Effect of impeller design and power consumption on crystal size distribution

Abstract

in Wiley Online Library (wileyonlinelibrary.com) Crystallization processes in a 500 mL stirred tank crystallizer with computational fluid dynamics (CFD) and population balances toward estimating how crystal size distributions (CSDs) are influenced by flow inhomogeneities was explored. The flow pattern and CSD are presented here though extensive phase Doppler particle analyzer measurements and CFD predictions for three different impeller designs (disc turbine, pitched blade turbine, and Propeller) and each rotated at three different speeds (2.5, 5, and10 r/s). As crystallization processes in practice could involve break-up and aggregation of crystals, some selected break-up and aggregation kernels are incorporated. Extensive comparison of simulations with experimental data showed consistent trends in the proper quantitative range. An attempt has also been made to develop scaling laws: (a) mean particle size with average power consumption per unit mass and (b) particle-size distribution with the turbulent energy dissipation distribution.

Study on effect of process parameters and mixing on morphology of ammonium diuranate

“…However, many times these agglomerates may undergo breakage to smaller agglomerates due to impeller shear. A production process, having high levels of both growth and nucleation result in a very broad crystal size distribution (CSD), which is undesirable from a downstream handling perspective [5]. Therefore, controlling supersaturation profile inside the crystallizer over the entire time of crystallization is expected to control the levels of nucleation, crystal growth, agglomeration and breakage, thereby controlling the morphology and crystal size distribution.…”

“…However, the stirred tanks are the most commonly used equipment in reactive crystallization. Parameters like reactor and impeller shapes, aspect ratio of the reactor vessel, number, type, location and size of impellers, degree of baffling, etc., provide effective handles to control the performance of stirred reactors [5]. In baffled stirred vessels, flow generated by the rotating impeller interacts with stationary baffles and generates complex, three-dimensional, recirculating turbulent flow.…”

Design and Hydrodynamic Characterization of a Draft Tube Baffle Tank for Lab‐Scale

“…In this work, two types of stirrers are considered, propeller and blade stirrer, each with three blades as common for crystallization applications , . If an ideal ratio of stirrer diameter d R to draft tube diameter is to be achieved, which is d R / d dt > 0.89 , a distance of 2 mm between draft tube and stirrer is required.…”

Optimization of Chemical Processes by the Hydrodynamic Simulation Method (HSM)

“…The motion of the fluids generates turbulent flow that plays key role in the momentum, heat and mass transfer during the operation of the reactor. Motion of fluids in a stirred reactor is provided by the rotation of an impeller, this source of motion in fluids also known as mixing [19]. There are crucial mixing parameters in different type of reaction and they can be calculated by VisiMix simulation tool [20].…”