Fluidization Behavior of Mixtures of Nanoparticles in Vibrated Fluidized Beds

2012 ◽  
Vol 550-553 ◽  
pp. 2968-2971 ◽  
Author(s):  
Xi Zhen Liang ◽  
Tao Zhou ◽  
Hao Duan
Keyword(s):  
Fluidized Bed ◽  
Zno Nanoparticles ◽  
Vibration Amplitude ◽  
Fluidized Beds ◽  
Mass Ratio ◽  
Pressure Drops ◽  
Bed Height ◽  
Vibrated Fluidized Bed ◽  
Mixed Nanoparticles

The experiments of mixtures of SiO2 and ZnO nanoparticles in a vibrated fluidized bed were carried out. The effects of ratio of initial static bed height to diameter (h0/D), vibration amplitude (A), frequency (f) and mass ratio of mixed SiO2 and ZnO nanoparticles on the behavior of mixtures of SiO2 and ZnO nanoparticles were studied. The experimental results proved that the fluidization quality of mixed nanoparticles can be enhanced under h0/D=1, A=3.0 mm, f =45Hz, leading to larger bed pressure drops at low superficial gas velocities. The bed height decreases with increase in the mass ratio of ZnO component of the mixture.

Comparative Study of the Hydrodynamic Performance of Shorter and Longer Blades in a Swirling Fluidized Bed

2013 ◽  
Vol 772 ◽  
pp. 560-565 ◽  
Author(s):  
Vinod Kumar Venkiteswaran ◽  
Shaharin Anwar Sulaiman ◽  
Vijay R. Raghavan
Keyword(s):  
Pressure Drop ◽  
Comparative Study ◽  
Fluidized Bed ◽  
Fluidized Beds ◽  
Hydrodynamic Performance ◽  
Industrial Processes ◽  
Blade Length ◽  
Bed Height ◽  
Current Systems

Fluidized beds have been widely used in industrial processes. The inefficiency of current systems provides opportunities for improvement and development of new fluidized bed techniques. The swirling fluidized bed is an outcome of such a quest. The main shortcomings of present day SFB systems are the underutilization of available annular area and massing of bed particles at the periphery of the bed column. In this work the authors report the effect of increasing the annular area in a Swirling Fluidized Bed (SFB) by using longer blades for the distributor and compare it to the conventional blade length of 50 mm. Distributor blades of two different lengths, 50 mm and 100 mm, was used in this work and the bed height was measured with spherical bed particle of three different sizes (4 mm, 5 mm, 6 mm) at varying bed weight and superficial velocity. For a given bed weight, the benefits are achieved through a lower bed pressure drop as well as better quality of fluidization.

The Pressure Drop at Critical Fluidization of Large Particles in Vibrated Fluidization Bed

2012 ◽  
Vol 550-553 ◽  
pp. 2763-2766
Author(s):  
Xue Jun Zhu ◽  
Jun Deng
Keyword(s):  
Pressure Drop ◽  
Fluidized Bed ◽  
Large Particle ◽  
Particle Diameter ◽  
Future Design ◽  
Vibration Strength ◽  
Bed Height ◽  
Large Particles ◽  
Vibrated Fluidized Bed ◽  
Critical Fluidization

The pressure drop at critical fluidization for two-dimensional vibrated fluidized bed(240 mm×80 mm) was studied, with large particle glass beads of average diameters dp of 1.8mm, 2.5mm and 3.2mm.The effect of the vibration strength, the static bed height and the particle diameter on the pressure drop was analyzed. The results of the study show that the pressure drop decreases with the increase of the vibration strength. It plays an even more prominent part with decreases of the static bed height and the particle diameter. The empirical correlation equations to predict the pressure drop was established, and the results of the prediction was compared with the experimental data, the error is in range of ±10%. The results can provide references for future design and research on the vibrated fluidized bed.

scholarly journals Study on Fluidization Characteristics of Magnetically Fluidized Beds for Microfine Particles

Minerals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 61
Author(s):  
Yakun Tian ◽  
Shulei Song ◽  
Xuan Xu ◽  
Xinyu Wei ◽  
Shanwen Yan ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Fluidized Bed ◽  
Magnetic Field Strength ◽  
Fluidized Beds ◽  
Expansion Rate ◽  
Gas Velocity ◽  
Bed Height ◽  
Bed Expansion ◽  
The Magnetic Field

