JP2009297671A - Displacement type energy recovery apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a displacement type energy recovery apparatus used for a sea water desalination system or an apparatus therefor wherein excessive processing accuracy to an energy recovery chamber constituting the apparatus is not needed, long processing is not needed, loss due to sliding resistance does not occur as a solid piston does not exist, and friction loss generated in the energy recovery chamber can be reduced. <P>SOLUTION: In the displacement type energy recovery apparatus 23 for recovering energy to a low pressure liquid LW side by increasing the pressure of the low pressure liquid LW by transmitting the pressure of flowing high pressure liquid HW to the flowing low pressure liquid LW, the energy recovery chamber 21 for introducing the high pressure liquid HW and low pressure liquid LW is provided, non-miscible fluid NF not miscible with any of the high pressure liquid HW and low pressure liquid LW is contained in the energy recovery chamber 21, and the high pressure liquid HW is separated from the low pressure liquid LW by the non-miscible fluid NF. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an energy recovery device used in a seawater desalination apparatus or a seawater desalination system that removes salt from seawater and desalinates seawater. In particular, the present invention relates to a positive displacement energy recovery apparatus capable of improving the reliability, high-efficiency (energy saving) operation of the seawater desalination apparatus / system, and high recovery efficiency of fresh water.

  A seawater desalination plant that uses the reverse osmosis membrane method mainly comprises a pretreatment system, a high-pressure pump, a reverse osmosis membrane cartridge, and an energy recovery device. The taken seawater is adjusted to a condition of constant water quality by a pretreatment system, and then pressurized by a high-pressure pump and pumped to a reverse osmosis membrane cartridge. Part of the high-pressure seawater in the reverse osmosis membrane cartridge overcomes the osmotic pressure, passes through the membrane, and is taken out as fresh water from which salt has been removed. Other seawater is discharged as a reject (concentrated water) from the reverse osmosis membrane cartridge in a state where the salinity is high and concentrated. Here, the maximum operating cost (electric power cost) in a seawater desalination plant greatly depends on the energy for raising the pretreated seawater to a pressure that can overcome the osmotic pressure, that is, the reverse osmotic pressure, that is, the pressurized energy by the high-pressure pump. To do.

  That is, more than half of the power cost, which is the maximum operating cost in a seawater desalination plant, is often spent on pressurization by a high-pressure pump. Therefore, an energy recovery device that effectively recovers the pressure energy held by the high salinity and high pressure reject discharged from the reverse osmosis membrane cartridge plays an important role.

  FIG. 18 is a schematic diagram showing a configuration example of a seawater desalination plant using the reverse osmosis membrane method. As shown in FIG. 18, the seawater 1 taken by the water intake pump 2 is adjusted to a predetermined water quality condition by the pretreatment device 3 and then pressurized by the high pressure pump 5 driven by the electric motor 6, 7 and then fed to the reverse osmosis membrane cartridge 8. On the other hand, a part of the seawater in the high-pressure chamber 9 in the reverse osmosis membrane cartridge 8 overcomes the osmotic pressure, passes through the reverse osmosis membrane 10, and is taken out as demineralized water 12 from which the salt content has been removed. The other seawater is discharged from the reverse osmosis membrane cartridge 8 to the concentrated seawater line as a high-pressure reject 13 in a state where the salinity is increased and concentrated. The high-pressure reject (high-pressure concentrated water) 13 discharged from the cartridge 8 is introduced into the energy recovery device 23.

The energy recovery device 23 uses a positive displacement energy recovery device as a measure (system) for effectively recovering and using the pressure energy possessed by the high-salt concentration high-pressure reject 13 and making the system operation highly efficient.
Examples of conventional configurations of the positive displacement energy recovery apparatus include US Pat. No. 5,306,428 (Patent Document 1) and US Pat. No. 5,977,429 (Patent Document 2).

FIG. 19 is a schematic diagram illustrating a configuration example of a conventional positive displacement energy recovery apparatus. The positive displacement energy recovery device 23 mainly includes a direction switching valve 20, two energy recovery chambers 21, and a check valve module 22.
The function of the positive displacement energy recovery device is as follows:
(1) The high pressure reject 13 from the reverse osmosis membrane cartridge 8 is introduced into the direction switching valve 20,
(2) By driving the direction switching valve 20, the high-pressure rejects 13 are alternately introduced into the energy recovery chambers 21,
(3) Drive the piston in the energy recovery chamber 21,
(4) The seawater introduced into the energy recovery chamber 21 is boosted from the water supply line 4 through the check valve module 22 as the piston is driven,
(5) Via the check valve module 22, the seawater boosted in the energy recovery chamber 21 is discharged to the supply seawater bypass boost line 24 and introduced into the booster pump 27 driven by the electric motor 26.
That is. Reference numeral 25 denotes a discharge line.

  By using this positive displacement energy recovery system in a seawater desalination plant, it is possible to reduce the flow rate of fluid after pretreatment that is pressurized with a high-pressure pump, and to reduce the energy required for operation (flow rate and pressure). As a result, the operation efficiency of the system is increased.

FIG. 20 is a schematic view showing a conventional configuration example of the energy recovery chamber. As shown in FIG. 20, the energy recovery chamber 21 includes a cylindrical cylinder 131 and a piston 133 that reciprocates within the cylinder 131. Two input / output ports 131 a and 131 b are formed in the cylinder 131. The piston 133 is installed in the cylinder 131 so as to be movable in the axial direction.
The function of the energy recovery chamber 21 is as follows.
(1) The piston 133 is driven by the pressure of the high-pressure reject 13 introduced into the chamber 21 through the direction switching valve 20, and the pressure of the seawater introduced into the chamber 21 by the water intake pump 2 across the piston 133 is increased. Done
(2) The piston 133 is driven by the discharge pressure of the intake pump 2, and the reject introduced into the chamber 21 across the piston 133 is discharged to the discharge line 25 via the direction switching valve 20.
That is.

That is, in the energy recovery chamber 21, (1) introduction of seawater → (2) driving of piston by introduction of high pressure reject → (3) pressure increase of seawater → (1) introduction of seawater (1) ) → (2) → (3) is repeated to introduce and derive the fluid.
The cycle of (1) → (2) → (3) can be rephrased as follows. That is,
(A) In FIG. 20, when the piston 133 moves from the left end of the cylinder 131 to the right end, seawater is introduced and concentrated seawater (reject) is discharged.
(B) When the piston 133 moves from the right end to the left end of the cylinder 131, the seawater is increased in pressure by introducing high-pressure concentrated seawater (high-pressure reject).
(C) By repeating the above (a) and (b) alternately with the two cylinders 131, the energy by the pressure and flow rate of the high-pressure concentrated seawater is recovered in a manner of increasing the pressure of the seawater at a constant flow rate.

