• 전기학회논문지
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• 제59권11호
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• pp.2006-2011
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• 2010

The superheater in the thermal power plant makes the wet steam into the dry steam with high temperature and high pressure by using the boiler heat. The dry steam pressure rotates the turbine-generator system. The efficiency and life time of the boiler heavily depends on the steam temperature regulation. The steam temperature can be deviated from the reference by the MW demand of the power plant. It is therefore required that the PI(proportional-integral) controller should be robust against the disturbance such as the MW demand. In this paper, the PI controller with the integral state predictor is proposed and applied to regulate the steam temperature of the superheater, and it is compared with the conventional PI controller operated in the thermal power plant in view of control performance.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1686-1691
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• 2004

The effect of recirculated exhaust gas on performance and exhaust emissions with FGR rate are investigated by using a natural circulation, pressurized draft and water tube boiler with FGR system operating at several boiler loads and over fire air(OFA) damper openings. The purpose of this study is to apply the FGR system to a power plant boiler for reducing $NO_{x}$ emissions. To activate the combustion, the suction damper of two stage combustion system installed in the upper side of wind box is opened by handling the lever between $0^{\circ}$ and $90^{\circ}$ , and the OFA with 0 to 20% into the flame is supplied, as the combustion air supplied to burner is reduced. It is found that the fuel consumption rate divided by evaporation rate does not show an obvious tendency to increase or decrease with rising the FOR rate, and $NO_{x}$ emissions are decreased, at the same OF A damper opening, as FOR rates are elevated and boiler loads are dropped.

• 에너지공학
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• 제14권2호
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• pp.147-152
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• 2005

본 논문에서는 화력발전소 보일러 연료소비량을 측정에 의하지 않고 계산으로 구하는 방법을 세부 항목 별로 유도하고 그 결과를 검증하였다. 보일러 경계를 출입하는 Energy in Energy out의 정량적 관계를 분석하여 Energy in에 해당하는 투입열량과 Energy out에 해당하는 흡수열량 및 손실열량으로부터 에너지 출입의 유기적인 관계식을 수립하여 연료소비량 계산식을 유도, 정립하고 실제 운전중인 석탄 및 중 유연소 발전소에 적응하여 계산식의 정확성을 검증하였다.

• 플랜트 저널
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• 제4권3호
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• pp.54-59
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• 2008

The resonance of boiler is caused by exciting force in the gas path and it generates the vibration by the harmony of boiler's dimensional factor. According to trending toward the boiler of increasing capacity and a bigger size, it has a problem of the vibration at back-pass heating surfaces. We can predict such vibrations as comparison between vortex frequency and gas column's natural frequency. We can't rely on the method for the past decades because of changing parameters, such as an allowable error, gas temperature, gas velocity, Strouhal number. We can reduce the vibration to use the seasoning effect and change the operating condition in coal fired boiler but it's not essential solution. When the vibration occurred in the model boiler, we must measures the acoustic pressure and frequency of places for considering the means. So far, we confirmed the problem from field measures and theoretical analysis about the acoustic vibration of boiler. We installed anti-acoustic baffle in a existing boiler to change the acoustic natural frequency at the cavity, which results in reducing the acoustic vibration. The first, we prove that the acoustic resonance is caused by harmonizing vortex shedding frequency of tube heat surface with acoustic natural frequency of cavity in the range of 650~750 MW loads. The second, the acoustic resonance at the back-pass heating surface has the third order of acoustic natural frequency at the second economizer. We install five anti-acoustic baffles at the second economizer to reducing the resonance. We confirm considerably reducing the acoustic vibration of boiler during the commercial boiler.

