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Keywords:

  • precipitation;
  • barium sulfate;
  • rotating liquid film reactor;
  • computational fluid dynamics;
  • population balance;
  • crystal size distribution

Abstract

Precipitation of nanosized barium sulfate in a rotating liquid film reactor (RLFR) has been investigated experimentally and through simulations based on the computational fluid dynamics technique including the population balance equation coupled with the Navier–Stokes equations, renormalization group k–ε model equations, and species transport equations. A comparative experiment was carried out involving conventional precipitation in a flask. The structure of the precipitate was identified by powder X-ray diffraction (PXRD), which showed that the crystals obtained using the RLFR were smaller in size than those obtained in the flask. Transmission electron microscopy (TEM) images demonstrated that the crystals produced by the two different processes had different morphologies. Further detailed experiments involving varying the operating parameters of the RLFR were performed to investigate the effects on crystal size distribution (CSD). Increasing the speed of the rotor in the RLFR in the range 1000–5000 rpm or increasing the rotor-stator gap in the range 0.1–0.5 mm resulted in a decrease in particle size and narrower particle size distributions. The simulation results suggested that turbulent effects and reaction processes in the effective reactor space were directly related to rotor speed and rotor-stator gap. The simulated volume weighted mean diameter and CSD of particles of barium sulfate were almost identical to the corresponding experimental results obtained using TEM and laser particle size analyzer. The effects of other parameters such as the Kolmogorov scale and competition between induction time and mixing time are also discussed. © 2009 American Institute of Chemical Engineers AIChE J, 2009