The energy recovery chamber of the conventional positive displacement energy recovery apparatus represented by US Pat. No. 5,306,428 (Patent Document 1) and US Pat. No. 5,977,429 (Patent Document 2) as described above has the following problems. Has a point.
(1) The outer peripheral surface of the piston slides with respect to the inner surface of the cylinder of the energy recovery chamber. In particular, in the chamber formed for the purpose of processing a large flow rate, the area of the sliding surface of the piston (proportional to the piston diameter) and the reciprocating range (stroke) of the piston become large. As an example of the dimensions of the chamber, the cylinder inner diameter (≈piston outer diameter) is about 0.4 m, and the chamber length is about 7 m. As shown in this example, the energy recovery chamber is large in size, and the piston, which is a component of the energy recovery chamber, slides in the cylinder. Therefore, the surface accuracy and parallelism of the sliding surface of the piston and cylinder are high, and long in the axial direction. It is necessary to manufacture a long cylinder (cylindrical), and the manufacturing cost is high.
(2) In order to prevent the mixing of seawater and concentrated seawater, it is desirable to reduce leakage on the side surface of the piston. However, the design that reduces leakage on the side surface of the piston (the use of a seal and the miniaturization of the gap) has the effect of increasing the sliding resistance of the piston, resulting in energy loss.
(3) In order to prevent the mixing of seawater and concentrated seawater, it is desirable to reduce the time during which seawater and concentrated seawater are in contact with each other via the piston (that is, the movement time of the piston). For this purpose, it is desirable that the moving speed of the piston is high, but this is directly linked to an increase in energy loss caused by the sliding of the piston. Further, when the moving speed of the piston is increased, the flow velocity in the energy recovery chamber is also increased, and the friction loss between the seawater and the inner wall of the chamber is increased. Moreover, the short movement time of the piston means that the drive frequency of the sluice valve and the check valve is increased, and the life of valves and the like is shortened.

US Pat. No. 5,306,428 US Pat. No. 5,797,429

  The present invention has been made in view of the above circumstances, and in a positive displacement energy recovery device used in a seawater desalination system or the same device, excessive energy processing accuracy is not required for the energy recovery chamber constituting the device. In addition, there is no need for long processing, there is no solid piston, so there is no loss due to sliding resistance, and the volume type that can reduce the friction loss that occurs in the energy recovery chamber The object is to provide an energy recovery device.

In order to achieve the above-described object, one aspect of the present invention is a volumetric type in which the pressure of the flowing high-pressure liquid is transmitted to the flowing low-pressure liquid to increase the pressure of the low-pressure liquid and recover energy on the low-pressure liquid side. In the energy recovery apparatus, an energy recovery chamber for introducing the high-pressure liquid and the low-pressure liquid is provided, an immiscible fluid that does not mix with either the high-pressure liquid or the low-pressure liquid is placed in the energy recovery chamber, and the high-pressure liquid The liquid and the low-pressure liquid are separated from each other by the immiscible fluid.
According to the present invention, an immiscible fluid is placed in the energy recovery chamber, a high pressure liquid is introduced on one side of the immiscible fluid, and a low pressure liquid is introduced on the other side of the immiscible fluid. By doing so, the pressure of the high pressure liquid can be transmitted to the low pressure liquid in a state where the high pressure liquid and the low pressure liquid are separated by the immiscible fluid, and the pressure of the low pressure liquid is increased to the low pressure liquid side. Energy can be recovered.

In a preferred aspect of the present invention, the immiscible fluid is an ionic liquid.
In a preferred aspect of the present invention, the immiscible fluid is oil.
In a preferred aspect of the present invention, the immiscible fluid is composed of a nonpolar solvent.
In a preferred aspect of the present invention, the immiscible fluid is made of a liquid metal.

  In a preferred aspect of the present invention, the energy recovery chamber includes two containers and a communication portion that communicates the two containers at the bottom or bottom of the two containers, and the immiscible fluid is the high-pressure fluid. The specific gravity is greater than any of the liquid and the low-pressure liquid, is present in the lower part of the two containers, and also fills the communication part, and the high-pressure liquid exists in the upper part of one of the two containers, The low pressure liquid is present in the upper part of the other container, and during the energy recovery operation, the high pressure liquid and the low pressure liquid are separated by the immiscible fluid in the lower part of each container, It is characterized by preventing entry.

  According to the present invention, the energy recovery chamber has an input / output port (opening) formed in the upper part of the container, so that the high-pressure liquid and the low-pressure liquid are introduced into or led out from the chamber through the input / output port. It has become. The two containers contain an immiscible fluid that is immiscible with either the high pressure liquid or the low pressure liquid so as to fill approximately half the volume under the container. The high pressure liquid is introduced into the upper part of one container, and the low pressure liquid is introduced into the upper part of the other container. In the energy recovery chamber, the pressure of the high pressure liquid is transmitted to the low pressure liquid in a state where the high pressure liquid and the low pressure liquid are separated by the immiscible fluid, thereby increasing the pressure of the low pressure liquid. Recover energy on the side. During the energy recovery operation, the high-pressure liquid and the low-pressure liquid are partitioned by the immiscible fluid at the lower part of each container, and are controlled so as not to enter different container sides.

  In a preferred aspect of the present invention, the energy recovery chamber includes two containers and a communication portion that communicates the two containers at the top of the two containers, and the immiscible fluid includes the high-pressure liquid and The specific gravity is smaller than any of the low-pressure liquids, exists in the upper part of the two containers, and also fills the communication part, and the high-pressure liquid exists in the lower part of one of the two containers, and the low-pressure liquid Exists in the lower part of the other container, and during the energy recovery operation, the high-pressure liquid and the low-pressure liquid are separated by the immiscible fluid at the upper part of each container, and each enters a different container side. It is characterized by preventing it from happening.

  According to the present invention, the energy recovery chamber has an input / output port (opening) formed in the lower part of the container, so that the high-pressure liquid and the low-pressure liquid are introduced into or led out from the chamber through the input / output port. It has become. The two containers contain an immiscible fluid that is immiscible with either the high pressure liquid or the low pressure liquid so as to fill approximately the half volume of the upper side of the container. The high pressure liquid is introduced into the lower part of one container, and the low pressure liquid is introduced into the lower part of the other container. In the energy recovery chamber, the pressure of the high pressure liquid is transmitted to the low pressure liquid in a state where the high pressure liquid and the low pressure liquid are separated by the immiscible fluid, thereby increasing the pressure of the low pressure liquid. Recover energy on the side. During the energy recovery operation, the high-pressure liquid and the low-pressure liquid are partitioned by an immiscible fluid at the top of each container, and are controlled so as not to enter different container sides.

  One aspect of the seawater desalination apparatus of the present invention is a reverse osmosis membrane cartridge that generates demineralized water by membrane treatment of high-pressure seawater discharged from the high-pressure pump with a reverse osmosis membrane, and is not treated with the reverse osmosis membrane. Using the pressure of the concentrated water discharged from the reverse osmosis membrane cartridge, the volumetric energy recovery device that pressurizes the supplied seawater, and the pressurized seawater pressurized by the volumetric energy recovery device 8. A seawater desalination apparatus comprising a pressurizing apparatus that joins high-pressure seawater discharged from the high-pressure pump, wherein the positive-capacity energy recovery apparatus has a volume according to claim 1. It is a shape energy recovery device.

