Energy costs impact the profitability of virtually all industrial processes. Stressing how plants use power, and how that power is actually generated, this book provides a clear and simple way to understand the energy usage in various processes, as well as methods for optimizing these processes using practical hands-on simulations and a unique approach that details solved problems utilizing actual plant data. Invaluable information offers a complete energy-saving approach essential for both the chemical and mechanical engineering curricula, as well as for practicing engineers.
Table of Contents:
Preface xiii Conversion Factors xvii
List of Symbols xix
1. Introduction to Energy Usage, Cost, and Efficiency 1
1.1 Energy Utilization in the United States 1
1.2 The Cost of Energy 1
1.3 Energy Efficiency 4
1.4 The Cost of Self-Generated versus Purchased Electricity 10
1.5 The Cost of Fuel and Fuel Heating Value 11
1.6 Text Organization 12
1.7 Getting Started 15
1.8 Closing Comments 16
References 16
Problems 17
2. Engineering Economics with VBA Procedures 19
2.1 Introduction to Engineering Economics 19
2.2 The Time Value of Money: Present Value (PV) and Future Value (FV) 19
2.3 Annuities 22
2.4 Comparing Process Alternatives 29
2.4.1 Present Value 31
2.4.2 Rate of Return (ROR) 31
2.4.3 Equivalent Annual Cost/Annual Capital Recovery Factor (CRF) 32
2.5 Plant Design Economics 33
2.6 Formulating Economics-Based Energy Optimization Problems 34
2.7 Economic Analysis with Uncertainty: Monte Carlo Simulation 36
2.8 Closing Comments 38
References 39
Problems 39
3. Computer-Aided Solutions of Process Material Balances: The Sequential Modular Solution Approach 42
3.1 Elementary Material Balance Modules 42
3.1.1 Mixer 43
3.1.2 Separator 43
3.1.3 Splitter 44
3.1.4 Reactors 45
3.2 Sequential Modular Approach: Material Balances with Recycle 46
3.3 Understanding Tear Stream Iteration Methods 49
3.3.1 Single-Variable Successive Substitution Method 49
3.3.2 Multidimensional Successive Substitution Method 50
3.3.3 Single-Variable Wegstein Method 52
3.3.4 Multidimensional Wegstein Method 53
3.4 Material Balance Problems with Alternative Specifications 58
3.5 Single-Variable Optimization Problems 61
3.5.1 Forming the Objective Function for Single-Variable Constrained Material Balance Problems 61
3.5.2 Bounding Step or Bounding Phase: Swann’s Equation 61
3.5.3 Interval Refinement Phase: Interval Halving 65
3.6 Material Balance Problems with Local Nonlinear Specifications 66
3.7 Closing Comments 68
References 69
Problems 70
4. Computer-Aided Solutions of Process Material Balances: The Simultaneous Solution Approach 76
4.1 Solution of Linear Equation Sets: The Simultaneous Approach 76
4.1.1 The Gauss–Jordan Matrix Elimination Method 76
4.1.2 Gauss–Jordan Coding Strategy for Linear Equation Sets 78
4.1.3 Linear Material Balance Problems: Natural Specifi cations 78
4.1.4 Linear Material Balance Problems: Alternative Specifications 82
4.2 Solution of Nonlinear Equation Sets: The Newton–Raphson Method 82
4.2.1 Equation Linearization via Taylor’s Series Expansion 82
4.2.2 Nonlinear Equation Set Solution via the Newton–Raphson Method 83
4.2.3 Newton–Raphson Coding Strategy for Nonlinear Equation Sets 86
4.2.4 Nonlinear Material Balance Problems: The Simultaneous Approach 90
References 92
Problems 93
5. Process Energy Balances 98
5.1 Introduction 98
5.2 Separator: Equilibrium Flash 101
5.2.1 Equilibrium Flash with Recycle: Sequential Modular Approach 103
5.3 Equilibrium Flash with Recycle: Simultaneous Approach 109
5.4 Adiabatic Plug Flow Reactor (PFR) Material and Energy Balances Including Rate Expressions: Euler’s First-Order Method 112
5.4.1 Reactor Types 112
5.5 Styrene Process: Material and Energy Balances with Reaction Rate 117
