Drainage pump equipment

Abstract

To provide a drainage pumping system in which a drainage pump having a small discharge amount is placed in a first drainage pit so that the drainage pump that is started first discharges a suitable amount of water, and this drainage pump can be started first and reliably.SOLUTION: A drainage pump 2, a drainage pump 3, and a drainage pump 4 are placed in a drainage pit 1 that collects water such as water leaking from a water wheel of a power plant, and the drainage pump 4 has a smaller discharge amount per predetermined time than the drainage pumps 2 and 3 and is activated by a water level detection result by a water level detection device 20 different from a water level detection device 200 for the drainage pumps 2 and 3. The water level detection device 20 uses as a reference a water level shallower than a reference water level of the water level detection device 200, and the drainage pump 4 is activated when the water level reaches this reference, so that the drainage pump 4 is activated first among the drainage pumps 2, 3, and 4, and the water level detection device 20 is a float switch type to ensure reliable activation of the drainage pump 4.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a drainage pump facility for a power plant such as a hydroelectric power plant. [Background technology]

[0002] As shown in Patent Documents 1 and 2, for example, hydroelectric power plants have a first drainage pit at the bottom of the power plant building to temporarily store water leaking from the turbines and the like, and the water is drained from this first drainage pit to the outside. Since the water may contain oil when drained from the first drainage pit to the outside in this way, a second drainage pit is sometimes placed outdoors between the first drainage pit and the outside to detect oil, and an oil detection device is sometimes installed in the second drainage pit.

[0003] On the other hand, as in Patent Document 2, water temporarily stored in the first drainage pit may be drained using, for example, two drainage pumps placed in the first drainage pit. For example, one drainage pump may be used as a regular drainage pump and the other as a backup drainage pump. In this case, when a water level detection device placed in the first drainage pit detects that the water level in the drainage pit has reached a predetermined standard, a signal is sent from the water level detection device to the motor of the regular drainage pump via a predetermined path, activating the regular drainage pump and draining the water from the first drainage pit. When the regular drainage pump is unable to drain due to a malfunction or breakdown, and the water level in the first drainage pit rises further, and the water level detection device placed in the drainage pit detects that the water level in the first drainage pit has reached a second standard, a signal is sent from the water level detection device to the motor of the backup drainage pump via a predetermined path, activating the backup drainage pump and draining the water from the first drainage pit. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-20086 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-162659 Summary of the Invention [Problem to be solved by the invention]

[0005] However, if the discharge volume per given time of the drainage pump is large due to a mismatch between the actual amount of water leakage from the power plant and the designed discharge volume of the drainage pump, the large amount of wastewater sent to the second drainage pit will inadvertently stir up the water surface in the second drainage pit, causing a malfunction of the oil detection device floating on the surface of the wastewater stored in the second drainage pit.

[0006] Furthermore, a wire-type float 200 as shown in Fig. 6 is generally used as a device for detecting the water level in a drainage pit. As shown in Fig. 6, the wire-type float 200 is configured to include, for example, a float 201, a tube 201a for surrounding the float 201, a wire 202, a drum 203 for winding the wire 202, a mechanism 204 for setting the water level, and a weight 205. However, with the wire-type float 200 as shown in Fig. 6, there have been cases where doubts have arisen about its reliable water level detection capability, due to the wire 202 becoming twisted or kinked in the low water level range that is normally used.

[0007] The present invention has been made to solve such problems, and its main objective is to provide a drainage pump facility in which a drainage pump with a discharge volume per specified time that is smaller than the other drainage pumps is placed in a first drainage pit so that the drainage pump that is started first will discharge an appropriate amount of water, and this placed drainage pump can be started first and reliably. [Means for solving the problem]

