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Production of calcium chloride (CaCl2) and aqueous ammonia (NH4
+) from the
ammonia chloride (NH4Cl) stream in the Solvay process was studied using an
Ammonia Recovery Tower to produce 29 wt % aqueous ammonia and 40 wt % CaCl2
from the process feed stream or the tower bottoms stream. OLI, a thermodynamic
equilibrium process simulator, modeled four different distillation and evaporation
configurations. Using a feed rate of 2300 kg/hr of 5.8 wt % NH4Cl, each configuration
produced 1360 kg/hr of 30 wt % aqueous ammonia and 770 kg/hr to 4130 kg/hr of 40
wt % CaCl2. A bench scale evaporator with 1.0 L of working volume was used to
produce 40 wt % CaCl2 solutions. A steady state production of 40 wt % CaCl2 was
achieved in the laboratory using model feed solutions, Ammonia Tower process feed
and processed Ammonia Tower bottoms. In general, there was a close agreement
between the simulation and the experimental results. In both the experimental trials
and modeling predictions, the 40 wt % CaCl2 solution that used the processed
Ammonia Tower bottoms as the evaporator feed solution, contained a lower
concentration of ammonia than the 40 wt % CaCl2 solutions that used the Ammonia
Tower feed. |
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