engineering data on mixing

Engineering Data on Mixing by Reiji Mezaki, Masafumi Mochizuki, Kohei Ogawa • ISBN: 0444828028 • Publisher: Elsevier Science & Technology Books • Pub. Date: January 2000 Preface This book is a compilation of the engineering data on mixing, which have appeared in the major technical journals of chemical engineering and bioengineering since 1975. That year marked the beginning of a period of rapid advancement in the science and technology of mixing, with rather reliable results for both theoretical and experimental studies. In addition, we have included some important earlier articles which have been and are still being referred to. Mixing is a basic technology important in a wide variety of industries. Many numbers of tanks equipped with various types of agitators have been used for mixing all kinds of materials since ancient times. Yet designs of both agitators and tanks still depend primarily on art and experience. In the light of this fact we felt that the data on mixing should be compiled and presented in a systematic manner for assistance in design and analysis of agitated tanks , and to provide easier access to mixing data for various engineering activities. Of course, computer- aided searches of pertinent data bases can be of assistance to chemical engineers and bioengineers in their studies. However, computer surveys of data bases are sometimes time- consuming and often costly. Furthermore inadequate selection of key words can jeopardize the searches. In view of these objections, we offer this book in the hope that it will be useful to those who desire to conduct an efficient and accurate survey of the mixing data of interest to them. No attempts were made to verify the mixing data given by the various investigators. We have simply indicated the limitations of correlations and data when they are available. The use of uniform units might have been appreciated by users of this book. However, we have elected to use the original units as given by the various authors, lest errors be introduced in the conversion process. In Chapter 1 we present a variety of results for the experimental measurements of flow patterns in stirred tanks. Most of the measurements were made by using modem Laser- Doppler techniques. This chapter is useful for the prediction of flow patterns in tanks with many different geometries, various types of agitators, and fluids of diverse physical and rheological properties. Here can also be found valuable data for the validation of results obtained by CFD simulations. Chapters 2 through 5 deal with data for traditional chemical engineering subjects. In Chapter 6 we sununarize a number of scale-up relations developed over the years for various systems. They include liquid, solid-liquid, liquid-liquid, gas-liquid, and solid-liquid-gas systems. Chapter 7 provides data related to multiphase processes. We wish to call attention to two sections: Section 7.4.1 Drop size and drop-size distributions Section 7.4.2 Bubble size and bubble-size distributions These two subjects have not been treated systematically either in text books or in handbooks on stirred-tank mixing, although the results of both experimental and theoretical investigations have been reported on many occasions. Chapter 8 deals with gas-inducing mechanically agitated systems. The applications of this type of agitation system will become increasingly attractive from the standpoint of rationahzation of stirred-tank operations as well as environmental protection. A review of this book will reveal many important research subjects that fall in the domain of stirred-tank mixing. We examined over nine hundred technical articles published since 1950. From this activity we could draw two important conclusions: (1) First, about 95% of the results reported in those articles were obtained by employing vessels whose diameters were less than 0.5 m. In industry, vessels with appreciably greater diameters are in daily use, and many more vessels will be designed and fabricated for future