View
217
Download
1
Category
Preview:
Citation preview
WÄRTSILÄ 2-STROKE DUAL FUEL
TECHNOLOGY
1 © Wärtsilä Technical Seminar 2013 Dual fuel technology update / Marcel Ott
CIMAC NMA NORGE ANNUAL MEETING 22.01.2014
Wärtsilä gas engine technolgies
Dual- fuel (DF)
’Low pressure’
Gas-diesel (GD)
’High pressure’ Spark-ignition Gas (SG)
’Low pressure’
1987 1992 1995
Technical Seminar 2013 Dual fuel technology update / Marcel Ott 2 © Wärtsilä
Building on medium speed experience…
6 segments >240 installations >1000 DF engines >7’000’000 running hours
DF Power Plant • 64
installations • 331 engines • Output 4040
MW • Online
since1997
LNGC • 130 vessels • 520 engines Multigas Carrier • 5 vessels • 20 engines Conversion • 1 Chem. Tanker • 2 engines
OSV’s • 21 vessels • 70 engines Production • 1 platform • 8 FPSO’s etc. • 1 FSO • 33 engines
LNG Cruise ferry • 1 vessels • 4 engines • Complete gas
train LNG ferries • 4 ferries • 16 engines Conversion • 1 ferry • 2 engines
Coastal Patrol • DF-propulsion • DF main and
auxiliary engines
TUG • 2 vessel • 2 engines
each • Mechanical
drive Guide Ship • 1 vessel
/engine IWW • 2 vessel • 3 engines
Power Plants Merchant Offshore Cruise & Ferry
Navy Others
’The experience gained from ’medium speed’ DF development is the base for the 2-s DF success’
Technical Seminar 2013 Dual fuel technology update / Marcel Ott 3 © Wärtsilä
The 2-stroke DF concept
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
‘Pre-mixed lean-burn’ combustion
Scavenging Compression/ gas admission
Ignition expansion
Low pressure Dual Fuel
Technical Seminar 2013 Dual fuel technology update / Marcel Ott 4 © Wärtsilä
The 2-stroke DF concept
The main merits: • Low pressure gas < 10 bar
– no space… – no CAPEX, no OPEX… – no maintenance…
• …needed for High pressure gas equipment
• Lean Burn ‘Otto’ combustion – no additional technology… – No additional CAPEX… – No OPEX increase...
• …to reach world class emission levels
‘Pre-mixed lean-burn’ combustion
Scavenging Compression/ gas admission
Ignition expansion
low pressure Dual Fuel
Technical Seminar 2013 Dual fuel technology update / Marcel Ott 5 © Wärtsilä
2-stroke DF - Technology
Pre-chamber technology
Engine Control & Automation system
Gas admission system
Micro-pilot + Common Rail
A few key technologies make the difference...
Technical Seminar 2013 Dual fuel technology update / Marcel Ott 6 © Wärtsilä
2-stroke DF - Key Technologies
Micro pilot and Pre-chamber technology • Electronically controlled injectors +
Common Rail fuel supply • Pilot fuel (for ignition) only 1% -
minimizing fuel costs • Pre-chamber technology for best
combustion stability and reduced emissions
• Technology developed and proven on 4-stroke
• Option for HFO as pilot will be available
Technical Seminar 2013 Dual fuel technology update / Marcel Ott 7 © Wärtsilä
Pre-chamber
2-stroke DF - Key Technologies
Gas admission system • 2 x GAV (Gas Admission Valve) per
cylinder • GAV actuated hydraulically • Hydraulic power supply from exhaust
valve servo oil system • Precise gas admission control – from
full load to ’idling’ • The key to optimized fuel/air mixture
formation – engine performance • Double walled piping for enhanced
safety
Technical Seminar 2013 Dual fuel technology update / Marcel Ott 8 © Wärtsilä
2-stroke DF - Key Technologies
Engine control and automation system • Wärtsilä ‘UNIC’ based control
system • All essential controls in one
system • Individual control of combustion
related parameters – optimized engine performance
• Inbuilt Redundancy for ’single main engine’ application
• Safety functions related to gas operation including knock- and misfire detection
Pilot fuel injector
Gas admission valves
Control system
2x Gas admission valves
Pilot fuel injectors
Engine speed/ CA-signal Engine stop signal
Gas duration
Gas pressure
Pilot fuel pressure
Exhaust valve drive
Exhaust valve
Technical Seminar 2013 Dual fuel technology update / Marcel Ott 9 © Wärtsilä
Low pressure DF – engine testing
Engine testing • Full-scale testing started in August 2013
• Engine basic performance established
• Key advantages of the 2-s DF technology
successfully confirmed
• Exploration of further performance improvements will continue
Technical Seminar 2013 Dual fuel technology update / Marcel Ott 10 © Wärtsilä
Low pressure DF – engine output
Technical Seminar 2013 Dual fuel technology update / Marcel Ott 11 © Wärtsilä
Engine output
Max rating lower than ‘diesel’, due to limitations from knocking / pre-ignition
May in some applications require 1 (one) cylinder more than the ‘diesel’ engine to reach the required output
Most applications today run on ’de-rated’ output
R1
R2 R3
R4
2-stroke DF - NOx Emissions
Wärtsilä 2-s DF
HP
• Significant reduction of NOx emissions due to the low pressure DF technology – clearly below IMO Tier III – without exhaust gas after
treatment
Technical Seminar 2013 Dual fuel technology update / Marcel Ott 12 © Wärtsilä
2-stroke DF - total emission picture
• CO2 and SOx reduced in gas operation due to fuel composition
• PM further reduced by the DF
technology with Lean-burn Otto-combustion with pre-chamber ignition
Tier3!
