TL;DR
Column flooding causes purity loss and pressure drop spike. Reduce vapor or liquid rate to below the flood point, then diagnose the root cause.
What you might see
- column differential pressure rising sharply
- overhead product purity dropping
- bottoms product contaminated with lights
- liquid backup visible in downcomer
Likely causes
Vapor rate above the design flood point for the installed packing or tray
Liquid rate above downcomer capacity causing backup and weeping
Feed composition changed causing increased internal vapor/liquid ratio
Packing fouled with solids reducing open area and increasing resistance
Required tools
- Differential pressure recorder or transmitter log
- Process sample bottles
- Lab GC or analyzer
Safety first
- Distillation columns processing pharma intermediates or solvents operate under pressure and contain flammable or toxic materials. Do not enter the column without a vessel entry permit and gas detection.
- Pressure relief devices on the column must be functional before reducing reboiler duty. Do not bypass or block the relief path.
- Hot process fluids are present. Wear appropriate chemical and thermal PPE during sampling.
Procedure
- 1
Log the column differential pressure and compare to the normal operating range.[1]
- 2
Reduce the reboiler duty or the feed rate by 10 to 15 percent. Watch for differential pressure to decrease.[1]
- 3
Sample the overhead and bottoms products to confirm the purity impact.
- 4
Check the feed composition against the design basis. An off-spec feed with excess lights can increase internal vapor load.
- 5
Review the reflux ratio against the design value. High reflux increases liquid load and can push the column past the downcomer capacity.
- 6
If the column continues to flood after reducing rates, plan an inspection during the next shutdown for packing fouling or damage.
- 7
Document the flood point operating conditions for comparison against previous stable operation. This establishes whether capacity has degraded.
Sources
Koch-Glitsch (internals) Koch-Glitsch FLEXIPAC / IMTP / Provalve Distillation Column general technical documentation, Koch-Glitsch (internals)
Koch-Glitsch FLEXIPAC / IMTP / Provalve distillation column general flooding and capacity procedures (general)
More guides for Koch-Glitsch (internals) Koch-Glitsch FLEXIPAC / IMTP / Provalve
How to diagnose packing fouling on a Koch-Glitsch FLEXIPAC / IMTP distillation column
A slow rise in differential pressure over months indicates packing fouling. Track the trend, plan an inspection at the next turnaround, and consider a column wash before opening.
How to diagnose valve tray weeping on a Koch-Glitsch Provalve distillation column
Tray weeping happens when vapor flow is too low to prevent liquid from draining through the tray. Increase vapor load or inspect for damaged valve caps at the next shutdown.
Stop fixing the same fault twice.
Dovient turns guides like this into your team's shared playbook, with AI that catches recurring issues before they break the line.