Method and system for performing a batch reverse osmosis process using a tank with a movable partition

Abstract

A reverse osmosis system and method of operating the same includes a membrane housing comprising a reverse osmosis membrane therein. The membrane housing has a feed fluid input, a brine outlet and a permeate outlet; The system further includes a charge pump, a plurality of valves and a tank having a volume comprising a movable partition dividing the volume into a first volume and a second volume. The plurality of valves selectively couples the charge pump to the first volume or the second volume and the brine outlet to the second volume or the first volume respectively.

Description

METHOD AND SYSTEM FOR PERFORMING A BATCH REVERSE OSMOSIS PROCESS USING A TANK WITH A MOVABLE PARTITIONTECHNICAL FIELD

[0001] The present disclosure relates generally to reverse osmosis systems, and, more specifically, to a method and system for using separates volumes to enable a continuous process. This application claims priority to United States Provisional Application No. 63 / 659,069 filed under 35 U.S.C. § 111(b) on June 12, 2024, the disclosure of which is incorporated herein by reference in its entirety.BACKGROUND

[0002] The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

[0003] Reverse osmosis systems typically use one or more membrane housings that have one or more membranes therein that are used to extract an essentially pure fluid from a solution. The desalination reverse osmosis membranes receive feed fluid from brackish or sea water and extract fresh water therefrom. Fresh water is extracted or separated when the pressure of the feed fluid exceeds the osmotic pressure of the fluid which allows permeate or product fluid to cross the semi-permeable reverse osmosis membrane. The fluid that is left on the input side to the membrane becomes higher in salt concentration because fresh water that travels through the membrane does not include the salt. The water that passes through the membrane is referred to as a permeate. The pressure required to produce fresh water is proportional to the concentration of the total dissolved solids (TDS) in this feed solution within the reverse osmosis housing. For typical ocean water, the concentration is about 35,000 parts per million (ppm) and the corresponding osmotic pressure is about 450 pounds per square inch (psi) (3,102 kPa). For 70,000 ppm feed fluid, the osmotic pressure approximately doubles to 900 psi (about 6,205 kPa). A typical seawater reverse osmosis system uses a series of membranes that recover up to about 45% of the fresh water and generate about 55% concentrate brine from the original volume of seawater. The net driving pressure (NDP) equals the feed pressure minus the osmotic pressure. The net driving pressure is the pressure energy available to drive pure fluid across the membrane.

[0004] Referring now to Figure 1, a membrane channel 10 is illustrated between two membrane sheets 12. The channel 10 includes an inlet 14 and an outlet 16. An amount of permeate 18 represented by the droplets has permeated from the channel 10 through the membrane sheets 12. As the feed fluid that enters the inlet 14 and progresses through the membrane channel 10, the concentration of dissolved solids increases as the permeate 18 is extracted. The higher number of droplets of permeate 18 toward the inlet 14 indicate that permeate production is higher toward the inlet 14 and decreases toward the outlet 16. Because of the increasing totaled dissolved solids and the corresponding reduction in the net driving pressure, less permeate is extracted from the channel 10.

[0005] Referring now to Figure 2, the relationship of the feed pressure, osmotic pressure, the feed total dissolved solids, the permeate rate and the net driving pressure is illustrated for a membrane channel of a reverse osmosis system with about 45% recovery handling of the seawater. As is illustrated, the feed pressure is about 860 psi (5929 kPa) and loses about 10 psi (69 kPa) over the life of the channel. The osmotic pressure at the start of the channel is about 450 psi (3, 100 kPa) and rises to about 820 psi (5653 kPa) due to the increase in total dissolved solid of the feed. The feed total dissolved solid begins at about 35,000 ppm and rises to about 63,000 ppm at the end of the channel. The net driving pressure begins at about 500 psi (3450 kPa) and decreases to about 50 psi (350 kPa). The permeate flow rate decreases to negligible at the end of the channel 10.

[0006] Referring now to Figure 3, a batch reverse osmosis system 30 is illustrated. The batch reverse osmosis system 30 is used to treat a volume of feed fluid. The process repeatedly passes an initial volume of feed fluid through the reverse osmosis membranes and removes permeate until a desired level of concentration of total dissolved solids or a specific amount of permeate has been produced. The batch reverse osmosis system 30 has a feed reservoir or source 32 that communicates fluid to a charge pump 34. The charge pump 34 communicates fluid through a valve 36 and into an inlet 38 of a tank 40. The valve 36 is open during filling of a batch tank 40 and is closed after the tank 40 is filled with feed fluid. The tank 40 may include an air vent 41 for releasing displaced air as the tank 40 is filled and drawing in air as the tank 40 is emptied. A drain valve 42 is coupled to a port 44 for draining the processed fluid into a brine tank 46 as will be described in more detail below.

[0007] An outlet port 50 communicates fluid from the tank 40 to a high pressure pump 52 through pipes 51 and 53. The high pressure pump 52 increases the pressure of the fluid from the tank 40 and communicates the fluid to the membrane housing 54 that has a membrane 56 therein. A permeate pipe 58 drains permeate that passes through the membrane 56. The permeate pipe 58 is in communication with a permeate tank 60 that collects the permeate that passes therethrough. A brine pipe 62 communicates brine concentrated fluid through a valve 64 to a port 66 in the tank 40.

[0008] A controller 70 coupled to a concentration sensor 72 monitors the process and the concentration of the fluid within the tank 40 to end the process when the fluid within the tank 40 reaches a predetermined concentration. The controller 70 may also be used to control the various valves including valve 36, the valve 64 and the pumps including the high pressure pump 52 and the charge pump 34. In the process, feed fluid is provided to the tank 40 through the charge pump 34 and open valve 36. When the tank 40 is filled, the charge pump 34 is powered off and the valve 36 is closed. As the tank 40 is filling, air is vented from the tank through the air vent 41. Drain valve 42 is also closed during the filling of the tank 40 through pipe 38. During batch processing, the high pressure pump 52 is controlled to provide pressure. The valve 64 is also opened during batch processing to circulate the concentrated brine back to the tank 40. During batch processing, fluid from the tank 40 leaves the port 50 and enters the pipe 51 whereby the high pressure pump 52 increases the pressure and provides the desired pressure to the membrane housing 54 through pipe 53. Permeate exits the membrane housing through the pipe 58. The control valve 64 is adjusted to achieve a desired flow rate and depressurized brine fluid returns to the tank 40 through port 66.

[0009] As the batch of fluid within the tank is processed, concentrated brine is recirculated back to the tank 40 which increases the concentration of the fluid within the tank 40. As the fluid becomes increasingly concentrated, the pressure output by the high pressure pump 52 is increased. The recirculation of the fluid from the tank 40 to the high pressure pump 52 through the membrane housing 54, brine pipe 62 and the valve 64 continues until the sensor 72 measures the ending concentration.

[0010] Once desired concentration has been achieved, the high pressure pump 52 is stopped and the concentrate within the tank 40 is drained through the drain valve 42 which is opened todrain the fluid into the brine tank 46. Thereafter, the drain valve 42 is closed and the charge pump 34 is activated and the valve 36 is open to provide a fresh batch of feed fluid to the tank 40.

