Maximum Spoutable Height Research Articles

Hydrodynamics, numerical study and application of spouted bed

Abstract This article reviews the major research and development on spouted beds (SBs). Due to its unique structural and flow characteristics, the SB is a very successful system in most applications. Two-phase and sometimes three-phase interactions generate a large number of variables to be noted in each process. Up-to-date information on the fundamentals and applications of SBs has been briefly presented, based on the published works. Thousands of interesting studies on hydrodynamic characteristics, numerical simulations, and new applications of SBs are reported. In the first step, the present work presents a review of hydrodynamic characteristics (circulation of solids in SB, measurement techniques for particle tracking and empirical hydrodynamics, pressure drop, maximum spoutable height, minimum spouting velocity, and diameter of the spout). In the second step, main mathematical models and computational fluid dynamics (CFD) simulation of the SB to predict and analyze different processes are described. Some main mathematical modeling and the recent advances of two fluid methods and discrete element method approaches in CFD simulation of SBs are summarized. In the last step, some new applications of the SB are presented. As the result of this review, we can observe the importance of further development of hydrodynamics structure, working on modeling and related correlations and improve the applications of SBs.

Cold flow experimental study and computer simulations of a compact spouted bed reactor

Spouted beds are a very interesting class of gas–solid contactors that possess excellent heat transfer and mixing characteristics, while they are particularly suited to process coarse particles. Proper design of such beds requires the prediction of various hydrodynamic characteristics, such as the minimum spouting velocity and maximum spoutable height. Contrary to their typical initial applications, spouted beds have been finding recently more frequent use on the one hand at endothermic processes and on the other hand using much finer particle sizes. In the current work, the hydrodynamic characteristics of a laboratory scale spouted bed of 0.05m diameter have been investigated via cold flow studies using olivine particles of 3.55–5.00×10−4m size. Hydrodynamic parameters have been measured at this compact geometry and fine particle size and were compared with common literature correlations. An empirical correlation was derived to predict the fountain height for the studied fine particle spouted bed. Computer simulations have been further used to investigate the heat transfer characteristics of the bed under endothermic reactive conditions, using methane reforming as a case study. Given sufficient external heat supply, a spouted bed operating at a well-mixed regime can efficiently drive even highly endothermic reactions.

Experimental investigations of a pseudo-2D spout fluidized bed with draft plates

Spout fluidized beds often prove promising for gas–solid contacting operations involving chemical reactions with changing particle size. However, difficulties may arise during operation, such as unstable spouting, dead zones formation and limited flexibility in adjustment of maximum spoutable height and residence time. This can be improved by inserting draft tubes or plates. In this work, the hydrodynamics of a pseudo-2D spout fluidized bed with draft plates was studied by changing the background velocity from 0 to 1.75m/s with increments of 0.25m/s and the spout velocity from 10 to 50m/s with increments of 5m/s. The distinct flow regimes were identified by capturing high-speed images and Fast Fourier transformation (FFT) of measured pressure signals. In addition, the effects of the entrainment height (in the range of 0.03–0.05m), static bed aspect ratio (in the range of 1–1.5) and particle properties (for glass and γ-aluminum oxide particles) on the hydrodynamics were investigated by determining the time-averaged particle volumetric flux by combined particle image velocimetry (PIV) and digital image analysis (DIA) for two regimes namely, spouting-with-aeration (IV) and fluidized bed-spouting-with-aeration (dispersed spout) (VIII).

Comparative Evaluation of Existing Correlations to Predict Spouted Bed Hydrodynamics

Spouted bed technology is highly dependent upon empirical correlations for design and modeling purposes. In order to carry out a state-of-the-art review on the hydrodynamic parameters needed for design and performance evaluation of spouted beds, a detailed analysis is made regarding the reliability of various hydrodynamic correlations of spouted beds reported in the literature. Spout diameter, maximum spoutable height, and minimum spouting velocity as critical hydrodynamic parameters are evaluated. Many correlations show poor predictions for calculating these parameters in certain operating conditions. Cecen's equation[ 1 ] successfully predicts the maximum spoutable bed height for fine particles. For large particle diameters, the equation of Morgan and Littman[ 2 ] is valid. The equations of McNab[ 3 ] and Malek et al.[ 4 ] for determining spout diameter and the equations of Grbavcic et al.[ 5 ] and Mathur and Gishler[ 6 ] for calculating the minimum spouting velocity are recommended. Although some researchers have tried to modify the old equation of Mathur and Gishler[ 6 ] to improve its predictions of minimum spouting velocity, this equation is more successful than any other equation proposed yet for a wide range of operating conditions.

