JP6836574B2 - Energy recovery device - Google Patents

Description

The present invention relates to an energy recovery device for a water treatment system by a reverse osmosis membrane method used for desalination of seawater and the like.

The reverse osmosis method is known as one of the methods for producing fresh water from seawater. In this reverse osmosis method, a pressure higher than the osmotic pressure of seawater is applied to seawater in the direction opposite to the direction in which the osmotic pressure acts, and filtration is performed with a semipermeable membrane (reverse osmosis membrane: RO membrane) to separate salts and freshwater. Is what you do. In this reverse osmosis method, seawater in which freshwater is separated and salts are concentrated (concentrated seawater) flows out from the reverse osmosis membrane module while maintaining high pressure energy. In order to effectively utilize the high pressure energy of the outflowing concentrated seawater, various energy recovery devices have been put into practical use.

Conventionally, for example, Patent Document 1 has proposed an example of an energy recovery device in a seawater desalination system by a reverse osmosis method. In Patent Document 1, one end of each of the pair of cylinder devices is communicated with the water supply pump and the pressure boosting pump via a flow path direction regulating device composed of two check valves. Further, the other end of the cylinder device is communicated with the inflow / outflow port of the flow path switching device. Further, the inflow port of the flow path switching device is communicated with the outlet of the high-pressure concentrated seawater of the reverse osmosis membrane module. Further, an outflow port is provided at one end of the flow path switching device.

In this energy recovery device, the seawater sent from the water supply pump is pressurized by the high-pressure pump and supplied to the reverse osmosis membrane module, and the high-pressure concentrated seawater discharged from the reverse osmosis membrane module is supplied to the cylinder device at high pressure. It drives a piston that pushes out seawater, and also sends high-pressure seawater from the cylinder device to the reverse osmosis membrane module via a booster pump. The operation of supplying the high-pressure concentrated seawater discharged from the reverse osmosis membrane module to the cylinder device and driving the piston that pushes out the seawater at high pressure is called a pumping process.
In addition, after the pumping process is completed, seawater is supplied from the water supply pump to the cylinder device via the flow path direction regulating device, and the piston is driven in the opposite direction to the pumping process to discharge concentrated seawater and fill it with seawater. It is called the filling process.
In this way, in this energy recovery device, when the piston of the cylinder device reaches the end of the cylinder, the high-pressure concentrated seawater from the back-penetrating membrane module is alternately supplied to the pair of cylinder devices by the flow path switching device, and the water supply pump. Control is performed so that the pair of cylinder devices are alternately filled with seawater.

As a result, continuous filtration is possible by repeatedly performing the seawater pumping step and the filling step with the two cylinder devices. In this way, the energy consumption of the high-pressure pump is reduced by supplying high-pressure seawater from the two cylinder devices to the reverse osmosis module via the booster pump using the high-pressure energy of the concentrated seawater discharged from the reverse osmosis membrane module. It will be reduced.

Japanese Unexamined Patent Publication No. 2013-86043

In the above-mentioned conventional technique, the following problems remain.
That is, in the above-mentioned conventional technique, high-pressure seawater is sent to the membrane separation device by a high-pressure pump that directly pressurizes the seawater sent from the water supply pump and a pressure-increasing pump that boosts the seawater sent from the cylinder device. There is a disadvantage that the equipment becomes complicated and the equipment cost increases because two systems of boosting paths using two pumps of the above are required.

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide an energy recovery device that requires only one pressurizing pump and can simplify the equipment.

The present invention has adopted the following configuration in order to solve the above problems. That is, the energy recovery device according to the first invention separates high-pressure seawater into fresh water and concentrated seawater with a back-penetrating membrane, discharges the fresh water into a freshwater pipe, and discharges the high-pressure concentrated seawater into a concentrated water pipe. An energy recovery device connected to the device, the water supply pump that supplies seawater, the high-pressure pump that pressurizes the seawater and supplies the high-pressure seawater to the membrane separation device, and one end communicating with the water supply pump. A plurality of ends connected to the concentrated water pipe and the drainage channel via a flow path switching mechanism that communicates with and shuts off the concentrated water pipe and also communicates with and shuts off the drainage channel of the concentrated seawater. Cylinder device and the seawater connected to one end of the plurality of cylinder devices to alternately supply the seawater to the plurality of cylinder devices and alternately extruding the seawater from the plurality of cylinder devices at high pressure to the film separation device. By controlling the flow path direction regulating mechanism and the flow path switching mechanism to switch the connection of the plurality of cylinder devices to the concentrated water pipe and the drainage channel, the high-pressure concentrated seawater is supplied to the cylinder device and inside. A control function performed by a pumping step of pushing out the seawater at a high pressure and a filling step of supplying the seawater from the water supply pump to the cylinder device after the pumping step and filling the seawater while discharging the concentrated seawater inside. The cylinder device is provided with a control unit having a control unit, the other end of which is connected to the concentrated water pipe and the drainage channel, and the primary side cylinder into which the concentrated seawater is introduced and a primary side cylinder that reciprocates within the primary side cylinder. It is penetrated through a side piston, a secondary cylinder whose one end communicates with the water supply pump and the seawater is introduced, a secondary piston that reciprocates in the secondary cylinder, and one end of the primary cylinder. Along with this, a connecting shaft portion that is penetrated through the other end of the secondary cylinder and connects the primary piston and the secondary piston is provided, and the inner diameter of the primary cylinder and the secondary cylinder are provided. It is characterized in that it is different from the inner diameter of.

