Multistep type fluid machine

Abstract

To provide a multistep type fluid machine for allowing the operation according to the situation and specification of the machine field.SOLUTION: A multistep type fluid machine 1 includes: a first fluid machine 2A to which pipes 5, 6 are connected; a second fluid machine 2B to which pipes 7, 8 are connected; a rotary shaft 3 for operating the fluid machines 2A, 2B; a connection pipe 10 for connecting the pipes 6, 7; a connection pipe 11 for connecting the pipes 5, 7; a connection pipe 12 for connecting the pipes 6, 8; a three-way valve 14 capable of switching the state of connecting the connection pipe 10 to the pipe 6 and the state of connecting the connection pipe 12 thereto; and an on-off valve 18 capable of switching the state of communicating the pipe 7 and the connection pipe 11 with each other. The switching operations of the three-way valve 14 and the on-off valve 18 enable the first fluid machine 2 and the second fluid machine 2 to execute series connection operation in series connection and parallel connection operation in parallel connection.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a multistage fluid machine. [Background technology]

[0002] Patent Document 1 discloses a reverse-rotation pump turbine power generation system using a double-suction volute pump. In this power generation system, a bypass flow path is provided connecting the inlet and outlet of the reverse-rotation pump turbine, and when the actual flow rate exceeds the rated flow rate at the rated head, the excess flow rate is diverted into the bypass flow path to prevent overload, which would otherwise occur if a current exceeded the rated current. Patent Document 1 also discloses a power generation system in which multiple reverse-rotation pump turbines are connected in parallel. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6433269 Summary of the Invention [Problem to be solved by the invention]

[0004] The power generating device of Patent Document 1 does not take into consideration what to do when the head falls below the rated head. Therefore, the fluid machinery disclosed in Patent Document 1 has room for improvement in terms of optimal operation according to the actual conditions and specifications of the plant.

[0005] An object of the present invention is to provide a multistage fluid machine that can be optimally operated in accordance with the conditions and specifications of the plant. [Means for solving the problem]

[0006] The present invention relates to a first fluid machine to which first and second pipes for passing liquid are connected, a second fluid machine to which third and fourth pipes for passing liquid are connected, a rotating shaft for integrally operating the first fluid machine and the second fluid machine, a first connecting pipe for connecting the second pipe and the third pipe, an end of the third pipe on the opposite side to the second fluid machine with respect to a connection portion of the first connecting pipe, a second connecting pipe for connecting the first pipe, a third connecting pipe for connecting the second pipe and the fourth pipe, a three-way valve switchable between a series connection position in which the first connecting pipe is connected to the second pipe and communication with the third connecting pipe is blocked, and a parallel connection position in which communication with the first connecting pipe is blocked and communication with the third connecting pipe is opened, and The present invention provides a multistage fluid machine comprising an on-off valve that is disposed on the second connecting pipe side of the connection portion or in the second connecting pipe and is switchable between a fully open position that connects the third pipe and the second connecting pipe and a fully closed position that blocks communication between the third pipe and the second connecting pipe, and by switching the three-way valve and the on-off valve, it is possible to perform a series connection operation in which the first pipe, the second pipe, the first connecting pipe, the third pipe, and the fourth pipe are connected in series, and a parallel connection operation in which the first pipe, the second connecting pipe, and the third pipe are connected and the second pipe, the third connecting pipe, and the fourth pipe are connected in parallel.

[0007] The multistage fluid machine of this aspect can perform a series connection operation in which the first fluid machine and the second fluid machine are connected in series, and a parallel connection operation in which they are connected in parallel, by switching the three-way valve and the on-off valve. This multistage fluid machine can be used as a power generation device by connecting a generator to the rotating shaft and supplying water to the fourth pipe and discharging it from the first pipe. On the other hand, the multistage fluid machine can be used as a liquid supply device by connecting a driver to the rotating shaft and sucking water into the first pipe and discharging it from the fourth pipe.

[0008] When used as a power generation device, switching to series connection operation increases the flow rate to each fluid machine compared to parallel connection operation, allowing for increased shaft power of the rotating shaft and increased power generation.On the other hand, switching to parallel connection operation reduces the flow rate to each fluid machine compared to series connection operation, reducing the shaft power of the rotating shaft and power generation, thereby preventing overload.As a result, operation can be performed at optimal power generation efficiency according to the actual head and rated head of the plant.

[0009] When used as a liquid supply system, switching to series connection operation makes it possible to increase the discharge pressure of the fluid machinery, thereby increasing the head and reducing the flow rate, compared to parallel connection operation.On the other hand, switching to parallel connection operation makes it possible to decrease the discharge pressure of the fluid machinery, thereby decreasing the head and increasing the flow rate, compared to series connection operation.As a result, operation can be performed at the optimal pump efficiency (rated head and rated flow rate) required, depending on the actual head and flow rate at the actual plant. [Effects of the Invention]

[0010] The present invention allows for optimal operation according to the conditions and specifications of the plant. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram of a power generating device that is a multistage fluid machine according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a block diagram of the power generating device of FIG. 1. [Figure 3] FIG. 2 is a cross-sectional view showing a three-way valve in a series connection position. [Figure 4] FIG. 2 is a cross-sectional view showing a three-way valve in a parallel connection position. [Figure 5] FIG. 4 is a cross-sectional view showing a three-way valve in an intermediate connection position. [Figure 6] FIG. 2 is a schematic diagram showing a power generation device in a series connection operation state. [Figure 7] FIG. 2 is a schematic diagram showing a power generation device in a parallel connection operation state. [Figure 8] 1 is a schematic diagram showing a power generation system in an intermediate connection operating state; [Figure 9]FIG. 6 is a schematic view of a water supply device which is a multistage fluid machine according to a second embodiment. [Figure 10] FIG. 10 is a block diagram of the water supply device of FIG. [Figure 11] Schematic diagram showing a water supply device in a series connection operating state. [Figure 12] Schematic diagram showing a water supply device in a parallel connection operating state. [Figure 13] Schematic diagram showing a water supply device in an intermediate connection operating state. [Figure 14] FIG. 10 is a schematic view of a power generating device, which is a multistage fluid machine according to a third embodiment. [Figure 15] FIG. 2 is a schematic diagram of a power generating device in a first series connection state. [Figure 16] Schematic diagram of a power generation device connected in parallel. [Figure 17] FIG. 10 is a schematic diagram of the power generation device in a second series connection state. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0013] Referring to Figures 1 and 2, a multistage fluid machine 1 according to an embodiment of the present invention comprises two fluid machines 2A and 2B that can be operated together by a rotating shaft 3, four pipes 5 to 8, three connecting pipes 10 to 12, a three-way valve 14, an on-off valve 18, and a control unit 20.

