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Advanced solutions for increasing operational optimisation on LNG carriers

In the second of our tech talks, Jeremy Crossman, Sales Excellence & Coaching at Wärtsilä Marine Power, speaks to three experts about the latest solutions for increasing operational optimisation on LNG carriers. Fredric Sunabacka, Product Manager for Wärtsilä’s W32 and W34 engines, Michael Kranz, General Manager of Shaft Generator Systems, and Jon Storholt, Manager of Power & Systems Integration, share their insights into Wärtsilä’s 34DF engine, shaft generator systems and hybrid integrated solutions.

There are many reasons that make the Wärtsilä 34DF engine ideal for LNG carriers, both in the engine itself and because of the advantages of partnering with an experienced industry leader like Wärtsilä. “Wärtsilä has over 30 years of experience with gas engines, and all of this knowledge and experience can be seen in the Wärtsilä 34DF engine, which is installed in close to 80 LNG carriers, which is almost 300 engines,“ shares Sunabacka. “It has the best power-to-weight ratio on the market and it also boasts some of the lowest greenhouse gas (GHG) emissions thanks to its GHG reduction package, which is available for both newbuilds and as a retrofit package. Energy and lube oil consumption are competitive across the load range, and it can reach full output operating on gas, with a methane number down to 70. It also offers low load optimisation, fuel-sharing capabilities and automatic Cetane tuning.“

“Not only does Wärtsilä deliver premium products and services, we are also here to support you when times are tough,” continues Sunabacka. “Wärtsilä prides itself on being a reliable partner, continuously developing products and solutions to help meet industry decarbonisation targets. We have the capability to integrate all our products and match them to LNG carriers and their operating profile.”

The benefits of shaft generator systems

There are many benefits to using a shaft generator system rather than just a simple fixed-speed shaft generator. “The additional converter means you can use the shaft generator system as an electric power source even though the propeller speed is changing,“ explains Kranz. “The previous generation of shaft generators required a fixed main engine speed to connect to the main switchboard with the correct frequency and voltage. This limited the time when the shaft generator could be used, but with the shaft generator system you can have many more running hours – up to six times more on deep-sea vessels like LNG carriers, for example. This is because the system will also work at low speeds, in heavy seas and when your propeller speed is frequently changing. When using a controllable pitch propeller system, another advantage is you can continuously optimise your combinator curves during operation and the shaft generator system will continue to work as normal.“

“For LNG carriers, or indeed any gas carriers, a shaft generator system is the perfect way to handle your boil-off gas,” Kranz continues. “When the main engine is running on gas, the shaft generator allows you to generate all the electrical power needed onboard with very good efficiency and close to zero maintenance costs for the whole shaft generator system. Many gas carriers are built for long distances and sailing in deep waters, so they want to focus on pure power generation – we call this power-take-off (PTO) functionality. For this setup the Wärtsilä shaft generator system has the highest efficiency on the market as we use two optimised components that are specially designed for this application.”

Four options each with unique advantages

“There are two main differences between shaft generator systems,“ points out Kranz. The first is that shaft generators can either be connected to a gearbox or they can be inline around the propeller shaft. Gearbox shaft generators are smaller electric machines with a higher RPM, and inline shaft generators are bigger with two-stroke main engines. The second difference is that these systems can be either an electrically excited or a permanent magnet type. The former has been around for a long time and is often the preferred choice for single-shaft propulsion. There is no magnetic force holding the shaft so if something is failing you don’t run the risk of losing propulsion.

“Permanent magnet generators are a little more expensive, but they are more efficient and are generally preferred for twin-shaft propulsion. As the name suggests, this generator always has a magnetic field so can be more challenging to use, but there are other benefits in terms of shaft arrangement and they are also lighter. Wärtsilä offers all four options in our shaft generator systems: fast turning, slow turning, electrically excited and permanent magnet solutions.“

Integration is increasingly common

“In the last decade we have experienced high demand for integrated functionalities in the shaft generator system,“ observes Kranz. “The reason being you can easily make a multi drive if you are installing a frequency converter anyway. This happens with thruster motors, battery connecters, shore connection or power-take-in (PTI)/power-take-home (PTH) functionality – whenever you push energy into the electric motor instead of taking the energy out of it. Over the last 10 years, one in four systems has been equipped with at least one of these functionalities. This higher degree of integration is a benefit for the shipyard as they only have one point of contact, which is a benefit for owners too as it makes troubleshooting easier. You can just leave it to Wärtsilä to design the shaft generator system and then your chosen functions really work together.

“For thrusters, this means that you can integrate relatively big thruster motors into the shaft generator system and start them using the power from the shaft generator. You can use connected batteries to do both the peak shaving for the thrusters (so no auxiliary engine has to be used just to start a thruster) and to keep the auxiliary engine off during manoeuvring because the battery provides blackout prevention or spinning reserve. For shore connection you can use the shaft generator system to connect the vessel to a different frequency than you have onboard, such as a 50 Hz grid on the onshore side and 60 Hz on the vessel, supplying your main switchboard with the frequency and voltage the vessel needs and giving you full flexibility for future operation. And if no shore connection is available, you can use the shaft generator converter to supply the mains using the battery in eco-harbour mode.“

The benefits of hybrid integrated solutions

“We develop and deliver electrical and hybrid integrated solutions, products and digital solutions for the marine industry,“ sums up Storholt. “With hybrid technology, we can support the future of the marine industry by helping operators to improve efficiency and reduce emissions and operational costs. With fuel costs expected to continue increasing, hybrid technology can enable vessels to adapt to future green and transition fuels.

“For LNG carriers, finding the business case for implementing hybrid technology can be challenging; however, there are many functions that are enabled by hybrid technology, such as spinning reserve/blackout prevention, peak shaving, optimal loading, improved dynamic performance and electric operation. A hybrid battery system can be used to support the general operation of the vessel during transit, manoeuvring and in port. In addition, batteries can be used for cargo handling, supporting auxiliary power or other modes of operation.“

Future-proofed intelligence at its core

“Wärtsilä can offer a wide range of hybrid concepts and integrated hybrid propulsion solutions for both mechanical and electrical propulsion,“ continues Storholt. “Mechanical hybrid propulsion is where the main engine is equipped with a PTO or PTO/PTI shaft generator in combination with a battery system, or a battery solution is simply integrated to provide supporting auxiliary power.“ Electrical hybrid propulsion solutions combine and optimise the operations of different power sources such as batteries, engines, fuel cells or other innovative means of power storage or generation to deliver efficient propulsion. Wärtsilä hybrid solutions are suitable for applications in a wide variety of segments, as well as for retrofits of existing installations.

“Wärtsilä’s hybrid and zero-emissions propulsion technologies all feature our unique energy management system (EMS) at their core. The EMS is the brain of the system, connecting and optimising power sources and demands to deliver efficient propulsion while controlling the process in an efficient, safe and stable way. One of the major advantages of the EMS is that it’s able to adapt to the surrounding technology as new energy storage systems and fuels develop.“

A bright future when we work together

“Wärtsilä has a large portfolio and the capability to integrate all our products,” points out Sunabacka. “We can also include them in long-term partnerships that are designed to match LNG carriers and their operating profile. Our vision for the future is to partner even closer with our customers on a more personal level, building strong relationships that optimise their businesses while we work towards common goals. Together we have a bright future.”

To find out more about how Wärtsilä’s 34DF engine, shaft generator systems and hybrid integrated solutions can help to optimise operations on LNG carriers, watch the webcast in full: https://www.wartsila.com/marine/technology-tailored-for-lng-carriers/efficient-and-flexible-solutions.
Source: Wärtsilä

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