Developments in diesel

Malcolm Latarche
Malcolm Latarche

24 May 2016


If LNG and alternative fuels have been making the headline news in marine power in 2016, it does not mean that nothing of note is happening in the conventional diesel arena. It is generally accepted that for the foreseeable future, oil burning engines will be in the majority. There is a likelihood that, in some ship types, particularly diesel-electric vessels and those with multiple main or auxiliary engines, battery energy storage could become a popular option to replace one or more engines. The engines most affected will be medium and high speed engines rather than low-speed two-strokes and offshore ships will be high on the list. That coupled with the fact that for the last 18 months or so, offshore shipping has not been the most vibrant sector and new orders are rapidly drying up. That is not good news for the likes of Caterpillar and Cummins who along with Rolls-Royce rely heavily on offshore ships for a large part of their sales. Nevertheless, Cummins did take the opportunity at Asia Pacific Maritime in March to launch a new engine for the marine market. It was only quite recently that Cummins replaced its venerable KTA series with the new Quantum series with models designated with a QSK prefix. The largest engine type, the QSK60 is a quite recent model with power outputs from 1,491kW to 2,013kW it is most frequently used as a propulsion engine for small offshore types such as fast crew boats and EERVs where it is often used to power waterjets through gearboxes. The marine version of the QSK95 that was launched in March – rail and other versions already exist – increases the maximum power output of Cummins’ marine engines by 50%. With ratings from 2,386kW to 3,132kW the QSK95 achieves a power output previously available only from larger medium-speed marine engines and opens up opportunities as a propulsion engine in larger offshore vessel types. Winterthur Gas & Diesel (WinGD), the joint venture that now manages the former Wärtsilä two-stroke engine business was making news with the delivery of the 14,000teu NYK container ship Blue Jay in March. The ship is fitted with a 9-cylinder Wärtsilä X82 diesel engine that is distinctive in that it is one of the first with a dual-rating option. The flexibility permitted by electronically controlled fuel injection and exhaust valve actuation, combined with turbochargers with very wide compressor maps has allowed WinGD to build an engine switchable between two pre-set modes matched to different operating strategies. Rudolf Holtbecker, general manager, business & application development, WinGD, explained “Ship owners wish to be able to respond to market conditions by having closer control over the fuel costs of their ships. In recent years this has led to owners operating their ships at lower speeds with engines running below their design ratings. “With the X engines, the dual-rating option has been introduced to allow ship owners to use their engines either with a low or a high maximum power output, improving fuel consumption in each operating mode without major modifications.” Improvements to engines are not always so innovative but incremental changes that add to longevity and reduce maintenance are appreciated by operators. Mitsubishi Heavy Industries Marine Machinery & Engine has just announced such a change with the adoption of a new material known as DSA760 developed by DaidoSteel for the exhaust valve of Mitsubishi UE engines. Compared to valves made with conventional Nimonic alloys valves made of DSA760 have been verified to show higher corrosion resistance on large bore UE engine with an expected 18 month longer lifetime. DSA760 is a heat-resistant alloy with added chromium and aluminium. It is estimated that the wear rate of the combustion surface is decreased by about 60%.