[0014] The multistage fluid machine 1 can change the communication state of the pipes 5-8 and the connecting pipes 10-12 by controlling the three-way valve 14 and the on-off valve 18 by the control unit 20. Specifically, the state can be changed to a state in which two fluid machines 2A, 2B are connected in series (see FIGS. 6 and 11), a state in which two fluid machines 2A, 2B are connected in parallel (see FIGS. 7 and 12), or a state in which two fluid machines 2A, 2B are connected in series and in parallel (see FIGS. 8 and 13). In the following description, of the two fluid machines, the one located on the right side in FIG. 1 may be referred to as the first fluid machine 2A, and the one located on the left side in FIG. 1 may be referred to as the second fluid machine 2B.

[0015] 1 and 2 is a power generation device 1A in which water flows in through a pipe 8 and flows out through a pipe 5, causing a rotating shaft 3 to rotate and a generator 4 to generate electricity. In this power generation device 1A, a control unit 20 controls a three-way valve 14 and an on-off valve 18 based on an actual head (detected head Hd) and a rated head (effective rated head) Hr determined by specifications, and also controls the on-off valve 18 based on an actual flow rate (detected flow rate Qd) and a rated flow rate Qr at the rated head Hr, thereby enabling operation with optimal power generation efficiency.

[0016] 9 and 10 is a water supply (liquid supply) device 1B that sucks water from a pipe 5 and discharges it from a pipe 8 by rotating a rotary shaft 3 driven by a motor (driver) 27. In this water supply device 1B, a control unit 20 controls the three-way valve 14 and the on-off valve 18 based on the actual head (detected head Hd) and the rated head Hr determined by the specifications, and also controls the on-off valve 18 based on the actual flow rate (detected flow rate Qd) and the rated flow rate Qr at the rated head Hr, enabling operation at optimal pump efficiency.

[0017] The power generation system 1A of the first embodiment shown in Figures 1 and 2 and the water supply system 1B of the second embodiment shown in Figures 9 and 10 have the same basic configuration, including fluid machines 2A, 2B, piping 5-8, connecting pipes 10-12, a three-way valve 14, an on-off valve 18, and a control unit 20. However, the power generation system 1A and the water supply system 1B differ in which of the generator 4 and the motor 27 is connected to the rotating shaft 3.

[0018] (First embodiment) Hereinafter, a power generating device 1A of the first embodiment will be described with reference to FIGS.

[0019] The fluid machines 2A and 2B are configured as double-suction volute pumps or single-suction volute pumps (reverse-rotation water turbines). Each of the fluid machines 2A and 2B has one impeller (not shown) and a pair of connection ports 2a and 2b. In the case of the power generation device 1A, water flows in through the upper connection port (second connection port) 2b in FIG. 1 and flows out through the lower connection port (first connection port) 2a in FIG. 1. The fluid machines 2A and 2B are not limited to double-suction volute pumps or single-suction volute pumps, and can be changed as needed to any reverse-rotation water turbine that allows water to flow in through connection port 2b and out through the other connection port 2a.

[0020] The rotating shaft 3 is formed by a single shaft that operates the two fluid machines 2A, 2B as a unit. The rotating shaft 3 penetrates the casings of the two fluid machines 2A, 2B and is rotatably supported by the casings. Impellers provided in each of the fluid machines 2A, 2B are attached to the rotating shaft 3. The rotation of the impellers caused by the flow of water supplied to the fluid machines 2A, 2B causes the rotating shaft 3 to rotate. However, the rotating shaft 3 may be configured such that a first rotating shaft that penetrates the first fluid machine 2A and a second rotating shaft that is separate from the first rotating shaft and penetrates the second fluid machine 2B are integrally connected by a coupling, and any other configuration can be used as long as it enables the two fluid machines 2A, 2B to operate as a unit.

[0021] The generator 4 is connected to one end of the rotating shaft 3 that protrudes from the first fluid machine 2A, and generates electricity by the rotation of the rotating shaft 3. The generator 4 can be configured in any manner that is normally used.

[0022] The pipe (first pipe) 5 is connected to the connection port 2a of the first fluid machine 2A. The end of the pipe 5 opposite the first fluid machine 2A is connected to a drainage tank (not shown). The pipe (second pipe) 6 is connected to the connection port 2b of the first fluid machine 2A. The end of the pipe 6 opposite the first fluid machine 2A is connected to a three-way valve 14.

[0023] The pipe (third pipe) 7 is connected to the connection port 2a of the second fluid machine 2B. The end of the pipe 7 opposite to the second fluid machine 2B is connected to the pipe 5 via a connection pipe 11. The pipe (fourth pipe) 8 is connected to the connection port 2b of the second fluid machine 2B. The end of the pipe 8 opposite to the second fluid machine 2B is connected to a water tank (not shown) located at a higher position than the fluid machines 2A and 2B.

