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증기터빈의 기동조건과 성능개선이 터빈의 진동에 미치는 영향
이혁순,정혁진,송우석,Lee, Hyuk Soon,Chung, Hyuk Jin,Song, Woo Sok 한국압력기기공학회 2011 한국압력기기공학회 논문집 Vol.7 No.3
The analysis shows that the vibration is one of the main reasons of turbine failure. Especially, the problems caused by vibration occur right after retrofit of the turbine-generator and restarting the turbine. Through the case study of high vibration caused by after the turbine trip and restart, turbine vibration was identified to be influenced by startup condition. Turbine startup at high casing temperature right after unscheduled turbine trip cause radial expansion in rotor by contraction in axial direction, while casing continues to contract by steam flowing into casing. Consequently, gap between rotor and casing decrease until to metal contact to cause high vibration. Through the case study of high vibration of turbine-generator system after generator retrofit, it was identified that generator replacement could cause high vibration in turbine-generator system if the influence of generator replacement on entire system was not considered properly. To prevent startup delay caused by high vibration, it is important to keep the gaps at the design standard and start the turbine after thermal equilibrium.
상태기반정비에 의한 증기터빈 저널베어링의 정비주기 최적화
이혁순,정혁진,송우석,Lee, Hyuk Soon,Chung, Hyuk Jin,Song, Woo Sok 한국압력기기공학회 2011 한국압력기기공학회 논문집 Vol.7 No.2
Turbine journal bearings are designed to support the weight of the rotors on a hydrodynamic oil film and to provide dynamic stability to the rotor system. The life time of journal bearings is infinite theoretically because the journal bearings are separated from the shaft journal by oil film. But poor design, assembly, operation and maintenance can cause problems to the journal bearings. The FMEA(Failure Mode and Effects Analysis) results of the journal bearings show that frequent maintenance of the journal bearings can cause failures and reduction of the bearing life. Therefore, the maintenance periods and history of the journal bearings with the bearing FMEA results are reviewed in order to establish the optimized maintenance period of the journal bearing for the nuclear power plants. Consequently it is necessary to maintain a best condition of lubrication system, reject time-based maintenance and perform the condition-based maintenance of journal bearings in order to maintain optimum condition of the journal bearing.
이혁순(H. S. Lee),유성연(S. Y. Yoo),이상식(S. S. Lee) 한국유체기계학회 2007 유체기계 연구개발 발표회 논문집 Vol.- No.-
Seat leakage, seat wear and erosion by cavitation are main degradation mechanisms in control valve. One of most desirable solution of cavitation is to minimize velocity change by installing improved cage using the series restriction stage. In this research, suitability of existing valve was reviewed using CFD and design analysis. According to the result of the research, design modification for the control valve was performed, and the result of modification was also reviewed using CFD. The modified valve showed a improved velocity pattern without cavitation.
이혁순(Hyuk Soon Lee),최문호(Moon ho Choi) 한국유체기계학회 2019 유체기계 연구개발 발표회 논문집 Vol.2019 No.7
The auxiliary feed water supply system of the nuclear power plant should be kept in the standby state at all times as a heat removal source and high pressure cooling water should be injected into the steam generator of high pressure in case of emergency. The auxiliary feed water supply system consists of a main flow path for injecting cooling water into the steam generator from the multi-stage pump and a bypass flow path for the safe operation and performance test of the pump. The bypass piping of the auxiliary feed pump was equipped with a multi-stage orifice to reduce the pressure, and leakage occurred at the downstream of the multi-stage orifice during the performance test. The cause of the leakage was estimated to be a cavitation phenomenon and it was verified by numerical analysis. In addition, by measuring the vibration of bypass pipe by controlling flow rate through bypass channel, it was proved that cavitation occurred in multistage orifice through this and it was recommended to limit the flow rate of bypass channel to prevent further leakage.