Demonstration of dual-fuel engine for LNG carriers

New 'fuel sharing' feature to give operators the option to use liquid and gaseous fuel at the same time.

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Updated on 06 Apr 2016 13:57 GMT

On April 5, 2016, Winterthur Gas & Diesel (WinGD), together with Doosan Engine Co., Ltd demonstrated the first low-speed, low-pressure Wärtsilä 6-cylinder X62DF (W6X62DF) engine for a commercial application.

The event took place at Doosan's works in Changwon, Korea, and the W6X62DF engine is also the first X-DF engine to be sold for the new generation of very large liquefied natural gas (LNG) carriers.

The engine is currently being tested by Doosan before delivery and is one of a pair that will power the first of two 180,000-cubic-metre LNG carriers being built by Samsung Heavy Industries Co., Ltd (SHI) in Korea for SK Shipping Co., Ltd and Marubeni Corporation. The vessels are due to operate on long-term charter to France's Total S.A.

Operating modes and data

In addition to witnessing the W6X62DF running under a number of load and fuelling conditions, visitors to the Changwon event are said to have also seen the validation of its engine control features, tuning, economy and emissions. Key aspects examined during the demonstration included the engine's design fuel consumption and its Tier III NOx emissions compliance in gas mode without any additional exhaust treatment.

CAPEX and OPEX benefits

At a technical seminar following the W6X62DF demonstration at Changwon, WinGD and Doosan also stressed the cost benefits of X-DF technology with low-pressure gas admission.

Reductions in capital expenditure (CAPEX) of 15 to 20% are said to be possible compared to other low-speed dual-fuel engine technology. This has been attributed to the simpler and lower cost LNG fuel gas handling system needed for gas admission at pressure below 16 bar. On the operating expenditure (OPEX) side, gains are expected, especially for LNG carriers, since no high-pressure gas compression system external to the engine is needed to enable the use of natural boil-off gas (NBOG).

A further advantage, according to WinGD and Doosan, is that WinGD X-DF technology allows stable operation on gas across the entire load range from 5% to 100%, so that there is no need to increase liquid fuel injection under any situation where sufficient gaseous fuel is available. Moreover, at around only 1% of the total heat released during combustion, pilot fuel consumption is said to be lower than with other low-speed dual-fuel engine technology.

Fuel sharing

During the technical seminar, WinGD also announced that a 'Fuel sharing' feature will be available on X-DF engines later this year. This feature aims to give vessel operators broad flexibility to use liquid and gaseous fuel at the same time if economically viable at a given time.

Type-approved technology

The first engine employing WinGD's X-DF technology with low-pressure gas admission, an RT-flex50DF, has already successfully completed classification society type approval testing (TAT).