On the road with the Wärtsilä 31 engine

The Wärtsilä 31 has been deployed in both the marine and energy sectors. We go out in the field to see how it has performed.

Text: David J. Cord Photo: Wärtsilä

Wärtsilä operates in somewhat conservative industries, where new products are looked at with scepticism. Nevertheless, the Wärtsilä 31 engine has turned many heads, confidently placing itself as one of the best 4-stroke engines the markets have ever seen. With its modular design and latest technology, the Wärtsilä 31 is here to stay for decades to come, retaining its strong position amid foreseen stricter environmental requirements and the need for the highest efficiency. 

Today more than 100 Wärtsilä 31 engines have been sold, accounting for spark ignited gas, diesel and dual-fuel versions for both marine and energy customers. These engines have been delivered for several different applications and use within the marine and energy industries. In less than two years, 100 MW of power output capability by the Wärtsilä 31 engines has been handed over to commercial operation. 

The Wärtsilä 31 technology has brought benefits to both the maritime and energy sectors. It brings reduced emissions with higher efficiency and supports the integration of renewable energy sources. The engines can be quickly ramped up and ramped down as needed, providing important flexibility in power generation. The engine family is modular, so it is possible for customers to update – e.g. power up or switch the fuel – when needed. The engines can also be converted to run on clean fuels of the future when they are ready for commercial use.  

Juha-Matti Myllykoski has been involved with the Wärtsilä 31 since its inception and continues to help its improvement using data from the field. He works in R&D and is the programme manager for the medium bore engine platform.  

“Over 200 dedicated and passionate people in Wärtsilä are involved, including experts in mechanics, automation, lab testing, production and services,” Myllykoski says. “Our goals from the beginning were to develop an engine that is highly energy-efficient, increases output, complies with upcoming emissions requirements and brings value for our customers and Wärtsilä.”

The pressure of being the first 

The first marine application of the Wärtsilä 31 was handed over for commercial operation in August 2018 on the ferry Hammershus, owned by the Danish operator Molslinjen. Jan Hauberg Jørgensen, Chief Engineer at Molslinjen, was apprehensive. As the first customer, you never know how a brand-new product will perform in the real world, but it turned out he had nothing to fear. 

“The engines perform better than expected from my point of view,” he says. “Wärtsilä follows us closely because they don’t want us to have a bad experience.” 

Wärtsilä works in a proactive mode to make sure that lessons are always learnt, ensuring positive customer experiences. However, Molslinjen did have an event which could have caused problems: the failure of a high-pressure pump on one of their engines. This caused some operational issues for the customer, but it was turned into a good learning experience. 

“It was handled professionally, and it was easy to get back on track. They tested the failed pump and improved the design,” Jørgensen says. “The service teams are always on call and ready to come to us at short notice. Overall, I am happy with the engine and pleased with Wärtsilä’s service.” 

Molslinjen is so pleased with the product that in late May 2020 they decided to equip their new 115-metre-long high-speed ferry with four Wärtsilä 31 16-cylinder engines. The new vessel will be an all-aluminium catamaran with a top speed of 40 knots. By using Wärtsilä 31 technology, both the tight route schedules and reliability of the vessel are ensured. When these are combined with prolonged maintenance intervals, the crew is able to concentrate on their main task – transporting people and cargo. 

Bringing flexibility and efficiency to energy producers 

The first Wärtsilä 31SG engine generating sets for energy production began running in the US state of Mississippi on 8 April 2020. Cooperative Energy had wanted to upgrade one of their plants to help supply affordable, reliable and flexible power.  

“There is a lot of variable generation in our market, such as our 52 MW solar plant,” Jim Compton, President Emeritus of Cooperative Energy, told us in December. “We need to match variable generation with more flexible capacity which can rapidly start up when needed. Wärtsilä’s engine generation sets meet this need. The Wärtsilä 31SG engines are top-of-the-line.” 

Carefully analysing the Wärtsilä 31 in action 

Sami Horttana, Senior Technical Support Engineer, Wärtsilä 31 Technical Services, is studying the engine in the field and learning how to continually improve it. “We have been following the engines in several different ways, such as replacing components for detailed testing in our laboratory, analysing operational data and closely collaborating with our end customers,” he says. “This allows us to detect and correct any possible issue, avoiding possible unplanned downtime. We are also following the wear rate and condition of the components to ensure that we meet our expected time between overhauls.” 

Engine development is carried out systematically with Wärtsilä’s customers, including with a field follow-up programme. Data is gathered through remote connections, scheduled physical component inspections and feedback from customers. The aim is to confirm the engine components and performance in real working conditions to ensure that development tasks have met the set requirements. 

“It is amazing to see that for the latest 10,000 running hours accumulated on our follow-up installation the engine performance is relatively unchanged,” Horttana says.  

Built for the needs of today and tomorrow 

The Wärtsilä 31 has proven its worth in the field, and the team is continuously seeking ways to improve it even further. In fact, the engine was created with the future in mind. It was designed specifically to be upgraded to cleaner gas or liquid fuels as they become available in the future.  

“The future is bright,” says Risto Lejon, Product Manager for the Wärtsilä 31 Energy Business engines. “Our transition to a 100% renewable energy future is supported and enabled by the Wärtsilä 31. We have had no major issues from customers, and I look forward to working with this engine for many years to come.” 

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