal reserves in the faulting zones using environmentally friendly conversion technology to obtain power and chemical generator gas, chemicals and heat.

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Kačur, Ján, Marek Laciak, Milan Durdán, and Patrik Flegner. "Model-Free Control of UCG Based on Continual Optimization of Operating Variables: An Experimental Study." Energies 14, no. 14 (July 18, 2021): 4323. http://dx.doi.org/10.3390/en14144323.

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The underground coal gasification (UCG) represents an effective coal mining technology, where coal is transformed into syngas underground. Extracted syngas is cleaned and processed for energy production. Various gasification agents can be injected into an underground georeactor, e.g., air, technical oxygen, or water steam, to ensure necessary temperature and produce syngas with the highest possible calorific value. This paper presents an experimental study where dynamic optimization of operating variables maximizes syngas calorific value during gasification. Several experiments performed on an ex situ reactor show that the optimization algorithm increased syngas calorific value. Three operation variables, i.e., airflow, oxygen flow, and syngas exhaust, were continually optimized by an algorithm of gradient method. By optimizing the manipulation variables, the calorific value of the syngas was increased by 5 MJ/m3, both in gasification with air and additional oxygen. Furthermore, a higher average calorific value of 4.8–5.1 MJ/m3 was achieved using supplementary oxygen. The paper describes the proposed ex situ reactor, the mathematical background of the optimization task, and results obtained during optimal control of coal gasification.

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Durdán, Milan, Ján Terpák, Ján Kačur, Marek Laciak, and Patrik Flegner. "MODELING OF MATERIAL BALANCE FROM THE EXPERIMENTAL UCG." Acta Polytechnica 60, no. 5 (November 16, 2020): 391–99. http://dx.doi.org/10.14311/ap.2020.60.0391.

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The underground coal gasification is a continually evolving technology, which converts coal to calorific gas. There are many important parameters in this technology, which are difficult to measure. These parameters include the underground cavity growth, amount gasified coal, and the leakage of input and output gaseous components into the surrounding layers during the coal gasification process. Mathematical modeling of this process is one of the possible alternatives for determining these unknown parameters. In this paper, the structure of the mathematical model of laboratory underground coal gasification process from the material balance aspect is presented. The material balance consists of mass components entering and leaving from the UCG process. The paper shows a material balance in the form of a general mass balance and atomic species balance. The material balance was testing by six UCG laboratory experiments, which were realized in two ex-situ reactors.

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Saik, P., V. Lozynskyi, O. Anisimov, O. Akimov, A. Kozhantov, and O. Mamaykin. "Managing the process of underground coal gasification." Naukovyi Visnyk Natsionalnoho Hirnychoho Universytetu, no. 6 (December 23, 2023): 25–30. http://dx.doi.org/10.33271/nvngu/2023-6/025.

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Purpose. The research purpose is to determine the efficiency parameter of the coal gasification process based on the analysis of the composition of combustible gases (Н2, СН4, СО) and the producer gas calorific value, depending on the methods of supplying the blast mixtures to the gasifier oxidative zone. Methodology. A laboratory setup is used to perform experimental research into underground coal seam gasification. Its constituent segments are a stand, branches for supplying blast and gas-outlet mixtures, as well as a flow control system. This setup makes it possible to model the coal seam occurrence according to the mining-geological conditions of its occurrence. When determining the gasification process efficiency, two methods of supplying the blast mixture are tested: through a blast injection well and combined method (blast injection well + controlled pipeline). The generated producer gas calorific value has been determined analytically according to the “additivity rule”, taking into account the concentration of each combustible gas and its calorific value. Findings. The underground gasifier efficiency when changing the method of supplying the air mixture has been substantiated. Based on qualitative data on the concentration of combustible gasifier gases at the outlet of a modeled underground gasifier, conditions for increasing their concentration have been characterized and time intervals have been determined, through which their decrease occurs with increasing outgassed space. Originality. It has been revealed that the use of combined blast method in an underground gasifier causes a double supply of oxidizing agent to the gasification zone. This intensifies the gasification process by expanding the gasification reaction zones both along the length of the gasification column and along the seam thickness. Also, the combined method of supplying the blast mixture is characterized by improved thermal stability and gas formation parameters. Practical value. The research results make it possible to quickly make technological decisions for changing the operating modes of the underground gasifier, as well as determine the optimal method for supplying air mixtures, which improves the quality and calorific value of the producer gas. When changing the blast supply method to a combined method, the average concentration of Н2, СН4 and СО combustible gases increases by 3.85 %, and the calorific value increases by an average of 0.53 MJ/m3.