In this energy recovery device, the cylinder device is penetrated through one end of the primary side cylinder, the primary side piston, the secondary side cylinder, the secondary side piston, and the primary side cylinder, and other than the secondary side cylinder. It is provided with a connecting shaft portion that is penetrated through the end and connects the primary side cylinder and the secondary side piston, and since the inner diameter of the primary side cylinder and the inner diameter of the secondary side cylinder are different, the primary side cylinder and the secondary side cylinder It is possible to set the seawater discharged from the cylinder device to a desired pressure and flow rate according to the ratio of the inner diameter to the next cylinder.
That is, since the input / output ratio of seawater pressure and flow rate in the cylinder device is proportional to the cylinder cross-sectional area ratio according to Pascal's principle, only the flow rate and pressure on the primary side need to be controlled, and the control system Easy to build. In addition, the pressure energy recovered from the concentrated seawater that has entered the primary cylinder is transmitted to the seawater that has entered the secondary cylinder in advance via the connecting shaft, and is supplied to the suction side of the high-pressure pump, so that only the pressing pressure is applied. It is possible to increase the discharge pressure of the high-pressure pump.
In this way, seawater is pushed out from the cylinder device at the pressure and flow rate set by the primary side cylinder and the secondary side cylinder and supplied to the high-pressure pump side, so that the pressure of the seawater is further added to the membrane separation device. By boosting the pressure of seawater from the water supply pump and supplying it to the high-pressure pump, the pressure booster pump that compensates for the head loss of each part such as the semitransparent membrane (reverse permeable membrane: RO membrane) and each pipe is no longer necessary. Become. That is, the pressure generated from the secondary cylinder becomes the pushing pressure of the high-pressure pump, and the total head of the high-pressure pump can be lowered by the pushing pressure. Since the head loss of each part such as the RO membrane and each pipe may be added to the head of the high-pressure pump, the booster pump becomes unnecessary.
Further, since the cylinder device has a structure in which the primary side piston and the secondary side piston are connected by the connecting shaft portion, the fluid energy on the primary side is transmitted directly to the secondary side via the piston and the connecting shaft portion. Higher efficiency.
In addition, since the flow rate and pressure ratio associated with energy transfer are always constant, the control of the entire system including this device only needs to be targeted at the flow rate and pressure on the primary side, which facilitates control.
Further, since the fluids on the primary side and the secondary side of the cylinder are completely separated by each cylinder or the like, mixing that causes an increase in salt concentration does not occur.

In the first invention, the energy recovery device according to the second invention leaks to one end of the primary cylinder and between the primary piston and one end of the primary cylinder in the primary cylinder. A primary side drain hole capable of discharging the concentrated seawater to the outside is formed, and at the other end of the secondary cylinder, the secondary piston and the other end of the secondary cylinder in the secondary cylinder are formed. It is characterized in that a secondary drain hole is formed so that the seawater leaked from the portion can be discharged to the outside.
That is, in this energy recovery device, at one end of the primary cylinder, a primary drain hole capable of discharging concentrated seawater leaked between the primary piston and one end of the primary cylinder in the primary cylinder to the outside. Is formed, not only the air but also the concentrated seawater leaked beyond the primary side piston is pushed out from the primary side drain hole by the primary side piston that reciprocates and does not mix with the secondary side seawater.
Further, at the other end of the secondary cylinder, a secondary drain hole capable of discharging seawater leaked between the secondary piston and the other end of the secondary cylinder in the secondary cylinder to the outside. Is formed, not only the air but also the seawater leaked over the secondary piston is pushed out from the secondary drain hole by the secondary piston that reciprocates and does not mix with the concentrated seawater on the primary side.

In the energy recovery device according to the third invention, in the first or second invention, the ratio of the inner diameter of the primary cylinder to the inner diameter of the secondary cylinder is set to be the same for all of the plurality of cylinder devices. It is characterized by being.
That is, in this energy recovery device, the ratio of the inner diameter of the primary cylinder to the inner diameter of the secondary cylinder is set to be the same for all of the plurality of cylinder devices, so that the pressure and flow rate of seawater extruded by each cylinder device can be increased. It becomes constant and can supply pressurized seawater in a well-balanced manner.

In the energy recovery device according to the fourth invention, in any one of the first to third inventions, the inner diameter of the primary cylinder is set smaller than the inner diameter of the secondary cylinder, and the flow path direction regulating mechanism is set. However, the seawater extruded from the cylinder device is supplied to the suction side of the high-pressure pump.
That is, in this energy recovery device, the inner diameter of the primary cylinder is set smaller than the inner diameter of the secondary cylinder, and the flow path direction regulating mechanism supplies the seawater extruded from the cylinder device to the suction side of the high-pressure pump. Therefore, the pressure generated from the secondary cylinder becomes the pushing pressure of the high-pressure pump, and the total head of the high-pressure pump can be lowered by the pushing pressure.

