Uma Contribuição ao Estudo do Processo de Separação em Ciclones Filtrantes

Abstract

The process of separation in a filtering cyclone is analogous to the phenomenological behavior in a conventional cyclone, however, the presence of the filter medium provides significant ow disturbances. Analyzing the process of separation in a filtering cyclone, it was found that permeability interferes on the fluid dynamic behavior and because some inconsistencies in the form of determination until then, was part of the objectives of this thesis the proposition of alternative methodologies to determine the permeability of the filter medium. This work was based on the study, analysis and understanding of the uid dynamic behavior in filtering cyclones. In research, we used experimental techniques and knowledge of computational fluid dynamics, for the better understanding of the complex process of separation in ltering cyclones. The main contribution of this study was to evaluate the length of the height of the feed, the permeability in the cone and the volumetric flow rate of feed, in order to study the fluid dynamic behavior inside the equipment. As laboratory experimental results, it was found that permeability is influenced by the geometric shape of the area, so that the methodology proposed in the thesis was the most appropriate, taking into account the geometric e ects and preserve the real features of the flow. With regard to the lab results, it was found that at high feed speeds the diference in separation efficiency of conventional and filtering cyclones was around 5 %. It was also evaluated the effect of injection of particles on pressure drop in filtering and conventional cyclones; in this case, both provided the decrease of pressure drop when you inject particulates. In relation to the numerical results were statistically analyzed the significance of independent variables in relation to the Euler number (Eu) and the reason of the filtrate (Rf ). It was found that the three analyzed variables were significant in the process in relation to the response variables. The results of numerical simulations have shown that the feed height was the variable that most interfered in the cyclone filter performance (Eu); about Rf the variable determinant was the permeability. In the case of the phenomenological behavior, the permeability presented significant effect on the tangential speeds profile for low flows rate containing a small cyclone feed height.