• Journal of the Korean Institute of Gas
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• v.21 no.5
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• pp.95-103
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• 2017

A lot of hazardous materials have been used for product processing and utility plant. Many accidents including toxic release, fire and explosions occur in the ammonia related facility and plant. Various safety and environment management program including PSM, SMS, ORA etc. are being implemented for risk management and accident prevention in the production industry. Also much study and research have been carried about risk assessment of accident scenario in the academic and research area. In this paper, firstly risk level was assessed by using a typically used KORA program and LOPA PFD method for the selected ammonia unloading and storage facility. And then risk reduction measures for the risk assessed facility were studied in 3 aspects and some measures were proposed. Those Risk Reduction measures are including a leak detection and emergency isolation, water spray, dilution tank, dike and trench, scattering protection in hardware impovement aspect, and a applicable risk criteria, conditional modifier for existing LOPA PFD, alternative supporting modeling program in risk estimation methodology aspect, and last RBPS(Risk Based Process Safety) program, re-doing of process hazard analysis, management system compliance audit in managerial activity aspect.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.4
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• pp.132-137
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• 2018

Although the number of chemical accidents has been declining since the Chemical Control Act of 2015, there have been repeated occurrences of similar types of accidents at printed circuit board (PCB) manufacturing facilities. These accidents were caused by the overflow of hydrochloric acid and hydrogen peroxide, which are toxic chemicals used in the printed circuit board manufacturing process. An analysis of the $Cl^-$ content to identify the cause of the accident showed that in the mixed route of hydrochloric acid and hydrogen peroxide, which are accidental substances, the $Cl^-$ concentration was 66.85 ppm in the hydrogen peroxide sample. Through reaction experiments, it was confirmed that the deformation of a PVC storage tank and generation of chlorine gas, which is a toxic gas, occurred due to reaction heat occurring up to $50.5^{\circ}C$. This paper proposes a facility safety management plan, including overcharge, overflow prevention, leak detection device, and separation tank design for mixing prevention in printed circuit board manufacturing facility etch process. To prevent the recurrence of accidents of the same type, the necessity of a periodic facility safety inspection and strengthening of the safety education of workers was discussed.

• Journal of the Korean Institute of Gas
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• v.21 no.2
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• pp.41-49
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• 2017

Recently, as the number of facilities using chemicals is increasing, the amount of handling is rapidly increasing. However, chemical spills are occurring steadily, and if large quantities of chemicals are leaked in time, they are likely to cause major damage. These industrial complexes use information obtained from a number of sensors to detect and monitor leaking areas, and are used in industrial fields by applying existing fixed sensors to robots and drones. Therefore, it is necessary to propose a sensor placement method at the interface for rapid detection and response based on various leaking scenarios reflecting leaking conditions and environmental conditions of the chemical handling process. In this study, COMSOL was used to analyze the actual accident scenarios by applying the medium parameter to the case of chemical leaks. Based on the accident scenarios, the objective function is selected so that the velocity of each robot is calculated by attaching importance to each item of sensor detection probability, sensing time and sensing scenario number. We also confirmed the feasibility of this method of reliability analysis for unexpected leak accidents. Based on the above results, it is expected that it will be helpful to trace back the leakage source based on the concentration data of the portable sensor to be applied later.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.7
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• pp.964-970
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• 2023

As part of the International Maritime Organization ef orts to reduce greenhouse gas emissions, the maritime industry is exploring low-carbon fuels such as liquefied natural gas and methanol, as well as zero-carbon fuels such as hydrogen and ammonia, evaluating them as environmentally friendly alternatives. Particularly, ammonia has substantial operational experience as cargo on transport ships, and ammonia ship engines are expected to be available in the second half of 2024, making it relatively accessible for commercial use. However, overcoming the toxicity challenges associated with using ammonia as a fuel is imperative. Detection is possible at levels as low as 5 ppm through olfactory senses, and exposure to concentrations exceeding 300 ppm for more than 30 min can result in irreparable harm. Using the KORA program provided by the Chemical Safety Agency, an assessment of the potential risks arising from leaks during ammonia bunkering was conducted. A 1-min leak could lead to a 5 ppm impact within a radius of approximately 7.5 km, affecting key areas in Busan, a major city. Furthermore, the potentially lethal concentration of 300 ppm could have severe consequences in densely populated areas and schools near the bunkering site. Therefore, given the absence of regulations related to ammonia bunkering, the potential for widespread toxicity from even minor leaks highlights the requirement for the development of legislation. Establishing an integrated system involving local governments, fire departments, and environmental agencies is crucial for addressing the potential impacts and ensuring the safety of ammonia bunkering operations.

