Solids flow mapping in a gas–solid riser: Mean holdup and velocity fields

Bhusarapu, Satish; Al‐Dahhan, Muthanna H.; Duduković, Milorad P.

doi:10.1016/j.powtec.2006.01.013

Cited by 101 publications

(114 citation statements)

References 57 publications

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“…This is to be expected as the turbulence in riser flows is proved to be anisotropic [3]. The anisotropy could be attributed to the length to diameter ratio of the riser that is much larger than unity, implying that the axial a) b) measurements in riser flows [3][4]8]. This observation implies that the instantaneous radial and azimuthal particle velocities exhibit a rather broad distribution of slightly positive and slightly negative values, which result in very low mean values upon averaging.…”

Section: Resultsmentioning

confidence: 82%

“…Larger velocity fluctuations in one direction correspond to an anisotropic flow. This is to be expected as the turbulence in riser flows is proved to be anisotropic [3]. The anisotropy could be attributed to the length to diameter ratio of the riser that is much larger than unity, implying that the axial a) b) measurements in riser flows [3][4]8].…”

Section: Resultsmentioning

confidence: 88%

“…This observation is in agreement with Van den Moortel et al [8], who also studied a dilute riser flow. However, Bhusarapu et al [3] observe the opposite behavior, when comparing the Dilute Phase Transport and the Fast Fluidization regimes. In the latter work, it is noted that under dilute flow conditions, two competing mechanisms affect the observed fluctuations.…”

Section: Resultsmentioning

confidence: 97%

“…The development of theoretical models and empirical equations to simulate the riser flow suffer from this lack of relevant experimental data, e.g. in view of model validation and refinement [3][4]. Furthermore, the majority of the available experimental data for two-phase riser flow provides at its best two simultaneously measured solids velocity components.…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, the majority of the available experimental data for two-phase riser flow provides at its best two simultaneously measured solids velocity components. Two-dimensional experimental data are insufficient to validate and refine existing or develop new accurate computational flow models for an in nature 3-D flow [3]. Therefore, precise experimental data providing coincident measurements of the three components of the solids velocity vectors are needed to gain insight into the 3-D flow characteristics along the entire riser height.…”

Section: Introductionmentioning

confidence: 99%

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Three-component solids velocity measurements in the middle section of a riser

Pantzali

Bayon

Heynderickx

et al. 2013

Chemical Engineering Science

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Coincident three-component experiments are conducted in a 8.7-m-high cylindrical riser (internal diameter 0.10 m) of a Pilot-Scale Cold-Flow Circulating Fluidized Bed set-up using two LDA probes. At heights close to the solids inlet, the flow is highly disturbed due to the asymmetrical position of both the air and solids inlets. A fully developed parabolic axial solids velocity field is observed at a height of 2.5 m. The radial and azimuthal solids velocity components are significantly smaller than the axial one and are close to zero. The velocity fluctuations in the flow direction are larger than in the other directions, showing that the flow is anisotropic. However, the radial and azimuthal velocity fluctuations are higher than the corresponding mean velocities. All fluctuating velocities are decreasing significantly with increasing riser height, i.e. as the flow becomes more developed. No average down-flow of solids is recorded, not even close to the wall, probably due to the very high dilution (ε s <0.2%) used in the presented work. The measured turbulent kinetic energy indicates that the flow is dominated by wall-particle rather than intra-particle collisions. The acquired data can be useful for validation of riser simulations.

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Section: Resultsmentioning

confidence: 82%

Section: Resultsmentioning

confidence: 88%

Section: Resultsmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Three-component solids velocity measurements in the middle section of a riser

Pantzali

Bayon

Heynderickx

et al. 2013

Chemical Engineering Science

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Enabling Process Innovations via Mastering Multiphase Flows: Gas–Solid Processes

Utikar¹,

Pareek²

2022

Multiphase Flows for Process Industries

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Study of the ability of multiphase continuum models to predict core‐annulus flow

2007

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in Wiley InterScience (www.interscience.wiley.com).We use the well established core-annulus flow regime as a numerical benchmark to evaluate the sensitivity of gas-solids continuum models and boundary conditions to model formalisms and parameters. By using transient, 1D, grid-independent numerical solutions, we avoid the use of speculative closure terms and show that the kinetic theory of granular flow (KTGF) is sufficient to model core-annulus regime. That regime arises in the time-average solution as a consequence of the fluctuating motion of regions with high solids concentration. These fluctuations are most sensitive to the gravitational acceleration (g) and granular energy dissipation terms. The fluctuation frequency is a ffiffi ffi g p . The effect of fluctuations is so dominant that decreasing the restitution coefficient (KTGF parameter) actually increases the average granular temperature. The wall boundary conditions for solids momentum and granular energy equations dictate the core-annulus flow regime. They must cause a net dissipation of granular energy at the wall for predicting that regime.

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Solids flow mapping in a gas–solid riser: Mean holdup and velocity fields

Cited by 101 publications

References 57 publications

Three-component solids velocity measurements in the middle section of a riser

Three-component solids velocity measurements in the middle section of a riser

Enabling Process Innovations via Mastering Multiphase Flows: Gas–Solid Processes

Study of the ability of multiphase continuum models to predict core‐annulus flow

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