MAN Diesel & Turbo has designed an LNG-fueled two-stroke ME-GI engine for DNV’s mew concept Quantum 9000 container ship. DNV launched the Quantum concept a year ago; the new Quantum 9000 concept has been designed to be more efficient and environmentally friendly than existing ships without introducing major complications when the ship is to be built or operated.
|The ME-GI engine. Inset shows ME-GI engine add-ons compared to the standard ME engine. Click to enlarge.|
The ME-GI dual-fuel engine is not a new engine technologically, but a development of the MAN B&W low-speed electronically controlled ME family of engines. In 1994, all major classification societies approved the GI concept for stationary and marine applications. Technically, notes MAN Diesel & Turbo, there is only a small difference between fuel and gas-burning engines. The gas supply line is designed with ventilated double-wall piping and HC sensors for safety shutdown. The GI control and safety systems are add-on systems to the normal engine systems.
Apart from these systems on the engine, the engine and auxiliaries will comprise some new units. The most important aspects, apart from the gas supply system, are:
- Control oil supply for actuation of gas injection valves; and
- Inert gas system, which enables purging of the gas system on the engine with inert gas.
The GI system also includes a control and safety system, comprising a hydrocarbon analyser for checking the hydrocarbon content of the air in the double-wall gas pipes.
The control and safety system is designed to “fail to safe conditions”. All failures detected during gas fuel running, including failures of the control system itself, will result in a gas fuel stop/shutdown and a changeover to HFO (heavy fuel oil) operation. Blow-out and gas-freeing purging of the high-pressure gas pipes and of the complete gas supply system will follow.
Changeover to fuel oil mode is always done without any power loss on the engine.
The pilot oil for LNG mode can be low-sulphur marine gas oil for ignition and back-up fuel, particularly useful when sailing in emission controlled areas (ECA). This means that the ECA sulphur emission requirements can be met even when the two-stroke main engine has to switch off gas operation at very low loads.
By making simple modifications, we have achieved high fuel efficiency, high fuel flexibility and high reliability. The Quantum 9000 introduces LNG to the preferred container ship propulsion system and thus makes LNG more available to container ship owners.—Lars Ryberg Juliussen Senior Manager, MAN Diesel & Turbo
In addition to having dual-fuel engines, Quantum 9000 achieves full fuel flexibility and at the same time meets the upcoming ECA requirements. The ship’s energy efficiency is also better than that of conventional existing container ships.
In addition to the use of gas, the engine solution includes waste heat recovery to improve the energy efficiency and exhaust gas circulation to reduce the emissions. A number of other improvements have been made possible by adopting a twin island arrangement, such as increased cargo capacity and reduced need for ballast water. Also the improved sightline from the bridge, which contributes to increasing the safety in operation, and the minimum fuel consumption, can be mentioned.