• Journal of the Korean Institute of Gas
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• v.25 no.6
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• pp.53-65
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• 2021

While the hydrogen refueling station is rapidly expanded and installed, the safety inspection of the hydrogen pressure vessel in the station should be very important. Of these, according to ASME, hydrogen embrittlement tests must be performed for hydrogen vessel that store hydrogen above a certain pressure. The main test method for hydrogen embrittlement inspection is to carry out fracture tests and fatigue fracture tests in a high pressure hydrogen atmosphere, which allows the durability limit of the pressure vessel to be measured and the endurable limit to be determined in the hydrogen atmosphere. In detail, the critical crack depth can be calculated by the stress intensity factor(K), and the service life can be determined by da/dN (fatigue growth rate). API579-1/ ASME FFS-1 part 9 exemplifies the calculation method according to the mode of crack-like flaws, but for various shapes such as plates and cylinders, there are about 55 modes according to the shape and location of the crack. Due to the fairly complex formula, it is not easily accessible. In this study, we will show you how to calculate fracture mechanics numerically via Excel and VBA. In addition, this was applied to analyze the effects of the thickness and inner diameter of the pressure vessel on the service life.

• Journal of the Korean Institute of Gas
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• v.10 no.1 s.30
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• pp.19-25
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• 2006

Explosion limit is one of the major physical properties used to determine the fire and explosion hazards of the flammable substances. Explosion limits are used to classify flammable materials according to their relative flammability. Such a classification is important for the safe handling, storage, transportation of flammable substances. In this study, the lower explosion limits(LEL) of the flammable mixtures predicted with the appropriate use of the vapor composition and the heat of combustion of the individual components which constitute mixture. The values calculated by the proposed equations were a good agreement with literature data within a few percent. From a given results, It is to be hoped that this methodology will contribute to the estimation of the explosive properties of flammable mixtures with improved accuracy and the broader application for other flammable substances.

• Journal of the Korean Institute of Gas
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• v.12 no.2
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• pp.1-6
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• 2008

For the safety design and operation of many gas process, it is necessary to know certain explosion limit, flash point, autoignition temperature (AIT) and minimum oxygen concentration of handling substances. Also it is necessary to know explosion limit at high temperature and pressure. In this study for the safe handling of hydrogen, explosion limit and AIT of combustion properties for hydrogen were investigated. By using the literatures data, the lower and upper explosion limits of hydrogen recommended 4.0 vol% and 77.0 vol%. Also the AIT of hydrogen with ignition sources recommended $400^{\circ}C$ at the electrically heated crucible furnace (the whole surface heating) and recommended $640^{\circ}C$ at the local hot surface. The new equations for predicting the temperature and the pressure dependence of the explosion limits of hydrogen are proposed. The values calculated by the proposed equations were a good agreement with the literature data.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.6
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• pp.453-459
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• 2021

The system marginal price of electricity is the amount paid to all the generating units, which is an important decision-making factor for the construction and maintenance of an electrical power unit. In this paper, we suggest a long-term forecasting model for calculating the system marginal price based on prices of natural gas and oil. As most variables used in the analysis are nonstationary time series, the long run relationship among the variables should be examined by cointegration tests. The forecasting model is similar to an error correction model which consists of a long run cointegrating equation and another equation for short run dynamics. To mitigate the robustness issue arising from the relatively small data sample, this study employs various testing and estimating methods. Compared to previous studies, this paper considers multiple fuel prices in the forecasting model of system marginal price, and provides greater emphasis on the robustness of analysis. As none of the cointegrating relations associated with system marginal price, natural gas price and oil price are excluded, three error correction models are estimated. Considering the root mean squared error and mean absolute error, the model based on the cointegrating relation between system marginal price and natural gas price performs best in the out-of-sample forecast.

• Journal of the Korean Institute of Gas
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• v.9 no.3 s.28
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• pp.9-14
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• 2005

To estimate the explosion characteristics of converted gas, the study was examined into effects of altering oxygen concentration and adding hydrogen. From the result of the experiment, as the concentration of converted gas and hydrogen were increased at $21\%$ oxygen concentration, the lower explosion limit was low. Minimum explosion oxygen concentration was $6\%$. Maximum explosion pressure of converted gas was $4.61 kg_f/cm^2$, now Maximum explosion pressure rising velocity was $130.75 kg_f/cm^2/s$ at converted gas concentration $40\%$. Also, minimum ignition energy was 0.13 mJ at converted gas concentration $50\%$.

