• Title/Summary/Keyword: Gas Leakage

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Analysis of Pre-Swirl Effect for Plain-Gas Seal Using CFD (CFD를 사용한 비접촉식 가스 실의 입구 선회류 영향 해석)

  • Ha, Tae-Woong
    • The KSFM Journal of Fluid Machinery
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    • v.16 no.3
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    • pp.26-31
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    • 2013
  • In present 3D CFD study, the method for determining leakage and rotordynamic coefficients of a plain-gas seal is suggested by using the relative coordinate system for steady-state simulation. In order to find the effect of pre-swirl speed at seal inlet, pre-swirl velocity is included as a parameter. Present analysis is verified by comparison with results acquired from Bulk-flow analysis code and published experimental results. The results of 3D CFD rotordynamic coefficients of direct stiffness(K) and cross-coupled stiffness(k) show improvements in prediction. As pre-swirl speed at seal inlet increases, k also increases to destabilize system. However, pre-swirl speed at seal inlet does not show sensitivity to the leakage and rotordynamic coefficients of K and damping(C).

LPG 이송작업시 인적과오에 대한 사상수목분석

  • 김호영;김성영;임현교
    • Proceedings of the Korean Institute of Industrial Safety Conference
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    • 1998.05a
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    • pp.277-284
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    • 1998
  • LPG refueling include a lot of risk done by human beings, dealing with highly combustible gas, so, during the refueling, the leakage initiated by human errors can result in a catastrophic accident. Therefore, this research tried to show what kind of tasks would include the high probability of the human errors and what should be considered for effective safety management in the LPG refueling. At first, 4 typical cases were taken through surveying various accident cases, and then a prototype of the refueling task was presented. And each task was analysed by FTA and ETA. The results showed that overpressure occupies 64.64% of the major reasons for gas leakage, and its probability was approximately 6.62E-06. Among the tasks, gas leakage resulted from mal-assembly of lorry hoses had the highest rate, and human errors related to opening and closing valves of pipe lines were most frequent. Also, the effects of confirming tasks were analyzed quantitatively.

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DCT based Magnetic Flux Leakage Analysis for Defect Feature Extraction of Gas Pipelines (DCT 기반의 자기 누설 신호 분석을 통한 가스 배관에서의 결함 신호 특징 추출)

  • Han, Byung-Gil;Park, Gwan-Soo;Yoo, Hui-Ryong;Rho, Young-Woo;Choi, Doo-Hyun
    • Proceedings of the IEEK Conference
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    • 2006.06a
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    • pp.359-360
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    • 2006
  • Magnetic Flux Leakage (MFL) methods are widely employed for the non-destructive testing of gas pipelines. In the application of MFL pipeline inspection technology, corrosion anomalies are detected and identified via their leakage filed due to changes in wall thickness. This paper presents discrete cosine transform (DCT) based MFL signal analysis for defect feature extraction of natural gas pipelines. The original MFL signals are transformed into new ones based on the analysis. The usefulness of the approach has been shown by the experimental results.

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A Study on the Charpy Impact Performance of Structural Steel Considering the Leakage of Cryogenic Liquefied Gas (극저온 액화가스 누출에 의한 선체 구조용 강재의 샤르피 충격성능에 관한 연구)

  • Dong Hyuk Kang;Jeong-Hyeon Kim;Seul-Kee Kim;Tae-Wook Kim;Doo-Hwan Park;Ki-Beom Park;Jae-Myung Lee
    • Journal of the Korean Society of Industry Convergence
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    • v.26 no.2_2
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    • pp.333-340
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    • 2023
  • Environmental regulations are being strengthened worldwide to solve global warming. For this reason, interest in eco-friendly gas fuels such as LNG and hydrogen is continuously increasing. However, when adopting eco-friendly gas fuel, liquefying at a cryogenic temperature is essential to ensure economic feasibility in storage and transportation. Although austenitic stainless steel is typically applied to store cryogenic liquefied gas, structural steel can experience sudden heat shrinkage in the case of leakage in the loading and unloading process of LNG. In severe cases, the phase of the steel may change, so care is required. This study conducted Charpy impact tests on steel material in nine different temperature ranges, from room to cryogenic temperatures, to analyze the effects of cryogenic liquefied gas leaks. As a result of the study, it was not easy to find variations in ductile to brittle transition temperature (DBTT) due to the leakage of cryogenic liquefied gas. Still, the overall impact toughness tended to decrease, and these results were verified through fracture surface analysis. In summary, brittle fracture of the steel plate may occur when a secondary load is applied to steel for hull structural use exposed to a cryogenic environment of -40 ℃ or lower. Therefore, it needs to be considered in the ship design and operating conditions.

