Process Engineering for a Small Planet How to Reuse, Re-Purpose, and Retrofit Existing Process Equipment

Our earth is just one big, complex Process Facility with limited air, water, and mineral resources. It responds to a number of process variables?among them, humanity and the environmental effects of our carbon consumption. What can professionals in the Hydrocarbon Process Industry do to retard environmental degradation? Rather than looking to exotic technology for solutions, Process Engineering for a Small Planet details ready-at-hand methods that the process engineer can employ to help combat the environmental crisis.

Drawing from the author's professional experience working with petroleum refineries petroleum refineries, petrochemical plants, and natural gas wells, this handbook explains how to operate and retrofit process facilities to:

• Reuse existing process equipment
• Save energy
• Reduce greenhouse gas emissions
• Expand plant capacity without installing new equipment
• Reduce corrosion and equipment failures

Covering topics from expanding fractionator and compressor capacity and vacuum tower heater expansion to minimizing process water consumption and increasing centrifugal pump capacity, Process Engineering for a Small Planet offers big ideas for saving our small planet.

Foreword xv

Preface xvii

Introduction: Turning of the Tide 1

1. Expanding Fractionator and Compressor Capacity 3

Reuse of Existing Fractionator

Changing Tray Deck Panels

Alternates to New Compressor

Keeping Compressor Rotor Clean

Calculating Liquid Injection Rates to Compressor

2. Vacuum Tower Heater Expansion 17

 Entrainment Velocity Limitations

 Missing Tray Deck Manways

 Heater Draft Limitation

 Improving Ejector Performance

 Velocity Steam in Heater Passes

3. Natural-Draft-Fired Heaters 27

 Control Excess Air

 O₂ and Combustible Analyzers

 Improving Air–Fuel Mixing

 Convective Section Air Leaks

 Air Preheater Leaks

 Indirect Air Preheat

4. Crude Pre-Flash Towers 37

 Pre-Flash Tower Flooding

 Energy Saving with Pre-Flash Towers

 Capacity Benefits

 Pre-Flash Tower External Reflux

5. Amine Regeneration and Sulfur Recovery 47

 Amine Capacity Expansion

 Sulfur Plant Capacity Expansion

 Rich Amine Flash Drum Design

 Cascaded Seal Legs

 Sulfur Recovery from Sour Water Stripper Off-Gas

 Acid Gas of High CO₂ Content

 Sulfur Plant Oxygen Enrichment

6. Treating and Drying Hydrocarbons 59

 Jet Fuel Treating

 Salt Dryer Operation

 Water-Washing Sodium Naphthanates from Jet Fuel

 Pipe Distributor Design

 Treating Sour Naphtha

 Converting Mercaptans to Disulfides

7. Minimizing Process Water Consumption 71

 Two-Stage Wastewater Stripper

 Steam Condensate Recovery

 Condensate Drum Balance Line Location

 Water Hammer

 Measuring Condensate Recovery

 Cooling Tower Cycles of Concentration

8. Incremental Expansion Design Concept: Reprocessing Waste Lube Oil 79

 Reprocessing Waste Lube Oil

 Vacuum Tower Design

 Wash Oil Grid Coking

 Vapor Horn Design in Vacuum Towers

 Stripping Tray Efficiency

 Precondenser Fouling

 Pump NPSH Limit in Vacuum Service

 Exchanger Fouling in Waste Oil Service

 Transfer-Line Sonic Velocity

9. Improving Fractionation Efficiency in Complex Fractionators 91

 Pre-Flash Tower Concept

 Intermediate Reflux

 Stripping Tray Efficiency

 Maximizing Diesel Recovery from Crude

 Picket Weirs

 Adjusting Pump-arounds

 Pressure Optimization

10. Increasing Centrifugal Pump Capacity and Efficiency 103

 Hydraulic Limitations

 Worn Impeller-to-Case Clearances

 Impeller Wear Ring

 Upgrading Impeller Size

 Marginal Cavitation

 Viscosity Effects on Efficiency

 NPSH Limited Condition

11. Eliminating Process Control Valves Using Variable-Speed Drivers 113

 Frequency Control of Motors

 Eliminating Control Valves on Pump Discharge

 Direct Speed Control of Steam Turbine

 Variable-Speed Compressors