5.6 Euler’s Method versus Fourth-Order Runge–Kutta Method for Numerical Integration 121
5.6.1 The Euler Method: First-Order ODEs 121
5.6.2 RK4 Method: First-Order ODEs 122
5.7 Closing Comments 124
References 125
Problems 125
6. Introduction to Data Reconciliation and Gross Error Detection 132
6.1 Standard Deviation and Probability Density Functions 133
6.2 Data Reconciliation: Excel Solver 136
6.2.1 Single-Unit Material Balance: Excel Solver 136
6.2.2 Multiple-Unit Material Balance: Excel Solver 138
6.3 Data Reconciliation: Redundancy and Variable Types 138
6.4 Data Reconciliation: Linear and Nonlinear Material and Energy Balances 143
6.5 Data Reconciliation: Lagrange Multipliers 149
6.5.1 Data Reconciliation: Lagrange Multiplier Compact Matrix Notation 152
6.6 Gross Error Detection and Identification 154
6.6.1 Gross Error Detection: The Global Test (GT) Method 154
6.6.2 Gross Error (Suspect Measurement) Identification: The Measurement Test (MT) Method: Linear Constraints 155
6.6.3 Gross Error (Suspect Measurement) Identification: The Measurement Test Method: Nonlinear Constraints 156
6.7 Closing Remarks 158
References 158
Problems 158
7. Gas Turbine Cogeneration System Performance, Design, and Off-Design Calculations: Ideal Gas Fluid Properties 164
7.1 Equilibrium State of a Simple Compressible Fluid: Development of the T ds Equations 165
7.1.1 Application of the T ds Equations to an Ideal Gas 166
7.1.2 Application of the T ds Equations to an Ideal Gas: Isentropic Process 166
7.2 General Energy Balance Equation for an Open System 167
7.3 Cogeneration Turbine System Performance Calculations: Ideal Gas Working Fluid 167
7.3.1 Compressor Performance Calculations 167
7.3.2 Turbine Performance Calculations 168
7.4 Air Basic Gas Turbine Performance Calculations 169
7.5 Energy Balance for the Combustion Chamber 172
7.5.1 Energy Balance for the Combustion Chamber: Ideal Gas Working Fluid 172
7.6 The HRSG: Design Performance Calculations 173
7.6.1 HRSG Design Calculations: Exhaust Gas Ideal and Water-Side Real Properties 176
7.7 Gas Turbine Cogeneration System Performance with Design HRSG 177
7.7.1 HRSG Material and Energy Balance Calculations Using Excel Callable Sheet Functions 179
7.8 HRSG Off-Design Calculations: Supplemental Firing 180
7.8.1 HRSG Off-Design Performance: Overall Energy Balance Approach 180
7.8.2 HRSG Off-Design Performance: Overall Heat Transfer Coefficient Approach 181
7.9 Gas Turbine Design and Off-Design Performance 185
7.9.1 Gas Turbines Types and Gas Turbine Design Conditions 185
7.9.2 Gas Turbine Design and Off-Design Using Performance Curves 186
7.9.3 Gas Turbine Internal Mass Flow Patterns 186
7.9.4 Industrial Gas Turbine Off-Design (Part Load) Control Algorithm 188
7.9.5 Aeroderivative Gas Turbine Off-Design (Part Load) Control Algorithm 189
7.9.6 Off-Design Performance Algorithm for Gas Turbines 189
7.10 Closing Remarks 193
References 194
Problems 194
8. Development of a Physical Properties Program for Cogeneration Calculations 198
8.1 Available Function Calls for Cogeneration Calculations 198
8.2 Pure Species Thermodynamic Properties 202
8.3 Derivation of Working Equations for Pure Species Thermodynamic Properties 207
8.4 Ideal Mixture Thermodynamic Properties: General Development and Combustion Reaction Considerations 209
8.4.1 Ideal Mixture 209
8.4.2 Changes in Enthalpy and Entropy 209
8.5 Ideal Mixture Thermodynamic Properties: Apparent Difficulties 211
8.6 Mixing Rules for EOS 213
8.7 Closing Remarks 215
References 216
Problems 216
9. Gas Turbine Cogeneration System Performance, Design, and Off-Design Calculations: Real Fluid Properties 222
9.1 Cogeneration Gas Turbine System Performance Calculations: Real Physical Properties 223
