Table of Contents

Cover

Title Page

Preface

Part 1: Fundamentals

Chapter 1: Overview of This Book
1. 1.1 Energy Sustainability
2. 1.2 ULSD – Important Part of the Energy Mix
3. 1.3 Technical Challenges for Making ULSD
4. 1.4 What is the Book Written for
5. References
Chapter 2: Refinery Feeds, Products, and Processes
1. 2.1 Introduction
2. 2.2 ASTM Standard for Crude Characterization
3. 2.3 Important Terminologies in Crude Characterization
4. 2.4 Refining Processes
5. 2.5 Products and Properties
6. 2.6 Biofuel
Chapter 3: Diesel Hydrotreating Process
1. 3.1 Why Diesel Hydrotreating?
2. 3.2 Basic Process Flowsheeting
3. 3.3 Feeds
4. 3.4 Products
5. 3.5 Reaction Mechanisms
6. 3.6 Hydrotreating Catalysts
7. 3.7 Key Process Conditions
8. 3.8 Different Types of Process Designs
9. References
Chapter 4: Description of Hydrocracking Process
1. 4.1 Why Hydrocracking
2. 4.2 Basic Processing Blocks
3. 4.3 Feeds
4. 4.4 Products
5. 4.5 Reaction Mechanism and Catalysts
6. 4.6 Catalysts
7. 4.7 Key Process Conditions
8. 4.8 Typical Process Designs
9. References

Part 2: Hydroprocessing Design

Chapter 5: Process Design Considerations
1. 5.1 Introduction
2. 5.2 Reactor Design
3. 5.3 Recycle Gas Purity
4. 5.4 Wash Water
5. 5.5 Separator Design
6. 5.6 Makeup Gas Compression
7. References
Chapter 6: Distillate Hydrotreating Unit Design
1. 6.1 Introduction
2. 6.2 Number of Separators
3. 6.3 Stripper Design
4. 6.4 Debutanizer Design
5. 6.5 Integrated Design
6. References
Chapter 7: Hydrocracking Unit Design
1. 7.1 Introduction
2. 7.2 Single-stage Hydrocracking Reactor Section
3. 7.3 Two-stage Hydrocracking Reactor Section
4. 7.4 Use of a Hot Separator in Hydrocracking Unit Design
5. 7.5 Use of Flash Drums
6. 7.6 Hydrocracking Unit Fractionation Section Design
7. 7.7 Fractionator First Flow scheme
8. 7.8 Debutanizer First Flow scheme
9. 7.9 Stripper First Fractionation Flow scheme
10. 7.10 Dual Zone Stripper Fractionation Flow scheme
11. 7.11 Dual Zone Stripper – Dual Fractionator Flow scheme
12. 7.12 Hot Separator Operating Temperature
13. 7.13 Hydrogen Recovery
14. 7.14 LPG Recovery
15. 7.15 HPNA Rejection
16. 7.16 Hydrocracking Unit Integrated Design
17. References

Part 3: Energy and Process Integration

Chapter 8: Heat Integration for Better Energy Efficiency
1. 8.1 Introduction
2. 8.2 Energy Targeting
3. 8.3 Grassroots Heat Exchanger Network (Hen) Design
4. 8.4 Network Pinch for Energy Retrofit
5. Nomenclature
6. References
Chapter 9: Process Integration for Low-Cost Design
1. 9.1 Introduction
2. 9.2 Definition of Process Integration
3. 9.3 Grand Composite Curves (GCC)
4. 9.4 Appropriate Placement Principle for Process Changes
5. 9.5 Dividing Wall Distillation Column
6. 9.6 Systematic Approach for Process Integration
7. 9.7 Applications of the Process Integration Methodology
8. 9.8 Summary of Potential Energy Efficiency Improvements
9. References
Chapter 10: Distillation Column Operating Window
1. 10.1 Introduction
2. 10.2 What is Distillation?
3. 10.3 Why Distillation is the Most Widely Used?
4. 10.4 Distillation Efficiency
5. 10.5 Definition of Feasible Operating Window
6. 10.6 Understanding Operating Window
7. 10.7 Typical Capacity Limits
8. 10.8 Effects of Design Parameters
9. 10.9 Design Checklist
10. 10.11 Concluding Remarks
11. Nomenclature
12. References

