fuel/lube oil systems - and – propulsion train & shaft line components
TRANSCRIPT
Fuel/Lube Oil Systems
- AND –
Propulsion Train & Shaft Line
Components
References
Required:•Introduction to Naval Engineering
(Ch. 6 pg. 81-84, Ch. 8 143-164).
ObjectivesA. Know the features of a standard shipboard lube oil system.
B. Know the standard safety considerations for both fuel and lube oil systems.
C Know the features of a standard shipboard fuel oil system.
D. Comprehend the theory of operation and key components of shipboard main propulsion power transmission from power source to propellers.
E. Comprehend the effects of cavitation.
Fuel Oil Systems
Tanks
• Storage tanks– Integral part of the ship’s bottom– Volume affects on list/trim of the ship
• Service tanks– 24 hour fuel supply– For immediate use
• Contaminated oil settling tanks– Contaminants pumped to oily waste
tanks– Good oil sent to service tanks
Piping System
• Fill and transfer system– On-loads, transfers, and off-loads fuel
oil– Emergency supply capability
• Stripping system– Used to discharge contaminated oil,
sludge, and water to the settling tank• Service system
– Must deliver oil at the proper temperature, pressure, and purity
Lube Oil System
• Provide lubrication and remove heat generated by bearings in overcoming friction
• Major components:– Sump– Pump– Strainer– Cooler– Bearings
Sump
PumpStrainer
Moving Parts
CoolerSW
Lube Oil System Components
• Storage tanks• Settling tanks• Cooler/heater• Pumps
– AC PLO Pump (Run)– DC PLO Pump (Stby)– Electrically redundant
Additional Components
• Strainers– Prevent passage of grit, scale, dirt,
and other foreign material• Filters• Purifiers
Propulsion Train & Shaft Line
Components
Introduction
• Reduction Gears - fast to slow• Lubrication System - minimize
friction• Shaft components - turbines to the
working medium (ocean)• Propeller - transform rotational
energy into thrust
Reduction Gears
• Purposes– Allow turbine
and propeller to operate at most efficient speeds
– Combine two turbines to common shaft
Reduction Gears• Gear Types
– Straight• excessive vibration• low power-transfer
ability– Helical
• Reduces vibration, quieter
• Higher power transfer ability
• Excessive axial thrust
– Double Helical• Two sets of teeth cut
at opposite angles• Eliminates axial
thrust
Reduction Gears• Reduction Process
– Pinion (small) gear drives reduction (large) gear
– Reduction ratio = turns of pinion : turns of reduction gear
– Double-reduction: reduction in 2 steps (more compact design)
– For naval reduction gears, normally 30:1
Reduction Gears• Articulated
– Shaft between the first reduction gear and second reduction pinion is shortened to reduce the size of the reduction gears
– To allow the shorter shaft to transfer more torque, a quill shaft is installed.
– A quill shaft is composed of two shafts, the outer shaft is hollow, coupled together on one end.
Quill Shaft
Reduction Gears• Locked Train
– Two sets of gears and shafts
– Torque transmitted equally
– Increases ability to transmit torque using smaller components
• Turbine shafts connected to reduction gears by flexible couplings to allow for thermal expansion
Shaft Turning/Jacking Gear
• Electric motor that rotates reduction gears, turbines, and shaft w/o using steam– Cool down turbines
after operation– Prior to startup for
even heating– Position for
maintenance• Can be used to lock
shaft in place– In event of casualty
(i.e., loss of lube oil)
Propulsion Shaft• Shaft is hollow: reduces weight &
increases resiliency• Consists of four sections
– Thrust shaft - from thrust bearing in reduction gears to end of engineroom
– Line shaft - located in shaft alley (supported by line shaft bearings)
– Stern shaft - part of shaft which penetrates hull (supported by Stern Tube bearings)
– Propeller shaft - shaft connected to propeller (supported by Strut Bearings)
Propulsion Shaft• Different sections needed for easy
installation, removal, & maintenance
Shaft Bearings• Designed to
support the moving parts of:– Shaft– Turbines
• Thrust bearings– Absorb axial forces
• Radial (Journal) bearings– Absorb radial forces– Line-shaft, stern
tube, and strut bearings
Propeller• Made of hub and blades & creates the
thrust necessary to propel the ship through the water
• Terms:– Pitch: axial
distance advanced during one complete revolution of screw
– Face: the pressure side
– Back: the suction side
Propeller Types• Constant vs. Variable
Pitch– Variable has the twisted
look– Adv: more efficient over
wide range of speeds• Fixed vs. Controllable
Pitch– In controllable, blades
can rotate on hub to change pitch (change direction)
• Right vs. Left Hand Screw– Viewed from aft of ship– Twin-screw ships have
one of each
Propeller
• Cavitation– Formation and subsequent collapse of
bubbles as propeller turns– Occurs at critical speed
• Effects– Excessive noise– Erosion of blades– Decreased efficiency
Propeller Power vs. Shaft RPM
• Flow a RPM; Thrust (head) a RPM2; Power a RPM3
• So, if 10% power yields 100 RPM, how much power will produce 200 RPM?
10% x%1003 2003
x = 10 * (200/100)3
= 80% power
Take aways
• Classify the main reduction gears• Describe the purpose of each
component in the propulsion train• Draw and label a one line diagram
of a simple lube oils system• Describe propeller cavitation.
What are the negative effects of cavitation.
Questions?