[0024] The connecting pipe (first connecting pipe) 10 is a crossover pipe for connecting the pipe 6 connected to the first fluid machine 2A and the pipe 7 connected to the second fluid machine 2B. More specifically, one end of the connecting pipe 10 is connected to the end of the pipe 6 opposite to the first fluid machine 2A via a three-way valve 14. The other end of the connecting pipe 10 is connected to an intermediate portion of the pipe 7. In the case of the power generation device 1A, the connecting pipe 10 communicates between the connection port 2a, which is the outlet of the second fluid machine 2B, and the connection port 2b, which is the inlet of the first fluid machine 2A.

[0025] The connecting pipe (second connecting pipe) 11 is a bypass pipe that connects the pipe 5 connected to the first fluid machine 2A and the pipe 7 connected to the second fluid machine 2B. More specifically, one end of the connecting pipe 11 is connected to an intermediate portion of the pipe 5. The other end of the connecting pipe 11 is connected to an end of the pipe 7 that is located on the opposite side to the second fluid machine 2B with respect to the connection portion 7a of the connecting pipe 10. In the case of the power generation device 1A, the connecting pipe 11 communicates between the connection port 2a, which is the outlet of the second fluid machine 2B, and the connection port 2a, which is the outlet of the first fluid machine 2A.

[0026] The connecting pipe (third connecting pipe) 12 is a bypass pipe that connects the pipe 6 connected to the first fluid machine 2A and the pipe 8 connected to the second fluid machine 2B. More specifically, one end of the connecting pipe 12 is connected to the end of the pipe 6 opposite to the first fluid machine 2A via a three-way valve 14. The other end of the connecting pipe 12 is connected to an intermediate portion of the pipe 8. In the case of the power generation device 1A, the connecting pipe 12 communicates between the connection port 2b, which is the inlet of the second fluid machine 2B, and the connection port 2b, which is the inlet of the first fluid machine 2A.

[0027] The three-way valve 14 is configured to switch the communication state of the connecting pipes 10 and 12 with the pipe 6 connected to the first fluid machine 2A. More specifically, the three-way valve 14 is configured as a three-way solenoid valve and is communicatively connected to the control unit 20. Under the control of the control unit 20, the three-way valve 14 can be electrically switched to a series connection state shown in FIG. 3 in which the connecting pipe 10 is connected to the pipe 6 and the communication with the connecting pipe 12 is blocked, a parallel connection state shown in FIG. 4 in which the communication with the connecting pipe 10 is blocked and the connecting pipe 12 is connected, and an intermediate connection state shown in FIG. 5 in which the connecting pipes 10 and 12 are connected at a predetermined ratio. While FIG. 5 shows a state in which the connecting pipes 10 and 12 are connected to the pipe 6 at the same ratio, the communication ratio in the intermediate connection state can be adjusted in stages between the series connection state shown in FIG. 3 and the parallel connection state shown in FIG. 4.

[0028] 3 to 5, the three-way valve 14 includes a valve case 15 and a valve element 16. However, the three-way valve 14 can be modified as needed as long as it has a configuration that allows switching of the communication state of the connecting pipes 10 and 12 with the piping 6.

[0029] The valve case 15 includes a valve chamber 15a in which the valve element 16 is disposed, and three cylindrical connection parts 15b to 15d that communicate with the valve chamber 15a. The first connection part 15b is connected to the piping 6 that is connected to the first fluid machine 2A, the second connection part 15c is connected to the connection pipe 10, and the third connection part 15d is connected to the connection pipe 12.

[0030] The valve element 16 is spherical and rotatably disposed in the valve chamber 15a. The valve element 16 can switch the communication state of the second connection portion 15c and the third connection portion 15d with respect to the first connection portion 15b via a flow path 16a through which water can flow. Specifically, the valve element 16 can be switched among a series connection position in which the first connection portion 15b and the second connection portion 15c are connected via the flow path 16a and the third connection portion 15d are not connected; a parallel connection position in which the first connection portion 15b and the third connection portion 15d are connected via the flow path 16a and the second connection portion 15c is not connected; and an intermediate connection position in which the first connection portion 15b is connected to both the second connection portion 15c and the third connection portion 15d via the flow path 16a. In the series connection position, first connection portion 15b and second connection portion 15c are 100% connected, and in the parallel connection position, first connection portion 15b and third connection portion 15d are 100% connected. In the intermediate connection position shown in Figure 5, second connection portion 15c and third connection portion 15d are connected to first connection portion 15b at the same rate. However, the rate at which second connection portion 15c and third connection portion 15d are connected to first connection portion 15b can be changed by adjusting the rotational angle position of valve body 16.

[0031] The on-off valve 18 is configured to switch the communication state between the piping 7 connected to the second fluid machine 2B and the connecting pipe 11. The on-off valve 18 is configured by an electromagnetic valve and is communicatively connected to the control unit 20. Under the control of the control unit 20, the on-off valve 18 can be electrically switched between a fully open position in which the connecting pipe 11 is connected to the piping 7, a fully closed position in which the connecting pipe 11 is blocked from communication, and an intermediate position in which the connecting pipe 11 is connected to the piping 7 at a predetermined rate (opening degree). The opening degree at the intermediate position can be adjusted in stages between the fully open position and the fully closed position. The on-off valve 18 is disposed in the piping 7 connected to the second fluid machine 2B, closer to the connecting pipe 11 than the connection portion 7a of the connecting pipe 10. However, the on-off valve 18 may be disposed in the connecting pipe 11 or between the piping 7 and the connecting pipe 11.

[0032] 1 and 2, the control unit 20 is connected to the generator 4, the three-way valve 14, the on-off valve 18, a pair of pressure sensors 22A and 22B, a flow rate sensor 23, and an input unit 24. The control unit 20 is composed of one or more microcomputers and other electronic devices, and includes a memory 21 that stores programs for controlling the communication ratio of the three-way valve 14 and the on-off valve 18, as well as setting values ​​(rated head Hr and rated flow rate Qr) used in the programs.

