consequence modeling

  Storage tanks are always one of the equipment that can cause serious risks for industries and nearby units due to the complex process conditions. Releasing the substances of these tanks can lead to consequences such as fiery explosions and the dispersion of toxic substances. Therefore, identifying the causes and modeling their consequences is considered essential.

In this study, the bow tie diagram for identifying the cause-and-effect diagram of diesel tanks, and also fuzzy theory for determining the failure rate of basic events, were used. In order to determine the probability of basic events, fuzzy theory and experts' opinions were considered, and finally, phast8.2 software was used for modeling possible scenarios.

The results of the bow tie analysis showed that a total of 45 basic events and 4 consequences, including pool fire, eruption fire, sudden fire and explosion were identified. The result of consequence modeling showed that the maximum intensity of the thermal radiation caused by the pool fire for the diesel tank was equal to 23 kW / m2 and the maximum increase in the blast wave was estimated to be 19.7 bar. The results of risk evaluation for the consequences of pool fire, eruptive fire and steam explosion showed that the estimated risk number is more than 104 and are in the unacceptable range.

Using the bow tie method in combination with consequence modeling can provide experts with a more open view of the accidents along with causes and consequences which happen for storage tanks

  Storage tanks are always one of the equipment that can cause serious risks for industries and nearby units due to the complex process conditions. Releasing the substances of these tanks can lead to consequences such as fiery explosions and the dispersion of toxic substances. Therefore, identifying the causes and modeling their consequences is considered essential.

In this study, the bow tie diagram for identifying the cause-and-effect diagram of diesel tanks, and also fuzzy theory for determining the failure rate of basic events, were used. In order to determine the probability of basic events, fuzzy theory and experts' opinions were considered, and finally, phast8.2 software was used for modeling possible scenarios.

The results of the bow tie analysis showed that a total of 45 basic events and 4 consequences, including pool fire, eruption fire, sudden fire and explosion were identified. The result of consequence modeling showed that the maximum intensity of the thermal radiation caused by the pool fire for the diesel tank was equal to 23 kW / m2 and the maximum increase in the blast wave was estimated to be 19.7 bar. The results of risk evaluation for the consequences of pool fire, eruptive fire and steam explosion showed that the estimated risk number is more than 104 and are in the unacceptable range.

Using the bow tie method in combination with consequence modeling can provide experts with a more open view of the accidents along with causes and consequences which happen for storage tanks

Ammonia is a toxic gas and is used as a refrigerant due to its special thermodynamic properties. This study was designed to evaluate the toxic effects of ammonia leakage in an industrial refrigerator.

The present study was conducted in an industrial refrigerator in 2019. Due to its widespread use in industrial refrigerators, reservoirs containing ammonia gas were selected as the center of hazards. Given the potential damage of this chemical, only the toxic dimension of this gas was evaluated. Also, owing to the importance of determining the extent of human vulnerability, the scenarios were evaluated in the worst condition and in the case of the catastrophic rupture of reservoirs. Consequences modeling of selected scenarios was performed using PHAST 7.2 software.

The obtained concentration profiles showed that during the first and last six months of year, reservoir 1 with up to respectively 570.20 and 349.09 meters beyond it in the wind direction, located on the ERPG3 level, according to ERPG (Emergency Response Planning Guidelines) levels. Likewise, in reservoir 2 between 891.05 and 556.74 m from the reservoir, during the first and last six months of the year, located on the ERPG3 level, respectively.

Catastrophic rupture of ammonia tanks and its dispersion into the environment can cause a high mortality rate. Therefore, implementation of preventive programs such as emergency response planning appropriate to the potential hazards of ammonia gas, development of a comprehensive risk management plan, determining the correct location of reservoirs following the results of consequence modeling, etc. can be effective steps in reducing the consequences in the case of such accidents.

Methane is one of the gaseous materials with high potential of damage. Today, it is widely used in process, chemical industries and human environments. This study thus aimed to predict the emissions and the probable effects of liquid methane using ALOHA software in order to perform appropriate safety measures and consequently to reduce the plausible adverse effects.

Considering the results of HAZOP studies, the worst case scenario was chosen and, using ALOHA software, possible methane gas leak scenarios from the reservoir were modeled. During the study, all the moral standards were observed.

Based on the results obtained, gas concentrations of liquid methane would reach 400000 ppm in a distance of 39 meters around the reservoir, which is in the range of PAC-3 demonstrating risk of death threatening the lives of surrounding people. In the event of a full leakage of 238 meters around the reservoir, the methane gas concentration is predicted to be 50000 ppm, which is equivalent to the low explosive charge (LEL) of methane gas. Wave pressure of vapor cloud caused by methane leaks exceeds 1 psi in a distance of 270 meters.

The consequences of methane toxicity in the studied refinery are one of the most serious threats to the personnel. Therefore, preparing a reaction plan for emergency conditions will have an effective role in limiting the harmful effects of the toxic and dangerous materials emissions.

