Applications of CFD Techniques in the Design of Fabric Filters

Abstract

Analyzing the gas flow inside a bag filter experimentally is a difficult challenge to overcome, since the complexity of the highly three-dimensional flow hinders any form of directly measuring the flow. In recent years, the increasing availability of computational resources together with the increasing accuracy of numerical methods built up techniques that describe the flow of fluids in industrial equipments through mathematical modelling and numerical simulations. Among these techniques, Computational Fluid Dynamics (CFD) is noteworthy regarding the design of new equipment, since it uses experimental data in their simulations. In this work, the CFD techniques are applied to investigate the best position for feeding the dirty gas in a filter bag, in order to support the search for a more efficient and durable equipment design. To evaluate the filter bag performance, two different inlet positions were simulated. The first, called “conventional”, with gas jet reaching the bags in the centre and the second with concentric triple feed (called “triple”), in which the same gas flow rate is fed by in three regions roughly in the top, center, and bottom of the filter medium. The aim was to determine which design has improved uniformity of mass flow distribution between the bags and lower the equipment pressure drop, in order to increase the filter lifetime. For this purpose, it was used the isothermal and incompressible single phase flow model with turbulence being treated by realizable k-e model. It was concluded that the “triple” showed a better gas distribution to be filtered among the bags system, thus representing a more advantageous layout option when compared to “conventional”.