Effect of particle mixing on the hydrodynamics of fluidized bed of nanoparticles

Ali, Syed Sadiq; Asif, Mohammad

doi:10.1016/j.powtec.2017.01.041

Cited by 20 publications

(16 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In order to improve the fluidization hydrodynamics of solids that exhibit poor fluidization behavior, various assisted fluidization techniques have been proposed in the literature [24][25][26][27][28][29][30][31][32][33][34]. These techniques are generally implemented in conjunction with conventional fluidization to provide additional energy to the fluidized bed for overcoming interparticle forces that cause powder cohesiveness and other nonhomogeneities observed during fluidization.…”

Section: Introductionmentioning

confidence: 99%

“…Another simple yet cost-effective assisted fluidization technique is the addition of external inert particles. A carefully chosen sample of external particles with appropriate physical properties, when mixed with resident solid phase of the fluidized bed, has been found to significantly enhance fluidization hydrodynamics [23,30,31,46]. For example, the addition of Group A particles to a bed of nanopowder was found to promote deagglomeration and suppress the phenomenon of hysteresis [31,46].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Enhancement of CO2 Removal Efficacy of Fluidized Bed Using Particle Mixing

2018

Self Cite

View full text Add to dashboard Cite

The present study proposes a cost-effective assisted fluidization technique of particle mixing to improve the carbon capture effectiveness of a fluidized bed containing fine adsorbent powder. Using activated carbon as the adsorbent, we mixed external particle of Geldart group B classification in different fractions to examine the effectiveness of the proposed strategy of particle mixing. Four different particle-mixing cases were considered by varying the amount of added particle—0, 5, 10, and 30 wt %—on external particle-free basis. The inlet flow of the nitrogen was fixed, while two different flows of carbon dioxide were used. The adsorption experiment consisted of a three step procedure comprising purging using pure nitrogen, followed by adsorption with fixed inlet CO2 concentration, and finally the desorption step. Inlet flows of both nitrogen and CO2 were separately controlled using electronic mass flow controllers with the help of data acquisition system (DAQ). The CO2 breakthrough was carefully monitored using the CO2/O2 analyzer, whose analog output was recorded using the DAQ. Best results were obtained with 10% external particles. This is in conformity with the results of our previous study of bed hydrodynamics, which pointed to clear improvement in the fluidization behavior with particle mixing.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Enhancement of CO2 Removal Efficacy of Fluidized Bed Using Particle Mixing

2018

Self Cite

View full text Add to dashboard Cite

show abstract

“…Its primary size was 12 nm and it had a surface area of 200 ± 25 m 2 /g. However, due to agglomeration, dry-particle size analysis yielded a wide size distribution, ranging from 2 to 100 µm with a Sauter mean diameter of 20 µm [30]. Though its true density was 2200 kg/m 3 , the tapped density was found to be only 50 kg/m 3 , which indicated the highly porous nature of the bed with a void fraction of 0.98.…”

Section: Introductionmentioning

confidence: 97%

“…In addition to being energy intensive, these techniques are also difficult to implement on an industrial scale. Some assisted fluidization techniques, which do not require a direct supply of energy, include tapered and inclined fluidized beds [23,24], fluid flow pulsation [8,[25][26][27][28][29], and inert particle mixing [3,4,[30][31][32][33][34]. In some cases, a combination of two assisted fluidization techniques has also been used to further enhance the performance of fluidized beds [35][36][37][38].…”

mentioning

confidence: 99%

Nanopowder Fluidization Using the Combined Assisted Fluidization Techniques of Particle Mixing and Flow Pulsation

