• Journal of Korean Society for Atmospheric Environment
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• v.26 no.2
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• pp.151-160
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• 2010

Particles emitted from three coal-fired power plants burning bituminous and sub-bituminous coals were examined for PM and size fractions PM>2.5 and PM2.5. The ratio of PM2.5/PM was ranged from 10 to 62%, and PM emission increased with the amount of coal feed, which was 7.23~15.66 kg/h. The emission range of PM2.5 from three power plants was 1.24~4.48 kg/h (dry), which was function of the mixed rate of viscous sub-bituminous coal in feed. Of course such effect should be examined by further tests in details. Based on the consumed coal and thermal load, the emission factors averaged were shown as 59.03 g-PM/ton-coal, 14.79 g-PM2.5/ton-coal and 22.51 g-PM/MWh, 5.54 g-PM2.5/MWh, respectively.

• 한국연소학회:학술대회논문집
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• 2015.12a
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• pp.93-96
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• 2015

Commercial coal gasifiers typically use entrained flow type reactors, but have unique features in terms of reactor shape, gasifying agent, coal feeding type, ash/slag discharge, and reaction stages. The MHI gasifier is characterized as air-blow dry-feed entrained reactor, which incorporates a short combustion stage at the bottom and a tall gasification stage above. This study investigates the flow and reaction characteristics inside a MHI gasifier by using computational fluid dynamics (CFD) in order to understand its design and operation features. For its pilot-scale system at 200 ton/day capacity, the distribution of coal and air supply between the two reaction stages was varied. It was found that the syngas composition and carbon conversion rate were not significantly influenced by the changes in the distribution of coal and air supply. However, the temperature, velocity and flow pattern changed sensitively to the changes in the distribution of coal and air supply. The results suggest that one key factor to determine the operational ranges of coal and air supply would be the temperature and flow pattern along the narrower wall between the two reaction stages.

• Resources Recycling
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• v.13 no.5
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• pp.51-56
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• 2004

Economic benefits of the dry bottom ash handling system over the wet bottom ash handling system in a new 500MW${\times}$2units pulverized coal thermal power plant in Korea were evaluated. The higher initial capital cost in the dry bottom ash handling system was estimated. However, this higher initial capital costs would be compensated with reductions of the operating cost mainly due to the recycling of bottom ash. Economic analysis showed that the payback period of 4.9 years and the internal rate of return at 21.1% were expected for the additional initial capital cost of the dry bottom ash handling system.

• The Korean Journal of Ecology
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• v.19 no.5
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• pp.365-373
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• 1996

A survey was carried out to investigate the contamination of streams by the acid mine drainage originated from the abandoned coal mines and coal refuse piles. The physico-KDICical characteristics such as pH, sulfate and elements concentrations in the water and sediment in streams were analyzed. Microbial activity in the sediment was evaluated by measuring dehydrogenase activities. At sites contaminated by acid mine drainage, the pH of the water and sediment declined to acidic range from neutral due to the accumulation of sulfate. The dehydrogenase activity ranged from 12 to $170{\mu}g-TPF{\cdot}g-dry\;soil^{-1}{\cdot}24h^{-1}$ at the contaminated sites, whereas uncontaminated sites had activities of 1,176~4,259 ${\mu}g-TPF{\cdot}g-dry\;soil^{-1}{\cdot}24h^{-1}$. The dehydrogenase activity was significantly affected by low pH of the sediment, indicating that high concentration of sulfate inhibited microbial activity. The concentrations of heavy metals such as Pb and Fe in contaminated sdeiment (37~46 ppm Pb; 46,000~464,000 ppm Fe) were much higher than those in the uncontaminated sediment. The concentration of Al in the contaminated water acidfied by coal mine drainage was in the range of 11 to 42 ppm. Compared with those in the uncontaminated sediment, the concentrations of Mn, Mg and Ca in contaminated sediment were low because of the leaching from soil to water by the acidfied stream water.

• Economic and Environmental Geology
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• v.31 no.6
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• pp.499-508
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• 1998

The Imgok Creek is located in the Gangreung coal field, which has been known that sulfides are more abundant than other coal fields in Korea, and it has been severly contaminated by acid mine drainage (AMD) discharging from the abandoned coal mines, such as the Youngdong, the Dongduk and the Waryong coal mines. The purposes of this study are to synthetically assess the contamination of natural water, stream sediment and cultivated soils, and to provide the basic data for AMD treatment. Geochemical samples were collected in December, 1996 (dry season) and April, 1997 (after three day's rainfall). TDS of the Youngdong mine water was remarkably higher than those of other mine waters. In the Imgok Creek, concentrations of most elements, except Fe decreased with distance by dilution caused by the inflow of uncontaminated tributaries. From the results of NAMDI and $I_{geo}$ calculation, the Youngdong coal mine was the main contamination source of the study area. Groundwater pollution was not yet confirmed in this study and the paddy and farm land soils were also not yet contaminated by mining activity based on the pollution index ranging from 0.27 to 0.47.

