• 한국방재학회 논문집
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• 제4권2호
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• pp.53-59
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• 2004

본 연구는 집중호우 시에 발생하는 맨홀뚜껑의 비산(飛散)현상의 원인을 수리모형과 수치모형(SWMM)을 사용하여 밝힌 연구이다. 대규모 간선에서 써차지 흐름의 급격한 수두상승 현상에 대해 수치모형과 수리모형 결과가 매우 잘 일치하였다. 맨홀 뚜껑이 비산 하는 현상의 원인은 펌프장의 게이트 조작이나 간선의 막힘 등으로 발생하는 써차지 흐름에 따른 압력전파에 의해 기인하는 맨홀 내 잔존 압축공기괴의 맨홀에서의 팽창 분출에 의한 것으로 나타났다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 19-21 Oct. 1992
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• pp.292-296
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• 1992

There are lots of disturbance in the super heater temperature control system of power plant boiler as follows. 1.Burner light off. 2.Excess Air. 3.Burner tilt. 4.G.R fan flow. Temperature control system of super heater in the power plant has delay time about 5 min. So it is difficult to control the super heater temperature in the power plant. This paper show us the application of domestic development DCS to control the super heater temperature in seoul #5 thermal power plant unit.

• 연구논문집
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• 통권27호
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• pp.101-108
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• 1997

The characteristics of combustion and emissions in multi-staged oil burner have been experimentally studied for the various range of equivalence ratios, drop sizes and fuel formulations. Malvern system was used to measure droplet size of fuel. Light fuel oil and light fuel oil doped with pyridine($C_5H _5N$) were used to investigate the effects on fuel NOx emission. The emissions of NO and CO in exhaust gas and the flame temperatures were measured by the gas analyzer and thennocouples. NOx emissions were increased by increasing the excess air ratio (range:$lambda=1.1-1.4$) or decreasing the SMD of droplet in single-staged burner. In comparison with the single-staged burner, the emission of NOx in multi-staged burner was reduced by 50% but CO emission was slightly increased. It is found that multi-staged burner has a good capability in reducing thermal NOx resulting from the distributed heat release rate and lower flame temperature in fuel-rich and fuel-lean combustion zone. Moreover, the fuel NOx emission of the multi-staged burner is lower than that of single-staged burner, because multi-staged burner has fuel rich zone where fuel N is converted to $N_2$ more than NO. In 3-staged burner, the percentage of each stage combustion air have strong influence on emission characteristics. It is also found that NOx emission can be reduced by decreasing inner and outer air percentage or increasing middle air flow rate and CO emission is vice versa.

• 한국환경과학회지
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• 제6권3호
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• pp.267-276
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• 1997

It has been studded that combustion and the production of air pollution of anthracite - bituminous coal blend In a fluidized bed coal combustor, The objects of thIns study were to investigate mixing characteristics of the particles as well as the combustibility of the low grade domestic anthracite coal and Imported h19h calorific bltununous coal in the fluidized bed coal combustor. They were used as coal samples ; the domestic low grade anthracite coal with heating value of 2,010kca1/kg and the Imported high grade bituminous coal with beating value of 6,520kca1/kg. Also, the effects of air flow rate and anthracite fraction on the reaching time of steady state condition have been studied. The experimental results are presented as follows. The time of reaching to steady state was affected by the temperature variation. The steady state time was about 120 minute at 300sc1h which was the fastest. It has been found that $O^2$ and $CO^2$ concentration were reached steady state at about 100 minute. It has been found that $O^2$ concentration decreased and $CO^2$ concentration increased as the height of fluidlzed bed Increased. It was found that splash zone was mainly located from 25cm to 35cm above distributor. Also, as anthracite traction Increased, the mass of elutrlatlon particles Increased, and $CO^2$ concentration decreased. As gk flow rate Increased,$O^2$ concentration decreased and $CO^2$ concentration increased. Regardless of anthracite fraction and flow rate, the uncombustible weight percentage according to average diameter of elutriation particles were approldmately high In the case of One Particles. As anthracite traction and k now rate Increased, elutriation ratio Increased. As anthracite fraction was increased, exit combustible content over feeding combustible content was Increased. Regardless of anthracite fraction, size distribution of Ued material from discharge was almost constant. Over bed temperature 85$0^{\circ}C$ and excess air 20% , the difference of combution efficiencies were little. It is estimate that the combustion condition In anthracite-bituminous coal blend combustion is suitable at the velocity 0.3m/s, bed temperature 85$0^{\circ}C$, the excess air 20%.

• 한국수소및신에너지학회논문집
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• 제34권1호
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• pp.38-46
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• 2023

Carbon neutrality policies have been strengthened to reduce emissions, and the importance of technology road maps has been emphasized. In the global industrial boiler market, carbon neutrality is implemented through fuel diversification of methane-hydrogen mixture gas. However, various problems such as flashback and flame unstability arise. There is a limit to implementing the actual system as it remains in the early stage. Therefore, it is necessary to secure the source technology of methane-hydrogen hybrid combustion system applicable to industrial fields. In this study, control program for methane-hydrogen fuel conversion was developed to expect various parameters. After determining the hydrogen mixing ratio and the input air flow, the fuel conversion control algorithm was constructed to get the parameters that achieve the target oxygen concentration in the exhaust gas. LabVIEW program was used to derive correlations among hydrogen mixing rate, oxygen concentration in exhaust gas, input amount of air and heating value.

