• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.3
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• pp.207-213
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• 2018

Nowadays, circulating fluidized bed combustor(CFBC) boilers system that can reduce environmental pollution particles are widely used in electric power plants. But the fly ash generated from CFBC boilers has lower $SiO_2$ and higher MgO and $SO_3$ contents and also has free CaO inducing expansion and abrupt initial setting of concrete. Therefore, revised KSL5405 for CFBC fly-ash as well as pulverized coal combustion(PCC) is introduced in the concrete field. In this study, the chemical properties and mechanical properties of blended cements with PCC and CFBC fly-ash produced in Korea are analyzed. The blended cement with only CFBC fly ash shows a lower length change than OPC but a higher flow change ratio. The compressive strength of blended cement paste with PCC and CFBC fly ash is slightly greater than that of cement paste with only PCC fly-ash. Based on the results, CFBC flyash blended cement products should be used with PCC flyash to ensure the material stability and material properties.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.12 no.4
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• pp.315-327
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• 2007

This study investigated temporal and spatial variation of Pb and stable Pb isotopes accumulated in Ulleung Basin core sediments (4) using MC ICP/MS in order to identify the sources of anthropogenic Pb in the East/Japan Sea. Leached (1M HCl) Pb concentration and isotope ratios ($^{207}Pb/^{206}Pb\;and\;^{208}Pb/^{206}Pb$) were nearly constant during 300 yrs past than 1930, but increased up to twice in concentration and as much as 3.41% (1.70%) after 2000. On the other hand, residual Pb concentrations were nearly constant for past 400 yrs. The accumulation rates of anthropogenic Pb in the basin area were in the range of $3.1-3.5mg/m^2/yr$, which were similar levels to total atmospheric Pb deposition fluxes from 1990s to the present. In the slope area, more increase of anthropogenic Pb accumulation than the levels expected from mass accumulation rate could be found after the middle of 1990s. From the detailed evaluation for the temporal and spatial variation of accumulation rate and isotope ratios of anthropogenic Pb, we proposed probable sources and pathways of anthropogenic Pb. Pb emmision by coal burning from the China and Korea initiated the accumulation of anthropogenic Pb in the sediments of East/Japan Sea from 1930s. The accumulation of Pb increased by the addition of anti-nocking agents from both countries untill the beginning of 1990s, but from the middle of 1990s to the present, the phase-out of gasoline additives and the rapid increase of coal burning from the China maintained the atmospheric Pb levels in the Ulleung basin nearly similar to before. However, the local sources within this basin might take an important role in the rapid increase of anthropogenic Pb accumulation in slope areas from the middle of 1990s.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.206.2-206.2
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• 2010

현재 RPF 생산공정에서 생산된 RPF는 약 7,500~8,500kcal/kg 의 높은 열량을 지니고 있다. 이러한 특성으로 연소시 소각로 내부의 온도가 부분적으로 급격히 상승하여 적정온도조절이 어렵고, 로내 장치들의 내구성이 저하되는 등 문제가 발생하고 있다. 또한, RPF에 포함된 비교적 높은 농도의 염소 함량(0.8~1.8% wt)으로 인해 다량의 대기오염물질이 발생되는 단점이 나타나고 있다. 따라서, 이러한 문제점들을 개선하기 위해 RPF의 개질이 필요하며 본 연구에서는 슬러지와 RPF를 혼합하여 열량, 성형성, 염소함량등을 고려하여 최적의 혼합비율을 선정하였다. J하수처리장에서 발생하는 하수슬러지를 이용하여 5, 15, 25, 30, 35%를 RPF 성형공정에 혼합하여 실험하였다. 5% 혼합시 발열량은 약 6,300~6,800kcal/kg, 염소농도는 0.8~1.6%(wt), 15% 혼합시 발열량은 5,500~6,000kcal/kg, 염소농도는 0.7~1.4%(wt), 25% 혼합시 발열량은 5,200~5,900kcal/kg, 염소농도는 0.6~1.1%(wt), 30% 혼합시 발열량은 5,000~5,700kcal/kg, 염소농도는 0.6~1.0%(wt), 35% 혼합시 발열량은 4,800~5,200kcal/kg, 염소농도는 0.4~0.6%(wt)으로 나타났다. 각 혼합비율에서 관찰된 성형성은 5~25% 혼합까지는 성형된 RPF와 유사하게 일정한 크기 및 강도를 유지 할 수 있었으나, 25% 이상 혼합시 분말형태의 가루가 많이 발생되며 강도가 약해져 쉽게 부스러지는 문제점등이 나타났다. 연료의 개질 형태나 성형성등을 고려하였을 때 슬러지 혼합비율이 약 15~25% 정도가 최적 혼합비율인 것으로 나타났다.