[0008] In order to achieve the above object, the drainage pump equipment of the present invention is arranged between a first drainage pit that stores water from equipment in a power plant and a drainage path from the first drainage pit to a drainage destination of the drainage, The first drainage pit a second drainage pit for storing water from the first drainage pit; a first drainage pump disposed in the first drainage pit for sending water from the first drainage pit to the second drainage pit; a second drainage pump disposed in the first drainage pit for sending water from the first drainage pit to the second drainage pit, the second drainage pump being different from the first drainage pump; a first water level detection device for detecting when the water level of the water accumulated in the first drainage pit reaches a predetermined standard in the first and second drainage pumps and prompting the first and second drainage pumps to start; and an oil detection device disposed in the second drainage pit for detecting oil in the water accumulated in the second drainage pit. The drainage pump equipment further comprises a third drainage pump disposed in the first drainage pit for sending water from the first drainage pit to the second drainage pit, the third drainage pump having a smaller discharge amount per predetermined time into the second drainage pit than the first and second drainage pumps, and the third drainage pump starts before the first and second drainage pumps. In the case of a hydroelectric power plant, the power plant equipment is, for example, a water turbine. The first drainage pit is, for example, a drainage pit located at the bottom of the power plant building. The second drainage pit is, for example, a drainage pit located outdoors. The drainage destination is, for example, a river, pond, lake, or sea.

[0009] In this way, a third drainage pump with a lower discharge volume per given time than the other two drainage pumps is provided as a pump for transporting water from the first drainage pit to the second drainage pit, and by starting this third drainage pump first, the discharge volume per given time from the first drainage pit to the second drainage pit at the beginning of drainage can be reduced, making it less likely that the water surface in the second drainage pit will be stirred up unintentionally, and preventing malfunction of the oil detection device floating on the water surface of the second drainage pit.

[0010] The drainage pump facility of the present invention is characterized in that the first drainage pit has a second water level detection device different from the first water level detection device, and the second water level detection device detects when the water level in the first drainage pit reaches a second standard that is shallower than the predetermined standard used by the first water level detection device, and prompts the third drainage pump to start. The first water level detection device is, for example, a wire-type float.

[0011] In this way, it is possible to use a second water level detection device separate from the first water level detection device as a water level detection device that detects when the water level in the first drainage pit has reached a predetermined standard and prompts the third drainage pump to start up, thereby increasing the freedom of the device selected as the second water level detection device.

[0012] Furthermore, in the drainage pump equipment of the present invention, the second water level detection device is characterized in that a float is attached to the tip of a linear member suspended from above the first drainage pit toward the accumulated water, and the second water level detection device detects that the water accumulated in the first drainage pit has reached the second standard by displacement of the float, and prompts the third drainage pump to start. The second water level detection device is, for example, a hanging float switch.

[0013] In this way, by using a device such as a hanging float switch as the second water level detection device, the reliability of the detection device can be increased compared to when a wire-type float is used, making it possible to increase the certainty of starting the third drainage pump first out of the three drainage pumps. [Effects of the Invention]

[0014] As described above, according to the drainage pump equipment of the present invention, a third drainage pump having a smaller discharge volume per given time than the other two drainage pumps is provided as a pump for transporting water from the first drainage pit to the second drainage pit, and by starting this third drainage pump first, the discharge volume per given time from the first drainage pit to the second drainage pit can be reduced at the beginning of drainage, which makes it difficult for the water surface in the second drainage pit to be inadvertently stirred, thereby making it possible to prevent malfunction of an oil detection device floating on the water surface of the second drainage pit.

[0015] In particular, according to the drainage pump equipment of the invention of claim 2, it is possible to use a second water level detection device separate from the first water level detection device as a water level detection device that detects when the water level in the first drainage pit has reached a predetermined standard and prompts the third drainage pump to start up, thereby increasing the freedom of the device selected as the second water level detection device.

[0016] In particular, according to the drainage pump equipment of the invention defined in claim 3, the water level detection device for the third drainage pump is a hanging float switch type that is hung from above the first drainage pit, so as long as a place for hanging can be secured, it can be installed without using special holes or tools, etc. Moreover, since it is possible to avoid the wire from becoming twisted or kink when using, for example, a wire-type float as the second water level detection device, it is possible to increase the reliability of the water level detection device. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a schematic diagram showing an example of the configuration of a hydroelectric power plant and an example of the configuration of a drainage pump facility that the hydroelectric power plant has. [Figure 2] FIG. 2 is an enlarged view showing a first drainage pit of the drainage pump facility and devices such as a drainage pump installed around the first drainage pit. [Figure 3]FIG. 3 is a diagram of a control circuit for controlling three drainage pumps. [Figure 4] FIG. 4 is a perspective view of a hanging float switch that constitutes a water level detection device for the third drainage pump. [Figure 5] Figure 5 shows the operation of a hanging float switch, where (a) shows the state when the switch is turned ON, and (b) shows the state when the switch is turned OFF. [Figure 6] FIG. 10 is a diagram showing a wire float that constitutes a water level detection device for the first and second drainage pumps. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0019] Figures 1 and 2 show an example of the schematic configuration of a hydroelectric power plant to which the present invention can be applied, and an example of drainage pump equipment having, for example, a drainage pit 1 located at the deepest position of the hydroelectric power plant and a drainage pit 9 located outdoors.

