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MAN B&W 2.04
Example 4: Special running conditions.
Engine coupled to fixed pitch propeller (FPP) and with shaft generator
Layout diagram Load diagram
Power, % of L 1
100%
L 3
L 4
7
5
4
1 2 6
M Specified MCR of engine
S Continuous service rating of engine
O Matching point of engine
A Reference point of load diagram
MP Specified MCR for propulsion
SP Continuous service rating of propulsion
SG Shaft generator
Also for th<strong>is</strong> special case in example 4, a shaft generator <strong>is</strong>
installed but, compared to example 3, th<strong>is</strong> case has a specified
MCR for propulsion, MP, placed at the top of the layout
diagram.
<strong>Th<strong>is</strong></strong> involves that the intended specified MCR of the engine
M’ will be placed outside the top of the layout diagram.
One solution could be to choose a larger diesel engine with
an extra cylinder, but another and cheaper solution <strong>is</strong> to reduce
the electrical power production of the shaft generator
when running in the upper propulsion power range.
MAN B&W ME/ME-C/ME-B/-GI-TII engines
1 2 6
Propulsion curve
for fouled hull
and heavy weather
Engine speed, % of L 1
M
A=O
M
S
MP
SG
SP
100%
L 1
7
L 2
MAN Diesel
Power, % of L 1
100%
Engine service curve for fouled
hull and heavy weather
incl. shaft generator
1 2 6
Propulsion curve
for fouled hull
and heavy weather
Engine speed, % of L 1
Point A and M of the load diagram are found:
Line 1 Propeller curve through point S
Point A Inter<strong>section</strong> between line 1 and line L 1 – L 3
Point M Located on constant power line 7
through point A and with MP’s speed
Point O Equal to point A
4
3.3%A 5%A
Page 9 of 10
M
A=O
M
S
MP
SG
100%
In choosing the latter solution, the required specified MCR
power can be reduced from point M’ to point M as shown.
Therefore, when running in the upper propulsion power range,
a diesel generator has to take over all or part of the electrical
power production.
However, such a situation will seldom occur, as ships are
rather infrequently running in the upper propulsion power
range.
Point A, having the highest possible power, <strong>is</strong> then found at
the inter<strong>section</strong> of line L 1 – L 3 with line 1 and the corresponding
load diagram <strong>is</strong> drawn. Point M <strong>is</strong> found on line 7 at MP’s
speed, and point O=A.
Fig. 2.04.07: Special running conditions. Engine coupled to a fixed pitch propeller (FPP) and with a shaft generator
L 3
L 4
SP
L 1
7
5%L 1
L 2
3 3
178 06 35�1.8
198 69 93-5.1