Hydroprocessing for Clean Energy

Frank Zhu, PhD, is Senior Fellow at Honeywell UOP, Des Plaines. He is a leading expert in industrial process design, modeling and energy optimization with more than 80 publications and 30 patents. He is the co-founder of the ECI International Conference: CO2 Summit, the recipient of AIChE Energy and Sustainability Award, and the author of Energy and Process Optimization for the Process Industries by Wiley/AICHE. Richard Hoehn is a Senior Fellow at Honeywell UOP, Des Plaines where he has been employed for 42 years, 31 of which have been in the field of hydroprocessing.  He received a BS in chemical engineering from Purdue University. He currently holds 36 US patents and has received the Ernest W. Thiele Award from the Chicago Section of the AIChE. Dr. Vasant Thakkar, PhD, was a Senior Fellow at Honeywell UOP, Des Plaines, before retiring in 2015. Vasant worked in Refining R&D Group for over 36 years. Vasant received Honeywell Distinguished Technologist award in 2014. Vasant holds 38 US patents. He received Ph. D. in chemical Engineering from Colorado school of Mine. He held membership in AIChE and ASTM D2 committee. Edwin Yuh is a Fellow at Honeywell UOP, Des Plaines where he has been employed for 37 years, 35 of which have been in the field of hydroprocessing. He received a BS in chemical engineering from Columbia University and a MS in chemical engineering from Northwestern University. Most of his UOP career is in technical service.