The energy recovery device according to the fifth invention includes, in any one of the first to third inventions, a water pipe that sends the seawater from the water supply pump to the high-pressure pump, and the inner diameter of the primary cylinder is the said. Set larger than the inner diameter of the secondary cylinder,
The flow path direction regulating mechanism is characterized in that the seawater extruded from the cylinder device is supplied to the discharge side of the high-pressure pump.
That is, this energy recovery device is provided with a water supply pipe that sends seawater from the water supply pump to the high-pressure pump, the inner diameter of the primary side cylinder is set to be larger than the inner diameter of the secondary side cylinder, and the flow path direction regulating mechanism is a cylinder. Since the seawater extruded from the device is supplied to the discharge side of the high-pressure pump, the pressure of the deleted booster pump can be increased and merged with the seawater sent out from the high-pressure pump. That is, the pressure of the seawater sent out from the cylinder device increases according to the inner diameter ratio between the primary side cylinder and the secondary side cylinder, and becomes equal to the pressure of the seawater sent out from the high pressure pump, so that the seawater can be sent to the membrane separation device. .. Further, the flow rate of seawater sent to the membrane separation device is the sum of the flow rate of seawater sent from the water supply pipe to the high-pressure pump and the flow rate of seawater sent from the cylinder device, and the required flow rate can be secured.

According to the present invention, the following effects are obtained.
That is, according to the energy recovery device according to the present invention, the cylinder device is penetrated through the primary side cylinder, the primary side piston, the secondary side cylinder, the secondary side piston, and one end of the primary side cylinder. Since it is provided with a connecting shaft portion that is penetrated through the other end of the secondary cylinder and connects the primary piston and the secondary piston, the inner diameter of the primary cylinder and the inner diameter of the secondary cylinder are different. , It becomes possible to set the pressure and the flow rate of the seawater sent out from the cylinder device according to the ratio of the inner diameters of the primary side cylinder and the secondary side cylinder.
Therefore, in the energy recovery device of the present invention, seawater can be sent to the membrane separation device at a high pressure and a sufficient flow rate only by a high-pressure pump, which eliminates the need for a pressure boosting pump, which has been required in the past, and simplifies the equipment. This makes it possible to reduce equipment costs.

It is a schematic diagram which shows the 1st Embodiment of the energy recovery device which concerns on this invention. It is a schematic diagram of the main part which shows the 2nd Embodiment of the energy recovery device which concerns on this invention. It is a schematic diagram which shows the 3rd Embodiment of the energy recovery device which concerns on this invention.

Hereinafter, the first embodiment of the energy recovery device in the present invention will be described with reference to FIG.

As shown in FIG. 1, the energy recovery device 1 in the present embodiment separates high-pressure seawater into freshwater and concentrated seawater with a reverse osmosis membrane, discharges the freshwater to the freshwater pipe 3, and discharges the high-pressure concentrated seawater to the concentrated water pipe 4. It is an energy recovery device connected to the membrane separation device 5 for discharging.

The energy recovery device 1 includes a water supply pump P1 that supplies seawater, a high-pressure pump P2 that pressurizes seawater and supplies high-pressure seawater to the membrane separation device 5, and a concentrated water pipe 4 having one end communicating with the water supply pump P1. A plurality of cylinders whose other ends are connected to the concentrated water pipe 4 and the drainage channel 19 via flow path switching mechanisms 6A and 6B that communicate and shut off the concentrated seawater and communicate with and shut off the drainage channel 19 of concentrated seawater. Seawater connected to devices 7A and 7B and one end of a plurality of cylinder devices 7A and 7B to alternately supply seawater to the plurality of cylinder devices 7A and 7B and alternately extruded from the plurality of cylinder devices 7A and 7B at high pressure. By controlling the flow path direction regulating mechanism 11 and the flow path switching mechanisms 6A and 6B to switch the connection of the plurality of cylinder devices 7A and 7B to the concentrated water pipe 4 and the drainage channel 19, high-pressure concentrated seawater Is supplied to the cylinder devices 7A and 7B to push out the seawater inside at high pressure, and after the pumping process, the seawater from the water supply pump P1 is supplied to the cylinder devices 7A and 7B to discharge the concentrated seawater inside while discharging the seawater. It includes a filling step for filling and a control unit C having a control function for performing the filling.

The cylinder devices 7A and 7B include a primary cylinder 8A in which the other end is connected to the concentrated water pipe 4 and the drainage channel 19 to introduce concentrated seawater, a primary piston 9A that reciprocates in the primary cylinder 8A, and one end. Is penetrated through one end of the secondary cylinder 8B, the secondary cylinder 8B that communicates with the water supply pump P1 and introduces seawater, the secondary piston 9B that reciprocates in the secondary cylinder 8B, and the primary cylinder 8A. A connecting shaft portion 12 which is penetrated through the other end of the secondary cylinder 8B and connects the primary piston 9A and the secondary piston 9B is provided.
That is, the primary side piston 9A and the secondary side piston 9B connected by the connecting shaft portion 12 move in the same direction together with the connecting shaft portion 12.

