• Title/Summary/Keyword: 밸브누설

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A Study on Optimal Operation for Flare systems (플레어 시스템의 최적 운영방안에 대한 연구)

  • Song, Bang-Un;Bok, Hyeong-Jun;Woo, In-Sung
    • Journal of the Korean Institute of Gas
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    • v.23 no.6
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    • pp.1-7
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    • 2019
  • Most oil refineries and chemical plants have flare systems designed to mitigate pressure rises in process facilities in case of emergencies that require the release of large amounts of gas due to sudden process shutdowns such as power outages. However, the rise of the flame of the flare system causes civil complaints from residents around the factory due to visible pollution, and economic loss occurs in the company, which requires constant management. In this study, two items were diagnosed and analyzed in order to derive the optimal operation method of flare system. First, to detect the cause of the rise in flame height, the acoustic leak detector was used to check gas leaks in safety valves and pressure control valves. Second, to identify the cause of flame instability, the pulsation phenomenon was diagnosed through the CFD simulation and modeling experiments of the sealing drum. By confirming the leak at 4.3% of the safety valve and 10% of the pressure control valve, the cause of abnormal sparking was derived. The information presented in this study can be easily applied to any company that has a flare system, and is expected to prevent complaints and product loss.

FE Analysis on the Screwed Safety of a Valve for a LPG Bombe (LPG 용기용 밸브의 체결안전성에 관한 유한요소해석)

  • Kim, Chung-Kyun;Oh, Kyong-Seok
    • Journal of the Korean Institute of Gas
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    • v.11 no.4
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    • pp.79-84
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    • 2007
  • In this paper, the finite element analysis of a valve screw for a LPG cylinder has been presented on the leakage safety and strength one, which are computed and investigated by a contact normal stress and von Mises stress between a female screw of a valve and a male screw of a neck ring in a LPG bombe. The LP gas charging pressure of a LPG bombe is $8{\sim}9kg/cm^2$, which is pressurized to the screw sealing contact areas between a valve and a LP gas cylinder. The peak failures of the screw tooth height due to a scratch wear and chipping loss of the contact area may decrease screw tooth strength and increase a leakage of a LP gas. These are strongly affect to the contact normal and von Mises stresses of the valve screws. The FEM computed results show that the tooth height loss due to a wear and chipping failure of the screw peak does not affect to the LP gas leak and strength of a valve screw theoretically. But if the tooth wear of the screw height of a brass valve overpasses the critical strength safety of the valve, the valve screw may be failed in fastening the valve and a LP gas bombe suddenly.

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Study on the performance improvement of a Main Oxidizer shut-off Valve (CC 산화제 개폐밸브 성능향상에 관한 연구)

  • Bae, Young-Woo;Kim, Do-Hyung;Hong, Moon-Geun;Lee, Soo-Yong;Jang, Ki-Won
    • Aerospace Engineering and Technology
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    • v.9 no.2
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    • pp.63-72
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    • 2010
  • MOV(Main Oxidizer shut-off Valves) control the combustion of launch vehicle systems by the supply and the isolation of liquid oxygen to a main combustion chamber in launch vehicle systems. Moreover, the MOV should secure a constant flow rate of liquid oxygen for combustion instability in the steady operational state. Although it has been showed that a EM(Engineering Model) with a high discharge coefficient value compared with the TM(Technology Model) fills the overall performance requirements, additional design modifications in some critical parts of the EM were conducted to improve the performance. The configurations of the pressure-control body, the middle flange, and the rips of the inlet body of the EM were modified and the performance tests have been performed with test models. Consequently, the intended improvements have been verified by the performance tests.

