Measurements of solids concentration in a three-phase reactor by an ultrasonic technique

Soong, Yee; Gamwo, Isaac K.; Blackwell, A.G.; Schehl, R.R.; Zarochak, M.F.

doi:10.1016/0923-0467(95)03011-5

Cited by 7 publications

(15 citation statements)

References 9 publications

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“…Warsito et al (1995) applied the ultrasonic technique to gasliquid and liquid-solid systems. Soong et al (1995) and Stolojanu and Prakash (1997) applied the ultrasonic technique to three phase slurry systems to measure solids concentration.…”

Section: Ultrasonic Techniquementioning

confidence: 99%

Heat Transfer and Hydrodynamics in a Three-Phase Slurry Bubble Column

Prakash

1997

Ind. Eng. Chem. Res.

103

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The instantaneous and time-averaged heat transfer coefficients in the regions near the wall and at the center and average gas holdups were measured in a 0.28 m diameter slurry bubble column for the air−water and air−water−glass beads (35 μm) system. The effects of high gas velocities (up to 0.35 m/s) and high solids concentrations (up to 40 vol %) were investigated. Gas holdup decreased with increasing slurry concentrations; the rate of decline was rapid at high gas velocities. The instantaneous local heat transfer measurements were analyzed to study the bubble behavior in the regions near the wall and at the center for different solids concentrations. Larger bubbles were detected in the wall region in slurry systems compared to the solid-free system. The average heat transfer coefficient decreased with increasing slurry concentrations. The heat transfer coefficient was always lower at the wall than at the center.

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Section: Ultrasonic Techniquementioning

confidence: 99%

Heat Transfer and Hydrodynamics in a Three-Phase Slurry Bubble Column

Prakash

1997

Ind. Eng. Chem. Res.

103

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“…The detailed information of the ultrasonic unit has been reported elsewhere. [16][17][18] Data were obtained with longitudinal waves at a frequency of 1 MHz using lithium niobate transducers (1.905 cm o.d.). Both the transmitter and receiver were mounted directly inside the reactor wall at 33 cm above the gas distributor.…”

Section: Experimental Methodsmentioning

confidence: 99%

Ultrasonic Characterizations of Slurries in a Bubble Column Reactor

Soong

Gamwo

Blackwell

et al. 1999

Ind. Eng. Chem. Res.

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An indirect method (ultrasonic) and a direct technique were used to measure solid holdup in a bubble-column reactor. Nitrogen, water, and fine glass beads were used as the gas, liquid, and solid phases, respectively. The solid particle concentration in the slurry was varied from 5 to 30 wt %, and the gas superficial velocity was increased from 0.5 to 12 cm/s. The solid holdup measurements by the ultrasonic technique compared reasonably well with results obtained by the direct sampling technique.

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“…It is therefore, suitable for opaque systems and has a faster response (Chang et al, 1984;Stolojanu and Prakash, 1997). Although this technique can be used in fermentation media, Soong et al (1995) described the weakness of this technique due to low variation of ultrasonic velocity in fermentation media.…”

Section: Techniques To Evaluate Gas Holdupmentioning

confidence: 99%

Mixing characteristics of draft tube airlift bioreactor using the electrical resistance tomography

Yakubu-Gumery¹

2021

Preprint

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In this work, mixing characteristics in terms of mixing time, hydrodynamics (liquid circulation velocity and gas hold up) and shear rate were performed in the downcomer of a draft tube airlift bioreactor with different geometries (i.e., Ad/Ar between 0.38 – 2.31 and bottom clearances between 0.003-0.00 m). Newtonian (water and 34.5% coalescing sugar solution) and on Newtonian (0.2% and 0.5% xanthan gum solutions) with different viscosities were used as the liquid phase. Compressed air was used as the gas phase which was introduced through cross and circular shaped sparger configurations at superficial velocities Ugr = 0.00165-0.00807 m/s. The combined effects of geometric parameters (Ad/Ar, bottom clearances), sparger configuration, and liquid viscosity on mixing characteristics have been presented. Results showed that the increase in superficial gas velocity (Ugr) corresponds to an increase in energy generated, and thus decreases in mixing time. However, the increase in Ugr corresponds to the increase in liquid circulation velocity, gas holdup and shear rate values. Moreover, bottom clearances and draft tube diameters show effects on flow resistance frictional losses which affect results of mixing parameters investigated. The influence of sparger configurations on mixing time and liquid circulation velocity is significant due to their effect on gas distribution. Mixing time decreased to about 40% in air-water media using the cross shaped sparger. Results obtained with cross shaped sparger showed even and uniform distribution of gas, which provided better mixing as compared to the circular shaped sparger configuration. However, the sparger configuration effect on shear rate is not as significant (about 20% reduction in shear rate values using the cross shaped sparger). The effect of fluid viscosity had a significant influence on both mixing times and circulation velocity, especially in the coalescing media of sugar and xanthan gum solutions. Results from this work will help to develop a clear pattern for operation and mixing that can help improving [sic] several industrial processes, especially the ones related to emerging fields of technology such as the biotechnology industry.

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Measurements of solids concentration in a three-phase reactor by an ultrasonic technique

Cited by 7 publications

References 9 publications

Heat Transfer and Hydrodynamics in a Three-Phase Slurry Bubble Column

Heat Transfer and Hydrodynamics in a Three-Phase Slurry Bubble Column

Ultrasonic Characterizations of Slurries in a Bubble Column Reactor

Mixing characteristics of draft tube airlift bioreactor using the electrical resistance tomography

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