Numerical Study on Characteristics of Gas Leakage in an Underground Combined Cycle Power Plant (지하 복합발전 플랜트 내부의 가스 누출 특성에 대한 수치해석 연구)

  • Bang, Joo Won;Sung, Kun Hyuk;Ryou, Hong Sun;Lee, Seong Hyuk
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.5
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    • pp.594-600
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    • 2016
  • The present study numerically investigated the gas leakage characteristics in a simplified underground combined cycle power plant. The effect of obstacles near a crack location on the gas concentration in the confined space was analyzed by using the lower flammable limit (LFL) of methane gas. When the jet flow was close to the vertical walls, the longitudinal leakage distance increased by about 60% (when an obstacles was present) compared to the case without any obstacle, because these obstacles prevented transverse flows. In addition, when an air filter was installed near to the trajectory of the gas flow, the longitudinal leakage distance was similar to the distance between the crack and obstacle, whereas the transverse leakage distance increased up to 8 times compared to the case without any obstacle. As the jet flow impacts on the obstacle and changes its direction, the gas flows recirculate. Therefore, it is necessary to consider the effect of the structure and facility locations on the trajectory of the jet flow to propose an accident prevention system in confined spaces.

Implementation of High Magnetization System for Performance Enhancement of Magnetic Flux Leakage Tool

  • Cho, Sung-Ho;Yoo, Hui-Ryong;Kim, Dong-Ku;Park, Dae-Jin;Rho, Yong-Woo;Seo, Kang;Park, Gwan-Soo;Choi, Doo-Hyun;Song, Sung-Jin
    • Journal of Magnetics
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    • v.15 no.4
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    • pp.199-203
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    • 2010
  • This paper discusses the effectiveness of high magnetization saturation in ILI (In-Line Inspection) using an MFL (Magnetic Flux Leakage) tool, and introduces a practical method for improving the magnetization level together with the piggability. Thin steel plates, replacing the conventional wire brushes were used as conductors to transfer the magnetic flux to the pipe wall. The newly designed MFL tool was compared with the conventional version by means of FEM (Finite Element Method) analysis and full-scale experiments. In the results, the newly developed magnetization system obtained a stronger MFL signal amplitude, specially 2.7 times stronger, than that obtained by the conventional magnetization system for the same defect dimensions.

Identification on Principle of Acoustic Wave Propagation in a Gas Duct (가스 파이프 내부의 음향 전파 특성에 관한 연구)

  • Kim, Min-Soo;Lee, Sang-Kwon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.05a
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    • pp.1100-1105
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    • 2007
  • In the gas supply duct, the gas leakage caused by the impact of the construct equipment is serious problem. The identification of the impact position is an important issue and an engineering work. For the basic research of this problem, the principle studies for the acoustic wave propagation in a gas duct are proceeded in this paper. This principal work is based on the identification of the cut-off frequency associated with major modes of the gas duct theoretically and experimentally. The cut-off frequency is confirmed by STFT and cross-correlation function is used to identify the leakage position.

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Identification on Principle of Acoustic Wave Propagation Characteristics in a Gas Pipe (가스 배관 내부의 음파 전달 특성에 관한 연구)

  • Kim, Min-Soo;Lee, Sang-Kwon;Jang, Sang-Yup;Koh, Jae-Pil
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.18 no.8
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    • pp.797-804
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    • 2008
  • In the gas supply pipe, the gas leakage caused by the impact of the construct equipment is serious problem. The identification of the impact position is an important issue and an engineering work. For the basic research of this problem, the principle studies for the acoustic wave propagation in a gas pipe are proceeded in this paper. This principal work is based on the identification of the cut-off frequency associated with major modes of the gas pipe theoretically and experimentally The cut-off frequency is confirmed by STFT and cross-correlation function is used to identify the leakage position.

Review on Sensor Technology to Detect Toxic Gases (독성가스 감지용 센서 기술 동향 리뷰)

  • Lee, Janghyeon;Lim, Si-Hyung
    • Journal of Sensor Science and Technology
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    • v.24 no.5
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    • pp.311-318
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    • 2015
  • The excess use and generation of various toxic gases from many industrial complexes and plant facilities have increased the possibility of leakage or explosion accidents, which can cause fatal damage to human beings in the wide range of neighboring area. To prevent the exposure to the fatal toxic gases, it is very important to monitor the leakage of toxic gases using gas sensors in real time. Various types of gas sensors, which can be classified as semiconductor, electrochemical, optical, and catalytic combustion types according to the operating principles, have been developed. In this review, the operation principles of gas sensors are explained and the performance of those sensors is compared. The state-of-the-art gas sensor technologies developed by research institutes or companies are reviewed also.

An Experimental Study on Air Leakage and Heat Transfer Characteristics of a Rotary-type Heat Recovery Ventilator

  • Han, Hwa-Taik;Kim, Min-Kyu
    • International Journal of Air-Conditioning and Refrigeration
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    • v.13 no.2
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    • pp.83-88
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    • 2005
  • This study investigates the air leakage and heat transfer characteristics of a commercially available rotary-type air-to-air heat exchanger with a fiber polyester matrix. Crossover leakage between the exhaust and supply air is measured using a tracer gas method for various ventilation rates and rotational speeds of the wheel. A correlation equation for the leakage is obtained by summing up pressure leakage and carryover leakage. The pressure leakage is observed to be a function of ventilation rate only, and the carryover leakage is found to be a linear function of wheel speed. The real efficiency of the heat exchanger can be obtained from its apparent efficiency by taking into account the leakage ratio. The heat recovery efficiency decreases, as the ventilation rate increases. As the wheel speed increases, however, the efficiency increases initially but reaches a constant value for the speeds over 10rpm.