The inner diameter of the primary cylinder 8A and the inner diameter of the secondary cylinder 8B are different, and in the present embodiment, the inner diameter of the primary cylinder 8A is set to be smaller than the inner diameter of the secondary cylinder 8B.
Further, the ratio of the inner diameter of the primary cylinder 8A to the inner diameter of the secondary cylinder 8B is set to be the same for all of the plurality of cylinder devices 7A and 7B.

Further, the flow path direction regulating mechanism 11 is set to supply the seawater extruded from the cylinder devices 7A and 7B to the suction side of the high pressure pump P2. That is, the flow path direction regulating mechanism 11 is set to send the seawater extruded from the cylinder devices 7A and 7B to the connecting pipe 11e connected to the suction side of the high pressure pump P2.
The connecting shaft portion 12 may be housed in a connecting cylinder member that coaxially connects the primary side cylinder 8A and the secondary side cylinder 8B.

At one end of the primary cylinder 8A, a primary drain hole 8a capable of discharging concentrated seawater leaked between the primary piston 9A and one end of the primary cylinder 8A in the primary cylinder 8A is formed. Has been done.
Further, at the other end of the secondary cylinder 8B, seawater leaking between the secondary piston 9B and the other end of the secondary cylinder 8B in the secondary cylinder 8B can be discharged to the outside. The secondary drain hole 8b is formed.
A piston seal (not shown) for preventing leakage is provided on the outer peripheral surfaces of the primary side piston 9A and the secondary side piston 9B.

One end of the cylinder devices 7A and 7B is drained from the concentrated water pipe 4 via a first flow path switching mechanism 6A that communicates with and shuts off the concentrated water pipe 4 and communicates with and shuts off the drain pipe 19 of the concentrated seawater. One end is concentrated via a second flow path switching mechanism 6B that communicates with and shuts off the first cylinder device 7A connected to the pipe 19 and the concentrated water pipe 4 and also communicates with and shuts off the drain pipe 19. A second cylinder device 7B connected to the water pipe 4 and the drain pipe 19 is provided.

That is, the control unit C controls the first flow path switching mechanism 6A and the second flow path switching mechanism 6B to switch the connection between the first cylinder device 7A and the second cylinder device 7B to the concentrated water pipe 4 and the drain pipe 19. It has a control function for alternately pouring high-pressure concentrated seawater into the first cylinder device 7A and the second cylinder device 7B, and a control function for alternately discharging concentrated seawater from the first cylinder device 7A and the second cylinder device 7B. ing.

Further, a water supply pump P1 is connected to the seawater supply pipe 2a, and seawater is sent from the supply pipe 2a to the flow path direction regulating mechanism 11 by the water supply pump P1.
The flow path direction regulating mechanism 11 alternately supplies seawater to the first cylinder device 7A and the second cylinder device 7B, and alternately pushes seawater from the first cylinder device 7A and the second cylinder device 7B at high pressure. Is set to return to the membrane separation device 5 via the connecting tube 11e.

The concentrated water pipe 4 is branched in the middle and is connected to the first flow path switching mechanism 6A and the second flow path switching mechanism 6B.
The first flow path switching mechanism 6A and the second flow path switching mechanism 6B supply concentrated seawater to the first cylinder device 7A or the second cylinder device 7B and stop the supply thereof, and the first cylinder device 7A or the second cylinder device 7B. It is provided with a switching cylinder device 13 for switching between discharging concentrated seawater from the water and stopping the concentrated seawater, and a driving device 14 for driving the switching cylinder device 13.

The switching cylinder device 13 reciprocates within the switching cylinder 20 and the switching cylinder 20 connected to one end of the first cylinder device 7A or the second cylinder device 7B, the drain pipe 19, and the concentrated water pipe 4. The drain side piston 20a capable of communicating and shutting off one end of the 1-cylinder device 7A or the second cylinder device 7B and the drain pipe 19 and the concentrated water pipe 4 and the drain side piston 20a integrally reciprocate in the switching cylinder 20. A supply-side piston 20b and a drain-side piston 20a are provided at one end, and a supply-side piston 20b is provided at an intermediate portion, and the other end projects outward from the other end of the switching cylinder 20 and is connected to the drive device 14. It is provided with a switching piston rod 22.

The switching cylinder 20 includes an outflow port 13a connected to the drainage pipe 19 of concentrated seawater and provided on one end side, an inflow port 13b connected to the concentrated water pipe 4 and provided in the intermediate portion, and a first cylinder device 7A or. It has an inflow / outflow port 13c connected to the second cylinder device 7B and provided between the outflow port 13a and the inflow port 13b.

The control unit C is provided at a plurality of locations including, for example, near the other end of the primary cylinder 8A of each cylinder device 7A, 7B, and reaches the position of the primary piston 9A, particularly near the other end of the primary cylinder 8A. It is provided with a position detector (not shown) for detection, and has a function of controlling the first flow path switching mechanism 6A and the second flow path switching mechanism 6B based on the detection signals of these position detectors.
The position detectors may be installed at at least one of a plurality of locations other than the above on the primary side cylinder 8A and the secondary side cylinder 8B.