[0011] Referring now to Figure 4, another prior reverse osmosis system 30’ is illustrated in further detail. The same components illustrated in Figure 3 are provided with the same reference numerals. In this example, an energy recovery device such as a turbocharger 74 having a turbine portion 74T and a pump portion 74P is used to recover at least a portion of the energy of the pressurized brine concentrate stream in the brine outlet pipe 62. That is, the brine from the membrane housing 54 is communicated to the turbine portion 74T of the turbocharger 74. The turbine 74T rotates the pump portion 74P to increase the pressure within the input line 78 to the membrane housing 54. The depressurized brine fluid returns to the tank 40 through the inlet port 66 and the valve 64. The high pressure pump 52 can operate at a lower pressure because of the boost provided by the turbocharger 74. By reducing the pump power, the added heat into the fluid is reduced. This also eliminates the cooling equipment to maintain the fluid temperature to a desired batch temperature.

[0012] Referring now to Figure 5, a similar example to that illustrated in Figure 3 is set forth. In this example, another high pressure pump 80 is coupled between the fill reservoir 32 and the input port 38 to the tank 40. This configuration may be referred to as a "semi-batch" reverse osmosis system 30". In this example, the charge pump 34 transfers feed fluid from the reservoir 32 to entirely fill the tank 40. The valve 36 is closed. The high pressure pump 80 is used to pump feed into the fluid tank 40 from the reservoir 32. The pump 52 is engaged so that as feed is injected into the tank 40 through the feed pipe 51 and the feed fluid input pipe 53, the pressure quickly rises due to the incompressibility of the fluid. The pressure reaches the point where the permeate exits the membrane housing 54 through the permeate outlet pipe 58 into the tank 60. The permeate flow equals the rate of flow from the high pressure pump 80. As permeate is extracted, the pressure in tank 40 increase to overcome the increasing osmotic pressure in order to maintain the permeate flow into the permeate tank 60. The pump 52 circulates fluid from the tank 40 through the membrane housing 54 and back to the tank 40. Concentration sensor 72 senses the concentration of the fluid within the tank 40 and when a concentration has reached a concentration limit, the high pressure pump 80 is shut down and valve 42 is opened to allow the fluid within the tank 40 to drain into the brine tank 46. The next batch begins by opening the valve 36 and increasingthe amount of fluid within the tank 40 until it is full wherein the valve 36 is closed and the high pressure pump 80 is activated to feed fluid into the tank 40 during the permeate production as described above.SUMMARY

[0013] The present disclosure provides a method and system for batch processing feed fluid in a system that can continuously operate in an efficient manner. In one aspect of the disclosure, a reverse osmosis system and method of operating the same includes a membrane housing comprising a reverse osmosis membrane therein. The membrane housing has a feed fluid input, a brine outlet and a permeate outlet; The system further includes a charge pump, a plurality of valves and a tank having a volume comprising a movable partition dividing the volume into a first volume and a second volume. The plurality of valves selectively couples the charge pump to the first volume or the second volume and the brine outlet to the second volume or the first volume respectively. In another aspect of the disclosure, a method includes filling a first volume and a second volume of a tank, having a movable partition separating the first volume at a first end of the tank and the second volume at a second end of the tank, producing permeate with fluid in the second volume at a membrane housing, recirculating brine to the second volume from the membrane housing, and filling the first volume with feed fluid in response to producing permeate to cause the partition to move toward the second end until a concentration of fluid in the second volume exceeds a threshold.

[0014] Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

[0016] Figure 1 is a cutaway view of a membrane and fluid flow therethrough according to the prior art.

[0017] Figure 2 is a chart of feed pressure, osmotic pressure, feed total dissolved solids (TDS), permeate rate and net driving pressure (NDP) according to the prior art.

[0018] Figure 3 is a schematic view of a reverse osmosis system according to the batch- operated reverse osmosis system according to the prior art.

[0019] Figure 4 is a second schematic view of a batch operated system according to the prior art.

[0020] Figure 5 is a schematic of a third batch-operated system according to the prior art.

[0021] Figure 6 I s a schematic of a batch-operated system according to the disclosure.

[0022] Figure 7 is a state chart for the operating states of the valves of Figure 6 during operation.

[0023] Figure 8A is an alternative valve configuration for a reverse osmosis system.

[0024] Figures 8B and 8C illustrate the different states of the spool valve of Figure 8A.

[0025] Figure 9 is a state table for the operating states of the reverse osmosis system using the spool valve of Figure 8A.

[0026] Figure 10 is an alternative example of a tank and movable partition.

[0027] Figure 11 is a side view of an alternative configuration for the movable partition ofFigure 10.

[0028] Figure 12 is a chart illustrating feed pressure, osmotic pressure, feed total dissolved solids, permeate rate and net driving pressure according to the operation of the present examples.

[0029] Figure 13 is a schematic view of another example of a reverse osmosis system of the disclosure.

[0030] Figure 14A is a partial schematic view of the reverse osmosis system of Figure 0. In a first state.

[0031] Figure 14B is a partial schematic view of the reverse osmosis system of Figure 13 in a second state.

[0032] Figure 15A is a partial schematic view of the reverse osmosis system having a common wall.

[0033] Figure 15B is a top view of the reverse osmosis tank of Figure I SA.

[0034] Figure 15C is an alternative example of a common wall tank.

[0035] Figure 16 is a side view of an in-water reverse osmosis tank system.

[0036] Figure 17 is a side view of an on-land reverse osmosis tank system.

[0037] Figure 18 is a side view of the invention.

[0038] Figure 19 is a side view of the system.

[0039] Figure 20 is a side view of the invention.

[0040] Figure 20 A, B, C and D are side diagrammatic views of the invention.

[0041] Figure 21 is a side view of another feature of the invention.

[0042] Figure 21A is a partial side view of a component of the invention.

[0043] Figure 22 is a side view of the invention.

[0044] Figure 23 is a side view of the system.

[0045] Figure 24 is a side view of a feature of the invention.

[0046] Figure 25 is a side view of a feature of the invention.

[0047] Figure 26 is a side view of a feature of the invention.

[0048] Figure 27 is a side view of a feature of the invention.

[0049] Figure 28 is a side view of a feature of the invention.

[0050] Figure 29 is a side view of a feature of the invention.

[0051] Figure 30 is a side view of a feature of the invention.

[0052] Figure 31 is a side view of a feature of the invention.

[0053] Figure 32 is a partial side view of a feature of the invention.DETAILED DESCRIPTION

[0054] The following description is merely exemplary m nature and is not intended to limit the present disclosure, application, or uses. For purposes of clarity, the same reference numbers will be used in the drawings to identify similar elements. As used herein, the phrase at least on of A, B, and C should be construed to mean a logical (A or B or C), using a non-exclusive logical or it should be understood that steps within a method may be executed in different order without altering the principles of the present disclosure.

[0055] In the following description, a method and system for managing the reverse osmosis system to minimize energy consumption of the high pressure pump is set forth. A process that achieves continuous operation by allowing recharge of fresh feed to occur while the batch process is processing permeate is set forth.

[0056] Referring now to Figure 6, the same elements are provided with the same reference numerals from those of Figures 1 through 5. In this example, the tank 40 includes a movable partition 6IO. The movable partition 6 I O divides the volume of the tank into a first volume 612 and a second volume 614. The movable partition 610 may separate the volumes 612 and 614 so that there is no mixing of fluid there between. That is, during the process, different salt concentrations may be with the first volume 612 and the second volume 614. The tank 40 has a first end 616 and a second end 618. The first end 616 helps define the first volume 612. The second end 618 helps define the second volume 614. A side wall 619, together with the first end 616 and the second end 618, define the entire volume within the tank 40. The tank 40 may also be various shapes. The movable partition 610 moves up and down during permeate production process. Details of this will be described below. A three-way valve 620 is used in place of the valve 36. The three-way valve communicates fluid from the feed source 32 received at port 620C and the charge pump 34 to either the first port 622 or the second port 624 of the tank 40 through valve port 620A or 620B, respectively. The valve port 620A is in communication with the port 622. The port 620B is in communication with the port 624 of the tank 40. Feed fluid is thus communicated into the first volume 612 through the port 622. Fluid is communicated into the second volume 614 through the port 624.

