The present invention relates generally to the field of reverse osmosis processes. More specifically, the present invention relates to systems and methods for enhancing the efficiency of reverse osmosis processes.
Reverse osmosis (RO) processes can be employed to remove contaminants from water. RO systems can be used in a wide variety of applications, such as production of drinking water or removing hardness from water or other such fluids to prevent scaling, among other applications. RO systems can be used in applications where clean water is scarce, such as facilities in remote locations or in mobile applications such as emergency vehicles, recreational vehicles, military vehicles and marine applications, among other uses.
In many of these applications, the efficiency of RO systems is an ongoing challenge. This can be especially true for applications in which the supply of energy or feed water is limited. For example, when RO systems are used in remote locations or mobile applications, the supply of power and/or feed water can be limited. The efficiency of an RO system can be measured in many ways, including the amount of energy required to purify a given amount of water, or alternatively, the amount of purified water obtained from a given amount of unpurified water fed into the system.
RO systems can comprise a RO module and a pumping system. The pumping system can supply pressurized fluid to the RO module, and the RO module typically has a RO membrane. In some applications, water molecules can pass through the RO membrane and, depending on what type of membrane is used, certain molecules, ions, atoms or other undesirable contaminants can be prevented from passing through the membrane. This yields a purified water stream from a purified side of the RO membrane and a concentrate stream from a concentrate side of the RO membrane.
In RO systems, the osmotic pressure (often referred to as the normal osmotic pressure) is the applied pressure required to prevent the flow of a water across a membrane which separates solutions of different concentrations. The water entering a RO module can be introduced at a pressure greater than the osmotic pressure. This elevated pressure can facilitate water crossing the membrane while certain contaminants can be partially or completely prevented from crossing the membrane. Thus, RO systems typically require energy to boost the pressure of the feed water above the osmotic pressure. Many RO systems also exhaust water from the system in order to prevent the build-up of excessive concentrations of impurities on the concentrated side of the membrane. Thus, the amount of feed water required can be significantly greater than the amount of purified water produced. Both the amount of energy and the amount of feed water required to produce an amount of purified water is an ongoing concern.
The present invention is related to the purification of water using RO systems, including systems which have improved efficiency, for example improved efficiency with respect to energy consumption and/or feed fluid requirements.
In one illustrative embodiment, a RO system is provided that includes a RO module and a pump system. A first inlet port of the pump system can be fluidly connected to a feed fluid stream (e.g. water), and an outlet port of the pump system can be fluidly connected to an inlet port of the RO module. The RO system can also have an outlet port on the concentrate side of the RO module for exhausting concentrate and an outlet stream on the purified side of the RO membrane for exhausting purified fluid. The concentrate outlet port can be fluidly connected to a second inlet port of the pump system, creating a recycle stream. In some cases, this recycle stream can be a closed loop, conserving a portion or substantially all of the pressure of the water exhausted from the concentrate side of the RO module. The pump system can be configured to receive both the feed stream and the recycle stream, and raise these two streams to a predetermined pressure for introduction into the RO module. Further, the closed-loop recycle stream can have an exhaust line for exhausting a portion of the recycled concentrate. Exhausting a portion of this concentrate stream can help maintain an acceptable concentration of impurities on the concentrate side of the membrane. In a further embodiment, a valve can be placed in the exhaust line to regulate the volume of the recycle concentrate that is exhausted from the system.
In another illustrative embodiment, an RO system can have an RO module and a pump system, where the pump system comprises two pumps. A first pump can be configured to receive a feed water stream and a second pump can be configured to receive a recycle stream from the concentrate side of the RO module. Each pump can have a pumping chamber. The respective streams can enter the pumping chambers at relatively lower pressures and leave the pumping chambers at relatively higher pressures. In some cases, a positive displacement pumping member can be disposed in these pumping chambers. In one embodiment, the chambers can be adjacent one another and a single positive displacement pumping member can act on both chambers. In such a case the chambers and the single positive displacement pumping member can be referred to as two pumps or, alternatively, can be collectively referred to as a double acting pump, for example a double acting simplex positive displacement pump. Other examples of the pump could be a double acting simplex plunger pump or a double acting simplex piston pump.
Efficiency of the RO system can be measured based on the amount of feed fluid that is required to produce a certain volume of purified fluid. Efficiency can also be described in terms of the amount of energy required to produce a certain volume of purified fluid.
