EBOOK - Liquid Ring Vacuum Pumps, Compressors and Systems (H. Bannwarth) | Cộng đồng Kỹ thuật cơ điện Việt Nam EBOOKBKMT

EBOOK - Bơm chân không chất lỏng, máy nén và hệ thống (H. Bannwarth) - 505 Trang.

In 1991, the first edition of the technical manual “Liquid ring vacuum pumps, compressors and plants” was published in German language by the publishing house VCH Verlag in D-69496 Weinheim, Germany. Three years later, in 1994, the second, revised edition came out and I took advantage of the opportunity to update and complete it according to the progressing technical developments.

With this first edition in English language, again updated, I could fulfil the request for a translated version of the book expressed by many interested students and practitioners of industry and engineering offices at home and abroad. I express my thanks to the publishing house Wiley-VCH Verlag particularly for the again pleasant cooperation and the continuous support I enjoyed.
I would also like to express my gratitude to the managing directors of the company group Lederle GmbH and Hermetic-Pumpen GmbH, Mr. Wolfgang Krmer and Dr. Roland Kr mer for their generous support. Many thanks to all companies and publishing houses not mentioned here for kindly providing me with the respective documents.

CONTENTS:

Preface of the first edition in German language in 1991 XI
1 Gas Physics and Vacuum Technology 1
1.1 The term “vacuum” 1
1.2 Application of vacuum technology 1
1.2.1 Basic operations in process engineering 2
1.2.2 Basic fields and worked-out examples for the application of vacuum
technology 3
1.2.3 Overview of the most important vacuum processes 6
1.2.4 Basic designs of apparatus for mass transfer and mass combination 7
1.2.5 Limits to the application of vacuum in process engineering 8
1.3 Operating ranges and measuring ranges of vacuum 9
1.3.1 Vacuum pressure ranges 9
1.3.2 Vapor pressure curve of water in vacuum 9
1.3.3 Vacuum operation ranges, temperature pressure table 10
1.3.4 Total pressure measuring 12
1.3.5 Pressure meters 14
1.3.6 Definition of terms for vacuum measuring devices 21
1.4 Gas flow and vacuum ranges 23
1.4.1 Vacuum ranges and types of flow 23
1.4.2 Mean free path 23
1.4.3 Reynolds number 25
1.4.4 Gas flow, suction power, suction capacity 26
1.4.5 Flow losses in pipework 28
1.4.6 Effective suction capacity of vacuum pumps 30
1.4.7 Gas-inflow and outflow on a vacuum chamber 32
1.4.8 Practice oriented application of the gas flow calculation 34
1.5 Physical states of matter 44
1.5.1 The terms gases, vapors, vacuum 44
1.5.2 Physical basic principles of ideal gases 44
1.5.3 Standard temperature and pressure 52
1.5.4 Real gases and vapors 53
1.5.5 Phase transitions and their descriptions 55
1.6 Mixtures of ideal gases 59
1.6.1 Mass composition 59
1.6.2 Molar composition 60
1.6.3 Volumetric composition 60
1.6.4 Ideal gas mixtures and general equation of gas state 61
1.7 Gas mixtures and their calculation 63
1.7.1 Density of an ideal gas mixture 64
1.7.2 Molar mass of gas mixture 64
1.7.3 Gas constant of an ideal gas mixture 65
1.7.4 Relation between mass proportions and volume percentage 66
1.7.5 Gas laws and their special application in vacuum technology 68
1.8 Discharge of gases and vapors 73
1.8.1 General state equation of gas 73
1.8.2 Real gas factor Z 74
1.8.3 General gas constant 75
1.8.4 The special gas constant depending on the type of gas 77
1.8.5 Thermal state equation for ideal gases 78
1.8.6 Suction of dry gases and saturated air-water vapor mixture
by liquid ring vacuum pumps 79
1.8.7 Gases in mixtures with overheated vapors 97
1.8.8 Condensation and cavitation 100
1.9 Change of gas state during the compression process 100
1.9.1 The isothermal compression 101
1.9.2 The adiabatic compression 101
1.9.3 Adiabatic exponentk 102
1.9.4 Especially distinguished changes of state 104
1.10 Names and definitions in vacuum technology 105
2 Machines for Vacuum Generation 111
2.1 Overview of vacuum pumps 111
2.2 Description of vacuum pumps and their functioning 111
2.2.1 Gas transfer vacuum pumps 111
2.2.2 Gas binding vacuum pumps 120
2.3 Operating fields of pumps acc. to suction pressure 121
2.4 Suction pressure and suction capacity of different pump designs 123
2.5 Usual designs and combinations of vacuum pumps 124
2.5.1 Sliding vane vacuum pump 124
2.5.2 Multi cell vacuum pump 127
2.5.3 Liquid ring vacuum pump 129
2.5.4 Rotary plunger vacuum pump 131
2.5.5 Trochoidal vacuum pump 131
2.5.6 Roots pump 133
2.5.7 Jet pump 140
2.6 Vacuum pump units and their control 146
2.6.1 The three phases of evacuation 146
2.6.2 Vacuum pumps in series 147
2.7 Names and definitions of vacuum pumps and their accessories 150
3 Liquid Ring Vacuum Pumps and Liquid Ring Compressors 157
