• Corrosion Science and Technology
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• 제20권5호
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• pp.242-248
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• 2021

Unforeseen failures of boilers in power plants may affect the continuation of electricity generation. Main failures in boilers are influenced by the tube material, tube position, boiler service temperature and pressure, and chemical composition of the feed water and coal. This investigation was intended to find answers on the causes and mechanism of failure of the fire-side boiler water-wall tubes, due to perforation and corrosion. The tube conformed to the material requirements in terms of its chemical composition and hardness. Microscopic examination showed ferrite and pearlite indicating no changes in its microstructure due to the temperature variation. SEM test showed a single layer and homogenous film density particularly on the area far from perforation. However, layers of corrosion product were formed on the nearby perforation area. EDX showed that there were Na, Ca, S, and O elements on the failed surface. XRD indicated the presence of Fe₂O₃ oxide. The failure mechanism was identified as a result of significant localized wall thinning of the boiler water wall-tube due to oxidation.

• 동력기계공학회지
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• 제7권1호
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• pp.20-24
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• 2003

Boiler is one of the most important utilities providing steam to turbine in order to supply mechanical energy in thermal power plant. It is composed of thousands of tubes for high efficient heat transfer. Water is converted to steam inside the waterwall tubes. Many chemical components dissolved in boiler water come out of itself, deposit to the tube wall surface, prohibit heat transer, raise tube metal temperature, eventually fail the boiler tubes. Several tasks such as fracture surface study, tensile test, hardness test, metallurgical test, composition analysis of sticking elements were conducted to identify the root cause of tube failure.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1146-1151
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• 2005

This paper deals with the control problem of a natural circulation water tube boiler with constraint conditions. Some linearized models for the water tube boiler are proposed around some operating points, and the model based predictive control law is adopted to control the plant accounting for constraints. In this controller, the Kalman filter is used for the state estimation, and the controller is designed based on the linearized model. The control performance of the designed controller is exemplified via some nonlinear simulations around the operation point, which show it works well.

• 사물인터넷융복합논문지
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• 제8권1호
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• pp.23-29
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• 2022

본 연구의 개발대상 제품은 선박 및 발전용 EGB(Exhaust Gas Boiler-폐열보일러) 종류로써 디젤 엔진, 가스 엔진, 가스 터빈 등에서 나오는 배기 가스의 여열을 이용하여 물을 가열하여 고온·고압의 증기나 온수를 발생시키는 열회수 장치이다. 발생된 증기나 온수는 선박의 선실 난방 및 온수 시설이나 HFO Heating, 터빈 구동에 필요한 동력원으로 사용된다. 폐열보일러의 원리는 여열을 가진 고온의 배기 가스가 보일러의 Tube를 통과하면서 물을 데우는 역할을 한다. 데워진 물은 스팀 형태로 선실이나 터빈장치로 보내어져 사용하게 되는 구조이다. 본 연구에서는 EGB의 열전달 부품인 관형 튜브를 Plate Tube로 대체하여 열전달 표면을 늘려 효율을 극대화하는데 목표가 있다.

• 설비공학논문집
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• 제18권12호
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• pp.992-998
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• 2006

This study is to optimize design parameters for waste heat recovery boiler with water tube and three drum. The design optimization considered here is to find the most economic dimension of the boiler considered which results in a minimum cost in producing a unit amount of steam per given period of operation. For this purpose, optimize design have to determine what are the main parameters of affecting the total cost of producing a unit amount of steam which is comprised of manufacturing cost of the boiler, operating cost of the fan etc.

• 설비공학논문집
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• 제24권3호
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• pp.265-270
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• 2012

A finned tube type heat exchange module has been proposed for a multi-burner water tube boiler. Fin density and length increase in streamwise direction to equalize the evaporation for each module, which makes it difficult to apply conventional bulk design procedure. The design program has been improved by updating data for every row of tubes along the flow. A numerical simulation has been also conducted to evaluate the effect of inlet conditions and validated with experiment. The heat transfer of the first row has been underpredicted by the conventional Zhukauskas correlation, since the acceleration of the flow due to the blockage is not fully inflected. The fin tip temperature is also underpredicted by Bessel solution, because of the interaction with neighboring fins.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2007년도 동계학술발표대회 논문집
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• pp.528-533
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• 2007

A finned tube type heat transfer module has been proposed for a multi-burner water tube boiler. Fins change their geometry along the streamwise direction to maximize the performance, which makes it difficult to apply conventional bulk analysis. The design program has been improved by updating data for every row of tubes along the flow. A numerical simulation has been also performed to evaluate the effect of inlet conditions and validated with experiment. The heat transfer of the first row has been underpredicted by the conventional Zhukauskas correlation, where the acceleration of the flow due to the blockage is not fully inflected. The fin tip temperature is also underpredicted by Bessel solution, because of the interaction with neighboring fins.

• KEPCO Journal on Electric Power and Energy
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• 제6권2호
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• pp.145-150
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• 2020

유동층보일러를 구성하는 요소 중 하나인 수냉벽튜브는 외부의 고온 연소 가스를 이용해 물을 증기로 가열하는 튜브군의 하나로써, 보일러를 이용한 전력생산에 중요한 역할을 담당하지만, 고온 가스 및 유동매체로 인해 마모 및 부식이 심하게 일어나면 누수가 발생하게 되고, 누수로 인한 2차 피해도 발생될 뿐만 아니라, 발전 효율이 현저히 떨어지게 되어 수냉벽튜브의 유지보수는 매우 중요하다. 본 연구에서는 원격장 기반의 발신자(Exciter) 센서 설계, 원격장 와전류 시스템 구성, 수냉벽튜브 외벽 결함평가를 목적으로 하였으며, 이를 위한 발신자 형상의 센서 설계를 시작으로, 수냉벽튜브의 크기, 재질, 주파수, Lift-Off (센서와 수냉벽튜브 사이의 거리) 등 여러 가지 요인에 따른 시험을 진행하여 그에 따른 최적의 발신자 센서를 설계하였다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2009년 춘계학술대회논문집
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• pp.335-340
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• 2009

Operating medium or large scale industrial boilers in partial load condition, the burner should undergo the off-design points resulting in poor exhaust gas characteristics. To obtain the stable turn down performance, two or more burners can be used for the industrial boiler. In case multiple burners are adopted, the heat transfer can be enhanced by arranging the burners properly. In the present study, numerical simulations have been conducted for the combustion chamber of a 2 t/h class industrial boiler in order to clarify the heat transfer characteristics at the combustion chamber.

• 한국전산유체공학회지
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• 제14권2호
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• pp.77-83
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• 2009

Operating medium or large scale industrial boilers in partial load condition, the burner should undergo the off-design points resulting in poor exhaust gas characteristics. To obtain the stable turn down performance, two or more burners can be used for the industrial boiler. In case multiple burners are adopted, the heat transfer can be enhanced by arranging the burners properly. In the present study, numerical simulations have been conducted for the combustion chamber of a 2 t/h class industrial boiler in order to clarify the heat transfer characteristics at the combustion chamber.