In yet another embodiment of the invention, a method for purifying fluid with a RO system is provided that includes the step of providing feed fluid to the inlet of a first pump. The method can also include the step of providing a recycle stream from a concentrate outlet of a RO module to an inlet of a second pump. The method can comprise a step of using the first pump to boost the pressure of the feed fluid and the method can further comprise the step of using the second pump to boost the pressure of the recycle stream. In an optional additional step, the two streams with boosted pressures can be mixed together and the method can also comprise the step of providing the two streams to the inlet of the RO module. The two pumps in this method can also be configured such that they can be referred to as one double acting positive displacement pump, for example a simplex double acting plunger pump or a simplex double acting piston pump.
The following description should be read with reference to the drawings, in which like elements in different drawings are numbered in like fashion. The drawings, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of the invention. Although examples of construction, dimensions, and materials are illustrated for the various elements, those skilled in the art will recognize that many of the examples provided have suitable alternatives that may be utilized.
Referring now to
The pump system 3 can have a feed fluid inlet 10, a recycle inlet 14 and a pressurized fluid outlet 11. The feed fluid inlet 10 can connect to a feed fluid stream 101 such as a water stream, the recycle inlet 14 can connect to a recycle stream 103, and a pressurized fluid stream 102 can fluidly connect the pressurized fluid outlet 11 to the RO water inlet 12 of the RO module 2. In some embodiments, the pump system 3 can have two pumping chambers. In such cases, the pressurized fluid stream 102 can comprise two conduits, one running from an exit of each of the pumping chambers, and delivering the fluid to the RO module. Also, the two conduits of the pressurized water stream 102 could later be joined into a single conduit, which can lead to the RO module 2.
It is also contemplated that the fluid streams (for example, fluid streams 101, 102, 103) can have other structures or modules disposed in them. As an example, the feed stream 101 and/or the pressurized fluid stream 102 can have a filter placed in it, for example a media filter, a screen filter or any other type of filter that can remove particulate matter and/or other undesirable substances from the water stream. It is also contemplated that one or more of the fluid streams (for example, 101, 102, 103, 107) can have a water sanitization system, such as an ozone treatment module, placed in the line in order to kill any undesired organisms in the fluid such as viruses or bacteria.
In the illustrative embodiment of
Further, in some embodiments, the recycle stream 103 can be split into two fluid pathways, with a first fluid pathway allowing the recycle stream 103 to continue on to the pump system and a second fluid pathway leading to an effluent stream 105. A valve 104 can be disposed in the effluent stream 105. The effluent stream can lead to a drain or storage container 106. The valve 104 can be a pressure regulating bypass valve. In such a case, the valve can release an amount of concentrate from the recycle stream 103 into the drain 106 in order to maintain a certain pressure in the recycle stream 103. In some cases, maintaining a constant pressure throughout the RO system 1 can be desirable if avoiding changes in pressure in the RO system is desirable, especially across the RO membrane 4. In other embodiments, the flow of the effluent stream 105 can be controlled using a flow set-point rather than the pressure set-point. In such cases, other types of valves could be used, such as needle valves, ball valves, gate valves, or other flow-control valves known in the art. In some cases, a controller (not shown) may be provided to actively or periodically change the flow of the effluent stream 105. For example, in cases of a higher temporary demand for purified water, the flow of the effluent stream 105 may be reduced. Likewise, during periods of lower demand for purified water, the flow of the effluent stream may be increased to flush the system of any excessive concentrate.
When a RO system has an exhaust line, for example exhaust line 106 of
In addition, the purified water stream 15 can be run through additional banks of RO modules. In these modules, a fluid stream running from the concentrate side of the membrane can be connected with the recycle stream 103 and the purified stream can contain purified fluid that can in some cases be run through additional banks of RO modules. In
Turning now to
In some embodiments, the system can comprise conduits that fluidly connect the exit ports (36, 38) to the vessel 34, and the pressurized fluid line 302 can then further extend from the vessel exit port 39 to a RO module. Alternatively, the exit ports (36, 38) can open directly into the vessel 34, and the pressurized fluid line 302 can then extend from the vessel exit port 39 to a RO module. In yet another alternative, it is contemplated that pressurized fluid line 302 can comprise multiple conduits that lead from the exit ports (36, 38). These conduits can be joined downstream into one conduit, which can then lead to a RO module. Such an embodiment can have a vessel 34 disposed in the pressurized fluid line 302 after the conduits are joined, for example for prevention or mitigation of pressure variation in the fluid being supplied to the RO module.
In the illustrative embodiment shown in
In some cases, the inlet and outlet ports (35, 36, 37, 38) of the pumps (32, 33) can include check valves. For example, the inlet ports (35, 37) of the pumps (32, 33) can have check valves that partially or totally limit the flow of fluids to a direction entering the pumps (32, 33). Outlet ports (36, 38) can have check valves that partially or totally limit the flow of fluids to a direction exiting the pumps (32, 33).
