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The use of spouted beds for batch drying has already been approached in the literature, in which the design of internal devices and aspects related to energy efficiency have been investigated, but there is hardly any information on continuous drying. This paper analyses the performance of a fountain confined conical spouted bed in continuous drying of fine and ultrafine sands, whose configuration has been optimized in previous studies. Capacity curves have been established and the influence of operating parameters has been analyzed. Drying capacity is higher with fine sand, which is explained by the difference in physical properties of the sands. Furthermore, the best use of the energy available is attained with high sand flow rates, which allows reaching energy efficiencies above 95% and 91% for fine and ultrafine sand. This analysis allows predicting the performance of spouted beds in the continuous drying of powder materials in large scale conditions.

Explicit dimensionless models are proposed for estimating the minimum spouting velocity, operating pressure drop and peak pressure drop in open-sided draft tubes spouted bed using the genetic programming (GP). The models are developed based on 664 experimental data for minimum spouting velocity, 660 for peak pressure drop and 652 for operating pressure drop. The parameters of significant influence are considered as GP input variables, and reliable semi-empirical correlations have been obtained. The models predict the hydrodynamic parameters analyzed with average absolute relative errors of 12.90%, 15.99% and 10.92% for the minimum spouting velocity, peak pressure drop and operating pressure drop, respectively. A comparison of literature correlations with the present ones shows that the latter lead to considerably lower errors from the experimental data. The prediction capability of the new models was evaluated in a range of operating and geometric conditions and a close agreement with the experimental data was observed.

Spouted bed stability and operation is greatly affected by particle features. Accordingly, the hydrodynamic behaviour of conical spouted beds has been studied for fine particles differing in size and density in a wide range of inlet air flow rates. This knowledge is essential for a successful scaling up and industrial implementation of the spouted bed. Therefore, the effect air velocity and solid properties (density and size) have on local solid velocity has been ascertained in a fountain confined conical spouted bed using a borescope technique (Particle Tracking Velocimetry, P T V ) applied to several bed configurations. The results show a close relationship between the inlet air velocity and the local solid velocity, with the gas-solid contact being especially vigorous in the configurations without draft tube and with the open-sided draft tube. The solid circulation flow rate is lowest when a nonporous draft tube is used due to the low solid vertical velocities in the annulus, even at high air flow rates. Nevertheless, vertical velocities in the annular zone increase when particle size and density are increased, although these velocities are lower in the spout and fountain regions due to the higher momentum exchange required for their acceleration.

A novel borescopic technique together with the monitoring of pressure fluctuation signals (power spectral distribution, PSD) has been used to track fine particles and characterize solid flow dynamics in fountain confined conical spouted beds. Radial and axial particle velocity profiles have been obtained for different configurations, and spout-annulus and fountain core-periphery interfaces have been delineated. The downward particle velocities in the annulus peak at intermediate positions in this zone, whereas the upward velocities in the dilute zones (spout and fountain core) peak at the axis or close to this position. Among the different configurations analysed in this work, the system without draft tube shows the greatest vertical particle velocities in almost all the different radial and axial positions. The evolution of the spout size along the bed depends on the configuration used, but all of them differ from those commonly reported in the literature. Thus, the spout expands from the bed bottom to the surface, without any neck at an intermediate bed level. Furthermore, the cross-sectional spout shape has been delineated in the systems with open-sided draft tube, and significant spout expansion is observed due to air percolation from the spout into the annulus through the opened faces. Finally, the average spout diameters of the systems without draft tube and with open-sided draft tubes have been compared with those predicted by literature correlations. Those proposed by San Jose et al. and Volpicelli et al. provide the best fit for the configurations without draft tube and with open-sided draft tube, with their relative errors being 9.83% and 8.88%, respectively.

A novel internal device called fountain confiner has been developed, which stabilizes the system and allows operating with fine particles, even without any type of draft tube. Given the stability this device confers upon the system, lower minimum spouting velocities than in conventional systems are required, and therefore the correlations in the literature overestimate this hydrodynamic parameter. Accordingly, runs have been carried out using this novel device in order to study the hydrodynamics and the influence geometric and operating factors have on the minimum spouting velocity in fountain confined conical spouted beds, with and without draft tubes. The beds are made up of fine sand and sawdust particles. Based on an experimental design, it was ascertained that, although certain factors are influential in given configurations, those of greater influence in all the configurations are the solid properties, static bed height and gas inlet diameter. Therefore, new correlations have been proposed for predicting the minimum spouting velocity in each configuration.

