Relationship between Methane Emission and Strata Behavior at Island Coal Face

2012 ◽  
Vol 524-527 ◽  
pp. 662-667
Author(s):  
Xin Xian Zhai ◽  
Fu Lin Wang
Keyword(s):  
Coal Mine ◽  
Methane Emission ◽  
Emission Rate ◽  
Main Roof ◽  
Control Measures ◽  
Emission Rates ◽  
Coal Face ◽  
Coal Wall ◽  
Strata Behavior ◽  
Methane Emission Rate

According to the practical conditions of the island coal face in No.2 Coal Mine of Pingdingshan Coal Company Ltd., China, the strata behaviors and methane emission were monitored and their two relationships were analyzed. The results indicate that strata behavior at coal face affects its methane emission rates at coal wall and goaf，which the quantity of methane emission rate at coal face is largely increasing after main roof weighting. So through the monitor of periodic roof weighting time, larger methane emission rate at coal face can be predicted. Then the related methane control measures can be taken timely.

Spatial and temporal variation of 13C-signature of methane emitted by a temperate mire ecosystem

2021 ◽  
Author(s):  
Janne Rinne ◽  
Patryk Łakomiec ◽  
Patrik Vestin ◽  
Per Weslien ◽  
Julia Kelly ◽  
...  
Keyword(s):  
Spatial Variation ◽  
Temporal Variation ◽  
Methane Emission ◽  
Trophic Status ◽  
Emission Rate ◽  
Temporal Behavior ◽  
Emission Rates ◽  
Spatial Differences ◽  
Mire Ecosystem ◽  
Methane Emission Rate

<p>The net methane emission of any mire ecosystem results from a combination of biological and physical processes, including methane production by archaea, methane consumption by bacteria, and transport of methane from peat to the atmosphere. The complexity of spatial and temporal behavior of methane emission is connected to these.</p><p><sup>13</sup>C-signature of emitted methane offers us a further constraint to evaluate our hypothesis on the processes leading to the variation of methane emission rates. For example, assuming the spatial variation in methane emission rate at microtopographic scale is due to variation in trophic status or variation in methane consumption, will lead to differences in the relation of methane emission rate and its <sup>13</sup>C-signature, expressed as δ<sup>13</sup>C.</p><p>We have measured the methane emission rates and δ<sup>13</sup>C of emitted methane by six automated chambers at a poor fen ecosystem over two growing seasons. The measurements were conducted at Mycklemossen mire (58°21'N 12°10'E, 80m a.s.l.), Sweden, during 2019-2020. In addition, we measured atmospheric surface layer methane mixing ratios and δ<sup>13</sup>C to obtain larger scale <sup>13</sup>C-signatures by the nocturnal boundary-layer accumulation (NBL) approach. All δ<sup>13</sup>C-signatures were derived using the Keeling-plot approach.</p><p>The collected data shows spatial differences of up to 10-15 ‰ in 10-day averages of δ<sup>13</sup>C-signatures between different chamber locations. Temporal variations of 10-day average δ<sup>13</sup>C-signatures from most chamber locations reached over 5 ‰, while the temporal variation of NBL derived δ<sup>13</sup>C-signature was slightly lower.</p><p>The observed spatial variation in the δ<sup>13</sup>C-signature was somewhat systematic, indicating, especially in the middle of the summers, the main control of spatial variation of methane emission to be the trophic status. The temporal changes, measured at different locations, indicate spatial differences in the temporal dynamics at the microtopographic scale. The temporal behavior of larger scale NBL δ<sup>13</sup>C-signature does not fully correspond to the behavior of the chamber derived average δ<sup>13</sup>C-signature.</p>

Influences of Mining Depths of Coal Faces in Duanwang Coal Mine on the Gas Emission Law