[0057] Another three-way valve 630 has a valve port 630A, a valve port 630B and a port 63OC. The port 630C is in communication with the high pressure pump 52 and a brine drain valve 632. The brine drain valve 632 is in communication with orifices 634 and the brinereservoir 638. A total dissolved solid sensor or concentration sensor 635 may monitor the concentration of the drain or brine fluid entering the brine reservoir 638.

[0058] Another three-way valve 640 has a port 640C in communication with the brine pipe 62, a port 640B that is in communication with the port 642 (that is in communication with the first volume 612 of the tank 40) and a port 640A in communication with the port 644 which is in communication with the second volume 614 of the tank 40.

[0059] Referring now to Figures 6 and 7, the operation of the reverse osmosis system 30" is set forth. The states of the valves 620, 630, 632 and 640 are set forth. The fluid in the three-way valves flows into or out of the port "C" and into or out of one of the port "A" or port "B" for each valve which are denoted in the chart below. Valve 632 is a two-way valve that is either opened ("O") or closed ("C"). In the first state, the RO system 30"makes permeate at the membrane housing 54 by way of the pipe 58. The valves 620, 630, 632 and 640 may be referred to as a plurality of valves. However, the various states of the valves may allow various conditions. In the first state, the plurality of valves are set to make permeate from the volume 614 while feed fluid enters the volume 612. That is, the valve 620 is set to communicate feed fluid from the port 620C to 620A and into the port 622. It is presumed in state 1 that the tank 40 is already filled with fluid. Fluid is provided from the port 644 to valve 630 and, in particular, to port 630B of the valve 630. Fluid is communicated through the valve and port 630C to the high pressure pump 52 and membrane housing 54 where permeate is produced through the pipe 58. Leftover brine fluid from the process in the membrane housing 54 returns to the tank though the pipe 62 and port 640C and port 640A of the three-way valve 640. Fluid leaves the port 640A of the valve and enters the port 644 in the second end 618 of the tank 40. During this process, the valve 632 is closed. As the process progresses, the movable partition 610 moves in a direction toward the second end 618 or, in this example, in a downward direction. When the concentration of the fluid in the volume 614 reaches a predetermined concentration as determined by the controller 70 using the concentration sensor 72A, the process stops processing permeate from the volume 614 and purges brine fluid from the volume 614.

[0060] When brine is being purged from the volume 614, the system enters state 2, the valve states of the valves 620, 630 and 640 in state 2 are identical to those of state 1 with the exception of valve 632 which changes from closed to open. When valve 632 opens, brine continues to be pumped through the pipe 51, the high pressure pump 52, pipe 53 andthe valve 632. Ultimately, the movable partition 610 moves in a downward direction at or near the second end 618.

[0061] In state 3 of Figure 7, the valve states of valve 620, 630 and 640 are reversed from that of state 1. That is, valve 620 now communicates fluid from the port 620C through the port 620B and into the port 624 of the tank 40. Valve 630 communicates fluid from the port 642 through the port 630A and 630C of the three-way valve 630 to the pipe 51. Valve 640 communicates brine from the port 640C through the port 640A. Valve 632 is in a closed state and thus all of the fluid passing through the valve 630 enters the high pressure pump 52 and the membrane housing 54.

[0062] In state 4, brine is purged from the first volume 612. In this situation, the plurality of valves 620, 630 and 640 are in the identical state as that of state 3 with the exception being valve 632 which is placed in an open state. In state 3, the movable partition 610 moves toward the first end 616 until the sensor 72B senses a predetermined concentration of the first volume by way of the controller 70. The controller 70 then changes the state of the various valves and may change the speed of the high pressure pump 52 and the pump 34.

[0063] A few notable features set forth in Figure 6 may be evident to those skilled in the art. Even though purging through the valve 632 takes place, when purging either the volume 612 or the volume 614, the membrane housing 54 continues to receive fluid through pipe 11, pump 52 and pipe 53 and generates permeate fluid through the permeate pipe 58.

[0064] During the process, the flow rate through the membrane housing 54 as controlled by the high pressure 52 is optimized to prevent fouling and maximize membrane efficiency. The pump 34 continues to replace the permeate within the appropriate volume of the tank 40.

[0065] The orifices 634 reduce the pressure drop across the valve to maximize the valve life and to allow the brine drain to drain until the partition has reached the bottom of the tank in state 1. The flow resistance through the valve 632 allows enough resistance so that some permeate production is performed. That is, not all of the circulated brine fluid leaves the system but rather a portion of the circulating brine fluid reaches the membrane housing 54 through the pump 52. After state 2 and prior to state 3, the pipes 51, 53 and 62 between the various components arepreferably kept to a small distance so the amount of dead volume of highly concentrated brine between the transition from states 1 and 2 to states 3 and 4 is reduced to a minimum.

[0066] Reducing the amount of brine in the dead volume of some configurations may also be important.

[0067] Referring now to Figure 8 A, a spool valve 810 is used to replace the valves 620, 630 and 640 illustrated above in Figure 6 in the reverse osmosis system 30iv. The spool valve 810 is in fluid communication with the charge pump 34, the brine pipe 62, the high pressure pump 52 and the drain valve 632.

[0068] The spool valve 810 has a linear actuator 812 that is used to move a rod 814 to align the spool disks 816, 818 and 820 to their desired position relative to the various ports 830-844 formed in the casing 850 of the spool valve 810.

[0069] It should be noted that the illustration set forth in Figure 8A do not include the controller 70 and the electrical couplings to the various pumps and to the sensors 72A, 72B and 635. However, the sensors may also be provided in Figure 8 in the same manner as Figure 6.

[0070] In this configuration, the linear actuator 812 is disposed in the leftmost or most outward position away from the actuator 812 position. It should also be noted that a seal 860 is disposed between the port 834 and the port 842. By providing the seal 860, the high pressure portion end or portion and the low pressure end or portion within the spool valve 810 are separated. By alignment of the disks 816, 818 and 820, different flow paths may be formed through the casing so that fluid may be provided to and from the various devices in a similar manner to that set forth in Figure 6. Figures 8B and 8C illustrate state A which also corresponds to Figure 8 A and state B which corresponds to the disks 816, 818 and 820 moved to the rightmost position or toward linear activity 812 with the rod 814.

[0071] Effectively, ports 830, 838 and 832 act in a fluidically similar manner to three-way valve 620. The ports 832, 838 and 840 act in a fluidically similar manner to valve 630 and ports 842, 844 and 836 act in a fluidically similar way to valve 640.

[0072] Referring now to Figures 8A-8C and Figure 9, the various states are set forth using the spool valve. In state A, permeate is made from the volume 614. Feed fluid enters volume 612. The movable partition 610 moves in a downward position during permeate production in state AValve 632 is closed in state 1. State A corresponds to the rod 814 being in the leftmost position. That is, state A corresponds to fluid being communicated between ports 838 and 832, between ports 840 and 834 and between ports 844 and 836. State 2 has the spool valve 810 also in state A. That is, brine is being purged from the volume 614 while feed fluid continues to reach the membrane housing 54. Pump 52 continues to operate. Valve 632 in state 2 is in an open position.