Bed symmetry has been analysed in fountain confined conical spouted beds operating with fine particles. Thus, vertical particle velocities and the spout shape have been determined in a wide range of spouting air velocities and bed configurations. Bed symmetry is widely accepted in the spouted beds without draft tubes or with nonporous ones, but this is not the case when open-sided draft tubes are used. Thus, radial particle velocity profiles differ depending on the cross-sectional angular plane considered in the open-sided draft tubes. The spout expands preferentially along the tube opened surface, and is wider as spouting air velocity and aperture ratio are increased. The literature correlations proposed for the average spout diameter have been analysed and no one is valid for estimating this parameter in the whole range of spouting air velocities and configurations analysed in these systems operating with fine particles. This work has received funding from Spain's Ministry of Science and Innovation (PID2019-107357RB-I00 (AEI/FEDER, UE)), the Basque Gov- ernment (IT1218–19 and KK-2020/00107) and the European Commis- sion (HORIZON H2020-MSCA RISE-2018. Contract No.: 823745). M. Tellabide thanks Spain's Ministry of Education, Culture and Sport for his Ph.D. grant (FPU14/05814). I. Estiati thanks the University of the Basque Country for her postgraduate grant (ESPDOC18/14).

The drying of fine sand particles (below 1 mm) has been studied in a conical spouted bed fitted with a draft tube in order to ascertain the performance of a new internal device to confine the fountain. Accordingly, batch runs have been carried out using three types of draft tubes, with confiner and without it under ambient conditions. Their performances have been compared in order to ascertain the optimum configuration. The results evidence that the systems with the confiner perform much better than those without it. Thus, the drying time decreases considerably and the pressure drop and air flow rate decrease slightly when the confiner is used. The drying performance of the open-sided draft tube is superior to any other configuration, i.e., the drying time required with this tube is the shortest. Nonporous draft tubes are the worst option due to their poor gas-solid contact. Porous draft tubes have an intermediate performance.

A study has been carried out on the influence process conditions and design parameters have on the drying in a conical spouted bed. Optimum parameters have been determined for the draft tub...

Conventional spouted beds have been extensively used in many real-life applications but are not suited for all types of materials, especially fine particles, which require internal devices to improve their motion in the spouted bed. However, unlike conventional spouted beds, there are almost no mechanistic or empirical models available for the design of spouted beds with internals. Given the availability of an extensive but not experimentally designed database, the main purpose of this study is to present an analysis of neural networks and empirical models in terms of their suitability to fit and predict average cycle times in conical spouted beds with and without draft tubes. The parameters investigated are particle size, density, contactor angle, gas inlet diameter, static bed height, and draft tube features. Although the amount of information is always a key factor when fitting models, the size of the database used in this study strongly affects the fitting performance of empirical models, whereas artificial neural networks are more influenced by how the data are scaled. Results of model verification show that both techniques are suitable for predicting average cycle times for data outside the range covered by the database.

Many applications of the conical spouted beds involve operations using coarse and fine particle mixtures, which require high gas velocities due to the coarse particles, thereby leading to fine particle entrainment. In order to avoid entrainment, a new device has been proposed to confine the fountain. Thus, a study has been conducted on the influence the geometry and configuration of both confiner and draft tube have on particle entrainment, operating pressure drop, operating air flow rate and maximum cycle time. The results show that the fountain confiner greatly stabilises the operation and significantly reduces (above 50%) particle entrainment, but its influence on the other parameters is of rather low significance. Furthermore, the distance between the lower end of the device and the bed surface has a great impact on the performance of the spouted bed regime. Entrainment monitoring throughout time showed that its rate depends on the configuration, but remains constant with time.

