• Title/Summary/Keyword: Combined cycle power plants

Search Result 90, Processing Time 0.032 seconds

On-Line Detection of Shorted Turn in Generator Rotor Windings (발전기 회전자 권선의 운전중 층간단락 탐지)

  • Kim, Hui-Dong;Lee, Yeong-Jun;Park, Jong-Jeong;Ju, Yeong-Ho
    • The Transactions of the Korean Institute of Electrical Engineers C
    • /
    • v.48 no.3
    • /
    • pp.192-199
    • /
    • 1999
  • During start up and shut down, the generator is rotating at a low speed and copper dusts cause arcing between the turns in the slot. Shorted turns occurred primarily by the movement of these copper dusts between individual windings in the generator rotor. Detection of shorted turns was performed in five gas turbine generators in two combined cycle power plants. Two types of permanent and temporary flux probes were used in this paper. These flux probes have been used to develop a methodology for detecting shorted turns in an operating generator's rotor. The flux probes sense the rotor winding slot leakage flux and produce a voltage proportional to the rate of change of the flux. This pattern of flux variation is the signature unique to each rotor winding. An appropriate waveform analysis technique canidentify the pole location, the slot number, and the number of shorted turns within each slot. Shorted turns in field winding of gas turbine generator(125.7 MVA) were detected to twelve turns on al total 190 turns.

  • PDF

24 Hours Blood Pressure Variation and Related Risk factors (24시간 혈압 변동과 관련 위험 요인)

  • Choi In-Joo;Kim Young-Mi;Lee Hae-Jung
    • Journal of Korean Academy of Fundamentals of Nursing
    • /
    • v.12 no.3
    • /
    • pp.307-316
    • /
    • 2005
  • Purpose: The purpose of this study was to identify 24 hours blood pressure variations among adults over 40 years of age. Method: The participants(50 adults) were recruited from P hospital and B company. The participants were divided into normotensive and hypertensive tendency groups and then sub-divided into non-dipper, dipper, and extreme dipper. The data were collected from April, 2003 to September, 2004 and analyzed using SPSS for Window program. Results: 1) There were significant differences in cardiovascular risk factor, systolic and diastolic blood pressures, and LDH, diet between the normotensive and hypertensive tendency groups. 2) Dippers in both groups showed a marked decrease in blood pressure during the night, but non-dippers in both groups didn't show a marked nocturnal decrease in blood pressure. 3) There were significant differences in heart rate, WHR, BMI, LDH, triglyceride, glucose, affective-oriented coping strategies between dippers and non-dippers. 4) There were significant differences in heart rate, WHR, BMI, LDH, triglyceride, affective-oriented coping strategies between dipper and non-dipper within hypertensive tendency group. Conclusion: Further studies are needed to provide effective intervention in hypertension when applying 24 hour blood pressure monitoring.

  • PDF

Regenerating Condition Optimization of NGCC Combined Carbon Capture Process Simultaneously Considering Absorption and Regeneration Rates (흡수율과 재생율을 동시 고려한 천연가스복합발전 공정 연계 이산화탄소 포집 공정의 재생 조건 최적화)

  • Jeong Hun Choi;Young-Hwan Chu
    • Korean Chemical Engineering Research
    • /
    • v.61 no.3
    • /
    • pp.368-377
    • /
    • 2023
  • Natural Gas Combined Cycle(NGCC) recently receives lots of attention as an attractive form of power plants by virtue of its low carbon emission compared with coal-fired power plant. Nevertheless, it also needs carbon capture process since it is difficult to completely suppress carbon emission even for the NGCC. A simulation study has been performed to optimize operating condition of a carbon capture process using MEA considering low partial pressure of carbon dioxide in NGCC emission gas. For accurate optimization, overall process model including both NGCC and the carbon capture process has been built with a simulation software. Then, optimization in which various performance indices such as carbon dioxide absorption rate, solvent regeneration rate and power loss in the NGCC are simultaneously reflected has been done. Especially, it is noticeable that this study focuses on not only the amount of energy consumption but also the absorption and regeneration performance of carbon capture process. The best result considering all the performance indices has been achieved when the reboiler temperature is 120 ℃ and the reason has been analyzed.