• Fire Science and Engineering
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• v.34 no.2
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• pp.7-13
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• 2020

In this study, water glass was applied as a coating material to a rigid polyurethane foam to improve the flame-retardant properties of the foam. The heat release rate of the cone calorimeter of the urethane foam, in which the inorganic water-glass coating layer was applied, decreased rapidly. The water glass coated on the polyurethane surface formed a glassy foam by foaming with water, which did not escape during the vitrification reaction when the foam or glass was heated. The glassy foam formed on the polyurethane foam became a fire-resistant insulation layer that inhibited the combustion of the polyurethane foam for more than 10 min. Water glass was found to improve the flame-retardant properties of the rigid polyurethane foam.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.7
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• pp.2267-2276
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• 1996

Twin-fluid atomization has been widely used in combustors and process industries because of its high performance and simple structure. Flow visualization and pressure measurements were conducted to investigate the effects of gas flow in twin-fluid atomization. Schlieren photographs showed that changes in atomizing gas pressure, altered the wave patterns, and the lengths of both recitrculating toroid (impinging stangnation point) nad supersonic flow region in the jet. A longer supersonic wave pattern like net-shape wqas observed as atomizing gas pressure increased. The disintegration phenomenon of liquid delivery tube. The variation of spray angles with gas pressures were obtained by visualization using laser sheet beam. Suction pressuresat the nozzle orifice exit and recirculating region are shown to be used to estimate the stable atomization condition of a twin-fluid atomizer.

• Korean Chemical Engineering Research
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• v.56 no.3
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• pp.349-355
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• 2018

$BaMnAl_{11}O_{19}$ was prepared by urea-induced homogeneous precipitation and characterized by X-ray diffraction and scanning electron microscopy. At increased precipitant concentrations, AlOOH replaced $Al(OH)_3$ as an Al precursor. $BaMnAl_{11}O_{19}$ exhibited enhanced catalytic combustion performance and inhibited CO generation. Catalytic performance was also enhanced by the presence of $BaAl_2O_4$ and $BaMnAl_{11}O_{19}$. Compared to $BaAl_2O_4$, $BaMnAl_{11}O_{19}$ exhibited superior catalytic combustion activity.

• Journal of Energy Engineering
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• v.2 no.2
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• pp.208-214
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• 1993

Pyrolysis of bituminous coal has been carried out in a two-stage fixed bed reactor to produce high heating value gas(7000 kcal/N㎥) for industrial or town gas usage. The effects of coke catalyst, pyrolysis temperature (468∼565$^{\circ}C$), and catalytic cracking temperature (700∼850$^{\circ}C$) on the product gas properties from pyrolysis of bituminous coal have been determined. From pyrolysis of Dong Jin coal with coke, the carbon deposition on catalyst is found to be less than 5% of product tar and approximately 15% of total energy iii the parent coal can be recovered as high heating value gas. Oil composition in the product tar from the two-stage pyrolysis is higher than that from low-temperature pyrolysis. The tar produced from pyrolysis below 516$^{\circ}C$ can be easily catalytically cracked but, the tar produced above 565$^{\circ}C$ cannot be cracked easily with catalyst. From the product gas analysis, the catalytic cracking temperature should be maintained below 800$^{\circ}C$ since cracking speed of ethylene increases remarkably with the cracking temperature above 800$^{\circ}C$.

• Fire Science and Engineering
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• v.26 no.2
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• pp.90-96
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• 2012

Since vertical flame spread speed on exterior materials is much faster than horizontal fire, analysis of its fire characteristic is required. For the study of vertical fire pattern created by penetrating windows or openings from the exterior wall of buildings, the research is based on the fire simulation for an aluminum-complex-panel with which is commonly used as exterior materials and consists of polyethylene core material. As a result, the flame reaches the 2nd floor after 135 seconds in the early stage of fire, the 10the floor after 470 seconds and the 30th floor, the highest floor, after 711 seconds. The result shows that fire spread abruptly expands on upper floor due to stack effect of a turbulent flow or exterior materials. In consequence, we can confirm a serious problem that a conflagration of a building through an opening that is equipped with the exterior-materials spreads into interior of building at that same time.

• Journal of the Korean Institute of Gas
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• v.11 no.4
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• pp.17-22
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• 2007

The NOx emission characteristics with oxygen enrichment in non-premixed counterflow flames were investigated numerically. To consider systematically the situation of inevitable $N_2$ contamination by air infiltration in the process of pure-oxygen combustion, the volume ratio of $O_2$ in an oxidizer was changed from 21% to 100%. As a result the NO emission index $(EI_{NO})$ has the highest value under condition of 75% oxygen enrichment. This result can be explained by the change of $N_2$ destruction rate with oxygen enrichment rather than flame temperature, flame thickness and residence time. In particular, it was found that the reaction of N+NO=$N_2+O$ has the largest contribution on NOx production in oxygen-enrichment flames.

• Journal of the Korean Institute of Gas
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• v.19 no.5
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• pp.36-40
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• 2015

To evaluate the safety of propane cylinder, the flame test was performed by the flame exposure scenario of propane cylinder. The cylinder which was exposed in a flame was rapidly occurred to increase the internal pressure by liquid expansion, if so it cause of physical explosion. Therefore, the cylinder which was applied with thermal pressure relief device sholud be not bursted and the propane should be discharged to outside safely. The flame average temperature that was around of cylinder is $600^{\circ}C$, and then it increased $700^{\circ}C$ by discharged propane. The result of flame test, the cylinder was deformed, but it was not bursted. The regulations of flame exposure test for propane cylinder were not restricted, this paper can be applied to restrict the flame test if the cylinder is possible to expose the flame. Also, the results is expected as reference for estimation of the pressure cylinder performance.