Correlating parameters for axial dispersion in liquid fluidized systems

Krishnaswamy, P.R.; Ganapathy, R.; Shemilt, L. W.

doi:10.1002/cjce.5450560504

Cited by 27 publications

(6 citation statements)

References 12 publications

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“…It slightly underestimated the values obtained in the present experimental investigation. On the cther hand, the 0-oBed predictions of the Krishnaswamy et al (1978) correlation are found to be poor at low flow rates.…”

Section: Aiche Journalmentioning

confidence: 91%

“…They pointed out that the extent of axial liquid dispersion in a fluidized bed of low-density solid particles is significantly less than that of high-density solid particles. Consequently, existing correlations (Chung and Wen, 1968;Krishnaswamy et al, 1978) for the prediction of the dispersion coefficients in a fluidized bed containing high-density solid particles cannot be extended to the low-density operating regime. Similar conclusions were drawn by Kikuchi et al (1984) who considered very low-density polystyrene particle in their study of axial liquid dispersion in liquid fluidized beds.…”

Section: Introductionmentioning

confidence: 96%

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Distributor effects in liquid fluidized beds of low‐density particles

1991

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The effect offlow nonuniformities existing near the distributor of a liquid fluidized bed containing very low-density particles (p, = 1.05 g/mL) has been investigated experimentally. Immobilized enzyme or cell bioreactors operated as liquid fluidized beds often employ low-density particles as the support matrix containing the immobilized biocatalyst. With poorly designed multihole distributors, dead zones can be created which seriously undermine the performance of the bioreactor due to the lack of nutrients. Design guidelines are provided for distributors to minimize the inlet flow disturbances, and hence eliminate potential distributor region problems. As a result, the dispersion model, which is normally used for design purposes, can then be applied.

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Section: Aiche Journalmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 96%

Distributor effects in liquid fluidized beds of low‐density particles

1991

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“…Voluminous reports are available in the literature wherein empirical correlation has been proposed to estimate axial dispersion coefficient as a function of physical properties of solid and liquid phases, and superficial liquid velocity for a given geometrical parameters (Chung and Wen 1968;Krishnaswamy and Shemilt 1972;Krishnaswamy, Ganapathy, and Shemilt 1978;Kikuchi et al1984;Tan and Krishnaswamy 1989;Tang and Fan 1990;Kalaga et al 2012). However, there is no correlation available in the literature to predict axial dispersion coefficient in multistage column with due consideration of solid circulation rate.…”

Section: Correlation For Dispersion Coefficient In Multistage Slcfbmentioning

confidence: 99%

Novel multistage solid–liquid circulating fluidized bed: liquid phase mixing characteristics

Thombare

Kalaga

Bankar

et al. 2019

Particulate Science and Technology

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Liquid phase axial mixing studies have been carried out in the novel solid-liquid circulating fluidized bed (SLCFB). The SLCFB primarily consists of a single multistage column (having an inner diameter of 100 mm i.d. and length of 1.40 m) which is divided into two sections wherein both the steps of utilization, namely loading (e.g., adsorption and catalytic reaction) and regeneration of solid phase, can be carried out simultaneously in continuous mode. Weak base anion exchange resin was used as the solid phase, whereas water as the fluidizing medium. The effects of physical properties of solid phase, superficial liquid velocity, and solid circulation rate on liquid phase axial dispersion coefficient were investigated. The dispersion coefficient increases monotonically with an increase in the size of solid particle, superficial liquid velocity, and solid circulation rate. The axial dispersion model (ADM) was used to model experimental residence time distribution (RTD) data. A good agreement was found between ADM predictions and the experimental measurements. A unified correlation has also been proposed to determine dispersion coefficient as a function of physical properties of solid and liquid phases, superficial liquid velocity, and solid circulation rate based on all previous and present experimental data on multistage SLCFB.

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“…'; 1 < Re, < 200 EPC = (0.20 + 0.011Re0.48) x ( R e~/ R e ) (28) An improved correlation for the axial dispersion coefficient in liquid fluidized beds was given by Krishnaswamy et al":…”

Section: Hydrodynamicsmentioning

confidence: 99%

Countercurrent multistage fluidized bed reactor for immobilized biocatalysts: I. Modeling and simulation

Vos¹,

Groen²,

Potters³

et al. 1990

Biotech & Bioengineering

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For the application of immobilized enzymes, fixed bed reactors are used almost exclusively. Fixed bed reactors have specific disadvantages, especially for processes with a deactivating catalyst. Therefore, we have studied a novel reactor type with continuous transport of the immobilized biocatalyst. Flow of biocatalyst is countercurrent to the substrate solution. Because of a stagewise reactor design, back-mixing of biocatalyst is very limited and transport is nearly plug flow. The reactor operates at a constant flow rate and conversion, due to constant holdup of catalytic activity. The reactor performance is compared with a configuration of fixed bed reactors. For reactions in the first-order regime, enzyme requirements in this new reactor are slightly less than for fixed bed processes. The multistage fluidized bed appears to be an attractive reactor design to use biocatalyst to a low residual activity. However, nonuniformity of the particles might affect plug flow transport of the biocatalyst. A laboratory scale reactor and experiments are described in Part II(1) of this series. Hydrodynamic design aspects of a multistage fluidized bed are discussed in more detail in Part III.(2).

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Correlating parameters for axial dispersion in liquid fluidized systems

Cited by 27 publications

References 12 publications

Distributor effects in liquid fluidized beds of low‐density particles

Distributor effects in liquid fluidized beds of low‐density particles

Novel multistage solid–liquid circulating fluidized bed: liquid phase mixing characteristics

Countercurrent multistage fluidized bed reactor for immobilized biocatalysts: I. Modeling and simulation

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