sure of said second stream to a pressure greater than
said operating pressure so that the second stream
removes the treated solution from said one side of
said membrane separation means.
5. Apparatus for separating relatively pure water from an untreated aqueous solution comprising:
a housing and a semi-permeable membrane positioned in said housing, said membrane having first and second sides being adapted to permeate water through to said second side leaving a treated aqueous solution on said first side when untreated aqueous solution under a pressure in excess of the osmotic pressure of said untreated aqueous solution is introduced to said first side;
a source of untreated solution and a primary feed circuit delivering a first stream of untreated solution from said source into said housing under an operating pressure in excess of the osmotic pressure of said solution for treatment by said membrane;
means for periodically introducing a second stream of untreated solution into said housing under a pressure greater than the operating pressure of said first stream so that said second stream removes the treated solution in said housing from the first side of said membrane;
said last mentioned means includes a -secondary feed circuit comprising, a fluid storage chamber, first conduit means connecting said storage chamber to said source of untreated solution;
means for delivering untreated solution from said source 30 to said storage chamber at a pressure less than the operating pressure of said first stream of solution, a second conduit means connecting said storage chamber to said housing, valve means in said second conduit means having a closed condition for fluidly isolating said housing and said storage chamber when untreated solution is being delivered into said storage chamber and an open condition for opening communication between said housing and said storage chamber and means for transferring untreated solution from said chamber through said second conduit means to produce said second stream of untreated solution when the valve means in said second conduit means are open.
6. The apparatus as defined in claim 5, wherein said secondary feed circuit has a pump operative to deliver untreated solution from said source to said chamber when the valve means in said second conduit means are closed, and to transfer untreated solution from said chamber 50
through said second conduit when the valve means in said second conduit means are open.
7. The apparatus as defined in claim 6, wherein said pump is operative to raise the pressure of untreated solution transferred from said chamber to said housing to a pressure greater than the operating pressure of said first stream of untreated solution.
8. The apparatus as defined in claim 5, including a flexible diaphragm dividing said chamber into a pair of subchambers including a first subchamber connected by said first conduit means to said source of untreated solution and by said second conduit means to said housing; third conduit means connecting said housing and said second subchamber for the transfer of treated solution from said housing; and valve means in said third conduit means having a closed condition for fluidly isolating said housing and said second subchamber and an open condition for opening communication between said housing and said second subchamber.
9. The apparatus as defined in claim 8, including fourth conduit means connecting said second subchamber to a brine collection means so that when the pump in said secondary circuit introduces untreated solution into said first subchamber, said diaphragm flexes into said second subchamber to remove treated solution from said second subchamber through said fourth conduit means to said brine collection means.
10. The apparatus as defined in claim 9, including first check valve means in said first conduit means and second check valve means in said fourth conduit means, both of said check valve means being operative to assume a closed condition when said first and second subchambers are fluidly connected with said housing so that the pressure of the untreated solution in said secondary circuit approaches the operating pressure of the first stream of said untreated solution, and to assume an open condition when said first and second subchambers are fluidly isolated from said housing.
References Cited
UNITED STATES PATENTS
2,889,048 6/1959 Nordin 210—409
3,355,382 11/1967 Huntington 210—22
REUBEN FRIEDMAN, Primary Examiner
F. A. SPEAR, Jr., Assistant Examiner
U.S. CI. X.R.
210—136, 321, 409
