Critical Assessment of Performance of a Draft Tube Configured in a Spouted Bed for Various Fluid–Particle Properties

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A coupled computational fluid dynamics (CFD)discrete element method (DEM) technique has been adopted to examine the dynamic behavior of particles in a rectangular spouted bed. Eulerian method has been used to solve the Navier−Stokes equation for the gas phase (for the CFD) and Lagrangian method (for the DEM) for the particle phase, where the k−ϵ two-equation turbulence model has been used to capture the effect of gas-phase turbulence. In the present work, we sought to predict the minimum spouting velocity (U ms ) numerically for a fixed bed height and particular particle properties. The effects of the inelastic collision and the friction on translational and rotational dynamics of the particles in spout, annulus, and fountain zones have been brought out with the intensive parametric study. The results reported here would be a way forward for a better understanding of the spouted bed processing where translational and rotational dynamics of particles play a key role.

Section: Resultssupporting

confidence: 82%

Section: ■ Results and Discussionmentioning

confidence: 99%

Numerical Studies on Particle Dynamics in a Spouted Bed

Raman

Mollick

Goswami

2021

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“…In our recent studies, it is found that H e and D dt are the most influential design parameters to determine U ms . Therefore, for a better comparison, H e has been kept constant for all the DTSB.…”

Section: Resultsmentioning

confidence: 98%

Novel Porous Draft Tube To Manipulate Fluid Throughput from Spout to Annulus in a Spouted Bed

Mollick

Pandit

Mukherjee

et al. 2020

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A porous draft tube (DT) with suitable converging and diverging angles having varying porosity is newly introduced in a spouted bed (SB) for manipulating the fluid exchange rate from the spout to the annular region and thus to enhance the fluid residence time in the annular region. A comparative study of the exchange of the spouting gas (argon) into the bed of zirconia and glass beads in a conventional, nonporous, and porous DT-fitted SB with different converging and diverging angles of 9 and 18° is reported here. Computational fluid dynamics simulation using “Fluent, v-15.0” was performed to identify hydrodynamic phenomena inside the DT as well as in the bed for converging and diverging porous DT designs. Experimental findings for the efficient combination of converging and diverging angles have been compared with the simulation results.

“…Mollick et al 37 conducted a study to evaluate the performance of a draft tube in a spouted bed compared to that of a conventional spouted bed for various processes. They carefully determined that there is always a critical combination of the draft tube's diameter and the entrainment height below it, which determines the operational efficiency.…”

Section: T H Imentioning

confidence: 99%

“…Altzibar et al , conducted a study to measure particle cycle times (average, maximum, and minimum) in a draft tube conical spouted bed under various geometric factors of the contactor (angle and gas inlet diameter), draft tube (diameter, height of the entrainment zone, and width of the faces), and different operating conditions (particle density). Their study explored the impacts of the draft tube type and other factors related to the contactor, draft tube, and particle system.…”

Section: Introductionmentioning

confidence: 99%

Comprehensive CFD-TFM Simulation of Drying in Spouted Beds with Draft Tubes

Naghdi,

Arabi,

Molaei Dehkordi

2024

In this article, simulation runs were conducted to predict the drying evolution of sand in conical spouted beds with a nonporous draft tube using the Eulerian−Eulerian approach. The simulation results were validated against experimental data reported in the literature, and good agreement was achieved. In addition, the effects of various operating and design parameters, such as superficial gas velocity, inlet air temperature, the draft tube's length and diameter, and the solid phase's initial moisture content on the sand drying, were carefully investigated. It was found that the operating temperature and superficial gas velocity are the most essential parameters for improving the drying process and reducing the drying time of the sand particles. In addition, the choice of drag model, restitution coefficient, and specularity coefficient were found to have no significant influence on the drying time of the solid phase. Moreover, increasing the particles' diameter and initial moisture content leads to longer drying times, whereas increasing the conical bed angle prolongs the drying time for the solid particles. On the other hand, increasing the nozzle diameter and entrance length decreases the drying time of the solid phase. Furthermore, reducing the diameter and length of the draft tube also decreased the drying time.