Crystallization

Praj offers dryers and crystallization which is a key componentof ZLD solutions. Crystallizers are thermal evaporators that can be driven by either steam or mechanical vapor compression.

Forced Circulation Crystallizers


Last effect of multi-effect evaporator acts as a crystallizer, in which effluent is concentrated above the solubility of salt (super saturation) and then supersaturated salt solution is fed to the thickener or settling tank. Low rpm agitator is provided to ensure suspension of salt in the tank.

This mother liquor and crystals are fed to continuous type pusher centrifuge, after pusher centrifuge dry salts are collected and mother liquor is recycled back to multi-effect evaporation system for further concentration. Distillate recovered from the process is suitable for reuse depending on the feed properties.

Chilling Crystallizers

This is a selective type of crystallizer in which liquid effluent is concentrated up to certain required concentration and then fed to thickener. This thickener is equipped with jacketed chilling system, as solubility of salt decreases with decrease in temperature. As temperature decreases, salt crystallizes.

Advantages

  • Continuous operation
  • Best suitable for mixture of crystalline salts
  • lower operating cost