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TIP: Follow MAN & Turbo's DieselFacts
DieselFacts is MAN Diesel & Turbo's technical customer magazine. DieselFacts online contains current and previous editions with extra material, including video clips.
http://mandieselturbo.com/0000665/Press/Publications/DieselFacts.html
[ SAMPLE ARTICLE EXCERPT ]
DieselFacts 2/2012
Tier III Selective Catalytic Reduction
Development of large two-stroke diesel engines
[ EXCERPT ]
With a view to meeting the NOx Tier III regulations due to take effect in 2016, Hitachi Zosen is developing an SCR (Selective Catalytic Reduction) system for low-speed diesel engines in cooperation with MAN Diesel & Turbo. To this end, a prototype was recently fitted to an MAN B&W 6S46MC-C engine aboard a general cargo newbuilding for Nissho Shipping.
NOx regulation
The regulation of air pollution stemming directly from diesel engines is among the IMO regulations covering hazardous waste from ships. The first NOx regulation was introduced in 2000 (Tier I), with Tier II coming into force in 2011 and Tier III in 2016. As such, Tier III represents an 80% reduction in NOx compared with Tier I. While it was possible to meet Tier II limits through engine adjustments alone, meeting Tier III makes it necessary to introduce external techniques. It is mandatory to observe the new NOx regulations, and any negative effect on fuel consumption and running costs is a major concern for ship operators.
De-NOx technology for Tier III
Realistically, SCR and EGR (Exhaust Gas Recirculation) are the two main techniques that can help engines meet Tier III NOx regulations, based on the service experience from power plants and cars, respectively.
Hitachi Zosen and MAN Diesel & Turbo agreed to develop an SCR system for two-stroke engines located before the turbocharger. Hitachi Zosen chose SCR as its NOx-reduction method because: it is possible to make a compact system using high-temperature and high-pressure gas, and de-NOx efficiency is improved
it is possible to maintain the engine’s running performance whether the SCR system is running or not and with no harm to the engine Hitachi Zosen is a total solution provider of marine SCR systems.
SCR system for marine diesel engines
There are two solutions for a marine SCR system. One is a lowpressure system, installed downstream of the turbocharger. The other is a high-pressure system, installed upstream of the turbocharger and which Hitachi Zosen has concentrated on.
High-pressure SCR system
A diesel engine emits nitrogen oxides and dioxides. When a urea solution is injected into the duct upstream of the reactor, it is then converted into ammonia. Subsequently, NOx reacts with the ammonia in the catalyst in the HPSCR reactor and is converted into nitrogen and water with the clean gas then flowing into the turbocharger. Hitachi Zosen provides the optimised control system of urea solution injection.
Two SCR on/off valves and an SCR bypass valve control the smooth flow of flue gas into the SCR system, using a sequence that is programmed by MAN Diesel & Turbo.
NOx removal catalyst
The Hitachi Zosen catalyst has a characteristic triangular configuration and its wall also has a lot of fibre matrix reinforcement. It is therefore very tough and resistant to engine vibration despite being quite thin.
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TIP: Follow MAN & Turbo's DieselFacts
DieselFacts is MAN Diesel & Turbo's technical customer magazine. DieselFacts online contains current and previous editions with extra material, including video clips.
http://mandieselturbo.com/0000665/Press/Publications/DieselFacts.html
[ SAMPLE ARTICLE EXCERPT ]
DieselFacts 2/2012
Tier III Selective Catalytic Reduction
Development of large two-stroke diesel engines
[ EXCERPT ]
With a view to meeting the NOx Tier III regulations due to take effect in 2016, Hitachi Zosen is developing an SCR (Selective Catalytic Reduction) system for low-speed diesel engines in cooperation with MAN Diesel & Turbo. To this end, a prototype was recently fitted to an MAN B&W 6S46MC-C engine aboard a general cargo newbuilding for Nissho Shipping.
NOx regulation
The regulation of air pollution stemming directly from diesel engines is among the IMO regulations covering hazardous waste from ships. The first NOx regulation was introduced in 2000 (Tier I), with Tier II coming into force in 2011 and Tier III in 2016. As such, Tier III represents an 80% reduction in NOx compared with Tier I. While it was possible to meet Tier II limits through engine adjustments alone, meeting Tier III makes it necessary to introduce external techniques. It is mandatory to observe the new NOx regulations, and any negative effect on fuel consumption and running costs is a major concern for ship operators.
De-NOx technology for Tier III
Realistically, SCR and EGR (Exhaust Gas Recirculation) are the two main techniques that can help engines meet Tier III NOx regulations, based on the service experience from power plants and cars, respectively.
Hitachi Zosen and MAN Diesel & Turbo agreed to develop an SCR system for two-stroke engines located before the turbocharger. Hitachi Zosen chose SCR as its NOx-reduction method because: it is possible to make a compact system using high-temperature and high-pressure gas, and de-NOx efficiency is improved
it is possible to maintain the engine’s running performance whether the SCR system is running or not and with no harm to the engine Hitachi Zosen is a total solution provider of marine SCR systems.
SCR system for marine diesel engines
There are two solutions for a marine SCR system. One is a lowpressure system, installed downstream of the turbocharger. The other is a high-pressure system, installed upstream of the turbocharger and which Hitachi Zosen has concentrated on.
High-pressure SCR system
A diesel engine emits nitrogen oxides and dioxides. When a urea solution is injected into the duct upstream of the reactor, it is then converted into ammonia. Subsequently, NOx reacts with the ammonia in the catalyst in the HPSCR reactor and is converted into nitrogen and water with the clean gas then flowing into the turbocharger. Hitachi Zosen provides the optimised control system of urea solution injection.
Two SCR on/off valves and an SCR bypass valve control the smooth flow of flue gas into the SCR system, using a sequence that is programmed by MAN Diesel & Turbo.
NOx removal catalyst
The Hitachi Zosen catalyst has a characteristic triangular configuration and its wall also has a lot of fibre matrix reinforcement. It is therefore very tough and resistant to engine vibration despite being quite thin.
///////
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