NUMERICAL SIMULATION OF GAS-SOLID FLOW IN AN INTERCONNECTED FLUIDIZED BED

The gas-particles flow in an interconnected bubbling fluidized cold model is simulated using a commercial CFD package by Ansys. Conservation equations of mass and momentum are solved using the Eulerian granular multiphase model. Bubbles formation and their paths are analyzed to investigate the behaviour of the bed at different gas velocities. Experimental tests, carried out by the cold model, are compared with simulation runs to study the fluidization quality and to estimate the circulation of solid particles in the bed

influence of piston shape and injector geometry on combustion and emission characteristics of syngas in direct injection spark ignition engine

Abstract This paper presents a numerical study of the influence of piston shape and injector geometry on combustion and emissions characteristics of a direct-injection spark-ignition engine fueled by syngas (50% by volume of hydrogen, 50% by volume of carbon monoxide) under low/medium load conditions. Three different piston cup geometries namely: High-clearance Combustion Cup (HCC), Low-clearance Combustion Cup (LCC) and Omega Combustion Cup (OCC) have been considered with a compression ratio of 14. An axial full-cone gas jet injector has been considered together with a hollow-cone gas jet injector with several included half-angles, i.e. 30°, 45°, 52.5° and 60°. Computational fluid dynamics modelling has been performed to simulate the combustion process. The results indicate that, in terms of performance, OCC shape is favorable, even if OCC generates relatively higher NOx than the other two configurations. A further analysis has been performed by simulating an engine with OCC piston shape and an included half-angle of injection of 30°, by varying the Start Of Injection (SOI). The results show that the flame propagation velocity reduces as the SOI advances, since the fuel distribution becomes more homogeneous approaching to a premixed case. However, the flame speed reduction is partially balanced by the disappearance of very lean regions thanks to fuel convection and diffusion

Thermodynamic Analysis of Biomass Gasification by Different Agents

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Towards the Circular Economy of Rare Earth Elements: Lanthanum Leaching from Spent FCC Catalyst by Acids

Rare earth elements (REEs) are strategic materials widely used in different applications from Information and Communication Technologies (ICT) to catalysis, which are expected to grow more in the future. In order to reduce the impact of market price and reduce the environmental effect from soil extraction, recovery/purification strategies should be exploited. This paper presents a combined acid-leaching/oxalate precipitation process to recover lanthanum from spent FCC catalyst using nitric acid. Preferred to hydrochloric and sulphuric acid (preliminary assessed), HNO3 showed a good capability to completely leach lanthanum. The combination with an oxalate precipitation step allowed demonstrating that a highly pure (>98% w/w) lanthanum solid can be recovered, with a neglectable amount of poisoning metals (Ni, V) contained into the spent catalyst. This could open a reliable industrial perspective to recover and purify REE in the view of a sustainable recycling strategy

Preparazione e caratterizzazione di materiali metallo-organici per separazione di syngas e catalisi

Dottorato di Ricerca in Ingegneria Chimica e dei Materiali, Ciclo XXII, a.a.2008-2009Università della Calabri

Numerical simulation of gas-solid flow in an interconnected fluidized bed

The gas-particles flow in an interconnected bubbling fluidized cold model is simulated using a commercial CFD package by Ansys. Conservation equations of mass and momentum are solved using the Eulerian granular multiphase model. Bubbles formation and their paths are analyzed to investigate the behaviour of the bed at different gas velocities. Experimental tests, carried out by the cold model, are compared with simulation runs to study the fluidization quality and to estimate the circulation of solid particles in the bed

Second generation biodiesel synthesis and its innovative utilization in order to improve biomass gasification process

Dottorato di Ricerca in: Chemical Engineering and Materials, Ciclo XXII, a.a.2008-2009Università della Calabri

A CFD Investigation of Syngas Spark Ignition Engines

In the last two decades, specific interest has been addressed towards Internal Combustion Engines (ICEs) powered by bio-fuels. The growing interest for bio-fuels is related to constantly increasing stringent exhaust gases regulations and to a remarkable request of reduction of CO2- emissions. In the same direction (CO2-emissions reduction) and, additionally with the aim to minimize the dependence from crude oil, several alternative fuels have gained attention in the automotive industry. The fuels of bio-origin can provide a feasible solution to worldwide petroleum crisis by promising a sustainable development, energy conservation and environmental preservation. Gasoline and diesel-driven engines are the major sources of Green- House Gases (GHG) emissions [1-3]. Scientists around the world have been explored several alternative energy sources including biomass derived fuels, biogas, primary alcohol, vegetable oils, biodiesel, etc. These alternative energy sources are largely environmental-friendly but their use needs further investigations in relation to the specific applications. Some of them can be used directly while others need to be formulated to bring their relevant properties closer to those of conventional fuels. This work deals with some features of spark ignition engines powered by syngas. The ENEA GRID Cresco resources have been used to perform accurate simulations using an advanced parallel CFD code