It is contemplated that any of the embodiments of pumping systems described with respect to
In the example of
Turning to
In some cases, for example as shown in
In some cases, the manifold 411 can be removably secured to, or it can be separate from, the pump housing 47. In other cases, the manifold 411 can be integral with the pump housing 47. Further, in some cases, both the vessel 424 and the manifold 411 can be integral with the pump housing 47, they can both be removably secured to the pump housing 47, or they can both be separate from the pump housing 47.
In the illustrative embodiments of
As shown in the embodiment of
In some cases where the positive displacement pumping mechanism 43 acts on both the first and second pumping chambers (40, 41), as shown in
It is contemplated that any of the embodiments described with respect to
In addition to a plunger-type pump being used in the pumping system, several other types of pumps can be used in the pumping system in accordance with this invention. As one example,
In the embodiment of
In an embodiment such as
As with the pump system shown in
It is contemplated that any of the embodiments described with respect to
Turning now to
As with the pump system shown in
In this embodiment, a first positive displacement pumping mechanism can be disposed in the first pumping chamber 71. For example, the first positive displacement pumping mechanism can be a first plunger 73. A second positive displacement pumping mechanism can be disposed in the second pumping chamber 72. For example, the second positive displacement pumping mechanism can be a second plunger 74.
The first and second plungers (73, 74) can be connected to one or more drives. The one or more drives can move the plungers (73, 74) through a pumping motion. For example, when a drive moves the first plunger 73 in the direction of arrow “A”, the pressure can be increased in the first chamber 71, forcing fluids out of the first chamber 71. When a drive moves the first plunger 73 in the direction of arrow “B”, the pressure in the first chamber 71 can be decreased, which can draw fluids into the first chamber 71. Similarly, the second plunger moving in the direction of arrow “A” can lower the pressure in the second chamber 72, which can force fluids out of the second chamber 72. Further, moving the second plunger in the direction of arrow “B” can increase the pressure in the second chamber 72, which can draw fluids into the second chamber 72.
The plungers can each have their own drive mechanism, which can be any drive mechanism known in the art, such as an electric motor. Also, as shown in the illustrative embodiment of
It is contemplated that any of the embodiments described with respect to
In some embodiments, the systems can be incorporated into portable units that can be battery powered and/or powered from an existing electrical grid, and can be used in locations where purified water is relatively scarce. In some cases, the relatively low amount of energy required to run the RO systems described herein can facilitate the use of solar power to run the RO system.
In another example embodiment, any of the systems described above can be used to purify water for cleaning systems or other systems where impurities can affect the operation. For example, in clothes, window, or car cleaning operations, metal ions or other materials in the water can cause staining or allow residue to be present after the water is dried from the cleaned object (staining or residue can cause water-spotting in some cases). One example of a cleaning operation is described in U.S. Pat. No. 6,276,015, entitled “Method of Cleaning a Soiled Surface”, the entirety of which is herein incorporated by reference. A RO system can be used to remove the metal ions or the materials that cause the staining or water-spotting.
As another example, in some operations where build-up of scale is an issue, the RO systems described above can be used to remove materials that cause the scaling. For example, in misting systems where water evaporation occurs readily, build-up of scale can be an issue. Removing the scaling materials from the water prior to the misting operation can lessen the amount of scaling that occurs. One example of such a system is described in U.S. Pat. No. 6,454,190, entitled “Water Mist Cooling System”, the entirety of which is herein incorporated by reference.
Yet another embodiment of the invention comprises a method of purifying fluid with an RO system. The RO system can have a RO module and a pumping system. The RO module can have a concentrate side and a purified side, separated by a RO membrane. The method includes the step of introducing feed fluid to a RO system. The pressure of the feed fluid can be boosted using a pumping system, where the pumping system can be any of the systems described above. The method can further comprise the step of exhausting a portion of the fluid from the concentrate side of the RO module, forming a recycle line. At least a portion of the exhausted concentrate can be introduced to the pumping system through the recycle line. The pumping system can be used to boost the pressure of both the feed fluid and the recycled concentrate to above an osmotic pressure, and these pressurized fluids can then be fed into the concentrate side of the RO module. In addition, the method can include the step of splitting off a portion of the concentrate exhaust into an effluent stream that can exit the system. A further step in the method includes recovering the energy of this effluent stream.
Having thus described the several embodiments of the present invention, those of skill in the art will readily appreciate that other embodiments may be made and used which fall within the scope of the claims attached hereto. Numerous advantages of the invention covered by this document have been set forth in the foregoing description. It will be understood that this disclosure is, in many respects, only illustrative. Changes may be made in details, particularly in matters of shape, size and arrangement of parts without exceeding the scope of the invention.