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P R E FA C E
This sixth edition of the text on the unit operations of chemical engineering has been extensively revised and updated, with much new material and considerable condensation of some sections. Its basic structure and general level of treatment, however, remain unchanged. It is an introductory text, written for undergraduate students in their junior or senior years who have completed the usual courses in mathematics, physics, chemistry, and an introduction to chemical engineering. An elementary knowledge of material and energy balances and of thermodynamic principles is assumed. Separate chapters are devoted to each of the principal unit operations, grouped into four sections: fluid mechanics, heat transfer, mass transfer and equilibrium stages, and operations involving particulate solids. One-semester or one-quarter courses may be based on any of these sections or combinations of them. The order of the first 16 chapters has not been changed; later ones, dealing with mass transfer and operations involving solids, have been rearranged in a more logical order. Nearly all equations have been written for SI units, and the Newton’s law conversion factor gc has been eliminated except in the few instances where it must be included. Symbols for dimensionless groups have been changed to Re for NRe, for example, Pr for NPr, and so forth. Many new examples and problems have been added, some reflecting the importance of biochemical engineering processes. Material on handling, mixing, and grinding particulate solids has been greatly condensed and dealt with in a single chapter. The number of appendixes is reduced from 22 to 19. Derivations of the differential equations for continuity and momentum balances, leading to the Navier-Stokes equation, have been added, as well as the differential forms of Fourier’s law and Fick’s law, emphasizing the analogies among momentum, heat, and mass transfer. The chapter on adsorption has been expanded to include new material on chromatography and ion exchange, and renamed “Fixedbed Separations.” Other new material has been added on viscoelastic fluids, laminar flow in annuli, drag coefficients, affinity laws for pumps, high-efficiency agitators and motionless mixers, plate-type heat exchangers, boiling by submerged tube bundles, cooling towers, aqueous phase extraction, cross-flow filtration, and many other topics. Many of the problems at the ends of the chapters are new or revised. Most are expressed in SI units. Nearly all the problems can be solved with the aid of a pocket calculator; for a few, a computer solution is preferable. McGraw-Hill and the authors thank Dr. N. T. Obot for his many suggestions regarding fluid mechanics and heat transfer, and Professor Charles H. Gooding of Clemson University for his detailed and helpful review of the manuscript. Julian C. Smith Peter Harriott xvii
iii
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CONTENTS
Preface
SECTION I
1
xvii
Introduction Definitions and Principles
3
Unit Operations Unit Systems
4 4
Physical Quantities / SI Units / CGS Units / Gas Constant / FPS Engineering Units / Conversion of Units / Units and Equations
Dimensional Analysis Basic Concepts
16 20
Equations of State of Gases
Symbols Problems References
SECTION II
2
3
24 25 27
Fluid Mechanics Fluid Statics and Its Applications
31
Hydrostatic Equilibrium
32
Applications of Fluid Statics Symbols Problems References
34
Fluid Flow Phenomena
44
Laminar Flow, Shear Rate, and Shear Stress Rheological Properties of Fluids Turbulence Boundary Layers Symbols Problems References
45
41 42 43
46 51 59 63 64 65 vii
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4
5
6
7
8
Basic Equations of Fluid Flow
67
Mass Balance in a Flowing Fluid; Continuity Differential Momentum Balance; Equations of Motion Macroscopic Momentum Balances Mechanical Energy Equation Symbols Problems References
67
Incompressible Flow in Pipes and Channels
94
Shear Stress and Skin Friction in Pipes Laminar Flow in Pipes and Channels Turbulent Flow in Pipes and Channels Friction from Changes in Velocity or Direction Symbols Problems References
94
72 77 82 90 92 93
97 104 117 123 124 127
Flow of Compressible Fluids
128
Definitions and Basic Equations Processes of Compressible Flow Isentropic Flow through Nozzles Adiabatic Friction Flow Isothermal Friction Flow Symbols Problems References
128
Flow Past Immersed Bodies
150
Drag and Drag Coefficients Flow through Beds of Solids Motion of Particles through Fluids Fluidization Symbols Problems References