-25% -25% -25%
-37%
-99% -96%
-98%
-85%
Technical Seminar 2013 Dual fuel technology update / Marcel Ott 13 © Wärtsilä
What about methane slip?
• Methane slip = THC emissions (Total Unburned Hydrocarbons)
• No regulations or limits regarding methane emissions exist
• Methane is 20..25 times stronger green house gas than CO2
• The 2-stroke DF reduces the total CO2 footprint compared to HFO
• Potential to further reduce the methane slip on 2-stroke DF by further development
Total hydro carbon contribution to CO2 equivalent emissions
-10%
-23%
Technical Seminar 2013 Dual fuel technology update / Marcel Ott 14 © Wärtsilä
The keys to low methane slip
Methane slip is reduced by: • ‘Direct’ methane slip can be
avoided by correct gas admission valve timing
• Use of pre-chamber technology
to have complete combustion • Optimized combustion space
to avoid ‘dead volumes’
X X
Technical Seminar 2013 Dual fuel technology update / Marcel Ott 15 © Wärtsilä
Low pressure DF – engine output limitations
Technical Seminar 2013 Dual fuel technology update / Marcel Ott 16
Methane number
For the DF engine, actual output may be limited by Methane Number of the gas
However:
Typically, the MN of LNG is 70..90
Typically, operating area for low speed engines is < 85% CMCR
No de-rating needed
In case MN is too low, engine control system will automatically make the necessary adjustments and limit output to a safe level or trip to diesel for 100% output
Methane Number MN
Derating factor KKNOCK
Preliminary, to be confirmed
Typical max. service load
Low pressure DF - operation
Operational features • Dual -fuel operation - Gas with
HFO/MDO as ‘back-up’ • Seamless fuel transfer without
load reduction • Gas operation over the entire
load range • Load acceptance like ‘Diesel’
in normal conditions – Automatic switch to diesel in
case of ‘emergency’ or ‘crash stop’
Technical Seminar 2013 Dual fuel technology update / Marcel Ott 19 © Wärtsilä
First 2-stroke DF engines contracted!
Technical Seminar 2013 Dual fuel technology update / Marcel Ott 20 © Wärtsilä
• Terntank Rederi A/S
• 2x 15k product tankers
• ME: 5RT-flex50DF
• Ship deliveries early 2016
© Wärtsilä / Ship Powerr 2s
First vessel order - Wärtsilä 2s low-pressure DF engine
Owner Terntank Rederi A/S, Sweden Shiptype 15000 tdw Tanker, 2 vessels Service speed 14.5 kn Shipyard AVIC Dingheng, China Order date November 2013 Ship delivery Feb and May 2016 Engine type 5RT-flex50DF, CMCR 5750 kW / 99 rpm
Wärtsilä 2-stroke DF – what‘s next?
Next steps and targets: • Finalize engine testing of the
RT- flex50DF and release of performance data
• Get ’Safety Concept’ and Type Approval in mid 2014
• Factory Acceptance test of the first pilot engine in 2014
• First pilot in operation in 2015 • Expand the DF technology to
larger bore Generation X engine types
Technical Seminar 2013 Dual fuel technology update / Marcel Ott 22 © Wärtsilä
THANK YOU!