Selection of Postweld Heat Treatment Condition of a High-Temperature and High-Pressure Forged Valve (고온고압용 단조밸브의 용접후열처리 조건 선정)

  • Park, Jae-Seong;Heo, Ki-Moo;Yoon, Sung-Hoon;Moon, Yoon-Jae;Lee, Jae-Heon
    • Plant Journal
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    • v.10 no.2
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    • pp.48-59
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    • 2014
  • Coupons which have same figure as weld joint of the forged steel valves and 1 inch nominal weld thickness were manufactured using ASTM A182 F92 material. After welding with GTAW method, the welded specimens have been post-weld heat treated at $705^{\circ}C$, $735^{\circ}C$, $750^{\circ}C$, $765^{\circ}C$, $795^{\circ}C$ and $825^{\circ}C$ for 1 hour per 1 inch nominal weld thickness each (Group 1) to evaluate characteristics of welds based on various holding temperature. Indeed, 3 welded specimens were post-weld heat treated for 30 minutes, 1 hour and 2 hour (Group 2) at $735^{\circ}C$ to evaluate characteristics of welds based on various holding time. Hardness values were measured at the weld metal, heat affected zone and base metal to observe hardness change depending on the condition. As a result of the evaluation, appropriate holding temperature for PWHT is proved as $750^{\circ}C$ and $765^{\circ}C$ for 1hour per 1 inch nominal weld thickness. Indeed, holding for 1 hour per 1 inch nominal weld thickness was insufficient for PWHT effect when the holding temperature was at $735^{\circ}C$. The microstructure of post-weld heat treated weld metal was determined as tempered-martensite structure.

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Leakage Monitoring of Control Valves for Nuclear Power Plants Using Multi-measuring (Multi-measuring기법을 이용한 원전 제어밸브의 누설진단)

  • Kim, Sung-Young;Kim, Young-Bum;Kim, Bong-Ho;Lee, Sang-Guk
    • Proceedings of the KSME Conference
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    • 2007.05b
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    • pp.3458-3463
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    • 2007
  • Leakage would happen because of the damage of high temperature and high-pressure valve in nuclear power plant. condition based prevention maintenance is essential by using the suitable method based on local condition. Energy loss prevention can prevent from an accurate test, Local actually and ability. The methods of test for high energy fluid leakage at present are analysis of ${\Delta}$T, AE(Acoustic Emission) analysis, and thermal image. The result for test of AC (Main steam) system in YNG 2 Unit reveals that the AE occurred clearly in leakage situation, but thermal image didn't occur. It is identified that leakage is occurred when the orifice located front and back of valve operates. It shows that making a impatient judgment by using the single method if it is leakage is containing uncertainty. So I think that using the Multi-Measuring method is more sound judgment than Single-Measuring method.

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A Study on the As-Built Leakage Diagnosis of Main Steam Drain Valves for Nuclear Power Plants by Multi-measuring Technique (다중계측기법을 이용한 원전 주증기배수밸브의 현상태 누설진단에 관한 연구)

  • Kim, Sung-Young;Kim, Young-Bum;Kim, Do-Hyeong;Lee, Sang-Gok
    • Proceedings of the KSME Conference
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    • 2008.11b
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    • pp.2606-2611
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    • 2008
  • The high energy fluid leakage from the high temperature and high differential pressure drop system of NPPs (Nuclear Power Plants) decreases efficiency and consequently leads to considerable economic loss due to less power production. Also, the leakage possibly damages critical parts of components such as valve and trim with the effect of cavitation, flashing, and erosion, etc. and deteriorates its performance. Thus, in this study, we diagnosed the as-is leakage for four (4) main steam drain valves and two (2) steam traps of Yonggwang 1,2 units during normal operation by using multi-measuring technique and observed the occurrence of fine leakage. In the course of measuring fluid leakage, the sign of fine leakage is estimated to be the leakage from orifice. By converting the leakage to energy loss, it is equivalent to the amount of several hundred thousand won per each unit, which supports the basis for the justification of fine leakage.

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Fault Diagnosis Algorithm of an Air-conditioning System by using a Neural No-fault Model and a Dual Fuzzy Logic (신경망무고장모델과 이중퍼지로직을 사용한 냉방기 고장진단 알고리즘)

  • Han Do-Young;Jung Nam-Chul
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.18 no.10
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    • pp.791-799
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    • 2006
  • The fault diagnosis technologies may be applied in order to decrease the energy consumption and the maintenance cost of an air-conditioning system. In this paper, a fault diagnosis algorithm was developed by using a neural no-fault model and a dual fuzzy logic. Five different faults, such as the compressor valve leakage, the liquid line blockage, the condenser fouling, the evaporator fouling, and the refrigerant leakage of an air-conditioning system, were considered. The fault diagnosis algorithm was tested by using a fault simulation facility. Test results showed that the algorithm developed for this study was effective to detect and diagnose various faults. Therefore, this algorithm may be practically used for the fault diagnosis of an air-conditioning system.