[0020] 1, the hydroelectric power plant has a water turbine generator 100 equipped with equipment such as a generator and a water turbine, and the water turbine generator 100 is configured by connecting the shafts of the generator and the water turbine. In this embodiment, the water turbine generator 100 is installed on the floor surface 101a of the water turbine room 101.

[0021] In this embodiment, as shown in Fig. 1, there is a space 103 below the turbine chamber 101, and a pipe 104 extending from the bottom of the turbine generator 100 into the space 103 passes through the space 103 and connects to the drainage pit 1, allowing water leaking from the turbine of the turbine generator 100 to flow into the drainage pit 1. Motors 5a, 5b, and 5c for driving drainage pumps 2, 3, and 4, which will be described below, are installed on a top plate 1b of the turbine chamber 101 located above the drainage pit 1 and connected to the floor surface 101a. These motors 5a, 5b, and 5c are controlled by control signals S1, S2, and S3 sent from a drainage pump control circuit 60 (details of which are shown in Fig. 3) housed in the switchboard 6 of Fig. 2, as will be described later.

[0022] As shown in Figures 1 and 2, drainage pit 1 is equipped with drainage pump 2, drainage pump 3, and drainage pump 4, which will be described later, to send (drain) the water that has accumulated in drainage pit 1 to drainage pit 9 located outside the hydroelectric power plant.

[0023] In this embodiment, drainage pump 2 is used as a regular drainage pump, and drainage pump 3 is used as a standby drainage pump. When the water level in drainage pit 1 detected by water level detection device 200 shown in FIG. 6 reaches Reference 1 (described below), a control signal S1 is sent to motor 5a to start drainage pump 2. When the water level in drainage pit 1 is detected to fall below Reference 4 (described below), a control signal S1 is sent to motor 5a to stop drainage pump 2. Furthermore, when the water level in drainage pit 1 detected by water level detection device 200 reaches Reference 2 (described below), a control signal S2 is sent to motor 5b to start drainage pump 3. When the water level in drainage pit 1 is detected to fall below Reference 4, a control signal S2 is sent to motor 5b to stop drainage pump 3.

[0024] In this embodiment, water pumped up from drainage pit 1 by operation of drainage pump 2 is discharged into drainage pit 9 via drainage path 80. In this embodiment, water pumped up from drainage pit 1 by operation of drainage pump 3 joins drainage path 80 from drainage path 81 and is then discharged into drainage pit 9. A plurality of valves 80a, 80b are arranged in drainage path 80 to prevent backflow, for example, when inspecting drainage pump 2, and a plurality of valves 81a, 81b are arranged in drainage path 81 to prevent backflow, for example, when inspecting drainage pump 3.

[0025] In this embodiment, the water level detection device 200 is a wire float. That is, as shown in Fig. 6, the water level detection device 200 has a main body fixed to the top plate 1b of the drainage pit 1, a weight 205, and a drum 203. A wire 202 is wound around the drum 203, and a float 201 is fixed to the tip of this wire 202, and the float 201 floats on the surface of the water accumulated in the drainage pit 1.

[0026] The float 201 moves up and down as the drum 203 rotates in conjunction with the up and down fluctuations of the water level accumulated in the drainage pit 1, and the wire 202 is wound up and pulled out. A tube 201a surrounding the float 201 is arranged around the float 201, with a length from the bottom surface 1a of the drainage pit 1 to near the underside 1c of the top plate 1b. The water level detection device 200 is connected to the drainage pump control circuit 60 in the distribution board 6.

[0027] As a result, when the water level detection device 200 detects that the water level in the drainage pit 1 has reached a predetermined standard (the aforementioned standards 1 and 2) due to the up and down movement of the float 201, it outputs a signal S4 to the drainage pump control circuit 60, as shown in Figure 2.

