engine

Transcription

engine

WARTSILA MODERn 2-Stroke
engines
Athens, 23nd January 2014, Chios Marine Club
Dionysios Antonopoulos
Wärtsilä Greece, Manager 2-Stroke Technical Services
Wärtsilä 2-stroke / D.Antonopoulos
Historical development of engine parameters
Historical development:
Gradually higher stroke/bore ratio
Gradually increased propeller diameter
Gradually lower rotational speeds
(1980s RTA58 127rpm – 1990s RTA62 113rpm – 2000s RTA58T 105rpm)
Increasing vessel efficiency - Main engine
Fuel prices
Freight rates
Environment
Modern new low speed engines adapted
in modern vessel designs
High stroke to bore
Low rpm (Larger propeller)
Electronically controlled common rail
(Tunings-flexible operation)
De-rating potential
Larger propeller
Longer stroke
De-Rating
Engine layout
Higher propulsive
efficiency
… depending on prop.
diameter
Area of CMCR- selection
during 1990 - 2007
in the 80ties
after 2008
Lower specific
fuel consumption (BSFC)
Note:
Size - Shape of layout field is
engine type dependent.
New Generation W-X62&72
W-X62&72 – Advantages from flex system
• Common rail system – overview
– Rail Unit
• High pressure rails for fuel and servo
oil
• Activation of exhaust valve by
electronically controlled Exhaust
Valve Control Unit
– Supply Unit
• Pressurizing of fuel
and servo oil
– Redundant piping for fuel
and servo oil between
Supply Unit and Rail Unit
W-X62&72 – Design concept
• Concept running gear
82T
– Crankshaft
• Semi built execution in one part
• Several versions / materials
– Conrod / cross head
82T
• Guide shoe in one piece with white metal lining
• Straight cross head pin
– Bearings
82T
• White metal main, cross head and big end
bearing
– Piston cooling / cross head lubrication
• Knee lever
– Gear wheels
82T
• Compact aft end arrangement of
supply unit for short gear drive
82T
• Concept engine structure
– Column
82T
• Double wall execution
– Bedplate
X35
• Single wall execution
– Gear housing
82T
• Separate gear housing
– Tie rods
82T
• Single tie rods
• Concept hot parts
– Cylinder liner
82T
• Self-supporting execution (no supporting ring)
82T
– Cylinder cover
• Round shape, flat surface
82T
– Cylinder jacket
• One-piece or split execution
– Piston
82T
• Jet-shaker cooling
• 3 piston rings
– Exhaust valve
82T
• Electronically controlled, hydraulically actuated
– Piston gland box
82T
W-X62&72 – High reliability
• Cylinder cover & valves
– 6 cylinder cover bolts
– Cylinder cover
• Bore cooling
• Round shape
– Exhaust valve
• Water cooled exhaust valve cage
• Bore cooled exhaust valve seat
• Hydraulic valve drive and air spring
– 3 fuel injection nozzles
– Electronically controlled starting air valve
W-X62&72 – High reliability
• Piston
– 3 piston rings
• Introduced on RT-flex82C&T
– Well-proven jet-shaker piston oil
cooling concept
– High top land
– Stress and temperature optimized
by FE calculation
• Position and number of cooling bores
optimized for even temperature
distribution on piston crown
• Concept flex system
82T
– Supply unit
• Compact supply unit for fuel and servo pumps
• Size IV (V4) fuel pumps
• Driven by gear wheels
– Fuel injection
X35
• Time controlled fuel injection valves from
L’Orange
• FAST injection nozzles as on other RT
engines
• Mechanical flow limiters
– Rail unit
X35
• Single wall fuel and servo oil rail pipe
• Pre-assembled rail unit box
• Fuel injection control
– Three time controlled fuel
injection valves per cylinder
(from L’Orange)
• Solenoid actuated
• Optimized injection control at
