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# Calculation for continuous crystallizers

## Cooling

We can deduce the composition Xs of the exit liquor by:

• - knowing the composition Xe and the temperature Te of the supply, that is at the entry, and;
• - providing ourselves with the mass of crystals to be produced WE (Xe-

Xs).

The temperature T* of this liquor must correspond to the exiting saturation equilibrium.

Thus, we know the entry temperature Te and exit temperature T* of the mass. We can deduce the thermal cooling power to be provided Q:

If the difference in concentration between equilibrium X* and the level of real solute on exit Xs is assumed to be zero, experience shows that this hypothesis is typically verified.

Q: thermal power (W)

Te: entry temperature of the mother liquor (degrees Celsius)

T*: exit temperature of the slurry (degrees Celsius)

WE: flow of water accompanying the product to be crystallized (kg.s-1)

Xe: level of solute in the mother liquor on entry (kg.kg-1)

Xs: level of solute on exit (kg.kg-1)

CE: thermal capacity of water (J.kg-1.°C-1)

CS: thermal capacity of the product to be crystallized (J.kg-1.°C-1)

Л,,: crystallization heat of the product (J.kg-1).

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