A contactor vessel was built to operate as either a mechanically or a conventional spouted bed for the purpose of analyzing the drying of pasty and granular materials under comparable conditions in both configurations. A classical conical–cylindrical spouted bed with a 60° conical base and an air inlet central orifice was modified to enable the switch by introducing in the vessel’s center an open helicoidal conveyor screw placed above the air inlet orifice. This screw is removable and conveniently returns the bed to its conventional spouted configuration. Experiments on drying solutions (calcium carbonate suspensions and skimmed milk) and granular materials (porous alumina particles) were performed for various bed parameter settings. The spouting pressure drop, outlet air temperature, and relative humidity were measured over time under different conditions. Mechanical agitation is proved effective in drying diluted carbonate calcium liquid suspensions and coarse porous alumina particles at an air velocity approximately 50% lower in comparison to drying in a conventional spouted bed. The conventional spouted bed performed better at drying liquid skimmed milk as the mechanical agitation combined with the axial inlet air flow is not effective in mitigating sticking and powder agglomeration in the bed when handling pastes of complex composition. Introducing mechanical agitation in the designed setup broadens the operating range of a conventional spouted bed with axial air flow in the inlet.

The minimum spouting velocity, Ums, is a critical topic, and an exact prediction of this parameter certainly can be useful in design and scale-up of the conical spouted beds. In the present study, a number of intelligence methods was applied to predict Ums in conical spouted beds equipped with non-porous draft tube. Six dimensionless moduli comprising the essential operating and geometric parameters, namely, the gas density, the gas viscosity, the particle diameter, the particle density, the cone angle, the nozzle diameter, the static bed height, the length of the tube, the entrainment height, and the tube diameter were taken as models inputs. The total number of data samples is 1004 that includes 572 data points to train the smart models and 432 data points to test those models. The self-organizing map (SOM) was used to examine the effect of inputs correlation on the performance of the chosen smart models. Among the different models, a multi-layer perceptron (MLP) trained by Bayesian Regulation (BR) incorporating SOM i.e. (MLP-BR-SOM) predicted the best results with mean relative error of 9.71 and 12.45% for train and test data, respectively. In addition, sensitivity analysis (SA) of the proposed model was performed and it was shown the Ar, DT/D0, and H0/D0 have most influential parameters in prediction of Ums.

A full 3D model of a conical spouted bed equipped with an open-sided draft tube was simulated using CFD-DEM embedded in a commercial CFD code ANSYS-FLUENT. The dense discrete phase model (DDPM) with DEM closure for particle–particle interaction available in the FLUENT was used for the particulate phase. The dispersed k-e turbulent model was used in the computational model for the gas phase. The geometry used in the simulation for both the contactor and the open-sided draft tube was identical to that of a pilot plant in which the hydrodynamic studies were carried out. The influence of the open-sided draft tube was studied by using two configurations, one flushed with the bed surface and the other one protruding above the bed surface. The CFD-DEM results indicated that the accuracy of model predictions significantly depends on the modification in the Gidaspow drag function. The predicted pressure drops and fountain heights were consistent with the experimental data. New aspects of particle flow pattern, axial solid velocity, solid volume fraction in the bed, and power spectral density have also been discussed.

A study has been carried out on the applicability of the correlations proposed in the literature for calculating peak and spouting pressure drops to biomass materials. These parameters are essential for estimating energy consumption in spouted beds and depend on the contactor geometry, operating conditions and the type of particles. Five biomass materials have been studied based on their suitability for energy production by combustion and their different size, density and shape factor. Both peak and spouting pressure drops increase as particle size and density are increased and shape factor is decreased. Correlations have been proposed based on those already reported in the literature for regular materials. The influence of particle size and density is more pronounced in these irregular biomass materials than in regular ones, especially in the peak pressure drop. Shape factor is also highly influential, which is reflected on the greater influence of the static bed height for irregular materials, especially for the spouting pressure drop.

A device and methodology have been developed for measuring the circulation rate of fine particles in conical spouted beds. A comparison with particle tracking shows the method is appropriate. The influence of the spouted bed variables have been investigated on the average cycle time, maximum cycle time and circulation rate.

A multilayer perceptron with back-propagation learning algorithm is developed to predict the minimum spouting velocity (ums) in draft tube conical spouted beds. Six dimensionless variables involving ten essential geometric and operating parameters of the beds were taken as model inputs. To compare the model results with both experimental data and those predicted by the limited existing empirical equations, the root mean square error and the mean relative error are utilized. Although there is a complex relationship between the input variables and ums, and despite the huge number of data available, the steps of training and testing show good agreement with the corresponding experimental values. This demonstrates that an artificial neural network is a useful approach to predict ums, especially when the relationship between the geometric and operating parameters and ums is complex and difficult to define.

