fuels & lubes
››› emissions and virtually no particulate matter emissions • non-toxic, water soluble and almost impossible to ignite accidentally.
Glycerol-burning engine technology is reportedly proven in combined heat and power plant, and retrofits for existing diesel engines are said to be readily executed, with modifications only required to the external engine aspiration system. A relatively low energy density compared with fossil fuels is partially offset by the fuel’s increased efficiency; and while a greater volume of glycerol needs to be carried for a given range its low hazard nature would allow additional storage in the hull spaces of many vessels. Glycerol is applicable for use in diesel engines of any size but until a comprehensive distribution network is established GLEAMS will concentrate on markets where limited volumes of fuel are required and bunkering typically occurs at a single location. The potential early candidates are identified as offshore support vessels, ferries, survey and pilot boats, fishing craft, dredgers, marine police and small commercial and leisure vessels.
The benign characteristics of glycerol are considered particularly attractive for operators in environmentally sensitive areas. Participating in the GLEAMS project are Aquafuel Research, Gardline Marine Sciences, Lloyd’s Register EMEA, Marine South East and Redwing Environmental. Potential end-users and other interested parties can engage with the project through an online forum by joining the GLEAMS Interest Group.
Dutch tug trials Shell GTL fuel Royal Boskalis’s Rotterdam-based Smit Elbe recently became the first tug in the Netherlands to be fuelled with Shell GTL (gas-to-liquids). The vessel will use GTL for six months to determine whether the fuel can effect a sizeable reduction in emissions without engine modifications. Emission measurements will be taken at regular intervals, the pilot project providing data for a wider emissions reduction policy for the port of Rotterdam. GTL, a liquid fuel produced from natural gas and converted into synthetic diesel by chemical transformation, is claimed to produce much lower emissions of NOx, SOx, particulates and black smoke than regular diesel. The hydrocarbon fuel contains no sulphur, aromatics or toxic constituents. Blending 20 per cent of GTL diesel with conventional diesel reportedly results in a fuel that exceeds almost all international environmental standards for 2015. Built in 2007, Smit Elbe is powered by twin Caterpillar 3516B TA high speed engines, each delivering 1,839kW and arranged to drive an azimuthing propulsion thruster with a fixed pitch propeller.
100 I Marine Propulsion I April/May 2014 Gas fuel option for Q-Max LNG carrier
A project commissioned by Qatari shipping company Nakilat and the LNG producers Qatargas and RasGas calls for the conversion of a low speed diesel engine to burn natural gas as an alternative to heavy fuel oil. One of the company’s large Q-Max LNG carriers will benefit from the retrofit, reportedly the first of an MAN B&W two-stroke engine in service to ME-GI (Gas Injection) specification. The modification – assigned to the Nakilat-
Keppel Offshore & Marine yard in Qatar’s port of Ras Laffan – will enable the engine to handle cargo boil-off gas and meet global emission regulations. The cleaner fuel is also expected to allow longer times-between- overhaul for the engine as well as providing fuel supply flexibility in reaction to market changes. Using boil-off gas as a bunker fuel source in LNG shipping has hitherto been confined to tonnage powered by steam turbine/boiler plant or medium speed dual/tri- fuel diesel-electric machinery. The 266,000m3 Q-Max LNGCs are powered by twin MAN B&W 6-cylinder S70ME-C diesel engines which can be converted to gas-burning GI status.
• LNG carrier newbuildings are now being
specified with MAN Diesel & Turbo’s MAN B&W ME-GI low speed engines allowing cargo boil-off gas to be burned as fuel. Among the references, twin five-cylinder G70ME-GI packages will drive 173,400m3 carriers ordered by Teekay LNG Partners, while twin seven-cylinder G70ME-GI engines will power a pair of 176,300m3 carriers booked by Knutsen OAS. The latter plants are expected to yield fuel savings of more than 30 tonnes of gas per day over an equivalent medium speed dual- fuel diesel-electric installation at a normal ship speed of 15-17 knots.
• Burckhardt Compression reports growing business for its fully balanced Laby-GI compressor to serve LNG carriers specified with MAN B&W dual-fuel two-stroke engines. The Swiss designer’s compressors will inject cargo boil-off gas into the ME-GI engine for use as a fuel; an onboard facility also enables boil-off gas to be reliquefied and returned to the cargo tanks. Laby-GI compressors can handle LNG boil- off gas at suction temperatures down to -1700C without pre-heating the gas or pre-cooling the compressor. A gas-tight housing eliminates gas emissions and losses to the environment.
Preparing to go for gas: one of Nakilat’s Q-Max LNGC fleet More mass flow metering in Singapore
Another two ExxonMobil-chartered bunker tankers in Singapore are now available with the group's own mass flow metering system, taking its Maritime and Port Authority (MPA)-approved fleet to three vessels. Ship operators can reportedly save up to three hours and US$7,000 per delivery, with increased transparency during bunkering. ExxonMobil’s system was developed in collaboration with the MPA and Singapore’s Standards, Productivity and Innovation Board to provide improved accuracy and efficiency, significant cost and time savings, enhanced system
integrity and higher traceability and transparency. Efficiency is raised throughout the
bunkering process by measuring fuel mass directly and reducing the uncertainties associated with density, temperature and other variables such as tank geometry. The supplier estimated cost savings can be achieved by measuring these variables in real time, which also avoids human calculation errors associated with traditional tank dipping. Measurement data is also logged
throughout, offering a transparent and accurate record of fuel transferred to the tanks. MP
www.mpropulsion.com
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