• Title/Summary/Keyword: Chemical Pressure Vessel

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The Evaluation of Thin Pressure Vessel′s Internal Defects by Laser Shearography (레이저 전단 간섭계를 이용한 압력용기의 내부 결함 평가)

  • 장경영;장석원;현민관
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2003.06a
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    • pp.929-933
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    • 2003
  • Internal defects of thin pressure vessel used in the power plants or the chemical plants may be created and grow due to corrosion or creep fatigue to reduce the strength and cause critical failure during operation. Therefore it is very important to detect this defect at the early stage. For this purpose, non-destructive, non-contact and highly sensitive method should be considered for on-line application. In this paper, a laser shearographic interferometer is applied to inspect circular defects and notch defects existed inside of thin pressure vessel under the presence of pressure up to 3 times of atmospheric pressure. The influences of the defect shape and size as well as the internal pressure to the characteristic pattern in the shearography fringe are investigated, and the quantitative evaluation of the defect size is tried. Also the experimental results are compared with the destructive test results to show the applicability of this method to the quantitative evaluation of internal defects in the thin pressure vessel.

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Dynamic Modeling & Analysis of Vapor Phase Blowdown of Depressurized Vessel (기체 블로우 다운의 동적 모델링 및 분석)

  • Kim, Kyungwoon;Seo, Ji Won;Hwang, Sungwon;Lee, Yun Ju;Moon, Young Sik
    • Korean Chemical Engineering Research
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    • v.54 no.3
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    • pp.350-359
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    • 2016
  • For accurate estimation over the change of pressure and temperature of the vessel during blowdown period, a new dynamic blowdown model was developed in this work. In particular, heat transfer from the vessel wall to discharge gas at both laminar or turbulent flow in the vessel was embedded to the model to increase the accuracy of blowdown estimation. For thermodynamics, the whole blowdown period was discretized into finite pressure decrement steps, and the step size was adjusted so that the calculation can be more efficiently carried out, while maintaining the model's accuracy. Both Peng-Robinson and Soave-Redlich-Kwong equation of states were applied to the model, and the results were compared each other. Finally, the simulation results was compared with Haque and coworkers' experimental results, and it proved high accuracy of the model.

Study on the Measurement of Safety of a High Pressure Vessel (고압용기(高壓容器)의 안전도(安全度) 측정(測定)에 관(關)한 연구(硏究))

  • Yim, Tong-Kyu;Choi, Man-Yong;Han, Eung-Kyo
    • Journal of the Korean Society for Nondestructive Testing
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    • v.2 no.2
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    • pp.9-16
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    • 1983
  • There are two weak points in a high pressure vessel, one is a corner, the other is a crack on the base. In order to evaluate safety of a department of a corner and a crack like a starfish on the base in a high pressure vessel (working pressure: $130kg/cm^{2}$), which was made by Marison's Process, we analyzed stress by strain gauge, measured thickness and hardness by ultrasonic testing, and were able to test pressure by water pressure from nondestructive testing. Also destructive testings were applied to measure thickness and to observe microstructure and chemical composition of a corner on the base. From the results of the experiment, values of experiment were satisfied with a condition of application. But, it is considered that a crack on the base is to be investigated with more by Fracture Mechanics.

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Quantitative Estimation of Radiation Damage in Reactor Pressure Vessel Steels by Using Multiscale Modeling (멀티스케일 모델링을 이용한 압력용기강의 조사손상 정량예측)

  • Lee, Gyeong-Geun;Kwon, Junhyun
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.10 no.1
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    • pp.113-121
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    • 2014
  • In this work, an integrated model including molecular dynamics and chemical rate theory was implemented to calculate the growth of point defect clusters(PDC) and copper-rich precipitates(CRP) which could change the mechanical properties of reactor pressure vessel(RPV) steels in a nuclear power plant. A number of time-dependent differential equations were established and numerically integrated to estimate the evolution of irradiation defects. The calculation showed that the concentration of the vacancies was higher than that of the self-interstitial atoms. The higher concentration of vacancies induced a formation of the CRPs in the later stage. The size of the CRPs was used to estimate the mechanical property changes in RPV steels, as is the same case with the PDCs. The calculation results were compared with the measured values of yield strength change and Charpy V-notch transition temperature shift, which were obtained from the surveillance test data of Korean light water reactors(LWRs). The estimated values were in fair agreement with the experimental results in spite of the uncertainty of the modeling parameters.