The bed pressure drop, minimum fluidized gas velocity, bed density, and bed expansion rate are important parameters characterizing the fluidization characteristics of gas-solid fluidized beds. By analyzing these parameters, the advantages and disadvantages of the fluidization state can be known. In this study, experiments were conducted to study the fluidization characteristics of a gas-solid magnetically fluidized bed for microfine particles by changing the magnetic field strength, magnetic field addition sequence, and static bed height. The experimental results show that when the magnetic field strength increased from 0 KA/m to 5 KA/m, the minimum fluidized gas velocity of particles increased from 4.42 cm/s to 10.32 cm/s, while the bed pressure drop first increased and then decreased. When the magnetic field strength is less than 3.4 KA/m, the microfine particles in the bed are mainly acted on by the airflow; while when the magnetic field strength is greater than 3.4 KA/m, the microfine particles are mainly dominated by the magnetic field. The magnetic field addition sequence affects the fluidization quality of microfine particles. The fluidized bed with ‘adding magnetic field first’ shows a more stable fluidization state than ‘adding magnetic field later’. Increasing of the static bed height reduces the bed expansion rate. The bed expansion rate is up to 112.5% at a static bed height of h0 = 40 mm and H = 5 KA/m. This will broaden the range of density regulation of a single magnetic particle and lay the advantage of gas-solid magnetically fluidized bed for microfine particles in the field of separation of fine coal.

scholarly journals Removal of Tetracycline from Wastewater Using Circulating Fluidized Bed

2020 ◽  
Vol 21 (3) ◽  
pp. 29-37
Author(s):  
Sabreen Lateef Kareem ◽  
Ahmed A Mohammed
Keyword(s):  
Fluidized Bed ◽  
Zno Nanoparticles ◽  
Circulating Fluidized Bed ◽  
Liquid Velocity ◽  
Particle Density ◽  
Airflow Rate ◽  
Velocity Correlation ◽  
Pistachio Shell ◽  
Bed Height ◽  
Adsorbent Surface

   In this study, the circulating fluidized bed was used to remove the Tetracycline from wastewater utilizing a pistachio shell coated with ZnO nanoparticles. Several parameters including, Tetracycline solution flowrate, initial static bed height, Tetracycline initial concentration and airflow rate were systematically examined to show their effect on the breakthrough curve and the required time to reach the adsorption capacity and thus draw the fully saturated curve of the adsorbent. Results showed that using ZnO nanoparticles will increase the adsorbent surface area and pores and as a result the adsorption increased, also the required time for adsorbent saturation increased and thus the removal efficiency may be achieved at minimum antibiotic flowrate, maximum bed height, higher antibiotic concentration, and higher airflow rate. Also, a minimum fluidization velocity correlation was developed in this study. This correlation was found to be a function of liquid velocity, bed height, particle size, and particle density. The results showed that circulating fluidized bed has a better performance and last more than two hours before the bed biomass exhausted in comparison with traditional fluidized bed.

Research on the Effect of Distributor Aperture Ratio on Fluidization Quality of Vibrated Fluidized Bed

2014 ◽  
Vol 496-500 ◽  
pp. 507-511
Author(s):  
Bin Li ◽  
Si Da Chen ◽  
Xiang Wei Kong ◽  
Shuang Tian Zhang
Keyword(s):  
Experimental Data ◽  
Fluidized Bed ◽  
Material Distribution ◽  
Flow State ◽  
Aperture Ratio ◽  
Vibration Model ◽  
Porous Media Model ◽  
Vibrated Fluidized Bed ◽  
Euler Model

In this paper, combining with the experimental data in the reference, the purpose is to research effect of three different aperture ratios (α=6%, α=9%, α=12%) of distributor on the fluidization quality of vibrated fluidized bed (VFB). Euler-Euler model in Fluent is used to simulate the flow state. User-defined functions are used to define vibration model, and the distributor is simplified based on the porous media model. The results show that the introduction of the distributor can improve uniformity and quality of the fluidization. The aperture ratio of distributor has little influence on material distribution, however, the uniformity of the fluidization is improved with the decrease of the aperture ratio.

CFD Simulation of Fluid Dynamics in a Gas-Solid Jetting Fluidized Bed

2007 ◽  
Vol 5 (1) ◽  
Author(s):  
Qicheng Wang ◽  
Kai Zhang ◽  
Guogang Sun ◽  
Stefano Brandani ◽  
Jinsen Gao ◽  
...  
Keyword(s):  
Fluidized Bed ◽  
Fluidized Beds ◽  
Cfd Simulation ◽  
Fluid Model ◽  
Outer Region ◽  
Solid Material ◽  
Fundamental Parameters ◽  
Bed Height ◽  
Two Fluid Model ◽  
Solid Movement

A thorough understanding of fundamental parameters, such as transient and time-averaged gas and solid velocities, is helpful for designing and manipulating the gas-solid jetting fluidized beds. In this study, a new two-fluid model developed in our group is used to investigate numerically the gas and solid velocities in the gas-solid jetting fluidized beds by adding the user-defined Fortran subroutines in the platform of CFX 4.4, a commercial CFD software package. Simulation is carried out in a two-dimensional fluidized bed 2.0 m high and 0.3 m wide equipped with a nozzle in the centre at the inlet. Resin, belonging to Geldart B Group, is selected as the solid material. The numerical results show that the solid movement is predominantly upward in the center of the bed, whilst it is primarily downward in the outer region of the bed. Particles exchange between these two regions across their neighboring boundary. Gas interchange between the jet and the emulsion phase becomes obvious with the jet evolution. The time-averaged distributions of gas and solid velocities in the bed are greatly influenced by jet gas velocity, and the effect of the static bed height can be ignored. These numerical computations provide helpful information for designing and scaling up the jetting fluidized bed.

