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Vacuum Technology in the Chemical Industry

Vacuum Technology in the Chemical Industry

Wolfgang Jorisch (Editor)

ISBN: 978-3-527-65391-1

Feb 2015

392 pages

$140.99

Description

Based on the very successful German edition and a seminar held by the German Engineers` Association (VDI) on a regular basis for years now, this English edition has been thoroughly updated and revised to reflect the latest developments. It supplies in particular the special aspects of vacuum technology, applied vacuum pump types and vacuum engineering in the chemical, pharmaceutical and process industry application-segments. The text includes chapters dedicated to latest European regulations for operating in hazardous zones with vacuum systems, methods for process pressure control and regulation and leak detection.
All of the authors work or did work at a selection of the most important German companies involved in vacuum technology, and their expertise is disseminated here for engineers working in vacuum technology, chemical process design, plant operation, and mechanical engineering.

List of Contributors XV

1 Fundamentals of Vacuum Technology 1
Wolfgang Jorisch

1.1 Introduction 1

1.2 Fundamentals of Vacuum Technology 2

1.2.1 Fundamentals of Gas Kinetics 3

1.2.2 Equation of State for Ideal Gases 6

1.2.3 Flow of Gases through Pipes in a Vacuum 7

1.2.4 Vacuum Pumps Overview 12

References 14

2 Condensation under Vacuum 15
Harald Grave

2.1 What Is Condensation? 15

2.2 Condensation under Vacuum without Inert 16

2.3 Condensation with Inert Gases 17

2.4 Saturated Inert Gas–Vapour Mixtures 19

2.5 Vapour–Liquid Equilibrium 20

2.6 Types of Condensers 21

2.7 Heat Transfer and Condensation Temperature in a Surface Condenser 24

2.8 Vacuum Control in Condensers 30

2.9 Installation of Condensers 30

2.10 Special Condenser Types 32

Further Reading 34

3 Liquid Ring Vacuum Pumps in Industrial Process Applications 35
Pierre Hähre

3.1 Design and Functional Principle of Liquid Ring Vacuum Pumps 35

3.1.1 Functional Principle 35

3.1.2 Design Details 37

3.2 Operating Behaviour and Design of Liquid Ring Vacuum Pumps 40

3.2.1 Hydraulics 40

3.2.2 Thermodynamics 41

3.2.3 Counterpressure, Air Pressure 45

3.2.4 Design Data 47

3.3 Vibration and Noise Emission with Liquid Ring Vacuum Pumps 48

3.3.1 Vibration Stimulation by Imbalance of Rotary Solids 48

3.3.2 Vibration Stimulation by Pulsation 49

3.3.3 Vibration Stimulation by Flow Separations 50

3.3.4 Measures for Vibration Damping 50

3.4 Selection of Suitable Liquid Ring Vacuum Pumps 51

3.4.1 Simple, Robust and Suitable for the Entire Pressure Range 52

3.4.2 The Vacuum Pump for the Delivery of Liquid 52

3.4.3 Quiet and Compact for a Vacuum Close to the Vapour Pressure 57

3.4.4 A Compact Unit 59

3.4.5 The Right Sealing Concept 59

3.4.6 Vacuum Control 63

3.4.7 Valve Control 63

3.4.8 Power Adjustment 64

3.5 Process Connection and Plant Construction 67

3.5.1 Set-Up and Operation of Liquid Ring Vacuum Pumps 67

3.5.2 Conveyance of the Operating Liquid 68

3.5.3 Precompression 69

3.6 Main Damage Symptoms 73

3.6.1 Water Impact 73

3.6.2 Cavitation 73

3.6.3 Calcareous Deposits and How to Avoid Them 75

3.7 Table of Symbols 78

4 Steam Jet Vacuum Pumps 81
Harald Grave

4.1 Design and Function of a Jet Pump 81

4.2 Operating Behaviour and Characteristic 84

4.3 Control of Jet Compressors 87

4.4 Multi-Stage Steam Jet Vacuum Pumps 90

4.5 Comparison of Steam, Air and Other Motive Media 93

Further Reading 95

5 Mechanical Vacuum Pumps 97
Wolfgang Jorisch

5.1 Introduction 97

5.2 The Different Types of Mechanical Vacuum Pumps 99

5.2.1 Reciprocating Piston Vacuum Pump 100

5.2.2 Diaphragm Vacuum Pump 100

5.2.3 Rotary Vane Vacuum Pump 101

5.2.4 Rotary Plunger Vacuum Pump 102

5.2.5 Roots Vacuum Pump 103

5.2.6 Dry Compressing Vacuum Pump 104

5.3 When Using Various Vacuum Pump Designs in the Chemical or Pharmaceutical Process Industry, the Following Must Be Observed 104

