• Title, Summary, Keyword: coal

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Response of coal rock apparent resistivity to hydraulic fracturing process

  • Song, Dazhao;Wang, Enyuan;Qiu, Liming;Jia, Haishan;Chen, Peng;Wei, Menghan
    • Geomechanics and Engineering
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    • v.14 no.6
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    • pp.581-588
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    • 2018
  • In order to explore the comprehensive evaluation means of the extent of hydraulic fracturing region in coal seams, we analyzed the feasibility of detecting the response of coal rock direct current (DC) apparent resistivity to hydraulic-fracturing using Archie's theory, and conducted experimental researches on the response of DC resistivity in the hydraulic fracturing process using small-scale coal rock samples. The results show that porosity and water saturation are the two factors affecting the apparent resistivity of coal rock while hydraulic fracturing. Water has a dominant effect on the apparent resistivity of coal rock samples. The apparent resistivity in the area where water flows through is reduced more than 50%, which can be considered as a core affect region of hydraulic fracturing. Stress indirectly impacts the apparent resistivity by changing porosity. Before hydraulic fracturing, the greater axial load applied, the more serious the rupture in the samples, resulting in the greater apparent resistivity. Apparent resistivity testing is a potential regional method to evaluate the influence range of hydraulic fracturing in coal seams.

Manager's Attitude about Health Management of Workers in Coal Mine Industry (석탄광업소장의 근로자 건강관리에 대한 태도)

  • Rhee, Kyung-Yong;Hong, Jeong-Pyo
    • Journal of Preventive Medicine and Public Health
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    • v.22 no.2
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    • pp.197-207
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    • 1989
  • This study was planned to investigate employer's attitude about health management of workers in coal mine industry. The sample size was 38.3% (178 coal mine industries) of total 463 coal mine industries. The mailing survey was used to collecting data of coal mine industry and manager of coal mine industry. Distribution of attitude about health management of workers in coal mine industry, specifically necessity and availability of some items of health management and some apparatus of working environment, was skewed to positive attitude. While recognition of susceptability of coal workers' pneumoconiosis was low, that of seriousness of incidence of coal workers' pneumoconiosis was high.

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Geochemical and Physical Properties of the Jangseong and Imported Chinese Coals (장성탄광 석탄과 수입 중국 석탄의 지구화학적 및 물리적 특성)

  • Chon, Hyo Taek;Kim, Myeong Kyun
    • Economic and Environmental Geology
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    • v.28 no.4
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    • pp.381-388
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    • 1995
  • The petrographic, geochemical, and physical properties of the Jangseong and Chinese coals were investigated. The most common mineral matters of Jangseong coal are kaolinite, muscovite, sericite, illite, quartz and pyrophyllite. Mineral matters in Chinese coal are mainly composed of quartz, calcite, dolomite and kaolinite. Jangseong coal ash has higher content of $Al_2O_3$, $K_2O$, $TiO_2$, As, Rb and V, and lower content of CaO, MgO, $Na_2O$, $Fe_2O_3$ and $P_2O_5$ than those of Chinese coal ash. The liquid limit and the plasticity index of Jangseong coal were compared with those of Chinese coal. The result shows that the briquetting ability of Jangseong coal is a little bit better than that of Chinese coal. The briquetting ability is found to be principally dependent on the type and the content of mineral matter in coal, especially clay mineral.

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The Effect of Particle Size on Ignition Characteristics of Pulverized High-Volatile Bituminous Coal

  • Kim, Hyung-Taek
    • Journal of Energy Engineering
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    • v.2 no.3
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    • pp.285-292
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    • 1993
  • A cylindrical-shape, horizontal furnace was used to investigate the effect of particle size on the pulverized coal combustion behavior. Three differently-sized fractions (5, 30, and 44 microns in average diameter) of high-volatile bituminous coal, were burned in the test furnace. Ignition characteristics of pulverized coal flame were determined through the amount of methane in the carrier gas for the self-sustaining flame. Easiest ignition occurred with the immediately-sized coal particles. Ignition of coal jet flame appeared to occur through a gas-phase homogeneous process for particles larger than 30 microns. Below this limiting size, heterogeneous process probably dominated ignition of coal flame. Oxygen concentration of combustion air was varied up to 50%, to determine the oxygen-enrichment effect on the coal ignition behavior. Oxygen enrichment of primary air assisted ignition behavior of pulverized coal flame. However, enrichment of secondary air didn't produce any effect on the ignition behavior.

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The Calculation Method of Coal Pyrolysis Products Depending on the Coal Rank (탄종별 열분해 생성물의 조성 계산방법)

  • Pak, Ho-Young;Seo, Sang-Il
    • Transactions of the Korean hydrogen and new energy society
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    • v.21 no.5
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    • pp.442-451
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    • 2010
  • This paper describes the calculation method to obtain the product composition of coal pyrolysis at high pressure and high temperature. The products of coal pyrolysis should be determined for the coal gasifier simulation, and this is the first step of the coal gasifier simulation. The pyrolysis product distribution greatly affects the coal gasifier efficiency such as carbon conversion, cold gas efficiency and the syngas composition at the outlet of the gasifier. The present calculation method is based on the coal ultimate/proximate analysis and several correlations among gasifier pressure, coal properties and pyrolysis products. The calculated products for 5 coals have been compared with those from the commercial pyrolysis model.

