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Chemical Engineering and Processing, Vol.37, No.2, 207-213, 1998
Eutectic freeze crystallization : Application to process streams and waste water purification
Two case studies are presented using eutectic freeze crystallization (EFC) as an alternative for evaporative crystallization : a 7.8 ton day(-1) 35 w% aqueous sodium nitrate and a 24 ton day(-1) 12 w% copper sulfate stream. The proposed crystallizer is a cooled disk column crystallizer (CDCC), using indirect cooling for heat transfer. in single stage operation, the formed ice crystals are used to pre-cool the feed stream. A two stage refrigeration unit utilizes the formed ice crystals in the condensation of refrigerant. Expressed as a thermal equivalent energy requirement, EFC requires 1282 kJ kg(-1) NaNO3 and 1037 kJ kg(-1) CuSO4 . 5H(2)O. Compared to conventional multi-step evaporation, the energy reductions are 30% for sodium nitrate and 65%, for copper sulfate.