Particle entrainment is a serious problem in spouted bed contactors when operation is carried out using beds made up of ultrafine particles, irregular ones and fine and coarse particle mixtures. Accordingly, the conventional conical spouted bed has been modified by inserting a fountain confiner in the contactor, and a study has been carried out on the efficiency of the confinement device to avoid fine particle entrainment. Furthermore, the influence of the geometry of the device on the hydrodynamics of conical spouted beds has been studied. The results show that the fountain confiner largely avoids fine particle entrainment, i.e., 60–70% reduction depending on the type of draft tube used. Furthermore, the fountain confiner reduces the operating bed pressure drop and the maximum cycle time of the particles in the contactor, but has no effect on the minimum spouting velocity. Nevertheless, the greatest advantage of the fountain confiner lies in the stabilization of the fountain and the homogenisation of the solid circulation in the bed, which leads to a significant increase in the gas-solid contact in the fountain.

The design factors of fountain confined conical spouted beds have been assessed in order to determine their best combination for scaling up and enhancing fine particle retention. The results evidence that the length of the confiner and the height of the draft tube entrainment zone are the key design factors, causing the highest entrainment reduction. Thus, the optimum confiner length is within the range of 2-3 times the bed surface diameter and the desirable height of the entrainment zone is approximately 1-2 times the tube diameter. This study also concludes that the best system for attaining high stability with minimum elutriation is the one equipped with an open-sided draft tube with an aperture ratio of around 20%.

Spouted beds are an interesting alternative for the treatment of biomass for energy purposes, given that the insertion of a draft-tube allows large-scale handling of solids with a wide range of sizes and diverse properties. The hydrodynamic correlations proposed in the literature have not been validated with particles of low density and shape factor. Therefore, a detailed experimental study has been conducted using five types of biomasses and different combinations of the contactor geometric factors. The correlations in the literature for plain conical spouted beds and for those provided with nonporous and open-sided draft-tubes have been taken as a starting point and, based on the experimental results, they have been modified in order to account for the properties of the solids. Two strategies have been considered in the methodology for modifying the coefficients in the literature correlations. Both are based on the introduction of coefficients one by one based on a hypothesis test. Accordingly, new correlations based on existing ones have been proposed, with the number of coefficients modified being minimum.

A study has been carried out on the influence the draft-tube configuration has on the solid circulation in conical spouted beds made up of sawdust. Knowledge on the performance of these fine particles of low density and irregular texture is required for the pyrolysis, gasification or combustion of this waste materials in conical spouted beds. Accordingly, particle cycle times have been monitored for contactors of different geometry (angle and gas inlet diameter) provided with draft-tubes of different configuration (nonporous and open-sided tubes). The study has been carried out according to a factorial design of experiments. Particle cycle times follow an almost exponential distribution for both types of tubes and are highly dependent on the type of draft tube and contactor angle, especially in the range from 36° to 45°. On average, cycles times are twice to triple longer when nonporous tubes are used. Therefore, the open-sided internal device provides stability and ensures high turbulence to beds made up of fine and irregular particles, with their behaviour being similar to stable beds made up of coarse particles in which no draft-tube is required.

The spouted bed regime is an alternative to fixed and fluidized beds due to the excellent gas-solid contact and the high reduction in operating pressure drop. Nevertheless, the most important limitation of this technology lies in its scaling up, since the inlet diameter/particle diameter ratio must be below 20–30 to avoid bed instability. In order to overcome this limitation, a new internal device called fountain confiner has been developed, which stabilises the system and allows operating with fine particles even without any type of draft tube. Runs have been carried out using the fountain confiner in order to analyse the stability of beds composed of very fine particles and the characteristic hydrodynamic curves (pressure drop vs. air velocity) have been obtained. The use of this new device allows attaining highly stable operation regimes, widening the operational range to 4 times that of plain spouted beds, and increasing the inlet diameter/particle diameter ratio from 20–30 to 1000. Moreover, the optimum distance between the bed surface and the lower end of the confiner has been delimited for the range of operating conditions studied, 0.06 - 0.08 m (between 1 / 2 and 1 / 3 the confiner diameter), since it is a key parameter for system stability. Finally, the effect of several geometric factors and the scaling up of this technology has been analysed for fine particles of different size and density.