A note on a boundary condition for spouted beds

The boundary condition, zero solids pressure at the top of a particle bed of maximum spoutable height, H m, is shown to eliminate any resort to empiricism in the derivation of the fluid velocity in the annulus of a spouted bed for which both viscous and inertial effects are taken into account. The same boundary condition fails when applied to a spouted bed for which the bed height H < H m, especially when H < 0.8 H m.

Maximum spoutable bed height of spout-fluid bed

Experimental study on the maximum spoutable bed height of a spout-fluid bed (cross-section of 0.3 m × 0.03 m and height of 2 m) packed with Geldart group D particles has been carried out. The effects of particle size, spout nozzle size and fluidizing gas flow rate on the maximum spoutable bed height were studied. Experimental data were compared to some published experiments and predictions. The results show that the maximum spoutable bed height of spout-fluid bed decreases with increasing particle size and spout nozzle size, which appears the same trend to that of spouted beds. The increasing of fluidizing gas flow rate leads to a sharply decrease in the maximum spoutable bed height. The existent correlations of the maximum spoutable bed height in the literature were observed to involve large discrepancies. Additionally, the flow characteristics when bed materials deeper than the maximum spoutable height were summarized. Under this condition, the spout-fluid bed operated without a stable and coherent spout or fountain assembles the characteristics of jetting fluidized bed. Besides, the mechanisms of spout termination were investigated. It was found that slugging in the spout and growth of instabilities would cause the spout termination in spout-fluid bed.

Hydrodynamics and heat transfer in a plasma spouted bed reactor

The literature reveals very little intformation about plasma spouted bed hydrodynamics. Spouting of corindon particles with diameters ranging from 0.4 to 3.36 mm with argon plasma was conducted in a 90-mm-diameter column in the temperature range 300–1300°C. It was found that the maximum spoutable height (Hm) decreases with increasing particle diameter and decreasing mean bed temperature. A relation between the inlet plasma velocity and Hm is proposed. Concerning heat transport phenomena in the annulus, measurements and calculations indicate a large axial diffusivity but a poor radial mixing. Typical values of Dz and Dr are proposed on the basis of an identification procedure.

Jet penetration and pressure drops in water spouted beds of fine particles

AbstractNew expressions for the maximum spoutable height and spout pressure drop ratio are developed for fine particles spouted in water. The maximum spoutable height in both water and air systems is found to be dependent upon two dimensionless parameters, β and ALim. For fine particles spouted with water, the dimensionless pressure drop ratio depends only upon the voidage, ϵ at the bottom of the spout.

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ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTReply to comments on "Predicting the maximum spoutable height in spouted beds of irregularly shaped particles"Howard Littman and Morris H. Morgan IIICite this: Ind. Eng. Chem. Res. 1987, 26, 2, 398–399Publication Date (Print):February 1, 1987Publication History Published online1 May 2002Published inissue 1 February 1987https://doi.org/10.1021/ie00062a041RIGHTS & PERMISSIONSArticle Views26Altmetric-Citations-LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (241 KB) Get e-Alerts Get e-Alerts

Comments on "Predicting the maximum spoutable height in spouted beds of irregularly shaped particles"

Comments on "Predicting the maximum spoutable height in spouted beds of irregularly shaped particles"

A new spouting regime in beds of coarse particles deeper than the maximum spoutable height

AbstractA new spouting regime for coarse particles in beds deeper than the maximum spoutable height has been identified and its location on a phase diagram is presented for an air spouted bed of 5 mm glass spheres.The periodic formation and breakup of single bubbles originating at the top of the spout at lower gas velocities than required to observe the new regime has been studied using high speed photographs. An analogy is drawn between these observations and the breakup of bubbles in a turbulently fluidized bed.

