Tài liệu Chemical Micro Process Engineering pptx

1 1.1.2 Drivers for Mixing in Micro Spaces 2 1.1.3 Mixing Principles 3 1.1.4 Means for Mixing of Micro Spaces 4 1.1.5 Generic Microstructured Elements for Micro-mixer Devices 5 1.1.6 Exp

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Chemical Micro Process Engineering

Processing and Plants

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A Müller, G Kolb

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Hessel, V., Hardt, S., Löwe, H.

Fundamentals, Modelling and Reactions

2004 ISBN 3-527-30741-9

Ehrfeld, W., Hessel, V., Löwe, H

Microreactors

New Technology for Modern Chemistry

2000 ISBN 3-527-29590-0

Menz, W., Mohr, J., Paul, O

Microsystem Technology

2001 ISBN 3-527-29634-4

Sanchez Marcano, J G., Tsotsis, Th T

Catalytic Membranes and Membrane Reactors

2002 ISBN 3-527-30277-8

Dobre, T Gh., Sanchez Marcano, J G

Chemical Engineering

Modelling, Simulation and Similitude

2005 ISBN 3-527-30607-2

Sundmacher, K., Kienle, A (Eds.)

Reactive Distillation

Status and Future Directions

2003 ISBN 3-527-30579-3

Nunes, S P., Peinemann, K.-V (Eds.)

Membrane Technology

in the Chemical Industry

2001 ISBN 3-527-28485-0

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Processing and Plants

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carefully produced Nevertheless, authors and publisher do not warrant the information contained in these books, including this book, to be free of errors Readers are advised to keep in mind that statements, data, illustrations, procedural details or other items may inadvertently be inaccurate.

Library of Congress Card No.: Applied for British Library Cataloging-in-Publication Data:

A catalogue record for this book is available from the British Library.

Bibliographic information published by Die Deutsche Bibliothek

Die Deutsche Bibliothek lists this publication

in the Deutsche Nationalbibliografie; detailed bibliographic data is available in the internet at http://dnb.ddb.de.

by photoprinting, microfilm, or any other means – nor transmitted or translated into

a machine language without written permission from the publishers Registered names, trademarks, etc used in this book, even when not specifically marked as such, are not to be considered unprotected by law Printed in the Federal Republic of Germany Printed on acid-free paper

Typesetting Manuela Treindl, Laaber Printing betz-druck GmbH, Darmstadt Bookbinding J Schäffer GmbH i G.,

Grünstadt

ISBN-13 978-3-527-30998-6 ISBN-10 3-527-30998-5

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Preface XXIII Abbreviations and Symbols XXV

1 Mixing of Miscible Fluids 1

1.1 Mixing in Micro Spaces – Drivers, Principles, Designs and Uses 1

1.1.1 ‘Mixing Fields’, a Demand Towards a more Knowledge-based Approach –

Room for Micro Mixers? 1

1.1.2 Drivers for Mixing in Micro Spaces 2

1.1.3 Mixing Principles 3

1.1.4 Means for Mixing of Micro Spaces 4

1.1.5 Generic Microstructured Elements for Micro-mixer Devices 5

1.1.6 Experimental Characterization of Mixing in Microstructured

Devices 6

1.1.7 Application Fields and Types of Micro Channel Mixers 7

1.2 Active Mixing 8

1.2.1 Electrohydrodynamic Translational Mixing 8

1.2.1.1 Mixer 1 [M 1]: Electrohydrodynamic Micro Mixer (I) 9

1.2.1.2 Mixer 2 [M 2]: Electrohydrodynamic Micro Mixer (II) 10

1.2.1.3 Mixer 3 [M 3]: Electrokinetic Instability Electroosmotic Flow Micro

Mixer, First-generation Device 11

1.2.1.4 Mixer 4 [M 4]: Electrokinetic Instability Electroosmotic Flow Micro

Mixer, Second-generation Device 12

1.2.1.5 Mixer 5 [M 5]: Electrokinetic Instability Micro Mixer by Zeta-potential

Variation 13

1.2.1.6 Mixer 6 [M 6]: Electrokinetic Dielectrophoresis Micro Mixer 14

1.2.1.7 Mixing Characterization Protocols/Simulation 14

1.2.1.8 Typical Results 16

1.2.2 Electro Rotational Mixing 24

1.2.2.1 Mixer 7 [M 7]: Coupled Electrorotation Micro Mixer 24

1.2.3 Chaotic Electroosmotic Stirring Mixing 25

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1.2.3.1 Mixer 8 [M 8]: Chaotic Electroosmotic Micro Mixer 26

1.2.3.2 Mixing Characterization Protocols/Simulation 271.2.3.3 Typical Results 27

1.2.4 Magnetohydrodynamic Mixing 31

1.2.4.1 Mixer 9 [M 9]: Magnetohydrodynamic Micro Mixer 31

1.2.5 Air-bubble Induced Acoustic Mixing 341.2.5.1 Mixer 10 [M 10]: Acoustic Microstreaming Micro Mixer, Version 1 35

1.2.5.2 Mixer 11 [M 11]: Acoustic Microstreaming Micro Mixer, Version 2 35

1.2.5.3 Mixer 12 [M 12]: Design Case Studies for Micro Chambers of Acoustic

Microstreaming Micro Mixer, Version 2 36

1.2.6 Ultrasonic Mixing 41

1.2.6.1 Mixer 13 [M 13]: Ultrasonic Micro Mixer 42

1.2.7 Moving- and Oscillating-droplet Mixing by Electrowetting 44

1.2.7.1 Mixer 14 [M 14]: Moving- and Oscillating-droplet Micro Mixer 45

1.2.8 Moving- and Oscillating-droplet Mixing by Dielectrophoresis 53

1.2.8.1 Mixer 15 [M 15]: Dielectrophoretic Droplet Micro Mixer 53

1.2.8.2 Mixer 16 [M 16]: Electrical Phase-array Panel Micro Mixer 54

1.2.8.3 Mixer 17 [M 17]: Electrical Dot-array Micro Mixer 54

1.2.9 Bulge Mixing on Structured Surface Microchip 57

1.2.9.1 Mixer 18 [M 18]: Structured Surface Bulge Micro Mixer 57

1.2.10 Valveless Micropumping Mixing 59 1.2.10.1 Mixer 19 [M 19]: Valveless Micropumping Micro Mixer 59 1.2.10.2 Mixing Characterization Protocols/Simulation 60 1.2.10.3 Typical Results 61

1.2.11 Membrane-actuated Micropumping Mixing 61 1.2.11.1 Mixer 20 [M 20]: Membrane-actuated Micropumping Micro Mixer 61 1.2.11.2 Mixing Characterization Protocols/Simulation 62

1.2.11.3 Typical Results 62

1.2.12 Micro Impeller Mixing 63 1.2.12.1 Mixer 21 [M 21]: Impeller Micro Mixer 64 1.2.12.2 Mixer 22 [M 22]: Ferromagnetic Sphere-chain Micro Mixer 64 1.2.12.3 Mixing Characterization Protocols/Simulation 65

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1.2.13 Magnetic Micro-bead Mixing 66

