Distillation is one of the widely used separation method in most of the Chemical Process Industries. Improper design/ operation & maintenance leads to various troubles like reduced plant capacity, poor quality of separated products, high energy consumption, etc. This presentation is for learning about the troubleshooting of packed type distillation systems. Through conceptual aspects of the overall distillation system, reader can easily identify the various causes of probable troubles and will be able to suggest their remedial measures.
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Troubleshooting of
Distillation Column
(Packed Type)
Enhancing Visualization
Trouble may be due to
d.) Poor Erection
o Column Perpendicularity
o Liquid Distributor Leveling
o Condensor Elevation
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Troubleshooting of
Distillation Column
(Packed Type)
Enhancing Visualization
Trouble may be due to
e.) Careless Pre-commissioning Checks
o Debris left in column
o Glass in SG/LG Missing
o Wrong Direction of Rotameter
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Troubleshooting of
Distillation Column
(Packed Type)
Enhancing Visualization
Trouble may be due to
f.) Inexperienced Startup
o Fast Initial Heating
o No cooling water in condensor
o Higher feed rate at the start
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Troubleshooting of
Distillation Column
(Packed Type)
Enhancing Visualization
Trouble may be due to
g.) Casual Normal Operation
o High reflux ratio (than specified)
o Low feed temperature
o Sub-cooled reflux
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Troubleshooting of
Distillation Column
(Packed Type)
Enhancing Visualization
Trouble may be due to
h.) Careless Maintenance
o Damaging column packing
o Changed gasket material
o Relocating instrument
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Troubleshooting of
Distillation Column
(Packed Type)
Enhancing Visualization
Know About Distillation
Here the Imperfection Starts (Man Made) which leads to Trouble
Third (Plant) Provision
Space like Packing for Heat & Mass Transfer
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Troubleshooting of
Distillation Column
(Packed Type)
Enhancing Visualization
Know About Packed Bed Column
a.) Cylindrical Vertical Vessel with Nozzles, Manholes, etc.
Atmospheric
Pressure
Vacuum
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Troubleshooting of
Distillation Column
(Packed Type)
Enhancing Visualization
Know About Packed Bed Column
b.) Packing
To provide space for Liquid/ Vapor direct contact
Simultaneous Heat & Mass Transfer
More Contact & Less Pressure Drop
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Troubleshooting of
Distillation Column
(Packed Type)
Enhancing Visualization
Know About Packed Bed Column
b.) Packing
First Generation (Raschig Ring, Berl Saddle)
1895 to the 1950s
simple shapes with closed surfaces, robust
and stable design, cost-effective production
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Troubleshooting of
Distillation Column
(Packed Type)
Enhancing Visualization
Know About Packed Bed Column
b.) Packing Second Generation (Pall Ring, Intalox Saddle)
late 1950s to the early 1970s
surfaces with cutted windows and bent tongues,
improved area distribution lowering pressure
drop and enhancing capacity
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Troubleshooting of
Distillation Column
(Packed Type)
Enhancing Visualization
Know About Packed Bed Column
b.) Packing
Third Generation (Net/Grid Structures, IMPT Ring)
late 1970s to the 1990s
framework structure, large free cross section,
low pressure drop, high efficiency
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Troubleshooting of
Distillation Column
(Packed Type)
Enhancing Visualization
Know About Packed Bed Column
b.) Packing Fourth Generation (Raschig Super-Ring)
late 1990s until present
lower pressure drop and better mass transfer
efficiency
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Troubleshooting of
Distillation Column
(Packed Type)
Enhancing Visualization
Know About Packed Bed Column
d.) Liquid Distributor
1. Gravitational Types
i. Orifice Type
ii. Weir Type
2. Pressure Drop Types
i. Spray Nozzle Type
ii. Perforated Pipe Type
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Troubleshooting of
Distillation Column
(Packed Type)
Enhancing Visualization
Know Distillation System
Feed Preheater
Reboiler
Distillation
Column
Bottom Product
Cooler
Top Product
Cooler
Condenser
A + B
A
B
Steam
Steam
Cooling Water
Cooling
Water
Cooling
Water
Feed
Top Vapors
Reflux
Top
Product
Bottom
Product
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Troubleshooting of
Distillation Column
(Packed Type)
Enhancing Visualization
Know Distillation System
Feed Preheater
Reboiler
Distillation
Column
Bottom Product
Cooler
Top Product
Cooler
Condenser
A + B
A
B
Steam
Steam
Cooling Water
Cooling
Water
Cooling
Water
Feed
Top Vapors
Reflux
Top
Product
Bottom
Product
a.) Feeding
• Gravity/ Pump
• Pre-heating
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Troubleshooting of
Distillation Column
(Packed Type)
Enhancing Visualization
Know Distillation System
Feed Preheater
Reboiler
Distillation
Column
Bottom Product
Cooler
Top Product
Cooler
Condenser
A + B
A
B
Steam
Steam
Cooling Water
Cooling
Water
Cooling
Water
Feed
Top Vapors
Reflux
Top
Product
Bottom
Product
b.) Vapor Condensation/ Reflux
• Condensor – Horizontal/Vertical
• Partial vs. Total Condensation
• Reflux – Gravity / Pump
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Troubleshooting of
Distillation Column
(Packed Type)
Enhancing Visualization
Know Distillation System
Feed Preheater
Reboiler
Distillation
Column