The first flow path switching mechanism 6A and the second flow path switching mechanism 6B include the driving device 14 for driving the switching cylinder device 13.
The drive device 14 is configured by using, for example, a hydraulic piston connected to a hydraulic pump, an electric actuator, or the like.
The control unit C has a function of controlling a hydraulic servo valve or a servo motor (not shown) to operate the drive device 14 based on the detection signal.

The other ends of the first cylinder device 7A and the second cylinder device 7B are communicated with the water supply pump P1 via a flow path direction regulating mechanism 11 composed of a pair of check valves 11.
One end of the first cylinder device 7A is communicated with the inflow / outflow port 13c of the switching cylinder device 13 in the first flow path switching mechanism 6A, and one end of the second cylinder device 7B is for switching in the second flow path switching mechanism 6B. It is communicated with the inflow / outflow port 13c of the cylinder device 13.

Further, the inflow port 13b of the switching cylinder device 13 is communicated with the concentrated water pipe 4. Further, an outflow port 13a connected to the drain pipe 19 is provided at one end of the switching cylinder device 13. The drain side piston 20a and the supply side piston 20b arranged in the switching cylinder 20 are connected to the switching piston rod 22. Further, one end of the switching piston rod 22 is connected to the driving device 14 and reciprocates in the switching cylinder 20 in conjunction with the driving device 14.

The flow path direction regulating mechanism 11 has a pair of branch pipes 11c connected to the supply pipe 2a, and the other ends of the first cylinder device 7A and the second cylinder device 7B corresponding to these branch pipes 11c are connected by a cylinder. It is connected via a tube 11d. In the branch pipe 11c, a pair of check valves 11 are provided on both sides of the connecting portion of the cylinder connecting pipe 11d. Further, the other end of the pair of branch pipes 11c is connected to the connecting pipe 11e.

Next, the operation of the energy recovery device 1 of the present embodiment will be described with reference to the drawings.
First, as shown in FIG. 1, when the primary side piston 9A of the first cylinder device 7A in the pumping process moves in the direction of arrow Y1, the secondary side piston 9B connected by the connecting shaft portion 12 also moves in the same direction. By doing so, the seawater in the secondary cylinder 8B is pushed out to the branch pipe 11d side. The seawater extruded into the branch pipe 11d is supplied to the high-pressure pump P2 via the connecting pipe 11e.
On the other hand, when the secondary piston 9B of the second cylinder device 7B in the filling step moves in the direction of the arrow Y2 of the primary piston 9A, the primary piston 9A connected by the connecting shaft portion 12 also moves in the same direction. Then, the concentrated seawater in the primary cylinder 8A is discharged to the drain pipe 19 via the inflow / outflow port 13c.

When the primary side piston 9A reaches the position of the predetermined position detector, a detection signal is transmitted from the position detector to the control unit C, and when the control unit C receives this detection signal, the control unit C sends the second flow path. The drive device 14 of the switching mechanism 6B is controlled to switch the flow path.
At this time, the inflow port 13b and the outflow / inflow port 13c of the switching cylinder device 13 in the second flow path switching mechanism 6B are communicated with each other, and high-pressure concentrated seawater is supplied from the membrane separation device 5 to the second cylinder device 7B. The communication between the outflow / inflow port 13c and the outflow port 13a is cut off, and the pumping process of the second cylinder device 7B is started.
In this way, the flow path is switched, and the pumping step and the filling step are alternately repeated in the first cylinder device 7A and the second cylinder device 7B.

In the present embodiment, the flow rate of seawater sent to the high-pressure pump P2 by the primary side cylinder 8A and the secondary side cylinder 8B having different inner diameters is determined.
Q1: Flow rate sent from the primary cylinder Q2: Flow rate sent from the secondary cylinder A1: Cross-sectional area in the primary cylinder A2: Cross-sectional area in the secondary cylinder, the flow rate and area are calculated by the following relational expression. Relationship is determined.
Flow rate ratio: Area ratio = Q2 / Q1: A2 / A1

For example, a case where the ratio of the cross-sectional area A1 in the primary cylinder 8A to the cross-sectional area A2 in the secondary cylinder 8B is A1: A2 = 1: 2 will be described below.
In this case, in the first cylinder device 7A in the pressure feeding process, assuming that the flow rate of concentrated seawater in the primary cylinder 8A is 5,000 m ³ / d and the pressure is 4.0 MPa, the flow rate of seawater in the secondary cylinder 8B is 10. The pressure is 2.0 MPa at 000 m ^{3 / d.}

At this time, the high pressure pump P2, the pressure in the flow from the first cylinder device 7A is 10,000 m ³ / d is sent seawater 2.0 MPa, flow rate membrane separation device 5 is at 10,000 m ³ / d If it is desired to send seawater having a pressure of 4.0 MPa, the pressure may be increased by 2.0 MPa with the high-pressure pump P2. Therefore, in the conventional technique, high-pressure seawater is sent to the membrane separation device by a high-pressure pump that directly pressurizes the seawater sent from the water supply pump and a pressure-increasing pump that boosts the seawater sent from the cylinder device, and is a pump for pressurization. Two systems of pressure boosting paths using two systems were required. In this embodiment, all the seawater sent from the cylinder device is sent to the suction side of the high-pressure pump, and the head loss of each part such as the RO membrane and each pipe supplemented by the pressure-increasing pump is expected to be the total head of the high-pressure pump, so the pressure is increased. No need for a pump.