1.2.13.1 Mixer 23 [M 23]: Magnetic Micro-bead Micro Mixer 66

1.2.14 Rotating-blade Dynamic Micro Mixer 66

1.3 Passive Mixing 66

1.3.1 Vertical Y- and T-type Configuration Diffusive Mixing 66

1.3.1.1 Mixer 24 [M 24]: T-type Micro Mixer 67

1.3.1.2 Mixer 25 [M 25]: Y-type Micro Mixer 67

1.3.1.3 Mixer 26 [M 26]: Y-type Micro Mixer with Venturi Throttle 67

1.3.1.4 Mixer 27 [M 27]: Y-type Micro Mixer with Extended Serpentine

Path 68

1.3.1.5 Mixer 28 [M 28]: T-type Micro Mixer with Straight Path 68

1.3.2 Horizontally Bi-laminating Y-feed Mixing 79

1.3.2.1 Mixer 29 [M 29]: Unfocused Horizontally Bi-laminating Y-feed Micro

Mixer 79

1.3.3 Capillary-force, Self-filling Bi-laminating Mixing 84

1.3.3.1 Mixer 30 [M 30]: Capillary-force, Self-filling Bi-laminating Micro

Mixer 84

1.3.4 Cross-injection Mixing with Square Static Mixing Elements 86

1.3.4.1 Mixer 31 [M 31]: Cross-shaped Micro Mixer with Static Mixing

Elements 86

1.3.5 Hydrodynamic Focusing Cross-Injection Mixing 90

1.3.5.1 Mixer 32 [M 32]: Hydrodynamic Focusing Cross-injection Micro

Mixer 90

1.3.6 Geometric Focusing Bi-laminating Mixing 93

1.3.6.1 Mixer 33 [M 33]: Geometric Focusing Bi-laminating Micro Mixer 94

1.3.7 Bi-laminating Microfluidic Networks for Generation of Gradients 95

1.3.7.1 Mixer 34 [M 34]: Bi-laminating Microfluidic Network 95

1.3.7.2 Experimental Characterization Protocols/Simulation 96

1.3.8 Bifurcation Multi-laminating Diffusive Mixing 98

1.3.8.1 Mixer 35 [M 35]: Bifurcation Multi-laminating Micro Mixer 99

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1.3.9 Interdigital Multi-laminating Diffusive Mixing (Normal and

Focusing) 102

1.3.9.1 Mixer 36 [M 36]: Unfocused Interdigital Multi-laminating Micro Mixer

with Co-flow Injection Scheme (I), ‘Rectangular Mixer’ 105

1.3.9.2 Mixer 37 [M 37]: Interdigital Vertically Multi-laminating Micro Mixer

with Co-flow Injection Scheme (II) 106

1.3.9.3 Mixer 38 [M 38]: Interdigital Horizontally Bi-laminating Micro Mixer

with Cross-flow Injection Scheme, Reference Case to [M 37] 107

1.3.9.4 Mixer 39 [M 39]: Interdigital Horizontally Multi-laminating Micro

Mixer with Co-flow Injection Scheme 108

with Counter-flow Injection Scheme – ‘3-D Slit Mixer’ 110

with Counter-flow Injection Scheme, 10-fold Array 112

with ‘Slit-type’ Focusing – ‘Plane Slit Mixer’ 113

with Triangular Focusing (I) 114

with Optimized Triangular Focusing – ‘SuperFocus’ 114

with Triangular Focusing Zone (II) 116

with Flow-re-directed Focusing Zone 117 1.3.9.12 Mixing Characterization Protocols/Simulation 118 1.3.9.13 Typical Results 121

1.3.10 Interdigital Concentric Consecutive Mixing 139

1.3.10.1 Mixer 47 [M 47]: Interdigital Consecutive Micro Mixer,

StarLam300 140

1.3.10.2 Mixer 48 [M 48]: Interdigital Consecutive Micro Mixer,

StarLam3000 142 1.3.10.2 Mixing Characterization Protocols/Simulation 142 1.3.10.3 Typical Results 142

1.3.11 Cyclone Laminating Mixing 144

1.3.11.1 Mixer 49 [M 49]: Cyclone Laminating Micro Mixer, Tangential

1.3.12 Concentric Capillary-in-capillary and Capillary-in-tube Mixing 149 1.3.12.1 Mixer 52 [M 52]: Capillary-in-capillary Micro Mixer 150

1.3.12.2 Mixer 53 [M 53]: Capillary-in-tube Micro Mixer 150

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1.3.12.3 Mixing Characterization Protocols/Simulation 151

1.3.13 Droplet Separation-layer Mixing 151

1.3.13.1 Mixer 54 [M 54]: Concentric Separation-layer Interdigital Micro

Mixer 153 1.3.13.2 Mixer 55 [M 55]: Planar Separation-layer Interdigital Micro Mixer 154 1.3.13.3 Mixing Characterization Protocols/Simulation 154

1.3.14 Split-and-recombine Mixing 162

1.3.14.1 Mixer 56 [M 56]: Möbius-type Split-and-recombine Micro Mixer 163

1.3.14.2 Mixer 57 [M 57]: Möbius-type Split-and-recombine Micro Mixer with

Fins 164 1.3.14.3 Mixer 58 [M 58]: Fork-element Split-and-recombine Micro Mixer 164 1.3.14.4 Mixer 59 [M 59]: Stack Split-and-recombine Micro Mixer 166

1.3.14.5 Mixer 60 [M60]: Up-down Curved Split-and-recombine Micro Mixer 167

1.3.14.6 Mixer 61 [M 61]: Multiple-collisions Split-and-recombine Micro

Mixer 167 1.3.14.7 Mixer 62 [M 62]: Separation-plate Split-and-recombine Micro Mixer 168 1.3.14.8 Mixing Characterization Protocols/Simulation 169

1.3.15 Rotation-and-break-up Mixing 175

1.3.15.1 Mixer 63 [M 63]: Rotation-and-break-up Micro Mixer (I) 176

1.3.15.2 Mixer 64 [M 64]: Rotation-and-break-up Micro Mixer (II) 176

1.3.16 Micro-plume Injection Mixing 180

1.3.16.1 Mixer 65 [M 65]: Micro-plume Injection Micro Mixer 180

1.3.17 Slug Injection Mixing 182

1.3.17.1 Mixer 66 [M 66]: Segmented-flow Micro Mixer 182

1.3.18 Secondary Flow Mixing in Zig-zag Micro Channels 183

1.3.18.1 Mixer 67 [M 67]: Y-type Micro Mixer with Zig-zag or Straight

Channel 183

1.3.18.2 Mixer 68 [M 68]: T-type Micro Mixer with Zig-zag or Straight

Channel 184 1.3.18.3 Mixing Characterization Protocols/Simulation 185

1.3.19 Mixing by Helical Flows in Curved and Meander Micro Channels 191 1.3.19.1 Mixer 69 [M 69]: Curved Channel Micro Mixer 191

1.3.19.2 Mixer 70 [M 70]: Meander Channel Micro Mixer 192

1.3.19.3 Mixer 71 [M 71]: 3-D L-shaped Serpentine Micro Mixer 193

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1.3.20 Distributive Mixing with Traditional Static Mixer Designs 203 1.3.20.1 Mixer 72 [M 72]: Intersecting Elements Microstructured Mixer 204 1.3.20.2 Mixer 73 [M 73]: Helical Elements Micro Mixer 204

1.3.20.3 Mixing Characterization Protocols/Simulation 205 1.3.20.4 Typical Results 205

1.3.21 Passive Chaotic Mixing by Posing Grooves to Viscous Flows 206 1.3.21.1 Mixer 74 [M 74]: Non-grooved Channel – Reference Case 206 1.3.21.2 Mixer 75 [M 75]: Oblique, Straight-grooved Micro Mixer (I) 207

1.3.21.3 Mixer 76 [M 76]: Oblique, Asymmetrically Grooved Micro Mixer –

Staggered Herringbone Mixer (SHM) 207 1.3.21.4 Mixer 77 [M 77]: Oblique, Straight-grooved Micro Mixer (II) 208 1.3.21.5 Mixer 78 [M 78]: Diagonal-grooved Micro Mixer 208

1.3.21.6 Mixing Characterization Protocols/Simulation 209 1.3.21.7 Typical Results 209

1.3.22 Chaotic Mixing by Twisted Surfaces 216 1.3.22.1 Mixer 79 [M 79]: Twisted Surface Micro Mixer 216 1.3.22.2 Mixing Characterization Protocols/Simulation 217 1.3.22.3 Typical Results 218

