Laboratory Studies on Evaluation of Gasification Effect for Conversion of Coal Resources in Underground Coal Gasification (UCG) Reactors

2012 ◽  
Vol 600 ◽  
pp. 111-115 ◽  
Author(s):  
Fa Qiang Su ◽  
Ken-ichi Itakura ◽  
Gota Deguchi ◽  
Koutarou Ohga ◽  
Tatsuhiko Goto
Keyword(s):  
Coal Gasification ◽  
Calorific Value ◽  
Clean Energy ◽  
Underground Coal Gasification ◽  
Public Attention ◽  
Experimental Conditions ◽  
Coal Resources ◽  
Clean Energy Technology ◽  
Hole Model ◽  
Coaxial Hole

Underground coal gasification (UCG) as a clean energy technology and efficient way for the conversion of the coal resources into energy in-situ has attracted wide public attention in recent years. Laboratory-scale experiments on coal blocks can provide significant insight into UCG process. The main goal of this study was evaluation of the gasification effect applying L-shape linking-hole and Coaxial-hole UCG models. Experimental results show the gas composition, AE activity and the temperature distribution inside the combustion reactors under similar operating parameters. Positive correlation was found between the temperature and cumulative AE events. The results shown that the gasification of L-shape linking-hole model obtained the average calorific value, as high as 11.3 MJ/m3, whereas in the Coaxial-hole model, the average calorific value of gas produced was only 5.79 MJ/m3under the experimental conditions. Even so, the results of conducted Coaxial-hole UCG experiment provide the original and sorely lacking data base for future new-style UCG research.

Evaluating the costs and achievable benefits of extending technologies for uneconomical coal resources in South Africa: the case of underground coal gasification

2008 ◽  
Vol 19 (4) ◽  
pp. 21-31 ◽  
Author(s):  
M. Zieleniewski ◽  
A.C. Brent
Keyword(s):  
South African ◽  
Coal Gasification ◽  
Economic Value ◽  
Calorific Value ◽  
Underground Coal Gasification ◽  
Direct Process ◽  
Coal Resources ◽  
Geological Surveys ◽  
Safety And Health ◽  
Expected Benefits

As the South African economy relies heavily on its coal resources, these resources should be utilised and managed in the best possible manner. Underground coal gasification (UCG) is one of the leading technologies used where conventional min-ing techniques are uneconomical. UCG delivers gas suitable for synthesis, production of fuels and elec-tricity, or for home usage. The method is perceived as being environmentally friendly and safer than traditional mining. The study summarised in this paper was conducted so as to create a simple model that would allow for the evaluation of UCG process-related costs versus expected benefits in a wider context and under different circumstances. The parameters of the model are: feasibility definition, i.e. maximum possible gas calorific value, based on geological surveys and gasification agents for a pre-defined need; direct process-related costs that are derived from the expected capital and operational expenditures and compared to the value and vol-ume of the gas produced; and assessment of exter-nality costs, i.e. the indirect economic value of envi-ronmental, safety and health benefits. The external-ities concept should encourage governmental agen-cies to consider further investment in UCG technol-ogy as a vehicle for delivering, potentially, high sav-ings in terms of the reduction in the costs of envi-ronmental damage resulting from gaseous emis-sions into the atmosphere, specifically expenditure on national health.

scholarly journals Effect of Lignite Properties on Its Suitability for the Implementation of Underground Coal Gasification (UCG) in Selected Deposits

Energies ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5816
Author(s):  
Krzysztof Kapusta
Keyword(s):  
Moisture Content ◽  
Coal Gasification ◽  
Calorific Value ◽  
Process Efficiency ◽  
Average Moisture Content ◽  
Underground Coal Gasification ◽  
Gasification Process ◽  
Laboratory Setup ◽  
Large Bulk

Two experimental simulations of underground coal gasification (UCG) processes, using large bulk samples of lignites, were conducted in a surface laboratory setup. Two different lignite samples were used for the oxygen-blown experiments, i.e., “Velenje” meta-lignite (Slovenia) and “Oltenia” ortho-lignite (Romania). The average moisture content of the samples was 31.6wt.% and 45.6wt.% for the Velenje and Oltenia samples, respectively. The main aim of the study was to assess the suitability of the tested lignites for the underground coal gasification process. The gas composition and its production rates, as well as the temperatures in the artificial seams, were continuously monitored during the experiments. The average calorific value of gas produced during the Velenje lignite experiment (6.4 MJ/Nm3) was much higher compared to the result obtained for the experiment with Oltenia lignite (4.8 MJ/Nm3). The Velenje lignite test was also characterized by significantly higher energy efficiency, i.e., 44.6%, compared to the gasification of Oltenia lignite (33.4%). The gasification experiments carried out showed that the physicochemical properties of the lignite used considerably affect the in situ gasification process. Research also indicates that UCG can be considered as a viable option for the extraction of lignite deposits; however, lignites with a lower moisture content and higher energy density are preferred, due to their much higher process efficiency.