150
Transportation and Metering of Fluids
187
Pipe, Fittings, and Valves Pumps
187
133 134 140 145 147 148 149
157 162 171 182 183 185
194
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ix
Positive-Displacement Pumps / Centrifugal Pumps
Fans, Blowers, and Compressors
209
Fans / Blowers and Compressors / Comparison of Devices for Moving Fluids
Measurement of Flowing Fluids
219
Full-Bore Meters / Insertion Meters
9
SECTION III
10
11
Symbols Problems References
234
Agitation and Mixing of Liquids
238
Agitated Vessels Blending and Mixing Suspension of Solid Particles Dispersion Operations Agitator Selection and Scaleup Symbols Problems References
239
236 237
259 265 270 278 281 282 284
Heat Transfer and Its Applications Heat Transfer by Conduction
291
Basic Law of Conduction Steady-State Conduction Unsteady-State Conduction Symbols
291
Problems References
312
Principles of Heat Flow in Fluids
315
Typical Heat-Exchange Equipment Energy Balances Heat Flux and Heat-Transfer Coefficients
315
293 300 311 314
319 321
Overall Heat-Transfer Coefficient / Individual Heat-Transfer Coefficients
Symbols Problems References
333 334 335
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12
Heat Transfer to Fluids Without Phase Change
336
Boundary Layers Heat Transfer by Forced Convection in Laminar Flow Heat Transfer by Forced Convection in Turbulent Flow
336 339 346
Transfer by Turbulent Eddies and Analogy Between Transfer of Momentum and Heat
Heat Transfer in Transition Region Between Laminar and Turbulent Flow Heat Transfer to Liquid Metals Heating and Cooling of Fluids in Forced Convection Outside Tubes Natural Convection Symbols Problems References
13
14
15
358 360 362 365 371 373 375
Heat Transfer to Fluids with Phase Change
377
Heat Transfer from Condensing Vapors Heat Transfer to Boiling Liquids Symbols Problems References
377
Radiation Heat Transfer
406
Emission of Radiation Absorption of Radiation by Opaque Solids Radiation Between Surfaces
407
Radiation to Semitransparent Materials Combined Heat Transfer by Conduction-Convection and Radiation Symbols Problems References
423
Heat-Exchange Equipment
431
Shell-and-Tube Heat Exchangers Plate-Type Exchangers Extended-Surface Equipment Scraped-Surface Exchangers
432
389 401 403 404
410 413
425 427 428 430
446 449 455
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16
xi
Condensers and Vaporizers Heat Transfer in Agitated Vessels Heat Transfer in Packed Beds Symbols Problems References
456
Evaporation
473
Types of Evaporators
475
Performance of Tubular Evaporators
479
459 463 467 469 471
Evaporator Capacity / Evaporator Economy
Vapor Recompression Symbols Problems References SECTION IV
17
498 500 500 502
Mass Transfer and Its Applications Principles of Diffusion and Mass Transfer Between Phases Theory of Diffusion Prediction of Diffusivities Mass-Transfer Theories
511 512 518 523
Film Theory / Boundary Layer Theory / Penetration Theory / Two-Film Theory
Mass-Transfer Coefficients
530
Experimental Measurements / Coefficients for Mass Transfer through Known Areas
18
Symbols Problems References
540
Gas Absorption
546
Packings and Packed Tower Design Principles of Absorption Absorption from Rich Gases Mass-Transfer Correlations
546
542 544
557 574 580
Absorption in Plate Columns
Absorption with Chemical Reaction
588
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19
Symbols Problems References
590
Humidification Operations
596
Definitions Humidity Chart Wet-Bulb Temperature Cooling Towers
596
592 594
600 604 608
Theory of Counterflow Cooling Towers
20
Symbols Problems References
618
Equilibrium-Stage Operations
622
Equipment for Stage Contacts Principles of Stage Processes
622
619 621
625
Equilibrium-Stage Calculations for Multicomponent Systems
21
Symbols Problems References
639
Distillation
641
Flash Distillation Continuous Distillation with Reflux
641
639 640
645
Material Balances in Plate Columns / Number of Ideal Plates; McCabe–Thiele Method
Enthalpy Balances Design of Sieve-Plate Columns Plate Efficiencies
672 681 689
Theory of Plate Efficiency
22
Distillation in Packed Columns Batch Distillation Symbols Problems References
699
Introduction to Multicomponent Distillation
713
Phase Equilibria in Multicomponent Distillation Flash Distillation of Multicomponent Mixtures
713
700 704 706 711
717
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23
xiii
Fractionation of Multicomponent Mixtures Azeotropic and Extractive Distillation Symbols Problems References