Further, in the membrane separation device 5, concentrated seawater flow rate 5,000 m ³ / d, with fed at a pressure 4.0MPa to the first cylinder device 7 A, freshwater freshwater (permeate) flow rate 5,000 m ³ / d It is sent to the pipe 3.
At this time, in the second cylinder device 7B, which is the filling step, the flow rate of seawater in the secondary cylinder 8B is 10,000 m ³ / d, and the discharge amount of concentrated seawater in the primary cylinder 8A is 5,000 m ³ It becomes / d.

As described above, in the energy recovery device 1 of the present embodiment, the cylinder devices 7A and 7B have the primary side cylinder 8A, the primary side piston 9A, the secondary side cylinder 8B, the secondary side piston 9B, and the primary side cylinder. It penetrates through one end of 8A and penetrates through the other end of the secondary cylinder 8B to connect the primary piston 9A and the secondary piston 9B and move together with the primary piston 9A and the secondary piston 9B. Since the connecting shaft portion 12 is provided and the inner diameter of the primary cylinder 8A and the inner diameter of the secondary cylinder 8B are different, the cylinder device 7A is provided according to the ratio of the inner diameters of the primary cylinder 8A and the secondary cylinder 8B. , It becomes possible to set the pressure and flow rate of the seawater sent out from 7B.

That is, as described above, since the input / output ratio of the seawater pressure and the flow rate at 7A and 7B in the cylinder device is proportional to the cylinder cross-sectional area ratio, only the flow rate and the pressure on the primary side need to be controlled. The control system can be easily constructed. Further, the pressure energy recovered from the concentrated seawater contained in the primary cylinder 8A is transmitted to the seawater previously contained in the secondary cylinder 8B via the connecting shaft portion 12 and supplied to the suction side of the high pressure pump P2 for pushing. It is possible to increase the discharge pressure of the high-pressure pump by the amount of pressure.
In this way, seawater is pushed out from the cylinder devices 7A and 7B at the pressure and flow rate set by the primary side cylinder 8A and the secondary side cylinder 8B and supplied to the high pressure pump P2 side to further add seawater pressure. Then, the conventional pressure boosting pump that can supply the membrane separation device 5 and compensates for the head loss of each part such as the RO membrane and each pipe by boosting the seawater from the water supply pump P1 and supplying it to the high pressure pump P2. It becomes unnecessary. That is, the pressure generated from the secondary cylinder 8B becomes the pushing pressure of the high-pressure pump P2, and the total head of the high-pressure pump P2 can be lowered by the pushing pressure. Since the head loss of each part such as the RO membrane and each pipe may be added to the head of the high-pressure pump P2, the booster pump becomes unnecessary.

In particular, the inner diameter of the primary cylinder 8A is set smaller than the inner diameter of the secondary cylinder 8B, and the flow path direction regulating mechanism 11 supplies the seawater extruded from the cylinder devices 7A and 7B to the suction side of the high pressure pump P2. Therefore, the pressure generated from the secondary cylinder 8B becomes the pushing pressure of the high-pressure pump P2, and the total lift of the high-pressure pump P2 can be lowered by the pushing pressure.

Further, since the cylinder devices 7A and 7B have a structure in which the primary side piston 9A and the secondary side piston 9B are connected by the connecting shaft portion 12, the fluid energy on the primary side is transferred to the secondary side via the piston and the connecting shaft portion. By communicating directly, the transmission efficiency is high.
Further, since the ratio of the inner diameter of the primary cylinder 8A to the inner diameter of the secondary cylinder 8B is set to be the same in all of the plurality of cylinder devices 7A and 7B, the pressure of seawater pushed out by each of the cylinder devices 7A and 7B and The flow rate becomes constant, and it is possible to supply well-balanced pressurized seawater.

In addition, since the flow rate and pressure ratio associated with energy transfer are always constant, the control of the entire system including this device only needs to be targeted at the flow rate and pressure on the primary side, which facilitates control.
Further, since the fluids on the primary side and the secondary side of the cylinders are completely separated by the piston seals of both cylinders and each cylinder, mixing that causes an increase in salt concentration does not occur.

Further, at one end of the primary cylinder 8A, a primary drain hole 8a capable of discharging concentrated seawater leaked between the primary piston 9A and one end of the primary cylinder 8A in the primary cylinder 8A to the outside is provided. Since it is formed, not only the air but also the concentrated seawater leaked beyond the primary side piston 9A is pushed out from the primary side drain hole 8a by the primary side piston 9A that reciprocates and does not mix with the secondary side seawater.

Further, seawater leaking between the secondary piston 9B and the other end of the secondary cylinder 8B in the secondary cylinder 8B can be discharged to the outside at the other end of the secondary cylinder 8B. Since the secondary drain hole 8b is formed, not only the air but also the seawater leaked beyond the secondary piston 9B is reciprocated by the secondary piston 9B, which is pushed out from the secondary drain hole 8b to the primary side. Does not mix with concentrated seawater.

