TL;DR

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.

What you might see

differential pressure trend increasing over months
separation efficiency declining
solids observed in bottoms product
increased reboiler duty needed to hold product spec

Likely causes

Tap to mark as ruled out

Solid precipitation from process chemistry depositing on packing surface
Polymerization of reactive feed components coating the packing
Corrosion products from column internals or overhead system washing down
Operator error allowing non-volatile feed component above design rate

Required tools

Process trend historian access
Lab solids analysis capability
Differential pressure transmitter calibration kit

Safety first

Column internals in pharma service contain hazardous process materials. Any column entry requires a confined space permit, atmospheric testing, and supplied air or SCBA.
Hot wash or solvent flush procedures must be reviewed against the column pressure rating and relief valve setting before starting.
Disposed packing material from a fouled column may be classified as hazardous waste. Segregate and label per site procedures.

Procedure

7 steps · ~30 min

1
Pull the differential pressure trend for the last 3 to 6 months. A steady upward trend confirms fouling rather than a transient event.[1]
2
Review feed analysis records for periods of elevated solids or reactive components.
3
Check overhead condenser and reboiler heat transfer efficiency trends. Fouling in the column often correlates with exchanger fouling.[1]
4
Assess whether a hot wash or solvent flush can be performed in-line to reduce fouling before a full turnaround.
5
If in-line wash is appropriate, circulate an approved solvent through the column while monitoring differential pressure.
6
Add the column to the next turnaround scope for internal inspection, packing removal, and cleaning or replacement.
7
Document the fouling history and the suspected chemical cause for the turnaround team.

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 packing fouling and inspection procedures (general)

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