Cover
Half-Title Page
Distillation Troubleshooting
ISBN: 0-4714-6744-8
Dedication
Table of Contents
1: Troubleshooting Distillation Simulations
CASE STUDY 1.1 METHANOL IN C3 SPLITTER OVERHEAD?
CASE STUDY 1.2 WATER IN DEBUTANIZER: QUOVADIS?
CASE STUDY 1.3 BEWARE OF HIGH HYDROCARBON VOLATILITIES IN WASTEWATER SYSTEMS
CASE STUDY 1.4 A HYDROCARBON VLLE METHOD USED FOR AQUEOUS FEED EQUILIBRIUM
CASE STUDY 1.5 MODELING TERNARY MIXTURE USING BINARY INTERACTION PARAMETERS
CASE STUDY 1.6 VERY LOW CONCENTRATIONS
REQUIRE EXTRA CARE IN VLE SELECTION
CASE STUDY 1.7 DIAGRAMS TROUBLESHOOT
ACETIC ACID DEHYDRATION SIMULATION
CASE STUDY 1.8 EVERYTHING VAPORIZED
IN A CRUDE VACUUM TOWER SIMULATION
CASE STUDY 1.9 CRUDE VACUUM TOWER SIMULATION UNDERESTIMATES RESIDUE YIELD
CASE STUDY 1.10 MISLED BY ANALYSIS
CASE STUDY 1.11 INCORRECT FEED
CHARACTERIZATION LEADS TO IMPOSSIBLE PRODUCT SPECIFICATIONS
CASE STUDY 1.12 CAN YOU NAME
THE KEY COMPONENTS?
CASE STUDY 1.13 LOCAL EQUILIBRIUM
FOR CONDENSERS IN SERIES
CASE STUDY 1.14 SIMULATOR HYDRAULIC
PREDICTIONS: TO TRUST OR NOT TO TRUST?
CASE STUDY 1.15 PACKING HYDRAULIC
PREDICTIONS: TO TRUST OR NOT TO TRUST
CASE STUDY 1.16 DO GOOD CORRELATIONS MAKE THE SIMULATION HYDRAULIC CALCULATIONS RELIABLE?
2: Where Fractionation Goes Wrong
CASE STUDY 2.1 NO REFLUX, NO SEPARATION
CASE STUDY 2.2 HEAVIER FEEDSTOCK
IMPEDES STRIPPING
CASE STUDY 2.3 POOR H 2 S REMOVAL FROM NAPHTHA HYDROTREATER STRIPPER
CASE STUDY 2.4 HEAVIES ACCUMULATION
INTERRUPTS BOIL-UP
CASE STUDY 2.5 INTERREBOILER DRIVES TOWER
TO A PINCH
CASE STUDY 2.6 TEMPERATURE MULTIPLICITY IN
MULTICOMPONENT DISTILLATION
CASE STUDY 2.7 COMPOSITION PROFILES ARE KEY
TO MULTICOMPONENT DISTILLATION
CASE STUDY 2.8 COMPOSITION PROFILE PLOT
TROUBLESHOOTS MULTICOMPONENT SEPARATION
CASE STUDY 2.9 WATER ACCUMULATION CAUSES
CORROSION IN CHLORINATED HYROCARBON TOWER
CASE STUDY 2.10 HICCUPS IN A REBOILED
DEETHANIZER ABSORBER
CASE STUDY 2.11 WATER ACCUMULATION IN
REBOILED DEETHANIZER ABSORBER
CASE STUDY 2.12 WATER ACCUMULATION AND
HICCUPS IN A REFLUXED GAS PLANT DEETHANIZER
CASE STUDY 2.13 HICCUPS IN A COKER
DEBUTANIZER
CASE STUDY 2.14 HICCUPS IN A SOLVENT
RECOVERY COLUMN
CASE STUDY 2.15 THREE-PHASE DISTILLATION
CALCULATIONS AND TRAPPED COMPONENTS
CASE STUDY 2.16 HICCUPS IN AN
AMMONIA STRIPPER
CASE STUDY 2.17 EXCESS PREHEAT
LEADS TO HICCUPS
CASE STUDY 2.18 RECYCLING CAUSES
WATER TRAPPING
CASE STUDY 2.19 IMPURITY BUILDUP IN ETHANOL TOWER
CASE STUDY 2.20 INTERREBOILER INDUCES
STUBBORN HYDRATES IN A C2 SPLITTER
CASE STUDY 2.21 SIPHONING IN DECANTER OUTLET PIPES
CASE STUDY 2.22 HICCUPS IN AZEOTROPIC
DISTILLATION TOWER
CASE STUDY 2.23 HICCUPS IN AN EXTRACTIVE
DISTILLATION TOWER
3: Energy Savings and Thermal Effects
CASE STUDY 3.1 EXCESS PREHEAT BOTTLENECK CAPACITY
CASE STUDY 3.2 A COLUMN REVAMP
THAT TAUGHT SEVERAL LESSONS
CASE STUDY 3.3 BYPASSING A FEED AROUND THE TOWER
CASE STUDY 3.4 HEAT INTEGRATION SPIN
CASE STUDY 3.5 CHANGE IN CUT POINT FLOODS TOWER
CASE STUDY 3.6 SIMULATION DIAGNOSES HEAT
REMOVAL BOTTLENECK
CASE STUDY 3.7 REMEMBER THE HEAT BALANCE
4: Tower Sizing and Material Selection Affect Performance
CASE STUDY 4.1 EXTREMELY SMALL DOWNCOMERS
INDUCE PREMATURE FLOOD
CASE STUDY 4.2 EXTREMELY SMALL DOWNCOMERS FLOOD PREMATURELY
CASE STUDY 4.3 DUMPING LEADS TO
FLUCTUATIONS IN A DEPROPANIZER
CASE STUDY 4.4 LOW DEPROPANIZER
FEED CAPACITY
CASE STUDY 4.5 MINOR TRAY DESIGN CHANGES ELIMINATE CAPACITY BOTTLENECK
CASE STUDY 4.6 ESTABLISHING DOWNCOMER SEAL
CAN BE DIFFICULT
CASE STUDY 4.7 A TROUBLESOME PROCESS WATER
STRIPPER
CASE STUDY 4.8 DOES YOUR DISTILLATION
SIMULATION REFLECT THE REAL WORLD?