Next, the second and third embodiments of the energy recovery device in the present invention will be described with reference to FIGS. 2 and 3. In the following description of each embodiment, the same components described in the above embodiment are designated by the same reference numerals, and the description thereof will be omitted.

The difference between the second embodiment and the first embodiment is that the first embodiment includes two cylinder devices 7A and 7B, whereas the energy recovery device 21 of the second embodiment shows FIG. As shown, it is provided with three cylinder devices 7A, 7B and 7C.
That is, in the second embodiment, the cylinder device is composed of the first cylinder device 7A, the second cylinder device 7B, and the third cylinder device 9C.

In the second embodiment, the branch pipe 11c branches into three corresponding to the three cylinder devices, and is connected to the first cylinder device 7A, the second cylinder device 7B, and the third cylinder device 7C via the check valve 11, respectively. It is connected.
Further, the flow path switching mechanism is also composed of a first flow path switching mechanism 6A, a second flow path switching mechanism 6B, and a third flow path switching mechanism 6C corresponding to the three cylinder devices.
Like the first cylinder device 7A and the second cylinder device 7B, the third cylinder device 7C also includes a primary side cylinder 8A, a primary side piston 9A, a secondary side cylinder 8B, and a secondary side piston 9B.

In the second embodiment, for example, when the first cylinder device 7A is in the pumping step and the third cylinder device 9C is in the filling step among the three cylinder devices 7A, 7B, 7C, the second cylinder device 7B is used. In the process of the cylinder devices 7A, 7B, 7C so that the primary side piston 9A and the secondary side piston 9B have reached the other end of the second cylinder device 7B and the second cylinder device 7B is in the standby process. Switching is set. That is, by using one of the three cylinder devices 7A, 7B, and 7C as a pumping process, one as a filling process, and one as a standby process, seawater is always supplied from the water supply pump P1 to supply water. The pulsation of the pump P1 can be suppressed.

As described above, also in the energy recovery device 21 of the second embodiment, the three cylinder devices 7A, 7B, 7C include the primary side cylinder 8A, the primary side piston 9A, the secondary side cylinder 8B, and the secondary side piston 9B. , Penetrated through one end of the primary cylinder 8A and penetrated through the other end of the secondary cylinder 8B to connect the primary side piston 9A and the secondary side piston 9B to connect the primary side piston 9A and the secondary side piston 9A and the secondary side piston. Since each of the connecting shaft portions 12 that move together with 9B is provided and the inner diameter of the primary cylinder 8A and the inner diameter of the secondary cylinder 8B are different, the ratio of the inner diameters of the primary cylinder 8A and the secondary cylinder 8B is set. It becomes possible to set the pressure and the flow rate of the seawater sent out from each of the cylinder devices 7A, 7B, and 7C accordingly.

Next, the difference between the third embodiment and the first embodiment is that in the first embodiment, the inner diameter of the primary cylinder 8A is set smaller than the inner diameter of the secondary cylinder 8B, and the flow path direction regulating mechanism 11 supplies the seawater extruded from the cylinder devices 7A and 7B to the suction side of the high-pressure pump P2, whereas in the energy recovery device 31 of the third embodiment, as shown in FIG. 3, the primary side The inner diameter of the cylinder 8A is set to be larger than the inner diameter of the secondary cylinder 8B, and the flow path direction regulating mechanism 11 supplies the seawater extruded from the cylinder devices 7A and 7B to the discharge side of the high-pressure pump P2. is there.
Further, in the energy recovery device 31 of the third embodiment, one end is connected to the supply pipe 2a and the other end is connected to the high pressure pump P2, and the water supply pipe 2b that sends the seawater from the water supply pump P1 to the high pressure pump P2 as well. It has.

For example, the ratio of the cross-sectional area A1 in the primary side cylinder 8A and the cross-sectional area A2 in the secondary side cylinder 8B is set to the ratio required to pressurize the booster portion 0.2 MPa by the conventional booster pump. Then, the case where the water production rate is 50% will be described.
The flow rate of seawater supplied from the water supply pump P1 is 10,000 m ³ / d.
In this case, in the first cylinder device 7A in the pressure feeding process, assuming that the flow rate of concentrated seawater sent to the primary cylinder 8A is 5,000 m ³ / d and the pressure is 4.0 MPa, the flow rate of seawater in the secondary cylinder 8B is The pressure is 4,762 m ³ / d and the pressure is 4.2 MPa, and the pressure is sent to the connecting pipe 11e.

^{At this time, seawater having a flow rate of 5,238 m 3} / d is sent from the water pipe 2b to the high-pressure pump P2, pressurized by the high-pressure pump P2, and sent out as seawater having a pressure of 4.0 MPa, and the connecting pipe 11e. combined with seawater flow 4,762m ³ / d from, the membrane separation device 5, the flow rate 10,000 m ³ / d, high pressure seawater pressure 4.0MPa fed.
In the membrane separation device 5, concentrated seawater is ^{sent to the cylinder devices 7A and 7B at a flow rate of 5,000 m 3} / d and a pressure of 4.0 MPa, and fresh water (permeated water) is sent to the fresh water pipe 3 at a ^{flow rate of 5,000 m 3 / d.} Be sent out.

