Multi-stage counter-current concentrating method

A multiple-stage, counter-current, freeze concentration system for concentrating an aqueous feed liquid to produce a concentrated product comprising:

• a first stage including:
• (a) at least one scraped surface heat exchanger for producing continuously a slurry of said feed liquid and seed crystals of an effective diameter less than 10 microns;
• (b) recrystallizing means including a recrystallization vessel connected to said heat exchangers of said first stage for continuously receiving said slurry and growing crystals to form a slurry with crystals larger than said seed crystals;
• (c) means for removing a portion of the liquid within said vessel of said first stage and recirculating a part of the portion to the heat exchanger of said first stage;
• (d) at least one wash column for receiving said slurry from said vessel of said first stage and separating the ice and liquid;
• (e) means for mixing the liquid separated by said wash column of said first stage with said feed liquid and supplying the mixture to said heat exchanger of said first stage;
• and
• (f) means for withdrawing the liquid in said vessel of said first stage as an intermediate concentrated product;
• and
• a second stage including:
• (a) at least one scraped surface heat exchanger for producing a slurry of said intermediate product and seed crystals of an effective diameter of less than 10 microns;
• (b) recrystallizing means including a recrystallization vessel connected to said heat exchangers of said second stage for continuously receiving said slurry and growing crystals to form a second slurry with crystals larger than said seed crystals;
• (c) means for removing a portion of the liquid within said vessel of said second stage and recirculating a part of the portion to the heat exchanger of said second stage;
• (d) means for removing said second slurry from said vessel of said second stage;
• (e) means for supplying at least the ice crystals in the second slurry to the vessel of said first stage so that at least substantially all of the seed crystals in said vessel of said first stage melt and reform on the crystals from said second stage;
• and
• (f) means for withdrawing the liquid in said vessel of said second stage as said concentrated product.

A method of concentrating an aqueous beverage feed liquid to produce a concentrated product comprising:

• forming a first slurry of seed ice crystals and liquid including said feed liquid;
• supplying said first slurry to a first recrystallization vessel to grow larger crystals therein;
• separating a portion of the liquid in said first vessel from the larger crystals therein and adding at least a part of the separated liquid to said first feed liquid;
• removing said slurry with said larger crystals from said recrystallization vessel and separating the larger crystals in the slurry from the liquid;
• removing a portion of the liquid from said first vessel and adding at least a part thereof to said feed liquid before forming said first slurry of seed crystals;
• forming a second slurry of seed ice crystals and liquid from said first vessel;
• supplying said second slurry to a second recrystallization vessel to grow larger crystals therein;
• removing a portion of the liquid from said second vessel and adding at least a part thereof to liquid from said first vessel before forming said second slurry;
• and
• supplying the larger crystals from said second vessel to said first vessel so that at least substantially all said seed crystals therein melt and reform on said larger crystals from said second vessel.