• Journal of ILASS-Korea
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• v.19 no.3
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• pp.136-141
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• 2014

This study reports numerically the characteristics of dust scattering around the coal storage pile yards, substantially affected by the windbreak wall height. The dust scattering is closely associated with the frictional effect of wind flows as well as the pressure variation that consequently affect the dust particle behavior. In the present study, with the use of the commercial code of FLUENT, the distribution of wind velocity and pressure are predicted around coal storage pile yard for four different heights of the wind break wall. From the results, it was found that for the case 1 with the outer windbreak wall height of 3 m and inner windbreak wall height of 6 m, the amount of scattering dust for a year was estimated to be 1451 kg, whereas for the case 4 where a height of outer windbreak wall is 10 m and a height of inner windbreak wall is 16 m, the amount of scattering dust for a year was 358 kg. It shows that the dust scattering can be reduced by 75%, indicating important role of windbreak wall height on particle scattering. The numerical results would be useful in decision of the appropriate height of windbreak wall for decreasing the amount of scattering dust under various environmental conditions.

• Korean Journal of Soil Science and Fertilizer
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• v.47 no.6
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• pp.525-532
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• 2014

Since mine wastes were merely dumped in the mine waste dump, they have produced acid mine drainage (AMD). Therefore, main objective of this study was to evaluate the effect of coal combustion products (CCPs) on heavy metal stabilization and detoxification for mine wastes. Total six treatments for incubation test were conducted depending on mixing method (completely mixing and layered). Also, lysimeter experiment was conducted to examine efficiency of polyacrylamide (PAM) on reduction of mine wastes erosion. Result of incubation test showed that concentrations of soluble aluminium (Al) and iron (Fe) in leachate decreased compared to control. The lowest soluble Al and Fe in leachate was observed in 50% mixed treatment (14.2 and $1.03mg\;kg^{-1}$ for Al and Fe respectively) compared to control treatment (253.0 for Al and $52.6mg\;kg^{-1}$ for Fe). The pH of mine wastes (MW) and leachate increased compared to control after mixing with CCPs and ordered as control (MW 6.4, leachate 6.3) < 10% (MW 7.7, leachate 7.1) < 20% (MW 9.0, leachate 7.8) < 30% (MW 9.5, leachate 8.3) < 40% (MW 9.9, leachate 8.5) < 50% (MW 10.5, leachate 8.6). Application of PAM, both in liquid and granular type, dramatically decreased the suspended solid (SS) concentration of CCPs treatments. Reduction of SS loss was ordered as MW70CR30L ($24.4mg\;L^{-1}$) > MW70CR30LPL ($6.7mg\;L^{-1}$) > NT ($3.1mg\;L^{-1}$) > MW70CR30M ($1.6mg\;L^{-1}$) > MW70CR30MPL ($1.1mg\;L^{-1}$) > MW70CR30PGM ($0.7mg\;L^{-1}$) > MW70CR30LPG ($0.5mg\;L^{-1}$) > MW70CR30MPG ($0.4mg\;L^{-1}$). Overall, application of CCPs can be environmental friendly and cost-effective way to remediate coal mine wastes contaminated with heavy metals. In addition, use of PAM could help to prevent the erosion coal mine wastes in mine waste disposal area.

• Plant Journal
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• v.14 no.4
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• pp.39-47
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• 2018

In this research, when the output of the standard coal-fired thermal power plant operating continuously at the rated output of 500 MW is changed to operate at 300 to 500 MW, the amount of sulfur oxide produced and the amount of sulfur oxide in the absorption tower of desulfurization equipment and proposed an extra liquid to gas ratio improvement inversely proportional to the output. In order to calibrate the combustion efficiency at low power, the ratio of sulfur oxides relative to the amount of combustion gas is increased as the excess air ratio is increased. When the concentration of sulfur oxide at the inlet of the desulfurization absorber was changed from 300 to 500 ppm along with the output fluctuation. The liquid to gas ratio of limestone slurry and combustion gas was changed from 10.99 to 16.27. Therefore, if the concentration of sulfur oxides with output of 300 MW is x, The following correlation equation is recommended for the minimum required flow rate of slurry for the reduction of surplus energy due to the increase of the liquid weight at low load. $y1[m^3/sec]=0.11x+3.74$

• Journal of Korean Society for Atmospheric Environment
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• v.2 no.2
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• pp.9-18
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• 1986

