MAN B&W ME-C series for LNG Carriers. Diesel engine technology
MAN B&W offers a full programme of marine diesel engines for every conceivable application.
The low speed engine programme is developed in Denmark and manufactured by a family of licensees at major ship-building centres in the world. Single unit powers range from 2,000 hp to well over 100,000 hp, all for direct coupled installation at propeller speeds from 250 rpm down to 60 rpm for the largest propellers.
The power requirement for an LNG carrier calls for some 40,000 ph, typically two off 60 or 70 cm bore units.
MAN B&W low speed engines hold a world-wide market share of about 65% in their segment.
The introduction of electronically controlled camshaft-less low speed diesel engines is now gaining momentum.
MAN B&W has developed and refined this new technology in its ME-range of engines by combining traditional, proven technologies with enhanced electronic control so as to design engines which, while being both production-friendly and operationally easy to handle, yet will provide all benefits to the owner and operator of contemporary and future software achievements. Another recent demonstration took place with the delivery of a 6S70ME-C engine at HSD in Korea in July 2003. The ME engines have the same speed and power as their MC counterparts.
Camshaft-controlled diesel engines have been the state of the art ever since the birth of reciprocating machinery and have been refined and developed ever since. However, a mechanical cam is fixed once made and, in spite of various mechanical and hydraulic add-on devices like VIT, etc., timing control possibilities are limited with mechanical cams. Not least fuel injection pressure control and variation over the load range have limitations with a cam-controlled engine.
Therefore, the main purpose of changing to electronic control is to ensure fuel injection timing and rate, as well as the exhaust valve timing and operation, exactly when and as desired.
Especially with respect to the fuel injection rate, the control system has been so designed that it is possible to maintain a rather high injection pressure also at low load, without the limitation of the camshaft-controlled engine, where this would result in too high pressure at high load. The ‘cam angle, inclination and length’ are electronically variable. In addition, the ME engine features electronic control of the cylinder lube oil feed, by having our proprietary Alpha Lubricators integrated in the system. With the Alpha Lubrication system, about 0.3g/bhph cyl.oil can be saved, compared with engines with mechanical lubricators.
The electronic control of the engine fuel injection and exhaust valves improves low-load operation, engine acceleration, and gives better engine balance and load control, leading to longer times between overhauls, also by implementation of enhanced diagnostics systems. It will give lower fuel consumption, lower cylinder oil consumption and, not least, better emission characteristics, particularly with regard to visible smoke and NOx.
For the ME engines, the electronic control system has been made complete. Hence, the ME engine features fully integrated control of all functions like the governor, start and reversing, fuel, exhaust and starting valves, as well as cylinder oil feeding.