• Journal of Korean Society of Disaster and Security
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• v.16 no.3
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• pp.1-15
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• 2023

This study focuses on modeling the impact of ammonia leakage from the storage tank in a combined cycle power plant's flue gas denitrification facility. It employs accident impact assessments and diffusion models to determine the optimal scenarios for ammonia storage tank leakage accidents. The study considers the operating conditions of variables as standard conditions for predicting the extent of damage. The Taean combined cycle power plant is chosen as the target area, taking into account seasonal factors such as temperature, humidity, wind speed, atmospheric stability, and wind direction. By utilizing a Gaussian diffusion model, the concentration of ammonia gas at various locations is estimated to assess the potential extent of external damage resulting from a leak. The study reveals that in conditions of high temperature and stable atmosphere within the specified range, lower wind speeds contribute to increased damage to the human body due to ammonia diffusion.

• Journal of the Korean Institute of Gas
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• v.28 no.1
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• pp.11-18
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• 2024

If flammable liquid leaks, vapor evaporated from the pool can cause poisoning or suffocation to workers, leading to secondary accidents such as fires and explosions. To prevent such damage, ventilation facilities shall be installed when designing indoor workplaces. At this time, the behavior varies depending on the characteristics of the leaked chemical, so it is necessary to select a suitable vent location according to the material. Therefore, 3D CFD simulations were introduced to derive optimal vent position and ventilation efficiency was quantitatively evaluated by vent position. At this time, assuming a situation in which flammable liquids leak at indoor workplaces to form pools, the concentration of vapor evaporated from pools was compared to derive the optimal vent position. As a result of research on toluene with high vapor density, ventilation efficiency was confirmed to be the highest at the upper supply-lower exhaust, and it is judged that introducing it can achieve about 3.7 times ventilation effect at the same maintenance cost. Through this study, it is expected that the workplace will be able to secure workers' safety by applying simulation results and installing ventilation ports.

• Journal of Navigation and Port Research
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• v.48 no.4
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• pp.274-283
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• 2024

Climate change is currently one of the most pressing environmental issues, primarily caused by carbon emissions from fossil fuel usage. As a result, alternative fuels that effectively reduce carbon emissions are garnering more attention. Among these alternatives, hydrogen has numerous advantages, such as its ability for large-scale storage and transport. However, it is crucial to prioritize safety measures, particularly in facilities that handle hydrogen, due to its highly flammable and fast-spreading nature. This study aims to compare and analyze the placement of supply and exhaust vents to efficiently release hydrogen in the event of a leak in an enclosed space. The experiments involved six different scenarios, each with various combinations of supply and exhaust vents. To ensure the experimental process's safety, helium, which shares similar physical properties with hydrogen, was used to analyze the internal oxygen concentration during ventilation system operations. The results revealed that among the six scenarios, Case 2, which employed a lower side supply vent and an upper side exhaust vent, exhibited the shortest ventilation time of 4 minutes and 30 seconds. Additionally, the decrease rate in oxygen concentration was examined in the upper, middle, and lower areas. Ventilation utilizing an upper surface supply vent and two exhaust vents on the upper surface and upper side (Case 6), showed lower oxygen concentration values in the upper area, while Case 2 yielded lower values in the middle and lower areas. Therefore, it is crucial to select an appropriate supply and exhaust vent configuration considering the space's characteristics and usage environment.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.11
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• pp.997-1006
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• 2009

