• Title/Summary/Keyword: Coal Slurry

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Theoretical Analysis of Ignition of a Coal-Water Slurry Droplets with Interior Temperature Distribution (내부 온도분포를 고려한 Coal-Water Slurry의 점화현상에 관한 이론적 해석)

  • Choi, C.E.;Baek, S.W.;Kim, J.W.
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.7 s.94
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    • pp.1823-1832
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    • 1993
  • CWS(coal-water slurry) is used for application in power plants, boilers, industrial furnaces. A single coal-water slurry droplet ignition has been examined to reveal the basic nature of their evaporation, volatilization and heating processes. The interior droplet temperature distribution has been considered. The effect of coal thermal conductivity, droplet size, water fraction in the slurry, gas temperature and velocity and radiation on the ignition phenomena were also studied. Either increasing the velocity and gas temperature or decreasing the droplet size and water fraction in the slurry may reduce the time for evaporation and ignition delay time.

Spray Characteristics of a Coal Slurry with Liquid Carbon Dioxide (고압 저등급탄-이산화탄소 슬러리 분무특성에 관한 연구)

  • KIM, CHANGYEON;KIM, HAKDUCK;SONG, JUHUN
    • Transactions of the Korean hydrogen and new energy society
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    • v.26 no.4
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    • pp.357-362
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    • 2015
  • There is potential method to utilize the liquid carbon dioxide ($LCO_2$) in coal gasification plants. The $LCO_2$ could be used to effectively transport coal particles instead of conventional carrier such as liquid water ($H_2O$) particularly in wet-fed gasifier. However, there is a lack of fundamental study on the atomization behavior of $LCO_2$ coal slurry under high pressure condition. In this study, the flashing spray characteristics of a coal mixture with $LCO_2$ was examined during a throttling process by using a flow visualization system. The spray of coal water slurry which is in the Rayleigh-type break up mode was significantly different. This difference indicates that the coal water slurry did not effectively transport the coal, as compared to $LCO_2$ coal slurry.

Coal particle distribution inside fuel droplets of high loading CWM (고부하도 CWM 연료방울안에 존재하는 미분탄 분포)

  • 김성준;유영길
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.15 no.2
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    • pp.618-629
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    • 1991
  • The purpose of this experiment is to understand the distribution of coal particles inside CWM droplet which is believed to be a very important factor controlling the flame stability. CWM slurry is atomized by an air assisted twin fluid nozzle. An experimental rig is designed and fabricated. The mean size of coal particle distribution in CWM slurry, atomizing air pressure, coal particle loading in slurry and sampling position inside spray are main experimental variables. The atomized CWM droplets are sampled on the thin white layer of magnesium oxide by the emergency sampling shutter. The sampled coal particles on magnesium oxide layers are collected into test tubes and dispersed completely by Ultra-Sonicator. The size distribution of coal particles inside droplets are measured by Coulter Counter. The presence of coal particle inside the impressions of droplets on magnesium oxide layer are investigated by photo technique. There are quite many droplets which do not have any coal particles. Those are just water droplets, not CWM droplets. The population ratio of droplets without coal particles to toal number of droplets is strongly affected by the mean size of coal particle distribution in slurry and this ration becomes bigger number as the mean size of coal particles be larger. The size distribution of coal particles inside CWM droplets is not even and depends on the size of droplet. Experimental results show that the larger CWM droplets has droplets has bigger mean value of particle size distribution. This trend becomes more evident as the atomizing air pressure is raised and the mean size of coal particles in CWM slurry is bigger. That is, the distribution of coal particles inside CWM dropolets is very much affected by the atomizing air pressure and the mean size of pulverized coal particles in CWM slurry.

Entrained-Flow Coal Water Slurry Gasification (분류층 습식 석탄가스화 기술)

  • Ra, HoWon;Lee, SeeHoon;Yoon, SangJun;Choi, YoungChan;Kim, JaeHo;Lee, JaeGoo
    • Korean Chemical Engineering Research
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    • v.48 no.2
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    • pp.129-139
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    • 2010
  • Coal gasification process, which had developed originally to convert coal from hydrogen and carbon monoxide, has used and developed in many countries because of environmental advantages such as carbon dioxide storage, decrease of pollutants and so on. Generally entrained-flow gasification process using pulverized coal under $75{\mu}m$ is used in Integrated Gas Combined Cycle(IGCC) because of easy scale up and high efficiency of energy conversion. Especially entrained-flow gasifers with coal water slurry have been used in many applications due to its fully developed technologies. In this paper, several technologies for coal-water slurry gasification that involves slurry preparation, burner, gasifier, slag melting and numerical simulation for plant design and operation were investigated. Entrained-flow gasification with coal water slurry can be used for synfuel production, SNG, chemicals as well as IGCC. To develop hybrid gasification process and use different types of coal, it is necessary to develop new technologies that will increase efficiency of the process.

Numerical and experimental study for Datong coal gasification in entrained flow coal gasifier

  • Park, Y. C.;Park, T. J.;Kim, J. H.;Lee, J. G.
    • Proceedings of the Korea Society for Energy Engineering kosee Conference
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    • 2001.11a
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    • pp.69-76
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    • 2001
  • The coal gasification process of a slurry feed type, entrained-flow coal gasifier was numerically predicted in this paper. By divding the complicated coal gasification process into several simplified stages suh as slurry evaporation, coal devolitilisation and two-phase reactions coupled with turbulent flow and two-phase heat transfer, a comprehensive numerical model was constructed to simulate the coal gasification process. The k-$\varepsilon$turbulence model was used for the gas phase flow while the Random-trajectory model was applied to describe the behavior of the coal slurry particles. The unreacted-core shrinking model and modified Eddy Break-Up(EBU) model were used to simulate the heterogeneous and homogeneous reactions, respectively. The simulation results obtained the detailed informations about the flow field, temperature inside the gasifier. Meanwhile, the simulation results were compared with the experimental data as function of $O_2$/coal ratio. It illustrated that the calculated carbon conversions agreed with the measured ones and that the measurd quality of the atngas was better than the calculated one when the $O_2$/coal ratio increases. The result was related with the total heat loss through the gasifier and uncertain kinetics for the heterogeneous reactions.