Part 4: Process Equipment Assessment

Chapter 11: Fired Heater Assessment
1. 11.1 Introduction
2. 11.2 Fired Heater Design for High Reliability
3. 11.3 Fired Heater Operation for High Reliability
4. 11.4 Efficient Fired Heater Operation
5. 11.5 Fired Heater Revamp
6. Nomenclature
7. References
Chapter 12: Pump Assessment
1. 12.1 Introduction
2. 12.2 Understanding Pump Head
3. 12.3 Define Pump Head – Bernoulli Equation
4. 12.4 Calculate Pump Head
5. 12.5 Total Head Calculation Examples
6. 12.6 Pump System Characteristics – System Curve
7. 12.7 Pump Characteristics – Pump Curve
8. 12.8 Best Efficiency Point (Bep)
9. 12.9 Pump Curves for Different Pump Arrangement
10. 12.10 Npsh
11. 12.11 Spillback
12. 12.12 Reliability Operating Envelope (ROE)
13. 12.13 Pump Control
14. 12.14 Pump Selection and Sizing
15. Nomenclature
16. References
Chapter 13: Compressor Assessment
1. 13.1 Introduction
2. 13.2 Types of Compressors
3. 13.3 Impeller Configurations
4. 13.4 Type of Blades
5. 13.5 How a Compressor Works
6. 13.6 Fundamentals of Centrifugal Compressors
7. 13.7 Performance Curves
8. 13.8 Partial Load Control
9. 13.9 Inlet Throttle Valve
10. 13.10 Process Context for a Centrifugal Compressor
11. 13.11 Compressor Selection
12. Nomenclature
13. References
Chapter 14: Heat Exchanger Assessment
1. 14.1 Introduction
2. 14.2 Basic Concepts and Calculations
3. 14.3 Understand Performance Criterion – U Values
4. 14.4 Understand Fouling
5. 14.5 Understand Pressure Drop
6. 14.6 Effects of Velocity on Heat Transfer, Pressure Drop, and Fouling
7. 14.7 Heat Exchanger Rating Assessment
8. 14.8 Improving Heat Exchanger Performance
9. Nomenclature
10. References
Chapter 15: Distillation Column Assessment
1. 15.1 Introduction
2. 15.2 Define a Base Case
3. 15.3 Calculations for Missing and Incomplete Data
4. 15.4 Building Process Simulation
5. 15.5 Heat and Material Balance Assessment
6. 15.6 Tower Efficiency Assessment
7. 15.7 Operating Profile Assessment
8. 15.8 Tower Rating Assessment
9. 15.9 Guidelines
10. Nomenclature
11. References

Part 5: Process System Evaluation

Chapter 16: Energy Benchmarking
1. 16.1 Introduction
2. 16.2 Definition of Energy Intensity for a Process
3. 16.3 The Concept of Fuel Equivalent for steam and Power (FE)
4. 16.4 Data Extraction
5. 16.5 Convert All Energy Usage to Fuel Equivalent
6. 16.6 Energy Balance
7. 16.7 Fuel Equivalent for Steam and Power
8. 16.8 Energy Performance Index (EPI) Method for Energy Benchmarking
9. 16.9 Concluding Remarks
10. 16.10 Nomenclature
11. References
Chapter 17: Key Indicators and Targets
1. 17.1 Introduction
2. 17.2 Key Indicators Represent Operation Opportunities
3. 17.3 Define Key Indicators
4. 17.4 Set Up Targets for Key Indicators
5. 17.5 Economic Evaluation for Key Indicators
6. 17.6 Application 1: Implementing Key Indicators Into an “Energy Dashboard”
7. 17.7 Application 2: Implementing Key Indicators to Controllers
8. 17.8 It Is Worth the Effort
9. Nomenclature
10. References
Chapter 18: Distillation System Optimization
1. 18.1 Introduction
2. 18.2 Tower Optimization Basics
3. 18.3 Energy Optimization for Distillation System
4. 18.4 Overall Process Optimization
5. 18.5 Concluding Remarks
6. References

Part 6: Operational Guidelines and Troubleshooting

Chapter 19: Common Operating Issues
1. 19.1 Introduction
2. 19.2 Catalyst Activation Problems
3. 19.3 Feedstock Variations and Contaminants
4. 19.4 Operation Upsets
5. 19.5 Treating/Cracking Catalyst Deactivation Imbalance
6. 19.6 Flow Maldistribution
7. 19.7 Temperature Excursion
8. 19.8 Reactor Pressure Drop
9. 19.9 Corrosion
10. 19.10 HPNA
11. 19.11 Conclusion
Chapter 20: Troubleshooting Case Analysis
1. 20.1 Introduction
2. 20.2 Case Study I – Product Selectivity Changes
3. 20.3 Case Study II – Feedstock Changes
4. 20.4 Case Study III – Catalyst Deactivation Balance
5. 20.5 Case Study IV – Catalyst Migration
6. 20.6 Conclusion
Index

End User License Agreement

List of Illustrations

Chapter 3: Diesel Hydrotreating Process

Figure 3.1 Diesel hydrotreating cold separator flow scheme.
Figure 3.2 Diesel hydrotreating hot separator flow scheme.
Figure 3.3 Saturates (paraffin, naphthene, and olefins) and aromatic distribution.
Figure 3.4 Trends of sulfur specification change over time.
Figure 3.5 Hydrotreating catalysts shapes.
Figure 3.6 Simplified process flow diagram.
Figure 3.7 Description of two-stage process pilot plant.

