Design of stirred vessels with gas entrained from free liquid surface

Patwardhan, Ashwin W.; Joshi, Jyeshtharaj B.

doi:10.1002/cjce.5450760303

Cited by 31 publications

(17 citation statements)

References 26 publications

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“…Equations that have been proposed for the estimation of k L a in surface aerators (ungassed systems) are similar to those proposed for sparged and mechanically agitated gas-liquid contactors [86,99]. One particular equation for surface aeration of water by a dual pitched-blade impeller system states [50]: ; , : .…”

Section: Mechanically Agitated Surface Aeratorsmentioning

confidence: 97%

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Gas–Liquid Oxygen Mass-transfer; from Fundamentals to Applications in Hydrometallurgical Systems

Filippou

Cheng

Demopoulos

2000

Mineral Processing and Extractive Metallurgy Review

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Oxygen gas is used as a reactant in many hydrometallurgical processes. However, oxygen is sparingly soluble in aqueous electrolyte solutions, and the driving force for its masstransfer from the gas to the aqueous phase is also very low. Hence, the mass-transfer of oxygen depends significantly on the interfacial area between the gas and the liquid phase, which in turn depends on the mixing conditions inside the reactor. A change in the solution composition or the presence of solids can further alter the rate of oxygen masstransfer. All such phenomena related to the gas-liquid oxygen mass-transfer in hydrometallurgical unit operations are critically reviewed in the present article -from the basic thermodynamics and kinetics of oxygen dissolution in aqueous solutions to the most recent advances in oxygen mass-transfer systems.

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Section: Mechanically Agitated Surface Aeratorsmentioning

confidence: 97%

“…Several other equations for determining N cr are presented in a recent review by Patwardhan and Joshi [99].…”

Section: Mechanically Agitated Surface Aeratorsmentioning

confidence: 97%

Gas–Liquid Oxygen Mass-transfer; from Fundamentals to Applications in Hydrometallurgical Systems

Filippou

Cheng

Demopoulos

2000

Mineral Processing and Extractive Metallurgy Review

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“…Hence, viscous fluids may benefit from surface baffles, which are half baffles located in the upper half of the reactor. These baffles iimit vortex formation while ~ncreasing surface turbulence [ 48]. Surface baffle design Induces small vortices which entrain gas more effectively, Increasing gas holdup and the gas-liquid mass h·ansfer coefficient.…”

Section: Figure 4: Viscosity Effect On the Gas-liquid Mass Transfer Cmentioning

confidence: 99%

Mixing Considerations in Stirred Tank Bioreactors When Using Fluid Property Altering Microorganisms

Kadic

Heindel

2010

ASME 2010 3rd Joint US-European Fluids Engineering Summer Meeting: Volume 1, Symposia – Parts A, B, and C

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Stirred tank reactors are one of the standard reactors in the chemical industry and have been widely implemented for biological applications. They are used with viscous liquids, slurries, very low gas flow rates, and large liquid volumes. Stirred tank bioreactors are popular because a well-mixed state, required or preferred for numerous biological processes, is usually achieved in such situations; however, many production processes using microorganisms tend to experience fluid property alterations, which significantly impact mixing, operational parameters, and process results. The most troubling issues occur when a fluid gradually undergoes a viscosity change and/or slowly exhibits non-Newtonian behavior due to microorganism growth since these will alter the flow conditions and possibly limit the conversion rate or production scale. This paper provides an overview of the relevant mixing issues in stirred tank bioreactors when using a range of fluid viscosities, surface tensions, and/or non-Newtonian fluids. ABSTRACT Stirred tank reactors are one of the standard reactors in the chemical industry and have been widely implemented for biological applications. They are used with viscous liquids, lurries, very low gas flow rates, and large liquid vo lumes. tirred tank bioreactors are popular because a well-mixed state, required or prefetTed for numerous biological processes, is usually achieved in such situations; however, many production processes using microorganisms tend to experience fluid property alterations, which significantly impact mixing, operational parameters, and process results. The most troubling i ues occur when a fluid gradually undergoes a viscosity change and/or slowly exhibits non-Newtonian behavior due to microorganism growth since these will alter the flow conditions and possibly limit the conversion rate or production sca le. This paper provides an overview of the relevant mixing issues in tirred tank bioreactors when using a range of fluid viscosities, urface tensions, and/or non-Newtonian fluids .

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“…Thakre and Joshi [4] have successfully used low Reynolds number k-e model and the Reynolds stress model (RSM) for the prediction of heat transfer coefficients in a single-phase fully developed turbulent pipe flow. The details of this work have been given later in section 2.…”

Section: Introductionmentioning

confidence: 99%

“…In surface aerators (Patwardhan and Joshi, [4]) and self-inducing impellers (Patwardhan and Joshi, [5]) gas phase is drawn from the headspace into the liquid. For this purpose bubbles need to get formed by the generation of wavy/turbulent motion near the top surface and the bubbles thus formed need to be drawn down into the liquid phase.…”

Section: Introductionmentioning

confidence: 99%

Reduction of Empiricism through Flow Visualization and Computational Fluid Dynamics

Joshi¹

2002

Chem. Eng. Technol.

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Design of stirred vessels with gas entrained from free liquid surface

Cited by 31 publications

References 26 publications

Gas–Liquid Oxygen Mass-transfer; from Fundamentals to Applications in Hydrometallurgical Systems

Gas–Liquid Oxygen Mass-transfer; from Fundamentals to Applications in Hydrometallurgical Systems

Mixing Considerations in Stirred Tank Bioreactors When Using Fluid Property Altering Microorganisms

Reduction of Empiricism through Flow Visualization and Computational Fluid Dynamics

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