Uma contribuição ao estudo do escalonamento de ciclones

AUTOR(ES)

Marcos Donizete Lopes

DATA DE PUBLICAÇÃO

2003

RESUMO

The use of models in scale is a practical way of studying how the operational parameters influence the performance of industrial cyclones. The model and the prototype cyclones should be built according to a scaling law - given by a set of dimensionless parameters --, so that they are similar. It there will be fluid-dynamical similarity between the cyclones if they are geometrically similar and the sets of corresponding dimensionless parameters are equal. A group of dimensionless parameters which represent the gas-solid flow phenomenon in cyclones should consider interpartic1e forces, such as the van der Waals and the electrostatic forces. However, as it would be quite difficult to comply with a scaling law determined from taking into consideration these forces, it was decided not to include them and check the range of applicability of the simplified set. Moreover, during the tests, all the dimensionless parameters were made equal, with the exception of the Reynolds number, because, for practical reasons, atmospheric air was used in the tests for both prototype and model cyc1ones, what is equivalent to neglect the viscous forces as compared to the inertial forces. The present work showed that when the model and prototype cyclones were operating at the corresponding velocities and with the same solids concentration at the inlet, similarity was obtained between the collection efficiencies when the solids concentration was less than 1.0 kg/kg, meaning that the proposed methodology was appropriate, that is, that the forces not included were not significant and could be neglected. Concerning the pressure drop in the cyclones, it was observed that the ratio of the pressure drop, Dp, by the pressure drop in the cyclone with no solids, was more appropriate than the ratio Dp/romo2; for expressing similarity, maybe because the entrance velocity, mo, is not the best velocity to be used as a scaling parameter

ASSUNTO(S)

separadores (maquinas) escoamento bifasico van der waals forças de

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