1.3.23 Chaotic Mixing by Barrier and Groove Integration 219

1.3.23.1 Mixer 80 [M 80]: Barrier-embedded Micro Mixer with Slanted

Grooves 219

1.3.23.2 Mixer 81 [M 81]: Barrier-embedded Micro Mixer with Helical

Elements 220 1.3.23.3 Mixing Characterization Protocols/Simulation 222 1.3.23.4 Typical Results 222

1.3.24 Distributive Mixing by Cross-sectional Confining and Enlargement 226

1.3.24.1 Mixer 82 [M 82]: Distributive Micro Mixer with Varying Flow

Restriction 226 1.3.24.2 Mixing Characterization Protocols/Simulation 226 1.3.24.3 Typical Results 226

1.3.25 Time-pulsing Mixing 227 1.3.25.1 Mixer 83 [M 83]: Time-pulsing Cross-flow Micro Mixer (I) 228 1.3.25.2 Mixer 84 [M 84]: Time-pulsing Cross-flow Micro Mixer (II) 228 1.3.25.3 Mixing Characterization Protocols/Simulation 229

1.3.26 Bimodal Intersecting Channel Mixing 236 1.3.26.1 Mixer 85 [M 85]: Bimodal Intersecting Channel Micro Mixer 238 1.3.26.2 Mixing Characterization Protocols/Simulation 238

1.3.27 Micro-bead Interstices Mixing 241 1.3.27.1 Mixer 86 [M 86]: Micro-bead Interstices Micro Mixer 242 1.3.27.2 Mixing Characterization Protocols/Simulation 242 1.3.27.3 Typical Results 242

1.3.28 Recycle-flow Coanda-effect Mixing Based on Taylor Dispersion 243

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1.3.28.1 Mixer 87 [M 87]: Coanda-effect Micro Mixer with Tesla

Structures 245 1.3.28.2 Mixing Characterization Protocols/Simulation 247

1.3.29 Recycle-flow Mixing Based on Eddy Formation 251

1.3.29.1 Mixer 88 [M 88]: Recycle-flow Micro Mixer 251

1.3.30 Cantilever-valve Injection Mixing 254

1.3.30.1 Mixer 89 [M 89]: Cantilever-valve Injection Micro Mixer 254

1.3.31 Serial Diffusion Mixer for Concentration Gradients 256

1.3.31.1 Mixer 90 [M 90]: Serial-diffusion Micro Mixer for Concentration

Gradients 257 1.3.31.2 Mixing Characterization Protocols/Simulation 258

1.3.32 Double T-junction Turbulent Mixing 260

1.3.32.1 Mixer 91 [M 91]: Double T-junction Micro Mixer 260

1.3.33 Jet Collision Turbulent or Swirling-flow Mixing 262

1.3.33.1 Mixer 92 [M 92]: Frontal-collision Impinging Jet Micro Mixer,

‘MicroJet Reactor’ 263 1.3.33.2 Mixer 93 [M 93]: Y-Type Collision Impinging Jet Micro Mixer 263 1.3.33.3 Mixer 94 [M 94]: Impinging Jet Array Micro Mixer 264

References 272

2 Micro Structured Fuel Processors for Energy Generation 281

2.1 Outline and Definitions 281

2.1.1 Power Range and Applications 281

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2.4 Micro Structured Test Reactors for Fuel Processing 288

2.4.1 Methanol Steam Reforming (MSR) 290

2.4.1.1 Methanol Steam Reforming 1 [MSR 1]:

Electrically Heated Serpentine Channel Chip-like Reactor 293

Electrically Heated Parallel Channel Chip-like Reactor 293

Electrically Heated Stack-like Reactor 293

Externally Heated Stack-like Reactor 295

Electrically Heated Stack-like Reactor 297

Electrically Heated Screening Reactor 298

2.4.1.7 Development of Catalyst Coatings for Methanol Steam Reforming in

Micro Channels 299

2.4.2 Autothermal Methanol Reforming 304

2.4.2.1 Autothermal Methanol Reforming 1 [AMR 1]:

Micro Structured Autothermal Methanol Reformer 305

2.4.2.2 Autothermal Methanol Reforming 2 [AMR 2]:

Micro Structured String Reactor for Autothermal Methanol

Reforming 305

2.4.2.3 Catalyst Development for Methanol Decomposition 307

2.4.3 Hydrocarbon Reforming 307

2.4.3.1 Methane Steam Reforming 307

2.4.3.2 Development of Catalyst Coatings for Methane Steam Reforming in

Micro Channels 308

2.4.3.3 Hydrocarbon Reforming 1 [HCR 1]: Micro Structured Monoliths for

Partial Methane Oxidation 308

2.4.3.4 Hydrocarbon Reforming 2 [HCR 2]: Partial Methane Oxidation Heat

Exchanger/Reactor 311

2.4.3.5 Hydrocarbon Reforming 3 [HCR 3]: Micro Structured Autothermal

Methane Reformer 312

2.4.3.6 Hydrocarbon Reforming 4 [HCR 4]: Compact Membrane Reactor for

Autothermal Methane Reforming 312

2.4.3.7 Hydrocarbon Reforming 5 [HCR 5]: Sandwich Reactors Applied to

Propane Steam Reforming 314

2.4.3.8 Hydrocarbon Reforming 6 [HCR 6]: Micro Structured Monoliths for

Partial Propane Oxidation and Autothermal Reforming 317

2.4.3.9 Catalyst Development for the Autothermal Reforming of Isooctane and

Gasoline in Micro Structures 319

2.5 Combustion in Micro Channels as Energy Source for Fuel

Processors 320

2.5.1 Catalytic Hydrogen Combustion 320

2.5.1.1 Mechanistic Investigations of Hydrogen Combustion 320

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2.5.1.2 Catalytic Hydrogen Combustion 1 [CHC 1]: Single-channel Micro

Reactor for Catalytic Hydrogen Combustion 321

2.5.1.3 Catalytic Hydrogen Combustion 2 [CHC 2]: Quartz-glass Micro

Reactor for Catalytic Hydrogen Combustion 322

2.5.1.4 Catalytic Hydrogen Combustion 3 [CHC 3]: Combined

Mixer/Cross-flow Combustor/Heat Exchanger for Determination of the Kinetics of

Hydrogen Oxidation 322

2.5.1.5 Catalytic Hydrogen Combustion 4 [CHC 4]: Cross-flow Combustor/

Heat Exchanger for Hydrogen Oxidation 324

2.5.1.6 Catalytic Hydrogen Combustion 5 [CHC 5]: Combination of a Mixer,

a Cross-flow Combustor/Heat Exchanger and a Heat Exchanger for

Product Quenching for Hydrogen Oxidation 326

2.5.2 Catalytic Combustion of Alcohol Fuels 328

2.5.3 Catalytic Hydrocarbon Combustion (CHCC) 328

2.5.3.1 Catalytic Hydrocarbon Combustion 1 [CHCC 1]: Ceramic Micro

Reactor for Butane Combustion 328

2.5.3.2 Catalytic Hydrocarbon Combustion 2 [CHCC 2]: MEMS System for

Butane Combustion 329

2.5.3.3 Catalytic Hydrocarbon Combustion 3 [CHCC 3]: Silicon Micro Reactor

for Butane Combustion 332

2.5.4 Homogeneous Combustion in Micro Channels 332

2.5.4.1 Modeling of Homogeneous Methane Combustion in Micro

Channels 332

2.5.4.2 Homogeneous Combustion in Micro Channels 1 [HCC 1]:

Homogeneous Hydrogen Combustion in a Micro Combustor 333

2.5.4.3 Homogeneous Combustion in Micro Channels 2 [HCC 2]:

Homogeneous Hydrogen Combustion in a 2-D Micro

Combustor 334

2.6 Micro Structured Reactors for Gas Purification (CO Clean-up) 335

2.6.1 Water-gas Shift 335

2.6.1.1 Simulation of the Effect of Integrating Heat-exchange Capabilities

into Water-gas Shift Reactors 336

2.6.1.2 Catalyst Testing for the Water-gas Shift Reaction in Micro Structures 337

2.6.1.3 Water-gas Shift 1 [WGS 1]: Stack-like Reactor Applied to Water-gas

Shift Testing 337

2.6.1.4 Water-gas Shift 2 [WGS 2]: Stack-like Reactor Applied to Water-gas

Shift 339

2.6.1.5 Water-gas Shift 3 [WGS 3]: Sandwich-type Reactor ([HCR 4])

Applied to Water-gas Shift Catalyst Testing 341

2.6.2 Preferential Carbon Monoxide Oxidation 342

2.6.2.1 Preferential Carbon Monoxide Oxidation 1 [PrOx 1]:

MEMS-like Reactor Applied to Studies of the PrOx Reaction in Micro

Channels 344

Single-plate Reactor Based on MEMS Technology 346

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Integrated Micro Structure Heat Exchanger for PrOx Applied in a

