Turbulent mixing in a three-phase fluid bed

Vail, Yu. K.; Manakov, N. Kh.; Manshilin, V. V.

doi:10.1007/bf00726659

Cited by 6 publications

(10 citation statements)

References 4 publications

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“…This indicates that radial mixing in three-phase fluidized beds increases with increasing gas velocity. A similar trend was observed by Vail et al (1968) and El-Temtamy et al (1979) for the radial mixing of liquid phase in three-phase fluidized beds. Figure 9 displays the effect of solid particle addition on the temperature profiles of a gas-liquid system, namely a flattening of the temperature profile.…”

Section: Wall-lo-bed Heal Transfer In Three-phase Fluidized Bedssupporting

confidence: 88%

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Heat transfer in three‐phase fluidized beds

Chiu

Ziegler

1983

AIChE Journal

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Wall-to-bed heat transfer coefficients in three-phase fluidized beds with glass beads and cylindrical 7-alumina particles were determined experimentally. In the present study, the relative increase in heat transfer coefficient was found equal to the relative decrease in liquid holdup in three-phase fluidized beds. Modified Stanton number has been correlated with modified Reynolds number. STms = Stm2 = C Rem2-O.3O5 Pr-2/3The above correlation can be useful in reactor design. Heat transfer in three-phase fluidized beds is hypothesized to encounter a wall resistance and bed resistance in series. * Nominal particle size.Actual particle Sie. 6, and d, based on actual particle size.

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Section: Wall-lo-bed Heal Transfer In Three-phase Fluidized Bedssupporting

confidence: 88%

“…However, the effect is relatively insensitive at high gas velocities. A similar trend was observed by Vail et al (1968) for radial mixing in three-phase fluidized beds.…”

Section: Wall-lo-bed Heal Transfer In Three-phase Fluidized Bedssupporting

confidence: 85%

Heat transfer in three‐phase fluidized beds

Chiu

Ziegler

1983

AIChE Journal

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“…In the gas-liquid-solid fluidized bed a considerable backmixing in the liquid phase has been reported by several workers (Vail et al, 1968;Ostergaard, 1969;Michelsen and Ostergaard, 1970;Muroyama et al, 1978 andEl-Temtamy et al, 1979). The axial liquid mixing coefficient increases considerably with bed diameter.The degree of axial liquid mixing also depends on the flow pattern in the gasliquid-solid fluidization.…”

Section: Coefficientmentioning

confidence: 79%

Wall‐to‐bed heat transfer coefficient in gas—liquid—solid fluidized beds

1984

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Wall to bed heat transfer has been studied in three‐phase fluidized beds with a cocurrent up‐flow of water and air. Six sizes of glass beads, two sizes of activated carbon beads and one size of alumina beads, varying in average diameter from 0.61 to 6.9 mm and in density from 1330 to 3550 kg/m3, were fluidized in a 95.6 mm diameter brass column heated by a steam jacket. Complementary heat transfer experiments have been performed also for a gas–liquid cocurrent column and liquid–solid fluidized beds. The wall‐to‐bed coefficient for heat transfer in the gas–liquid–solid fluidized bed is evaluated on the basis of the axial dispersion model concept. The ratio of the wall‐to‐bed heat transfer coefficient in the gas–liquid–solid fluidized bed to that in the liquid–solid fluidized bed operated at the same liquid flow rate is correlated in terms of the ratio of the velocity of gas to that of liquid and the properties of solid particles. A correlation equation for estimating the wall‐to‐bed heat transfer coefficient in the liquid–solid fluidized bed is also developed.

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“…Since the applications of three phase fluidized bed reactors have been increasing in the field of chemical and bio-chemical processes, the hydrodynamic characteristics, such as phase holdups, bubble properties, and mixing characteristics are required to provide prerequisite knowledge for designing three phase fluidized bed reactors. However, information on the radial dispersion characteristics in three phase fluidized beds is very limited in the literature (Vail et al, 1968;El-Temtamy et al, 1979;Kang and Kim, 1986a,b;Yasunishi et al, 1987). For the radial dispersion of liquid phase in three phase fluidized beds, the radial mixing intensity increases with increasing liquid velocity, but it decreases with an increase in gas velocity (Vail et al, 1968).…”

Section: Introductionmentioning

confidence: 98%

“…However, information on the radial dispersion characteristics in three phase fluidized beds is very limited in the literature (Vail et al, 1968;El-Temtamy et al, 1979;Kang and Kim, 1986a,b;Yasunishi et al, 1987). For the radial dispersion of liquid phase in three phase fluidized beds, the radial mixing intensity increases with increasing liquid velocity, but it decreases with an increase in gas velocity (Vail et al, 1968). On the other hand, El-Temtamy et al (1979) have reported that D, is dependent on the concentration of bubbles and their wakes.…”

Section: Introductionmentioning

confidence: 99%

Radial Dispersion and Bubble Characteristics in Three-Phase Fluidized Beds

Han

Kim

1990

Chemical Engineering Communications

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The effects of gas and liquid velocities, liquid viscosity and particle size on the radial dispersion coefficient of liquid phase (D,) and the bubble properties in three-phase fluidized beds have been determined. A new flow regime map based on the drift flux theory in three-phase fluidized beds has -been proposed.In three-phase fluidized beds, D, increases with increasing gas velocity in the bubble coalescing and in the slug flow regimes, but it decreases in the bubble disintegrating regime. The coefficient exhibits a maximum value in the bed of small particles with increasing liquid velocity at lower gas velocities. However, it increases with increasing liquid velocity at higher gas velocities. In two and three-phase fluidized beds of larger particles (6.8 mm), D, exhibits a maximum value with an increase in liquid viscosity at lower gas velocities, but it increases at higher gas velocities. The mean bubble chord length and its rising velocity increase with increasing gas velocity and liquid viscosity. However, the bubble chord length decreases with an increase in liquid velocity and it exhibits a maximum value with increasine oarticle size in the bed. The radial disoersion coefficients in the bubble coalescine and -.disintegrating regimes of three-phase fluidized beds in terms of the Peclet number in the present and previous studies have been well represented by the correlations based on the concept of isotropic turbulence theory.

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Turbulent mixing in a three-phase fluid bed

Cited by 6 publications

References 4 publications

Heat transfer in three‐phase fluidized beds

Heat transfer in three‐phase fluidized beds

Wall‐to‐bed heat transfer coefficient in gas—liquid—solid fluidized beds

Radial Dispersion and Bubble Characteristics in Three-Phase Fluidized Beds

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