Operation Characteristics of Pilot-Scale Gasification System for Coal Syngas Production (석탄 합성가스 제조를 위한 pilot급 가스화 시스템 운전특성)

  • Chung, Seok-Woo;Jung, Woo-Hyun;Lee, Seung-Jong;Yun, Yong-Seung
    • New & Renewable Energy
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    • v.3 no.4
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    • pp.90-97
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    • 2007
  • Gasification has been regarded as a very important technology to decrease environmental pollution and to obtain higher efficiency. The coal gasification process converts carbon containing coal into a syngas, composed primarily of CO and $H_2$. And the coal syngas can be used as a source for power generation or chemical material production. This paper illustrates the opeartion characteristics and results of pilot-scale coal syngas production facilities. The entrained-bed pilot scale coal gasifier was operated normally in the temperature range of $1,300{\sim}1,400^{\circ}C,\;2{\sim}3kg/cm^2$ pressure. And Indonesian KPC coal produced syngas that has a composition of $46{\sim}54%\;CO,\;20{\sim}26%\;H_2,\;and\;5{\sim}8%\;CO_2$.

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Operation Characteristics of Pilot-Scale Gasification System for Coal Syngas Production (석탄 합성가스 제조를 위한 pilot급 가스화 시스템 운전특성)

  • Chung, Seok-Woo;Jung, Woo-Hyun;Lee, Seung-Jong;Yun, Yong-Seung
    • 한국신재생에너지학회:학술대회논문집
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    • pp.429-432
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    • 2007
  • Gasification has been regarded as a very important technology to decrease environmental pollution and to obtain higher efficiency, The coal gasification process converts carbon containing coal into a syngas, composed primarily of CO and $H_2$. And the coal syngas can be used as a source for power generation or chemical material production. This paper illustrates the operation characteristics and results of pilot-scale coal syngas production facilities. The entrained-bed pilot scale coal gasifier was operated normally in the temperature range of $1,300{\sim}1,400^{\cdot}C$, $2{\sim}3kg/cm^2$ pressure. And Indonesian KPC coal produced syngas that has a composition of $46{\sim}54$% CO, $20{\sim}26$% $H_2$, and $5{\sim}8$% $CO_2$.

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Characteristics of Co-Combustion of Korean Anthracite with Bituminous Coal in a Circulating Fluidized Bed (순환유동층에서 유.무연탄 혼소 특성)

  • Lee, J.M.;Kim, J.S.;Lee, E.M.
    • Journal of the Korean Society of Combustion
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    • v.10 no.3
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    • pp.1-9
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    • 2005
  • The characteristics of co-combustion of Korean anthracite and bituminous coal was determined in a TGA and a lab-scale CFB reactor. The combustion reactivity of Korean anthracite (E = 51.2 kcal/mol) was much lower than that of bituminous coal (E = 14.5 kcal/mol). As the addition amount of the bituminous coal into the anthracite was increased, the reactivity of the anthracite was found to be improved. The effluent rate of the emission gases from the CFB reactor was not changed appreciably when each coal burned. As the bituminous coal was added, however, the effluent rate of the emissions was increased. The unburned carbon in fly ash from the CFB reactor was decreased with increasing the ratio of bituminous coal in co-combustion. But as the ratio of the bituminous coal was larger than 40 %, the combustion reactivity was not increased any more.

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Combustion Technology for Low Rank Coal and Coal-Biomass Co-firing Power Plant (저급탄 석탄화력 및 석탄-바이오매스 혼소 발전을 위한 연소 기술)

  • Lee, Donghun;Ko, Daeho;Lee, Sunkeun;Baeg, Guyeol
    • 한국연소학회:학술대회논문집
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    • pp.129-132
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    • 2013
  • The low rank coal combustion and biomass-coal co-firing characteristics were reviewed on this study for the power plant construction. The importance of using low rank coal(LRC) for power plant is increasing gradually due to power generation economy and biomass co-firing is also concentrated as power source because it has carbon neutral characteristics to reduce green-house effect. The combustion characteristics of low rank coal and biomass for a 310MW coal firing power plant and a 100MW biomass and coal co-firing power plant were studied to apply into actual power plant design and optimized the furnace and burner design.

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Study on correlation of acoustic emission and plastic strain based on coal-rock damage theory

  • Jin, Peijian;Wang, Enyuan;Song, Dazhao
    • Geomechanics and Engineering
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    • v.12 no.4
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    • pp.627-637
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    • 2017
  • The high positive correlation between plastic strain of loaded coal-rock and AE (acoustic emission) characteristic parameter was studied and proved through AE experiment during coal-rock uniaxial compression process. The results show that plastic strain in the whole process of uniaxial compression can be gained through the experiment. Moreover, coal-rock loaded process can be divided into four phases through analyzing the change of the plastic strain curve : pressure consolidation phase, apparent linear elastic phase, accelerated deformation phase, rupture and development phase, which corresponds to conventional elastic-plastic change law of loaded coal-rock. The theoretical curve of damage constitutive model is in high agreement with the experimental curve. So the damage evolution law of coal rock damage can be indicated by both acoustic emission and plastic strain. The results have great academic and realistic significance for further study of both AE signal characteristics during loaded coal-rock damaged process and the forecasting of coal-rock dynamic disasters.