• 대한전기학회논문지
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• 제40권1호
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• pp.120-127
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• 1991

The purpose of this study is to develop a fault detection and diagnosis scheme that can monitor process fault and instrument fault of a steam generator. The suggested scheme consists of a Kalman filter and two bias estimators. Method of detecting process and instrument fault in a steam generator uses the mean test on the residual sequence of Kalman filter, designed for the unfailed system, to make a fault decision. Once a fault is detected, two bias estimators are driven to estimate the fault and to discriminate process fault and instrument fault. In case of process fault, the fault diagnosis of outlet temperature, feed-water heater and main steam control value is considered. In instrument fault, the fault diagnosis of steam genrator's three instruments is considered. Computer simulation tests show that on-line prompt fault detection and diagnosis can be performed very successfully.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.1397-1405
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• 2009

In recent decades, exergy analysis has been holding spotlight as a useful tool in the design, assessment, optimization, and improvement of energy system. This paper presents the results of the energy and exergy analysis of a steam turbine cogeneration system for industrial complex using two efficiency concepts of conventional one and exergetic one. In order to obtain the destroyed exergy of each component, mathematical analysis is conducted by using exergy balance and the second law of thermodynamics, according as the parameters are changed, such as the ratio of returned process steam, process steam supplied, temperature and pressure of boiler and power. The computer program developed in this study can determine the efficiencies and exergy destroyed at each component of cogeneration system. As a result of this study, a component having the largest destroyed exergy was boiler. And closed and opened feedwater heater had the lowest one. The affects to the cogeneration system due to the variation of process steam flow and return rate of condensed water is shown that the total electric power efficiency(${\eta}_E$) is decreased as increasing the return rate of condensed water under constant process steam flow. As the boiler pressure is increased for the more production of electricity, the efficiency of cogeneration system was decreased.

• 한국추진공학회지
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• 제2권2호
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• pp.74-82
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• 1998

복합발전 사이클은 가스터빈이나 스팀터빈으로부터의 출력을 이용하여 전개를 생산하기 위한 발전기를 구동시키고 배영회수기로부터 나온 증기를 스틸터빈에서 팽창시킴으로서 부가적인 동력을 얻는 장치를 가리킨다. 보통 가스터빈 배기로 부터의 온도는 $400{\sim}650^{\circ}C$정도로서 배열회수기에서 효과적으로 스팀을 생산할 수 있는 수준의 온도이다. 복합 사이클은 일반적으로 상부사이클과 하부사이클로 구분하는데 대부분의 열에너지 공급이 이루어지는 상부사이클을 브레이돈사이클 이라하며 브레이돈사이클에서 소비되는 에너지는 보다 낮은 온도 수준인 하부사이클에서 회수된다. 이러한 복합사이클은 최근 들어 더욱 보편적으로 적용되고 있는데 그 이유는 첫째, 가스터빈이나 스팀터빈이 독자적으로도 충분히 기술적인 검증을 받은 열기관으로서 초기에 비해 개발비가 저렴해졌다는 데 있고, 둘째, 작동유체인 공기가 $1000^{\circ}C$ 이상에서도 별다른 문제없이 적용될 수 있는 안전한 유체이고 비용이 전혀 들지 않는다는 점이다. 그 뿐 아니라 스팀터빈에 사용되는 물도 중저온에서 매우 저가로 공급할 수 있고 쉽게 공급이 가능하다는 이점으로 하부사이클에의 적용이 매우 양호하다는 점이다. 최근 소재기술의 개발에 따른 터빈입구온도의 향상은 이러한 복합발전 사이클의 기술적, 경제적 이점을 더욱 강화시켜 주고 있다. 본 연구에서는 3압에 의한 복합사이클에 대한 성능해석을 통하여 상부사이클이 전체 복합발전 성능에 미치는 영향을 조사하였으며 그 결과를 서인천 복합발전 인수 성능시험결과와 비교하였다. 본 연구결과는 현재 개념설계가 이루어지고 있는 장차 150~200MW수준의 산업용 가스터빈 개발에 중요한 방향제시를 할 수 있을 것으로 판단된다.

• 한국기계가공학회지
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• 제20권4호
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• pp.94-105
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• 2021

A graphical user interface (GUI) program for steam tracing system selection was developed by using a theoretical model. We derived the model on the basis of the one-dimensional heat transfer theory of conduction and convection through a composite wall. Computational fluid dynamics (CFD) and experiments were performed for validation at steam temperatures of 120.4[℃] and 158.9[℃]. The temperature of a pipe's outer surface obtained through CFD matched well with that predicted by the proposed model for both conditions. By contrast, the experiment results showed a small error at 120.4[℃] and a large error at 158.9[℃] because of the melting of the heat transfer compound and water phase transition. Thus, the steam temperature range of the proposed model is below 120.4[℃].