5.3.1 Circulatory-Lubricated Rotary Vane and Rotary Plunger Vacuum Pumps 104

5.3.2 Fresh-Oil-Lubricated Rotary Vane Vacuum Pumps 108

5.3.3 Dry, Respectively Oil-Free Compressing Vacuum Pumps 110

5.3.4 Roots Vacuum Pumps 111

5.3.5 Dry Compressing Vacuum Pumps for Chemistry Applications 118

References 128

6 Basics of the Explosion Protection and Safety-Technical Requirements on Vacuum Pumps for Manufacturers and Operating Companies 129
Hartmut Härtel

6.1 Introduction 129

6.2 Explosion Protection 130

6.2.1 General Basics 130

6.2.2 Explosive Atmosphere and Safety Characteristics 131

6.2.3 Measures of the Explosion Protection 144

6.3 Directive 99/92/EC 146

6.3.1 Requirements on Operating Companies of Vacuum Pumps 146

6.3.2 Classification of Hazardous Areas into Zones 149

6.4 Directive 94/9/EC 150

6.4.1 Equipment Groups and Categories 150

6.4.2 Assignment between Equipment Categories and Zones 152

6.4.3 Requirements on Manufacturers of Vacuum Pumps 153

6.4.4 Conformity Assessment Procedure 154

6.4.5 Application of the Regulations of the Directive 155

6.5 Summary 157

References 158

Further Reading 159

7 Measurement Methods for Gross and Fine Vacuum 161
Werner Große Bley

7.1 Pressure Units and Vacuum Ranges 161

7.2 Directly and Indirectly Measuring Vacuum Gauges and Their Measurement Ranges 162

7.3 Hydrostatic Manometers 163

7.4 Mechanical and Electromechanical Vacuum Gauges 164

7.4.1 Sensors with Strain Gauges 165

7.4.2 Thermal Conductivity Gauges 167

7.4.3 Thermal Conductivity Gauges with Constant Filament Heating Power 169

7.4.4 Thermal Conductivity Gauges with Constant Filament Temperature 170

7.4.5 Environmental and Process Impacts on Thermal Conductivity Gauges 170

References 172

Further Reading 172

8 Leak Detection Methods 173
Werner Große Bley

8.1 Definition of Leakage Rates 173

8.2 Acceptable Leakage Rate of Chemical Plants 174

8.3 Methods of Leak Detection 175

8.4 Helium as a Tracer Gas 176

8.5 Leak Detection with Helium Leak Detector 176

8.6 Leak Detection of Systems in the Medium-Vacuum Range 177

8.6.1 Connection of Leak Detector to the Vacuum System of a Plant 177

8.6.2 Detection Limit for Leakage Rates at Different Connection Positions of a Multistage Pumping System 179

8.7 Leak Detection on Systems in the Rough Vacuum Range 180

8.7.1 Connection of Leak Detector Directly to the Process Vacuum 180

8.7.2 Connection of Leak Detector at the Exhaust of the Vacuum System 180

8.8 Leak Detection and Signal Response Time 181

8.9 Properties and Specifications of Helium Leak Detectors 182

8.10 Helium Leak Detection in Industrial Rough Vacuum Applications without Need of a Mass Spectrometer 183

8.10.1 Principle of theWise Technology® Sensor 185

8.10.2 Application 186

References 187

Further Reading 187

European Standards 187

9 Vacuum Crystallisation 189
Guenter Hofmann

9.1 Introduction 189

9.2 Crystallisation Theory for Practice 189

9.3 Types of Crystallisers 195

9.4 Periphery 203

9.5 Process Particularities 205

9.5.1 Surface-Cooling Crystallisation 206

9.5.2 Vacuum-Cooling Crystallisation 207

9.5.3 Evaporation Crystallisation 207

9.6 Example – Crystallisation of Sodium Chloride 207

References 209

10 Why Evaporation under Vacuum? 211
Gregor Klinke

Summary 211

10.1 Introduction 211

10.2 Thermodynamics of Evaporation 211

10.3 Pressure/Vacuum Evaporation Comparison 213

10.3.1 Vapour Utilisation 214

10.3.2 Design of the Apparatuses 214

10.3.3 Machine Equipment 214

10.3.4 Corrosion 215

10.3.5 Insulation 215

10.3.6 Safety Aspects 215

10.3.7 Product Properties 215

10.3.8 Boiling Range 216

10.4 Possibility of Vapour Utilization 217

10.4.1 External Utilization 217

10.4.2 Multi-Stage Evaporation 217

10.4.3 Mechanical Vapour Recompression 217

Further Reading 220

11 Evaporators for Coarse Vacuum 221
Gregor Klinke

Summary 221

11.1 Introduction 221

11.2 Criteria for the Selection of an Evaporator 221

11.2.1 Suitability for the Product 221

11.2.2 Cleaning 222

11.2.3 Quality of Heat Transfer 222

11.2.4 Required Space 222

11.2.5 Cost Efficiency 223

11.3 Evaporator Types 223