• 비파괴검사학회지
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• 제24권1호
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• pp.45-51
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• 2004

발전소 보일러튜브는 장시간 동안 고온고압하의 기혹한 조건으로 운전됨에 따라 크리프, 열피로와 같은 각종 열화에 의해 누설손상이 발생하고 있다. 이러한 누설손상을 실시간 감시하고 진단하기 위하여 음향방출기술을 이용한 현장적용 연구를 수행하였다. 또한 고장예측 진단기술, 튜브의 수명관리 및 설비 감시에 활용할 수 있도록 음향방출 진단시스템을 개발하여 현장에 설치하고, 보일러 운전상태에 따른 신호측정 및 평가, 누설위치 판별 등에 대해 고찰하였다. 누설감지는 저주파 및 고주파대역의 누설로 구분하여 음향방출신호를 각각 측정 및 평가하였다. 현장적용 연구결과로부터 실시간으로 보일러튜브 상태감시와 누설위치 추적이 가능하였으며, 향후 본 기술을 이용하면 발전설비 안전운전과 발전소 정지에 따른 경제적 손실 예방에 크게 기여할 것으로 기대된다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.642-647
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• 2008

The boiler structure is determined by combustion characteristics and construction costs in the combustion chamber of a large commercial boiler. The heat transfer in boiler is composed of the radiation and the convection. The convective heat transfer has happened to back-pass heating surface. The combustion gas sequentially passes through the reheater tube, 1st economizer tube, and 2nd economizer tube. In case of being lowered in boiler height, we have to install additional tube bundle in back-pass heating surface for increasing the heat transfer of boiler, which causes the noise and vibration from combustion gas. When the combustion gas passes through the back-pass tube bundle in specified load of commercial boiler, this paper analyzes the acoustic characteristics between vortex-shedding frequency and natural frequency in tube bundle cavity. The case study reduce the resonance by changing natural frequency characteristics of tube-bundle cavity using a way to install ant-noise baffle in the direction of combustion gas flow.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2005년도 창립60주년 기념 추계 학술대회
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• pp.93.1-93.1
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• 2005

• Journal of Electrical Engineering and Technology
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• 제11권4호
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• pp.848-859
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• 2016

System failures in thermal power plants (TPPs) can lead to serious losses because the equipment is operated under very high pressure and temperature. Therefore, it is indispensable for alarm systems to inform field workers in advance of any abnormal operating conditions in the equipment. In this paper, we propose a clustering-based fault detection method for steam boiler tubes in TPPs. For data clustering, k-means algorithm is employed and the number of clusters are systematically determined by slope statistic. In the clustering-based method, it is assumed that normal data samples are close to the centers of clusters and those of abnormal are far from the centers. After partitioning training samples collected from normal target systems, fault scores (FSs) are assigned to unseen samples according to the distances between the samples and their closest cluster centroids. Alarm signals are generated if the FSs exceed predefined threshold values. The validity of exponentially weighted moving average to reduce false alarms is also investigated. To verify the performance, the proposed method is applied to failure cases due to boiler tube leakage. The experiment results show that the proposed method can detect the abnormal conditions of the target system successfully.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.342-348
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• 2002

The welding technology for production of power plant facility as for other industries has been progressing forward automation and mechanization for cost reduction and shortening of cycle time. The welding for boiler tube is automated or mechanized as the parts and subassemblies of tubes are conveyed automatically in the shop. The temperature of boiler stearn is being progressively increased for higher plant efficiency. The welding of nuclear component is characterized by heavy thickness and narrow gap Submerged Arc Welding. Narrow gap Gas Metal Arc Welding and Electron Beam Welding is applied to turbine diaphragm. To improve the resistance of solid particle erosion of turbine blade and nozzle partition, HVOF spray technology and boriding process has been applied.

• 대한기계학회논문집A
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• 제24권11호
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• pp.2812-2822
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• 2000

Several methods have been developed to predict the rupture time of the boiler tubes in thermal power plant. However, existing life prediction methods give very conservative value at operating stress of power plant and rupture strain cannot be well estimated. Therefore, in this study, rupture time and strain prediction method accounting for creep, corrosion and heat transfer is newly proposed and compared with the current research results. The creep damage evolves by continuous cavity nucleation and constrained cavity growth. The corrosion damage evolves by steam side and fire side corrosion. The results showed good correlation between the theoretically predicted rupture time and the current research results. And rupture strain may be well estimated by using the proposed method.