Mitsubishi Heavy Industries (MHI) and Mitsubishi Hitachi Power Systems (MHPS) have jointly developed a large-scale rectangular marine scrubber that removes sulfur oxides (SOx) from the exhaust gases emitted by marine diesel engines.
Created in response to new, more stringent SOx emissions regulations that come into effect globally from 2020, the new scrubber is able to purify exhaust gas emitted from inexpensive heavy fuel oil to a level equivalent to more expensive low-sulfur fuels and has been designed to allow easy installation on existing ships, according to MHI.
As explained, the adoption of a rectangular box-shape configuration – the world’s first – offers ease of installation in small spaces and superlative emissions treatment for high-output engines used on large-scale containerships.
The new SOx scrubber uses seawater as its cleaning agent, adopting a simple “open-loop” system in which seawater intake is sprayed directly on the exhaust gas. Effective use of seawater alkaline eliminates the need for chemicals or additional processing.
Further, because the horizontal and vertical dimensions of the rectangular scrubber tower can be freely modified, volume efficiency is higher than previous cylindrical scrubbers, providing space savings. The equipment configuration is simple, allowing easy installation not only in newly commissioned ships but in retrofitted vessels as well, MHI said.
The scrubber’s main unit can be set into the upper deck’s engine casing, meaning it doesn’t encroach on the ship’s load space. This is said to be particularly beneficial for large-scale containerships that use a “twin island” design structure.
Since 2015, the International Maritime Organization (IMO) requires sulfur content of less than 0.5% for marine fuels in designated emission control areas (ECA). However, this will expand to all sea areas from 2020 when new regulations are introduced.
Under the new regulatory structure, the use of cheaper fuels with 3.5% sulfur content will still be allowed if the installed equipment offers proportionate emissions reductions.
Deliveries of the scrubber are expected from 2020 and, in preparation, both companies will seek certification from selected countries while conducting extensive tests on ships.
The scrubber was unveiled by the duo at the Nor-Shipping 2017 maritime trade fair in Oslo, Norway, being held from May 30 – June 2.