Industry: Sulfuric Acid ManufacturingApplication: Drying Tower Mist EliminationLocation: KazakhstanChallenge: Excessive pressure drop under high gas velocity conditions

A sulfuric acid production facility in Kazakhstan was experiencing repeated failure of fiber bed mist eliminator elements installed in the drying tower. The existing units had reached the end of their service life and required full replacement. However, a straightforward like-for-like replacement was not viable — the plant's gas velocity through the drying tower was significantly higher than standard design parameters, and a conventional replacement unit would not meet the system's pressure drop requirement.

The plant engineering team approached Filtearth for a custom-engineered replacement solution that could handle the elevated gas velocity while keeping pressure drop within the system limit.

The core problem was a conflict between mist elimination performance and system pressure drop at high gas velocity.

Standard fiber bed mist eliminator elements for sulfuric acid drying tower service are typically designed with a fiber bed thickness of 50mm. At the gas velocities present in this tower, a 50mm fiber bed would generate an operating pressure drop of approximately 1,800 Pa — well above the system design limit of 1,450 Pa. Exceeding this pressure drop limit would increase load on the system blower, reduce overall plant throughput, and risk instability in the drying tower operation.

At the same time, simply reducing fiber bed thickness to lower pressure drop would compromise mist removal efficiency — an unacceptable outcome for a sulfuric acid drying tower where mist carry-over causes corrosion damage to downstream equipment and acid loss from the process.

The engineering challenge was clear: design a fiber bed mist eliminator that maintains high mist removal efficiency at elevated gas velocity while keeping operating pressure drop below 1,450 Pa.

Filtearth's engineering team analyzed the plant's gas flow data — including volumetric flow rate, operating temperature, pressure, and tower geometry — and developed a custom fiber bed specification optimized for this specific operating condition.

The key design decision was to reduce fiber bed thickness from the standard 50mm to 25mm, combined with a carefully selected fiber grade and packing density optimized to maintain mist removal efficiency at the higher face velocity resulting from the thinner bed.

This approach required precise fiber selection: too coarse a fiber grade and efficiency would drop; too fine and pressure drop would remain too high. Filtearth's engineering team specified a fiber grade and packing density combination that achieved the target performance at the reduced bed thickness.

Following installation of the 7 custom fiber bed elements in the drying tower, the plant reported stable operation with the following performance:

The custom 25mm fiber bed design achieved an operating pressure drop of approximately 1,200 Pa — 250 Pa below the system limit and 600 Pa lower than the standard 50mm design would have produced. Mist removal efficiency was maintained above 99.99%, meeting the drying tower's acid mist control requirements.

The installation has operated stably since commissioning, with no reported issues related to pressure drop, mist carry-over, or element integrity.

This project illustrates a critical principle in fiber bed mist eliminator design: bed thickness, fiber grade, and packing density must be co-optimized for the specific operating velocity — not selected from a standard catalog.

At elevated gas velocities, reducing fiber bed thickness is counterintuitive but technically justified when paired with the correct fiber specification. A thinner bed at higher face velocity, engineered with the right fiber grade, can achieve equivalent or superior mist removal efficiency compared to a thicker standard bed — while delivering significantly lower pressure drop.

This kind of application-specific engineering is what separates a custom mist eliminator supplier from a catalog product vendor.

If your sulfuric acid drying tower is experiencing any of the following, a custom-engineered fiber bed solution may be the right approach:

Filtearth provides full engineering analysis before proposing a solution — not a catalog selection. If your process data falls outside standard parameters, that is exactly the situation our engineering team is designed to handle.

To discuss a custom fiber bed mist eliminator for your sulfuric acid drying tower or other corrosive process application, contact Filtearth with your process data:

We provide a full engineering proposal within 3-5 business days of receiving your process data.