Urea-SCR Catalyst System Selection for Fuel and PM Optimized Engines and a Demonstration of a Novel Urea Injection System

Gekas, Ioannis; Gabrielsson, Pär; Johansen, Keld; Nyengaard, Lars; Lund, Thomas

doi:10.4271/2002-01-0289

Cited by 29 publications

(18 citation statements)

References 2 publications

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“…1,2 The emission reductions focus primarily on oxides of nitrogen (NO x ) and after considering available options, two selective catalytic reduction (SCR) systems were installed on the ferry Alice Austen as part of a pilot-phase demonstration. 2 An SCR system, using urea injection, has demonstrated effectiveness at reducing NO x emissions by over 90% in other applications, [3][4][5][6][7] and SCR is now suggested as a major pathway to achieving 2010 U.S. on-road diesel vehicle emissions standards. The SCR systems also incorporated oxidation catalysts to reduce ammonia (NH 3 ), carbon monoxide (CO), and hydrocarbon (HC) emissions, a concern because although CO is a product of combustion, it…”

Section: Introductionmentioning

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 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: Introductionmentioning

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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“…(1) Fast reaction: (2) Slow reaction: (3) (4) (5) (6) It is clear now that the VWT system emerges as the most robust catalytic system for an ammonia-SCR. It is highly active at medium temperature range (190 to 450 °C) and has superior resistance against sulfur poisoning.…”

Section: Standard Reactionmentioning

confidence: 98%

“…Generally, the engine management system for a diesel engine is optimized to give very low PM, less than 0.02 g/kWh However the optimized combustion for reducing the PM leads to higher NOx emissions [1,2]. Ammonia-SCR is mostly widely used to reduce the NOx level up to 90 %.…”

Section: Introductionmentioning

confidence: 99%

Low Temperature Selective Catalytic Reduction of NOx over Vanadium-Based Catalysts

Narkhede¹,

Kumar²,

Cursetji³

et al. 2015

SAE Int. J. Engines

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Diesel engines are becoming popular because of more fuel efficient and durability. While the CO and HC impurities are significantly lower than in gasoline engines, the design strategies for reduction of Particulate Matter and Nitrogen Oxides remain a major challenge for environment. The work mainly focused on reduction of NOx from diesel engines using SCR technology under Indian driving conditions and furl availability. With BS III/IV fuel available in the country, the catalyst system of choices the Vanadia Tungsten Titania (VWT) system because of its proven resistance to Sulfur poisoning. However, under urban driving conditions on Indian roads, the major obstacle is the low engine out temperatures which are below the normal operating temperature window (200 to 450 °C) of VWT -SCR.The objective of the present investigation is to develop low temperature SCR catalyst system that outperforms the existing commercial catalytic system during the cold start and low load operating conditions. This work focused on modifying the preparation parameters so as optimize the activity of Vanadium for NOx reduction in the temperature range between 200 -450°C.With the help of sophisticated catalyst characterization tools, novel and highly active formulations of vanadium has been developed, which is more active at lower temperatures as well as do not catalyze the undesirable reactions such as those leading to N 2 O formation. The metal oxide catalysts are designed and developed to obtain innovative and attractive solutions for the reduction of NOx emissions during cold start and low load operating conditions. The influence of various operating parameters such as NO 2 /NOx ratio, NH 3 /NOx ratio, space velocity over the typical temperature range on performance of an optimized SCR formulation are investigated for proper design and sizing of the after treatment system.

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“…It has been demonstrated that Euro V levels (NOx= 2 g/KWh) can be achieved when this approach is applied to engines with Euro IV technology (NOx= 3.5 g/KWh). With an SCR conversion efficiency of 80-85%, the Euro V emissions target can be still met even with NOx higher than the EURO IV levels [39].…”

Section: Emission Reduction Strategiesmentioning

confidence: 99%

Simple strategy-based technique to reduce emissions from SCR-equipped heavy-duty diesel engine over different engine-out calibrations

Ardanese¹

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Heavy-duty diesel engine manufacturers, regulators and operators in Europe and US have judged the Selective Catalytic Reduction (SCR) system to be the most suitable exhaust aftertreatment technology to meet the Euro V and US 2010 emission standards for oxides of nitrogen (NOx). The choice of the SCR as the exhaust aftertreatment system has been accompanied by engine calibrations with higher engine-out NOx emissions. Temporary deactivation of the exhaust aftertreatment device, due to malfunction or disrepair could result in excessively high NOx emissions at the tailpipe. Therefore, there is a need to evaluate alternative engine calibrations that would limit in-use NOx emissions during SCR inefficiencies. The objective of this study was to develop and implement a technique to program an engine with different calibrations, which were optimized for exhaust aftertreatment performance. Two very distinct calibrations were evaluated over transient and steady state conditions. The implementation of these calibrations helped meet the emission standards under conditions, which are critical for the SCR operation under real worldconditions, but may not be encountered during the engine certification testing. Multiple calibrations were designed by means of a simple multivariate optimization technique involving the variation of only four engine parameters, namely EGR rate, boost pressure, injection pressure and injection timing. In addition, an empirical model for accurate NOx and fuel consumption (FC) prediction was developed, assuming independency of the parameters. The technique developed in this study was found to be quick to implement, simple and efficient; requiring very little engine test cell time. The main calibrations proved to be engine cycle independent, since comparable emission levels were measured over ESC, FTP and ETC cycles. Low-NOx map was obtained by raising the injection pressure and increasing EGR rates. A NOx emissions reduction of 20% was achieved, with a penalty in fuel economy of less than 3% from the baseline. Several fuel efficient calibrations were generated by advancing injection timing and increasing injection pressure; the highest improvement brought a reduction in FC of more than 6%. Multiple calibrations can be generated by this technique and alternatively used by the engine control system depending upon the thermodynamic conditions of the exhaust stream at the inlet of the SCR system

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Urea-SCR Catalyst System Selection for Fuel and PM Optimized Engines and a Demonstration of a Novel Urea Injection System

Cited by 29 publications

References 2 publications

Atmospheric Emissions from a Passenger Ferry with Selective Catalytic Reduction

Atmospheric Emissions from a Passenger Ferry with Selective Catalytic Reduction

Low Temperature Selective Catalytic Reduction of NOx over Vanadium-Based Catalysts

Simple strategy-based technique to reduce emissions from SCR-equipped heavy-duty diesel engine over different engine-out calibrations

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