The use of stainless steel and GRP in scrubbers provides quality, they also require coatings for some areas, such as discharge nozzle to mitigate corrosion. The installation of scrubber systems on approximately 4,000 ships (predominantly open-loop scrubbers) is scheduled for next year to comply with the 2020 sulfur limits and to maintain air quality.

Open-loop scrubber systems discharge all wash water overboard. Less than 2% of the scrubbers are considered to be closed-loop wet scrubber systems, while 20% of them are regarded to be hybrids (both open and closed-loop air treatment systems to comply with wash water discharge regulations in areas where it is forbidden to do).

SOx caught in the exhaust gas dissolves in the washwater and produces strong acids resulting in low pH of the wash water. Wet air scrubbers manufacturers have to pay careful attention to the choice and specification of wet scrubber material and coatings because wash water pipelines cause cracks and leaks in the scrubber.

The acidic wash water flows down the walls of the scrubber tower during the process of air treatment. A conventional wet scrubber tower suffers from a high level of acidic corrosion. Additionally, scrubber systems face potential damage to the anti-biofouling coatings on the hull.

According to IMO regulations, the pH level of scrubber wash water is required to be 6.5 at 4 m from the discharge point when the vessel is stationary. The pH level is far from 6.5 after the neutralization process may damage the binder existing in some biocidal antifouling systems of wet air scrubbers.

All wet scrubber systems include the following main requirements for the materials: corrosion resistance, acid resistance, and high-temperature performance. The corrosion process can happen both in all seawater pipelines and the water supply to the scrubber tower. “The scrubber tower is an area where an acid attack can be severe”. 

The temperature in the wet scrubber tower varies from 50°C to 60°C, while the overboard pipeline temperature can be less than 40°C, that is why the use of appropriate coatings in addition to the proper selection of wet air scrubber materials is highly recommended.

Finally, there is an opinion that a manufacturer of wet scrubber systems will provide the required materials chosen for the scrubber, and there is a need for coatings just in the overboard discharge section because of the high probability of wash water impact on the hull coating.

If you are looking for the best air treatment device to improve air quality, Redwood Technology offers a cutting-edge type of wet scrubber – a Multi-Vortex wet air scrubber.

Redwood technology is a fast-growing vendor of wet air scrubbers. The multi-vortex scrubber can remove gas emissions, dust, vapors, and other pollutants from a gas stream. It is an innovative technology created to save water that makes it more cost-efficient and differs from other types of scrubbers.  If you have any questions or would like to purchase a multi-vortex wet air scrubber, please contact us at info@rdwd.tech