Spout-fluid Bed Research Articles

A plasma spout-fluid bed for the recovery of vanadium from vanadium ore

A laboratory scale plasma spout-fluid bed was developed for the sodium carbonate roasting of vanadium mineral concentrate to extract vanadium as sodium metavanadate. A 20-kW d.c. plasma torch was used with nitrogen and argon as the plasma gases. The bed stability and degree of vanadium conversion were analyzed as a function of temperature, time, and concentrate-to-salt ratio. It was shown that heating and reaction occur primarily when particles pass through the plasma spout. If spout temperatures are too high, melting and agglomeration lead to instability of the bed. Although batch operation was rather unsuccessful due to elutriation of the salt during heat-up, simulated continuous operation gave high conversion rates.

SPOUTED AND SPOUT-FLUIDIZED BEDS FOR GRAM DRYING

ABTRACT The objectives of this work are to analyze the drying performance of conical-cylindrical spouted bed (CSB) dryers for three different grains (rice, corn and wheat), and to compare the drying efficiency of CSB dryers with that of spout-fluid bed (SFB) dryers. A PC-program was developed for: (I) -optimization of the CSB dryer dimensions; (2) -simulation of drying grains in the optimized CSB dryer (including start-up period); and, (3) -analysis of the drying performance in a similar SFB dryer. The liquid diffusion model is used to describe the falling rate drying period. Semi-empirical correlations available in the literature as well as information obtained in the authors' laboratory for spouted and spout-fluidized beds of grains are used to describe the aerodynamic parameters. The results are presented in terms of the size of the dryer, energy consumption, air handling requirement, drying characteristics etc for different drying conditions. The drying effeciency in a CSB is compared with that in a s...

The annulus of a spouted bed as a three-dimensional electrode

The possibility of application of spouted and spout-fluid beds in electrochemistry is discussed and a comparison with other three-dimensional systems is made. It is shown that spouted and spout-fluid beds may be used as three-dimensional electrodes whose hydrodynamic behaviour provides all the good properties of packed and fluidized-bed electrodes and simultaneously eliminates their disadvantages and restrictions. Copper electrolysis was carried out in a spouted bed system. The identical copper deposit on various particles, chosen at random, indicates that the particles have the same history of treatment in the spouted bed. The deposit on one particle shows uniform treatment of every part of its surface regardless of surface relief. The high quality of the copper deposit suggests that electrochemical reaction is not limited by diffusion.

Solids circulation in a spout‐fluid bed with draft tibe

AbstractA 20 cm diameter semi‐cylindrical spout‐fluid bed with a draft tube has been used to study the effects of operating and geometric parameters on the solids circulation rates at ambient temperature. A new technique has been developed for measuring the solids fluxes with great accuracy. Solids circulation rate data have been found to be strongly influenced by both geometry and relative magnitude of spouting and auxiliary gas flowrates, as they in turn affect the flow of the gas‐solid mixture inside the draft tube. The solids circulation rate was greatly enhanced when an auxiliary flow aerated the annular region and such enhancement has been found to be linearly dependent on the auxiliary flow contribution to the total gas flow and on the distance between the base of the draft tube and the inlet nozzle.

Spouted, fluidized and spout-fluid bed combustion of bituminous coals

Spouted, fluidized and spout-fluid bed combustion of three bituminous coals or coal rejects of differing ash contents was carried out in a 0.3 m internal diameter combustor. Coal feed rates were between 6 and 22 kg h −1, excess air was usually 15–20%, the internal coil coolant was either air or water, and the average bed temperature ranged from 740 to 980 °C. Each of the three contacting modes was able to burn the coal to which it was subjected. Although differences in combustion performance between the three modes were generally small, the experimental results indicated that the spout-fluid bed tended to give somewhat higher combustion efficiencies at the lower temperatures, greater temperature uniformity and improved bed-to-immersed-surface heat transfer compared with the other two modes of operation. For all three modes, combustion efficiencies were over 90%, provided that bed temperatures were higher than 870 °C and that fines captured in the primary cyclone were recycled to the bed. The size and density of inert bed materials played a significant role. Denser and coarser inert particles tended to segregate, leaving burning char particles at or near the bed surface. Bed-to-cooling-coil heat transfer coefficients were of similar magnitude to those measured in earlier studies.

Flow regimes and combustion behaviour in coal-burning spouted and spout-fluid beds

A study of coal combustion was carried out in a 0.15-m diameter half-column spout-fluid bed combustor, in which a sub-bituminous Alberta coal was burned in inert beds of sand. High temperatures promoted spout instability leading to earlier appearance of pulsatory spouting, the jet-in-fluidized-bed regime, and slugging than for room temperature operation. While radial temperature profiles below the bed surface were quite uniform, axial profiles showed a significant temperature jump in the fountain region above the bed surface. Axial profiles of oxygen concentration fell abruptly at the bed surface due to rapid burning there. The size of inert particles and the amount of auxiliary air were found to influence the hydrodynamics and combustion behaviour.

