scholarly journals Tests to Ensure the Minimum Methane Concentration for Gas Engines to Limit Atmospheric Emissions

Energies ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 44 ◽  
Author(s):  
Marek Borowski ◽  
Piotr Życzkowski ◽  
Rafał Łuczak ◽  
Michał Karch ◽  
Jianwei Cheng
Keyword(s):  
Carbon Dioxide ◽  
Greenhouse Gas ◽  
Methane Concentration ◽  
Coal Mines ◽  
Drainage System ◽  
Hard Coal ◽  
Atmospheric Emissions ◽  
Coal Seams ◽  
Mining Operations ◽  
Methane Drainage

During the extraction of hard coal in Polish conditions, methane is emitted, which is referred to as ‘mine gas’. As a result of the desorption of methane, a greenhouse gas is released from coal seams. In order to reduce atmospheric emissions, methane from coal seams is captured by a methane drainage system. On the other hand, methane, which has been separated into underground mining excavations, is discharged into the atmosphere with a stream of ventilation air. For many years, Polish hard coal mines have been capturing methane to ensure the safety of the crew and the continuity of mining operations. As a greenhouse gas, methane has a significant potential, as it is more effective at absorbing and re-emitting radiation than carbon dioxide. The increase in the amount of methane in the atmosphere is a significant factor influencing global warming, however, it is not as strong as the increase in carbon dioxide. Therefore, in Polish mines, the methane–air mixture captured in the methane drainage system is not emitted to the atmosphere, but burned as fuel in systems, including cogeneration systems, to generate electricity, heat and cold. However, in order for such use to be possible, the methane–air mixture must meet appropriate quality and quantity requirements. The article presents an analysis of changes in selected parameters of the captured methane–air mixture from one of the hard coal mines in the Upper Silesian Coal Basin in Poland. The paper analyses the changes in concentration and size of the captured methane stream through the methane capturing system. The gas captured by the methane drainage system, as an energy source, can be used in cogeneration, when the methane concentration is greater than 40%. Considering the variability of CH4 concentration in the captured mixture, it was also indicated which pure methane stream must be added to the gas mixture in order for this gas to be used as a fuel for gas engines. The balance of power of produced electric energy in gas engines is presented. Possible solutions ensuring constant concentration of the captured methane–air mixture are also presented.

scholarly journals Tests to Ensure the Minimum Methane Concentration for Gas Engines to Limit Atmospheric Emissions

2019 ◽  
Author(s):  
Marek Borowski ◽  
Piotr Życzkowski ◽  
Rafał Łuczak ◽  
Michał Karch ◽  
Jianwei Cheng
Keyword(s):  
Carbon Dioxide ◽  
Greenhouse Gas ◽  
Methane Concentration ◽  
Coal Mines ◽  
Drainage System ◽  
Hard Coal ◽  
Atmospheric Emissions ◽  
Coal Seams ◽  
Mining Operations ◽  
Methane Drainage

During the extraction of hard coal in Polish conditions, methane is emitted, which is referred to as mine gas. As a result of the desorption of methane, a greenhouse gas is released from coal seams. In order to reduce atmospheric emissions, methane from coal seams is captured by a methane drainage system. On the other hand, methane, which has been separated into underground mining excavations, is discharged into the atmosphere with a stream of ventilation air. For many years, Polish hard coal mines have been capturing methane to ensure the safety of the crew and the continuity of mining operations. As a greenhouse gas, methane has a significant potential, as it is more effective at absorbing and re-emitting radiation than carbon dioxide. The increase in the amount of methane in the atmosphere is a significant factor influencing global warming, however, it is not as strong as the increase in carbon dioxide. Therefore, in Polish mines, the methane-air mixture captured in the methane drainage system is not emitted to the atmosphere, but burned as fuel in systems, including cogeneration systems, to generate electricity, heat and cold. However, in order for such use to be possible, the methane-air mixture must meet appropriate quality and quantity requirements. The article presents an analysis of changes in selected parameters of the captured methane-air mixture from one of the hard coal mines in the Upper Silesian Coal Basin in Poland. The paper analyses the changes in concentration and size of the captured methane stream through the methane capturing system. The gas captured by the methane drainage system, as an energy source, can be used in cogeneration, when the methane concentration is greater than 40%. Considering the variability of CH4 concentration in the captured mixture, it was also indicated which pure methane stream must be added to the gas mixture in order for this gas to be used as a fuel for gas engines. The balance of power of produced electric energy in gas engines is presented. Possible solutions ensuring constant concentration of the captured methane-air mixture are also presented.

