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LIEBERMAN BOOKS

pemalfunctions

By Norman P. Lieberman

PROCESS EQUIPMENT MALFUNCTIONS:
Techniques to Identify and Correct Plant Problems

FIRST EDITION PUBLISHED BY: McGRAW-HILL
ISBN 978-0-07-177020-0

CONTENTS

Chapter 1. Distillation Tray Malfunctions:Decreasing Tower Delta P / Resealing Downcomers / Effect on Fractionation / Effect of Displaced / Downcomer / Downcomer Bracing Brackets / Top Tray Flooding / Loss of Liquid Level on Tray Decks / Lost Bubble Cap Clearance / Directional Flow Tray Panels / Missing Reboiler Return Impingement Plate / Flow Path Length / Discrimination between Flooding & Dumping / Shed- or Baffle- type Trays / Author’s Observations: Concepts versus Calculations
Chapter 2. Packed Tower Problems: Syn Gas Scrubber Flooding / Reduction in Percent Open Area / Corrugated Grid Support / Packed Bed Failure in a Catacarb Regenerator / Bed Hold Downs / Liquid Distribution to Packed Beds / Gravity Distributors Used in Fractionation Service / Spray Nozzle Malfunctions / Spray Nozzle Pressure Drop / Plastic Packing / Packed Towers in Offshore Applications
Chapter 3.

Distillation Tower Pressure & Composition Control: Steam Trap Stability Malfunctions / Heat Makes Pressure / Leaking Vent Valve / Excess Condensing Capacity / Oversized Control Valves / Effect of Light Ends on Pressure Control / Effect of Lighter Components on Overhead Composition Control / Use of Balance Lines / Ambient Conditions & Air-Cooled Condenser / Sticking Control Valve / Instability in Cyclic Operations / Instabilty Due to Flooding / Thermosyphon Circulation Instability / Feed Instability / Author’s Observations: Chemical Engineering Education – Reality versus Theory

Chapter 4. Salt & Rust Formation on Tray Decks: Naphtha Reformer Stabilizer / Continuous Water Wash / KOH Carry-Over / Dry Amine Salt Sublimation on Trays / Draw-Off  Nozzle Plugging with NH4Cl Salts / Carbon Steel Tray Decks / Movable Valve Caps / Water in Reflux Absorbs Salts from Vapors / Combustible Salts in Packed Towers
Chapter 5. Fractionator Bottoms Product Stripping: Sampling Hot, Heavy Residual Hydrocarbons / Bypassed Stripping Trays / Restoring Stripping Efficiency / Faulty Stripping Tray Installation / Failure of Vacuum Tower Stripping Trays / Seal Pan Problems / Stripping Tray Efficiency / Commissioning Steam Strippers / Screwed Connections on Vessel Walls – A Safety Note / Reference
Chapter 6.

Heat Extraction with Pumparounds: Pump-Downs versus Pumparounds / Effect of Tray Loading / Circulation Pump Cavitation / Undersized Draw-Off Nozzle / Effect of Pumparounds on Fractionation Efficiency / Pumparound Heat Transfer Capacity / Structured Packing in Pumparounds / Duplex Filter Malfunctions / Pumparounds Do Fractionate

Chapter 7. Reboiled and Steam SideStrippers: Excessive Vapor Line Delta P / Lack of Elevation Driving Force / Subcooled Liquid Feed / The Function of Stripping Steam / Moisture in Stripping Steam / Lack of the Loop Seal / Jammed Control Valve / High Liquid Level / Top Tray Flooding / Hole Distribution / Reboiled Side Stream Strippers / False Steam Flow Indication
Chapter 8. Inspecting Tower Internals: Use of a Self-Leveling Laser Light / What to Look for When Inspecting Trays / Tower Closure / Seal Pan Design Error
Chapter 9.

Process Reboilers – Shell and Tube: Effect of Velocity on Heat Transfer Coefficient / Flux Limited Situations / Forced-Circulation Refrigerant / Film Resistance in Sensible Heat Transfer / Effect of Vortex Shedding on Reboiler Duty / Effect of Additional Baffles / Lost Thermosyphon Circulation / Reboiler Delta P Causes Tower Flooding / Kettle Reboilers / Cutting Holes in Kettle Reboiler Baffles / Tower Stab-In Reboilers / Reboiler Floating Head and Tube Leaks / Steam-Side Problems

Chapter 10.