Chapter 4: Description of Hydrocracking Process

Figure 4.1 Where hydrocracking fits in the refinery configuration.
Figure 4.2 Once-through process flow scheme.
Figure 4.3 Single-stage process flow scheme.
Figure 4.4 Two-stage process flow scheme.
Figure 4.5 Dual-function hydrocracking catalyst components.
Figure 4.6 Metal function.
Figure 4.7 Competing pathways for conversion of multiring aromatics.
Figure 4.8 Commonly used Y zeolite structure.
Figure 4.9 Commercial catalyst shapes.
Figure 4.10 Effect of conversion on hydrocracking performance.
Figure 4.11 Relative deactivation rate change for change in pressure.
Figure 4.12 Effect of recycle gas rate.
Figure 4.13 Advanced partial conversion hydrocracking.
Figure 4.14 Mild hydrocracking – incorporates finishing reactor in single gas and pressure loop.
Figure 4.15 One pressure loop and one recycle gas loop for cost-efficient design.
Figure 4.16 Two-stage high conversion design.

Chapter 5: Process Design Considerations

Figure 5.1 Flow map for two-phase packed bed reactor system.
Figure 5.2 Example of gravity flow distributor.
Figure 5.3 Example of vapor lift distributor.
Figure 5.4 Example of quench distributor and mixing system.
Figure 5.5 Example of good catalyst bed distribution.
Figure 5.6 Example of bad catalyst bed distribution.
Figure 5.7 Example of dense loading machine.
Figure 5.8 Example of reactor bed pressure drop buildup due to fines.
Figure 5.9 Distributor basket location.
Figure 5.10 Distributor basket orientation.
Figure 5.11 Examples of graded bed loading.
Figure 5.12 Effect of cold separator temperature on recycle gas hydrogen purity for a single separator hydroprocessing unit.
Figure 5.13 Effect of cold separator temperature on recycle gas hydrogen purity for a hydroprocessing unit with a hot separator.
Figure 5.14 Equilibrium K versus temperature for hydrogen, nitrogen, and selected hydrocarbons.
Figure 5.15 Enrichment flow scheme.
Figure 5.16 Effect of enrichment ratio on hydrogen purity.
Figure 5.17 Ammonium bisulfide disassociation curve.
Figure 5.18 Ammonium chloride disassociation curve.
Figure 5.19 Symmetrical piping arrangement.
Figure 5.20 Wash water circulation flow scheme.
Figure 5.21 Example of vertical three-phase separator.
Figure 5.22 Example of horizontal separator.
Figure 5.23 Clearance pocket for a reciprocating compressor.
Figure 5.24 Operation of stepless valve unloading system.
Figure 5.25 Single spillback compressor configuration.
Figure 5.26 Stagewise compressor spillback configuration.

Chapter 6: Distillate Hydrotreating Unit Design

Figure 6.1 Single separator flow scheme.
Figure 6.2 Hot separator flow scheme.
Figure 6.3 Reboiled stripper column.
Figure 6.4 Steam stripped stripper column.
Figure 6.5 Dew point monitor for steam stripped columns.
Figure 6.6 Solubility of water in n-octane versus temperature.
Figure 6.7 Water content of distillate product for various operating pressures.
Figure 6.8 Exchanger surface area requirements versus hot separator temperature.
Figure 6.9 Total capital + operating costs versus hot separator operating temperature.
Figure 6.10 Solution loss for a hydrotreating unit with and without a hot separator.
Figure 6.11 Hydrogen recovery without flash drums.
Figure 6.12 Hydrogen recovery with flash drums.
Figure 6.13 Heat recovery ratio (β) versus heater duty fraction (Q_H).

Chapter 7: Hydrocracking Unit Design

Figure 7.1 Single-stage hydrocracking unit.
Figure 7.2 Relation between distillate selectivity and conversion per pass.
Figure 7.3 Alternative single-stage recycle hydrocracking flow scheme.
Figure 7.4 Two-stage hydrocracking unit.
Figure 7.5 Separate hydrotreat hydrocracking unit.
Figure 7.6 Fractionator first flow scheme.
Figure 7.7 Debutanizer first fractionation flow scheme.
Figure 7.8 Composition profile for a debutanizer column in a debutanizer first flow scheme.
Figure 7.9 Stripper first fractionation flow scheme.
Figure 7.10 Composition profile for stripper column in a stripper first configuration.
Figure 7.11 TBP distillation of hot and cold flash liquid.
Figure 7.12 Dual-zone stripper fractionation flow scheme.
Figure 7.13 Dual-zone stripper dual-fractionator flow scheme.
Figure 7.14 Cold flash liquid temperature requirement versus hot separator operating temperature.
Figure 7.15 Stripping steam requirement versus hot separator operating temperature.
Figure 7.16 Reactor section exchanger surface versus hot separator operating temperature.
Figure 7.17 Total capital + operating costs versus hot separator operating temperature.
Figure 7.18 Solution loss for a hydrocracking unit.
Figure 7.19 LPG recovery flow scheme.
Figure 7.20 Overall LPG recovery versus lean oil rate.
Figure 7.21 Recycle oil sample from a high conversion hydrocracking unit.
Figure 7.22 HPNA adsorption chamber installation.
Figure 7.23 Schematic of HPNA stripping zone.
Figure 7.24 Feed and product from an HPNA stripping zone.
Figure 7.25 Reactor section flow scheme.
Figure 7.26 Light fractionation section.
Figure 7.27 Heavy fractionation section.

