Effect of the rate of stirring on crystal size in precipitating or salting-out systems

Nývlt, Jaroslav; Žáček, Stanislav

doi:10.1135/cccc19861609

Cited by 15 publications

(5 citation statements)

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“…We return to this point at the end of the paper. A few studies of mixing effects in semibatch crystallizers have also been reported (Nyvlt and Zacek, 1986;Pohorecki and Baldyga, 1983).…”

Section: Introductionmentioning

confidence: 99%

Effect of mixing on the precipitation of barium sulfate in an MSMPR reactorssss

Fitchett

Tarbell

1990

AIChE Journal

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The effect of mixing intensity (power input) on the precipitation/ crystallization of barium sulfate in a two-feedstream (sodium sulfate, barium chloride) continuous stirred-tank crystallizer with mixed product removal was investigated through experiments and companion mathematical models. Crystal growth rate and nucleation rate were very sensitive to mixing intensity, with growth rate increasing eightfold and nucleation rate decreasing 100-fold as power input per unit mass was increased from 0.001 to 0.73 m2/s3 (0 to 1,200 rpm stirrer speed). Experimental results at high feed concentration were accurately described by a model accounting for homogeneous nucleation and kinetic growth of particles as well as turbulent mass transfer to particles and turbulent micromixing of feedstreams. The principal mixing effect was due to particle mass transfer, not micromixing. Experiments at low feed concentration were more difficult to model because of a more complex nucleation mechanism and altered particle morphology.

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“…We return to this point at the end of the paper. A few studies of mixing effects in semibatch crystallizers have also been reported (Nyvlt and Zacek, 1986;Pohorecki and Baldyga, 1983).…”

Section: Introductionmentioning

confidence: 99%

Effect of mixing on the precipitation of barium sulfate in an MSMPR reactorssss

Fitchett

Tarbell

1990

AIChE Journal

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“…However, no influence of stirring speed on the mean size of nanoparticles formed was observed in the experimental study of drowning out of ethylcellulose . For the crystallization of griseofulvin by compressed carbon dioxide as an antisolvent, and the salting out of KAl(SO 4 ) 2 , it was experimentally observed that the mean crystal size decreased with increasing stirring rate. Such opposing observations can be attributed to the different kinetics of each individual system.…”

Section: Resultsmentioning

confidence: 95%

“…6,7 Various experimental studies of antisolvent crystallization in an agitated semibatch vessel indicate that the crystal size distribution (CSD) depends strongly on the operating conditions, such as agitation rate, mode of addition (direct or reverse), addition rate, solvent composition, and size of the crystallizer. 5,[8][9][10][11][12][13][14][15][16][17][18][19][20] The polymorphic or pseudopolymorphic form can also depend on the operating conditions. [21][22][23][24][25][26] Most variations in the operating conditions have a direct influence on the mixing of the antisolvent and the solution, which affects the localized supersaturation and, thus, the crystal product.…”

Section: Introductionmentioning

confidence: 99%

“…Antisolvent crystallization is used widely in the pharmaceutical industry. This enables the crystallization of thermally sensitive pharmaceuticals without introducing large temperature changes in the process. , Current state-of-the-art crystallization technology such as impinging jet crystallizers utilizes high-intensity mixing of the antisolvent and the solution to produce crystals smaller than 25 μm with improved bioavailability and increased dissolution rates, − which, at the same time, reduces the undesirable effects of milling. , Various experimental studies of antisolvent crystallization in an agitated semibatch vessel indicate that the crystal size distribution (CSD) depends strongly on the operating conditions, such as agitation rate, mode of addition (direct or reverse), addition rate, solvent composition, and size of the crystallizer. ,− The polymorphic or pseudopolymorphic form can also depend on the operating conditions. − …”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Simulation of Mixing Effects in Antisolvent Crystallization Using a Coupled CFD-PDF-PBE Approach

Woo

Tan

Chow

et al. 2006

Crystal Growth & Design

116

104

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Antisolvent crystallization is widely used in the production of pharmaceuticals. Although it has been observed experimentally that the crystal size distribution is strongly influenced by the imperfect mixing of the antisolvent with the solution, these effects have not been adequately quantified. In this work, a turbulent computational fluid dynamics (CFD) code was coupled with a multienvironment probability density function (PDF) model, which captures the micromixing in the subgrid scale, and the population balance equation, which models the evolution of the crystal size distribution. The population balance equation (PBE) was discretized along the internal coordinate using a high-resolution central scheme. The presence of solids was addressed by treating the suspension as a pseudo-homogeneous phase with a spatial variation in the effective viscosity. This coupled CFD-PDF-PBE algorithm was applied to an antisolvent crystallization process in an agitated semibatch vessel, where the rising liquid level was modeled by a dynamic mesh. The effects of agitation speed, addition mode, and scale-up on the local primary nucleation and size-dependent growth and dissolution rates, as well as the crystal size distribution, were numerically investigated.

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“…Various experimental studies of antisolvent crystallization in an agitated semibatch vessel indicate that the crystal size distribution (CSD) depends strongly on operating conditions such as agitation rate, mode of addition (direct or reverse), addition rate, solvent composition, and size of the crystallizer [3,[19][20][21][22][23][24][25][26][27][28][29][30][31]. The polymorphic or pseudopolymorphic form can also depend on the operating conditions [32][33][34][35][36][37].…”

Section: Introductionmentioning

confidence: 99%