Shell-and-Tube Heat Exchangers in Sensible Heat Transfer Service: Advantages of U-Tube Exchangers / Effect of Surface Roughness / Fouling Due to Laminar Flow / Combating Tube-Side Fouling / Avoiding the Root Cause of Fouling / Shell-Side Fouling / Exchanger Tube Leaks / Finding Tube Leaks / Effect of Viscosity on Laminar Flow / Excessive Exchanger Delta P – Tube Side / Excessive Delta P – Shell Side / Excessive Nozzle Delta P / Two-Pass Shell Benefits / Two-Pass Shell Malfunctions / Fouling Due to Gum Formation

Chapter 11.

Condenser Limitations: Blow-Through / Optimum Drainability Point / Identifying Condensate Back-up in the field / Methods to Achieve the Optimum Drainability Point / Required Subcooling of Condensed Liquids / Non-Condensable Venting / Exchanger Fouling / Use of Low-Fin Tubes in Condenser Service / Cooling Medium Problems / Parallel Condensers with Non-Symmetrical Piping / Combined Effect of Blow-Through and Condensate Back-up

Chapter 12. Air Coolers – Forced- and Induced-Draft Air Side Malfunctions: Effect of Moisture on Aluminum Fins / Fin Mechanical Damage / Measuring Airflow Through Bundle / Air Recirculation / Vane Tip Clearance / Increasing Airflow for Forced-Draft Fans / Cleaning Air Cooler Fins / Removing Loose Deposits from Fins / Fan Speed Adjustment and Louvers / Excess Amperage Load on Motors / Induced-Draft Fans / Hot Air Recirculation / Water Sprays with Air Coolers / Sloped Air Cooler Bundles / References
Chapter 13. Cooling Water: Towers and Circulation: Hydraulic Losses in Cooling Water Systems / Cleaning Water Circulation Lines / Changing Tube-Side Passes / Fouling on Water Side / Other Circulating Problems / Cooling Tower Efficiency / Cooling Tower Fire Protection / Bypassing Water-Cooled Exchangers / Author’s Comments
Chapter 14.

Steam Condensate Collection Systems: Consequences of Flashing in Condensate Drain Line / Condensate Drum Elevation / Correcting Steam Condensate Back-up / Temperature Approach Pinch Point / Limits of Process Engineering Design / Review Question / Blowing the Condensate Seal / Level Malfunctions in Condensate Drums / Steam and Water Hammer / Correcting Steam/Water  Hammer / Corrosion Potential of Condensate / Shell-Side Condensate Back-up / Condensate Recovery Pump / Summary of Malfunctions / Condensate Back-up Due to Oversizing / Correcting Water Hammer

Chapter 15. Steam Quality Problems: Steam Turbine Vibrations / Leaking Superheat Coils / Vacuum Jet Performance / Steam Stripping Hot Oil / Steam/Methane Reformers / Plugging Steam Sparger / Salting Out of Overspeed Trip on Turbine / Measuring the Moisture Content of Steam / Appearance of Wet Steam / Suppressing Entrainment / Delta T Level Control / Moisture Due to Turbine Exhaust / Vacuum Jet Demonstration / Ambient Heat Losses / Effects of Superheated Steam / Boiler Feed Water Quality / Steam Contamination with Non-condensibles / Using Low-Quality Steam
Chapter 16.

Level Control Problems:Becoming Tapped Out / Plugged Level Taps / Blowing Out Level Taps / Erratic Level Indication Due to Tray Flooding / Moisture in Level Taps / Suction Pressure Control / Split Liquid Levels / Insulating a Level-Trol / External Skin Temperatures / Stab-In Reboiler Level Control / Level Control in Waste Heat Boilers / Observing Interface Levels in Clear Liquids / Water-Hydrocarbon Interface / Measuring Levels of Solids / Mislocated Top-Level Taps / Redundancy Minimizes Effect of Malfunctions / Consequences of Level Malfunctions / Stilling Well

Chapter 17.