The present invention has the following effects.
(1) Since there is no solid piston, excessive energy processing accuracy is not required for the energy recovery chamber, and extremely long processing is not required. Therefore, the manufacturing cost can be reduced.
(2) Since there is no solid piston, there is no loss due to sliding resistance.
(3) Since the inlet-side seawater and the outlet-side seawater are harder to mix than through the piston, it is not necessary to extremely shorten the time during which the inlet-side seawater and the outlet-side seawater are in contact. For this reason, the flow velocity in the energy recovery chamber is not excessive and friction loss does not increase. Even if the volume of the energy recovery chamber is constant and the flow rate is constant, the friction loss can be reduced by changing the cross-sectional area of the chamber to reduce the flow velocity, and the design is flexible. The drive frequency of the sluice valve and check valve can be reduced, and the life of valves and the like is extended.

Hereinafter, an embodiment of an energy recovery device for seawater desalination according to the present invention will be described with reference to FIGS. 1 to 17. 1 to 17, the same or corresponding components are denoted by the same reference numerals, and redundant description is omitted.
FIG. 1 is a schematic diagram showing a configuration example of a seawater desalination plant (seawater desalination apparatus / system) to which the energy recovery apparatus of the present invention is applied. As shown in FIG. 1, seawater 1 taken by a water intake pump 2 is adjusted to a predetermined water quality condition by a pretreatment device 3, and then pressurized by a high pressure pump 5 driven by an electric motor 6, and is supplied to a high pressure line. 7 and then fed to the reverse osmosis membrane cartridge 8. The high pressure pump 5 can also control the flow rate by a control valve or an inverter. On the other hand, part of the water in the seawater in the high pressure chamber 9 in the reverse osmosis membrane cartridge 8 overcomes the osmotic pressure, passes through the reverse osmosis membrane 10 and is taken out as demineralized water 12 from which the salt content has been removed. The other seawater is discharged from the reverse osmosis membrane cartridge 8 to the concentrated seawater line as a high-pressure reject (high-pressure concentrated water) 13 in a state where the salinity is high and concentrated. The high-pressure reject 13 discharged from the reverse osmosis membrane cartridge 8 is introduced into the volumetric energy recovery device 23. In the positive displacement energy recovery device 23, a reject that has lost pressure energy due to recovery of pressure is discharged as a low-pressure energy recovery reject 25. Part of the seawater in the supply line 4 is pressurized by the positive displacement energy recovery device 23 and discharged to the supply seawater bypass boost line 24.

  The seawater discharged to the supply seawater bypass boost line 24 is boosted by the positive displacement energy recovery device 23, but has a lower pressure than the seawater toward the reverse osmosis membrane cartridge 8. Therefore, in the seawater desalination plant to which the energy recovery apparatus of the present invention is applied, an energy recovery pump turbine 18 is provided between the supply seawater bypass boost line 24 and the booster pump discharge line 19 in order to join both. It is installed. The turbine impeller installed in the turbine 14 of the energy recovery pump turbine 18 is driven by taking out a small amount of pressure energy held by the high-pressure water from the high-pressure pump 5, and is fixed on the same axis as the turbine 14. The pump up from the supply seawater bypass boost line 24 to the booster pump discharge line 19 is realized. High-pressure water discharged from the turbine impeller flows out to the turbine discharge line 27. According to this method, the electric motor 26 required in the prior art (see FIG. 22) can be omitted, and the structure of the high-pressure water seal of the booster pump 17 is not required. Cost reduction can be realized.

  FIG. 2 is a schematic diagram showing another configuration example of the seawater desalination plant to which the energy recovery apparatus of the present invention is applied. As shown in FIG. 2, seawater 1 taken by a water intake pump 2 is adjusted to a predetermined water quality condition by a pretreatment device 3, and then pressurized by a high pressure pump 5 driven by an electric motor 6, 7 is sent to the reverse osmosis membrane cartridge 8 by pressure. The high-pressure pump 5 can also control the flow rate by a control valve or an inverter. On the other hand, a part of the water in the seawater in the high pressure chamber 9 in the reverse osmosis membrane cartridge 8 overcomes the reverse osmosis pressure, passes through the reverse osmosis membrane 10 and is taken out as demineralized water 12 from which the salt content has been removed. The other seawater is discharged from the reverse osmosis membrane cartridge 8 to the concentrated seawater line as a high-pressure reject 13 in a state where the salinity is increased and concentrated. The high-pressure reject 13 discharged from the cartridge 8 is introduced into the positive displacement energy recovery device 23. In the positive displacement energy recovery device 23, a reject that has lost pressure energy due to recovery of pressure is discharged as a low-pressure energy recovery reject 25. Part of the seawater in the supply line 4 is pressurized by the positive displacement energy recovery device 23 and discharged to the supply seawater bypass boost line 24.

  The seawater discharged to the supply seawater bypass boost line 24 is boosted by the positive displacement energy recovery device 23, but has a lower pressure than the seawater toward the reverse osmosis membrane cartridge 8. Therefore, in the seawater desalination plant to which the energy recovery chamber of the present invention is applied, an energy recovery pump turbine 18 is installed between the supply seawater bypass boost line 24 and the high-pressure line 7 in order to join both. ing. The turbine impeller of the energy recovery pump turbine 18 is driven by taking a small part of the concentrated seawater line (reject) 13 to the reverse osmosis membrane cartridge 8 from the turbine inlet line 28. As a result, the pump impeller fixed coaxially with the turbine 14 rotates, and pumping up from the supply seawater bypass boost line 24 to the high pressure line 7 is realized. According to this method, it is possible to omit the electric motor 26 and the inverter (electric equipment and wiring for supplying energy from the outside) which are necessary in the prior art (see FIG. 22), and in addition to the booster pump 17 The structure of the high-pressure water seal is not required, and the structure can be greatly simplified and the cost can be reduced. As a result, the reliability of the entire system is improved. Further, by discharging a part of the reject water from the turbine inlet line 28, the amount of seawater drawn from the supply line 4 to the positive displacement piston pump 23 is reduced, and as a result, the operating flow rate of the high-pressure pump 5 is increased. The high-efficiency high-pressure pump 5 can be selected. In the embodiment shown in FIG. 1, the head of the high-pressure pump 5 needs to be set higher by the amount of energy for driving the turbine impeller of the energy recovery pump turbine 18. However, in the embodiment shown in FIG. There is an advantage.

  The energy recovery pump turbine 18 is controlled by controlling the flow rate of the inflow into the turbine section. The high-pressure concentrated seawater obtained by operating the high-pressure pump 5 using the reverse osmosis membrane cartridge 8 as a constant pressure source as the energy source is the turbine. 14, that is, it can be controlled in a self-adjusting manner by the fluid force in the system, so that operability and controllability are easier than the conventional technique (see FIG. 22) in which the booster pump 17 is driven by the electric motor 26. There is a feature that becomes.

  FIG. 3 is a schematic diagram showing the positive displacement energy recovery device 23 of the present invention applied to the seawater desalination plant shown in FIGS. 1 and 2. As shown in FIG. 3, the positive displacement energy recovery device 23 mainly includes a direction switching valve 20, two energy recovery chambers 21, and a check valve module 22. In the positive displacement energy recovery device 23, the high pressure reject 13 from the reverse osmosis membrane cartridge 8 is introduced into the direction switching valve 20, and the high pressure reject 13 is alternately introduced into each energy recovery chamber 21 by driving the direction switching valve 20. The seawater introduced into the energy recovery chamber 21 from the water supply line 4 via the check valve module 22 is pressurized, and the seawater boosted in the energy recovery chamber 21 via the check valve module 22 is supplied to the supply seawater bypass. It discharges to the boost line 24 and introduces into the booster pump 17 driven by the turbine 14 of the energy recovery pump turbine 18.