Organic removal efficiency and methane production rate, a feasibility of power generation from biogas, and the optimum conditions for membrane operation were evaluated for the pilot scale (5 tons/day) two-phase anaerobic digestion coupled with ultra filtration (TPADUF) system fed with garbage leachate. The TPADUF system is consisted of a thermophilic acidogenic reactor, a mesophilic methanogenic reactor, and an UF membrane. When garbage leachate with 150 g/L of TCOD was fed to the TPADUF up to organic loading rate (OLR) of 11.1 g COD/L/d, the effluent TCOD was lower than 6 g/L and the average removal efficiencies of TCOD and SCOD were higher than 95%. The methane composition of the gas was 65%, and the methane yield was 39 $m^3/m^3$ garbage leachatefed, 260 $m^3$/tons $COD_{added}$, or 270 $m^3$/tons $COD_{removed}$, even there was some gas leak. The power production per consumed gas was 0.96 kWh/$m^3$ gas or 1.49 kWh/$m^3$ methane. This lower power production efficiency mainly due to the small capacity of gas engine (15 kW class). The membrane was operated at the average flux of 10 L/$m^2$/hr. When the flux decreased, washing with water and chemical (NaOCl) was conducted to restore the flux. In the TPADUF system, optimum pH could be maintained without alkali addition by recycling the membrane concentrate or mixed liquor of the methanogenic digester to the acidogenic reactor. Also, partial production of methane in the acidogenic reactor had a positive effect on lowering the OLR of the methanogenic reactor.

• Fire Science and Engineering
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• v.31 no.5
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• pp.53-62
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• 2017

Electric power which is the energy source of economy and industries requires long distance transportation due to regional difference between its production and consumption, and it is supplied through the multi-loop transmission and distribution system. Prior to its actual use, electric power flows through several transformations by voltage transformers in substations depending on the characteristics of each usage, and a transformer has the structure consisting of the main body, winding wire, insulating oil and bushings. A transformer fire that breaks out in substations entails the primary damage that interrupts the power supply to houses and commercial facilities and causes various safety accidents as well as the secondary economic losses. It is considered that causes of such fire include the leak of insulating oil resulting from the destruction of bottom part of bushings, and the chain reaction of fire due to insulating oil that reaches its ignition point within 1 second. The smoke detector and automatic fire extinguishing system are established in order to minimize fire damage, but a difficulty in securing golden time for extinguishing fire due to delay in the operation of detector and release of gas from the extinguishing system has become a problem. Accordingly, this study was carried out according to needs of active mechanism to prevent the spread of fire and block the leak of insulating oil, in accordance with the importance of securing golden time in extinguishing a fire in its early stage. A bushings fireproof structure was developed by applying the high temperature shape retention materials, which are expanded by flame, and mechanical flame cutoff devices. The bushings fireproof structure was installed on the transformer model produced by applying the actual standards of bushings and flange, and the full scale fire test was carried out. It was confirmed that the bushings fireproof structure operated at accurate position and height within 3 seconds from the flame initiation. It is considered that it could block the spread of flame effectively in the event of actual transformer fire.

• Journal of the Korean Institute of Gas
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• v.5 no.4 s.16
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• pp.1-7
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• 2001

This paper presents a 'consequence analysis' for vapor cloud explosions caused by heavy gas leakages from commercially used storage tanks at petrochemical plants. Particularly, this paper emphasizes on evaluating the results of various vapor cloud explosion accidents from Butane storage tanks. Also this paper analyses the impact of variables on the accidents in order to acquire the optimum conditions for variables. $SuperChems^{TM}$ Professional Edition was applied to analyse the impact (If atmospheric and other variables in the situation where vapor cloud continuously disperses from the ground level. Under the assumption that practical operating conditions are selected as a standard condition, and Butane leaks from the storage tank for 15 minutes, the results show that the maximum distance of LFL (Lower Flammable Limit) was 52 meters and overpressure by the vapor cloud explosion was 1 psi at 128.2 meters. It is observed that the impact of the variables on accidental Butane storage tank leakage mainly varied upon atmospheric stability, wind velocity, pipe line size, visible length, etc., and changes in the simulation result occurred as the variables varied. The maximum distance of the LFL (Lower Flammable Limit) increased as the visible length became shorter, the size of the leak became larger, the wind velocity was decreased, and the climatic conditions became more stable. Thus, by analysing the variables that influence the simulation results of explosions of Butane storage tanks containing heavy gases, I am presenting the most appropriate method for 'consequence analysis' and the selection of standards for suitable values of variables, to obtain the most optimal conditions for the best results.