Excessive Ambient Heat Losses: Whiting Hi-Fi Unit / Manway Insulation / Calculating Ambient Heat Losses / Steam-Jacketed Pipe / Transfer Line Flanges / Effect of Wet Insulation / Insulation in Refrigeration System / Un-Insulated Minimum Flow Spill-Back / Fuel Saving for Replacing a Channel Head Insulating Blanket

Chapter 18. Process Plant Corrosion: Weld Leaks / Erosion-Corrosion / Some Common Corrosion Problems / Naphthenic Acid Corrosion and Sulfur / Chrome Embrittlement – Piping and Vessels / Surface Condenser Seal Strip Failure / Carbon Steel versus Chrome Steel Piping / Quantifying Corrosion Rates in Piping / Corrosion Effect on Process Efficiency / Hydrogen Ion Penetration in Steel / Carbonic Acid Corrosion / Shell Norco Explosion / H2S promotes  HCl Corrosion / Internal Boiler Tube Corrosion / Effect of a High Velocity / Author’s Comment
Chapter 19. Vapor-Liquid Separation Vessels: Kellog Allowable Velocity / Inadequate Tower Diameter /  Inadequate Vertical Height / Fog Formation / Excessive Inlet Velocities / Foam Formation in Bottoms / Factors Promoting Foam Formation / Defoaming Agents / Plugged Level Taps / Effect of Pressure and Temperature / Effect of Surface Tension / Measuring Entrainment Rates / Vapor Separation from a High-Viscosity Liquid /
Chapter 20.

Knock-Out Drums; Demisters and Impingement Plates: Demister Malfunctions / Catacarb CO2 Absorber Carryover / Demister Suppresses Overspray / Demister in Sulfuric Acid Service / Improper Use of Demisters / Demister Malfunction in Compressor Suction / Internal Vortex Breaker Tubes / Impingement Plate in Knock-Out Drums / Fog / Droplet Properties Affect Settling Rate

Chapter 21.

Hydrocarbon -Water Separation – Electric Desalters and Gravity Settling : Crude Oil Desalter Malfunctions / Measuring Emulsion Levels / Causes and Cures of Emulsion Layer Growth / Excessive Vapor Pressure / Water–Oil Separation by Gravity / Liquid Phase Interface Level Indication / Safety Note – Manual Water Drains / Coalescers

Chapter 22. Natural Draft Fired Heaters: Calculating Available Draft / Fouled and Distorted Convective Section Tubes / Combustion Air Limitations / The Point of Absolute Combustion / Cause of Poor Air-Fuel Mixing Efficiency / Indication of Lack of Combustion Air / Safety Note Regarding Adjusting Excess Air / Air Limitations Due to Physical Restrictions / Heat Release Limitations / Excessive Radiant Heat Density / Flame Impingement / Erratic Draft
Chapter 23.

Tube Failure in Fired Heaters: High-Temperature Creep / Tube Hot Spot Identification / Causes of Coke Formation in Tubes / Feed Interruption / Flame Impingement / Sodium in Feed / Tube Pigging to Remove Coke / Tube Dry-Out Deposits / Convective Tube Failure in Steam Generation Service / Exterior Tube Failure in Oil-Fired Heaters / Excessive Average Heat Flux Rates / Effect of Air Preheat and Energy Savings / Water in Feed to Coker Heater Radiant Tubes / Carbon Steel Tube Failures