scholarly journals The Impact of the Coexistence of Methane Hazard and Rock-Bursts on the Safety of Works in Underground Hard Coal Mines

Energies ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 128
Author(s):  
Justyna Swolkień ◽  
Nikodem Szlązak
Keyword(s):  
Rock Burst ◽  
Methane Concentration ◽  
High Energy ◽  
Hard Coal ◽  
Coal Seams ◽  
Safety Level ◽  
Methane Drainage ◽  
Innovative Methods ◽  
Hard Coal Mining ◽  
The Impact

Several natural threats characterize hard coal mining in Poland. The coexistence of methane and rock-burst hazards lowers the safety level during exploration. The most dangerous are high-energy bumps, which might cause rock-burst. Additionally, created during exploitation, safety pillars, which protect openings, might be the reason for the formation of so-called gas traps. In this part, rock mass is usually not disturbed and methane in seams that form the safety pillars is not dangerous as long as they remain intact. Nevertheless, during a rock-burst, a sudden methane outflow can occur. Preventing the existing hazards increases mining costs, and employing inadequate measures threatens the employees’ lives and limbs. Using two longwalls as examples, the authors discuss the consequences of the two natural hazards’ coexistence. In the area of longwall H-4 in seam 409/4, a rock-burst caused a release of approximately 545,000 cubic meters of methane into the excavations, which tripled methane concentration compared to the values from the period preceding the burst. In the second longwall (IV in seam 703/1), a bump was followed by a rock-burst, which reduced the amount of air flowing through the excavation by 30 percent compared to the airflow before, and methane release rose by 60 percent. The analyses presented in this article justify that research is needed to create and implement innovative methods of methane drainage from coal seams to capture methane more effectively at the stage of mining.

scholarly journals Possibilities of Capturing Methane from Hard Coal Deposits Lying at Great Depths

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3542
Author(s):  
Nikodem Szlązak ◽  
Justyna Swolkień
Keyword(s):  
Underground Mining ◽  
Drainage System ◽  
Hard Coal ◽  
Coal Seams ◽  
Second Stage ◽  
Methane Drainage ◽  
Coal Deposits ◽  
Significant Difference ◽  
Flammable Gas ◽  
Deposition Depth

Methane present in coal seams is a natural hazard present during the exploitation of underground mining plants. It is an explosive and flammable gas that is released into mining excavations, and it is necessary to reduce its concentration. Capturing methane while preparing extraction is virtually impossible due to the low permeability of coal resulting from its deposition depth. After the beginning of exploitation and disrupting the seam’s structure, methane is released into mine air. The most common method of minimizing gas released into ventilation air is draining the rock mass. This method allows achieving the desired ventilation parameters but requires appropriate mining techniques in hazardous areas. The article presents the example of methane capture during the operation in the longwall B-15 with an overlying drainage gallery. The authors have highlighted an example of the longwall B-15 that when using this particular drainage method, allowed capturing twice the amount of methane forecasted, thus increasing the efficiency of methane drainage. At the preliminary stage of longwall development, the amount of methane charged by the drainage system had relatively low values, reaching 15 m3/min. In the next few months, these parameters increased and varied between 35 to 55 m3/min. A significant difference in methane capture appeared in the second stage of exploitation, where the highest value of captured methane reached 82 m3/min. This particular longwall example shows that it is crucial to properly design the drainage system for seams with high forecasted methane release. It is worth remembering that using a drainage gallery provides an increase in the methane capture from the desorption zone areas, thus increasing total methane capture in comparison to forecasts.

