• Journal of the Korean Society of Combustion
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• v.18 no.1
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• pp.21-26
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• 2013

In the Shell coal gasification process, the syngas produced in a gasifier passes through a syngas cooler for steam production and temperature control for gas cleaning. Fly slag present in the syngas may cause major operational problems such as erosion, slagging, and corrosion, especially in the upper part of the syngas cooler (gas reversal chamber, GRC). This study investigates the flow, heat transfer and particle behaviors in the GRC for a 300 MWe IGCC process using computational fluid dynamics. Three operational loads of 100%, 75% and 50% were considered. The gas and particle flows directly impinged on the wall opposite to the syngas inlet, which may lead to erosion of the membrane wall. The heat transfer to the wall was mainly by convection which was larger on the side wall at the inlet level due to the expansion of the cross-section. In the evaporator below the GRC, the particles were concentrated more on the outer channels, which needs to be considered for alleviation of fouling and blockage.

• Magazine of the Korean Society of Agricultural Engineers
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• v.45 no.2
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• pp.107-115
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• 2003

Dairy manure amended with crop and forest residues (moisture 69% wet basis, C/N 22) was composted in a 605 L pilot-scale vessel using continuous air flow (56 L/min) for 19 days. Three pilot-scale sawdust biofilters (moisture 63%, pH 5.0) were built to clean biological waste gas from the composting process. For each methods, two replicated experiments were monitored over a period of three weeks. The system was evaluated to determine the biofilter media depth that would be adequate for compost odour reduction. The compost air cleaning was measured based on ammonia gas concentration before and after passing through the biofilter. Ammonia gas removal efficiency over 3 weeks was 42, 75 and 87% at sawdust biofilter media depth levels of 202, 400 and 600 mm, respectively. Each sawdust biofilter was operated at a moisture content in the range of 60~62% (wb), a temperature from 15 to $25^{\circ}C$, an average pressure drop from 240 to 340 Pa and a detention time from 60 to 180 seconds during the biofiltration process.

• Journal of the Korean Institute of Gas
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• v.24 no.3
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• pp.33-39
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• 2020

In general, in a batch reaction process in which products are made using flammable liquids, splash filling is used to clean the walls of the reactor by spraying flammable liquids, which are raw materials used for product, during cleaning of the reactor after work. During this process, mist of flammable liquid is generated, the lower limit of explosion is lowered, and fire·explosion may occur due to discharges caused by various types of complex charges, such as flow charge, collision charge, and ejection charge. Therefore, based on the recent accident case, to identify the risk when working in the form of splash filling with toluene in a batch process and perform an explosion impact analysis using the TNT equivalent method After that, we will analyze the accident results and suggest preventive measures such as constant purge system, improvement of cleaning method, and use of tantalum to prevent such accident.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.10
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• pp.957-964
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• 2010

The deactivated catalyzed diesel particulate filter-trap (DPF) was remanufactured by ultrasonic wave treatment with various prepared solutions, followed by active component re-impregnation, and the emission control performance and surface properties of remanufactured DPF were studied at various remanufacturing conditions. The proper ultrasonic wave cleaning time at various prepared solutions and optimal re-impregnation amounts of active component for the best emission control performance of DPF were investigated and its performance tests were also carried out with various temperatures for the conversions of CO, THC (total hydrocarbon) and PM (particulate matter) by catalytic reaction test unit using bypass gas from the diesel engine dynamo system. It was found that the emission control performance of DPF remanufactured with the high-temperature air washing, ultrasonic wave cleaning at acid/base solutions and active component re-impregnation method was recovered to 95% level of its activity compared to that of the fresh DPF, which was caused by removing the deactivating materials from the surface of the DPF, through the analyses of performance test and their surface characterization by Optical microscope, EDX, ICP, TGA, and porosimeter.

• Korean Journal of Materials Research
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• v.18 no.2
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• pp.73-76
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• 2008

[ $SF_6$ ] gas has been widely used as an insulating, cleaning and covering gas due to its outstanding insulating feature and because of its inert properties. However, the global warming potential of $SF_6$ gas is extremely high relative to typical global warming gases such as $CO_2$, CFCs, and $CH_4$. For these reasons, it is necessary to separate and collect waste $SF_6$ gas. In this study, the effects of a surfactant (Tween) on the formation rate of $SF_6$ gas hydrates were investigated. The $SF_6$ gas hydrate formation rate increased with the addition of Tween and showed a nearly 6.5 times faster hydrate formation rate with an addition of 0.2 wt.% Tween compared to an addition of pure water. This is believed to be due to the increased solubility of $SF_6$ gas with the addition of the surfactant. It was also found that $SF_6$ gas hydrate in the surfactant solution showed two-stage hydrate formation rates with a formation rate that increased rapidly in the 2nd stage.