Design of Quorum Quenching Microbial Vessel to Enhance Cell Viability for Biofouling Control in Membrane Bioreactor

  • Cheong, Won-Suk;Kim, Sang-Ryoung;Oh, Hyun-Suk;Lee, Sang H.;Yeon, Kyung-Min;Lee, Chung-Hak;Lee, Jung-Kee
    • Journal of Microbiology and Biotechnology
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    • v.24 no.1
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    • pp.97-105
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    • 2014
  • Quorum quenching (QQ) with a microbial vessel has recently been reported as an economically feasible biofouling control platform in a membrane bioreactor (MBR) for wastewater treatment. In this study, a quorum quenching MBR with a ceramic microbial vessel (CMV) was designed to overcome the extremely low F/M ratio inside a microbial vessel. The CMV was prepared with a monolithic ceramic microporous membrane and AHL-degrading QQ bacteria, Pseudomonas sp. 1A1. The "inner flow feeding mode" was introduced, under which fresh feed was supplied to the MBR only through the center lumen in the CMV. The inner flow feeding mode facilitated nutrient transport to QQ bacteria in the CMV and thus enabled relatively long-term maintenance of cell viability. The quorum quenching effect of the CMV on controlling membrane biofouling in the MBR was more pronounced with the inner flow feeding mode, which was identified by the slower increase in the transmembrane pressure as well as by the visual observation of a biocake that formed on the used membrane surface. In the QQ MBR with the CMV, the concentrations of extracellular polymeric substances were substantially decreased in the biocake on the membrane surface compared with those in the conventional MBR. The CMV also showed its potential with effective biofouling control over long-term operation of the QQ MBR.

Purification of Iron Oxides and Application to Magnetic Hard Ferrite

  • Kim, Jeong-Seog;Chou, Kyoung-Ho;Kim, Jai-Young
    • The Korean Journal of Ceramics
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    • v.2 no.3
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    • pp.125-130
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    • 1996
  • Hematite iron ore and waste iron oxide sludge containing about 3-5 wt% $SiO_2$ were purified by three types of method developed on the basis of the Bayer process which is known as the purification process of bauxite ore. The basic principle of the developed methods lies in the fact that the impurities contained in the iron oxides, such as $SiO_2$ and $Al_2O_3$ are soluble in the alkaline reagents. Reaction of the raw materials with KOH was done in pressure vessel, at atmospheric pressure, and by both of these two. By the pressure vessel method $SiO_2$ content was reduced to below 0.5 wt% in the waste iron oxide sludge, while, in iron ore, $SiO_2$ remained at 2-3 wt%. The atmospheric pressure reaction rendered the waste iron oxide sludge $SiO_2$ content below 0.5wt% when the reaction temperature increased to above 90$0^{\circ}C$. The combined method of two previous methods was the most effective process and rendered the refined iron oxide about 300-400ppm of $SiO_2$. Using some refined iron oxides, Ba-ferrite was produced and magnetic properties were measured. The highest quality of magnetic properties obtained in this study were Br=2.09 G, bHc=1.99 KOe, iHc=4.54 KOe, $(BH)_{max}$=1.06 MGOe. Effect of sintering condition and chemical composition will be discussed.

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Study on the Characterization of Oxidative Degradation of Automotive Gasoline (자동차용휘발유의 산화열화특성 규명 연구)

