Flow behavior of gas and particles in conical spouted beds is experimentally studied and simulated using the twofluid gas-solid model with the kinetic theory of granular flow.The bed pressure drop and fountain height ...Flow behavior of gas and particles in conical spouted beds is experimentally studied and simulated using the twofluid gas-solid model with the kinetic theory of granular flow.The bed pressure drop and fountain height are measured in a conical spouted bed of 100 mm I.D.at different gas velocities.The simulation results are compared with measurements of bed pressure drop and fountain height.The comparison shows that the drag coefficient model used in cylindrical beds under-predicted bed pressure drop and fountain height in conical spouted beds due to the partial weight of particles supported by the inclined side walls.It is found that the numerical results using the drag coefficient model proposed based on the conical spouted bed in this study are in good agreement with experimental data.The present study provides a useful basis for further works on the CFD simulation of conical spouted bed.展开更多
On the basis of hydrodynamic and scaling-up studies, a pilot-plant-scale thermal spouted bed reactor (50 mm in ID and 1500 mm in height) was designed and fabricated by scaling-down cold simulators. It was tested for m...On the basis of hydrodynamic and scaling-up studies, a pilot-plant-scale thermal spouted bed reactor (50 mm in ID and 1500 mm in height) was designed and fabricated by scaling-down cold simulators. It was tested for making syngas via catalytic partial oxidation (CPO) of methane by air. The effects of various operating conditions such as operating pressure and temperature, feed composition, and gas flowrate etc. on the CPO process were investigated. CH4 conversion of 92.2% and selectivity of 92.3% and 83.3% to CO and H2, respectively, were achieved at the pressure of 2.1 MPa. It was found that when the spouted bed reactor was operated within the stable spouting flow regime, the temperature profiles along the bed axis were much more uniform than those operated within the fixed-bed regime. The CH4 conversion and syngas selectivity were found to be close to thermodynamic equilibrium limits. The results of the present investigation showed that spouted bed could be considered as a potential type of chemical reactor for the CPO process of methane.展开更多
A novel reaction-drying process was carried out in a spouted bed reactor with inert particles and used to prepare ultrafine CaCO3 particles. Effects of concentrations of CO2 and Ca(OH)2, and reaction temperature on Ca...A novel reaction-drying process was carried out in a spouted bed reactor with inert particles and used to prepare ultrafine CaCO3 particles. Effects of concentrations of CO2 and Ca(OH)2, and reaction temperature on Ca(OH)2 conversion were experimentally investigated. The particle sizes and composition of CaCO3 produced were characterized with transmission electron microscopy (TEM) and X-ray diffraction (XRD). The results indicated that ultrafine CaCO3 particles with mean size of 80 nm could be obtained with this novel process.By modifying the Arrhenius Equation and considering the Ca(OH)2 state, a kinetic model was established to describe the process in the spouted bed. The model parameters estimated from the reaction-drying experiments were found to fit well the experimental data, indicating the applicability of the proposed kinetic model.展开更多
The development of intensification technology for spouted beds has become a current research focus,and an effective way to improve the efficiency of spouted beds is to reform their structure.Although numerous studies ...The development of intensification technology for spouted beds has become a current research focus,and an effective way to improve the efficiency of spouted beds is to reform their structure.Although numerous studies have been conducted on conventional beds,there are few reviews on the comprehensive application of intensification technology for spouted beds.In this paper,we comprehensively review the role of intensification technology in spouted beds for use in hydrodynamics,drying,desulfurization,pyrolysis,coating,biomass and waste gasification,and biomass drying from the perspective of experiment and simulation.Finally,potential problems and challenges in current spouted-bed research are summarized.展开更多
In a spouted bed of 80mm in ID and 1700mm in height, the gas residence time distributions at different radial positions in both spout and annular area were measured with five different kinds of particles as spouting m...In a spouted bed of 80mm in ID and 1700mm in height, the gas residence time distributions at different radial positions in both spout and annular area were measured with five different kinds of particles as spouting material, air as spouting gas, and hydrogen as tracer. The effects of superficial gas velocity, operating pressure, particle size and its category on gas residence time distribution were discussed. It was found that the gas velocity profile in spout was more uniform than that in annulus. It could be concluded that the gas flow in the spout could be treated as a plug-flow, while that in the annulus inhibited a strong non-ideal flow behavior. Increasing the superficial gas velocity and decreasing the operating pressure, the particle density and its size gave rise to spouting disturbance, thus the measured tracer concentrations vs. time curves fluctuated. The variances of residence time distribution curves could be taken as a measure of the gas fluctuation degree.展开更多
Novel draft tubes have been assessed to scale up the spouted bed technology. Accordingly, alumina drying runs have been conducted using different configurations (without tube and with open-sided and nonporous tubes) u...Novel draft tubes have been assessed to scale up the spouted bed technology. Accordingly, alumina drying runs have been conducted using different configurations (without tube and with open-sided and nonporous tubes) under intermittent strategies consisting in alternating periods of drying and periods of reduction or interruption of the air flow rate, and they have been compared with continuous drying. Furthermore, the influence the draft tubes have on the drying performance and energy requirements in the drying process has been evaluated. The results allow inferring that intermittent drying considerably decreases both drying time and energy requirements. Moreover, the new draft tubes improved the drying of alumina, as a similar energy efficiency than without draft tube was attained with lower specific energy consumption, which is essential to reduce the high-energy demand in the drying process and mitigate climate change. These findings, along with the stability the new tubes provided to the process, involve a further step in the scale up of spouted beds for industrial operations.展开更多
