Adsorption characteristics of supercritical CO2/CH4 on different types of coal and a machine learning approach
ویژگی های جذب CO2 / CH4 فوق بحرانی در انواع مختلف ذغال سنگ و رویکرد یادگیری ماشین-2019
The injection of CO2 into deep coal beds can not only improve the recovery of CH4, but also contribute to the geological sequestration of CO2. The adsorption characteristics of coal determine the amount of the greenhouse gas that deep coal seams can store in place. Using self-developed adsorption facility of supercritical fluids, this paper studied the adsorption behavior of supercritical CO2 and CH4 on three types of coal (anthracite, bituminous coal A, bituminous coal B) under different temperatures of 35 °C, 45 °C and 55 °C. The influence of temperature, pressure, and coal rank on the Gibbs excess and absolute/real adsorption amount of supercritical CO2/CH4 on coal samples has been analyzed. Several traditional isotherm models are applied to interpret the experimental data and Langmuir related models are verified to provide good performances. However, these models are limited to isothermal conditions and are highly depended on extensive experiments. To overcome these deficiencies, one innovative adsorption model is proposed based on machine learning methods. This model is applied to the adsorption data of both this paper and four early publications. It was proved to be highly effective in predicting adsorption behavior of a certain type of coal. To further break the limit of coal type, the second optimization model is provided based on published data. Using the second model, one can predict the adsorption behavior of coal based on the fundamental physicochemical parameters of coal. Overall, working directly with the real data, the machine learning technique makes the unified adsorption model become possible, avoiding tedious theoretical assumptions, derivations and strong limitations of the traditional model.
Keywords: Supercritical CO2 | Supercritical CH4 | Coal | Adsorption model | Machine learning
Simulating mining-induced strata permeability changes
شبیه سازی تغییرات نفوذپذیری اقشار ناشی از معادن-2018
Mining processes fracture the surrounding strata and may modify the flow of groundwater by inducing new fractures or changing the permeability of existing defects. The result of mining-induced permeability changes can be disturbance to aquifers or other surface or sub-surface water bodies. Traditional methods for predicting mining-induced fracture connectivity and enhanced permeability based on empirical strain-based criteria may not satisfy modern regulatory demands, nor adequately reflect local geological, geotechnical and hydro geological conditions. Standard continuum numerical methods may indirectly estimate permeability enhance ment from plastic strains however they are not able to track aperture on flow paths or predict fracture con nectivity. This paper presents a numerical approach that is demonstrated to be capable of representing longwall mining induced fracturing in sedimentary rock masses. By initiating and propagating fractures, determining connectivity and calculating aperture in a piecewise manner on flow paths, we have estimated permeability enhancement from first principles. Fracture intensity and porosity metrics are calculated and identify the height of the enhanced permeability fractured zone above a longwall goaf. Permeability within the overburden is estimated from the Kozeny-Carman permeability–porosity equation. At a mine site studied in detail in this paper a permeability increase from the in situ state is predicted to range from approximately eight orders-of-magnitude in the caved zone to one to two orders-of-magnitude in the strata above the fractured zone. Realistically si mulating cracking, fracturing and crushing of rock strata remains numerically intensive and challenging at the scale of a longwall panel. It is demonstrated in this paper and provides valuable insights into the rockmass response to mining.
Keywords: Coal mining permeability changes ، Coal mining ، Kozeny-Carman ، PFC ، Aquifer interference ، Fracture propagation
The synthetic geo-ecological environmental evaluation of a coastal coal-mining city using spatiotemporal big data: A case study in Longkou, China
ارزیابی زیست محیطی مصنوعی محیط زیست یک شهر زغال سنگ ساحلی با استفاده از داده های بزرگ و طولانی مدت: مطالعه موردی در Longkou، چین-2017
The geological and ecological (geo-ecological) environment of the coastal coal-mining city is a basic element for human subsistence, and it connects the regional economy with social sustainable devel opment. Using Longkou, a coastal mining city, as an example, a geological and ecological environmental quality assessment was conducted based on spatiotemporal big data. Remote sensing images, a digital elevation model (DEM), and precipitation and interpolation processing were used to generate factor layers. A synthetic evaluation index system was set up, including physical geography, geological condi tions, mining intensity, ecological environmental recovery and geological hazards associated with mining. Moreover, an analytical hierarchy process was used to calculate the factor weight of each evaluation factor, and a consistency check was performed to build an assessment model of the geo ecological environment of Longkou. The results indicate that multi-factor spatiotemporal big data pro vide a scientific assessment of the geo-ecological environmental quality with indispensable data and methods. The spatial distribution of geo-ecological environmental quality presented clear specialization of zonality, showing poor quality in the coastal coal mine ore concentration area and good quality in the inland and mountainous areas of Nanshan Mountain. The geo-ecological environmental quality of Longkou was divided into 5 levels as worst, poor, middle, good and better districts. The good and better districts accounted for 76.763% of the total area of the assessment region, indicating that the geo ecological environmental quality of the study area was in good condition. The mining intensity and ecological environment recovery were major factors in determining the regional variation of the geo ecological environment of Longkou. The possible causes inducing uncertainties and limitations in eval uation of the geo-ecological environmental quality were discussed. The model combining AHP with GIS proposed in this paper is an effective means of evaluating regional geo-ecological environmental quality.