CASE STUDY 4.9 FLOOD TESTING OF A PACKED VACUUM TOWER
CASE STUDY 4.10 IN SPECIAL APPLICATIONS,
SPRAY TOWERS DO BETTER THAN PACKINGS
5: Feed Entry Pitfalls in Tray Towers
CASE STUDY 5.1 FLASHING FEED GENERATES A 12-YEAR BOTTLENECK
CASE STUDY 5.2 FLASHING FEED ENTRY CAN
MAKE OR BREAK A TOWER
CASE STUDY 5.3 FLASHING FEED PIPING BOTTLENECKS DEMETHANIZER
CASE STUDY 5.4 FLASHING FEED ENTRY CAN
BOTTLENECK A TOWER
CASE STUDY 5.5 A GOOD TURN ELIMINATES
HYDRAULIC HAMMER
CASE STUDY 5.6 DISTRIBUTION KEY TO GOOD
SHED DECK HEAT TRANSFER
6: Packed-Tower Liquid Distributors Number 6 on the Top 10 Malfunctions
CASE STUDY 6.1 MALDISTRIBUTION CAN ORIGINATE FROM A MULTITUDE OF SOURCES
CASE STUDY 6.2 IMPROVED DISTRIBUTION
AND PUMPAROUNDS CUT EMISSIONS
CASE STUDY 6.3 KEEPING SOLIDS OUT OF PACKING DISTRIBUTORS
CASE STUDY 6.4 PLUGGED DISTRIBUTORS
CASE STUDY 6.5 DISTRIBUTOR OVERFLOWS
CASE STUDY 6.6 A HATLESS VAPOR RISER PREVENTS PROPER SCRUBBING
CASE STUDY 6.7 FEED PIPES NEED PROPER CHANGES WHEN REPLACING TRAYS BY PACKINGS
CASE STUDY 6.8 SLUG FLOW IN A DEBUTANIZER
FEED PIPE
CASE STUDY 6.9 SLUG FLOW IN FEED PIPE
CASE STUDY 6.10 COLLECTOR DRIP BYPASSES
DISTRIBUTOR
CASE STUDY 6.11 HOW NOT TO MODIFY A LIQUID DISTRIBUTOR
CASE STUDY 6.12 TRACER ANALYSIS LEADS TO A
HOLE IN A DISTRIBUTOR
CASE STUDY 6.13 TILTED DISTRIBUTORS GIVE
POOR IRRIGATION
7: Vapor Maldistribution in Trays and Packings
CASE STUDY 7.1 OVERFLOWING VAPOR DISTRIBUTOR CAUSES PACKING FLOOD
CASE STUDY 7.2 VAPOR CROSS-FLOW
CHANNELING
CASE STUDY 7.3 CENTER DOWNCOMER
OBSTRUCTS BOTTOM FEED
CASE STUDY 7.4 CHANNELING INITIATING AT A
CHIMNEY TRAY
8: Tower Base Level and Reboiler Return Number 2 on the Top 10 Malfunctions
CASE STUDY 8.1 BASE LIQUID LEVEL CAN MAKE
OR BREAK A FRACTIONATOR
CASE STUDY 8.2 HIGH-LIQUID-LEVEL DAMAGE
CASE STUDY 8.3 EVENT TIMING ANALYSIS
DIAGNOSES HIGH-LIQUID-LEVEL DAMAGE
CASE STUDY 8.4 CAN IMPROVED LEVEL
MONITORING AVOID HIGH-LEVEL DAMAGE?
CASE STUDY 8.5 HIGH-BASE-LEVEL
DAMAGE INCIDENTS
CASE STUDY 8.6 REBOILER RETURN IMPINGEMENT
ON LIQUID LEVEL DESTABILIZES TOWER
CASE STUDY 8.7 INSUFFICIENT SURGE CAUSES INSTABILITY
CASE STUDY 8.8 BAFFLING BAFFLES
CASE STUDY 8.9 A 7-FT VORTEX
9: Chimney Tray Malfunctions Part of Number 7 on the Top 10 Malfunctions
CASE STUDY 9.1 HEAT BALANCES CAN IDENTIFY TOTAL DRAW LEAKS
CASE STUDY 9.2 ANOTHER LEAKING TOTAL-DRAW
CHIMNEY TRAY
CASE STUDY 9.3 CHIMNEY TRAY OVERFLOW
TARNISHES SUCCESSFUL REVAMP
CASE STUDY 9.4 LEAKING CHIMNEY TRAY UPSETS
FCC FRACTIONATOR HEAT BALANCE
CASE STUDY 9.5 FLAT HATS CAN INDUCE LEAKS
CASE STUDY 9.6 HYDRAULIC GRADIENT ON A
CHIMNEY TRAY
CASE STUDY 9.7 "LEAK-PROOF" CHIMNEY TRAYS
IN AN FCC MAIN FRACTIONATOR
CASE STUDY 9.8 LIQUID-LEVEL MEASUREMENT ON
A CHIMNEY TRAY
CASE STUDY 9.9 A CHIMNEY TRAY BOTTLENECKING
FCC MAIN FRACTIONATOR
10: Draw-Off Malfunctions (Non-Chimney Tray) Part of Number 7 on the Top 10 Malfunctions
CASE STUDY 10.1 CHOKING OF DOWNCOMER
TRAP-OUT LINE
CASE STUDY 10.2 FRACTIONATOR DRAW INSTABILITY
CASE STUDY 10.3 A NONLEAKING DRAW TRAY
CASE STUDY 10.4 LEAK TESTS ARE KEY TO PRODUCT RECOVERY
CASE STUDY 10.5 DOWNCOMER UNSEALING
AT DRAW PAN
CASE STUDY 10.6 LIQUID ENTRAINMENT IN VAPOR DRAW
CASE STUDY 10.7 WEEP INTO A VAPOR SIDE DRAW
CASE STUDY 10.8 AERATION DESTABILIZES
REFLUX FLOW
11: Tower Assembly Mishaps Number 5 on the Top 10 Malfunctions
CASE STUDY 11.1 SHOULD VALVE FLOATS BE REMOVED BEFORE BLANKING?