20 kW Fuel Processor 346

Stack-like Reactor Applied to PrOx 348

Integrated Heat Exchanger/Reactor for PrOx 350

Stack-like Reactor Applied to PrOx 351

2.6.3 Micro Structured Membranes for CO Clean-up 352

2.6.3.1 Micro Structured Membranes for CO Clean-up 1 [MMem 1]:

Palladium-based Reactor for Membrane-supported Water-gas Shift 353

Palladium Membrane Micro Reactor 353

Palladium Membranes in Micro Slits 355

Supported Palladium Membrane 355

Sputtered Tantalum Membrane 355

Pd and Pd77Ag23 Membranes 356

Free-standing Pd, Pd/Cu and Pd/Ag Membranes 356

2.7 Integrated Micro Structured Reactor Fuel Processing Concepts 356

2.7.1.1 Parametric Study for Coupling Highly Exothermic and Endothermic

Reactions 357

2.7.1.2 Co-current Operation of Combined Meso-scale Heat Exchangers and

Reactors for Methanol Steam Reforming 358

2.7.1.3 Feasibility Study for Combined Methane Oxidation/Steam Reforming

in an Integrated Heat Exchanger 359

2.7.2 Integrated Systems Fuelled by Methanol 360

2.7.2.1 Integrated Systems Fuelled by Methanol 1 [ISMol 1]:

Integrated Methanol Fuel Processor (Casio) 360

Integrated Methanol Fuel Processor (Motorola) 360

Integrated Autothermal Methanol Fuel Processor (Ballard) 361

Integrated Methanol Steam Reforming Fuel Processor for 20 kW

Power Output 363

Integrated Methanol Fuel Processor for 100 W Power Output 364

Integrated Methanol Fuel Processor for 15 W Power Output 365

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Integrated Methanol Fuel Processor for the Sub-watt Power

Range 366

Integrated Reformer/Combustor Reactor 367

Chip-like Methanol Reformer/Combustor 368

Micro Integrated Heat Exchanger/Reactor for Methanol Steam

Reforming 368

Micro Integrated Heat Exchanger/Fixed-bed Reactor for Methanol

Steam Reforming 369

Integrated Methanol Evaporator and Hydrogen Combustor 370

Integrated Methanol Evaporator and Methanol Reformer 371

2.7.3 Integrated Systems Fuelled by Methane 372

2.7.3.1 Integrated Systems Fuelled by Methane 1 [ISM 1]:

2.7.3.2 Integrated Systems Fuelled by Methane 2 [ISM 2]:

2.7.3.3 Design Study for the Multi-stage Adiabatic Mode 372

2.7.4 Integrated Systems Running on Various Fuels 374

2.7.4.1 Integrated Systems Running on Various Fuels 1 [ISV 1]:

Integrated Evaporator/Burner Device for Automotive

Applications 374

Combined System of Integrated Reformer/Heat Exchanger and

Evaporator/Heat Exchanger Devices for Automotive Applications 375

Combined System of Integrated Reformer/Heat Exchanger and

Evaporator/Heat Exchanger Devices for Automotive Applications 375

Integrated Evaporator/Reformer/Burner Device for Automotive

Applications 377

Combined Evaporator/Reformer/Burner Device 379

Integrated Reformer/Burner Device for Various Fuels 380

Integrated Steam Reformer/Heat Exchanger for Isooctane 380

Design of an Integrated MEMS Reformer/Burner Device for

Butane 381

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2.8 Comparison of Micro Structured Fuel Processor Systems with

Conventional Technologies 381

2.8.1.1 Comparison on a Larger Scale Between a Shell and Tube Heat

Exchanger, a Porous Metal Structure and a Plate and Fin Heat

Exchanger Applied to Preferential CO Oxidation 382

2.8.1.2 Comparison Between Packed Bed and Coating in Micro Tubes Applied

to Methanol Steam Reforming 383

2.8.1.3 Comparison Between Coated Micro Structures and a Conventional

Monolith Applied to Autothermal Methanol Reforming 383

2.8.1.4 Comparison Between a Micro Structured Monolith and Conventional

Monoliths Applied to Partial Oxidation of Methane 383

Monolith Applied to Water-gas Shift 384

Monolith Applied to Preferential Oxidation of Carbon Monoxide 384

2.9 Fabrication Techniques for Micro Structured Energy Generation

2.10 Catalyst Coating Techniques for Micro Structures and Their

Application in Fuel Processing 392

2.10.1 Coating of Ready-made Catalyst 392

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3 Catalyst Screening 409

3.1 Introduction 409

3.1.1 Catalyst Screening During the Last Decade 409

3.1.2 Current Situation and Future Challenges for Catalyst Screening 410

3.1.2.1 Library Size and Design 410

3.1.2.2 Sample Handling and Characterization 410

3.1.2.3 Automated Measurement and Analysis 410

3.1.2.4 Data Handling 411

3.1.2.5 In Situ Surface Science Studies to Provide Micro Kinetics 411

3.1.2.6 Multidisciplinary Knowledge Beyond Chemistry and Chemical

Engineering Needed for Future Catalyst Screening 413

3.1.3 Features of Chemical Micro Process Engineering to Impact on Catalyst

Screening 413

3.1.3.1 Flow Conditions in Small-sized Reactors 413

3.1.3.2 Analytical Expressions of Laminar Flow for Consolidation of Screening

Experiments 413

3.1.3.3 Impact of Laminar-flow Descriptions on Computational Evaluation

Methods 414

3.1.3.4 Heat Transport and Thermal Overshooting 414

3.1.3.5 Exploration of Novel Reaction Regimes by Micro-space Operation 414

3.1.3.6 Up-scaling 415

3.1.4 Structure of the Contents of the Chapter 415

3.2 Catalyst Preparation Methodology 416

3.2.1 Catalyst Deposition 416

3.2.1.1 Manual Impregnation Procedure 416

3.2.1.2 Semi-automated Impregnation Method 417

3.2.1.3 Catalyst Powder Injection 418

3.2.1.4 Catalyst Pellet Preparation 418

3.2.1.5 Parallel Sputter Coating 419

3.3 Parallel Batch Screening Reactors 424

3.3.1 Reactor 1 [R 1]: Agitated Mini-autoclaves 424

3.3.4 Lawn-format Assays 428

3.3.5 Catalyst Screening by Multistep Synthesis 428

3.4 Screening Reactors for Steady Continuous Operation 431

3.4.1 Multiple Micro Channel Array Reactors 431

3.4.1.1 Reactor 4 [R 4]: Stacked Platelet Screening System 431

3.4.1.2 Reactor 5 [R 5]: 10-fold Parallel Reactor with Exchangeable Flow

Distribution Section 434

3.4.1.3 Reactor 6 [R 6]: Micro Reactor for Steam Reforming Catalyst Testing 437

3.4.1.4 Reactor 7 [R 7]: High-throughput Micro Reactor with Parallel Micro

Compartments 438

3.4.1.5 Reactor 8 [R 8]: Modular Screening Reactor Unit 440

3.4.2 Chip-type Screening Reactors 442

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3.4.2.1 Reactor 9 [R 9]: Laboratory Automaton Integrated Chip-like

