Filtern
Erscheinungsjahr
Dokumenttyp
- Vortrag (88)
- Zeitschriftenartikel (64)
- Beitrag zu einem Tagungsband (52)
- Beitrag zu einem Sammelband (9)
- Handbuch (5)
- Buchkapitel (3)
- Forschungsbericht (3)
- Sonstiges (1)
- Zeitschriftenheft (Herausgeberschaft für das komplette Heft) (1)
- Posterpräsentation (1)
Sprache
- Deutsch (116)
- Englisch (110)
- Mehrsprachig (1)
Schlagworte
- Pool fire (16)
- Organic peroxides (14)
- CFD (13)
- CFD simulation (11)
- SADT (11)
- Organic peroxide (10)
- Ammoniumnitrat (9)
- DTBP (9)
- Safety distances (9)
- Explosion (8)
Organisationseinheit der BAM
Eingeladener Vortrag
- nein (88)
Single and multiple fireballs of di-tert-butyl peroxide are numerically investigated using ANSYS CFX. Calculations contain varying inlet conditions, scale-adaptive shear stress turbulence modeling and one-step combustion reaction on a three-dimensional hexahedral mesh. Time-resolved flame temperatures, sizes and thermal radiation are compared to experimental results. There, fireballs were generated by fire engulfment of steel drums containing 200 l substance. After a vigorous burning, the remaining peroxide forms single and multiple fireballs involving 10 % to 20 % of the initial amount. The comparison of all simulations and two selected experiments show the special numerical treatment required for organic peroxides. Finally, the numerical predictions of irradiance in 30 m distance to the fire show a good agreement for both experiments. This proves the use of CFD as an appropriate method for thermal hazard assessment and the prediction of safety distances for organic peroxide fireballs.
To simulate a full fire engulfment during transportation or storage a closed removable head steel drum filled with 200 l Di-tert-butyl peroxide (DTBP) is subjected to a wood fire. Due to the enormous heat flux and the exothermic self-decomposition large flames arise and finally multiple fireballs occur. The fireballs consume up to 20 % of the total mass (20 % equals to 31 kg). They are characterized by high surface emissive power and large flames associated with high thermal radiation causing spontaneous ignition of objects in the surrounding. The measured sizes of the DTBP fireballs are smaller compared to the results of the general equations for hydrocarbon fireballs. Because these equations are recommended by the Health and Safety Executive (UK) to be applicable for organic peroxides explicit comparisons of DTBP with LPG, diesel and gasoline concerning the characteristics of fireballs are carried out. Also the burning time is compared and confirms a faster combustion of the peroxide. Moreover, the development of size and emissive power for DTBP and diesel fireballs are compared in a normalized graph. The results provide the assumption that new empirical models are required to be developed for hazard assessment of organic peroxide fireballs.
Fireballs of liquid organic peroxides differ from those of liquid hydrocarbon fuels. Modified equations for predicting the fireball diameter, height, surface emissive power and the duration in dependence of the fuel mass are presented for di-tert-butyl peroxide. They base on 13 steel drum tests with fuel masses from 10 kg to 168 kg. Moreover, computational fluid dynamics simulations are performed using the laminar flamelet approach and a statistically turbulence treatment. Fireballs involving peroxide from 10 kg to 80 kg were simulated and their properties compared to the experimentally developed models. The deviations of each property are partially compensating each other leading to an adequate prediction of thermal safety distances for both, a time-independent and a time-averaged treatment. Simulations prove to be a good tool for predicting thermal radiation hazards of fireball scenarios.
The burning behaviour and thermal radiation of pool fires of organic peroxides (OP) have been studied by several authors in the past. It was shown that mass burning rates, flame temperatures and thus the Surface Emissive Power (SEP) of OP exceed to that of hydrocarbons considerably. These facts lead to further investigations of even dangerous worst case scenarios i.e. related to storage and transportation. A metal drum containing 200 l of DTBP (Di-tert-butyl peroxide) is investigated under a surrounding wood fire. Due to a higher heat flux to the substance, the mass burning rate reaches multiples of an equivalent pool fire and results in several fireballs. The analyses of thermographic camera images and radiometer measurements show higher flame lengths, higher temperatures and thereforeincreased thermal radiation compared to OP pool fires. The resulting greater safety distances for a DTBP fireball event are discussed.
A large number of azodicarboxylates and their derivatives are produced and used in the chemical industries. The versatile applications of these azodicarboxylates in research institutes and in the chemical industries for chemical synthesis arouse additional hazards. The intent of this paper is to obtain first knowledge about the structure–response relationship regarding the explosive properties and the thermal hazards of different versatile used azodicarboxylates. The substances are examined with the differential scanning calorimetry (DSC). Furthermore, different laboratory test methods, based on the UN Recommendations on the Transport of Dangerous Goods, are applied to determine the explosive properties of the mentioned substances. On the basis of the obtained results, the known influence of the nitrogen content within the molecule regarding their thermal behaviour could be confirmed. The measured heat of decomposition appeared to be proportional to the nitrogen content within the group of the aliphatic and the aromatic azodicarboxylates. To emphasize this dependency, further investigations should be done. The long term objective of this research is to develop structure–response relationships of the explosive properties and the thermal hazards originating from azodicarboxylates.
A large number of Azodicarboxylates and their derivatives are produced and used in the chemical industries. The versatile applications of these Azodicarboxylates in research institutes and in the chemical industries for chemical synthesis arouse additional hazards. The aim of this paper is to obtain a predication about the structure-response relationship regarding the explosive properties and the thermal hazards of different versatile used Azodicarboxylates. The substances were examined with the Differential Scanning Calorimetry (DSC). Furthermore, different laboratory test methods, based on the UN Recommendations on the Transport of Dangerous Goods, were applied to determine the explosive properties of the mentioned substances.
The classification of solid oxidizers according to the regulations on the transport of dangerous goods (based on the UN Recommendations/Model Regulations and accepted by all international organisations for the transport of dangerous goods as ADR, IMO, IATA) and in future also according to the GHS (Globally Harmonized System of Classification and Labelling of Chemicals) is performed on the basis of the results of the UN test O.1 (UN test O.1 ―Test for oxidizing solids‖ described in chapter 34.4.1 in the Recommendations on the Transport of Dangerous Goods – Manual of Tests and Criteria, see [1]). This test was introduced into the UN Manual of Tests and Criteria in 1995 as a replacement for a similar test from 1986. Even if the UN O.1 test as described in the current 5th revised edition of UN Manual of Tests and Criteria gives some improvements compared to the old test, which had had many deficiencies, there are still some problems left with this test in terms of e.g. repeatability or reproducibility of test results, how to handle compacted or multilayer formulations like tablets, toxicity and partly significantly varying particle size distribution within defined fractions of 150 μm to 300 μm of the reference oxidizer potassium bromate (KBrO3). For this reason the IGUS EOS working group installed an ad-hoc working group in 2002 assigned with the task to propose solutions for the existing problems. The appropriateness of such proposed solutions has to be proved by the method of interlaboratory (round robin) tests before they are presented for the adoption to the UN Committee of Experts on the TDG and on the GHS with a proposal of a completely revised test procedure.