all engine loads
– Mechanical flow limiters
• Proven ICU based design
– Flex proven non return
valves in rising pipes (for
case of pipe breakage)
– Single wall rail pipe
• Round bore
• Fuel injection valves
– Time controlled
– Design is based on proven 4-stroke HFO
technology
– First 2-stroke application on X35 & X40
– Stretched X35/40 injector for X62 & X72
• Same moving parts
– 24 VDC solenoid actuation (low voltage)
– FAST injection nozzle added
(FAST = Fuel Actuated Sacless Technology)
• Validation with conventional injectors on RTflex60C and RT-flex96C
– Max. > 5000 hours
non-FAST
FAST
W-X62&72 – 5 years between overhaul
• Water separation
– Underslung design for efficient
natural water separation
• Air swirl supported water droplet
separation
– Radial acceleration of air flow leads to
separation of > 80% of the water
droplets
• Additional water separator element for
high efficiency
• Effective drain (pressure balanced)
• WECS-9520
FCM-20 cylinder modules
Control of cyl. lubrication by ALM-20
Crank Angle Sensor (CAS)
External power supply E85
One box per cylinder
ECR Manual Panel
Control Room
2 x 230VAC
Propulsion control
Speed ctrl. / RCS / SS
Alarm & Monitoring
System
CANo pen or ModBus
#1 Module Bus #2
ModBus #4
ALM-20
© Wärtsilä Land & Sea Academy
FCM-20
Cyl. 5
FCM-20
4-20 mA
Cyl. 4
Actuator for
Fuel Pump
Actuator f or
Fuel Pump
Servo oil
Pump
Servo oil
Pump
Servo oil
Pump
CANopen Module Bus #4
Cyl. Lubrication
Modules
ALM -20
ALM-20
E90 SIB
E95.6
CANopen / PWM
PWM
PWM
PWM
RT-flex Engine
Actuator for
Fuel Pump
Rail Unit
Page 2
ALM-20
ALM -20
Chapter 40
21-Oct-08
Actuator f or
Fuel Pump
Servo oil
Pump
ALM -20
CANopen Module Bus #n
Starting Valve
VCU
Engine
room
CANopen Module Bus #n-1
4 .. 20 mA
E95.1
4 .. 20 mA
ModBus #3
FCM-20
Cyl. 3
FCM-20
Cyl. 2
Cyl. 1
CCM-20 #5
CCM-20 #4
CCM-20 #3
CCM-20 #2
IOM-10
CCM-20 #1
FCM-20
CANopen System Bus
Local Manual
Panel
Power
Supplies
CANopen Module Bus #3
WECS-9520
3x ICU
flexView
online
spare FCM-20
–
–
–
–
–
FCM-20
CCM-20 cylinder modules
Integrated control of cyl. lubrication
Crank angle detection at gears
No separate power supply
One big rail box E90/95
MCM-11
–
–
–
–
–
Cyl. 6
• UNIC
Crank-Angle
SSI Bus
CA 2
CA 1
W-X62&72 – Low system oil losses
• Piston rod gland box
– Dismantling up- and downwards
– Ring package
• 2 highly efficient pre-scraper rings
• 2 gastight sealing rings
• 4 highly efficient oil scraper rings
with grey cast iron lips
– High contact pressure between oil
scraper rings and hard piston rod
– Big oil drain area to re-circulate
system oil
– Quasi-zero leakage to neutral
space
– Already running well in other
engine types
0
W-X62&72 – 5 years between overhaul
Optimized liner wall
temperatures
• Cooling bore
insulation for
low ratings
Anti-polishing ring
• Mid-stroke
insulation
• Shorter water guide jacket
• Adapted water cooling
Pulse Lubricating System
3 piston rings
• Top ring gas-tight
• Cr-ceramic coated
• Pre-profiled
Piston ring grooves
with thick chromium
layer
Liner plateau honed
Piston skirt with bandage
• ICC principle
– Control system compares measured cylinder pressure to target values
– Automated adjustment of injection begin (close loop control)
– ICC integrated in UNIC control system
Measured
values
Target
values
Low load operation
NO LIABILITY WHETHER DIRECT, INDIRECT, SPECIAL, INCIDENTAL OR CONSEQUENTIAL IS ASSUMED WITH RESPECT TO THE
INFORMATION CONTAINED ON THIS SECTION. THIS PRESENTATION IS INTENDED FOR INFORMATION PURPOSES ONLY.