2013 ◽  
Vol 295-298 ◽  
pp. 2874-2878
Author(s):  
Xin Xian Zhai ◽  
Yan Wei Zhai ◽  
Shi Wei Zhang
Keyword(s):  
Theoretical Analysis ◽  
Coal Mine ◽  
Production Capacity ◽  
Control Measures ◽  
Shanxi Province ◽  
Coal Face ◽  
Gas Emission ◽  
Average Value ◽  
Mining Depth ◽  
Selection Of

Duanwang Coal Mine in Shanxi province, China, is located at north of Qinshui coalfield which gently inclined and thick seams have been mined. Authorized production capacity of the coal mine is 1.8Mt/a. With the increase of mining depth, the mine gas emission quantity increased. The mine became high gassy one from low gassy mine. Using field measurement and theoretical analysis methods, the following conclusion can be drawn. Gas emission quantity of coal face is directly correlated with mining depth. With the increase of mining depth, both absolute and relative gas emission quantities at coal face increased. The gradient of gas emission quantity was 0.0438-0.1338m3/t/m, the average value was 0.1062m3/t/m. These results would provide a foundation for prediction of the gas emission quantity and selection of gas control measures.

scholarly journals A Satellite Data-Driven Framework to Rapidly Quantify Air Basin-Scale NO<sub>x</sub> Emission and Its Application to the Po Valley during the COVID-19 Pandemic

2021 ◽  
Author(s):  
Kang Sun ◽  
Lingbo Li ◽  
Shruti Jagini ◽  
Dan Li
Keyword(s):  
Emission Rate ◽  
Control Measures ◽  
Nox Emission ◽  
Data Driven ◽  
Anthropogenic Emissions ◽  
Emission Rates ◽  
Po Valley ◽  
Basin Scale ◽  
Emission Changes ◽  
Business As Usual

Abstract. The evolving nature of the COVID-19 pandemic necessitates timely estimates of the resultant perturbations to anthropogenic emissions. Here we present a novel framework based on the relationships between observed column abundance and wind speed to rapidly estimate air basin-scale NOx emission rate and apply it at the Po Valley in Italy using OMI and TROPOMI NO2 tropospheric column observations. The NOx chemical lifetime is retrieved together with the emission rate and found to be 15–20 h in winter and 5–6 h in summer. A statistical model is trained using the estimated emission rates before the pandemic to predict the trajectory without COVID-19. Compared with this business-as-usual trajectory, the real 2020 emission rates show two distinctive drops in March (−41 %) and November (−35 %) that correspond to tightened COVID-19 control measures. The temporal variation of pandemic-induced NOx emission changes qualitatively agree with Google and Apple mobility indicators. The overall net NOx emission reduction in 2020 due to the COVID-19 pandemic is estimated to be 21 %.

scholarly journals Comparing facility-level methane emission rate estimates at natural gas gathering and boosting stations

Elem Sci Anth ◽  
2017 ◽  
Vol 5 ◽  
Author(s):  
Timothy L. Vaughn ◽  
Clay S. Bell ◽  
Tara I. Yacovitch ◽  
Joseph R. Roscioli ◽  
Scott C. Herndon ◽  
...  
Keyword(s):  
Natural Gas ◽  
Confidence Intervals ◽  
Methane Emission ◽  
Emission Rate ◽  
National Study ◽  
Aircraft Measurements ◽  
Component Level ◽  
Facility Level ◽  
Unburned Fuel ◽  
Methane Emission Rate

