• Title/Summary/Keyword: Once-through Steam Generator

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Design of digital nuclear power small reactor once-through steam generator control system

  • Qian, Hong;Zou, Mingyao
    • Nuclear Engineering and Technology
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    • v.54 no.7
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    • pp.2435-2443
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    • 2022
  • The once-through steam generator used in the small modular reactor needs to consider the stability of the outlet steam pressure and steam superheat of the secondary circuit to achieve better operating efficiency. For this reason, this paper designs a controllable operation scheme for the steam pressure and superheat of the small reactor once-through steam generator. On this basis, designs a variable universe fuzzy controller, first, design the fuzzy control rules to make the controller adjust the PI controller parameters according to the change of the error; secondly, use the domain adjustment factor to further subdivide the input and output domain of the fuzzy controller according to the change of the error, to improve the system control performance. The simulation results show that the operation scheme proposed in this paper have better system performance than the original scheme of the small reactor system, and controller proposed in this paper have better control performance than traditional PI controller and fuzzy PI controller, what's more, the designed control system also showed better anti-disturbance performance in lifting experiment between 100% and 80% working conditions. Finally, the experimental platform formed by connecting the digital small reactor with Matlab/Simulink through OPC(OLE for Process Control) communication technology also verified the feasibility of the proposed scheme.

Modelling and Verification of Once-Through Subcritical Heat Recovery Steam Generator (관류형 아임계압 배열회수보일러의 열성능 모델링과 검증)

  • Lee, Chae-Soo;Choi, Young-Jun;Kim, Hyun-Gee;Yang, Ok-Chul;Chong, Chae-Hon
    • Proceedings of the KSME Conference
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    • 2004.11a
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    • pp.1692-1697
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    • 2004
  • The once-through heat recovery steam generator is ideally matched to very high temperature and pressure, well into the supercritical range. Moreover this type of boiler is structurally simpler than drum type boiler. In drum type boiler, each tube play a well-defined role: water preheating, vaporization, superheating. Empirical equations are available to predict the average heat transfer coefficient for each regime. For once-through heat recovery steam generator, this is no more the case and mathematical models have to be adapted to account for the disappearance of drum type economizer, boiler, superheater. General equations have to be used for each tube of boiler, and actual heat transfer condition in each tube has to be identified.

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Reinforcement learning-based control with application to the once-through steam generator system

  • Cheng Li;Ren Yu;Wenmin Yu;Tianshu Wang
    • Nuclear Engineering and Technology
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    • v.55 no.10
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    • pp.3515-3524
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    • 2023
  • A reinforcement learning framework is proposed for the control problem of outlet steam pressure of the once-through steam generator(OTSG) in this paper. The double-layer controller using Proximal Policy Optimization(PPO) algorithm is applied in the control structure of the OTSG. The PPO algorithm can train the neural networks continuously according to the process of interaction with the environment and then the trained controller can realize better control for the OTSG. Meanwhile, reinforcement learning has the characteristic of difficult application in real-world objects, this paper proposes an innovative pretraining method to solve this problem. The difficulty in the application of reinforcement learning lies in training. The optimal strategy of each step is summed up through trial and error, and the training cost is very high. In this paper, the LSTM model is adopted as the training environment for pretraining, which saves training time and improves efficiency. The experimental results show that this method can realize the self-adjustment of control parameters under various working conditions, and the control effect has the advantages of small overshoot, fast stabilization speed, and strong adaptive ability.

Development of a thermal-hydraulic analysis code for once-through steam generators using straight tubes for SMRs (일체형 원자로용 관류식 직관형 증기발생기 열수력 해석 코드 개발)

  • Park, Youngjae;Kim, Iljin;Kang, Kyungjun;Kang, Hanok;Kim, Youngin;Kim, Hyungdae
    • Journal of Energy Engineering
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    • v.24 no.2
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    • pp.91-102
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    • 2015
  • A thermal-hydraulic design and performance analysis computer code for a once-through steam generator using straight tubes is developed. To benchmark the developed physical models and computer code, an once-through steam generator developed by other designer is simulated and the calculated results are compared with the design data. Also, the same steam generator is analyzed with the best-estimate thermal-hydraulic system code, MARS, for the code-to-code validation. The overall characteristics of heat transfer area, pressure and temperature distributions calculated by the developed code show general agreements with the published design data as well as the analysis results of MARS. It is demonstrated that the developed code can be utilized for diverse purposes, such as, sensitivity analyses and optimum thermal design of a once-through steam generator.

