• 대한기계학회논문집B
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• 제41권5호
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• pp.353-363
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• 2017

부하변동과 외란에 따른 관류보일러 물-증기 계통의 동적 거동을 물리적 모델링 접근방법으로 모사하였다. 본 논문에서는 수관의 질량, 에너지와 운동량 방정식을 고려한 아임계 영역의 동적 모사를 보고한다. 500MWe 급의 절탄기, 증발기와 과열기로 이루어진 단순한 보일러 시스템을 가정하였고, 증발기 모델링은 참고문헌 데이터와 검증을 진행 하였다. 이 시스템에 대하여 외란에 따른 정량적 응답특성을 살펴보았다. 또한, 수연비(증기량과 연료의 유량비)가 설계조건과 크게 다른 탈 설계 운전 사례에 대한 보일러 시스템의 동적 응답평가를 진행 하였다. 그 결과를 통해 적절한 수연비의 제어와 재순환 시스템과 분무 감온기 설계의 중요성이 재확인 되었다.

• 대한기계학회논문집B
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• 제24권7호
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• pp.967-975
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• 2000

Transient characteristics of a boiler and turbine system for a steam power plant are simulated. One-dimensional unsteady models are introduced for each component. An interaction between boiler and turbine and a control of the water level in the drum are taken into account. Transient responses of the system to the variations of main system variables such as fuel and air flow rate, cooling water injection rate at the attemperator, gas recirculation rate at the furnace and opening of the turbine control valve are examined. Effect of fluid inertia and tube wall thermal inertia on predicted dynamic behavior is investigated.

• 한국기계가공학회지
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• 제21권2호
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• pp.94-100
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• 2022

A study was conducted to significantly increase the heat transfer area by simultaneously burying the excel pipe in the floor and wall of a container house, thereby greatly reducing the initial heating time. In addition, a small hot water boiler suitable for the heating load of a small container house with a maximum area of 6 m² was studied. A wall-mounted hot water boiler was developed as a result of the study. When a hot water boiler is installed outdoors for heating, heat radiation energy is lost in winter from the hot water boiler and hot water pipe due to the low temperature. We propose an approach through which the energy loss was greatly reduced and the temperature of hot water increased in proportion to the operating time. Moreover, as the mass flow rate of the hot water flowing inside the excel pipe increased, the temperature of the hot water decreased. The temperature of the wall and floor surfaces of the container house increased in proportion to the increase in the mass flow rate of hot water flowing inside the excel tube. Natural convection heat transfer was realized from the wall and floor surfaces of the container house, and the heat transfer area was increased by a factor of 3 with respect to heat transfer area limited to the floor by the existing hot water panel. As a result, the initial temperature increase rate was much higher because of the larger heat transfer area.

• 태양에너지
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• 제17권4호
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• pp.57-66
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• 1997

The performance of gas-fired boilers were experimentally investigated. The heat exchanger used for the experiments consisted of circular tube with longitudinal fins for the gas side and a spiral coil for the water side. The burner was located at the top of the heat exchanger, and the burned gas flowed down to the exit. The experiments carried out for different water flow rates, the heat capacities of the boiler and the number of baffle. The thermal efficiency of the upward flow was higher than that of the downward flow of the water in the heat exchanger. As the boiler capacity increased, the thermal efficiency decreased. As the number of the baffles increase, the thermal efficiency increased and the increasing rate of the efficiency decreased. The gas-side overall heat transfer coefficient was independent of the flow rate of the water. The effect of the number of the baffles on the heat transfer coefficient was greater than that of the boiler capacity.

• 에너지공학
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• 제22권3호
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• pp.287-293
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• 2013

이 논문은 보일러 운전중에 일어나는 결함요소의 하나인 스케일형성을 감소하기 위한 연구이다. 스케일의 결함은 보일러 튜브의 과열로 보일러 파열에 치명적인 영향을 미치거나, 보일러내부의 수의 순환 불량으로 내부의 물흐름에 영향을 미쳐 내부의 수의 불균등을 가져오기도 한다. 그리고 스케일은 보일러 재료보다 열전달이 되지 않음에 따른 에너지손실도 가져와 지구 온난화의 환경에 영향을 끼친다. 이러한 스케일의 형성을 방지하거나 제거하기 위하여 한국정부에서는 보일러수질관리를 위하여 2005년도에 스케일부착을 방지하거나 제거할 수 있는 장치를 시설하도록 하였다. 이러한 스케일형성 방지 및 제거하기 위한 기법에 관한 연구는 1821년 감자 전분에 의한 스케일형성 감소에 의한 연구를 시작으로 그 후 많은 연구가 있어왔다. 1994년 한국에 러시아 음향연구소의 한 과학자로부터 개발된 초음파 스케일 방지장치가 소개된 이래로 다양한 보일러에 보급되기 시작했다. 초음파 스케일방지 장치가 성능을 발휘할 수 있는 조건을 실증할 필요가 있다. 보일러는 대부분 원형 곡면의 본체와 튜브로 구성 되어 있다. 보일러의 구성 요소 중 스케일결함 가장영향을 많이 미치는 원통형에 대한 실증을 실시하였다. 그 결과 초음파의 일정음압과 주파수에 도달하여야 스케일형성에 영향을 미친다는 것을 확인할 수 있었다.

