Antisolvent process for treating liquids that include high total dissolved solids

摘要

The present invention provides a low energy alternative to conventional thermal/evaporation processes for “zero liquid discharge” treatment of strong saline brines. The products of the process include a salt-free liquid and solid salt. In particular, an antisolvent can be mixed with liquids containing high total dissolved solids. The mixture can be chilled, whereby solid salt is precipitated and separated from the mixture at near ambient temperature leaving a mixed liquor. The antisolvent can be selected from a class of organic compounds that form solutions with salt brines that exhibit a critical solution temperature lower than a critical solution temperature of the salt brines alone. The mixed liquor can be heated to a temperature above its lower critical solution temperature to produce an antisolvent liquid phase for recycle to the process. Finally, a reduced salinity aqueous phase can be polished by reverse osmosis or other conventional technology to produce clean water for discharge or beneficial use.

主权项

1. A system for treating a high total dissolved solids liquid, the system comprising:
a temperature-reduction vessel that receives a high TDS liquid and an antisolvent such that a mixture is formed inside the temperature-reduction vessel at a temperature below a critical solution temperature of the mixture, thereby causing precipitation of salt and production of a salt slurry; a separator receiving the salt slurry and separating the salt slurry into a mixed liquor and a salt cake; a heating vessel receiving the salt cake and applying heat to the salt cake to produce dry salt and a mixed vapor; a phase separator receiving a recuperated mixed liquor, a temperature of the recuperated mixed liquor in the phase separator being greater than a lower critical solution temperature of the recuperated mixed liquor, and thus causing the recuperated mixed liquor to separate into an antisolvent phase and an aqueous phase; a recuperator receiving the antisolvent phase and the mixed liquor and indirectly transferring heat from the antisolvent phase to the mixed liquor thus turning the mixed liquor into the recuperated mixed liquor; a heater that applies heat to the recuperated mixed liquor such that the temperature of the recuperated mixed liquor in the phase separator is greater than the lower critical solution temperature of the recuperated mixed liquor; and a fluid path between the phase separator and the temperature-reduction vessel for passing antisolvent back into the temperature-reduction vessel, wherein the phase separator is coupled to the heating vessel, the heater, and the recuperator.