Characterization of sulfur and chlorine behavior during pyrolysis of biomass and waste

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Hydrodynamic study of a circulating fluidized bed used for biomass gasification between 20 °c and 900 °c

This work, carried out in the GAYA project frame and subsidized by ADEME, concerns the hydrodynamic study of a 60 kWth circulating fluidized bed pilot plant constructed at the Laboratoire de Génie Chimique in Toulouse for biomass gasification. In that process, biomass gasification and heating of fluidisation material (sand, olivine, catalyst…) which also acts as heat transfer medium, are performed in two separate reactors: a dense fluidized bed and a transported bed. Thermal energy, required in order to heat the fluidisation material, is supplied by the partial combustion of the char produced in the gasification reactor. The hydrodynamic study carried out at atmospheric pressure between 20 °C and 900 °C leads to the determination of the influence of the temperature and media average particle size (olivine), the reactor geometric properties and the fluidization gas nature (air or steam) on the media hydrodynamic parameters such as the minimum fluidization velocity and porosity, the bed expansion and the solid transport velocity. Results have shown that the minimal fluidization and transport velocity decrease with the bed temperature increase. However, the bed expansion is not affected by this factor. Furthermore, the particles transport happens from the terminal falling velocity and increases with the gas velocity. The fluidization gas nature has a significant effect on the minimal fluidization velocity, but not on the bed expansion. Correlations are proposed in order to estimate the characteristic parameters of the olivine hydrodynamic behavior depending on the temperature, the fluidization gas nature and the solid particle size

Hydrodynamic Study of a Circulating Fluidized Bed at High Temperatures: Application to Biomass Gasification

Experimental data on the hydrodynamic behavior of dense and circulating fluidized beds at high temperatures are scarce in the literature. This work deals with the hydrodynamic study of a Fast Internally Circulating Fluidized Bed (FICFB) used for biomass gasification. The first part of this study investigates the influence of the bed temperature (between 20 and 950 °C) and the nature of fluidizing gas (air or steam) on the hydrodynamic parameters of a dense fluidized bed of olivine particles (i.e. minimum fluidization velocity and voidage as well as average voidage). Three olivine batches are used with a mean Sauter diameter of 282, 464 and 689 μm, respectively. Experimental results are compared with different empirical correlations from the literature to evaluate their validity under elevated temperature conditions. Besides, two dimensionless correlations calculating the minimum fluidization velocity and average bed voidage are proposed. The second part of this study focuses on the hydrodynamic behavior of an FICFB operating between 20 and 850 °C. The effect of different process parameters (i.e. bed material nature, air velocity, solids inventory, bed temperature) on the solids circulation flow rate is investigated. It was found that the transport velocity Utr is not affected by the bed temperature and the bed material inventory. It mainly depends on the terminal settling velocity Ut of bed material particles. Besides, key parameters controlling solids flow rate are the combustor gas velocity and the solids inventory. An increase in these parameters leads to a higher circulation flow rate

Fluidised Bed Gasification of Diverse Biomass Feedstocks and Blends—An Overall Performance Study

The aim of this work is to investigate the fluidised bed gasification of several pure and blended feedstock prepared in the form of pellets: oak bark, two bark/wheat straw blends (85/15 and 50/50 wt%) and lignin residue remaining from bioethanol production. Gasification conditions were defined to be representative of dual fluidised bed ones (steam gasification at 850 °C, followed by air combustion of the char). The cold gas efficiency (77–81%), gas composition and tar content (0.9–2.3 g/kgdaf) are close for the gasification of bark and the two bark/wheat straw blends. For lignin residue, the cold gas efficiency is lower (71%), and the tar content is 9.1 g/kgdaf. The agglomeration propensity is much higher for lignin residue than for the other feedstock. This was put into evidence with in-bed temperature measurements at different levels, and confirmed with post-test size screening of the bed material particles. The 50/50 wt% bark/wheat straw blend seems to undergo defluidisation in combustion, however followed by refluidisation of the bed. These findings were also well correlated with a predictive model for defluidisation

En marge des métropoles, le carreau Wendel en Lorraine: de la friche industrielle au projet culturel