CASE STUDY 11.2 DIRECTIONAL VALVE
INSTALLATION
CASE STUDY 11.3 CAN PICKET FENCE WEIRS CAUSE EARLY FLOODING?
CASE STUDY 11.4 INSPECTING SEAL PANS IS A MUST
CASE STUDY 11.5 A GOOD SIMULATION LEADS TO
OPEN MANWAYS
CASE STUDY 11.6 LUBE OIL VACUUM
TOWER PROBLEM
CASE STUDY 11.7 DEBRIS IN LIQUID DISTRIBUTOR
CAUSES ENTRAINMENT
CASE STUDY 11.8 POOR RANDOM PACKING
INSTALLATION LOSES CAPACITY, FRACTIONATION
CASE STUDY 11.9 COMING TO GRIPS WITH RANDOM PACKING HANDLING
CASE STUDY 11.10 STRUCTURED PACKING
INSTALLATION
CASE STUDY 11.11 CORRECT FEED INTO
PARTING BOXES
CASE STUDY 11.12 INVERTED CHIMNEY HATS
CASE STUDY 11.13 PROBLEMS WITH FABRICATION
AND INSTALLATION OF PACKING LIQUID
DISTRIBUTORS
CASE STUDY 11.14 ONE HEAT EXCHANGER
CAUSING PROBLEMS IN TWO TOWERS
CASE STUDY 11.15 LIQUID LEG IN VENT LINE LEADS
TO TOWER UPSET
CASE STUDY 11.16 IS YOUR COOLING WATER FLOWING BACKWARD?
12: Difficulties During Start-Up, Shutdown, Commissioning, and Abnormal Operation Number 4 on the Top 10 Malfunctions
CASE STUDY 12.1 COMMISSIONING OF LEAN-OIL STILL REBOILER
CASE STUDY 12.2 REVERSE FLOW LEADS TO
CORROSION AND FLOODING
CASE STUDY 12.3 CAUSTIC WASH
CAN DISSOLVE DEPOSITS
CASE STUDY 12.4 ON-LINE WASH
OVERCOMES SALT PLUGGING
CASE STUDY 12.5 SIMULATION IDENTIFIES DRAW
PAN DAMAGE
CASE STUDY 12.6 UNIQUE CONTROL PROBLEM IN
TOTAL-REFLUX START-UPS
13: Water-Induced Pressure Surges Part of Number 3 on the Top 10 Malfunctions
CASE STUDY 13.1 SIDE-STRIPPER PRESSURE
SURGE CAN DAMAGE MAIN FRACTIONATOR
CASE STUDY 13.2 DAMAGE DUE TO WATER ENTRY INTO HOT TOWERS
CASE STUDY 13.3 INTERFACE CONTROL LEADS TO PRESSURE SURGE IN QUENCH TOWER
14: Explosions, Fires, and Chemical Releases Number 10 on the Top 10 Malfunctions
CASE STUDY 14.1 PREVENTING STRUCTURED PACKING FIRES
CASE STUDY 14.2 PREVENTING STRUCTURED
PACKING FIRES
CASE STUDY 14.3 OTHER PACKING FIRE EXPERIENCES
15: Undesired Reactions in Towers
CASE STUDY 15.1 LOWERING BOTTOM
TEMPERATURE CAN STOP REACTION
CASE STUDY 15.2 REACTION, AZEOTROPING,
ACCUMULATION, AND FOAMING
CASE STUDY 15.3 DO NOT PREJUDGE THE DESIRABILITY OF A REACTION
16: Foaming
CASE STUDY 16.1 CONCLUSIVE TEST FOR FOAMING
CASE STUDY 16.2 POOR OPERATION OF AMINE ABSORBER
CASE STUDY 16.3 TOO MUCH ANTIFOAM IS WORSE THAN TOO LITTLE
CASE STUDY 16.4 STATIC MIXER HELPS
ANTIFOAM INJECTION
CASE STUDY 16.5 GAMMA SCANS
DIAGNOSE FOAMING
CASE STUDY 16.6 LOW DOWNCOMER VELOCITIES
ARE CRITICAL FOR FOAMING SYSTEMS
CASE STUDY 16.7 ENLARGED DOWNCOMER
CLEARANCES MITIGATE FOAMING
CASE STUDY 16.8 HARDWARE CHANGES
DEBOTTLENECK FOAMING
17: The Tower as a Filter Part A. Causes of Plugging—Number 1 on the Top 10 Malfunctions
18: The Tower as a Filter Part B. Location of Plugging—Number 1 on the Top 10 Malfunctions
CASE STUDY 18.1 VALVE TRAYS IN STICKY CHEMICALS SERVICE AT HIGH RATES
CASE STUDY 18.2 FOULING BEHIND INTERRUPTER
BARS AND INLET WEIRS
CASE STUDY 18.3 EFFECT OF TRAY HOLE SIZE ON FOULING
CASE STUDY 18.4 VALVE STICKING: NUMEROUS
EXPERIENCES
CASE STUDY 18.5 PLUGGING INCIDENT: TRAYS Versus STRUCTURED PACKINGS
CASE STUDY 18.6 PLUGGING INCIDENT: PACKING Versus PACKING
CASE STUDY 18.7 PLUGGING IN A PACKED-TOWER
