scholarly journals Evaluation of a Compact Coaxial Underground Coal Gasification System Inside an Artificial Coal Seam

Energies ◽  
2018 ◽  
Vol 11 (4) ◽  
pp. 898 ◽  
Author(s):  
Fa-qiang Su ◽  
Akihiro Hamanaka ◽  
Ken-ichi Itakura ◽  
Gota Deguchi ◽  
Wenyan Zhang ◽  
...  
Keyword(s):  
Coal Seam ◽  
Large Scale ◽  
Horizontal Well ◽  
Coal Gasification ◽  
Calorific Value ◽  
Ex Situ ◽  
Underground Coal Gasification ◽  
Study Results ◽  
Geological Conditions ◽  
Feasible Option

The Underground Coal Gasification (UCG) system is a clean technology for obtaining energy from coal. The coaxial UCG system is supposed to be compact and flexible in order to adapt to complicated geological conditions caused by the existence of faults and folds in the ground. In this study, the application of a coaxial UCG system with a horizontal well is discussed, by means of an ex situ model UCG experiment in a large-scale simulated coal seam with dimensions of 550 × 600 × 2740 mm. A horizontal well with a 45-mm diameter and a 2600-mm length was used as an injection/production well. During the experiment, changes in temperature field and product gas compositions were observed when changing the outlet position of the injection pipe. It was found that the UCG reactor is unstable and expands continuously due to fracturing activity caused by coal crack initiation and extension under the influence of thermal stress. Therefore, acoustic emission (AE) is considered an effective tool to monitor fracturing activities and visualize the gasification zone of coal. The results gathered from monitoring of AEs agree with the measured data of temperatures; the source location of AE was detected around the region where temperature increased. The average calorific value of the produced gas was 6.85 MJ/Nm3, and the gasification efficiency, defined as the conversion efficiency of the gasified coal to syngas, was 65.43%, in the whole experimental process. The study results suggest that the recovered coal energy from a coaxial UCG system is comparable to that of a conventional UCG system. Therefore, a coaxial UCG system may be a feasible option to utilize abandoned underground coal resources without mining.

Ex Situ UCG Model Experiments with Oxygen Enriched Air in an Artificial Coal Seam

2017 ◽  
Vol 737 ◽  
pp. 379-384
Author(s):  
Fa Qiang Su ◽  
Ken-ichi Itakura ◽  
Akihiro Hamanaka ◽  
Gota Deguchi ◽  
Kohki Sato ◽  
...  
Keyword(s):  
Coal Seam ◽  
Coal Gasification ◽  
Calorific Value ◽  
Close Correlation ◽  
Gas Production ◽  
Ex Situ ◽  
Underground Coal Gasification ◽  
Coal Consumption ◽  
Gas Leakage ◽  
Gasification Reaction

Underground Coal Gasification (UCG) demands precise evaluation of the combustion area in the coal seam. Especially, the monitoring of fracture activity in the coal seam and around rock is important not only for efficient gas production but also for estimation of subsidence and gas leakage to the surface. For this objective, laboratory experiments were conducted using the simulated UCG models. This paper also investigated gas energy for coal consumption, the production gas quantity and heat value, the application of oxygen element balance in the gasification reaction process, and the gas composition obtained in this study. During burning of the coal, temperatures inside the coal, contents of product gases and acoustic emission (AE) activities were monitored successively under the control of feeding gas (air/oxygen and steam) flow rate. Comparison of the temperature variation and accumulated AE event curves revealed a close correlation between them. The local change of temperature inside the coal induced fractures with AE. The AE activity was related closely to the local changes of temperature inside the model. The evaluation of gas energy recovery calculated from the obtained product gas provided a fair evaluation for the coal consumed, and the quantity of gas product and calorific value obtained from the UCG process.

scholarly journals Monitoring and evaluation of simulated underground coal gasification in an ex-situ experimental artificial coal seam system