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.

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 Experimental Study of Reverse Underground Coal Gasification

Energies ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2949 ◽  
Author(s):  
Hongtao Liu ◽  
Feng Chen ◽  
Yuanyuan Wang ◽  
Gang Liu ◽  
Hong Yao ◽  
...  
Keyword(s):  
Growth Rate ◽  
Flame Front ◽  
Oxygen Concentration ◽  
Coal Gasification ◽  
Calorific Value ◽  
Injection Rate ◽  
Underground Coal Gasification ◽  
Gasification Process ◽  
Combustible Gases ◽  
Different Characteristics

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.

scholarly journals RESEARCH OF THE GASIFICATION PROCESS OF WOOD BIOMASS IN A CONTINUOUS LAYER

2017 ◽  
pp. 14-20
Author(s):  
Yo.S. Mysak ◽  
S.S. Lys
Keyword(s):  
Coal Gasification ◽  
Calorific Value ◽  
Clean Energy ◽  
Gaseous Fuel ◽  
Household Waste ◽  
Low Grade ◽  
Regression Equations ◽  
Wood Biomass ◽  
Gas Generator ◽  
Continuous Layer

The gasification technology of wood biomass is an essential problem whose solution will create clean energy as an alternative combustion of fossil fuels and coal gasification. It also can solve the problems of the ecological utilization of industrial and household waste as well as of obtaining cheap energy and improving industrial effects for the environment. The analysis of the theoretical provisions and experimental tests has proved the possibility of processing wood during its gasification in a gas generator with a continuous layer; it is processed into gaseous fuel with the lower calorific value being 1.5 times higher in comparison with the calorific value of the gaseous fuel that is produced by other known gas generators of this type. The experimental results have specified the regression dependence of heat that is produced by burning the synthesis gas during the gasification of low-grade fuel on the fractional composition of the fuel, the amount of air, and the fuel layer height. The resulting regression equations can be the basis for implementing the studied process and its rational management. The equations of the input factors’ dependence on the original setting make it possible to determine every possible parameter of assessing the process under study at any value of the factors between the upper and lower levels. Bibl. 12, Fig. 1, Tab. 2.

scholarly journals Role of Promoters in Hoisting the Catalytic Performance for Enhanced CO Methanation

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Hussain I. ◽  
Jalil A. A. ◽  
Mamat C. R. ◽  
Siang T. J. ◽  
Azami M. S. ◽  
...  
Keyword(s):  
Natural Gas ◽  
Calorific Value ◽  
Clean Energy ◽  
Catalytic Performance ◽  
Energy Sources ◽  
Complete Combustion ◽  
Coal Resources ◽  
Clean Energy Source ◽  
Industrial Level ◽  
Promising Source

The increasing demand of natural gas and its rising cost have urged some countries to take initiatives to fulfil their energy needs. The production of substituted natural gas (SNG) by syngas (CO + H2) from coal or biomass is one of the most effective methods. As a promising source of energy, SNG has attracted much attention on research and applications due to the high demand for environmental protection. It is regarded as a clean energy source and an effective method for the application of coal resources, particularly in the regions with abundant coal resources but scarce natural gas such as in China [1-3]. SNG has attracted increasing attention due to its lower emission of sulphur and particulate matter. SNG is expected to be one of the main energy sources of the 21st century. It is environmentally friendly and less costly, has high calorific value, complete combustion, and smoke free compared to other energy sources. It has significant importance for the industrial level and transportation sectors.

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.

scholarly journals Model Predictive Control of UCG: An Experiment and Simulation Study

2019 ◽  
Vol 48 (4) ◽  
pp. 557-578
Author(s):  
Jan Kacur ◽  
Patrik Flegner ◽  
Milan Durdan ◽  
Marek Laciak
Keyword(s):  
Model Predictive Control ◽  
Predictive Control ◽  
Coal Gasification ◽  
Technical Problem ◽  
Calorific Value ◽  
Multivariate Adaptive Regression Splines ◽  
Underground Coal Gasification ◽  
Mining Equipment ◽  
Real Process

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.

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.

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