Investigation of turbulence modulation in solid–liquid suspensions using parallel competing reactions as probes for micro-mixing efficiency

Unadkat, Heema; Nagy, Zoltán K.; Rielly, Chris D.

doi:10.1016/j.cherd.2013.05.005

Cited by 12 publications

(23 citation statements)

References 25 publications

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“…Possible reasons for this phenomenon are local or bulk changes in the rheology of the fluid due to complex dynamic interactions between the liquid and solid particles (as well as possible particle-particle interactions) or that the solids particles act to suppress turbulence within the continuous phase. Suppression or augmentation of turbulence within solid-liquid and liquid-liquid systems is an observed phenomenon which has been the studied by many workers at low dispersed phase concentrations, [28][29][30][31] although mechanistic understanding at high solids concentrations remains elusive with little study. 32 Evidence exists in the rheology data of unstable behavior at high solid loadings.…”

Section: Flow Regimesmentioning

confidence: 99%

Concentrated slurry formation via drawdown and incorporation of wettable solids in a mechanically agitated vessel

et al. 2018

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This article describes the effect of vessel configurations on the drawdown and incorporation of floating solids to prepare concentrated alumina slurries in stirred tanks. The impeller speed and power draw required to incorporate all dry powder within four seconds, N JI and P JI , are used to evaluate incorporation performance. The effect of impeller type is assessed, with pitched blade impellers proving to be the most effective across the full range of solid contents considered. At higher solids content the energy demand is shown to increase dramatically, with a 100-fold increase in energy required to add 1% w/w more solid at 50% by weight compared to 1% by weight. Analysis of impeller power numbers show this coincides with a transition from constant power number to a region where power number increases linearly with decreasing Reynolds number. Contrary to studies at low solids content, the presence of baffles is shown to inhibit drawdown.

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Section: Flow Regimesmentioning

confidence: 99%

Concentrated slurry formation via drawdown and incorporation of wettable solids in a mechanically agitated vessel

et al. 2018

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“…The concentration of triiodide (I − 3 ) in the third reaction can be measured by a UV spectrophotometer. Reaction (1) is quasi-instantaneous with a second-order rate constant k 1 at about 40 while Reaction (2) is very fast and has the same order of magnitude as the micromixing process as indicated by Fournier et al 41 The rate constant k 2 depends on the ionic strength I and will change during the micromixing process, 42 which was found to be well approximated by the following empirical relationships:…”

Section: Reaction Kineticsmentioning

confidence: 69%

Effect of hydrodynamic heterogeneity on micromixing intensification in a Taylor–Couette flow reactor with variable configurations of inner cylinder

Liu

Yang

et al. 2021

AIChE Journal

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Effect of hydrodynamic heterogeneity on micromixing intensification in a Taylor-Couette flow (TC) reactor with variable configurations of inner cylinder has been investigated by adoption of a parallel competing iodide-iodate reaction system. Two types of inner cylinder, circular inner cylinder and lobed inner cylinder (CTC and LTC), were used to generate hydrodynamic heterogeneity, focusing on the effects of the Reynolds number, the acid concentration, and the feeding time on the micromixing performance. Segregation index (Xs) was employed to evaluate the micromixing efficiency. It is revealed that Xs decreases with the increase of Reynolds number and feeding time but increases with the increase of acid concentration for both the CTC and LTC. However, the LTC does present a better micromixing performance at various operating conditions than that of the CTC as affirmed by both the experimental and computational fluid dynamics simulation results.

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“…The concentration of triiodide (I − 3 ) in the third reaction can be measured by a UV spectrophotometer. Reaction ( 1) is quasi-instantaneous with a second-order rate constant k 1 at about 10 11 Lmol -1 s -1 (Unadkat et al , 2013), while Reaction ( 2) is very fast and has the same order of magnitude as the micromixing process as indicated by . The rate constantk 2 depends on the ionic strength I (Guichardon et al , 2000) and will change during the micromixing process, which was found to be well approximated by the following empirical relationships:…”

Section: Reaction Kineticsmentioning

confidence: 92%

“…Generally, the products produced in such a system are easily analysed by using the spectrophotometric method. This method have been successfully applied for the assessment of the micromixing efficiency in stirred vessel reactors (Unadkat et al , 2013;and Lemenand et al , 2017) and in high shear mixer (Qin et al , 2017). As the use of the parallel competing reaction system has the advantages of simple control, sensitive measurement through detection of the product concentration and low toxicity of agents, the Villermaux iodide-iodate reaction system is adopted in the present study.…”

Section: Micromixing Characterization Modellingmentioning

confidence: 99%

Effect of Hydrodynamic Heterogeneity on Micromixing in a Taylor-Couette Flow Reactor with Lobed Inner Cylinder

Liu

Yang

et al. 2020

Preprint

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Effect of hydrodynamic heterogeneity on micromixing intensification in a Taylor-Couette flow reactor (TC) with variable configurations of inner cylinder has been investigated by adoption of a parallel competing iodide-iodate reaction system. Two types of inner cylinder, circular inner cylinder and lobed inner cylinder (CTC and LTC), were used to generate hydrodynamic hydrodynamic heterogeneity for comparison of the micromixing intensification, focusing on the effects of the Reynolds number of the TC reactor, the acid concentration, and the feeding time. The Segregation index (Xs) was employed to evaluate the micromixing efficiency. It was revealed that Xs decreases with the increase of Reynolds number and feeding time but increases with the increase of acid concentration for both the CTC and LTC. However, the LTC does present a better micromixing performance at various operating conditions than that of the CTC as affirmed by both the experimental and computational fluid dynamics (CFD) simulation results.

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Investigation of turbulence modulation in solid–liquid suspensions using parallel competing reactions as probes for micro-mixing efficiency

Cited by 12 publications

References 25 publications

Concentrated slurry formation via drawdown and incorporation of wettable solids in a mechanically agitated vessel

Concentrated slurry formation via drawdown and incorporation of wettable solids in a mechanically agitated vessel

Effect of hydrodynamic heterogeneity on micromixing intensification in a Taylor–Couette flow reactor with variable configurations of inner cylinder

Effect of Hydrodynamic Heterogeneity on Micromixing in a Taylor-Couette Flow Reactor with Lobed Inner Cylinder

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