The Effectiveness of the Methane Drainage of Rock-Mass with a U Ventilation System

2016 ◽  
Vol 61 (3) ◽  
pp. 617-634
Author(s):  
Nikodem Szlązak ◽  
Justyna Swolkień
Keyword(s):  
Methane Emission ◽  
Methane Concentration ◽  
Ventilation System ◽  
Drainage System ◽  
Air Velocity ◽  
Coal Seams ◽  
Methane Drainage ◽  
Roof Caving ◽  
Geological Conditions ◽  
Very High

Abstract Methane drainage is used in Polish coal mines in order to reduce mine methane emission as well as to keep methane concentration in mine workings at safe levels. The article describes the method of methane drainage used in longwall D-2 in seam 410. In Poland, coal seams are frequently mined under difficult geological conditions in the roof and in the presence of very high methane hazard. In such situations, mines usually use a system with roof caving and a U ventilation system, which means that methane is drawn off from a tail entry behind the longwall front. In this system, boreholes are drilled from a tailgate and methane is drawn off from behind longwall face. The article shows the influence of a specific ventilation system on the drainage efficiency at longwall D-2 in seam 410. At this longwall, measurements of methane emission and the efficiency of methane capture were conducted. They consisted in gauging methane concentration, air velocity, absolute air pressure and the amount of methane captured by the drainage system. Experimental data were used to estimate the variations in absolute methane-bearing capacity and ventilation methane, and – most importantly – to gauge the efficiency of methane drainage.

scholarly journals Forecasting Methane Emissions from Hard Coal Mines Including the Methane Drainage Process

Energies ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3840 ◽  
Author(s):  
Magdalena Tutak ◽  
Jarosław Brodny
Keyword(s):  
Neural Networks ◽  
Greenhouse Gas ◽  
Natural Environment ◽  
Underground Mining ◽  
Coal Mines ◽  
Energy Resource ◽  
High Energy ◽  
Methane Emissions ◽  
Hard Coal ◽  
Methane Drainage

With regard to underground mining, methane is a gas that, on the one hand, poses a threat to the exploitation process and, on the other hand, creates an opportunity for economic development. As a result of coal exploitation, large amounts of coal enter the natural environment mainly through ventilation systems. Since methane is a greenhouse gas, its emission has a significant impact on global warming. Nevertheless, methane is also a high-energy gas that can be utilized as a very valuable energy resource. These different properties of methane prompted an analysis of both the current and the future states of methane emissions from coal seams, taking into account the possibilities of its use. For this reason, the following article presents the results of the study of methane emissions from Polish hard coal mines between 1993–2018 and their forecast until 2025. In order to predict methane emissions, research methodology was developed based on artificial neural networks and selected statistical methods. The multi-layer perceptron (MLP) network was used to make a prognostic model. The aim of the study was to develop a method to predict methane emissions and determine trends in terms of the amount of methane that may enter the natural environment in the coming years and the amount that can be used as a result of the methane drainage process. The methodology developed with the use of neural networks, the conducted research, and the findings constitute a new approach in the scope of both analysis and prediction of methane emissions from hard coal mines. The results obtained confirm that this methodology works well in mining practice and can also be successfully used in other industries to forecast greenhouse gas and other substance emissions.

scholarly journals Analysis of methane hazard in longwall working equipped with a powered longwall complex

