The risk involved is a function of consequences of failure times probability of failure. Reducing any one will reduce the overall risk. Probability of failure is a statistical value whereas the controllable parameter is the severity of consequences. Most research are being done to assess the consequence of failure and minimizing the overall damage. Fire risks: Fire risks are everywhere. Whether it is an industrial facility or a building combustibles are used widely. Ignition sources are abundant too. Thus the chances to initiate fire are very high provided an oxidizer (mostly atmospheric air) is present.
• Tank/Pool fires: Tank/Pool fires are the most common consequence of an accidentally leaked (open) and contain (closed) flammable liquids and gases. Fig. 1 shows such a tank fire of a hydrocarbon fuel in reality and that in a lab-scale. The extrapolation from lab to real-scale increases the errors and reduces the accuracy. Hence, a quality set of measurement data on possible large pool fires are required to say something precisely about the thermal safety distances for immediate vicinity e.g. nearby tanks. Many experimental investigations were done on pool fires for various fuels (gasoline, kerosene, heptane, ethanol, LNG: Liquefied Natural Gas, LPG: Liquefied Petroleum Gas, crude oil, organic peroxides etc.). Small- as well large-scale test results for kerosene and organic peroxides are shown in Figs 3, 4 and 5. The safety distances for hydrocarbon tank fires are normally 3d to 4d (d: tank/pool diameter) whereas for fuels like ethanol LNG, LPG and organic peroxides require up to 10d. This was also proved by computer simulations (CFD: Computational Fluid Dynamics) performed by the group members in India and Germany. Also investigated are the multiple tank fires, a much realistic representation of the scenario and optimum spacing between the tanks and tank farm layout were established.
• Jet fires: Jet fires are high momentum fires producing intense thermal radiation and when impinging on a surface it can overheat and can lead to worst-case scenario or so-called domino effect. In our group jet fires (which are most likely) are studied mainly with CFD models. The thermal radiation from the fire were predicted and safety distances were developed for variety of fuels like LPG, organic peroxides.
• Small-scale burning (liquid, gases and solids) tests
• Fireballs: Fireballs are the results of BLEVE (Boiling Liquid Expanding Vapor Explosions) of closed containers of fluids under and without pressure. Mainly known BLEVEs are for LPG, LNG, CO2 etc. Recently organic peroxides when under controlled heating showed BLEVE and fireballs. Fireballs emit excessive thermal radiation for short duration which are necessary to correctly measure and predict. Fig. shows the development of an organic peroxide fireball with time. The diameter, height, burn duration and radiation were measured and predicted and eventually safety distances were developed.
• Building fires: Building fires in infrastructure are commonly controllable and uncontrollable. The uncontrollable fire in buildings can lead to complete collapse as happened in World Trade Center 2001 and recently in Iran. Such events are impossible to reconstruct in real-scale. Thus computational tools are often used. In our group we study all possible scenarios that can occur in a high-rise building. The fire and smoke spread, detectors layout, evacuation strategies are developed with the standard fire modeling code. The scenarios occurring frequently are recommended to be modeled for future high-rise buildings in order to avoid any major losses.
Large Pool Fire
Experimental Simulation of Pool Fire
Small Pool Fire
Thermal Image of Large Pool Fire
~striving for a safer tomorrow~
TECHNOLOGICAL RISK RESEARCH & ANALYSIS GROUP (TRAG)
तकनीकी जोखिम अनुसंधान एवं विश्लेषण समूह (ट्राग)