A boundary‐layer model of fluid‐particle mass transfer in fixed beds

Carberry, James J.

doi:10.1002/aic.690060323

Cited by 207 publications

(82 citation statements)

References 21 publications

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“…The m a s transfer coefficients +ks for 3 mm cylinder are smaller than for 6 mm cylinders at L = 2.99 kg/m2.s (Figure 5). It should be noted that a decrease in 4kS is predicted at sufficiently lower liquid Reynolds numbers (Carberry, 1960) and the enhancement of 4kS is expected to be smaller for decreasing particle size (Goto et al, 1975). …”

Section: Data Sampling and Aqulsitlonmentioning

confidence: 97%

Solid‐liquid mass transfer in packed beds with cocurrent gas‐liquid downflow

Rao

Drinkenburg

1985

AIChE Journal

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Local instantaneous solid-liquid mass transfer coefficients were measured in two-phase gas-liquid downflow through packed columns for 3 X 3 mm and 6 X 6 mm cylinders. An electrochemical technique was used. Liquid flow rates from 3.0 to 26.6 kg/m2.s and gas flow rates from 0.07 to 1.16 kg/m2*s covered the gascontinuous, ripple, and pulse flow regimes. Timeaveraged mass transfer coefficients in trickle flow and in pulse flow for the pulse proper and the base (outside the pulse) were found to increase with increasing gas and liquid rates. Correlations are presented in terms of liquid phase Reynolds numbers and in terms of Kolmogoroff numbers. The mass transfer coefficients in the pulse were found to correspond closely to the coefficients that would be attained in the dispersed bubble flow regime. V. G. RAO and A. A. H. DRINKENBURG Department of Chemical EnglneerlngRljksunlversltelt Gronlngen 9747 AG Gronlngen, The Netherlands SCOPE Trickle-bed reactors, when operated in the gas-continuous trickle flow regime, are generally restricted to relatively slow reactions since the rate is often controlled by the mass transfer resistance. Operation of the reactor at higher gas and liquid rates produces pulse flow in which high transfer rates can be realized (Hirose et al., 1976). The pulse flow regime is better suited for fast reactions than the trickle flow regime. For design, the resistance to absorption of gaseous components into the liquid and the transfer of the reacting species through the liquid film to the catalyst surface must be known, which necessitates the study of solid-liquid mass transfer. The many reported studies on solid-liquid mass transfer generally have utilized one of two methods: measuring the dissolution rate of some soluble packing or packing coated with a soluble dye, or measuring the electrical current in water under diffusion-limited transport conditions.The electrochemical method has certain advantages over the other. It facilitates direct and instantaneous measurements of solid-liquid mass transfer and is thus very useful to measure mass transfer fluctuations, especially under pulsing flow conditions. Chou et al. (1979) first measured such fluctuations in pulse flow. The pulses were found to play an important role in enhancing mass transfer coefficients, Not much is known about the mass transfer coefficients in the pulses, their dependence on flow rate of the phases, and the packing properties. No study other than Chou's has been reported in this direction. All earlier studies employed the dissolution method, from which only time-averaged values were found.The present study was conducted to understand the fundamental nature of the pulses with respect to mass transfer, the extent of mass transfer fluctuations, and their qualitative and quantitative influence on mass transfer. The instantaneous mass transfer from a single active particle (brass cylinder electrochemically coated with nickel) in the bed was measured. Beds with particles of 3 X 3 mm and 6 X 6 mm cylinders were used. The active particl...

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Section: Data Sampling and Aqulsitlonmentioning

confidence: 97%

Solid‐liquid mass transfer in packed beds with cocurrent gas‐liquid downflow

Rao

Drinkenburg

1985

AIChE Journal

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“…Mass transfer coefficients were calculated from the Carberry (1960) correlation for each of the respective flow rates. The q s values are from the isotherm fits and the diffusivities are approximate values based on the batch and confocal experiments.…”

Section: Column Breakthroughmentioning

confidence: 99%

Effects of ionic strength on lysozyme uptake rates in cation exchangers. I: Uptake in SP Sepharose FF

Dziennik

Belcher

Barker

et al. 2005

Biotech & Bioengineering

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Fluorescence scanning confocal microscopy was used in parallel with batch uptake and breakthrough measurements of transport rates to study the effect of ionic strength on the uptake of lysozyme into SP Sepharose FF. In all cases the adsorption isotherms were near-rectangular. As described previously, the intraparticle profiles changed from slow-moving self-sharpening fronts at low salt concentration, to fast-moving diffuse profiles at high salt concentration, and batch uptake rates correspondingly increased with increasing salt concentration. Shrinking core and homogeneous diffusion frameworks were used successfully to obtain effective diffusivities for the low salt and high salt conditions, respectively. The prediction of column breakthrough was generally good using these frameworks, except for low-salt uptake results. In those cases, the compressibility of the stationary phase coupled with the shrinking core behavior appears to reduce the mass transfer rates at particle-particle contacts, leading to shallower breakthrough curves. In contrast, the fast uptake rates at high ionic strength appear to reduce the importance of mass transfer limitations at the particle contacts, but the confocal results do show a flow rate dependence on the uptake profiles, suggesting that external mass transfer becomes more limiting at high ionic strength. These results show that the complexity of behavior observable at the microscopic scale is directly manifested at the column scale and provides a phenomenological basis to interpret and predict column breakthrough. In addition, the results provide heuristics for the optimization of chromatographic conditions.

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“…r_H++NaOH >R-Na++H2O (1) Mass balance equations for NaOHin a packed bed with negligible axial dispersion are :…”

Section: Evaluation Of Mass Transfer Coefficientsmentioning

confidence: 99%

Liquid-solid mass transfer in gas-liquid cocurrent flows through beds of small packings.

Yoshikawa

Iwai

Goto

et al. 1981

J. Chem. Eng. Japan

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to be zero d at Hin Fig. 2, waiting time for homogeneousnucleation surface energy Literature Cited [sec] [sec] [erg/ cm2] 1) Harano, Y., K. Nakano, M. Saito and T. Imoto: /. Chem. Eng. Japan, 9, 373 (1976).2) Harano, Y. andK. Oota: ibid., ll, 119 (1978 Rates of mass transfer from liquid phase to small particles (average diameter, 0.46-1.3 mm) were measured by use of ion-exchange reaction followed by instantaneous irreversible reaction at 30°C. Nitrogen gas and dilute aqueous solution of sodium hydroxide were fed into a shallow bed packed with a strong cation exchange resin. Volumetric mass transfer coefficients for gasliquid cocurrent up flow and downflow were almost identical at the same gas and liquid flowrates but became somewhat greater than those in liquid-full single phase flow. A unified correlation could be derived by arranging experimental data for three arrangements : liquid-full single phase flow, gas-liquid cocurrent up flow and down flow (trickle-bed).

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A boundary‐layer model of fluid‐particle mass transfer in fixed beds

Cited by 207 publications

References 21 publications

Solid‐liquid mass transfer in packed beds with cocurrent gas‐liquid downflow

Solid‐liquid mass transfer in packed beds with cocurrent gas‐liquid downflow

Effects of ionic strength on lysozyme uptake rates in cation exchangers. I: Uptake in SP Sepharose FF

Liquid-solid mass transfer in gas-liquid cocurrent flows through beds of small packings.

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