Influence of geometry and angular velocity on performance of a rotating disk filter

Bouzerar, Roger; Jaffrin, Michel Y.; Ding, Luhui; Paullier, Patrick

doi:10.1002/aic.690460206

Cited by 88 publications

(52 citation statements)

References 15 publications

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“…Correlations obtained for max and memb through multiple linear regression of all CFD runs shown in Table I (correlation: R (and, thus, the same h/R), but different (runs 4 and 13), also present quite different values of shear stress. Thus, the present results are in agreement with those of Bouzerar et al (2000) and Schiele (1979), who investigated rotating disk filters and proposed an equation for the shear stress at the membrane surface, where the only geometric variable involved is the rotor radius.…”

Section: Influence Of Geometric and Operational Variables On Shear-stsupporting

confidence: 94%

CFD‐aided design of a dynamic filter for mammalian cell separation

Castilho

Anspach

2003

Biotech & Bioengineering

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In the present work, a rotating disk filter was designed for mammalian cell separation with the aim of avoiding both cell damage and membrane fouling. Different geometric and operational variables of the rotating disk filter were studied using computational fluid dynamics (CFD) by varying rotor radius, rotor angle, membrane-rotor distance, and angular velocity. The combinations of these variables followed a statistical design, so that an analysis of the CFD results provided correlations describing the average shear stress on the membrane surface and the maximum shear stress in the whole module as a function of the variables studied. Based on these correlations, and on the shear resistance levels of Chinese hamster ovary (CHO) and baby hamster kidney (BHK) cell lines, which were investigated using a cone-and-plate viscosimeter, it was possible to determine the geometry and angular velocity that would minimize both cell damage and membrane fouling. After construction, the filter was tested in filtration experiments at increasing permeate fluxes. Cell viability remained >90% for the duration of the experiments (2.5 h), and no indication of fouling was observed. It was shown that the designed dynamic filter is able to effectively avoid both cell damage and membrane fouling, and thus can be used for mammalian cell harvesting and perfusion.

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Section: Influence Of Geometric and Operational Variables On Shear-stsupporting

confidence: 94%

CFD‐aided design of a dynamic filter for mammalian cell separation

Castilho

Anspach

2003

Biotech & Bioengineering

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“…3b)). According to [33], a particle at the cake surface is subjected to two main forces: the shear stress (depending on the shear rate applied to the particle) and the drag force. When the shear force exceeds the drag force, the particle losses contact with the cake.…”

Section: Resultsmentioning

confidence: 99%

“…The total weight of solid particles in the cake is not constant during the consolidation period [32]. Additionally, the value of the shear stress on the cake surface and viscosity of suspension varies in the direction from the axis of rotation to the external edge of the rotating disk [33]. Accounting for these difficulties, a simplified approach based on Darcy's law [30]:…”

mentioning

confidence: 99%

Dead‐End Dynamic Filtration of Highly Concentrated CaCO₃ Suspensions in the Presence of a Dispersant

et al. 2010

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This work discusses dewatering of CaCO 3 suspensions in the presence of a dispersant (sodium polyacrylate). Suspensions were dewatered using the rotating diskaided dead-end dynamic filtration technique. Dewatering efficiency was studied as a function of the dispersant content and operational parameters (disk rotation speed, filtration pressure). Two dewatering modes, with initial (i-dewatering) and delayed (d-dewatering) dispersant addition, were tested. For concentrated suspensions, the d-dewatering allowed higher final dryness and better fluidity than i-dewatering with minimum dispersant losses in the filtrate. IntroductionMineral suspensions with a high concentration of particles and low viscosity are required for many practical applications, such as ceramic processing and preparation of paints, or paper coatings [1,2]. However, viscosity is generally high with concentrated mineral suspensions due to their aggregation and formation of spatial networks [3,4]. One effective way of fluidity regulation is based on the addition of suitable dispersants [5].The highly concentrated (72-75 wt %) and low-viscosity suspensions of calcium carbonate (CaCO 3 ) are required for improvement of paper whiteness, gloss, and printability. The sodium and ammonium salts of polyacrylic acid were found to be effective dispersants for CaCO 3 suspensions [6,7].Different methods for preparation of highly loaded CaCO 3 suspensions, based on powder rehydration in the presence of a dispersant , containing up to 74 wt % CaCO 3 in the presence of 0.5 wt % sodium polyacrylate [16,17]. However, a supplementary stage of mechanical cake homogenization is required for cake fluidization and high dryness can be achieved after CaCO 3 cake compression at 10-15 bars. The dead-end filtration technique always results in growth of the filter cake in low filtration efficiency and it requires supplementary mechanical agitation for filter cake fluidization. To avoid these limitations, different continuous microfiltration techniques with shear flow were tested [18,19,[20][21][22][23][24].The filtration flux in a rotating disk system is governed by different operational parameters, such as filtration pressure, rotation speed, concentration of feed suspension, as well as the design of the filtration module. The moment of dispersant addition in the course of filtration may also be an important factor influencing the dryness and fluidity of the final suspension and filtrate contamination by the dispersant. Then, it requires further investigation.This work is devoted to the study of dewatering of CaCO 3 suspensions using a lab-scale dynamic filtration module. The cylindrical filter cell comprised a rotating disk with adjustable speed and filtration was carried out on a fixed microfiltration membrane. The time of dispersant (sodium polyacrylate) addition and operational parameters (disk rotation speed, filtration pressure) were analyzed. Materials and Methods MaterialsThe aqueous suspension of calcium carbonate with an initial solid content of 20.0 wt % was provi...

