1,721,084 research outputs found
Low temperature drying of pomace in Spout and Spout-Fluid Beds
No full textThe solid residue that originates from virgin olive oil production has a consistency that falls between a paste and a particulate solid, consists of two phases: the crushed olive kernel and the fruit pulp. The kernel particles can be used as high quality solid fuel, while oil can be extracted from the pulp residue. Two technological problems should be tackled to optimize the extraction process: drying the solid residue at low temperature and separating the two phases. The pomace was dried batchwise in a 0.17 m diameter spouted bed and continuously in a 0.29 m diameter draft tube spout-fluid bed with independent control of the air flow rate to the spout and to the annulus. Experimental drying tests were carried out. The drying kinetics were measured during each test in the 0.17 m diameter bed. The solids circulation rate was measured in the larger unit, under a wide range of air flow rates to both the spout and the annulus. An operation regime map has been obtained from a characterization of the quality of the fluidization under a wide range of hydrodynamical conditions. The drying efficiency of both apparatuses was studied
INAIL POLITECNICO DI TORINO E UNIONE INDUSTRIALE REALIZZANO UN LABORATORIO PER LO STUDIO DELLE ATMOSFERE ESPLOSIVE PROVOCATE DA POLVERI AERODISPERSE
No full textExperimental Measurement Of Radial Gas Dispersion in the Riser of a Circulating Fluidized Bed
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A GENERALISED EXPLICIT METHOD FOR THE PACKING LIMIT MANAGEMENT IN DENSE GAS-SOLID FLOW CFD SIMULATIONS
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A critical comparison of frictional stress models applied to the simulation of bubbling fluidized beds
No full textThe behaviour of a gas-solid flow in a bubbling fluidized bed operated near the minimum fluidization condition is strongly influenced by the frictional stresses between the particles, these being highly concentrated and their motion dominated by enduring contact among them and with the walls. The effect of the introduction of frictional stresses in a Eulerian-Eulerian two fluid model based on the kinetic theory of the granular flow is evaluated. The models of Johnson and Jackson [1987. Frictional-collisional constitutive relations for granular materials, with application to plane shearing. Journal of Fluid Mechanics 176, 67-93], Syamlal et al. [1993. Mfix documentation: volume I, theory guide. Technical Report DOE/METC-9411004, NTIS/DE9400087, National Technical Information Service, Springfield, VA], and Srivastava and Sundaresan [2003. Analysis of a frictional-kinetic model for gas-particle flow. Powder Technology 129, 72-85] are compared with the kinetic theory of the granular flow and with experimental data both in a bubbling fluidized bed with a central jet and in a bubbling fluidized bed with a porous distributor. The predicted evolution of the bubble diameter along the height of the fluidized beds is examined, the shapes of the bubbles predicted by the models are compared and the evolution in time of the bubbles is shown. In the case of the bed with a central jet, the bubble detachment time is also calculated. The results show that the introduction of a frictional stress model improves the prediction of the bubbles diameter in a bubbling fluidized bed with a central jet and positively affects the bubbles diameter distribution in a uniformly fed bubbling fluidized bed. The high sensitivity of the model to the value of the particulate phase fraction at which frictional stresses start to be accounted for is pointed out through a sensitivity analysis performed on the Srivastava and Sundaresan [2003. Analysis of a frictional-kinetic model for gas-particle flow. Powder Technology 129, 72-85] mode
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