One of the emerging applications of spouted beds is their use as thermal receivers in CSP systems,offering significant advantages such as high heat transfer rates and uniform temperature distribution.However,experimen...One of the emerging applications of spouted beds is their use as thermal receivers in CSP systems,offering significant advantages such as high heat transfer rates and uniform temperature distribution.However,experimental studies on directly irradiated spouted beds remain limited in the literature.The aim of this study was to investigate the thermal performance of a directly irradiated spouted bed receiver using CarboHSP and olivine particles.Experiments were conducted in a 0.15 m ID spouted bed with a 60°conical angle.Hydrodynamic experiments were first performed to understand the gas-solid dynamics and establish a foundation for subsequent thermal studies.The solar radiation was simulated by a 2 kWe metal halide lamp.Temperature profiles influenced by particle size,spouting velocity,and particle type were analyzed,and charge and discharge efficiencies were determined.Higher temperatures are obtained as the particle size and spouting gas velocity are reduced.The results also show that olivine particles are a cost-effective alternative for spouted bed thermal receivers,offering thermal performance comparable to CarboHSP particles.展开更多
A numerical investigation of the three-dimensional conical spouted bed was conducted using CFD coupled with discrete element method to systematically analyze particle-gas flow patterns,bubble volume fluctuations,and f...A numerical investigation of the three-dimensional conical spouted bed was conducted using CFD coupled with discrete element method to systematically analyze particle-gas flow patterns,bubble volume fluctuations,and fountain characteristics.Moreover,the impact of conical angles on dynamic characteristics is demonstrated under varying gas inlet velocity and particle diameter.Firstly,the simulation result shows that increasing the conical angle is advantageous for enhancing both y-direction and angular velocities of particles,while the impact of this angle varies with inlet velocity and particle diameter.The great inlet velocity and particle diameter significantly enhance the voidage,while the larger conical angle promotes the uniform radial particle distribution.Besides,smaller conical angle and medium inlet velocity is prone to result in the higher frequency and amplitude for the fluctuations of particle height.Meanwhile,enlarging the conical angle results in a shift of the fountain frequency from high to low when the particle size is small.The conical angle plays a crucial role in determining bubble behavior under the condition of medium velocity and small diameter.Besides,the fine particle and small conical angle are prone to cause the noticeable main frequencies.展开更多
This paper presents an alternative approach for plastic waste valorization in a fountain confined conical spouted bed reactor.The study evaluates the application of an upgraded spouted bed design for the steam crackin...This paper presents an alternative approach for plastic waste valorization in a fountain confined conical spouted bed reactor.The study evaluates the application of an upgraded spouted bed design for the steam cracking of polypropylene(PP)at 750℃,focusing on high value added products.The highly efficient cracking process results in a high gas yield of 80.9 wt%.This stream is composed of H_(2),CO,CO_(2),C_(1)-C_(4)paraffins and C_(2)-C_(4)olefins,with the latter reaching a total yield of 49.2 wt%.Among the light olefins,propylene(21.8 wt%)and ethylene(16.5 wt%)are the most relevant.Interestingly,a remarkable yield of the valuable BTX fraction was obtained,14.0 wt%,with benzene being the predominant compound.The reactor configuration and excellent control of process conditions enhanced light olefins yield byβ-scission and radical mechanism,promoting the formation of light hydrocarbons,as well as minimizing secondary oligomerization and reforming reactions.This study is a proof of the viability of steam cracking in a fountain confined spouted bed reactor for converting PP into valuable chemical intermediates,as well as the viability of this technology for industrial application in waste plastic valorization.展开更多
Spouted bed is a type of fluidized bed that has been widely used in various industrial processes because of its excellent mass and heat transfer efficiency.In practical applications,the fluidization of the multicompon...Spouted bed is a type of fluidized bed that has been widely used in various industrial processes because of its excellent mass and heat transfer efficiency.In practical applications,the fluidization of the multicomponent particle system containing non-spherical particles is frequently encountered in spouted beds.To better understand the spouting behaviors of the multicomponent particle system,therefore,this study employs a CFD-DEM(Computational Fluid Dynamics-Discrete Element Method)coupling approach to investigate the spouting behaviors.Spherical particles along with two types of ellipsoidal particles(i.e.,oblate ellipsoid,and prolate ellipsoid)are included in this paper.Through the combination of these three particle types,seven distinct systems(three monodisperse systems,three binary mixtures,and one ternary mixture)are simulated to analyze the effects of particle shape and composition of particle systems on spouting behaviors.The simulation results reveal that introducing non-spherical particles into systems containing either spherical or oblate ellipsoidal particles tends to enhance spouting behaviors,whereas adding spherical particles to prolate ellipsoidal particle systems inclines to suppress it.The addition of non-spherical particles into the spherical particle system can enhance the particle interlocks,and using the oblate particles should have more important influence than prolate particles.Moreover,the influence of particle shape on the spout deflection behaviors is quite complicated,and the use of prolate ellipsoidal particles versus oblate ellipsoidal particles may produce opposite effects.These findings should provide valuable insights for optimizing spouted bed operations involving complex particle mixtures.展开更多
Valorization of organic solid waste(OSW)is a promising avenue for the production of value-added products and renewable energy sources.This paper offers an exhaustive review of the thermochem-ical conversion processes ...Valorization of organic solid waste(OSW)is a promising avenue for the production of value-added products and renewable energy sources.This paper offers an exhaustive review of the thermochem-ical conversion processes in spouted bed reactors,which yield products like biochar,bio-oil,and syngas,as well as energy forms such as heat and electricity.While numerous studies have been conducted on thermoconversion in spouted beds,there is a scarcity of systematic reviews on this topic.This paper underscores the importance of spouted beds in torrefaction,pyrolysis,and gasification,drawing on both experimental and simulation perspectives.By focusing on reactor design,reaction condition optimiza-tion,and catalyst enhancement,OSW can be more efficiently transformed into valuable products and bioenergy.Furthermore,the integration of simulation and modeling offers profound insights into the intricate reactions that occur during thermal conversion.Current simulation studies in spouted bed reactors are primarily centered around reaction kinetics,Computational Fluid Dynamics(CFD)modeling,the Multiphase Particle-In-Cell(MP-PIC)approach,and process simulation.The future integration of Artificial Intelligence(AI)is anticipated to enhance parameter optimization with greater precision and facilitate industrial scale-up.The paper concludes with a synthesis and contemplation of the prospective advancements in spouted bed technology.展开更多
