3 Wettstein Waertsilae Low-Speed Low-Pressure Dual-Fuel Engine

8/19/2019 3 Wettstein Waertsilae Low-Speed Low-Pressure Dual-Fuel Engine

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The Wärtsilälow-speed low-pressure

dual-fuel enginedevelopment

LNG IN PRACTICE

SEMINAR ON BOARD

MS VIKING GRACE

SEPT. 18, 2013 Rudolf Wettstein

Wärtsilä Switzerland Ltd

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RTX-5 test engine on GAS

• Engine commissioned for full scale gas

operation during August

• All systems up and running:

– Gas admission system

– Pilot injection

– Engine control system

– etc…

• Performance optimization started

– 75% power output achieved

– Fuel change over from gas to diesel and vice

versa

– NOx level on gas far lower than Tier lll limit

– Low load operation on gas seems feasiblewith sufficient stability

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Transfer Diesel – Gas – Diesel

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Transfer from Diesel to Gas

NOx emissions

in gas mode!

Trip back to Diesel



Engine performance

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Gas mode Diesel mode

Output BMEPtarget 18.8 bar

currently 17.3 bar

Energy

consumption *

target +/- 0% * +2% *

currently

NOx emissions IMO Tier III IMO Tier II

Gas pressure (bar g) < 10 ---

* Reference = Standard diesel R1 Tier II tuning

Current focus on installations running mostly on gas

(ECA vessels, LNGC, …)

Efficiency to be confirmed on full scale test engine



Emission values – medium-speed dual-fuel engine

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CO2

NOx

SOx

Particulates

Dual-Fuel engine

in gas mode

Diesel

engine0

10

20

30

40

50

60

70

80

90

100

Emission

values [%]

-25%

-85%

-99%

-99%

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Methane slip

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• THC emissions (‘methane slip’) is not limited by IMO

• CO2 equivalent emissions in any case lower than on diesel/HFO operation

0

0,2

0,4

0,6

0,8

1

1,2

Diesel/HFO Gas/DF Gas/GD (ME-GI)

Contribution from methane slip;Contribution from Carbon in fuel;

Relative CO2 equivalent



Basic concept (2 stroke – low pressure)

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Principles:

Engine operating accordingly

to Otto process

Injection of gas at mid-stroke.

Low pressure gas injection

(<10 bar) sufficient High impact on NOX reduction

Meets IMO Tier III without

after treatment

‘Pr e-mixed l ean-bur n’ c o mbust ion

ScavengingCompression/

gas admission

Ignition

expansion



Other concept (2 stroke – high pressure)

Principles:

Engine operating accordingly

to Diesel process

Injection of gas close to TDC.

Air is completely compressed

and, therefore, high pressuregas injection (300 bar) is

required.

No significant NOX reduction

Requires SCR or EGR (not

proven) in order to meet IMOTier III levels

Scavenging/

compression

Pilot & HP gas

injection Expansion

Dir ect inj ect ion, dif f usion co mbust io n

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Otto or Diesel cycles: effects on NOX

Big temperature

difference

NOx formation!

Otto, max flame temp.

Diesel, max flame temp.

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1858-1913

1831-1891



Technical features – Gas admission

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Gas admission system

2 x GAV (gas admission valve) per cylinder

GAV actuated by hydraulically ‘fast-switching’

solenoid valves

Hydraulic power supply from exhaust valve

servo oil system



Technical features – Pilot fuel system

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Pilot fuel system

Pilot fuel utilized for ignition(as in four-strokes DF engines)

Pilot fuel consumption ~1% of BSFC at 100% load

Pre-chamber technology for best ignition and

combustion stability

Fuel supply based on common-rail technology

Pre-chamber



Technical features – Pilot fuel system

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Pilot fuel system

Single fuel oil pump serving all cylinders(common-rail technology)

Filters and pressure regulation included

Pilot fuel pump electrically driven

UNIC





Technical features – Automation

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Engine automation and control system

UNIC based control system Individual control of combustion related

parameters (cyl.pressure, combustion process,

….)

