B-Gon | Solutions for Gas Scrubbers (Peroxide Scrubber)

Introduction / Problem
One of the biggest challenges in sulfuric acid plants is meeting increasingly strict environmental regulations on SO2 emissions. With Chile’s DS 28 regulation, many facilities have sought technologies to reduce emissions, including the Peroxide Scrubber.

The Peroxide Scrubber oxidizes SO2 to H2SO4 using hydrogen peroxide (H2O2). Oxidation can occur in packed beds where sulfur dioxide gas contacts diluted sulfuric acid containing trace H2O2.
Like any packed tower, the rising gas carries a liquid mist. In a peroxide scrubber, this mist is 40–50% sulfuric acid, posing a significant safety and environmental hazard.

The Problem

A major foundry in Chile contacted Clark Solutions seeking a solution for acid mist carryover in its peroxide scrubber. During the first year of operation, the area around the plant was affected by constant acid drift, corroding equipment and creating a safety risk for operators.

The installed mist eliminator was a 2-pass vane type.

Analysis

In packed towers under scrubber conditions, mist droplet sizes can be as small as 5 µm, and the choice of mist eliminator must address this requirement.

A CFD study was conducted on the existing vane mist eliminator under the plant’s operating conditions:

• Particle Tracing: Two conditions were analyzed: 5 µm and 20 µm droplets at different times.
• Colored velocity contours show gas velocity at each point in the eliminator (m/s).
• The pink trajectory shows a 20 µm particle entering the vane eliminator. It is captured when attempting to change direction at the second bend.
• The blue trajectory follows a 5 µm particle, which essentially follows the gas stream throughout the unit.
• Vane eliminators are effective at capturing droplets ≥20 µm with minimal re-entrainment, making them suitable where mist sizes are larger than this or where fouling is a concern.

Alternative Solutions

Clark Solutions offers other configurations for the same application. A more economical option uses PP mesh with FRP support plates, though this has a lower temperature limit.

B-Gon CFD Study and Performance

A 3D CFD simulation was performed for the B-Gon mist eliminator:

• Red points indicate 5 µm mist droplets attempting to pass through the B-Gon.
• 99% of 5 µm particles are captured when all B-Gon layers are considered.

The key to B-Gon’s performance is that 93% of its fibers are perpendicular to the flow direction, increasing capture efficiency. Its honeycomb-like structure and wire thickness enable the unit to remain in service for years without deforming, and the design allows cleaning — a major advantage over standard plastic mesh eliminators.

Project Implementation

As shown in the photo, a B-Gon mist eliminator with a 4000 mm diameter was engineered and built in just 10 modules, simplifying installation and reducing the risk of gas bypass between modules.