2018 ◽  
Vol 223 ◽  
pp. 82-92 ◽  
Author(s):  
Fa-qiang Su ◽  
Akihiro Hamanaka ◽  
Ken-ichi Itakura ◽  
Wenyan Zhang ◽  
Gota Deguchi ◽  
...  
Keyword(s):  
Coal Seam ◽  
Coal Gasification ◽  
Monitoring And Evaluation ◽  
Ex Situ ◽  
Underground Coal Gasification

scholarly journals Regression Models Utilization to the Underground Temperature Determination at Coal Energy Conversion

Energies ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5444
Author(s):  
Milan Durdán ◽  
Marta Benková ◽  
Marek Laciak ◽  
Ján Kačur ◽  
Patrik Flegner
Keyword(s):  
Coal Seam ◽  
Regression Model ◽  
Regression Models ◽  
Coal Gasification ◽  
Cavity Growth ◽  
Temperature Data ◽  
Ex Situ ◽  
Underground Coal Gasification ◽  
Gasification Process ◽  
Cavity Growth Rate

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.

scholarly journals A COMPARATIVE STUDY OF DATA-DRIVEN MODELING METHODS FOR SOFT-SENSING IN UNDERGROUND COAL GASIFICATION

2019 ◽  
Vol 59 (4) ◽  
pp. 322-351
Author(s):  
Ján Kačur ◽  
Milan Durdán ◽  
Marek Laciak ◽  
Patrik Flegner
Keyword(s):  
Coal Gasification ◽  
Calorific Value ◽  
Multivariate Adaptive Regression Splines ◽  
Ex Situ ◽  
Gaussian Kernel ◽  
Support Vector ◽  
Underground Coal Gasification ◽  
Process Data ◽  
Adaptive Regression ◽  
Data Driven Modeling

Underground coal gasification (UCG) is a technological process, which converts solid coal into a gas in the underground, using injected gasification agents. In the UCG process, a lot of process variables can be measurable with common measuring devices, but there are variables that cannot be measured so easily, e.g., the temperature deep underground. It is also necessary to know the future impact of different control variables on the syngas calorific value in order to support a predictive control. This paper examines the possibility of utilizing Neural Networks, Multivariate Adaptive Regression Splines and Support Vector Regression in order to estimate the UCG process data, i.e., syngas calorific value and underground temperature. It was found that, during the training with the UCG data, the SVR and Gaussian kernel achieved the best results, but, during the prediction, the best result was obtained by the piecewise-cubic type of the MARS model. The analysis was performed on data obtained during an experimental UCG with an ex-situ reactor.

scholarly journals Characterisation of the Contaminants Generated from a Large-Scale Ex-Situ Underground Coal Gasification Study Using High-Rank Coal from the South Wales Coalfield

2020 ◽  
Vol 231 (10) ◽  
Author(s):  
Sivachidambaram Sadasivam ◽  
Renato Zagorščak ◽  
Hywel Rhys Thomas ◽  
Krzysztof Kapusta ◽  
Krzysztof Stańczyk
Keyword(s):  
Iron Oxide ◽  
Large Scale ◽  
Coal Gasification ◽  
Produced Water ◽  
High Rank ◽  
Ex Situ ◽  
Underground Coal Gasification ◽  
The South ◽  
South Wales ◽  
Pressure Experiment

Abstract This paper presents an analysis of contaminants generated from large-scale, laboratory-based, underground coal gasification (UCG) experiments using a high-rank coal from the South Wales Coalfield. The experiments were performed at atmospheric and elevated pressures (30 bar) by varying the oxidants’ composition. The experiments were designed to predict the amount of produced water and contaminants generated at each stage of the operating conditions. The mass balance of water supplied and produced in the experiments was accounted for. Chemical analyses of produced water, char and ash contents were performed to quantify the inorganic and organic chemical parameters. Most of the contaminant concentrations in the produced water from the 30-bar pressure experiment were lower than the concentrations generated from the atmospheric pressure experiment. The measured concentrations of the inorganic chemical species and the inorganic parameters of the coal seam water from the South Wales Coalfield were used in theoretical calculations to predict the dominant equilibrium species concentrations in a hypothetical scenario of effluent contaminated groundwater. The biodegradation of organic contaminants such as phenol, benzene and sorbed fractions of inorganic contaminants from the produced water on iron oxide in the ash residue was predicted using existing biotransformation kinetics and surface complexation models, respectively. The biodegradation of phenol and benzene would be a slow process even at optimum conditions and the iron oxide left in the cavity can act as a sorbent for a few inorganic species. The evidence from the present study suggests future work towards (i) developing an appropriate water treatment process during gas cleaning, (ii) operational procedure (pressure and proportions of oxidant) and (iii) developing UCG-specific experimental prediction of contaminant transportation and transformation kinetics.

