Investigations into NOx Aftertreatment with Urea SCR for Light-Duty Diesel Vehicles

Blakeman, Philip G.; Chandler, G. R.; John, Gareth; Wilkins, A. J. J.

doi:10.4271/2001-01-3624

Cited by 13 publications

(6 citation statements)

References 6 publications

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“…Some low-temperature SCR designs report greater than 80% NO x conversion at 150°C by using a preoxidation catalyst before the urea injection point. 29,30 The preoxidation catalyst generates NO 2 , preferably with a 1:1 ratio of NO:NO 2, which enhances low-temperature reactions between NH 3 and NO x . 29,30 Heating the SCR to maintain optimal catalyst brick temperature might be considered, although this may require substantial energy.…”

Section: Discussionmentioning

confidence: 99%

“…29,30 The preoxidation catalyst generates NO 2 , preferably with a 1:1 ratio of NO:NO 2, which enhances low-temperature reactions between NH 3 and NO x . 29,30 Heating the SCR to maintain optimal catalyst brick temperature might be considered, although this may require substantial energy. Other methods may be considered for marine emissions reduction such as replacing the engines with new models, but the vessel is not often designed for routine engine removal.…”

Section: Discussionmentioning

confidence: 99%

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Atmospheric Emissions from a Passenger Ferry with Selective Catalytic Reduction

Nuszkowski

Clark

Spencer

et al. 2009

Journal of the Air & Waste Management Association

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The two main propulsion engines on Staten Island Ferry Alice Austen (Caterpillar 3516A, 1550 hp each) were fitted with selective catalytic reduction (SCR) aftertreatment technology to reduce emissions of oxides of nitrogen (NO x ). After the installation of the SCR system, emissions from the ferry were characterized both pre-and postaftertreatment. Prior research has shown that the ferry operates in four modes, namely idle, acceleration, cruise, and maneuvering modes. Emissions were measured for both engines (designated NY and SI) and for travel in both directions between Manhattan and Staten Island. The emissions characterization used an analyzer system, a data logger, and a filter-based particulate matter (PM) measurement system. The measurement of NO x , carbon monoxide (CO), and carbon dioxide (CO 2 ) were based on federal reference methods. With the existing control strategy for the SCR urea injection, the SCR provided approximately 64% reduction of NO x for engine NY and 36% reduction for engine SI for a complete round trip with less than 6.5 parts per million by volume (ppmv) of ammonia slip during urea injection. Average reductions during the cruise mode were 75% for engine NY and 47% for engine SI, which was operating differently than engine NY. Reductions for the cruise mode during urea injection typically exceeded 94% from both engines, but urea was injected only when the catalyst temperature reached a 300°C threshold pre-and postcatalyst. Data analysis showed a total NO x mass emission split with 80% produced during cruise, and the remaining 20% spread across idle, acceleration, and maneuvering. Examination of continuous NO x data showed that higher reductions of NO x could be achieved on both engines by initiating the urea injection at an earlier point (lower exhaust temperature) in the acceleration and cruise modes of operation. The oxidation catalyst reduced the CO production 94% for engine NY and 82% for engine SI, although the high CO levels during acceleration did cause analyzers to overrange. No clear, quantitative conclusions could be made regarding the effects of the SCR on PM.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Atmospheric Emissions from a Passenger Ferry with Selective Catalytic Reduction

Nuszkowski

Clark

Spencer

et al. 2009

Journal of the Air & Waste Management Association

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“…The (Gentemann and Caton, 2003). decomposition illustrated was based on the studies done by Koebel et al (2001), Koebel and Strutz (2003), Ball (2001), Luders et al (1995) and Blakeman et al (2001).…”

Section: Probable Process Mechanismmentioning

confidence: 99%

Control of combustion-generated nitrogen oxides by selective non-catalytic reduction

Javed

Irfan

Gibbs

2007

Journal of Environmental Management

266

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“…Reactions (2)-(4) are NO x reduction reactions. The oxidation of ammonia is described by reactions (5) and (6). Finally, reaction (7) is referred to as desorption of ammonia from the surface of the catalyst.…”

Section: Mathematicalmentioning

confidence: 99%

“…This technology was first used in stationary applications and has also become very popular for both light-duty and heavy-duty vehicles over the last decade [5][6][7]. Urea SCR is undoubtedly one of the most effective methods of reducing NO x because of its high selectivity and reactivity with NO x in the presence of excess oxygen and is also very economical.…”

Section: Introductionmentioning

confidence: 99%