23 © Wärtsilä Technical Seminar 2013 Dual fuel technology update / Marcel Ott
GENERAL SAFETY ASPECTS OF THE 2-S DF
Technical Seminar 2013 Dual fuel technology update / Marcel Ott 24 © Wärtsilä
Principles
• Gas safe machinery space: Single failure will not lead to gas release into machinery
space
• Dilute possible ignitable gas concentrations to levels below the lower explosion limit (LEL)
• Limit consequences of explosions (worst case)
Technical Seminar 2013 Dual fuel technology update / Marcel Ott
Goal: Ensure safe handling of gas fuel under all operating conditions, to minimize the risk to the ship, persons on board and to the environment
Ope
ratio
nal r
isk
25 © Wärtsilä
Principles
Main systems to detect abnormal conditions: • Gas detectors (in double wall pipes, machinery space, on engine) • Knocking sensors • Cylinder pressure monitoring Possible system reactions upon detection of abnormal conditions: • Trip back to diesel (back-up mode), all gas pipes vented,
no pressurized gas on engine • Engine slow-down • Engine shut-down (only if impossible to run
in back-up mode)
Technical Seminar 2013 Dual fuel technology update / Marcel Ott
Back-up mode and system
redundancy of diesel engine is
always available!
26 © Wärtsilä
Machinery space concept
Technical Seminar 2013 Dual fuel technology update / Marcel Ott
Forced engine room ventilation
GVU (Gas Valve Unit) enclosure
Gas safe area Double wall fuel gas pipe
Gas venting pipe Annular pipe / GVU enclosure venting
GVU
Fuel Gas
Air in
Engine room: gas safe area
Gas detectors in annular space
Blower
27 © Wärtsilä
• Gas piping in engine room double walled • GVU execution options:
• enclosed type GVU installed in engine room • ‘single walled’ GVU in separate ‘GVU-room’
Gas pipe ventilation
• As a general rule, gas pipes after GVU are always depressurized when the engine is not running in gas mode
• Master gas fuel valve should be installed outside of engine room in case of a gas-alarm, also the supply line before the GVU will
be vented
Technical Seminar 2013 Dual fuel technology update / Marcel Ott 28 © Wärtsilä
Double wall pipe design
Active ventilation of annular space: • Volume exchanged min.
30 times/hour • Transport of gas to gas detector Alarm triggered in case of leakage Trip to diesel, gas pipes vented
O-Ring
Air passage
Technical Seminar 2013 Dual fuel technology update / Marcel Ott 29 © Wärtsilä
Gas detection in engine room and GVU
Technical Seminar 2013 Dual fuel technology update / Marcel Ott 30 © Wärtsilä
• One gas detector in the DF-engine room ventilation outlet • One gas detector above DF-engine • Each ventilated duct enclosing gas supply piping • One gas detector above GVU, if they are installed in engine room or dedicated compartment • Green gas detector for piston underside will be delivered by engine maker and is directly connected to the Engine Safety System (ESS) • Gas detectors in engine gas vent line are optional
Engine / exhaust system ventilation
Prevent accumulation of gas in the engine and exhaust system: • After emergency stop / shut
down in gas mode • Purging with engine auxiliary
blowers • Exhaust valves automatically
opened • Slow-turning / air run
procedure to flush all cylinders
Auxiliary blower
Technical Seminar 2013 Dual fuel technology update / Marcel Ott 31 © Wärtsilä
External exhaust system
Standard gas engine installation: external exhaust system to be fitted with rupture discs: • Prevent damage to exhaust
system in case of exhaust gas explosion
• Rupture discs replaceable • Explosion vent outlet must be led
to safe area
Technical Seminar 2013 Dual fuel technology update / Marcel Ott 32 © Wärtsilä
Detection of abnormal combustion
Safety relevant functionalities: • Knock detection • Misfiring detection
Performance optimization • Cylinder balancing
(compression pressure, firing pressure)
• Maximize efficiency
Ope
ratin
g w
indo
w
Ther
mal
effi
cien
cy
NO
x em
issi
ons
BM
EP
Air / Fuel ratio
Knocking
Mis
firin
g
Optimum performance for all cylinders
Trip to diesel, all gas pipes vented
if abnormal combustion:
Technical Seminar 2013 Dual fuel technology update / Marcel Ott 33 © Wärtsilä
Conclusions
• Draft version of the engine safety concept ready • More detailed description of systems etc. available in the document • Classification society expected to review and give feedback on:
– Scope – Content – Comments to individual chapters on more detailed level
Technical Seminar 2013 Dual fuel technology update / Marcel Ott 34 © Wärtsilä
Recommended