The Influence of Excluding No-load Cost from SMP on Cost Reduction Incentive of Generators (계통한계가격(SMP)에서 무부하비용 제외가 발전사 비용절감 유인에 미치는 영향)

  • Kim, Myung Yun;Cho, Sung Bong
    • Environmental and Resource Economics Review
    • /
    • v.23 no.4
    • /
    • pp.617-641
    • /
    • 2014
  • Korean electricity market is a Cost-Based Pool (CBP) designed to minimize electricity production cost through cost by providing cost reduction incentives to generators. Generation companies have shown diverse efforts to reduce costs in CBP market such as procuring low-price fuels, installing high efficiency gas turbine and constructing power plants near the heavy-load site. Recently, as a way to improve CBP market, a proposal to exclude no-load cost from System Marginal Price (SMP) and to compensate generators ex post was suggested to Korea Power Exchange. This study analyzes the impact of excluding no-load cost from SMP on the cost reduction incentive of generators. We found that excluding no-load cost from SMP enhances the likelihood of decreasing the cost reduction incentives of LNG combined-cycle generators lying on the price-setting range.

Economic Feasibility Study of the Life Extension by Reactor Type of Nuclear Power Plant in Korea (우리나라 원자력발전의 노형을 고려한 계속운전의 경제성 비교 연구)

  • Cho, Sungjin;Kim, Yoon Kyung
    • Environmental and Resource Economics Review
    • /
    • v.27 no.2
    • /
    • pp.261-286
    • /
    • 2018
  • This paper evaluated the economic feasibility of the life extension of Kori unit 1 and Wolsong unit 1 according to the types of the nuclear power plants (NPPs) and the life extension period comparing to the levelized costs of energy (LCOE) of the new NPPs, coal-fired plants (CFPs), and combined cycle gas turbine (CCGTs) which proposed in the $7^{th}$ Basic Plan for Electricity Supply and Demand. The economic feasibility of the life extension of NPPs using LCOE method is affected by the types of NPPs, lifetime extension periods, discount rate, and capacity factor. According to the analysis results, the pressurized light water reactor (PWR) is more economical than the pressurized heavy water reactor (PHWR). Comparing the economical efficiency between the life extension of NPPs and other alternatives, the operation of the PWR for 20 years is more economical than the one of new NPPs and CFPs. However, 20 years of life extension of PHWR is more economical than the CCGTs, but less economical than new NPPs and CFPs. In summary, the 20 years of life extension of the NPPs seems to be more, especially for the PWR, which is more cost effective than other generation alternatives. Therefore, the government policy of the life extension of NPPs need to be a selective approach that simultaneously considers both safety and economics rather than closing all NPPs.

Study on the Radial Diffuser of Multistage High Pressure Pump (고압 다단 펌프의 레이디얼 디퓨저에 대한 연구)

  • Kim, Deok Su;Mamatov, Sanjar;Park, Warn Gyu
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.40 no.11
    • /
    • pp.727-736
    • /
    • 2016
  • In this study, a high-pressure multistage pump used in the combined cycle power plants is analyzed. The pump performance characteristics (differential head and efficiency) are numerically analyzed for different shapes of the radial diffuser. The design variables selected for the radial diffuser are, number of vanes, diameter ratio ($D_4/D_3$), return channel outlet angle(${\alpha}_6$), and pressure recovery factor ($C_p$). The numerical analysis results showed that the differential head and efficiency are the highest when the diameter ratio is the highest. Further, it was observed that the differential head was lower when the return channel outlet angle was $60^{\circ}$ than when it was $90^{\circ}$, because of pre-swirl at the diffuser outlet.

Comparison of Quench Methods in The Coal Gasification System with Carbon Capture (CO2 포집을 포함한 석탄 가스화 시스템에서 급냉 방법에 따른 비교)

  • Lee, Joong-Won;Kim, Ui-Sik;Ko, Kyung-Ho;Chung, Jae-Hwa;Hong, Jin-Pyo
    • Transactions of the Korean hydrogen and new energy society
    • /
    • v.23 no.3
    • /
    • pp.285-292
    • /
    • 2012
  • The integrated gasification combined cycle (IGCC) system is well known for its high efficiency compared with that of other coal fueled power generation system. IGCC offers substantial advantages over pulverized coal combustion when carbon capture and storage (CCS) is required. Commercial plants employ different types of quenching system to meet the purpose of the system. Depending on that, the downstream units of IGCC can be modeled using different operating conditions and units. In case with $CO_2$ separation and capture, the gasifier product must be converted to hydrogen-rich syngas using Water Gas Shift (WGS) reaction. In most WGS processes, the water gas shift reactor is the biggest and heaviest component because the reaction is relatively slow compared to the other reactions and is inhibited at higher temperatures by thermodynamics. In this study, tehchno-econimic assessments were found according to the quench types and operating conditions in the WGS system. These results can improve the efficiency and reduce the cost of coal gasification.