9.1.1 Air Compressor (AC) Performance Calculation 224
9.1.2 Energy Balance for the Combustion Chamber (CC) 224
9.1.3 C Functions for Combustion Temperature and Exhaust Gas Physical Properties 224
9.1.4 Gas and Power Turbine (G&PT) Performance Calculations 229
9.1.5 Air Preheater (APH) 230
9.2 HRSG: Design Performance Calculations 230
9.3 HRSG Off-Design Calculations: Supplemental Firing 232
9.3.1 HRSG Off-Design Performance: Overall Energy Balance Approach 233
9.3.2 HRSG Off-Design Performance: Overall Heat Transfer Coefficient Approach 234
9.4 Gas Turbine Design and Off-Design Performance 235
9.5 Closing Remarks 237
References 238
Problems 238
10. Gas Turbine Cogeneration System Economic Design Optimization and Heat Recovery Steam Generator Numerical Analysis 243
10.1 Cogeneration System: Economy of Scale 244
10.2 Cogeneration System Confi guration: Site Power-to-Heat Ratio 244
10.3 Economic Optimization of a Cogeneration System: The CGAM Problem 245
10.3.1 The Objective Function: Cogeneration System Capital and Operating Costs 246
10.3.2 Optimization: Variable Selection and Solution Strategy 248
10.3.3 Process Constraints 249
10.4 Economic Design Optimization of the CGAM Problem: Ideal Gas 249
10.4.1 Air Preheater (APH) Equations 249
10.4.2 CGAM Problem Physical Properties 249
10.5 The CGAM Cogeneration Design Problem: Real Physical Properties 250
10.6 Comparing CogenD and General Electric’s GateCycle™ 253
10.7 Numerical Solution of HRSG Heat Transfer Problems 254
10.7.1 Steady-State Heat Conduction in a One-Dimensional Wall 254
10.7.2 Unsteady-State Heat Conduction in a One-Dimensional Wall 255
10.7.3 Steady-State Heat Conduction in the HRSG 259
10.8 Closing Remarks 266
References 267
Problems 267
11. Data Reconciliation and Gross Error Detection in a Cogeneration System 272
11.1 Cogeneration System Data Reconciliation 272
11.2 Cogeneration System Gross Error Detection and Identification 278
11.3 Visual Display of Results 281
11.4 Closing Comments 281
References 282
Problems 283
12. Optimal Power Dispatch in a Cogeneration Facility 284
12.1 Developing the Optimal Dispatch Model 284
12.2 Overview of the Cogeneration System 286
12.3 General Operating Strategy Considerations 287
12.4 Equipment Energy Efficiency 287
12.4.1 Stand-Alone Boiler (Boiler 4) Performance (Based on Fuel Higher Heating Value (HHV)) 288
12.4.2 Electric Chiller Performance 289
12.4.3 Steam-Driven Chiller Performance 290
12.4.4 GE Air Cooler Chiller Performance 291
12.4.5 GE Gas Turbine Performance (Based on Fuel HHV) 294
12.4.6 GE Gas Turbine HRSG Boiler 8 Performance (Based on Fuel HHV) 295
12.4.7 GE Gas Turbine HRSG Boiler 8 Performance Supplemental Firing (Based on Fuel HHV) 296
12.4.8 Allison Gas Turbine Performance (Based on Fuel HHV) 296
12.4.9 Allison Gas Turbine HRSG Boiler 7 Performance (Based on Fuel HHV) 297
12.4.10 Allison Gas Turbine HRSG Boiler 7 Performance Supplemental Firing (Based on Fuel HHV) 297
12.5 Predicting the Cost of Natural Gas and Purchased Electricity 298
12.5.1 Natural Gas Cost 299
12.5.2 Purchased Electricity Cost 299
12.6 Development of a Multiperiod Dispatch Model for the Cogeneration Facility 302
12.7 Closing Comments 309
References 310
Problems 310
13. Process Energy Integration 314
13.1 Introduction to Process Energy Integration/Minimum Utilities 314
13.2 Temperature Interval/Problem Table Analysis with 0° Approach Temperature 316
13.3 The Grand Composite Curve (GCC) 317
13.4 Temperature Interval/Problem Table Analysis with “Real” Approach Temperature 318
13.5 Determining Hot and Cold Stream from the Process Flow Sheet 319
13.6 Heat Exchanger Network Design with Maximum Energy Recovery (MER) 324
13.6.1 Design above the Pinch 325
13.6.2 Design below the Pinch 327
