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- 2011 (8) (entfernen)
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- Acetylene (1)
- Berstdruck (1)
- Chemically unstable gases (1)
- Chemisch instabile Gase (1)
- Decomposition (1)
- Druckefestigkeit (1)
- Explosion (1)
- Explosion control (1)
- Explosion limits (1)
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Eingeladener Vortrag
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Acetylenflaschen im Feuer
(2011)
In connection with the use of chemically unstable gases (especially acetylene and ethylene oxide) accidents keep on happening - amongst them also quite serious ones. These gases are known to be chemically unstable. A chemically unstable sas is a flammable gas that is able to react exolosivelv even in the absence of air or oxveen. The investigation of accidents showed that the Chemical instability of flammable gases played an important role in the severity of accidents. Therefore, this hazardous property was included in the global harmonizatiön of the Classification of Chemicals. The Classification of chemically unstable flammable gases and mixtures is an amendment to Chapter 2.2 “Flammable gases” of the UN Globally Harmonized System of Classification and Labelling of Chemicals (GHS), because most chemically unstable gases are flammable as well. The proposal to add them to the GHS originated from the experts of an informal working group of the UN Sub-Committee of Expert on the GHS (UNSCEGHS) headed by BAM, Germany. The UNSCEGHS has decided to include it in the Fourth Revised Edition of the GHS. The respective method for determining whether a gas is chemically unstable or not, is included in the UN Manual of Tests and Criteria. This paper presents some experimental investigations of these gases, the test methods, examples of new classifications and results from CHEMSAFE
Prevention of the explosion of acetylene cylinders involved in fire: experiments and simulations
(2011)
In order to assess the effectiveness of water cooling of acetylene cylinders involved in fire, a total of 13 bonfire tests with 8.9-, 10
and 50-l-cylinders were performed. During the experiments the pressure
in the cylinder and the temperature at different locations within the porous material and on the Shell surface as well as the flame temperature were measured. Overall 8 burst tests were performed, in order to determine the times to explosion for the cylinders. Cylinders failed not later than 15 minutes from the ignition of the bonfire, often with generation of a fireball. During the other 5 tests, the fire was extinguished before the expected burst and the cylinder was cooled with water. In 2 of the 5 extinction experiments, the explosion of the cylinder could be prevented. Noticeably, in one case the on-set of the decomposition of acetylene had already been observed, before the cooling was started. In spite of that, the cooling was still effective. The interpretation of the current results and of the data from previous tests with 40-l-cylinder suggests that single acetylene cylinders involved in fire might be saved by cooling, if their pressure does not exceed a value of about 45 bara. The recorded values of pressure and temperature were used to develop and validate a mathematical model for the prediction of the heat transfer in acetylene cylinders during the exposure to fire and the afterward cooling. The predictions agreed well with the experimental results.
In Gasphasen aus Ethylenoxid (EO) und Propylenoxid (PO), die bei technischen Alkoxylierungsreaktionen vorkommen, können auch ohne den Zutritt von Luft Zerfallsreaktionen stattfinden, die explosionsartig mit einer vielfachen Temperatur- und Drucksteigerung verlaufen. Zur Abschätzung der Auswirkungen solcher Explosionen wurden die Explosionsdrücke und die zeitlichen Druckanstiege von reinem EO und EO/PO-Gemischen bei Temperaturen von 100°C bis 200°C und Drücken von 1 - 10 bar in einem 3-dm³-Behälter und punktuell in einem 100-dm³-Behälter experimentell bestimmt.
Self-ignition behavior of mixtures of methane and oxygen was investigated in a temperature range from 600 to 800°C. Variations of mixture composition, inert gas content, temperature and filling rate of the ignition autoclave were carried out in order to establish process boundaries for high temperature partial oxidation processes. The tests show that considerably high methane contents are needed to avoid an ignition. Heating-up tests show that ignition is possible at surprisingly low temperatures. This can be attributed to pre-ignition reactions that produce more instable intermediates.
Ein entscheidendes Problem neuer Wasserstofftechnologien ist die leichte und sichere Lagerung ausreichender Mengen an Wasserstoff insbesondere für Nutzung bei tragbaren oder mobilen Anwendungen. Eine neue und innovative Technologie basierend auf gebündelte Kapillaren wurde entwickelt. Diese Systeme garantieren eine sichere Speicherung, Lagerung und kontrollierte Freisetzung von Wasserstoff, obgleich Speicherdrücke bis 1200 bar angewendet werden. Die neue Technologie ermöglicht die Lagerung einer erheblich größeren Menge Wasserstoff als andere Systeme und übertraf bereits die Zielsetzung des DOE 2010. Es wird erwartet, die DOE-Zielsetzung für das Jahr 2015 bereits in naher Zukunft zu erreichen. Hauptaspekt für die Speichertechnologie ist die Druckfestigkeit der Glaskapillaren. Es ist weithin bekannt, dass besonders Quarz eine dreimal höhere Festigkeit als Stahl hat. Gleichzeitig ist die Dichte ungefähr dreimal niedriger, was bedeutet, dass viel weniger Material notwendig ist, um die gleiche Druckfestigkeit zu erreichen. Die Druckfestigkeit einzelner Kapillare ist in der Abhängigkeit der Materialien, der Abmessungen, der Wandstärke etc. ermittelt worden, um optimale Parameter für die "finalen" Kapillaren herauszufinden.