FLUID MECHANICS OF MIXING: MODELLING, OPERATIONS AND EXPERIMENTAL TECHNIQUES

FLUID MECHANICS AND ITS APPLICATIONS Volume 10

Series Editor: R. MOREAU MADYLAM Ecole Nationale Superieure d' Hydraulique de Grenoble Boite Postale 95 38402 Saint Martin d' Heres Cedex, France

Aims and Scope of the Series The purpose of this series is to focus on subjects in which fluid mechanics plays a fundamental role. As well as the more traditional applications of aeronautics, hydraulics, heat and mass transfer etc., books will be published dealing with topics which are currently in a state of rapid development, such as turbulence, suspensions and multiphase fluids, super and hypersonic flows and numerical modelling techniques. It is a widely held view that it is the interdisciplinary subjects that will receive intense scientific attention, bringing them to the forefront of technological advance-ment. Fluids have the ability to transport matter and its properties as well as transmit force, therefore fluid mechanics is a subject that is particulary open to cross fertilisation with other sciences and disciplines of engineering. The subject of fluid mechanics will be highly relevant in domains such as chemical, metallurgical, biological and ecological engineering. This series is particularly open to such new multidisciplinary domains. The median level of presentation is the first year graduate student. Some texts are monographs defining the current state of a field; others are accessible to final year undergraduates; but essentially the emphasis is on readability and clarity.

For a list of related mechanics titles, see final pages.

Fluid Mechanics of Mixing: Modelling, Operations and Experimental Techniques

edited by

R. King

SPRINGER-SCIENCE+BUSINESS MEDIA, B.V.

ISBN 978-90-481-4156-2 ISBN 978-94-015-7973-5 (eBook) DOI 10.1007/978-94-015-7973-5

Printed an acid-free paper

AII Rights Reserved 1992 Springer Science+Business Media Dordrecht Originally published by Kluwer Academic Publishers in 1992 Softcover reprint of the hardcover 1 st edition 1992 No part of the material protected by this copyright notice may be reproduced or utilized in any form or by any means, electronic or mechanical, inc\uding photocopying, recording or by any information storage and retrieval system, without written permission from the copyright owner.

ACKNOWLEDGEMENTS This volume contains selected papers presented at the 7th European Congress on Mixing, September 1991, Brugge, Belgium.

Organized on behalf of the Working Party on Mixing of the European Federation of Chemical Engineering (EFCE) by the Royal Flemish Society of Engineers (KVIV) and the Belgian Branch of the Societe de Chimie Industrielle.

CONTENTS

Preface Xl

SECTION 1: MODELLING OF MIXING PROCESSES

Effect of macromixing on a competitive/consecutive reaction in a semi-batch stirred 3 reactor : Paul's iodination experiments interpreted by networks-of-zones R Mann, A M EI-Hamouz

The variation of flow pattern and mixing time with impeller spacing in stirred vessels 11 with two Rushton impellers S M Mahmoudi, M Yianneskis

Development of transitional flow mixing impeller 19 R J Weetman

Distribution of turbulence characteristics in agitated systems with axial high-speed 27 impeller and baffles I Fort, M Vozny, B Forstova

A computational study on dispersing gas in a stirred reactor 37 A Bakker, H E Van Den Akker

Measurements and modelling of flow in gas sparged, agitated vessels 47 G K Patterson

Simple performance correlations for agitated vessels 55 J M Smith

Gradients in production scale bioreactors 65 J Feijen, J J Hofmeester Solid distribution in slurry reactors stirred with multiple impellers : continuous flow 73 systems M Nocentini, F Magelli

SECTION 2: MIXING OPERATIONS

The mixing of miscible liquids with large differences in density and viscosity 83 S S Burmester, C D Rielly, M F Edwards

Power input and gas hold up in gas liquid dispersions agitated by axial flow impellers 91 V Machon, C M McFarlane, A W Nienow

Improving Xanthan fermentation performance by changing agitators 99 Z Xueming, A W Nienow, C A Kent, S Chatwin, E Galindo

Determination of the mean specific power input in stirred vessels with suspensions 107 R K Geisler, C Buurman, A B Mersmann

A comparison of the efficiency of five agitator designs for solids suspension duties 117 at high solids concentrations N I Heywood, S Rehman, R G Whittemore

The design of agitated dissolution tanks 131 P Did, F Rieger, I Rousar

Modelling and control of multistage mixer extractors 139 C Tsouris, L L Tavlarides

Local measurements of liquid and solid velocities and of particle sizes in stirred 145 suspensions with a phase doppler particle analyser P Guiraud, J Costes, J Bertrand, J Bousquet

Hydrodynamic characteristics of a gas-inducing impeller 153 G M Evans, C D Rielly, J F Davidson, K J Carpenter

Heat transfer in mechanically stirred gas-liquid system 163 J Karcz, F Strek

Heat and mass transfer efficiencies of multi-impeller gas-viscous liquids contactors 173 H Linden, H Desplanches, Y Gaston-Bonhomme, J L Chevalier, M Bruxelmane, V Dufour

SECTION 3: EXPERIMENTAL TECHNIQUES

Measurement of concentration fluctuations during mixing in a stirred tank and in 183 a channel flow by laser induced fluorescence spectroscopy C Andre, R David, J N Gence, J Villermaux

Reynolds stresses and stirring regimes of a Rushton turbine 191 M Mahouast

Micrornixing behaviour in a batch vessel with several impellers using alkali-fluorescent 197 dye system Y Hirofuji, T Inoue, Y Nagase An experimental study of micromixing using two parallel reactions 207 J R Bourne, S Yu

LDA measurements of flow in stirred gas-liquid reactors 217 V P Mishra, J B Joshi

A study of ventilated gas cavities on disc-turbine blades 225 S A Manning, G J Jameson

Numerical particle tracking in a turbine agitated vessel 233 K A Kusters, J G Wijers, D Thoenes

Residence time distribution of solid and liquid phase in a stirred tank reactor 247 L Guo, S Yang

Local wall heat transfer coefficients using surface calorimeters 253 J B Fasano, R S Brodkey, S J Haam

PREFACE

This volume is a selection of the material presented at the 7th European Mixing Congress. It is concerned exclusively with mixing in circular section vessels, using centrally mounted paddles or similar impellers.

The contents are arranged under three classifications: Modelling of Mixing Processes, Mixing Operations and Experimental Techniques. The classifications result in the original material appearing in a different order to that of the Congress. This arrangement is intended to assist the reader in identifying the topic area by function or application, rather than by technology.

In this book the section on Modelling contains papers which focus on the representation of the mixing process, whether by equation, scale-up criteria, or fluid dynamic simulation.

Similarly, Mixing Operations are concerned with the application or function of the mixing process, such as mass transfer, heat transfer or mixing time.

Experimental Techniques addresses the tools the researcher needs to use at the data gathering experimental stage. It collects together advances made in the various methods used by some of the foremost researchers, and indicates those areas still in need of additional instrumentation or methods of data reduction.

The book is intended for researchers, designers and users of mixing equipment, and for those planning research and development programmes and who wish to keep up to date with advances in the basic technology and its applications.

It is published with the full permission of the Royal Flemish Society of Engineers.