How to Retrofit a Packed Tower When Operating Temperature Increases

A rise in tower operating temperature can appear less dramatic than a major change in chemistry or production rate.

However, higher temperature can affect nearly every part of an existing packed tower.

It can change:

• gas volume;
• material strength;
• corrosion rate;
• polymer stability;
• liquid properties;
• process equilibrium.

A tower that was reliable at the original temperature may therefore require substantial internal review after a process-temperature increase.

Confirm Normal and Maximum Temperature

Do not evaluate only the new normal operating temperature.

Determine:

• normal temperature;
• startup temperature;
• shutdown temperature;
• short-term excursions;
• cleaning temperature;
• steam exposure if applicable.

Many materials fail because of occasional temperature peaks rather than continuous normal operation.

Recheck Plastic Components First

Plastic packing and internals deserve particular attention.

Depending on polymer type, higher temperature may reduce:

• stiffness;
• mechanical strength;
• dimensional stability;
• service life.

Possible components include:

• random packing;
• support grids;
• distributors;
• demister components;
• piping.

A plastic material that is chemically compatible may still be unsuitable thermally.

Check Thermal Deformation

Higher temperature can allow plastic internals to creep or distort under load.

This matters particularly for:

• deep packed beds;
• large distributor spans;
• support grids;
• hold-down devices.

Long-term service temperature should be considered rather than only short-duration material data.

Re-evaluate Corrosion

Corrosion rate often changes with temperature.

A metal that performed adequately at the original condition may corrode much faster at the new temperature.

Material review should include actual:

• chemistry;
• concentration;
• contaminants;
• temperature.

Temperature and chemical compatibility cannot be assessed separately.

Recalculate Gas Volume

At higher temperature, gas density may decrease and actual volumetric gas flow may increase.

For the same mass flow, this can increase superficial velocity.

Possible consequences include:

• higher pressure drop;
• lower flooding margin;
• increased entrainment.

Hydraulic recalculation may therefore be required even if production rate does not change.

Check Liquid Properties

Temperature changes can alter:

• viscosity;
• density;
• surface tension.

These properties influence packing wetting, pressure drop, and mass transfer.

The old hydraulic design should not automatically be reused.

Review Process Performance

Higher temperature may change absorption equilibrium or separation efficiency.

For some absorption systems, increased temperature can reduce solubility.

The tower may therefore require more effective mass-transfer area or different operating conditions.

A purely mechanical material upgrade may not solve the new process limitation.

Inspect Expansion and Support Arrangements

Metal and plastic components expand differently with temperature.

A retrofit introducing new materials should consider thermal expansion.

Rigid attachment of components with significantly different thermal behavior can create stress or distortion.

Review Cleaning Procedures

If higher-temperature operation also leads to different cleaning methods, confirm that all replacement materials are compatible.

For example, plastic internals selected for process temperature may still be unsuitable for high-temperature steam cleaning.

Decide Whether a Material Conversion Is Needed

Possible retrofit paths may include:

• one polymer to another;
• plastic to metal;
• metal alloy upgrade;
• ceramic packing.

The correct choice depends on both temperature and process chemistry.

No material should be selected on temperature resistance alone.

Check the Whole Internal Material Chain

A common mistake is to upgrade the packing while leaving older temperature-sensitive components in place.

The weakest remaining component may then become the next failure point.

Review all wetted internals and supporting parts.