• Proceedings of the Korea Society for Simulation Conference
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• 1999.10a
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• pp.235-235
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• 1999

화력 발전소의 드럼형 보일러 제어 프로세스에 있어 드럼 수위(Drum Level)의 정확한 측정은 매우 중요하다. 만약 드럼 수위가 불안정하게 되면 급수 유량 제어가 불안정하여 증기 온도 제어를 불안정하게 하고, 증기 온도의 변화는 보일러 출구 증기 압력을 변화시켜 연소 제어 계통을 불안정하게 한다. 결국 드럼 수위의 불안정은 발전소 전체 프로세스를 불안정하게 한다. 또한 드럼 수위의 오지시로 인해 수위가 과도하게 높아져 물이 터빈에 유입되면 터빈 날개의 파손을 가져오고, 반대로 수위가 너무 낮으면 과열로 인한 보일러 튜브의 파열을 초래하기도 한다. 특히, 보일러의 기동시 또는 과도상태일 때는 드럼 압력의 변화에 따른 water 및 steam의 밀도 변화로 인한 오차가 크며, 압력 대 밀도(비중)의 관계가 비선형 함수이므로 별도의 압력검출기에 의해 드럼 압력을 측정하여 압력 변화에 따른 오차를 보정해주어야 하는데 아날로그 시스템의 경우에는 이러한 압력 수위 보정을 기준 압력에 대해서만 하므로 기동시 또는 과도상태에서의 수위 제어에 많은 문제점이 있다. 본고에서는 이러한 보일러 드럼 수위 압력 보정의 유.무에 따라 드럼 수위 변화에 대해 시뮬레이션을 하여 압력 보정이 드럼 수위에 미치는 영향을 고찰하고자 한다.

• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.2163-2165
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• 2001

화력 발전소 드럼수위의 제어는 보일러 시스템의 효율적인 운용을 위해 중요한 위치를 차지하고 있다. 드럼수위의 제어 목적은 드럼수위를 외란에 관계없이 항상 설정치로 유지하는 것이다. 정상 운전중에는 드럼의 중앙이하 부분에는 물이 차 있고, 상부에는 증기가 차 있으나 만일 수위가 너무 높아지면 carry over 현상이 발생하며 반대로 너무 낮으면 드럼 하부의 과열 및 튜브의 손상을 초래하여 대사고를 유발하게 되므로 드럼수위는 항상 정상으로 유지해야 한다. 드럼수위 제어루프는 처음에는 드림수위만을 제어입력으로 취하는 PI 제어기에 의해 이루어지다가, 주증기량이 일정량 이상 유지되면 드럼수위가 일정한 설정치를 유지하도록 급수량, 드럼수위, 주증기량에 의한 PI-PI 캐스케이드 형태의 제어로 절환되어 제어가 이루어진다. 또한 드럼 수위는 차압검출기에 의해서 측정되어지는데, 드럼의 압력에 따라 물과 증기의 밀도가 변하기 때문에 차압검출기에 의한 드럼수위 지시치는 드럼압력에 의한 보상도 요구되어진다. 본 논문에서는 중용량 화력발전소를 대상으로 드럼수위 보상과 드럼수위 제어기를 구현하고, 적용하여 실제 발전출력 증발시의 드럼수위 제어결과를 보임으로서 구현한 드럼수위 제어기의 효용성을 보인다.

• Korean Chemical Engineering Research
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• v.54 no.4
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• pp.479-486
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• 2016

The efficient steam drum should be required to reduce carbon oxide emissions and heat recovery in oxygen converter hood system. However, steam generation is limited to the time of the oxygen blowing period, which is intermittent or cyclical in operation of steel-making process. Thus, steam drum should be optimized for an effective steam generation during the oxygen blowing portion of the converter cycle. In this study, a three-dimensional computational fluid dynamics (CFD) model has been developed to describe the impacts of changing various operating conditions and geometric shape on thermo-fluid characteristics and performance of the steam drum. This model encompasses not only fluid flow and heat transfer but also evaporation and condensation at the interfacial surface in the steam drum by using VOF (Volume of Fluid) method. To validate the prediction performance of this model, comparison of the steam flow rate between numerical and experimental result has been performed, resulting in the accuracy of the relative error by less than 3.2%.

• Journal of computational fluids engineering
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• v.16 no.1
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• pp.67-72
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• 2011

HRSG (Heat Recovery Steam Generator) is a boiler to recover heat from the exhaust gas of an engine and to generate steam for more power generation or process. For the HRSG, water-tube type boiler is commonly adopted to accommodate the working pressure or capacity requirement of the system. The water-tube type boiler has a steam drum to separate steam from the water-steam mixture supplied from the evaporator tube (riser). The drum should be sized properly to separate the steam by the gravity and auxiliary internals, such as a demister, which are installed to filter the steam. To size the steam drum and to estimate the filter efficiency of drum internals, the velocity distribution inside the drum needs to be identified. In the present study, a series of CFD has been conducted to find the velocity distributions inside steam drums for conventional HRSGs and water-tube type industrial boilers. The velocity distributions obtained from the simulation have been normalized and a correlation to predict them has been found. The correlation is applied to the steam drum design by determining a proper position of a demister to show proper separation performance.