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The Comparative Study on the Gasification Process between Coal Water Slurry and Dry Pulverized Coal (습식 및 건식 석탄가스화공정에 대한 비교 연구)

  • Shim, Hyun-Min;Wang, Hong-Yue;Jung, Su-Yong;Kim, Hyung-Taek
    • 한국신재생에너지학회:학술대회논문집
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    • 2007.06a
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    • pp.788-791
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    • 2007
  • 기존의 미분탄 화력발전을 대체할 수 있는 차기 주자인 가스화복합발전(Integrated Gasification Combined Cycle) 기술은 단순히 열과 전기를 얻는데 그치지 않고 $CO_2$ 저감뿐만 아니라 다양한 형태의 2차 에너지원과 화학원료를 생산할 수 있는 기술이다. 상용화 운전 중인 기존의 IGCC 플랜트는 석탄 공급에 있어 건조된 미분탄(dry pulverized coal) 형태로 공급하는 건식 형태와 석탄슬러리(Coal water slurry)의 액상으로 공급하는 습식 형태로 대별되고 있다. 본 연구에서는 ASPEN plus를 이용하여 상용화 IGCC 플랜트에 대한 기본 모델을 구축하였으며, 산지별로 대상 탄종을 illinois #6(미국), Shenhua(중국), Drayton(호주)로 선정하여 가스화공정에 대한 성능을 해석하였다. 동일한 발전 출력을 얻고자 하였을 때, 석탄의 공급방식에 따라 필요한 석탄과 유틸리티 공급량과 가스화기 전${\cdot}$후단에서의 운전특성과 생성되는 합성가스(syngas) 조성, 냉가스(cold gas) 효율 및 탄소 전환율을 통해 각 case에 대한 플랜트 특성을 비교하였다.

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An Experimental Study on the Combustion Behavior of Single Coal-Water Slurry Droplet (석탄-물 혼합물 단일액적의 연소 특성에 관한 실험적 연구)

  • 채재우;조용철;전영남;한영수
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.16 no.11
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    • pp.2159-2168
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    • 1992
  • Coal-water slurry is considered to have the potential for displacing petroleum used in the existing oil-fired industrial and utility boilers. The combustion of coal-water slurry(CWS) is a complex process and little is known about the detailed mechanism. In this paper the combustion behavior of a single suspended droplet of CWS in hot gas stream was investigated. The effect of coal particle size, water content in droplet, initial droplet size, ambient temperature and oxygen fraction in ambient gas were studied. The results are as follows; (1) Increasing the oxygen fraction in ambient gas considerably reduced the char combustion time. (2) The variation of water content and coal particle size in droplet showed little effect on the combustion behavior. (3) In the relatively high temperature ambient gas, the water evaporation time became shorter and the combustion process was stable.

Removal of sulfur element from high-sulfur coal by superconducting HGMS technology

  • Han, Shuai-shuai;Li, Su-qin;Yang, Rui-ming;Yang, Chang-qiao;Xing, Yi
    • Progress in Superconductivity and Cryogenics
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    • v.21 no.2
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    • pp.26-30
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    • 2019
  • Coal is the most abundant fossil fuel on Earth and is used in a wide range of applications. The direct combustion of high-sulfur coal produces a large amount of sulfur dioxide, which is a toxic and corrosive gas. A new superconducting high gradient magnetic separation (HGMS) technology was studied to remove sulfur from high sulfur coal. The magnetic separation concentrate was obtained under the optimum parameters, such as a particle size of -200 mesh, a magnetic field strength of 2.0 T, a slurry concentration of 15 g/L, and a slurry flow rate of 600 ml/min. The removal rate of sulfur is up to 59.9%. The method uses a magnetic field to remove sulfur-containing magnetic material from a pulverized coal solution. It is simple process with, high efficiency, and is a new way.

Study on flow characteristics in entrained flow gasifier with high speed impinging jet (고속충돌노즐을 이용한 분류층 가스화기내의 유동특성에 관한 연구)

  • Lee, Hyo-Jin;Park, Tae-Jun;Lee, Jae-Gu;Kim, Jae-Ho;An, Dal-Hong
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.20 no.5
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    • pp.1735-1742
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    • 1996
  • An entrained flow gasifier simulating the cold mode was tested to estimate its performance for coal gasification and flow characteristics with a developed high speed impinging jet nozzle. The burner was designed for high temperature and high pressure(HTHP) conditions, especially for IGCC(Integrated Coal Gasification Combined Cycle). In order to get proper size of droplets for high viscous liquid such as coal slurry, atomization was achieved by impacting slurry with high speed (over 150m/sec) secondary gas (oxygen/or air)/ Formed water droplets were ranged between 100.mu.m to 20.mu.m in their sizes. The flow characteristics in the gasifier was well understood in mixing between fuel and oxidizer. Both external and internal recirculation zones were closely investigated through experimentation with visualization and numerical solutions from FLUENT CODE.