Bottom Product
Cooler
Top Product
Cooler
Condenser
A + B
A
B
Steam
Steam
Cooling Water
Cooling
Water
Cooling
Water
Feed
Top Vapors
Reflux
Top
Product
Bottom
Product
c.) Heat Supply
• Direct / Indirect
• Reboiler – Thermosiphon, Forced, Kettle
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Troubleshooting of
Distillation Column
(Packed Type)
Enhancing Visualization
Design of Distillation (Packed Column)
a.) Height of Packing
Theoretical Stages x HETP
Based on Feed Condition & Reflux Ratio
Based on Packing Type
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Troubleshooting of
Distillation Column
(Packed Type)
Enhancing Visualization
Design of Distillation (Packed Column)
b.) Material & Energy Balance
Overall Material Balance
A=10 t
B=90 t
T =100 t
A=9.99 t
B=0.01 t
T=10 t
A=0.01 t
B=99.99 t
T=90 t
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Troubleshooting of
Distillation Column
(Packed Type)
Enhancing Visualization
Design of Distillation (Packed Column)
b.) Material & Energy Balance
At Reflux Ratio = 4
Reflux Flow = 40 t
Vapor Flow = 50 t
A=10 t
B=90 t
T =100 t
A=9.99 t
B=0.01 t
T=10 t
A=0.01 t
B=99.99 t
T=90 t
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Troubleshooting of
Distillation Column
(Packed Type)
Enhancing Visualization
Design of Distillation (Packed Column)
b.) Material & Energy Balance
Energy Balance
•for Condensor Load
•for Reboiler Load
A=10 t
B=90 t
T =100 t
A=9.99 t
B=0.01 t
T=10 t
A=0.01 t
B=99.99 t
T=90 t
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Troubleshooting of
Distillation Column
(Packed Type)
Enhancing Visualization
Design of Distillation (Packed Column)
c.) Column Diameter
Tower Area = Vapor Mass Rate / Vapor Mass Velocity
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Troubleshooting of
Distillation Column
(Packed Type)
Enhancing Visualization
Variation Analysis (in Designed Column)
A.) Feed
a.) Feed Flow Rate
a.1) Expected = 100 TPH Actual = 50 TPH
a.2) Expected = 100 TPH Actual = 150 TPH
Vapor / Liquid Load
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Troubleshooting of
Distillation Column
(Packed Type)
Enhancing Visualization
Variation Analysis (in Designed Column)
A.) Feed
b.) Feed Composition
b.1) Expected : 10% w/w ‘A’ Actual : 5 % w/w ‘A’
b.2) Expected : 10% w/w ‘A’ Actual : 20 % w/w ‘A’
Change of Feed Nozzle
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Troubleshooting of
Distillation Column
(Packed Type)
Enhancing Visualization
Variation Analysis (in Designed Column)
A.) Feed
c.) Feed Temperature/ Condition
c.1) Expected : 900C Liquid Actual : 600C Liquid
c.2) Expected : 900C Liquid Actual : 900C Vapor
Heat Load to Reboiler
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Troubleshooting of
Distillation Column
(Packed Type)
Enhancing Visualization
Variation Analysis (in Designed Column)
B.) Reflux
a.) Flow Rate
a.1) Expected : 50 TPH Actual : 25 TPH
a.2) Expected : 50 TPH Actual : 100 TPH
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Troubleshooting of
Distillation Column
(Packed Type)
Enhancing Visualization
Variation Analysis (in Designed Column)
C.) Steam in Reboiler
a.) Flow Rate
b.) Pressure
c.) Quality : Dry, Wet, Superheated
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Troubleshooting of
Distillation Column
(Packed Type)
Enhancing Visualization
Trouble Identification
a.) By Operating Parameter Study
Pressure, Temperature, Composition at different locations
Bottom Pressure Expected : 2.5 kg/cm2(g) Actual : 2.6 kg/cm2(g)
Bottom Temperature Expected : 105oC Actual : 104oC
Bottom Composition Expected : 0.01%w/w ‘A’ Actual : 0.1%w/w ‘A’
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Troubleshooting of
Distillation Column
(Packed Type)
Enhancing Visualization
Trouble Identification
b.) By Visual Inspection
During Operation : Flooding through SG/LG
On Column Opening : Choked Liquid Distributor
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Troubleshooting of
Distillation Column
(Packed Type)
Enhancing Visualization
Trouble Identification
c.) By Advanced Tools
•Simulation Models
•Gamma Scanning
•X-Ray Analysis
•Video Camera
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Troubleshooting of
Distillation Column
(Packed Type)
Enhancing Visualization
Troubles within Column
b.) Hardware Specific
•Packing : Size, Type, Broken/Damaged Packing
•Liquid Distributor : Choked holes, Tilted, Under/Over sized
•Vapor Supply : Sheath
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Troubleshooting of
Distillation Column
(Packed Type)
Enhancing Visualization
Other Hardware Affecting Distillation
a.) Equipment other than Distillation Column
a.1) Heat Exchanger
•Feed Pre-heater
•Condensor
•Reboiler
•Coolers
•Heat Transfer Area – Less / More
•Orientation – Horizontal / Vertical
•Location - Elevation
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Troubleshooting of
Distillation Column
(Packed Type)
Enhancing Visualization
Other Hardware Affecting Distillation
a.) Equipment other than Distillation Column
a.2) Pump
•Feed Pump
•Reflux Pump
•Product Draw Pump
•Flow Rate vs. Head
•NPSH (Required) vs. NPSH (Available)
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Troubleshooting of
Distillation Column
(Packed Type)
Enhancing Visualization
Other Hardware Affecting Distillation
b.) Pipe Line
•Reflux Line with Loop
•Thermo-siphon Reboiler Piping
•Utility Piping – Steam, Cooling Water
•Vacuum Line
•Pump Suction Line
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Troubleshooting of
Distillation Column
(Packed Type)
Enhancing Visualization
Other Hardware Affecting Distillation
c.) Instrument
•Wrong Calibration
•Control Valve Operation
•Wrong Placement/Installation
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