A shorter route to greater profits
Wärtsilä’s so-called ‘new generation’ – the Generation X series – of two-stroke engines was introduced in May 2011, with the aim of significantly contributing to lowering marine engine fuel costs and improving environmental performance.
The five-strong family comprises the X35 and X40, covering the small-bore end of the market; the X62 and X72 engines designed specifically for medium sized, bulker, tanker and container Panamax and feeder vessels, and the X92, planned for delivery in 2014. The Wärtsilä X92 is designed for propulsion of large and ultra large container vessels of 8000 TEU and above. All X-series engines have higher internal efficiencies and extended power/speed layout fields, and are claimed to be notably more economical than other engines in their market segment.
Wärtsilä says that the technologies employed in the Generation X engines offer competitive operational performance, having been derived from its proven existing two- and four-stroke engine designs. These include cylinder lubrication systems, common rail fuel injection, exhaust valve control, and the Wärtsilä UniC (Unified Controls) system. The electronically-controlled common rail fuel injection system, together with the extra long stroke and low rpm, results in high efficiencies, e.g. a reduction in fuel consumption of as much as 10% compared to current engine installations. Exhaust emissions are considerably lowered, while lubricating oil consumption is optimised. The improvement in emission levels of CO2 makes it easier for shipyards to achieve a more favourable EEDI.
The engine speeds and power ranges selected for the Generation X engines are intended for flexibility throughout a variety of operational applications. Additional flexibility is provided by an enlarged layout field. This enables selection of a combination of propeller speed and diameter to achieve efficiency at minimal daily fuel consumption.
The common rail fuel injection is time controlled, and the injection pressure is maintained at an optimum level irrespective of engine speed. At very low speeds, individual fuel injectors are shut off and the exhaust valve timing is adjusted to help keep smoke emissions below the visible limit.
Another benefit is that part-load fuel consumption is lower than with conventional camshaft-type engines. Two alternative fuel consumption profiles are available as standard - Delta Tuning and Low-Load Tuning - to give even lower brake-specific fuel consumption in what is the main operating range for many vessels.
The engines are designed so that overall flexibility eases compliance with current and pending environmental regulations, with CO2, SOx and NOx emissions all reduced. They are IMO Tier II compliant, and prepared for the forthcoming Tier III requirements.
Current and future needs
According to Wärtsilä, the shipping industry needs to rapidly adjust to changing market conditions. Economies of scale, increasing fuel prices and operational costs are driving the search for greater efficiencies, and environmental legislation is a major challenge throughout the marine sector. The Generation X series of engines was developed with all these needs in mind, to be in line with the industry’s current and future needs.
The X35 and X40 engines are intended for small bulk carriers, product tankers, general cargo vessels, reefers, feeder container ships, and small LPG carriers. The first of these electronically controlled, low speed engines was started in November 2011 and passed its factory test in February 2012. The X35 covers a power range of 3,475kW to 6,960kW at 142 to 167rpm, while the X40 has a power range of 4,550kW to 9,080kW at 124 to 146rpm. Both engines are available in five- to eight-cylinder configurations.
The X62 and X72 are compact mid-sized engines for main power applications in Capesize or Panamax bulk carriers, Aframax or Suezmax tankers, and feeder and Panamax container ships in the 1,600 to 4,500 TEU range. The X62 and X72 are claimed to be the most compact engines in their class, with minimal physical width. This results in a slimmer aft vessel design for further propeller efficiency gains. The power range of the X62 is from 6,600kW to 21,280kW, while the X72 has a power output from 8,880kW to 28,880kW. Both engines are available in four- to eight-cylinder configurations.
The latest X92 version is introduced in direct response to the move towards larger ships with more efficient propulsion systems in the container shipping sector. The X92 covers a power range from 25,860kW to 70,200kW and is available in six- to twelve-cylinder configurations.
In addition to the above operational and cost benefits, the Generation X series is designed for high reliability. The technologies used are well proven, as exemplified by the time controlled fuel injection system that serves also to improve operating costs.
High overall reliability, together with lower fuel costs and reduced maintenance requirement, results in a lower total cost of ownership. Extended intervals between overhauls and the possibility to re-manufacture key components contribute to lower maintenance costs. Plus, because the engines are simple to operate and service, highly-trained crews are not required.
Wärtsilä says that the route to profits for ship owners and operators has been a difficult one during recent years. With this in mind, the Generation X engines have been designed in close co-operation with customers to meet the many challenges that they face, and to shorten the route to industry profits.
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