Standard or Custom? How to Define Tower Internals for an Early-Stage Wet Scrubber Project

Many wet-scrubber inquiries begin with a simple request:

“Please recommend your standard configuration.”

The buyer may want standard random packing, a standard demister, a support grid, and a liquid distributor.

This sounds straightforward.

But tower internals do not all have the same level of standardization.

Understanding which components can be selected from standard product ranges and which require tower-specific dimensions prevents both overengineering and inaccurate quotations.

Random Packing Is Highly Standardized

Random packing is usually the easiest component to quote from a standard range.

Typical selectable parameters include:

• geometry;
• material;
• nominal size.

For many corrosive scrubbers, the supplier may offer standard sizes of PP or other plastic packing.

Once the required packing volume is known, the product itself may require little customization.

Mist Eliminator Material May Be Standard, but Diameter Usually Is Not

Wire mesh demister material can be based on standard mesh configurations.

However, the final demister assembly normally depends on:

• tower diameter;
• gas velocity;
• support structure;
• manway size;
• segmentation requirements.

Therefore, the media may be standard while the finished assembly is project-specific.

Support Grids Are Usually Tower-Specific

A packing support must fit the actual column.

The required design depends on:

• vessel diameter;
• packing load;
• liquid holdup;
• material;
• support ring;
• beam arrangement;
• required open area.

A supplier may have standard design concepts, but the finished support grid is rarely a universal catalogue item.

Liquid Distributors Are Even More Process-Dependent

A distributor must match:

• tower diameter;
• liquid rate;
• turndown;
• feed arrangement;
• process chemistry;
• fouling tendency.

A “standard PP distributor” may describe the material and general construction style.

It does not mean that one distributor fits every scrubber.

Why Buyers Ask for Standard Configurations

Early-stage projects often do not yet have final dimensions.

The buyer may be:

• comparing suppliers;
• preparing a budget;
• evaluating possible technology;
• developing a preliminary equipment layout.

At this stage, requesting detailed custom engineering may be unnecessary.

The supplier should therefore provide useful information without pretending the design is final.

A Two-Level Recommendation Works Well

Preliminary standard recommendation

The supplier may provide:

• common packing types;
• standard packing sizes;
• available materials;
• typical demister styles;
• common support-grid concepts;
• common distributor designs.

This helps the buyer understand the available system.

Project-specific final design

Once the buyer provides:

• tower diameter;
• gas flow;
• liquid flow;
• temperature;
• chemistry;
• manway;
• required performance;

the final internal dimensions can be engineered.

Avoid Giving False Standard Dimensions

One common mistake is to provide exact distributor or demister dimensions before the vessel diameter is confirmed.

This may create the impression that the product can be ordered directly.

A more accurate statement is:

“Standard design concept; final diameter and segmentation according to tower dimensions.”

That keeps the preliminary quotation useful without creating technical ambiguity.

Standardization Still Has Commercial Value

Using standard materials and proven configurations can reduce:

• engineering time;
• manufacturing complexity;
• tooling requirements;
• project risk.

A project does not need to be completely custom simply because some final dimensions are tower-specific.

The correct goal is:

standardize where possible, customize where necessary.

Corrosive Scrubbers Need Material Consistency

When multiple internals are supplied together, material compatibility should be reviewed across the entire package.

For example:

• packing;
• demister;
• support;
• distributor;
• fasteners.

Using corrosion-resistant PP for the packing while leaving incompatible metal fasteners exposed may create a weak point.

Final Engineering Principle

“Standard configuration” should refer to a proven design family, not a claim that every tower internal has universal dimensions.

Random packing can often be truly standardized.

Distributors, supports, demisters, and segmented internals typically require final project dimensions before fabrication.