Self ignition of layers of powder mixtures: Effect of solid inertantsnext term

Autor: Bideau, D., Dufaud, O., Le Guyadec, F., Perrin, L., Genin, X., Corriou, J.P., Caleyron, A.
Přispěvatelé: Laboratoire des Procédés Avancés de Décontamination, Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire Réactions et Génie des Procédés (LRGP), Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS)
Jazyk: angličtina
Rok vydání: 2011
Předmět:
Zdroj: Powder Technology
Powder Technology, 2011, 209 ((1-3)), pp. 81-91. ⟨10.1016/j.powtec.2011.02.012⟩
Powder Technology, Elsevier, 2011, 209 ((1-3)), pp. 81-91. ⟨10.1016/j.powtec.2011.02.012⟩
ISSN: 0032-5910
DOI: 10.1016/j.powtec.2011.02.012⟩
Popis: International audience; Within the scope of risk assessment in the nuclear industries, the influence of alumina insertion on the previous termself-ignitionnext term behavior of zirconium previous termpowder layersnext term has been studied. A model, based on a set of partial differential equation describing the distribution of temperature and species concentrations and their evolution with time has been developed. Numerous experiments, both in static and dynamic modes, have been carried out in order to validate the model. They have notably allowed the identification of the oxidation kinetics, which is governed by the diffusion into the oxide previous termlayernext term and represented by Jander's model. The activation energy has been set at 97.5 kJ mol− 1. The experimental minimum previous termignitionnext term temperature of pure zirconium has been determined to be 213 °C, whereas the model leads to a value of 210 °C. It has also shown a good agreement with the tests performed both in static and dynamic modes at various alumina concentrations ranging from 0 to 90 wt.%. The average deviation obtained is 3.5%, which confirms the adequacy of the model. In static mode, a threshold-like behavior has been observed with a threshold level as high as 85 wt.%, whereas a more progressive increase has been obtained for the dynamic heating mode. A parametric study including especially the influences of previous termlayernext term porosity, oxygen partial pressure and previous termlayernext term dimensions has notably demonstrated the importance of the thermal effusivity and of the oxidation kinetics. The limitation due to the oxygen diffusion being predominant, the chemical reactions between nitrogen and zirconium could not be neglected in the lower part of the dust previous termlayers.next term This model allows a good visualization of the previous termignitionnext term process. Thus, it enables the estimation of the previous termignitionnext term delay and temperature, parameters which are essential to evaluate quantitatively the previous termignitionnext term risk of such previous termpowdersnext term and to propose adequate prevention and protection means.
Databáze: OpenAIRE
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