Magnetically Stabilized Fluidization Part I Gas and Solids Flow

Geuzens, P.; Thoenes, D.

doi:10.1080/00986448808940385

Cited by 19 publications

(42 citation statements)

References 8 publications

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“…Magnetic stabilization of fluidized beds has also been used to reduce axial dispersion and enhance separations (19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29). The use of a magnetic field has been shown to limit particle motion in systems containing both a single magnetic support and a mixture of magnetically susceptible and nonmagnetic support material (19,(30)(31).…”

Section: Introductionmentioning

confidence: 99%

Effect of Hydrodynamic and Magnetic Stabilization on Fluidized-Bed Adsorption

Seibert

Burns

1998

Biotechnol. Prog.

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Direct fermentation broth processing using fluidized beds is extremely advantageous due to the low operating pressure drop of the device and the ability of the bed to process suspended-solids-containing solutions. Unfortunately, the solid particles in fluidized beds typically show a great deal of mixing compared to those in packed beds. This mixing may lead to early breakthrough and inefficient use of adsorptive capacity. Stabilization reduces the solids mixing and improves the performance and efficiency of a fluidized bed. A comparison of packed, fluidized, and stabilized beds reveals that, while normal fluidized beds do contain a significant amount of mixing, the breakthrough behavior of the bed is not drastically different than that of a packed bed. Magnetic stabilization of the bed usually leads to an increase in adsorption efficiency but is dependent on field strength and orientation. Permanently magnetized beds were also investigated and produced breakthrough efficiencies similar to those of packed beds.

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Section: Introductionmentioning

confidence: 99%

Effect of Hydrodynamic and Magnetic Stabilization on Fluidized-Bed Adsorption

Seibert

Burns

1998

Biotechnol. Prog.

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“…Peclet number is considered as an important parameter that affects the rate of the bioconversion as shown in Eq. (8). It is evident in Fig.…”

Section: Methodsmentioning

confidence: 80%

Antibiotics production in a fluidized bed reactor utilizing a transverse magnetic field

Al-Qodah

2000

Bioprocess Engineering

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A mathematical model is developed to describe the performance of a three-phase¯uidized bed reactor utilizing a transverse magnetic ®eld. The model is based on the axially dispersed plug¯ow model for the bulk of liquid phase and on the Michaelis-Menten kinetics. The model equations are solved by the explicit ®nite difference method from transient to steady state conditions. The results of the numerical simulation indicate that the magnetic ®eld increases the degree of bioconversion. The mathematical model is experimentally veri®ed in a threephase¯uidized bed reactor with Penicillium chrysogenum immobilized on magnetic beads. The experimental results are well described by the developed model when the reactor operates in the stabilized regime. At low and relatively high magnetic ®eld intensities certain discrepancy in the model solution is observed when the model over estimates the product concentration. List of symbolsB magnetic ®eld intensity, mT C dimensionless substrate concentration in the bulk of the liquid C b substrate concentration in the bulk of the liquid, kg/m 3 C p Penicillin concentration, kg/m 3 C f substrate concentration in the bio®lm, kg/m 3 C o substrate concentration in the bulk of the liquid, kg/m 3 C s substrate concentration at the surface of the bead, kg/m 3 C x biomass dry density, kg/m 3 D aw molecular diffusivity of lactose in water, m/s D e effective diffusivity of lactose in the bio®lm, m 2 /s D l axial dispersion coef®cient, m 2 /s d p Particle diameter, m K m saturation constant, kg/m 3 K s external mass transfer coef®cient for the transport of glucose, m/s L bed height, m L o bed height, m M s saturation magnetic intensity, mT Pe Peclet number R radius of the magnetic bead, m Re Reynolds number r distance inside the bio®lm, m r s radius of the magnetic support, m S dimensionless substrate concentration inside the bio®lm U g gas velocity, m/s U l liquid velocity, m/s V max maximum reaction rate, kg lactose/kg cell X v cell density in the bio®lm, kg/m 3 X dimensionless radius Y max maximum yield coef®cient, kg/kg Y x/s growth yield coef®cient, kg/kg Z dimensionless length z length, mGreek letters q b bulk density of the magnetic particles, kg/m 3 q s molded density of the magnetic particles, kg/m 3 ebed porosity e f bio®lm porosity e gb gas holdup e l liquid holdup e so initial solid holdup l max maximum growth rate, s )1 aParameter, (K s A s L/(e l U l ) h dimensionless time, U l t/L d bio®lm thickness, m IntroductionWhole cell immobilization technology has generated considerable interest in the ®eld of bioreactor design and operation. It has lead to the design of new reactor con®gurations to accommodate the resulting immobilized cell conformation in the form of relatively large spherical particles. Currently,¯uidized bed bioreactors are being considered as promising reactor con®gurations that are suitable to carry out bioprocesses with immobilized whole cells. The reactors are characterized by low shear stresses compared to mechanically stirred vessels and good mixing conditions, whic...

