Reverse osmosis system

Abstract

The invention concerns a reverse osmosis system (1) with at least one membrane unit (2) comprising an inlet (3), a permeate outlet (4) and a concentrate outlet (5), a high-pressure pump (8) that is connected to the inlet (3), a pressure exchanger (11) comprising at least one high-pressure concentrate connection (HPC), and a booster pump. It is endeavored to achieve the lowest possible energy consumption. For this purpose, the booster pump is made as a displacement pump (16) that is arranged between the concentrate outlet (5) and the high-pressure concentrate connection (HPC) of the pressure exchanger (11).

Claims

1. A reverse osmosis system comprising: at least one membrane unit comprising an inlet, a permeate outlet and a concentrate outlet, a high-pressure pump that is connected to the inlet, a pressure exchanger comprising at least one high-pressure concentrate connection, and a booster pump, wherein the booster pump is a displacement pump that is arranged between the concentrate outlet and the high-pressure concentrate connection of the pressure exchanger and configured to feed concentrate from the concentrate outlet into the high-pressure concentrate connection of the pressure exchanger, and wherein the pressure exchanger and said displacement pump have a common drive shaft.

2. The reverse osmosis system according to claim 1, wherein the volumes of the pressure exchanger and the displacement pump are adapted to one another.

3. The reverse osmosis system according to claim 1, wherein the displacement pump is made as a variable displacement pump.

4. The reverse osmosis system according to claim 3, wherein it has at least one concentrate sensor.

5. The reverse osmosis system according to claim 1, wherein the displacement pump and the pressure exchanger have a common shaft sealing area.

6. The reverse osmosis system according to claim 1, wherein the displacement pump has a pump outlet on a front side, with which it is arranged on the pressure exchanger.

7. The reverse osmosis system according to claim 6, wherein the pump outlet is arranged opposite to an outlet (HPF) of the pressure exchanger.

8. The reverse osmosis system according to claim 5, wherein a unit comprising the displacement pump and the pressure exchanger can also be operated in the opposite flow direction, meaning that the displacement pump is connected in series after the pressure exchanger.

9. The reverse osmosis system according to claim 1, wherein the high-pressure pump has a common drive shaft with the displacement pump.

10. The reverse osmosis system according to claim 9, wherein the high-pressure pump, the pressure exchanger and the displacement pump are assembled to form one unit.

11. The reverse osmosis system according to claim 10, wherein the pressure exchanger is arranged between the displacement pump and the high-pressure pump.

12. The reverse osmosis system according to claim 11, wherein the pressure exchanger and the high-pressure pump have a common outlet (HPF) from the one unit and/or a common inlet (LPF) into the one unit.

13. The reverse osmosis system according to claim 1, wherein, on the concentrate side, the pressure exchanger has a concentrate influencing device comprising at least one of the following elements: a bypass valve, a pressure relief valve and a throttle valve.

14. The reverse osmosis system according to claim 1, wherein a non-return valve is arranged in parallel to the high-pressure pump.

15. A reverse osmosis system comprising: at least one membrane unit comprising an inlet, a permeate outlet and a concentrate outlet; a high-pressure pump that is connected to the inlet; a pressure exchanger comprising at least one high-pressure concentrate connection; and a booster pump; wherein the booster pump is a displacement pump that is arranged between the concentrate outlet and the high-pressure concentrate connection of the pressure exchanger and configured to feed concentrate from the concentrate outlet into the high-pressure concentrate connection of the pressure exchanger, and wherein said high-pressure pump and said displacement pump have a common drive shaft that extends through said pressure exchanger.

16. The reverse osmosis system according to claim 15, wherein the volumes of the pressure exchanger and the displacement pump are adapted to one another.

17. The reverse osmosis system according to claim 15, wherein the displacement pump is made as a variable displacement pump.

18. The reverse osmosis system according to claim 17, additionally comprising at least one concentrate sensor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following, the invention is described on the basis of preferred embodiments in connection with the drawings, showing:

(2) FIG. 1 shows a first embodiment of a reverse osmosis system,

(3) FIG. 2 shows a second embodiment of a reverse osmosis system, and

(4) FIG. 3 is a schematic sectional view of a unit with pressure exchanger and displacement pump, and high pressure pump on a common drive shaft with the unit.

DETAILED DESCRIPTION

(5) FIG. 1 is a schematic view of a reverse osmosis system 1, also called reverse osmosis plant or reverse osmosis arrangement.

(6) The reverse osmosis system comprises a membrane unit 2 with an inlet 3, a permeate outlet 4 and a concentrate outlet 5. A membrane 6 is arranged between the inlet 3 and the permeate outlet 4.

(7) Of course, the membrane unit 2 can also have more than one inlet 3, one permeate outlet 4 and/or one concentrate outlet 5, and a corresponding housing.

