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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Institute of Gas
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The Korean Institute of GAS
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Volume & Issues
Volume 1, Issue 1 - Dec 1997
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A Study on the Safe Gap for Explosion-proof
Oh Kyu-hyung ;
Journal of the Korean Institute of Gas, volume 1, issue 1, 1997, Pages 1~6
In case of using the electrical apparatus in the hazardous atmosphere which exist flammable gas mixtures, There is a dangerosity of gas explosion accident by the electrical spark. The most general method to prevent the explosion by the spark is to use the flame-proof type electrical apparatus to isolate the ignition source. from the flammable atmosphere. But actualy it is impossible to isolate the ignition sources from the atmosphere. So it was needed to find the safe gap which prevent ignition of flammable atmosphere by transmission of flame or heat when a flammable gas mixture exploded inside the apparatus. In this study we tried to find the maximum experimental safe gap(MESG) of
-air mixtures by using the 8 litre spherical vessel with 25mm flange. The experiment parameter were ignition position, concentration and initial pressure before explosion. From the experiment the ignition position was affected to the MESG. MESG value was minimum near the stoichiometric concentration of gas mixtures, and according to the increase of initial pressure MESG was decreased.
A Study on Pressure Dependence of Minimum Ignition Energy
Ha Dong-Myeong ; Lee Su-Kyung ;
Journal of the Korean Institute of Gas, volume 1, issue 1, 1997, Pages 7~13
To investigate the pressure dependence of minimum ignition energy(MIE), thermal ignition theory, concept of heat transfer, ideal gas law, and kinetic theory are discussed. Correlation equations for the MIE and pressure were obtained through a regression analysis of reported data. In the proposed methodology the predicted MIE with pressure variations agree with reported data within a few average absolute deviations(A.A.D.). Therefore the proposed methodology has provided to be the general method for predicting the MIE of hydrocarbons.
Simulation and Analysis of a Gas Pipeline Network in Kyungin Area using Statistical Approach
Lee Eun-Lyong ; Chang Seung-Yong ; Kim In-Won ;
Journal of the Korean Institute of Gas, volume 1, issue 1, 1997, Pages 14~20
Pipeline network analysis requires fluid mechanics. A lot of equations have been used for flow analysis according to the behavior of fluid in pipelines and the operative situations. In this paper, simulation and analysis have been performed for the pipeline network system in Kyungin area using a steady-state mathematical model. Then, a statistical model using partial least squares(PLS) method has been developed with the data obtained from the developed mathematical model. The results showed that it is possible to simulate and analyze pipeline network systems using statistical approach.
Numerical Analysis on the Stress Behaviours Due to Geometry Effects of the Membrane Corrugation
Kim Chung-Kyun ; Lee Young-Suck ; Cha Baeg-Soon ; Kim Young-Gyu ; Yoon In Soo ; Hong Seong Ho ;
Journal of the Korean Institute of Gas, volume 1, issue 1, 1997, Pages 21~26
This paper presents the numerical results of six corrugation models which compute the stress behaviours and stress levels of the membrane structure under the hydrostatic pressure of cryogenic liquids and thermal loadings using a non -linear finite element analysis program. A three-dimensional analysis of various corrugation geometries was performed on the maximum mean normal stress distributions along the upper surface of the membrane sheet. Comparisons of the FEM results for various geometry models of the corrugation are presented, which shows that the corrugated configuration of the ring knot model can be effectively performed for the combined forces such as the hydrostatic pressure and thermal loading in comparison with the Technigaz type corrugation which has small comer and apex curvatures. The FEM results show that the ring knot corrugation can be used for the deepest depth, 180m of the LNG storage tank in comparison with other corrugation models.
