Dual Fuel Marine Diesel Engines – LNG & MDO – the Way Ahead?

By George Backwell at November 09, 2010 08:05
Filed Under: General

Marine Diesel engines, thanks to enormous technological strides in the past few decades, have proven themselves powerful, reliable and efficient, to the extent that by year 2000 motor ships composed no less than 98% of the merchant fleet. Despite these plaudits, regulatory bodies continue to penalise the Diesel engine for exhaust gas emissions inherent in a combustion process using Marine Diesel Oil (MDO) fuel that almost always leaves by-products of oxides of nitrogen, unburned hydrocarbons, and carbon monoxide in the exhaust smoke.

Environmentalists have the expectation that technology will solve all political and economic problems, and will not be disappointed to hear that developers have succeeded in harnessing low emission Liquid Natural Gas (LNG), a  clean fuel with lean burn combustion characteristics, to power the engine invented by Rudolf Diesel in 1897. Many analysts confirm the recent prediction of Klaus Deleroi, Senior V-P, MAN Diesel & Turbo SE, that: "When it comes to ship-propulsion technology, the future is gas. Not only for LNG carriers, but also for cargo vessels, ferries and even cruise liners."  In the light of such a bold prophesy, a brief look back may be helpful.

Boil-off cargo LNG was originally used in LNG carriers themselves to power steam turbine plant, but it was not until 2002 that the world's first LNG powered cargo vessel, Viking Energy came into service powered by a Dual Fuel system that enabled the main propulsion plant to run on either LNG or liquid fuel (in July 2010 a fourth similar Dual Fuel vessel was on order). It is this system that is becoming favored in some LNG carriers today. How is fuel-injection managed in the latest Dual Fuel technology?

The new MAN Diesel & Turbo SE Duel Fuel engines installed in the recently launched LNG carrier, Castillo de Santisteban, employ a common rail, spark inducing, 'micro-pilot' fuel-injection system for the engine when in LNG mode, and when running on liquid fuel a separate conventional camshaft operated fuel injection system takes over. MAN announced on 27, October 2010 that their 51/60DF engines installed in Castillo de Santisteban (when operated in LNG mode) already comply by a considerable margin with IMO Tier-lll limits for NOx without need for exhaust gas treatment. It appears the Diesel engine may soon enter a new LNG/MDO-fuelled era.

 

Comments (2) -

Good article and very cute picture. The only recommandation I would do is to lower the temperature of LNG in the cargo tanks -162 C.

Mauro Brattich |     11/9/2010 10:36:27 AM #

I like the drawing too! but did you know that the Q-Max and Q-Flex LNG Carriers are "double- hulled" in the cargo areas only,the insulation used is not Perlite but polystyrene & polyurethane that begs the question that the LNG containment tanks relief valves may be undersized. A SHIP TOO FAR!!
                                                           D.R.

D.R. |     11/17/2010 8:30:15 AM #

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