Patent ID: 7228713

Claim:
A multi-stage vacuum cooling and freezing process for solution separation, which utilizes freezing and melting to produce condensate and may be used to assist in multi-stage vacuum distillation to increase the number of stages thereof, comprising the steps of providing and combining a tower-like multi-stage vacuum cooling system and a tower-like multi-stage vacuum freezing system; setting said multi-stage cooling and freezing systems to an initial state thereof; and performing transferring of solutions, a constant temperature distilling process, and a drain-to-vacuum and freezing process to produce ice crystals in a degassed solution; wherein said multi-stage vacuum freezing system using a low-temperature solution discharged at the lowest stage of said multi-stage vacuum cooling system as an initial solution needed to perform said multi-stage vacuum freezing to save energy needed for pre-cooling, and using vapors produced in multi-stage vacuum distilling and cooling processes as condensation heat required to melt said ice crystals produced in said degassed solution; low-temperature concentrated solution and molten ice crystals produced through said multi-stage vacuum freezing process being used to cool a hot circulating solution discharged from the last stage of multi-stage vacuum distillation and to maintain the temperature of a vacuum vessel for collecting the condensate produced in said multi-stage vacuum distillation, enabling an expanded distilling temperature range and accordingly increased stages for the multi-stage distillation and increased yield of solution separable with one unit of energy.