For identification and apportionment of sources emitting particulate matters in environment, the multi-elemental characterization of size-density fractionated particulate matters was carried out. Eight types of samples were tested; soil, flyash released from burning of bunker-Coil, diesel oil, coal, and soft coal, urban road-way dust, urban dust fall, and airborne particulate matter. The fractions of particulate matters obtained by heavy liquid separation methos with a series of dichloromethane-bromoform were then analyzed using atomic absorption spectrophotometry for Ni, Cr, Cu, An, Fe, Al, and Mg. Each sample showed a different concentration profile as a function of density, and a number of useful conclusions concerning characterization of elemental distribution were obtained. From the density distributions of elements in soil, the maximum value was found for all elements in the density range of 2.2 $\sim 2.9g.cm^{-3}$, including the density of $SiO_2$. However, the distribution of metallic compounds with the density lower than $2.2g.cm^{-3}$ was prevalent in urban roadway dust, urban dust fall, and airborne particulate matter. And the density distribution curves of these urban dusts also have the higher distribution at the density of 2.2 - 2.9g.cm^{-3}$, including the density of wind-blown silica. This tendency generally was prevalent in the natural source elements, such as Al, Fe, Mn, and Mg. The maximum values were found in the density ranges of 1.3 $\sim 2.2g.cm^{-3}$ from the density distribution of elements in oil fired flyash. These distributions of anthropogenic source elements, such as Zn, Ni, Cu, and Cr were higher predominately than those of natural source elements. And the higher distribution was found in the density range of $2.2 \sim 2.9g.cm^{-3}$ from the density distribution of elements in coal and soft-coal fired flyash. These distributions showed similar patterns to soil. But anthropogenic source elements somewhat predominated at the density ranges of $1.3 \sim 2.2g.cm{-3} and 2.9g.cm^{-3}$ to soil. Therefore the higher distribution of anthropogenic source elements in the density ranges of $1.3 \sim 2.2g.cm^{-3} and 2.9g.cm^{-3}$ was considered as anthropogenic origin.

• Journal of Environmental Science International
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• v.28 no.6
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• pp.561-570
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• 2019

A zeolitic material (Z-Y2) was synthesized from Coal Fly Ash (CFA) using a fusion/hydrothermal method under low-alkali condition (NaOH/CFA = 0.6). The adsorption performance of the prepared zeolite was evaluated by monitoring its removal efficiencies for Sr and Cs ions, which are well-known as significant radionuclides in liquid radioactive waste. The XRD (X-ray diffraction) patterns of the synthesized Z-Y2 indicated that a Na-A type zeolite was formed from raw coal fly ash. The SEM (scanning electron microscope) images also showed that a cubic crystal structure of size $1{\sim}3{\mu}m$ was formed on its surface. In the adsorption kinetic analysis, the adsorption of Sr and Cs ions on Z-Y2 fitted the pseudo-second-order kinetic model well, instead of the pseudo-first-order kinetic model. The second-order kinetic rate constant ($k_2$) was determined to be $0.0614g/mmol{\cdot}min$ for Sr and $1.8172g/mmol{\cdot}min$ for Cs. The adsorption equilibria of Sr and Cs ions on Z-Y2 were fitted successfully by Langmuir model. The maximum adsorption capacity ($q_m$) of Sr and Cs was calculated as 1.6846 mmol/g and 1.2055 mmol/g, respectively. The maximum desorption capacity ($q_{dm}$) of the Na ions estimated via the Langmuir desorption model was 2.4196 mmol/g for Sr and 2.1870 mmol/g for Cs. The molar ratio of the desorption/adsorption capacity ($q_{dm}/q_m$) was determined to be 1.44 for Na/Sr and 1.81 for Na/Cs, indicating that the amounts of desorbed Na ions and adsorbed Sr and Cs ions did not yield an equimolar ratio when using Z-Y2.

• Korean Chemical Engineering Research
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• v.47 no.5
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• pp.580-586
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• 2009

In this study, co-combustion characteristics of Chinese bituminous coal and North Korean anthracite were investigated using a 2 MWe scale circulating fluidized bed power plant. At first, the combustion efficiency of bituminous coal of China and Australia as a function of excess air ratio and temperature were observed. The results showed that the combustion efficiency was influenced by particle size and volatile content of coal, the combustion efficiency of Chinese bituminous coal was over 99.5%. The unburned carbon particles from fly ash and bottom ash were a content 5~7% and 0.3%, respectively. The combustion efficiency with the mixture ratio 20% of bituminous coal and anthracite decreased over 5% because of the increase of entrained particles by a small average particle size of anthracite in the combustor. However, the outlet concentration of $SO_2$ and $NO_x$ was not changed remarkably. The concentrations of the typical air pollutants such as $NO_x$ and $SO_2$ were 200~250 ppm($O_2$ 6%), 100~320 ppm($O_2$ 6%) respectively. The outlet concentration of $NO_x$ was decreased to 30~65% with $NH_3$ supplying rate of 2~13 l/min in SCR process. The $SO_x$ removal efficiency was up to 70% by in-furnace desulfurization using limestone with Ca/S molar of approximately 6.5. With wet scrubbing using $Mg(OH)_2$ as absorbent, the $SO_x$ removal efficiency reached 100% under near pH 5.0 of scrubbing liquid.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.9
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• pp.863-871
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• 2004

