Filtern
Erscheinungsjahr
Dokumenttyp
- Vortrag (26)
- Beitrag zu einem Tagungsband (25)
- Zeitschriftenartikel (13)
- Posterpräsentation (11)
- Beitrag zu einem Sammelband (2)
- Dissertation (1)
Schlagworte
- Pool fire (11)
- CFD simulation (9)
- CFD (7)
- Peroxy-fuels (7)
- Mass burning rate (6)
- Organic peroxides (6)
- TBPB (6)
- TBPEH (5)
- Overpressure (4)
- Safety distance (4)
Eingeladener Vortrag
- nein (26)
The diffusive burning characteristics of four peroxy-fuels (usually known as liquid organic peroxides) and one hydrocarbon fuel are experimentally investigated targeting alternative fuels (or as additives to conventional fuels) for the future. Measurements are performed in form of pool fires with pool diameters in the range between 1 cm and 1 m. Mass, momentum and energy transfer studies are carried out by measuring the mass burning rate, flame length, flame temperature and radiation heat transfer across the liquid fuel and gaseous flame. It has been shown that comparatively much less mass of peroxy-fuels and pressure drop (required to maintained the flow) of fuel are required to produce a given heat flux. The momentum delivered by the peroxy-fuel vapours are order of magnitude higher than for hydrocarbons making the visibility of flame to be 4–5 times larger. A heat balance analysis shows that the total heat release rate of a peroxy-fuel fire is contributed equally by convection and radiation. Finally, the three E's (Efficiency, Economy and Emission) are discussed in the context of present experimental results followed by some recommendations concerning safe handling of the proposed fuels.
Data and predictions for the mass burning rates of di-tert-butyl peroxide (DTBP) pool fires (0.003 m < pool diameter < 3 m) are presented. The mass burning rates of DTBP fires are up to five times higher and are less dependent on pool diameter compared to hydrocarbon pool fires caused by an additional heat release rate due to exothermic decomposition reaction in the liquid phase. This heat release rate is calculated using a first-order reaction kinetic obtained from microcalorimetric measurements. A new model is derived considering the heat release rate due to the decomposition reaction, which is shown to be 40% of the heat release rate radiated to the pool surface. With the presented model, which also includes physical quantities, especially the limiting fuel concentration for upward flame propagation, it is possible to predict the mass burning rates of large DTBP pool fires. The predicted values are in very good agreement with the experiments.
Limiting distances for flame merging of multiple n-heptane and di-tert-butyl peroxide pool fires
(2013)
Experiments to determine the limiting distances for flame merging of multiple pool fires are presented. As model substances n-heptane and di-tert-butyl peroxide are used. Laboratory scale tests with a Diameter d = 6 cm and relative distances between the pools of 0.08 ≤ D/d ≤ 4 are described and complemented with field experiments with a diameter d = 1.5 m and relative distances between the pools of 0.17 ≤ D/d ≤ 1.
Three regions for flame merging are observed and limiting distances are determined. A merging Region with the limiting distance Dmerg/d within which all flames merge together over the complete burning time. A transition region with the limiting distance Dtran/d within which some flames merge together while other flames are separated from each other. A separated region within which all flames are completely separated from each other. A correlation against the number of burning pools is presented to predict the limiting distances Dmerg/d und Dtran/d.
Data and prediction for the mass burning rate of a tert-butyl-peroxy-benzoat (TBPB) pool fire (pool diameter = 3 m) is presented. The mass burning rates of TBPB fires are up to six times higher and less dependent on pool diameter compared to hydrocarbon pool fires caused by an additional heat release rate due to exothermic decomposition reaction in the liquid phase. This heat release rate is calculated using a 1st order reaction kinetic obtained from micro calorimetric measurements. A new model is derived considering the heat release rate due to the decomposition reaction which is shown to be 100 % of the heat release rate radiated to the pool surface. With the presented model, including also physical quantities, especially the limiting fuel concentration for upward flame propagation, it is possible to predict the mass burning rates of large TBPB pool fires. The predicted values are in very good agreement with the experiments.
Die thermische Zersetzung von AIBN wurde in einem Projekt mit mehreren Teilnehmern untersucht. Hierbei wurde die selbstbeschleunigende Zersetzungstemperatur SADT) sowohl experimentell als auf Grundlage von Simulationsrechnungen bestimmt. Die Besonderheit bei dem Feststoff AIBN ist, dass die Zersetzung sowohl in der festen, als auch in der flüssigen Phase nach dem Schmelzen stattfindet, was bei den durchgeführten Simulationsrechnungen berücksichtigt werden musste. Die berechneten SADT Werte stimmen mit den experimentell bestimmten sehr gut überein.
Das Abbrandverhalten und die thermische Strahlung von Poolfeuern organischer Peroxide (OP) wurden bereits in der Vergangenheit ausführlich untersucht. Dabei ergaben sich zum Teil erhebliche Unterschiede hinsichtlich der Abbrandraten, Temperaturen, Strahlungsintensitäten und Flammenlängen im Vergleich zu flüssigen Kohlenwasserstoffen. Das größere Gefahrenpotenzial von OP führt zu strikteren Sicherheitsbestimmungen für Lagerung und Transport. Da das Gefahrenpotenzial maßgeblich von den tatsächlich auftretenden Szenarien abhängt, ist eine Bewertung solcher Ereignisse unumgänglich um nachhaltig die Gesundheit von Mensch und Umgebung zu sichern. Ein Metallfass, gefüllt mit 200 Litern DTBP (Di-tertiär-butylperoxid), wurde auf dem Testgelände Technische Sicherheit der BAM einem Außenfeuer ausgesetzt. Durch den starken Wärmeeintrag erhöht sich die Massenabbrandrate des Peroxids um ein Vielfaches und das Fass entleert sich schließlich unter Ausbildung mehrerer Feuerbälle. Die Flammengröße, Flammentemperatur und damit die thermische Strahlung überschreiten die der gewöhnlichen OP-Poolfeuer. Die resultierenden höheren Sicherheitsabstände sind abschließend berechnet.
The industrial fire accidents e.g. Buncefield (2005) and Jaipur (2009) have come up with several issues concerning safe storage and transportation of flammable liquids. The pre and post fire consequences are therefore important to be analyzed prior to the handling of flammable fuels. Pool or/and tank fire is the most often seen scenario after the leak/spill of liquid fuel. An overview of the typical scenarios from large hydrocarbon and organic peroxide pool fires and their respective safety distances for the people and the infrastructure are the important subjects of this paper.
Combustion of peroxy-fuels
(2011)
Dampening of energetic properties and the effects of blending proportions of isododecane on the diffusive burning behaviour of peroxy-fuels are experimentally studied. Blended peorxy-fuels are obtained by adding isododecane in the proportions of 25 wt.%, 50 wt.% and 75 wt.%, respectively, in technical pure peroxy-fuels. The fuels were burned in form of pool fires with diameters 0.02 m ≤ d ≤ 1 m. The mass burning rates and relative flame lengths are found to be weakened with increasing diluent proportions. By measuring the mass burning rates and visible flame lengths of pool fires of different samples of fuel blends an optimum blending criterion is developed. Furthermore, it is shown that the dilution proportions and flame characteristics can be correlated by empirical equations.