• International Journal of Fluid Machinery and Systems
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• 제9권1호
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• pp.85-94
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• 2016

An experimental study is conducted for unsteady wet steam flow in a four-stage low-pressure test steam turbine. The measurements are carried out at outlets of the last two stages by using a newly developed fast response aerodynamic probe. This FRAP-HTH probe (Fast Response Aerodynamic Probe - High Temperature Heated) has a miniature high-power cartridge heater with an active control system to heat the probe tip, allowing it to be applied to wet steam measurements. The phase-locked average results obtained with a sampling frequency of 200 kHz clarify the flow characteristics, such as the blade wakes and secondary vortexes, downstream from the individual rotational blades in the wet steam environment.

• 한국압력기기공학회 논문집
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• 제5권1호
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• pp.1-8
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• 2009

본 논문에서는 국제적으로 개발 중인 초고온가스로와 연계하여 대량의 수소를 생산하기 위한 방안의 일환으로 국내에서 개발 중인 고온증기전기분해 시스템에 사용될 열교환기 재료의 고온증기 부식실험에 대해 소개하였다. 이를 위해 관련된 국내외 연구현황을 조사분석한 결과를 요약하여 소개하였으며 마지막으로 현재 수행중인 고온증기부식 연구의 실험조건 및 계획을 제시하였다. 실험 및 연구결과는 초고온가스로와 연계된 고온전기분해를 이용한 수소생산시스템의 개발에 활용될 예정이다.

• 한국유체기계학회 논문집
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• 제18권6호
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• pp.19-26
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• 2015

The present paper presented and applied an exergy analysis method to evaluate the magnitudes and the locations of exergy losses in the conventional desuperheating and depressurizing process of high pressure and temperature steam delivery system. In addition, for the reduction of exergy losses occurred in conventional process, the present study proposed new alternative processes in which the pressure reducing valve and the desuperheater of conventional process are substituted with steam turbine and heat exchanger, and their effects on exergy loss reduction and exergy efficiency improvement are theoretically investigated and compared. From the present analysis results, the total exergy loss caused in conventional desuperheating and depressurizing process accounted for 66.5% of exergy input and 85% of the total exergy loss was due to the mixing between steam and cold water(e.g desuperheating). However, it was shown from the present analysis results that the present alternative processes can additionally reduce exergy loss by maximum 92.7% of the total exergy loss in conventional process, and can also produce additional and useful energy, the electricity of 220.6 kWh and the heat of 54.3 MJ/hr.

• 설비공학논문집
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• 제30권2호
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• pp.100-106
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• 2018

Recently, the development of a heat pump technology to recover process waste heat and to generate steam of $120^{\circ}C$ or higher required for industrial processes, has attracted attention. The research of conventional heat pump utilizing the available energy is used primarily for air conditioning, and the production temperature is about $60^{\circ}C$, so it is difficult to utilize it for industrial use. Therefore, in this study, we developed a steam heat pump (SGHP) which recovers the waste heat of process and generates steam at $120^{\circ}C$. The low-pressure refrigerant R245fa, considered to be an eco-friendly refrigerant, has been selected as the refrigerant for SGHP in this study since its Ozone Depletion Potential (ODP) is zero and the Global Warming Potential (GWP) is relatively low. A flash tank functioning as a phase separator was installed in the rear stage of the condenser, and the saturated water of high temperature was decompressed to generate steam. It was started at the initial temperature of $70^{\circ}C$, and it was confirmed that $120^{\circ}C$ steam was produced after the system stabilized. We have conducted experiments by modifying the system, and ultimately achieved a heating capacity of 101.4 kW and a COP of 3.05.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.441-444
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• 2006

Extrusion molding concrete panel is cured two times, that is the steam curing at atmospheric pressure and a high-pressure steam curing(autoclaving). Steam curing at atmospheric pressure is done before autoclaving and to acquire the proper strength for treat in process. Though this curing is the important factor on the quality of product and the speed in manufacturing process, it was not evaluated properly so far. Because of ignorance about curing, some engineers even think that the dry curing is better than the steam curing. This study is to investigate the properties of specimen according to variation of curing conditions in the coring chamber such as laboratory scale, pilot plant, and commercial plant. As estimating, in case of steam curing at atmospheric pressure to make extrusion molding concrete panel, moisture curing is better than dry curing and the desirable maximum temperature in curing chamber is about $50^{\circ}C$.

• 한국기계가공학회지
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• 제17권4호
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• pp.23-31
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• 2018

Stress of a steam separator, equipment of the high-pressure (HP) evaporator for a HRSG, was analyzed and evaluated according to ASME Boiler & Pressure Vessel Code Section VIII Division 2. First, from the analysis results of the piping system model of the HP evaporator, reaction forces of the riser tubes connected to the steam separator, i.e., nozzle loads, were derived. Next, a finite element model of the steam separator was constructed and analyzed for the design pressure and the nozzle loads. The results show that the maximum stress occurred at the bore of the riser nozzle. The primary membrane stresses at the shell and nozzle were found to be less than the allowable stress. Next, the steam separator was analyzed for the steady-state operating conditions of operating pressure, operating temperature, and nozzle loads. The maximum stress occurred at the bore of the riser nozzle. The primary plus secondary membrane plus bending stress at the shell and nozzle was found to be less than the allowable stress.