Some aerodynamic and solids circulation measurements in a slotted spouted bed of grains

Pressure drop, minimum circulation velocity and solids circulation rates were measured in a spouted bed with a slotted gas inlet and a draft tube formed by vertical partitions, for barley, peas, corn and wheat. Both full (symmetric) and half (asymmetric) configurations were examined. The presence of appropriately positioned vertical baffles was found to yield stable spouting and eliminate the upper limit on the maximum spoutable height. The solids circulation rate, which is equal to the solids entrainment rate by the spouting air jet, was observed to correlate directly with the square root of the air inlet velocity for all the grains studied. Effects of bed height, height and location of the vertical baffle(s) and the inlet slot width on the bed pressure drop and solids circulation rate are documented and discussed.

Spouting characteristics of small glass particles with water

Experimental data are reported for the minimum spouting velocity, bed pressure drop, maximum spoutable height and spout diameter which show that spouting of small particles with water represents a new spouting regime. The transition from large to small particle spouting occurs when the voidage at the inlet to the spout goes from unity to less than unity.

Prediction of the maximum spoutable height in spout‐fluid beds

AbstractThe development of the semi‐theoretical correlation in Hadzisdmajlovic et al. (1983) for predicting the maximum spoutable height in a spout‐fluid bed, is observed to involve certain discrepancies. Based on their experimental data, a new correlation is proposed.

The mechanics of spout‐fluid beds at the minimum spout‐fluid flowrate

AbstractEquations for predicting the minimum fluid flowrate in spout‐fluid beds of coarse spherical particles are developed and experimentally verified. Correlations for the spout diameter and maximum spoutable height are also given. The annular pressure drop equations developed in previous work are experimentally verified.

Predicting the maximum spoutable height in spouted beds of irregularly shaped particles

Predicting the maximum spoutable height in spouted beds of irregularly shaped particles

Prediction of the maximum spoutable height and the average spout to inlet tube diameter ratio in spouted beds of spherical particles

Prediction of the maximum spoutable height and the average spout to inlet tube diameter ratio in spouted beds of spherical particles

A theory for predicting the maximum spoutable height in a spouted bed

The Canadian Journal of Chemical EngineeringVolume 56, Issue 1 p. 133-133 ErrataFree Access A theory for predicting the maximum spoutable height in a spouted bed Howard Littman, Howard Littman Dept. of Chemical & Environmental Engineering, Rensselaer Polytechnic Institute, Troy, New York, 12181Search for more papers by this author Howard Littman, Howard Littman Dept. of Chemical & Environmental Engineering, Rensselaer Polytechnic Institute, Troy, New York, 12181Search for more papers by this author First published: February 1978 https://doi.org/10.1002/cjce.5450560124AboutPDF 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 No abstract is available for this article. Volume56, Issue1February 1978Pages 133-133 RelatedInformation

A theory for predicting the maximum spoutable height in a spouted bed

AbstractA theory is presented for predicting the maximum spoutable height, in a spouted bed where fluidization of the annular solids limits the penetration of the fluid jet entering the bed.The quantity (Hmds/(D – d) is found to be a function of ds/Dc only for spherical particles and \[ \frac{{H_m d_S }} {{(D_c^2 ‐ d_S^2 )}} = 0.345\left( {\frac{{d_S }} {{D_c }}} \right)^{ ‐ 0.384} \] where the spout diameter is calculated using McNab's correlation(7). Insertion of McNab's correlation into Equation (1) shows that Hm is proportional to D and the effect of dp on Hm varies from d to d as the particle Reynolds number increases assuming 1 ≥ (ds/D).Using experimental value of ds, the calculated values of Hm differ from the experimental ones by 8.5% on average.When small particles are spouted with air, the penetration of the jet is limited by the formation of a slug in he spout and the theoretical value provides an upper limit for Hm.

Fluid flow pattern, minimum spouting velocity and pressure drop in spouted beds

AbstractThis study extends the theory of Mamuro and Hattori to beds of less than the maximum spoutable height. The new model gives predictions for the fluid flow pattern, minimum spouting velocity and spouting pressure drop which are in agreement both with experimental data on beds spouted with air and water (obtained in this study) and with literature data.A correlation for Hm in water spouted beds of spherical glass particles is also presented.