TY - CONF A1 - Schälike, Stefan A1 - Mishra, Kirti Bhushan A1 - Ziemann, Sylvia A1 - Wehrstedt, Klaus-Dieter A1 - Schönbucher, A. ED - Beyer, M. ED - Stolz, T. T1 - Massenabbrandraten organischer Peroxide unter besonderer Berücksichtigung der thermischen Stabilität N2 - Die Flüssigkeitstemperatur Temperatur in der flüssigen Phase unmittelbar im Grenzbereich zur Gasphase während eines Abbrandes organischer Peroxide überschreitet die Onset-Temperatur der beginnenden exothermen Zersetzungsreaktion des Peroxids, so dass diese zu berücksichtigen ist. Für die Peroxide Di-tert-butyl-Peroxid (DTBP) und tert-butyl-peroxybenzoat (TBPB) muss daher bei der Berechnung des Wärmerückstromes ein zusätzlicher Term für die Zersetzung in der Flüssigkeit additiv ergänzt werden. Der Umsatz der Zersetzungsreaktion wird unter den Bedingungen eines CSTR modelliert und erfolgt auf Basis einer Reaktionskinetik 1. Ordnung. Es kann gezeigt werden, dass der Wärmestrom in einem DTBP-Poolfeuer ≈ 40 % und einem TBPB-Poolfeuer ≈ 100 % des Wärmerückstromes durch Wärmestrahlung entspricht. Durch Q-Punkt-d können die vergleichsweise hohen Massenabbrandraten und die relative Unabhängigkeit der Massenabbrandraten vom Pooldurchmesser erklärt werden. Über eine Energiebilanz wird ein Modell basierend auf physikalischen Parametern entwickelt, das die Massenabbrandraten großer Poolfeuer, in sehr guter Übereinstimmung mit den experimentellen Ergebnissen, vorhersagt. T2 - 13. BAM-PTB-Kolloquium zur chemischen und physikalischen Sicherheitstechnik CY - Braunschweig, Germany DA - 18.06.2013 KW - Poolfeuer KW - Massenabbrandrate KW - Organische Peroxide KW - Thermische Stabilität KW - Onset-Temperatur PY - 2013 SN - 978-3-95606-062-5 DO - https://doi.org/10.7795/210.20130801E SN - 1868-5838 SP - 40 EP - 47 AN - OPUS4-29815 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mishra, Kirti Bhushan A1 - Wehrstedt, Klaus-Dieter A1 - Krebs, Holger T1 - Amuay refinery disaster: The aftermaths and challenges ahead N2 - Amuay refinery disaster (2012) is another recent example of Vapor Cloud Explosion (VCE) and fire accidents preceded by Buncefield (2005), Puerto-Rico (2009) and Jaipur (2009), respectively [9]. The incident has left many safety issues behind which must be repeatedly addressed. Unfortunately, the lessons taught by previous similar events are just not understood carefully. It reveals that the proper safety measures for such facilities were either underestimated or were not accounted seriously. Consequently, the resulting overpressures from explosion and the subsequent thermal radiation from tank fires have once again proved to be disastrous to both mankind and infrastructure. This article highlights the aftermaths of Amuay incident and addresses the challenges put forward by it. Furthermore, a comparative study is performed between such incidents to analyze the similarities and how they could have been avoided. KW - Refinery disaster KW - Vapor cloud explosion KW - Fire KW - Safety distance KW - Overpressure KW - Radiation PY - 2014 DO - https://doi.org/10.1016/j.fuproc.2013.10.025 SN - 0016-2361 SN - 0378-3820 SN - 1873-7153 VL - 119 SP - 198 EP - 203 PB - Elsevier CY - Amsterdam AN - OPUS4-29816 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - THES A1 - Mishra, Kirti Bhushan T1 - Experimental investigation and CFD simulation of organic peroxide pool fires (TBPB and TBPEH) N2 - Time averaged mass burning rate (m˙′′f ), flame length (H), temperature (T ), irradi- ance (E) and surface emissive power (SEP ) of TBPB (tert -butyl peroxybenzoate) and TBPEH (tert-butyl peroxy-2-ethylhexanoate) pool fires are measured for six pool di- ameters (d = 0.059 m, 0.107 m, 0.18 m, 0.5 m, 1 m and 3.4 m) at BAM in house and outside test facility. The measured heats of combustion (–Δhc) of TBPB and TBPEH are 30113 kJ/kg and 34455 kJ/kg and the specific heat capacities at constant pressure (cp) are 1.8 kJ/(kg K) and 2.1 kJ/(kg K) respectively. The measured m˙′′f of TBPB and TBPEH pool fires are in the range of 0.37 kg/(m2 s)≤ m˙ ′′ f ≤ 0.83 kg/(m2 s) and show little dependence on the pool diameter d, and are four to sixty times higher (for d = 1 m) than that of hydrocarbon pool fires. It is shown that the mass burning