• 한국가스학회지
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• 제22권4호
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• pp.39-48
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• 2018

가스리프트(gas lift) 설계 영향인자인 오일 조성과 주입가스 조성에 따라 해저 오일 저류층(offshore oil reservoir) 내 가스리프트 최적 설계를 수행하였다. 이를 위해 오일의 API 비중에 따라 구축된 저류층 모델을 이용하여 생산 시뮬레이션을 수행하였다. 저류층의 지속적인 생산성 감소 시, 가스리프트 적용에 의한 오일 생산증진효과가 크게 나타남을 확인하였다. 생산정 모델을 이용하여 가스리프트 반응곡선을 분석한 결과, 오일의 API 비중이 감소하고 주입가스의 비중이 증가할수록 생산량 증진에 필요한 주입 가스량이 높게 산출되었다. 다중밸브를 이용하여 가스리프트 최적 설계를 수행하였으며, 단일밸브 설계와 비교했을 때 가스 주입심도 감소로 인해 상대적으로 낮은 주입압력으로도 가스리프트 공법 운영이 가능하였다. 저류층 모델과 생산정 모델을 연계하여 가스리프트 적용에 따른 오일 생산증진을 분석한 결과, API 비중이 낮은 중질유 저류층에 천연가스를 주입했을 때 가스리프트에 의한 생산효율이 극대화될 수 있다.

• 한국유체기계학회 논문집
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• 제13권6호
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• pp.57-62
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• 2010

MW-class gas turbines are suitable for distributed generation systems such as community energy systems(CES). Recently, biogas is acknowledged as an alternative energy source, and its use in gas turbines is expected to increase. Steam injection is an effective way to improve performance of gas turbines. This study intended to examine the influence of injecting steam and using biogas as the fuel on the operation and performance a gas turbine combined heat and power (CHP) system. A commercial gas turbine of 6 MW class was used for this study. The primary concern of this study is a comparative analysis of system performance in a wide biogas composition range. In addition, the effect of steam temperature and injected steam rate on gas turbine and CHP performance was investigated.

• 한국입자에어로졸학회지
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• 제8권4호
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• pp.125-132
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• 2012

Mercury oxidation in an SCR(selective catalytic reduction) catalyst was tested in this study with the conditions simulating the SCR system in full-scale coal-fired flue gas. A commercially available SCR catalyst was located in a temperature-controlled reactor system, and simulated gas was injected into the reactor. Mercury oxidation efficiency was determined from the difference between inlet and outlet elemental mercury concentrations. A control experiment was carried out with the gas composition of 12% $CO_{2}$, 5% $H_{2}O$, 5% $O_{2}$, 500 ppm $SO_{2}$, 400 ppm NO, 400 ppm $NH_{3}$, 5 ppm HCl, and 20 ${\mu}g/m^{3}$ Hg. Additional tests were conducted with different gas composition from the control condition to investigate the effect of gas composition on mercury oxidation in the SCR catalyst.

• Journal of Korean Society for Atmospheric Environment
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• 제19권E4호
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• pp.169-175
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• 2003

The effect of gas composition on the discharge characteristics and the ozone production in silent discharge (SD) process was investigated. The major gas components, $N_2$, $O_2$, and $H_2O$ influence the discharge properties according to their relative magnitude of ionization thresholds and electron affinities. The generated amount of ozone increased with the discharge energy by increasing the electron mean energy. The higher oxygen content injected, the higher ozone produced. A small amount of water vapor significantly lowered the discharge onset voltage by the ionization threshold decreasing effect and high electrical conductivity. However, the further increase of water vapor contributes to decrease the electron density by the electron affinity The addition of water greatly reduced the ozone generation through the formation of OH radical and the catalytic ozone destruction process.

• Asian-Australasian Journal of Animal Sciences
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• 제16권3호
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• pp.380-383
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• 2003

The gas dilution technique was used to evaluate the possibility of estimating the volume of gaseous phase in the rumen from its composition in sheep given rice whole crop silage (RWS) or dent corn silage (DCS) at a level of maintenance (M) or 2 M, and in the course of fasting. The rumen gas composition was determined at 2 and 7.5 h after morning feeding. Nitrogen gas was injected by using an airtight syringe into the rumen immediately after collecting the rumen gas sample as a control. Then rumen gas samples were collected at 5, 10, 20, 40 and 60 min. after injection. Dry-matter intakes were $42g/kg^{0.75}$ and $57g/kg^{0.75}$ for DCS, and $36g/kg^{0.75}$ and $59g/kg^{0.75}$ for RWS, at 1 M and 2 M levels, respectively. Animals ingested both silages about 20% less than expected at 2 M level. The rumen gas composition did not differ significantly between 2 h and 7.5 h after feeding except for $N_2$. Content of $CO_2$ in gas composition was significantly higher at 2 M level than at 1 M (p<0.05) for both RWS and DCS, whereas $CH_4$ showed no significant difference between feeding levels. At both feeding levels, $CO_2$ showed a higher (p<0.05) percentage in DCS than RWS. A dilution technique by using $N_2$ injection is not appropriate for the determination of gas production in vivo, unless the rate of rumen gas turnover is considered. Changes in composition at fasting indicate that the rumen fermentation may reach the lowest level after 72 h fasting for sheep given silage as their sole diet.

