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[세션초청논문] 크리프 영역 고온 압력기기의 고신뢰도 건전성 평가를 위한 HITEP 플랫폼의 개발
이형연(Hyeong-Yeon Lee),이제환(Jewhan Lee),정시화(Si-Hwa Jeong),원민구(Min-Gu Won),허남수(Nam-Su Huh) 대한기계학회 2020 대한기계학회 춘추학술대회 Vol.2020 No.12
A high-reliability integrity evaluation platform of ‘HITEP’ has been developed with web-based language for a pressure boundary component and piping system subjected to high-temperature operation in creep regime. The platform program, called “HITEP” means ‘HIgh Temperature integrity Evaluation Program” which is for design evaluation of high-temperature pressure boundary components and piping as per the two major design codes of ASME Section III Division 5 Subsection HB (‘ASME-HB’) and RCC-MRx. The HITEP platform enables a user to provide information of current status and the optimal maintenance time based on the integrity evaluations. The design evaluation modules of the HITEP platform have been verified with a number of relevant example problems for RCC-MRx and ASME-HB. Because current high-temperature design codes of ASME BPVC Section VIII and ASME B31.1 being used for high temperature pressure vessel and piping were shown to be potentially non-conservative for long-term creep conditions in previous studies, the HITEP platform might be contributing to enhancing reliability of a high temperature pressure boundary components in thermal power plant and refinery plants as well operating at high temperature in creep range.
장기간 크리프 영역에서 가동되는 압력 기기 및 배관계통의 ASME Code (VIII Div.2 & B31.1)를 따른 설계의 비보수성 리스크
이형연(Hyeong-Yeon Lee),이제환(Jewhan Lee),김태완(Tae-Wan Kim) 대한기계학회 2019 대한기계학회 춘추학술대회 Vol.2019 No.11
ASME Section VIII Division 2(‘ASME VIII(2)’) and ASME B31.1 are widely used for design of not only lowtemperature but also high-temperature pressure vessels and piping, respectively operating at high temperature in creep range. In high-temperature design of a pressure vessel according to ASME VIII(2) and of a piping according to ASME B31.1, creep effects are not considered explicitly and the design evaluation results do not change depending on hold times at high temperature. In case of French high temperature design code of RCC-MRx, it explicitly takes creep hold time into account like the case of ASME Section III Division 5. Sensitivity analyses with various hold times at high temperature in design evaluations were conducted as per RCC-MRx to see the effects of hold times on design evaluations for a heat exchanger of IHX (intermediate heat exchanger) and a piping system in a sodium test facility. The conservatism of ASME VIII(2) and ASME B31.1 in case of long-term operation at high temperature in creep range have been quantified based on the comparisons in design evaluations as per ASME Codes with those of RCC-MRx which explicitly takes hold time into account. It was shown from the comparison that the results from ASME VIII (2) and ASME B31.1 exceeded the design limits of RCC-MRx if hold times exceed certain limits, which means ASME VIII (2) and ASME B31.1 might give non-conservative results in case of long time operation in creep range.
대체 기술기준을 적용한 크리프 영역 고온 압력기기의 건전성 개선
이형연(Hyeong-Yeon Lee),이제환(Jewhan Lee),어재혁(Jaehyuk Eoh) 대한기계학회 2021 大韓機械學會論文集A Vol.45 No.12
본 연구에서는 크리프 영역의 고온에서 가동되는 316L 스테인리스강 재질의 고온 열교환기의 고신뢰도 설계 및 평가 방법론을 제시하였다. 대형 소듐 열유동특성 종합효과시험시설로서 한국원자력연구원 내에 구축 완료 후 가동 중에 있는 STELLA-2 내 고온 소듐-공기 열교환기인 UHX의 구조설계 및 건전성 평가 방법론을 기술하였다. 일차 냉각재인 소듐의 온도가 550℃이고, 이차냉각재인 공기의 유입온도가 20℃로 530℃의 높은 온도차를 가지며 사용재질이 316L 스테인리스강인 헬리컬형 열교환기 UHX에 대해 구조설계 방법론과 3D 유한요소해석 기반 응력해석 및 건전성 평가 방법론을 제시하였다. 고온 압력기기의 설계에 통상적으로 사용하는 ASME BPVC Section VIII Division 2의 적용 시 기술현안, 그리고 대체 기술기준인 RCC-MRx를 따른 설계 건전성 평가 방법론을 제시하였다. In this study, the methodologies for design and integrity evaluations for a heat exchanger made of type 316L stainless steel subjected to high temperatures in the creep range are suggested. Structural design and integrity evaluations are conducted for a sodium-to-air heat exchanger UHX in the STELLA-2 test facility at the Korea Atomic Energy Research Institute (KAERI) for large-scale sodium thermal fluid characteristics integral effect tests and is currently under operation. The helical-type heat exchanger of the UHX has a temperature difference of 530°C with the primary coolant of 550°C sodium and secondary coolant of 20°C air and is made of austenitic stainless steel of type 316L. Methodologies for the structural designs, stress analyses, and integrity evaluations based on 3D finite element analysis are suggested. In the integrity evaluations on the UHX, the technical issues to applying the ASME BPVC Section VIII Division 2 that is generally used for design of the pressure vessel is analyzed and design methodologies for alternative design rules of the RCC-MRx are provided.
