This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
Suitable Stainless Steel Selection for Exhaust Line Containing a Selective Catalytic Reduction (SCR) System
Technical Paper
2011-01-1323
ISSN: 0148-7191, e-ISSN: 2688-3627
Annotation ability available
Sector:
Language:
English
Abstract
Due to the evolution of emission control standards, new
pollution control systems will be necessarily used for off-road
vehicles and trucks exhaust systems and in the near future for
passenger cars. Indeed, the will to reduce NOx emission through
Euro 5 (2009) and then to Euro 6 (2014) and American EPA Tier 4
(2008-2015) imposes the implementation of a new after-treatment
system within the exhaust line. One of the most promising
technologies takes advantage of the reduction feature of ammonia
(NH₃) on NOx. This system called Selective Catalytic Reduction
(SCR) couldn't be developed by storing directly ammonia as a
reduction agent on the vehicle due to its high toxicity and
flammability. It is why urea is used as an ammonia generator
through thermolysis reaction.
During this process, the stainless steel wall of the exhaust
line undergoes sprinkling of urea decomposition products - among
which ammonia - at the upstream injection point of the catalyst and
also cyclic heat treatment due to exhaust gas. The combination of
both needs to be studied in further detail to get a better
understanding of mechanisms involved in the exhaust material
durability under such conditions. With the aim of simulating this
particular hot corrosion process two dedicated laboratory benches
were developed at the ArcelorMittal Stainless Steel Research Center
(Isbergues, France).
The simulated tests consist in spraying urea solution on cyclic
heated stainless steel in the temperature range of the application
(from 200°C to 600°C). We evidenced nitriding mechanisms due to the
contact between urea decomposition products and the hot stainless
steel surface and also highlighted different performance between
austenitic and ferritic grades and even noticeable behavior
variation among every stainless steel family. Thus, ferritic grades
exhibit better performance among which K41X (441 - 1.4509) and K33X
(molybdenum stabilized ferritic close to 436Ti grade - 1.4513) show
the best behavior, in particular as compared to 304 austenitic
grade.
This paper will review the test set-up, the results obtained and
will discuss the most suitable stainless steel grade selection for
the SCR application in both mixing zone and the downstream
area.
Recommended Content
Authors
Topic
Citation
Saedlou, S., Santacreu, P., and Leseux, J., "Suitable Stainless Steel Selection for Exhaust Line Containing a Selective Catalytic Reduction (SCR) System," SAE Technical Paper 2011-01-1323, 2011, https://doi.org/10.4271/2011-01-1323.Also In
References
- Rajasekar, E. et al. Review of NOx reduction technologies in CI engines fuelled with oxygenated biomass fuels Renew Sustain Energy Rev. 2010 10.1016/j.sers.2010.03.005
- Johnson, T. Diesel Engine Emission and Their Control Platinum Metals Rev. 2008
- Koebel, M et al. Selective Catalytic Reduction of NO and NO 2 et low temperature Catalysis Today 2002
- Forzatti, P. et al. Diesel NOx after-treatment catalytic technologies: Analogies in LNT and SCR catalytic chemistry Catalysis Today 2010 10.1016/j.cattod.2010.02.025
- Koebel, M. et al. Urea SCR: a promising technique to reduce NOx emissions from automotive diesel engines Catalysis Today 2000
- Kjäll, J. High Temperature Corrosion in Urea-Exhaust Environment Diploma Work 85 2007 1652-8913 2007
- Simmons, J.W. Effect of Nitride (Cr 2 N) precipitation on the mechanical, corrosion and wear properties of austenitic stainless steel ISIJ International 1996
- Wang, J. et al. Effects of DC plasma nitriding parameters on microstructure and properties of 304L stainless steel Materials Characterization 2008
- López, D. et al. Effect of Particle Velocity and Impact Angle on the Corrosion-Erosion of AISI 304 and AISI 420 Stainless Steel Wear 259 2005 118 124
- Mohammadi, F. Luo, J. Effect of Particle Angular Velocity and Friction Force on Erosion Enhanced Corrosion of 304 Stainless Steel Corrosion Science 2010 10.1016/j.corsci.2010.05.012
- Mesa, D.H. et al. The effect of testing temperature on corrosion-erosion resistance of martensitic stainless steel Wear 255 2003 139 145 10.1016/S0043-1648(03)00096-6
- Levey, P.R. Van Bennekom, A. “A Mechanistic Study of the Effects of Nitrogen on the Corrosion Properties of Stainless Steel” Corrosion Science 51 12 911 921 1995