Use of High Efficiency Propeller
Designs to Optimise Propulsive
Efficiency
Adrian Miles
Managing Director
Stone Marine Propulsion
Presented at ENERGY EFFICIENCY PRACTICE & PROSPECTS
Athens 27/11/2012
STONE MARINE GROUP
Stone Marine Propulsion
Supply : Large Propellers & Sterngear
Stone Marine Services
Servicing : Propellers & Sterngear
Stone Marine Shipcare
Servicing : Propellers
Stone Marine Singapore
Supply : Small Propellers & Sterngear
Stone Marine Namibia
Subsidiary of Stone Marine Services
Stone Marine Bruntons
Supply : Small Propellers & Sterngear
Summary
1. The Stone Marine 'NPT' high efficiency propeller
2. Propeller Optimisation Basics.
Case study 1:
3.
'Seahorse' 35k Bulk carrier
Optimise Propeller Revs
Slow steaming:
Case study 2:
5. Conclusions
Container Vessel,
De-rate Engine and fit optimised Propeller
NPT Propeller
- NPT = 'New Profile Technology'
- 2-4% Efficiency Gain
-Smaller Optimum Diameter
-Smaller Blade Surface
-Significant Weight & Inertia Reduction
-Lower Pressure Pulses
-Same Cost as Conventional Propeller
NPT Propeller – How it Works
-Reduced Pressure Peak on Section
-Blade Surface Area Reduced
- Viscous Drag Reduced = Improved
Efficiency
Measurements by HSVA(Hamburg)
Pressure Impulses
Trials Powers
104.0%
Pressure
Gauge
103.0%
Camera
102.0%
Relative101.0%
Propulsive
Efficiency
5
0.8×σdesign
MPNo.90(NBS)
4
Amplitude[Kpa]
100.0%
99.0%
MPNo.91
3
2
1
98.0%
1
0
Propeller
Conventional
PAI
4
NBS
8
12
Order.
16
20
Propeller Optimisation Basics
Slow turning, Large Diameter = Highest Efficiency
Engine Layout Selection
Maximum
Continuous Rating
(MCR), Power and
RPM selected from
'layout' box
Propeller Diameter
Maximise Diameter
Select RPM to Suit
Case Study 1: Seahorse 35 Bulk Carrier
(Source Grontmij & Schmidt Maritime)
Case Study 1: Seahorse 35 Bulk Carrier
Case Study 1: Seahorse 35 Bulk Carrier
Version 3
Comparison between optimum diameter conventional
and NPT Propellers
Case Study 1: Seahorse 35 Bulk Carrier
Version 3 – Model Test
Summary of Fuel Oil Savings
SEAHORSE 35 Version
1
2
3
4
5
1. Main Engine Maker
[-]
MAN B&W
MAN B&W
MAN B&W
MAN B&W
MAN B&W
2. Main Egine Type
[-]
5S50
5S50
5S50
5S50
5S50
3. Main Engine Mark
[-]
MC-C7.1 TI
ME-B8.1 TII
ME-B9.2 TII
ME-B9.2 TII
ME-B9.2 TII
4. Main Engine Tuning
[-]
127rpm
110rpm
99rpm
99rpm
Part Load
5. Propeller
[-]
5,54 m NPT
5,80 m Wärts.
5,90 m NPT
5,90 m NPT
5,90 m NPT
6. Becker MEWIS Duct®
[-]
No
No
No
Yes
Yes
7. Design Speed 1)
[knots]
14,0
14,0
14,0
14,0
13,0
8. SMCR2)
[kW]
7.500
6.900
6.350
6.050
4.700
9. NCR3)
[kW]
6.082
5.913
5.670
5.440
4.230
10. NCR verified by:
[-]
Sea trial
Sea trial
Tanktest
Tanktest
Tanktest
11. % of SMCR
[%]
81%
86%
89%
90%
90%
12. NCR Index
[-]
100%
97%
93%
89%
70%
[g/kWh]
166,8
167,2
161,0
159,9
158,6
[%]
100%
100%
97%
96%
95%
[mt/day]
24,3
23,7
21,9
20,9
16,1
[%]
100%
97%
90%
86%
66%
13. SFOCNCR
14. SFOC Index
15. M/E FOCMDO4)
16. FOC Index
1)
Design speed at scantling draft of 10,1 m
2)
NCR : Main engine power to reach design speed at scantling draft including 15% sea margin and 1% shaft loss
3)
M/E fuel oil consumption at NCR based on MDO (LCV 42,700 kJ/kg). M/E makers SFOC tolerance of 5% is not incl.
Oct. 2012
Schmidt Maritime
14
Summary of EEDI
SEAHORSE 35 Version
17. EEDI1)
18. EEDI Index
19. EEDI Base Line
20. EEDI blw. Base Line
1)
1
2
3
4
5
[g/DWTxnm]
6,53
6,23
5,60
5,32
4,50
[%]
100%
95%
86%
81%
69%
[g/DWTxnm]
6,54
6,54
6,54
6,54
6,54
[%]
0%
5%
14%
19%
31%
Main engine makers SFOC tolerance of 5% is included.
IMO Energy Efficiency Design Index (EEDI) - BULK CARRIERS
(EEDI Base Line = 961,79 x Capacity-0,477)
EEDI [g-CO2/DWTxnm]
7.0
Phase 0 (-0%) from 1/1 2013
Phase 1 (-10%) from 1/1 2015
6.5
Phase 2 (-20%) from 1/1 2020
6.0
Phase 3 (-30%) from 1/1 2025
Version 1
5.5
Version 2
5.0
Version 3
Version 4
4.5
Version 5
4.0
30,000
32,500
35,000
37,500
40,000
Capacity [DWT]
Oct. 2012
Schmidt Maritime
15
Case Study 2: De-rating Large Container Vessel
12 to 6 cylinders
Propeller Speed (rpm) v Engine Power (kW)
26 to 18 kts (max)
75000
70000
65000
6 to 3 blades
60000
55000
12 Cylinders 72240
kW
Pb (kW)
50000
45000
6 Cylinders
33750kW
+6.5% Propeller
40000
Existing 6 Blade
Propeller
35000
3 Blades 97 RPM
30000
+6% SFOC saved
25000
Total +12% saving
20000
15000
80
85
90
RPM
95
100
105
2.6 years payback
on $1 700 000
Containership De-rating
3 and 4 blade options
Existing Propeller
6 Blades
29000
Pb (kW)
24000
19000
3 Blades NPT
14000
9000
4 Blade NPT
4000
10.0
11.0
12.0
13.0
14.0
15.0
16.0
17.0
Vs (knots)
18.0
19.0
20.0
21.0
Case Study 3: De-rating Large Container Vessel
NPT Propellers Supplied
Over 75 NPT Propellers on order or supplied
Over 100 of predecessor 'NBS' types in Japan
Largest NPT to date 10.4m, 67t mass
Conclusions
Large diameter, slow turning best for efficiency
Newbuilds should use this principle to set MCR
Retrofits can use this principle to de-rate engine
NPT Propeller smaller diameter = lower rpm = higher
efficiency