대용량 고온 열저장 성능시험 장치 내 700°C 열교환기의 고온 설계
이형연(Hyeong-Yeon Lee),윤정(Jung Yoon),이제환(Jewhan Lee) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11
High-temperature design of 700°C class heat exchanger was conducted that would be designed and installed in a large-scale high-temperature thermal storage performance test facility at KAERI site. The helical tube type sodium-to-air heat exchanger of 316 family stainless steel would be subjected to high-temperature operation with 300 hours steady state at 700°C over each creep-fatigue loading cycles. Stress analyses were conducted with the two candidate heat resistant materials of 316L and 316L(N) of French high-temperature design rules of RCC-MRx. Overall procedures on design and evaluation of 700°C class heat exchanger as per elevated temperature rules were taken and technical issues on the design evaluations in current design procedures were provided.
대용량 열저장 성능 시험장치용 내열강의 고온 재료거동 특성
이형연(Hyeong-Yeon Lee),하도현(Do-Hyun Ha),이제환(Jewhan Lee),어재혁(Jaehyuk Eoh) 대한기계학회 2022 大韓機械學會論文集A Vol.46 No.6
재생가능 에너지원의 간헐성을 극복하기 위한 유망한 방안 중의 하나는 대용량 열에너지 저장(TES) 시스템을 활용하는 것이며, 최근 TES 개발 연구는 고효율의 구현을 위해 설계 온도가 상승하는 추세에 있다. 본 연구에서는 설계온도 700°C의 대용량 열에너지 저장 성능시험장치 내 압력기기 및 배관계통에 사용될 수 있는 내열강 후보재료의 고온 재료 물성 현황과 거동 특성에 대해 분석하였다. 고온에서 가동되는 설비인 만큼 높은 신뢰성이 요구되는 TES 시스템용 내열강 후보재료 중 원자력 및 비원자력 기술기준에 등재되어 있는 내열강들을 중심으로 크리프 강도, 설계 응력강도 등의 재료 거동을 비교 분석하였다. 700°C 설계 평가와 관련하여 설계기술기준의 부재 물성을 분석하고, 부재 물성 중 일부 물성은 재료시험을 통해 확보하였다. One of the promising ways to overcome the intermittency of renewable energy sources is to utilize a large-scale thermal energy storage system. The recent research and development of TES systems have suggested increasing the design temperature to obtain higher efficiency. In this research, analyses were conducted on the current status and behavior characteristics of heat resistant candidate materials used in pressure boundary components and piping systems in large-scale thermal energy storage performance test facilities, using a design temperature of 700°C. Comparative analyses were conducted on the material behaviors of candidate materials, such as the creep rupture strengths and design stress intensities of the codified materials in the design rules of nuclear-grade and non-nuclear-grade; because the facility was operating at high temperatures, thereby requiring high levels of reliability. In addition, analyses on the absent material properties in the design rules from a 700°C high-temperature design evaluation viewpoint, were conducted, where some of the absent material properties were obtained from material tests.
세 개의 핀-튜브 군(群)을 가지는 교차유동 소듐-공기 열교환기 성능해석을 위한 새로운 1차원 전산해석 모델링 접근법
김형모(Hyungmo Kim),이제환(Jewhan Lee),어재혁(Jaehyuk Eoh),정지영(Ji-Young Jeong) 대한기계학회 2016 대한기계학회 춘추학술대회 Vol.2016 No.12
A novel computational modeling approach for a cross flow type sodium-to-air heat exchanger with three-row finnedtube banks was developed for its heat transfer performance analysis. The reference heat exchanger was installed in a separate effect test facility: SELFA (Sodium thermal-hydraulic Experiment Loop for Finned-tube sodium-to-Air heat exchanger), which has lots of helical fins on the outer surface of each heat transfer tube. Due to its complicated geometries, a simplified one-dimensional (1-D) modeling approach for heat transfer performance analysis using MARS-LMR has been used even in safety analyses of a nuclear power plant, e.g., Prototype Gen IV Sodium-cooled Fast Reactor (PGSFR). To make narrow the discrepancy between the computational modeling and real heat exchanger geometry, we developed and proposed more realistic modeling approach for a finned-tube type heat exchanger by considering each tube row separately. The results were evaluated using comparisons with 3-D CFD analysis results, which show reasonable agreements rather than the result obtained from a conventional 1-D modeling approach. This methodology can be implemented to more realistic modeling to cope with computing time increase at a limited computational resource.