Minimum fluidization velocity of large particles in a draft tube airlift reactor

Petrović, Dragan Lj.; Pošarac, Duško; Dudukovic, Aleksandar P.; Skala, Dejan

doi:10.1016/0009-2509(93)80275-u

Cited by 9 publications

(8 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Basically, three flow regimes in three-phase airlift reactors were defined (Fan et al, 1984): the packed bed regime (no suspension of particles and no liquid circulation), the fluidized bed regime (with particle suspension exclusively in the riser and non-zero liquid circulation) and the circulated bed regime (with the solid phase distributed throughout the reactor). Airlift reactors with high crosssectional area ratio A D /A R and with high loading of low density solid particles (typical features of a HCDS) favor the direct change from packed to circulation bed mode (Petrovic et al, 1993). Knowing the magnitude of the circulation velocity during the bioprocess can provide prompt and useful information about the variations of partial processes (affected by hydrodynamics) in individual parts of the reactor.…”

Section: Introductionmentioning

confidence: 99%

Relationships between hydrodynamics and rheology of flocculating yeast suspensions in a high‐cell‐density airlift bioreactor

Klein

Maia

Vicente

et al. 2005

Biotech & Bioengineering

View full text Add to dashboard Cite

In this article a hydrodynamic and rheological analysis of a continuous airlift bioreactor with high-cell-density system is presented. A highly flocculating recombinant strain of Sacharomyces cerevisiae containing genes for lactose transport (lactose permease) and hydrolysis (beta-galactosidase) was exploited to ferment lactose from cheese whey to ethanol. The magnetic particle-tracer method was used to assess the effect of operational conditions (air-flow rate, biomass concentration) on hydrodynamic behavior of an airlift bioreactor during the fermentation process. Measurements of liquid circulation velocity showed the existence of a critical value of biomass concentration at which a dramatic deceleration of net liquid flow appeared with increasing biomass quantity. Rheological analysis revealed exponential increase of viscosity of the yeast floc suspension at the same biomass concentration of about 73 g/dm3 corresponding to 42.8% v/v of solid fraction. These facts have a particular importance for the successful processing of a high-cell-density airlift bioreactor as only a circulated flow regime will be favorable to keep the solid particles in suspension state and evenly distributed throughout the bioreactor.

show abstract

Section: Introductionmentioning

confidence: 99%

Relationships between hydrodynamics and rheology of flocculating yeast suspensions in a high‐cell‐density airlift bioreactor

Klein

Maia

Vicente

et al. 2005

Biotech & Bioengineering

View full text Add to dashboard Cite

show abstract

“…During the present investigation three distinct regimes of solid phase were observed, as described by Fan et al 12 At low gas flow rates, a packed‐bed regime was observed. In general, the solids having low diameters tend to promote coalescence and solids having larger diameters offer good distribution properties 6. In the present investigation polystyrene ( d p = 0.0036 m) and Nylon‐6 ( d p = 0.0035 m) particles were found to promote bubble coalescence.…”

Section: Resultsmentioning

confidence: 52%

“…Immich and Onken2 presented a suitable model for the prediction of minimum gas velocity in an airlift reactor and bubble column. Petrovic et al 6 reported the influence of liquid‐phase properties and geometrical design on ( U sg ) c with large solid particles (high density). Vicente and Teixeira7 reported the ( U sg ) c required for calcium alginate beads (low‐density) in an airlift bioreactor with an enlarged degassing section.…”

Section: Introductionmentioning

confidence: 99%

Critical gas velocity in a three‐phase internal loop airlift reactor with low‐density particles

Muthukumar¹,

Sankari²,

Velan³

2004

J of Chemical Tech & Biotech

View full text Add to dashboard Cite

In the present investigation the effects of the addition of organic additives (propanol, benzoic acid, iso-amyl alcohol and carboxymethyl cellulose) on the critical gas velocity, (U sg ) c , in an internal airlift loop reactor with low-density particles (Nylon-6 and polystyrene) were reported. Whereas the (U sg ) c was reduced by adding the above additives, it increased with solids loading and density of the particles. The draft tube-to-reactor diameter ratio (D E /D) in the range of 0.5-0.6 gave minimum (U sg ) c values. The proposed dimensionless correlation predicted the experimental data well.

show abstract

“…It is interesting to note that the presence of such a high value of p f -likely dominated by the pressure drop at the liquid plate distributor-stabilises the fluidization regime over a broad interval of U G . In fact the fluidization regime was observed also in other works (Petrovic et al, 1993;Olivieri et al, 2003Olivieri et al, , 2004 but over very limited ranges of U G and without plate distributors at the bottom of the draft tube. The fluidized bed regime was typically upperly limited by the stabilisation of the circulation regime.…”

Section: Resultsmentioning

confidence: 67%

A novel three‐phase airlift reactor without circulation of solids

Olivieri

Marzocchella

2010

Can J Chem Eng

View full text Add to dashboard Cite

A novel configuration of a three-phase internal loop airlift reactor is proposed. The draft is divided in two sections: top) gas-liquid contact section; bottom) liquid-solid contact section. Solids particles are fluidized in the bottom section by liquid circulation. The main advantage compared with classic airlift or three-phase fluidized bed is the reduced stress on particles as interference with bubbles is prevented. Experiments with silica sand (325 micronm diameter) were carried out to characterize the hydrodynamics of the airlift. The influence of superficial gas velocity, overall solids hold-up and sparger height were assessed. A theoretical analysis was proposed to derive simple design criteria

show abstract

Minimum fluidization velocity of large particles in a draft tube airlift reactor

Cited by 9 publications

References 11 publications

Relationships between hydrodynamics and rheology of flocculating yeast suspensions in a high‐cell‐density airlift bioreactor

Relationships between hydrodynamics and rheology of flocculating yeast suspensions in a high‐cell‐density airlift bioreactor

Critical gas velocity in a three‐phase internal loop airlift reactor with low‐density particles

A novel three‐phase airlift reactor without circulation of solids

Contact Info

Product

Resources

About