The release of toxic, hazardous and fire hazardous substances from storage tanks in process and chemical industries has always been one of the hazards of working people, residents around these industries, and the environment. This study was done with the aim of modeling and evaluating the consequences of benzene leakage in the coke production unit of Isfahan Steel Company.

In order to observe ethical standards in research, research information was obtained with written permission from Isfahan Steel Company. In the present study, in order to modeling and investigating the release of benzene, at first cycle of the process in the coking plant, and then Existing hazards were identified by performing a risk assessment using the FMEA method. The consequence evaluation in a process unit consists of selecting a scenario, specifying the scenario's specifications, modeling the consequences of the scenarios and finally analyzing the results. For this purpose, the software ALOHA version 5.4.7 has been used for modeling the outcome and evaluation of benzene leakage.

The results of simulations show that the most serious risk factor for personnel is the concentration of benzene in the environment. And due to the control room being 72 meters from the corresponding reservoir, up to 169 meters of the tank the concentration of benzene vapors reaches 800 ppm. Hence, people who are at this distance will not be able to escape during an incident. Also, the contour lines of simulating the pool fire resulting from the benzene release, shows that in the leakage scenarios with a diameter of 5 mm, 25 mm and 100 mm, distances less than 10, 14 and 51 m influenced with fire, respectively.

Despite the errors in the results of mathematical modeling and the explanation of possible scenarios, simulation of benzene leakage and its consequences, can be used in the formulation of preventive strategies and emergency planning in the coking plant of Isfahan Steel Company.

One of the most fuel materials that recently considered is compressed natural gas (CNG). Despite all the known benefits, storage, transportation and use of compressed natural gas as a fuel have risks such as explosions and fires. This study was aimed towards Consequence Modeling of Fire and Explosion on Methane Storage Tanks in a CNG refueling Station.

In this study, A CNG station was evaluated. Considering the results of the visit the CNG station, survey of the recent studies and events and review of experts' opinions, four scenarios of discharges, catastrophic rupture, jet fire and explosions in compressed natural gas storage tanks were evaluated. Then each of these scenarios by using the software is modeled and Possible Consequences of each scenario were evaluated. In order to Consequence Modeling and examine the outcome of Consequences in this study, the PHAST software version 6.7 was used.

In this study two jet fire and explosion scenarios of storage tanks were selected as the worst case scenarios. In jet fire scenario the maximum area affected by fire is 135/13 square meters in the leakage dimension of 150 millimeters. The results of CNG storages explosion modeling also showed that at a distance of 20 meters from storage tanks, the explosion pressure increase is 1 bar (The probability of death in this pressure is 100%) and gradually decrease by increase the distance from the storage tanks, as far as the distance of 400 meters, it reaches at 0.01 bar that is a safe area. It was also found, in the radius 52, 69 and 232 meters of the storage tanks there were 0.21, 0.14 and 0.02 bar increasing pressure, respectively.

The results of present study showed that leakage and damage of the storage tanks, can lead to deadly accidents, Particular in dual-purpose refueling stations (CNG and Gasoline). So according to the results of this study, increasing the number of this refueling stations in recent years, corrective actions in order to increasing the safety levels in methane gas storage tanks in CNG refueling Station is essential

The leakage of hazardous materials in industries threatens the workers and residents around these industries and also severely damages the environment. This study thus aimed to predict the emissions and the probable effects of carbon disulfide using ALOHA software in order to performing the appropriate safety measures and consequently to reduce the adverse effects. The results of HAZOP studies were used to identify the hazards in one of the refinery units. The plausible worst scenario was also chosen. ALOHA software was then used to model the probable scenarios of carbon disulfide emissions from the tank. All stages of this research were conducted ethically. Based on the results obtained, the concentration of carbon disulfide reaching to the control room would be fatal in the event of an incident. This result is supported by carbon disulfide concentrations of 480 ppm in an area of up to 600 meters around the tank, which is in the range of AGEL-3. In the event of full leakage, the concentration of carbon disulfide would be 7800 ppm 150 m around the tank, which is about 60% of the minimum flammable concentration of this gas. The explosion wave pressure in a distance of up to 190 m around the tank is anticipated to be about 3 psi, which may cause serious injuries to workers. The consequences of carbon disulfide toxicity in the studied refinery are one of the most serious threats to the personnel. Therefore, preparing a reaction plan for emergency conditions will have an effective role in limiting the harmful effects of the toxic and dangerous materials emissions.

Ethylene oxide (EO) is a very toxic and dangerous substance with a high potential for explosion and fire. Ethylene oxide units are among the most hazardous units in petrochemical industries. This study was designed to analyze and model the consequences of ethylene oxide storage tanks explosion in one of Iran's petrochemical industries.

In this study, the consequences of the ethylene oxide storage tanks explosion in a petrochemical industry was identified and analyzed. This study was conducted in 2017 using PHAST software version 6.54. For this study, two climate conditions including the first climate conditions (spring and summer) and the second climate conditions (autumn and winter) were considered.

