• 한국물환경학회지
• /
• 제22권6호
• /
• pp.1119-1122
• /
• 2006

Aeration by using diffusers usually requires approximately 50~90% of the total electricity needed to operate WWTP (WasteWater Treatment Plant)s. Accurate evaluation of the oxygen transfer efficiency for an aeration system, and recommendation of a better alternative may help saving WWTP operational costs. Appropriate techniques and methods to achieve this purpose have not been introduced in Korea. In this study, in-process analysis was performed for a coarse bubble aeration system by the off-gas method to evaluate its applicability in Korea. To accomplish this analysis, an off-gas test, unsteady-state clean water test and steady-state off-gas column test was conducted and comparisons to other aeration systems were made. The ${\alpha}$ and the F estimated from the results of the unsteady-state clean water test and the steady-state off-gas column test were 0.61 and 0.90 respectively in a coarse bubble aeration system. The comparison of P.E tube diffusers laid out single spiral roll and ceramic dome diffusers laid out full floor coverage showed that the oxygen transfer efficiency of the coarse bubble aeration system was less than or similar to other aeration systems. But, airflow rates per unit area were 4~5 times greater than other aeration systems. In regards to the oxygen transfer efficiency for airflow rates per unit area, a retrofit to higher efficiency diffusers was urgently needed. This study showed proved that off-gas methods can apply to evaluate diffuser performances to estimate operating factors and to compare other aeration systems in Korea.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2008년도 추계학술대회B
• /
• pp.2198-2203
• /
• 2008

Hydrogen which can be produced through reforming process of hydrocarbon fuel is supplied into anode side of fuel cell system. In the fuel cell, only 70% of hydrogen is consumed through electrochemical reaction and 30% hydrogen passed by as anode off gas. When electrical output of fuel cell is within range of 1.0 to 3.0kW, burner for the reformer uses only anode off gas. And it uses mixture gas of anode off gas and LNG within range of 3.5 to 5.0kW in electrical output. CHEMKIN 4.1 program's Premixed code was used for calculating the properties of each gas. Results show that burning velocity and adiabatic flame temperature are 34.4cm/s, 1681.7K at equivalence ratio 0.8 within range of 1.0kW to 3.0kW and for cases of 3.5kW, 5.0kW, of electrical output, burning velocity and adiabatic flame temperature represent 30.5, 29.8cm/s and 1722.8, 1750K respectively. CO shows the lowest emission index at equivalence ratio 0.8 and NOx reveals the highest emission index at equivalence ratio 1.

• Journal of Radiation Protection and Research
• /
• 제25권2호
• /
• pp.99-107
• /
• 2000

플라즈마 아크 용융방식 유리화 시험설비의 계통내 기체 및 최종배출구 전단의 배기체를 분석함으로써 배기체중에 포함된 분석용 첨가물의 거동 및 배기가스 처리장치의 제염성능을 평가하였다. 중금속 물질(Pb, Cd, Hg), 방사성 모의물질(Co, Cs) 그리고 방사성핵종($^{60}Co,\;^{137}Cs$)을 분석용 첨가물로 사용한 실험결과로부터 첨가물질의 거동에 따른 유리화 설비 배기체처리시스템의 제염특성 및 제염제수를 구하였다.

• 한국연소학회지
• /
• 제17권4호
• /
• pp.5-10
• /
• 2012

The reformer system is a chemical device that drives the conversion of hydrocarbon to hydrogen rich gas under high temperature environment($600-1,000^{\circ}C$). Generally, NG(Natural Gas) or AOG(Anode Off Gas) is used as fuel of fuel cell reformer combustion system. The experimental study to analyze the combustion characteristics of a premixed ceramic burner used for 0.5-1.0 kW fuel cell reformer was performed. Ceramic burner experiments using NG and AOG were carried out to investigate the flame stability characteristics by heating capacity, equivalence ratio and different fuels respectively. The results show that surface flames can be classified into green, red, blue and lift-off flames as the equivalence ratio of methane-air mixture decreases. And the stable flames can be established using NG and AOG as reformer fuel in the perforated ceramic burner. In particular, the blue flame is found to be stable at a lean equivalence ratio under different mixture conditions of NG and AOG for the 0.5 to 1.0 kW fuel cell system power range. NOx emission is under 60 ppm between 0.70 to 0.78 of equivalence ratio and CO emission is under 50 ppm between 0.70 to 0.84 of equivalence ratio.

