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Marine Propulsion & Auxiliary Machinery

Marine Propulsion & Auxiliary Machinery

Chemical breakthrough simplifies scrubber consumables handling

Mon 18 Mar 2019 by Gavin Lipsith

Chemical breakthrough simplifies scrubber consumables handling
A stable suspension brings operational and cost advantages for closed-loop scrubber users

Easier handling will make magnesium hydroxide a more attractive option for ship operators using closed-loop scrubbers after a breakthrough in the production of the alkali source.

Magnesium hydroxide supplier Nedmag Industries has managed to keep the alkaline compound in stable suspension using wet grinding and the addition of a polymeric dispersant. The process means that the product no longer separates, so ship crew do not need to agitate it continuously.

The company currently supplies its product, under the MH53S Mare brand, to around 50 ships, with a further 30 being added each quarter. These include big ro-pax and container vessels for European owners.

The Dutch supplier has engaged chemicals company Timab Magnesium to ensure global availability for the compound in the marine market. The companies plan to boost current distribution, which covers China as well as Europe, to make the product available at key bunkering hubs.

Nedmag sales manager Henk van den Berg noted that the volume of magnesium hydroxide required for scrubbing is 25% less than for the most common alkali source used with scrubbers, caustic soda. The magnesium suspension is also non-hazardous, meaning further cost savings by reducing the logistical complexity and safety precautions demanded for highly corrosive caustic soda.

“Our belief is that more vessels will be driven to adopt closed-loop scrubbers as the use of open-loop scrubbers is restricted further by ports and in coastal waters,” Mr van den Berg said.

Nedmag process development manager Lucas van den Brekel explained that stabilisation was a complex process and potentially challenging for other suppliers to replicate. Nedmag’s product is also finer and more pure than other manufacturers’, both of which contribute to performance.

Alkali sources including caustic soda and magnesium hydroxide are sprayed into exhaust gases to neutralise the highly acidic sulphur oxides found in the exhaust. They are not required for open-loop scrubbers, where seawater is used instead. 

Responses to IMO's global sulphur limits and operational challenges for scrubber users will be among issues discussed at Riviera Maritime Media's Sulphur Cap 2020 Conference in Amsterdam on 8-9 May.

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