FIG. 4 is a diagram showing an energy recovery chamber according to the first embodiment of the present invention. As shown in FIG. 4, the energy recovery chamber 21 includes two cylindrical containers 31 and 32 and a communication pipe 33 that communicates the two cylindrical containers 31 and 32 on the lower side. In the present embodiment, the containers 31 and 32 are constituted by cylindrical or rectangular tubes, and the two containers 31 and 32 have substantially the same internal volume.
In the energy recovery chamber 21, two input / output ports (openings) 21a and 21b are formed at the upper end of the container. Concentrated seawater (high-concentration seawater) and seawater (through the input / output ports 21a and 21b) Raw seawater) is introduced into or led out from the chamber 21. The two cylindrical containers 31 and 32 are immiscible so as not to be mixed with either concentrated seawater (high-concentration seawater) or seawater (raw seawater) so as to fill a volume approximately half below the containers 31 and 32. Sex fluid NF is contained. Concentrated seawater (high-concentration seawater) is introduced into the upper part of one container, and seawater (raw seawater) is introduced into the upper part of the other container. In the embodiment shown in FIG. 4, concentrated seawater (high-concentration seawater) is introduced into the upper part of the container 32, and seawater (raw seawater) is introduced into the upper part of the container 31. Yes. Hereinafter, the immiscible fluid NF is also referred to as immiscible liquid NF as appropriate.

  That is, in the energy recovery chamber 21, the concentrated seawater (high-concentration seawater) HW that is a high-pressure liquid and the seawater (raw seawater) LW that is a low-pressure liquid are separated by an immiscible fluid NF. . The concentrated seawater HW, which is a high-pressure liquid discharged from the reverse osmosis membrane cartridge 8, and the seawater (raw seawater) LW supplied from the water supply line 4 are introduced into or led out from the energy recovery chamber 21, thereby By transferring the pressure to seawater (raw seawater) LW, which is a low-pressure liquid, the pressure of seawater (raw seawater) LW, which is a low-pressure liquid, is increased so that energy is recovered on the side of the seawater (raw seawater) LW I have to. During this energy recovery operation, the concentrated seawater HW, which is a high-pressure liquid, and the low-pressure seawater LW are partitioned by the immiscible fluid NF at the bottom of each container so that they do not enter different container sides. Is controlled.

  As shown in FIG. 4, the containers 31 and 32 are provided with an ultrasonic liquid level sensor 37 and a liquid level sensor 38 for measuring the liquid level by a change in electric capacity or conductivity. Thereby, the liquid level in the container is controlled so that the immiscible fluid NF is contained (present) in each container. That is, the liquid level of concentrated seawater rises and falls within the container 32, and the liquid level of seawater (raw seawater) only rises and falls within the container 31, and the concentrated seawater HW and seawater (raw seawater) LW are not. Always separated by a miscible fluid NF.

Next, the operation of the positive displacement energy recovery apparatus configured as shown in FIGS. 3 and 4 will be described with reference to FIGS.
(1) The reject 13 (concentrated seawater HW) is introduced into the supply port of the control valve 20.
(2) Intake seawater LW is introduced into the switching valve unit 22 through the water supply line 4.
(3) As the spool of the control valve 20 operates, the liquid level of the immiscible fluid NF in the energy recovery chamber 21 changes.

Operation Example (A) FIG. 5 shows a case where the spool 302 operates in a direction in which the supply port P of the control valve 20 and the control port A communicate with each other.
The pressure of the concentrated seawater HW passes through the control valve 20 (P port → A port), the surface on the control valve 20 side of the immiscible fluid NF in the energy recovery chamber 21 (upper in FIG. 5) (right side in the diagram) Act on.
The immiscible fluid NF in the energy recovery chamber 21 (upper in FIG. 5) flows from the right side container 32 to the left side container 31 in the same figure.
Seawater introduced through the switching valve unit 22 in the energy recovery chamber 21 (upper part in FIG. 5) is increased in pressure by the operation of the immiscible fluid NF, and is introduced into the booster pump 17 through the switching valve unit 22. .
At the same time, the control port B and the return port R of the control valve 20 communicate with each other, and the water supply line pressure switches the immiscible fluid NF in the energy recovery chamber 21 (lower in FIG. 5) through the switching valve unit 22. It acts on the valve portion 22 side (left side in the figure). The immiscible fluid NF in the energy recovery chamber 21 (lower in FIG. 5) flows from the left container 31 to the right container 32 in the figure.

The flow rate of the immiscible fluid NF is determined by the difference between the pressure after passing through the switching valve portion 22 and the pressure of the supply seawater bypass boost line 24, and the conditions for the immiscible fluid NF to flow are:
“Pressure after passing through switching valve portion 22”> “Supply seawater bypass boost line 24”
It becomes.
The flow rate of the immiscible fluid NF is set by opening a valve (not shown) on the supply seawater bypass boost line and operating the valve.
Next, seawater is filled in the container 31 on the switching valve portion 22 side, which is partitioned by the immiscible fluid NF in the energy recovery chamber 21 (lower in FIG. 5).

(B) FIG. 6 shows a case where the spool 302 operates in a direction in which the supply port P of the control valve 20 and the control port B communicate with each other.
The pressure of the reject (concentrated seawater HW) passes through the control valve 20 (P port → B port), the surface on the control valve 20 side of the immiscible fluid NF in the energy recovery chamber 21 (lower in FIG. 6) (right side in the figure) Acting on the surface).
The immiscible fluid NF in the energy recovery chamber 21 (lower in FIG. 6) flows from the right container 32 to the left container 31 in the figure.
Seawater introduced through the switching valve portion 22 is increased in the energy recovery chamber 21 (lower in FIG. 6) by the operation of the immiscible fluid NF, and is introduced into the booster pump 17 through the switching valve portion 22.
At the same time, the control port A and the return port R of the control valve 20 communicate with each other, and the water supply line pressure switches the immiscible fluid NF in the energy recovery chamber 21 (upper in FIG. 6) through the switching valve unit 22. It acts on the valve portion 22 side (left side in the figure). The immiscible fluid NF in the energy recovery chamber 21 (upper in FIG. 6) flows from the left container 31 to the right container 32 in the figure.

The flow rate of the immiscible fluid NF is determined by the difference between the pressure after passing through the switching valve portion 22 and the pressure of the supply seawater bypass boost line 24, and the conditions for the immiscible fluid NF to flow are:
“Pressure after passing through the switching valve unit 22”> “Pressure in the supply seawater bypass boost line 24”
It becomes.
The flow rate of the immiscible fluid NF is set by opening a valve (not shown) on the supply seawater bypass boost line and operating the valve.
Next, seawater is filled in the container 31 on the switching valve portion 22 side, which is partitioned by the immiscible fluid NF in the energy recovery chamber 21 (upper in FIG. 6).
By performing the operations (control valves) (A) and (B) in the positive displacement energy recovery device 23 as described above, the pressure of the intake seawater (raw seawater LW) is increased using the pressure of the reject (concentrated seawater HW). Is done.