The use of fossil fuels like coal, oil and natural gases around the world causes an increase of the carbon dioxide content in the atmosphere. In order to reduce the concentration of the greenhouse gas, the idea of carbon dioxide sequestration in the ocean is proposed to be an effective mitigation strategy to counteract potential global warming due to the greenhouse effect. Therefore, in the present study, calculations of the dissolution behavior of carbon dioxide when liquid carbon dioxide is released at 1,000m and 1,500m in depth by fixed pipeline are performed. The results show that carbon dioxide droplets change to carbon dioxide bubbles in gas phase around 500m in depth, and the droplets are completely dissolved below 500 m in depth if the liquide carbon dioxide is released both at 1,000 m in depth with the initial diameter of 0.007m or less and at 1,500m in depth with the diameter of 0.011m or less.

• Journal of Advanced Marine Engineering and Technology
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• v.18 no.4
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• pp.33-42
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• 1994

The radiative heat transfer analysis in the fluidized particles layer has important application in many technological areas such as combustion chambers at high pressure and temperature, plasma generators for nuclear fusion, MHD generator using pulverized coal and the liquid droplet radiator used to reject wasted heat from a power plant operating in space. To accurately model the radiation properties of the fluidized particles layer, it is necessary to know the radiation interchange factors of particles in each layer. But the solutions are usually not possible for the equations of radiative heat transfer because it has an inherent difficulty in treating the governing intergo- differential equations, which are derived from the remote effects of radiative heat transfer. In this study, the analysis uses the Monte Carlo simulation method with optical depth model to calculate the radiation interchange factors of particles in each layer with wall and with each other.

• Bulletin of the Korean Chemical Society
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• v.35 no.6
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• pp.1613-1618
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• 2014

Perovskite-type oxides are promising oxygen carriers in producing oxygen-enriched $CO_2$ gas stream for oxyfuel combustion. In this study, a new series of $SrCo_{1-x}Fe_xO_{3-{\delta}}$ (x = 0.2, 0.4, 0.6, 0.8) was prepared and used to produce $O_2/CO_2$ mixture gas. The phase, crystal structure, and morphological properties of $SrCo_{1-x}Fe_xO_{3-{\delta}}$ were investigated through X-ray diffraction, specific surface area measurements, and environmental scanning electron microscopy. The oxygen desorption performance of $SrCo_{1-x}Fe_xO_{3-{\delta}}$ was studied in a fixed-bed reactor system. Results showed that the different x values of $SrCo_{1-x}Fe_xO_{3-{\delta}}$ have no obvious effects on crystalline structure. However, the oxygen desorption performance of $SrCo_{1-x}Fe_xO_{3-{\delta}}$ is improved by Co doping. Moreover, $SrCo_{0.8}Fe_{0.2}O_{3-{\delta}}$ synthesized via a new EDTA method has a larger BET surface area ($40.396m^2/g$), smaller particle size (48.3 nm), and better oxygen production performance compared with that synthesized through a liquid citrate method.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.71.1-71.1
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• 2011

석석탄가스화 기술은 고온, 고압 조건에서 미분탄과 산소의 가스화 반응에 의해 CO와 $H_2$가 주성분인 합성가스를 제조하는 기술로서 차세대 화력발전 뿐만아니라 다양한 화학원료 제조를 위한 분야에서 각광을 받고 있다. 또한, 가스화 기술은 향후 CCS기술, CTL(Coal To Liquid, 석탄액화)기술, SNG(Synthetic Natural Gas, 합성천연가스)생산, 수소생산, 각종 화학원료 생산 등과 연계가 가능한 미래 석탄이용 분야의 핵심 기술이라 할 수 있다. 따라서, 고등기술연구원에서는 이러한 석탄가스화를 통해 양질의 합성가스를 제조하기 위한 기술 개발의 일환으로 pilot급 고온, 고압 건식 분류층 가스화기, 기류수송 방식의 미분탄공급장치, 수냉자켓 구조의 합성가스 냉각장치, 합성가스 중 분진제거를 위한 금속필터 장착 집진장치 등을 연계하여 20기압의 고압 조건에서 장시간 연속운전을 진행하였다. 본 연구에서는 미분탄 공급을 위하여 상부공급 버너를 적용하였고 석탄가스화기는 $1,300{\sim}1,350^{\circ}C$ 정도의 온도에서 운전을 진행하였으며 미분탄을 75 kg/h의 조건에서 연속적으로 공급하였다. 그리고, 이러한 조건에서 5.5일 정도의 연속운전을 진행하는 동안 CO 44~48%, $H_2$ 20~21%, $CO_2$ 4~5% 조성의 석탄 합성가스를 $200Nm^3/h$ 안정적으로 제조할 수 있었다.