Result Analysis Modeling

Consequence Analysis Modeling - A Case Study in Tank Storage Areas Following scenario modeling of catastrophic events that may occur at facilities, such as fires, explosions and toxic dispersion (Hazard and Operability Analysis (HAZOP), Fault Tree and Event Tree Analyses (FTA-ETA)), it is recommended that consequence analysis modeling studies be conducted. In this way, it is advisable to perform these studies in order to observe the potential effects of selected scenarios on facility operations and to assess the adequacy of risk mitigation measures at the facility. The thermal radiation modeling study aimed to model the physical hazards that could occur following the release of flammable chemicals during transfer operations in the tank storage area at the facility. Using thermal radiation contours obtained from modeling outputs, the adequacy of the positioning of fire suppression systems and equipment located in the tank storage area was evaluated. Within the scope of the thermal radiation modeling study, the EFFECTS program was initially used, which is owned by the Netherlands-based Netherlands Organization for Applied Scientific Research (TNO), and subsequently by the Norway-based Gexcon. [caption id="attachment_140158" align="aligncenter"] Figure 1: Screenshot of the EFFECTS program interface[/caption] During the modeling study, liquid spill, pool evaporation, and dense gas dispersion models were used. The liquid spill model is used in modeling of tanks containing liquid with a hole below the liquid level or a hole in a pipe connected to the tank. Pool evaporation models calculate the amount of vapor evaporating from the liquid pool formed on the surface following the release of liquid material. In the dense gas dispersion model, if the gas has a higher density than air, it will tend to spread radially due to gravity and will result in a "gas pool." According to thermal radiation modeling results, thermal radiation diameters of 1 kW/m² - 3 kW/m² - 10 kW/m² were examined. For each tank, calculations were performed for effective exposure duration and effective exposure duration during evacuation for fire suppression equipment remaining within the 1 kW/m² thermal radiation contour and for operators using this equipment. For fire suppression equipment with negative values for evacuation time, effective exposure duration, and effective exposure duration during evacuation, repositioning relative to the relevant tanks was reconsidered. [caption id="attachment_140159" align="aligncenter"] Figure 2: Thermal radiation modeling example for solvent tanks-1 (left), modeling example-2 (right)[/caption] Figure 2 on the left shows the thermal radiation modeling contours for a solvent tank and the fire suppression equipment located around the solvent tank. The calculated effective exposure duration and effective exposure duration during evacuation for the operator using this fire suppression equipment was calculated as a positive value. Figure 2 on the right shows the thermal radiation modeling contours for a different solvent tank and the fire suppression equipment located around the solvent tank. As no fire suppression equipment was located within the 1 kW/m² contour obtained from this modeling result, effectiveness durations could not be calculated for the operator. As seen in Figure 2 right and left, a catastrophic event that may occur in the tank storage area affects both the tanks in the tank storage area through domino effect and also impacts the railway adjacent to the tank storage area and any potential passenger/cargo train. To prevent domino effect and to limit possible catastrophic events, various measures should be evaluated and a blast/fire wall should be constructed between the railway and the tank storage area as a limiting measure. Following all scenario modeling studies, another study to be performed is the determination of individual and social risks. In this study, individual and social risks to populated areas surrounding the facility outside the establishment resulting from a possible catastrophic event at the facility can be determined using the RISKCURVES program owned by Gexcon.   Damla Gizem Uyar Process Safety Technical Manager Önder Akademi A.Ş.   Melisa Kumlalı Process Safety Specialist Önder Akademi A.Ş.   Sources / References (1) Methods for the calculation of Physical Effects Due to releases of hazardous materials (liquids and gases) – Third edition Second revised print 2005 (2) Methods for the determination of possible damage to people and objects resulting from releases of hazardous materials – First edition 1992