3D Numerical Simulations of Selective Catalytic Reduction of NOx With Detailed Surface Chemistry

2017 ◽  
Author(s):  
Zhaoyu Luo ◽  
Parvez Sukheswalla ◽  
Scott A. Drennan ◽  
Mingjie Wang ◽  
P. K. Senecal
Keyword(s):  
Experimental Data ◽  
Steady State ◽  
Surface Chemistry ◽  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Water Solution ◽  
Nox Reduction ◽  
Nox Emissions ◽  
Detailed Surface ◽  
Exhaust After Treatment

Environmental regulations have put stringent requirements on NOx emissions in the transportation industry, essentially requiring the use of exhaust after-treatment on diesel fueled light and heavy-duty vehicles. Urea-Water-Solution (UWS) based Selective Catalytic Reduction (SCR) for NOx is one the most widely adopted methods for achieving these NOx emissions requirements. Improved understanding and optimization of SCR after-treatment systems is therefore vital, and numerical investigations can be employed to facilitate this process. For this purpose, detailed and numerically accurate models are desired for in-cylinder combustion and exhaust after-treatment. The present paper reports on 3-D numerical modeling of the Urea-Water-Solution SCR system using Computational Fluid Dynamics (CFD). The entire process of Urea injection, evaporation, NH3 formation and NOx reduction is numerically investigated. The simulation makes use of a detailed kinetic surface chemistry mechanism to describe the catalytic reactions. A multi-component spray model is applied to account for the urea evaporation and decomposition process. The CFD approach also employs an automatic meshing technique using Adaptive Mesh Refinement (AMR) to refine the mesh in regions of high gradients. The detailed surface chemistry NOx reduction mechanism validated by Olsson et al. (2008) is applied in the SCR region. The simulations are run using both transient and steady-state CFD solvers. While transient simulations are necessary to reveal sufficient details to simulate catalytic oxidation during transient engine processes or under cyclic variations, the steady-state solver offers fast and accurate emission solutions. The simulation results are compared to available experimental data, and good agreement between experimental data and model results is observed.

Observer-Based Estimation of Aging Condition for Selective Catalytic Reduction Systems in Vehicle Applications

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Yao Ma ◽  
Junmin Wang
Keyword(s):  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Estimation Error ◽  
Nox Reduction ◽  
Observer Design ◽  
Accurate Estimation ◽  
Nox Emissions ◽  
Aging Condition ◽  
Entire Vehicle ◽  
Scr System

This paper presents two observers for estimating the aging condition of selective catalytic reduction (SCR) systems in vehicle applications. SCR systems have been widely recognized as one of the leading engine exhaust gas aftertreatment systems for reducing diesel powertrain tailpipe NOx emissions in ground vehicle applications. While fresh SCRs are quite effective in reducing tailpipe NOx emissions, their NOx reduction capabilities and performances may substantially degrade with in-service aging. To maintain the emission control performance of a SCR system for a diesel engine during the entire vehicle service life, it is thus critical to have an accurate estimation of the SCR system aging condition. In this paper, two Lyapunov-based observers utilizing the measurements of NOx and ammonia concentrations are analytically developed and verified in simulations for estimating the SCR aging condition. The measurement uncertainty is explicitly considered in the observer design process. A sufficient condition for the boundedness of the estimation error is derived. Simulation results under the US06 test cycle demonstrate the effectiveness of the proposed observers.

Power Improvement and NOx Reduction Strategies for a Hydrogen-Fueled Multicylinder Internal Combustion Engine

2019 ◽  
Vol 141 (12) ◽  
Author(s):  
Jayakrishnan Krishnanunni ◽  
Divesh Bhatia ◽  
Viresh Dutta ◽  
Lalit Mohan Das
Keyword(s):  
Internal Combustion Engine ◽  
Selective Catalytic Reduction ◽  
Power Output ◽  
Catalytic Reduction ◽  
Combustion Engine ◽  
Nox Reduction ◽  
Internal Combustion ◽  
Nox Emissions ◽  
Spark Timing ◽  
Reduction Strategies