Hydrodynamics of spout-fluid beds

Experiments were carried out in a half-column incorporating auxiliary flow, introduced through up to five slots along a 60° conical base, in addition to a central flow of air. The column had a diameter of 0.15 m and inlet diameters of either 19 or 25 mm. Three different types of particle were investigated, all with mean particle sizes in the 2 – 4 mm range. Four different flow regimes — fixed bed, spouting with aeration, spout-fluidization and jet in a fluidized bed — were identified and mapped. The minimum total gas flow required for spouting with aeration and for spout-fluidization was always greater than that corresponding to minimum spouting. Gas percolation through the annulus increased by as much as 50% as the proportion of auxiliary flow was increased for a given total gas flow rate. Solids circulation was increased somewhat by addition of auxiliary flow for deep beds, but a decrease occurred for shallow beds. The overall bed pressure drop under minimum spouting with aeration conditions increased linearly with auxiliary flow. On the other hand, the fountain height decreased as the fraction of auxiliary flow was increased for a fixed total gas flow, and increased with auxiliary flow for a fixed central gas flow. The empirical correlation of McNab predicted the average spout diameter well if the sum of the central and auxiliary flows was used in the correlation.

Flow regimes for spout‐fluid beds

The Canadian Journal of Chemical EngineeringVolume 62, Issue 6 p. 825-829 Article Flow regimes for spout-fluid beds D. V. Vuković, Corresponding Author D. V. Vuković University of Belgrade, 11001 Belgrade POB 494, Yugoslavia D. V. Vuković, Faculty of Technology and Metallurgy Dž. E. Hadžismajlović, Institute for Chemistry, Technology and Metallurgy Ž B. Grbavćić, Institute for Chemistry, Technology and Metallurgy R. V. Garić, Faculty of Technology and Metallurgy H. Littman, Rensselaer Polytechnic Institute, Troy, N.Y. 12180–3590 USASearch for more papers by this authorDž. E. Hadžismajlović, Corresponding Author Dž. E. Hadžismajlović University of Belgrade, 11001 Belgrade POB 494, Yugoslavia D. V. Vuković, Faculty of Technology and Metallurgy Dž. E. Hadžismajlović, Institute for Chemistry, Technology and Metallurgy Ž B. Grbavćić, Institute for Chemistry, Technology and Metallurgy R. V. Garić, Faculty of Technology and Metallurgy H. Littman, Rensselaer Polytechnic Institute, Troy, N.Y. 12180–3590 USASearch for more papers by this authorŽ B. Grbavćić, Corresponding Author Ž B. Grbavćić University of Belgrade, 11001 Belgrade POB 494, Yugoslavia D. V. Vuković, Faculty of Technology and Metallurgy Dž. E. Hadžismajlović, Institute for Chemistry, Technology and Metallurgy Ž B. Grbavćić, Institute for Chemistry, Technology and Metallurgy R. V. Garić, Faculty of Technology and Metallurgy H. Littman, Rensselaer Polytechnic Institute, Troy, N.Y. 12180–3590 USASearch for more papers by this authorR. V. Garić, Corresponding Author R. V. Garić University of Belgrade, 11001 Belgrade POB 494, Yugoslavia D. V. Vuković, Faculty of Technology and Metallurgy Dž. E. Hadžismajlović, Institute for Chemistry, Technology and Metallurgy Ž B. Grbavćić, Institute for Chemistry, Technology and Metallurgy R. V. Garić, Faculty of Technology and Metallurgy H. Littman, Rensselaer Polytechnic Institute, Troy, N.Y. 12180–3590 USASearch for more papers by this authorH. Littman, Corresponding Author H. Littman University of Belgrade, 11001 Belgrade POB 494, Yugoslavia D. V. Vuković, Faculty of Technology and Metallurgy Dž. E. Hadžismajlović, Institute for Chemistry, Technology and Metallurgy Ž B. Grbavćić, Institute for Chemistry, Technology and Metallurgy R. V. Garić, Faculty of Technology and Metallurgy H. Littman, Rensselaer Polytechnic Institute, Troy, N.Y. 12180–3590 USASearch for more papers by this author D. V. Vuković, Corresponding Author D. V. Vuković University of Belgrade, 11001 Belgrade POB 494, Yugoslavia D. V. Vuković, Faculty of Technology and Metallurgy Dž. E. Hadžismajlović, Institute for Chemistry, Technology and Metallurgy Ž B. Grbavćić, Institute for Chemistry, Technology and Metallurgy R. V. Garić, Faculty of Technology and Metallurgy H. Littman, Rensselaer Polytechnic Institute, Troy, N.Y. 12180–3590 USASearch for more papers by this authorDž. E. Hadžismajlović, Corresponding Author Dž. E. Hadžismajlović University of Belgrade, 11001 Belgrade POB 494, Yugoslavia D. V. Vuković, Faculty of Technology and Metallurgy Dž. E. Hadžismajlović, Institute for Chemistry, Technology and Metallurgy Ž B. Grbavćić, Institute for Chemistry, Technology and Metallurgy R. V. Garić, Faculty of Technology and Metallurgy H. Littman, Rensselaer Polytechnic Institute, Troy, N.Y. 12180–3590 USASearch for more papers by this authorŽ B. Grbavćić, Corresponding Author Ž B. Grbavćić University of Belgrade, 11001 Belgrade POB 494, Yugoslavia D. V. Vuković, Faculty of Technology and Metallurgy Dž. E. Hadžismajlović, Institute for Chemistry, Technology and Metallurgy Ž B. Grbavćić, Institute for Chemistry, Technology and Metallurgy R. V. Garić, Faculty of Technology and Metallurgy H. Littman, Rensselaer Polytechnic Institute, Troy, N.Y. 12180–3590 USASearch for more papers by this authorR. V. Garić, Corresponding Author R. V. Garić University of Belgrade, 11001 Belgrade POB 494, Yugoslavia D. V. Vuković, Faculty of Technology and Metallurgy Dž. E. Hadžismajlović, Institute for Chemistry, Technology and Metallurgy Ž B. Grbavćić, Institute for Chemistry, Technology and Metallurgy R. V. Garić, Faculty of Technology and Metallurgy H. Littman, Rensselaer Polytechnic Institute, Troy, N.Y. 12180–3590 USASearch for more papers by this authorH. Littman, Corresponding Author H. Littman University of Belgrade, 11001 Belgrade POB 494, Yugoslavia D. V. Vuković, Faculty of Technology and Metallurgy Dž. E. Hadžismajlović, Institute for Chemistry, Technology and Metallurgy Ž B. Grbavćić, Institute for Chemistry, Technology and Metallurgy R. V. Garić, Faculty of Technology and Metallurgy H. Littman, Rensselaer Polytechnic Institute, Troy, N.Y. 12180–3590 USASearch for more papers by this author First published: December 1984 https://doi.org/10.1002/cjce.5450620613Citations: 45AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume62, Issue6December 1984Pages 825-829 RelatedInformation