GAS INLET
CASE STUDY 18.8 OVERCOMING TOP-TRAY PLUGGING IN A CRUDE FRACTIONATOR
CASE STUDY 18.9 PARTIALLY PLUGGED KETTLE DRAW DOES NOT IMPAIR TOWER OPERATION
19: Coking Number 1 on the Top 10 Malfunctions
CASE STUDY 19.1 COKING IN A TALL, EFFICIENT WASH ZONE
CASE STUDY 19.2 TOO MANY STAGES LEAD TO WASH BED COKING
CASE STUDY 19.3 VACUUM TOWER COKING
CASE STUDY 19.4 COKING OF GRID IN FCC MAIN
FRACTIONATORS
CASE STUDY 19.5 COKING OF BAFFLE TRAYS
20: Leaks
CASE STUDY 20.1 TRACERS DIAGNOSE
LEAKING REBOILER
CASE STUDY 20.2 PREHEATER LEAK IDENTIFIED
FROM A SIMPLE FIELD TEST
CASE STUDY 20.3 SEVERAL LEAKS IN ONE HEAT
EXCHANGE SYSTEM
CASE STUDY 20.4 BOTTOM LEAK DISRUPTS FLOW
IN UPPER PUMPAROUND
21: Relief and Failure
22: Tray, Packing, and Tower Damage Part of Number 3 on the Top 10 Malfunctions
CASE STUDY 22.1 SHORT TRAY HOLDDOWN CLIPS UNABLE TO RESIST A PRESSURE SURGE
CASE STUDY 22.2 UPLIFTING OF POORLY FASTENED TRAYS
CASE STUDY 22.3 PACKING COLLAPSE DUE TO QUENCHING AND RAPID BOILING
CASE STUDY 22.4 RAPID PRESSURE FALL AT START-UP
CASE STUDY 22.5 TRAY UPLIFT DURING COMPRESSOR START-UP
CASE STUDY 22.6 INTERNAL DAMAGE DURING HOOK-UP OF VACUUM EQUIPMENT
CASE STUDY 22.7 VALVE POP-OUT: NUMEROUS
EXPERIENCES
CASE STUDY 22.8 VAPOR GAP DAMAGE
CASE STUDY 22.9 LOSS OF VACUUM
DAMAGES TRAYS
CASE STUDY 22.10 FOULING AND DAMAGE IN AN
EXTRACTIVE DISTILLATION ALDEHYDE COLUMN
CASE STUDY 22.11 TRAY DAMAGE BY GAS LIFTING
OF REFLUX DRUM LIQUID
CASE STUDY 22.12 TRAY DAMAGE AS A RESULT OF STEAMOUT FOLLOWED BY A WATER WASH
CASE STUDY 22.13 RAPID CONDENSING AT FEED ZONE DAMAGES TRAYS
CASE STUDY 22.14 PREVENTING WATER
STRIPPER DAMAGE
CASE STUDY 22.15 PREVENTING ANOTHER WATER
STRIPPER DAMAGE
CASE STUDY 22.16 BETRAYING MITIGATES
FLOW-INDUCED VIBRATIONS
23: Reboilers That Did Not Work Number 9 on the Top 10 Malfunctions
CASE STUDY 23.1 REBOILER SURGING
CASE STUDY 23.2 SEPARATION OF TWO LIQUID
PHASES IN A REBOILER
CASE STUDY 23.3 LEAKING DRAW TRAY MAKES
ONCE-THROUGH REBOILER START-UP DIFFICULT
CASE STUDY 23.4 LIQUID-STARVED
ONCE-THROUGH REBOILER
CASE STUDY 23.5 SURGING IN A EXTRACTIVE
DISTILLATION REBOILER SYSTEM
CASE STUDY 23.6 REBOILER FEED BLOCKAGE
CASE STUDY 23.7 THERMOSIPHON THAT WOULD
NOT THERMOSIPHON
CASE STUDY 23.8 ESTABLISHING THERMOSIPHON
ACTION IN A DEMETHANIZER REBOILER
CASE STUDY 23.9 FILM BOILING
CASE STUDY 23.10 LOSS OF CONDENSATE SEAL
IN A DEMETHANIZER REBOILER
CASE STUDY 23.11 PREVENTING LOSS
OF CONDENSATE SEAL
CASE STUDY 23.12 INABILITY TO REMOVE
CONDENSATE FROM REBOILER
24: Condensers That Did Not Work
CASE STUDY 24.1 PRESSURE AND LEVEL SURGING
CASE STUDY 24.2 INADEQUATE CONDENSATE
REMOVAL
CASE STUDY 24.3 NONCONDENSABLES CAN BOTTLENECK CONDENSERS AND TOWERS
CASE STUDY 24.4 ENTRAINMENT FROM C3 SPLITTER
KNOCKBACK CONDENSER
CASE STUDY 24.5 EXPERIENCE WITH A KNOCKBACK
CONDENSER WITH COOLING-WATER THROTTLING
25: Misleading Measurements Number 8 on the Top 10 Malfunctions
CASE STUDY 25.1 POOR STEAM EJECTOR
PERFORMANCE OR COLUMN VACUUM
MEASUREMENT ISSUE?
CASE STUDY 25.2 INCORRECT READINGS CAN
INDUCE UNNECESSARY SHUTDOWNS
CASE STUDY 25.3 CAN LYING PRESSURE
TRANSMITTERS BOTTLENECK TOWER CAPACITY?