2020 ◽  
Vol 174 ◽  
pp. 01011
Author(s):  
Leszek Sobik ◽  
Jarosław Brodny ◽  
Gennady Buyаlich ◽  
Pavel Strelnikov
Keyword(s):  
High Performance ◽  
Underground Mining ◽  
Practical Knowledge ◽  
Mining Operation ◽  
Mining Area ◽  
Hard Coal ◽  
Coal Seams ◽  
Methane Drainage ◽  
High Degree ◽  
Advanced Model

Most of currently exploited hard coal seams has a very high degree of methane saturation. Consequently, the mining process of such deposits generates substantial amounts of methane. This in turn increases the risk of fire and/or explosion of this gas. Methane hazard is currently one of the most dangerous threats occurring in the process of underground mining exploitation. In particular, this applies to longwall excavations where the rock mass mining process generates the highest level of this gas. Commonly used high-performance longwall complexes cause an increase in the amount of coal output, which also causes an increase in the amount of methane released. In order to prevent hazardous concentrations, appropriate ventilation systems and atmosphere monitoring in mining excavations are used. The paper discusses currently used methods designed to limit risks caused by methane such as methane drainage. The paper presents an example of the use of an innovative method of analysing methane risk status and measures aimed at minimizing it. The developed method is based on air parameters in the actual mining area which were then used to create a method of ventilation for such excavations. The method combines advanced model analysis and experience of mine employees and integrates academic and practical knowledge. The main objective of the activities presented in the article was to improve the safety of mining operation

Mining Gassy Coal Seams with a Three-Entry Panel Layout

2012 ◽  
Vol 524-527 ◽  
pp. 613-617
Author(s):  
Jun Hua Xue ◽  
Sheng Xue
Keyword(s):  
Coal Mine ◽  
Methane Concentration ◽  
Ventilation System ◽  
Coal Mines ◽  
Distribution Characteristics ◽  
Coal Seams ◽  
Gas Drainage ◽  
Gas Emissions ◽  
Underground Coal Mines

To address the issue of high gas emissions in mining gassy coal seams in underground coal mines, the concept of a three-entry panel layout with a retained goaf-edge gateroad and a “Y” type ventilation system is introduced in this paper. With the layout and ventilation system, distribution characteristics of methane concentration in the panel goaf is analyzed, technologies of gas drainage with boreholes drilled from the retained goaf-edge gateroad and into stress-relieved overlying and underlying seams are described, and an application case of such layout in a coal mine is also presented in this paper.

scholarly journals Comparative Analysis of Methane Concentration Near the Junction of the Longwall and Top Road

2019 ◽  
Vol 27 (3) ◽  
pp. 166-173
Author(s):  
Marian Zmarzły ◽  
Paweł Trzaskalik
Keyword(s):  
Bearing Capacity ◽  
Methane Concentration ◽  
Drainage System ◽  
Negative Influence ◽  
Methane Drainage ◽  
Increased Risk ◽  
Low Costs ◽  
The One ◽  
Fire Threat ◽  
Methane Concentrations

AbstractMining of longwalls ventilated by the „U” method is willingly applied in Polish coal-mines due to low costs of workings maintenance, low costs of ventilation and a lower fire threat because of a limited flow of air through goafs. However, such a way of ventilation may pose an increased risk of methane explosion. For this reason, the “U” ventilation has been limited in longwalls with methane risk. The mining regulations in force provide that ventilation methane-bearing capacity, i.e. the intensity of methane flow into the ventilation air cannot exceed 20 m3 CH4/min. The regulations also provide that in the event the absolute methane-bearing capacity, i.e. a sum of methane released to the ventilation air and captured by the methane drainage system is higher than 25 m3 CH4/min and the “U” method of ventilation is applied, the effectiveness of methane drainage should be minimum 50% in relation to the forecast absolute methane-bearing capacity. To streamline the process of ventilation near the junction of the longwall and the gallery carrying off the used air, auxiliary ventilation means are applied, such as a ventilation partition, a ventube – which supplies air without methane or with a low concentration of methane, injectors etc. Application of these means is limited by the cross-section of the heading carrying off the air from the longwall. Deformations of the ventilating roadway, which is usually located in the one-sided vicinity of goafs, may prevent the use of a ventilation partition, which has a negative influence on the conditions of ventilating the junction of the longwall and ventilating roadway. The author of the article also refers to such conditions, presenting average values and maximum concentrations of methane concentrations recorded with four methane concentration sensors, located in the vicinity of the junction of the longwall and ventilating roadway.