By employing the Eulerian-Eulerian Two Fluid Model, the effect of different particle size, supercritical CO_(2) (scCO_(2)) velocity at slit jet (U_(jet)) and initial bed height on the macroscopic characteristics (i.e....By employing the Eulerian-Eulerian Two Fluid Model, the effect of different particle size, supercritical CO_(2) (scCO_(2)) velocity at slit jet (U_(jet)) and initial bed height on the macroscopic characteristics (i.e., fountain morphology, profiles of particle velocity, momentum transfer characteristics among particles, transient temperature evolutions of particles, interphase heat transfer coefficient and wall to bed heat transfer characteristics) in the pseudo 2D rectangular spouted bed using scCO_(2) as fluidizing agent is numerically studied in detail herein. Considering there are currently no relevant visualized experiments reported using scCO_(2) as a fluidized agent due to the extreme operating pressure of CO_(2) (25 MPa in this paper) under supercritical conditions, present numerical model was validated with experimental data by using air as the fluidizing agent, confirming simulated instantaneous volume fraction distribution of air and transient temperature evolutions of particles basically consistent with the experiments. Numerical results reveal some of the internal relations among hydrodynamics characteristics in bed, momentum transfer characteristics among particles and relevant heat transfer behaviours. Results show larger Ujet and smaller particle size will accelerate the particles' translational motion in spout, spout core and fountain core zone. Larger particle concentration will promote inter-particle collisions while suppress the kinetic motion of particles in above zones. Decrease the particle size will enhance interphase convective heat transfer coefficient, while increasing U_(jet) results insignificant impacts. Finally, we also observe the transition zone between annular and periphery zone has a certain enhancing effect on the wall to bed heat transfer coefficient.展开更多
Due to the lack of gas-solid radial mixing in conventional spouted bed(CSB),particles are prone to accumulation and the formation of flow dead zones.To address the limitations of CSBs,this study,for the first time,the...Due to the lack of gas-solid radial mixing in conventional spouted bed(CSB),particles are prone to accumulation and the formation of flow dead zones.To address the limitations of CSBs,this study,for the first time,the combination optimization of the two strengthening internal components of multi-jets and draft tube was carried out,and two new types of internal strengthening structural spouted beds were proposed:the Integral Multi-jets Draft-tube Spout-fluidized Bed(IMDSFB),and the Integral Multi-jets Open-hole Draft-tube Spout-fluidized Bed(IMODSFB).At the same time,the hydrodynamic character-istics of IMDSFB and IMODSFB are studied by numerical simulation for the first time and compared with the draft tube spouted bed(DTSB)and CSB.Results indicate that compared to CSB,the spouting heights of the DTSB,IMDSFB,and IMODSFB were enhanced by 2.92%,14.75%,and 7.94%,respectively,and the dead zone of the DTSB,IMDSFB,and IMODSFB decreased by 14%,1%,and 5%,respectively.Compared to the CSB and DTSB,the addition of novel internal components notably improved the radial velocities of both gas and particles,as well as the gas-solid slip velocity,while reducing flow dead zones within the bed.Furthermore,the gas turbulence kinetic energy in the novel spout-fluidized beds was higher,with increased fluctuations of gas velocity in the spouting region.The granular temperature in the IMDSFB and IMODSFB was higher than in the CSB and DTSB,indicating enhanced particle fluctuations within the bed.These improvements contribute to more efficient gas-solid phase interactions,thereby enhancing the overall performance of the spouted bed.展开更多
One of the emerging applications of spouted beds is their utilization as thermal energy storage units in concentrated solar power systems(CSP).Computational Fluid Dynamics-Discrete Element Method(CFD-DEM)is one of the...One of the emerging applications of spouted beds is their utilization as thermal energy storage units in concentrated solar power systems(CSP).Computational Fluid Dynamics-Discrete Element Method(CFD-DEM)is one of the approaches to model multiphase flow reactors and gain insights into their behavior.Although several studies have used the CFD-DEM approach to investigate heat transfer in fluidized and spouted beds,research on CFD-DEM thermal modeling of spouted beds specifically as solar receivers in CSP systems remains limited.Therefore,the aim of this study is to evaluate the predictive capability of the CFD-DEM approach for modeling spouted bed thermal receivers and to gain insight into the hydrodynamic and thermal parameters that influence simulation results.An open-source program MFIX(Multiphase Flow with Interphase Exchanges)was used for model development.For model validation both cold and hot laboratory scale(15 cm cylindrical diameter,60°conical angle)conical spouted beds were built and used in experiments.CFD-DEM simulations were carried out for Carbo HSP particles(dp=0.95 mm,ρp=3630 kg/m^(3))at a static bed height of 100 mm.Throughout the study,the coarse-grained particle-DEM(CGP-DEM)method was used to reduce the computational time.The hydrodynamic simulation results indicate that gas-solid flow behavior in the spouted bed is well captured using both CGP-CFD-DEM and CFD-DEM approaches.The coarse-grained simulations of convective cooling during the discharge of a directly irradiated spouted bed with CarboHSP particles slightly underpredict the experimental cooling curve.Since the cooling curve is highly sensitive to wall boundary conditions,accurately determining these conditions is crucial for precise heat loss predictions.Furthermore,the coarse-grained particle diameter was found to have no significant effect on bed temperature.展开更多
Experiments were conducted in a rectangular spouted bed to study the effect of surface modification of the particles on the gas-solid hydrodynamics.The surface was modified by doing coating the particles with acrylic ...Experiments were conducted in a rectangular spouted bed to study the effect of surface modification of the particles on the gas-solid hydrodynamics.The surface was modified by doing coating the particles with acrylic paint.A completely different solid flow pattern was observed at the onset of spouting when coated particles were used.Instead of forming a cavity at the gas entry nozzle,particles from the top of the bed were fluidized at a particular gas flow rate,and a crack propagated downwards.After that,a big gas bubble formed at the bottom,which subsequently underwent bursting with the release of pressure.We report such hitherto unknown phenomena for a shallow granular bed for the first time.Instantaneous particle dynamics have been characterized using high-speed imaging.It is deduced that the cohesiveness of coated particles is the controlling parameter for this anomalous spouting behavior.Peak pressure drop and the corresponding superficial gas velocity for coated glass beads are more significant than uncoated particles for the same static bed height.A homogenous mixture of uncoated and coated glass beads exhibited bed characteristics as that of pure coated particles if the volume fraction of coated particles is greater than 20%.展开更多