CASE STUDY 25.4 MISSING BAFFLE AFFECTS LEVEL
TRANSMITTER
CASE STUDY 25.5 BOTTOM-LEVEL TRANSMITTER
FOOLED BY FROTH
CASE STUDY 25.6 BOTTOM-LEVEL TRANSMITTER
FOOLED BY LIGHT LIQUID
26: Control System Assembly Difficulties
CASE STUDY 26.1 C2 SPLITTER COMPOSITION
CONTROLS
CASE STUDY 26.2 CONTROLLING TEMPERATURE
AT BOTH ENDS OF A LEAN-OIL STILL
CASE STUDY 26.3 INVERSE RESPONSE
CASE STUDY 26.4 INVERSE RESPONSE WITH NO REFLUX DRUM
CASE STUDY 26.5 REBOILER SWELL
CASE STUDY 26.6 BASE BAFFLE INTERACTS WITH
HEAT INPUT CONTROL
CASE STUDY 26.7 GOOD REFLUX CONTROL MINIMIZES CRUDE TOWER OVERFLASH
CASE STUDY 26.8 VAPOR SIDEDRAW CONTROL
27: Where Do Temperature and Composition Controls Go Wrong
28: Misbehaved Pressure, Condenser, Reboiler, and Preheater Controls
CASE STUDY 28.1 LIQUID LEG INTERFERES WITH PRESSURE CONTROL
CASE STUDY 28.2 PRESSURE/ACCUMULATOR LEVEL
CONTROLS INTERFERENCE
CASE STUDY 28.3 EQUALIZING LINE MAKES OR
BREAKS FLOODED CONDENSER CONTROL
CASE STUDY 28.4 INERTS IN FLOODED
REFLUX DRUM
CASE STUDY 28.5 POOR HOOKUP OF HOT-VAPOR
BYPASS PIPES
CASE STUDY 28.6 PRESSURE CONTROL VALVE IN THE VAPOR LINE TO THE CONDENSER
CASE STUDY 28.7 CAN CONDENSER FOULING BY
COOLING-WATER THROTTLING BE BENEFICIAL?
