New Diesel by MAN Fulfils Container Ship Low-load Engine Needs

By George Backwell at July 28, 2012 08:16
Filed Under: General

Container ship operators looking for the lowest possible fuel oil consumption at any engine load will be interested to hear word from MAN Diesel & Turbo that the first super-long-stroke large bore two-stroke engine specifically designed for them, the S90ME-C9.2, has just successfully completed trials on Hyundai Heavy Industries Engine & Machinery Division’s  test bed.

Marine Diesel Engine MAN S90ME-C9.2: Photo credit Man Diesel & Turbo

The new engine, of reduced size for container ship engine rooms (although the largest ever designed by MAN) is based on the VLCC-optimised S90ME-C8 engine, as operators look to reduce operating costs through slow steaming, turbocharger cut out and low-load engine optimisation; all of which are offered by the new engine.

 Engine Design ConceptMAN S90ME-C9.2

Low-speed two-stroke main engines of MAN’s existing MC type, with a chain driven camshaft, have limited flexibility with regard to fuel injection and exhaust valve activation, which are the two most important factors in adjusting the engine to match the prevailing operating conditions.

A system with electronically controlled hydraulic activation provides the required flexibility, and such a system forms the core of the ME ‘Engine Control System’
 
Control functions are exercised over the fuel pressure booster, where oil pressure is controlled by an electronically controlled proportional valve; the exhaust valve, which is opened hydraulically by means of a two-stage actuator (and closed by an ‘air spring’); and the starting valves, which are opened pneumatically by electronically controlled ‘On/Off’ valves.

In the hydraulic system, normal lube oil is used as the medium, filtered and pressurised by a Hydraulic Power Supply unit mounted on the engine or placed elsewhwhere in the engine room.

By electronic control of each of these valves accord­ing to the measured instantaneous crankshaft position, the Engine Control System thus fully controls the combustion process.

Optimised SFOC (Specific Fuel Oil Consumption)

In their drive to reduce CO2 and at the same time fuel consumption, ship owners have need in economically challenging times to operate their ships at a reduced ship speed and consequently at reduced engine load which demands greater engine operational flexibility.

This flexibility is obtained in the new engine by means of different ‘Engine Running Modes’, which are selected either automatically, depending on the operating conditions, or manually by the operator to meet specific goals. The basic running mode is ‘Fuel economy mode’ to comply with IMO NOx emission limitations.

The Three MCR Modes (Graph courtesy of MAN Diesel & Turbo)

The engine is delivered with the following three different MCR (Maximum Continuous Rating) optimisations, as shown above:

1)  High-rated MCR with part load optimisation
2)  De-rated MCR optimisation with part-load tuning
3)  De-rated MCR optimisation with low-load tuning

The S90-C9.2 engine is a very large unit indeed and will deliver a torque of 8.5 million Nm at 84 rpm and a total output of 69,720 kW. It is to be installed in a container ship built at Samsung Heavy Industries for Hong Kong-based Orient Overseas Container Line.

 

 

 

 

Comments (2) -

Most big engines, such as this S90ME monster, use 2-stroke cycle for its higher power density. Currently we have to choose between 2- and 4-cycle engine - each has pros-and-cons.  

We don't have the dilemma anymore. There is a new stroke technology called D-Cycle(TM), or the differential-stroke cycle. It is a hybrid of the 2-/4-cycle and is more powerful than 2-cycle and cleaner than 4-cycle with operational control of the 4 strokes during a cycle.  

D-Cycle(TM) has the flexibilities during engine operations to optimize (1) stroke displacements and durations for part/low-load operations for fuel savings and (2) stroke ratios among the 4 strokes for more enhanced fuel savings. The 4 strokes can be optimized all the time during engine operations.    

MJ Yan |     7/29/2012 8:53:52 AM #

MAN has a (much) smaller monster engine, L35/44DF, which delivers 3.2MW to 5.3 MW (versus the 70MW S90). The big monster is a 2-cycle, while the smaller monster is a 4-cycle.

4-cycle has only half of the engine (cylinders) propelling the ship, while the other half are "catching" a breath. This is just a gross waste of precious engine structure. But 2-cycle has its share of issues. So their hybrid - D-cycle(TM) - is the way to go.    

MJ Yan |     9/5/2012 10:40:20 AM #

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