(8) By means of a high-pressure pump 8 that is driven by a motor 9, the membrane unit 2 is supplied with feed water from a storage 7, for example the sea. The high-pressure pump 8 can, for example, be a piston pump. The motor 9 can be an electric motor that is controlled by a frequency converter. Thus, it is possible to drive the high-pressure pump 8 at variable speeds and thus variable supply amounts.

(9) For reasons of simplicity, the water from the storage 7 will, in the following, simply be called “feed water”.

(10) Via a displacement pump 16, the concentrate outlet 5 is indirectly connected to a concentrate side 10 of a pressure exchanger 11. In this connection, the displacement pump is connected to a high-pressure concentrate connection HPC of the concentrate side 10. In this embodiment, the concentrate side 10 also comprises a low-pressure concentrate connection LPC that is again connected to the storage 7.

(11) The pressure exchanger 11 also comprises a feed water side 12 with a low-pressure feed water connection LPF and a high-pressure feed water connection HPF. The low-pressure feed water connection LPF is connected to a feed water pump 13 that also supplies the high-pressure pump 8 with feed water. The feed water pump 13 is also driven by a motor 14. Also different pumps can be used to supply the high-pressure pump 8 and the pressure exchanger 11.

(12) Instead of the subdivision into a concentrate side 10 and a feed water side 12, the high-pressure concentrate connection HPC and the low-pressure feed water connection LPF as well as the high-pressure feed water connection HPF and the low-pressure concentrate connection LPC can be arranged on one side. This will cause a reversed direction of the flow through a low-pressure area of the pressure exchanger 11. The flow from the low-pressure concentrate connection LPC to the high-pressure concentrate connection HPC in the pressure exchanger 11 then occurs in the different direction than the flow from the low-pressure feed water connection LPF to the high-pressure feed water connection HPF.

(13) The pressure exchanger 11 is driven by a motor 15, here making a rotor of the pressure exchanger 11 rotate. In a manner known per se, a channel of the rotor is filled with feed water via the low-pressure feed water connection LPF. The feed water presses concentrate contained in the channel out through the low-pressure concentrate connection LPC, the concentrate thus returning to the storage 7. When the rotor has been turned by a predetermined angle, for example approximately 180°, the concentrate at the high-pressure concentrate connection HPC will push the feed water out through the high-pressure feed water connection HPF.

(14) Between its inlet 3 and its concentrate outlet 5, the membrane unit 2 has a certain pressure loss, and also the pressure exchanger 11 causes a certain pressure loss. Accordingly, before the pressure exchanger 11 the booster pump is arranged in the form of a displacement pump 16. The displacement pump 16 is driven by a motor 17. By means of the displacement pump, the pressure of the concentrate before the pressure exchanger 11 is increased so much that the feed water is supplied from the high-pressure feed water connection under a pressure that corresponds to the pressure at the outlet of the high-pressure pump 8.

(15) With each rotation, the displacement pump supplies a constant volume, independently of the speed. This gives an approximately linear correlation between the speed and the supply amount. The displacement pump 16 can be a piston pump, a gearwheel pump, a gerotor pump, an orbit pump, a membrane pump, a hose pump, a peristaltic pump, a screw pump, a spindle pump, an eccentric screw pump, a vane pump or the like. Such a displacement pump 16 has a better efficiency than, for example, a centrifugal pump, a jet pump or a turbine pump.

(16) The motors 9, 14, 15 and 17 can be controlled by a control device 18. The control device 18 “knows” the output provided by the pressure exchanger 11. Accordingly, the control device 8 can control the motor 17 of the displacement pump 16 so that the displacement pump 16 can relatively easily provide the supply amount that is adapted to the output of the pressure exchanger 11. A major advantage of the displacement pump 16 namely is that, as mentioned, that it has a linear dependence between the speed and the supply amount, so that the supply amount can be accurately set by a change of the speed. Thus, it is avoided that concentrate from the concentrate connection 5 is mixed with feed water from the feed pump 13. In many cases, it is also possible to adjust the pressure independently of the load.

(17) If further information is required, for example information about the pressure at the concentrate outlet 5, a corresponding pressure sensor may be arranged here, which is then also connected to the control device 18. For reasons of clarity, however, this is not shown.

(18) Optionally, the pipe between the concentrate outlet 5 and the high-pressure concentrate outlet HPC of the pressure exchanger 11 may comprise a measuring motor, not shown, that is also connected to the control device 18.

(19) The measuring motor should also be a motor with constant displacement, that is, independently of the speed, the measuring motor has a constant output per rotation.

(20) The displacement pump 16 can also be a variable displacement pump, that is, the volume displaced per rotation can be set at a desired value.

(21) FIG. 2 shows a modified embodiment, in which the same elements as in FIG. 1 have the same reference signs. For reasons of clarity, the control device 18 and its connections are not shown here.

(22) In this embodiment, the pressure exchanger 11 and the displacement pump 16 are assembled to one component 22.

