Calculation for continuous crystallizers
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-
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).