The spouted bed has been used in the coating process of high-density nuclear fuel particle.The particle fluidization behaviors in pseudo-2D and 3D spouted beds were simulated and validated.The effects of four independ...The spouted bed has been used in the coating process of high-density nuclear fuel particle.The particle fluidization behaviors in pseudo-2D and 3D spouted beds were simulated and validated.The effects of four independent variables(cone angle,particle density,inlet gas velocity,and particle loading)on particle fluidization behaviors in the 3D spouted bed were investigated systematically.The cone angle effect on fluidization mechanism was studied quantitatively first time.A new fluidization quality index was proposed based on the particle entrainment principle,and an extreme value was obtained when the cone angle was 60°,considered to be the optimum value for the 3D conical spouted bed.It was indicated the gas–solid contact efficiency can be kept up if the gas velocity was proportional to ρ_(p)^(0.65) and N_(p)^(0.78) when the particle density or loading was increased.These results will be useful for geometry and operation parameters design of the 3D conical spouted bed and helpful for developing the fluidization mechanism of high-density particles.展开更多
Numerical simulation study is conducted for a pressurized spouted fluidized bed coal carbonizer, in which hydrodynamics of pressurized spouted fluidized bed, chemical reactions and energy balance are taken into accoun...Numerical simulation study is conducted for a pressurized spouted fluidized bed coal carbonizer, in which hydrodynamics of pressurized spouted fluidized bed, chemical reactions and energy balance are taken into account. The effect of operating conditions such as bed pressure, air and steam mass flow ratio, temperature on product compositions in the bed is investigated. According to the calculated results, bed pressure and bed temperature have the key effects on coal semi gasification.展开更多
Spouted bed has drawn much attention due to its good heat and mass transfer efficiency in many chemical units.Investigating the flow patterns and heat and mass transfer inside a spouted bed can help optimize the spout...Spouted bed has drawn much attention due to its good heat and mass transfer efficiency in many chemical units.Investigating the flow patterns and heat and mass transfer inside a spouted bed can help optimize the spouting process.Therefore,in this study,the effects of particle shape on the hydrodynamics and heat transfer in a spouted bed are investigated.This is done by using a validated computational fluid dynamics-discrete element method(CFD-DEM)model,considering volume-equivalent spheres and oblate and prolate spheroids.The results are analysed in detail in terms of the flow pattern,microstruc-ture,and heat transfer characteristics.The numerical results show that the prolate spheroids(Ar=2.4)form the largest bubble from the beginning of the spouting process and rise the highest because the fluid drag forces can overcome the interlocking and particle-particle frictional forces.Compared with spherical particles,ellipsoidal spheroids have better mobility because of the stronger rotational kinetic energy resulting from the rough surfaces and nonuniform torques.In addition,the oblate spheroid system exhibits better heat transfer performance benefiting from the larger surface area,while prolate spheroids have poor heat transfer efficiency because of their orientation distribution.These findings can serve as a reference for optimizing the design and operation of complex spouted beds.展开更多
Using a high-viscosity Newtonian fluid, glycerol, an experimental investigation was carried out to evaluate the stable spouting regime in conical spouted beds using four particle mixtures： a reference （monoparticles...Using a high-viscosity Newtonian fluid, glycerol, an experimental investigation was carried out to evaluate the stable spouting regime in conical spouted beds using four particle mixtures： a reference （monoparticles）, a binary mixture, two ternary mixtures with flat and Gaussian distributions respectively. The mixtures were selected for particle diameters （dp） ranging from 1.09 to 4.98 mm and particle diameter ratios （dpL/dps） ranging from 1.98 to 4.0. Experimental data show that pressure fluctuation signals of the bed, as indicated by changes in their standard deviations, provide suitable information to identify the range of operational conditions for stable spouting. However, the analysis of skewness of curves of pressure fluctuation as a function of air velocity appears not sufficient to identify a particular flow regime. For glycerol in the spouting regime, the standard deviation is noted to increase with increasing glycerol concentration due to the growth of interparticle forces. The implications of these research findings on the drying of suspensions in conical spouted beds using glass bead mixtures are also discussed.展开更多
An improved and efficient DEM-CFD approach is developed for spouted beds. A nonlinear Discrete Element Method （DEM）, with a concept of spring, dash-pot and friction slider, is used for tracing the movement of each i...An improved and efficient DEM-CFD approach is developed for spouted beds. A nonlinear Discrete Element Method （DEM）, with a concept of spring, dash-pot and friction slider, is used for tracing the movement of each individual particle. The gas flow is described by a set of reorganized governing equations. Two phases are coupled through contributions due to effects of porosity, viscosity and drag. All equations are solved with the commercial package Fluent with an implementation of User Defined Functions （UDF）. To validate the improved model, a two-dimensional conical-base spouted bed is chosen as a case study. An unstructured mesh system is adopted instead of regular grid system. The simulation also takes the Saffman force and Magnus effect into account. The calculation results show good agreement with the experimental observations which are taken from the literature.展开更多
基金Supported by the National Natural Science Foundation of China(51206020)the Program for New Century Excellent Talents in University(NCET-12-0703)the Northeast Petroleum University Foundation
文摘Flow behavior of gas and particles in conical spouted beds is experimentally studied and simulated using the twofluid gas-solid model with the kinetic theory of granular flow.The bed pressure drop and fountain height are measured in a conical spouted bed of 100 mm I.D.at different gas velocities.The simulation results are compared with measurements of bed pressure drop and fountain height.The comparison shows that the drag coefficient model used in cylindrical beds under-predicted bed pressure drop and fountain height in conical spouted beds due to the partial weight of particles supported by the inclined side walls.It is found that the numerical results using the drag coefficient model proposed based on the conical spouted bed in this study are in good agreement with experimental data.The present study provides a useful basis for further works on the CFD simulation of conical spouted bed.