FIG. 7 is a view showing an energy recovery chamber according to the second embodiment of the present invention. The energy recovery chamber according to the embodiment shown in FIG. 7 has a configuration in which the energy recovery chamber according to the embodiment shown in FIG. 4 is turned upside down. That is, as shown in FIG. 7, the energy recovery chamber 21 includes two cylindrical containers 31 and 32 and a communication pipe 33 that communicates the two cylindrical containers 31 and 32 on the upper side. . In the present embodiment, the containers 31 and 32 are constituted by cylindrical or rectangular tubes, and the two containers 31 and 32 have substantially the same internal volume.
In the energy recovery chamber 21, two input / output ports (openings) 21a and 21b are formed at the lower end portion of the container. Concentrated seawater (high-concentration seawater) and seawater (through the input / output ports 21a and 21b) Raw seawater) is introduced into or led out from the chamber 21. The two cylindrical containers 31, 32 are immiscible so as not to be mixed with either concentrated seawater (high-concentration seawater) or seawater (raw seawater) so as to fill a volume approximately half of the upper side of the containers 31, 32. Of fluid NF. Concentrated seawater (high-concentration seawater) is introduced into the lower part of one container, and seawater (raw seawater) is introduced into the lower part of the other container. In the embodiment shown in FIG. 7, concentrated seawater (high-concentration seawater) is introduced into the lower part of the container 32, and seawater (raw seawater) is introduced into the lower part of the container 31. Yes.

  That is, in the energy recovery chamber 21, the concentrated seawater (high-concentration seawater) HW that is a high-pressure liquid and the seawater (raw seawater) LW that is a low-pressure liquid are separated by an immiscible fluid NF. . The concentrated seawater HW, which is a high-pressure liquid discharged from the reverse osmosis membrane cartridge 8, and the seawater (raw seawater) LW supplied from the water supply line 4 are introduced into or led out from the energy recovery chamber 21, thereby By transferring the pressure to seawater (raw seawater) LW, which is a low-pressure liquid, the pressure of seawater (raw seawater) LW, which is a low-pressure liquid, is increased so that energy is recovered on the side of the seawater (raw seawater) LW I have to. During this energy recovery operation, the concentrated seawater HW, which is a high-pressure liquid, and the low-pressure seawater LW are partitioned by an immiscible fluid NF at the top of each container so that they do not enter different container sides. Is controlled.

  The containers 31 and 32 are provided with an ultrasonic liquid level sensor and a liquid level sensor (not shown) for measuring the liquid level based on a change in electric capacity or conductivity. Thereby, the liquid level in the container is controlled so that the immiscible fluid NF is contained (present) in each container. That is, the liquid level of concentrated seawater rises and falls within the container 32, and the liquid level of seawater (raw seawater) only rises and falls within the container 31, and the concentrated seawater HW and seawater (raw seawater) LW are not. Always separated by a miscible fluid NF. In the energy recovery chamber 21 shown in FIG. 7, the positions of concentrated seawater, seawater and immiscible fluid are different from those in the energy recovery chamber 21 shown in FIG. 4, but the operation is the same.

8A and 8B are views showing an energy recovery chamber according to the third embodiment of the present invention. FIG. 8A is a cross-sectional view, and FIG. 8B is a plan view. As shown in FIG. 8 (a), the energy recovery chamber 21 includes two cylindrical containers 41 and 42, and a container-shaped communication body 43 that communicates the two cylindrical containers 41 and 42 on the bottom side. It has. In the present embodiment, the containers 41 and 42 are constituted by cylindrical containers, and the bottoms are open. A container-like communication body 43 having a rectangular cross section is provided to close the bottom of the containers 41 and 42 and to allow the containers 41 and 42 to communicate with each other on the bottom side. The two containers 41 and 42 have substantially the same internal volume.
In the energy recovery chamber 21, two input / output ports (openings) 21a and 21b are formed at the upper end of the container. Concentrated seawater (high-concentration seawater) and seawater (through the input / output ports 21a and 21b) Raw seawater) is introduced into or led out from the chamber 21. The two cylindrical containers 41, 42 are immiscible so as not to be mixed with either concentrated seawater (high-concentration seawater) or seawater (raw seawater) so as to fill a volume approximately half below the containers 41, 42. Sex fluid NF is contained. Concentrated seawater (high-concentration seawater) is introduced into the upper part of one container, and seawater (raw seawater) is introduced into the upper part of the other container. In the embodiment shown in FIG. 8, the concentrated seawater (high concentration seawater) HW is introduced into the upper part of the container 42, and the seawater (raw seawater) LW is introduced into the upper part of the container 41. It has become.

  That is, in the energy recovery chamber 21, the concentrated seawater (high-concentration seawater) HW that is a high-pressure liquid and the seawater (raw seawater) LW that is a low-pressure liquid are separated by an immiscible fluid NF. . Then, the concentrated seawater HW, which is a high-pressure liquid discharged from the reverse osmosis membrane cartridge 8, and the seawater (raw seawater) supplied from the water supply line 4 are introduced into or extracted from the energy recovery chamber 21, whereby the pressure of the concentrated seawater HW is increased. Is transmitted to seawater (raw seawater) LW, which is a low-pressure liquid, so that the pressure of seawater (raw seawater) LW, which is a low-pressure liquid, is increased and energy is recovered to the seawater (raw seawater) LW side. ing. During this energy recovery operation, the concentrated seawater HW, which is a high-pressure liquid, and the low-pressure seawater LW are partitioned by the immiscible fluid NF at the bottom of each container and do not enter different container sides. That is, the liquid level of concentrated seawater rises and falls within the container 42, and the liquid level of seawater (raw seawater) only rises and falls within the container 41, and the concentrated seawater HW and seawater (raw seawater) LW are not. Always separated by a miscible fluid NF.

  The energy recovery chamber shown in FIG. 8 is obtained by replacing the circular communication pipe 33 of the energy recovery chamber shown in FIG. 4 with a container-like communication body 43 having a rectangular cross section. Thereby, the flow path area of the communication path which connects between the two containers 41 and 42 can be increased, and the pressure loss of a communication path can be decreased. The operation of the energy recovery chamber shown in FIG. 8 is the same as that of the energy recovery chamber shown in FIG.

FIG. 9 is a view showing an energy recovery chamber according to the fourth embodiment of the present invention. As shown in FIG. 9, the energy recovery chamber in this embodiment is obtained by adding a float to the energy recovery chamber shown in FIG. That is, the floats 35 are accommodated in the containers 31 and 32, respectively. The float 35 is located on the interface between the immiscible fluid NF and the concentrated seawater HW or seawater (raw seawater) LW in the containers 31 and 32.
10 and 11 are diagrams illustrating the operation of the positive displacement energy recovery apparatus including the energy recovery chamber using the float. As shown in FIGS. 10 and 11, the operation of the positive displacement energy recovery apparatus including the energy recovery chamber using the float is the same as the operation shown in FIGS. 5 and 6.