Plant-wide On-line Monitoring and Diagnosis Based on Hierarchical Decomposition and Principal Component Analysis
Cho Hyun-Woo ; Han Chong-hun ;
Journal of the Korean Institute of Gas, volume 1, issue 1, 1997, Pages 27~32
Continual monitoring of abnormal operating conditions i a key issue in maintaining high product quality and safe operation, since the undetected process abnormality may lead to the undesirable operations, finally producing low quality products, or breakdown of equipment. The statistical projection method recently highlighted has the advantage of easily building reference model with the historical measurement data in the statistically in-control state and not requiring any detailed mathematical model or knowledge-base of process. As the complexity of process increases, however, we have more measurement variables and recycle streams. This situation may not only result in the frequent occurrence of process Perturbation, but make it difficult to pinpoint trouble-making causes or at most assignable source unit due to the confusing candidates. Consequently, an ad hoc skill to monitor and diagnose in plat-wide scale is needed. In this paper, we propose a hierarchical plant-wide monitoring methodology based on hierarchical decomposition and principal component analysis for handling the complexity and interactions among process units. This have the effect of preventing special events in a specific sub-block from propagating to other sub-blocks or at least delaying the transfer of undesired state, and so make it possible to quickly detect and diagnose the process malfunctions. To prove the performance of the proposed methodology, we simulate the Tennessee Eastman benchmark process which is operated continuously with 41 measurement variables of five major units. Simulation results have shown that the proposed methodology offers a fast and reliable monitoring and diagnosis for a large scale chemical plant.
A Study on Strengthened Genetic Algorithm for Multi-Modal and Multiobjective Optimization
Lee Won-Bo ; Park Seong-Jun ; Yoon En-Sup ;
Journal of the Korean Institute of Gas, volume 1, issue 1, 1997, Pages 33~40
An optimization system, APROGA II using genetic algorithm, was developed to solve multi-modal and multiobjective problems. To begin with, Multi-Niche Crowding(MNC) algorithm was used for multi-modal optimization problem. Secondly, a new algorithm was suggested for multiobjective optimization problem. Pareto dominance tournaments and Sharing on the non-dominated frontier was applied to it to obtain multiple objectives. APROGA II uses these two algorithms and the system has three search engines(previous APROGA search engine, multi-modal search engine and multiobjective search engine). Besides, this system can handle binary and discrete variables. And the validity of APROGA II was proved by solving several test functions and case study problems successfully.
A Reliability of Equation of State for Nitrogen, Oxygen and Argon
Yong Pyeong-Soon ; Moon Hung-Man ; Son Moo-Ryong ; Yi Sung-Chul ;
Journal of the Korean Institute of Gas, volume 1, issue 1, 1997, Pages 41~48
The equation of state is widely utilized as a simple model for the prediction of gas properties. There are several equations of state and they often make diverse and hard to believe output of gas properties. In this study, We show a reliability of equation of state for nitrogen, oxygen and argon in pressure range from 1 bar to 30 bar and temperature range from liquefaction to room temperature. We use three equations of state such as Soave-Redlich-Kwong, Peng-Robinson and BWR-LS' equation of state which provided in the Aspen plus. The results were compared with literatures and virial equation. Finally, We report the differences of process calculation of distillation column and expansion turbine in cryogenic air separation plant with change of equation of state.
A Study on the Relationship of Explosion Characteristics and Combustion Heat of Gas Mixtures
Oh Khy-hyung ; Kim Hong ; Yoo Joo-hyun ; Kim Tae-Jin ;
Journal of the Korean Institute of Gas, volume 1, issue 1, 1997, Pages 49~55
Destruction phenomena of structure by gas explosion is due to the explosion pressure and heat. Explosion pressure is a kind of energy converted from the gas mixture explosion. In this paper, we tried to find the relationship between explosion characteristics and combustion heat of the hydrocarbon-oxygen mixtures. Experiment were carried out with the volume of
cylindrical explosion vessel. Hydrocarbon gases which used in this study were methane, ethylene, propane, and buthane Experimental parameter was the concentration of the gas mixtures. Explosion characteristics were measured with strain type pressure transducer through the digital storage oscilloscope. From the experimental result, it was found that explosion pressure depend upon the combustion heat.
Development and Application of Pipeline Network Optimization Simulator
Sung Won-Mo ; Kwon Oh-kwang ; Lee Chung-Hwan ; Huh Dae-ki, ;
Journal of the Korean Institute of Gas, volume 1, issue 1, 1997, Pages 56~63
This paper presents a hybrid network model(HY-PIPENET) implementing a minimum cost spanning tree(MCST) network algorithm to be able to determine optimum path and constrained derivative(CD) method to select optimum Pipe diameter. The HY-PIPENET has been validated with the published data of 6-node/7-pipe network. Networking system and also this system has been optimized with MCST-CD method. As a result, it was found that the gas can be sufficiently supplied at the lower pressure with the smaller diameters of pipe compared to the original system in 6-node/7-pipe network. Hence, the construction cost was reduced about
in the optimized system. The hybrid networking model has been also applied to a complicated domestic gas pipeline network in metropolitan area, Korea. In this simulation, parametric study was peformed to understand the role of each individual parameter such as source pressure, flow rate, and pipe diameter on the optimized network. From the results of these simulations, we have proposed the optimized network as tree-type structure with optimum pipe diameter and source pressure in metropolitan area, Korea, however, this proposed system does not consider the environmental problems or safety concerns.