rates of the investigated organic peroxides can be represented as an exponential function of the self-accelerating decomposition temperature (SADT). Low SADT implies that the organic peroxide pool fires burn at a much higher m˙′′f than hydrocarbon pool fires. Fuel Froude numbers (Frf) of TBPB and TBPEH are 5 to 100 times (depending on d) higher than for hydrocarbon pool fires. Due to higher Frf the H of TBPB and TBPEH (measured with a S-VHS Videocamera) are found to be two times larger (d = 1 m) than corresponding pool fires of hydrocarbons. Heskestads flame length correlation predicts the Hd (d = 3.4 m) of TBPB and TBPEH pool fires much better than Thomas and Fay correlations. The measured time averaged flame temperatures T (d = 3.4 m) for TBPB and TBPEH pool fires are in the range of 1400 K ≤ T ≤ 1500 K and are 200 K to 300 K higher than for JP-4, kerosene and gasoline. The irradiances of the TBPB and TBPEH pool fires measured by radiometers are E (Δy/d = 0.3) = 45 kW/m2 and E = 98 kW/m2 which are two to ten times higher in comparison to the corresponding n-pentane, super gasoline and diesel pool fires. So the thermal safety distances for organic peroxide pool fires are larger by a factor four in comparison to the hydrocarbon pool fires. An infrared thermography system is used for the determination of SEP of TBPB and TBPEH pool fires. The values of surface emissive power for TBPB and TBPEH are SEP (d = 3.4 m) = 196 kW/m2 and SEP = 258 kW/m2 and thus the SEP are by a factor of approximately two higher than for hydrocarbon pool fires. A self-sustained pulsating Hd (’W’-Effect) is found in TBPB pool flames and is further analysed to explain the reason of occurance on the basis of chemical structure of the fuel and discontinuous heat flux back from flame to the liquid pool. CFD simulations of TBPB and TBPEH pool fires at d = 0.18 m, 0.5 m, 1 m, 3.4 m and 8 m are carried out using the Unsteady Reynolds Averaged Navier Stokes (URANS) equa- tions. The three-dimensional geometries have been discritized with unstructured hybrid grids, with the number of cells in the range of 1 million. Depending on the grid resolu- tion and the pool diameter time steps of 0.0001 s ≤ Δt ≤ 0.01 s for the CFD simulations are used. For solving the discritized equations a finite volume based implicit solver AN- SYS CFX has been used. For modelling the combustion, stoichiometric combustion for both peroxides are assumed. The temperature dependence of the reaction rate has been determined by the Arrhenius approach. For modelling the combustion eddy dissipation concept (EDC) model has been used. For turbulence buoyancy modified k- � and SAS (Scale Adaptive Simulation) turbulence models are used. For the thermal radiation and soot mass fraction discrete transfer radiation model and Magnusson soot model have been used. A new method is suggested for the prediction of mass burning rate (m˙′′f ) by CFD simula- tion. Both peroxide pool fires show approximately constant mass burning rate indepen- dent of d whereas m˙′′f of TBPEH are under predicted at the beginning but show relatively good agreement with measurements for large pool diameters (d = 1 m). In case of TBPB the CFD simulation over predicts the mass burning rate m˙′′f of small TBPB pool fires and shows a continuous decrease with d. CFD predicts the flame length H close to the measured data provided that the constants in Thomas equation are modified. The CFD predicted time averaged surface emission flame temperatures of TBPB and TBPEH pool fires (d = 3.4 m, 1437 K and 1542 K) are in good agreement with the measured time averaged flame temperatures. The CFD predicted SEP for TBPB and TBPEH pool fires (d = 3.4 m, 217 kW/m2 and 288 kW/m2) are also in agreement with the measured values. From the CFD predicted irradiance ECFD it is possible to determine the thermal safety distances from large pool fires of hydrocarbons and organic peroxides. T3 - BAM Dissertationsreihe - 63 KW - Pool fires KW - organic peroxides flame characteristics KW - safety distance KW - CFD simulation PY - 2010 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-950 SN - 978-3-9813550-6-2 SN - 1613-4249 VL - 63 SP - 1 EP - 150 PB - Bundesanstalt für Materialforschung und -prüfung (BAM) CY - Berlin AN - OPUS4-95 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mishra, Kirti Bhushan A1 - Wehrstedt, Klaus-Dieter A1 - Krebs, Holger T1 - Boiling liquid expanding vapour explosion (BLEVE) of peroxy-fuels: Experiments and computational fluid dynamics (CFD) simulation N2 - 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. KW - BLEVE KW - Hydrocarbons KW - Peroxy-fuels KW - Safety distances KW - CFD simulation PY - 2015 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-334184 DO - https://doi.org/10.1016/j.egypro.2015.02.082 SN - 1876-6102 VL - 66 SP - 149 EP - 152 PB - Elsevier Ltd. CY - Amsterdam AN - OPUS4-33418 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mishra, Kirti Bhushan A1 - Wehrstedt, Klaus-Dieter T1 - Decomposition effects on the mass burning rate of organic peroxide pool fires N2 - The mass burning rate of pool fires of organic peroxides do not vary appreciably with the pool size as have been observed for the hydrocarbons. Instead the decomposition temperature largely controls the same. The dependence of mass burning rate on the decomposition temperatures namely self-accelerating decomposition temperature (SADT) and extrapolated onset temperature measured by differential scanning calorimetry (DSC) for organic peroxide pool fires are identified and correlations are developed. KW - Decomposition KW - SADT KW - Pool fire KW - Mass burning rate KW - Organic peroxides KW - DSC PY - 2012 DO - https://doi.org/10.1016/j.jlp.2011.06.014 SN - 0950-4230 SN - 1873-3352 VL - 25 IS - 1 SP - 224 EP - 226 PB - Butterworth CY - Guildford, Surrey AN - OPUS4-25020 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mishra, Kirti Bhushan A1 - Wehrstedt, Klaus-Dieter T1 - CFD simulation of hybrid fuel combustion N2 - CFD (Computational Fluid Dynamics) simulation results of hybrid fuel combustion i.e. one hydrocarbon and one peroxy-fuel in an industrial burner are reported. The addition of one of the most stable peroxy-fuels (Di-tert-butyl peroxide, DTBP) in one reference hydrocarbon fuel i.e .in methane is studied. Both fuels are assumed to be in the gas phase and are mixed in form of a multi component mixture. The content of peroxy-fuel in methane is varied between 5 % to 50 %. CFD results indicate that the addition of DTBP (> 10 %) drastically enhance the reaction rates of methane and hence ensure an efficient combustion. It is also found that 50 % of DTBP addition doubles the reaction rate which helpsto burn the entire fuel in a relatively smaller volume of the chamber and leads to an economical processing of the material. The influences of the same on NOx production are also discussed. T2 - NCFMFP 2012 - 39th National conference on fluid mechanics and fluid power CY - Surat, Gujarat, India DA - 13.12.2012 KW - CFD KW - Hybrid fuel KW - Hydrocarbon KW - Peroxy-fuel KW - Combustion PY - 2012 SN - 978-81-925-494-0-8 DO - https://doi.org/10.13140/2.1.2528.3205 IS - FMFP2012 - 209 SP - 1 EP - 7 AN - OPUS4-27587 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mishra, Kirti Bhushan A1 - Wehrstedt, Klaus-Dieter A1 - Krebs, Holger T1 - Lessons learned from recent fuel storage fires N2 - Industrial fire and explosion hazards due to accidents in fuel storage units have gained a considerable attention in the recent times. Both the regulatory bodies and scientific communities are heavily concerned about the proper safety measures to avoid such calamities in future. This paper aims to bring some essentials related to the hazards arose from the recent fuel storage fire accident occurred in Buncefield, UK (2005), Puerto Rico, USA (2009) and Sitapura, India (2009). The potential similarities behind occurrence of these accidents are studied. The applicability of various methods (models) and also computer simulations to estimate the safety distancesaccording to the international standards for both explosion and fire hazard are verified. Theoverpressures caused by the Vapor Cloud Explosion (VCE) and radiation flux emitted by the fireare considered for respective explosion and fire hazard estimations. The prime focus is placedon the regulations laid down by the National Fire Protection Agency of the United States and the European Norms. T2 - ICCEU 