The vacuum freezing multiple phase transformation process

Abstract

Bench-scale experiments have been completed on the Vacuum Freezing Multiple Phase Transformation (VFMPT) Process disclosed in U.S. Patent Number 4,505,728. The VFMPT Process can be used for desalination, industrial solution concentration, water reuse and waste treatment. The key steps are vacuum evaporative freezing, sub-triple point vapor desublimation, desublimate melting, super-triple point vapor generation, crystal-washing and crystal-melting. These operations have been demonstrated with rate information collected. Construction of an integrated prototype system is nearly complete with testing of the heart of the system complete. A preliminary economic analysis shows two results (1) the VFMPT Process will be more competitive than reverse osmosis and distillation/evaporation in the range of solute concentrations represented by sea water desalination both in terms of equipment cost and operating cost and (2) in many applications at higher concentrations, the VFMPT Process is expected to dominate because reverse osmosis membranes cannot be operated at the high pressures required.