CASE STUDY 28.8 CONTROL TO PREVENT FREEZING
IN CONDENSERS
CASE STUDY 28.9 VALVE IN REBOILER STEAM INDUCES OSCILLATIONS DURING START-UP
CASE STUDY 28.10 CONDENSATE DRUMS
ELIMINATE REBOILER START-UP OSCILLATIONS
29: Miscellaneous Control Problems
Distillation Troubleshooting Database of Published Case Histories
1: Troubleshooting Distillation Simulations
1.1 VLE
1.1.1 Close-Boiling Systems
1.1.2 Nonideal Systems
1.1.3 Nonideality Predicted in Ideal System
1.1.4 Nonideal VLE Extrapolated to Pure Products
1.1.5 Nonideal VLE Extrapolated to Differen t Pressures
1.1.7 Poor Characterization of Petroleum Fractions
1.1.6 Incorrect Accounting for Association Gives Wild Predictions
1.2 Chemistry, Process Sequence
1.3 Does Your Distillation Simulation Reflect the Real World?
1.3.1 General
1.3.2 With Second Liquid Phase
1.3.3 Refinery Vacuum Tower Wash Sections
1.3.4 Modeling Tower Feed
1.3.5 Simulation/Plant Data Mismatch Can Be Due to an Unexpected Internal Leak
1.3.6 Simulation/Plant Data Mismatch Can Be Due to Liquid Entrainment in Vapor Draw
1.3.7 Bug in Simulation
1.4 Graphical Techniques to Troubleshoot Simulations
1.5 How Good Is Your Efficiency Estimate?
1.6 Simulator Hydraulic Predictions: To Trust or Not to Trust
1.6.1 Do Your Vapor and Liquid Loadings Correctly Reflect Subcool, Superheat, and Pumparounds?
1.6.2 How Good Are the Simulation Hydraulic Prediction Correlations?
2: Where Fractionation Goes Wrong
2.1 Insufficient Reflux or Stages; Pinches
2.2 No Stripping in Stripper
2.3 Unique Features of Multicomponent Distillation
2.4 Accumulation and Hiccups
2.4.1 Intermediate Component, No Hiccups
2.4.2 Intermediate Component, with Hiccups
2.4.3 Lights Accumulation
2.4.4 Accumulation between Feed and Top or Feed and Bottom
2.4.5 Accumulation by Recycling
2.4.6 Hydrates, Freeze-Ups
2.5 Two Liquid Phases
2.6 Azeotropic and Extractive Distillation
3: Energy Savings and Thermal Effects
3.1 Energy-Saving Designs and Operation
3.1.1 Excess Preheat and Precool
3.1.2 Side-Reboiler Problems
3.1.3 Bypassing a Feed around the Tower
3.1.4 Reducing Recycle
3.1.5 Heat Integration Imbalances
3.2 Subcooling: How It Impacts Towers
3.2.1 Additional Internal Condensation and Reflux
3.2.2 Less Loadings above Feed
3.2.3 Trapping Lights and Quenching
3.2.4 Others
3.3 Superheat: How It Impacts Towers
4: Tower Sizing and Material Selection Affect Performance
4.1 Undersizing Trays and Downcomers
4.2 Oversizing Trays
4.3 Tray Details Can Bottleneck Towers
4.4 Low Liquid Loads Can Be Troublesome
4.5 Special Bubble-Cap Tray Problems
4.6 Misting
4.7 Undersizing Packings
4.8 Systems Where Packings Perform Different from Expectations
4.9 Packed Bed Too Long
4.10 Packing Supports Can Bottleneck Towers
4.11 Packing Hold-downs Are Sometimes Troublesome
4.12 Internals Unique to Packed Towers
4.13 Empty (Spray) Sections
5: Feed Entry Pitfalls in Tray Towers
5.1 Does the Feed Enter the Correct Tray?
5.2 Feed Pipes Obstructing Downcomer Entrance
5.3 Feed Flash Can Choke Downcomers
5.4 Subcooled Feeds, Refluxes Are Not Always Trouble Free
5.5 Liquid and Unsuitable Distributors Do Not Work with Flashing Feeds
5.6 Flashing Feeds Require More Space
5.7 Uneven or Restrictive Liquid Split to Multipass Trays at Feeds and Pass Transitions
5.8 Oversized Feed Pipes
5.9 Plugged Distributor Holes
5.10 Low Ä Ñ Trays Require Decent Distribution
6: Packed-Tower Liquid Distributors: Number 6 on the Top 10 Malfunctions
6.1 Better Quality Distributors Improve Performance
6.1.1 Original Distributor Orifice or Unspecified
6.1.2 Original Distributor Weir Type
6.1.3 Original Distributor Spray Type
6.2 Plugged Distributors Do Not Distribute Well
6.3 Overflow in Gravity Distributors: Death to Distribution
6.4 Feed Pipe Entry and Predistributor Problems
6.5 Poor Hashing Feed Entry Bottleneck Towers
6.6 Oversized Weep Holes Generate Undesirable Distribution
6.7 Damaged Distributors Do Not Distribute Well
6.8 Hole Pattern and Liquid Heads Determine Irrigation Quality
6.9 Gravity Distributors Are Meant to Be Level
6.10 Hold-Down Can Interfere with Distribution
6.11 Liquid Mixing Is Needed in Large-Diameter Distributors
6.12 Notched Distributors Have Unique Problems
6.13 Others
7: Vapor Maldistribution in ºÕ-ays and Packings
7.1 Vapor Feed/Reboiler Return Maldistributes Vapor to Packing Above
7.2 Experiences with Vapor Inlet Distribution Baffles
7.3 Packing Vapor Maldistribution at Intermediate Feeds and Chimney Trays
7.4 Vapor Maldistribution Is Detrimental in Tray Towers
8: Tower Base Level and Reboiler Return: Number 2 on the Top 10 Malfunctions
8.1 Causes of High Base Level
8.1.1 Faulty Level Measurement or Level Control
8.1.2 Operation
8.1.3 Excess Reboiler Pressure Drop
8.1.4 Undersized Bottom Draw Nozzle or Bottom Line
8.1.5 Others
8.2 High Base Level Causes Premature Tower Flood (No Tray/Packing Damage)
8.3 High Base Liquid Level Causes Tray/Packing Damage
8.4 Impingement by the Reboiler Return Inlet
8.5 Undersized Bottom Feed Line
8.6 Low Base Liquid Level
8.7 Issues with Tower Base Baffles
8.8 Vortexing
9: Chimney Tray Malfunctions: Part of Number 7 on the Top 10 Malfunctions
9.1 Leakage
9.2 Problem with Liquid Removal, Downcomers, or Overflows
9.3 Thermal Expansion Causing Warping, Out-of-Levelness
9.4 Chimneys Impeding Liquid Flow to Outlet
9.5 Vapor from Chimneys Interfering with Incoming Liquid
9.6 Level Measurement Problems
9.7 Coking, Fouling, Freezing
9.8 Other Chimney Tray Issues