Coordinated dual-tracer, aircraft-based, and direct component-level measurements were made at midstream natural gas gathering and boosting stations in the Fayetteville shale (Arkansas, USA). On-site component-level measurements were combined with engineering estimates to generate comprehensive facility-level methane emission rate estimates (“study on-site estimates (SOE)”) comparable to tracer and aircraft measurements. Combustion slip (unburned fuel entrained in compressor engine exhaust), which was calculated based on 111 recent measurements of representative compressor engines, accounts for an estimated 75% of cumulative SOEs at gathering stations included in comparisons. Measured methane emissions from regenerator vents on glycol dehydrator units were substantially larger than predicted by modelling software; the contribution of dehydrator regenerator vents to the cumulative SOE would increase from 1% to 10% if based on direct measurements. Concurrent measurements at 14 normally-operating facilities show relative agreement between tracer and SOE, but indicate that tracer measurements estimate lower emissions (regression of tracer to SOE = 0.91 (95% CI = 0.83–0.99), R2 = 0.89). Tracer and SOE 95% confidence intervals overlap at 11/14 facilities. Contemporaneous measurements at six facilities suggest that aircraft measurements estimate higher emissions than SOE. Aircraft and study on-site estimate 95% confidence intervals overlap at 3/6 facilities. The average facility level emission rate (FLER) estimated by tracer measurements in this study is 17–73% higher than a prior national study by Marchese et al.

scholarly journals Support design of main retracement passage in fully mechanised coal mining face based on numerical simulation

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Yalong Li ◽  
Mohanad Ahmed Almalki ◽  
Cheng Li
Keyword(s):  
Numerical Simulation ◽  
Coal Mine ◽  
Surrounding Rock ◽  
Control Measures ◽  
Coal Face ◽  
Support Design ◽  
Working Face ◽  
Surrounding Rock Control ◽  
Mining Face ◽  
Mining Pressure

Abstract For the comprehensive mechanised coal mining technology, the support design of the main withdrawal passage in the working face is an important link to achieve high yield and efficiency. Due to the impact of mining, the roof movement of the withdrawal passage is obvious, the displacement of the coal body will increase significantly, and it is easy to cause roof caving and serious lamination problems, and even lead to collapse accidents, which will affect the normal production of the mine. In this paper, the mining pressure development law of the main withdrawal passage support under the influence of dynamic pressure is designed, the most favourable roof failure form of the withdrawal passage is determined, and the action mechanism and applicable conditions of different mining pressure control measures are studied. The pressure appearance and stress distribution in the final mining stage of fully mechanised coal face are studied by numerical simulation. The deformation and failure characteristics and control measures of roof overburden in the last mining stage of fully mechanised coal face are analysed theoretically. Due to the fact that periodic pressure should be avoided as far as possible after the full-mechanised mining face is connected with the retracement passage, some auxiliary measures such as mining height control and forced roof blasting are put forward on this basis. The relative parameters of the main supporting forms are calculated. The main retracement of a fully mechanised working face in a coal mine channel is put forward to spread the surrounding rock grouting reinforcement, reinforcing roof, and help support and improve the bolt anchoring force, the main design retracement retracement channels in the channel near the return air along the trough for supporting reinforcing surrounding rock control optimisation measures, such as through the numerical simulation analysis, the optimisation measures for coal mine fully mechanised working face of surrounding rock is feasible. Numerical simulation results also show that the surrounding rock control of fully mechanised working face of coal mine design improvements, its main retreat channel under the roof subsidence, cribbing shrank significantly lower, and closer, to better control the deformation of surrounding rock, achieved significant effect, to ensure the safety of coal mine main retracement channel of fully mechanised working face support.

scholarly journals The Stability Factors’ Sensitivity Analysis of Key Rock B and Its Engineering Application of Gob-Side Entry Driving in Fully-Mechanized Caving Faces

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Hong-Sheng Wang ◽  
Hai-Qing Shuang ◽  
Lei Li ◽  
Shuang-Shuang Xiao
Keyword(s):  
Coal Mine ◽  
Orthogonal Experiment ◽  
Engineering Application ◽  
Main Roof ◽  
Fracture Line ◽  
Rock Block ◽  
Fracture Location ◽  
Mechanics Model ◽  
Geological Conditions ◽  
Coal Wall

