How Do Engineers Evaluate Existing Tower Internals Before a Revamp Project?
Before starting a packed tower revamp project, engineers must determine whether the existing tower internals can continue to operate safely and meet the new performance requirements.
Replacing packing alone is not always enough.
Existing internals may affect:
- Hydraulic performance
- Liquid distribution
- Mechanical reliability
- Installation feasibility
- Long-term operation
A proper evaluation helps engineers decide whether to:
- Reuse existing internals
- Repair specific components
- Replace selected internals
- Upgrade the complete internal system
Why Is Existing Tower Internal Evaluation Important?
A packed tower works as an integrated system.
The performance depends on the interaction between:
- Packing
- Liquid distributor
- Redistributor
- Support grid
- Hold-down grid
- Mist eliminator
During a revamp project, the original tower design may no longer match:
- New production targets
- Changed process conditions
- Higher capacity requirements
Existing internals that were acceptable years ago may become the limiting factor.
What Tower Internals Should Engineers Evaluate?
1. Liquid Distributor Condition
The liquid distributor is one of the most important components affecting packing performance.
Engineers evaluate:
- Corrosion condition
- Blockage of openings
- Mechanical deformation
- Levelness
- Distribution capability
Possible problems:
- Uneven liquid distribution
- Dry packing areas
- Channeling
2. Liquid Redistributor Condition
For towers with multiple packing sections, engineers should evaluate redistributors.
Important checks include:
- Liquid collection capability
- Redistribution performance
- Structural condition
- Fouling or blockage
A damaged redistributor may reduce the performance of the lower packing section.
3. Packing Support Grid Condition
The support grid must safely carry the packed bed load.
Engineers check:
- Corrosion
- Structural strength
- Deformation
- Open area condition
Possible issues:
- Reduced load capacity
- Restricted gas/liquid flow
- Packing instability
4. Hold-Down Grid Condition
The hold-down grid helps maintain packing stability.
Engineers evaluate:
- Mechanical integrity
- Fixing condition
- Corrosion
- Compatibility with existing packing
Problems may cause:
- Packing movement
- Uneven packing arrangement
- Operation instability
5. Mist Eliminator Condition
For towers equipped with mist eliminators, engineers evaluate:
- Fouling
- Corrosion
- Structural damage
- Separation capability
A damaged mist eliminator may cause:
- Liquid carryover
- Downstream contamination
- Increased maintenance
What Factors Influence Whether Internals Can Be Reused?
1. Mechanical Condition
Engineers check:
- Remaining thickness
- Corrosion level
- Structural strength
- Damage history
A component may look acceptable but still have insufficient remaining service life.
2. Compatibility With New Packing
A new packing selection may require different internal conditions.
Engineers should confirm:
- Support capacity
- Opening area
- Distribution requirements
- Bed arrangement
3. New Operating Conditions
Revamp projects often change operating requirements.
Examples:
- Higher gas flow
- Higher liquid circulation
- Increased capacity
- Different process chemicals
Existing internals may not support the new conditions.
4. Performance Requirements
Engineers should evaluate:
- Required efficiency
- Required capacity
- Pressure drop limitation
The decision should be based on the future target, not only current condition.
How Do Engineers Evaluate Existing Internals During a Revamp?
Step 1: Review Original Design Documents
Important documents include:
- Tower drawings
- Internal drawings
- Original specifications
- Previous modification records
Step 2: Review Operating History
Engineers analyze:
- Previous performance
- Pressure drop changes
- Maintenance records
- Operating problems
Step 3: Perform Internal Inspection
Inspection may include:
- Visual examination
- Corrosion check
- Fouling assessment
- Mechanical condition review
Step 4: Compare With New Requirements
Engineers determine:
- Can existing internals handle the new duty?
- Are modifications required?
- Which components should be replaced?
When Should Existing Internals Be Replaced?
1. Severe Corrosion or Damage
Replacement is usually considered when:
- Structural strength is reduced
- Reliability cannot be guaranteed
2. Performance Limitation
Examples:
- Poor liquid distribution
- Insufficient capacity
- Excessive pressure drop
3. New Packing Requires Different Internals
A new packing upgrade may require:
- Different support design
- Improved distributor
- Additional redistribution
4. Future Expansion Requirements
If the plant expects:
- Higher production
- More demanding operation
a complete internal upgrade may provide better long-term value.
Common Mistakes During Internal Evaluation
Assuming Old Internals Can Always Be Reused
Age alone is not the only factor.
Engineers must consider:
- Condition
- Performance
- Future requirements
Checking Only Packing Condition
Packing is only one part of the tower system.
Internals often determine whether new packing can perform properly.
Ignoring Installation Limitations
Replacement design must consider:
- Manway size
- Segment dimensions
- Assembly method
Evaluating Components Separately
Tower internals work together.
A distributor, packing, support system, and mist eliminator should be evaluated as one system.
What Information Is Needed for Existing Internal Evaluation?
Engineers should provide:
Tower Information
- Tower diameter
- Tower drawings
- Internal arrangement
- Manway dimensions
Operating Information
- Gas flow rate
- Liquid flow rate
- Temperature
- Pressure
- Process fluid information
Performance Information
- Current problems
- Historical operation
- Pressure drop changes
- Efficiency changes
Project Requirements
- New capacity target
- Required efficiency
- Shutdown schedule
- Material requirements
How DAIER Supports Tower Revamp Evaluation
DAIER provides engineering support for packed tower upgrades including:
- Packing replacement
- Liquid Distributor evaluation
- Redistributor replacement
- Support Grid replacement
- Hold-down Grid replacement
- Mist Eliminator upgrade
- Complete Tower Internals solutions
For revamp projects, engineers can provide:
- Existing tower information
- Internal drawings
- Operating problems
- Performance targets
DAIER can support evaluation and customized fabrication based on actual tower conditions.
Specs and test data available upon request.