Engine Load Diagram; Definitions; Operating Curves And Limits For Continuous Operation; Standard Engine Load Diagram - Man B&W L35MC6-TII Project Manual

MAN B&W

Engine Load Diagram

Definitions

The engine's load diagram, see Fig. 2.04.02, de-
fines the power and speed limits for continuous as
well as overload operation of an installed engine
having an optimising point O and a specified MCR
point M that confirms the specification of the ship.
Point A is a 100% speed and power reference
point of the load diagram, and is defined as the
point on the propeller curve (line 1), through the
optimising point O, having the specified MCR
power. Normally, point M is equal to point A, but
in special cases, for example if a shaft generator
is installed, point M may be placed to the right of
point A on line 7.
The service points of the installed engine incorpo-
rate the engine power required for ship propulsion
and shaft generator, if installed.
Operating curves and limits for continuous
operation
The continuous service range is limited by four
lines: 4, 5, 7 and 3 (9), see Fig. 2.04.02. The pro-
peller curves, line 1, 2 and 6 in the load diagram
are also described below.
Line 1:
Propeller curve through specified MCR (M) engine
layout curve.
Line 2:
Propeller curve, fouled hull and heavy weather
– heavy running.
Line 3 and line 9:
Line 3 represents the maximum acceptable speed
for continuous operation, i.e. 105% of A.
During trial conditions, the maximum speed may
be extended to 107% of A, see line 9.
The above limits may in general be extended to
105%, and during trial conditions to 107% of the
nominal L speed of the engine, provided that the
1
torsional vibration conditions permit.
MAN B&W MC/MC-C-TII engines
Engine shaft power, % of A
110
105
7
100
5
95
90
4
1 2 6
85
80
75
70
65
60
55
50
45
40
60 65
Regarding 'i' in the power function P = c x n
A 100% reference point
M Specified MCR point
O Optimising point
Line 1 Propeller curve through optimising point (i = 3)
(engine layout curve)
Line 2 Propeller curve, fouled hull and heavy weather
– heavy running (i = 3)
Line 3 Speed limit
Line 4 Torque/speed limit (i = 2)
Line 5 Mean effective pressure limit (i = 1)
Line 6 Propeller curve, clean hull and calm weather
– light running (i = 3), for propeller layout
Line 7 Power limit for continuous running (i = 0)
Line 8 Overload limit
Line 9 Speed limit at sea trial
Point M to be located on line 7 (normally in point A)
Fig. 2.04.02: Standard engine load diagram
The overspeed set-point is 109% of the speed
in A, however, it may be moved to 109% of the
nominal speed in L
vibration conditions permit.
Running at low load above 100% of the nominal L
speed of the engine, is, however, to be avoided for
extended periods. Only plants with controllable
pitch propellers can reach this light running area.
MAN Diesel
6
8 4 1
2
70 80 85 90
75
, provided that the torsional
1
2.04
Page 2 of 10
O=A=M
7
5
3
9
95 100 105 110
Engine speed, % of A
, see page 2.01.
1
178 39 18-4.1
1
198 69 94-7.1