Mecânica dos fluidos computacional aplicada aos separadores dinâmicos de primeira geração da indústria cimenteira

Abstract

The industrial cement manufacture process is a combination of chemical, mechanical and thermal steps. It starts on mining activities, and, passes through crushing, grinding, raw meal homogenization, clinquerization, dosing systems to finish with cement grinding and packing. The cost associated to electrical energy corresponds to 15% of total production cost, 11.6% of which come from grinding operation. In the ideal grinding process every particle from mill feed that achieves required size goes direct to final product stream, hence the energy consumption is exclusively related to big particles breaking. Once in the real grinding systems it is not possible, mechanical separators are applied to control the size of final product particles. Dynamics separators works by a principle to promote a uniform dispersion on air flow stream. Particles are classified according to the equilibrium of drag force, due to air flow, and centrifugal force, due to air rotation, acting direct on the particles. The goal of this study is to apply CFD (Computational Fluid Dynamics) for an internal flow assessment of dynamic separation of first generation, in order to determine the effects of rotating and static components and to identify potential by-pass reduction and product fineness control strategy based on geometry modifications. A numerical simulation of separator internal flow had indicated that taking off whizzers separation efficiency could increase. And when separator operates without whizzers more benefits had been proven as reduction of 20% in by-pass, reduction of R$ 0.30/ton produced in the operational cost and reduction in the standard deviation of 90m residues.