Hydrogen enriched syngas production via gasification of biofuels pellets/powders blended from olive mill solid wastes and pine sawdust under different water steam/nitrogen atmospheres

International audienceIn this paper we focused on the gasification of biomass charcoal using a macro TG under the CO2 gasifier agent mixed with nitrogen at different mass molar fractions; 40%, 70% and 100% respectively. Moreover, the gasification tests were conducted at different isothermal temperatures; 750°C, 800°C, and 900°C respectively. For this purpose, two densified residues were selected; the exhausted olive mill solid wastes (EOMSW) and the pine sawdust (PS). Then, four different samples were prepared from these residues when investigating the impregnated and the non-impregnated samples using the olive mill waste water (OMWW) as by-product for the impregnation process. A comparison between obtained results during this current study and those obtained during our latest study when using steam as gasifier agent was carried out. We observe that the mass loss profiles meet the usual lingo-cellulosic gasification behaviours. Moreover, the increase of the isothermal temperatures or of the CO2 percentage affects positively the conversion, the gasification rate and the char reactivity. It is worth noting that the CO2 agent acts differently by comparison to the steam. Indeed, the gasification process using steam is found to be faster and more reactive

Converting CO2 from a Harmful Gas to a Renewable Source of Matter and Energy: A Review

The emission of greenhouse gases, specifically CO2, has reached non-acceptable levels causing global warming with adverse effects. Owing to rigorous ongoing research, these harmful substances might be converted to beneficial sources. The main objective of this study was to review the most effective processes that might utilize carbon dioxide to produce various substances, chemicals, and energy. For this, different existing and projected short-term and long-term strategies have been presented and discussed. Specifically, processes like the artificial tree of Lackner to capture CO2, chemical looping combustion (CLC), the application of CO2 in the food and processing industry, wastewater treatment, supercritical and refrigerant CO2, hydrogenation of CO2, the cultivation of microalgae, thermolysis, electrolysis, and photoelectrocatalysis techniques for producing hydrogen and biofuels, based on thermochemical processes, are the most promising ways to reduce and reuse CO2. Such behavioral changes can lead to the exchange of CO2 between natural reservoirs and help to maintain CO2 equilibrium among the atmosphere, the upper mixed layer of the sea, and the deep sea. Consequently, the mean global temperature and the climate are directly affected.</jats:p

A Comprehensive Review of Syngas Production, Fuel Properties, and Operational Parameters for Biomass Conversion

International audienceThis study aims to provide an overview of the growing need for renewable energy conversion and aligns with the broader context of environmentally friendly energy, specifically through producing syngas from biomass. Unlike natural gas, which is mainly composed of methane, syngas contains a mixture of combustible CO, H2, and CnHm. Therefore, optimizing its production requires a thorough examination of various operational parameters such as the gasifying agent, the equivalence ratio, the biofuel type, and the state, particularly in densified forms like pellets or briquettes. As new biomass sources are continually discovered and tested, operational parameters are also constantly evaluated, and new techniques are continuously developed. Indeed, these techniques include different gasifier types and the use or non-use of catalysts during biofuel conversion. The present study focuses on these critical aspects to examine their effect on the efficiency of syngas production. It is worth mentioning that syngas is the primary gaseous product from gasification. Moreover, it is essential to note that the pyrolysis process (prior to gasification) can produce, in addition to tar and char, a mixture of gases. The common feature among these gases is their versatility in energy generation, heat production, and chemical synthesis. The analysis encompasses the resulting gas features, including the yield and composition, mainly through the hydrogen-to-carbon monoxide ratio and the carbon monoxide-to-carbon dioxide ratio, as well as the lower heating value and considerations of the tar yield.</div

A Numerical Study of Turbulent Combustion of a Lignocellulosic Gas Mixture in an Updraft Fixed Bed Reactor

International audienceLignocellulosic biomass is an established source of energy with various applications. Yet, its diversity renders the proper combustion of its thermochemical degradation vapors challenging. In this work, the combustion of syngas obtained from biomass thermochemical conversion was numerically investigated to limit pollutant emission. The Computational Fluid Dynamics (CFD) simulation was performed using the open-source OpenFOAM. The reactor was considered in an axisymmetric configuration. The gas mixture resulting from the pyro-gasification devolatilization was composed of seven species: CO, CO2, H2O, N2, O2, light, and heavy hydrocarbon, represented by methane (CH4) and benzene (C6H6), respectively. The evolutions of mass, momentum, energy, and species’ concentrations were tracked. The flow was modeled using the RANS formulation. For the chemistry, reduced kinetic schemes of three and four steps were tested. Moreover, the Eddy Dissipation Concept (EDC) model was used to account for the turbulence–chemistry interaction. The numerical prediction enabled us to describe the temperature and the species. Results show that all transported variables were closely dependent on the mass flow rate of the inflow gas, the primary and the secondary air injections. Finally, from a process perspective, the importance of the secondary air inlet to limit pollutants emissions can be concluded