Scale-up in chemical engineering

Title:

Personal Author:

Zlokarnik, Marko

Publication Information:

Weiheim : Wiley-VCH, 2002

ISBN:

9783527302666

Subject Term:

Chemical processes -- Simulation methods

Chemical engineering -- Simulation methods

Available:*

Library	Item Barcode	Call Number	Material Type	Item Category 1	Status
Searching... IBD Library	30000010041239	TP155.7 Z56 2002	Open Access Book	Book	Searching... Unknown
Searching... IBD Library	30000010041243	TP155.7 Z56 2002	Open Access Book	Book	Searching... Unknown

A chemical engineer is generally concerned with the industrial implementation of processes in which chemical or microbiological conversion of material takes place in conjunction with the transfer of mass, heat, and momentum. The characteristics of these processes depend on their scale.
They include heterogeneous chemical reactions and unit operations. Understandably, chemical engineers have always wanted to find ways of simulating these processes to gain insights assising them while designing new industrial plants or trying to optimize existing plants.
Irrespective of whether the model involved represents a "scale-up" or a"scale-down", certain important questions always apply: How small can the model be? Is one model sufficient or should tests be carried out in models of different sizes? When must or when can physical properties differ? When must the measurements be carried out on the model with the original system of materials? Which rules govern the adaptation of the process parameters in the model measurements to those of the full-scale plant? Is it possible to achieve complete similarity between the processes in the model and those in its full-scale counterpart? If not: how should one proceed?

These questions touch on the fundamentals of the theory of models, which are based on dimensional analysis. Although they have been used in the field of fluid dynamics and heat transfer for more than a century - cars, aircrafts, vessels and heat exchangers were scaled up according to these principles - these methods have gained only a modest acceptance in chemical engineering.
This book attempts to fill this gap. It is aimed at students and practicing chemical engineers. It consists of two parts.
The first part presents the principles of dimensional analysis and of scale-up, based on it, in an easily comprehensible and transparent manner. These principles are illustrated by 23 examples concerning well-known operations from the field of chemical engineering.
The second part of the book presents selected examples of treatment of processes in the field of mechanical (11 samples), thermical (6 examples) and chemical (5 examples) process engineering by the dimensional analysis. The last chapter shows that this method can also be favourably applied to the motion processes in the living world (5 examples), leading to a better understanding of them.

Author Notes

Prof. Dr.-Ing. Marko Zlokarnik taught similarity theory at the Technical University of Clausthal-Zellerfeld

