Experimentally validated numerical study of gas-solid vortex unit hydrodynamics

Niyogi, Kaustav; Torregrosa, María M.; Pantzali, Maria N.; Heynderickx, Geraldine; Marin, Guy

doi:10.1016/j.powtec.2016.10.049

Cited by 26 publications

(23 citation statements)

References 42 publications

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“…The breaking of the densely packed structure causes a pressure rise, as observed in zone II. Upon further addition of particles the pressure drops again because of a combined effect of a new semiperiodic bed structure being brought about and the change in the reduction size of backflow region …”

Section: Resultsmentioning

confidence: 99%

“…The simulations are performed using a sectional geometry of the Unit‐1. Previous works have demonstrated the possibility of using a sectional pie geometry of the vortex unit to mimic the performance of the entire unit, thus reducing the computational costs of these simulations . The chosen mesh contains one gas inlet slot at the center of the geometry.…”

Section: Experimental Setupsmentioning

confidence: 99%

“…Gas flow behavior in gas–solid units is substantially different as compared to the single phase behavior discussed above. Most of the momentum in the gas is transferred to the solids, thus almost immediately reducing the gas velocity by 70–80% of its value in gas‐only flow . Upon exiting the solids bed, in the freeboard, the gas will almost immediately exit the unit via the central exhaust.…”

Section: Introductionmentioning

confidence: 99%

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An experimental and numerical study of the suppression of jets, counterflow, and backflow in vortex units

et al. 2019

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Vortex units are commonly considered for various single and multiphase applications due to their process intensification capabilities. The transition from gas-only flow to gas-solid flow remains largely unexplored nonetheless. During this transition, primary flow phenomenon, jets, and secondary flow phenomena, counterflow and backflow, are substantially reduced, before a rotating solids bed is established.This transitional flow regime is referred to as the vortex suppression regime. In the present work, this flow transition is identified and validated through experimental and computational studies in two vortex units with a scale differing by a factor of 2, using spherical aluminum and alumina particles. This experimental data supports the proposed theoretical particle monolayer solids loading that allows estimation of vortex suppression regime solids capacity for any vortex unit. It is shown that the vortex suppression regime is established at a solids loading theoretically corresponding to a monolayer being formed in the unit for 1g-Geldart D-and 1g-Geldart B-type particles. The model closely agrees with experimental vortex suppression range for both aluminum and alumina particles. The model, as well as the experimental data, shows that the flow suppression regime depends on unit dimensions, particle diameter, and particle density but is independent of gas flow rate.This combined study, based on experimental and computational data and on a theoretical model, reveals the vortex suppression to be one of the basic operational parameters to study flow in a vortex unit and that a simple monolayer model allows to estimate the needed solids loading for any vortex device to induce this flow transition. K E Y W O R D Sgas-solid vortex reactor, gas-solid vortex units, monolayer model, process intensification, vortex suppression regime Abbreviations: GSVR, gas-solid vortex reactor; GSVU, gas-solid vortex unit; GVU, gasvortex unit; HDPE, high density polyethylene.

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Section: Resultsmentioning

confidence: 99%

Section: Experimental Setupsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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An experimental and numerical study of the suppression of jets, counterflow, and backflow in vortex units

et al. 2019

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“…Adding an external energy source can improve the performance of the mixers or the devices, but at the same time increases the energy consumption. Until today, vortex units have been mainly applied for gas–solid applications 8‐18 . If the GLVR is used in micromixing applications, it is a type of unit that is situated between the active and passive mixers, or static and rotational reactors for two reasons: (a) a GLVR creates a gas–liquid system where the gas phase can be regarded as an external energy input; (b) a strong vortex (rotating) flow is created in the GLVR, but in a static geometry.…”

Section: Introductionmentioning

confidence: 99%

Micromixing in a gas–liquid vortex reactor

et al. 2021

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The gas–liquid vortex reactor (GLVR) has substantial process intensification potential for multiphase processes. Essential in this respect is the micromixing efficiency, which is of great importance in fast reaction systems such as crystallization, polymerization, and synthesis of nanomaterials. By creating a vortex flow and taking advantage of the centrifugal force field, the liquid micromixing process can be intensified in the GLVR. Results show that introducing a liquid into a gas‐only vortex unit results in suppression of primary and secondary gas flow. The Villermaux–Dushman protocol is applied to study the effects of the gas flow rate, liquid flow rate, and liquid viscosity based on a segregation index. Based on the incorporation model and reaction kinetics, the micromixing time of the GLVR is determined to be in the range of 10−4 ~ 10−3 s, which is comparable to the highly efficient rotating packed bed and substantially better than a static mixer.

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“…This arrangement allows intensification of the bed performance [21,22], i.e., intensification of heat and mass transfer [20,21] as well as improved mixing [21,23,24]. This is due to the vortex flow pattern and is characteristic for all vortex reactors [24][25][26][27]. In terms of the reactor's performance it allows increased throughput (increased productivity) with reduced residence times [28].…”

Section: Toroidal Bed Reactormentioning

confidence: 99%

Drying of Lignite of Various Origins in a Pilot Scale Toroidal Fluidized Bed Dryer using Low Quality Heat

et al. 2019

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An experimental study was carried out for lignites of different places of origin, i.e., Poland, Greece, Romania and Australia, using a toroidal bed dryer. The effect of the temperature on the drying efficiency, including the loss of moisture content over time under fixed drying conditions was the subject of the investigation. The main goal was to confirm the possibility of the use of a toroidal bed as a base for a drying system that could utilize low quality heat from sources such as flue gases from a boiler and determine the optimum parameters for such a system. The conducted study has conclusively proven the feasibility of the use of low temperature heat sources for drying lignite in a toroidal bed. A moisture content of 20% could be achieved for most of the tested lignites, using the toroidal bed, with reasonably short residence times (approx. 30 min) and an air temperature as low as 60 °C. Moreover, the change of the particle size distribution, to some degree, affected the final moisture content due to the entrainment of wet, fine particles. The study also determined that the in-bed attrition of the particles is partially responsible for the generation of fines.

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Experimentally validated numerical study of gas-solid vortex unit hydrodynamics

Cited by 26 publications

References 42 publications

An experimental and numerical study of the suppression of jets, counterflow, and backflow in vortex units

An experimental and numerical study of the suppression of jets, counterflow, and backflow in vortex units

Micromixing in a gas–liquid vortex reactor

Drying of Lignite of Various Origins in a Pilot Scale Toroidal Fluidized Bed Dryer using Low Quality Heat

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