Rolls-Royce adds SCR system for mtu Series 2000 marine engines

Rolls-Royce is introducing a selective catalytic reduction (SCR) exhaust after-treatment system for its mtu Series 2000 marine engines, which will make vessels using the engines IMO Tier III compliant.

The system is being certified with exhaust after-treatment specialist Eminox and completes Rolls-Royce’s SCR offering for the Series 2000 range. A similar solution has already been introduced for the higher-powered mtu Series 4000 engines.

The technology is aimed at vessels including offshore supply vessels, ferries, crew boats and patrol boats operating in areas such as the North Sea and Baltic Sea, where IMO Tier III requirements apply.

SCR systems inject an aqueous urea solution into the exhaust. The resulting chemical reaction converts nitrogen oxides into nitrogen, water and other harmless substances. Rolls-Royce says its system reduces NOx emissions by 75% compared with the IMO Tier II limit.

The new installation is designed for up to 16,000 operating hours, depending on the vessel’s load profile, and does not require compressed air for urea dosing.

“With this new offering, all models in the mtu Series 2000 are now available with integrated SCR systems,” said Dr Lukas Köhler, senior vice-president global marine and mining at Rolls-Royce Power Systems. “We have already launched a new, flexible and compact solution for the more powerful mtu Series 4000. This enables us to equip our customers with future-proof propulsion systems to meet the challenges of modern shipping.”

For operators, SCR provides a means of meeting the NOx requirements without replacing the underlying diesel propulsion system. The system’s integration into the engine and exhaust arrangement will also be a consideration for newbuilds and retrofit projects where machinery-space constraints are significant.

SCR systems already on the market

Several established SCR systems are already available for newbuild and retrofit applications.

Wärtsilä offers its NOx Reducer (NOR) for medium-speed marine engines. The system is available for both newbuilds and retrofits and is designed to meet IMO Tier III requirements. Wärtsilä says the system is supplied as part of an engine-and-SCR package, with the reactor, urea pump, dosing equipment and mixing system integrated into the installation.

Yanmar has developed its own SCR systems for marine engines and has been using the technology to meet IMO Tier III requirements since the introduction of the regulations. Its systems use an integrated catalyst and bypass arrangement and are designed for operation in both ECA and non-ECA waters.

Yanmar has also introduced an SCR system for its 6LY400-440 high-speed engine, with claimed NOx reductions of 60–90%, depending on load and exhaust temperature.

MAN Energy Solutions offers modular SCR systems across its four-stroke medium-speed engine range. Its system is available for new engines and retrofits, with the company stating that NOx reductions of up to 90% are possible.

Caterpillar has likewise combined SCR with its MaK engines for IMO Tier III applications, including its M 25 E medium-speed platform.