Chapter 8: Heat Integration for Better Energy Efficiency

Figure 8.1 Composite curves: heat demand (grey) versus heat availability (dark) profiles. (a) No heat recovery case; (b) heat recovery (hatched area).
Figure 8.2 Process flow diagram as an example of energy targeting.
Figure 8.3 (a) T/H representation of three hot streams; (b) T/H representation of a hot composite stream.
Figure 8.4 (a) T/H representation of two cold streams; (b) T/H representation of a cold composite stream.
Figure 8.5 Composite curves representing the three hot and two cold streams.
Figure 8.6 Basic concepts of composite curves.
Figure 8.7 (a) Energy targets for a specified ΔT_min; (b) energy targets for different ΔT_min.
Figure 8.8 Pinch principle: penalty of cross-pinch heat transfer.
Figure 8.9 Calculation of surface area from the composite curves.
Figure 8.10 Capital and energy trade-off.
Figure 8.11 Cost targeting for determining ΔT_min,opt.
Figure 8.12 General stream splitting and matching based on the composite curves.
Figure 8.13 Block decomposition.
Figure 8.14 Composite curves for the illustrative example.
Figure 8.15 Initial design for the example: Q_H = 139.4 kW, area = 320 m², total cost =$51,188/year.
Figure 8.16 Optimized design for the example: Q_H = 144.3 kW, area = 289 m², total cost = $46,786/year.
Figure 8.17 An illustration of a network pinch.
Figure 8.18 Process flow diagram for the crude distillation unit.
Figure 8.19 Base case heat exchanger network.
Figure 8.20 Heat recovery limits in the base case network.
Figure 8.21 Resequence of exchanger 4: min Q_H = 98.08; ΔQ_Rec = 4.4.
Figure 8.22 Heat recovery limits for the network after resequence of exchanger 4.
Figure 8.23 Stream split: min Q_H = 96.3; ΔQ_Rec = 1.8.
Figure 8.24 Retrofit design developed by the network pinch method.

Chapter 9: Process Integration for Low-Cost Design

Figure 9.1 The trend of increased refinery complexity over time.
Figure 9.2 Sequential process design: traditional design approach.
Figure 9.3 Construction of grand composite curve. (a) Composite curves. (b) Shifted composite curves. (c) Grand composite curve.
Figure 9.4 Selection of multiple utility. (a) Bad utility selection, (b) proper utility selection, (c) utility involving furnace.
Figure 9.5 Reaction integration against process. (a) Poor reaction integration. (b) Better reaction integration.
Figure 9.6 Construction of column grand composite curve. (a) Converged simulation. (b) Column grand composite. (c) Ideal column.
Figure 9.7 Column integration with process. (a) Inappropriate placement. (b) Using column modification for integration. (c) Appropriate placement.
Figure 4.8 Procedure for column integration with process. (a) Feed stage optimization. (b) Reflux modification. (c) Feed conditioning. (d) Side condensing/reboiling.
Figure 4.9 Feed stage optimization.
Figure 4.10 Thermal inefficiency in direct sequence. (a) Direct distillation sequence. (b) Component profiles for the columns.
Figure 4.11 Thermal efficiency for prefractionator arrangement. (a) Prefractionator arrangement. (b) Component profiles for the columns.
Figure 4.12 From prefractionation to dividing wall. (a) Prefractionator. (b) Thermally coupled columns (Petlyuk column). (c) Dividing wall column.
Figure 4.13 Process integration methodology.
Figure 4.14 Effects of catalyst improvements on process energy efficiency.
Figure 4.15 Single-stripper fractionation scheme.
Figure 4.16 Proposed two-stripper fractionation scheme.
Figure 7.17 Composite curves representing the single-stripper fractionation scheme.
Figure 7.18 Composite curves representing the two-stripper fractionation scheme.
Figure 7.19 Grand composite curve for the single-stripper fractionation scheme.
Figure 7.20 Grand composite curve for the two-stripper fractionation scheme.
Figure 7.21 Stacked two-stripper fractionation scheme.
Figure 7.22 Current design: single column depentanizer with sidedraw.
Figure 7.23 Dividing wall column for the depentanizer.
Figure 7.24 Existing naphtha separation for 2-naphtha products.
Figure 7.25 Typical design scheme of naphtha separation for 4-naphtha products.
Figure 7.26 Separation of three naphtha products. (a) Typical sequence of two splitter columns. (b) Dividing wall column.
Figure 7.27 Applying dividing wall to naphtha separation.
Figure 9.28 Existing hydrocracking unit.
Figure 9.29 Energy-saving projects to remove the heater bottlenecks.
Figure 9.30 Reaction and fractionation projects to remove the process bottlenecks.