[0073] In state 3, permeate is being made from volume 612 and feed fluid is entering volume 614. In state B, fluid is being communicated between ports 830 and 838, between ports 832 and 840 and between ports 842 and 836. As noted above, during the process of permeate production, the pump 52 may be controlled to increase in speed and therefore provide higher pressure to the membrane housing 54.

[0074] Referring now to Figure 10, the movable partition 610 illustrated above may be a conformable movable partition 610' as illustrated in Figures 10 and 11. The movable partition 610' includes an upper surface 1010 and a lower surface 1012. The upper surface 1010 partially defines the first volume 612 of Figure 6. The lower surface 1012 partially defines the second volume 614. The upper surface 1010 conforms to the shape of the first end 616 of tank 40. The shape of the lower surface 1012 conforms to the shape of the second end 618 of tank 40. This allows a minimization (or near elimination) of the volume 612 or 614 near the end of the process. It should be noted that the pressure difference between the upper surface 1010 and the lower surface 1012 is very minimal and thus the cost of preventing leakage around the movable partition 610' is minimal. A seal 1020 may be disposed around the movable partition 610'. A plurality of different types and shapes and numbers of seals 1020 may be provided.

[0075] Referring specifically to Figure 11, the movable partition 610' may include a passage 1110 therethrough. The passage 1110 has a width 1112 that is wider than both of the difference between the ports 622 and 642 and ports 624 and 644. The width of the passage is defined at reference number 1112. A swinging plate 1120 may have a spring loaded pivot 1122 coupled thereto. The spring force allows the swinging plate 1120 to open only under high pressures experienced at the end of each permeate production cycle. The open position of the swinging plate 1120 is maintained until feed fluid is pumped into the tank volume and the direction of flow through the swinging plate 1120 is reversed (or the drain valve is closed). In both instance, the pressure is relieved. After relieving the pressure and the permeate production begins with thevolume on the opposite side of the opening of the swinging plate 1120. The plate 1120, because it is in axial alignment with the port 622, 642, 624 and 644, allows the plate 1120 the move in the direction indicated by the arrows under high pressure. When the partition 610 moves up or down within the tank 40, the plate 1120 will remain in a closed position to prevent mixing of the volumes 612 and 614. Because there is still a "dead" volume within the pipes attached to the membrane and various pumps, feed flow continues to enter the tank and causes the partition to open under the force of the feed flow. By allowing the plate 1120 to open, some of the feed flow is able to enter the piping to flush the pipes. Thus, the highly concentrated brine is removed from the pipes and the dead volume within the pipes is eliminated. A total dissolved solid sensor 635 illustrated in Figure 6 may be used to end the fluid flow through the plate 1120 and thus the permeate production can be resumed as the partition moves in the opposition direction. Thus, the plate 1120 will open at the bottom of the tank 40 until the TDS sensor 635 reads that a drain fluid concentration is below a drain concentration threshold which corresponds to a low amount of total dissolved solids present in feed fluid in contrast to high TDS fluid present at the end of permeate production. The sensor 635 senses the transition between the TDS amounts. Then, the plurality of valves may be changed so that feed fluid enters the bottom of the tank and permeate production is from volume 612. Likewise, when the movable partition 610' reaches the top limit of travel, the swinging plate 1120 may open and flush the piping until the TDS sensor 635 reads below a drain fluid concentration threshold. Thereafter, the plurality of the valves may change state and feed fluid provided into the volume 612 so that permeate is produced using the volume 614.

[0076] Referring now to Figure 12, the conditions during a batch operated run using the partition 610' illustrated above is set forth. As can be seen, compared to that of Figure 2, the net driving pressure and permeate rate are relatively constant until the time between the finish and the purge. This time is relatively small and thereafter the cycle starts in the reverse direction.

[0077] By providing the partitions 610 or 610', the incoming feed fluid does not mix with the brine. This is different than the known semi-batch system described above in Figures 1-5. The elimination of the feed fluid and the brine mixing increases the efficiency of the overall system by preventing irreversible losses with different levels of total dissolved solids. Further, there is no disruption to the membrane production to recharge the tank after the brine has been fully processed because the tank is already charged with fresh feed on the other side of the movablepartition 610 or 610' with purging of the dead volume not interrupting permeate production. The permeate production at a constant rate continues until the purge process is complete even though the process is at a slightly lower efficiency. The process only takes a short amount of time and full permeate production is then continued. Although the system undergoes a range of pressures in response to the degree of brine concentration, full depressurization is never performed. This reduces the cyclical stresses on the tank, piping and the membrane.

[0078] Referring now to Figure 13, a reverse osmosis system 30v in this example, two tanks 40 A and 40B are used to house the first volume 612 and a second volume 614 rather than having the volumes divided by the movable partition 610 as illustrated above. By providing two different volumes, relatively low cost equipment and high maximum energy efficiency may be achieved. When using the movable partition or two separate tanks, the fluid being processed is not allowed to mix with the previously processed brine and therefore the total dissolved solids in the feed are minimized. The same reference numerals for each of the components set forth previously are used in Figures 13, 14A and 14B. In addition to two separate volumes and two tank 40A, 40B, two separate concentration sensors 1330 and 1332 are used in a similar manner to that used above with respect to Figure 6. The sensors 1330, 1332 may act to detect the tank being drained as well. This may be accomplished in one sensor or two sensors at locations 1330, 1332. Further, two different drain ports 44A, 44B are in fluid communication with the drain valves 42A, 42B and the respective drain reservoirs 46A, 46B to form drain lines.

[0079] In this example, two three-way valves 1310 and 1312 are provided. In a sense, the operation of the system is nearly the same as that set forth in Figure 6. That is, the low pressure pump 34 fills the tank 40A with an initial fill of feed water. In state A, the three- way valve 1312 couples the port 1314 through valve ports 1312B and 1312C to the high pressure pump 52. The brine outlet pipe 62 is in communication with the port 1318 of the tank 40B through valve ports 1310C and 1310A of the valve 1310. The high pressure fluid flow passes through the turbine 74T of the turbocharger 74 to provide boost as described above in Figure 4. The permeate exits the membrane housing 54 through the permeate pipe 58. The low pressure brine enters the tank 40B through the port 1318. Over time, the fluid level of the brine in the tank 40B increases while the fluid level of the fluid in the tank 40A decreases. To reduce the amount of time of starting the process, once enough fill fluid has entered the tank 40A, the process may start as long as the filling process is faster than the permeate production process. In the same manner described, theconcentrate of the first volume 612 and the second volume 614 are monitored. Further, the drain valves 42A, 42B act in a similar manner.

[0080] Referring now to Figures 14A and 14B, once the liquid level of the volume 612 in tank 40A is reduced to a substantial amount such as at the bottom of the tank in Figure 13, the states of the valves 1310 and 1312 switch to a second state in Figure 14A. That is, valve 1312 communicates fluid from the tank 40B through port 1320 to the high pressure pump 52 through valve ports 1312A and 1312C. Port 1316 and tank 40A receive fluid from the brine pipe 62 through the turbine 74T through valve ports 1310B and 1310C. In Figure 14A, tank 40B is reducing in level while tank 40A is filling. The high pressure pump 52 will increase the pressure in the fluid to a higher pressure due to the higher total dissolved solids. Once the level of the tank 40B reaches the bottom as indicated by sensor 1332, the valves 1310 and 1312 are switched.