Preface to the 1st Edition	p. XIII
Preface to the 2nd Edition	p. XV
Symbols	p. XVII
1 Introduction	p. 1
2 Dimensional Analysis	p. 3
2.1 The Fundamental Principle	p. 3
2.2 What is a Dimension?	p. 3
2.3 What is a Physical Quantity?	p. 3
2.4 Base and Derived Quantities, Dimensional Constants	p. 4
2.5 Dimensional Systems	p. 5
2.6 Dimensional Homogeneity of a Physical Content	p. 7
Example 1 What determines the period of oscillation of a pendulum?	p. 7
Example 2 What determines the duration of fall [theta] of a body in a homogeneous gravitational field (Law of Free Fall)? What determines the speed v of a liquid discharge out of a vessel with an opening? (Torricelli's formula)	p. 9
Example 3 Correlation between meat size and roasting time	p. 12
2.7 The Pi Theorem	p. 14
3 Generation of Pi-sets by Matrix Transformation	p. 17
Example 4 The pressure drop of a homogeneous fluid in a straight, smooth pipe (ignoring the inlet effects)	p. 17
4 Scale Invariance of the Pi-space-the Foundation of the Scale-up	p. 25
Example 5 Heat transfer from a heated wire to an air stream	p. 27
5 Important Tips Concerning the Compilation of the Problem Relevance List	p. 31
5.1 Treatment of Universal Physical Constants	p. 31
5.2 Introduction of Intermediate Quantities	p. 31
Example 6 Homogenization of liquid mixtures with different densities and viscosities	p. 33
Example 7 Dissolved air flotation process	p. 34
6 Important Aspects Concerning the Scale-up	p. 39
6.1 Scale-up Procedure for Unavailability of Model Material Systems	p. 39
Example 8 Scale-up of mechanical foam breakers	p. 39
6.2 Scale-up Under Conditions of Partial Similarity	p. 42
Example 9 Drag resistance of a ship's hull	p. 43
Example 10 Rules of thumb for scaling up chemical reactors: Volume-related mixing power and the superficial velocity as design criteria for mixing vessels and bubble columns	p. 47
7 Preliminary Summary of the Scale-up Essentials	p. 51
7.1 The Advantages of Using Dimensional Analysis	p. 51
7.2 Scope of Applicability of Dimensional Analysis	p. 52
7.3 Experimental Techniques for Scale-up	p. 53
7.4 Carrying out Experiments Under Changes of Scale	p. 54
8 Treatment of Physical Properties by Dimensional Analysis	p. 57
8.1 Why is this Consideration Important?	p. 57
8.2 Dimensionless Representation of a Material Function	p. 59
Example 11 Standard representation of the temperature dependence of the viscosity	p. 59
Example 12 Standard representation of the temperature dependence of density	p. 63
Example 13 Standard representation of the particle strength for different materials in dependence on the particle diameter	p. 64
Example 14 Drying a wet polymeric mass. Reference-invariant representation of the material function D(T, F)	p. 66
8.3 Reference-invariant Representation of a Material Function	p. 68
8.4 Pi-space for Variable Physical Properties	p. 69
Example 15 Consideration of the dependence [mu](T) using the [mu subscript w]/[mu] term	p. 70
Example 16 Consideration of the dependence [rho](T) by the Grashof number Gr	p. 72
8.5 Rheological Standardization Functions and Process Equations in Non-Newtonian Fluids	p. 72
8.5.1 Rheological Standardization Functions	p. 73
8.5.1.1 Flow Behavior of Non-Newtonian Pseudoplastic Fluids	p. 73
8.5.1.2 Flow Behavior of Non-Newtonian Viscoelastic Fluids	p. 76
8.5.1.3 Dimensional-analytical Discussion of Viscoelastic fluids	p. 78
8.5.1.4 Elaboration of Rheological Standardization Functions	p. 80
Example 17 Dimensional-analytical treatment of Weissenberg's phenomenon - Instructions for a PhD thesis	p. 81
8.5.2 Process Equations for Non-Newtonian Fluids	p. 85
8.5.2.1 Concept of the Effective Viscosity [mu subscript eff] According to Metzner-Otto	p. 86
8.5.2.2 Process Equations for Mechanical Processes with Non-Newtonian Fluids	p. 87
Example 18 Power characteristics of a stirrer	p. 87
Example 19 Homogenization characteristics of a stirrer	p. 90
8.5.2.3 Process Equations for Thermal Processes in Association with Non-Newtonian Fluids	p. 91
8.4.2.4 Scale-up in Processes with Non-Newtonian Fluids	p. 91
9 Reduction of the Pi-space	p. 93
9.1 The Rayleigh - Riabouchinsky Controversy	p. 93
Example 20 Dimensional-analytical treatment of Boussinesq's problem	p. 95
Example 21 Heat transfer characteristic of a stirring vessel	p. 97
10 Typical Problems and Mistakes in the Use of Dimensional Analysis	p. 101
10.1 Model Scale and Flow Conditions - Scale-up and Miniplants	p. 101
10.1.1 The Size of the Laboratory Device and Fluid Dynamics	p. 102
10.1.2 The Size of the Laboratory Device and the Pi-space	p. 103
10.1.3 Micro and Macro Mixing	p. 104