Acoustic Field Effects on Minimum Fluidization Velocity in a 3D Fluidized Bed

2012 ◽  
Author(s):  
David R. Escudero ◽  
Theodore J. Heindel
Keyword(s):  
Fluidized Bed ◽  
Fluidized Beds ◽  
High Heat ◽  
Frequency Change ◽  
Process Industries ◽  
Minimum Fluidization Velocity ◽  
Pressure Drops ◽  
Fluidization Velocity ◽  
Minimum Fluidization ◽  
Specific Frequency

Fluidized beds are used in a variety of process industries because they provide uniform temperature distributions, low pressure drops, and high heat/mass rates. Minimum fluidization velocity is an important factor in understanding the hydrodynamic behavior of fluidized beds, and this characteristic may be modified through high frequency (sound) vibrations. The effects caused by sound wave frequency on the minimum fluidization velocity in a 3D fluidized bed are investigated in this study. Experiments are carried out in a 10.2 cm ID cold flow fluidized bed filled with glass beads with material density of 2600 kg/m3, and particles sizes ranging between 212–600 μm. In this study, four different bed height-to-diameter ratios are examined: H/D = 0.5, 1, 1.5, and 2. Moreover, the sound frequency of the loudspeaker used as the acoustic source ranges between 50–200 Hz, with a sound pressure level fixed at 110 dB. Results show that the minimum fluidization velocity is influenced by the frequency change. As the frequency increases, the minimum fluidization velocity decreases until a specific frequency is reached, beyond which the minimum fluidization velocity increases. Thus, acoustic fields provide an improvement in the ease of fluidization of these particles.

scholarly journals Experimental Quantification of the Lateral Mixing of Binary Solids in Bubbling Fluidized Beds

Energies ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7796
Author(s):  
Huanan Li ◽  
Jikai Huang ◽  
Zhigang Liu ◽  
Mingming Lv ◽  
Can Ji
Keyword(s):  
Fluidized Bed ◽  
Fluidized Beds ◽  
Diffusion Mechanism ◽  
Center Line ◽  
Mixing Ratios ◽  
Capacitance Probe ◽  
Lateral Mixing ◽  
Solids Mixing ◽  
And Diffusion

A novel experimental method for the lateral mixing of binary solids in bubbling fluidized beds was developed based on the capacitance probe technique. The evolutions of local mixing ratios in a fluidized bed which can be assumed as one mixing cell were analyzed in detail. The solids mixing within one mixing cell was resolved and the effect of convection and diffusion mechanism on lateral mixing was evaluated individually. The results show that at lower part of the fluidized bed, convection plays a more important role in the mixing process near the wall; meanwhile, diffusion is very important for the mixing around the center line. This is opposite with that at the higher part. A lateral micro dispersion coefficient was proposed to characterize the lateral mixing within the mixing cell and the value is generally between 0.005 and 0.025 m/s. A new mixing index was proposed to evaluate the lateral mixing quality of binary solids. It was found that at the lower part of the fluidized bed, the best mixing is acquired at the half radius, whereas mixing at the center line is the worst. At the higher part, solid mixing is better when increasing the distance from the wall. The influences of gas velocity and static bed on the lateral mixing were also discussed from a microscopic perspective.

Comparative Bio-sorption of Cadmium and Nickel Ions from Aqueous Solution onto Fibers of Date Palm using Fluidized Bed Column

2019 ◽  
Vol 70 (5) ◽  
pp. 1507-1512
Author(s):  
Baker M. Abod ◽  
Ramy Mohamed Jebir Al-Alawy ◽  
Firas Hashim Kamar ◽  
Gheorghe Nechifor
Keyword(s):  
Aqueous Solution ◽  
Heavy Metal ◽  
Metal Ions ◽  
Fluidized Bed ◽  
Removal Efficiency ◽  
Heavy Metal Ions ◽  
Date Palm ◽  
Operating Conditions ◽  
Initial Concentration ◽  
Bed Height

The aim of this study is to use the dry fibers of date palm as low-cost biosorbent for the removal of Cd(II), and Ni(II) ions from aqueous solution by fluidized bed column. The effects of many operating conditions such as superficial velocity, static bed height, and initial concentration on the removal efficiency of metal ions were investigated. FTIR analyses clarified that hydroxyl, amine and carboxyl groups could be very effective for bio-sorption of these heavy metal ions. SEM images showed that dry fibers of date palm have a high porosity and that metal ions can be trapped and sorbed into pores. The results show that a bed height of 6 cm, velocity of 1.1Umf and initial concentration for each heavy metal ions of 50 mg/L are most feasible and give high removal efficiency. The fluidized bed reactor was modeled using ideal plug flow and this model was solved numerically by utilizing the MATLAB software for fitting the measured breakthrough results. The breakthrough curves for metal ions gave the order of bio-sorption capacity as follow: Cd(II)]Ni(II).

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