Sfoc Calculations, Example - Man B&W S80ME-C7 Project Manual

MAN B&W Diesel A/S

SFOC calculations, example

Data at nominel MCR (L
Power 100%
Speed 100%
Nominal SFOC:
High efficiency turbocharger
M power is selected as 85% of L
1
M speed is selected as 90% of L
1
M is in this example selected on the same
2
propeller curve as M
1
If the power of M were selected as 75% of
2
L = 17,460 kW and the corresponding speed is
1
86.3% of that in L = 65.6 r/min
1
The savings in g/kWh compared to SFOC in L
Power in Matching point
1 85% x 100% = 85.0%
M = 85%
1 2 85% x 70% = 59.5%
of L
1
3 85% x 50% = 42.5%
4 75% x 100% = 75.0%
M = 75%
2
5 75% x 70% = 52.5%
of L
1 6 75% x 50% = 37.5%
Fig. 2.10.01: Examples of SFOC for different specified MCR points for 6S80ME-C with fixed pitch propeller,
high efficiency turbocharger
S80ME-C
): 6S80ME-C
1
23,280 kW
76 r/min
167 g/kWh
= 19,788 kW
1
= 68.4 r/min
1
SFOC
saving
Data of specified MCR =
Power
Speed
SFOC found:
SFOC
g/kWh
+4
+3
+2
+1
0
-1
-2
-3
-4
6
-5
: -6
1
-7
-8
-9
-10
1.9
-11
6.7
-12
3.2
-13
4.4 -14
-15
9.0
-16
4.9
30% 40%
M
19,788
68.4
165.1
Diagram a
Part Load SFOC curve
Nominal SFOC
3
M
2
4
2
5
50% 60% 70%
42.5 59.5
37.5 52.5 75
2.10
Page 1 of 2
M
1 2
17,400 kW
65.6 r/min
162.6 g/kWh
M
1
1
80% 90% 100% 110%
% of specified MCR
85
178 23 44-9.2
198 42 67-6.0