10: Drawoff Malfunctions (Non-Chimney Tray): Part of Number 7 on the Top 10 Malfunctions
10.1 Vapor Chokes Liquid Draw Lines
10.2 Leak at Draw Tray Starves Draw
10.3 Draw Pans and Draw Lines Plug Up
10.4 Draw Tray Damage Affects Draw Rates
10.5 Undersized Side-Stripper Overhead Lines Restrict Draw Rates
10.6 Degassed Draw Pan Liquid Initiates Downcomer Backup Flood
10.7 Other Problems with Tower Liquid Draws
10.8 Liquid Entrainment in Vapor Side Draws
10.9 Reflux Drum Malfunctions
11: Tower Assembly Mishaps: Number 5 on the Top 10 Malfunctions
11.1 Incorrect Tray Assembly
11.2 Downcomer Clearance and Inlet Weir Malinstallation
11.3 Flow Passage Obstruction and Internals Misorientation at Tray Tower Feeds and Draws
11.4 Leaking Trays and Accumulator Trays
11.5 Bolts, Nuts, Clamps
11.6 Manways/Hatchways Left Unbolted
11.7 Materials of Construction Inferior to Those Specified
11.8 Debris Left in Tower or Piping
11.9 Packing Assembly Mishaps
11.9.1 Random
11.9.2 Structured
11.9.3 Grid
11.10 Fabrication and Installation Mishaps in Packing Distributors
11.11 Parts Not Fitting through Manholes
11.12 Auxiliary Heat Exchanger Fabrication and Assembly Mishaps
11.13 Auxiliary Piping Assembly Mishaps
12: Difficulties during Start-Up, Shutdown, Commissioning, and Abnormal Operation: Number 4 on the Top 10 Malfunctions
12.1 Blinding/Unblinding Lines
12.2 Backflow
12.3 Dead-Pocket Accumulation and Release of Trapped Materials
12.4 Purging
12.5 Pressuring and Depressuring
12.6 Washing
12.7 On-Line Washes
12.8 Steam and Water Operations
12.9 Overheating
12.10 Cooling
12.11 Overchilling
12.12 Water Removal
12.12.1 Draining at Low Points
12.12.2 Oil Circulation
12.12.3 Condensation of Steam Purges
12.12.4 Dehydration by Other Procedures
12.13 Start-Up and Initial Operation
12.13.1 Total-Reflux Operation
12.13.2 Adding Components That Smooth Start-Up
12.13.3 Siphoning
12.13.4 Pressure Control at Start-Up
12.14 Confined Space and Manhole Hazards
13: Water-Induced Pressure Surges: Part of Number 3 on the Top 10 Malfunctions
13.1 Water in Feed and Slop
13.2 Accumulated Water in Transfer Line to Tower and in Heater Passes
13.3 Water Accumulation in Dead Pockets
13.4 Water Pockets in Pump or Spare Pump Lines
13.5 Undrained Stripping Steam Lines
13.6 Condensed Steam or Refluxed Water Reaching Hot Section
13.7 Oil Entering Water-Filled Region
14: Explosions, Fires, and Chemical Releases: Number 10 on the Top 10 Malfunctions
14.1 Explosions Due to Decomposition Reactions
14.1.1 Ethylene Oxide Towers
14.1.2 Peroxide Towers
14.1.3 Nitro Compound Towers
14.1.4 Other Unstable-Chemical Towers
14.2 Explosions Due to Violent Reactions
14.3 Explosions and Fires Due to Line Fracture
14.4 Explosions Due to Trapped Hydrocarbon or Chemical Release
14.5 Explosions Induced by Commissioning Operations
14.6 Packing Fires
14.6.1 Initiated by Hot Work Above Steel Packing
14.6.2 Pyrophoric Deposits Played a Major Role, Steel Packing
14.6.3 Tower Manholes Opened While Packing Hot, Steel Packing
14.6.4 Others, Steel Packing Fires
14.6.5 Titanium, Zinconium Packing Fires
14.7 Fires Due to Opening Tower before Cooling or Combustible Removal
14.8 Fires Caused by Backflow
14.9 Fires by Other Causes
14.10 Chemical Releases by Backflow
14.11 Trapped Chemicals Released
14.12 Relief, Venting, Draining, Blowdown to Atmosphere
15: Undesired Reactions in Towers
15.1 Excessive Bottom Temperature/Pressure
15.2 Hot Spots
15.3 Concentration or Entry of Reactive Chemical
15.4 Chemicals from Commissioning
15.5 Catalyst Fines, Rust, Tower Materials Promote Reaction
15.6 Long Residence Times
15.7 Inhibitor Problems
15.8 Air Leaks Promote Tower Reactions
15.9 Impurity in Product Causes Reaction Downstream
16: Foaming
16.1 What Causes or Promotes Foaming?
16.1.1 Solids, Corrosion Products
16.1.2 Corrosion and Fouling Inhibitors, Additives, and Impurities
16.1.3 Hydrocarbon Condensation into Aqueous Solutions
16.1.4 Wrong Filter Elements
16.1.5 Rapid Pressure Reduction
16.1.6 Proximity to Solution Plait Point
16.2 What Are Foams Sensitive To?
16.2.1 Feedstock
16.2.2 Temperature
16.2.3 Pressure
16.3 Laboratory Tests
16.3.1 Sample Shake, Air Bubbling
16.3.2 Oldershaw Column
16.3.3 Foam Test Apparatus
16.3.4 At Plant Conditions
16.4 Antifoam Injection
16.4.1 Effective Only at the Correct Quantity/Concentration
16.4.2 Some Antifoams Are More Effective Than Others
16.4.3 Batch Injection Often Works, But Continuous Can Be Better
16.4.4 Correct Dispersal Is Important, Too
16.4.5 Antifoam Is Sometimes Adsorbed on Carbon Beds
16.4.6 Other Successful Antifoam Experiences
16.4.7 Sometimes Antifoam Is Less Effective
16.5 System Cleanup Mitigates Foaming
16.5.1 Improving Filtration
16.5.2 Carbon Beds Mitigate Foaming But Can Adsorb Antifoam
16.5.3 Removing Hydrocarbons from Aqueous Solvents
16.5.4 Changing Absorber Solvent
16.5.5 Other Contaminant Removal Techniques
16.6 Hardware Changes Can Debottleneck Foaming Towers
16.6.1 Larger Downcomers
16.6.2 Smaller Downcomer Backup (Lower Pressure Drop, Larger Clearances)
16.6.3 More Tray Spacing
16.6.4 Removing Top Two Trays Does Not Help
16.6.5 Trays Versus Packings
16.6.6 Larger Packings, High-Open-Area Distributors Help
16.6.7 Increased Agitation
16.6.8 Larger Tower
16.6.9 Reducing Base Level
17: The Tower as a Filter: Part A. Causes of Plugging—Number 1 on the Top 10 Malfunctions
17.1 Piping Scale/Corrosion Products
17.2 Salting Out/Precipitation