Chapter 24. Fired Heaters: Air Preheaters: Preheating Air to a Vacuum Tower Heater / Air Preheater Fouling and Delta P / Air Preheater Creates Draft Limitations / Example of Flue Gas By-Passing / Air Pre-Heat Using Low-Pressure Steam / Preheater Leaks Reduce Combustion Air / Loss of Draft Through an Empty Air Preheater Exchanger / Overheating Combustion Air / Fire Damage to an Air Preheater / Restrictive Air Intake / Correct Design Alternatives for Air Peheater / Rules of Thumb for Temperature Gradients
Chapter 25. Disabling Safety Systems: Acid Plant Shut-Down / What Constitutes an Emergency / Sulfur Plant Hydrogen Sulfide Feed Gas Trip / By-passing the Start-up or Trip Panel / Flame-Out Detector Malfunction / Intentionally Disabled Safety Devices And Trips / Incinerator Pilot Light Malfunction / Furnace High-Temperature Fuel Gas Trip / Author’s Comment
Chapter 26. Vacuum Systems and Steam Jets: Converging-Diverging Ejector / Velocity Boost / Wet Steam / Surging / Water in Motive Steam / Effect of Spill-Back on Pressure Stability / By-passing Primary Ejector / Mechanical Defects of Jets / Diffuser Erosion / Steam Nozzle Erosion / Critical Jet Discharge Pressure / Fouling of Waste Gas Burner / Overloading Vacuum Jets / Air Equivalent / Relative Jet Efficiency / High Discharge Pressure / Hogging Jets / Liquid Seal Ring Compressor / Liquid Ejectors / High-Pressure, Superheated Motive Steam / Fouled Steam Nozzle
Chapter 27. Vacuum Surface Condensers and Precondensers: Condensate Back-up Due to Air Leak in Barometric Drain Line / Leaks Inside Seal Drum / Sludge Accumulation in Seal Drum / Detecting Condensate Back-up / Air Baffle Internal Leakage / Oversized Impingement Plate / Impingement Plates as Vapor Distributors / Cooling Water Pressure to Surface Condensers / Tube Leaks / Air Leaks / Cooling Water Flow Configuration / Management Malfunctions / Fixed Tube Sheet Condensers / Author’s Comments
Chapter 28. Excess Gas Overloads: Vacuum Systems Ejectors: Air Leaks / How to Find Air Leaks / Air Leaks on Vacuum Towers / Exchanger Leaks / Poor Vacuum Tower Feed Stripping / Evolution of Cracked Gas / Sources of Cracked Gas / Effect of Heater Outlet Temperature / Cracked Gas Evolution from Boot / Air Leaks in Heater Transfer Lines / Purges and Seal Gas / Reminder about Water Partial Pressure
Chapter 29. Centrifugal Pump NPSH Limitations: Cavitation, Seal and Bearing Failures: Symptoms of Cavitation / Seal Failure Due to Piping Alignment Problems / Causes of Lack of NPSH / Starting NPSH Requirements / Leaks into Pump Suction / Mixing two Dissimilar Streams in a Pump Suction / Correcting Vaporization in a Draw-Off Sump / Low NPSH Pumps / Plugged Suction Screens / Preserving Mechanical Seal Integrity / Effect of Increased Vessel Pressure / Effect of Lighter Liquid / Effect of Lower Temperature on Pump Cavitation / Sump Pumps / Other Causes of Seal Damage / Bearing Vibrations / Pumping Aerated Liquids / Pressure Control and Pump Cavitation
Chapter 30. Centrifugal Pump and Driver Capacity Limits: Lubrication Failures: Combating Excessive Motor Loads / Pump Operation on Flat Part of Performance Curve / Turbine-Driven Pumps / Steam Quality Issues / Effect of Specific Gravity on Pump Capacity / Marginal Cavitation Limits / Checking Performance on Pump Curve / Pump Spinning Backwards / Undersized Control Valves / Running Pumps in Parallel / Negative Pump Curve / Bearing Lubriction / Pressure Accumulation in Bearing Housing / Pump Rotation Schedule / Motor Lubrication / Origin of Pump Vibrations
Chapter 31. Steam Turbine Drivers: Is Wet Steam Good or Bad? / Interaction of Speeding Steam with a Machine / Turbine Driven Pumps / Governor Speed Control / Steam Chest Port Valves / Port Valve Malfunctions / Low Steam Chest Pressure / Overspeed Trip Malfunctions / Accidentally Closed Port Valve / Condensing Steam Turbines / Water in Turbine-Driven Pump Bearing Housing / Critical Speed Vibrations / Turbine versus Motor Drivers / Gas Fired Turbines
Chapter 32. Centrifugal Compressors: Surge, Fouling, and Driver Limits: Ratio of Specific Heats of a Gas / The Dynamic Nature of Centrifugal Compressors / Factors Affecting Vapor Density (PV) / Factors Affecting Feet of Head (HP) / Density versus Head Requirements / What is Surge? / Effect of Spill-Back on Surge / Suction Throttling versus Spill-Back / Stonewalling / Rotor Fouling / Salt Accumulation in Rotor Wheels / Excessive Vibrations / Work versus Flow in Dynamic Compressors
Chapter 33. Reciprocating Compressors: Unloading and Efficiency: The Carnot Cycle / Pulsation Malfunctions / Indicator Card (or Beta Scan) / Drawing Conclusions from Indicator Card / Typical Reciprocating Compressor Efficiency / Pulsation Damping Plates / Breaking Piston Rods / Gas Engine Drives / Starting Volumetric Efficiency / Controlling Compressor Gas Flow Rates / Head-End Adjustable Unloaders / Effect of Molecular Weight on Compressor Performance / Reciprocating versus Centrifugal Compressor Selection
Chapter 34. Summary: Typical Energy Savings and Efficiency Projects: How to Harvest an Apple Orchard / Steam Turbines / Centrifugal Pumps / Distillation / FCU Air Blower Limitations / Vacuum Towers / Fired Heaters / What’s the Problem?

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