Estimation of Ammonia Storage Nonuniformity for Urea-Based Selective Catalytic Reduction Systems

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Qinghua Lin ◽  
Pingen Chen
Keyword(s):  
Selective Catalytic Reduction ◽  
Emission Reduction ◽  
Catalytic Reduction ◽  
Urea Solution ◽  
Coverage Ratio ◽  
Ammonia Storage ◽  
Simulation Results ◽  
Parallel Configuration ◽  
Scr Model ◽  
The Impact

Ammonia storage nonuniformity has a significant impact on the emission reduction performance of urea-based selective catalytic reduction (SCR) systems. In this paper, a unique SCR platform with two catalysts in a parallel configuration was created for investigating the impact of ammonia storage nonuniformity on the emission reduction performance in a simulation environment. The established two-cell SCR platform allows users to independently control the ammonia-to-NOx ratio (ANR) for each catalyst using two independent urea solution injectors. Simulation results over US06 cycle demonstrate that, compared to the case without ammonia storage nonuniformity, the tailpipe NOx and ammonia emissions can be increased by 6.73% and 22.0%, respectively, due to the nonuniform ammonia storage in the case of an ANR nonuniformity index (NUI) at 0.2. Furthermore, an innovative model-based method was proposed for estimating the ammonia coverage ratio nonuniformity (i.e., ammonia storage nonuniformity if storage capacity is known) by utilizing a control-oriented SCR model and the tailpipe NOx and ammonia measurements at the confluence point. Simulation results proved the effectiveness of the proposed method in estimating the ammonia coverage ratio nonuniformity.

Design of Urea-SCR Model of a Feedforward Controller Based on Simulation in Diesel Engine

2012 ◽  
Vol 562-564 ◽  
pp. 1924-1927
Author(s):  
Bao Yi Wang ◽  
Qian Wang
Keyword(s):  
Mathematical Model ◽  
Steady State ◽  
Diesel Engine ◽  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Accurate Performance ◽  
Feedforward Controller ◽  
Simulation Results ◽  
Scr Model

Using a mathematical model, a feedforward controller model of Urea-SCR (selective catalytic reduction, SCR) in diesel engine is realized. At steady-state conditions, the simulated NOX concentration shows great consistence with the experimental value in the downstream of the converter. It can be seen that the simulation results show comparatively accurate performance of the model with the converter temperature changing linearly in the range from 450K to 750K.

Selective Catalytic Reduction of NO with Hydrocarbons:  Experimental and Simulation Results

1996 ◽  
Vol 35 (8) ◽  
pp. 2508-2515 ◽  
Author(s):  
Gesthimani D. Lionta ◽  
Sophia C. Christoforou ◽  
Evangelos A. Efthimiadis ◽  
Iacovos A. Vasalos
Keyword(s):  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Reduction Of No ◽  
Simulation Results

scholarly journals Influence of Selective Catalytic Reduction (SCR) system on stainless steel durability

2013 ◽  
Vol 66 (2) ◽  
pp. 153-158
Author(s):  
Claudine Miraval ◽  
Saghi Saedlou ◽  
Romain Evrard ◽  
Pierre-Olivier Santacreu ◽  
Johan Leseux
Keyword(s):  
Stainless Steel ◽  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Material Selection ◽  
Catalytic Converter ◽  
Water Solution ◽  
Urea Solution ◽  
Diesel Vehicles ◽  
Set Up ◽  
Corrosion Mechanisms

Stainless steel is largely used in the car exhaust market and will be applied now for truck and off-road vehicles. In that field of application, designs are more and more complex with the integration of a catalytic converter and particle filter, consequence of more and more severe diesel depollution regulations. In particular, due to the necessity of reducing NOx emission established by Euro 5 standard (2009), Euro 6 (2014) and American Tier 4 (2014), new equipment were developed for diesel vehicles (truck as well as car). The most promising technology is called Selective Catalytic Reduction (SCR) and takes advantage of the reduction feature of ammonia (NH3) on NOx. As NH3 cannot be stored directly within the vehicle for safety reasons (toxicity & flammability of ammonia) urea in water solution was selected to initiate the reaction by means of a spraying nozzle. To get a better understanding of the involved hot corrosion mechanisms and afterward to improve material selection, a dedicated laboratory test was developed at Isbergues Research Center. The simulated test consists of spraying urea solution on cyclic heated stainless steel in a range from 200ºC to 600ºC. We evidenced a nitriding mechanism due to the urea decomposition on the surface of stainless steel at high temperature, and also the very different behaviours between austenitic and ferritic grades. The last one, in particular K41X (1.4509-441) and K33X (1.4513-molybdenum stabilized ferritic) grades show the best performance in particular when compared to the standard 304 austenitic grade. The paper will review the test set-up, the result obtained and will discuss the stainless steel grade selection for the SCR application.

Robust Filtering for Ammonia Coverage Estimation in Diesel Engine Selective Catalytic Reduction Systems

2013 ◽  
Vol 135 (6) ◽  
Author(s):  
Hui Zhang ◽  
Junmin Wang ◽  
Yue-Yun Wang
Keyword(s):  
Diesel Engine ◽  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Critical Role ◽  
Approximation Error ◽  
Ammonia Concentration ◽  
Nonlinear Observer ◽  
Coverage Ratio ◽  
Vehicle Simulation ◽  
Measurement Noises

In this paper, we investigate the nonlinear observer designs to estimate the ammonia coverage ratio in the diesel engine selective catalytic reduction (SCR) systems. The ammonia coverage ratio is an important variable due to its critical role in the SCR NOx conversion and the ammonia slip. However, the ammonia coverage ratio cannot be directly measured by onboard sensors. Therefore, it is necessary to develop effective observers to estimate the ammonia coverage ratio online. Based on a three-state SCR model, we develop two nonlinear observers. The first one only employs the dynamics of the ammonia concentration. The structure and the algorithm are simple. But it is sensitive to the measurement noises and the uncertainties in the system parameters. The second one is a discrete-time smooth variable structure estimator which is robust to the measurement noises, the approximation error, and the system uncertainties. Both estimators are implemented on a full-vehicle simulation of the FTP75 test cycle. The simulation results have verified the theoretical analysis.

scholarly journals PILOT-SCALE EVALUATION OF THE IMPACT OF SELECTIVE CATALYTIC REDUCTION FOR NOx ON MERCURY SPECIATION

2000 ◽  
Author(s):  
Dennis L. Laudal ◽  
John H. Pavlish ◽  
Kevin C. Galbreath ◽  
Jeffrey S. Thompson ◽  
Gregory F. Weber ◽  
...  
Keyword(s):  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Pilot Scale ◽  
Mercury Speciation ◽  
Scale Evaluation ◽  
The Impact
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