FEA(Finite Element Analysis) Study for Electronic Hydrogen Regulator of Confidentiality Improvement (전자식 수소레귤레이터 기밀성 향상을 위한 FEA 연구)

  • Son, Won-Sik;Song, Jae-Wook;Jeon, Wan-Jae;Kim, Seung-Mo
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.9
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    • pp.175-181
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    • 2019
  • In the case of a conventional single stage decompression regulator used for large depressurization in the hydrogen fuel cell system of a fuel cell electric vehicle (FCEV), problems can arise, such as pulsation, slow response, hydrogen brittleness, leakage, high weight, and high cost due to high decompression. Most of these problems can be overcome easily using two decompression mechanisms (two-stage structures). In addition, a wide outlet-pressure control range can be secured if an electronic solenoid is applied to the second decompression. Accordingly, it is necessary to improve the precision of the outlet pressure of a two-stage pressure-reducing regulator and develop techniques, such as leakage prevention, durability, light weight, and price reduction. Therefore, to improve the outlet pressure accuracy and prevent leakage, the structural part before and after decompression to improve the air tightness were divided and the analysis was carried out assuming that the valve part was closed (open ratio: 0%) after each initial internal pressure application.

Comparative Study of the Navier-Stokes Equation & the Reynolds Equation in Spool Valve Analysis Considering Cavitation (캐비테이션을 고려한 스풀밸브 해석에서 Navier-Stokes 방정식과 Reynolds 방정식에 의한 비교 연구)

  • Hong, Sung-Ho;Son, Sang-Ik;Kim, Kyung-Woong
    • Tribology and Lubricants
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    • v.29 no.5
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    • pp.275-285
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    • 2013
  • The Reynolds equation is commonly used to investigate the lubrication characteristics of a spool valve. However, the applicability of the Reynolds equation is questionable for analyzing a spool valve because cavitation often occurs in the grooves of the valve and the depth of a groove is much higher than the clearance in most cases. In this study, the validity of the Reynolds equation in the spool valve analysis is investigated by comparing the results obtained from the Reynolds equation and those obtained from the Navier-Stokes equation. The results are compared in terms of the lateral forces, friction forces, and volume flow rates (leakages). A significant difference of more than 20% is found in the lateral forces in cases where cavitation occurs and there are many grooves. Therefore, the Navier-Stokes equation should be used to investigate the lubrication characteristics of a spool valve when cavitation occurs and when the spool valve contains many grooves.

Fluid Film Characteristics between Cylinder Block and Valve Plates in Oil Hydraulic Piston Pumps (유압 피스톤 펌프의 실린더 블록과 밸브 플레이트 사이의 유막 특성)

  • Jung J.Y.;Song K.K.;Oh S.H.;Kim J.K.
    • Transactions of The Korea Fluid Power Systems Society
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    • v.1 no.2
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    • pp.8-14
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    • 2004
  • Abstract: In the oil hydraulic piston pumps the clearance between the valve plate and cylinder block plays an important role for volumetric and overall efficiency. Thus, adequate lubricational fluid film is needed for the interface. In this study, fluid film thickness is measured by a gap sensor and a slip ring under operational conditions to observe the behavior of the lubrication mechanism in detail. To investigate the effect according to the valve plate types in view of the fluid film, three different types were designed. Leakage flow rate and shaft torque were also measured to clarify the effect according to the valve plate types. A broad range of experiments were conducted to provide reasonable data on the effect of fluid film. In this experiments two main parameters were found, of which the one is the discharge pressure and the other is valve plate geometry. As a result, we found that the spherical valve plate could get more stable fluid film thickness, maintain good efficiency for high pressure range than the other types.

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