• 한국가스학회지
• /
• 제19권6호
• /
• pp.80-84
• /
• 2015

본 연구에서는 기존의 차단기능형 수직식 용기밸브와 새로이 개발된 수평식 용기밸브의 몸체전고와 중량에 대한 설계 데이터를 고찰하였다. 차단기능형 수평식 용기밸브의 전고는 기존의 차단기능형 수직식 용기밸브에 비해 41~42%나 획기적으로 줄어들었다. 또한, 수평식 밸브의 몸체 무게는 기존의 차단기능형 수직식 밸브에 비해 29~40%나 줄어든 결과를 얻었다. 이러한 결과는 단지 기존의 수직식 밸브에서 밸브의 여러 가지 구성요소를 수평식으로 배열을 바꾼 구조변경 설계를 통해 확보한 것이다.

• Journal of Korean Society for Atmospheric Environment
• /
• 제9권E호
• /
• pp.382-389
• /
• 1993

An evaluation of a plasma reactor was conducted to investigate its potential as a feasible and economical off-gas control technology for an air stripping tower (AST). The plasma reactor was powered by an alternating current with frequencies up to 1000Hz. The study showed that over 90% conversion of gas-phase trichloroethylene (TCE) can be achieved. An optimum frequency for the laternating current existed for maximum power input. The optimum frequency was dependent on the reactor geometry and the primary voltage applied. for a fixed geometry, a plasma reactor has a limited capacity for flow rate. Even though it is a feasible process to control off-gases, further investigations should be conducted to develop a more economic process.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2007년도 춘계학술대회논문집
• /
• pp.1100-1105
• /
• 2007

In the gas supply duct, the gas leakage caused by the impact of the construct equipment is serious problem. The identification of the impact position is an important issue and an engineering work. For the basic research of this problem, the principle studies for the acoustic wave propagation in a gas duct are proceeded in this paper. This principal work is based on the identification of the cut-off frequency associated with major modes of the gas duct theoretically and experimentally. The cut-off frequency is confirmed by STFT and cross-correlation function is used to identify the leakage position.

• 한국소음진동공학회논문집
• /
• 제18권8호
• /
• pp.797-804
• /
• 2008

In the gas supply pipe, the gas leakage caused by the impact of the construct equipment is serious problem. The identification of the impact position is an important issue and an engineering work. For the basic research of this problem, the principle studies for the acoustic wave propagation in a gas pipe are proceeded in this paper. This principal work is based on the identification of the cut-off frequency associated with major modes of the gas pipe theoretically and experimentally The cut-off frequency is confirmed by STFT and cross-correlation function is used to identify the leakage position.

• 대한기계학회논문집B
• /
• 제30권5호
• /
• pp.472-479
• /
• 2006

Recently, various methods have been developed to improve the performance of gas turbines for combined cycle power plants. This paper especially focused on the gas turbine with a reheat process. The purpose of this study is to analyze performance characteristics of a reheat-cycle gas turbine on both a design point and off-design operations. Results of the parametric study of this model show how operating and design parameters influence on the performance of the gas turbine. Moreover, possibilities for the analysis of off-design performance based on a self-generated compressor performance characteristic map are presented.

• 대한기계학회논문집
• /
• 제17권7호
• /
• pp.1851-1863
• /
• 1993

A procedure for the prediction of the off-design performance of a gas turbine engine is proposed. The system performance at off-design speed is predicted by coupling the thermodynamic models of a compressor and a turbine. The off-design performance of a compressor is obtained using the stage-stackimg method, while the Ainlay-Mathieson method is used for a turbine. The procedure is applied to a single-shaft gas turbine and its predictability is found satisfactory. The results also show that the net work output increases with the increase of the turbine inlet temperature, while the thermal efficiency is marginal. The maximum thermal efficiency at design point is obtained between the highest pressure ratio and design pressure ratio.