Keywords:Remote sensing|Analytic hierarchy process|Geo-ecological environmental assessment|Coal mine concentration area
An integrated system of applying the use of Internet of Things, RFID and Cloud Computing: A case study of logistic management of Electricity Generation Authority of Thailand (EGAT) Mae Mao Lignite Coal Mining, Lampang, Thailand
یک سیستم یکپارچه برای استفاده از اینترنت اشیا، RFID و محاسبات ابری: مطالعه موردی مدیریت لجستیک اداره تولید برق تایلند (EGAT) معادن ذغال سنگ معدن منگن، لمپنگ، تایلند-2017
This research aims to find the best practice of logistic management for Electricity Generation Authority of Thailand (EGAT) Mae Mao Mining, Lampang. This research applied the use of RFID for lignite coal trucks and data from RFID proceed through a server and was stored into a private cloud computing. The equipment and tools used in research was a RFID reader, UHF passive RFID tags, Arduino Mega 2 5 6 0 + Ethernet Shield, PHP, Jason, Node.JS and Maria DB as a database system. The protocol used was MQTT. 27 trucks had UHF passive tags installed, 1 crusher (location number 3) had an RFID reader installed. This system has been operating 24 hours a day 7 days a week, from the beginning of 2015 to mid 2016. The results of the research show that officers who worked for related systems were satisfied. The system enhanced the best practice of lignite coal mining logistic in terms of information checking.
Keywords : logistic | RFID | iOT |Cloud Computing
Experimental study on the minimum ignition temperature of coal dust clouds in oxy-fuel combustion atmospheres
مطالعه تجربی بر روی حداقل درجه حرارت اشتعال ابرهای گرد و غبار ذغال سنگ در اتمسفر احتراق سوخت اکسیژن-2016
Article history:Received 24 October 2015 Received in revised form 22 December 2015Accepted 26 December 2015Available online 31 December 2015Keywords:Ignition temperature Oxygen richO2 /CO2 ambient BAM furnace Ignition mechanismBAM furnace apparatus tests were conducted to investigate the minimum ignition temperature of coal dusts (MITC) in O2 /CO2 atmospheres with an O2 mole fraction from 20 to 50%. Three coal dusts: Indone- sian Sebuku coal, Pittsburgh No.8 coal and South African coal were tested. Experimental results showed that the dust explosion risk increases signiﬁcantly with increasing O2 mole fraction by reducing the min- imum ignition temperature for the three tested coal dust clouds dramatically (even by 100 ◦ C). Compared with conventional combustion, the inhibiting effect of CO2 was found to be comparatively large in dust clouds, particularly for the coal dusts with high volatile content. The retardation effect of the moisture content on the ignition of dust clouds was also found to be pronounced. In addition, a modiﬁed steady- state mathematical model based on heterogeneous reaction was proposed to interpret the observed experimental phenomena and to estimate the ignition mechanism of coal dust clouds under minimum ignition temperature conditions. The analysis revealed that heterogeneous ignition dominates the igni- tion mechanism for sub-/bituminous coal dusts under minimum ignition temperature conditions, but the decrease of coal maturity facilitates homogeneous ignition. These results improve our understanding of the ignition behaviour and the explosion risk of coal dust clouds in oxy-fuel combustion atmospheres.© 2015 Elsevier B.V. All rights reserved.
Keywords: Ignition temperature | Oxygen rich | O2/CO2 ambient | BAM furnace | Ignition mechanism
Experimental investigation of the minimum auto-ignition temperature (MAIT) of the coal dust layer in a hot and humid environment
بررسی تجربی حداقل دمای خودکار احتراق (MAID) از لایه گرد و غبار ذغال سنگ در یک محیط گرم و مرطوب-2016
Ventilation Air Methane (VAM) abatement technology is recognized as a promising and value adding technique for reducing fugitive methane emissions, however, it also increases the potential ﬁre and explosion risks of overheated coal dust. To eliminate these risks from the abatement systems it is ne- cessary to determine the critical combustion characteristics of the minimum auto ignition temperature (MAIT) for a coal dust layer.This study investigates the auto-ignition behavior of coal dust layers in a humid environment with Relative Humidity (RH) 4 80%. The MAIT of four different coal dust samples (Australian coal) with particle sizes below 212 μm and dust layer thicknesses of 5, 12 and 15 mm were measured using a dust layer auto ignition temperature apparatus in accordance with the ASTM E2021 standard.It was concluded that the MAIT of the coal dust layer signiﬁcantly decreases with decreasing particle size. The MAIT for the coal samples with a smaller D50 size were observed to be lower in comparison with samples with a larger D50 size. The dust layer thickness was shown to signiﬁcantly impact on the MAIT. The MAIT increased proportionally with the increasing thickness of the coal dust layer. The effect of the coal dust moisture content and humidity on the MAIT for compacted dust layers was noticeable, whereas, this effect was less important with loose dust layers. In addition, this work investigated and compared the MAIT for a typical coal dust sample based on the existing ASTM and International Elec- trotechnical Commission (IEC) standard procedures for ignition of coal dust layers.& 2016 Elsevier Ltd. All rights reserved.