• 설비공학논문집
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• 제30권2호
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• pp.68-82
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• 2018

Radiant floor heating systems with capillary tubes are energy saving systems in which hot water is circulated into capillary tube with a small diameter. In this study, the heating performance of capillary tube system is investigated in an experimental study and a simulation model. The results of the study showed that, the capillary tube radiant floor heating system maintains a more stable floor surface temperature in comparison a PB pipe system. In terms of energy consumption, the capillary tube radiant floor heating system proved to be more efficient than the PB pipe heating system at $40^{\circ}C$ of low temperature hot water supply. The difference between water temperature and room temperature can be held low for heating which saves energy. Low temperature radiant floor heating system with capillary tubes have significant advantages such as health improvement, low energy cost, optimum use of heat source(boiler) and higher operational efficiency.

• KEPCO Journal on Electric Power and Energy
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• 제4권1호
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• pp.25-31
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• 2018

A boiler system transforms water to pressured supercritical steam which drives the running of the turbine to rotate in the generator to produce electricity in power plants. Materials for building the tube system face challenges from high temperature creep damage, thermal fatigue/expansion, fireside and steam corrosion, etc. A database on the creep resistance strength and steam oxidation of the materials is important to the long-term reliable operation of the boiler system. Generally, the ferritic steels, i.e., grade 1, grade 2, grade 9, and X20, are extensively used as the superheater (SH) and reheater (RH) in supercritical (SC) and ultra supercritcal (USC) power plants. Currently, advanced austenitic steel, such as TP347H (FG), Super304H and HR3C, are beginning to replace the traditional ferritic steels as they allow an increase in steam temperature to meet the demands for increased plant efficiency. The purpose of this paper is to provide the state-of-the-art knowledge on boiler tube materials, including the strengthening, metallurgy, property/microstructural degradation, oxidation, and oxidation property improvement and then describe the modern microstructural characterization methods to assess and control the properties of these alloys. The paper covers the limited experience and experiment results with the alloys and presents important information on microstructural strengthening, degradation, and oxidation mechanisms.

• 수산해양교육연구
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• 제6권1호
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• pp.58-76
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• 1994

Heat transfer and pressure drop measurements are made on low integral-fin tubes in turbulent water flow condition. The integral-fin tubes investigated in this paper are nominally 19mm in diameter. Eight tubes have been used with trapezoidally shaped integral-fins having fin density from 748 to 1654 fpm and 10, 30 grooves. Plain tube having same diameter as finned tube is also tested for comparison. Experiments are carried out using R-11 as working fluid. The refrigerant condensates at a saturation state of $30^{\circ}C$ on the outside tube surface cooled by coolant. The amount of noncondensable gases present in the test loop is reduced to a negligible value by repeated purging. For a given heat input to the boiler and given cooling water flow rate, all test data are taken on steady state. The heat transfer loop is used for testing single long tubes and cooling water is pumped from a storage tank through filters and flowmeters to the horizontal test section where it is heated by steam condensing on the outside of the tube. The pressure drop across the test section is measured by means of pressure gauge and manometer. Each tube tested is cleaned with sodium dichromate pickling solution and well rinsed with water prior to installation in the test section. The results obtained in this study is as follows : 1. Based on inside diameter and nominal inside area, heat transfer of finned tube is enhanced up to 4 times as that of a plain tube at constant Reynolds number and up to 2 times at constant pumping power. 2. Friction factors are up to 1.6~2.1 times those of plain tube. 3. At a given Reynolds number, Nusselt number decrease with increasing pitch to diameter. 4. The constant pumping power ratio for low integral-fin tubes increase directly with the effective area to the nominal area ratio, and with the effective area diameter ratio.

• 대한전기학회논문지:전력기술부문A
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• 제48권1호
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• pp.44-51
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• 1999

This paper proposes a new approach of plant fault diagnosis which is based on detecting the characteristic pattern signals and associating them with the corresponding faults. The new approach does not require analytic modeling of the target system but best reflects the expertise embedded in the experienced human operation by mimicking them in a systematic way. This paper intends to illustrate the feasibility of the proposed by developing the algorithms to detect and estimate the typical characteristic pattern signals, I. e., oscillatory patterns, and applying them to the diagnosis of various faults of a 500MW boiler control system including tube rupture, feed-water leak, and controller failure.

• KEPCO Journal on Electric Power and Energy
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• 제2권3호
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• pp.403-407
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• 2016

In general, drum-type boilers are designed for base load duty and applied under constant pressure operation mode. Recently, however conditions often occur that even drum-type boilers have to operate at partial load conditions. A feasibility study on adopting the sliding pressure operation for drum-type boiler was conducted, and corresponding performance changes and effects on the equipment were analyzed by utilizing a process simulation model. As a result, the conclusion was reached that drum type boilers are able to adopt the sliding pressure operation and can improve of net efficiency at part load operation in spite of the Rankine cycle efficiency reduction due to the decreases in main steam pressure. Because of thank to improvement of high pressure turbine stage-1 internal efficiency and power savings of boiler feed water pump. The sliding pressure operation is advantageous in terms of stress level relief for boiler tube as well as maintaining the rating steam temperature at part load condition. However, cautions are required because the drum boilers have poor dynamic response characteristics which may get worse during the sliding pressure operation.