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“…Therefore, in a general dimensionless form the solution (2.7) can be expressed as Note: The definition of the Peclet number Pe L = Di/UL^j in (2.8) differs from the common expression Pe = UL/D , but we will follow Geuzens (1985) since in the solutions (see 2.7 for example) the group D L /ULi, e j naturally occurs as well as in some practically developed relationships commented next.…”

Section: Fitting the Dispersion Model To The Real Reactormentioning

confidence: 99%

Magnetic Field Assisted Fluidization - A Unified Approach Part 7. Mass Transfer: Chemical reactors, basic studies and practical implementations thereof

Hristov¹

2009

Reviews in Chemical Engineering

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Transfer Studies 5.1. Bubble Columns with chemically inert coarse particles 5.2. Slurry Bubble Columns (SBC) 5.2.7. Slurry Bubble Columns with chemically inert flne particles 5.2.2. Slurry Bubble Columns with fine suspended catalyst particles: laboratory studies 5.2.3. Slurry Bubble Columns with fine suspended catalyst particles: process oriented examples 5.4. Trickle beds (Counter-current flow) 5.4.1. General comments 5.4.2. Flue gas desulphurization -Approach ofGui et al. 5.4.3. Flue gas desulphurization by enhanced iron corrosion in a magnetic field 5.4.4. L-S mass transfer with SRNA-4 catalyst in magnetically assisted trickle bed 5.4.5. Comments and suggestion about the mass transfer dimensionless correlations. 5.4.6. Final comments on magnetically assisted trickle beds 5.5. Magnetically assisted airlifts -mass transfer issues 6. INDUSTRIAL IMPLEMENTATIONS -Trials and errors 6.1. Preamble 6.2. Early attempts: Bulgarian pilot-plant experiments 6.2.7. Results 6.2.2. Principle drawbacks 6.3 The EXXON Era 6.4. The Chinese Wave 6.5. Critical Overview and Lessons 7. CLOSING COMMENTS ACKNOWLEDGMENTS LIST OF SYMBOLS REFERENCES SUMMARY Part 7 of the series Magnetic Field Assisted Fluidization (MFAF)-A Unified Approach is devoted to chemical reactor design utilizing Brought to you by | University of Birmingham Authenticated Download Date | 6/13/15 5:09 PM Jordan HristovReviews in Chemical Engineering magnetically assisted fluidized beds. Basic reactor principles wellimplemented in the chemical engineering science are used to analyze the existing situation of those special types of mass transfer devices. The hydrodynamics of all systems reviewed in the previous parts of the series (G-S, L-S and G-L-S) serves as a foundation assuring proper understanding of their mass transfer performances. Thorough analysis of MFAF mass transfer studies in both laboratory and pilot scales is performed. Special attention is paid to the attempts to do industrial implementations of MFAF based chemical reactors: trial-error steps, pitfalls and recent achievements. Part 7 refers only to reactor designs and chemical reaction performances whilst magnetically assisted bioreactors are at issue in a separate part of the review series. All these issues make Part 7 a comprehensive review thoroughly investigating one undeveloped, but with a great potential and directly applicable to practice, branch of magnetic field assisted fluidization. PREFACEDear readers, Part 7 of the series Magnetic Field Assisted Fluidization (MFAF) finally arrived to the point where contacting devices based on this fluidization technique and their mass transfer performances have to be analyzed. As it was mentioned continuously in the previous reviews, the hydrodynamics and the proper knowledge of the regimes enable to understand and control the mass and heat transfer operations in a correct way. Now, with knowledge accumulated systematically in the preceding 6 issues, we approach mass transfer operations performed by various groups of investigators over 45 years and provoke...

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Magnetically Stabilized Fluidization Part I Gas and Solids Flow

Cited by 19 publications

References 8 publications

Effect of Hydrodynamic and Magnetic Stabilization on Fluidized-Bed Adsorption

Effect of Hydrodynamic and Magnetic Stabilization on Fluidized-Bed Adsorption

Antibiotics production in a fluidized bed reactor utilizing a transverse magnetic field

Magnetic Field Assisted Fluidization - A Unified Approach Part 7. Mass Transfer: Chemical reactors, basic studies and practical implementations thereof

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