11.3.1 Agitator Evaporator 223

11.3.2 Natural Circulation Evaporator 223

11.3.3 Climbing-Film Evaporator 225

11.3.4 Falling-Film Evaporator 226

11.3.5 Forced-Circulation Evaporator 228

11.3.6 Fluidised-Bed Evaporator 230

11.3.7 Plate Evaporator 231

Further Reading 233

12 Basics of Drying Technology 235
Jürgen Oess

12.1 Basics of Solids–Liquid Separation Technology 235

12.2 Basics of Drying Technology 235

12.2.1 Convection Drying 236

12.2.2 Radiation Drying 237

12.2.3 Contact Drying 237

12.2.4 Advantages of the Vacuum Drying 242

12.3 Discontinuous Vacuum Drying 244

12.3.1 Setup of a Batch Vacuum Drying System 244

12.3.2 Operation of Discontinuous Vacuum Dryers 244

12.4 Continuous Vacuum Drying 246

12.4.1 Setup of a Batch Vacuum Drying System 246

12.4.2 Operation of Continuous Vacuum Dryers 246

12.4.3 Inlet- and Outlet Systems 247

12.5 Dryer Designs 248

Reference 249

13 Vacuum Technology Bed 251
Michael Jacob

13.1 Introduction to Fluidized Bed Technology 251

13.1.1 Open or Once-through Fluidized Bed Plants 251

13.1.2 Normal Pressure Fluidized Bed Units with Closed-Loop Systems 251

13.2 Vacuum Fluidized Bed Technology 253

13.2.1 Layout 253

13.2.2 Sequence of Operation 255

13.2.3 Fluidization at Vacuum Conditions 255

13.2.4 Heat Energy Transfer under Vacuum Conditions 256

13.2.5 Applications 257

References 258

14 Pharmaceutical Freeze-Drying Systems 259
Manfred Heldner

14.1 General Information 259

14.2 Phases of a Freeze-Drying Process 260

14.2.1 Freezing 260

14.2.2 Primary Drying – Sublimation 261

14.2.3 Secondary Drying 264

14.2.4 Final Treatment 264

14.2.5 Process Control 265

14.3 Production Freeze-Drying Systems 266

14.3.1 Drying Chamber and Shelf Assembly 267

14.3.2 Ice Condenser 270

14.3.3 Refrigerating System 271

14.3.4 Vacuum System 273

14.3.5 Cleaning of the Freeze-Drying System 274

14.3.6 Sterilisation 276

14.3.7 VHP Sterilisation 277

14.4 Final Comments 278

Further Reading 279

15 Short Path and Molecular Distillation 281
Daniel Bethge

15.1 Introduction 281

15.2 Some History 281

15.2.1 Vacuum Distillation 282

15.2.2 Short Path Evaporator 285

15.2.3 The Vacuum System 286

15.2.4 Distillation Plant 288

15.2.5 Application Examples 289

15.2.6 New Developments 292

15.3 Outlook 293

References 293

16 Rectification under Vacuum 295
Thorsten Hugen

16.1 Fundamentals of Distillation and Rectification 295

16.2 Rectification under Vacuum Conditions 298

16.3 Vacuum Rectification Design 302

16.3.1 Liquid and Gas Load 303

16.3.2 Pressure Drop 303

16.3.3 Separation Efficiency 303

16.4 Structured Packings for Vacuum Rectification 305

Nomenclature, Applied Units 309

Greek Symbols 310

Subscripts and Superscripts 310

References 310

17 Vacuum Conveying of Powders and Bulk Materials 311
Thomas Ramme

17.1 Introduction 311

17.2 BasicTheory 312

17.2.1 General 312

17.2.2 Typical Conditions in a Vacuum Conveying Line 315

17.3 Principle Function and Design of a Vacuum Conveying System 318

17.3.1 Multiple-Stage, Compressed-Air Driven Vacuum Generators 319

17.3.2 Conveying and Receiver Vessels 322

17.3.3 Filter Systems 324

17.4 Continuous Vacuum Conveying 325

17.5 Reactor- and Stirring Vessel Loading in the Chemical Industry 325

17.6 Conveying,Weighing, Dosing and Big-Bag Filling and Discharging 330

17.7 Application Parameters 330

References 330

18 Vacuum Filtration – Systemand Equipment Technology, Range and Examples of Applications, Designs 331
Franz Tomasko

18.1 Vacuum Filtration, a Mechanical Separation Process 331

18.1.1 On theTheory of Filtration and Significance of the Laboratory Experiment 332

18.1.2 Guide to Filter-Type Selection 333

18.2 Design of an Industrial Vacuum Filter Station 335

18.3 Methods of Continuous Vacuum Filtration, Types of Design and Examples of Application 337

18.3.1 Vacuum Filtration on a Curved Convex Surface, the Drum Filter 337

18.3.2 Vacuum Filtration on a Curved Concave Surface, the Internal Filter 351

18.3.3 Vacuum Filtration on a Flat Horizontal Surface 352

18.3.4 Vacuum Filtration on a Vertical Flat Surface, the Disc Filter 358

References 361

Index 363