• Clean Technology
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• v.18 no.4
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• pp.419-425
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• 2012

This work explored the characteristics and the photocatalytic activities of S element-doped $TiO_2$ (S-$TiO_2$) and N element-doped $TiO_2$ (N-$TiO_2$) for the decomposition of gas-phase isopropyl alcohol (IPA) at sub-ppm concentrations, using a plug-flow reactor irradiated by 8-W daylight lamp or visible light-emitting-diodes (LEDs). In addition, the generation yield of acetone during photocatalytic processes for IPA at sub-ppm levels was examined. The surface characteristics of prepared S- and N-$TiO_2$ photocatalysts were analyzed to indicate that they could be effectively activated by visible-light irradiation. Regarding both types of photocatalysts, the cleaning efficiency of IPA increased as the air flow rate (AFR) was decreased. The average cleaning efficiency determined via the S-$TiO_2$ system for the AFR of 2.0 L $min^{-1}$ was 39%, whereas it was close to 100% for the AFR of 0.1 L $min^{-1}$. Regarding the N-$TiO_2$ system, the average cleaning efficiency for the AFR of 2.0 L $min^{-1}$ was above 90%, whereas it was still close to 100% for the AFR of 0.1 L $min^{-1}$. In contrast to the cleaning efficiencies of IPA, both types of photocatalysts revealed a decreasing trend in the generation yields of acetone with decreasing the AFR. Consequently, the N-$TiO_2$ system was preferred for cleaning of sub-ppm IPA to S-$TiO_2$ system and should be operated under low AFR conditions to minimize the acetone generation. In addition, 8-W daylight lamp exhibited higher cleaning efficiency of IPA than for visible LEDs.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2006.05a
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• pp.170-175
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• 2006

• Proceedings of the KAIS Fall Conference
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• 2001.05a
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• pp.79-81
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• 2001

저압 기상 영역에서 Anhydrous HF 가스와 Methanol vapor를 사용하는 산화막 식각공정을 수행하기 위하여 (1) 반응기 부피의 최소화, (B) 공정압력의 최소화, (3) 고순도 알루미나 Reactor 적용, (4) Cluster화의 개념을 적용한 VPC 장치를 제작하였다. Wafer의 온도, HF의 분압 및 Working Pressure 등의 공정변수에 따른 Oxide Wafer의 식각특성의 변화를 확인하였다. 또한 Etch Uniformity를 향상시키기 위하여 Shower Head 구조를 변경시켜서 실험하였으며, CFD Simulation을 이용하여 Reactor내에서의 HF gas 및 Methanol vapor의 분율을 예측하였다.

• Nuclear Engineering and Technology
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• v.51 no.2
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• pp.641-645
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• 2019

Experimental equipment for studying the sorption properties of iodine sorbents using radioactive methyliodide has been developed. The sorption capacity index ${\alpha}$ is proposed as a criterion parameter for assessing the quality of impregnated activated charcoals. It was found that this parameter does not depend on the dynamic conditions during the sorbent test. It was shown that values of the sorption capacity index allow to recommend iodine sorbents for industrial gas cleaning processes.

• Journal of Energy Engineering
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• v.12 no.1
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• pp.1-10
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• 2003

Pressurized fluidized bed combustion unit is operated at pressures of 1~1.5 MPa with combustion temperatures of 850~87$0^{\circ}C$. The pressurized coal combustion system heats steam, in conventional heat transfer tubing, and produces a hot gas supplied to a gas turbine. Gas cleaning is a vital aspect of the system, as is the ability of the turbine to cope with some residual solids. The need to pressurize the feed coal, limestone and combustion air, and to depressurize the flue gases and the ash removal system introduces some significant operating complications. The proportion of power coming from the steam : gas turbines is approximately 80:20%. Pressurized fluidized bed combustion and generation by the combined cycle route involves unique control considerations, as the combustor and gas turbine have to be properly matched through the whole operating range. The gas turbines are rather special, in that the maximum gas temperature available from the FBC is limited by ash fusion characteristics. As no ash softening should take place, the maximum gas temperature is around 90$0^{\circ}C$. As a result a high pressure ratio gas turbine with compression intercooling is used. This is to offset the effects of the relatively low temperature at the turbine inlet.