use. In view of this fact, much of the accumulated data and associated theory based on small- scale experiments will probably be VI inadequate for prediction of the performance of industrial-scale vessels. More data are undoubtedly needed to narrow the gap originating from this mismatch of equipment sizes. More specifically, advanced scale-up techniques, not rules, should be developed for precise prediction. In this respect it would be of great help if industries were cooperative in furnishing unsuccessful, as well as successful, examples of scale-up. (2) Secondly, there is a striking shortage of mixing data for systems in which highly viscous, non-Newtonian fluids are studied. It may be true that conventional agitated tanks are not satisfactory for such fluids. However, the authors of this book feel that many challenges still exist in this area. In this book we have excluded from consideration two important subjects related to mixing: reactions and crystallization in stirred tanks. Most of the articles treating those subjects were found to place more emphasis on the development of rate expressions for the reactions or crystallization. Here, we have aimed to compile data correlating process parameters with agitated-tank geometry and the physical properties of the relevant fluids. For this reason we feel that reactions and crystallization should be treated differently. It should be noted that several important journals issued in Russia, in Eastern Europe, and in the People's Republic of China were not considered in our search for mixing data. This is mainly because of difficulties in obtaining the original journals as well as the English- language versions. However, the authors sincerely hope that the pubhcation of this book will encourage other interested persons to compile mixing data published in the geographical regions mentioned above. Perhaps in this way some collaborative efforts will result in a substantially more complete compilation of engineering mixing data. It is inevitable that errors, omissions, and misunderstandings will arise in a work of this type. The authors will be grateful if readers would take the time and trouble to point these out to us. The authors would like to thank Professor R. B. Bird of the University of Wisconsin, who aided with advice and suggestions in reviewing and editing the title and preface to this book. Acknowledgment is also made to the staff members of Shinzan Sha, in particular, to Mr. K. Shinoe for his constructive advice during the preparation of the manuscript of this book, and to Ms. H. Tomita for the preparation of the camera-ready manuscript. Without their efforts this book could not have become a reality. August, 1999 Reiji Mezaki Masafumi Mochizuki Kohei Ogawa Table of Contents Preface, Pages v-vi Chapter 1 - Flow patterns, Pages 1-84 Chapter 2 - Mixing time, Pages 85-115 Chapter 3 - Power draw and consumption, Pages 117-238 Chapter 4 - Heat transfer, Pages 239-304 Chapter 5 - Mass Transfer, Pages 305-468 Chapter 6 - Scale-up rules, Pages 469-512 Chapter 7 - Other subjects related to multi-phase systems, Pages 513-731 Chapter 8 - Gas-inducing mechanically agitated systems, Pages 733-764 Author index, Pages 765-769 Chapter 1. Flow patterns 1.1 Single phase Peters, D. C. and Smith, J. M., Ttans. Instn. Chem. Engrs., 45, T360 (1967) Fluid Flow in the Region of Anchor Agitator Blades Experimental apparatus Vessel Type: flat-bottomed Diameter: 12.08 in Height: 18 in Liquid contained Height: 14 in Impeller Type: anchor Width of agitator blade: 1.0 in Wall/blade clearance: runs2A 0.125 in runs2C 0.50 in Working fluids and their physical properties No. 1 lubricating oil 2 lubricating oil 3 glycerol (3% water) 4 silicone oil (MS200) 5 silicone oil (MS200) 6 1% polyacrylamide (aq.) 7 2% 8 4% Reynolds numbers were computed Flow measurement technique Photography Results Tank: 22.9 cm diameter Anchor: 19.5 cm diameter, 2.5 cm wide, 90 rev/min Fluid: Silicone oils, 60 poise and 180 poise Velocity components perpendicular to radii, along. normal to, and at 30*^ to agitator blade ^ (poise) 1.5 - 2.5 6.8 - 10.4 5.6 - 9.75 125 - 131 290 ~ 318 n 0.7 0.46 - 0.54 0.30 - 0.38 p (g/cm^) 0.865 0.885 1.25 0.96 0.98 /j(gs" Vcm) p(g/cm^) 2.12 - 2.57 1.01 40.4 - 50.4 1.02 308-460 1.04 using temperature-corrected viscosity data. 1 ' 1 ' ' t- t«- - t- 1 8 « ' ' ' LJ-' f ^^^-^^V^J Hi)) ^^^Sr/w/y feCX^^^y^vy*!?