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[Shama]

Does chemcad has a default unitop that I can use as a crystallizer. I am using a separator with a saline stream (contains Na+, Cl- and water) and two outlet stream, one containing only water and the other containing Na+ and Cl-. My feed is a electrolyte solution containing the compounds I mention (5% Nacl and 95% WATER). I am trying to calculate the exergy lost in the process using the entropy and enthalpy information. My calculation does not give a reasonable answer ( exergy loss is negative).

Can anyone please help to design a crystallization unit in chemcad. I only conisdered a separator. Do I need to consider anything else with separator unit or there is a unitOP for this.

Please help.


Thanks

[wojtar]

There is a unitop "Crystallizer (CRYS)" in CHEMCAD.
I heve ever used it -> can't give any advice.

This is from CHEMCAD help section:

"The CRYS module can be used to simulate crystallization or melting processes by cooling or heating. It can also be used as a dissolver where a second solvent stream is added to maintain the outlet stream at a desired concentration level.
The CRYS module has two inlets and two outlets. The second inlet would normally contain a solvent. The first outlet contains the vapor product, if any, and the second outlet contains the crystallized mix.
The CRYS module solves the material and energy balances around a general-purpose crystallizer or dissolver. Solids formation or solution may be by evaporation, liquid addition, or temperature change. Crystallization must be defined by a component equation and a solubility table."