Effect of particle size on flow behavior in fluidized beds

Timsina, Ramesh; Thapa, Rajan Kumar; Moldestad, Britt Margrethe Emilie; Eikeland, Marianne Sørflaten

doi:10.2495/eq-v4-n4-287-297

Cited by 8 publications

(4 citation statements)

References 15 publications

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“…Therefore, early fluidization results in lower minimum fluidization and lower pressure drop for smaller particles. For example, Ramesh Timsina [36] revealed similar information computationally about the pressure drop rise with the particle size increase and vice versa. On the other hand, additional bed expansion was also observed in smaller particles due to the higher uplift of smaller particles for a similar air flow rate.…”

Section: Effect Of Bed Particle Sizementioning

confidence: 89%

Optimizing Design and Operational Parameters for Enhanced Mixing and Hydrodynamics in Bubbling Fluidized Bed Gasifiers: An Experimental and CFD-Based Approach

et al. 2023

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An experimental investigation of hydrodynamics of gas-solid flow is carried out by engaging different designs of air distributor plates. An analysis of three different plates, i.e., perforated, 45° slotted and novel hybrid plate, revealed the difference in pressure drop and minimum fluidization velocities (Umf) for varying input operational variables. Umf is found to be lowest for perforated and highest for 45° slotted plate, whereas pressure drop is found to be highest for 45° slotted plate and lowest for novel hybrid distributor plate. The bubbles rise velocity ratio (Umf,b/Umf,f) is noticed minimum for 45° slotted plate due to relatively larger bubbles originating from the bigger slot openings and maximum for perforated distributor plate owing to smaller bubbles with dominant axial rise. Furthermore, the bed height rise ratio (h/L) is observed as a minimum for perforated distributor and maximum for 45° slotted plate due to larger bubbles through 45° slots rupturing the bed surface, causing more bed expansion. Furthermore, CFD analysis is also carried out to observe the insight flow dynamics using the distributor plates. The simulations use a two-fluid model (TFM) and K-Epsilon turbulence models. CFD model shows promising results in agreement with the experimental results. CFD results revealed that the lower portion enhanced lateral dispersion/mixing of solid particles due to 45° angular openings of an air inlet. In contrast, the perforated plate exhibited a straight upward motion of small air bubbles, causing no radial/lateral mixing. CFD results for the hybrid plate show the mixed axial as well as lateral mixing of solids by revealing velocity distribution; therefore, the novel hybrid plate is found to be an optimum distributor plate due to its lowest pressure drop, adequate Umf, intermediary bed height rise ratio and moderate bubble rise velocity ratio across the bed.

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Section: Effect Of Bed Particle Sizementioning

confidence: 89%

Optimizing Design and Operational Parameters for Enhanced Mixing and Hydrodynamics in Bubbling Fluidized Bed Gasifiers: An Experimental and CFD-Based Approach

et al. 2023

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“…However, this parameter depends on various factors, e.g., the density of the particles and gas respectively, the particle diameter, the porosity of the fixed bed at minimal fluidization, and the sphericity of the particles. Many empirical relations are derived in the literature that attempt to predict the minimal fluidization velocity [26]. However, in practice, 𝑈 𝑚𝑓 is typically higher than the predicted value, as was recently reported for the fluidization of 5 μm silica microspheres.…”

Section: De-agglomeration Of Powder Particlesmentioning

confidence: 98%

Impact-induced generation of single airborne microspheres and the subsequent vacuum-driven assembly of ordered arrays

et al. 2023

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“…In the case of low-grade ore in combination with temperatures above 1123 K, type 3 sticking must be considered [ 29 , 52 , 69 ]. Second, the smaller the particles, the higher the contact area between colliding particles and the possibility for collisions and the smaller the momentum imparted, and thus, the higher the sticking tendency [ 50 , 53 , 56 , 61 , 80 , 81 ]. In addition, Zhong et al found that a broad particle size distribution compared to a narrow particle size distribution shows a higher tendency towards sticking at elevated temperatures due to a lower sintering temperature [ 72 ].…”

Section: Influence Of the Reduction Process On The Fluidization Behaviormentioning

confidence: 99%

Analysis of the Usability of Iron Ore Ultra-Fines for Hydrogen-Based Fluidized Bed Direct Reduction—A Review

Wolfinger¹,

Spreitzer

Schenk

2022

Materials

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This review focuses on the usability of iron ore ultra-fines for hydrogen-based direct reduction. Such technology is driven by the need to lower CO2 emissions and energy consumption for the iron and steel industry. In addition, low operational and capital expenditures and a high oxide yield because of the direct use of ultra-fines can be highlighted. The classification of powders for a fluidized bed are reviewed. Fluid dynamics, such as minimum fluidization velocity, entrainment velocity and fluidized state diagrams are summarized and discussed regarding the processing of iron ore ultra-fines in a fluidized bed. The influence of the reduction process, especially the agglomeration phenomenon sticking, is evaluated. Thus, the sticking determining factors and the solutions to avoid sticking are reviewed and discussed. The essential theoretical considerations and process-relevant issues are provided for the usability of iron ore ultra-fines for hydrogen-based fluidized bed direct reduction.

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Effect of particle size on flow behavior in fluidized beds

Cited by 8 publications

References 15 publications

Optimizing Design and Operational Parameters for Enhanced Mixing and Hydrodynamics in Bubbling Fluidized Bed Gasifiers: An Experimental and CFD-Based Approach

Optimizing Design and Operational Parameters for Enhanced Mixing and Hydrodynamics in Bubbling Fluidized Bed Gasifiers: An Experimental and CFD-Based Approach

Impact-induced generation of single airborne microspheres and the subsequent vacuum-driven assembly of ordered arrays

Analysis of the Usability of Iron Ore Ultra-Fines for Hydrogen-Based Fluidized Bed Direct Reduction—A Review

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