^^^^ IS^^^^^r^'^^' Velocity profiles and flow patterns (Beckner, J. L., Ph. D. Thesis, 1965. University of Wales) Chapter 1. Flow pattoms \' X y 16 p.p.s. (some points at 8 p.p.s.) NiRe)=21A, Run3-2C-10 25.4 p.p.s. (some points at 12.7 p.p.s.) iV(i?«)=105.3, Run3-2C-30 33.4 p.p.s. and 63.4 p.p.s. i\^(/?e)=143.4, Run3-2C-60 Flow patterns with glycerol 1.1 Single phas« ^" • . -^A* • . 7 • '. •M-Ji'.i'V^ ••• y /f • r'' * . >r;*, . / 32.0p.p.s. N*(Me)=l2.9, Run7-2C-40 64.0 p.p.s (some points at 32 p.p.s.) iV*(/?^)=25.5, Run7-2C-80 '- -r - ^ * / 64.0 p.p.s (some points at 32 p.p.s.) N*(Jie)=3lA, Run7-2C-100 Notation a geometrical constant c clearance between blades and wall D paddle diameter DT tank diameter k usual power law characterization parameter n usual power law characterization parameter N rotational speed of stirrer p density of fluid /i viscosity of fluid Note: Cxeneralized Reynolds numbers are based on a power law (expression for the shear rate/shear stress relationship as used by Beckner) Flow patterns with 2% aqueous polyacrylamide, 1 in. blade, 0.5 in clearance The normal Reynolds number: NiHe)=N^Dpln The Reynolds nimiber for power-law fluids: N*{Re)=N^~''D^p/[k[a(\-n)Y'\ a=37-120 C/DT Chapter 1. Plow patterns Cooper, R. C. and Wolf, D., Can. J. ofChem. Eng., 46,94 (1968) Velocity Profiles and Pumping Capacities for Turbine Type Impellers Experimental apparatus Vessel Type: flat-bottomed Diameter: 15 in Height: 20 in Baffle Number: 4 Width: IV2 in Impeller Type: 6 and 10 bladed turbines Dimension: Turbine No. 1 2 3 4 5 6 7 8 9 10 11 12 Blade diameter in. 3 4 5 6 9 9 4 4 4 4 4 4 Blade width in. 0.6 0.8 1.0 1.2 1.8 3.6 0.6 1.0 1.2 1.4 1.6 0.8 Blade length in. 0.75 1.0 1.25 1.5 2.25 2.25 1.0 1.0 1.0 1.0 1.0 1.0 No of Blades 6 6 6 6 6 6 6 6 6 6 6 10 Working fluids Water and air Flow measurement technique Hot-wire anemometry and three-directional pressure measurement 1.1 Siiigl* phas« Results J 2 .4 .« .B LO Normalized radial velocity profiles for various turbine sizes and various rotational speeds in water. Radial velocity profiles at different radial distances (4-in. turbine in water). Notation VR radial velocity component W turbine blade width Z vertical distance Chapter 1. Flow patterns Bourne, J. R. and Butler, H., Trans. Instn. Chem. Engrs., 47, Til (1969) An Analysis of the Flow Produced by Helical Ribbon Impellers Experimental apparatus Dimensions of vessels and impellers Type: flat-bottomed Volume: (1) 6 gals (2) 160 gals Geometry The geometry of the helical ribbon mixer Summery of principal dimensions Impeller number 1 2 3 4 5 d (in) 10.303 11.030 11.142 11.370 34.34 d D 0.889 0.952 0.962 0.981 0.954 h D 1.06 1.06 1.06 1.06 1.06 W D 0.108 0.108 0.108 0.108 0.104 s D 0.345 0.345 0.345 0.345 0.345 Zo D 1.22 1.2L' 1.22 1.22 1.22 Working fluids and their physical properties Pseudoplastic fluids: aqueous solutions of sodium carboxy methyl cellulose (CMC) and hydroxypropyl methyl cellulose (Celacol) apparent viscosities 1 ~ 500 poise at concentrations up to 3 w/w% and shear rates of 1 - 3001/s [...]... (1979) IWo Dimensional Model Analysis of Flow Behavior of Highly Viscous Non-Newtonian Fluid in Agitated Vessel with Paddle Impeller Dimension of vessel and impeller 0.3 ^d/D< 0.9 Computational conditions 10 < Re {=^DVp/fi) Computational results d/D > 0.5 n «o.e Rcf 0 (p/>*.v) Non-Newtonian viscosity distribution for paddle of rf/2>=0.5 Notation Non-Newtonian viscosity distributions for different size... -Q05 -01 Q05 (a) V, component (b) lit component (a) Vr component (b) Vet component Distribution offlowvelocity expressed by threedimensional components (D=0.2m, it =6.88 s *) Distribution offlowvelocity expressed