Hydrodynamic effects on mixing and competitive reactions in laboratory reactors

Akiti, Otute; Yeboah, Agnes; Bai, Ge; Armenante, Piero M.

doi:10.1016/j.ces.2004.10.049

Cited by 18 publications

(9 citation statements)

References 10 publications

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“…The generated flow is expected to cause higher concentrations of the solution in the lower parts of the tank as compared to the upper regions. This observation clearly concurs with the experimental results performed in this work as well as conclusion of Akiti, and Bai [31], who earlier proved that the anchor impeller produces less flow and turbulence regardless of the configuration of the mixing vessel. The velocity streamlines of this impeller in (Figure 8), shows that the blades drove the fluid to the walls, which then splashed back and was directed vertically and in opposite directions toward the center of the tank.…”

Section: Cfd Post-process Analysissupporting

confidence: 93%

A Study of the Mixing Performance of Different Impeller Designs in Stirred Vessels Using Computational Fluid Dynamics

Torotwa

2018

Designs

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Design and operation of mixing systems using agitated vessels is a difficult task due to the challenge of obtaining accurate information on impeller-induced turbulence. The use of Computational Fluid Dynamics (CFD) can provide detailed understanding of such systems. In this study, experimental tests and computational fluid dynamics simulations were performed to examine the flow characteristics of four impeller designs (anchor, saw-tooth, counter-flow and Rushton turbine), in achieving solution homogeneity. The impellers were used to mix potassium sulfate granules, from which values of electrical conductivity of the solution were measured and used to estimate the distribution pattern of dissolved solid concentrations within the vessel. CFD models were developed for similar mixing arrangement using commercial software, ANSYS Fluent 18.1 solver and the standard k-epsilon (ε) turbulence model. The Multiple Reference Frame (MRF) approach was used to simulate the impeller rotation. Velocity profiles generated from the simulations were in good agreement with the experimental predictions, as well as with results from previous studies. It was concluded that, through CFD analysis, detailed information can be obtained for optimal design of mixing apparatus. These findings are relevant in choosing the best mixing equipment and provides a basis for scaling up mixing operations in larger systems.

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Section: Cfd Post-process Analysissupporting

confidence: 93%

A Study of the Mixing Performance of Different Impeller Designs in Stirred Vessels Using Computational Fluid Dynamics

Torotwa

2018

Designs

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“…Firstly, the vertical elements of the probe can act as small "baffles" in the rotating fluid, disrupting the smooth tangential flow generated by the impeller and producing an enhanced dissolution rate. This phenomenon is well known and amply described (35,36). Secondly, the presence of a single probe on only one side of the vessel introduces a small asymmetry in an otherwise symmetrical system.…”

Section: Discussionmentioning

confidence: 87%

Effect of a Fiber-Optic Probe on the Dissolution of Salicylic Acid Tablets in USP Apparatus 2

Bing¹,

Bredael²,

Armenante³

2013

Dissolution Technol.

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Fiber-optic probes permanently inserted in the dissolution medium in dissolution vessels can automate the sampling process but can also potentially affect the hydrodynamics in the vessel, possibly resulting in increased drug dissolution rates. In this work, dissolution experiments with non-disintegrating salicylic acid calibrator tablets were conducted in dissolution testing Apparatus 2 in both the presence and absence of a commercially available fiber-optic probe (Opt-Diss). Tests were conducted using tablets dropped in the medium according to USP guidelines, as well as with tablets fixed at nine positions on the vessel bottom (i.e., either centered in the vessel or placed at different off-center locations with respect to the vessel vertical centerline). The results were compared using statistical tools. In many cases, the presence of the probe resulted in slightly faster dissolution rates. The difference between the results obtained in experimental systems with the probe and those obtained with the control system without the probe depended on tablet position. Larger differences were observed when the tablets were on inner circle positions (10° off-center circle), especially when the tablets were located immediately downstream of the probe. A paired t-test as well as the difference factor (f 1 ) and similarity factor (f 2 ) were used to statistically analyze the results. In most cases, the results obtained with the inserted probe were statistically different, according to the paired t-test, from those obtained without it. It can be concluded that fiber-optic sampling probes can often result in small but measurable enhancements in the dissolution rates, which can produce appreciable variations in test results.

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“…These include process optimization, process safety evaluation, scale-sensitivity understanding, and robustness testing [1]. Reaction kinetics and model-based reactor engineering are seldom adopted for the production of pharmaceutical ingredients, even though they can be quite advantageous for process design and engineering [2][3][4][5][6][7][8][9][10][11][12]. Let alone their economical favourability, which is even more valid for complex reaction networks [2].…”

Section: Introductionmentioning

confidence: 99%

“…A suitable approach should firstly consist of the supposition of likely reaction mechanisms and choice of appropriate analytical techniques [4,5], followed by the process model construction [6] and its optimization for a given operation [7,8]. While it has been generally accepted that such an approach may also substantially reduce risks when performing the scale-up of process [9][10][11][12], the overall procedure from the underlying mechanisms to optimization is rather rare in API development. To a lesser extent, the particular aspects of model-based engineering have been adopted previously [3][4][5][6][7][8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Modelling chemical kinetics of a complex reaction network of active pharmaceutical ingredient (API) synthesis with process optimization for benzazepine heterocyclic compound

Grom¹,

Stavber²,

Drnovšek³

et al. 2016

Chemical Engineering Journal

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Hydrodynamic effects on mixing and competitive reactions in laboratory reactors

Cited by 18 publications

References 10 publications

A Study of the Mixing Performance of Different Impeller Designs in Stirred Vessels Using Computational Fluid Dynamics

A Study of the Mixing Performance of Different Impeller Designs in Stirred Vessels Using Computational Fluid Dynamics

Effect of a Fiber-Optic Probe on the Dissolution of Salicylic Acid Tablets in USP Apparatus 2

Modelling chemical kinetics of a complex reaction network of active pharmaceutical ingredient (API) synthesis with process optimization for benzazepine heterocyclic compound

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