Microsystem 442

3.4.2.2 Reactor 10 [R 10]: Chip-based Catalytic Reactor 442

3.4.2.3 Reactor 11 [R 11]: Chemical Processing Microsystem 444

3.4.3 Pellet-type and Ceramic Reactors 446

3.4.3.1 Reactor 12 [R 12]: Alumina Tablets Equipped Parallel Gas-phase

Reactor 446

3.4.3.2 Reactor 13 [R 13]: Ceramic Monolith Reactor 449

3.4.3.3 Reactor 14 [R 14]: High-pressure Fixed-bed Reactor 4513.4.3.4 Reactor 15 [R 15]: Multiple-bead Pellet-type Catalyst Carrier Reactor 452

3.4.4 Well-type Screening Reactors 453

3.4.4.1 Infrared/Thermography Monitored Screening Reactor 453

3.4.4.2 Reactor 16 [R 16]: Catalyst Filled Borings Reactor 454

3.4.4.3 Reactor 17 [R 17]: Sputtered Catalyst Spots on Quartz Wafer Reactor 457

3.4.4.4 Reactor 18 [R 18]: Polymerization Reactions Screening Reactor 459

3.4.4.5 Reactor 19 [R 19]: Photochemical Active Catalyst Parallel Screening

Reactor 459

3.4.4.6 Reactor 20 [R 20]: Microstructured Chips with Catalyst-coated

Channels 460

3.4.4.7 Reactor 21 [R 21]: 64-Channel Tubular Disk Fixed-bed Reactor 460

3.4.4.8 Reactor 22 [R 22]: The Microstructured Titer Plate Reactor Concept 461

3.4.4.9 Physical Parameter Screening Reactor 469

3.5 Reactors for Transient/Dynamic Operation 470

3.5.1 Transient Operations in Microstructured Gas-phase Reactors 470

3.5.1.1 Reactor 23 [R 23]: Microstructured Titer Plate Transient Reactor

Concept 471

3.5.2 Dynamic Sequential Screening in Liquid/Liquid and Gas/Liquid

Reactors 477

3.5.2.1 Reactor 24 [R 24]: High-throughput Gas/Liquid and Liquid/Liquid

Dynamic Sequential Screening Reactor 477

3.5.2.2 Multi-port Valves, Injection Valves and Sensors 480

3.6 Computational Evaluation Methods 483

3.6.1 Evaluations Following Biological Means 484

3.6.2 Numerical Evaluation Methods 487

3.6.3 Kinetics Derived from Signal Dispersion 489

References 498

4 Micro Structured Reactor Plant Concepts 505

4.1 Micro Reactor or Micro Structured Reactor Plant (MRP) 505

4.2 Applicable Principles for Micro Structured Reactor Plant (MRP)

Design 507

4.2.1 Miniplant Technology – A Model for the Micro Structured Reactor

Plant Concept 510

4.2.2 The Micro Unit Operations Concept 511

4.2.3 Design Problems of Chemical Micro Structured Reactor Plants 511

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4.3 Process Conception and Economics 515

4.3.1 Market Study and Availability of Micro Structured Reactors 516

4.3.2 Pilot Study 517

4.4 Early Concepts for Micro Structured Reactor Plant Design 518

4.4.1 Paradigm Change Drives Miniplant Design Methodology 519

4.4.1.1 Reduction of Process Complexity for Distributed Chemical

Manufacture 519

4.4.1.2 Historical Analysis of Chemical Plant Development 520

4.4.1.4 Supply-chain Systems 521

4.4.2 Reactor 1 [R 1]: Concept for an HCN Miniplant 522

4.4.3 Reactor 2 [R 2]: Concept for a Disposable HF Miniplant 523

4.4.3.1 Use of Polymers as Disposable Construction Material 523

4.4.3.2 Capacity of a Disposable Plant for HF Production 523

4.5 Fluidic and Electrical Interconnects –

Device-to-device and Device-to-world 523

4.5.1 Reactor 3 [R 3]: Fluidic Manifold Concept –

Micro Structured Reactor-to-micro Structured Reactor 524

4.5.2 Reactor 4 [R 4]: Commercially Available Fluidic Interconnects –

Micro Structured Reactor-to-micro Structured Reactor 525

4.5.3 Reactor 5 [R 5]: Specially High-pressure Fluidic Interconnect –

4.6 Table-top Laboratory-scale Plants 533

4.6.1 Reactor 9 [R 9]: CPC Table-top Reactors 534

4.6.2 Reactor 10 [R 10]: Microinnova ‘Chemical Production Anywhere’

4.6.5 Reactor 13 [R 13]: Modular Micro Reaction System FAMOS

(Fraunhofer-Allianz Modulares Mikroreaktionssystem) 542

4.6.6 Reactor 14 [R 14]: EM Modular Microreaction System

(Ehrfeld Mikrotechnik) 544

4.6.7 Reactor 15 [R 15]: Integrated Chemical Synthesizer 546

4.6.8 Reactor 16 [R 16]: Integrated Micro Laboratory Disk Synthesizer 549

4.6.9 Reactor 17 [R 17]: The NeSSI Modular Micro Plant Concept 551

4.6.10 Reactor 18 [R 18]: The Micro Structured Reactor Backbone Interface

Concept 551 4.6.10.1 The Backbone Interface Concept 552

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4.6.10.2 Case Study 1 [C 1]: Physical Characterization of the Set-up for an

Enantioselective Synthesis 555

4.6.10.3 Case Study 2 [C 2]: Chemical Characterization of the Backbone Using

the Sulfonation of Toluene with Gaseous SO3 559

4.7 Hybrid Plants 562

4.7.1 Reactor 19 [R 19]: Micro Structured Reactor – Miniplant Hybrid

Combination 562

4.7.2 Reactor 20 [R 20]: Hybrid Methanol Steam Reformer 563

4.7.3 Reactor 21 [R 21]: Hybrid Set-up of Mini-scaled and Micro Structured

Components Inside a Reactor Housing 565

4.9.2 Reactor 24 [R 24]: Micro Structured Reactor Plant for Heterogeneously

Catalyzed Gas-phase Reactions 569

4.9.3 Reactor 25 [R 25]: Micro Structured Reactor Plant for H2O2

4.11.1.3 Automation 3 [A 3]: User-ajustable Process Control System 579 4.11.1.4 Automation 4 [A 4]: Sensor Analytical Manager 583

4.11.2 Inline Analysis, Actuators and Sensorics 583 4.11.2.1 Some Analytical Techniques Relevant for Micro-channel Processing 584

4.11.2.2 Automation 5 [A 5]: Inline Sensors According to the ISA SP76

4.11.2.7 Automation 10 [A 10]: High-pressure Flow Cell for Optical Microscopic

Observations 589 4.11.2.8 Automation 11 [A 11]: Flow Cell for Optical Inspections 590

4.11.2.9 Automation 12 [A 12]: Golden Gate® Single Reflection Diamond ATR

Unit 590

4.11.2.10 Automation 13 [A 13]: Combination of Inline Sensors with Electronic

and Fluidic Bus System 590

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4.11.2.11 Automation 14 [A 14]: Booster Pumps 593

4.11.3 Process Simulation 594

4.11.3.1 Simulation 1 [S 1]: Micro Reaction Simulation Toolkit 596

4.11.3.2 Simulation 2 [S 2]: Steady-state Process Simulator 598

4.11.3.3 Simulation 3 [S 3]: Reactor Modeling for a Homogeneous Catalytic

Reaction 598

4.12 Process Engineering 599

4.12.1 Basic Engineering 599

4.12.2 Detailed Engineering 601

4.12.2.1 Engineering 1 [E 1]: Computer-aided Plant Design Software 601

4.12.2.2 Engineering 2 [E 2]: Process Analyzer and Sample-handling System 604 4.12.2.3 Engineering 3 [E 3]: The μChemTech Piping Concept 604