[0033] The first pressure sensor 22A is disposed in the pipe 5 on the opposite side to the first fluid machine 2A with respect to the connection portion 5a of the connecting pipe 11. The second pressure sensor 22B is disposed in the pipe 8 on the opposite side to the second fluid machine 2B with respect to the connection portion 7a of the connecting pipe 12. The pressure sensors 22A and 22B are pressure detection units that detect the pressure inside the pipes 5 and 8, respectively. Any pressure detection unit can be applied as long as it has a configuration that can detect the pressure inside the pipes 5 and 8. The pressure detection unit may also be a differential pressure sensor that detects the pressure difference (differential pressure) inside the pipes 5 and 8.

[0034] The flow rate sensor 23 is disposed in the pipe 8 near the connection portion 8a of the connecting pipe 12, on the opposite side of the connection portion 8a from the second fluid machine 2B. The flow rate sensor 23 is a flow rate detection unit that detects the actual flow rate per unit time flowing through the pipe 8. However, any flow rate detection unit can be applied as long as it has a configuration that can detect the flow rate passing through the pipe 8.

[0035] The input unit 24 is a switch, and allows the rated head Hr and rated flow rate Qr according to the conditions of the plant to be input as specifications.

[0036] The control unit 20 switches the three-way valve 14 and the on-off valve 18 based on the detected head Hd obtained from the pressures P1, P2 detected by the pressure sensors 22A, 22B and the rated head Hr stored in the memory 21. The control unit 20 further switches the on-off valve 18 based on the flow rate Qd detected by the flow rate sensor 23 and the rated flow rate Qr stored in the memory 21. The detected head Hd can be calculated from the difference between the pressure P2 detected by the upstream pressure sensor 22B and the pressure P1 detected by the downstream pressure sensor 22A.

[0037] Specifically, the control unit 20 switches the three-way valve 14 and the on-off valve 18 to operate the piping system shown in Fig. 1 in the series connection state shown in Fig. 6 or the parallel connection state shown in Fig. 7. In addition, in order to maintain the highest power generation efficiency by the generator 4 and to prevent damage due to overload, the control unit 20 adjusts the communication ratio of the three-way valve 14 and the opening degree of the on-off valve 18 to operate the system in the intermediate connection state shown in Fig. 8.

[0038] In the series connection operation shown in Fig. 6, the three-way valve 14 is switched to the series connection position shown in Fig. 3, and the on-off valve 18 is switched to a fully closed state. As a result, the pipes 8 and 7, the connecting pipe 10, and the pipes 6 and 5 are connected in this order, and the two fluid machines 2B and 2A are connected in series. In this state, all of the water that flows into the pipe 8 passes through the fluid machines 2A and 2B, so the amount of power generated by the generator 4 due to the rotation of the rotating shaft 3 is maximized.

[0039] In the parallel connection operation shown in Fig. 7, the three-way valve 14 is switched to the parallel connection position shown in Fig. 4, and the on-off valve 18 is switched to the fully open position. As a result, the pipe 8, the connecting pipe 12, and the pipe 6 communicate with each other, and the pipe 7, the connecting pipe 11, and the pipe 5 communicate with each other, and the two fluid machines 2B, 2A are connected in parallel. In this state, the water that flows into the pipe 8 is equally divided and passes through the fluid machines 2A, 2B, so the amount of power generated by the generator 4 due to the rotation of the rotating shaft 3 is minimized.

[0040] The intermediate connection operation shown in FIG. 8 is a state in which the three-way valve 14 is switched to the intermediate connection position shown in FIG. 5 and the on-off valve 18 is switched to a 50% opening. In this intermediate connection state, the pipes 8, 7, the connecting pipe 10, and the pipes 6, 5 are connected to each other, and the pipes 8, 12, and 6 are connected to the pipes 7, 11, and 5, and the two fluid machines 2B, 2A are connected in series and in parallel. In this state, water flowing into the pipe 8 is equally divided and passes through the fluid machines 2A, 2B, but the passing flow rate is lower than in the series connection operation shown in FIG. 6 and higher than in the parallel connection operation shown in FIG. 7. Therefore, the amount of power generated by the generator 4 due to the rotation of the rotating shaft 3 is also lower than in the series connection operation shown in FIG. 6 and higher than in the parallel connection operation shown in FIG. 7.

[0041] Next, an example of the control of the three-way valve 14 and the on-off valve 18 by the control unit 20 of the first embodiment will be described. However, the control by the control unit 20 can be changed as necessary.

[0042] First, at the start of operation, the control unit 20 sets the pipes 5 to 8 and the connecting pipes 10 to 12 to the intermediate connection operation shown in FIG.

[0043] Next, the control unit 20 compares the detected head Hd by the pressure sensors 22A, 22B with the rated head Hr, and when the detected head Hd is less than the rated head Hr, the control unit 20 switches the three-way valve 14 and the on-off valve 18 to perform the series connection operation shown in Fig. 6. On the other hand, when the detected head Hd exceeds the rated head Hr, the control unit 20 switches the three-way valve 14 and the on-off valve 18 to perform the parallel connection operation shown in Fig. 7.

[0044] When the series connection operation shown in Fig. 6 is performed and the detected head Hd exceeds the rated head Hr, the control unit 20 switches the three-way valve 14 to the parallel connection position shown in Fig. 4. Here, switching the three-way valve 14 to the parallel connection position means rotating the valve element 16 of the three-way valve 14 in the series connection position shown in Fig. 3 clockwise to reduce the communication ratio of the connecting pipe 10 to the pipe 6 (for example, reduce by 10%) and increase the communication ratio of the connecting pipe 12 to the pipe 6 (for example, increase by 10%).

[0045] When the parallel connection operation shown in Fig. 7 is performed and the detected head Hd falls below the rated head Hr, the control unit 20 switches the three-way valve 14 to the series connection position shown in Fig. 3. Here, switching the three-way valve 14 to the series connection position means rotating the valve element 16 of the three-way valve 14 in the parallel connection position shown in Fig. 4 counterclockwise to increase the communication ratio of the connecting pipe 10 to the pipe 6 (for example, increase by 10%) and decrease the communication ratio of the connecting pipe 12 to the pipe 6 (for example, decrease by 10%).