Sizing of a tube inlet orifice of a once-through steam generator to suppress the parallel channel instability

  • Yoon, Juhyeon
    • Nuclear Engineering and Technology
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    • v.53 no.11
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    • pp.3643-3652
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    • 2021
  • Sizing the tube inlet orifice of a Once-Through Steam Generator (OTSG) is important to protect the integrity of the tubes from thermal cycling and vibration wear. In this study, a new sizing criterion is proposed for the tube inlet orifice to suppress the parallel channel instability in an OTSG. A perturbation method is used to capture the essential parts of the thermal-hydraulic phenomena of the parallel channel instability. The perturbation model of the heat transfer regime boundaries is identified as a missing part in existing models for sizing the OTSG tube inlet orifice. Limitations and deficiency of the existing models are identified and the reasons for the limitations are explained. The newly proposed model can be utilized to size the tube inlet orifice to suppress the parallel channel instability without excessive engineering margin.

Fault-tolerant control system for once-through steam generator based on reinforcement learning algorithm

  • Li, Cheng;Yu, Ren;Yu, Wenmin;Wang, Tianshu
    • Nuclear Engineering and Technology
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    • v.54 no.9
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    • pp.3283-3292
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    • 2022
  • Based on the Deep Q-Network(DQN) algorithm of reinforcement learning, an active fault-tolerance method with incremental action is proposed for the control system with sensor faults of the once-through steam generator(OTSG). In this paper, we first establish the OTSG model as the interaction environment for the agent of reinforcement learning. The reinforcement learning agent chooses an action according to the system state obtained by the pressure sensor, the incremental action can gradually approach the optimal strategy for the current fault, and then the agent updates the network by different rewards obtained in the interaction process. In this way, we can transform the active fault tolerant control process of the OTSG to the reinforcement learning agent's decision-making process. The comparison experiments compared with the traditional reinforcement learning algorithm(RL) with fixed strategies show that the active fault-tolerant controller designed in this paper can accurately and rapidly control under sensor faults so that the pressure of the OTSG can be stabilized near the set-point value, and the OTSG can run normally and stably.

Performance Design Analysis of the Supercritical Pressure Bottoming System of Combined Cycle Power Plants Using Once-Through Steam Generator (관류형 증기발생기를 사용한 복합발전용 초임계압 하부시스템의 성능 설계해석)

  • 양진식;김동섭;노승탁
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.26 no.10
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    • pp.1370-1377
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    • 2002
  • This study analyzed the design performance of the bottoming system of combined cycle power plants using a once-through heat recovery steam generator. For a parallel arrangement of the main heater and reheater, parametric analyses were carried out to present the criteria for determining the reheater pressure and the location of the starting point of the reheater in the HRSG. The performance of the bottoming system was presented fer a range from high subcritical to supercritical pressure. The steam turbine power is as high as that of conventional triple-pressure bottoming systems. The serial arrangement of heat exchangers with division of each heater into several segments can achieve similar power level.

Performance Analysis of Once-through HRSG and Steam Turbine System (관류형 열회수 증기발생기와 증기터빈 시스템의 성능해석)

  • Yang, J.S.;Kim, T.S.;Ro, S.T.
    • Proceedings of the KSME Conference
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    • 2001.11b
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    • pp.872-877
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    • 2001
  • This study analyzed the design performance of the bottoming system of combined cycle power plants adopting a single-pressure once-through heat recovery steam generator with reheat. A computer program was constructed and parametric analyses were carried out to present the criteria for determining the reheat pressure and the location of the starring point of the reheater in the HRSG. The performance of the bottoming system was presented for the range from high subcritical to supercritical pressures. It was founded that the power of the bottoming system can be as high as that of the present triple-pressure bottoming system even with a higher exhaust gas temperature. A requirement for this high performance is a proper arrangement of the reheater.

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Development of Dynamic Simulation Software for Power Plant and its Application to Once-Through Boiler (플랜트 동특성 해석용 소프트웨어 개발 및 초임계압 관류형 보일러에의 적용)

  • Lee, Ki-Hyun;Lee, Dong-Su;Cho, Chang-Ho
    • Proceedings of the KSME Conference
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    • 2000.11b
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    • pp.656-661
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    • 2000
  • In the recent trend of electric power supply market, a variable pressure operation supercritical once-through steam generator is highlighted as a thermal power plant for cycling load because of its superiority in load regulation. Almost all thermal power plants of the future are expected to be variable pressure operation supercritical once-through units. APESS(Advanced Plant Engineering & Simulation System) is a dynamic simulation software for power plant which is under being developed by Korea Heavy Industries & Construction Co., Ltd. This paper present the introduction of APESS and the result of simulation for variable pressure operation supercritical once-through steam generator.

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