[0081] Referring now to Figure 14B, valves 1310 and 1312 are switched to operate in the manner illustrated above with respect to Figure 13. As can be observed, the fluid level in tank 40A is reduced from the start of the process in Figure 13. That is, each cycle produces permeate that is removed from the volume of the tanks. Once the concentration of the remaining brine or the desired amount of permeate has been reduced, drain valves 42A and 42B are open to drain the tanks 40A, 40B. It should be noted that the sensors 1330 and 1332 may act as concentration sensors or level sensors.

[0082] Referring now to Figures 15A and 15B, an alternative tank 1510 is illustrated having a common bulkhead 1512. The common bulkhead divides the tank 1510 into the first volume 612 and the second volume 614. A common outer wall 1514 may surround the entire tank.

[0083] Referring now to Figure 15C, another design for a tank 1550 is set forth. In this example, a first tank 1552 is cylindrical in shape, has volume 612 therein and has a longitudinal axis 1554. An outer coaxial tank 1556 has volume 614 therein and is disposed around the tank 1552. Of course, other types of designs may be provided. The advantage of providing nested or directly adjacent tanks such as that illustrated in Figures 15A-15C are the reduced amount of land area required to place the tanks.

[0084] Referring now to Figure 16, the tanks 40A and 40B may be replaced with fabric bags 1610A and 1610B. The fabric bags 1610A, 1610B have ports 1612, 1614, 1616 and 1618 that correspond to the ports 1314, 1316, 1318 and 1320, respectively, as set forth in Figure 13. In thisexample, the ports 1612-1616 may be formed of flexible hoses. The bags 1610A and 1610B may be floating in water as illustrated by the water line 1620. The fabric bags 1610A, 1610B may be allowed to float in the body of water as indicated by the water level 1620 and may be located close to a reverse osmosis system in a sheltered bay directly adjacent to the reverse osmosis facility. The bags 1610A, 161 OB serve the same function and hold a first volume 612 and second volume 614, respectively. As the batch is processed and the brine concentration in the bags increases, negative buoyancy results and thus, subsurface support structures 1630 and 1632 may be used to support the fabric bags 1610A and 1610B as the brine increases.

[0085] Referring now to Figure 17, fabric bags 1610A and 1610B may be used on the land 1650. A sculpted surface 1652 and 1654 may receive bags 1610A and 1610B, respectively.

[0086] The invention may be described as a true batch reverse osmosis (RO) system with continuous operation using a single batch tank. True batch is a batch RO system in which the initial charge of feed water (or other solutions) undergoes a continuous extraction of permeate resulting in a decreasing volume of feed with increasing salinity in the batch tank and associated piping. The extraction process (i.e., permeation of the feed through an RO membrane) continues until the concentration in the fluid in the batch tank (called brine) reaches a process limit such as a desired concentration of total dissolved solids (TDS) or osmotic pressure. Note that the permeate or brine or both may be the beneficial product(s).

[0087] A major objective of the invention is to purge the concentrated brine while recharging with new feed without interrupting permeate production. As such, the system remains pressurized during operation with a relatively low range of pressure. This results in reduced range of cyclical loads on the batch tank, piping and instrumentation resulting in less fatigue stress hence longer life. In particular, large cyclical changes in pressure adversely affects RO membrane life due to relative motion between the membrane surfaces and the spacers that keep the membrane surfaces apart to form flow channels. This relative motion abrades the membrane surface resulting in damage that reduces membrane performance and usable life.

[0088] Figure 18 shows system 1000 with the basic features of the invention.

[0089] Batch tank 43 contains partition 45 that defines two volumes, volume A between partition 45 and tank end 42A and volume B between partion45 and tank end 42B.

[0090] Feed from reservoir 1 is drawn though pipe 3 through salinity meter 5 and flow meter 7 by high pressure (HP) pump 9 driven by motor 11. During batch operation (i.e. non-purging), feed passes through pipe 13 and pipe 15 through check valve 17 into pipe 25. Feed passes from pipe 25 to 3-way valve 37. Valve 37 directs flow through pipe 39 through valve port 37A to port 57A on tank 43 which connects to volume A or through valve port 37C through pipe 117 to port 57B on tank 43 that connects to volume B.

[0091] Partition 45 has a close clearance with tank 43 with peripheral seal 47 to prevent leakage. Corners 55 fit closely with corners 53 of tank 43. Sensors 41A and 41B detect the approach of partition to then tank ends 41 A and 4 IB respectively.

[0092] Batch tank port 123 A and pipe 71 and tank port 123B and Pipe 69 connect volumes A and B respectively with 3-way valve 65 through valve ports 65A and 65C respectively. Brine tank 61 is connected to valve port 65B by pipe 67. Brine from volume A and B is connected to the brine tank by pipes 69 and 71. Brine tank 61 is connected to turbine section 85 of turbocharger 83 by pipe 81. Brine purge valve 79 regulates flow of brine through pipe 81. The brine flow exits turbine section 85 and passes through flow meter 91 and salinity meter 93 through pipe 95 to brine collection tank 97.

[0093] Brine tank 61 may be packed with an array of small tubes 63 oriented in the direction of flow. The tubes minimize turbulence and helps provide laminar flow during the purge in which feed from volume A or B enters through pipe 121 and drives brine out through pipe 81 with minimal mixing between the feed and brine.

[0094] Pipes 40 and 115 connect valve ports 59 A and 59C respectively of valve 59 through valve port 59B to membrane 101 through pipe 99. Permeate exits membrane 101 through pipe 103 through flow meter 105 to permeate collection tank 107. Brine exits membrane 101 through pipe 109 and receives a pressure boost from circulation pump CP 111 driven by motor 113. A 3- way valve 73 receives flow from pump 111 and directs flow to either end of brine tank 61 through valve ports 73A and 73B of valve 73, and pipes 75 and 77 respectively.

[0095] The invention uses a single batch tank 43 and brine tank 61 to achieve continuous batch operation. Figure 2 illustrates the system with volume B undergoing batch operation with volume A is charging with fresh feed.

[0096] Note that system 1000 is closed with the only fluid exit through membrane 101 to permeate exit 103 during non-brine purging operation (i.e. valve 79 closed). System pressure is entirely controlled by the pressure necessary to establish a permeate flow through membrane 101 that equals HP pump flow. The required pressure increases as the batch process continues due to increasing TDS of the recirculating brine, hence increasing osmotic pressure.

[0097] A critical process parameter is the amount of permeate to be recovered from the feed. The ratio of permeate recovered to the starting amount of feed is called the recovery ratio. Recovery ratios range from 50% to 90+%. For example, a system that starts a batch run with 1,000 liters of feed designed for 70% recovery will end with 300 liters of brine remaining within in the system that needs to be purged.

[0098] The operating parameters for the system shown in figure 19 are described in the following table 1 and table 2. The details of the operation of the system have been generally described previously and only new features will be described in detail.

[0099] Referring to Figure 19, the system is assumed to be fully charged with feed in volume B with partition 45 at position Pl at tank end 42A. HP pump 9 and pump CP 111 are operating. HP pump 9 is controlled such that it delivers a desired permeation flow rate, usually a constant value but can be varied to achieve process objectives such as to reduce permeate flux rates in membrane 101 when the potential for fouling is high. As the batch process continues, volume A increases as feed enters and volume B decreases as permeate exits the system through membrane 101 and permeate pipe 103. Valve states are indicated in Table 1.