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Bielowicz, Barbara. "The suitability of polish ortho-lignite deposits for clean coal technologies." Gospodarka Surowcami Mineralnymi 32, no. 4 (December 1, 2016): 109–28. http://dx.doi.org/10.1515/gospo-2016-0034.

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Abstract The article presents the suitability of polish lignite deposits for clean coal technologies, mainly fluidized bed gasification and underground gasification. One of the key elements in this study, is a detailed diagnosis of the resource base, its analysis on the basis of the established verification criteria and -as a result - the achievement of a reliable assessment of suitability for highly efficient production of fuels and electric energy through lignite gasification in both surface and underground installations, taking into account both sozological conditions and protected geological sites. The analysis has shown that only 10 out of from 166 lignite deposit meet the criteria for the potential development of process underground gasification.

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Škvareková, Erika, Marianna Tomašková, Gabriel Wittenberger, and Štefan Zelenák. "Analysis of Risk Factors for Underground Coal Gasification." Management Systems in Production Engineering 27, no. 4 (December 1, 2019): 227–35. http://dx.doi.org/10.1515/mspe-2019-0036.

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AbstractThe purpose of this article is to determine the environmental impacts of underground gasification on the population and to analyze the risk of underground coal gasification (UCG) activities using selected risk assessment methods. Coal gas is a regular part of coal deposits and its extraction also allows the use of coal deposits that cannot be extracted by traditional methods. These technologies bring both positive and negative aspects. The paper points out the risk analysis, hazard identification and assessment during the operation of UCG technology using a risk graph and a risk matrix. Identified risks to workers that cannot be reduced should be taken into consideration and appropriate safeguard should be used. For each risk, it is necessary to inform employees about regular education and training. From worldwide experience with this technology, it is possible to analyze risks in Slovakia. Actual gasification produces polluting gases such as carbon dioxide, carbon monoxide, hydrogen sulphide, hydrogen sulphide, nitrogen oxides, tar and ash, and creates a risk that may occur on and under the surface of the site depending on the geological and hydrogeological structure of the deposits. Possible measures to mitigate the adverse effects are proposed for the implementation of this technology. Coal is still one of the main domestic primary energy sources. Currently, only 5 out of 19 deposits in the Slovak Republic are used. Underground gasification could increase the use of Slovak coal and brown coal deposits.

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Yin, Zhenyong, Hao Xu, Yanpen Chen, and Tiantian Zhao. "Coal char characteristics variation in the gasification process and its influencing factors." Energy Exploration & Exploitation 38, no. 5 (July 27, 2020): 1559–73. http://dx.doi.org/10.1177/0144598720935523.

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Underground coal gasification is a burgeoning coal exploitation technique that coal is directly converted into gaseous fuel by controlled combustion. In this paper, the gasification experiments of Inner Mongolia lignite, Xinjiang subbituminous coal, and Hancheng medium volatile bitumite were conducted respectively by using the tube furnace coal gasification experiment system. The gasification process was conducted under 3°C/min increment within the range of 600–900°C. The gas composition was analyzed by gas chromatography and the pore structure of the coal char was detected by low-temperature N2 adsorption. The results show that the gasification temperature, gasification agent, and coal type have an important influence on the gasification reaction. With the increase of gasification temperature, the effective component, gas calorific value, and gas production rate increase. When CO2 is used as the gasifying agent, the effective components in the gas are mainly CO. When H2O(g) is used as the gasifying agent, the effective component of gas is H2. The coal gasification performance with low thermal maturity is obvious better than the high rank coal with higher coalification. N2 adsorption–desorption experiments show that the pore is mainly composed by transition pore and the micropores, the specific surface area is chiefly controlled by a pore size of 2–3 nm. With the increase of coalification degree, the adsorption amount, specific surface area, and total pore volume show a decreasing trend. The gasifying agent has a great influence on the pore structure of the coal char. The gasification effect of H2O (g) is significantly better than that of CO2. Analyzing the gasification characteristics and pore changes of different coal rank coals under different gasification agents, we found that Inner Mongolia lignite is more conducive to the transport of gasification agents and gaseous products in coal.

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Laciak, Marek, Milan Durdán, Ján Kačur, and Patrik Flegner. "The Underground Coal Gasification Process in Laboratory Conditions: An Experimental Study." Energies 16, no. 7 (April 5, 2023): 3266. http://dx.doi.org/10.3390/en16073266.

