Hydrodynamics of Pulsed Fluidized Bed of Ultrafine Powder: Fully Collapsing Fluidized Bed
The processing of fine and ultrafine particles using a fluidized bed is challenging in view of their unpredictable hydrodynamic behavior due to interparticle forces. The use of assisted fluidization techniques in such cases can be effective in improving the bed hydrodynamics. This work investigates...
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doaj-6249e9293c6741c9be058ec4276444022020-11-25T02:58:03ZengMDPI AGProcesses2227-97172020-07-01880780710.3390/pr8070807Hydrodynamics of Pulsed Fluidized Bed of Ultrafine Powder: Fully Collapsing Fluidized BedMohammad Asif0Ebrahim H. Al-Ghurabi1Abdelhamid Ajbar2Nadavala Siva Kumar3Department of Chemical Engineering, King Saud University, PO Box 800, Riyadh 11421, Saudi ArabiaDepartment of Chemical Engineering, King Saud University, PO Box 800, Riyadh 11421, Saudi ArabiaDepartment of Chemical Engineering, King Saud University, PO Box 800, Riyadh 11421, Saudi ArabiaDepartment of Chemical Engineering, King Saud University, PO Box 800, Riyadh 11421, Saudi ArabiaThe processing of fine and ultrafine particles using a fluidized bed is challenging in view of their unpredictable hydrodynamic behavior due to interparticle forces. The use of assisted fluidization techniques in such cases can be effective in improving the bed hydrodynamics. This work investigates the dynamics of pulsed fluidized bed of ultrafine nanosilica subjected to square-wave flow pulsations. The pulse duration used in this study is sufficient to allow the complete collapse of the pulsed fluidized bed between two consecutive flow pulsations. The proposed pulsation strategy is carefully implemented using electronic mass flow controllers with the help of analog output signals from data acquisition system. Given that the different regions of the fluidized bed exhibit varying dynamics, which together contribute to overall bed dynamics, the bed transients in the upper, central, and lower regions of the fluidized bed are monitored using several sensitive pressure transducers located along the height of the bed. The effect of the flow pulsation on the hydrodynamics of the fluidized bed is rigorously characterized. A significant reduction in the minimum fluidization velocity was obtained and an increase in the bed homogeneity was observed due to flow pulsations. The frequency domain analysis of the signals clearly delineated the frequency of the various events occurring during the fluidization.https://www.mdpi.com/2227-9717/8/7/807pulsed fluidized bedultrafine powderbed dynamicsflow pulsationnanoagglomerates |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Mohammad Asif Ebrahim H. Al-Ghurabi Abdelhamid Ajbar Nadavala Siva Kumar |
spellingShingle |
Mohammad Asif Ebrahim H. Al-Ghurabi Abdelhamid Ajbar Nadavala Siva Kumar Hydrodynamics of Pulsed Fluidized Bed of Ultrafine Powder: Fully Collapsing Fluidized Bed Processes pulsed fluidized bed ultrafine powder bed dynamics flow pulsation nanoagglomerates |
author_facet |
Mohammad Asif Ebrahim H. Al-Ghurabi Abdelhamid Ajbar Nadavala Siva Kumar |
author_sort |
Mohammad Asif |
title |
Hydrodynamics of Pulsed Fluidized Bed of Ultrafine Powder: Fully Collapsing Fluidized Bed |
title_short |
Hydrodynamics of Pulsed Fluidized Bed of Ultrafine Powder: Fully Collapsing Fluidized Bed |
title_full |
Hydrodynamics of Pulsed Fluidized Bed of Ultrafine Powder: Fully Collapsing Fluidized Bed |
title_fullStr |
Hydrodynamics of Pulsed Fluidized Bed of Ultrafine Powder: Fully Collapsing Fluidized Bed |
title_full_unstemmed |
Hydrodynamics of Pulsed Fluidized Bed of Ultrafine Powder: Fully Collapsing Fluidized Bed |
title_sort |
hydrodynamics of pulsed fluidized bed of ultrafine powder: fully collapsing fluidized bed |
publisher |
MDPI AG |
series |
Processes |
issn |
2227-9717 |
publishDate |
2020-07-01 |
description |
The processing of fine and ultrafine particles using a fluidized bed is challenging in view of their unpredictable hydrodynamic behavior due to interparticle forces. The use of assisted fluidization techniques in such cases can be effective in improving the bed hydrodynamics. This work investigates the dynamics of pulsed fluidized bed of ultrafine nanosilica subjected to square-wave flow pulsations. The pulse duration used in this study is sufficient to allow the complete collapse of the pulsed fluidized bed between two consecutive flow pulsations. The proposed pulsation strategy is carefully implemented using electronic mass flow controllers with the help of analog output signals from data acquisition system. Given that the different regions of the fluidized bed exhibit varying dynamics, which together contribute to overall bed dynamics, the bed transients in the upper, central, and lower regions of the fluidized bed are monitored using several sensitive pressure transducers located along the height of the bed. The effect of the flow pulsation on the hydrodynamics of the fluidized bed is rigorously characterized. A significant reduction in the minimum fluidization velocity was obtained and an increase in the bed homogeneity was observed due to flow pulsations. The frequency domain analysis of the signals clearly delineated the frequency of the various events occurring during the fluidization. |
topic |
pulsed fluidized bed ultrafine powder bed dynamics flow pulsation nanoagglomerates |
url |
https://www.mdpi.com/2227-9717/8/7/807 |
work_keys_str_mv |
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