[0046] When the detected head Hd and the rated head Hr roughly match due to switching of the three-way valve 14, the control unit 20 compares the flow rate Qd detected by the flow sensor 23 with the rated flow rate Qr by switching the on-off valve 18. When the detected flow rate Qd is lower than the rated flow rate Qr, the control unit 20 switches the opening of the on-off valve 18 to the fully closed position, and when the detected flow rate Qd exceeds the rated flow rate Qr, the control unit 20 switches the opening of the on-off valve 18 to the fully open position. Here, switching the opening to the fully closed position means reducing the opening (degree of communication) of the on-off valve 18 (for example, by 10% reduction), and switching the opening to the fully open position means increasing the opening of the on-off valve 18 (for example, by 10% increase).

[0047] After adjusting the communication ratio of the three-way valve 14 and the opening degree of the on-off valve 18 in the above manner, the control unit 20 subsequently detects the detected head Hd using the pressure sensors 22A and 22B, and detects the detected flow rate Qd using the flow rate sensor 23. If fluctuations occur in the actual head Hd and the actual flow rate Qd, the control unit 20 readjusts the communication ratio of the three-way valve 14 and the opening degree of the on-off valve 18.

[0048] As described above, the control unit 20 proportionally controls the communication rate of the three-way valve 14 and the opening degree of the on-off valve 18 based on the detected head Hd and rated head Hr by the pressure sensors 22A and 22B, and the detected flow rate Qd and rated flow rate Qr by the flow rate sensor 23. Therefore, even if the actual detected head Hr changes, it can be adjusted to approach the rated head specified for maximum efficiency.

[0049] The power generating device 1A (multistage fluid machine 1) of the first embodiment configured as above has the following features.

[0050] By switching the three-way valve 14 and the on-off valve 18, the multi-stage fluid machine 1 can perform series connection operation in which the first fluid machine 2A and the second fluid machine 2B are connected in series, and parallel connection operation in which they are connected in parallel.

[0051] A control unit 20 is provided to control the three-way valve 14 and the on-off valve 18 based on the pressure difference between the inside of the pipe 5 and the inside of the pipe 8. Therefore, optimal operation can be performed according to the conditions and specifications of the plant.

[0052] When used as a power generation system 1A, by switching to the series connection operation shown in Fig. 6, the flow rate to each of the fluid machines 2A and 2B increases compared to the parallel connection operation shown in Fig. 7, so the shaft power of the rotating shaft 3 can be increased and the amount of power generated can be increased. On the other hand, by switching to the parallel connection operation shown in Fig. 7, the flow rate to each of the fluid machines 2A and 2B decreases compared to the series connection operation shown in Fig. 6, so the shaft power of the rotating shaft 3 can be reduced and the amount of power generated can be reduced, thereby suppressing overload. Therefore, operation can be performed with optimal power generation efficiency according to the actual head and rated head of the plant.

[0053] When the detected head Hd is lower than the rated head Hr, the control unit 20 switches the three-way valve 14 to the series connection position and switches the on-off valve 18 to the fully closed position. This increases the communication ratio of the piping 6 to the connecting pipe 10, increasing the shaft power of the rotating shaft 3 of the fluid machines 2A and 2B, thereby increasing the amount of power generated by the generator 4. On the other hand, when the detected head Hd is higher than the rated head Hr, the control unit 20 switches the three-way valve 14 to the parallel connection position and switches the on-off valve 18 to the fully open position. This decreases the communication ratio of the piping 6 to the connecting pipe 10, reducing the shaft power of the rotating shaft 3 of the fluid machines 2A and 2B, thereby reducing the amount of power generated by the generator 4. This ensures optimal power generation according to the conditions and specifications of the plant.

[0054] When the detected flow rate Qd is lower than the rated flow rate Qr, the control unit 20 switches the on-off valve 18 to the fully closed position. This increases the flow rate for each of the fluid machines 2A and 2B, and increases the shaft power of the rotating shaft 3 of the fluid machines 2A and 2B, making it possible to increase the amount of power generated by the generator 4. On the other hand, when the detected flow rate Qd is higher than the rated flow rate Qr, the control unit 20 switches the on-off valve 18 to the fully open position. This reduces the flow rate for each of the fluid machines 2A and 2B, and decreases the shaft power of the rotating shaft 3 of the fluid machines 2A and 2B, making it possible to reduce the amount of power generated by the generator 4. This ensures that optimal power generation can be performed according to the conditions and specifications of the plant.

[0055] Other embodiments and various modifications of the present invention will be described below, but in these descriptions, points that are not particularly mentioned are the same as those in the first embodiment. In the drawings referred to below, the same elements as those in the first embodiment are given the same reference numerals.

[0056] (Second embodiment) Next, a water supply device 1B of a second embodiment will be described with reference to Figures 9 and 10. This water supply device 1B differs from the power generation device 1A of the first embodiment shown in Figures 1 and 2 only in that a motor 27 is connected to the rotating shaft 3.

[0057] The motor 27 is a driving machine connected to one end of the rotating shaft 3 that protrudes from the first fluid machine 2A, and rotates the rotating shaft 3. However, the driving machine may be an internal combustion engine, and any driving machine can be used as long as it is configured to rotate the rotating shaft 3.

[0058] As in the first embodiment, the fluid machines 2A and 2B are configured as double-suction volute pumps or single-suction volute pumps. In the case of the water supply apparatus 1B, water is sucked in through the lower connection port (first connection port) 2a in Fig. 1 and discharged from the upper connection port (second connection port) 2b in Fig. 1. The fluid machines 2A and 2B are not limited to double-suction volute pumps or single-suction volute pumps, and can be changed as needed to any pump that can suck water in through connection port 2a and discharge it from connection port 2b.