13.7 Heat Exchanger Network Design with Stream Splitting 328
13.8 Heat Exchanger Network Design with Minimum Number of Units (MNU) 329
13.9 Software for Teaching the Basics of Heat Exchanger Network Design (Teaching Heat Exchanger Networks (THEN)) 331
13.10 Heat Exchanger Network Design: Distillation Columns 331
13.11 Closing Remarks 336
References 336
Problems 337
14. Process and Site Utility Integration 343
14.1 Gas Turbine-Based Cogeneration Utility System for a Processing Plant 343
14.2 Steam Turbine-Based Utility System for a Processing Plant 353
14.3 Site-Wide Utility System Considerations 356
14.4 Closing Remarks 362
References 363
Problems 363
15. Site Utility Emissions 368
15.1 Emissions from Stoichiometric Considerations 369
15.2 Emissions from Combustion Equilibrium Calculations 370
15.2.1 Equilibrium Reactions 371
15.2.2 Combustion Chamber Material Balances 371
15.2.3 Equilibrium Relations for Gas-Phase Reactions/Gas-Phase Combustors 372
15.2.4 Equilibrium Compositions from Equilibrium Constants 376
15.3 Emission Prediction Using Elementary Kinetics Rate Expressions 380
15.3.1 Combustion Chemical Kinetics 380
15.3.2 Compact Matrix Notation for the Species Net Generation (or Production) Rate 381
15.4 Models for Predicting Emissions from Gas Turbine Combustors 382
15.4.1 Perfectly Stirred Reactor for Combustion Processes: The Material Balance Problem 382
15.4.2 The Energy Balance for an Open System with Reaction (Combustion) 385
15.4.3 Perfectly Stirred Reactor Energy Balance 385
15.4.4 Solution of the Perfectly Stirred Reactor Material and Energy Balance Problem Using the Provided CVODE Code 386
15.4.5 Plug Flow Reactor for Combustion Processes: The Material Balance Problem 388
15.4.6 Plug Flow Reactor for Combustion Processes: The Energy Balance Problem 389
15.5 Closing Remarks 393
References 393
CVODE Tutorial 393
Problems 394
16. Coal-Fired Conventional Utility Plants with CO2 Capture (Design and Off-Design Steam Turbine Performance) 397
16.1 Power Plant Design Performance (Using Operational Data for Full-Load Operation) 398
16.1.1 Turbine System: Design Case (See Example 16.1.xls) 401
16.1.2 Extraction Flow Rates and Feedwater Heaters 402
16.1.3 Auxiliary Turbine/High-Pressure Feedwater Pump 402
16.1.4 Low-Pressure Feedwater Pump 403
16.1.5 Turbine Exhaust End Loss 403
16.1.6 Steam Turbine System Heat Rate and Performance Parameters 405
16.2 Power Plant Off-Design Performance (Part Load with Throttling Control Operation) 406
16.2.1 Initial Estimates for All Pressures and Effi ciencies: Sub Off_Design_Initial_Estimates ( ) 406
16.2.2 Modify Pressures: Sub Pressure_Iteration ( ) 406
16.2.3 Modify Effi ciencies: Sub Update Effi ciencies ( ) 408
16.3 Levelized Economics for Utility Pricing 409
16.4 CO2 Capture and Its Impact on a Conventional Utility Power Plant 413
16.5 Closing Comments 414
References 417
Problems 417
17. Alternative Energy Systems 419
17.1 Levelized Costs for Alternative Energy Systems 419
17.2 Organic Rankine Cycle (ORC): Determination of Levelized Cost 420
17.3 Nuclear Power Cycle 425
17.3.1 A High-Temperature Gas-Cooled Nuclear Reactor (HTGR) 425
References 427
Problems 427
Appendix. Bridging Excel and C Codes 429
A.1 Introduction 429
A.2 Working with Functions 431
A.3 Working with Vectors 434
A.4 Working with Matrices 442
A.4.1 Gauss–Jordan Matrix Elimination Method 442
A.4.2 Coding the Gauss–Jordan Matrix Elimination Method 443
A.5 Closing Comments 446
References 448
Tutorial 448
Microsoft C++ 2008 Express: Creating C Programs and DLLs 448
Index 458
About the Author :
F. Carl Knopf is the Robert D. and Adele Anding Professor of Chemical Engineering and Associate Director of the Center for Energy Studies' Minerals Processing Research Institute at Louisiana State University.
