The Crystallizer unit operation simulates crystallization processes for the manufacture of organics, inorganics, fertilizers, biochemicals and polymers. The crystallizer transforms a supersaturated solution into a mixed solid/liquid crystal slurry.
The crystallizer is modeled as a Mixed Suspension Mixed Product Removal (MSMPR) crystallizer or Continuous Stirred Tank Crystallizer (CSTC). This assumes ideal mixing in the unit and the product conditions are the same as the bulk conditions. The model also assumes that breakage or agglomeration of solid particles is negligible. A feed heat exchanger may be included in the model with recirculation if required.
The crystallization process depends on phase equilibria as well as kinetic or non-equilibrium considerations. Solid-liquid equilibrium is defined in terms of solubility, which is calculated from either the Van't Hoff equation or user-supplied solubility data.
You must select Design or Rating calculations in the Crystallizer Calculation Mode Window. In design mode, a specification is required and the volume is calculated. In rating mode, the vessel volume is defined.
The formation rate relationships are expressed as power law expressions in the Crystallizer Growth and Nucleation Rates Window. These are similar to equations for power law kinetics used for chemical reactions.
Full details of the calculation method can be found in the PRO/II Reference Manual.
The crystallizer unit can have any number of feed streams. The inlet pressure is taken to be the lowest pressure of all the feed streams.
Both an overhead and bottoms product must be specified in the Crystallizer Products Window. The bottoms contains the crystals in the solid/liquid slurry. The overhead contains any vapor generated in the unit.
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