As described above, the energy recovery device 31 of the third embodiment includes a water supply pipe 2b that sends seawater from the water supply pump P1 to the high pressure pump P2, and the inner diameter of the primary cylinder 8A is larger than the inner diameter of the secondary cylinder 8B. Since the set flow path direction regulating mechanism 11 supplies the seawater extruded from the cylinder devices 7A and 7B to the discharge side of the high-pressure pump P2, the pressure of the deleted booster pump is applied to the seawater sent out from the high-pressure pump P2. Can be boosted and merged.

That is, the pressure of the seawater sent out from the cylinder devices 7A and 7B increases according to the inner diameter ratio of the primary side cylinder 8A and the secondary side cylinder 8B, and by matching with the pressure of the seawater sent out from the high pressure pump P2, the pressure becomes higher. Seawater can be pumped into the membrane separation device 5. The flow rate of seawater sent to the membrane separation device 5 is the sum of the flow rate of seawater sent from the water pipe 2b to the high-pressure pump P2 and the flow rate of seawater sent from the cylinder devices 7A and 7B. Can be secured.

The present invention is not limited to each of the above embodiments, and various modifications can be made without departing from the spirit of the present invention.

1,1,31 ... Energy recovery device, 2a ... Supply pipe, 2b ... Water supply pipe, 3 ... Freshwater pipe, 4 ... Concentrated water pipe, 5 ... Membrane separation device, 6A ... First flow path switching mechanism, 6B ... Second flow Road switching mechanism, 6C ... 3rd flow path switching mechanism, 7A ... 1st cylinder device, 7B ... 2nd cylinder device, 7C ... 3rd cylinder device, 8A ... primary side cylinder, 8B ... secondary side cylinder, 8a ... primary Side drain hole, 8b ... Secondary side drain hole, 9A ... Primary side piston, 9B ... Secondary side piston, 11 ... Flow path direction regulation mechanism, 12 ... Connecting shaft, 19 ... Concentrated seawater drainage channel, P1 ... Water supply Pump, P2 ... High pressure pump, C ... Control unit

Claims (4)

An energy recovery device connected to a membrane separation device that separates high-pressure seawater into freshwater and concentrated seawater with a reverse osmosis membrane and discharges the freshwater to a freshwater pipe and discharges the high-pressure concentrated seawater to a concentrated water pipe.
A water pump that supplies seawater and
A high-pressure pump that pressurizes the seawater and supplies the high-pressure seawater to the membrane separation device.
One end communicates with the water supply pump to communicate with and shut off the concentrated water pipe, and the other end communicates with the concentrated water pipe via a flow path switching mechanism that communicates with and shuts off the drainage channel of the concentrated seawater. A plurality of cylinder devices connected to the drainage channel and
A flow path direction in which the seawater is connected to one end of the plurality of cylinder devices, the seawater is alternately supplied to the plurality of cylinder devices, and the seawater alternately extruded from the plurality of cylinder devices at high pressure is sent to the membrane separation device. Regulatory mechanism and
A pumping step of controlling the flow path switching mechanism to switch the connection of a plurality of the cylinder devices to the concentrated water pipe and the drainage channel, supplying the concentrated seawater at high pressure to the cylinder device, and pushing out the seawater inside at high pressure. A control unit having a control function for filling the seawater while supplying the seawater from the water supply pump to the cylinder device and discharging the concentrated seawater inside after the pumping step.
The cylinder device includes a primary cylinder in which the other end is connected to the concentrated water pipe and the drainage channel and the concentrated seawater is introduced.
The primary side piston that reciprocates in the primary side cylinder and
A secondary cylinder in which one end communicates with the water supply pump and the seawater is introduced.
A secondary piston that reciprocates in the secondary cylinder,
It is provided with a connecting shaft portion that is penetrated through one end of the primary cylinder and is penetrated by the other end of the secondary cylinder to connect the primary piston and the secondary piston.
The inner diameter of the primary cylinder and the inner diameter of the secondary cylinder are different .
Drain holes are formed at one end of the primary cylinder and the other end of the secondary cylinder.
A piston seal for preventing leakage is provided on the outer peripheral surfaces of the primary side piston and the secondary side piston.
An energy recovery device characterized in that one end of the primary cylinder and the other end of the secondary cylinder facing each other are closed except for a through hole of the connecting shaft portion and a drain hole. In the energy recovery device according to claim 1,
An energy recovery device, wherein the ratio of the inner diameter of the primary cylinder to the inner diameter of the secondary cylinder is set to be the same for all of the plurality of cylinder devices. In the energy recovery device according to claim 1 or 2.
The inner diameter of the primary cylinder is set smaller than the inner diameter of the secondary cylinder.
An energy recovery device, wherein the flow path direction regulating mechanism supplies the seawater extruded from the cylinder device to the suction side of the high-pressure pump. In the energy recovery device according to claim 1 or 2.
A water pipe for sending the seawater from the water supply pump to the high-pressure pump is provided.
The inner diameter of the primary cylinder is set to be larger than the inner diameter of the secondary cylinder.
An energy recovery device, wherein the flow path direction regulating mechanism supplies the seawater extruded from the cylinder device to the discharge side of the high-pressure pump.

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