17.3 Polymer/Reaction Products
17.4 Solids/Entrainment in the Feed
17.5 Oil Leak
17.6 Poor Shutdown Wash/Flush
17.7 Entrainment or Drying at Low Liquid Rates
17.8 Others
18: The Tower as a Filter: Part B. Locations of Plugging—Number 1 on the Top 10 Malfunctions
18.1 Trays
18.2 Downcomers
18.3 Packings
18.4 How Packings and Trays Compare on Plugging Resistance
18.4.1 Trays versus Trays
18.4.2 Trays versus Packings
18.4.3 Packings versus Packings
18.5 Limited Zone Only
18.6 Draw, Exchanger, and Vent Lines
18.7 Feed and Inlet Lines
18.8 Instrument Lines
19: Coking: Part of Number 1 on Tower Top 10 Malfunctions
19.1 Insufficient Wash Flow Rate, Refinery Vacuum Towers
19.2 Other Causes, Refinery Vacuum Towers
19.3 Slurry Section, FCC Fractionators
19.4 Other Refinery Fractionators
19.5 Nonrefinery Fractionators
20: Leaks
21: Relief and Failure
21.1 Relief Requirements
21.2 Controls That Affect Relief Requirements and Frequency
21.3 Relief Causes Tower Damage, Shifts Deposits
21.4 Overpressure Due to Component Entry
21.5 Relief Protection Absent or Inadequate
21.6 Line Ruptures
21.7 All Indication Lost When Instrument Tap Plugged
21.8 Trips Not Activating or Incorrectly Set
21.9 Pump Failure
21.10 Loss of Vacuum
21.11 Power Loss
22: Tray, Packing, and Tower Damage: Part of Number 3 on the Top 10 Malfunctions
22.1 Vacuum
22.2 Insufficient Uplift Resistance
22.3 Uplift Due to Poor Tightening during Assembly
22.4 Uplift Due to Rapid Upward Gas Surge
22.5 Valves Popping Out
22.6 Downward Force on Trays
22.7 Trays below Feed Bent Up, above Bent Down and Vice Versa
22.8 Downcomers Compressed, Bowed, Fallen
22.9 Uplift of Cartridge Trays
22.10 Flow-Induced Vibrations
22.11 Compressor Surge
22.12 Packing Carryover
22.13 Melting, Breakage of Plastic Packing
22.14 Damage to Ceramic Packing
22.15 Damage to Other Packings
23: Reboilers That Did Not Work: Number 9 on the Top 10 Malfunctions
23.1 Circulating Thermosiphon Reboilers
23.1.1 Excess Circulation
23.1.2 Insufficient Circulation
23.1.3 Insufficient Ä Ô, Pinching
23.1.4 Surging
23.1.5 Velocities Too Low in Vertical Thermosiphons
23.1.6 Problems Unique to Horizontal Thermosiphons
23.2 Once-Through Thermosiphon Reboilers
23.2.1 Leaking Draw Tray or Draw Pan
23.2.2 No Vaporization/Thermosiphon
23.2.3 Slug Flow in Outlet Line
23.3 Forced-Circulation Reboilers
23.4 Kettle Reboilers
23.4.1 Excess Ä Ñ in Circuit
23.4.2 Poor Liquid Spread
23.4.3 Liquid Level above Overflow Baffle
23.5 Internal Reboilers
23.6 Kettle and Thermosiphon Reboilers in Series
23.7 Side Reboilers
23.8 All Reboilers, Boiling Side
23.9 All Reboilers, Condensing Side
23.9.1 Non condensables in Heating Medium
23.9.2 Loss of Condensate Seal
23.9.3 Condensate Draining Problems
23.9.4 Vapor/Steam Supply Bottleneck
24: Condensers That Did Not Work
24.1 Inerts Blanketing
24.2 Inadequate Condensate Removal
24.3 Unexpected Condensation Heat Curve
24.4 Problems with Condenser Hardware
24.5 Maldistribution between Parallel Condensers
24.6 Flooding/Entrainment in Partial Condensers
24.7 Interaction with Vacuum and Recompression Equipment
24.8 Others
25: Misleading Measurements: Number 8 on the Top 10 Malfunctions
25.1 Incorrect Readings
25.2 Meter or Taps Fouled or Plugged
25.3 Missing Meter
25.4 Incorrect Meter Location
25.5 Problems with Meter and Meter Tubing Installation
25.6 Incorrect Meter Calibration, Meter Factor
25.7 Level Instrument Fooled
25.7.1 By Froth or Foam
25.7.2 By Oil Accumulation above Aqueous Level
25.7.3 By Lights
25.7.4 By Radioactivity (Nucleonic Meter)
25.7.5 Interface-Level Metering Problems
25.8 Meter Readings Ignored
25.9 Electric Storm Causes Signal Failure
26: Control System Assembly Difficulties
26.1 No Material Balance Control
26.2 Controlling Two Temperatures/Compositions Simultaneously Produces Interaction
26.3 Problems with the Common Control Schemes, No Side Draws
26.3.1 Boil-Up on TC/AC, Reflux on FC
26.3.2 Boil-Up on FC, Reflux on TC/AC
26.3.3 Boil-Up on FC, Reflux on LC
26.3.4 Boil-Up on LC, Bottoms on TC/AC
26.3.5 Reflux on Base LC, Bottoms on TC/AC
26.4 Problems with Side-Draw Controls
26.4.1 Small Reflux below Liquid Draw Should Not Be on Level or Difference Control
26.4.2 Incomplete Material Balance Control with Liquid Draw
26.4.3 Steam Spikes with Liquid Draw
26.4.4 Internal Vapor Control makes or Breaks Vapor Draw Control
26.4.5 Others
27: Where Do Temperature and Composition Controls Go Wrong?
28: Misbehaved Pressure, Condenser, Reboiler, and Preheater Controls
28.1 Pressure Controls by Vapor Flow Variations
28.2 Flooded Condenser Pressure Controls
28.3 Coolant Throttling Pressure Controls
28.3.1 Cooling-Water Throttling
28.3.2 Manipulating Airflow
28.3.3 Steam Generator Overhead Condenser
28.3.3 Steam Generator Overhead Condenser
28.4 Pressure Control Signal
28.5 Throttling Steam/Vapor to Reboiler or Preheater
28.6 Throttling Condensate from Reboiler
28.7 Preheater Controls
29: Miscellaneous Control Problems
29.1 Interaction with the Process
29.2 AP Control
29.3 Flood Controls and Indicators
29.4 Batch Distillation Control
29.5 Problems in the Control Engineer's Domain
29.6 Advanced Controls Problems
29.6.1 Updating Multivariable Controls
29.6.2 Advanced Controls Fooled by Bad Measurements
29.6.3 Issues with Model Inaccuracies
29.6.4 Effect of Power Dips
29.6.5 Experiences with Composition Predictors in Multivariable Controls
References
Index
About the Author
TrUe LiAr