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“…The flow field induced by the rotation of a flat disk parallel to a flat plate has been described previously by various authors (Bouzerar et al, 2000a(Bouzerar et al, , 2000bWilson and Schryer, 1978). Since in our case the axial gap between the membrane and the disk was relatively large (10 mm) the flow was of boundary layer type and turbulent except at low speeds and in the central part.…”

Section: Pressure and Shear Stress Distribution On The Membranementioning

confidence: 90%

Microfiltration and ultrafiltration of polysaccharides produced by fermentation using a rotating disk dynamic filtration system

Brou

Jaffrin

Ding

et al. 2003

Biotech & Bioengineering

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The recovery of exopolysaccharides (EPS) produced by Sinorhizobium meliloti bacteria by dynamic microfiltration was investigated using a rotating disk device designed in our laboratory, equipped with a 0.2 microm nylon membrane. This system differs from commercially available systems by the presence of vanes on the disk which produce a very important increase in permeate flux while yielding excellent EPS transmission. For polymers produced under standard fermentation conditions (70 h at 30 degrees C), the mass flux rose to 650 g h(-1) m(-2) using a disk equipped with 2 mm vanes rotating at 2000 rpm against 380 g h(-1) m(-2) with a smooth disk at the same speed. The maximum flux observed was 1560 g h(-1) m(-2) with a 6-mm vanes disk rotating at 3000 rpm and a 36 degrees C broth. An interesting finding was that the permeate flux J(f) for various disks can be correlated by the same function of the mean shear stress at the membrane tau(wm) according to J(f) = 4.6 tau(wm) (0.717) for a 30 degrees C broth, showing that the effect of vanes is merely to increase the shear stress by raising the fluid core velocity between the membrane and the disk. With 6-mm vanes the core angular velocity was found to be 84% of disk velocity vs. 45% for a smooth disk. When the fermentation temperature was increased to 36 degrees C to produce a lower molecular weight polymer, the permeate flux rose by about 250%, much more than what could be expected from the reduction in permeate viscosity and followed the same power law with membrane shear stress as for 30 degrees C. The same device was equipped with a PES 50 kDa membrane to concentrate EPS by ultrafiltration. Permeate fluxes were of the order of 160 L h(-1) m(-2) at 2000 rpm and 30 degrees C with nearly complete EPS rejection. Finally, the net electrical power consumed by the disk was measured by subtracting the power consumed without fluid from the power during filtration at the same speed. This power increases with speed and with the presence of vanes, but since the gain provided by the vanes is very high, the specific energy per m(3) of permeate is minimal with the highest vanes tested (6 mm) and maximal for smooth disks.

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Influence of geometry and angular velocity on performance of a rotating disk filter

Cited by 88 publications

References 15 publications

CFD‐aided design of a dynamic filter for mammalian cell separation

CFD‐aided design of a dynamic filter for mammalian cell separation

Dead‐End Dynamic Filtration of Highly Concentrated CaCO₃ Suspensions in the Presence of a Dispersant

Microfiltration and ultrafiltration of polysaccharides produced by fermentation using a rotating disk dynamic filtration system

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Influence of geometry and angular velocity on performance of a rotating disk filter

Cited by 88 publications

References 15 publications

CFD‐aided design of a dynamic filter for mammalian cell separation

CFD‐aided design of a dynamic filter for mammalian cell separation

Dead‐End Dynamic Filtration of Highly Concentrated CaCO3 Suspensions in the Presence of a Dispersant

Microfiltration and ultrafiltration of polysaccharides produced by fermentation using a rotating disk dynamic filtration system

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Dead‐End Dynamic Filtration of Highly Concentrated CaCO₃ Suspensions in the Presence of a Dispersant