Chapter 10: Distillation Column Operating Window

Figure 10.1 A complex configuration of a distillation column.
Figure 10.2 McCabe–Thiele diagram.
Figure 10.3 O'Connell correlation.
Figure 10.4 A typical trend of tower efficiency.
Figure 10.5 Capacity limits for distillation tower.
Figure 10.6 Vapor–liquid flow structure on tray deck.
Figure 10.7 Spray.
Figure 10.8 Downcomer backup flood.
Figure 10.9 Downcomer choke.
Figure 10.10 Fair's C_F correlation.
Figure 10.11 Key parameters for tray hydraulics (this graph is used for model illustration).
Figure 10.12 Downcomer design velocity curves in Figure 4 of Glitsch Design Manual (1974).
Figure 10.13 Maximum downcomer velocity correlation based on Glitsch's Figure 4 (1974).
Figure 10.14 Typical capacity diagram.
Figure 10.15 The flow regimes in distillation.
Figure 10.16 Tray design procedure.
Figure 10.17 Derive A_d from w_d and r.
Figure 10.18 Tray layout for the example problem.
Figure 10.19 Operating window for the example problem.

Chapter 11: Fired Heater Assessment

Figure 11.1 Schematic view of a typical process fired heater.
Figure 11.2 Flux profile and heat distribution in a heater.
Figure 11.3 Flux distribution around fired heater tube.
Figure 11.4 Tube thinning follows the flux distribution.
Figure 11.5 Correct and incorrect draft. (a) Proper draft control; (b) too high draft; (c) too low draft; (d) draft representation.
Figure 11.6 An example of flame impingement.
Figure 11.7 Good flame color and height.
Figure 11.8 Poor flame pattern from the first burner.
Figure 11.9 Dollar value for reducing O₂% by 1%. *Based on fuel price at $3/MMBtu.
Figure 11.10 Optimizing excess air.
Figure 11.11 Determining optimal O₂% level.
Figure 11.12 Integrated draft and O₂ control. (1) High draft – fire box pressure more negative; (2) low draft – fire box pressure more positive; (3) low or high O₂% – O₂% is above or below target.

Chapter 12: Pump Assessment

Figure 12.1 Pump head applies to any liquid (pump operating under no flow condition).
Figure 12.2 A simple process system.
Figure 12.3 A practical process system.
Figure 12.4 Illustration of Bernoulli equation (12.7).
Figure 12.5 Example 12.1 pump system curve.
Figure 12.6 Process system.
Figure 12.7 Pump system curve.
Figure 12.8 System curve for no static lift.
Figure 12.9 System curve for small friction losses.
Figure 12.10 System curve for negative static lift.
Figure 12.11 System curve for double discharges.
Figure 12.12 Pump head versus flow rate.
Figure 12.13 Pump curve for Figure 12.12.
Figure 12.14 Pump normal operating point.
Figure 12.15 Pump curve and system curve could change.
Figure 12.16 Pump curve.
Figure 12.17 Pump curves for single and two pumps in series.
Figure 12.18 Pump curves for single and two pumps in parallel.
Figure 12.19 A typical pump suction system.
Figure 12.20 NPSH_A expressed in feet for typical pump suction.
Figure 12.21 Pump suction for Example 12.3.
Figure 12.22 Reliability operating envelope.
Figure 12.23 Two flow control options.
Figure 12.24 Optimal pump selection.
Figure 12.25 Pump curves with corresponding impeller diameters and BHP curves.

Chapter 13: Compressor Assessment

Figure 13.1 Basic principles of compressor.
Figure 13.2 Centrifugal multistage horizontal split.
Figure 13.3 Centrifugal multistage radially split compressor.
Figure 13.4 Integrally geared centrifugal compressor.
Figure 13.5 Straight-through compressor.
Figure 13.6 Back-to-back compressor with double flow inlet.
Figure 13.7 2D blades with circular arc shape (a) or 3D blades with complex shape (b).
Figure 13.8 Key components of centrifugal compressor.
Figure 13.9 Different FC impellers: from low at the left to high at the right.
Figure 13.10 Performance curve for a centrifugal compressor.
Figure 13.11 Compressor performance curves.
Figure 13.12 Impeller with higher head coefficient has a smaller rise-to-surge.
Figure 13.13 Typical variable speed control compressor performance curves.
Figure 13.14 Performance curves for inlet guide vane control with constant speed driver.
Figure 13.15 Inlet guide vane control – constant speed driver.
Figure 13.16 Typical process involving a compressor.

