Minimum spouting velocity （Ums） is one of the most important flow characteristics for proper design and operation of spouted bed reactors. Many correlations for Ums have been published since spouted bed technology w...Minimum spouting velocity （Ums） is one of the most important flow characteristics for proper design and operation of spouted bed reactors. Many correlations for Ums have been published since spouted bed technology was initiated in 1955. In this paper, a new correlation is developed for Ums based on 767 published experimental data covering both high pressure and high temperature conditions. The calculated and the measured results of Ums are in better agreement than other published correlations.展开更多
Experiments were performed on spout characteristics of a cylindrical spout-fluidized bed （I.D. = 10 cm） with different static heights and two materials （A1203 and high density polyethylene）. Results of minimum spo...Experiments were performed on spout characteristics of a cylindrical spout-fluidized bed （I.D. = 10 cm） with different static heights and two materials （A1203 and high density polyethylene）. Results of minimum spouting velocity obtained in this study were compared with reported correlations for both spouted and spout-fluidized beds. Considerable discrepancies were found between the values obtained using different model equations as well as with respect to experimental results. Based on the Mathur-Gishler correlation, a new correlation is proposed for calculating the minimum spouting velocity that introduces the ratio U/Umf. It was found that the minimum spouting velocity decreases with increasing fluidizing gas velocity （U/Umf）. The pressure drop at the point of minimum spouting velocity is also correlated using this dimensionless group and is presented in this work. This investigation demonstrates that the use of correlations reported in the literature that focus primarily on conical bottom spouted beds are not applicable to fiat-bottom spouted and spout-fluidized beds.展开更多
This paper is devoted to outlining precisely the basic mathematics of a classical isoperimetric problem of the calculus of variations and showing how significant fluid mechanical problems in fluidization and spouting ...This paper is devoted to outlining precisely the basic mathematics of a classical isoperimetric problem of the calculus of variations and showing how significant fluid mechanical problems in fluidization and spouting can be addressed using this approach.展开更多
Visitors admire the Hukou Waterfall on the Yellow River in Yichuan County,Yan’an City,Shaanxi Province,on 11 August.It is the second-largest waterfall in China,as well as the largest yellow waterfall in the world.Kno...Visitors admire the Hukou Waterfall on the Yellow River in Yichuan County,Yan’an City,Shaanxi Province,on 11 August.It is the second-largest waterfall in China,as well as the largest yellow waterfall in the world.Known for its dramatic appearance,the waterfall narrows to just 20-30 metres before plunging over a cliff,resembling the spout of a teapot.展开更多
From experime nts, the influe nee of the physical characteristics of different bin ary mixtures of solids on the spouting regime of a pyramidal square-based spouted bed reactor is assessed. The applied methodology per...From experime nts, the influe nee of the physical characteristics of different bin ary mixtures of solids on the spouting regime of a pyramidal square-based spouted bed reactor is assessed. The applied methodology permits a more precise evaluation of the effects of the tested variables (diameter, density, sphericity) on the response variables (minimum air flows at which spouting begins and at which to maintain spouting con ditions). The associated pressure drops along the bed of particles a nd the height of the formed fountai n are analysed in each case. During the initial stages of fluidisation, binary mixtures containing different density ratios show dead zones. Segregation becomes more evident at large-size and high-density ratios. The lack of sphericity was found to be the main reason leading to blocking, channelling, and start-up problems when system failures occur. Nevertheless, the extent of segregation in all cases decreases with increasing the spouting velocity. In addition, a computational fluid dynamic model based on the discrete element method, previously validated for a single solid bed, is proposed as a tool to predict and evaluate potential segregation phenomena in binary mixtures. This model reproduced with high accuracy the encountered segregation phenomena. Its use may help define the technical limts inherent in the pyramidal spouted bed reactor.展开更多
Numerous industrial applications of spouted beds involve a mixture of granular particles, where differences in particle size, density, and shape can cause particle segregation, affecting the quality of flow and decrea...Numerous industrial applications of spouted beds involve a mixture of granular particles, where differences in particle size, density, and shape can cause particle segregation, affecting the quality of flow and decreasing product homogeneity. The aim of this study was to investigate the particle segregation and fluid dynamics of a conical spouted bed operating with a binary mixture of particles of different densities. Using glass beads and polyethylene particles with a diameter of 4 mm, we determined the effects of the mass fraction of denser particles and static bed height on the minimum spouting condition and mixture index. The pressure drop and airflow in the minimum spouting condition increased with an increase in bed height or jetsam concentration. Regarding particle segregation, the jetsam particles tended to concentrate near the bottom, at the spout–annulus interface because they have a shorter trajectory than the lighter particles in the fountain region. Jetsam-rich mixtures with high initial static bed heights exhibited more efficient particle mixing, excluding those at the bottom of the bed.展开更多