Hydraulic and Numerical Model Experiments of Flows in Circulation-Water-Pump Chambers (순환수취수펌프장 내의 흐름에 대한 수리 및 수치모형실험)

  • Yi, Yong-Kon;Cheong, Sang-Hwa;Kim, Chang-Wan
    • Journal of Korea Water Resources Association
    • /
    • v.38 no.8 s.157
    • /
    • pp.631-643
    • /
    • 2005
  • The objective of this study is to perform hydraulic and numerical model experiments of the flows in circulation-water-pump(CWP) chambers of combined cycle power plants (CCPP) to be built and to suggest improvement plans if the flows might cause a serious problem on the operation of CWPs. Hydraulic model was constructed in a scale of 1 to 20 using acrylic sheets and a two dimensional numerical model used was RMA2. To evaluate results of Hydraulic and numerical model experiments, evaluation criteria of flow conditions in the intake canal and CWP chambers were determined. Vertical vorticities obtained from numerical simulations for the initial plan of CCPPs were qualitatively compared with results of hydraulic model experiments and the formation possibility of a large scale vortex, one of the flow evaluation criteria, was evaluated. The initial plan was found not to satisfy the flow evaluation. Nine improvement plans were devised and numerically simulated. Four alternative plans among nine improvement plans were selected and hydraulically experimented. On the ground of the results of hydraulic model experiments, a final improvement plan, one of four improvement plants, was suggested. When CWP chambers and intake canals were designed with spatial constraints, flow separating wall and guide walls were found to improve flow conditions in CWP chambers.

Predictive Factors of Health promotion behaviors of Industrial Shift Workers (산업장 교대근무 근로자의 건강증진행위 예측요인)

  • Kim, Young-Mi
    • Korean Journal of Occupational Health Nursing
    • /
    • v.11 no.1
    • /
    • pp.13-30
    • /
    • 2002
  • Industrial shift workers feels suffer mental stresses which are caused by unfamiliar day sleep, noisy environment, sleeping disorder by bright light, unusual contacts with family, difficulty in meeting with friends or having formal social meetings and other social limitations such as the use of transportation. Such stresses influence health of the workers negatively. Thus the health promotion policy for shift workers should be made considering the workers' ways of living and shift work specially. This study attempted to provide basic information for development of the health promotion program for industrial shift workers by examining predictive factors influencing health promotion behaviors of those workers. In designing the study, three power generation plants located in Pusan and south Kyungsang province were randomly selected and therefrom 280 workers at central control, boiler and turbine rooms and environmental chemistry parts whose processes require shift works were sampled as subjects of the study. Data were collected two times from September 17 to October 8, 1999 using questionnaires with helps of safety and health managers of the plants. The questionnaires were distributed through mails or direct visits. Means for the study included the measurement tool of health promotion behavior provided by Park(1995), the tool of self-efficacy measurement by Suh(1995), the tool of internal locus of control measurement by Oh(1987), the measurement tool of perceived health state by Park(1995) and the tool of social support measurement by Paek(1995). The collected data were analyzed using SPSS program. Controlling factors of the subjects were evaluated in terms of frequency and percentage ratio Perceived factors and health promotion behaviors of the subjects were done so in terms of mean and standard deviation, and average mark and standard deviation, respectively. Relations between controlling and perceived factors were analyzed using t-test and ANOVA and those between perceived factors and the performance of health promotion behaviors, using Pearson's Correlation Coefficient. The performance of health promotion behaviors was tested using t-test, ANOVA and post multi-comparison (Scheffe test). Predictive factors of health promotion behavior were examined through the Stepwise Multiple Regression Analysis. Results of the study are summarized as follows. 1. The performance of health promotion behaviors by the subjects was evaluated as having the value of mean, $161.27{\pm}26.73$ points(min.:60, max.:240) and average mark, $2.68{\pm}0.44$ points(min.:1, max.:4). When the performance was analyzed according to related aspects, it showed the highest level in harmonious relation with average mark, $3.15{\pm}.56$ points, followed by hygienic life($3.03{\pm}.55$), self-realization ($2.84{\pm}.55$), emotional support($2.73{\pm}.61$), regular meals($2.71{\pm}.76$), self-control($2.62{\pm}.63$), health diet($2.62{\pm}.56$), rest and sleep($2.60{\pm}.59$), exercise and activity($2.53{\pm}.57$), diet control($2.52{\pm}.56$) and special health management($2.06{\pm}.65$). 2. In relations between perceived factors of the subjects(self-efficacy, internal locus of control, perceived health state) and the performance of health promotion behaviors, the performance was found having significantly pure relations with self-efficacy (r=.524, P=.000), internal locus of control (r=.225, P=.000) and perceived health state(r=.244, P=.000). The higher each evaluated point of the three factors was, the higher the performance was in level. 3. When relations between the controlling factors(demography-based social, health-related, job-related and human relations characteristics) and the performance of health promotion behaviors were analyzed, the performance showed significant differences according to marital status (t=2.09, P= .03), religion(F=3.93, P= .00) and participation in religious activities (F=8.10, P= .00) out of demography-based characteristics, medical examination results (F=7.20, P= .00) and methods of the collection of health knowledge and information(F=3.41, P= .01) and methods of desired health education(F=3.41, P= .01) out of health-related characteristics, detrimental factors perception(F=4.49, P= .01) and job satisfaction(F=8.41, P= .00) out of job-related characteristics and social support(F=14.69, P= .00) out of human relations characteristics. 4. The factor which is a variable predicting best the performance of health promotion behaviors by the subjects was the self-efficacy accounting for 27.4% of the prediction, followed by participation in religious activities, social support, job satisfaction, received health state and internal locus of control in order all of which totally account for 41.0%. In conclusion, the predictive factor which most influence the performance of health promotion behaviors by shift workers was self-efficacy. To promote the sense, therefore, it is necessary to develop the nursing intervention program considering predictive factors as variables identified in this study. Further industrial nurses should play their roles actively to help shift workers increase their capability of self-management of health.