• 대한환경공학회지
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• 제30권9호
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• pp.948-954
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• 2008

침지형 MBR 공정에서 막 오염과 플럭스 감소의 주요 원인인 케이크층에 의한 저항을 저감하기 위하여 분리막 모듈의 외부에 원통형 관을 도입하였다. 도입된 원통형관 안에 노즐과 산기관을 적용하여 공기 주입량에 따른 공기와 액체의 2상흐름(Two phase flow)중 slug 흐름을 유도하여 공기 방울에 의한 막세정의 효과를 비교 분석하였다. 실험결과 동일한 유량의 공기를 공급할 경우 노즐에서 발생한 공기방울이 원통형관으로 유입되면서 효율적인 slug 흐름을 형성으로 산기관을 사용한 공급 방식보다는 막오염 방지에 효과적이었음을 알 수 있었다. 그러나 노즐로 공급되는 공기의 유량을 최적화하지 않는다면 원통형 관의 벽 부분부터 활성슬러지 혼합액이 퇴적하게 되거나 막간에 슬러지가 퇴적되어 관 내부의 급격한 막힘 현상이 발생하여 일정시간이 경과하면, 오히려 산기관보다 급격한 막오염 현상을 나타냄을 알 수 있었다. 또한 원통형 관 내부에 침지된 분리막의 면적의 최적 비율, A$_m$/A$_t$가 비율이 존재하는 것을 확인할 수 있었다. 산기관의 경우에는 A$_m$/A$_t$ 비율이 0.27일 때 최소화된 막오염이 관찰된 반면에, 노즐의 경우에는 A$_m$/A$_t$ 비율이 0.55일 때 막오염이 최소값을 보였다. 따라서 상승하는 공기방울에 의한 막오염 저감효과는 관 내부의 중공사막이 차지하고 있는 비율, A$_m$/A$_t$에 크게 의존하고 있으며, 산기관과 노즐의 경우 그 최적비율은 각각 다름을 알 수 있었다.

• International Journal of Aeronautical and Space Sciences
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• 제1권1호
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• pp.62-69
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• 2000

Present study deals with performance analysis of an inert gas generator (IGG) which can be used as effective means to suppress fire. The IGG uses a turbo-jet engine to generate inert gas for fire extinguishing. It is generally known that a less degree of oxygen content in the product of combustion will increase the effectiveness of fire extinguishing. An inert gas generator system with water injection has advantages of suffocating and cooling effects that are very important factors for fire extinguishing. Some aspects of influencing parameters, such as, air excess coefficient, compressor pressure ratio, air temperature before combustion chamber, gas temperature after combustion chamber, mass flow rate of water injection etc. on the performance of IGG system are investigated.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2006년도 제33회 KOSCO SYMPOSIUM 논문집
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• pp.299-303
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• 2006

From the analysis of fly ash, which contains unburned carbon, collected from the coal-fired Yong Hung power station, most particles are turned out to be hollow cenosphere and agglomerated soot particles. The sooting potential from six coals used in the plant were investigated with CPD model. The results show that the higher potential presented to Peabody, Arthur, Shenhua coals rather than other coals. It is necessary to measure the coal flow rates at each coal feeding pipe for four burner levels since they affect the extent of mixing of soot with oxidant, in turn, the oxidation rate of soot particles. The unbalance in coal flow rate was found in several coal pipes. We successfully reduced unburned carbon in ash by increasing the excess air and changing the SOFA yaw angle.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.973-978
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• 2001

Numerical Analysis for liquid fuel combustion of horizontal firing boiler is performed. The mixture-fraction/PDF equilibrium chemistry model is used to predict the combustion of the vaporized fuel. P1 model for radiation effect is used. Superheater, reheater and economizer is modeled using porous with heat sink. Flow and temperature field is investigated, and distribution of thermal $NO_{x}$ and CO is investigated. Computation as the change of excess air and swirling is performed to investigate the change of thermal $NO_{x}$.

• 한국자동차공학회논문집
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• 제14권2호
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• pp.114-120
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• 2006

The basic effects of hydrogen addition for engine performance and emission were investigated in single cylinder research engine. Seven commercial injectors were tested to choose a suitable injector for hydrogen injection prior to its engine implementation. The hydrogen fuel leakage and flow rate were evaluated for each injector and KN3-1(Keihin, CO.) showed the best performance for hydrogen fuel. At the higher excess air ratio(${\lambda}=1.7$, 2.0), the better combustion stability was found with hydrogen addition even though its effect was small at lower excess air ratio (${\lambda}=1.0$, 1.3). Stable operation of the engine was even guaranteed at ${\lambda}=2.0$, if the amount of hydrogen gas was near 15% of total energy. In the lean region, ${\lambda}>1.3$, thermal efficiency was improved slightly while it was not clearly observed at ${\lambda}=1.0$, 1.3. It is considered that, in some cases, high temperature environment due to hydrogen combustion caused further heat loss to surroundings. Except for ${\lambda}=1.0$, with larger amount of hydrogen addition, CO was reduced drastically but it was emitted more at the leaner region. Nitric oxides(NOx) was increased a little more with hydrogen addition at ${\lambda}=1.0$, 1.3. However, at ${\lambda}>1.3$ its relative amount of emission was low. In addition, the amount of NOx was continuously decreased with hydrogen addition, but, at ${\lambda}=2.0$ the amount of NOx was lowered to 1/100 of that of ${\lambda}=1.0$. THC emission was significantly increased as air/fuel ratio was raised to leaner region due to misfire and partial burn.