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Eingeladener Vortrag
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Fire exposure tests of acetylene cylinders were performed. The purpose of the experiments was to gather information on the behavior in fire of such vessels, depending on the initial charge of acetylene. In fact "empty" acetylene cylinders still contain the solvent in which acetylene is dissolved plus the amount of acetylene to saturation at atmospheric pressure and ambient temperature and may still constitute a threat to safety. In the fire exposure tests performed the hazardousness of these vessels was demonstrated, since it was observed that not only fully charged acetylene cylinders but also cylinders with saturated solvent can explode, provided the heat transfer to the vessel is sufficient. The times to explosion were shorter for fully charged cylinders, due to the higher initial pressure and to the faster pressure increase. The effects of the explosions are comparable for both fully charged cylinders and for cylinders with saturated solvent, except for the smaller fireball which is produced in the second case, due to the smaller amount of fuel available. In both cases the cylinder walls or at least fragments can fly further than 100 m away from the burst location. Results of the experiments are presented in the paper. During the tests, temperature measurements at the cylinder walls and in the cylinder interior were performed. Furthermore, the pressure in the cylinder was recorded. The collected data will serve for the validation of a numerical model for the simulation of the heating of acetylene cylinders involved in fire and of the afterward cooling with water, which has been developed. The constitutive model equations and the results of some simulations are presented in the paper.
In order to prevent incidents in the
industrial production of Teflon® from
Tetrafluoroethylene (TFE), the safety related
aspects of the self-heating process of TFE must
be taken into account. Simulations of this self
heating process were performed with COMSOL
Reaction Engineering Lab® and COMSOL®
COMSOL Multiphysics®. A complex reaction
net was employed, resulting in a model allows
for a good agreement with experimentally
achieved results.
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.