This paper describes preliminary studies carried out to develop a system made up of two interconnected spouted beds for heat integration in highly endothermic processes, such as pyrolysis and gasification. Four different configurations of a dual spouted bed system have been studied depending on the location of the feeding and discharging points in the interconnection pipes, i.e., annulus–annulus, annulus–spout, fountain–spout and fountain–annulus. Fountain–annulus configuration has been determined to be the optimum option based on its stability, solid transfer rate (around 120 kg h − 1 ) and gas bypassing from one contactor to the other (below 1.5%). Once the optimum system has been established, the viability of the dual spouted bed system has been assessed for heat integration in the biomass pyrolysis, with the minimum temperature difference between the pyrolyser and combustor being 280 °C for attaining allothermal operation. Furthermore, studies have been carried out on the solid circulation rate (energy balance), gas bypassing from one contactor to the other and system stability against different perturbations, which have allowed determining the optimum configuration

Operating and peak pressure drops have been studied in conical spouted beds equipped with draft tubes of different configuration using materials of different size. The draft tubes used are nonporous and open-sided ones. Based on an experimental design, the factors of greater influence on both pressure drops have been determined and general correlations valid for fine and coarse materials have been proposed for predicting the operating pressure drop and peak pressure drop with each type of draft tube. The results show that conical spouted beds equipped with draft tubes give way to lower operating and peak pressure drops than those without draft tube. A comparison of draft tube systems reveals that nonporous tubes give way to the lowest values of both pressure drops, but the solid circulation rates and the gas–solid contact efficiency are poorer than those with open-sided draft tube systems.

Particle cycle times (average, maximum, and minimum) have been measured in draft tube conical spouted beds for different geometric factors of the contactor (angle and gas inlet diameter), draft tubes (diameter, height of the entrainment zone, and width of the faces) and under different operating conditions (particle density). On the basis of the results, the effects of the type of draft tube and different factors of the contactor/draft tube/particle system have been studied, and those of greater influence have been determined. The results show that particle cycle times and solid circulation rates are highly dependent on the type of draft tube, solid density, and contactor angle. Open-sided draft tubes are the ones with the highest solid circulation rate with stable spouting performance. Therefore, this internal device is a suitable option for scaling up spouted beds with a hydrodynamic performance similar to those without tubes.

The hydrodynamics and the influence of the geometric and operating factors on the minimum spouting velocity have been studied in draft tube conical spouted beds with materials of different size and density. Two draft tube configurations have been used: nonporous and open-sided tubes. Based on an experimental design, the factors of greater influence have been extracted and the general correlations valid for fine and coarse materials have been proposed for predicting the minimum spouting velocity for each type of draft tube. A comparison of the velocities with and without a tube reveals that the nonporous draft tube requires the lowest minimum spouting velocity. Nevertheless, the solid circulation rate and the gas–solid contact efficiency of the open-sided draft tube outperform any other spouted bed configuration, especially for fine particles. Consequently, open-sided draft tubes allow stable operation with fine particles and high solid circulation rates in conical spouted beds.

The drying of sawdust was studied in a conical spouted bed pilot plant in order to adapt this feed for the pyrolysis process. Air at different temperatures was used and the effect of sawdust particle size and operating gas velocity was studied. Batch operation was performed with no internal device and with nonporous and open-sided draft tubes in order to ascertain the optimum configuration of the contactor. Although the nonporous draft tube required the lowest minimum spouting velocity, its performance was poor due to deficient gas–solid contact. Configurations with open-sided draft tubes and with no internal devices had higher efficiencies because of their better contacts. An increase in air temperature resulted in a reduction in drying time but the operating conditions need to be fine-tuned to ensure proper energy efficiency.

A model has been built to predict the evolution of sand drying in a conical spouted bed with a non-porous draft tube. Three regions have been considered in the model, i.e., spout, annulus and fountain, and unsteady-state mass balances have been written for water in the solid and gaseous phases. The model has been validated by comparing its results with the experimental ones obtained in a previous study and it allows predicting the moisture content evolution of both the air and the sand during the drying process.

The performance of a draft-tube conical spouted bed for drying fine particles under batch operating conditions has been assessed at several temperatures using nonporous and open-sided draft tubes, and the results have been compared with those obtained when operating without a draft tube. In order to ascertain the influence of temperature on drying, experimental runs have been carried out in the 25―300 °C temperature range. The open-sided draft tube provides the best performance due to the excellent gas-solid contact attained with this device, which enables shorter drying times. A maximum air temperature of 200 °C is recommended for energy optimization. An open-sided tube protruding above the stagnant bed by at least 2/3 of the latter's height produces much lower and denser fountains than a tube flush with the upper surface of the bed.