Keywords: Dust layer | Coal ignition | Explosion | Volatile matter | MAIT | VAM
Effects of ignition energy on fire and explosion characteristics of dilute hybrid fuel in ventilation air methane
اثر انرژی اشتعال در آتش سوزی و ویژگی های انفجار سوخت ترکیبی رقیق در تهویه متان هوا-2016
Deﬂagration explosions of coal dust clouds and ﬂammable gases are a major safety concern in coal mining industry. Accidental ﬁre and explosion caused by coal dust cloud can impose substantial losses and damages to people and properties in underground coal mines. Hybrid mixtures of methane and coal dust have the potential to reduce the minimum activation energy of a combustion reaction. In this study the Minimum Explosion Concentration (MEC), Over Pressure Rise (OPR), deﬂagration index for gas and dust hybrid mixtures (Kst) and explosive region of hybrid fuel mixtures present in Ventilation Air Methane (VAM) were investigated. Experiments were carried out according to the ASTM E1226-12 guideline utilising a 20 L spherical shape apparatus speciﬁcally designed for this purpose.Results: obtained from this study have shown that the presence of methane signiﬁcantly affects explo- sion characteristics of coal dust clouds. Dilute concentrations of methane, 0.75e1.25%, resulted in coal dust clouds OPR increasing from 0.3 bar to 2.2 bar and boosting the Kst value from 10 bar m s—1 to 25 bar m s—1. The explosion characteristics were also affected by the ignitors’ energy; for instance, for a coal dust cloud concentration of 50 g m—3 the OPR recorded was 0.09 bar when a 1 kJ chemical ignitor was used, while, 0.75 bar (OPR) was recorded when a 10 kJ chemical ignitor was used.For the ﬁrst time, new explosion regions were identiﬁed for diluted methane-coal dust cloud mixtures when using 1, 5 and 10 kJ ignitors. Finally, the Le-Chatelier mixing rule was modiﬁed to predict the lower explosion limit of methane-coal dust cloud hybrid mixtures considering the energy of the ignitors.© 2015 Elsevier Ltd. All rights reserved.
Keywords: Hybrid mixture | Deflagration index | Pressure rise | Explosion characteristics | ASTM E2021 | Coal dust | Methane | Explosion | Dust cloud
شبیه¬سازی مبدل افزاینده DC-DC برای کاربرد مدول فتوولتائیک با استفاده از MATLAB/Simulink
سال انتشار: 2013 - تعداد صفحات فایل pdf انگلیسی: 11 - تعداد صفحات فایل doc فارسی: 23
بر پایه تحقیق حاضر، بسیاری از کاستی¬های توان در سرتاسر جهان وجود دارد به ویژه در کشوری مانند هند که مسئله انتقال شبکه همچنان جدی است. تقریبا توان حاصل از سوخت فسیلی بسیار کم شده است، برخی از سوختهای فسیلی عبارتند از ذغال سنگ، ذغال قهوه¬ای، نفت، و گاز. بنابراین بسیاری از آنها به دنبال استخراج توان از انرژی¬های سبز تجدیدپذیر همانند خورشیدی، باد، زیست توده، جزر و مدی و .. هستند که منجر به هیچ آلودگی در محیط زیست نمی¬شود. در این مقاله شبیه¬سازی و تحلیل پنل PV و نیز طراحی مبدل بازده بالا و همچنین شبیه¬سازی اجرا شده است. اگرچه سیستم¬های بر پایه توان خورشیدی، انرژی¬های تجدیدپذیر هستند، در مقایسه با سایر انرژی-های تجدیدپذیراز قبیل باد، زیست توده به تعداد بیشتری از اتصالات شبکه متصل نمی¬شوند. در بسیاری از مراحل مورد نیاز که می¬بایست صورت پذیرد، مبدل بوست بازده بالا به عنوان یک فاکتور اساسی و مهم مورد نیاز است. در این مقاله ولتاژ ورودی به مبدل ارتقا دهنده 15 ولت است که ولتاژ خروجی 55.64 ولت را دریافت می¬کند. receives the output voltage of 55.64V
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