In the energy recovery chamber 21 of the present invention, the float 35 functions as a safety device that prevents an emergency situation in which the immiscible fluid NF leaks and flows out of the energy recovery chamber.
That is, the proximity sensor or the touch sensor 39 (see FIG. 9) detects that the float 35 approaches or contacts the inner end face of the energy recovery chamber 21, and is transmitted as an operation switching signal for a valve of the energy recovery apparatus. To do. Further, the proximity sensor or touch sensor 39 detects that the float 35 approaches or comes into contact with the inner end face of the energy recovery chamber 21, so that it is regarded as an abnormal operation and is used as a signal output for taking measures such as an emergency stop.
In addition, the float 35 reduces the effective contact area between the immiscible fluid NF and seawater, and thus suppresses mixing of seawater and immiscible liquid. In this case, as shown in FIG. 12, it is desirable that the float 35 in the containers 31 and 32 has a flat plate shape, and the front and back surfaces thereof are processed to be hydrophilic and hydrophobic, respectively. That is, if the float 35 is a flat plate having a large area, the effective contact area between the immiscible fluid NF and concentrated seawater or seawater (raw seawater) can be reduced.

Next, physical properties necessary for the immiscible fluid will be described.
It is essential that the physical properties required for immiscible fluids are not mixed with seawater. The incidental conditions are that the viscosity should be as small as possible, the specific gravity differs from seawater in the case of a device configuration that needs to maintain a stable positional relationship (vertical relationship) with seawater due to gravity, and from the viewpoint of ease of handling It is preferably non-toxic, volatile and flammable.
From the viewpoint of not mixing with seawater, examples of immiscible fluids include so-called oils, essential oils, liquid metals, ionic liquids, and nonpolar solvents. From the viewpoint of making the device substantially the same as a conventional piston-type energy recovery device, it is desirable to use a liquid with low compressibility as the immiscible fluid.

Next, oils that can be used as immiscible fluids are exemplified.
Any suitable oil from vegetable, animal and mineral oils may be used. Generally, many vegetable oils that are non-volatile and less problematic from the viewpoint of safety can be used as immiscible fluids. For example, rapeseed oil, sunflower oil, sesame oil and the like. As other oils, liquid paraffin, silicone oil and the like can be used. Paraffin (petroleum wax), which is solid at room temperature, liquefies at 47 to 60 ° C. and does not mix with water, so it can be used if it is heated and kept above its melting point. Essential oil, which is a substance similar to fats and oils contained in plants, can be used in that it does not mix with water, but because it is volatile, it is harder to apply as an immiscible fluid than ordinary oil.

Next, a liquid metal that can be used as an immiscible fluid will be described.
Liquid metal is advantageous in that its specific gravity is significantly different from seawater. A typical liquid metal is mercury, but it is unsuitable from the standpoint of toxicity, and it is essential to protect it from leakage and the slight dissolution in seawater during use. Gallium is preferable from the viewpoint of safety. Since gallium has a melting point of 29.76 ° C, a mechanism to keep gallium at a higher temperature is required.

Next, an ionic liquid that can be used as an immiscible fluid will be exemplified.
Ionic liquids that can be used as immiscible fluids include:
N, N, N-trimethyl-N-propylammonium bis (trifluoromethanesulfonyl) imide
N-methyl-N-propylpiperidinium bis (trifluoromethanesulfonyl) imide
1-Butyl-3-methylimidazolium hexafluorophosphate
1-hexyl-3-methylimidazolium hexafluorophosphate
1-hexyl-3-methylimidazolium tetrafluoroborate
1-hexyl-3-methylimidazolium trifluoromethanesulfonate
1-octyl-3-methylimidazolium hexafluorophosphate
1-butyl-2,3-dimethylimidazolium tetrafluoroborate
1-butyl-2,3-dimethylimidazolium trifluoromethanesulfonate
1-hexyl-2,3-dimethylimidazolium tetrafluoroborate
1-hexyl-2,3-dimethylimidazolium trifluoromethanesulfonate
1-butylpyridinium hexafluorophosphate
1-butylpyridinium tetrafluoroborate
1-hexylpyridinium hexafluorophosphate
1-hexylpyridinium tetrafluoroborate
1-hexylpyridinium trifluoromethanesulfonate
1-ethyl-3-methylimidazolebis (trifluoromethanesulfonyl) imide
2-Butyl-3-methylimidazolebis (trifluoromethanesulfonyl) imide

Next, a nonpolar solvent that can be used as an immiscible fluid will be described.
Water is a strongly polar substance and has the property of being difficult to mix with a non-polar substance, which is the opposite property. Among these, hexane, heptane, cyclohexane, limonene, toluene, benzene, xylene, etc. are known as non-polar solvents, which are known to be difficult to mix with water, but are difficult to use from the viewpoint of safety and volatility. However, it is indispensable to protect against leakage and small amounts of dissolution in seawater during use.

Next, a positive displacement energy recovery apparatus combined with a heater when gallium is used as the immiscible fluid will be described.
Gallium is a metal with a melting point of 29.76 ° C., and becomes a liquid at higher temperatures. When this is adopted as an immiscible liquid, a mechanism for heating and / or keeping gallium at 29.76 ° C. or higher is necessary. The gallium heating method includes a throw-in heater inside the energy recovery chamber, a heater installed outside the energy recovery chamber, a temperature-controlled room filled with air, a method of immersing the energy recovery chamber in a thermostatic bath, and a heat exchanger pipe Method of installing inside or outside the energy recovery chamber, microwave heating, induction heating, ultrasonic heating, Joule heat heating by applying current by installing electrodes inside the energy recovery chamber, high temperature steam from the boiler to the energy recovery chamber Any method such as spraying or direct heating of the energy recovery chamber by flame may be used.

  FIG. 13 is a diagram showing an example in which a throw-in heater is installed as a mechanism for heating and / or keeping gallium warm. In the example shown in FIG. 13, the heater 40 is an electrothermal heater. The energy recovery chamber 21 shown in FIG. 13 is the same as that shown in FIG. 4 and includes two cylindrical containers 31 and 32 and a communication pipe 33 that communicates the two cylindrical containers 31 and 32 on the lower side. And. The cable for the heater is drawn out from the hole 21h formed in the energy recovery chamber 21. The hole 21h has a watertight and insulating structure. Desirably, the gallium is kept at an appropriate temperature, or a thermometer is installed inside or outside the chamber. When the temperature of gallium is lowered, gallium is solidified and fixed to the inner wall of the chamber, so that the action can be used as a kind of valve. However, when the chamber is large, the heat capacity of gallium also increases, so that a steep operation like an emergency closing valve cannot be expected. Therefore, the present invention can be applied to work that does not need to be rushed to prevent mixing of two kinds of seawater during maintenance before and after operation. However, when it is necessary to solidify gallium urgently, it is possible to spray cold water or cold air to the energy recovery chamber, or urgently flow a low-temperature refrigerant to the heat exchanger for heating.

  Thus, by solidifying a liquid metal such as gallium, it is possible to prevent a flow from occurring even if a differential pressure occurs between the high-pressure liquid (concentrated seawater) and the low-pressure liquid (raw seawater) due to the solidified metal. Is possible.

  Such a heating / cooling method is applicable not only to gallium but also to metals and other substances that are solid at room temperature. An example of the substance is paraffin (melting point: 47 to 60 ° C.). However, since paraffin has extremely poor conductivity, a heating method based on electric conduction such as induction heating or Joule heating cannot be applied.