3.1 Liquid ring vacuum pumps and compressors with radial flow 157
3.2 Liquid ring machines with axial flow 159
3.2.1. Liquid ring pump with lateral channel 159
3.2.2 Liquid ring pump with eccentric screw wheel 161
3.2.3 Liquid ring machines with elliptic casing 162
3.2.4 Liquid ring compressors 163
3.2.5 Liquid ring machines with eccentrically installed impeller 164
3.3 The operating liquid 177
3.3.1 Influence of the operating temperature of the ring liquid on suction
capacity and suction pressure of the pump 178
3.3.2 Operating behavior at different densities of the operating liquid 180
3.3.3 Influence of the viscosity of the operating liquid on the discharge
behavior of the pump 182
3.3.4 Solubility of gases in the operating liquid 183
3.4 The quantity of operating liquid 184
3.5 The behavior of liquid ring vacuum pumps in case of liquid
being carried simultaneously 186
3.6 The carrying of contaminants 187
3.7 The condensation effect 187
3.8 Characteristic curves of liquid ring machines at different compression
pressures and suction pressures 189
3.9 The similarity law for liquid ring gas pumps 189
3.10 Pump performance and power consumption of liquid ring
machines 191
3.10.1 Characteristic curves of liquid ring vacuum pumps and
compressors 193
3.11 Cavitation 195
3.12 Cavitation protection 196
3.13 Gas ejector in combination with the liquid ring vacuum pump 197
3.13.1 Operating range of a vacuum pump with gas ejector 198
3.13.2 Operation mode of gas ejectors 199
3.14 Operating modes, supply of operating liquid 202
3.14.1 Operation without liquid recirculation (fresh liquid operation) 203
3.14.2 Operation with liquid recirculation (combined operation) 206
3.14.3 Operation with closed circulation (circulating liquid operation) 208
3.15 Materials for liquid ring machines 210
3.16 Sealing of liquid ring vacuum pumps and compressors 214
Contents
3.17 Drives for liquid ring machines 216
3.17.1 Electric motor drive 216
3.17.2 Hermetic drive systems 218
3.17.3 Explosion protection on canned motor machines according to the
European Standard “EN” 224
3.17.4 Double walled security in hermetic drives (DWS) 226
3.17.5 Control and monitoring devices for machines
with double tube/double can 227
3.18 Compression of explosible gas-vapor mixtures with liquid ring
compressors 231
3.19 Safety standards for rotating machines 232
3.20 Characteristics and fields of applications of liquid ring
vacuum pumps and compressors 234
4 Vacuum and Compressor Plants with Liquid Ring Machines 239
4.1 Demands on pump systems in process engineering 239
4.2 Basic combinations of liquid ring vacuum pumps and
equipment in compact plants 241
4.3 Control of liquid ring pumps and pump systems 244
4.3.1 Electronic vacuum control for distillation in laboratories 246
4.3.2 Liquid ring vacuum pump system with automatic suction
pressure control 247
4.3.3 Control of coolant consumption for heat exchanger
and immission cooler 248
4.3.4 Optimal evacuation with liquid ring vacuum pumps 250
4.4 Pump unit designs and possibilities for the application
of liquid ring machines with design examples 253
4.4.1 Vacuum systems for condensate recovery 253
4.4.2 Pump systems with hermetic liquid ring vacuum pumps
and compressors 263
4.4.3 Vacuum pump unit of special design for the suction
of polluted process gases 272
4.4.4 Steam jet liquid ring vacuum system of
corrosion-resistant design 275
4.4.5 Selection of application examples for liquid ring machines 276
4.5 Electric heating and insulation on pumps and plants 279
4.6 Names and definitions – vacuum systems, components and
equipment 281
5 Components for Pump Units with Liquid Ring Vacuum Pumps
and Compressors 289
5.1 General criteria 289
5.2 Liquid separators 290
5.2.1 Vessel arrangements 292
5.3 Auxiliary appliances for vessels and pipework 293
Contents XVI
5.3.1 Inflow control unit 293
5.3.2 Outflow control unit 293
5.3.3 Injection segments 294
5.3.4 Purging equipment 294
5.3.5 Aeration and ventilating facilities 295
5.3.6 Sieves for liquids 296
5.4 Gas cleaning devices 297
5.4.1 Chamber separator 298
5.4.2 Impact plate separator 298
5.4.3 Centrifugal separator 299
5.4.4 Aero-cyclones 300
5.4.5 Filters 300
5.5 Heat transfer devices 301
5.5.1 Heat transition 302
5.5.2 Contamination of transfer surfaces 303
5.5.3 Designs of heat exchangers 304
5.6 Condensers 309
5.6.1 Surface condensers 310
5.6.2 Co-condensers 311
5.6.3 Condensate discharge 312
5.6.4 Exhaust gas condenser 314
5.7 Temperature controllers 315
5.8 Flowmeters 316
5.9 Shut-off instruments 316
5.10 Check valves and ball check valves 319
5.11 Safety valves 320
5.12 Vacuum ventilation valves 320
5.13 Flanges in vacuum technology 321
5.14 Fast flange connections, small flange connections in vacuum
technology 323