The results of the modeling for the first and second climate conditions showed that there were possibility of severe damages due to the explosion consequences up to 204 and 256 meters, respectively. In addition, based on the criteria for assessing the consequences of accidents associated with damage levels, such as the explosion wave, the wind speed and direction due to the sudden release scenario and the numerical results related to the modeling, the consequence of this scenario in the second climate conditions (autumn and winter) was higher than the first climate conditions (spring and summer).

The findings of the study indicated that, in addition to the high risk of explosion of ethylene oxide storage tanks, the modeling scenarios in different climate conditions have different consequences. Thus, more attention should be paid to safety of these equipment as risk centers in the petrochemical industry and similar industries

Being aware of the explosion, fire radius, and their damages, has an important role in accident prevention methods. Therefore, the aim of this study was modeling and evaluation of the consequences of propylene oxide spill in a petrochemical company.
Material and The QRA method including seven steps was used in this study. In the present study, in order to examine and modeling of the propagation propylene oxide, first a familiarization with the process information of the unit was done then, a risk assessment was carried out adopting HAZOP technique to identify existing hazards. Consequence analysis in a process unit includes: selecting important scenarios, characterizing scenario, modeling the consequences of scenarios, analyzing the results and determining the percentage of mortality. PHAST software version 6.51 was used for modeling of outcomes and assessment propylene leak.
urves of the firing zones of sudden release of propylene oxide showed that the influence puts are included up to radius of 0.15 meters in the scenario of leakage 5 mm, in scenarios with leaks 25 mm to a radius of 1.1 meters and in scenarios with leakage of 100 mm to a radius of 39 meters. The maximum intensity of flash fire in the initial point Scenario 5 mm was 4.2 kW/m2, in the scenario of radiation leakage was 25 mm at the distance to 5 meters from the fire intensity up to maximum of 9 kW/m2, and also in the scenario with 100 mm flash fire radiation leak at an earlier point fire was 14 kW/m2. The maximum intensity of thermal radiation at the distance to 5 meters up to 16.5 kW/m2, and maximum distance of 80 meters around the reservoir affected. The mortality rate of flash fire has exposed employees, was 50 percent.
Many accidents caused by leakage and explosion were due to corrosion, spoil tanks and equipment, and the majority of such accidents can be prevented by technical inspections and continuous audits.

using fossil fuels, some hazards such as explosion and fire are probable. This study was aimed to consequence modeling of fire on Methane storage tanks in a gas refinery using analyzing the risk, and modeling and evaluating the related consequences.
Hazard analysis by PHA was used to choosing the worst-case scenario. Then, causes of the scenario were determined by FTA. After that, consequence modeling by the PHAST software was applied for the consequence analysis.
Based on some criteria, the fire of methane gas tank (V-100) was selected as the worst-case scenario at the refinery. The qualitative fault tree showed three factors including mechanical, process, and human failures contribute in gas leakage. The leakage size and weather conditions were effective on the distance of radiation. Using consequence modeling, thermal radiation was considered as the major outcome of the incident. Finally, for outcome evaluating, probit equations were used to quantify losses and the percentage of fatalities due to the methane gas leakage and fire occurrence. The maximum number of fatalities caused by fire was obtained 23 persons.
In conclusion, the methane gas vessel in the refinery can be considered as the main center of hazard, therefore the implementation of the safety rules, eliminating mechanical failures, personal protection and education, and Effective measures to prevent and fighting of fire are proposed for decreasing the probable losses and fatalities.

One of the most essential and important steps for improving safety level in existing or designing units is consequence evaluation of hazards such as fire, explosion and dispersion of hazardous chemical substances. Due to severe operational conditions, high explosive and flammable gases such as methane and hydrogen, hydrogen production process is causing major industrial accidents of the view life and financial losses. Therefore safety is main concern of hydrogen producers. First, all hazards and potential scenarios of hydrogen production were identified by applying HAZID Technique, and after collecting the required data, consequence modeling was done by means of professional software PHAST6.54. Death probability of people by means of valid equations of probit was calculated and ultimately, the severity of the consequences was estimated using conventional criteria. The results revealed that, jet fire caused by a full bore rupture in Desulphurization reactor has the highest fatality (26person). The harm effect distance, maximum radiations of this incident were 250 m, 370 kW/m2 respectively. A full bore rupture in Reformer can lead to the most dangerous flash fire. So that people at distance up 130 m from placing leakage and affected area 1505m2 were exposed to concentration of 61120 ppm and all people would be killed. The most dangerous vapor cloud explosion caused by hydrogen purification absorbers, so that distances up to 60m from absorbers location all people would be killed and all process equipments and buildings will be completely destroyed. The safe distance of hydrogen production unit equals to 746 m from its boundary limit. Consequence evaluation is a quantitative and comprehensive method for estimation and evaluation of potential incidents severity of industrial hazardous units. The occurrence of incidents such as fires and explosions has the great life and financial losses in the hydrogen production process, Thus safety of industries nearby hydrogen production and consume must be specifically considered.