4.12.3 Scale-up, Flow Distribution and Interface to the Macroscopic World 605

4.12.4 Calculation of Fluid Dynamics in Rectangular Channels 610

4.12.4.1 Simulation of a Gas-phase Reaction 611

4.12.4.2 Residence Time Distribution for Guided Flow in Channels 611

4.12.4.3 Residence Time Distribution for Non-guided Flow 612

4.12.4.4 Calculation of Cumulative Residence Time Distribution 613

4.12.4.5 Calculations for Laminar- and Plug-flow Reactors 614

4.12.4.6 External Numbering-up and Flow Distribution 615

4.12.4.7 External Flow Distribution 615

4.13 New Processes for Cost-efficient Reactor Manufacturing 618

4.13.1 Ceramic Foil Manufacturing 619

4.13.2 Solder-based Interconnection Techniques 620

4.13.2.1 Channel Manufacturing by Copper Etching 620

4.13.2.2 Typical Application – Micro CPU Cooler 620

4.13.3 Printed Circuit Heat Exchanger Technology 621

4.13.3.1 Stainless-steel Diffusion Bonding 622

4.13.3.2 Catalyst Carrier Coating Inside Bonded Reactors 622

4.13.4 Online Reactor Manufacturing 622

4.13.4.1 Continuous Coating Processes in the Polymer Industry 622

4.13.4.2 Adaptation of Industrial Online Processes to Micro Structured Reactor

Manufacturing 622 4.13.4.3 Production Modules 624

4.13.4.4 Monolithic Heat Exchanger Manufacturing 629

References 630

Subject Index 639

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About one year ago the book “Chemical Micro Process Engineering – Fundamentals,Modelling, and Reactions” was released by the author team Hessel, Hardt andLöwe It described the fundamentals of the new technology and presented in detailapplications concerning organic and inorganic reactions as well as gas-phasereactions Thus, it provided insights for the readers how mature are today’s microreactors for real-world applications What was missing is the processing beforeand after such experiments “Before” are the unit operations which are part ofevery reaction, e.g mixing and heat transfer “After” is the combination of several(unit) operations including product purification to a complete process and theerection of a plant for this purpose, as e.g given for the field of fuel processing andrespective auxiliary power units From a commercial perspective, there is a need tohave a description about “micro-reactor process design” for finally gathering costcalculations, now that the first part of the book series about “micro-reactor design”has been released – thus, the new book part is subtitled “Processing and Plants”.Facing the (unit) operations of chemical engineering, microstructured devicesoffer improvements of existing processing and even completely novel possibilities,not covered by today’s apparatus At best, one would have given directly acompendium on all unit operations including their several sub-versions For mixing,for example, this would have to encompass blending, emulsification, foaming, gasabsorption, suspension, and more Having a glance on the current literature inthis field, it is evident that there are more than enough scientific papers to fill abook on the topic mixing in all its particulars The same holds for the “after”-reactionprocessing Thus, a decision had to be made and topics of major interest had to beselected

“Mixing” is the key to many improvements concerning the performance ofreactions, in particular in the field of organic synthesis Here, the focus was drawn

on mixing of miscible fluids, since this alone serves to fill an extended chapter.Heat transfer would have been the second most important subject; but books onmicro-channel heat transfer are already on the market “Fuel processing” is thecurrent main application of heterogeneous gas-phase processing using micro-structured reactors The corresponding target application, which is energy genera-tion, is regarded to be of crucial relevance for our society and industry, as e.g thefunding policies of the EU or of the U.S demonstrate The development of catalysts

is central for having highly active reformers, water-gas shift reactors, or

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gas-purification reactors; thus, to have a further chapter on catalyst screening was quitelogical As a last chapter, plant concepts are being discussed Albeit this development

is in its infancy, it is advised to have it as a separate topic here Microstructuredreactors pose their individual needs on interface development, process control,tubing and other peripherals, and all other aspects of plant built-up The provision

of robust plants is the final step needed for a commercial acceptance of the noveltechnology The series “Chemical Micro Process Engineering” is, accordingly, notcomplete now; further descriptions of unit operations and their combinations have

to be added in future But the subjects discussed now are given in a comprehensivemanner and on the latest state of the art Other topics of relevance such as heattransfer or dispersion mixing may be considered later

In the meantime, the topic chemical micro processing engineering and reactor technology have gained even more attention in the scientific world There

micro-is hardly any conference in chemical engineering which has not micro-reactortechnology as key topic and gives an own session to it Scientific publishing housesknow that micro-reactor articles are of major interest for their audience Specialissues of their journals are prepared on the subject Industry is not only testingmicro-reactor technology, but is actually starting using it In particular, micro-structured reactor plant concepts are on the way to be realized The interest isworld-wide and indeed countries such as Japan, Korea and China have becomeactive besides France, U.K., Germany, U.S., and The Netherlands The micro-reactortechnology has become a true part of globalization Still, there are believers andthose who are more reluctant to this new technology But the developments are not

on a national level anymore It is everyone’s own fortune how to handle the newpossibilities Chemical micro process engineering is deeply interdisciplinary and aknowledge-based technology; there is considerable capital investment on the side

of the traditional chemical engineering One cannot simply “buy” the newtechnology; it is more a strategic and long-lasting decision to do so On the otherside, it is sometimes very simple to have profits from micro reactors, as e.g fororganometallic reactions or processes with explosive media There is simply neededthe willingness to change old habits; management decision and action should be

in favor of lengthy discussions about the “pros” and “cons” which will never come

to a unanimous decision

We would like to thank Lea Widarto for administrative work, Tobias Hang foradministrative and graphical works, Friedhelm Schönfeld for scientific advice Wealso acknowledge the help of the publishing house Wiley-VCH, the STM-booksteam and especially here Karin Sora and Rainer Münz Last but not least, weappreciate the patience of our wives during ‘ad inifinitum’ lasting works on thebook during the last year

Mainz, January 2005 Volker Hessel, Holger Löwe,

Andreas Müller, Gunther Kolb

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Abbreviations and Symbols

A/D Analog~/digital~

AC Alternate current

AISP Aluminium triisopropylate

AMG Algebraic multi-grid

AMOS Automated multiplex oligonucleotide synthesizer

AMR Autothermal methanol reforming

ANN Artificial neural net

ANSI American National Standards Institute

APS Average particle size

APU Auxiliary power units

ASCII American Standard Code for Information Interchange

ASD Anodic spark deposition

ASE Advanced silicon etching

ASIC Application specific integrated circuit

ASME American Society of Mechanical Engineers

ATP Adenosine triphosphate

ATR Autothermal reforming

AuMμRes Automated micro reaction system

BET Brunauer, Emmett, Teller (surface area)

BMBF German Ministry of Education and Science

BOE Buffered oxide etching

CAC Catalytic combustion of alcohol fuels

CAD Computer aided design

CAE Computer aided engineering

CAPD Computer aided plant design

CCD Charge-coupled device

CE European certification

CEC Capillary electrochromatography column

CER Coupled electrorotation

CFD Computational fluid dynamics

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CHC Catalytic hydrogen combustionCHCC Catalytic hydrocarbon combustionCNC Computerized Numeric ControlCOC Cyclo olefin copolymer

CPAC Center for Process Analytical ChemistryCPR Catalytic plate reactor

CPU Central processing unitCVD Chemical vapor deposition

dh Hydraulic diameterDIN Deutsche IndustrienormDMFC Direct methanol fuel cellDNA Desoxyribonucleic acidDoE Design of experimentsDRIE Deep reactive ion etching

E(t) Exit-age distribution functionEDM Electro-discharge machiningEDTA Ethylene-diamine-tetraacetic acidEDX Energy dispersive X-ray

EHD ElectrohydrodynamicEKI Electrokinetic instability

FTOL Fluorescence-turn-off lengthFVM Finite volume method

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hdisp Averaged signal height