Preface xiii

Part 1 Fundamentals 1

1 Overview of This Book 3

1.1 Energy Sustainability 3

1.2 ULSD – Important Part of the Energy Mix 4

1.3 Technical Challenges for Making ULSD 7

1.4 What is the Book Written for 8

References 8

2 Refinery Feeds Products and Processes 9

2.1 Introduction 9

2.2 ASTM Standard for Crude Characterization 10

2.3 Important Terminologies in Crude Characterization 12

2.4 Refining Processes 13

2.5 Products and Properties 15

2.6 Biofuel 20

3 Diesel Hydrotreating Process 23

3.1 Why Diesel Hydrotreating? 23

3.2 Basic Process Flowsheeting 25

3.3 Feeds 28

3.4 Products 30

3.5 Reaction Mechanisms 36

3.6 Hydrotreating Catalysts 40

3.7 Key Process Conditions 44

3.8 Different Types of Process Designs 47

References 48

4 Description of Hydrocracking Process 51

4.1 Why Hydrocracking 51

4.2 Basic Processing Blocks 53

4.3 Feeds 58

4.4 Products 59

4.5 Reaction Mechanism and Catalysts 61

4.6 Catalysts 67

4.7 Key Process Conditions 70

4.8 Typical Process Designs 75

References 78

Part 2 Hydroprocessing Design 79

5 Process Design Considerations 81

5.1 Introduction 81

5.2 Reactor Design 81

5.3 Recycle Gas Purity 98

5.4 Wash Water 102

5.5 Separator Design 107

5.6 Makeup Gas Compression 115

References 121

6 Distillate Hydrotreating Unit Design 123

6.1 Introduction 123

6.2 Number of Separators 123

6.3 Stripper Design 127

6.4 Debutanizer Design 135

6.5 Integrated Design 136

References 147

7 Hydrocracking Unit Design 149

7.1 Introduction 149

7.2 Single-stage Hydrocracking Reactor Section 150

7.3 Two-stage Hydrocracking Reactor Section 155

7.4 Use of a Hot Separator in Hydrocracking Unit Design 158

7.5 Use of Flash Drums 160

7.6 Hydrocracking Unit Fractionation Section Design 161

7.7 Fractionator First Flow Scheme 161

7.8 Debutanizer First Flow Scheme 163

7.9 Stripper First Fractionation Flow Scheme 166

7.10 Dual Zone Stripper Fractionation Flow Scheme 168

7.11 Dual Zone Stripper – Dual Fractionator Flow Scheme 170

7.12 Hot Separator Operating Temperature 171

7.13 Hydrogen Recovery 174

7.14 LPG Recovery 175

7.15 HPNA Rejection 177

7.16 Hydrocracking Unit Integrated Design 181

References 187

Part 3 Energy and Process Integration 189

8 Heat Integration for Better Energy Efficiency 191

8.1 Introduction 191

8.2 Energy Targeting 191

8.3 Grassroots Heat Exchanger Network (Hen) Design 202

8.4 Network Pinch for Energy Retrofit 206

Nomenclature 213

References 213

9 Process Integration for Low-Cost Design 215

9.1 Introduction 215

9.2 Definition of Process Integration 216

9.3 Grand Composite Curves (GCC) 218

9.4 Appropriate Placement Principle for Process Changes 219

9.5 Dividing Wall Distillation Column 225

9.6 Systematic Approach for Process Integration 228

9.7 Applications of the Process Integration Methodology 230

9.8 Summary of Potential Energy Efficiency Improvements 246

References 247

10 Distillation Column Operating Window 249

10.1 Introduction 249

10.2 What is Distillation? 249

10.3 Why Distillation is the Most Widely Used? 251

10.4 Distillation Efficiency 253

10.5 Definition of Feasible Operating Window 255

10.6 Understanding Operating Window 256

10.7 Typical Capacity Limits 275

10.8 Effects of Design Parameters 275

10.9 Design Checklist 278

10.10 Example Calculations for Developing Operating Window 281

10.11 Concluding Remarks 296

Nomenclature 297

References 299

Part 4 Process Equipment Assessment 301

11 Fired Heater Assessment 303

11.1 Introduction 303

11.2 Fired Heater Design for High Reliability 304

11.3 Fired Heater Operation for High Reliability 310

11.4 Efficient Fired Heater Operation 315

11.5 Fired Heater Revamp 321

Nomenclature 322

References 322

12 Pump Assessment 323

12.1 Introduction 323

12.2 Understanding Pump Head 324

12.3 Define Pump Head – Bernoulli Equation 325

12.4 Calculate Pump Head 329

12.5 Total Head Calculation Examples 330

12.6 Pump System Characteristics – System Curve 332

12.7 Pump Characteristics – Pump Curve 333

12.8 Best Efficiency Point (BEP) 338

12.9 Pump Curves for Different Pump Arrangement 338

12.10 Npsh 340

12.11 Spillback 345

12.12 Reliability Operating Envelope (ROE) 346

12.13 Pump Control 347

12.14 Pump Selection and Sizing 347

Nomenclature 351

References 351

13 Compressor Assessment 353

13.1 Introduction 353

13.2 Types of Compressors 354

13.3 Impeller Configurations 357

13.4 Type of Blades 358

13.5 How a Compressor Works 358

13.6 Fundamentals of Centrifugal Compressors 360

13.7 Performance Curves 362

13.8 Partial Load Control 364

13.9 Inlet Throttle Valve 366

13.10 Process Context for a Centrifugal Compressor 367

13.11 Compressor Selection 368

Nomenclature 369

References 369

14 Heat Exchanger Assessment 371

14.1 Introduction 371

14.2 Basic Concepts and Calculations 371

14.3 Understand Performance Criterion – U Values 374

14.4 Understand Fouling 380

14.5 Understand Pressure Drop 382

14.6 Effects of Velocity on Heat Transfer Pressure Drop and Fouling 384

14.7 Heat Exchanger Rating Assessment 385

14.8 Improving Heat Exchanger Performance 396

Nomenclature 399

References 400

15 Distillation Column Assessment 401

15.1 Introduction 401

15.2 Define a Base Case 401

15.3 Calculations for Missing and Incomplete Data 403

15.4 Building Process Simulation 406

15.5 Heat and Material Balance Assessment 408

15.6 Tower Efficiency Assessment 411

15.7 Operating Profile Assessment 414

15.8 Tower Rating Assessment 417

15.9 Guidelines 419

Nomenclature 420

References 420

Part 5 Process System Evaluation 423

16 Energy Benchmarking 425

16.1 Introduction 425

16.2 Definition of Energy Intensity for a Process 426

16.3 The Concept of Fuel Equivalent for Steam and Power (FE) 427

16.4 Data Extraction 429

16.5 Convert All Energy Usage to Fuel Equivalent 432

16.6 Energy Balance 432

16.7 Fuel Equivalent for Steam and Power 435

16.8 Energy Performance Index (EPI) Method for Energy Benchmarking 441

16.9 Concluding Remarks 444

16.10 Nomenclature 445

References 446

17 Key Indicators and Targets 447

17.1 Introduction 447

17.2 Key Indicators Represent Operation Opportunities 448

17.3 Define Key Indicators 451

17.4 Set Up Targets for Key Indicators 456

17.5 Economic Evaluation for Key Indicators 460

17.6 Application 1: Implementing Key Indicators into an “Energy Dashboard” 463

17.7 Application 2: Implementing Key Indicators to Controllers 465

17.8 It is Worth the Effort 466

Nomenclature 467

References 467

18 Distillation System Optimization 469

18.1 Introduction 469

18.2 Tower Optimization Basics 470

18.3 Energy Optimization for Distillation System 475

18.4 Overall Process Optimization 481

18.5 Concluding Remarks 489

References 490

Part 6 Operational Guidelines and Troubleshooting 491

19 Common Operating Issues 493

19.1 Introduction 493

19.2 Catalyst Activation Problems 494

19.3 Feedstock Variations and Contaminants 495

19.4 Operation Upsets 496

19.5 Treating/Cracking Catalyst Deactivation Imbalance 497

19.6 Flow Maldistribution 500

19.7 Temperature Excursion 501

19.8 Reactor Pressure Drop 504

19.9 Corrosion 506

19.10 Hpna 509

19.11 Conclusion 511

20 Troubleshooting Case Analysis 513

20.1 Introduction 513

20.2 Case Study I – Product Selectivity Changes 514

20.3 Case Study II – Feedstock Changes 516

20.4 Case Study III – Catalyst Deactivation Balance 523

20.5 Case Study IV – Catalyst Migration 526

20.6 Conclusion 536

Index 537