An effect of the tubular baffles configuration in an agitated vessel with a high-speed impeller on the power consumption

Marta Major-Godlewska,Joanna Karcz

doi:10.1007/s11696-018-0533-4

Abstract

The results of the power consumption for an agitated vessel equipped with vertical tubular baffles and high-speed impeller are presented in the paper. Aqueous solutions of CMC were agitated within transitional range of the non-Newtonian liquid flow in the agitated vessel of inner diameter equal to 0.6 m. Eight different types of the impellers were tested: Rushton or Smith turbines, turbine with straight blades, pitched blade turbines and propeller. The J tubular baffles of outer diameter B were located in the position e from the vessel wall. Different configurations of baffles, arranged around the vessel circumference singularly or blocked in the modules, were considered in the study. In total, 180 different tubular baffles–impeller systems were tested. The measurements of the torque were conducted by means of the strain gauges method. Based on the power characteristics obtained for each impeller type, the effect of the geometrical parameters of the vertical tubular baffles on the power number was determined and discussed. The results show that geometry of the tubular baffles mostly affects the power number for the system with radial flow Rushton turbine. Moreover, power numbers decrease with the increase of the clearance between baffle and vessel wall for the systems, in which the radially axial circulation of the liquid is promoted. The dependences of the power number on the geometrical parameters of the vertical tubular baffles arranged singularly around the vessel circumference were described by means of the Eqs. (5)–(16). These equations can be useful in the project computations.

Highlights

IntroductionVertical tubular baffles arranged in a vessel (a reactor or bioreactor) can simultaneously fulfil a role of cooling (or heating) the coil in such an apparatus
Vertical tubular baffles arranged in a vessel can simultaneously fulfil a role of cooling the coil in such an apparatus
Heat transfer process in the agitated vessel equipped with vertical tubular coil was experimentally studied by Karcz and Major (2001a, b) for non-Newtonian liquid, as well as by Rosa et al (2013, 2017) for Newtonian liquid

Summary

Introduction

Vertical tubular baffles arranged in a vessel (a reactor or bioreactor) can simultaneously fulfil a role of cooling (or heating) the coil in such an apparatus. Large difference in agitation energy requirement is observed for a case of complete hindering of tangential liquid velocity in a baffled vessel (full baffling) compared to an un-baffled vessel Taking into account these differences, it can be supposed that the best configuration of the geometrical system consisting of tubular baffles–high-speed impeller exists for which the assumed intensity of the transport processes can be obtained. Heat transfer process in the agitated vessel equipped with vertical tubular coil was experimentally studied by Karcz and Major (2001a, b) for non-Newtonian liquid, as well as by Rosa et al (2013, 2017) for Newtonian liquid. The aim of the study presented in this paper was to experimentally determine the effect of the tubular baffles configuration and impeller type on the power consumption required to agitate pseudoplastic liquid within the transitional range of the fluid flow in an agitated vessel. For each experimental point (described by a given geometry of the agitated vessel, agitator speed n and torque M), averaged values of both n and M values were determined from 6 and 8 readings, respectively, on the electronic counter (8) and amplifier (10)

Results and discussion

12 Propeller

Conclusions