5.15 Surface condition of sealing surfaces 323
5.16 Sealing materials in vacuum technology 325
5.17 Vacuum greases 326
6 Design of Vacuum Pumps and Pipework 331
6.1 Leakages in vacuum systems 331
6.2 Evacuation time and suction capacity of the pump 332
6.2.1 Graphical determination of the evacuation time of vessels
in the rough vacuum range 333
6.3 Determination of suction capacity of vacuum pumps from the
leakage of the vessel 335
6.3.1 Leak rate values in practice 336
6.3.2 Determination of the leak rate by measuring on an existing plant 337
6.4 Determination of the pump suction capacity according to
the apparatus volume 338
Contents XVII
6.5 Vacuum loss of vessels with different designs 339
6.6 Arithmetic determination of volume flows, mass flows
and partial pressures 343
6.6.1 Calculation of gas-vapor mixtures 343
6.7 Flow velocities of liquids, vapors and gases 346
7 Assembly and Testing of Vacuum Pumps and Systems 351
7.1 Installation of machines and devices 351
7.2 Pipework 351
7.2.1 General notes regarding installation 351
7.2.2 Cleaning of the pipework 352
7.2.3 Characterization of the pipework according to the flow media 353
7.3 Leakage tests and pressure tests of devices and
pipework in the overpressure range 354
7.3.1 The leak test 354
7.3.2 The pressure test 355
7.4 Leak detection methods on components and plants
in the range of vacuum and overpressure 357
7.4.1 The leak detection 358
7.4.2 Leak detectors 358
7.4.3 Integral leak test 362
7.4.4 Leak localization on test units under vacuum or with test gas
overpressure 364
7.4.5 Leak test methods with helium leak detectors on vacuum plants 365
7.4.6 Test leak 367
7.5 Acceptance and performance tests on liquid ring machines 367
7.5.1 Acceptance rules 367
7.5.2 Similar experiment on liquid ring vacuum pumps 368
7.5.3 Acceptance test for liquid ring vacuum pumps 369
7.6 Electrical components and cables 372
7.7 Insulation 372
7.8 Putting into operation 373
7.9 Closing down 375
8 Materials, Surface Treatment and Safety-at-work in Vacuum Engineering 377
8.1 Criteria for the selection of materials 377
8.2 Surface treatment 378
8.2.1 Vacuum hygiene 378
8.2.2 Corrosion and corrosion protection 378
8.2.3 Treatment of metal surfaces for corrosion protection
by means of inorganic coats 380
8.2.4 Formulas for chemical or electrolytic pickling
and electrolytic polishing of metals 383
8.2.5 Paint coats 385
8.3 Health and safety protection at the workplace during
maintenance and operation of vacuum plants 387
8.3.1 Danger through implosion 387
8.3.2 Auxiliary materials for operation and maintenance
of vacuum pumps and plants 388
9 Explosion Protection and Explosion-proof Electrical Equipment 391
9.1 General 391
9.2 Danger of explosion and measures to prevent the ignition of
explosion-prone atmospheres 392
9.3 Zoning of explosion-prone areas 393
9.4 Classification of explosion-proof electrical equipment into
the main groups I and II 393
9.5 Ignition protection classes 396
9.6 Temperature classes 397
9.7 Standardized symbols for electrical equipment in explosion-prone
areas acc. to EN 50014 to EN 50020 401
9.8 Examples of explosion protection symbols 402
9.9 Comparison of symbols for explosion protection and firedamp
protection according to the old and new standard 404
9.10 Protection classes acc. to DIN IEC 34, part 5/VDE 0530, part 5 406
9.11 Motor power rating 407
9.12 Three-phase A.C. motors in VIK-design 408
9.13 “ATEX 100a” according to EU-Directive 94/9/EG
Application for liquid ring vacuum pumps 409
9.14 Regulations outside of CENELEC member states 411
9.15 Electric motors for explosion-prone areas acc. to the
American NEC-Rules 412
9.15.1 Classes and hazardous locations 412
9.15.2 Group classification 414
9.15.3 Temperatures for Class I and Class II in “hazardous locations” 414
9.15.4 Application of motors according to American regulations 416
9.15.5 Identification of motors 417
9.15.6 Protection classes acc. to NEMA in comparison to IEC 417
9.16 Internationally common power supply systems 418
10 Appendix 423
10.1 International system of units (SI) 423
10.1.1 SI basic units 423
10.1.2 Derived SI units 423
10.1.3 Additional SI units 425
10.1.4 Decimal multiples and parts of SI units 426
10.1.5 Units outside the International System of Units 426
10.2 Units of measurement and their conversion 428
10.3 Summary of physical and technical units 434
10.4 National and international standards, recommendations
and regulations 441
10.5 Graphical symbols used in the vacuum
and process technology 451
10.6 Graphical symbols and call letters for measuring control
and regulation (MCR) in process engineering 456
10.7 Physical call values of liquids and gases 464
10.8 Tables and diagrams 470

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