Next, an energy recovery chamber provided with a large number of horizontally placed thin tubes between two containers will be described. FIG. 14 is a plan view showing an energy recovery chamber in which a large number of horizontally placed thin tubes are provided between two containers. As shown in FIG. 14, the energy recovery chamber 21 includes two cylindrical containers 31 and 32 and a large number of thin tubes 53 that communicate the two cylindrical containers 31 and 32. In the present embodiment, the containers 31 and 32 are constituted by rectangular tube-shaped containers having a rectangular cross section, and the two containers 31 and 32 have substantially the same internal volume.
In the energy recovery chamber 21, two input / output ports (not shown) are formed at the upper end of the container, and concentrated seawater (high-concentration seawater) and seawater (raw seawater) are supplied through the input / output ports. It is introduced into or led out from the chamber 21. Concentrated seawater (high-concentration seawater) is introduced into one container, and seawater (raw seawater) is introduced into the other container. In the embodiment shown in FIG. 14, concentrated seawater (high-concentration seawater) is introduced into the container 32, and seawater (raw seawater) is introduced into the container 31. In addition, an immiscible fluid NF that is not mixed with either concentrated seawater (high-concentration seawater) or seawater (raw seawater) is placed in a large number of thin tubes 53 that communicate the two cylindrical containers 31 and 32. Yes. The immiscible fluid NF maintains a substantially spherical shape due to the surface tension in each thin tube 53 and separates the concentrated seawater HW and the seawater (raw seawater) LW in the thin tube 53.

  That is, in the narrow tube 53 of the energy recovery chamber 21, the concentrated seawater (high-concentration seawater) HW that is a high-pressure liquid and the seawater (raw seawater) LW that is a low-pressure liquid are separated by an immiscible fluid NF. is doing. Then, the concentrated seawater HW, which is a high-pressure liquid discharged from the reverse osmosis membrane cartridge 8, and the seawater (raw seawater) supplied from the water supply line 4 are introduced into or extracted from the energy recovery chamber 21, whereby the pressure of the concentrated seawater HW is increased. Is transmitted to seawater (raw seawater) LW, which is a low-pressure liquid, so that the pressure of seawater (raw seawater) LW, which is a low-pressure liquid, is increased and energy is recovered to the seawater (raw seawater) LW side. ing. During this energy recovery operation, the concentrated seawater HW, which is a high-pressure liquid, and the low-pressure seawater LW are partitioned by the immiscible fluid NF in the narrow tube 53 and do not enter different container sides. That is, the concentrated seawater flows in the narrow tube 53, and the seawater (raw seawater) only flows in the thin tube 53, and the concentrated seawater HW and the seawater (raw seawater) LW are immiscible fluids NF. Always separated. The immiscible fluid NF performs the same function as a piston in each thin tube 53 and pressurizes seawater (raw seawater).

Next, conditions (surface tension, etc.) for establishing an energy recovery chamber provided with a large number of horizontally placed thin tubes will be described.
When two or more immiscible fluids are put in a container or a tube, they are separated into upper and lower parts by a specific gravity difference in a quasi-static state. However, the fluid has an effect of reducing the surface area due to surface tension, and when the container or the tube is sufficiently small, it is possible to realize a situation in which other fluids such as a piston are separated by the plug-like fluid. Such a situation can be realized when the tube diameter is approximately 5 mm or less.

ここで、gは各物質間の表面張力、qは接触角と呼ばれ、それぞれ物性値である。ここでＦ_１が水とすると、q＞９０度の場合、固体は親水性と呼ばれ、q＜９０度の場合、固体は疎水性と呼ばれる。表面張力に比べ重力の効果が小さい場合、近似的にＦ_２の表面は円弧で近似できる。この時、図のａ，ｂは概略で以下のような関係式となる。

このａが概略で管径以上となるように流体Ｆ_２の量に関する値であるｂと接触角の関係を調整すれば、Ｆ_２が管のある断面を完全に満たすようになり、水（海水）を隔てることができる。 In general, when two kinds of immiscible liquids F ₁ and F ₂ is in contact with the solid surface S, the volume of F ₂ is sufficiently small as compared with the F _1, the liquid F _2, such as shown in FIG. 15 It becomes a shape. At this time, the following equation is established.

Here, g is the surface tension between the substances, and q is the contact angle, which is a physical property value. If F ₁ is water, the solid is called hydrophilic when q> 90 degrees, and the solid is called hydrophobic when q <90 degrees. When the effect of gravity is smaller than the surface tension, the surface of F ₂ can be approximated by an arc. At this time, a and b in the figure are roughly the following relational expressions.

If the relationship between the contact angle and b, which is a value related to the amount of the fluid F ₂ , is adjusted so that this a is approximately equal to or larger than the pipe diameter, the F ₂ will completely fill the cross section with the pipe, and water (seawater ) Can be separated.

  Further, the surface tension and the contact angle are physical values, but can be controlled to some extent by using a technique called electrowetting in which a voltage is applied. When this electrowetting is used, a tube having a tube diameter of 5 mm or more can be used without being limited to the above-described tube having a tube diameter of 5 mm or less, which is advantageous in apparatus design and operation.

16 (a) and 16 (b) are schematic schematic diagrams showing liquid level control using electrowetting, and FIG. 16 (a) is a diagram showing a state before liquid level control is performed. FIG. 16B is a diagram showing a state in which the liquid level control is performed. As shown in FIGS. 16A and 16B, the insulating layer 63 and the immiscible liquid NF and water are interposed between the opposing electrodes 61 and 62. A DC power supply 64 is provided between the counter electrodes 61 and 62.
If a predetermined voltage is applied between the counter electrodes 61 and 62 by controlling the DC power supply 64, the interface of the immiscible liquid NF can be controlled as shown in FIG. Thereby, the space between the electrodes 61 and 62 can be filled with the immiscible liquid NF. If this electrowetting is used, even if the tube diameter of the thin tube 53 shown in FIG. 14 is increased, the conduit in the thin tube 53 can be closed with the immiscible liquid NF.

Next, treatments or materials for making the inner surface of the apparatus hydrophilic or hydrophobic will be exemplified.
For example, metricyl group, carboxylic acid group, sulfonic acid group is introduced to the inner surface of the device, titanium oxide, zinc oxide, phosphate, etc. are applied, a hydrophilic resin material is applied, or a polymer material is applied. Then, it can be made hydrophilic by performing a plasma irradiation treatment. On the other hand, the surface can be made hydrophobic by applying an organic silicon compound or forming a water-repellent plasma polymerized film. In addition, any known hydrophilic surface treatment or hydrophobic surface treatment may be used. In addition to surface treatment, a hydrophilic or hydrophobic inner surface can be obtained by manufacturing an energy recovery chamber with a hydrophilic or hydrophobic (for example, glass) characteristic of the material itself.