  • Min, Kyong-Il;Yim, Eui Soon;Jung, Chung-Sub;Kim, Jae-Kon;Na, Byung-Ki
    • Korean Chemical Engineering Research
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    • v.51 no.2
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    • pp.250-256
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    • 2013
  • Gasoline generates organic acid and polymer (gum) by hydrocarbon oxidation depending on the storage environment such as temperature and exposure to sunlight, which can cause metal corrosion, rubber and resin degradation and vehicle malfunction caused by accumulation in fuel supply system. The gasoline which has not been used for a long time in bi-fuel (LPG-Gasoline) vehicle causes problems, and low octane number gasoline have evaporated into the field, but the exact cause has not been studied yet. In this study, we suggest a plan of quality management by investigating the gasoline oxidation behavior. In order to investigate the oxidation behavior of gasoline, changes of gasoline properties were analyzed at various storage conditions such as storage time, storage vessel type (vehicle fuel tank, PE vessel and Fe vessel) and storage circumstances (sunlight exposure and open system, etc.). Currently distributing gasoline and bioethanol blended fuel (blended 10%) were stored for 18 weeks in summer season. The sample stored in PE vessel was out of quality standard (octane number, vapor pressure, etc.) due to the evaporation of the high octane number and low boiling point components through the vessel cap and surface. Especially, the sunlight exposure sample stored in PE vessel showed rapid decrease of vapor pressure and increase of gum. Bioethanol blended fuel showed similar results as gasoline.

A Study on the Explosion Pressure Behavior of Methyl Ethyl Ketone Peroxide with Addition of Sulfuric Acid (황산의 첨가에 따른 Methyl Ethyl Ketone Peroxide의 폭발압력거동에 관한 연구)

  • Choi Jae-Wook;Jung Doo-Kyun;Choi Il-Gon
    • Journal of the Korean Institute of Gas
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    • v.8 no.4 s.25
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    • pp.50-54
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    • 2004
  • To examine the danger of explosion caused by decomposition explosion of Methyl Ethyl Ketone Peroxide, the mini cup pressure vessel tester (MCPVT) was used in the experiment. The maximum explosion pressure increased as the amount of $98\%H_2SO_4$ added to MEKPO increased from $0\%$ to $1\%,\;3\%$, and $5\%$, and the maximum pressure rising velocity increased as well. In addition, the temperature under the pressure at which decomposition starts decreased from $168.16^{\circ}C$ to $126.76^{\circ}C,\;91.21^{\circ}C$, and $81.25^{\circ}C$ as the amount of $H_2SO_4$ added increased.

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Influence of Steel-making Process and Heat-treatment Temperature on the Fatigue and Fracture Properties of Pressure Vessel Steels (제강 및 열처리 조건이 압력용기강의 피로 및 파괴특성에 미치는 영향)

  • Koh, S.K.;Na, E.G.;Baek, T.H.;Park, S.J.;Won, S.Y.;Lee, S.W.
    • Proceedings of the KSME Conference
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    • 2001.11a
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    • pp.87-92
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    • 2001
  • In this paper, high strength pressure vessel steels having the same chemical compositions were manufactured by the two different steel-making processes, such as vacuum degassing(VD) and electro-slag remelting(ESR) methods. After the steel-making process, they were normalized at $955^{\circ}C$, quenched at $843^{\circ}C$, and finally tempered at $550^{\circ}C$ or $450^{\circ}C$, resulting in tempered martensitic microstructures with different yielding strengths depending on the tempering conditions. Low-cycle fatigue(LCF) tests, fatigue crack growth rate(FCGR) tests, and fracture toughness tests were performed to investigate the fatigue and fracture behaviors of the pressure vessel steels. In contrast to very similar monotonic, LCF, and FCGR behaviors between VD and ESR steels, a quite difference was noticed in the fracture toughness. Fracture toughness of ESR steel was higher than that of VD steel, being attributed to the removal of impurities in steel-making process.

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Development of structural integrity evaluation program for reactor vessel under pressurized thermal shock (가압열충격에 대한 원자로용기의 구조건전성 평가프로그램의 개발)

  • 정명조
    • Computational Structural Engineering
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    • v.9 no.2
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    • pp.153-161
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    • 1996
  • In this paper, theory of fracture mechanics for the pressurized thermal shock is investigated and numerical procedure for the evaluation of the pressure vessel under pressurized thermal shock is developed. For the given material properties, transient history such as temperature and pressure, and postulated flaw, the stress distribution is obtained to calculate stress intensities for a wide range of assumed crack sizes. The stress intensities are compared with the material fracture toughness values corresponding to the chemical compositions and the distribution of the nil ductility transition temperature, to determine the crack growth during the transient. Plant-specific calculations have been performed for several transients and the evaluation results are discussed.

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