Table of Contents

PART 1 BASIC CONCEPTS AND THEORY 1

1 Overview of this Book 3

1.1 Introduction, 3

1.2 Who is this Book Written for?, 4

1.3 Five Ways to Improve Energy Efficiency, 5

1.4 Four Key Elements for Continuous Improvement, 7

1.5 Promoting Improvement Ideas in the Organization, 8

2 Theory of Energy Intensity 9

2.1 Introduction, 9

2.2 Definition of Process Energy Intensity, 10

2.3 The Concept of Fuel Equivalent (FE), 11

2.4 Energy Intensity for a Total Site, 13

2.5 Concluding Remarks, 15

3 Benchmarking Energy Intensity 16

3.1 Introduction, 16

3.2 Data Extraction from Historian, 17

3.3 Convert All Energy Usage to Fuel Equivalent, 17

3.4 Energy Balance, 21

3.5 Fuel Equivalent for Steam and Power, 23

3.6 Energy Performance Index (EPI) Method, 29

3.7 Concluding Remarks, 32

4 Key Indicators and Targets 35

4.1 Introduction, 35

4.2 Key Indicators Represent Operation Opportunities, 36

4.3 Define Key Indicators, 39

4.4 Set up Targets for Key Indicators, 45

4.5 Economic Evaluation for Key Indicators, 49

4.6 Application 1: Implementing Key Indicators into an "Energy Dashboard," 53

4.7 Application 2: Implementing Key Indicators to Controllers, 56

4.8 It is Worth the Effort, 57

PART 2 ENERGY SYSTEM ASSESSMENT METHODS 59

5 Fired Heater Assessment 61

5.1 Introduction, 61

5.2 Fired Heater Design for High Reliability, 62

5.3 Fired Heater Operation for High Reliability, 68

5.4 Efficient Fired Heater Operation, 73

5.5 Fired Heater Revamp, 80

6 Heat Exchanger Performance Assessment 82

6.1 Introduction, 82

6.2 Basic Concepts and Calculations, 83

6.3 Understand Performance Criterion—U Values, 89

6.4 Understanding Pressure Drop, 94

6.5 Heat Exchanger Rating Assessment, 96

6.6 Improving Heat Exchanger Performance, 106

7 Heat Exchanger Fouling Assessment 112

7.1 Introduction, 112

7.2 Fouling Mechanisms, 113

7.3 Fouling Mitigation, 114

7.4 Fouling Mitigation for Crude Preheat Train, 117

7.5 Fouling Resistance Calculations, 119

7.6 A Cost-Based Model for Clean Cycle Optimization, 121

7.7 Revised Model for Clean Cycle Optimization, 125

7.8 A Practical Method for Clean Cycle Optimization, 128

7.9 Putting All Together—A Practical Example of Fouling Mitigation, 130

8 Energy Loss Assessment 138

8.1 Introduction, 138

8.2 Energy Loss Audit, 139

8.3 Energy Loss Audit Results, 147

8.4 Energy Loss Evaluation, 149

8.5 Brainstorming, 150

8.6 Energy Audit Report, 152

9 Process Heat Recovery Targeting Assessment 154

9.1 Introduction, 154

9.2 Data Extraction, 155

9.3 Composite Curves, 156

9.4 Basic Concepts, 159

9.5 Energy Targeting, 160

9.6 Pinch Golden Rules, 160

9.7 Cost Targeting: Determine Optimal DTmin, 162

9.8 Case Study, 165

9.9 Avoid Suboptimal Solutions, 169

9.10 Integrated Cost Targeting and Process Design, 171

9.11 Challenges for Applying the Systematic Design Approach, 172

10 Process Heat Recovery Modification Assessment 175

10.1 Introduction, 175

10.2 Network Pinch—The Bottleneck of Existing Heat Recovery System, 176

10.3 Identification of Modifications, 179

10.4 Automated Network Pinch Retrofit Approach, 181

10.5 Case Studies for Applying the Network Pinch Retrofit Approach, 183

11 Process Integration Opportunity Assessment 195

11.1 Introduction, 195

11.2 Definition of Process Integration, 196

11.3 Plus and Minus (+/-) Principle, 198

11.4 Grand Composite Curves, 199

11.5 Appropriate Placement Principle for Process Changes, 200

11.6 Examples of Process Changes, 205

PART 3 PROCESS SYSTEM ASSESSMENT AND OPTIMIZATION 225

12 Distillation Operating Window 227

12.1 Introduction, 227

12.2 What is Distillation?, 228

12.3 Distillation Efficiency, 229

12.4 Definition of Feasible Operating Window, 232

12.5 Understanding Operating Window, 232

12.6 Typical Capacity Limits, 253

12.7 Effects of Design Parameters, 255

12.8 Design Checklist, 257

12.9 Example Calculations for Developing Operating Window, 257

12.10 Concluding Remarks, 276

13 Distillation System Assessment 281

13.1 Introduction, 281

13.2 Define a Base Case, 281