A study has been carried out on spouting performance in conical spouted beds at high temperatures and under vacuum by using materials of different textures, densities and particle diameters. The applicability of existing correlations for determining the minimum spouting velocity has been checked and, based on a statistical analysis to assess the influence of the dimensionless modulus, a new one has been proposed for the prediction of the minimum spouting velocity under vacuum and at high temperatures. This correlation provides good predictions in the pyrolysis of tyres under vacuum. Une etude a ete effectuee sur le rendement en matiere de jaillissement dans les lits jaillissants coniques a des temperatures elevees et sous vide en utilisant des matieres ayant differentes textures et densites et differents diametres de particules. L'applicabilite des correlations existantes en vue de determiner la vitesse de jaillissement minimale a ete verifiee et, en s'appuyant sur une analyse statistique visant a evaluer l'influence du module adimensionnel, une nouvelle correlation a ete proposee en ce qui a trait a la prediction de la vitesse de jaillissement minimale sous vide et a des temperatures elevees. Cette correlation offre de bonnes predictions en ce qui concerne la pyrolyse des pneus sous vide.

A one-dimensional model has been developed that considers the solid cross-flow from the annulus into the spouted bed. The model is based on mass and momentum balance equations for the gas and solid in both the annulus and spout. The great advantage of the model is the need for only two empirical equations: one for obtaining minimum spouting velocity and the other one for obtaining the pressure gradient throughout the bed. The simulated values for solid and gas velocities are consistent with the experimental ones, except particle velocity along the spout, whose accurate prediction requires the consideration of spout diameter change with bed level. Based on the data obtained at the top of the spout, the model allows for calculating properties in the fountain, namely, fountain height and voidage at the core of the fountain.

The hydrodynamics and performance of conical spouted beds provided with different types of draft-tubes have been studied for the treatment of fine particles. Correlations for calculation of the minimum spouting velocity, operating pressure drop, and peak pressure drop have been developed as a function of dimensionless moduli that take into account the geometric factors, particle characteristics, and operating conditions. A statistical analysis of the data obtained following a design of experiments shows that the height of the entrainment zone is highly significant in the nonporous draft-tubes, whereas the stagnant bed height is the counterpart in the open-sided draft-tubes.

A study has been conducted on the performance of a draft tube conical spouted bed for drying fine particles. Batch operation has been performed with nonporous, porous, and open-sided draft tubes in order to ascertain the optimum configuration of this internal device. The nonporous draft tube requires the lowest minimum spouting velocity. Nevertheless, the solid circulation rate and the drying efficiency of the open-sided draft tube are superior to any other spouted bed configuration. Moreover, it allows for reducing the height of the fountain and, consequently, the height of the drying equipment.

A hydrodynamic study of conical spouted beds equipped with draft tubes of different configurations have been carried out for fine and coarse particles belonging to Geldart groups D and B, respectively. The draft tubes used are conventional non-porous tubes and open-sided tubes, and runs have been carried out following a design of experiments in order to ascertain the effect of the draft tube geometry on the operating pressure drop and peak pressure drop. Furthermore, runs have been carried out without tubes to compare the results obtained with those obtained with the two types of tubes. The results evidence that the geometry of the draft tube influences the operating pressure drop and especially the peak pressure drop and, therefore, the hydrodynamics of conical spouted beds.

A hydrodynamic study of conical spouted beds equipped with draft tube has been carried out for glass beads. Runs have been carried out in conical spouted beds of different geometry according to a factorial design of experiments. The purpose of this design has been to study the effect on particle cycle times and solid circulation rate of the following: the insertion of a draft tube, draft tube configuration, and the different factors of the contactor and particle system. Particle cycle times (average, maximum, and minimum) have been measured in draft tube conical spouted beds for different geometric factors of the contactor (angle and gas inlet diameter), draft tubes (diameter, height of the entrainment zone, and width of the faces) and under different operating conditions. It can be concluded that the hydrodynamics of conical spouted beds with draft tube is influenced by the geometric factors of the draft tube, contactor and operating conditions.