[0028] The drainage pump 4 has a smaller discharge volume per given time than the drainage pumps 2 and 3 described above, and may be installed later in addition to the existing drainage pumps 2 and 3. When the water level in the drainage pit 1 detected by a water level detection device 20 different from the water level detection device 200 described above is detected to have reached standard 3 (described below), a control signal S3 is sent to the motor 5c to start the drainage pump 4, and when the water level in the drainage pit 1 is detected to have dropped below standard 4, a control signal S3 is sent to the motor 5c to stop the drainage pump 3.

[0029] In this embodiment, water pumped up from the drainage pit 1 by the operation of the drainage pump 4 is discharged into the drainage pit 9 via a drainage path 82 that is completely independent of the drainage paths 80 and 81. A plurality of valves 82a and 82b are arranged in the drainage path 82 to prevent backflow, for example, when inspecting the drainage pump 4.

[0030] In this embodiment, the water level detection device 20 is a hanging float switch. That is, as shown in Fig. 4, the water level detection device 20 is composed of, for example, a cable 24 having one end fixed to the top plate 1b of the drainage pit 1 and extending from a gap in the top plate 1b toward the bottom surface 1a of the drainage pit 1, a support 23 supporting the other end of the cable 24, a cable 22 extending from the support 23, and a float switch 21 provided at the end of the cable 22 in the extending direction. The length of the cable 24 hanging down from the top plate 1b can be adjusted to an appropriate dimension, and the end of the cable 24 opposite the support 23 is connected to the control circuit 60 of the distribution board 6.

[0031] As shown in FIG. 5, float switch 21 of water level detection device 20 contains movable weight 21a. As float switch 21 rises and sinks, movable weight 21a moves toward the connection side with cable 24 or away from the connection side with cable 24, thereby turning the switch on and off. That is, float switch 21 containing movable weight 21a itself functions as a switch. When the water level in drainage pit 1 rises to standard 3, it turns on as a switch. A signal S5 (shown in FIG. 2) indicating this ON state is transmitted to drainage pump control circuit 60 housed in control panel 6. Then, control signal S3 is transmitted from drainage pump control circuit 60 to motor 5c, starting motor 5c. This also starts drainage pump 4, which drains the water accumulated in drainage pit 1 into drainage pit 9 through drainage path 82. In this embodiment, criterion 3 for starting drainage pump 4 is set to a water level value that is shallower from the bottom of drainage pit 1 than criterion 1 for starting drainage pump 2 or criterion 2 for starting drainage pump 3, but the details of these criteria will be described later.

[0032] The operation of the water level detection device 20, which is a hanging float switch, will be described in more detail with reference to FIG.

[0033] Figure 5(a) shows the state in which float switch 21 of water level detection device 20 changes from an OFF state to an ON state. That is, at position A indicated by the initial solid line, float switch 21 is floating on water surface 25 where the water level from bottom surface 1a of drainage pit 1 is at lower limit water level H1, and cable 22 hangs down below support 23. In this case, movable weight 21a is at the end (hereinafter referred to as the tip) of float switch 21 opposite the attachment position of cable 22, and the switch is OFF. When the water level in drainage pit 1 rises above lower limit water level H1, float switch 21, which is floating on the water surface, also rises along with the rise in water level while floating on the water surface, and first reaches position B indicated by the dashed line, which is below support 23. Next, as the water level in the drainage pit 1 continues to rise, the float switch 21 rises to position C, indicated by the dashed line, which is approximately the same position as the support 23, and then to position D, indicated by the two-dot chain line, which are positions higher than the support 23, and to position E, indicated by the dashed line, until it reaches position F, indicated by the dashed line, where the float switch 21 floats on the water surface 26 where the water level from the bottom surface 1a of the drainage pit 1, set as reference 3, is at upper water level H2. As the float switch 21 rises in this manner, due to the relationship between the support 23 and the wire 22, it is displaced so that its tip points upward in the range from position C to position F. As a result, at position F, the tip is directly upward, and the movable weight 21a inside the float switch 21 has moved all the way to the connection side with the cable 22, which comes into contact with and magnetizes a magnet (not shown) inside the float switch 21, turning the switch ON.