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The underground coal gasification (UCG) process represents a modern and effective coal mining technology that enables coal energy extraction through thermic decomposition. The coal is transformed into syngas by oxidizers (e.g., air, technical oxygen, or water steam) and is injected into a georeactor. The produced syngas is exhausted on the surface, where it is transformed into the desired form of energy. This paper presents an experimental study of two experiments performed in ex-situ reactors. The paper describes the equipment for the UCG process, the physical models of the coal seam, and the analysis of coal. The obtained results from the experiments are presented as the behavior of the temperatures in the coal during the experiment, the syngas composition, and its calorific value. The material balance and effective gasification time of the UCG process were also identified for the individual experiments. The aim was to evaluate the impact of the coal seam model on the gasification process efficiency. Calculating the material balance during the gasification appears to be an effective tool for assessing leaks in the reactor while measuring the flow and concentration of the oxidizers and produced gas. The material balance data are make it possible to propose methods for controlling the input oxidizers. To increase the efficiency of the gasification in an ex-situ reactor, it is necessary to ensure the impermeable or poorly permeable surrounding layers of the coal seam.

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Yuan, Shuxia, Wanwan Jiao, Chuangye Wang, Song Wu, and Qibin Jiang. "Simulation of Underground Coal-Gasification Process Using Aspen Plus." Energies 17, no. 7 (March 28, 2024): 1619. http://dx.doi.org/10.3390/en17071619.

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In order to study the underground coal-gasification process, Aspen Plus software was used to simulate the lignite underground gasification process, and a variety of unit operation modules were selected and combined with the kinetic equations of coal underground gasification. The model can reflect the complete gasification process of the coal underground gasifier well, and the simulation results are more in line with the experimental results of the lignite underground gasification model test. The changes in the temperature and pressure of oxygen, gasification water, spray water, and syngas in pipelines were studied, and the effects of pipe diameters on pipeline conveying performance were investigated as well. The effects of the oxygen/water ratio, processing capacity, and spray-water volume on the components of syngas and components in different reaction zones were studied. In addition, the change tendency of gasification products under different conditions was researched. The results indicate that: (1) The depth of injection and the formation pressure at that depth need to be taken into account to determine a reasonable injection pressure. (2) The liquid-water injection process should select a lower injection pressure. (3) Increasing the oxygen/water ratio favors H2 production and decreasing the oxygen/water ratio favors CH4 production. (4) The content of CO2 is the highest in the oxidation zone, the lowest in the reduction zone, and then increases a little in the methanation reaction zone for the transform reaction. The content of CO is the lowest in the oxidation zone and the highest in the reduction zone. In the methanation reaction zone, CO partially converts into H2 and CO2, and the content of CO is reduced. (5) The injection of spray water does not affect the components of the gas but will increase the water vapor content in the gas; thus, this changes the molar fraction of the wet gas.

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Inkin, O. V., and N. I. Dereviahina. "Study of the migration processes in the roof of an underground gas-generator." Вісник Дніпропетровського університету. Геологія, географія 26, no. 1 (March 30, 2018): 64–70. http://dx.doi.org/10.15421/111807.

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Currently, coal is the main natural energy carrier in Ukraine due to its limited resources of oil and natural gas. A promising method for extracting coal is underground gasification using thermochemical and mass-exchange processes. This study was aimed at the investigation of migration processes in the roof rock of an underground gas-generator through developing a physicalmathematical model of migration of gasification products in the roof rocks of an underground gas-generator. We have substantiated the technological measures directed to eliminating the hydrocarbon zones, with additional extraction of useful products. We suggest a physical-mathematical model of migration of gasification processes in the roof rocks of an underground gas-generator, which allows elimination of hydrocarbon zones with additional extraction of useful products. We determined the pattern of the changes in the excess pressure and temperature during the processes of gasification in overburden, moisture content of the gas during its seepage through the roof rocks, and also colmatage of the porous space. Using the results, we improved the UCG technology by using the condensing products of gasification in the overburden.

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Lozynskyi, Vasyl. "Critical review of methods for intensifying the gas generation process in the reaction channel during underground coal gasification (UCG)." Mining of Mineral Deposits 17, no. 3 (September 30, 2023): 67–85. http://dx.doi.org/10.33271/mining17.03.067.

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Purpose. The research purpose is to perform a critical analysis of methods for intensifying the gas generation process in the reaction channel to improve the efficiency and economic feasibility of coal seam gasification technology. The paper studies in detail the aspects of the chemical mechanism and technological parameters of this process in order to determine the possibilities for improving efficiency and productivity. Methods. The review study is based on an approach that includes an analysis of the underground coal gasification development, the study of chemical reactions in the reaction channel, the study of the influence of factors such as temperature, pressure, blast and producer gas composition, etc. The experimental research data systematization is based on in-depth analysis of scientific papers published in peer-reviewed journals. Findings. The systematized results of research into nine main methods for intensifying the gas generation process in the reaction channel during underground coal gasification are presented. The factors having the greatest influence on gas generation in the reaction channel have been identified. Originality. Research results indicate the possibility of improving the process of underground coal gasification. The revealed relationships between different factors contribute to a deeper understanding of the chemical and physical processes in the reaction channel. Practical implications. The results obtained can be used to optimize the underground coal gasification process, increase the productivity and quality of gas generation. The specified results can serve as a basis for further scientific research and innovative developments in obtaining an alternative type of fuel.