[0100] When partition 45 reaches tank end 42B indicated by position P2, volume B has essentially zero volume and the batch cycle is complete. Brine to be purged is in piping, membrane 101 with the bulk in brine tank 61. HP pump 9 increases in speed to increase feed flow; ideally about twice its normal flow rate during batch processing. Table 2 indicates the valve states during the purge cycle. Valves 37, 73, 65 and 59 switch stages to direct flow to the other valve ports. This results in the fluid in volume A undergoing permeation while volume B is being charged with feed. During the purge process, valve 79 is partially opened to pass flow from batch tank that equals HP pump flow in excess of permeate flow through membrane 101. The flow of brine from brine tank 61 through valve 79 passes through turbine section 85 of turbocharger 83. Turbocharger 83 produces a pressure boost from pump section 87. The added boost reduces the differential pressure across pump 9 hence reducing energy consumption. The pressure boost causes check valve 17 to close thus preventing backflow into pipe 13.

[0101] When purging of brine tank 61 is completed as indicated by the salinity of purge flow that is close to feed salinity as measured by salinity meter 93, valve 79 is closed and HP pump flow is reduced accordingly. The duration of the batch purge process is typically a small fraction of the batch cycle time. Please refer to Table 3 for the operational details of the system at the end of the purge cycle.

[0102] Note that when brine tank 61 has been fully purged of brine with feed, it is placed back in circulation by opening valve 73 switching ports from 73A to 73C thereby introducing feed into the ongoing batch process.

[0103] The batch process has completed one complete cycle with the partition returning to its starting position adjacent end 42 A of tank 43 with Volume B, all piping, membrane 101 and brine tank 61 filled with feed. Note that permeation was continuous and membrane pressure never dropped below a value that would reduce or stop permeation.

[0104] Figure 20 shows system 1010 with another embodiment of the invention in which purging of the brine tank occurs at low pressure thus eliminating the need of an ERD during the purge process. The system is similar to what has been already described and only new features will be described in detail. Low pressure booster pump 8 and motor 10 provides a pressure boost of 2 to 3 bar to HP pump 9. During the purge process, brine tank 61 is isolated from the batch process by valve 78 and port 73C on 3-way valve 73. Valve 79 opens allowing low pressure feed to purge brine tank 61 with feed provided by LP pump 8. LP pump 8 increases its flow rate sufficiently to continue to provide feed to HP pump 9 with the balance directed to brine tank 61 which discharges brine at a low pressure thus minimizing energy losses and eliminating the need for an ERD.

[0105] Although brine tank 61 should provide the bulk of brine storage at the end of the batch cycle, piping and the membrane housing also needs to be purged with feed water. This is best accomplished by adding pipe 133 and valve 131 that allows feed flow from pump 9 to passto the circulation loop defined by membrane 101 and either volumes A or B during the purge process. During the purge process, HP pump 9 increases in speed to increase feed flow; ideally about twice its normal flow rate during batch processing. Simultaneously, valve 131 in pipe 133 opens to allow feed to pass directly into the circulation loop and valve 125 on pipe 135 opens sufficiently to drain a flow equal to the increase in flow from HP pump 9. Note that the rate of permeation from membrane 101 remains constant. Pipe 133 should be located immediately downstream of pipe 135 to ensure all piping in the circulation loop is flushed. Note that the minimum TDS of the circulation loop achievable by the purge process is approximately equal to Qin (flow in pipe 133) divided by Qout (flow in pipe 135) with Qin - Qout = Qpermeate. Practice suggest that an Qin that is twice Qout provides sufficiently flow to purge TDS. After brine tank 61 has completed its purge process and is brought into the circulation loop, the TDS will drop to a value very close to the feed TDS. This combination of brine tank purging and pipe / membrane purging can be timed that both are completed at approximately the same time.

[0106] To help explain the system shown in figure 20, the following flow diagrams have been provided. Figures 20-A and 20-B shows flows (indicated by heavy lines) and valve states for batch processing in volumes A and B respectively. Figures 20-C and 20-D shows flows (indicated by heavy lines) and valve states for purging of volumes A and B respectively. Please refer to Table 4 for additional clarification of the operational parameters.

[0107] Booster pump 8 would ideally be a centrifugal type able to accommodate variable flow rate without a speed adjustment with HP pump being a positive displacement type that maintains a constant flow rate at a given rotation rate with discharge pressure established by system resistance with increased flow required during the pipe / membrane purge process achieved by an increase in the speed of rotation of pump 9.

[0108] A control objective is to maintain a constant permeate production including the purge process. The control logic uses permeate flow data from flow meter 105. If permeate flow is too low, HP pump 9 speed is increased resulting in a membrane pressure increase. Conversely if permeate flow is too high, HP pump 9 speed decreases to reduce membrane pressure hence permeate flow.

[0109] The brine tank confers several other advantages. During the start of the batch process, the brine tank is filled with feed thus the membrane will initially process low TDS feed and thus have minimum pressure requirements and relatively low energy consumption by HP pump 34. Near the end of the batch cycle, the highest TDS brine is in the brine tank and does not pass through the membrane thus further reducing the energy consumption of HP pump 34 at the final stage of the batch process.

[0110] Figure 21 shows system 1020 with an improved method for continuous batch systems without a brine tank. Partition 45 has peripheral seal 43 to limit leakage relative to batch tank. Mounted on each side of partition 45 is flow distribution plate 46. The inboard face is a solid surface with a central hole 47 that opens into a series of radial channels 51 with flow channels 55 to form a flow distribution array as shown in Figure 4A. During operation central channel 51 A and 51B fits into opening 47 to establish a flow path from pipes 57A and 57B. Similar flow distribution plates 56A and 56B are fixed to tank ends 42A and 42B respectively and connect with pipes 40 and 115 respectively.

[0111] Batch functionality is identical to previous described embodiments. The difference is that central pipes 51 A and 5 IB limit partition movement to form brine volumes as needed based on the desired recovery.

[0112] The flow distributors minimize turbulence and mixing during the purge process within tank 43.

[0113] To illustrate the purge cycle, Figure 21 shows partition 45 and position P2 as established by the length of central pipe 5 IB. Sensor 41 B detects partition 45 and issues a signal to change valve 37 from port 37A to port 37C thus directing HP pump flow to pipe 117. This flow merges with flow exiting volume B and passes through pipe 115 to valve 59 through port 59B to enter membrane 101. Note that feed mixes with the lowest TDS portion of the brinevolume resulting in minimized irreversible losses from salinity mixing. Partition 45 is unable to move as it is hydraulically locked by closed valve ports 37 A, 65A and 59A.

[0114] The purge cycle is completed when salinity meter 93 measures a TDS value close to the feed salinity. At that point, valve 78 is closed and ports 65A and 59A open with port 37C remaining open to direct feed flow to volume B to begin the feed recharging process. Volume A undergoes batch processing.

[0115] Figure 22 shows system 1030 for a front-end RO system that provides brine to batch system 1010. Feed from tank 1 passes to LP pump 165 driven by motor 167. Pipe 14 leads to system 1010 to provide brine flushing as described in other embodiments. Pipe 14 also supplies HP pump 151 to pressurize feed for membrane array 155. Permeate exits membrane 155 and is collected in tank 161.

[0116] Brine exits membrane 155 through pipe 157 and passes to system 1010 to HP pump 9 driven by motor 11. Pump 9 needs to be rated for a high inlet pressure. Note that brine is not depressurized before entering as feed to system 1010 thus eliminating pressure losses between the systems.

[0117] The need for the front-end RO include:• The batch process is optimized for a specific recovery however feed conditions can vary. The front-end has variable recovery which is adjusted to provide a brine flow to the batch system that accommodates the batch system pre-set recovery.• The HP pump in system 11 would ideally be a positive displacement type that provides a fixed flow rate regardless of inlet pressure however a centrifugal pump is suitable with variable speed operation.• LP pump 165 provides sufficient pressure to HP pump 115 and flushing flow for batch system 11.

