Effect of Agitator\u2019s Types on the Hydrodynamic Flow in an Agitated Tank

Mohammed Foukrach,Mohamed Bouzit,Youcef Kamla,Houari Ameur

doi:10.1186/s10033-020-00454-2

Abstract

The aim of this paper is to study the effect of agitator’s types on the turbulent flows in stirred tanks without and with baffles. The hydrodynamics behavior induced by four different agitator’s types: a Rushton turbine (RT), a circular blade turbine (CBT), a diverging triangular blade turbine (DTBT) and converging triangular blade turbine (CTBT) are numerically predicted by solving the Navier-Stokes equations and RNG κ–ε turbulent model. The simulations are carried out using the Multi Reference Frame (MRF) approach. The numerical results showed good agreement with experiment. We find that the agitator CTBT gives an important profit on the power consumption per report/ratio the others and DTBT give a good reduction of the vortex size of the impeller angles.

Highlights

Mixing is one of the most widely used unit operations in the chemical, bio-chemical, pharmaceutical, petrochemical, and food processing
The absence of baffles does not ensure a good quality of mixing, this is due to the fact that the flow is mainly tangential, on the other hand the mixing becomes more efficient if the steering system comprises baffles, and that this translated by the transformation of the predominantly tangential flow into a three-dimensional flow
In order to verify the reliability of the calculation code and the simulation method used, reference was made to the work of Ref. [22]

Summary

Introduction

Mixing is one of the most widely used unit operations in the chemical, bio-chemical, pharmaceutical, petrochemical, and food processing. The objective of mixing is homogenization, manifesting itself in a reduction of concentration or temperature gradients or both simultaneously, within the agitated system [1]. A stirred tank unit typically consists of a rotating impeller in a vessel. Fluid motion is promoted by the transfer of energy from the impeller into the process fluid. The agitation of liquid in these tanks is an operation more or less simple to realize, but always complex to characterize, because of the nature of the flows and the geometry of the system. The study of the systems of agitation started in several works relating to the characterization of the turbulent flows. One can quote the work of Refs. [2,3,4,5,6,7]

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Results

Conclusion