Marine Scrubbers

Legislation requires the mitigation of sulfur oxide pollution caused by the combustion emissions of high sulfur fuels in cargo and passenger vessels. Only fuels with 0,5% max sulfur can be used worldwide, the limit becoming even stricter at 0,1% in various Emission Control Areas (ECAs). Ship owners are either changing to low sulfur Marine Gas Oil (MGO) or implement on-board desulfurization to achieve equivalent emissions to MGO while still burning heavy fuel oil. On board desulfurization can be either open loop (i.e. use of sea water for scrubbing and discharging washwater overboard), closed loop (i.e. use of sea water with enhanced alkalinity by the addition of a reagent and temporarily storing washwater onboard) or hybrid systems able to work in both modes at will. Closed loop/hybrid installations are expected to increase their market share due to more countries imposing washwater discharge bans (open loop scrubbers operation) due to environmental concerns (including the EU which has formed a dedicated forum). 

Magnesium oxide may be used as SOx absorbent in vessel scrubbers designed to handle MgO powders. Such systems offer several advantages over scrubbers utilizing caustic soda (NaOH) or hydrated lime (Ca(OH)₂). MgO is a milder base that cannot be overdosed, it offers higher alkalinity and sludges of lower volumes. Moreover, use of powder MgO offers greater flexibility than magnesium hydroxide (Mg(OH)₂) slurries which are often associated with stability problems and limited availability or encumbered logistics. Grecian magnesite MgO grades can offer several benefits…