Hydrolyse sous pression de la biomasse ligno-cellulosique

WasteEng Conference Series "Spéciale Afrique 2009", juillet 2009, Ouagadougou, BURKINA FASOInternational audienceDans les «procédés courants» de production de gaz combustible à partir de la biomasse, le séchage de cette dernière est une étape coû-teuse en énergie. Un nouveau procédé en cours d'étude permettrait de s'en affranchir. Dans ce cadre, nous étudierons l'hydrolyse acide et sous pression des constituants de la biomasse. Dans une première étape, nous rechercherons à établir un protocole d'hydrolyse de la biomasse. Des essais à l'acide sulfurique et oxalique et sous une légère pression (jusqu'à 3 ou 4 bars) ont mis en avant une amélioration des rendements. Néanmoins ceux-ci ne permettaient pas encore d'envisager une étape de développement industriel du procédé. Dans une seconde étape nous étudierons l'influence de la mise en pression au moyen d'un autoclave. Les produits de l'hydro-lyse seront caractérisés par chromatographie ionique. Mots clés : hydrolyse, biomasse ligno-cellulosique, chromatographie ionique, acide oxalique. Abstract The "current processes" of production of fuel gas starting from the biomass, the drying of the latter is an expensive stage in energy. A new process under study would make it possible to be freed some. Within this framework, we will study the acid hydrolysis and under pressure of the components of the biomass. In a first stage, we will seek to draw up a protocol of hydrolysis of the biomass. Tests with the sulphuric and oxalic acid and under a light pressure (until 3 or 4 bars) proposed an improvement of the outputs. Nevertheless the outputs obtained did not make it possible yet to consider a stage of industrial development of the process. In one second stage we will study the influence of the pressurization by means of an autoclave. The products of the hydrolysis will be characterized by ionic chromatography

Technologies plasmas appliquées aux traitements thermiques des déchets nucléaires.

Cette étude décrit plusieurs procédés chimiques à hautes températures développés au Commissariat à l’Energie Atomique et aux Energies Alternatives pour assurer le traitement de déchets issus de l’exploitation de la filière nucléaire. Ces procédés utilisent des technologies différentes de plasmas thermiques atmosphériques pour incinérer des familles de déchets organiques de formes et de compositions chimiques très variées. Dans chaque cas, un plasma d’oxygène à haute puissance est établi à partir d’une torche à plasma d’induction ou à partir d’une ou plusieurs torches à plasma d’arc électrique soufflé ou transféré garantissant une parfaite combustion de la fraction organique du déchet à traiter par le procédé

Chlorine management in thermal processes.

International audienceThermal processes are increasingly used to treat industrial or municipal organic waste. For instance cogeneration that is able to use one part of the internal energy waste is becoming more popular. Incineration is often used for the treatment of industrial waste. Incineration vitrification is under development for organic nuclear waste processing. Whatever the case, the presence of chlorine in the waste leads to severe corrosion problems in the process. To mitigate these difficulties in an incineration process for radioactive waste contaminated by plutonium (IRIS), the CEA has investigated the processes by which potentially hazardous compounds are produced in order to eliminate them or prevent their formation. The studies have led to propose a phosphate-based stabilization technique thanks to an addition of phosphorus in the waste. Through a reaction occurring in gas phase, the metals are stabilized under a phosphate form when the formation of volatiles chlorides is avoided.This very efficient technique has been applied for the nuclear waste incineration and has substantially improved process maintenance and security. It could be used for other application in the field of nuclear, household, industrial waste processing

Numerical study of the hydrodynamics in a two-phase induction melter for nuclear waste treatment under various operating parameters

International audienceThis article presents the numerical modeling of an in-can melter containing a metallic and a glass phase. Low-frequency electromagnetic induction is used to melt and stir the metal, and the latter heats and drags the glass phase. A careful choice of operating parameters is required to prevent the solidification of the glass, and to increase the performances of the process. Numerical modeling helps in avoiding experimental trial and error method and in studying the effect of the operating parameters on the hydrodynamics. The main difficulty for the numerical modeling comes from the deformation of the interfaces, produced by the magnetic pressure. First, a theoretical estimation of this phenomenon is performed and compared with numerical and experimental results. Then, numerical results are presented for different power inputs, AC frequencies, and quantities of glass. One of the phenomena obtained numerically is air entrainment at the triple point, creating bubbles in the glass

Kinetic Modeling of the Polychloroprene Pyrolysis Under Nitrogen Atmosphere

International audienceIn the present work it was performed the pyrolysis of polychloroprene (produced by Aldrich) in two types of experimental apparatus differentiated by the sample size they could work with. The first experimental device was a TG-DTA analyzer and the second one was a higher capacity thermo-balance placed inside a furnace (so-called ``Aubry''). The experimental conditions were the following: temperatures up to 1,000 degrees C and atmospheric pressure (1 bar), atmosphere of flowing nitrogen, three different heating rates (5, 10 and 15 K/min for the ``Aubry'' furnace and 10, 20 and 30 K/min for the TG-DTA) and two different quantities of samples (10 g for the first set-up and 10 mg for the second one). The mass loss of solid samples showed similar time evolutions for both devices. It indicated a first period of dehydrochloruration in the temperature range 300 - 400 degrees C followed by the pyrolysis of intermediary products in the temperature range 400-550 degrees C yielding gaseous and liquid volatiles fraction and a black carbonaceous char. Two kinetic models from literature were tested in order to describe the weight loss kinetics of polychloroprene during the pyrolysis process: an empirical one which considered three organic fractions decomposing separately and a more detailed one involving 191 reactions and 38 species (molecules and radicals). It was found that for the TG-DTA experiments both models are appropriate while for the ``Aubry'' furnace it would be necessary to use a modified kinetic model which takes into account the heat transfer

Numerical Simulation of Back Discharge Ignition

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15 Years or R&D on Electrofiltration for Gas Cleaning

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Densification of UO2 pellets by microwave sintering using an instrumented multimode cavity

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Design of an instrumented microwave multimode cavity for sintering of nuclear ceramics

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