基金Supported by the Doctorate Discipline Foundation of the Ministry of Education of China(No.2000042053)& China National Petroleum Co
文摘On the basis of hydrodynamic and scaling-up studies, a pilot-plant-scale thermal spouted bed reactor (50 mm in ID and 1500 mm in height) was designed and fabricated by scaling-down cold simulators. It was tested for making syngas via catalytic partial oxidation (CPO) of methane by air. The effects of various operating conditions such as operating pressure and temperature, feed composition, and gas flowrate etc. on the CPO process were investigated. CH4 conversion of 92.2% and selectivity of 92.3% and 83.3% to CO and H2, respectively, were achieved at the pressure of 2.1 MPa. It was found that when the spouted bed reactor was operated within the stable spouting flow regime, the temperature profiles along the bed axis were much more uniform than those operated within the fixed-bed regime. The CH4 conversion and syngas selectivity were found to be close to thermodynamic equilibrium limits. The results of the present investigation showed that spouted bed could be considered as a potential type of chemical reactor for the CPO process of methane.
基金Supported by the Three-Item Science & Technology Foundation of Fujian Province(K02017)
文摘A novel reaction-drying process was carried out in a spouted bed reactor with inert particles and used to prepare ultrafine CaCO3 particles. Effects of concentrations of CO2 and Ca(OH)2, and reaction temperature on Ca(OH)2 conversion were experimentally investigated. The particle sizes and composition of CaCO3 produced were characterized with transmission electron microscopy (TEM) and X-ray diffraction (XRD). The results indicated that ultrafine CaCO3 particles with mean size of 80 nm could be obtained with this novel process.By modifying the Arrhenius Equation and considering the Ca(OH)2 state, a kinetic model was established to describe the process in the spouted bed. The model parameters estimated from the reaction-drying experiments were found to fit well the experimental data, indicating the applicability of the proposed kinetic model.
基金supported by the National Natural Science Foundation of China(22178286)Shaanxi Qin Chuangyuan“scientist and engineer”team construction project(2022KXJ-041).
文摘The development of intensification technology for spouted beds has become a current research focus,and an effective way to improve the efficiency of spouted beds is to reform their structure.Although numerous studies have been conducted on conventional beds,there are few reviews on the comprehensive application of intensification technology for spouted beds.In this paper,we comprehensively review the role of intensification technology in spouted beds for use in hydrodynamics,drying,desulfurization,pyrolysis,coating,biomass and waste gasification,and biomass drying from the perspective of experiment and simulation.Finally,potential problems and challenges in current spouted-bed research are summarized.
基金Supported by the National Natural Science Foundation of China (No. 20490201) the Ministry of Education of China through the Doctorate Discipline Foundation (No. 2000042503).
文摘In a spouted bed of 80mm in ID and 1700mm in height, the gas residence time distributions at different radial positions in both spout and annular area were measured with five different kinds of particles as spouting material, air as spouting gas, and hydrogen as tracer. The effects of superficial gas velocity, operating pressure, particle size and its category on gas residence time distribution were discussed. It was found that the gas velocity profile in spout was more uniform than that in annulus. It could be concluded that the gas flow in the spout could be treated as a plug-flow, while that in the annulus inhibited a strong non-ideal flow behavior. Increasing the superficial gas velocity and decreasing the operating pressure, the particle density and its size gave rise to spouting disturbance, thus the measured tracer concentrations vs. time curves fluctuated. The variances of residence time distribution curves could be taken as a measure of the gas fluctuation degree.
基金funding from the grant PID2022-139454OB-I00 funded by MCIN/AEI/10.13039/501100011033the grants IT1645−22,KK−2023/00060 and PUE_2024_1_0006 funded by the Basque Government and the grants#2017/01856-7 and#2018/22655-2 funded by the Sao Paulo State Research Foundation(FAPESP)+1 种基金Moreover,this project has received funding from the European Comission,HORIZON H2020-MSCA-2023-SE-01,ID:101182827Maider Bolaños thanks the University of the Basque Country UPV/EHU for her Ph.D.grant(PIF21/69).
文摘Novel draft tubes have been assessed to scale up the spouted bed technology. Accordingly, alumina drying runs have been conducted using different configurations (without tube and with open-sided and nonporous tubes) under intermittent strategies consisting in alternating periods of drying and periods of reduction or interruption of the air flow rate, and they have been compared with continuous drying. Furthermore, the influence the draft tubes have on the drying performance and energy requirements in the drying process has been evaluated. The results allow inferring that intermittent drying considerably decreases both drying time and energy requirements. Moreover, the new draft tubes improved the drying of alumina, as a similar energy efficiency than without draft tube was attained with lower specific energy consumption, which is essential to reduce the high-energy demand in the drying process and mitigate climate change. These findings, along with the stability the new tubes provided to the process, involve a further step in the scale up of spouted beds for industrial operations.
基金the financial support of the Scientific and Technological Research Council of Turkey(Project No.:MAG 122M514).
