Gas/liquid mass transfer in sparged agitated slurries

Oguz, H. Kagan; Brehm, Axel; Deckwer, Wolf‐Dieter

doi:10.1016/0009-2509(87)80186-0

Cited by 44 publications

(14 citation statements)

References 16 publications

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“…The same trend of the k L a coef®cient increase in the range of small solid concentration was observed by other workers [1,3,4] too, for various types of particles.…”

Section: Resultssupporting

confidence: 71%

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Studies on transfer processes in mixing vessels: effect of particles on gas-liquid mass transfer using modified Rushton turbine agitators

Roman

Tudose

1997

Bioprocess Engineering

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The effect of suspended inert solid particles on gas-liquid mass transfer has been investigated in the vessels equipped with standard and modi®ed Rushton turbine agitators positioned singly or doubly on same shaft.The relations between the volumetric mass transfer coef®cient in various suspensions, speci®c power consumption and super®cial gas velocity were obtained.Mixing with the modi®ed Rushton turbines having the surface fraction of the perforations equal to 0.353, the oxygen transfer ef®ciency is over 45% higher than that obtained using standard Rushton turbines. List of symbolsoxygen transfer ef®ciency (m 3 O 2 /Wh) K consistency index (Pas n ) k L a volumetric mass transfer coef®cient (s A1 ) n¯ow behavior index (A) n p number of blades of mixing system (A) N agitator speed (s A1 ) P g power consumption in gas-liquid system (W) P gs power consumption in gas-liquid-solid system (W) r coef®cient of correlation (A) S1, S3 particle types (A) S C full surface of the blade (m 2 ) S G surface of the perforations applied on the blade (m 2 ) S G aS C surface fraction of the perforations (A) 1TP3, 2TP3 modi®ed blade turbines, single and double respectively (A) 1TR, 2TR standard Rushton turbines, single and double respectively (A) v s super®cial gas velocity (m/s) V L , V S volume of the liquid and suspension respectively (m 3 ) X particle concentration (g/l) w baf¯e width (m) IntroductionIn multiphase processes carried out in stirred vessels, interphase mass transfer is often an important step and may be rate determining for the overall process. The k L a values in mechanically agitated reactors depend on various parameters like system properties, vessel and stirrer dimensions and arrangement and operating conditions [1].For slurry reactors, it has been observed that the addition of solids has an in¯uence on gas-liquid mass transfer characteristics, even if these particles are not reactive and do not show increased adsorption of dissolved gases [2±4].In the systems with inert particles, k L a increases slightly at low particle concentrations under otherwise constant conditions but drops sharply if the viscosity of the slurry system relative to the liquid exceeds a value of roughly 4 [1±4].In the work [5], the gas-liquid mass transfer in a sparged vessel agitated by one, respectively two standard and modi®ed Rushton turbine agitators, was characterized.Between the ®ve modi®ed blade turbine types investigated, having a surface fraction S G aS C of the perforations in the range 0.117±0.588, the modi®ed turbine for which S G aS C is equal to 0.353 (noted TP3) was considered as optimum.The mass transfer ef®ciency of the TP3 modi®ed turbines, single or double, is over 30% higher than that obtained using the TR standard turbines.The purpose of this work is to examine the effect of the solid particles on gas-liquid mass transfer and to check the applicability of k L a correlations developed for gas-liquid systems.The TP3 modi®ed turbines, single or double, are compared with the standard turbines.The inert particles used are ...

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“…The same trend of the k L a coef®cient increase in the range of small solid concentration was observed by other workers [1,3,4] too, for various types of particles.…”

Section: Resultssupporting

confidence: 71%

“…The k L a values in mechanically agitated reactors depend on various parameters like system properties, vessel and stirrer dimensions and arrangement and operating conditions [1].…”

Section: Introductionmentioning

confidence: 99%

Studies on transfer processes in mixing vessels: effect of particles on gas-liquid mass transfer using modified Rushton turbine agitators

Roman

Tudose

1997

Bioprocess Engineering

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show abstract

“…From the correlation of Oguz et al (1987) for slurry systems (Table 11, a gas-liquid mass-transfer coefficient of 0.4 s-' can be achieved for a power input of 1.5 kW/m3 (7.5 hp/1,000 gal) of slurry. Thus, all the parameters chosen/recommended by the screening procedure are consistent and the reactor is a feasible one.…”

Section: Plmentioning

confidence: 98%

Screening procedure for synthesizing isothermal multiphase reactors

Kelkar

1998

AIChE Journal

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“…All three possible effects have been reported: a decrease in kLa value (Mills et al, 1987;Oguz et al, 1987), an increase (Derksen et al, 2000;Mehta et al, 1971) and a negligible influence (Oguz et al, 1987). A general trend suggested by Lee and Foster (1990) is that a small volume of relatively small sized solids (up to 2-3 vol.%) has little effect on kLa.…”

Section: Introductionmentioning

confidence: 97%

“…Although the influence of solids loading on the volumetric oxygen transfer coefficient kLa has been studied extensively (Albal et al, 1983;Garchia-Ochoa et al, 1997;Oguz et al, 1987), the effect of suspended particles on the kLa value is not clear yet. All three possible effects have been reported: a decrease in kLa value (Mills et al, 1987;Oguz et al, 1987), an increase (Derksen et al, 2000;Mehta et al, 1971) and a negligible influence (Oguz et al, 1987).…”

Section: Introductionmentioning

confidence: 99%