et al. 2019

Self Cite

View full text Add to dashboard Cite

In the present study, we report the fluidization behavior of ultrafine nanopowder using the assisted fluidization technique of particle mixing, which was further superimposed with the pulsation of the inlet gas flow to the fluidized bed. The powder selected in the present study was hydrophilic nanosilica, which shows strong agglomeration behavior leading to poor fluidization hydrodynamics. For particle mixing, small proportions of inert particles of Geldart group A classification were used. The inlet gas flow to the fluidized bed was pulsed with a square wave of frequency 0.1 Hz with the help of a solenoid valve controlled using the data acquisition system (DAQ). In addition to the gas flow rate to the fluidized bed, pressure transients were carefully monitored using sensitive pressure transducers connected to the DAQ. Our results indicate a substantial reduction in the effective agglomerate size as a result of the simultaneous implementation of the assisted fluidization techniques of particle mixing and flow pulsation. Appl. Sci. 2019, 9, 572 2 of 11 devices and configurations, such as ultrasonic comminution devices [15], high-shear mixers [16], mechanical vibrations [17], acoustic vibrations [18-20], and oscillating magnetic particles under a magnetic field [21,22]. In addition to being energy intensive, these techniques are also difficult to implement on an industrial scale. Some assisted fluidization techniques, which do not require a direct supply of energy, include tapered and inclined fluidized beds [23,24], fluid flow pulsation [8,[25][26][27][28][29], and inert particle mixing [3,4,[30][31][32][33][34]. In some cases, a combination of two assisted fluidization techniques has also been used to further enhance the performance of fluidized beds [35][36][37][38]. Levy and Celeste [6] studied the hydrodynamics of fine powders with sizes ranging from 12 nm to 15 µm in bubbling fluidized beds. They used the combined assisted techniques of horizontal mechanical vibrations and acoustic vibrations to enhance the fluidization behavior. The combined technique was found to be more effective than mechanical vibrations alone. Both the agglomerate diameter and the minimum fluidization velocities were substantially reduced by the application of combined assisted fluidization techniques. Liu and Guo [39] studied the effect of acoustic and magnetic vibrations on the hydrodynamics of fluidized beds containing fine powders ranging from 5 nm to 45 µm. The combination of assisted techniques helped to reduce the minimum fluidization velocity to a greater extent as compared to the case when these techniques were used separately. In the present study, a combination of two assisted fluidization techniques, namely, particle mixing and flow pulsation, is used to improve the fluidization behavior of a bed of nanopowder.In the assisted fluidization technique of particle mixing, the premixing of external particles with nanoparticles improves the bed homogeneity and promotes deagglomeration, and thus enhances the fluidization qualit...

show abstract

“…Strategies for improving fluidization hydrodynamics of powders are often known as assisted fluidization techniques. Examples are acoustics [9][10][11][12][13][14], particle-mixing [15][16][17][18][19][20], flow pulsations [21][22][23][24][25][26][27][28][29], and mechanical vibrations [30][31][32][33][34]. In some cases, a combination of two assisted fluidization technique has been suggested [20,35].…”

Section: Introductionmentioning

confidence: 99%

Deagglomeration of Ultrafine Hydrophilic Nanopowder Using Low-Frequency Pulsed Fluidization

et al. 2020

Self Cite

View full text Add to dashboard Cite

Low-frequency flow pulsations were utilized to improve the hydrodynamics of the fluidized bed of hydrophilic ultrafine nanosilica powder with strong agglomeration behavior. A gradual fluidization of unassisted fluidized bed through stepwise velocity change was carried out over a wide range of velocities followed by a gradual defluidization process. Bed dynamics in different regions of the fluidized bed were carefully monitored using fast and sensitive pressure transducers. Next, 0.05-Hz square-wave flow pulsation was introduced, and the fluidization behavior of the pulsed fluidized bed was rigorously characterized to delineate its effect on the bed hydrodynamics by comparing it with one of the unassisted fluidized bed. Flow pulsations caused a substantial decrease in minimum fluidization velocity and effective agglomerate diameter. The frequencies and amplitudes of various events in different fluidized bed regions were determined by performing frequency domain analysis on real-time bed transient data. The pulsations and their effects promoted deagglomeration and improved homogeneity of the pulsed fluidized bed.

show abstract

Effect of particle mixing on the hydrodynamics of fluidized bed of nanoparticles

Cited by 20 publications

References 34 publications

Enhancement of CO2 Removal Efficacy of Fluidized Bed Using Particle Mixing

Enhancement of CO2 Removal Efficacy of Fluidized Bed Using Particle Mixing

Nanopowder Fluidization Using the Combined Assisted Fluidization Techniques of Particle Mixing and Flow Pulsation

Deagglomeration of Ultrafine Hydrophilic Nanopowder Using Low-Frequency Pulsed Fluidization

Contact Info

Product

Resources

About