13.3 Calculations for Missing and Incomplete Data, 284

13.4 Building Process Simulation, 287

13.5 Heat and Material Balance Assessment, 288

13.6 Tower Efficiency Assessment, 292

13.7 Operating Profile Assessment, 295

13.8 Tower Rating Assessment, 298

13.9 Column Heat Integration Assessment, 300

13.10 Guidelines for Reuse of an Existing Tower, 302

14 Distillation System Optimization 305

14.1 Introduction, 305

14.2 Tower Optimization Basics, 306

14.3 Energy Optimization for Distillation System, 312

14.4 Overall Process Optimization, 318

14.5 Concluding Remarks, 326

PART 4 UTILITY SYSTEM ASSESSMENT AND OPTIMIZATION 327

15 Modeling of Steam and Power System 329

15.1 Introduction, 329

15.2 Boiler, 330

15.3 Deaerator, 333

15.4 Steam Turbine, 334

15.5 Gas Turbine, 338

15.6 Letdown Valve, 339

15.7 Steam Desuperheater, 341

15.8 Steam Flash Drum, 342

15.9 Steam Trap, 342

15.10 Steam Distribution Losses, 344

16 Establishing Steam Balances 345

16.1 Introduction, 345

16.2 Guidelines for Generating Steam Balance, 346

16.3 AWorking Example for Generating Steam Balance, 347

16.4 A Practical Example for Generating Steam Balance, 357

16.5 Verify Steam Balance, 362

16.6 Concluding Remarks, 364

17 Determining True Steam Prices 366

17.1 Introduction, 366

17.2 The Cost of Steam Generation from Boiler, 367

17.3 Enthalpy-Based Steam Pricing, 371

17.4 Work-Based Steam Pricing, 372

17.5 Fuel Equivalent-Based Steam Pricing, 373

17.6 Cost-Based Steam Pricing, 376

17.7 Comparison of Different Steam Pricing Methods, 377

17.8 Marginal Steam Pricing, 379

17.9 Effects of Condensate Recovery on Steam Cost, 384

17.10 Concluding Remarks, 384

18 Benchmarking Steam System Performance 386

18.1 Introduction, 386

18.2 Benchmark Steam Cost: Minimize Generation Cost, 387

18.3 Benchmark Steam and Condensate Losses, 389

18.4 Benchmark Process Steam Usage and Energy Cost Allocation, 394

18.5 Benchmarking Steam System Operation, 396

18.6 Benchmarking Steam System Efficiency, 397

19 Steam and Power Optimization 403

19.1 Introduction, 403

19.2 Optimizing Steam Header Pressure, 404

19.3 Optimizing Steam Equipment Loadings, 405

19.4 Optimizing On-Site Power Generation Versus Power Import, 407

19.5 Minimizing Steam Letdowns and Venting, 412

19.6 Optimizing Steam System Configuration, 413

19.7 Developing Steam System Optimization Model, 417

PART 5 RETROFIT PROJECT EVALUATION AND IMPLEMENTATION 423

20 Determine the True Benefit from the OSBL Context 425

20.1 Introduction, 425

20.2 Energy Improvement Options Under Evaluation, 426

20.3 A Method for Evaluating Energy Improvement Options, 429

20.4 Feasibility Assessment and Make Decisions for Implementation, 442

21 Determine the True Benefit from Process Variations 447

21.1 Introduction, 447

21.2 Collect Online Data for the Whole Operation Cycle, 448

21.3 Normal Distribution and Monte Carlo Simulation, 449

21.4 Basic Statistics Summary for Normal Distribution, 456

22 Revamp Feasibility Assessment 459

22.1 Introduction, 459

22.2 Scope and Stages of Feasibility Assessment, 460

22.3 Feasibility Assessment Methodology, 462

22.4 Get the Project Basis and Data Right in the Very Beginning, 465

22.5 Get Project Economics Right, 466

22.6 Do Not Forget OSBL Costs, 470

22.7 Squeeze Capacity Out of Design Margin, 471

22.8 Identify and Relax Plant Constraints, 472

22.9 Interactions Between Process Conditions, Yields, and Equipment, 473

22.10 Do Not Get Misled by False Balances, 474

22.11 Prepare for Fuel Gas Long, 475

22.12 Two Retrofit Cases for Shifting Bottlenecks, 477

22.13 Concluding Remarks, 480

23 Create an Optimization Culture with Measurable Results 481

23.1 Introduction, 481

23.2 Site-Wide Energy Optimization Strategy, 482

23.3 Case Study of the Site-Wide Energy Optimization Strategy, 487

23.4 Establishing Energy Management System, 492

23.5 Energy Operation Management, 496

23.6 Energy Project Management, 499

23.7 An Overall Work Process from Idea Discovery to Implementation, 500

References, 502

INDEX 503