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Emission Control Technology for Marine Applications
IMO MARPOL VI: Stage TIER III
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Tier I Tier II Tier III
RPM
NO
X g/
kWh
From TIER I to Tier II engine modifications are sufficient
From TIER II to Tier III engine modifications are no longer sufficient and
emission technology is required
The challenge is NOX reduction: the most
obvious solution is SCR technology
SCR catalystEngine
Urea Pump
Urea Doser
Urea tank
SCR Schematic Layout
Control Unit
SCR Pros and Cons
Emission target TIER III can be achieved for both TIER 1 and TIER II engines
Can be used with diesel containing sulphur (up to 2000 PPM*)
Exhaust geometry less flexible
Engine can be optimized for fuel consumption
Extra tank
Extra technical complexity
SCR technology was introduced >10 years ago in the HD market.
Extra cost (investment)
Over 1 500 000 installations are operational today
Extra cost of ownership
* Sulphur impact on system size
Ceramic substrates
Possible catalyst chapes
Metal substrates
Race track
Rectangle
RingRound
Oval
Square
Round
Oval
Square
Oval ring
Race track ring
Validation programs SCR(F) on two ships
Barge
This is considered as a normal application
Engine: Scania V8 16 liter 450 kW
Police Patrol ship
Considered as a worst case scenario
Engine : 2 x MTU V2000-01 600 kW
The Barge
The Barge
DOC SCR(F)
The barge
The silencer
The SCRF
The patrol ship
The patrol ship
The patrol ship
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SCR for Superyachts
Superyachts have access to good quality fuel
(European and American ports / marinas deliver road fuel or low sulphur fuel maximum 1000 PPM )
Facts
Superyachts use mainly high speed diesel engines
Annual operational hours are low150 -200 hours for privately owned vessels
500 hours for charter vessels
The average load profile is low
Challenge for superyachts
Integration of the SCR into the silencer• Space for SCR catalyst• Urea mixing – Gamma over the catalyst • Pressure drop• Silencing capacities• Maintenance and service
Model from DISCOM BV Netherlands
Typical exhaust for superyacht
Dry exhaust bypass
Wet exhaust(venturi)
Examples for MTU 2880 kW – SCR
Silencer for Superyacht with MTU 2880 kW.• Catalyst volume required +/- 422 dm³• Available volume in silencer 5422 dm³ • Less then 8 % of silencer volume• Expected pressure drop over the SCR catalyst 14 mBar
Model from DISCOM BV Netherlands
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SCR sizing versus fuel quality
Parameters affecting durability
Sulphur from fuel and lubrication oil- Formation of ammonium bisulphate (NH4SO4) – reversible- Clogging by soot and metal sulphates - reversible/irreversible
Phosphorous from lubrication oil- Phosphorous depositing in the catalyst pores – irreversible
Alkali metals- Na and K react with active sites on the surface – irreversible
Temperature- Sintering of the catalyst carrier – irreversible
Test results prove
Regulated emissions are not affected with sulphur levelsup to at least 350 ppm in the fuel with vanadium SCRCatalyst (tested for 4200 hours) (testcycle E3, ETC, ESC).
Testing with 1200 ppm S fuel shows that NOx conversion is affected when long periods of low temperatures occur.
Testing reveals good sulphur tolerance of the vanadium SCR catalyst as activity is fully recovered at increased temperature (350°C).
Urea dosing strategy must be adjusted accordingly.
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Urea dosing & NOx measurement for ships
Urea dosers
Injection section
Urea pressure rail
& Urea return rail
Nox sampling
Control cabinet - multi engine
Conclusions
Superyachts can be equipped with compact SCR systems that are resistant to the fuel used in this market.
By using metal substrates, a high degree of freedom in design is possible and can be combined with low pressure drops.
SCR systems will be effective between 20 % and 100% of engine load.
Last minute roll-out / introduction / implementation will lead to systems that are neither validated nor optimized for cost.
There are no other drawbacks for the technology other than economical drawbacks (space, investment, cost of ownership).
Thank you for your attention