Alfa Laval Debuts Inline Scrubber Design

“Through open-loop, closed-loop and hybrid arrangements, PureSOx can be suited to any vessel’s sailing profile,” says René Diks, Manager Marketing & Sales, Exhaust Gas Cleaning at Alfa Laval. “By adding an inline scrubber design to the already flexible PureSOx platform, we’ve made PureSOx even easier to adapt to individual vessel constructions.”

The inline scrubber design, or I-design, builds directly upon PureSOx technology, providing an additional alternative for vessels with more complex structural needs. “While inline configurations should not be seen as a default,” says Diks, “they can make it easier to accommodate the specific challenges of certain vessels.”

According to Alfa Laval, an important consideration in creating an inline PureSOx scrubber was the water trap, which is not formed naturally as it is in the existing U-design. “Because the absorber section is located atop the jet section in the I-design, no water trap is created between the two,” says Diks. “A key focus was eliminating the potential for water backflow, which is done by means of an internal water trap combined with overboard arrangements.”

As with the U-design PureSOx scrubber, the I-design scrubber can be configured with multiple inlets. This reduces space needs and installation costs by allowing one scrubber to handle exhaust gas from multiple sources, including boilers as well as the main and auxiliary engines.

A further alternative for inline PureSOx configurations is reflux. This option is especially attractive for cruise ships, RoPax vessels and other vessels that carry passengers, as it reduces the risk of dirty water droplets discoloring the ship’s deck.

Reflux involves the creation of two separate loops: one for the jet and a second for the absorber. In the jet loop, clean water is evaporated by means of the waste heat in the exhaust gas. The vapor is then recondensed as clean water in the absorber loop.

As a result, the water in the absorber stage is cleaner and the risk of deck discoloration is greatly reduced. Since the soot is concentrated in the initial jet stage, the water cleaning unit has a lighter burden as well.

The water cleaning unit is a vital component of any closed-loop or hybrid PureSOx system. When the scrubber is in closed-loop mode, the unit removes soot from the circulation water, thus protecting the scrubber and enabling compliant discharge of bleed-off.

The PureSOx water cleaning unit uses centrifugal separation, an Alfa Laval core technology that is completely unaffected by pitch and roll. Like the reflux principle, it is a patented solution unique to Alfa Laval.