Page 10 - Separation process principles 2

xiv Contents

PART 2 SEPARATIONS BY PHASE ADDITION OR CREATION 191

Chapter 6 Absorption and Stripping of Dilute Mixtures 193

6.0 Instructional Objectives 193
Industrial Example 194
6.1 Equipment 196
6.2 General Design Considerations 200
6.3 Graphical Equilibrium-Stage Method for Trayed Towers 201
Minimum Absorbent Flow Rate 202
Number of Equilibrium Stages 203
6.4 Algebraic Method for Determining the Number of Equilibrium Stages 205
6.5 Stage Efficiency 207
Performance Data 208
Empirical Correlations 208
Semitheoretical Models 2 12
Scale-up from Laboratory Data 214
6.6 Tray Diameter, Pressure Drop, and Mass Transfer 215
Tray Diameter 2 15
High-Capacity Trays 2 18
Tray Vapor Pressure Drop 2 19
Mass-Transfer Coefficients and Transfer Units 220
Weeping, Entrainment, and Downcomer Backup 222
6.7 Rate-Based Method for Packed Columns 223
6.8 Packed-Column Efficiency, Capacity, and Pressure Drop 228
Liquid Holdup 228
Column Diameter and Pressure Drop 233
Mass-Transfer Efficiency 237
6.9 Concentrated Solutions in Packed Columns 242
Summary 244 References 244 Exercises 246

Chapter 7 Distillation of Binary Mixtures 252
7.0 Instructional Objectives 252
Industrial Example 253
7.1 Equipment and Design Considerations 255
7.2 McCabe-Thiele Graphical Equilibrium-Stage Method for Trayed Towers 255
Rectifying Section 257
Stripping Section 259
Feed-Stage Considerations 259
Determination of Number of Equilibrium Stages and Feed-Stage Location 261
Limiting Conditions 261
Column Operating Pressure and Condenser Type 265
Subcooled Reflux 266
Reboiler Type 268
Condenser and Reboiler Duties 269
Feed Preheat 270