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Finnish firm Wärtsilä has confirmed an order by Daewoo Shipbuilding and Marine Engineering (DSME) yard in South Korea for a total of 54 Wärtsilä dual-fuel engines to power 172,600-cubic-metre (cbm) icebreaking LNG carriers being built for use in arctic conditions to serve the Yamal LNG project in Northern Russia.

The ships are to be owned by a joint venture between Teekay LNG Partners of Canada and China LNG Shipping (CLNG), and another joint venture between China Shipping LNG Investment Co.,Ltd. (CSLNG) and Japan-based Mitsui O.S.K.. Wärtsilä said the order for the engines was placed with its Korean joint venture company, Wärtsilä Hyundai Engine Co., (WHEC) in October.

According to Wärtsilä, the machinery is capable of operating on liquefied natural gas (LNG), heavy fuel oil (HFO), or low-viscosity marine diesel oil (MDO), but LNG will be the main type of fuel to be used.

In a statement, Wärtsilä said: "When operating in arctic waters the engines will be operating in ambient temperatures of as much as minus 50 degrees Celsius on LNG carriers breaking through ice more than two metres thick, in operating modes that allow dramatic variations in engine load within a limited period of time. Wärtsilä's ability to meet these demanding design criteria was a key factor in the award of this contract."

Wärtsilä is to supply 12-cylinder and 9-cylinder Wärtsilä 50DF dual-fuel engines for each LNG carrier. The total power output from the Wärtsilä engines is said to be 64,350 kilowatts (kW) per vessel.

"This very important order once again emphasises the technical leadership that Wärtsilä has established in dual-fuel engine technology. The fitting of Wärtsilä 50DF engines onboard the first LNG carriers in 2006 set a trend in the industry and since that introduction, 65 percent of all new LNG carriers have been fitted with Wärtsilä dual-fuel engines. The strong success of this particular engine over the alternatives is based on its superior propulsion efficiency and the clear environmental advantages that operating on gas allows," commented Lars Anderson, Vice President, Wärtsilä Ship Power.

Wärtsilä says it has so far supplied more than 160 ships with its Wärtsilä 50DF equipment.

The 50DF engine is manufactured in various configurations from a 6-cylinder in-line version to an 18-cylinder version in V-configuration, giving 950/975 kW per cylinder and a total maximum mechanical output of 17,100 kW, Wärtsilä says.

The engine speed is 500 or 514 rpm with 50Hz and 60 Hz applications and the maximum thermal efficiency is higher than with any other gas engine, according to the Finnish company.

With regard to emissions, Wärtsilä claims that nitrogen oxide (NOx) emissions are at least 85 percent below those specified in the current IMO regulations when operating in gas mode, and that CO2 emissions are some 25 percent less than those of a conventional marine engine running on diesel fuel.

The sulphur oxide (SOx) and particle emissions are said to be negligible at almost zero percent.