HEPES (4-(2-Hydroxyethyl)-piperazine-1-ethane-sulfonic acid

HPLC High performance liquid chromatography

ICS Integrated chemical synthesizer

IFP Integrated fuel processor

ISBL Inside battery limit

ISM Integrated systems fuelled by methane

ISMol Integrated systems fuelled by methanol

ISV Systems running on various fuels

ITO Indium tin oxide

L0 and L(t) Characteristic dimensions of the interfacial area

LAN Local area network

LCD Liquid crystal display

LHV Lower heating value

LIGA German acronym for lithography, electroforming, moulding

(Lithograpie, Galvanik, Abformung)LPCVD Low pressure chemical vapour deposition

MCFC Molten carbonate fuel cells

MEMS Micro-electro-mechanical systems

MiRTH-e Microreactor Technology for Hydrogen and Electricity

MMem Micro-structured membranes for CO Clean-up

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MRP Microstructured reactor plantMRT Micro reaction technology

MSR Methanol steam reforming

ND Numerical diffusionNEDC New European Drive CycleNeSSI New Sampling Sensor InitiativeNIR Near infrared

OSBL Outside battery limit

p0 Pressure drop of one SAR stepPCHE Printed circuit heat-exchangerPCR Printed circuit reactorPCS Process control systemPDF Probability density functionPDMS Poly-dimethylsiloxane

PEM Proton exchange membranePEMFC Proton exchange membrane fuel cellPET Poly-ethylene terephthalate

PVD Physical vapor depositionPZT Lead-zirconate-titanate

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ROMP Ring-opening metathesis polymerization

RTD Residence time distribution

RWGS Reverse water-gas shift reaction

S/C Steam to carbon ratio

SAM Sensor analytical manager

SAR Split-and-recombine

SDS Sodium dodecyl sulphate

SEM Scanning electron microscopy

SGS Simultaneous gradient-sputtering

SHM Staggered herringbone mixer

SME Static mixing elements

SNMS Secondary neutral particles mass spectrometry

SOI Silicon on insulator

SPS Spark plasma sintering

TAP Temporal analysis of products

tdisp Critical temperature

TEM Transmission electron microscopy

TEOS Tetraethyl-ortho-silane

THF Tetrahydrofurane

TOF Turnover frequency

TPR Temperature programmed reduction

U+, U–, and U±Dimensionless slip velocities

WGS Water-gas shift reaction

WHSV Weight hourly space velocity

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X Axial coordinate

x1 Axial coordinateXPS X-ray photoelectron spectrumXRD X-ray diffraction

μ Dynamic fluid viscosityμPVT Industrial platform for modular micro process engineeringμTAS Micro total analysis system

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‘Mixing Fields’, a Demand Towards a more Knowledge-based Approach –

Room for Micro Mixers?

Many unsolved challenges remain in the field of mixing [1] The diversity of mixingtasks is large and so is their industrial importance Mixing is a good example howequipment dominates the type of processing solution chosen (see Figure 1.1) [1].Mixing has been carried out in stirred tanks over decades and all mixing problemswere solved using this assumption as a starting condition

Meanwhile, there is a slight paradigm shift apart from such equipment designdominance to a more knowledge-based approach (see Figure 1.2), with the mixingobjective in the focus, i.e the so-called ‘mixing fields’, related to the rate and scales

of segregation destruction (for a detailed definition see [1]) [1] This demands a

Figure 1.1 Design and development cycle for equipment-based design:

using pre-decided equipment, a mixing configuration is chosen by

correlations and experience For stirred tanks this configuration is given,

e.g., by the power-to-volume ratio P/V and the impeller diameter N.

Then, CFD models are made to describe the flow field [1].

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greater variety of equipment solutions and in particular specially equipment, made for one specific mixing task Recently, this has led industry to use rotor stators,static mixers, multi-shaft mixers, extruders and pulping machines [1] It stands toreasons that such development may also pave the way for using microstructuredmixers for industrial applications.

tailor-Experts predict a trend from stirred-vessel mixing to the use of continuous mixing,e.g by in-line mixers [1] This again provides a chance for many microstructuredmixers

1.1.2

Drivers for Mixing in Micro Spaces

Many passive microstructured mixers (see e.g [2, 3]) follow design principles used

at the macro-scale for static mixers with internal packings [4] It stands to reasonthat some of the advantages in processing claimed for conventional static mixeralso apply or may be even more pronounced when using static mixers [4]:

compactness and low capital cost

low energy consumption and other operating expenses

negligible wear and no moving parts, which minimizes maintenance

lack of penetrating shafts and seals, which provides closed-system operation

short mixing time and well-defined mixing behavior

narrow residence-time distribution

performance independent of pressure and temperature

Figure 1.2 Design and development cycle for mixing-field based design:

there is a selection of the mixing equipment based on the process requirements This leads to the specification of a mixing field CFD simulations give the flow field reduced to a multi-scale mixing model.

The mixing field is integrated with other models of the key process mechanisms, aiming at giving an entire picture of the process [1].

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In addition, the following specific chemical engineering drivers may govern thedecision to use a micro or microstructured mixer:

enabling technology for niche mixing, where conventional mixers fail

enabling technology in particular for mixing under laminar-flow conditions inminute spaces

fast mixing for even faster reactions in chemical synthesis (see e.g [5])

analytical processing of fast reactions, e.g for quench-flow analysis (< 1 ms) tostudy rapid biological transformations [6]

laminar mixing of viscous media [7], as most micro-flow processing is anyway inthat regime

mixing at only small overall internal device volumes, e.g for

– handling of rare, precious samples in analysis or synthesis

– handling and screening of numerous samples on a small format in chemicaland biological analysis [8–15])

mixing below threshold dimensions and at small partial internal volumes toensure safety [16–19], for both mechanistic and thermal reasons, respectively[16]

mixing of a flow of high structural regularity [20], e.g to enhance predictability

of modeling and to improve scaling-/numbering-up

1.1.3

Mixing Principles

Mixing in minute spaces can basically rely only on two principles which are diffusionand convection Diffusion between short distances, establishing high concentrationgradients (see e.g [21]), was initially the most frequently applied principle by simplymaking the channels themselves smaller and smaller Soon, the limits of thatstrategy, also in terms of robustness (fouling) and costs (complex microfabrication),became obvious In recent years, various methods were developed to overcome thelimits by diffusion mixing, all of them based on the induction of secondary-flow(convective) patterns which are superposed on the main flow, often in the verticaldirection to the flow axis This includes recirculation patterns, chaotic advectionand swirling flows, just to name a few Convection is effective for mixing, since itserves to enlarge mixing interfaces Convections of ‘gross’ mass portions can beused at a much larger scale to ‘stir’ complete chamber volumes, e.g by ultrasound,

by elektrokinetic instability or acoustic means At high Reynolds numbers, turbulentmixing can be utilized; however, this is often not practicable, as this impliesachievement of unrealistic large flow velocities The few specially equipment known

to use turbulence rely either on free-guided flows or guide through meso-scalechannels

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Means for Mixing of Micro Spaces

The means of mixing can be classified as either active or passive Passive micro mixers

use part of the flow energy for feeding and thereby generate special flow schemeswith ultra-thin flow compartments such as lamellae for diffusion mixing or utilize

chaotic advection by secondary flows to enlarge the interfaces Active micro mixers

rely on moving parts or externally applied forcing functions such as pressure orelectric field

External energy sources for active mixing are, for example, ultrasound [22],

acoustic, bubble-induced vibrations [23, 24], electrokinetic instabilities [25], periodicvariation of flow rate [26–28], electrowetting induced merging of droplets [29],piezoelectric vibrating membranes [30], magneto-hydrodynamic action [31], smallimpellers [32], integrated micro valves/pumps [33] and many others, which arelisted in detail in Section 1.2

