Estudo numérico da influência das condições operacionais sobre a suspensão de sólidos em tanques mecanicamente agitados

Abstract

Various industrial processes are affected by the quality of solid suspension, which, when done properly, enhances mass, heat, and momentum transfer mechanisms, primarily by increasing the exposed surface area and contact between particles. Parameters such as solid distribution, particle velocity, and the height of the solid cloud are essential for evaluating the quality of solid suspension in agitated tanks. Therefore, one way to assess this phenomenon is by using computational techniques to predict these variables, as it has been an alternative to cost reduction compared to complex experimental methods. The present study aims to determine operational and design conditions in the solid suspension process, particularly the influence of impeller geometric characteristics, using a monophasic fluid dynamics approach within a mechanically agitated tank. Geometric modeling, mesh construction, and computational fluid dynamics (CFD) simulations were performed using the commercial software ANSYS® student. In analyzing the influence of impeller geometric variables on solid suspension in a liquid medium, a central composite design (CCD) experimental plan was employed, with the following factors evaluated: blade attack angle (θ), impeller diameter to tank diameter ratio (D/T), number of impeller blades (NI), height to tank diameter ratio (C/T), and agitation speed (⍵). The results show that the impeller diameter to tank diameter ratio, impeller rotation speed, diameter-speed ratio, height to tank diameter ratio, and blade angle have a significant linear influence on the response.