Involvement of Wärtsilä in slow steaming trend
Though many ship owners and operators
acted on their own responsibility, Wärtsilä
was involved to create guidelines for
operation with slow steaming
• Service bulletin RTA 79.2 /RT-flex 08.2 on
low load operation
• Active experience exchange with operators
• Offering of optimized engine tuning for slow
steaming
Involvement of Wärtsilä in slow steaming trend
• Service bulletin RT-148
Cylinder lubrication at low load
operation
• Use of intermediate BN
lubrication
• Service bulletin RT-93
Piston running behaviour at
low load operation
Key areas of attention for low load operation
Concerns of continuous operation at reduced load operation
• Incomplete combustion
– Poor atomisation with lower injection pressure (only RTA)
– Increased fouling and carbon deposits likely
• Lower airflow leading to high exhaust gas temperatures
– Critic
– at region after auxiliary blowers cut out / before cut in
– Possibility of very high exhaust, thus component temperatures
• Cold corrosion in exhaust system (pipes and boiler/economizer) with
auxiliary blowers on
– Through condensation of corrosive vapours
– Possible when observing very low engine temperatures during very low load
operation
– Main concern presented is Exhaust Gas Boiler tube stack
• Piston running behaviour
Low load operating experience
Endurance tests
Few deposits on turbocharger and exhaust system components
• Approx. 1200rhrs 10 – 11% load
• Regular loading up for nut shelling and soot blowing
•
Optimised Cylinder Oil feed rate based on inspections
Low load operating experience
Good condition in piston underside, combustion chamber & economizer
Feedback from customers
General customer statement:
• Unexpected low troubles with slow
steaming
Technical issues:
• Generally stable engine conditions
• No troubles with exhaust gas
system (fire, fouling, …)
• No large deposits in combustion
chamber
• Turbocharger efficiency kept by
regular cleaning and load ups
• Economizers with good behaviour
• Care to be taken for proper cylinder
lubrication (feedrate & BN)
Recommendations for low load operation
Avoid incomplete combustion
• Ensure good combustion through optimal
spray characteristic
• Ensure correct injector nozzle condition
• Cracking pressure correctly set
• Look for carbon deposits on and around
nozzle indicating poor spray
• Maintain higher fuel temperatures
• Aim to achieve lower viscosities, 12,13 cSt
Advantage of RT-flex engine with high
injection pressure at any load
Avoid cold corrosion and fouling
– When possible, keep exhaust gas temperatures above 230°C
– Avoid temperatures below 160°C at economizer outlet
– Regular load up to 70% load (2 times per week recommended – better few times with
slow load changes than often with quick load changes)
– Ensure good injection equipment
– Soot blowing of economiser
– The turbocharger(s) should be cleaned according maker’s recommendations
– Inspection of manifold and turbo grid periodically
– More regular piston underside inspections and cleaning necessary to confirm correct
lubrication rate
Avoid hot engine
– When possible, keep exhaust gas temperatures before TC below 450°C to avoid
excessive combustion chamber temperatures and high temperatures after TC
– Ensure good TC efficiency through regular load up and washing of turbocharger
Further suggestions & field experiences
• Observing turbocharger speeds at a constant load over the period of slow
steaming can provide an indication of fouling of the engine
• Increased turbocharger speeds can indicate nozzle ring fouling
• Can be avoided by regular loading up and cleaning according to service bulletin
• Current to electric motors of auxiliary blowers
• Avoid loads with on and off operation of auxiliary blowers
put on auxiliary blower
in permanent mode
• When operating in manual operation, caution should be take not to exceed normal
blower cut in and out pressures, thus rated current of motor
• Electrical starter cabinet may need observation / external ventilation when blower
operating continuously
Exhaust gas boiler operation
• Reduced steam generation at low load
• At very low loads, exhaust gas boiler is not operational
• Auxiliary boiler might be required to generate steam
• Fouling of boilers
• From several customers no troubles with boiler operation confirmed
• Good operation with exhaust gas temperatures down to 220°C reported – limit is
160°C on exit side
• If required, bypass of exhaust gas boiler can reduce soot build, and oil fired
auxiliary boiler to be used
Ensure good piston running behaviour
• Higher cooling water temperatures
– Reduces condensation (and thermal stresses)
– H.T. jacket maintain in highest possible
temperature range (towards 95°C)
• Search for optimum cylinder oil feed rate
– Regular inspections
– Feed rate adjustment depending upon liner / ring
condition, sulphur content of fuel, cooling water
temperature and efficiency of scavenge air
cooler and water separator
– Watch for hard calcium deposits or overly wet
ring pack
– Lower liner wall temperatures may increase
condensation, therefore sufficient lubrication is
necessary to avoid corrosion
• Careful load up
Load-up should be done very carefully in order to
avoid adverse piston running condition(Service
Bulletin RT-84)
Piston running experience with slow steaming
Black marks on liner running surface due
to low load operation
• Distributed across running surface
• Described as calcium sulphate
and soot adhering to surface
• Removed upon load up of engine
(can leave lighter/white patches)
• Adjust lubrication oil feed rate
Piston running experience with slow steaming
Cases of CC ring damage
• Combination of very low load
and high sulphur content
(>3%)
• Ring appears slightly spongy,
cracks develop and open
• Appearance of defined area
with adhesive wear
Conclusion:
• Increase of feed rate at low
load operation and high
sulphur content
service bulletin RT-93
Ring recovery example on RT-flex96C
Rings: 2800rhrs
Rings: 3600rhrs
h
100709_RT-93
_low_load_lubricat...