文摘One of the emerging applications of spouted beds is their use as thermal receivers in CSP systems,offering significant advantages such as high heat transfer rates and uniform temperature distribution.However,experimental studies on directly irradiated spouted beds remain limited in the literature.The aim of this study was to investigate the thermal performance of a directly irradiated spouted bed receiver using CarboHSP and olivine particles.Experiments were conducted in a 0.15 m ID spouted bed with a 60°conical angle.Hydrodynamic experiments were first performed to understand the gas-solid dynamics and establish a foundation for subsequent thermal studies.The solar radiation was simulated by a 2 kWe metal halide lamp.Temperature profiles influenced by particle size,spouting velocity,and particle type were analyzed,and charge and discharge efficiencies were determined.Higher temperatures are obtained as the particle size and spouting gas velocity are reduced.The results also show that olivine particles are a cost-effective alternative for spouted bed thermal receivers,offering thermal performance comparable to CarboHSP particles.
文摘A numerical investigation of the three-dimensional conical spouted bed was conducted using CFD coupled with discrete element method to systematically analyze particle-gas flow patterns,bubble volume fluctuations,and fountain characteristics.Moreover,the impact of conical angles on dynamic characteristics is demonstrated under varying gas inlet velocity and particle diameter.Firstly,the simulation result shows that increasing the conical angle is advantageous for enhancing both y-direction and angular velocities of particles,while the impact of this angle varies with inlet velocity and particle diameter.The great inlet velocity and particle diameter significantly enhance the voidage,while the larger conical angle promotes the uniform radial particle distribution.Besides,smaller conical angle and medium inlet velocity is prone to result in the higher frequency and amplitude for the fluctuations of particle height.Meanwhile,enlarging the conical angle results in a shift of the fountain frequency from high to low when the particle size is small.The conical angle plays a crucial role in determining bubble behavior under the condition of medium velocity and small diameter.Besides,the fine particle and small conical angle are prone to cause the noticeable main frequencies.
基金the financial support of the grants PID2022-140704OB-I00,PID2022-139454OB-I00 and PID2023-147671OB-I00 funded by MICIU/AEI/10.13039/501100011033 and by“ERDF/EU”the grant CNS2023-144031 funded by MICIU/AEI/10.13039/501100011033+2 种基金the“European Union NextGenerationEU/PRTR”,and the grants IT1645-22 and KK-2023/00060 funded by the Basque Government.Moreoverthis project has received funding from European Union's Horizon 2020 research and innovation programme(HORIZON-MSCA-2023-SE-01),Project ID:101182827Authors also acknowledge the funds received within the project PLAST4H2 EAPA 0018/2022 within the framework on the INTERREG ATLANTIC program.
文摘This paper presents an alternative approach for plastic waste valorization in a fountain confined conical spouted bed reactor.The study evaluates the application of an upgraded spouted bed design for the steam cracking of polypropylene(PP)at 750℃,focusing on high value added products.The highly efficient cracking process results in a high gas yield of 80.9 wt%.This stream is composed of H_(2),CO,CO_(2),C_(1)-C_(4)paraffins and C_(2)-C_(4)olefins,with the latter reaching a total yield of 49.2 wt%.Among the light olefins,propylene(21.8 wt%)and ethylene(16.5 wt%)are the most relevant.Interestingly,a remarkable yield of the valuable BTX fraction was obtained,14.0 wt%,with benzene being the predominant compound.The reactor configuration and excellent control of process conditions enhanced light olefins yield byβ-scission and radical mechanism,promoting the formation of light hydrocarbons,as well as minimizing secondary oligomerization and reforming reactions.This study is a proof of the viability of steam cracking in a fountain confined spouted bed reactor for converting PP into valuable chemical intermediates,as well as the viability of this technology for industrial application in waste plastic valorization.
基金the National Natural Science Foundation of China(grant No.52264042)Jiangxi Provincial Natural Science Foundation(grant Nos.20242BAB23034,20242BAB20162,20223AAG01009,and 20214BBG74005)Taishan Scholars Program(grant No.tsqn202408001)for financial supports to this work。
文摘Spouted bed is a type of fluidized bed that has been widely used in various industrial processes because of its excellent mass and heat transfer efficiency.In practical applications,the fluidization of the multicomponent particle system containing non-spherical particles is frequently encountered in spouted beds.To better understand the spouting behaviors of the multicomponent particle system,therefore,this study employs a CFD-DEM(Computational Fluid Dynamics-Discrete Element Method)coupling approach to investigate the spouting behaviors.Spherical particles along with two types of ellipsoidal particles(i.e.,oblate ellipsoid,and prolate ellipsoid)are included in this paper.Through the combination of these three particle types,seven distinct systems(three monodisperse systems,three binary mixtures,and one ternary mixture)are simulated to analyze the effects of particle shape and composition of particle systems on spouting behaviors.The simulation results reveal that introducing non-spherical particles into systems containing either spherical or oblate ellipsoidal particles tends to enhance spouting behaviors,whereas adding spherical particles to prolate ellipsoidal particle systems inclines to suppress it.The addition of non-spherical particles into the spherical particle system can enhance the particle interlocks,and using the oblate particles should have more important influence than prolate particles.Moreover,the influence of particle shape on the spout deflection behaviors is quite complicated,and the use of prolate ellipsoidal particles versus oblate ellipsoidal particles may produce opposite effects.These findings should provide valuable insights for optimizing spouted bed operations involving complex particle mixtures.
基金supported by National Natural Science Foundation of China(grant No.52476207)Shandong Province Excellent Youth Science Fund Project(grant No.2023HWYQ-022)+1 种基金Taishan Scholars Youth Expert Program of Shandong Province(grant No.tsqn202312002)Qilu Youth Scholar Program of Shandong University.