FIG. 17A and FIG. 17B are schematic schematic views showing the difference in liquid surface shape between the case of hydrophilicity and the case of hydrophobicity.
The reason for making it hydrophilic or hydrophobic is to reduce the risk that the immiscible liquid mixes with the seawater side and flows out of the chamber. As shown in FIG. 17 (a), by making it hydrophobic, the immiscible liquid side tends to be a liquid film, and conversely, it may be considered as a droplet that adheres to the inner surface and does not easily remain on the seawater side. In addition, as shown in FIG. 17B, by making it hydrophilic, the immiscible liquid becomes droplets and adheres to the inner surface, but conversely moves from there by gravity, buoyancy, or other flow. In some cases, it becomes easier to return to the original liquid side. Hydrophobicity and water repellency are treated as synonyms. Therefore, the risk of mixing with seawater may be minimized by appropriately making the inner surface hydrophilic or hydrophobic based on the nature of the immiscible liquid.

FIG. 1 is a schematic diagram showing a configuration example of a seawater desalination plant (seawater desalination apparatus / system) to which the energy recovery apparatus of the present invention is applied. FIG. 2 is a schematic diagram showing another configuration example of the seawater desalination plant to which the energy recovery apparatus of the present invention is applied. FIG. 3 is a schematic diagram showing a positive displacement energy recovery apparatus of the present invention applied to the seawater desalination plant shown in FIGS. 1 and 2. FIG. 4 is a diagram showing an energy recovery chamber according to the first embodiment of the present invention. FIG. 5 is a diagram for explaining the operation of the positive displacement energy recovery apparatus configured as shown in FIGS. 3 and 4. FIG. 6 is a diagram for explaining the operation of the positive displacement energy recovery apparatus configured as shown in FIGS. 3 and 4. FIG. 7 is a view showing an energy recovery chamber according to the second embodiment of the present invention. 8A and 8B are views showing an energy recovery chamber according to the third embodiment of the present invention. FIG. 8A is a cross-sectional view, and FIG. 8B is a plan view. FIG. 9 is a view showing an energy recovery chamber according to the fourth embodiment of the present invention. FIG. 10 is a diagram for explaining the operation of the positive displacement energy recovery apparatus including an energy recovery chamber using a float. FIG. 11 is a diagram for explaining the operation of a positive displacement energy recovery apparatus including an energy recovery chamber using a float. FIG. 12 is a diagram illustrating an example in which the float in the container has a flat plate shape. FIG. 13 is a diagram showing an example in which a throw-in heater is installed as a mechanism for heating and / or keeping gallium warm. FIG. 14 is a plan view showing an energy recovery chamber in which a large number of horizontally placed thin tubes are provided between two containers. FIG. 15 is a diagram showing the shape of one liquid when two immiscible liquids are in contact with the solid surface and the volume of one liquid is sufficiently smaller than the volume of the other liquid. . FIG. 16A and FIG. 16B are schematic schematic diagrams showing liquid level control using electrowetting. FIG. 17A and FIG. 17B are schematic schematic views showing the difference in liquid surface shape between the case of hydrophilicity and the case of hydrophobicity. FIG. 18 is a schematic diagram showing a configuration example of a seawater desalination plant using the reverse osmosis membrane method. FIG. 19 is a schematic diagram illustrating a configuration example of a conventional positive displacement energy recovery apparatus. FIG. 20 is a schematic view showing a conventional configuration example of the energy recovery chamber.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Seawater 2 Intake pump 3 Pretreatment device 4 Water supply line 5 High pressure pump 6 Electric motor 7 High pressure line 8 Reverse osmosis membrane cartridge 9 High pressure chamber 10 Reverse osmosis membrane 12 Desalinated water 13 High pressure rejection 14 Turbine 17 Booster pump 18 Energy recovery pump turbine 19 Booster pump discharge line 20 Directional switching valve 21 Energy recovery chambers 21a, 21b Input / output ports (openings)
21h Hole 22 Check valve module 23 Positive displacement energy recovery device 24 Supply seawater bypass boost line 25 Discharge line 26 Electric motor 27 Turbine discharge line 28 Turbine inlet line 31 Cylinders 31a and 31b Input / output ports 31 and 32 Container 33 Communication pipe 35 Float 40 Heater 41, 42 Container 43 Communication body 53 Thin tube 61, 62 Counter electrode 63 Insulating film 64 DC power supply 302 Spool NF Immiscible fluid (immiscible liquid)
HW concentrated seawater (high concentration seawater)
LW seawater (raw seawater)
P Supply port A Control port R Return port

Claims (8)

In a volumetric energy recovery device that recovers energy to the low-pressure liquid side by increasing the pressure of the low-pressure liquid by transmitting the pressure of the flowing high-pressure liquid to the flowing low-pressure liquid,
Providing an energy recovery chamber for introducing the high-pressure liquid and the low-pressure liquid;
An immiscible fluid that does not mix with either the high-pressure liquid or the low-pressure liquid is placed in the energy recovery chamber, and the high-pressure liquid and the low-pressure liquid are separated by the immiscible fluid. A positive displacement energy recovery device.   The positive displacement energy recovery apparatus according to claim 1, wherein the immiscible fluid is made of an ionic liquid.   The positive displacement energy recovery apparatus according to claim 1, wherein the immiscible fluid is made of oil.   The positive displacement energy recovery apparatus according to claim 1, wherein the immiscible fluid comprises a nonpolar solvent.   The positive displacement energy recovery apparatus according to claim 1, wherein the immiscible fluid is made of a liquid metal. The energy recovery chamber includes two containers, and a communication portion that communicates the two containers at the bottom or bottom of the two containers,
The immiscible fluid has a specific gravity greater than any of the high-pressure liquid and the low-pressure liquid, is present in the lower part of the two containers, and also fills the communication part,
The high-pressure liquid exists in the upper part of one of the two containers, the low-pressure liquid exists in the upper part of the other container, and during the energy recovery operation, the high-pressure liquid and the low-pressure liquid are 6. Volumetric energy recovery according to any one of claims 1 to 5, characterized in that the lower part of the container is separated by the immiscible fluid so that it does not enter different container sides. apparatus. The energy recovery chamber includes two containers and a communication portion that communicates the two containers at the upper part of the two containers.
The immiscible fluid has a specific gravity smaller than any of the high-pressure liquid and the low-pressure liquid, is present at the upper part of the two containers, and also fills the communication part,
The high-pressure liquid exists in the lower part of one of the two containers, the low-pressure liquid exists in the lower part of the other container, and during the energy recovery operation, the high-pressure liquid and the low-pressure liquid are respectively 6. Volumetric energy recovery according to any one of the preceding claims, characterized in that the upper part of the container is separated by the immiscible fluid and does not enter different container sides. apparatus. A high-pressure pump that pressurizes the supplied seawater;
A reverse osmosis membrane cartridge for producing demineralized water by membrane treatment of the high-pressure seawater discharged from the high-pressure pump with a reverse osmosis membrane;
A volumetric energy recovery device that pressurizes supplied seawater using the pressure of concentrated water discharged from the reverse osmosis membrane cartridge without being treated with the reverse osmosis membrane;
A seawater desalination apparatus comprising a pressurization device that pressurizes pressurized seawater pressurized by the positive displacement energy recovery device and joins the high pressure seawater discharged from the high pressure pump;
The said volume type energy recovery apparatus is the volume type energy recovery apparatus as described in any one of Claims 1 thru | or 7. The seawater desalination apparatus characterized by the above-mentioned.

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