Abstract
In this paper, the influence of hydrodynamic conditions in Kenics static mixer, which acts as a multifunctional reactor, on precipitation kinetics of barium sulfate is investigated. The investigated range of the Reynolds number varied between 500 and 5000, which covered both laminar and turbulent flow regimes. In all experiments, the relative supersaturation was maintained at the constant level (σ = 205). The obtained precipitate was collected and used for crystal size distribution (CSD) determination. On that basis, the kinetic parameters of the process were calculated using the mixed suspension mixed product removal (MSMPR) mathematical model of the process. It was found that for the whole investigated range of Reynolds number, the mixing conditions were satisfactory. CSD analysis showed that in the laminar regime, a clear tendency in crystal behavior could not be noticed. However, during the analysis of the turbulent regime, the presence of a critical Reynolds number was noticed. Above this value, there is a change in the flow pattern, which results in a change of kinetic parameters (B, G), as well as manifests in a form of a decrease in the value of mean diameters of crystals. The flow pattern change is caused by the geometry of the reactor’s inserts.
Highlights
Precipitation is a very rapid process accomplished by mixing reactants under appropriate process conditions
There is a change in the flow pattern, which results in a change of kinetic parameters (B, G), as well as manifests in a form of a decrease in the value of mean diameters of crystals
There is no information on experimental measurements of barium sulfate precipitation in a static mixer of Kenics geometry
Summary
Precipitation is a very rapid process accomplished by mixing reactants under appropriate process conditions. The crystallization with a chemical reaction, such as in the case of all crystallization processes, consists of three stages: supersaturation generation, nucleation, and crystal growth They may be accompanied by additional (usually undesired) phenomena influencing the final crystallization product quality. There is no information on experimental measurements of barium sulfate precipitation in a static mixer of Kenics geometry. As the parameter that allows one to compare precipitation kinetics in reactors of various geometry induction time was selected. Tested precipitation of barium sulfate in spinning disc reactor achieving induction time approximately equal to 2.5 × 10−3 s for the concentration of 1 × 10−5 mol/dm. Concluding, experimental investigation of barium sulfate precipitation in Kenics static mixer used as a multifunctional reactor was never reported up till now. The attempt to describe the precipitation of barium sulfate in the reactor of the described geometry was made
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