How to Convert a One-Piece Mist Eliminator into Removable Sections During Retrofit

Some older towers contain mist eliminators that were installed during original vessel fabrication as one large assembly.

When replacement becomes necessary, the maintenance team may discover that the old unit cannot pass through the existing manway.

Cutting it apart for removal is possible, but installing another one-piece unit would recreate the same problem.

A better retrofit designs the replacement as removable sections from the beginning.

Start with the Real Access Route

Measure the usable manway opening and internal turning space.

A section must not only pass through the manway but also move to its final position inside the vessel.

Long rectangular sections can become difficult to rotate even if their cross-section fits.

Divide the Separator According to Function

Segmentation should preserve:

• support;
• drainage;
• sealing;
• gas-flow uniformity.

Randomly dividing a large mesh pad into many small rectangles can create excessive joints and bypass paths.

Control Joints Between Sections

Gas carrying droplets can bypass through open gaps between sections.

The new design should provide controlled overlap, sealing, or close-fitting joints appropriate to the separator type.

The joint should remain practical for field assembly.

Seal the Perimeter

Sectional construction does not solve wall bypass automatically.

The assembled mist eliminator needs a suitable peripheral seal against the vessel or support frame.

Tower ovality should be considered.

Design Individual Section Weight

A module may fit through the opening yet remain too heavy for safe handling inside the tower.

Section weight should match actual site lifting or manual-handling capability.

Provide Clear Section Identification

Each module should have a defined location.

Permanent marking helps installation crews reconstruct the separator correctly.

This is especially important when sections are not interchangeable.

Preserve Drainage

For wire mesh pads, collected liquid needs to drain through or away from the pad.

For vane systems, drainage paths may be more directional.

Segmentation should not trap liquid at joints.

Check Support Frame Condition

A new sectional separator may be installed on the existing support.

That support should be inspected for:

• corrosion;
• levelness;
• open area;
• strength.

A new demister on a damaged frame is not a complete retrofit.

Consider Future Removal

The replacement should be removable using the same access route without cutting.

This can reduce future shutdown work significantly.

Trial Assembly Before Shipment

Factory trial assembly can confirm:

• overall diameter;
• section sequence;
• joint fit;
• support interfaces.

The assembly can then be separated for shipping.

Avoid Excessive Segmentation

More sections are not automatically better.

Every additional module creates more handling and more possible bypass joints.

The largest practical removable section is often the best choice.