Valorisation de biomasse en vecteur énergétique par voie thermochimique solaire

Gasification is an endothermic thermochemical process allowing the valorization of biomass into syngas. This thesis work proposes to replace the conventional autothermal process by an allothermic solar process to improve feedstock valorization, enhance syngas quality and store the solar energy. An exhaustive bibliographic review of existing reactors allowed for the identification of technological locks. Involved thermodynamic equilibrium were studied and the possibility of using metal oxides as oxidizing agent was investigated. Experimental campaigns with a fast induction heating batch reactor and a tubular solar reactor were performed for the identification of key factors for solar gasification and the proposal of an innovative solar reactor. A 1.5 kW spouted bed reactor was designed, built and tested under concentrated solar power at the CNRS-PROMES laboratory. A parametric study was realized to identify the reactor optimal operating conditions (oxidant type and flow rate, temperature, direct/indirect heating). The reactor demonstrated the possibility for continuous gasification of 120 g/h of biomass with a 30% solar-to-chemical energy conversion efficiency at 1300°C. The energy potential of the biomass was improved by 21%. A 3D thermal model of the reactor wasdeveloped to study direct and indirect heating configurations and suggest avenues of improvements.La gazéification est un procédé thermochimique endothermique permettant la valorisation de biomasse sous forme de gaz de synthèse. Ce travail de thèse propose de substituer au procédé autotherme conventionnel un procédé allotherme solaire pour augmenter la valorisation matiére, améliorer la qualité du gaz de synthése et stocker durablement l'énergie solaire. Une étude bibliographique exhaustive des réacteurs existants a permis d'identifier les verrous technologiques à lever. Les équilibres thermodynamiques mis en jeu ont été étudiés et la possibilité d'utiliser des oxydes métalliques comme agent oxydant a été explorée. Des campagnes expérimentales sur un réacteur batch à chauffage rapide par induction et un réacteur solaire tubulaire ont permis d'identifier les facteurs clés de la gazéification par voie solaire et de concevoir un banc expérimental pour le test du nouveau réacteur. Un réacteur à jet de 1,5 kW fut conçu, fabriqué et validé expérimentalement sous flux solaire concentré au laboratoireCNRS-PROMES. Une étude paramétrique fut réalisée pour identifier les conditions optimales de fonctionnement du réacteur (type et débits d'oxydant, température, mode de chauffage direct/indirect). Le réacteur a démontré la possibilité de gazéifier en continu 120 g/h de biomasse avec un rendement thermochimique de 30% à 1300°C. Une amélioration du potentiel énergétique de la biomasse de 21% a été atteinte. Un modèle thermique 3D du réacteur a été développé afin d'étudier les modes de chauffage direct et indirect et de proposer des pistes d'amélioration

Biomass Gasification in an Innovative Spouted-Bed Solar Reactor: Experimental Proof of Concept and Parametric Study

International audienceSolar thermochemical gasification of lignocellulosic biomass promises a new path for the production of alternative fuels as well as storage and transport of solar energy as a convertible and transportable fuel. The use of concentrated solar energy as the external heat source for the high-temperature reaction allows the production of high-value syngas with both higher energy conversion efficiency and reduced cost of gas cleaning and separation, while saving biomass feedstock. A newly designed solar reactor based on the principle of a spouted bed reactor was used for continuous solar-driven gasification of biomass particles. The reliable operation of this 1.5 kW reactor was experimentally demonstrated under real solar irradiation using a parabolic dish solar concentrator. Several types of biomass particles were continuously fed into the reactor at temperatures ranging from 1100 to 1400°C. The injected particles consisted of beech wood or a mix of resinous wood with size ranging from 0.3 to 2 mm. The aim of this study was to achieve a proof of concept for the novel solar reactor applied to biomass gasification. A parametric study of the gasification conditions was realized to optimize the syngas production. The influence of temperature, oxidizing agent nature (H 2 O or CO 2) and flow rate, heating configuration (direct or indirect irradiation), biomass type, particles size, and feeding rate on gas yield and composition was investigated. The syngas yield increased drastically with the temperature for both steam and CO 2 gasification, while increasing the steam content favored H 2 and reduced CO production. Maximum amounts of produced syngas over 70 mmol/g biomass and carbon conversion rates over 90% were achieved. The biomass energy content was solar-upgraded by a factor of 1.10 at 1400°C