En s’appuyant sur le nouveau concept d’économie culturelle, cet article a pour objectif d’étudier le rôle de la culture dans le Bassin Houiller Lorrain confronté à la fin de l’exploitation minière et situé à la frontière sarro-lorraine. Il interroge la relation entre culture et marge. Comment la culture est-elle mobilisée pour faire face à diverses formes de marginalisation? Quel renouveau, quelle reconversion et quelle résilience? Deux initiatives culturelles sont étudiées: la valorisation du patrimoine industriel et le développement d’un spectacle vivant issu de l’histoire locale. En premier lieu, l’article brosse les enjeux et les perspectives de l’économie culturelle. Ensuite, il présente le carreau Wendel en 2008, quatre ans après la fermeture des Houillères du Bassin de Lorraine. La troisième partie est consacrée au spectacle « Les enfants du charbon », né du vide issu de la fermeture et porté par des acteurs locaux. La dernière partie évalue la capacité de ce projet culturel à générer un développement local en jouant sur les synergies possibles avec d’autres acteurs.Drawing on the new concept of the cultural economy, this article has as its objective to study the role of culture in the Lorraine coal basin confronted with the end of mining activity. Questions of culture at the margins are raised in this case by asking how culture is mobilized to face up to diverse forms of marginalization and how renewal, reconversion, and resilience are involved in that process. Two cultural initiatives are studied here : the increased prestige of the industrial heritage and the development of live shows based on local history. The article first paints a broad picture of the stakes involved and then examines the prospect for an economy focused on culture rather than mining. In 2008, the Carreau Wendel mining-site museum opened four years after the closing of the coal mines of Lorraine. The third part is devoted to a live show « the coal children » conceptualized after mine closure by local actors. The last part evaluates the capacity of this cultural project to generate local development by playing on the synergies possible with other actors

Influence of H2O, CO2 and O-2 addition on biomass gasification in entrained flow reactor conditions: Experiments and modelling

International audienceBiomass gasification in Entrained Flow Reactor (EFR) is both studied with experiments in a drop tube reactor and modelling with a 1-D model (GASPAR). Operating conditions are chosen thanks to results of a preliminary modelling of an industrial EFR. Influence of addition of steam (0.55 g/g db), carbon dioxide (0.87 g/g db) and oxygen (Equivalent Ratio: 0-0.61) is investigated between 800 and 1400 degrees C with beech wood particles sieved between 315 and 450 mu m as feedstock. The model takes into account pyrolysis reaction, gas phase reaction with a detailed chemical scheme (176 species, 5988 reactions), char gasification by steam and CO2 and soot formation. H2O or CO2 addition has no influence on gasification product yields at 800 and 1000 degrees C, while at 1200 and 1400 degrees C the char gasification is significantly enhanced and soot formation is certainly inhibited by OH radical which reacts with soot precursors. The modification of output gas phase composition is mostly due to WGS reaction which reaches thermodynamic equilibrium from about 1200 degrees C. As expected, O-2 has a significant influence on gas and tar yields through combustion reactions. Char and soot yields decrease as ER increases. The GASPAR model allows a good prediction of gas and char and gives relevant evolution of soot and tar yields on the large majority of conditions studied

Pyrolysis and gasification of solid waste and its components in a lab scale induction-heating reactor

International audienceThe present study investigates the thermochemical conversion of solid recovered fuel, represented by selected “model materials”. A laboratory-scale induction heated device was specifically developed to achieve gasification conditions close to those encountered in a fluidized bed reactor. The novel device can handle up to 5 grams of solid, allowing fast heating rates (near 70°C/s) and a homogeneous distribution of temperature all along the reactor. Pyrolysis tests of a SRF sample and four model materials (Polyethylene (PE), Polyethylene Terephthalate (PET), beech wood, cardboard) were performed at 800°C. The yield and composition of the produced gas for each sample were determinated. Experimental results will help to elucidate the relation between the initial components of waste derived fuels and the obtained reaction products

Pyrolysis of solid waste and its components in a lab scale induction-heating reactor

International audienceThe present study investigates the thermochemical conversion of Solid Recovered Fuel (SRF), represented by selected “model materials”. A laboratory-scale induction heated device was specifically developed to achieve fast pyrolysis conditions close to those encountered in a fluidized bed reactor. The novel device can handle up to 5 grams of solid, allowing fast heating rates (near 70°C/s) and a homogeneous distribution of temperature all along the reactor. Pyrolysis tests of a SRF sample and four model materials (Polyethylene, Polyethylene Terephthalate, beech wood, cardboard) were performed at 800°C. The yield and composition of the produced gas for each sample were determined. Experimental results will help to elucidate the relation between the initial components of waste derived fuels and the obtained reaction products

Design and thermal characterization of an induction-heated reactor for pyrolysis of solid waste

International audienceA small-scale induction heated reactor (IHR) was specifically developed to study fast pyrolysis, here investigated as the first step of gasification process, representing some of the reaction conditions encountered in a fluidized bed reactor. First, the thermal response of the system was characterized at transient and steady state, and CFD calculations were performed to have a complete description of the temperature profiles inside the reactor. The novel device can handle a few grams of solid at temperatures up to 900 °C, allowing high heating rates (near 80 °C/s) and a uniform distribution of temperature in the sample. Secondly, the pyrolysis of a solid recovered fuel (SRF) sample was carried out at 800 °C, and the distribution and composition of reaction products were analyzed and compared with tests performed in a pilot scale fluidized bed reactor (FBR). The results obtained in the IHR showed a good reproducibility. The same main gas and tar species were measured in the IHR and FBR, with however some differences in gas and tar composition that were attributed to the extent of secondary reactions, enhanced by higher heat transfer rates and the presence of bed material in the FBR