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35

Mallett, CW. "Environmental controls for underground coal gasification." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 232, no. 1 (August 2, 2017): 47–55. http://dx.doi.org/10.1177/0957650917723733.

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Effective environmental management of an underground coal gasification pilot has been demonstrated at Kogan in Queensland, Australia. It commenced with selection of a suitable site with a coal seam surrounded by impervious rocks that provided a gas seal for the gasifier and sufficient groundwater pressure to constrain lateral loss of gas and chemicals through coal fractures. Project infrastructure was specified to withstand the temperatures and pressures experienced during gasification and gas processing. During syngas production in the second gasifier, Panel 2, it was shown that all pyrolysis products of environmental concern were retained within the gasifier. This was achieved by maintaining continuous groundwater inflow into the gasifier cavity through control of the relative pressures of the gasifier and surrounding groundwater. In Panel 1, it was shown that when pyrolysis products migrated out of the cavity, they were quickly detected and by modifying relative pressures to increase groundwater inflow the original groundwater conditions were restored. Following production, the cavities were decommissioned and in Panel 2 steam cleaning of the cavity removed 92% of the chemical load from the cavity. As a result, relatively low concentrations of pyrolysis products remained in the cavity. Fate and transport modelling predicted that these products will not migrate into the regional groundwater and will naturally degrade within three decades.

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Proshunin, Yu E., and A. M. Poturilov. "Underground gasification of coal and lignite." Coke and Chemistry 59, no. 10 (October 2016): 370–79. http://dx.doi.org/10.3103/s1068364x16100082.

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Ahmed Qamar, Rizwan, Asim Mushtaq, Ahmed Ullah, and Zaeem Uddin Ali. "Designing of Underground Coal Gasification Unit." Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 71, no. 2 (May 27, 2020): 103–33. http://dx.doi.org/10.37934/arfmts.71.2.103133.

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38

Walker, Leonard Keith. "Underground coal gasification: issues in commercialisation." Proceedings of the Institution of Civil Engineers - Energy 167, no. 4 (November 2014): 188–95. http://dx.doi.org/10.1680/ener.14.00003.

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Walker, L. K. "Commercial development of underground coal gasification." Proceedings of the Institution of Civil Engineers - Energy 160, no. 4 (November 2007): 175–80. http://dx.doi.org/10.1680/ener.2007.160.4.175.

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Cove, James, and Robert Oliver. "THIRTEENTH ANNUAL UNDERGROUND COAL GASIFICATION SYMPOSIUM." Petroleum Science and Technology 6, no. 1 (1988): 125–27. http://dx.doi.org/10.1080/08843758808915878.

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41

Jain, P. K. "Underground Coal Gasification – Experience of ONGC." IOP Conference Series: Earth and Environmental Science 76 (July 2017): 012004. http://dx.doi.org/10.1088/1755-1315/76/1/012004.

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Ghose, Mrinal K., and Biswajit Paul. "Underground coal gasification: a neglected option." International Journal of Environmental Studies 64, no. 6 (December 2007): 777–83. http://dx.doi.org/10.1080/00207230701775375.

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LIU, Shu-qin, Jing-gang LI, Mei MEI, and Dong-lin DONG. "Groundwater Pollution from Underground Coal Gasification." Journal of China University of Mining and Technology 17, no. 4 (December 2007): 467–72. http://dx.doi.org/10.1016/s1006-1266(07)60127-8.

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Khan, Md, Joseph Mmbaga, Ahad Shirazi, Japan Trivedi, Qingzia Liu, and Rajender Gupta. "Modelling Underground Coal Gasification—A Review." Energies 8, no. 11 (November 6, 2015): 12603–68. http://dx.doi.org/10.3390/en81112331.

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Mastalerz, Jerzy, Maciej S. Matyjaszczyk, and Jerzy Rauk. "Steam decomposition in underground coal gasification." Industrial & Engineering Chemistry Research 26, no. 2 (February 1987): 391–97. http://dx.doi.org/10.1021/ie00062a039.