Safety functions related to gas operation

included

Pilot fuel injector Pilot fuel injector

Gas admission valvesGas admission valves

Test

cylinder

running on

gas

Control

system

2x Gas admission valves2x Gas admission valves

Pilot fuel injectorsPilot fuel injectors

Engine speed/CA-signalEngine speed/CA-signal

Engine stop signalEngine stop signal

Gas durationGas duration

Gas pressureGas pressure

(Pilot fuel pressure)(Pilot fuel pressure)

Exhaust valve driveExhaust valve drive

Exhaust valveExhaust valve

Pilot fuel injector

Gas admission valves

Test

cylinder

running on

gas

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



Designing by CFD simulations

• CFD = computational fluid dynamics

• Used to evaluate and validate designs before engine tests, like: – number and location of gas admission points

– gas injection nozzle design

– gas pressure and injection timing influence

– pre-chamber optimization and combustion simulations

• Target

– screening/evaluation of design alternatives before testing

– optimize the engine already during the design phase

• Purpose

– shorten development time

– improved engine performance

Gas velocity distribution during

the initial phase of gas injection

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2-stroke gas engine – potential applications

1. Ships operating on gas when going into a ECA

(Emission Controlled Area)• operating temporarily on gas in ECA zones and

on HFO outside ECA

2. Ships operating ‘continuously’ on gas• majority of the time running on gas

• LNG Carriers, any other ship types using gas on

long-haul trips

Driver: emissions

Driver: operating costs

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Dual-fuel engine machinery for Merchant Vessels

DF auxil iary enginesGas

valve

unit G

G

G

Gas

valve

unit

Gas

valve

unit

Gasvalve

unit

LNG PacCyl.tank IMO C-type

Wärtsilä Package…..

a complete andmodularized solution for

LNG fuelled ships

Low-speed DF

main engine

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• Single wall piping on open deck

• Ventilated double wall piping for class

rules for ‚inherently safe engine room‘• Purging system for piping, GVU, tank,….

Cold box with LNG low-pressure pumps

evaporator, heater, valves, etc Very low electrical energy

consumption for gas feed



175’000 m3 LNG Carrier with twin-shaft machinery

Gas

valve

unit

Gas

valve

unit

Gas

valve

unit

Gas

valve

unit

5X72DF or 6/7X62DFCMCR = 12500 kW

Fuel Gas

Handling

System

(FGHS)

Gas

valve

unit

5X72DF or 6/7X62DFCMCR = 12500 kW

175‘000 m3

LNG, - 163 °C

2610 kW / 720 rpm

6L34DF

G

G

G

3915 kW / 720 rpm

9L34DF

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Boil-off gas rate and engine gas demand

Qh

Qv

Low pressure

compressor set

Heater

Evaporator

Boil-off gas rate = 0,1% per day

175 m3 per day = 80 ton/day

Main engines daily gas consumption

at Service Speed

2 x 37.5 ton/day = 75 ton/day

Aux engine daily gas consumption

6L34DF (at 50% of load)6 ton/day

Total gas demand: 81 t/day

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Low pressure feed pumps

Fuel Gas

Handling System

Wärtsilä Hamworthy

Nitrogen Generator


Reliquefactionplant




Gas engine history within SULZER

• 1965-’72: low pressure loop scavenged 6RD76 tested in Winterthur

• 7RNMD90 installed in 29’400m3 LNG-carrier “MV Venator ” in 1972

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High pressure engine was developed

in co-operation with IHI (Diesel

United).

It was demonstrated in 1986 on onecylinder of a 6RTA84 engine.



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 (<10bar)

• 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) Availabil ity

• RT-flex50DF mid 2014 4775 - 11520 kW• X62DF 2015 6160 - 19080 kW

• X72DF 2015 8320 - 25800 kW

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THANK YOU!

Wär ts il äWär ts il äLeading gas applications in the marine marketLeading gas applications in the marine market

22 © Wärtsilä 2sDF Engine / May 2013

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3 Wettstein Waertsilae Low-Speed Low-Pressure Dual-Fuel Engine