Chapter 14: Heat Exchanger Assessment

Figure 14.1 Location of h's and R's.
Figure 14.2 (a) Countercurrent and (b) cocurrent flows.
Figure 14.3 F_t factor for 1–2 TEMA E shell-and-tube exchangers.
Figure 14.4 TEMA standard shell types and front and rear-end head types.
Figure 14.5 A parallel arrangement of two 1–2 exchangers.

Chapter 15: Distillation Column Assessment

Figure 15.1 Heat-pumped C3 Splitter.
Figure 15.2 Use of heat/mass balances to obtain missing data.
Figure 15.3 McCabe–Thiele diagram.
Figure 15.4 A typical trend of tower efficiency.
Figure 15.5 Example column flow profile.
Figure 15.6 Example column temperature profile for a benzene–toluene separation.
Figure 15.7 Example composition profile for toluene–ethyl benzene separation.

Chapter 16: Energy Benchmarking

Figure 16.1 Energy flows into and out of the process unit.
Figure 16.2 Energy balance in a visualized form.
Figure 16.3 Steam system for Example problem 16.1.

Chapter 17: Key Indicators and Targets

Figure 17.1 Typical single-stage hydrocracking unit.
Figure 17.2 Debutanizer column in hydrocracking unit.
Figure 17.3 Correlations of debutanizer reboiler duty and other parameters.
Figure 17.4 Two common operating patterns: (a) inconsistent operation; (b) consistent operation but nonoptimal.
Figure 17.5 Operating data: (a) historian; (b) frequency distribution.
Figure 17.6 Operation performance: (a) current operation; (b) reduced variability; (c) increased profit.
Figure 17.7 Convert time series data in Figure 17.6 into normal distribution curves: (a) current; (b) reduced variability; (c) increased profit.
Figure 17.8 Converting the normal distribution curve to economic curve.
Figure 17.9 Economic curves generated based on normal distributions.

Chapter 18: Distillation System Optimization

Figure 18.1 Debutanizer example: energy optimization based on reflux ratio.
Figure 18.2 Operating margin as a function of the bottom composition.
Figure 18.3 Observed composition normal distribution versus operating margin.
Figure 18.4 Improved composition normal distribution versus operating margin.
Figure 18.5 Energy-separation trade-off: energy cost increases linearly as reflux rate while the top product quality improves.
Figure 18.6 Optimum reflux rate depends on energy price.
Figure 18.7 Pressure has significant effect on energy cost.
Figure 18.8 Deisopentanizer flow scheme.
Figure 18.9 Variation of DIP performance.
Figure 18.10 Optimization without Isom capacity constraint.
Figure 18.11 Optimization with Isom capacity constraint.
Figure 18.12 DIP economic improvements.

Chapter 19: Common Operating Issues

Figure 19.1 Example of catalyst NABT and ABT.
Figure 19.2 Pretreat nitrogen slip on pretreat (R1) and cracking (R2) ABT.
Figure 19.3 Effect of pretreat nitrogen slip on pretreat (R1) and cracking (R2) catalyst life.
Figure 19.4 Boy scouts fire and hydroprocessing reaction triangles.
Figure 19.5 Temperature excursion simulation.
Figure 19.6 Two temperature spike excursion.
Figure 19.7 Iron sulfide fine pressure drop problem.
Figure 19.8 REAC system – balanced design.
Figure 19.9 REAC system problem areas.
Figure 19.10 PNAs and HPNAs.
Figure 19.11 Mechanism of HPNA fouling.
Figure 19.12 HPNA management.
Figure 19.13 Unconverted oil color.

Chapter 20: Troubleshooting Case Analysis

Figure 20.1 Hydrocracking operating concerns.
Figure 20.2 Product distribution of different crudes.
Figure 20.3 First-stage cracking catalyst activity loss.
Figure 20.4 Step change in cracking catalyst activity.
Figure 20.5 High-temperature simulated distillation of feedstock.
Figure 20.6 Component analysis.
Figure 20.7 Catalyst performance after diesel flush and hot hydrogen strip.
Figure 20.8 Reactor bed configuration.
Figure 20.9 Pretreat temperature performance.
Figure 20.10 Cracking temperature performance.
Figure 20.11 New ceramic support.
Figure 20.12 Broken ceramic support.
Figure 20.13 R101 migration.
Figure 20.14 R201 migration.
Figure 20.15 Reactor outlet collector.
Figure 20.16 Catalyst migration into feed/effluent exchanger.
Figure 20.17 R101 bed 4 bottoms temperatures (24 points).
Figure 20.18 R101 bed 4 mid and top temperatures (8 points).
Figure 20.19 Catalyst in another feed/effluent exchanger.
Figure 20.20 Deformed first stage outlet collector.
Figure 20.21 Outlet collector – chunks of metal missing near the junction.