To reveal the critical factors of the main roof influencing stability of surrounding rocks of roadways driven along goaf in fully-mechanized top-coal caving faces, this paper builds a structural mechanics model for the surrounding rocks based on geological conditions of the 8105 fully-mechanized caving face of Yanjiahe Coal Mine, and the stress and equilibrium conditions of the key rock block B are analyzed, and focus is on analyzing rules of the key rock block B influencing stability of roadways driven along goaf. Then, the orthogonal experiment and the range method are used to confirm the sensitivity influencing factors in numerical simulation, which are the basic main roof height and the fracture location, the length of the key rock block B, and the main roof hardness in turn. It is revealed that the basic main roof height and its fracture location have a greater influence on stability of god-side entry driving. On the one hand, the coal wall and the roof of roadways driven along goaf are damaged, and the deformation of surrounding rocks of roadways and the vertical stress of narrow coal pillars tend to stabilize along with the increase of the basic main roof height. On the other hand, when the gob-side entry is located below the fracture line of the main roof, the damage caused by gob-side entry is the most serious. Therefore, on-site gob-side entry driving should avoid being below the fracture line of the main roof. At last, industrial tests are successfully conducted in the fully-mechanized top-coal caving faces, 8105 and 8215, of Yanjiahe Coal Mine.

scholarly journals METHANE EMISSION FROM PADDY SOIL IN RELATION TO SOIL TEMPERATURE IN TROPICAL REGION

2016 ◽  
Vol 78 (1-2) ◽  
Author(s):  
Fazli P. ◽  
Hasfalina C. M. ◽  
Mohamed Azwan M. Z. ◽  
Umi Kalsom M. S. ◽  
Nor Aini A. R. ◽  
...  
Keyword(s):  
Soil Temperature ◽  
Methane Emission ◽  
Paddy Soil ◽  
Emission Rate ◽  
Paddy Fields ◽  
Tropical Region ◽  
Emission Pattern ◽  
Short Period ◽  
Methane Emission Rate

Methane (CH4) is 21 times more powerful as a greenhouse gas than carbon dioxide. Wetlands including flooded paddy fields are one of the major sources for this gas. Paddy fields are responsible for producing 25 to 54 Tg of CH4 annually. Methane emission rate could be affected by several factors such as irrigation pattern, fertilizer type, soil organic matter and soil temperature. Among them, soil temperature is a determining factor which deserves to be investigated. This study performed with the aim of understanding the effect of soil temperature on the methane emission rate from paddy soil in a short period of time (hourly) and long term (during rice growing season). The results of this study suggest that soil temperature could control the amount of methane emission and there is a positive and strong correlation in both soil temperature and methane emission pattern in short period of time. However, in case of long term trend, other factors such as water management and plant age decreased this correlation from 0.768 to 0.528.

Study on Failure of Soft Overburden of Fully Mechanized Top Coal Caving

2012 ◽  
Vol 446-449 ◽  
pp. 2192-2195
Author(s):  
Jin Shan Wang ◽  
Zhong Chang Wang
Keyword(s):  
Abutment Pressure ◽  
Main Roof ◽  
Material Model ◽  
Stress And Strain ◽  
Similar Material ◽  
Coal Face ◽  
Coal Wall ◽  
Internal Stress Field ◽  
Seam Mining ◽  
Step Distance

The similar material model experiment takes the NO.S2S9 coal face in DaPing coal mine as a prototype to research the characteristics of movement and failure of the soft overburden under fully mechanized top coal caving conditions. The abutment pressure distribution and periodic weighting, caving span are given by monitoring the stress and strain in the similar material model. The results show that rocks fracture extended from button with the advance of workface. The first caving step distance of main roof is 34m. The periodic caving step distance of main roof is 10m. The internal stress field is 10m and the peak abutment pressure point is 80m far away from the coal wall, while the disturbance range in anterior coal wall is 200m. Some cracks are closed in the later stage. The advance of around 300m is the distance that the water flowing fractured zone’s height reaches the highest value. The biggest height of water- flowing fractured zone is 140m. The soft overburden has strong plastic deformation capability. The synchronism of failure and movement of overburden is strong. The failured overburden is compacted and the cracks keep close with the advance of workface. The simulation experiment provides a reference bases for the application and promotion of thick seam mining technology.

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