[0059] The pipes 5 to 8 differ only in that the end of the pipe (first pipe) 5 opposite to the first fluid machine 2A is connected to a water suction tank (not shown), and the end of the pipe (fourth pipe) 8 opposite to the second fluid machine 2B is connected to a water supply tank (not shown). The water supply tank is disposed at a higher position than the fluid machines 2A and 2B.

[0060] The piping structure of the connecting pipes 10-12 is the same as that of the first embodiment. In the case of the water supply apparatus 1B, the connecting pipe (first connecting pipe) 10 connects the connecting port 2b, which is the outlet of the first fluid machine 2A, to the connecting port 2a, which is the inlet of the second fluid machine 2B. The connecting pipe (second connecting pipe) 11 connects the connecting port 2a, which is the inlet of the first fluid machine 2A, to the connecting port 2a, which is the inlet of the second fluid machine 2B. The connecting pipe (third connecting pipe) 12 connects the connecting port 2b, which is the outlet of the first fluid machine 2A, to the connecting port 2b, which is the outlet of the second fluid machine 2B.

[0061] The control unit 20 differs from the power generation 1A of the first embodiment only in the program and setting values ​​(rated head Hr and rated flow rate Qr) stored in the memory 21. The rated head Hr is determined as a specification based on the pressure required to supply water to the water tank.

[0062] The control unit 20 switches the three-way valve 14 and the on-off valve 18 based on the detected head Hd obtained from the pressures P1, P2 detected by the pressure sensors 22A, 22B and the rated head Hr stored in the memory 21. The control unit 20 further switches the on-off valve 18 based on the flow rate Qd detected by the flow rate sensor 23 and the rated flow rate Qr stored in the memory 21. The detected head Hd can be calculated from the difference between the pressure P2 detected by the upstream pressure sensor 22B and the pressure P1 detected by the downstream pressure sensor 22A.

[0063] Specifically, the control unit 20 switches the three-way valve 14 and the on-off valve 18 to operate the piping system shown in Fig. 9 in a series connection state shown in Fig. 11 or a parallel connection state shown in Fig. 12. In addition, in order to maintain the highest pump efficiency by the motor 27, the control unit 20 adjusts the communication ratio of the three-way valve 14 and the opening degree of the on-off valve 18 to operate the system in an intermediate connection state shown in Fig. 13.

[0064] In the series connection operation shown in Fig. 11, the three-way valve 14 is switched to the series connection position shown in Fig. 3, and the on-off valve 18 is switched to a fully closed state. As a result, the pipes 5 and 6, the connecting pipe 10, and the pipes 7 and 8 are connected in this order, and the two fluid machines 2A and 2B are connected in series. In this state, all of the water sucked from the pipe 5 passes through the fluid machines 2A and 2B, so the water discharge pressure caused by the rotation of the rotating shaft 3 is at its highest. However, the water discharge flow rate is at its lowest.

[0065] In the parallel connection operation shown in Fig. 12, the three-way valve 14 is switched to the parallel connection position shown in Fig. 4, and the on-off valve 18 is switched to the fully open position. As a result, the pipe 5, the connecting pipe 11, and the pipe 7 are connected to each other, and the pipe 6, the connecting pipe 12, and the pipe 8 are connected to each other, and the two fluid machines 2A and 2B are connected in parallel. In this state, the water sucked in from the pipe 5 is equally divided and passes through the fluid machines 2A and 2B, so the water discharge pressure due to the rotation of the rotating shaft 3 is at its lowest. However, the water discharge flow rate is at its highest.

[0066] The intermediate connection operation shown in Figure 13 is a state in which the three-way valve 14 is switched to the intermediate connection position shown in Figure 5 and the on-off valve 18 is switched to an opening degree of 50%. In this intermediate connection state, the pipes 5 and 6, the connecting pipe 10, and the pipes 7 and 8 are connected to each other, and the pipes 5, 11, and 7 are connected to the pipes 6, 12, and 8, and the two fluid machines 2B and 2A are connected in series and in parallel. In this state, water sucked from the pipe 5 is equally divided and passes through the fluid machines 2A and 2B, but the passing flow rate is lower than in the series connection operation shown in Figure 11 and higher than in the parallel connection operation shown in Figure 12. Therefore, the discharge pressure caused by the rotation of the rotating shaft 3 is lower than the discharge pressure in the series connection operation shown in Figure 11 and higher than the discharge pressure in the parallel connection operation shown in Figure 12.

[0067] Next, an example of the control of the three-way valve 14 and the on-off valve 18 by the control unit 20 of the second embodiment will be described. However, the control by the control unit 20 can be changed as necessary.

[0068] First, at the start of operation, the control unit 20 sets the pipes 5 to 8 and the connecting pipes 10 to 12 to the intermediate connection operation shown in FIG.

[0069] Next, the control unit 20 compares the detected head Hd by the pressure sensors 22A, 22B with the rated head Hr, and when the detected head Hd is lower than the rated head Hr, switches the three-way valve 14 and the on-off valve 18 to perform the series connection operation shown in Figure 11, while when the detected head Hd is higher than the rated head Hr, switches the three-way valve 14 and the on-off valve 18 to switch to the parallel connection operation shown in Figure 12.

[0070] When the series connection operation shown in Fig. 11 is performed and the detected head Hd exceeds the rated head Hr, the three-way valve 14 is switched to the parallel connection position shown in Fig. 4, as in the case of the power generation plant 1A of the first embodiment. On the other hand, when the parallel connection operation shown in Fig. 12 is performed and the detected head Hd falls below the rated head Hr, the three-way valve 14 is switched to the series connection position shown in Fig. 3.

[0071] When the detected head Hd and the rated head Hr roughly coincide with each other by switching the three-way valve 14, the control unit 20 compares the flow rate Qd detected by the flow sensor 23 with the rated flow rate Qr by switching the on-off valve 18. When the detected flow rate Qd is lower than the rated flow rate Qr, the opening of the on-off valve 18 is switched to the fully closed position, and when the detected flow rate Qd is higher than the rated flow rate Qr, the opening of the on-off valve 18 is switched to the fully open position.