scholarly journals Model-Free Control of UCG Based on Continual Optimization of Operating Variables: An Experimental Study

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4323
Author(s):  
Ján Kačur ◽  
Marek Laciak ◽  
Milan Durdán ◽  
Patrik Flegner
Keyword(s):  
Experimental Study ◽  
Coal Gasification ◽  
Calorific Value ◽  
Ex Situ ◽  
Underground Coal Gasification ◽  
Water Steam ◽  
Operating Variables ◽  
Model Free ◽  
Optimization Task ◽  
Model Free Control

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.

Field test of large-scale hydrogen manufacturing from underground coal gasification (UCG)

2008 ◽  
Vol 33 (4) ◽  
pp. 1275-1285 ◽  
Author(s):  
Lanhe Yang ◽  
Xing Zhang ◽  
Shuqin Liu ◽  
Li Yu ◽  
Weilian Zhang
Keyword(s):  
Field Test ◽  
Large Scale ◽  
Coal Gasification ◽  
Underground Coal Gasification

Underground Сoal Gasification Efficiency in Areas of High Faulting Frequency

2017 ◽  
Vol 25 ◽  
pp. 118-127
Author(s):  
Vasyl Lozynskyi
Keyword(s):  
Coal Seam ◽  
Coal Gasification ◽  
Analytical Calculation ◽  
Underground Coal Gasification ◽  
Practical Application ◽  
Gasification Efficiency ◽  
Rational Order ◽  
Coal Reserves ◽  
Gasification Technology ◽  
Generator Gas

The purpose of this paper is substantiating of efficiency during application of borehole underground coal gasification technology based on target coal seam geology. Comprehensive methodology that included analytical calculation is implemented in the work. To determine the efficiency of coal seam gasification in faulting areas, an economic calculation method was developed. The obtained conditions of coal seam allow to provide rational order of mine workings. Conclusions regarding the implementation of the offered method are made on the basis of undertaken investigations. 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.

The Concept of Mining Enterprises Progress on the Basis of Underground Coal Gasification Method Characteristic

2019 ◽  
Vol 291 ◽  
pp. 137-147
Author(s):  
Volodymyr Falshtynskyi ◽  
Roman Dychkovskyi ◽  
Pavlo Saik ◽  
Vasyl Lozynskyi ◽  
Victor Sulaiev ◽  
...  
Keyword(s):  
Coal Seam ◽  
Coal Gasification ◽  
Thermal Power ◽  
Geometrical Parameters ◽  
Underground Coal Gasification ◽  
Additional Energy ◽  
Efficient Operation ◽  
Gaseous State ◽  
Gaseous Fuels ◽  
Thermal Generator

The authors of the paper consider the concept of further prospective development of mining enterprises. The basis of this concept are scientific results obtained during the study of physical and chemical processes of solids conversion into the gaseous state: coal → gaseous fuels. It was established that the main base of development of mining regions is a mining power-chemical complex. The basic segment of which is a well underground coal gasification station. It is established that increase of indicators of efficient operation of the station from gasification is possible by synthesis of technical and technological decisions on the use of coal seam energy. When coal gasification is over, the gasifier passes into a mode of thermal generator with the use of alothermal technique to remove heat and thermic decomposition products from the degassed space of the gasifier. Generator gas at its initial temperature (1100 – 1300oС) around an underground gasifier creates a powerful heat boiler with a temperature regime of 200 – 300oС. It was established that at work of six gasifiers on a coal seam with thickness of 1.0 m with geometrical parameters each at a width of 30 m and at the length of 450 m energy-thermal power will be 237.8 MW. At the same time, additional energy resources can be obtained by involving segments of alternative forms of energy supply to the life cycle of the mining enterprise.

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