[0118] The previously described embodiment achieve optimal functionality however it involves significant high-pressure piping and fittings. This contributes to higher capital costs and creates a relatively large brine volume that limits the highest possible recovery.

[0119] Figure 23 shows system 1010 with the same components and functionality as system 1010 shown in Figure 3. Labeling of several ports of the 3-way valves have been changed to better match pipe labeling. The components have been rearranged to illustrate the more compact equipment arrangement with much reduced pipe lengths and reduced number of pipe fittings resulting in reduced capital costs and reduced fluid volume.

[0120] Pipes 141 and 143 run from end walls 42 A to 42B within tank 43 and are extensions of pipes 57A and 71 that are also shown in Figure 20 in a different arrangement. Pipes 141 and 143 allow feed into and out of tank 43 respectively. These two pipes pass through partition 45 and are sealed with O-rings 149 and 151. Pipes 141 and 143 include opening 145 and 147 adjacent to end wall 42 A to accommodate fluid passage. Recesses 153 and 155 in partition 45 keep the passages clear when partition 45 has reached end wall 42A.

[0121] Pipes 141 and 143 may be light weight and use low-cost plastic as there is essentially little pressure differential along the length of the pipes.

[0122] The invention may be described as a true batch reverse osmosis (RO) system with continuous operation using a single batch tank. True batch is a batch RO system in which the initial charge of feed water (or other solutions) undergoes a continuous extraction of permeate resulting in a decreasing volume of feed with increasing salinity in the batch tank and associated piping. The extraction process (i.e., permeation of the feed through an RO membrane) continues until the concentration in the fluid in the batch tank (called brine) reaches a process limit such as a desired concentration of total dissolved solids (TDS) or osmotic pressure. Note that the permeate or brine or both may be the beneficial product(s).

[0123] A major objective of the invention is to purge the concentrated brine while recharging with new feed without interrupting permeate production. As such, the system remains pressurized during operation with a relatively low range of pressure. This results in reduced range of cyclical loads on the batch tank, piping and instrumentation resulting in less fatigue stress hence longer life. In particular, large cyclical changes in pressure adversely affects RO membrane life due to relative motion between the membrane surfaces and the spacers that keep the membrane surfaces apart to form flow channels. This relative motion abrades the membrane surface resulting in damage that reduces membrane performance and usable life.

[0124] Figure 24 shows system 1040 with the basic features of the invention.

[0125] Batch tank 43 contains partition 45 that defines two volumes, volume A between partition 45 and tank end 42 A and volume B between partion45 and tank 42B.

[0126] Feed from reservoir 1 is drawn though pipe 3 through salinity meter 5 and flow meter 7 by high pressure (HP) pump 9 driven by motor 11. During batch operation (i.e. non-purging), feed passes through pipe 13 and pipe 15 through check valve 17 into pipe 25. Feed passes from pipe 25 to 3-way valve 37. Valve 37 directs flow through either pipe 39 through valve port 37A to tank 43 to port 57A to volume A or through valve port 37C through pipe 117 to port 57B to volume B.

[0127] Partition 45 has a close clearance with tank 43 with peripheral seal 47 to prevent leakage. Corners 55 fit closely with corners 53 of tank 43. Sensors 41A and 41B detect the approach of partition to then tank ends 41 A and 41B respectively. Pipes 71 and 69 connect volumes A and B respectively with 3-way valve 65 through valve ports 65A and 65C respectively.

[0128] Pipes 40 and 115 connect valve ports 59 A and 59C respectively of valve 59 through valve port 59B to membrane 101 through pipe 99. Permeate exits membrane 101 through pipe 103 through flow meter 105 to permeate collection tank 107. Brine exits membrane 101 through pipe 109, through valve 160 entering port 160A and exiting 160B, and receives a pressure boost from circulation pump CP 111 driven by motor 113. 3-way valve 73 receives flow from pump 111 and directs flow to either end of brine tank 61 through valve ports 73 A and 73B of valve 73.

[0129] The invention uses a single batch tank 43 to achieve continuous batch operation. Figure 25 illustrates the system with volume B undergoing batch operation with volume A charging with fresh feed.

[0130] Note that system 1040 is closed with the only fluid exit through membrane 101 to permeate exit 103 during non-brine purging operation (i.e. valve 125 closed). System pressure is entirely controlled by the pressure necessary to establish a permeate flow through membrane 101 that equals HP pump flow. The required pressure increases as the batch process continues due to increasing TDS of the recirculating brine, hence increasing osmotic pressure.

[0131] A critical process parameter is the amount of permeate to be recovered from the feed.The ratio of permeate recovered to the starting amount of feed is called the recovery ratio.Recovery ratios range from 50% to 90+%. For example, a system that starts a batch run with 1,000 liters of feed designed for 70% recovery will end with 300 liters of brine remaining within in the system that needs to be purged.

[0132] Referring to Figure 26, the system is assumed to be fully charged with feed in volume B with partition 45 at position Pl at tank end 42A. HP pump 9 and pump CP 111 are operating. HP pump 9 is controlled such that it delivers a desired permeation flow rate, usually a constant value but can be varied to achieve process objectives such as to reduce permeate flux rates in membrane 101 when the potential for fouling is high. As the batch process continues, volume A increases as feed enters and volume B decreases as permeate exits the system through membrane 101 and permeate pipe 103. Valve states are indicated in Table 5.

[0133] When partition 45 reaches tank end 42B indicated by position P2, volume B is full of brine volume and the batch cycle is complete. The brine to be purged is in the batch tank, piping, and membrane 101. HP pump 9 shuts down, and pump 156 is turned on. At the same time valve 160 is switched so that ports 160C-160B are now open, and brine control valve 125 is opened.

[0134] Table 6 indicates the valve states during the purge cycle and is illustrated in figure 26. Valves 37, 125, and 160 switch stages to direct low salinity feed flow through the batch piping, batch tank and membrane flushing all high salinity from the system and out to drain through valve 125. During the purge HPP 9 continues to run pushing additional feed water into the flush loop through valve 37, and HPP 156 would be turned on to drive high flow feed water through valve 160 and into the recirculation pump 111. This system layout ensures that all the system brine water will be removed between batch cycles. During a purge cycle partition 45 remains in afixed position locked hydraulic ly by valve 37, 65 and 59. The combination of HPP 9, 111, and 156 are sized so they will create enough pressure to create constant permeate production during the purge cycle, valve 125 will be a high-pressure valve that will regulate brine flow and pressure out of the system.

[0135] The purge flow should be equal or close to the flow of the system recirculation pump, this allows the flush to happen at a very fast rate which will help maintain the health of the membranes in the system. Flushing at a faster rate will minimize the time between batch cycles, while improving purge efficiency due to less feed brine mixing.

[0136] At this point one full batch and purge cycle have been completed, and the system will change directions to perform a batch process with volume A as illustrated in figure 27. Note that permeation was continuous and membrane pressure never dropped below a value that would reduce or stop permeation. Purge on volume A is illustrated in figure 28.

[0137] Figure 29 shows system 1050 with an alternate method for continuous batch systems with brine tank. Partition 45 has peripheral seal 43 to limit leakage relative to batch tank. Batchfunctionality is identical to the previously described embodiments. The main difference is the addition of a brine tank, valve 78, 79 and 3-way valve 161. An optional ERD in the form of a turbocharger indicated by 83 could be incorporated in either the previous embodiment or the brine tank embodiment.