[0072] After adjusting the communication ratio of the three-way valve 14 and the opening degree of the on-off valve 18, the control unit 20 subsequently detects the detected head Hd using the pressure sensors 22A and 22B, and detects the detected flow rate Qd using the flow rate sensor 23. If fluctuations occur in the actual head Hd and the actual flow rate Qd, the control unit 20 readjusts the communication ratio of the three-way valve 14 and the opening degree of the on-off valve 18.

[0073] As described above, the control unit 20 proportionally controls the communication ratio of the three-way valve 14 and the opening degree of the on-off valve 18 based on the detected head Hd and rated head Hr by the pressure sensors 22A and 22B, and the detected flow rate Qd and rated flow rate Qr by the flow rate sensor 23. Therefore, even if the actual detected head Hr changes, it can be adjusted to approach the rated head of the most efficient specification.

[0074] The water supply device 1B of the second embodiment configured as above has the following features.

[0075] When used as a water supply system 1B, by switching to the series connection operation shown in Figure 11, the discharge pressure of the fluid machines 2A, 2B can be increased to increase the head and reduce the flow rate compared to the parallel connection operation shown in Figure 12. On the other hand, by switching to the parallel connection operation shown in Figure 12, the discharge pressure of the fluid machines 2A, 2B can be decreased to decrease the head and increase the flow rate compared to the series connection operation shown in Figure 11. Therefore, operation can be performed at the required pump efficiency (rated head and rated flow rate) according to the actual head and actual flow rate at the actual plant.

[0076] When the detected head Hd is lower than the rated head Hr, the control unit 20 switches the three-way valve 14 to the series connection position and switches the on-off valve 18 to the fully closed position. This increases the communication ratio of the piping 6 to the connecting pipe 10, and the discharge pressure of the fluid machines 2A and 2B increases, allowing the head of the discharged water to be increased. On the other hand, when the detected head Hd is higher than the rated head Hr, the control unit 20 switches the three-way valve 14 to the parallel connection position and switches the on-off valve 18 to the fully open position. This decreases the communication ratio of the piping 6 to the connecting pipe 10, and the discharge pressure of the fluid machines 2A and 2B decreases, allowing the head of the discharged water to be reduced. This ensures that discharge can be performed according to the conditions and specifications of the plant.

[0077] When the detected flow rate Qd is lower than the rated flow rate Qr, the control unit 20 switches the on-off valve 18 to the fully closed position. This increases the flow rate for each of the fluid machines 2A and 2B, and the discharge pressure from the fluid machines 2A and 2B increases, making it possible to increase the head of the discharged water. On the other hand, when the flow rate exceeds the rated flow rate, the control unit 20 switches the on-off valve 18 to the fully open position. This reduces the flow rate for each of the fluid machines 2A and 2B, and therefore the discharge pressure from the fluid machines 2A and 2B decreases, making it possible to lower the head of the discharged water. This ensures that discharge can be performed in accordance with the conditions and specifications of the plant.

[0078] (Third embodiment) 14 shows a power generation device 1A which is a multistage fluid machine 1 of the third embodiment. However, the multistage fluid machine 1 may also be used as a water supply device 1B by connecting a motor 27 to the rotating shaft 3 instead of the generator 4.

[0079] 14, a power generating device 1A of the third embodiment includes four fluid machines 2A to 2D. The four fluid machines 2A to 2D can be operated integrally by a rotary shaft 3.

[0080] The first fluid machine 2A and the second fluid machine 2B are connected by pipes 5A to 8A and connecting pipes 10A to 12A, similar to those in the first embodiment, and the connection state thereof can be switched by a three-way valve 14A and an on-off valve 18A. The third fluid machine 2C and the fourth fluid machine 2D are connected by pipes 5B to 8B and connecting pipes 10B to 12B, and the connection state thereof can be switched by a three-way valve 14B and an on-off valve 18B. In other words, the power generation system 1A of the third embodiment is composed of two fluid machine groups, each consisting of a pair of fluid machines 2A, 2B and a pair of fluid machines 2C, 2D. However, the power generation system 1A of the third embodiment may be composed of three or more fluid machine groups.

[0081] The pipe 8A connected to the second fluid machine 2B and the pipe 5B connected to the third fluid machine 2C are connected by a connecting pipe 10C, which is a crossover pipe, via a four-way valve 30. The pipe 7A connected to the second fluid machine 2B and the pipe 5B connected to the third fluid machine 2C are connected by a connecting pipe 11C.

[0082] The piping 8A, the connecting pipe 12A, and the connecting pipe 11C connected to the second fluid machine 2B are connected to the piping 8B connected to the fourth fluid machine 2D via the four-way valve 30 and the connecting pipe 12C. The end of the connecting pipe 12C opposite to the four-way valve 30 is connected to the piping 8B between the connecting portion 8a and the pressure sensor 22B.

[0083] An on-off valve 18C is provided in the piping 5B connected to the third fluid machine 2C. The on-off valve 18C is provided in the piping 5B on the opposite side to the third fluid machine 2C with respect to the connection portion 5b of the connecting pipe 10C.

[0084] The four-way valve 30 is connected to the piping 8A, the connecting pipe 12A, the connecting pipe 10C, and the connecting pipe 12C, which are connected to the second fluid machine 2B. The four-way valve 30 can be switched by the control unit 20 to a full series connection state shown in FIG. 15, a full parallel connection state shown in FIG. 16, and a semi-series connection state shown in FIG. 17. In the full series connection state shown in FIG. 15, the piping 8A and the connecting pipe 10C are connected to each other, and the connecting pipes 12A and 12C are disconnected, connecting all of the fluid machines 2A to 2D in series. In the full parallel connection state shown in FIG. 16, the piping 8A and the connecting pipes 12A and 12C are connected to each other, and the connecting pipe 10C is disconnected, connecting all of the fluid machines 2A to 2D in parallel. In the semi-series connection position shown in Figure 17, the pipe 8A and the connecting pipe 12C are connected, and the connection between the connecting pipes 10C and 12A is blocked, so that the first fluid machine group 2A and 2B and the second fluid machine group 2C and 2D are connected in series, and the first fluid machine group 2A and 2B and the second fluid machine group 2C and 2D are connected in parallel.

