Retrofit Solutions for Exhaust Gas and Water Cleaning

Upcoming environmental regulations will affect existing vessels, and as a consequence there is a growing demand for exhaust gas cleaning and ballast water treatment systems.

Retrofitting both scrubbers and ballast water management systems is – or will soon be – required for many ships to comply with regulations. There are retrofit solutions available across all ship types, from cruise vessels to merchant and offshore ships. Space requirement is usually the most critical factor when planning and executing a retrofit project but Wärtsilä has found solutions to the challenge.

The execution of retrofit projects for both scrubbers and ballast water management systems requires similar types of planning and engineering. There are typically three things that are analysed when planning a retrofit of exhaust gas or a water cleaning system. First, the space requirements of the system are analysed, taking into consideration the available space in the vessel. Next, engineers study the impact of the additional systems in terms of their weight, ship stability in case of scrubber systems, structural modifications, and relocation of any existing equipment inside the ship. Finally, engineers assess how to further optimise the installation method, with the aim of minimising costs and downtime during installation.

“Retrofitting exhaust gas or ballast water cleaning systems is feasible for all ship types – but how it is done can vary depending on the ship type. Finding space for the system is the most common challenge. When it comes to scrubber installations, we, for example, sometimes need to make changes in the funnel shape or rethink the use of spaces in the vessel to create more room for cleaning systems. However, we have not come across any project in which retrofitting would not be possible. It is just a matter of identifying the best solution or compromise with the ship owner,” says Leonardo Sonzio, Director Retrofit, Wärtsilä Environmental Solutions.

According to Sonzio, the biggest cost factors in retrofits are the equipment, and the installation operations and material. Generally, the cost of the equipment varies depending on the type and size of the ship. The installation cost depends on the extent of modifications to the existing ship, and the time needed at the dry dock.  As a rule of thumb, equipment and installation each represent forty percent of the total price for a turnkey retrofit; the remaining twenty percent is related to engineering, project management, site management, logistics and class approval costs.

“We have delivered or are in the process of delivering dozens of new build and retrofit projects for scrubbers. These include tankers, bulk carriers, container vessels, ro-ros, cruise vessels and ferries. More and more inquiries are coming in from ship owners. Also, we are expecting the demand for ballast water management systems to grow steadily, and we have experience with both new build and retrofit cases. Our approach to a successful retrofit project is true partnership and thorough engineering and planning before the contract is even signed. This enables us to manage risks in close cooperation with our customer,” Sonzio explains.

Wärtsilä ballast water management systems use a two stage approach involving mechanical filtration of organisms followed by a choice of either UV treatment  or electro-chlorination. The Wärtsilä portfolio of scrubbers includes three configurations: seawater open loop scrubbers, closed loop scrubbers, and hybrid scrubbers. All three configurations include a wash water treatment plant to clean the effluents before discharge into the sea with no risk of harm to the environment.

Wärtsilä said it is the only company capable of providing both scrubber and ballast water systems combined with turnkey retrofit services. With its professional project organization, Wärtsilä is able to manage all kinds of retrofit projects worldwide. Wärtsilä’s global services network supports customers throughout the lifecycle of the ship.

The most evident approaching regulations for existing vessels are the IMO Marpol Annex VI focusing on sulphur oxide (SOx) emissions, and the IMO Global Ballast Water Convention.