[0138] Figures 30 and 31 outlines the operation of the batch cycle with the partition moving from A to B. Valve 161 is open to 161A, valve 73 is open to 73C, valve 78 is open, and valve 79 is closed. In this configuration the recirculation loop runs through brine tank 61, and batch tank 43 would be sized so that the partition 45 would be allowed to travel across the entire tank length. The brine tank 61 now establishes the recovery of the system.

[0139] Once the partition 45 has reached the end of the batch tank 43, the purge cycle would begin. The purge cycle would be split into two paths, a low-pressure flush that removes brine from the brine tank 61, and a high pressure flush that would remove brine from the piping and membrane 101. The low-pressure flush would be achieved by opening valve 161C, closing valve 78 and opening valve 79. This would allow the brine tank to be flushed using pump 9 at low pressure reducing energy consumption required to purge all the brine volume from the system. The brine contained in the piping and in the membrane would be purged using pump 156 in a similar manner to the previous embodiment, the only difference being valve 73 which would have to be opened to 73 A bypassing flow around the brine tank during the high-pressure flush.

[0140] An optional ERD 83 could be installed on the brine line of the membrane 101. This would allow for brine control valve 125 to be fully open, and create a pressure drop across the ERD 83. This ERD 83 would then be tied to the high-pressure purge line 159 and result in a smaller pump 156 requirement and lower energy consumption during the purge cycle. The low- pressure flush and high-pressure flush would happen simultaneously, and the high-pressure flush would ensure permeate production continues throughout the entire purge cycle.

[0141] The partition 45 could be designed such that it helps direct flow within the batch tank 43 ensuring even mixing in the batch tank during the batch process and purge process. Figure 32 illustrates some of the ways even mixing could be accomplished. Either or both brine line 69 and 71 could be angled to create a spiral or vortex flow within the batch tank 43. Another option would be to create a flow director 163 attached to the partition 45 that would direct flow within the batch tank and help ensure even mixing throughout the system.

[0142] Those skilled in the art can now appreciate from the foregoing description that the broad teachings of the disclosure can be implemented in a variety of forms. Therefore, while this disclosure includes particular examples, the true scope of the disclosure should not be so limited since other modifications will become apparent to the skilled practitioner upon a study of the drawings, the specification and the following claims.

Claims

CLAIMSWhat is claimed is:

1. A reverse osmosis system comprising: a membrane housing comprising a reverse osmosis membrane therein, said membrane housing comprising a feed fluid input, a brine outlet and a permeate outlet; a charge pump; a tank having a first volume separated from a second volume by a movable partition; a plurality of valves, wherein said plurality of valves are configured, in a first mode, to selectively couple the charge pump to the first volume while the brine outlet in the feed input are connected to the second volume, and in a second mode to selectively couple the charge pump to the second volume while the brine outlet in the feed input are connected to the first volume, wherein the first mode and the second mode are configured for alternating operation; a brine drain valve having a brine inlet and a brine outlet, the brine inlet operatively connected to the feed fluid input; an energy recovery turbocharger having a turbine side with a turbine inlet and a turbine outlet and a pump side with a pump inlet and a pump outlet, the pump inlet being connected to the charge pump, the turbine side inlet being connected to the brine drain valve brine outlet, the pump outlet being operatively connected to the tank.

2. The system of claim 1 wherein a conduit having a first end positioned between the feed pump and the pump side inlet and a second end positioned between the pump side outlet and the tank.

3. The system of claim 2 wherein a check valve is positioned in the conduit to allow fluid to flow in a direction from the first end to the second end but present the flow of fluid in a direction from the second end to the first end.

4. The system of claim 3 wherein a flow valve is positioned between the tank and the fluid feed input on the membrane housing.

5. The system of claim 4 wherein a brine tank having a first port and a second port, the tank is disposed with the first port operatively connected to a pipe that extends from the tank to the flow valve, the second port being connected to a pipe that connects with the brine drain valve and the flow valve.

6. The system of claim 5 wherein the movable partition has a first surface that faces the first volume of the tank and a second surface that faces the second volume of the tank, a recess being formed on the first and second surfaces of the movable partition.

7. The system of claim 6 wherein the recess on the first and second surfaces of the movable partition are in alignment with the ports that supply fluid and remove fluid from the first and second volumes of the tank.

8. The system of claim 7 wherein the recess on the first and second surfaces have a depth that is sufficient to allow the flow of fluid from the inlet ports to the outlet ports with minimal pressure loss when the partition is adjacent the first or second end of the tank.

9. The system of claim 8 wherein an input valve is positioned between the charge pump and a feed fluid input located on the tank on each side of the movable partition.

10. The system of claim 9 wherein the brine tank has internal flow channels that reduce turbulence and mixing of the feed fluid and the brine.

11. The system of claim 10 wherein a purge valve is operatively connected to the brine tank12. The system of claim 11 wherein the brine tank has a capacity to accommodate the brine produced in one cycle of the system.

13. A reverse osmosis system comprising: a membrane housing comprising a reverse osmosis membrane therein, said membrane housing comprising a feed fluid input, a brine outlet and a permeate outlet; a charge pump; a tank having a first volume separated from a second volume by a movable partition; a plurality of valves, wherein said plurality of valves are configured, in a first mode, to selectively couple the charge pump to the first volume while the brine outlet in the feed input are connected to the second volume, and in a second mode to selectively couple the charge pump to the second volume while the brine outlet in the feed input are connected to the first volume, wherein the first mode and the second mode are configured for alternating operation; a brine drain valve having a brine inlet and a brine outlet, the brine inlet operatively connected to the feed fluid input;a moveable partition positioned in the tank, the partition having a flow distribution plate with a series of radial channels that form a volume for the brine.

14. A reverse osmosis system comprising: a membrane housing comprising a reverse osmosis membrane therein, said membrane housing comprising a feed fluid input, a brine outlet and a permeate outlet; a charge pump; a tank having a first volume separated from a second volume by a movable partition; a plurality of valves, wherein said plurality of valves are configured, in a first mode, to selectively couple the charge pump to the first volume while the brine outlet in the feed input are connected to the second volume, and in a second mode to selectively couple the charge pump to the second volume while the brine outlet in the feed input are connected to the first volume, wherein the first mode and the second mode are configured for alternating operation; a brine drain valve having a brine inlet and a brine outlet, the brine inlet operatively connected to the feed fluid input; a first pipe and a second pipe disposed in the tank, the first and second pipes extend from a feed inlet to a feed outlet on opposite ends of the tank.

15. The system of claim 14 where in a moveable partition is positioned in the tank, the moveable partition having openings for the first and second pipes.

16. The system of claim 15 wherein the moveable partition has recesses that are in alignment with the first and second pipes.

17. The reverse osmosis system of claim 5 wherein a discharge valve is operatively connected to the brine outlet of the membrane, to a circulation ump and to a supply pump.

18. The reverse osmosis system of claim 17 wherein the supply pump is operatively connected to a fluid supply and the charge pump.

19. The reverse osmosis system of claim 18 wherein the circulation pump is operatively connected to the first volume and the second volume of the tank.

20. The reverse osmosis system of claim 19 wherein a brine control valve is operatively connected to the brine outlet of the membrane and the brine collection tank.

21. The reverse osmosis system of claim 20 wherein the discharge valve is operatively connected to the pump inlet of the energy recovery turbocharger.

22. The reverse osmosis system of claim 21 wherein the brine control valve is operatively connected to the turbine inlet of the energy recovery turbocharger.

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