Cross current staged reverse osmosis

Patent metadata

Field	Value
Publication number	US-2017349465-A1
Application number	US-201715612570-A
Country	US
Kind code	A1
Filing date	Jun 2, 2017
Priority date	Jun 6, 2016
Publication date	Dec 7, 2017
Grant date	—

Abstract

Systems and processes for purifying and concentrating a liquid feed stream are disclosed. In the systems, the concentrated liquid output from the high pressure side of a reverse osmosis stage is used as the draw solution in the low pressure side of the reverse osmosis stage in a configuration called osmotically assisted reverse osmosis. This reduces the osmotic pressure differential across the membrane, permitting high solute concentrations to be obtained, hastening the purification of the liquid. Reduced system pressures are also obtained by arranging multiple osmotically assisted reverse osmosis stages in a cross-current arrangement. Overall system energy consumption is reduced compared to conventional thermal processes for high concentration streams.

First claim

1 - 20 . (canceled)

21 . A system for purifying a liquid feed stream to obtain a permeate, comprising:
(a) an initial reverse osmosis stage having: a high pressure side with a high pressure side inlet for receiving the liquid feed stream and a high pressure side outlet for outputting a recycle stream and a concentrate stream, and a low pressure side with a low pressure side inlet for receiving the recycle stream from the high pressure side outlet, and a low pressure side outlet for outputting a diluted stream; (b) an intermediate section having one or more intermediate reverse osmosis stages arranged in series, wherein each intermediate stage has: a high pressure side with a high pressure side inlet and a high pressure side outlet, a low pressure side with a low pressure side inlet and a low pressure side outlet, a recycle stream and a concentrate stream exiting the high pressure side outlet, the recycle stream being sent to the low pressure side inlet, and an exit stream exiting the low pressure side outlet; and wherein the intermediate section receives the diluted stream from the initial reverse osmosis stage and outputs a purified stream; and (c) a final reverse osmosis stage having: a high pressure side having a high pressure side inlet for receiving the purified stream and a high pressure side outlet for outputting a reject stream, and a low pressure side that outputs the permeate.

22 . The system of claim 21 , wherein the reject stream of the final reverse osmosis stage is combined with the diluted stream from the initial reverse osmosis stage and received by the intermediate section.

23 . The system of claim 22 , further comprising a pressurizing means for increasing the pressure of the diluted stream.

24 . The system of claim 21 , wherein the reject stream of the final reverse osmosis stage is combined with the liquid feed stream and received by the initial reverse osmosis stage.

25 . The system of claim 21 , further comprising a pressure reduction device through which at least the recycle stream of the initial reverse osmosis stage passes for reducing a pressure of the recycle stream.

26 . The system of claim 21 , further comprising an energy recovery device at the high pressure side outlet of each intermediate reverse osmosis stage.

27 . The system of claim 21 , further comprising a feed pump for pressurizing the liquid feed stream received by the initial reverse osmosis stage, an interstage pump for pressurizing the diluted stream that is received by the intermediate section, and a final pump for pressurizing the purified stream received by the final reverse osmosis stage.

28 . The system of claim 21 , wherein the intermediate section has a first intermediate reverse osmosis stage and a second intermediate reverse osmosis stage,
the first intermediate reverse osmosis stage receives the diluted stream from the initial reverse osmosis stage, the high pressure side of the second intermediate reverse osmosis stage receives the exit stream of the first intermediate reverse osmosis stage, the purified stream is the exit stream of the second intermediate reverse osmosis stage; and the reject stream of the final reverse osmosis stage is combined with the exit stream of the first intermediate reverse osmosis stage and received by the second intermediate reverse osmosis stage.

29 . The system of claim 21 , further comprising a means for pretreating the liquid feed stream upstream of the initial reverse osmosis stage.

30 . The system of claim 29 , wherein the means for pretreating the liquid feed stream includes a capacitive deionization system or a forward osmosis system.

31 . The system of claim 30 , further comprising a sonication system for receiving a concentrate from the capacitive deionization system.

32 . The system of claim 21 , wherein the initial reverse osmosis stage has a plurality of initial reverse osmosis modules, and the low pressure side outlet of each initial reverse osmosis module outputs a yield stream, the yield streams being combined to form the diluted stream.

33 . The system of claim 32 , wherein for each initial osmosis reverse module, an output stream exiting the high pressure side outlet is split to form a recycle stream that is fed to the low pressure side outlet.

34 . The system of claim 33 , wherein the recycle stream passes through a valve or energy recovery device prior to being fed to the low pressure side outlet.

35 . The system of claim 21 , wherein the intermediate section has a plurality of intermediate reverse osmosis stages, and the low pressure side outlet of each intermediate reverse osmosis stage outputs a yield stream, the yield streams being combined to form the purified stream.

36 . The system of claim 35 , wherein for each intermediate osmosis reverse stage, an output stream exiting the high pressure side outlet is split to form a recycle stream that is fed to the low pressure side outlet.

37 . The system of claim 36 , wherein the recycle stream passes through a valve or energy recovery device prior to being fed to the low pressure side outlet.

38 . The system of claim 21 , wherein the initial reverse osmosis stage has a plurality of initial reverse osmosis modules, and the low pressure side outlet of each initial reverse osmosis module outputs a yield stream, each yield stream being sent to a separate permeate concentration stage that outputs a concentrate stream and a permeate stream.

39 . The system of claim 21 , wherein the intermediate section has a plurality of intermediate reverse osmosis stages, and the low pressure side outlet of each intermediate reverse osmosis stage outputs a yield stream, each yield stream being sent to a separate permeate concentration stage that outputs a concentrate stream and a permeate stream.

40 . The system of claim 21 , further comprising a pressure retarded osmosis stage having a high pressure side and a low pressure side,
wherein the high pressure side of the pressure retarded osmosis stage receives a high pressure concentrate stream and outputs a high pressure diluate; wherein the low pressure side of the pressure retarded osmosis stage receives a dilute solution and outputs a concentrated solution; and wherein the high pressure concentrate stream is produced by pressurizing at least one of (a) the concentrate stream of the initial section and (b) the concentrate stream of the intermediate section.

41 . The system of claim 40 , wherein the high pressure diluate feeds a pressure exchanger that produces the high pressure concentrate stream.

42 . The system of claim 40 , wherein the high pressure diluate feeds an energy recovery device.

43 . The system of claim 40 , wherein the pressure retarded osmosis stage is operated so that fluid flow through the high pressure side and the low pressure side is counter-current or co-current.

Assignees

• Battelle Memorial Institute

Inventors

• Blohm Kurt
• Peterson Richard
• Lane Ann E
• Winecki Slawomir
• Argumedo Darwin

Classifications

• B01D2313/243

  Pumps · CPC title

• C02F1/4691

  Capacitive deionisation · CPC title

• C02F2103/08

  Seawater, e.g. for desalination · CPC title

• B01D2315/10

  Cross-flow filtration · CPC title

• B01D2311/2684

  Electrochemical processes · CPC title