 Spill-backs Waste Energy

 Calculating Incentive for Variable-Speed Drivers

 Floating Tower Pressure Control

12. Expanding Refrigeration Capacity 123

 Centrifugal Compressor Head vs. Flow Curve

 Calculating Compression Work

 Horsepower vs. Suction Pressure Limited

 Effect of Increasing Suction Pressure

 Reducing Refrigerant Condenser Fouling

 Effect of Noncondensibles

 Condensate Backup in Condenser

13. Oversizing Equipment Pitfalls 135

 Amine H₂ S Scrubber

 Optimizing Number of Trays in Absorbers

 Consequences of Overdesign

 Use of Demister in Knockout Drum

 Low Demister Velocity Promotes Mist Entrainment

14. Optimizing Use of Steam Pressure to Minimize Consumption of Energy 145

 Preserving the Potential of Steam to Do Work

 Power Recovery from Steam to a Reboiler

 Use of the Mollier Diagram

 Cogeneration Plants

 Extracting Work from Reboiler Steam Using

 Existing Equipment

 Understanding Thermodynamics of Flowing Steam

 Steam Turbine Efficiency Checklist

15. Expanding Compressor Capacity and Efficiency 157

 Reciprocating Compressors

 Pulsation Dampener Plates

 Adjustable Head-End Unloaders

 Natural Gas Engines

 Axial Compressor

 Rotor Fouling of Axial Air Compressor

 Centrifugal Compressors

 Cleaning Centrifugal Compressor Rotor

16. Vapor–Liquid Separator Entrainment Problems 171

 Effect of Foam on Indicated Liquid Levels

 Hydrogen-Heavy Gas Oil Separtors

 Foam Induced Carry-Over

 Enhancing De-Entrainment Rates

 Vapor Distribution Aids De-Entrainment

17. Retrofitting Shell-and-Tube Heat Exchangers for Greater Efficiency 179

 Running Slops Without Fouling

 Floating Suction in Charge Tanks

 Exchanger Online Spalling

 Effect of Feed Interruptions

 Tube Velocity and Surface Roughness

 Shell-Side Seal Strips

 Cooling High-Viscosity Fluids

 Expanding Water Cooler Capacity

 Hydrocarbon Losses to Cooling Towers

18. Reducing Sulfur and Hydrocarbon Emissions 189

 Sulfur Plant Waste Heat Boiler Modifications

 Hydrocarbon Leaks in Seawater Cooling Systems

 Incinerator Back-Fire in Sulfur Plant Main

 Reaction Furnace

 Loss of Draft Due to Air Leaks

 Global Emissions in Perspective

19. Hydrocarbon Leaks to the Environment 201

 Measuring Leaks Through Valves

 Fixing Leaking Valves On-Stream

 Detecting Leaking Relief Valves

 On-Stream Repair of Leaking Relief Valves

 Measuring Flows in Flare Lines

 Leaks into Cooling Water

 Air Cooler Leaks

 Valve Stem Packing

 Leaking Pump Mechanical Seal and Improper Use of Seal Flush

 Fixing Weld Leaks On-Stream

20. Composition-Induced Flooding in Packed Towers: FCU Fractionator Expansion 209

 Fluid Cracking Unit Fractionator Expansion

 Flooding of Slurry Oil P/A Sections

 FCU Fractionator Vapor Line Quench

 Multipump Piping Stress Analysis

 Perception vs. Reality in Process Design

21. Maintenance for Longer Run Lengths 219

 Sulfuric Acid Regeneration

 Importance of Reactor Insulation

 On-Stream Piping Repairs

 Preserving Pump Mechanical Seals

 Concept of Avoiding Unit Shutdowns

22. Instrument Malfunctions 229

 Control Valve Loss Due to Instrument Air Pressure Signal

 Stuck Flow Control Valve Stem

 Mislocated Liquid-Level Tap

 Reducing Load to Vacuum System by Correcting False Level Indication

23. Summary Checklist for Reuse of Process Equipment 237

 Fired Heaters

 Heat Exchangers

 Fin-Fan Air Coolers

 Distillation Tower Trays

 Vapor–Liquid Separators

 Centrifugal Pumps

 Fixed-Bed Reactors

 Electric Motors

 Gas and Steam Turbines

 Reciprocating and Centrifugal Compressors

 Air Blowers

 Water–Hydrocarbon Separators

 Overcoming Utility System Limits

24. Water–Hydrocarbon Separation: Corrosive Effects of Water 245

 Water–Oil Separators

 Corrosive Elements from Cracking Plants

 Water Traps in Strippers

 Current CO₂ Levels

 Environmental Overview

 Appendix: Solar Power Potential 257

 Index 259