cimac nma norge annual meeting 22.01 - · pdf file2-stroke df - key technologies . engine...

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’


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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


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


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...


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


Pre-chamber


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



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


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


Low pressure DF – engine output


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


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%


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%


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


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’


First 2-stroke DF engines contracted!


• 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


THANK YOU!

23 © Wärtsilä Technical Seminar 2013 Dual fuel technology update / Marcel Ott

GENERAL SAFETY ASPECTS OF THE 2-S DF


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

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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)


Back-up mode and system

redundancy of diesel engine is

always available!

26 © Wärtsilä

Machinery space concept


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


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


Gas detection in engine room and GVU


• 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


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


Detection of abnormal combustion

Safety relevant functionalities: • Knock detection • Misfiring detection

Performance optimization • Cylinder balancing

(compression pressure, firing pressure)

• Maximize efficiency

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Air / Fuel ratio

Knocking

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Optimum performance for all cylinders

Trip to diesel, all gas pipes vented

if abnormal combustion:


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


cimac nma norge annual meeting 22.01 - · pdf file2-stroke df - key technologies . engine...

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