-In this work a new mechanical device to improve the gas flow in cyclones by pressure drop reduction is presented and discussed. This behavior occurs due to the effects of introducing swirling breakdown phenomenon at the inlet of the vortex finder tube. The device consists of a tube with two gas inlets in an appositive spiral flux that produces a sudden reduction in the tangential velocity peak responsible for practically 80 % of the pressure drop in cyclones. In turn, peak reduction causes a decrease in pressure drop by a breakdown of the swirling, and because of this the solid particles tend to move faster toward the wall , increasing collection efficiency. As a result of this phenomenon the overall performance of cyclones is improved. Numerical simulations with 3-D, transient, asymmetric and anisotropic turbulence closure by differential Reynolds stress for Lapple and Stairmand standard geometries of 0.3 m in diameter, show a reduction in pressure drop of 20 % and a shift of the tangential velocity peak toward the wall. All numerical experiments were carried out with a commercial CFD code showing numerical stability and good convergence rates with high-order interpolation schemes, SIMPLEC pressure-velocity coupling and other numerical features.

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The purpose of this work is to present a new code, the CYCLO-EE 3 , which is based on computational fluid dynamics (CFD) techniques. The model used is based on the Eulerian-Eulerian approach and it is composed of several time differential equations in a 3-D-space domain with a 3-D symmetric cyclone inlet. The solid phase is treated like a hypothetical fluid and drag forces between phases are responsible for the gas-solid interaction. The CYCLO-EE 3 code makes possible the use of up to three solid phases, each one with size of particle, density and specific volumetric fraction. The mathematical model is completed using a hybrid turbulence model composed of the combination of the (k-ε) standard model and Prandtl's longitudinal mixing model to represent the turbulence of the gas phase. The model is solved using the finite volume method with staggered grids in the cylindrical coordinate system. The numerical results allowed prediction of the pressure drop and the collection efficiency as well as the complete fluid dynamic behavior of the gas-solid flow for the cyclone. The collection efficiency and pressure drop from an experimental study reported by literature were used to validate the model. A comparison between the experimental data and the numerical results shows that the CYCLO-EE 3 code predicts the results well.

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