• Plant Journal
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• v.11 no.2
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• pp.32-38
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• 2015

This study was conducted on combined cycle power plant consisting of HRSG with integral deaerator type to avoid tube failures of low pressure evaporator tubes. Based on the observation of pH variation at the discharge of boiler feed water pump by continuous pH measurement for a period of time, it was identified that pH of feed water is getting reduced as ammonia is distributed into vapor and liquid depending on the distribution ratio of ammonia in the LP drum after the deaerator. To solve this problem, the counterplan was prepared by reexamination of ammonia injection point and quantity. In conclusion, it was accomplished that 9.2~9.6 is the optimized pH range for boiler feed water by arranging additional piping for ammonia to inject directly to LP drum.

• Proceedings of the KIEE Conference
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• 2005.07d
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• pp.2622-2624
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• 2005

화력발전소 보일러의 급수량은 유출되는 증기량에 맞추어 자동 조절된다. 유출 증기량이 변하는 상황에서도 이에 상응하는 급수량은 실시간으로 조절되어야 한다. 증기량과 급수량에 차이가 있으면 보일러의 보유 수량과 드럼의 수위가 변하게 되므로, '드림수위를 일정하게 유지하는 것'이 급수량제어의 목표라고 할 수 있다. 본 논문은 실제 운용되고 있는 설비를 대상으로 고찰한 내용이며, 급수펌프 구동력으로는 중기터빈을 사용한다. 증기터빈과 급수펌프는 같은 축으로 연결되어있으며, 급수량 조절은 급수펌프의 회전속도를 제어함으로써 이루어진다. 터빈에 사응되는 증기는, 고압과 저압 2종류이며, 저압 증기가 부족한 경우에 고압증기를 사용하는 구성으로 되어있다. 증기 밸브의 유량 특성에는 비선형성을 많이 포함하고 있었다. 이 외에도 급수펌프가 갖는 비선형성을 분석하였으며, 이 특성들을 모두 종합한 '증기터빈 속도제어기 튜닝 곡선'을 제시하였다

• Journal of the Korean Institute of Gas
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• v.2 no.4
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• pp.1-6
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• 1998

In order to increase design efficiency, it is required to design steam boiler pressure parts systematically considering daily start-stop operation and load variation. The objective of this research is to develope an integrated system for increasing design efficiency of boiler pressure parts. The developed system consists of three program modules: (1) flexibility design module for the header stub considering fatigue life, (2) fatigue limit calculation and life evaluation module for the thick-walled boiler pressure part under cyclic operation using TRD301 code, (3) drawing automation module for the header and drum producing design drawings, welding data and bill of materials.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.11 no.4
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• pp.82-91
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• 1997

In this paper, a design method of the boiler-turbine control system in the coal fired power plant is proposed. We need to control electric output and drum pressure and water level in drum to guarantee stable operation and save energy for generating electricity and decrease air pollution in the boiler-turbine system. This boiler-turbine control system is composed of reference model part and model following part. The multivariable boiler-turbine system is separated into 3 SISO(Single Input Single Output) systems applying the concept of relative gain matrix. Each 3 reference models for separated boiler-turbine system are composed of 1st order nominal plant and hysteresis integral control system and they make good dy¬namic response with no overshoot and fast rising time. Each fuzzy controller to follow as close as possible to the response of each reference model is designed. The robustness and the good tracking property can be achieved using 5150 fuzzy controllers when there are modeling errors, disturbances and parameter pertur¬bations. The effectiveness of the proposed design method is verified through simulations.

• Journal of the Korean Society of Industry Convergence
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• v.7 no.1
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• pp.69-82
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• 2004

Recently, in the food, paper, steel and plastic industries, plate or sheet type products have been produced by the rolling drum. Steam heating drums are introduced into plastic products facilities in order to keep the density, microstructure, and strength of material uniformly. The drum journal can not help being concentrated by stresses due to the bending and torsion. Especially the drum, heated by high pressure steam, might be exposed in the steam leakage accident. First of all, the stresses on the steam drum journal are to be analyzed, and a case study proper to the subject was performed with a scraped journal, in order to investigate the failure characteristics as well as the initiation and propagation of fatigue cracks, and most probable circumstances of crack initiation. As the result of this study, it is suggested that newly installed drum journal be thoroughly inspected at the next periodic maintenance intervals for evidence of cracking, the microstructure examination and hardness measurements to prevent steam drum from the failure accident.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2082-2087
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• 2008

The heat transfer process from steam to web through the cylinder drum consists of the thermal resistance by condensate thickness. thickness of shell, and the contact resistance between cylinder and web. The most thermal resistance in conventional cylinder drum dryer is generated by condensate, which is increased by the increase on revolution per minute(RPM). Therefore, the increase of RPM for the production enhancement results in the more thermal resistance, and eventually RPM is restricted. In this study, the theoretical analysis on the characteristics of heat transfer in cylinder drum for paper dryer was performed in the stationary state of steam in drum. The overall heat transfer coefficient, steam quantity and heat transfer quantity were predicted by diameter and length of drum, condensate thickness, revolution per minute and steam temperature for experimental apparatus design.