Performance optimisation: Slow Steaming Upgrade Kit
•
•
•
•
Turbocharger cut-off at low engine loads
Increased scavenge air pressure
Higher fuel efficiency at low load
Fully automated control of the valves
“FAST” nozzle benefits
Reduced fuel operating costs by 1%
• Fuel consumption expected to reduce by nearly
1 % at part load
Reduced maintenance costs
• Improved combustion lead to less fouling in the
exhaust gas ways and boiler, reducing
frequency of cleaning
• Less deposits in combustion chamber may
increase piston running component lifetime and
improve their behaviour
Environmental friendliness
• Reduced HC and CO emissions
• Reduced CO2 emissions at part load
*Currently available only for RT-flex engines
First vessel order - Wärtsilä 2s low-pressure DF engine
Owner
Shiptype
Service speed
Shipyard
Order date
Ship delivery
Engine type
38
© Wärtsilä
Terntank Rederi A/S, Sweden
15000 tdw Tanker, 2 vessels
14.5 kn
AVIC Dingheng, China
November 2013
Feb and May 2016
5RT-flex50DF, CMCR 5750 kW / 99 rpm
Concept
A few key technologies make the difference...
Micro-pilot common rail system
Pre-chamber technology
Gas admission system
Engine Control & Automation
system
Concept
‘Pre-mixed lean-burn’ combustion
The Principle
Engine operating according to
the Otto process
Pre-mixed ‘Lean burn’
technology
Low pressure gas admission at
’mid stroke’
Ignition by pilot fuel in
prechamber
Scavenging
Compression/
gas admission
Ignition
expansion
Machinery space concept
Engine room:
gas safe area
Blower
Air in
G
V
U
Gas detectors in annular
space
Fuel
Gas
Forced engine room ventilation
Gas safe area
Double wall fuel gas pipe
GVU (Gas Valve Unit) enclosure
Gas venting pipe
Annular pipe / GVU enclosure venting
Low pressure DF - operation
‘Port-to-port’ operation on gas
Entire voyage in gas mode
• Engine start on diesel for safety
check
• Transfer to gas at low
load/idling
• Transfer to diesel before stop
In case of FPP, reversing/restart
will be done on diesel, then
transfer back to gas
Ilustrative operating profile
Gas in piston underside
Two possible sources of gas
Leaking gas admission valve
Blow-by gas from broken piston rings
Possible
source
2)
1) Leaking gas admission valve
2) blow-by from broken piston rings
Leakage
severe
moderate
severe
moderate
Effect of
failure
Excessive firing
pressures
or
Knocking
Small gas
concentration in
piston underside
Excessive firing
pressures
or
Knocking
Small gas
concentration in
piston underside
Detection
of failure
Cylinder
balancing
or
Knock detection
or
Gas valve lift
Gas sniffers in
piston underside
Cylinder balancing
or
Knock detection
Gas sniffers in
piston underside
1)
Action
Trip to diesel
Trip to diesel, slow down from ESS
Dual-fuel engine machinery for Merchant Vessels
Low-speed DF
main engine
• Single wall piping on open deck
Gas
valve
• Ventilated double wall piping for class
unit
rules for ‚inherently safe engine room‘
• Purging system for piping, GVU, tank,….
Wärtsilä Package…..
a complete and
modularized solution for
LNG fuelled ships
DF auxiliary engines
Gas
valve
unit
G
G
LNG Pac
Gas
valve
unit
Cyl.tank IMO C-type
G
Gas
valve
unit
Cold box with LNG low-pressure pumps
evaporator, heater, valves, etc
Very low electrical energy
consumption for gas feed
Conclusions
Why to choose a Wärtsilä low-pressure dual-fuel engine:
1) Meet IMO Tier III requirements without exhaust gas after-treatment due to
lean burn Otto combustion process
2) Low CAPEX due to low pressure gas supply system
• No large gas compression equipment
• No exhaust gas after treatment
3) Low OPEX due to high overall efficiency (low parasitic load)
4) Full Wärtsilä Package Complete and modularized
solutions for LNG fuelled ships
5) Availability
• RT-flex50DF mid 2014
• X62DF
2015
• X72DF
2016
4775 - 11520 kW
6160 - 19080 kW
8320 - 25800 kW
6) Retrofit for existing RT-flex50-D, X62 and X72
will be made available
THANK YOU!
Thank you!
46
© Wärtsilä

engine

Transcription

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