Underground coal gasification (UCG): A new trend of supply-side economics of fossil fuels

Mao, Fei

doi:10.1016/j.ngib.2016.12.007

Cited by 26 publications

(10 citation statements)

References 3 publications

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“…UCG has a history of development around the world [8], with the majority of field trials being conducted in the United States [9][10][11], European Union [12][13][14], China [15], Australia [16] and the former Soviet Union [17]. Most trials have demonstrated that the UCG can be successfully conducted and that under specific geological and thermodynamic conditions, environmental impact can be minimised.…”

Section: Introductionmentioning

confidence: 99%

Experimental study of underground coal gasification (UCG) of a high-rank coal using atmospheric and high-pressure conditions in an ex-situ reactor

Zagorščak

Sadasivam

Thomas

et al. 2020

Fuel

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This paper presents the results of an extensive experimental analysis of underground coal gasification (UCG) using large bulk samples in an ex-situ reactor under atmospheric and high-pressure (30 bar) conditions. The high-rank coal obtained from the South Wales (UK) coalfield is employed for that purpose. The aim of this investigation is to define the gas production rates, gas composition, gas calorific value, process energy efficiency and temperature changes within the UCG reactor during the gasification process based on the pre-defined reactants and flow rates. Two UCG trials, each lasting 105 hours, consisted of six stages where the influences of oxygen, water, air and oxygen enriched air (OEA) under different flow conditions on the gasification process were investigated. Based on the results of two multi-day experiments, it is demonstrated that the gasification under high pressure conditions produces syngas with higher average calorific value (8.49 MJ/Nm 3 ) in comparison to syngas produced at atmospheric pressure conditions (6.92 MJ/Nm 3 ). Hence, the overall energy efficiency of the high-pressure experiment is higher compared to the atmospheric pressure test, i.e. 57.67% compared to 51.72%. This is related to the fact that the high-pressure gasification produces more methane (11.97 vol.%) than the atmospheric pressure gasification (2.30 vol.%). Under elevated pressure, the temperatures recorded in the roof strata are about 100°C higher compared to the UCG process under atmospheric pressure conditions. This work provides new insights into the gasification of carbon-rich coals subject to different gasification regimes and pressures.

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Section: Introductionmentioning

confidence: 99%

Experimental study of underground coal gasification (UCG) of a high-rank coal using atmospheric and high-pressure conditions in an ex-situ reactor

Zagorščak

Sadasivam

Thomas

et al. 2020

Fuel

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“…In oxygen technology (i.e., typically a mixture of oxygen and water vapor), the calorific value is usually in the range of 9-14 MJ/Nm 3 [39]. Optimal control is the most investigated field in UCG within academic research.…”

Section: Control Of Ucgmentioning

confidence: 99%

“…At the fire face, there are high temperatures (up to 1200-1300°C). An extensive overview of UCG can be found in [9,12,39].…”

Section: Introductionmentioning

confidence: 99%

Model Predictive Control of UCG: An Experiment and Simulation Study

Kačur

Flegner

Durdán

et al. 2019

ITC

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Underground coal gasification (UCG) is a potential technology that enables to mine coal without traditional mining equipment. The coal is gasified deep in underground and produced syngas is processed on the surface. The most important technical problem in UCG is unstable quality of syngas and control. This paper proposes advanced control based on an adaptive predictive controller. The maintaining of desired calorific value depends on flow rates of gasification agents injected to the underground geo-reactor and controlled exhaust. The paper proposes a physical model of UCG technology and applies a method of multivariate adaptive regression splines (MARS) to model the gasification process. This method satisfactorily approximates nonlinearity in the process variables. The paper proposes adaptive model predictive control (MPC) using online model estimation and applied it on the MARS model of UCG that imitates the real process. The results have shown that optimization of manipulation variables can replace manual control in UCG. Getting better quality of syngas depends on setpoints, optimized manipulation variables, and constraints used in MPC. In simulations, the adaptive MPC has shown better performance in comparison with manual and PI control.

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“…Advantages of the mentioned technology are as follows: coal is not hoisted to the surface, there are no large rock volumes to be placed somewhere, the terrain integrity is not disturbed, there is no subsidence due to formation of underground voids, and there is no need in using additional chemical reagents that have negative impact on the environment [45][46][47]. Thus, all the technological operations of underground coal gasification are performed from the earth's surface without miners' underground operations.…”

Section: Introductionmentioning

confidence: 99%

Experimental Studies of the Effect of Design and Technological Solutions on the Intensification of an Underground Coal Gasification Process

et al. 2021

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This paper represents the results of experimental studies of physical modeling of the underground coal gasification process in terms of implementation of design and technological solutions aimed at intensification of a gasification process of thin coal seams. A series of experimental studies were performed in terms of a stand unit with the provided criteria of similarity to field conditions as well as kinetics of thermochemical processes occurring within a gas generator. Hard coal (high volatile bituminous coal) was selected as the raw material to be gasified, as that coal grade prevails in Ukrainian energy balance since it is represented by rather great reserves. Five blow types were tested during the research (air, air–steam, oxygen–steam, oxygen–enriched, and carbon dioxide and oxygen). As a result, the effect of tightness of a gas generator on the quantitative and qualitative parameters of coal gasification while varying the blow by reagents and changing the pressure in a reaction channel has been identified. Special attention was paid to the design solutions involving blow supply immediately into the combustion face of a gas generator. The experimental results demonstrate maximum efficiency of the applied gas generator design involving flexible pipelines and activator in the reaction channel and a blow direction onto the reaction channel face combined with blow stream reversing which will make it possible to improve caloricity of the generator gas up to 18% (i.e., from 8.4 to 12.8 MJ/m3 depending upon a blow type). Consideration of the obtained results of physical modelling can be used with sufficient accuracy to establish modern enterprises based on the underground coal seam gasification; this will help develop more efficiently the substandard coal reserves to generate heat energy as well as power-producing and chemical raw material. The research conclusions can provide technical reference for developing a new generation of underground coal gasification technology.

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Underground coal gasification (UCG): A new trend of supply-side economics of fossil fuels

Cited by 26 publications

References 3 publications

Experimental study of underground coal gasification (UCG) of a high-rank coal using atmospheric and high-pressure conditions in an ex-situ reactor

Experimental study of underground coal gasification (UCG) of a high-rank coal using atmospheric and high-pressure conditions in an ex-situ reactor

Model Predictive Control of UCG: An Experiment and Simulation Study

Experimental Studies of the Effect of Design and Technological Solutions on the Intensification of an Underground Coal Gasification Process

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