The removal of volatile organic compounds by photocatalytic degradation is one of the safest and most effective ways of removing pollutants from the air. This process is highly affected by the type of reactor, light e...The removal of volatile organic compounds by photocatalytic degradation is one of the safest and most effective ways of removing pollutants from the air. This process is highly affected by the type of reactor, light exposure, and hydrodynamics. For scale up purposes, continuous reactors with high capacity are required for treating large amounts of feedstock. In this work, two types of reactors based on different hydrodynamics, fluidized and spouted reactors, were designed to work under light irradiation inside the reactor. The efficiency of the reactors for volatile organic compound removal from high flow rates of air under Hg lamp irradiation using N-F-TiO2 photocatalyst was investigated. The performance of the fluidized bed and spouted bed were evaluated and compared at the same weight hourly space velocity of feed stream through the reactor. The results revealed that 80% of the initial acetaldehyde was removed in the fluidized bed after about 200 min, while in the spouted bed the acetaldehyde was totally removed after about 120 min.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
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
Optimization of draft tube position in a spouted bed reactor used for treatment of wastewater containing low concentration of heavy metals is investigated in this paper. Response surface methodology is used to optimiz...Optimization of draft tube position in a spouted bed reactor used for treatment of wastewater containing low concentration of heavy metals is investigated in this paper. Response surface methodology is used to optimize the draft tube height, the draft tube width and the gap between the bottom of the draft tube and the inlet nozzle. It is observed that the draft tube with a height of 60 millimeter, width of 12 millimeter and the gap of 13 millimeter between its bottom and inlet nozzle, results in optimum value of minimum spouting velocity, measured 45 cubic centimeter per second (2.7 Liter per minute) .展开更多
In order to grasp the particle flow characteristics and energy consumption of industrial fluidized spouted beds,we conduct numerical simulations on the basis of a Computational Particle Fluid Dynamics(CPFD)approach.In...In order to grasp the particle flow characteristics and energy consumption of industrial fluidized spouted beds,we conduct numerical simulations on the basis of a Computational Particle Fluid Dynamics(CPFD)approach.In particular,the traction model of Wen-Yu-Ergun is used and different inlet conditions are considered.Using a low-speed fluidizing gas,the flow state of the particles is better and the amount of particles accumulated at the bottom of the bed wall becomes smaller.For the same air intake,the energy loss of a circular nozzle is larger than that of a square nozzle.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
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
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
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
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
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
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
基金the National Natural Science Foundation of China through the program ＂Time and Spatial Multi-Scale Interactions in Chemical Engineering and Their Effects＂ （Grant No. 20490201）.
文摘Minimum spouting velocity （Ums） is one of the most important flow characteristics for proper design and operation of spouted bed reactors. Many correlations for Ums have been published since spouted bed technology was initiated in 1955. In this paper, a new correlation is developed for Ums based on 767 published experimental data covering both high pressure and high temperature conditions. The calculated and the measured results of Ums are in better agreement than other published correlations.
文摘Experiments were performed on spout characteristics of a cylindrical spout-fluidized bed （I.D. = 10 cm） with different static heights and two materials （A1203 and high density polyethylene）. Results of minimum spouting velocity obtained in this study were compared with reported correlations for both spouted and spout-fluidized beds. Considerable discrepancies were found between the values obtained using different model equations as well as with respect to experimental results. Based on the Mathur-Gishler correlation, a new correlation is proposed for calculating the minimum spouting velocity that introduces the ratio U/Umf. It was found that the minimum spouting velocity decreases with increasing fluidizing gas velocity （U/Umf）. The pressure drop at the point of minimum spouting velocity is also correlated using this dimensionless group and is presented in this work. This investigation demonstrates that the use of correlations reported in the literature that focus primarily on conical bottom spouted beds are not applicable to fiat-bottom spouted and spout-fluidized beds.
文摘This paper is devoted to outlining precisely the basic mathematics of a classical isoperimetric problem of the calculus of variations and showing how significant fluid mechanical problems in fluidization and spouting can be addressed using this approach.