A high temperature drop-tube and packed-bed solar reactor for continuous biomass gasification

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Solar Biomass Gasification Combined With Iron Oxide Reduction for Syngas Production and Green Iron Metallurgy

International audienceThe solar gasification of biomass with iron oxide for combined syngas and iron production was investigated. Both solar energy and biomass are promising renewable energies. The process of gasification converts solid carbonaceous feedstocks into either fuels or chemicals. However, conventional processes require partial combustion of the feedstock for energy supply and inherently suffer from high oxygen production costs and low syngas calorific value due to dilution with combustion products. Chemical looping gasification using solid oxides is an alternative option to tackle these issues. By supplying concentrated solar energy as the high-temperature heat source, it is possible to produce even more syngas from the process while enabling solar energy storage into dispatchable fuels. This work proposes to explore solar biomass gasification over iron oxide at high heating rates, representative of the conditions obtained in solar reactors. Thermodynamic equilibriums of gasification reactions between 100 and 1,500 • C were calculated and experimental results obtained at 1,100 • C with a specially designed induction furnace were reported for biomass gasification with iron oxide, water, or carbon dioxide as oxidizing agents. Solid products analysis showed that iron oxide can be reduced to metallic iron depending on the proportion of the oxygen carrier. These results indicate that iron oxide is an effective material for solar biomass gasification producing both syngas and iron via a novel green metallurgical process

Solar thermochemical gasification of wood biomass for syngas production in a high-temperature continuously-fed tubular reactor

International audienceHydrogen Biomass Pyrolysis Gasification Solar reactor a b s t r a c t Biomass gasification is an attractive process to produce high-value syngas. Utilization of concentrated solar energy as the heat source for driving reactions increases the energy conversion efficiency, saves biomass resource, and eliminates the needs for gas cleaning and separation. A high-temperature tubular solar reactor combining drop tube and packed bed concepts was used for continuous solar-driven gasification of biomass. This 1 kW reactor was experimentally tested with biomass feeding under real solar irradiation conditions at the focus of a 2 m-diameter parabolic solar concentrator. Experiments were conducted at temperatures ranging from 1000 C to 1400 C using wood composed of a mix of pine and spruce (bark included) as biomass feedstock. This biomass was used under its non-altered pristine form but also dried or torrefied. The aim of this study was to demonstrate the feasibility of syngas production in this reactor concept and to prove the reliability of continuous biomass gasification processing using solar energy. The study first consisted of a parametric study of the gasification conditions to obtain an optimal gas yield. The influence of temperature, oxidizing agent (H 2 O or CO 2) or type of biomass feedstock on the product gas composition was investigated. The study then focused on solar gasification during continuous biomass particle injection for demonstrating the feasibility of a continuous process. Regarding the energy conversion efficiency of the lab scale reactor, energy upgrade factor of 1.21 and solar-to-fuel thermochemical efficiency up to 28% were achieved using wood heated up to 1400 C

Design and experimental study of a novel solar chemical reactor for hydrogen production from continuous solar-driven biomass gasification

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Design, simulation and experimental study of a directly-irradiated solar chemical reactor for hydrogen and syngas production from continuous solar-driven wood biomass gasification

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Solar Biomass Gasification in Presence of Metal Oxide

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Solar Biomass Gasification in presence of iron oxide

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Hydrogen production from solar-driven biomass gasification in a high-temperature continuously-fed solar reactor

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