718
Leaching and Extraction
739
Leaching
739
734 735 736 738
Leaching Equipment / Principles of Continuous Countercurrent Leaching
Liquid Extraction
747
Extraction Equipment / Principles of Extraction
Special Extraction Techniques
766
Supercritical Fluid Extraction
24
Symbols Problems References
768
Drying of Solids
773
Principles of Drying
775
769 772
Phase Equilibria
Cross-Circulation Drying Through-Circulation Drying
782 790
Drying of Suspended Particles
Freeze-Drying Drying Equipment
793 794
Dryers for Solids and Pastes / Dryers for Solutions and Slurries / Selection of Drying Equipment
25
Symbols Problems References
807
Fixed-Bed Separations
812
Adsorption Adsorption Equipment
812
809 810
813
Equilibria; Adsorption Isotherms / Principles of Adsorption / Basic Equations for Adsorption / Solutions to Mass-Transfer Equations / Adsorber Design / Continuous Operation
Ion Exchange Equilibria / Mass-Transfer Rates / Operation of Ion Exchangers
839
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26
Chromatography Symbols Problems References
845
Membrane Separation Processes
857
Separation of Gases Separation of Liquids
857
852 854 855
878
Dialysis / Membranes for Liquid-Liquid Extraction / Pervaporation / Reverse Osmosis
27
Symbols Problems References
896
Crystallization
902
Crystal Geometry Equilibria and Yields Nucleation Crystal Growth Crystallization Equipment Crystallizer Design: Crystal Size Distribution
903
898 900
904 911 918 921 927
MSMPR Crystallizer
Crystallization from Melts Symbols Problems References
SECTION V
28
936 937 939 941
Operations Involving Particulate Solids Properties and Handling of Particulate Solids
945
Characterization of Solid Particles Properties of Masses of Particles
945 951
Storage and Conveying of Solids
Mixing of Solids
955
Mixers for Noncohesive Solids / Mixers for Cohesive Solids
Size Reduction Computer Simulation of Milling Operations / Equipment for Size Reduction
965
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29
xv
Ultrafine Grinders Symbols Problems References
977
Mechanical Separations
986
Screening
986
981 983 984
Screening Equipment
Filtration; General Considerations
991
Cake Filters
993
Centrifugal Filters / Filter Media / Filter Aids / Principles of Cake Filtration
Clarifying Filters
1018
Liquid Clarification / Gas Cleaning / Principles of Clarification
Crossflow Filtration; Membrane Filters
1021
Type of Membranes / Permeate Flux for Ultrafiltration / Concentration Polarization / Microfiltration
Gravity Sedimentation Processes Centrifugal Sedimentation Processes Symbols Problems References Appendix 1 Conversion Factors and Constants of Nature Appendix 2 Dimensionless Groups Appendix 3 Dimensions, Capacities, and Weights of Standard Steel Pipe Appendix 4 Condenser and Heat-Exchanger Tube Data
1035
Appendix 5 Appendix 6 Appendix 7 Appendix 8 Appendix 9 Appendix 10 Appendix 11
1070
Tyler Standard Screen Scale Properties of Liquid Water Properties of Saturated Steam and Water Viscosities of Gases Viscosities of Liquids Thermal Conductivities of Metals Thermal Conductivities of Various Solids and Insulating Materials Appendix 12 Thermal Conductivities of Gases and Vapors Appendix 13 Thermal Conductivities of Liquids Other Than Water Appendix 14 Specific Heats of Gases
1045 1056 1058 1061 1063 1066 1068 1069 1071 1072 1074 1076 1079 1080 1082 1083 1084
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CONTENTS
Appendix 15 Appendix 16 Appendix 17 Appendix 18
Specific Heats of Liquids Prandtl Numbers for Gases at 1 atm and 100°C Prandtl Numbers for Liquids Diffusivities and Schmidt Numbers for Gases in Air at 0°C and 1 atm Appendix 19 Collision Integral and Lennard-Jones Force Constants
1085
Index
1091
1086 1087 1088 1089
1
2
3
4
5
6
7
8
9
10
11
12
13
14
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17
18
19
20
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25
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28
29
30
31
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37
58
59
61
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58
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260
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241
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315
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321
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361
362
363
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371
372
379
380
381
382
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385
386
387
388
