• Journal of Energy Engineering
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• v.23 no.4
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• pp.41-48
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• 2014

Leak of liquid has been categorized conventionally into instantaneous release and continuous release. In this study, the spread of cryogenic liquid due to limited period of release is investigated for the first time to establish a new classification method with recognizing the irrationality of the conventional one. Such physical phenomena are governed by simultaneous equations concerning volume, radius and height of pool of the cryogenic liquid, and major parameters are evaporation rate per unit area, time of release, and spill quantity. The simultaneous governing equations is decoupled to get efficiently perturbation solutions. As the results, for the same spill quantity, in view of release model, combined release model that consists of continuous and consecutive instantaneous model is necessary with small time of release, while continuous model is solely required with large time of release. Also, the combined model is necessary for small spill quantity with the same time of release. These two regimes of release are clearly distinguished using the perturbation solution to provide a clear basis for the new classification of release models.

• Journal of Energy Engineering
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• v.23 no.3
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• pp.174-180
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• 2014

Experimental study of liquid nitrogen pool spread is carried out when it is continuously released. The liquid nitrogen spreads over a cement mortar plate with continuous release. Evaporation rate per unit area of the liquid nitrogen is measured using a digital balance, and a spreading distance of the liquid pool is measured by thermocouples. It is discovered that the evaporation rate per unit area of liquid nitrogen tends to decrease as the liquid pool spreads.

• Journal of the Korean Institute of Gas
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• v.8 no.1 s.22
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• pp.13-17
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• 2004

To evaluate suitability of the Gaussian plume model for the small scale release of a dense toxic gas, experimental concentrations of the small scale release of chlorine were compared with theoretical concentrations calculated by the Gaussian plume model using various dispersion coefficients. As a result, Ive found that the dispersion of chlorine gas was fairly varied with dispersion coefficient and atmospheric stability and that chlorine concentrations were well estimated by the Gaussian plume model using Briggs' dispersion coefficient and the effective release hight.

• Journal of the Korean Institute of Gas
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• v.8 no.2 s.23
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• pp.8-14
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• 2004

This study analyzed dispersion characteristics and toxic effect in the small-scale continuous release of chlorine gas. We found that the Gaussian model using the Briggs' dispersion coefficient and the effective release height was better predicting experiments than the BM model. From chlorine concentrations calculated by Gaussian model, simulation results showed that the dispersion of chlorine was more affected by atmospheric stability and wind speed than release rate and that the toxic effect of chlorine gas was similar to the effect of parameters on chlorine dispersion. From effected areas with toxic criteria, damaged areas could be estimated to protect human.

• Transactions of the Korean hydrogen and new energy society
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• v.24 no.6
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• pp.487-494
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• 2013

In this study, solutions for a liquid pool spreading model with continuous and instantaneous release are discussed based on the model used in the FERC's report. The effects of the release time on the liquid pool volume and radius are investigated for the continuous release. For the continuous release with the frictional resistance force in the liquid pool spreading model, the vaporization time decreases as the release time increases. On the other hand, for the continuous release without the frictional resistance force in the liquid pool spreading model, the vaporization time increases as the release time increases. These phenomena are deeply related to the pool radius. In addition, the effects of the initial pool radius for the instantaneous release in the liquid pool spreading model are discussed. For the case with the frictional resistance force in the liquid pool spreading model, as reducing release time in the model with the frictional resistance force for the continuous release, the solution for a continuous release approaches to that for an instantaneous release. On the contrary to this, the pool volume and radius for the instantaneous release without the frictional resistance force are totally different from those for the continuous release without the frictional resistance force.

• Fire Science and Engineering
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• v.12 no.2
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• pp.3-15
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• 1998

The consequence analysis for jet and flash fire accidents by the continuous release of butane vapor was performed and effects of process variables on consequences were analyzed in standard conditions. For the continuous release (87.8 kg/s) of butane vapor at 8m elevated height in the debutanizing process of the naphtha cracking plant operating at 877 kPa, 346.75 K, we found that for the jet fire accident, shape and size of the flame could be predicted and thermal radiation estimated by API model at 200m distance from release point was 1.5kW/$m^2$, and that for the flash fire accident, effect range was 11.2~120.2m. Also, simulation results showed that effects of operating pressures on consequences were larger than those of operating temperatures and results of accidents were increased with increasing operating pressures. At this time, effects of operating pressures on XUFL were smaller(about 1/10) than those on XLFL for the flash fire accident.