scholarly journals Comparison of Methane Control Methods in Polish and Vietnamese Coal Mines

2018 ◽  
Vol 35 ◽  
pp. 01004
Author(s):  
Marek Borowski ◽  
Zbigniew Kuczera
Keyword(s):  
Coal Mining ◽  
Coal Dust ◽  
Coal Mines ◽  
Hard Coal ◽  
Control Methods ◽  
Prevention Measures ◽  
Methane Drainage ◽  
Hazard Control ◽  
Preventive Actions ◽  
Coal Deposits

Methane hazard often occurs in hard coal mines and causes very serious accidents and can be the reason of methane or methane and coal dust explosions. History of coal mining shows that methane released from the rock mass to the longwall area was responsible for numerous mining disasters. The main source of methane are coal deposits because it is autochthonous gas and is closely related with carbonification and forming of coal deposits. Degree of methane saturation in coal deposits depends on numerous factors; mainly on presence or lack of insulating layers in cover deposit that allow or do not on degasification and easily methane outflow into surroundings. Hence in coal mining there are coal deposits that contain only low degree of methane saturation in places where is lack of insulating layers till high in methane coal deposits occurring in insulating claystones or in shales. Conducting mining works in coal deposits of high methane hazard without using of special measures to combat (ventilation, methane drainage) could be impossible. Control of methane hazard depends also on other co-occuring natural dangers for which used preventive actions eliminate methane hazard. Safety in mines excavating coal deposits saturated with methane depends on the correct estimation of methane hazard, drawn up forecasts, conducted observations, hazard control as well as undertaken prevention measures. Methane risk prevention includes identification and control methods of methane hazards as well as means of combating the explosive accumulation of methane in longwall workings. The main preventive actions in underground coal mines are: effective ventilation that prevents forming of methane fuses or placed methane accumulation in headings ventilated by airflow created by main fans and in headings with auxiliary ventilation, methane drainage using drain holes that are drilled from underground headings or from the surface, methanometry control of methane concentration in the air; location of the sensors is defined by law, additional ventilation equipment used in places of lower intensity of ventilation and places where methane is concentrated.

scholarly journals Analysis of Exploitation Parameters in Drainage Boreholes of the Longwall Demethylation System. Case Study

2021 ◽  
Vol 4 (1) ◽  
pp. 23-39
Author(s):  
Henryk Badura ◽  
Zygmunt Łukaszczyk
Keyword(s):  
Methane Concentration ◽  
Coal Mines ◽  
Extraction Process ◽  
Longwall Face ◽  
Coal Bed ◽  
Hard Coal ◽  
Methane Mixture ◽  
Roof Rocks ◽  
Made In

Abstract In hard coal mines with methane, there is often a need to apply demethylation in order to keep the methane concentration not exceeding 2% in the ventilation air. The basic demethylation method in longwall areas is through drainage boreholes made in the roof rocks of the coal bed, from top gate, in front of the longwall. The drainage boreholes are usually made in bundles, in a fan-shaped arrangement, with several boreholes in each bundle. The paper presents the results of measurements and tests of the efficiency of a bundle of four drainage boreholes drilled approximately 100 m in front of the longwall face. The efficiency of individual boreholes was analyzed in time and depending on the distance of borehole outlets from the longwall face. It was found that there is a large variation in the extraction of air-methane mixture by individual drainage boreholes, as well as large differences in the efficiency of individual drainage boreholes during the longwall extraction process.

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