[0085] The third embodiment configured as described above can achieve the same effects and advantages as the first embodiment. Moreover, since the fluid machines 2A to 2D can be switched between a full series connection state, a full parallel connection state, and a semi-series connection state, the adjustable range can be expanded depending on the actual head and rated head of the plant. The same applies when the multi-stage fluid machine 1 of the third embodiment is used as a water supply system 1B.

[0086] The present invention is not limited to the configuration of the above embodiment, and various modifications are possible.

[0087] For example, the three-way valve 14 may be switchable only between a series connection position and a parallel connection position. The on-off valve 18 may be switchable only between a fully open position and a fully closed position. Furthermore, the three-way valve 14 and the on-off valve 18 may each be configured to be manually switchable. [Explanation of symbols]

[0088] 1 Multi-stage fluid machine 1A Power Generation Equipment 1B Water supply device 2A,2B Fluid machinery 2a connection port 2b connection port 3 Rotation Axis 4. Generator 5 Piping (1st Piping) 5a Connection site 6 Piping (second piping) 7 Piping (third piping) 7a Connection site 8 Pipe (4th Pipe) 8a Connection site 10, 10A~10C Connecting pipe (first connecting pipe) 11, 11A to 11C Connecting pipe (second connecting pipe) 12, 12A to 12C Connecting pipe (third connecting pipe) 14, 14A, 14B three-way valve 15 Valve case 15a Valve chamber 15b First connection part 15c Second connection part 15d Third connection part 16 Valve body 16a Flow path 18, 18A~18C On-off valve 20 Control Unit 21 Memory 22A, 22B pressure sensor 23 Flow sensor 24 Input section 27 Motor 30 Four-way valve

Claims

1. a first fluid machine to which a first pipe and a second pipe for passing liquid are connected; a second fluid machine to which a third pipe and a fourth pipe for passing liquid are connected; a rotating shaft that integrally operates the first fluid machine and the second fluid machine; a first connecting pipe for connecting the second pipe and the third pipe; a second connecting pipe connecting an end of the third pipe on the opposite side to the second fluid machine with respect to a connecting portion of the first connecting pipe to the first pipe; a third connecting pipe for connecting the second pipe and the fourth pipe; a three-way valve switchable between a series connection position in which the first connecting pipe is connected to the second pipe and the third connecting pipe is disconnected, and a parallel connection position in which the first connecting pipe is disconnected and the third connecting pipe is connected to the second pipe; an on-off valve that is disposed on the second connecting pipe side of the third pipe relative to the connection portion or on the second connecting pipe and is switchable between a fully open position that connects the third pipe with the second connecting pipe and a fully closed position that blocks communication between the third pipe and the second connecting pipe; Equipped with By switching the three-way valve and the on-off valve, a series connection operation in which the first pipe, the second pipe, the first connecting pipe, the third pipe, and the fourth pipe are communicated with each other, and the first fluid machine and the second fluid machine are connected in series; a parallel connection operation in which the first pipe, the second connecting pipe, and the third pipe are communicated with each other, and the second pipe, the third connecting pipe, and the fourth pipe are communicated with each other, and the first fluid machine and the second fluid machine are connected in parallel; A multi-stage fluid machine capable of performing the above.

2. The multistage fluid machine according to claim 1 , further comprising a control unit that controls the three-way valve and the on-off valve based on a pressure difference between the first pipe and the fourth pipe.

3. a generator connected to the rotating shaft; a liquid is supplied to the fourth pipe and flows out of the first pipe, and the flow of the liquid to the first fluid machine and the second fluid machine rotates the rotating shaft, causing the generator to generate electricity; the three-way valve is capable of adjusting in a stepwise manner a communication ratio of the first connecting pipe and the third connecting pipe with respect to the second pipe between the series connection position and the parallel connection position; the on-off valve is capable of adjusting an opening degree in stages between the fully open position and the fully closed position, The control unit When the head, which is the pressure difference, falls below a rated head, the three-way valve is switched to the series connection position and the on-off valve is switched to the fully closed position; 3. The multistage fluid machine according to claim 2, wherein when the head exceeds the rated head, the three-way valve is switched to the parallel connection position and the on-off valve is switched to the fully open position.

4. The control unit When the flow rate through the fourth pipe falls below a rated flow rate, the on-off valve is switched to the fully closed position; 4. The multistage fluid machine according to claim 3, wherein the on-off valve is switched to the fully open position when the flow rate exceeds the rated flow rate.

5. A driving machine is connected to the rotating shaft, a configuration in which liquid is sucked through the first pipe and discharged through the fourth pipe by rotation of the rotary shaft by the driver, the three-way valve is capable of adjusting in a stepwise manner a communication ratio of the first connecting pipe and the third connecting pipe with respect to the second pipe between the series connection position and the parallel connection position; the on-off valve is capable of adjusting an opening degree in stages between the fully open position and the fully closed position, The control unit When the head, which is the pressure difference, falls below a rated head, the three-way valve is switched to the series connection position and the on-off valve is switched to the fully closed position; 3. The multistage fluid machine according to claim 2, wherein when the head exceeds the rated head, the three-way valve is switched to the parallel connection position and the on-off valve is switched to the fully open position.

6. The control unit When the flow rate through the fourth pipe falls below a rated flow rate, the on-off valve is switched to the fully closed position; 6. The multistage fluid machine according to claim 5, wherein the on-off valve is switched to the fully open position when the flow rate exceeds the rated flow rate.

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