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Final report of research activities at BAM concerning large scale fireballs of organic peroxides (OP). New models for OP fireball diameter, duration, height and Surface Emmissive Power (SEP) are proposed and discussed based on a large number of large-scale and small-scale experiments using Di-tert-butylperoxide (DTBP) as a liquid OP and heptane as a liquid hydrocarbon fuel. Finally, CFD simulations are used to predict the fireball parameters: diameter, duration, height and SEP. Also the impact on the German storage regulations for organic peroxides are discussed.
Summary of recent research activities at BAM concerning large scale fireballs of organic peroxides (OP). Videos of the tests performed in Nanjing, China, are presented. A new model for OP fireball diameter, duration, height and SEP is proposed based on all experiments. In addition, small scale test results using DTBP and heptane are presented. Finally, CFD simulation is used to predict the fireball parameters: diameter, duration and height.
Organic peroxides are energetic substances liable to decompose due to exothermic reactions when exposed to uncontrolled temperature, contamination, confinement and quantity. Their safe storage and transportation are the prime concern and chemical industries and regulating authorities. Their accidental release may and most often lead to shape of a pool. In present study, safety distances from such large pool fires (diameter d = 3.4 m) of organic peroxides are numerically predicted by solving the reactive, 3-D time dependent Navier-Stokes equations with reliable assumptions. The present model is validated against the data on buoyant turbulent diffusion flames. The safety distances predicted by simulation assume three regions in a fully developed fire i.e. hot spot, luminous zone and a flame surface. The time averaged data of temperatures of these regions lead to better estimation of irradiances against the measured data. A developed sphere analogy method (for a special class of organic peroxides) for maximum surface emissive power prediction is also verified.
Fire and explosion hazards associated with storage and transportation of flammable materials have been a matter of great interest in the recent times. BLEVE is a scenario that occurs when a closed fuel container is subjected to heat for a longer duration. Such events are disastrous to human beings and assets both. In the past there have been numerous studies on BLEVEs and fireballs of hydrocarbon fuels, e.g. kerosene, gasoline, LPG, LNG and others. Though, the fireballs of peroxy-fuels are not looked into detail as such. This article tries to overcome this lack of knowledge. Both, experimental investigation and CFD simulations are performed to measure and predict the fireball characteristics of a peroxy-fuel. Due to thermal decomposition in the liquid phase and active oxygen content a peroxy-fuel fireball burns at a very fast rate and emit higher thermal radiation whereas exhibits smaller diameter and elevation compared to hydrocarbons. That eventually leads to consideration of larger safety distances from them which are also verified by CFD results.
Organic peroxides are capable to form fireballs with explosive violence. Only fireball models for liquid hydrocarbon fuels are available for the assessment of the thermal radiation properties. Because the development of such fireballs usually differ from those of organic peroxides the properties need to be characterized by modified equations. In this study liquid organic peroxide fireballs from 16 kg to 155 kg substance masses are characterized and compared to selected existing correlations. Flame characteristics and irradiances are measured with infrared cameras and heat flux sensors. All fireballs are consequences of simulated worst case scenarios where filled steel drums are engulfed by fire with varying heat impact. The differences of the given semi-empirical equations and the presented experimental work are explained. A new model is proposed for organic peroxide fireballs by modifying the constants of the known equations. The thermal radiation impact and safety distances are calculated and compared.
The thermal radiation impact of organic peroxide fireballs is experimentally assessed using an infrared camera. Fireballs are generated while liquid peroxide filled steel drums are subjected to gas burner fire at different heating rates. Three large burning clouds are observed with varying flame characteristics. Thermal radiation properties are assessed by infrared images with the presented methods. Despite of the two-dimensional temperature fields, the flames are treated and characterized as three-dimensional objects. Fireball diameters and heights are calculated based on a representing radiating sphere with the same cloud volume. By the use of the solid flame model and assumptions for emissivity and transmissivity, heat fluxes and thermal radiation doses against distance are predicted. Thermal safety distances are presented based on the maximum irradiance and the allowed exposure time. The validation of the maximum and time-dependent radiation fields is achieved through heat flux sensors in varying distances to the fireball. The results prove the use of an infrared camera and a volume based size calculation to fully assess the thermal radiation hazards of fireballs.