List of Tables

Chapter 4: Description of Hydrocracking Process

Table 4.1 FCC and Hydrocracking Process Key Differences
Table 4.2 Nominal Operating Conditions for Typical Hydrocracking Unit
Table 4.3 Hydrocracking Feeds and Products from the Processing
Table 4.4 Product Fractions and the General Use
Table 4.5 Chemical Basis for Product Quality Measurements
Table 4.6 Hydroprocessing Reactions

Chapter 5: Process Design Considerations

Table 5.1 Flux Values for Hydroprocessing Reactors
Table 5.2 Effect of Flux on Reactor Size and Weight
Table 5.3 Typical K Values for Mesh Blankets

Chapter 6: Distillate Hydrotreating Unit Design

Table 6.1 Capital and Operating Cost Comparison for Hot Separator Flow Scheme versus Conventional Flow Scheme
Table 6.2 Diesel Fuel Standards for the United States and Europe
Table 6.3 Stripper Operation versus Hot Separator Temperature
Table 6.4 Recoverable Hydrogen in Flash Gas for a Hot Separator Flow Scheme
Table 6.5 Relative LPG Recovery with and without Flash Drums
Table 6.6 Recoverable Hydrogen Solution Loss versus Operating Pressure
Table 6.7 Process Considerations for Hydrogen Purification Technology
Table 6.8 Distillate Hydrotreater Design Comparison
Table 6.9 Utilities Cost Basis

Chapter 7: Hydrocracking Unit Design

Table 7.1 Typical Feedstock and Processing Conditions for VGO Hydrocracking
Table 7.2 Solution and Recoverable Hydrogen via Flash Drums
Table 7.3 Comparison of Capital Cost for Fractionator First and Stripper First Flow scheme
Table 7.4 Utilities Comparison for Fractionator First and Stripper First Flow scheme
Table 7.5 Utilities Comparison for Single Stripper versus Dual-Zone Stripper Designs
Table 7.6 Capital Cost Comparison for Single Stripper Versus Dual-Zone Stripper Designs
Table 7.7 Utilities Comparison for Single Stripper, Dual-Zone Stripper, and Dual-Zone Stripper/Dual-Fractionator Designs
Table 7.8 Typical Yields for a Maximum Distillate Hydrocracking Unit
Table 7.9 Composition of Flash Gas and Stripper Overhead Streams

Chapter 8: Heat Integration for Better Energy Efficiency

Table 8.1 Stream Data for the Illustrative Example
Table 8.2 Design Performance for the Illustrative Example

Chapter 9: Process Integration for Low-Cost Design

Table 9.1 Typical Energy Saving from Different Categories of Opportunities

Chapter 10: Distillation Column Operating Window

Table 10.1 System Factors
Table 10.2 Relation of Weir Loading Limits and Tray Spacing (Nutter Engineering, 1981)
Table 10.3 Example Tower Design Check List
Table 10.4 Column Overhead Conditions
Table 10.5 Trials of Calculating Tray Diameter
Table 10.6 Downcomer Layout for Example Problem
Table 10.7 Tray Design Overall Summary
Table 10.9 Hydraulic Performance Summary

Chapter 11: Fired Heater Assessment

Table 11.1 Maximum Flux Rate Used in an Operating Company, Btu/h ft²

Chapter 14: Heat Exchanger Assessment

Table 14.1 Gathered Data for a Reaction Air Cooler
Table 14.2 Calculation Results for a Reaction Air Cooler
Table 14.3 Liquid Fouling Factors

Chapter 15: Distillation Column Assessment

Table 15.1 Major Data Set for a Heat-Pumped C3 Splitter
Table 15.2 Heat and Mass Balances for a C2 Splitter
Table 15.3 Mass Balance Around a Fractionation Tower

Chapter 16: Energy Benchmarking

Table 16.1 Example Data Set for Energy Use and Generation

Chapter 18: Distillation System Optimization

Table 18.1 Product Specifications and Prices
Table 18.2 Simulation Results Versus DIP Operating Data
Table 18.3 Simulation Results at Designed Reboiler Duty

Chapter 20: Troubleshooting Case Analysis

Table 20.1 Options to Increase Naphtha Yield
Table 20.2 Feed Analysis – Aromatics Distribution

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Names: Zhu, Frank Xin X., author. | Hoehn, Richard, 1950- author. | Thakkar, Vasant, author. | Yuh, Edwin, 1954- author.

Title: Hydroprocessing for clean energy : design, operation and optimization / Frank (Xin X.) Zhu, Richard Hoehn, Vasant Thakkar, Edwin Yuh.

Description: Hoboken, New Jersey : John Wiley & Sons, Inc., [2017] | Includes bibliographical references and index.

Identifiers: LCCN 2016038243| ISBN 9781118921357 (cloth) | ISBN 9781119328254 (epub) | ISBN 9781119328247 (Adobe PDF)

Classification: LCC TP690.4 .Z49 2017 | DDC 660-dc23 LC record available at https://lccn.loc.gov/2016038243

Cover image courtesy: UOP Unicracking Process Unit of the Bangchak Petroleum Public Company Limited, Bangkok, Thailand

Preface

It all started during a conversation between Frank Zhu and Dick Hoehn over a beer while watching the big ships wind their way through the Bosphorus Strait during a trip to Istanbul for a customer meeting in 2009. The conversation centered on how to pass on some of the things that we have learned over the years, and in doing so, pay homage to those who were willing to share their knowledge with us along the way. We decided that a book would be a good medium to do this, and thus the seed was planted.