• Journal of the Korean Society of Tobacco Science
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• v.19 no.2
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• pp.92-101
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• 1997

This study was conducted to investigate the effect of fly ash on the yield and quality and to determine the optimum application amount of fly ash for tobacco(Nicotiana tabacum L). Two kinds of fly ash, anthracite and bituminous coal, were treated with different levels of 0, 20, 40, 60 MT/ha. Dry weights of tobacco at middle and topping growth stage were increased with application of fly ash, showing the highest dry weight at 40 MT/ha in both kinds of fly ash. It was showed that the bituminous coal had a little more effective for yield than that of anthracite. Comparing with the control, yields of tobacco applied with fly ash were significantly increased about 17.7% and 17.1% by the application of bituminous coal and anthracite, respectively. Quality of flue-cured leaves was better by application of fly ash than that of the control. The quality index was given the highest at 40 MT/ha for bituminous coal increasing by 24.6% and at 60 MT/ha fur anthracite increasing by 13.4% compared with the control. The economical efficiency considered of the yield and quality of tobacco was the highest at 40 MT/ha of bituminous. Soil pH, contents of available P2O5, organic matter, exchangeable Ca2+ and Mg2+ of soil during the growing season were increased by application of fly ash, showing more effectiveness in bituminous than that in anthracite. By the application of fly ash, the nutrients availability and the acidity of soil were reformed and they caused significantly the increase of growths yield, and quality of tobacco. By the application of lime reforming soil acidity, growth response, yields and quality of tobacco were not increased compared to the control, although the effect of reforming soil pH was remarkable.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.852-855
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• 2009

고압 미분탄 공급 기술은 건식 석탄가스화기 시스템의 안정적인 연속운전을 위한 핵심이 되는 기술로서, 본 연구에서는 스크류피더 방식 및 기류수송 방식의 pilot급 고압 미분탄 공급장치를 이용한 미분탄 공급량 제어 기술 개발을 진행하였다. 그리고, 일반적으로 dense phase 형태로 다량의 미분탄을 공급하는 기류수송 방식 고압 미분탄 공급장치에서 가스화기로 공급되는 미분탄의 공급량을 감소시키기 위하여 다공 chamber를 통하여 가압 질소를 공급할 경우, 차압이 증가함에 따라 미분탄의 공급량이 증가하기는 하지만 lean 또는 medium phase 형태로 미분탄 공급량 제어가 가능함을 확인할 수 있었다.

• Journal of Mechanical Science and Technology
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• v.15 no.6
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• pp.804-812
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• 2001

A triboelectrostatic separation system for removing unburned carbon from coal fly ash is designed and evaluated. Fly ash from a coal-fired power plant is used as an accepted additive in concrete where it adds strength, sulfate resistance and reduced cost, provided acceptable levels of unburned carbon are maintained. Unfortunately, unburned carbon in coal fly ash absorbs some of other additives and reduces the concrete strength. This paper describes to investigate dry triboelectrostatic process to separate unburned carbon from coal fly ash and utilize it into economically valuable products. The laboratory-scale triboelectrostatic separation system consists of a particle feeding system, a tribocharger, a separation chamber, and collection systems. Particles of unburned carbon and fly ash can be imparted positive and negative surface charges, respectively, with a copper tribocharger due to differences in the work function values of the particles and the tribocharger, and can be separated by passing them through an external electric field. Results showed that fly ash recovery was strongly dependent on the electric field strength and the particle size. 70wt% of fly ash containing 6.5wt% of carbon contents could be recovered at carbon contents below 3%. The triboelectrostatic separation system showed a potential to be an effective method for removing unburned carbon from coal fly ash.

• Transactions of the Korean hydrogen and new energy society
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• v.20 no.4
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• pp.352-359
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• 2009

KEPRI is developing a Korean type coal-gasification system and the scale is 20 ton/day. Prior to this pilot plant, a 1 ton/day class gasification system will be used for pre-testing of several coal types. This paper introduces the configuration and design conditions of this 1 ton/day class system, presenting the gas/coal ratio, oxygen/coal ratio, cold gas efficiency, CFD analysis of gasifier, and others. The existing combustion furnace for residual oil was retrofitted as a coal gasifier and a vertical and down-flow type burner was manufactured. Ash removal is carried out through a water quencher and a scrubber following the quencher, and the sulfur is removed by adsorption in the activated carbon tower. The gas produced from the gasifier is burned at the flare stack. In this paper, the results of design conditions and initial operation conditions of I ton/day gasification system are compared together.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.3 no.2
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• pp.185-201
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• 1993

The objectives of this study are to identify the physical, chemical and microstructural properties of coal fly ash and to increase the industrial use of coal fly ash. Experimental results show that 3 major constituents of coal fly ash are $SiO_2$, $Al_2O_3$ and coal fly ash includes the crystalline of Quartz and Mullite. Coal fly ash are classified into 7 groups based on the type of microstructure. Cenosphere is divided into floater and dry separated cenosphere which are consist mainly of $SiO_2$ and $Al_2O_3$. Cenosphere segregations are formed by adsorption and neck growth of the smaller sized cenosphere particles on the condition of the high temperature and air pressure.