文摘Valorization of organic solid waste(OSW)is a promising avenue for the production of value-added products and renewable energy sources.This paper offers an exhaustive review of the thermochem-ical conversion processes in spouted bed reactors,which yield products like biochar,bio-oil,and syngas,as well as energy forms such as heat and electricity.While numerous studies have been conducted on thermoconversion in spouted beds,there is a scarcity of systematic reviews on this topic.This paper underscores the importance of spouted beds in torrefaction,pyrolysis,and gasification,drawing on both experimental and simulation perspectives.By focusing on reactor design,reaction condition optimiza-tion,and catalyst enhancement,OSW can be more efficiently transformed into valuable products and bioenergy.Furthermore,the integration of simulation and modeling offers profound insights into the intricate reactions that occur during thermal conversion.Current simulation studies in spouted bed reactors are primarily centered around reaction kinetics,Computational Fluid Dynamics(CFD)modeling,the Multiphase Particle-In-Cell(MP-PIC)approach,and process simulation.The future integration of Artificial Intelligence(AI)is anticipated to enhance parameter optimization with greater precision and facilitate industrial scale-up.The paper concludes with a synthesis and contemplation of the prospective advancements in spouted bed technology.
基金support provided by the National Key R&D Program of China(grant No.2020YFA0714400).
文摘By employing the Eulerian-Eulerian Two Fluid Model, the effect of different particle size, supercritical CO_(2) (scCO_(2)) velocity at slit jet (U_(jet)) and initial bed height on the macroscopic characteristics (i.e., fountain morphology, profiles of particle velocity, momentum transfer characteristics among particles, transient temperature evolutions of particles, interphase heat transfer coefficient and wall to bed heat transfer characteristics) in the pseudo 2D rectangular spouted bed using scCO_(2) as fluidizing agent is numerically studied in detail herein. Considering there are currently no relevant visualized experiments reported using scCO_(2) as a fluidized agent due to the extreme operating pressure of CO_(2) (25 MPa in this paper) under supercritical conditions, present numerical model was validated with experimental data by using air as the fluidizing agent, confirming simulated instantaneous volume fraction distribution of air and transient temperature evolutions of particles basically consistent with the experiments. Numerical results reveal some of the internal relations among hydrodynamics characteristics in bed, momentum transfer characteristics among particles and relevant heat transfer behaviours. Results show larger Ujet and smaller particle size will accelerate the particles' translational motion in spout, spout core and fountain core zone. Larger particle concentration will promote inter-particle collisions while suppress the kinetic motion of particles in above zones. Decrease the particle size will enhance interphase convective heat transfer coefficient, while increasing U_(jet) results insignificant impacts. Finally, we also observe the transition zone between annular and periphery zone has a certain enhancing effect on the wall to bed heat transfer coefficient.
基金supported by National Natural Science Foundation of China(grant No.22478317).
文摘Due to the lack of gas-solid radial mixing in conventional spouted bed(CSB),particles are prone to accumulation and the formation of flow dead zones.To address the limitations of CSBs,this study,for the first time,the combination optimization of the two strengthening internal components of multi-jets and draft tube was carried out,and two new types of internal strengthening structural spouted beds were proposed:the Integral Multi-jets Draft-tube Spout-fluidized Bed(IMDSFB),and the Integral Multi-jets Open-hole Draft-tube Spout-fluidized Bed(IMODSFB).At the same time,the hydrodynamic character-istics of IMDSFB and IMODSFB are studied by numerical simulation for the first time and compared with the draft tube spouted bed(DTSB)and CSB.Results indicate that compared to CSB,the spouting heights of the DTSB,IMDSFB,and IMODSFB were enhanced by 2.92%,14.75%,and 7.94%,respectively,and the dead zone of the DTSB,IMDSFB,and IMODSFB decreased by 14%,1%,and 5%,respectively.Compared to the CSB and DTSB,the addition of novel internal components notably improved the radial velocities of both gas and particles,as well as the gas-solid slip velocity,while reducing flow dead zones within the bed.Furthermore,the gas turbulence kinetic energy in the novel spout-fluidized beds was higher,with increased fluctuations of gas velocity in the spouting region.The granular temperature in the IMDSFB and IMODSFB was higher than in the CSB and DTSB,indicating enhanced particle fluctuations within the bed.These improvements contribute to more efficient gas-solid phase interactions,thereby enhancing the overall performance of the spouted bed.
基金was support of the Scientific and Technological Research Council of Turkey(Project No.MAG 122M514)。
文摘One of the emerging applications of spouted beds is their utilization as thermal energy storage units in concentrated solar power systems(CSP).Computational Fluid Dynamics-Discrete Element Method(CFD-DEM)is one of the approaches to model multiphase flow reactors and gain insights into their behavior.Although several studies have used the CFD-DEM approach to investigate heat transfer in fluidized and spouted beds,research on CFD-DEM thermal modeling of spouted beds specifically as solar receivers in CSP systems remains limited.Therefore,the aim of this study is to evaluate the predictive capability of the CFD-DEM approach for modeling spouted bed thermal receivers and to gain insight into the hydrodynamic and thermal parameters that influence simulation results.An open-source program MFIX(Multiphase Flow with Interphase Exchanges)was used for model development.For model validation both cold and hot laboratory scale(15 cm cylindrical diameter,60°conical angle)conical spouted beds were built and used in experiments.CFD-DEM simulations were carried out for Carbo HSP particles(dp=0.95 mm,ρp=3630 kg/m^(3))at a static bed height of 100 mm.Throughout the study,the coarse-grained particle-DEM(CGP-DEM)method was used to reduce the computational time.The hydrodynamic simulation results indicate that gas-solid flow behavior in the spouted bed is well captured using both CGP-CFD-DEM and CFD-DEM approaches.The coarse-grained simulations of convective cooling during the discharge of a directly irradiated spouted bed with CarboHSP particles slightly underpredict the experimental cooling curve.Since the cooling curve is highly sensitive to wall boundary conditions,accurately determining these conditions is crucial for precise heat loss predictions.Furthermore,the coarse-grained particle diameter was found to have no significant effect on bed temperature.