• 한국세라믹학회지
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• 제29권9호
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• pp.681-688
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• 1992

Ultrafine Si3N4 and Si3N4+SiC mixed powders were synthesized through thermal plasma chemical vapor deposition(CVD) using a hybrid plasma, which was characterized by the supersposition of a radio-frequency plasma and arc jet. The reactant SiCl4 was injected into an arc jet and completely decomposed in a hybrid plasma, and the second reactant CH4 and/or NH3 mixed with H2 were injected into the tail flame through double stage ring slits. In the case of ultrafine Si3N4 powder synthesis, reaction efficiency increased significantly by double stage injection compared to single stage one, although crystallizing behaviors depended upon injection speed of reactive quenching gas (NH3+N2) and injection method. For the preparation of Si2N4+SiC mixed powders, N/C composition ratio could be controlled by regulating the injection speed of NH3 and/or CH4 reactant and H2 quenching gas mixtures as well as by adjusting the reaction space.

• 한국자동차공학회논문집
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• 제16권4호
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• pp.56-62
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• 2008

A synthetic gas reformed from hydrocarbon-based fuels consists of $H_2$, CO and $N_2$. Hydrogen contained in the synthetic gas is a very useful species in chemical processes, due to its wide flammability range and fast burning speed. The ESGI (Exhaust Synthetic Gas Injection) technology is developed to shorten the light-off time of three way catalysts through combustion of the synthetic gas in the exhaust manifold during the cold start period of SI engines. Before the ESGI technology is applied to the test engine, the authors set a test rig that consists of gas temperature and composition controllers, an exhaust pulse generator and an exhaust manifold with a visualization window, in order to optimize the point and conditions of injection of the synthetic gas. Through measuring burned gas temperatures and taking photographs of synthetic gas combustion at the outlet of the exhaust manifold, the authors tried to find the optimal injection point and conditions. Analysis of burned gas composition has been performed for various $O_2$ concentrations. As a result, when the synthetic gas is injected at the port outlet of the cylinder No. 4 and $O_2$ concentration exceeds 4%, combustion of the synthetic gas is strong and effective in the exhaust manifold.

• 한국수소및신에너지학회논문집
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• 제33권4호
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• pp.363-371
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• 2022

In this study, the operation characteristics of the internal reforming type molten carbonate fuel cell (MCFC) were studied using computational fluid dynamics (CFD) analysis according to the steam to carbon ratio (S/C ratio), operating temperature, and gas utilization. From the simulation results, the distribution of gas composition due to the electrochemical reaction and the reforming reaction was predicted. The internal reforming type showed a lower temperature difference than the external reforming type MCFC. As the operating temperature decreased, less hydrogen was produced and the performance of the fuel cell also decreased. As the gas utilization rate decreased, more gas was injected into the same reaction area, and thus the performance of the fuel cell increased.

• 한국수소및신에너지학회논문집
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• 제21권5호
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• pp.452-459
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• 2010

This study is aimed to investigate changes of combustion characteristics and heat efficiency when syngas from gasification process using low-rank fuel such as waste and/or biomass is applied partially to an industrial boiler. An experimental study on syngas co-combustion was performed in a 0.7 MW (1 ton steam/hr) water tube boiler using heavy oil as a main fuel. Three kinds of syngas were used as an alternative fuel: mixture gas of pure carbon monoxide and hydrogen, syngas of low calorific value generated from an air-blown gasification process, and syngas of high calorific value produced from an oxygen-blown gasification process. Effects of co-combustion ratio (0~20%) for each syngas on flue gas composition were investigated through syngas injection through the nozzles installed in the side wall of the boiler and measuring $O_2$, $CO_2$, CO and NOx concentrations in the flue gas. When syngas co-combustion was applied, injected syngas was observed to be burned completely and NOx concentration was decreased because nitrogen-containing-heavy oil was partially replaced by the syngas. However, heat efficiency of the boiler was observed to be decreased due to inert compounds in the syngas and the more significant decrease was found when syngas of lower calorific value was used. However, the decrease of the efficiency was under 10% of the heat replacement by syngas.

• 청정기술
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• 제19권2호
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• pp.113-120
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• 2013

화학적으로 안정한 과불화합물을 처리하기 위해서는 많은 양의 에너지를 필요로 한다. 이러한 단점을 극복하기 위해서 저전력 아크 플라즈마 시스템을 개발하였다. 분해대상은 $CF_4$, $SF_6$, $NF_3$가 플라즈마 토치로 직접 주입되었으며, 아크 플라즈마 토치의 열효율을 측정하여 실출력을 계산하였다. 실출력과 폐기체 유량 변화 그리고 추가적인 반응가스에 의한 분해효율을 확인하였다. 또한 열역학적 평형조성 분석을 수행하여 실험 결과와 비교하였다. 토치의 열효율은 60~66%의 결과를 보였으며 폐가스 유량이 증가함에 따라 분해효율이 감소하였고 입력전력이 늘어남에 따라 분해효율이 상승되었다. 추가적인 반응 가스가 없이 $CF_4$, $SF_6$, $NF_3$의 분해효율은 입력전력이 3 kW, 폐가스 유량이 70 L/min인 조건에서 각각 4, 15, 90%를 보였다. 반응가스로 산소와 수소를 이용하여 분해효율을 급격하게 증가시킬 수 있었으며, 실험 결과 산소보다 수소를 사용하였을 경우가 분해효율 상승효과와 부산물 제어에 효과적인 것을 알 수 있었다. 수소의 경우, 발생되는 부산물은 불화수소산이었으며 이는 일반적인 습식 스크러버를 이용하여 처리가 용이한 물질이다. 수소를 이용한 화학반응에서 입력전력이 3 kW, 폐가스유량이 100 L/min인 조건에서 $CF_4$가 25%, $SF_6$가 39%, $NF_3$가 99%의 분해효율을 각각 나타냈다.