文摘Visitors admire the Hukou Waterfall on the Yellow River in Yichuan County,Yan’an City,Shaanxi Province,on 11 August.It is the second-largest waterfall in China,as well as the largest yellow waterfall in the world.Known for its dramatic appearance,the waterfall narrows to just 20-30 metres before plunging over a cliff,resembling the spout of a teapot.
文摘From experime nts, the influe nee of the physical characteristics of different bin ary mixtures of solids on the spouting regime of a pyramidal square-based spouted bed reactor is assessed. The applied methodology permits a more precise evaluation of the effects of the tested variables (diameter, density, sphericity) on the response variables (minimum air flows at which spouting begins and at which to maintain spouting con ditions). The associated pressure drops along the bed of particles a nd the height of the formed fountai n are analysed in each case. During the initial stages of fluidisation, binary mixtures containing different density ratios show dead zones. Segregation becomes more evident at large-size and high-density ratios. The lack of sphericity was found to be the main reason leading to blocking, channelling, and start-up problems when system failures occur. Nevertheless, the extent of segregation in all cases decreases with increasing the spouting velocity. In addition, a computational fluid dynamic model based on the discrete element method, previously validated for a single solid bed, is proposed as a tool to predict and evaluate potential segregation phenomena in binary mixtures. This model reproduced with high accuracy the encountered segregation phenomena. Its use may help define the technical limts inherent in the pyramidal spouted bed reactor.
文摘Numerous industrial applications of spouted beds involve a mixture of granular particles, where differences in particle size, density, and shape can cause particle segregation, affecting the quality of flow and decreasing product homogeneity. The aim of this study was to investigate the particle segregation and fluid dynamics of a conical spouted bed operating with a binary mixture of particles of different densities. Using glass beads and polyethylene particles with a diameter of 4 mm, we determined the effects of the mass fraction of denser particles and static bed height on the minimum spouting condition and mixture index. The pressure drop and airflow in the minimum spouting condition increased with an increase in bed height or jetsam concentration. Regarding particle segregation, the jetsam particles tended to concentrate near the bottom, at the spout–annulus interface because they have a shorter trajectory than the lighter particles in the fountain region. Jetsam-rich mixtures with high initial static bed heights exhibited more efficient particle mixing, excluding those at the bottom of the bed.
文摘The removal of volatile organic compounds by photocatalytic degradation is one of the safest and most effective ways of removing pollutants from the air. This process is highly affected by the type of reactor, light exposure, and hydrodynamics. For scale up purposes, continuous reactors with high capacity are required for treating large amounts of feedstock. In this work, two types of reactors based on different hydrodynamics, fluidized and spouted reactors, were designed to work under light irradiation inside the reactor. The efficiency of the reactors for volatile organic compound removal from high flow rates of air under Hg lamp irradiation using N-F-TiO2 photocatalyst was investigated. The performance of the fluidized bed and spouted bed were evaluated and compared at the same weight hourly space velocity of feed stream through the reactor. The results revealed that 80% of the initial acetaldehyde was removed in the fluidized bed after about 200 min, while in the spouted bed the acetaldehyde was totally removed after about 120 min.
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 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%.
文摘Optimization of draft tube position in a spouted bed reactor used for treatment of wastewater containing low concentration of heavy metals is investigated in this paper. Response surface methodology is used to optimize the draft tube height, the draft tube width and the gap between the bottom of the draft tube and the inlet nozzle. It is observed that the draft tube with a height of 60 millimeter, width of 12 millimeter and the gap of 13 millimeter between its bottom and inlet nozzle, results in optimum value of minimum spouting velocity, measured 45 cubic centimeter per second (2.7 Liter per minute) .
基金supported by the Key Technology Research and Development Program of Zhejiang(2019C01127)the Natural Science Foundation of Zhejiang Province(LQ20E060012).
文摘In order to grasp the particle flow characteristics and energy consumption of industrial fluidized spouted beds,we conduct numerical simulations on the basis of a Computational Particle Fluid Dynamics(CPFD)approach.In particular,the traction model of Wen-Yu-Ergun is used and different inlet conditions are considered.Using a low-speed fluidizing gas,the flow state of the particles is better and the amount of particles accumulated at the bottom of the bed wall becomes smaller.For the same air intake,the energy loss of a circular nozzle is larger than that of a square nozzle.
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 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 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 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 (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.
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.
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.
