Computational fluid dynamics study on mixing mode and power consumption in anaerobic mono- and co-digestion

Influence of impeller diameter on local gas dispersion properties in a sparged multi-impeller stirred tank

Power consumption and mass transfer in a gas-liquid-solid stirred tank reactor with various triple-impeller combinations

Analysis of power consumption for gas dispersion in non-Newtonian fluids with a coaxial mixer: New correlations for Reynolds and power numbers

This chapter explains the complexity of providing a fermentation organism with dissolved oxygen at both the required concentration and rate to satisfy its oxygen demand. The effect of dissolved oxygen concentration on the physiology of industrial fermentations is addressed—developing the concepts of specific oxygen uptake rate ( Q O 2 Q O 2 ) and critical dissolved oxygen concentration. The dynamics of oxygen transfer are developed and the importance, and measurement, of the volumetric mass transfer coefficient ( K L a ) in the design and operation of a fermentation explained. The influence of mycelial morphology on culture rheology and oxygen transfer is explored and means of manipulating morphology, and thus rheology, are developed as well as the problems of mixing highly viscous pseudoplastic fermentations. The problem of designing a fermentation process that balances the oxygen demand of the organism with the oxygen supply capacity of the fermenter is addressed. Finally, the approaches to the scale-up and scale-down of fermentations are explored.

Aeration and agitation

Power consumption, local and average volumetric mass transfer coefficient in multiple-impeller stirred bioreactors for xanthan gum solutions

Power numbers in a baffled stirring tank with paddle-type impellers were measured over a range of Reynolds numbers, from laminar- to turbulent-flow regions. The impellers studied included a two-blade flat-paddle impeller, a 45° two-blade pitched-paddle impeller, a 45° four-blade pitched-blade turbine, and a two-stage pitched-blade turbine. The impeller-diameter-to-tank-diameter ratio was 0.5 to 0.6. The measured power numbers were compared with those derived from two other methods: prediction by using correlations and computational fluid dynamics (CFD). Power number correlations showed that the values estimated from the empirical correlations proposed by Nagata agreed closely with those measured in the laminar-flow region but deviated significantly in the transitional- and turbulent-flow regions. The power numbers derived from the correlation proposed by Kamei and Hiraoka agreed well with the experimental results in the laminar- and turbulent-flow regions. The power number in a stirring tank was also simulated by the CFD method. The numerical results showed satisfactory agreement with the experimental data over a wide range of Reynolds numbers.

Comparison of Power Number for Paddle-Type Impellers by Three Methods

The invention relates to oil exploitation equipment, in particular to a multi-stage continuous curing tank for hydrophobically associating polymer. According to the technical scheme, the multi-stage continuous curing tank for the hydrophobically associating polymer comprises a curing tank body, a stirring shaft arranged in a cavity of the curing tank body, stirring paddles arranged on the stirring shaft, and a driving motor for driving the stirring shaft to rotate, wherein at least one clapboard which is arranged along the axial direction of the curing tank body is arranged in the cavity of the curing tank body; independent mixing chambers are formed on the two sides of each clapboard in the axial direction; a plurality of flow passing holes which penetrate through each clapboard are uniformly distributed in each clapboard; the stirring shaft penetrates through each clapboard and extends to the mixing chambers; the stirring paddles are arranged on the stirring shaft positioned in the mixing chambers; a sealing piece is arranged between the stirring shaft and each clapboard; and an anti-mixing device is arranged on each clapboard. Through the technical scheme, by a dissolving and curing device, the treatment capacity is high, the hydrophobically associating polymer is quickly dissolved and cured, and the hydrophobically associating polymer which is high in viscosity and uniformly mixed can be obtained.

Multi-stage continuous curing tank for hydrophobically associating polymer

The utility model relates to oil exploitation equipment, in particular to a hydrophobic association polymer multi-level continuous slaking tank. The hydrophobic association polymer multi-level continuous slaking tank comprises a slaking tank, a stirring shaft arranged in a cavity of the slaking tank, a stirring paddle arranged on the stirring shaft, and a drive motor driving the stirring shaft to rotate. At least one baffle is arranged along the axial direction of the slaking tank in the cavity of the slaking tank. Two axial-direction sides of the baffle respectively form independent mixing rooms. A plurality of flow holes penetrating through the baffle are evenly distributed on the baffle. The stirring shaft penetrating through the baffle extends to each mixing room. The stirring shaft in each mixing room is respectively provided with the stirring paddle. A sealing piece is arranged between the stirring shaft and the baffle. The baffle is provided with a mixing-prevention device. By means of the technical structure, the hydrophobic association polymer multi-level continuous slaking tank is large in process amount, rapidly dissolves slaking hydrophobic association polymers, and can obtain the slaking hydrophobic association polymers of high viscosity and uniform mixing.

Guo-zhong Zhou

Papers

Power consumption, local and average volumetric mass transfer coefficient in multiple-impeller stirred bioreactors for xanthan gum solutions

Comparison of Power Number for Paddle-Type Impellers by Three Methods

Multi-stage continuous curing tank for hydrophobically associating polymer

Hydrophobic association polymer multi-level continuous slaking tank

Study on Solubility of Hydrophobically Associating Polymers Using Double Agitators