Mass transfer in liquid spout—fluid beds of ion exchange resin

Experiments were carried out to determine the liquid side mass transfer coefficient in spout-fluid beds of ion exchange resin. The ratio (Sh S—F) overall/Sh fluidized is correlated with the ratio of the flow rate through the nozzle to the total flow rate for different experimental conditions. A method for the calculation of the initial conversion in a spout—fluid bed is given and a model of a spout—fluid bed ion exchanger involving liquid flow pattern is proposed. Particle motion in the annulus was measured. The model is based on the assumption of film diffusion control. Experimental results obtained in the study of the conversion of ion exchange resin “Amberlite IR-120” in Na + form and diluted hydrochloric acid in a spout—fluid bed are in agreement with theoretical predictions.

Mass transfer in liquid spout—fluid beds of ion exchange resin

Experiments were carried out to determine the liquid side mass transfer coefficient in spout—fluid beds of ion exchange resin. The ratio (Sh S—F) overall/Sh fluidized is correlated with the ratio of the flow rate through the nozzle to the total flow rate for different experimental conditions. A method for the calculation of the initial conversion in a spout—fluid bed is given and a model of a spout—fluid bed ion exchanger involving liquid flow pattern is proposed. Particle motion in the annulus was measured. The model is based on the assumption of film diffusion control. Experimental results obtained in the study of the conversion of ion exchange resin “Amberlite IR-120” in Na + form and diluted hydrochloric acid in a spout—fluid bed are in agreement with theoretical predictions.

Macroscopic Streamline Integral Relations for Two-Phase Flows

A spout-fluidized bed is an example of a situation where a nonuniform fluid flow through a bed of particles causes particle circulation. Several integral relations are derived from a steady, two-dimensional two-phase flow model. The vorticity of the particle motion enclosed by a particle streamline is shown to be equal to the fluid vorticity enclosed by that streamline. The net flux of fluid vorticity through a particle streamline is shown to be equal to zero. The pressure drop along a fluid streamline is related to the net drag force along that streamline. The net flux of particle vorticity through a fluid streamline is given in terms of the pressure drop. Implications of these relations to the mechanics of particle-fluid flows are discussed. Relations giving the particle vorticity in terms of an integral of the fluid vorticity, and vice versa, are presented. A possible numerical scheme for calculation of the flow fields is discussed.