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Eingeladener Vortrag
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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.
Most of the measurements of temperatures in large pool fires are indirect and present a number of complexities due to the interactions of convection, radiation and soot blockage. In the present work these influences for two organic peroxide [tert-butyl peroxybenzoate (TBPB) and tert-butyl peroxy-2-ethylhexanoate (TBPEH)] pool fires are analysed.
Thermocouple measured temperature in the clear flame zone i.e. combustion zone are found to be 250-400 K lower than from the thermographic measurements. The convective and radiative heat flux contributions from the fire on temperature measurements are discussed. CFD (Computational Fluid Dynamics) simulations have been performed for large pool fires and the predicted time averaged flame temperatures were found to be in qualitative agreement with
measurements due to the stoichiometric combustion model used in the present simulations.
The use of energetic materials as a main fuel in high temperature process
industries are not known to the scientific community as such. This paper
highlights some of the features and advantages of using organic peroxides
especially di-tert-butyl peroxide (DTBP) in high temperature process industries.
The feasibility of using DTBP as a main or supporting fuel in process industries
have also been justified with the help of Computational Fluid Dynamics (CFD)
simulations. For peroxides requirement of less fuel and air for the same amount
of heat flux has been shown. The resulted emission from the combustion of
DTBP is also discussed.
Combustion of peroxy-fuels
(2011)
The diffusion flames of organic peroxides exhibit quite different characteristics than hydrocarbons. What makes them interesting to study is their fast burning behaviour. As a result the flame temperature enhances and so does the thermal radiation. Due to all these they demand safe handling during processing. However, they can be utilised at several places in different industries where a fuel with fast burning, high temperature and intense radiation are desired. Some of the possibilities to use them as a main or supporting fuel in a wide range of industrial utilities are the major content of this paper.
A new burner concept (PEROXY-BAM®) for the combustion of liquid organic peroxides (Peroxy-fuels) is presented. As peroxy-fuels are thermally unstable the design of burners for them should be accordingly modified ensuring a safe operation. It is found that 10 to 100 time less amounts of peroxy fuels are required for the same heat flux or output in comparison to hydrocarbons. Correspondingly, the fuel pump power and the volume of combustion chamber (furnace) are also reduced. As a result of less amount of fuel the emissions will also be stepped down and oxygen in the molecule helps to establish conditons like in an oxy-fuel combustion process. The advantages of using peroxy-fuels over hydrocarbons inside a model combustion chamber are also investigated with the help of CFD (Computational Fluid Dynamics) simulations.
new burner concept for peroxy-fuels is proposed. The performance of the proposed peroxy-fuel burner is predicted with the help of Computational Fluid Dynamics (CFD) simulation. It is found that peroxy-fuel burner not only requires considerable less amount of fuel for the same output/power but also at the same time the overall size of the processing unit can be reduced. As peroxy-fuels contain oxygen atoms within the molecule itself a similar to oxy-fuel combustion environment is created without even supplying pure oxygen. CFD simulations also support the above facts and demonstrate the existence of less favorable conditions to form NOx.
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.