• Journal of the Korean Institute of Gas
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• v.10 no.3 s.32
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• pp.60-64
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• 2006

Explosion range and explosion characteristics of by product gas from carbon black manufacturing process were studied. About 75% of the by product gas were composed with water vapour and nitrogen. And the combustible component in the gas were hydrogen, methane, acetylene and carbon mono-oxide. Because of the combustible components in the by product gas there are explosion hazards in the gas handling process. Explosion range of the gas by experiment was from 17.1% to 70.7% and the value has considerable difference with the calculated value from Lechatelier law. Explosion pressure of the gas was $5.4kg/cm^2$ and the average explosion pressure rise rate was $39.2kg/cm^2/s$. Based on the experimental result we can expect that a explosion or fire accident during the handling the gas can make a severe loss, therefore there should be a explosion prevention or protection measures in the gas handling process.

• 한국신재생에너지학회:학술대회논문집
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• 2008.10a
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• pp.246-249
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• 2008

IGCC (석탄가스화 복합발전) 시스템 공정 중 가스화기에서 발생되는 합성가스 내에는 높은 농도의 분진들이 함유되어 있기 때문에 하부 공정들을 보호하기 위해서는 가스화기 후단에 집진장치가 필히 설치되어야 한다. 집진장치의 설계 제작 운전에 있어서 점착성 분진층 부착,분진 브리징, 필터 파손 현상 등과 같은 다양한 문제점들로 인하여 고온의 합성가스를 처리하는 데는 아직 기술적 한계들이 산재해 있는 상황이다. 이와 같은 문제점들은 필터에 부착된 분진층의 탈진성능을 향상시키거나, 필터의 열피로를 줄일 수 있도록 필터 재생을 위한 탈진의 횟수를 줄이는 방법을 통하여 해결될 수 있다. 본 연구에서는 파일롯 규모의 IGCC용 세라믹캔들필터 집진장치에서의 가스 유입 및 탈진 조건에 따른 집진장치의 차압 특성 변화를 수치해석과 실험을 통하여 분석함으로써 탈진성능을 향상시킬 수 있는 조건과 탈진 횟수를 최소화시킬 수 있는 방안을 도출하고자 하였다.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 1998.05a
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• pp.179-184
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• 1998

가연성물질의 안전한 취급을 위해서는 이들 물질의 가장 기초적인 위험 특성 자료인 폭발한계(화재안전자료)에 대한 지식을 필요로 한다. 발화원이 존재할 때 가연성가스와 공기가 혼합하여 일정 농도 범위내에서만 연소가 이루어지는데 이 혼합범위를 폭발(연소)한계(explosive(flammable) limits) 또는 연소범위라 한다. (중략)

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.131.2-131.2
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• 2010

서부 발전 태안화력발전소에 건설 예정인 IGCC Demo plant의 설계 자료를 근거로 석탄 가스화기의 정상 상태 전산모사를 PRO/II를 사용하여 수행하였다. 석탄을 PRO/II가 받아들일 수 있는 성분으로 바꾼 후 가스화기를 버너와 가스화기 본체의 두 부분으로 나누어 모델링하였다. 버너는 단열조건의 Gibbs Reactor로 모델링하였다. 모사 결과 산소가 완전 소진될 때까지 반응이 진행되는 것을 확인하였다. 가스화기는 char gasification 반응은 kinetic reaction equation으로, gas phase reaction은 equilibrium reactor로 모사하는 알고리듬을 개발 하였으나 PRO/II의 기능에 한계가 있어 간단한 Gibbs Reactor로 모사하였다. 가스화기는 membrane wall에 의하여 냉각되는 것을 고려하여 $1550^{\circ}C$의 균일한 온도에서 반응이 일어나는 것으로 고려하였다. 전산 모사 결과 주요 성분의 조성이 실제 syngas의 조성과 5% 정도 오차가 있는 것으로 나타났다.

• Journal of the Korean Institute of Gas
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• v.15 no.2
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• pp.75-81
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• 2011

For the safe handling of cyclohexane, the explosion limit at $25^{\circ}C$ and the temperature dependence of the explosion limits were investigated. Flash point and AIT(autoignition temperature) for cyclohexane were experimented. By using the literatures data, the lower and upper explosion limits of cyclohexane recommended 1.0 Vol% and 9.0 Vol%, respectively. Moreover lower flash points of cyclohexane recommended $-20^{\circ}C$. It was measured relationship between the AITs and the ignition delay times by using ASTM E659-78 apparatus for cyclohexane, and the experimental AIT was $255^{\circ}C$. The new equations for predicting the temperature dependence of the explosion limits of cyclohexane is proposed. The values calculated by the proposed equations were a good agreement with the literature data.