2012 - 11th International conference on combustion and energy utilization CY - Coimbra, Portugal DA - 09.05.2012 KW - Industrial fires KW - Storage units KW - Safety measures KW - Explosion KW - Overpressure KW - CFD simulation PY - 2012 SP - 1 EP - 10 AN - OPUS4-26186 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mishra, Kirti Bhushan A1 - Wehrstedt, Klaus-Dieter T1 - CFD modeling of spill characteristics of flammable liquids N2 - Present work deals with safe storage and transportation of flammable liquids. A flammable liquid can spill as a result of an overflow, leakage, failure of mechanical parts, mistakes by personnel or some deliberate acts. If the spilled fuel finds an ignition source depending on flammability limits a pool fire develops. The fire and spill continue until steady state conditions are achieved. Under such conditions a steady state diameter of spill (pool) can be established. However, this theoretical diameter is based on the assumption that the volumetric spill and burning rates are equal. Determination of spill size (D) independent of burning rate (or if there is no burning) is not reported as such in the existing literature. We develop a Computational Fluid Dynamics (CFD) model to predict the spill size which is independent of burning rate and is based on the definition of overflow Reynolds number (Re). By changing Re different spill scenarios can be predicted. Here five cases with Re = 100, 500, 1000, 2000 and 2500 are considered. One liquid hydrocarbon (Jet A) and one organic peroxide (DTBP: di-tert butyl peroxide) spill are simulated. The model considers two phases i.e. air as a continuous phase and liquid fuel as a dispersed phase. Fig. 1 shows such predicted spill sizes for DTBP for five overflow Reynolds numbers. The spill characteristics of Jet A and DTBP found to be similar for a defined Reynolds number. A correlation between spill size and overflow Reynolds number is also established. In order to estimate the spill diameter and the height of vapor cloud the explosion limits of air-fuel mixtures are taken into consideration. The model makes it possible to estimate the spill characteristics of a wide variety of flammable liquids. T2 - 22nd Journées d´Etudes of the Belgian section of the combustion institute CY - Heverlee, Belgium DA - 11.09.2012 KW - Flammable liquids KW - Spill characteristics KW - CFD modeling KW - Overflow Reynolds number KW - Jet A KW - DTBP KW - Vapor cloud PY - 2012 SP - 18 EP - 19 AN - OPUS4-27924 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Mishra, Kirti Bhushan A1 - Wehrstedt, Klaus-Dieter T1 - Applications of peroxy-fuels in vehicle propulsion N2 - The combustion of petroleum derived conventional fuels (diesel, gasoline etc.) takes place relatively at a slower rate. In many applications they are forced to combust faster in order to match the specific power/output requirement. To accelerate the combustion process fuel (and oxidiser) supply has to be correspondingly increased by some means. These imply the necessity of high pressure fuel feed pump, air compressor (super or turbo charger) and a large volume of chamber to combust these mixtures. As an outcome the overall compactness of the vehicle declines. Furthermore, as an additional consequence in form of emissions e.g. COx and NOx occur as a result of fast combustion of fuel and air, We investigate combustion of a dass of energetic materials commonly known as organic peroxides (or peroxy-fuels) as a main fuel in vehicle propulsion. Peroxy-fuels are typically known as reaction enhancer’s, polymerizing agents and cross linkers. Sometimes, they have been also utilised in small amounts (1% to 5%) to conventional fuels successfully. It was found that combustion process was improved and emission was drastically turned down. Therefore, they are termed as combustion improvers as well. Also it was shown that with a peroxy-fuel an engine can be run anaerobically. T2 - COMBURA 2012 - Combustion research and application CY - Maastricht, The Netherlands DA - 03.10.2012 KW - Peroxy-fuels KW - Vehicle propulsion KW - Pool flame KW - Internal combustion engine PY - 2012 SP - 49 EP - 50 AN - OPUS4-26821 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -