We know the composition and temperature of the supply, and provide ourselves with the crystal mass to be produced. The operating pressure of the crystallizer is given.
We can thus deduce the saturation temperature T* of the mother liquor for the entry concentration.
During vaporization, concentration does not change as the slurry temperature remains constant and equal to T , since the pressure remains constant and equal to steam pressure n at TE. The difference between T* and TE rarely exceeds 5°C, as a general rule. This difference is the boiling delay.
Thus, the thermal heating power Q is written as:
This power is the total of the heat corresponding to the preheating and the water vaporization heat.
Q: thermal power (W)
Te: entry temperature of the mother liquor (°C)
T*: slurry exit temperature (°C)
WEe: water flow on entry (kg.s-1)
WEs: water flow on exit (kg.s-1)
CE: thermal capacity of water (J.kg-1.°C-1)
CS: thermal capacity of the product to crystallize (J.kg-1.°C-1)
ЛE : vaporization heat of water (J.kg-1)
X: mass ratio of the product (kg.kg-1).