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International audience; Hybrid propulsion generally combines a liquid oxidizer with a solid fuel. Compared to solid or bi- liquid engines, this type of propulsion offers advantages in terms of cost and flexibility. For several years, ONERA has been providing expertise in this area, both in experimental and numerical simulations. Various hybrid rocket motors have been designed and tested on ground, including under low ambient pressure conditions and in flight. The Propulsion Laboratory unit of the DMAE uses fully instrumented engine breadboards in order to optimize the oxidizer/fuel pair, as well as the injection system and the combustion efficiency. In addition, 0D and 1D codes for engine design areactively being developed. More recently, studies have been undertaken as part of the LEOP future satellite platforms, with the development of an innovative new combustion chamber.; La propulsion hybride combine généralement un oxydant liquide et un combustible solide. Comparé aux moteurs solides et bi-liquides, ce type de propulsion présente des avantages en termes de coût et de flexibilité. Depuis plusieurs années, l’ONERA offre une expertise dans ce domaine, par la réalisation à la fois d’études expérimentales et de simulations numériques. Différents moteurs hybrides y ont été conçus et testés au sol, y compris dans des conditions de haute altitude, et en vol. L’unité Laboratoire de Propulsion du DMAE utilise des moyens d’essais instrumentés pour optimiser le couple oxydant/combustible mais aussi le système d’injection et le rendement de combustion. En outre des codes 0D et 1D permettant la conception de ces moteurs y sont également développés. Plus récemment, des études ont été entreprises dans le cadre des futures plateformes de satellite de télécommunication avec le développement d’une architecture de chambre de combustion innovante.

International audience; The combustion of solid fuels in the rotary kiln and in the calciner of a cement plant generates fuel and thermal NO. This NO can be reduced inside the reducing zone of the calciner. This occurs in two different ways: homogeneous reduction by hydrocarbons and heterogeneous reduction by char. The purpose of this paper is to identify the relative contribution of volatile matters or char on the NO reduction process, which largely depends on the nature of the solid fuel used for reburning.Experiments were undertaken in an Entrained Flow Reactor (EFR), at three temperatures: 800, 900 and 1000 °C. Four major fuels used in the cement production process were studied: a lignite, a coal, an anthracite and a petcoke. Specific experiments were undertaken to determine (i) their devolatilisation kinetics and the gas species released. A wide range of species influencing the NO chemistry was carefully analyzed. Then, (ii) the char oxidation and (iii) the char NO reduction kinetics were characterized. Finally, (iv), the “global” NO reduction capability of each fuel was quantified through experiments during which all phenomena could occur together. This corresponds to the situation of an industrial reactor in reducing conditions. Anthracite and petcoke reduce only very small quantities of NO whereas lignite and coal reduce, respectively, 90% and 80% of the initially present 880 ppm of NO (at 1000 °C after 2 s).The four types of experiments described above were then modeled using a single particle thermo-chemical model that includes heterogeneous reactions and detailed chemistry in the gas phase. This model reveals that both NO reduction on char and NO reduction by volatiles mechanisms contribute significantly to the global NO reduction. After short residence times (several tenth of a second), gas phase reactions reduce NO efficiently; after long residence times (several seconds) the char reduces larger quantities of NO.