基金the support of BRNS,DAE,Govt.of India(No:34/14/15/2016-BRNS/34040).
文摘Experiments were conducted in a rectangular spouted bed to study the effect of surface modification of the particles on the gas-solid hydrodynamics.The surface was modified by doing coating the particles with acrylic paint.A completely different solid flow pattern was observed at the onset of spouting when coated particles were used.Instead of forming a cavity at the gas entry nozzle,particles from the top of the bed were fluidized at a particular gas flow rate,and a crack propagated downwards.After that,a big gas bubble formed at the bottom,which subsequently underwent bursting with the release of pressure.We report such hitherto unknown phenomena for a shallow granular bed for the first time.Instantaneous particle dynamics have been characterized using high-speed imaging.It is deduced that the cohesiveness of coated particles is the controlling parameter for this anomalous spouting behavior.Peak pressure drop and the corresponding superficial gas velocity for coated glass beads are more significant than uncoated particles for the same static bed height.A homogenous mixture of uncoated and coated glass beads exhibited bed characteristics as that of pure coated particles if the volume fraction of coated particles is greater than 20%.
基金funded by National Youth Talent Support Program(grant number 20224723061)National major S&T Project(grant number ZX06901).
文摘The spouted bed has been used in the coating process of high-density nuclear fuel particle.The particle fluidization behaviors in pseudo-2D and 3D spouted beds were simulated and validated.The effects of four independent variables(cone angle,particle density,inlet gas velocity,and particle loading)on particle fluidization behaviors in the 3D spouted bed were investigated systematically.The cone angle effect on fluidization mechanism was studied quantitatively first time.A new fluidization quality index was proposed based on the particle entrainment principle,and an extreme value was obtained when the cone angle was 60°,considered to be the optimum value for the 3D conical spouted bed.It was indicated the gas–solid contact efficiency can be kept up if the gas velocity was proportional to ρ_(p)^(0.65) and N_(p)^(0.78) when the particle density or loading was increased.These results will be useful for geometry and operation parameters design of the 3D conical spouted bed and helpful for developing the fluidization mechanism of high-density particles.
文摘Numerical simulation study is conducted for a pressurized spouted fluidized bed coal carbonizer, in which hydrodynamics of pressurized spouted fluidized bed, chemical reactions and energy balance are taken into account. The effect of operating conditions such as bed pressure, air and steam mass flow ratio, temperature on product compositions in the bed is investigated. According to the calculated results, bed pressure and bed temperature have the key effects on coal semi gasification.
基金the financial supports from the National Natural Science Foundation ofChina(grant No.51904122)the Key Project of Jiangxi Provincial Research and Development(grant No.20192BBHL80016)+2 种基金the jiangxi Provincial Natural Science Foundation(grant No.20212BAB214023)the Opening Research Project of State Key Laboratory of Multiphase Flow in Power Engineering(grant No.SKLMF-KF-1901)the China Postdoctoral Science Foundation Funding(grant No.2021M690975).
文摘Spouted bed has drawn much attention due to its good heat and mass transfer efficiency in many chemical units.Investigating the flow patterns and heat and mass transfer inside a spouted bed can help optimize the spouting process.Therefore,in this study,the effects of particle shape on the hydrodynamics and heat transfer in a spouted bed are investigated.This is done by using a validated computational fluid dynamics-discrete element method(CFD-DEM)model,considering volume-equivalent spheres and oblate and prolate spheroids.The results are analysed in detail in terms of the flow pattern,microstruc-ture,and heat transfer characteristics.The numerical results show that the prolate spheroids(Ar=2.4)form the largest bubble from the beginning of the spouting process and rise the highest because the fluid drag forces can overcome the interlocking and particle-particle frictional forces.Compared with spherical particles,ellipsoidal spheroids have better mobility because of the stronger rotational kinetic energy resulting from the rough surfaces and nonuniform torques.In addition,the oblate spheroid system exhibits better heat transfer performance benefiting from the larger surface area,while prolate spheroids have poor heat transfer efficiency because of their orientation distribution.These findings can serve as a reference for optimizing the design and operation of complex spouted beds.
文摘Using a high-viscosity Newtonian fluid, glycerol, an experimental investigation was carried out to evaluate the stable spouting regime in conical spouted beds using four particle mixtures： a reference （monoparticles）, a binary mixture, two ternary mixtures with flat and Gaussian distributions respectively. The mixtures were selected for particle diameters （dp） ranging from 1.09 to 4.98 mm and particle diameter ratios （dpL/dps） ranging from 1.98 to 4.0. Experimental data show that pressure fluctuation signals of the bed, as indicated by changes in their standard deviations, provide suitable information to identify the range of operational conditions for stable spouting. However, the analysis of skewness of curves of pressure fluctuation as a function of air velocity appears not sufficient to identify a particular flow regime. For glycerol in the spouting regime, the standard deviation is noted to increase with increasing glycerol concentration due to the growth of interparticle forces. The implications of these research findings on the drying of suspensions in conical spouted beds using glass bead mixtures are also discussed.
文摘An improved and efficient DEM-CFD approach is developed for spouted beds. A nonlinear Discrete Element Method （DEM）, with a concept of spring, dash-pot and friction slider, is used for tracing the movement of each individual particle. The gas flow is described by a set of reorganized governing equations. Two phases are coupled through contributions due to effects of porosity, viscosity and drag. All equations are solved with the commercial package Fluent with an implementation of User Defined Functions （UDF）. To validate the improved model, a two-dimensional conical-base spouted bed is chosen as a case study. An unstructured mesh system is adopted instead of regular grid system. The simulation also takes the Saffman force and Magnus effect into account. The calculation results show good agreement with the experimental observations which are taken from the literature.
