Apparatus and method for concentration of liquid bearing solids by freezing

Claim 2

The process according to claim 1 in which the solution and crystals discharged from said second heat exchanger rise upwardly through a constricted discharge conduit and then expand into a vertical conduit of substantially greater cross-sectional area than said discharge conduit to permit said frozen crystals to rise above the concentrated solution solely by buoyancy to effect draining of said concentrated solution therefrom as said column of solution and crystals rise.

Claim 3

The process according to claim 1 which the rate of initial delivery of the solution solely controls the rate of discharge of concentrated solute.

Claim 4

Apparatus to form a concentrated solution of a solute from a solution thereof in a solvent comprising in combination, a. means to feed such solution at a predetermined rate from a source thereof, b. an initial heat exchanger to receive said solution from said feed means and reduce the temperature thereof to a range of temperature below the freezing temperature of the solvent to form seed crystals of said solvent upon the walls of said exchanger and including scraper means operable to remove said crystals therefrom and intermix them with said solution, said initial heat exchanger having a discharge conduit of predetermined diameter, c. a secondary heat exchanger of substantially greater capacity than said initial heat exchanger and having an inlet connected to said discharge conduit of said initial heat exchanger to receive therefrom said solution containing seed crystals, and including means to maintain the temperature of said secondary heat exchanger substantially below that of said initial heat exchanger substantially below that of said initial heat exchanger to promote the growth of seed crystals into larger crystals of solvent, d. scraper means movable to agitate and extensively recirculate said solution and seed crystals within said secondary heat exchanger and means to operate said scraper means at reasonably rapid speed continuously to produce growth of larger crystals of solute at said lower temperature range while agitated within said solution, e. discharge means for said secondary heat exchanger operable to permit concentrated solute and said larger crystals formed therein to flow therethrough, f. a recirculating conduit of larger diameter than said discharge conduit of said initial heat exchanger connected directly between said inlet and discharge means of said secondary heat exchanger and operable to pass a mixture of solution and frozen crystals from said discharge means back to said inlet for further circulation therethrough to increase the size of the crystals in said solution before discharging the same from said secondary heat exchanger, g. a circulating pump within said recirculating conduit and operable to cause constant circulation and agitation of the solution and crystals unidirectionally through said heat exchanger to enhance the growth of larger crystals therein without aeration and foaming, h. a vertical column extending upward from said secondary heat exchanger and connected directly at the bottom thereof to said discharge means of said secondary heat exchanger and operable to permit a column of said crystals and solution to rise therein and permit said crystals to rise by buoyancy above the level of the solution is said column, i. means to drain said concentrated solute from said column of crystals, and j. means to remove the upper portion of said column of crystals therefrom.

Claim 5

The apparatus according to claim 5 in which said discharge conduit of said initial heat exchanger is connected to and discharges into said recirculating conduit adjacent the inlet of said secondary heat exchanger and said vertical column having an inlet conduit at the bottom thereof connected to and communicating with said recirculating conduit adjacent said discharge means of said secondary heat exchanger.

Claim 6

The apparatus according to claim 6 in which said inlet conduit of said vertical column is of a smaller diameter than said recirculating conduit.