Filtration of Colloidal Suspensions – MRI Investigation and Numerical Simulation

Erk, A.; Hardy, Edme H.; Althaus, Tim O.; Stahl, W.

doi:10.1002/ceat.200600054

Cited by 6 publications

(4 citation statements)

References 5 publications

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“…This model evolved after researchers indirectly observed the formation of a boundary layer near the liquid surface. They confirmed the presence of a boundary layer through MRI images and by placing discs in the centrifuge, which did not affect the separation efficiency [18][19][20][21]. Studies are still in progress to derive an analytical expression based on this model.…”

Section: Boundary Layer Modelmentioning

confidence: 87%

“…The sigma theory is a simple and the first principle analytical approach to analyze the TBC, which assumes plug flow and rigid body motion inside a rotating bowl [16,17]. The path of the solid particle in the tubular bowl centrifuge is examined using magnetic resonance imaging (MRI) and computational fluid dynamics (CFD) studies [18][19][20][21]. Zeng et al [22] proposed an innovative method that improved the seperation selectively due to the combined action of magnetic force, centrifugal force, and hydrodynamic drag upon paramagnetic particles.…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of Separation Efficiency in a Tubular Bowl Centrifuge

et al. 2022

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Centrifugal sedimentation, a well-known solid-liquid separation process, is typically used for the separation of solids from low concentration feeds because of its high separation efficiency due to high settling velocities. The performance of the tubular bowl centrifuge (TBC) can be studied by using the sigma theory, which assumes plug flow and rigid body motion inside the rotating bowl wall. The separation efficiency of the system is evaluated by determining the effective fluid layer thickness from the experimental data. A method suitable for evaluating the separation efficiency at different parameters for a given TBC is explained along with experimental validation. By using this method, different case studies are performed which depict the influence of each parameter on the separation efficiency. Also, it is demonstrated that the same higher separation efficiency (98 %) at 20 000 rpm could be achieved at higher bowl capacities.

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Section: Boundary Layer Modelmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 99%

Evaluation of Separation Efficiency in a Tubular Bowl Centrifuge

et al. 2022

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“…The in situ measurement in the centrifugation has been carried out using several techniques. In situ measurements of particle-liquid separation using noninvasive magnetic resonance imaging (MRI) successfully confirmed the separation process inside the centrifuge in terms of volume capacity, particle size distribution, and the hindered settling of the sediment [12][13][14]. On the other hand, the microscopic viewpoint, such as the particle behavior in the particle-liquid two-phase flow, can be considered to observe the L p .…”

Section: Introductionmentioning

confidence: 89%

In situ measurement of sludge thickness in high-centrifugal force by optimized particle resistance normalization for wireless electrical resistance detector (WERD)

Prayitno

Zhao

Iso

et al. 2020

Meas. Sci. Technol.

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This study investigates the in situ sludge thickness of polymers in a real-scale horizontal decanter centrifuge using the optimized particle resistance normalization (OPRN) technique. The sludge thickness of poly(methyl methacrylate) (PMMA) in an aqueous sodium chloride (NaCl) carrier fluid was observed as a function of the normalized particle resistance of a wireless electrical resistance detector. The measured resistance of the continuous phase during the centrifugation is set as the reference and normalized following its dominant frequency by Fourier transform. Here, the OPRN limits the particle resistance using the normalization function based on the closed-packing condition (i.e. Krieger 1972 Adv. Colloid Interface Sci. 3 111–36; Phillips et al 1992 Phys. Fluids A 4 30–40; and Rao et al 2002 Int. J. Numer. Methods Fluids. 39 465–83) in the particle sensitivity area (PSA). The normalized value is then plotted in the fitting equation using a nonlinear generalized reduced gradient. The PSA is solved by a simulation study on electrostatics and by static experiments. Two different centrifugation parameters of feed rates and two centrifugal forces at four different measurement points were considered to observe the sludge thickness distribution as a function of operational time. As a result, the in situ sludge thickness is described in the nonlinear fit plot equation with a coefficient score to explain the separation phenomenon inside the decanter centrifuge. The plot agrees well with the experimental data with a high degree of coefficient of determination.

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“…The noninvasive MRI method for in-situ investigations of solid-liquid separation processes was used by various authors [22,23]. The imaging experiments were carried out in a Bruker (Rheinstetten, Germany) Avance 200 tomograph (B 0 = 4.7 T) equipped with a Bruker mini036 micro-imaging gradient system.…”

Section: Mri Analysismentioning

confidence: 99%

Investigations on the Separation Efficiency of Tubular Bowl Centrifuges

Stahl¹,

Spelter²,

Nirschl³

2008

Chem Eng & Technol

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In the last decade a major progress has been achieved in the synthesis and functionalization of nanoscale particles, but the handling of such material systems like separation or classification has been neglected. With tubular centrifuges, even nanoscale particles can be separated from a suspension at reasonable throughputs due to very high g values. This is a great advantage compared to membrane techniques (low throughput) and filtering, disc stack and decanter centrifuges (lower g values). An analysis of the discharged solids in dependence on time and verification of sediment build-up with a magnetic resonance spectrometer (MRI) provide a comprehensive understanding of the sedimentation process in a tubular bowl centrifuge. MRI allows a noninvasive, direct view into the filled centrifuge rotor; this data is compared with theoretical results.

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Filtration of Colloidal Suspensions – MRI Investigation and Numerical Simulation

Cited by 6 publications

References 5 publications

Evaluation of Separation Efficiency in a Tubular Bowl Centrifuge

Evaluation of Separation Efficiency in a Tubular Bowl Centrifuge

In situ measurement of sludge thickness in high-centrifugal force by optimized particle resistance normalization for wireless electrical resistance detector (WERD)

Investigations on the Separation Efficiency of Tubular Bowl Centrifuges

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