(23) The motor 15 is connected to both the pressure exchanger 11 and the displacement pump 16 via a common drive shaft 21. In this connection, front sides of the displacement pump 16 and the pressure exchanger 11 are connected, for example with flanges arranged on the front sides, bolts, not shown in detail, ensuring that the displacement pump 16 and the pressure exchanger 11 form a unit.

(24) By means of this assembly to one unit 22, it can now be ensured that, in a manner of speaking, the high-pressure concentrate connection HPC and the high-pressure feed water connection HPF are arranged on one line and are in alignment with an outlet 23 of the displacement pump 16. The displacement pump 16, in this case, for example, a gerotor pump, can then supply pressure boosted feed water at its outlet 23. The pressure at the high-pressure feed water connection HPF then corresponds to the pressure at the outlet of the high-pressure pump 8.

(25) Due to the assembly of displacement pump 16 and pressure exchanger 11, an external piping, that is, a piping between the individual parts can be avoided. On the one side, this saves costs during manufacturing. Further, the energy consumption is reduced, as pressure losses can be reduced.

(26) Further, an advantage occurs in that at the pressure exchanger 11 and at the displacement pump 16, the drive shaft 21 has a common shaft sealing area 24. Accordingly, the drive shaft 21 must only be sealed towards the outside at the pressure exchanger 11. For this purpose, a sealing 25 is provided at the front side of the pressure exchanger 11 that faces away from the displacement pump 16. This sealing 25 is loaded by a relatively low pressure.

(27) FIG. 2 shows that the concentrate side 10 of the pressure exchanger 11 is provided with several concentrate flow influencing devices. These include a bypass valve 26 that can generate a short circuit over the inlet of the displacement pump 16 and be opened manually or by a control device, a pressure relief valve 27 that reacts to an overpressure and permits this overpressure to be discharged to the storage 7, and a throttle valve 28 that contributes to keeping the risk of cavitation small and controlling the fluid flow from the low-pressure feed water connection LPF to the low-pressure concentrate connection LPC.

(28) In parallel to the high-pressure pump 8 is arranged a non-return valve 29 that is, for example, formed as a spring-loaded non-return valve and prevents the pressure difference over the high-pressure pump 8 from becoming too large.

(29) The listing of the valves is not necessarily complete. For example, also deaeration valves for all devices are possible.

(30) In a manner not shown in detail, all embodiments may provide that also in connection with the low-pressure feed water connection LPF or the low-pressure concentrate connection LPC a measuring motor is arranged to drive the pressure exchanger 11. In this case, the pressure from the feed pump 13 would have to be increased in order to be able drive the measuring motor that can then in turn drive the pressure exchanger 11.

(31) FIGS. 1 and 2 further show a concentrate sensor 30 that is connected to an adjustment device of the displacement pump 16. In this case, the displacement pump 16 is made with an adjustable displacement. The concentrate sensor 30 currently determines the concentration of the feed water supplied to the membrane unit 2. When it detects that concentrate (or too much concentrate) gets into the feed water, the displacement of the displacement pump 16 is reduced accordingly, so that the output of the displacement pump 16 is adapted.

(32) Further sensors, for example flow sensors, can be used in suitable spots. In FIG. 3 the pressure exchanger 11 and the displacement pump 16 are assembled to one component. The pressure exchanger 11 and the displacement pump 16 have a common drive shaft 31. In this connection, the drive shaft 31 also extends through a front side 32 of the pressure exchanger 11 that faces away from the displacement pump 16.

(33) Also the high-pressure pump 8 can be arranged at the front side 32. The drive shaft 31 can then also extend through the high-pressure pump 8, so that on a side facing away from the pressure exchanger 11 it can be connected to a motor.

(34) The pressure exchanger has a first connection 33 and a second connection 34, one of the connections 33, 34 being the low-pressure feed water connection LPF and the respective other connection 33, 34 being the low-pressure concentrate connection LPC.

(35) The allocation of the connection 33 as low-pressure feed water connection LPF adjacent to the front wall 32 and opposite to the high-pressure feed water connection HPF is particularly advantageous, if the high-pressure pump is arranged at the front wall 32.

(36) The pressure exchanger 11 and the high-pressure pump 8 can then have the connection 33 as common low-pressure feed water connection LPF and also use the high-pressure feed water connection HPF in common. Compared with a normal process, in which the low-pressure feed water connection LPF is arranged on the same side as the high-pressure feed water connection HPF, the pressure exchanger will then be passed by the flow in the opposite direction, as the low-pressure feed water connection LPF is arranged on the side of the high-pressure concentrate connection HPC, and the high-pressure feed water connection HPF is arranged on the side of the low-pressure concentrate connection LPC. Thus, the pressure exchanger 11 and the high-pressure pump 8 can be connected by means of common pipes to the membrane unit 2 and the feed water pump 13, respectively. This ensures a very simple design that is highly unsusceptible to faults.

(37) Although various embodiments of the present invention have been described and shown, the invention is not restricted thereto, but may also be embodied in other ways within the scope of the subject-matter defined in the following claims.