Maritime Propulsion

Alfa Laval said its PureSOx exhaust gas cleaning system is gaining ground in the cruise ship market. Following a lengthy selection and qualification process, four PureSOx scrubbers have been ordered by Royal Caribbean Cruises Ltd (RCL). Three of these will be PureSOx 2.0 systems as presented at SMM 2014, while the fourth will be the first test inline version of PureSOx. 

 

Alfa Laval’s deliveries to RCL will extend over the summer of 2015. The PureSOx systems will be installed as retrofits aboard four Royal Caribbean International ships: three of the Freedom Class and one of the Voyager Class. Freedom of the Seas, Independence of the Seas and Liberty of the Seas will each receive a hybrid scrubber with multiple inlets, while Adventure of the Seas will receive an inline hybrid with one main engine connected. 

 

The contract for the Freedom Class vessels was signed in Q4 2014. “SOx scrubber systems are part of our commitment to meeting or exceeding important environmental standards, as they allow compliance even where low-sulphur fuels have limited availability,” said Harri Kulovaara, Executive Vice President, Maritime at RCL. “We chose Alfa Laval and PureSOx on the basis of strong references, a strong technical platform and a strong willingness to cooperate in implementing the technology on our vessels.”

 

“RCL is a highly capable partner with a strong interest in seeing marine scrubber technology move forward,” said René Diks, Manager Marketing and Sales, Exhaust Gas Cleaning at Alfa Laval. “Our collaboration on both the standard and inline PureSOx installations has been valuable for both parties.”

 

RCL, like many in the cruise industry, has an outspoken goal of reducing environmental impact. Scrubber technology fits neatly with this ambition, yet its implementation on cruise ships can be more difficult than on other vessels. The unique cruise ship construction poses challenges in meeting space and stability limitations.

 

For the RCL vessels, the process of meeting those challenges was a demanding year-long journey involving dedicated project teams from both RCL and Alfa Laval. A detailed and initially difficult Technology Qualification Process (TQP) was conducted, in which the two parties, sometimes supported by external integrators, discussed the technical requirements in depth. Uncertainties and concerns were identified, evaluated and carefully addressed.

 

“There is immense complexity in a retrofit of this size aboard a cruise ship,” said Kevin Douglas, Vice President, Technical Projects and Newbuild at RCL. “To ensure the right solution and the smoothest possible implementation, we needed a thorough, open and systematic dialogue. Alfa Laval has worked closely and vigorously with us to merge their system knowledge with our expertise in cruise ship installations. As a result, we have confidence the strong partnership will deliver results."

 

Despite the issues of space and weight on a cruise ship, the standard U-shaped configuration of PureSOx 2.0 could be incorporated into all three of RCL’s Freedom Class vessels. “This is a flexible configuration that reduces installation cost by allowing multiple engines to be connected,” Diks said. “Space for the scrubber itself was found behind the existing funnel, in front of the rock-climbing wall. The water cleaning unit and circulation tanks, which are necessary for hybrid operation, will be located high up and on the same deck, which will avoid the need for an additional booster pump.”

 

Hybrid operation, which offers both closed-loop and open-loop modes, was particularly important for the RCL vessels. Since their routes will take them into U.S. coastal waters, the vessels will be subject to US VGP legislation, which sets discharge criteria that are even stricter than those of IMO. “Our cruise ships will naturally use seawater in open-loop mode whenever this is feasible,” Douglas said. “However, their area of operations will require a closed-loop mode with reliable water cleaning. This is where Alfa Laval’s separation expertise comes into play.” 

 

The PureSOx installation aboard Adventure of the Seas will also be a hybrid system. However, the design of this Voyager Class vessel posed additional constraints. Because the space available was even less and the stability issues even greater than aboard the Freedom Class vessels, RCL was open to finding an alternative configuration. Adventure of the Seas will thus be the first vessel to install an inline version of PureSOx, which has been under development at the Alfa Laval Test and Training Center in Aalborg, Denmark. 

 

“Inline scrubber configurations will be attractive or even necessary for many cruise ships and RoPax vessels, which is why inline development has been a high priority for Alfa Laval,” said Jens Peter Hansen, Alfa Laval R&D Manager. “The analysis and trials at our new test centre have focused on ensuring a safe water trap and minimizing material stresses in the inline design, because the scrubber is cooled and heated with every start and stop. We were pleased to involve RCL, whose valuable insights and installation expertise have contributed to the final design, and we look forward to following up on this first inline installation.”

 

“We were very interested in working with Alfa Laval on the inline version of PureSOx, because it addresses the unique challenges of cruise ship building,” Douglas concurred. “We are keen to see scrubber technology develop, especially in this direction.”

 

With the selection and technical negotiations at an end, Alfa Laval is now established in exhaust gas cleaning for the cruise ship market. The four-vessel commitment from RCL doubles the number of cruise ship orders in the PureSOx portfolio.

 

“The cruise industry, with its environmental profile and unique technical considerations, places high demands on a SOx scrubber,” Diks said. “Alfa Laval PureSOx provides a great deal of flexibility in meeting those demands, and will offer even more flexibility when the inline version is officially launched.”