Devices relying on passive mixing utilize the flow energy, e.g due to pumping

action or hydrostatic potential, to restructure a flow in a way which results in fastermixing For example, thin multi-lamellae can be created in one step in special feedarrangements, termed interdigital [20, 34–42] A serial way of creating multi-lamellaecan be achieved by split-and-recombine (SAR) flow guidance [7, 43, 140] Chaoticmixing results from superimposed recirculation flow patterns (such as helical flows),with an exponential increase in specific interfaces [27, 28, 44–50] The injection ofmany sub-streams, e.g via an array of nozzles, into one main stream can createmicro-plumes with large interfaces [51] Turbulent mixing can be achieved bycollision of jets [52–54] A number of specially flow guidances are known as well.For example, re-directed flows create eddies which are exploited in Coanda effectmixers [55] and in other recycle-flow mixers [56] These and more passive principlesare described in Section 1.3

There are more reports about and more different types for passive than for activemicro mixers This is understandable, since for many applications flow energy isgiven Also, active micro mixers may be more difficult to fabricate, as they requirespecial additional elements besides the normal fluid pathway as in the case of passivedevices This also demands control of these functions, i.e further externalequipment may be needed All this implies greater complexity for active devices

On the other hand, these tools are specially designed for mixing tasks which passivemixers cannot accomplish, i.e mixing at very low flow velocities and/or of largefluid chambers Sometimes, active mixing devices may consume a much smallerfootprint area than passive ones with all their fluid feed channel architecture andlarge inlet and outlet ports The complexity of active micro mixers may not be aproblem any more for future devices, when microsystem integration is brought to

a more advanced level

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Generic Microstructured Elements for Micro-mixer Devices

The above-mentioned micro-mixer means have to be ‘transformed’ into physicalobjects, i.e the microstructures which then perform the mixing (see Figure 1.3).Bi-lamination can be achieved in T- and Y-flow structures [6, 57], which are miniatu-rized analogues of conventional mixing tees Multi-lamination is done via structureswith alternate feeds The latter are realized either by interdigital [20, 34–41] orbifurcation [42] structures To speed up mixing, thinning of the multi-lamellaeflow via geometric focusing zones can be utilized [20, 34–39] Several types of flowdividing and recombining structures were developed for SAR-type mixing, includingfork-like, stack-like, Möbius-type and 3-D curved caterpillar designs [7, 43, 125,

126, 140, 141] Chaotic mixing was first achieved by alternately arranged slantedgrooves, so-called herringbone structures, in a micro channel [44, 45] Barrier-embedded structures may be added and will further improve the mixing efficiency[3, 58] Later, other structures such as simple curved channels and zig-zag channelswere used as well [27, 28, 46–50, 59] Micro-plume injection is done by multi-holeplates adjacent to a mixing chamber, as simple through-holes with straight injection[51] or complex oblique arrays with tilted injection [54]

These are just a few among other examples of microstructured designs whichare discussed in detail in the next two chapters More information about thesemicro-mixer designs can be obtained from reviews, e.g [60–66]

In addition to grouping the mixers according to their mixing principles and theirgeneric microstructure designs, a practically oriented classification refers to thecomplexity of the fluid network [25] So-called in-plane mixers rely on streams whichare divided and mixed in a fluid network confined to one level (i.e a pattern thatcan be projected on to a single plane) [25] In turn, out-of-plane mixers rely on a

Figure 1.3 Schematic diagrams of selected passive and active micro

mixing principles [66] (source IMM).

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more complex, three-dimensional fluid network Examples of in-plane mixers arebi-laminating, T- and cross-channel mixers as described [57, 67–71] SAR and mostmulti-lamination mixers act out-of-plane; examples of these device types are given

in [7, 43] and [20, 36, 37, 39], respectively Another type of out-of-plane mixer isbased on micro-plume array injection [51]

It is customary, mainly owing to fabrication needs, that for biological applicationschip-like systems with two-layer construction are used, thus being in-plane Mixersused for the same purposes have to adjust to this fact Since multi-laminationtypically needs several layers to achieve the proper feeding pathways, other mixerswith simpler designs such as the electrokinetic instability mixer need to be applied[25] In contrast, chemical applications, where the mixer is only associated withpart of the plant and not integrated in a small, flat device, do not pose suchpreferences; indeed, multi-layer microfabrication architectures have been used.1.1.6

Experimental Characterization of Mixing in Microstructured Devices

For simulation characterization, the reader should refer to Chapter 2, Modeling and Simulation of Micro Reactors, in the first volume of this series [72].

For experimental characterization, flow visualization by colored or fluorescent

streams is the most facile method Dilution-type experiments contact dyed and pure

water streams (passive mixing) or standing volume portions (active mixing) in atype of photometric experiment This is usually monitored with the aid of micro-scopic, photo, video or high-speed camera techniques (see e.g [20])

Reaction-type experiments underlie mixing with a very fast reaction so that mixed

regions spontaneously indicate the result of the reaction (see e.g [20]) Besidesusing ‘normal’ fast organic reactions with color formation, change or quenching[20, 73], the usage of acid–base reactions with a pH-sensitive dye or a pH indicator

is common More detailed information is given by competitive reactions, i.e two

parallel reactions [74–78] These reactions develop differently with varying pH,solvent, etc., which is influenced via mixing Such reactions were first applied fordetermining mixing efficiency in stirred batch reactors and later adapted to theneeds of micro mixer devices [36] Still later, optimized protocols were developedfor micro-mixer testing giving more accurate and more reproducible results [79]

Concentration profiling uses on- or in-line measurements of optical properties,

typically not done for the whole volume, but along lines such as the channel section (see e.g [20]) Concentrations are accessible by photometric, electric orfluorescence measurements Furthermore, vibrational analysis such as IR andRaman spectroscopy can be used for the same task [80, 81] Concentration profilingcan also be achieved simply by gray-scale or comparable image analysis forquantitative data extraction from microscopy images of colored flows [20, 37, 68].These techniques are the most often used and simplest ways to characterizemixing in microstructured mixers Certainly, many more were used in the past.Information on such specially techniques given in the next two chapters where therespective mixer is discussed

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Application Fields and Types of Micro Channel Mixers

Generally, application fields of micro channel based mixers encompass both modern,specialised issues such as sample preparation for analysis and traditional, wide-spread usable mixing tasks such as reaction, gas absorption, emulsification, foamingand blending [63, 64, 66, 72, 82] (see also [83–90]) For novel and modern chemical

and biochemical analysis, typically micro mixer elements serve as mixing units within

credit card-sized fluidic chips, often being complex integrated systems Chip-like

micro mixer components (micro mixers) are employed for the more conventional

chemical and chemical engineering applications at the laboratory scale At pilot oreven production scales, much bigger components are applied for the same mixingtasks, typically comprising microstructures in a large housing, therefore being more

correctly termed micro structured mixers.

Micro mixer elements, micro mixers and micro structured mixers typically haveflows in the ml h–1, 1 l h–1 and 1000 l h–1 ranges, respectively, thus covering thewhole flow range up to the conventional static mixers and being amenable to analysisand chemical production as well (see Figure 1.4) When used at the upper flowlimit, microstructured mixers can act as process-intensification (PI) equipment

Figure 1.4 Micro mixers (laboratory scale) and micro structured mixers

(pilot scale) close the gap with static mixers, yielding apparatus for a multi-scale

concept Today’s microstructured devices achieve mixing at up to about 1 m 3 h –1

liquid throughput [2, 64] (by courtesy of RSC and Chemical Engineering).

Tiêu đề	Chemical Micro Process Engineering Processing and Plants
Tác giả	Volker Hessel, Holger Lửwe, Andreas Mỹller, Gunther Kolb
Trường học	University of [Name not specified]
Chuyên ngành	Chemical Engineering
Thể loại	Giáo trình
Năm xuất bản	2004
Thành phố	[City not specified]

Định dạng
Số trang	684
Dung lượng	17,25 MB