Fluid Bed Crystallizer

The fluid bed crystallizer is a patented new type of crystallizer (US pat. No. 5,523,064) specifically designed for surface cooled crystallization applications. In applications where crystals can be formed simply by cooling the feed solution, (no evaporation required) the fluid bed crystallizer should be considered.

Mechanical Design

  • Small physical size. All the separate items in a conventional shell and tube surface cooled crystallizer (crystallizer body, shell & tube heat exchanger, circulating pump, interconnecting ductwork) are combined into a single piece of equipment, eliminating the need for circulating piping; the heat exchanger and the crystallizer are combined into a single compact unit. The slurry pump is eliminated and replaced by a conventional fan.
  • Low elevation requirements. Typically 9 to 12 feet compared to 30 feet for conventional shell and tube crystallizers, little or no structural steel required.
  • Low maintenance. The only moving part is an air blower and an air damper, no pump seals which might leak.

Process Design

  • Larger crystals are produced because of the reduction in mechanical attrition and formation of nucleation of new seed crystals by eliminating the circulating pump and using air for agitation.
  • Higher liquid heat transfer coefficients are achieved with air agitation, because the liquor flow at the tube surface is more turbulent.
  • Operates at larger temperature differences between cooling medium and liquor temperature without crystal formation on the heat transfer surface. Higher temperature differences can be used because of the high turbulence at the tube surface caused by the bubbles rising through the slurry.
  • Less heat transfer surface required. Depending on the application, the effects of higher heat transfer coefficients combined with operating at larger temperature differences can reduce the required heat transfer by as much as 60%.
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