• Fire Science and Engineering
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• v.32 no.3
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• pp.76-87
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• 2018

This study describes the damage effects modeling for a quantitative prediction about the hazardous distances from pressurized chlorine saturated liquid tank, which has two-phase leakage. The heavy gas, chlorine is an accidental substance that is used as a raw material and intermediate in chemical plants. Based on the evaluation method for damage prediction and accident effects assessment models, the operating conditions were set as the standard conditions to reveal the optimal variables on an accident due to the leakage of a liquid chlorine storage vessel. A model of the atmospheric diffusion model, ALOHA (V5.4.4) developed by USEPA and NOAA, which is used for a risk assessment of Off-site Risk Assessment (ORA), was used. The Yeosu National Industrial Complex is designated as a model site, which manufactures and handles large quantities of chemical substances. Weather-related variables and process variables for each scenario need to be modelled to derive the characteristics of leakage accidents. The estimated levels of concern (LOC) were calculated based on the Gaussian diffusion model. As a result of ALOHA modeling, the hazardous distance due to chlorine diffusion increased with increasing air temperature and the wind speed decreased and the atmospheric stability was stabilized.

• Journal of the Korean Institute of Gas
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• v.2 no.4
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• pp.7-17
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• 1998

This study is to develop the consequence modeling methodology for quantitative prediction of the hazard distance(or toxic buffer distance) for two-phase flow continuous releases from the pressurized chlorine saturated liquid storage tank of the chemical plant facilities. The source term modeling was peformed by the refined analysis method based on USEPA's guideline and SuperChems model self-calculation, respectively. The hazard distance was predicted for STEL, IDLH and ERPGs(ERPG-2 and ERPG-3) concentrations being used as the toxic regultaion concentration in hazard estimation. To use as hazard estimation guideline for the establishment of the emergency response planning, the effects of source characteristics and meteorological vaiations on the hazard distance was especially considered for ERPG-2 concentration.

• Applied Chemistry for Engineering
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• v.10 no.8
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• pp.1155-1160
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• 1999

The screening methodology modeling, dispersion modeling procedures for continuous and instantaneous releases of the gas phase flow from the storage tank and pressure relief valve were considered. This study was performed to develop the screening methodology for prediction and control of hazardous/toxic gas releases by estimating the 1-hr average maximum ground-level concentration of $Cl_2$ gas vs. downwind distance by incorporating source term model including the general/physical properties of released material and release mode of the $Cl_2$ storage tank of the chemical plant facilities, dispersion model, and meteorological/topographical data into the TSCREEN model. As the results of the study, it was found that dispersion modes of the dense gas were affected by the state of the released material, the released conditions, physical-chemical properties of released material, and the released modes (continuous and instantaneous releases), and especially largely affected by initial (depressurized) density of the released material and release emission rate as well as the wind velocity. Especially, this study was considered to release hazardous material as meteorological data. It was thought that this screening methodology can be useful as a preliminary guideline for application of the refined analysis model by developing the generic sliding scale methodology for various senarios selected.

• Journal of the Korea Safety Management & Science
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• v.4 no.3
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• pp.35-43
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• 2002

For the unconfined vapor cloud explosion accident by the continuous release of gas-liquid flow of various saturated liquids in a vessel at ground level, overpressures were estimated and analyzed with various release conditions and materials by TNT equivalency model with vapor dispersion. We found that at same release conditions, overpressure showed n-heptane > xylene > n-hexane > toluene > n-heptane > benzene, respectively and that overpressure was increased with increasing the hole diameter and the storage pressure, but it was increased with decreasing the wind speed, the interested distance, and the vessel thickness.