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Accueil du site > Thèmes de recherche > Combustion & systèmes réactifs > 1.2 Formation and reduction of pollutants from combustion > 1.2.1 Chemical kinetics of NOx formation and destruction

1.2.1 Chemical kinetics of NOx formation and destruction

Nitrogen oxides (NOx) are important pollutants formed during combustion in air. Nitric oxide (NO) is generally the most important. In collaboration with the Ecole des Mines at Albi, we have studied the reduction of NO by solid fuels (ACL35). Our kinetic models have been extended to conditions relevant to a cement plant calciner. This work showed the importance of nitrogen and sulphur mass fractions in the fuel on the formation/reduction of NOx.

Among the intermediates formed during the oxidation of N-bound fuels, HCN (hydrogen cyanide) is produced. It is also a key-intermediate in NO-reburning. Therefore, its kinetics of oxidation has been reviewed ; an updated reaction scheme has been proposed in collaboration with the groups from Universities of Lyngby and Zaragoza (ACL37).

NOx formation in high pressure flames is studied, in collaboration with the PC2A, Lille (ANR project NO-mecha, 2009-2012). It aims at revisiting the NOx formation mechanism, particularly the recent controversy about the prompt-NO route (CH + N2 = NCN + H) in methane and natural gas-air flames. It relies on a novel experimental approach that allows obtaining a completely renewed database including most of the NO-sensitive species in a very large range of flame conditions in terms of pressure (4 kPa -1 MPa) and composition. The new high pressure counter-flow burner facility of ICARE is used coupled to laser diagnostics. LIF and PLIF techniques have been applied with success for OH radical measurements (ACTI12) in high pressure CH4/air flames (up to 1MPa) and measurements of NO and CH are ongoing. A modelling work is performed in parallel in order to test the performances of the kinetic mechanism GDFkin®3.0 (ACL176) at high pressure conditions. The formation of NOx was also investigated in collaboration with the University of Seattle for lean prevaporived premixed combustion conditions (ACL29).