Operation Aiding System for Abnormal Situation in Chemical Plant
Park Kyoung-Chan ; An Dae-Myung ; Hwang Kyu-Suk ;
Journal of the Korean Institute of Gas, volume 1, issue 1, 1997, Pages 64~72
A strategy is proposed for the systematic synthesis of goal-tree to support the operation of abnormal situation in chemical plant. A knowledge base using the heuristics of operators is organized for synthesizing goal tree to take appropriate safety precautions with properties of accident. A computer-based system which utilizes artificial intelligence technique is developed to evaluate the effectiveness of the methodology and applied to the model plant.
Dispersion Modeling Methodology for Hazardous/Toxic Gas Releases from Chemical Plant Facilities
Song Duk-Man ;
Journal of the Korean Institute of Gas, volume 1, issue 1, 1997, Pages 73~80
This study was performed to develop the dispersion modeling methodology for quantitative prediction of the hazard distance or toxic buffer distance by comparing 10-min average, 30-min average, and 1-hr average maximum ground-level concentration with
regultaion concentration, IDLH and ERPG-3 concentration for hazardous toxic gas,
releases from the storage tank of the chemical plant facilities. For this dispersion modeling, the source term model, dispersion model, meteorological and topographical data are incorporated into the SuperChems model, and then the effects of the atmospheric stability, wind speed, and surface roughness length changes on the maxum ground-level concentration were estimated.
Risk Assessment and Application in Chemical Plants Using Fault Tree Analysis
Kim Yun-Hwa ; Kim Ky-Soo ; Yoon Sung-Ryul ; Um Sung-In ; Ko Jae-Wook ;
Journal of the Korean Institute of Gas, volume 1, issue 1, 1997, Pages 81~86
This study is to estimate the possibility of accident in chemical plants from the analysis of system component which affects the occurrence of top event. Among the various risk assessment techniques, the Fault Tree Analysis which approaches deductively on the route of accident development was used in this study. By gate-by-gate method and minimal cut set, the qualitative and quantitative risk assessment for hazards in plants was performed. The probability of occurrence and frequency of top event was calculated from failure or reliability data of system components at stage of the quantitative risk assessment. In conclusion, the probability of accident was estimated according to logic pattern based on the Fault Tree Analysis. And the failure path which mostly influences on the occurrence of top event was found from Importance Analysis.
The development of automatic system using multimodel in hazard analysis
Kang Kyung Wook ; Kang Byung Kwan ; Suh Jung Chul ; Yoon En Sup ;
Journal of the Korean Institute of Gas, volume 1, issue 1, 1997, Pages 87~94
There are many kinds of complicated equipments in the chemical plants. So the chemical plants have high possibility of accidents. Hazard analysis is one of the basic tasks to ensure the safety of chemical plants. However, it has many shortcomings. To overcome the problems, there have been attempts to automate this work by utilizing computer technology, particularly knowledge-based technique. However, many of the past approaches are lacking in properties: safeguard consideration, accident diversity, cause and consequence diversity, pathway leading to accidents, and various hazard analysis reasoning. Therefore, in this study, three analysis algorithms were proposed using multimodel approach, and a hazard analysis system, AHA, was developed on G2. The case study was solved with AHA system successfully.
Prediction of Elastic-Plastic Fracture Toughness for Metallic Material using Finite Element Method
Sun Dong-Ju ; Park Myung-kyun ; Bahk Sae-Man ; Choi Young-Taek ;
Journal of the Korean Institute of Gas, volume 1, issue 1, 1997, Pages 95~100
In order to predict the elastic-plastic fracture toughness for metallic materials, Finite Element Method(FEM) was used for analysis of compact tension specimen. ASTM E399 test procedure was adopted for simulation of FEM. The Load-Crack Mouth Opening Displacement curve obtained from this analysis was used to detect the crack initiation point and determine the elastic-plastic fracture toughness
. In order to prove the results, they were compared with the results from previous experiments and they agree with experimental results.