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Imran, Muhammad, Dileep Kumar, Naresh Kumar, Abdul Qayyum, Ahmed Saeed, and Muhammad Shamim Bhatti. "Environmental concerns of underground coal gasification." Renewable and Sustainable Energy Reviews 31 (March 2014): 600–610. http://dx.doi.org/10.1016/j.rser.2013.12.024.

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Sadovenko, I. A., and A. V. Inkin. "Method for Stimulating Underground Coal Gasification." Journal of Mining Science 54, no. 3 (May 2018): 514–21. http://dx.doi.org/10.1134/s1062739118033941.

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Mellors, Robert, X. Yang, J. A. White, A. Ramirez, J. Wagoner, and D. W. Camp. "Advanced geophysical underground coal gasification monitoring." Mitigation and Adaptation Strategies for Global Change 21, no. 4 (July 1, 2014): 487–500. http://dx.doi.org/10.1007/s11027-014-9584-1.

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Liu, Hongtao, Feng Chen, Yuanyuan Wang, Gang Liu, Hong Yao, and Shuqin Liu. "Experimental Study of Reverse Underground Coal Gasification." Energies 11, no. 11 (October 29, 2018): 2949. http://dx.doi.org/10.3390/en11112949.

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Underground coal gasification (UCG) produces less pollution and is safer than traditional coal mining. In order to investigate the effects of different gasifying agents or comprehensive analyses of the characteristics of the gas components in the three zones for the reverse underground coal gasification process, a model test was carried out. The results showed that the oxygen concentration of a gasifying agent is recommended to be higher than 21%, which will lead to more combustible gases and a higher calorific value of gas. Higher flow rates and oxygen content generally afforded more desirable gas compositions and calorific values, with the latter as high as 1430.19 kcal/Nm3. For the enriched oxygen gasifying agent in the reverse gasification process, the flow increase from 10 to 20 Nm3/h affords a rapid increase in the growth rate of the flame front, from 1.80 to 4.88 m/day, which is much faster than that for the air gasifying agent. Increasing the gas injection rate and oxygen concentration will increase the growth rate of the flame front. This affects the distribution of the three zones and further leads to different characteristics of the gas components.

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Wiatowski, Marian, Krzysztof Kapusta, Aleksandra Strugała-Wilczek, Krzysztof Stańczyk, Alberto Castro-Muñiz, Fabián Suárez-García, and Juan Ignacio Paredes. "Large-Scale Experimental Simulations of In Situ Coal Gasification in Terms of Process Efficiency and Physicochemical Properties of Process By-Products." Energies 16, no. 11 (May 31, 2023): 4455. http://dx.doi.org/10.3390/en16114455.

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This paper presents a series of surface experiments simulating underground coal gasification (UCG). The main goal of the experiments was to investigate the influence of the gasification medium and the coal rank on the gasification process. Four multi-day trials were carried out using a laboratory gasification facility designed for the large-scale experimental simulations of UCG and located in the Experimental Mine “Barbara”, located at Mikołów, Poland. Two Polish bituminous coals were investigated: coal sourced from “Piast-Ziemowit” mine and coal sourced from “Wesoła” mine. Each of the two coals was gasified in two separate experiments using oxygen-enriched air (OEA) and pure oxygen as the respective gasifying agents. Gasification with oxygen resulted in significantly higher gas quality and higher process efficiency than gasification with OEA. Higher concentrations of hydrogen (23.2% and 25.5%) and carbon monoxide (31.8% and 33.4%) were obtained when oxygen was used as a gasifying reagent, while lower concentrations were obtained in the case of gasification with OEA (7.1% and 9.5% of hydrogen; 6.4% and 19.7% of carbon monoxide). Average gas calorific values were 7.96 MJ/Nm3 and 9.14 MJ/Nm3 for the oxygen experiments, compared to 2.25 MJ/Nm3 and 3.44 MJ/Nm3 for the OEA experiments (“Piast-Ziemowit” coal and “Wesoła” coal, respectively). The higher coalification degree of “Wesoła” coal (82.01% of carbon) compared to the “Piast-Ziemowit” coal (68.62% of carbon) definitely improves the gas quality and energy efficiency of the process. The rate of water condensate production was higher for the oxygen gasification process (5.01 kg/h and 3.63 kg/h) compared to the OEA gasification process (4.18 kg/h and 2.63 kg/h, respectively), regardless of the type of gasified coal. Additionally, the textural characteristics (porosity development) of the chars remaining after coal gasification experiments were analyzed. A noticeable development of pores larger than 0.7 nm was only observed for the less coalified “Piast-Ziemowit” coal when analyzed under the more reactive atmosphere of oxygen.

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Journal articles on the topic 'Underground coal gasification'

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