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

Published on Jun 1, 2013in Rem-revista Escola De Minas
· DOI :10.1590/S0370-44672013000200003
Claudine Miraval (Aperam), Saghi Saedlou1
Estimated H-index: 1
(Aperam)
+ 2 AuthorsJohan Leseux1
Estimated H-index: 1
(Aperam)
Abstract
O aco inoxidavel e amplamente utilizado no sistema de exaustao de carros de passeio e sera aplicado, agora, em caminhoes e veiculos off-road. Nesse campo de aplicacao, os projetos sao cada vez mais complexos com a integracao de catalisador e filtro de particulas, como consequencia dos cada vez mais severos regulamentos sobre despoluicao de veiculos diesel. Notadamente, devido a necessidade de reducao das emissoes de oxidos de nitrogenio (NOx), estabelecida pelas normas Euro 5 (2009), Euro 6 (2014) e American Tier 4 (2014), novos equipamentos foram desenvolvidos para veiculos a diesel (caminhoes, bem como viaturas). A tecnologia mais promissora e chamada de Reducao Catalitica Seletiva (do ingles SCR), que aproveita o recurso de reducao por amonia (NH3) em NOx. Como NH3 nao poderia ser diretamente armazenada no interior do veiculo, por razoes de seguranca (toxicidade e inflamabilidade da amonia), a solucao aquosa de ureia foi escolhida para iniciar a reacao por meio de um bico de pulverizacao. Para se obter uma melhor compreensao dos mecanismos de corrosao a quente envolvidos e, depois, para se melhorar a selecao de materiais, um teste de laboratorio foi desenvolvido no Centro de Pesquisa de Isbergues. O teste simulado consiste em pulverizar uma solucao de ureia no aco inoxidavel aquecido ciclicamente na faixa de 200oC a 600oC. Evidenciou-se um mecanismo de nitretacao, devido a decomposicao da ureia sobre a superficie de aco inoxidavel a temperatura elevada e, tambem, foram observados comportamentos bastante diferentes entre as familias austenitica e ferritica. A ultima familia, em particular os tipos K41X (1.4509-441) e K33X (1.4513 molibdenio-ferritico estabilizado), mostra o melhor desempenho, em especial em relacao ao padrao da classe 304 austenitica. O artigo faz uma revisao do teste de set-up, apresenta os resultados obtidos e discute a escolha do tipo de aco inoxidavel para a aplicacao em SCR.
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Published on Mar 1, 2009in Materials Characterization 2.89
Jun Wang16
Estimated H-index: 16
(Sichuan University),
Ji Xiong2
Estimated H-index: 2
(Sichuan University)
+ 4 AuthorsBaoluo Shen11
Estimated H-index: 11
(Sichuan University)
Abstract A wear-resistant nitrided layer was formed on a 304L austenitic stainless steel substrate by DC plasma nitriding. Effects of DC plasma nitriding parameters on the structural phases, micro-hardness and dry-sliding wear behavior of the nitrided layer were investigated by optical microscopy, X-ray diffraction, scanning electron microscopy, micro-hardness testing and ring-on-block wear testing. The results show that the highest surface hardness over a case depth of about 10 µm is obtained a...
62 Citations Source Cite
Published on Jun 1, 2000in Catalysis Today 4.67
Manfred Koebel17
Estimated H-index: 17
(Paul Scherrer Institute),
Martin Elsener31
Estimated H-index: 31
(Paul Scherrer Institute),
M Kleemann1
Estimated H-index: 1
(Paul Scherrer Institute)
Abstract Urea-SCR, the selective catalytic reduction using urea as reducing agent, has been investigated for about 10 years in detail and today is a well established technique for DeNO x of stationary diesel engines. It is presently also considered as the most promising way to diminish NO x emissions originating from heavy duty vehicles, especially trucks. The paper discusses the fundamental problems and challenges if urea-SCR is extended to mobile applications. The major goal is the reduction o...
688 Citations Source Cite
Published on Sep 1, 2010in Renewable & Sustainable Energy Reviews 9.18
E. Rajasekar1
Estimated H-index: 1
,
A. Murugesan11
Estimated H-index: 11
(K. S. Rangasamy College of Technology)
+ 1 AuthorsN. Nedunchezhian7
Estimated H-index: 7
Oxygenated fuels like biodiesel and alcohols have the potential to provide a reliable and a cost effective alternative to India's increasing future energy demands. They have a prospective future since they are renewable and can be produced easily in India's rural areas. Due to rapid industrialization and the increased number of vehicles on the road, the energy needs of the country are increasing rapidly. Oxygenated fuels can substantially replace the large demand for diesel to generate power for...
101 Citations Source Cite
Published on Jun 1, 2010in Catalysis Today 4.67
Pio Forzatti57
Estimated H-index: 57
(Polytechnic University of Milan),
Luca Lietti45
Estimated H-index: 45
(Polytechnic University of Milan)
+ 1 AuthorsEnrico Tronconi54
Estimated H-index: 54
(Polytechnic University of Milan)
This paper reviews the main results of wide investigations dedicated to the understanding of the chemistry and the reaction pathways operating in the reduction of NOx in LNT and SCR processes for the aftertreatment of NOx in diesel exhausts. In particular, similarities and differences between the two processes will be highlighted. The reactions involved in the NH3-NO/NO2-SCR reacting system were investigated by an extensive set of various unsteady-state experiments performed over both vanadium-b...
69 Citations Source Cite
Published on Jan 1, 2008in Platinum Metals Review
Timothy V. Johnson4
Estimated H-index: 4
138 Citations Source Cite
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