Abstract The conventional operation of a hydrogen internal combustion engine (ICE) under lean conditions results in low NOx emissions, however, at the cost of power generated. In this study, the power output of a hydrogen-fueled ICE was increased while maintaining the NOx emissions at low levels. The power output was increased by turbocharging, relatively richer operation, and spark timing optimization, whereas a combination of exhaust gas recirculation (EGR) and H2-selective catalytic reduction (H2-SCR) aftertreatment was used to reduce NOx emissions. Turbocharging resulted in a maximum torque output of 168 N·m at 3200 rpm as compared to 70 N·m at 1600 rpm for the naturally aspirated operation. However, the turbocharger could not generate enough boost at low speeds and the equivalence ratio was increased to obtain a high power output which resulted in a substantial increase in the NOx emissions. The use of EGR resulted in an average reduction of 72% in the NOx emissions. Retarding of spark timing significantly reduced the NOx emissions too, but was limited by the adverse impact on the torque. Since hydrogen would be available onboard a hydrogen-fueled vehicle, we for the first time report external injection of H2 for use as a reductant in the selective catalytic reduction unit. Even under extremely oxidizing conditions, the efficiency of aftertreatment was found to be 35.4% averaged over various speeds. A maximum of 83.7% overall reduction in NOx emissions was achieved by using the combined EGR and H2-SCR strategies.

RSCR® System to Reduce NOx Emissions From Boilers

2009 ◽  
Author(s):  
Richard F. Abrams ◽  
Robert Faia
Keyword(s):  
Selective Catalytic Reduction ◽  
Flue Gas ◽  
Heat Recovery ◽  
High Efficiency ◽  
Catalytic Reduction ◽  
Low Cost ◽  
Nox Reduction ◽  
Waste To Energy ◽  
Nox Emissions ◽  
Reaction Products

Babcock Power Environmental (BPE), a Babcock Power Inc. company, has developed a new, innovative, high-efficiency NOx reduction technology designed to greatly reduce the NOx emissions from waste to energy (WTE) boilers at relatively low cost. This “tail-end” system uses Selective Catalytic Reduction (SCR) to achieve the high reduction performance. Conventional SCR catalyst cannot be used in the traditional “high-dust” location, downstream of the economizer because constituents in the ash would poison the catalyst quickly, rendering it useless. Thus, the Regenerative Selective Catalytic Reduction (RSCR®) system is designed to operate at the end of the plant before the flue gas is discharged to the stack. The process utilizes a reactant (usually aqueous ammonia) to be added to the flue gas stream upstream of the RSCR to reduce NOx to harmless reaction products, N2 and H2O. The RSCR combines the efficient heat recovery, temperature control, reactant mixing, and catalyst into a single unit and provides the maximum NOx reduction and heat recovery practical. The paper will describe the overall predicted performance of a typical WTE boiler plant using this new technology. The paper will also provide actual operating data on the RSCR, which has been retrofitted to four biomass-fired units.

Selective Catalytic Reduction of NOx Emissions

2021 ◽  
pp. 1115-1130
Author(s):  
R. J. G. Nuguid ◽  
F. Buttignol ◽  
A. Marberger ◽  
O. Kröcher
Keyword(s):  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Nox Emissions ◽  
Reduction Of Nox

Perspective on SCR NOx control for diesel vehicles

2019 ◽  
Vol 4 (6) ◽  
pp. 969-974 ◽  
Author(s):  
Christine K. Lambert
Keyword(s):  
Steady State ◽  
Selective Catalytic Reduction ◽  
Research Design ◽  
Catalytic Reduction ◽  
System Research ◽  
Reduction Of No ◽  
Diesel Vehicles ◽  
Aqueous Urea ◽  
Nox Control ◽  
Scr System

The selective catalytic reduction of NOx with aqueous urea (“urea SCR”) is originally a steady-state technology that has been successfully applied to diesel vehicles worldwide. This Perspective summarizes 20+ years of SCR system research, design, and future improvements.

scholarly journals Current Catalyst Technology of Selective Catalytic Reduction (SCR) for NOx Removal in South Korea

Catalysts ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 52 ◽  
Author(s):  
Hyo-Sik Kim ◽  
Saravanan Kasipandi ◽  
Jihyeon Kim ◽  
Suk-Hwan Kang ◽  
Jin-Ho Kim ◽  
...  
Keyword(s):  
Air Pollution ◽  
Nitrogen Oxides ◽  
South Korea ◽  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Research Trends ◽  
Nox Emissions ◽  
Nox Removal ◽  
National Characteristics ◽  
The World

Recently, air pollution has worsened throughout the world, and as regulations on nitrogen oxides (NOx) are gradually tightened many researchers and industrialists are seeking technologies to cope with them. In order to meet the stringent regulations, research is being actively conducted worldwide to reduce NOx-causing pollution. However, different countries tend to have different research trends because of their regional and industrial environments. In this paper, the results of recent catalyst studies on NOx removal by selective catalytic reduction are reviewed with the sources and regulations applied according to the national characteristics of South Korea. Specifically, we emphasized the three major NOx emissions sources in South Korea such as plant, automobile, and ship industries and the catalyst technologies used.

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