We eventually settled on a topic currently relevant to refiners: clean energy with a focus on the production of ultra-low-sulfur diesel (ULSD) in particular. The selection of this topic came from realizing that a paradox exists in the world: people want to enjoy life fueled with a sufficient and affordable energy supply and, at the same time, live in a clean environment. There is no magic formula for achieving this, but with a knowledge of fundamentals and appropriate application of technology, the goal can be realized.

ULSD is an important part of the clean energy mix. It is made by hydroprocessing of certain fractions of petroleum crude oil. It is used in cars, trucks, trains, boats, buses, heavy machinery, and off-road vehicles. The bad news is that without adequate processing to produce clean diesel fuel and upgraded engine technology, diesel engines emit sulfur dioxide and particulates. The impact of fuel sulfur on air quality is widely understood and known to be significant.

There are challenges in producing ULSD in an economical and reliable manner. Over the years, a great deal of effort has been poured into developing the catalysts and process technology to accomplish this. It is intended that this book will be a resource for hydroprocessing technology as it relates to hydroprocessing in general and ULSD production in particular and that it will be a useful reference for plant managers, hydroprocessing unit engineers, operators, and entry-level design engineers.

We believe that there is currently no book available to provide relevant knowledge and tools for the process design and operation of facilities to produce ULSD, particularly considering the fact that these guidelines and methods have evolved over time to address the issues with the efficient production of ULSD. To this end, we decided that the book should cover four themes: fundamentals, design, assessment, and troubleshooting. That was the reason why the current team of authors was formed to create this book. The four themes correspond with each individual author's experience and expertise. An R&D specialist, Vasant, has an extensive background in the fundamentals of hydroprocessing catalysis (Chapters 3 and 4); Dick has many years of experience in the field of engineering design and development of hydroprocessing technology (Chapters 5–7); Edwin, a technical service specialist, brings a wealth of knowledge about operations and troubleshooting (Chapters 19 and 20); and Frank has both academic and practical background in process energy efficiency, process integration, and assessment methods (all other 13 chapters). The four authors represent a sum total of over 100 years of experience in the field of hydroprocessing.

The purpose of this book is to bridge the gap between hydroprocessing technology developers and the engineers who design and operate the processes. To accomplish this, 6 parts with 20 chapters in total are provided in this book. Part 1 provides an overview of the refining processes including the feeds and products together with their specifications, in particular, the fundamental aspects for hydroprocessing are discussed in detail. Part 2, mainly discusses on process design aspects for both diesel hydrotreating and hydrocracking processes. The focus of Part 3 is on process and heat integration methods for achieving high energy efficiency in design. In Part 4, the basics and operation assessment for major process equipment are discussed. In contrast, Part 5 focuses on process system optimization for achieving higher energy efficiency and economic margin. Last but not least, Part 6 deals with operation, in which operation guidelines are provided and troubleshooting cases are discussed.

Clearly, it was no small effort to write this book; but it was the desire to provide practical methods for helping people understand the issues involved in improving operations and designing for better energy efficiency and lower capital cost, which motivated us. In this endeavor, we owe an enormous debt of gratitude to many of our colleagues at UOP and Honeywell for their generous support in this effort. First of all, we would like to mention Geoff Miller, former vice president of UOP and now vice president of Honeywell, who has provided encouragement in the beginning of this journey for writing this book. We are very grateful to many colleagues for constructive suggestions and comments on the materials contain in this book. We would especially like to thank the following people for their valuable comments and suggestions: Bettina Marie Patena for Chapters 5 through 7, Zhanping (Ping) Xu for Chapter 10, Darren Le Geyt for Chapter 11, Bruce Lieberthal for Chapters 12 and 13, and Phil Daly for Chapter 14. Our sincere gratitude also goes to Charles Griswold, Mark James, and Rich Rossi for their constructive comments. Jane Shao produced beautiful drawings for many figures in the book. The contributions to this book from people mentioned above are deeply appreciated. I would also like to thank our co-publishers, AIChE and John Wiley for their help. Special thanks go to Steve Smith AIChE and Michael Leventhal for their guidance. The copyediting and typesetting by Vishnu Priya and her team at John Wiley is excellent. Finally, we would like to point out that this book reflects our own opinions but not those of UOP or Honeywell.

Frank (Xin X.) Zhu
Richard Hoehn
Vasant Thakkar
Edwin Yuh

Des Plaines, Illinois USA

June 1, 2016

HYDROPROCESSING FOR CLEAN ENERGY

Design, Operation, and Optimization

Preface

Part 1
Fundamentals