An Experimental Study on Groundwater Head, Injection Water Flowrate and Seepage Water Flowrate under Clogging State of Underground Storage
Han Choong-Yong ; Kang Joe M. ;
Journal of the Korean Institute of Gas, volume 1, issue 1, 1997, Pages 101~105
When the water curtain system is employed to keep the liquefied gas in the underground storage cavern, clogging is observed in borehole. Since this phenomenon causes serious difficulties in managing LPG storage cavern, it needs to detect the degree of clogging accurately under various circumstances. Thus, in this study the active factors of clogging, that is, groundwater head, injection water flowrate, and seepage water flowrate, were investigated experimentally using a physical model. Experimental results show that groundwater head around storage cavern increases as cavern Pressure increases, while it decreases as clogging becomes severe. The pressure in storage cavern is required to reduce up to atmospheric pressure in order to detect and identify the degree of clogging more accurately. The decrease of uroundwater head due to clogging slows down as the pressure in borehole increases. As amounts of suspended matters in injected water increase, both injection water flowrate and seepage water flowrate decrease linearly with time, and the flowrate of injection water drops rapidly compared with seepage water flowrate.
A Study on The Ignition Limit of Flammable Gases by Discharge Spark of Resistive Circuit
Lee Chun-Ha ;
Journal of the Korean Institute of Gas, volume 1, issue 1, 1997, Pages 106~112
This study measured the ignition limits of methane-air, propane-air, ethylene-air, and hydrogen-air mixture gases by discharge spark of D.C. power resistive circuit. The used experimental device is the IEC type spark ignition test apparatus, it consists of explosion chamber and supply -exhaust system of mixture gas. Mixture gases (methane-air, propane-air, ethylene-air, and hydrogen-air) were put into explosion chamber of IEC type spark ignition test apparatus, then it was confirmed whether ignition was made by 3,200 times of discharge spark between tungsten electrode and cadmium electrode. The ignition limits were found by increasing or decreasing the value of current. For the exact experiment, the ignition sensitivity was calibrated before and after the experiment in each condition. The ignition limits were found by changing the value of concentration of each gas-air mixture in D.C. 24 [V] resistive circuit. As the result of experiment, it was found that the minimum ignition limit currents exist at the value of methane-air 8.3 [
], propane-air 5.25[
], ethylene-air 7.8 [
], and hydrogen-air 21[
] mixture gases. For each the minimum ignition concentration of gases, the relationships between voltage and minimum ignition current were found. The results are as follows. - The minimum ignition limits are decreasing in the order of methane, propane, ethylene, and hydrogen. - The value of ignition current is inversely proportional to the value of source voltage. - The minimum ignition limit currents increase sharply at more than 2 [A]. The reason is caused by overheating the electrode.
Influence of Dust Environment on the Detection Capability of Ultraviolet Flame Detector
Kim Hong ; Hu Rui ;
Journal of the Korean Institute of Gas, volume 1, issue 1, 1997, Pages 113~119
The detection capability of UV flame detector in dust environment would be impaired. In this study, an experiment was conducted, in an effort to further understand the behavior of UV flame detector and to evaluate its detection capability in industry dust environment. Detergent powder, coal powder and dry extinguishing agent were selected as dust sources. Flaming sources include propane and gasoline flame. Experiment results indicate that dust can cause remarkable attenuation of UV flame radiation. The concentration of dust and the length of air layer where dust dispersed determine the reduction of radiation intensity. On the other hand, the attenuation of UV radiation also depends on the chemical and Physical properties of dust.
A Study on Thermal Stability of Chlorinated Polyethylene
Seul S. D. ; Lee N. W. ;
Journal of the Korean Institute of Gas, volume 1, issue 1, 1997, Pages 120~126
The thermal decomposition of low density polyethylene(LDPE) and
chlorinated polyethylene(CPE) were studied using a dynamic thermogravimetry in the stream of nitrogen gas with 20ml/min. The mathematic method, differential (Friedman) and Integral (Ozawa) method were used to obtain value of activation energy of decomposition energy on the reaction. The activation energies evaluated by the above methods agree with each other very well. The maximum average activation energy calculated was 71.71kcal/mol. The thermal decomposition of LDPE and CPE were considered to be carried out by main chain scission and the thermogravimetric trace curve agree with the theoretical equation.