  • PDF

A Study on Comparative Analysis of Socio-economic Impact Assessment Methods on Climate Change and Necessity of Application for Water Management (기후변화 대응을 위한 발전소 온배수 활용 양식업 경제성 분석)

  • Lee, Sangsin;Kim, Shang Moon;Um, Gi Jeung
    • Journal of Korean Society of societal Security
    • /
    • v.4 no.2
    • /
    • pp.73-78
    • /
    • 2011
  • In order to resolve the problem of change in global climate which is worsening as days go by and to preemptively cope with strengthened restriction on carbon emission, the government enacted 'Framework Act on Low Carbon Green Growth' in 2010 and selected green technology and green industry as new national growth engines. For this reason, the necessity to use the un-utilized waste heat across the whole industrial system has become an issue, and studies on and applications of recycling in the agricultural and fishery fields such as cultivation of tropical crops and flatfishes by utilizing the waste heat and thermal effluent generated by large industrial complexes including power plants are being actively carried out. In this study, we looked into the domestic and overseas examples of having utilized waste heat abandoned in the form of power plant thermal effluent, and carried out economic efficiency evaluation of sturgeon aquaculture utilizing thermal effluent of Yeongwol LNG Combined Cycle Power Plant in Gangwon-do. In this analysis, we analyzed the economic efficiency of a model business plan divided into three steps, starting from a small scale in order to minimize the investment risk and financial burden, which is then gradually expanded. The business operation period was assumed to be 10 years (2012~2021), and the NVP (Net Present Value) and economic efficiency (B/C) for the operation period (10 years) were estimated for different loan size by dividing the size of external loan by stage into 80% and 40% based on the basic statistics secured through a site survey. Through the result of analysis, we can see that reducing the size of the external loan is an important factor in securing greater economic efficiency as, while the B/C is 1.79 in the case the external loan is 80% of the total investment, it is presumed to be improved to 1.81 when the loan is 40%. As the findings of this study showed that the economic efficiency of sturgeon aquaculture utilizing thermal effluent of power plant can be secured, it is presumed that regional development project items with high added value can be derived though this, and, in addition, this study will greatly contribute to reinforcement of the capability of local governments to cope with climate change.

  • PDF