10.1.4 Micro Mixing and the Selectivity of Complex Chemical Reactions	p. 105
10.1.5 Mini and Micro Plants from the Viewpoint of Scale-up	p. 105
10.2 Unsatisfactory Sensitivity of the Target Quantity	p. 106
10.2.1 Mixing Time [theta]	p. 106
10.2.2 Complete Suspension of Solids According to the 1-s Criterion	p. 106
10.3 Model Scale and the Accuracy of Measurement	p. 107
10.3.1 Determination of the Stirrer Power	p. 108
10.3.2 Mass Transfer in Surface Aeration	p. 108
10.4 Complete Recording of the Pi-set by Experiment	p. 109
10.5 Correct Procedure in the Application of Dimensional Analysis	p. 111
10.5.1 Preparation of Model Experiments	p. 111
10.5.2 Execution of Model Experiments	p. 111
10.5.3 Evaluation of Test Experiments	p. 111
11 Optimization of Process Conditions by Combining Process Characteristics	p. 113
Example 22 Determination of stirring conditions in order to carry out a homogenization process with minimum mixing work	p. 113
Example 23 Process characteristics of a self-aspirating hollow stirrer and the determination of its optimum process conditions	p. 118
Example 24 Optimization of stirrers for the maximum removal of reaction heat	p. 121
12 Selected Examples of the Dimensional-analytical Treatment of Processes in the Field of Mechanical Unit Operations	p. 125
Introductory Remark	p. 125
Example 25 Power consumption in a gassed liquid. Design data for stirrers and model experiments for scaling up	p. 125
Example 26 Scale-up of mixers for mixing of solids	p. 131
Example 27 Conveying characteristics of single-screw machines	p. 135
Example 28 Dimensional-analytical treatment of liquid atomization	p. 140
Example 29 The hanging film phenomenon	p. 143
Example 30 The production of liquid/liquid emulsions	p. 146
Example 31 Fine grinding of solids in stirred media mills	p. 150
Example 32 Scale-up of flotation cells for waste water purification	p. 156
Example 33 Description of the temporal course of spin drying in centrifugal filters	p. 163
Example 34 Description of particle separation by means of inertial forces	p. 166
Example 35 Gas hold-up in bubble columns	p. 170
Example 36 Dimensional analysis of the tableting process	p. 174
13 Selected Examples of the Dimensional-analytical Treatment of Processes in the Field of Thermal Unit Operations	p. 181
13.1 Introductory Remarks	p. 181
Example 37 Steady-state heat transfer in mixing vessels	p. 182
Example 38 Steady-state heat transfer in pipes	p. 184
Example 39 Steady-state heat transfer in bubble columns	p. 185
13.2 Foundations of the Mass Transfer in a Gas/Liquid (G/L) System	p. 189
A short introduction to Examples 40, 41 and 42	p. 189
Example 40 Mass transfer in surface aeration	p. 191
Example 41 Mass transfer in volume aeration in mixing vessels	p. 193
Example 42 Mass transfer in the G/L system in bubble columns with injectors as gas distributors. Otimization of the process conditions with respect to the efficiency of the oxygen uptake E = G/[Sigma]P	p. 196
13.3 Coalescence in the Gas/Liquid System	p. 203
Example 43 Scaling up of dryers	p. 205
14 Selected Examples for the Dimensional-analytical Treatment of Processes in the Field of Chemical Unit Operations	p. 211
Introductory Remark	p. 211
Example 44 Continuous chemical reaction process in a tubular reactor	p. 212
Example 45 Description of the mass and heat transfer in solid-catalyzed gas reactions by dimensional analysis	p. 218
Example 46 Scale-up of reactors for catalytic processes in the petrochemical industry	p. 226
Example 47 Dimensioning of a tubular reactor, equipped with a mixing nozzle, designed for carrying out competitive-consecutive reactions	p. 229
Example 48 Mass transfer limitation of the reaction rate of fast chemical reactions in the heterogeneous material gas/liquid system	p. 233
15 Selected Examples for the Dimensional-analytical Treatment of Processes whithin the Living World	p. 237
Introductory Remark	p. 237
Example 49 The consideration of rowing from the viewpoint of dimensional analysis	p. 238
Example 50 Why most animals swim beneath the water surface	p. 240
Example 51 Walking on the Moon	p. 241
Example 52 Walking and jumping on water	p. 244
Example 53 What makes sap ascend up a tree?	p. 245
16 Brief Historic Survey on Dimensional Analysis and Scale-up	p. 247
16.1 Historic Development of Dimensional Analysis	p. 247
16.2 Historic Development of Scale-up	p. 250
17 Exercises on Scale-up and Solutions	p. 253
17.1 Exercises	p. 253
17.2 Solutions	p. 256
18 List of important, named pi-numbers	p. 259
19 References	p. 261
Index	p. 269

Available:*

On Order

Summary

Summary

Author Notes

Table of Contents