by threedimensional components (D=0.2 m, «=6.88 s *) 1.1 S i n g I * phas« 25 Cenler axis of vessel blade 0 a: [-{U k » \ V V _ -0.6 [ {:=: (c) Vt component Distribution offlowvelocity expressed... fluid consistency, k g / m (sec)^"** ^-^mv/DT I {(cDw+2)}.N J n flow behavior index J? radial coordinate, m Re Reynolds number, DVp/fi, dimensionless V rotational velocity of vessel wall, m / s e c Superscript p non-Newtonian viscosity, N s e c / m ^ — averaged value /Xar apparent viscosity, N s e c / m ^ Subscript ft* dimensionless non-Newtonian viscosity, fi/po, NN non-Newtonian fluid dimensionless... Visualization Experimental conditions Impeller rotational velocity: 82,104 and 106 rpm Results Notation B width of impeller blade, m D impeller diameter, m N impeller rotational speed, 1/min Sock surface !cl B/D»1/8 Front surface N*106rpm Visualization of flow on the surface of blade with oil film method 1.1 Single phase 21 Kuboi, R and Nienow, A W, Chem Eng Sci., 41,123 (1986) Intervortex Mixing Rates... Fluid: tap water and water/glycerin solutions Tracer: polystyrene particles (diameter 0.5 mm) Flow measurement technique Photography Experimental conditions Direction of Impeller speed: 5 rps Results rototion Schematic thee dimensional view of the trailing vortex pair Dirtetion Schematic two dimensional view of theflowin the stirrer blade region S, stagnation point Chapter 1 Flow patterns 14 , Blode... Working fluids Aqueous solutions of com syrup containing solid-particles as tracers Flow measurement technique Photography Experimental conditions Results i • : C«tcuUt«d : ExptrimtnUI Tangential velocity distributions (Be = 1) Notation d impeller diameter N rotational speed of impeller U, V velocity components VB tangential velocity of blade tip Re Reynolds number, d ^Nl v, dimensionless V kinematic viscosity... HELICAL SCREW (GRAY) 0.01 0.02 0.0^ 0.1 1 -K , C / D , 0.2 I/D^ Shear characteristics Notation b blade width of helical ribbon, cm d impeller diameter, cm D vessel diameter, cm Dd disk diameter, cm gr gravitational conversion factor, g cm/G sec^ / distance between disks, cm n rotational speed, 1/sec Pv power consumption/unit volume, Gcm/seccm^ Vb, V2 tangential and axial velocity, cm/sec 77 liquid viscosity,... (CN)6 The kinematic viscosities of the solutions are the same as that of water Flow measurement technique Measurement of diffusional mass transfer rate using a multi-electrode Experimental conditions Impeller speed: 60,90 and 120 rpm Results Notation r_ radial position, mm Ui mean velocity of i component, cm/sec UT impeller tip velocity, cm/sec 2 axial position, mm 65 75 85 95 105 r, mm Turbulence intensity... H==2D, n=150 rpm (group A) Notation D Ettox hb H L n P' 6 P- 6mn tank diameter maximum value of mixing efficiency vertical distance between bottom of a tank and center of lower impeller water depth vertical distance between double impellers impeller rotational speed energy consumption minimum value of energy consumption P- 6 Chapter 1 Flow patterns 30 Wu, H and Patterson, G K., Chem Eng Scu, 44,2207... The distribution of axialfluidvelocities in the core for impeller 2 pumping upwards Notation d D h N r Ri 5 Vt W Zo Y / 1 outside diameter of ribbon inside diameter of tank height of ribbon rotational speed of impeUer radial coordinate inside radius of ribbon pitch of ribbon axial fluid velocity width of ribbon static height of liquid in tank 1 'i X-t- i 1 ! r -T— • r - — 0-03 X V Y Y y 20A X40 i^AO . dimensionless V rotational velocity of vessel wall, m/sec p non-Newtonian viscosity, Nsec/m^ /Xar apparent viscosity, Nsec/m^ ft* dimensionless non-Newtonian viscosity, fi/po, dimensionless. Viscous Non-Newtonian Fluid in Agitated Vessel with Paddle Impeller Dimension of vessel and impeller 0.3 ^d/D< 0.9 Computational conditions 10 < Re {=^DVp/fi) Computational results. Preface This book is a compilation of the engineering data on mixing, which have appeared in the major technical journals of chemical engineering and bioengineering since 1975. That year marked