[0034] 5(b) shows the float switch 21 of the water level detection device 20 changing from an ON state to an OFF state. That is, at the initial position A indicated by the solid line, where the float switch 21 floats on the water surface 26 where the water level from the bottom surface 1a of the drainage pit 1 is at the upper limit water level H2, the tip of the float switch 21 faces directly upward, so the movable weight 21a inside the float switch 21 is on the connection side (opposite the tip) with the cable 22, and the switch is in the ON state. Even if the water level in the drainage pit 1 drops below the upper limit water level H2, in the case of position B indicated by the dashed line, where the float switch 21 is above the support 23, or position C indicated by the dashed line, where the float switch 21 is substantially at the same level as the support 23, in this embodiment, the tip of the float switch 21 remains facing directly upward, so the movable weight 21a inside the float switch 21 remains on the connection side (opposite the tip) with the cable 22, and the switch is maintained in the ON state. When the water level in the drainage pit 1 drops further and the float switch 21 reaches position D, indicated by the two-dot chain line, which is at least lower than the support 23, the tip of the float switch 21 begins to point downward due to the relationship between the support 23 and the cable 22. Then, when the water level in the drainage pit 1 drops further and the float switch 21 passes through position E, indicated by the dashed line, from position D and reaches position F, indicated by the one-dot chain line, where the water level from the bottom surface 1a of the drainage pit 1, set as standard 4, is at the water surface 25, which is at the lower limit water level H1, the tip of the float switch 21 will point straight down. As a result, the movable weight 21a moves all the way to the tip side of the float switch 21, separates from the magnet, and loses its magnetic force, turning the switch OFF.

[0035] From drainage pit 9 located outside the hydroelectric power plant, water flows further outside (for example, into a river or the sea) as shown by the arrow in Fig. 1. Accordingly, in this embodiment, an oil detection device 8 floats on the water surface as shown in Figs. 1 and 2 to detect whether the water flowing outside contains oil. Accordingly, in this embodiment, an oil removal device (not shown) for removing oil detected by oil detection device 8 is installed, for example, in drainage pit 9. However, the oil removal device may be installed in drainage pit 1, or in both drainage pits 1 and 9.

[0036] Next, an example of the drainage pump control circuit 60 housed in the control panel 6 will be described with reference to FIG.

[0037] The control circuits 60 for each of the drainage pumps 2, 3, and 4 are located between the power supply lines P and N, which are the control bus bars. From the right in Fig. 3, they are circuits 61, 62, and 63 that control the drainage pump 4, drainage pump 3, and drainage pump 2. The control circuit 61 for the drainage pump 4 is connected to the motor 5c, the control circuit 62 for the drainage pump 3 is connected to the motor 5b, and the control circuit 62 for the drainage pump 2 is connected to the motor 5a.

[0038] The circuit 61 that controls the drainage pump 4 on the right side of Fig. 3 is a pair of automatic control circuit 61a and manual control circuit 61b. When testing the drainage pump 4, turning on the manual switch 613 of the control circuit 61 of the drainage pump to be tested and pressing the push button switch 614 operates the relay 617, which in turn turns on the relay contact 614a, allowing the drainage pump 4 to operate continuously. Pressing the b-contact push button switch 615 stops the drainage pump 4, and the drainage pump 4 can also be tested manually, but in the present invention, further explanation of the manual case will be omitted.

[0039] The automatic control circuit 61a is composed of an automatic switch 610, terminals 611a, 611b, 611c, a limit switch 612, a relay contact 612a, an oil leakage detection switch 616 with a b-contact, a relay 617, and a drainage pump failure detection switch 618 with a b-contact. The limit switch 612 is connected to a water level detection device (wire-type float) 200 and constitutes an automatic control circuit similar to that of the drainage pump 3 described below, but as shown in Fig. 3, a water level detection device (hanging float switch) 20 is connected to terminals 611b and 611c, and the limit switch 612 and the automatic control circuit of the relay contact 612a are not used, so terminals 611a and 611b are directly connected by wiring.

[0040] When the water level of the water 1d in the drainage pit 1 rises and reaches a set standard 3 (for example, the upper limit water level H2, i.e., a water level 1.2 m above the bottom surface 1a of the drainage pit 1), the float switch 21 of the water level detection device 20 turns ON, and a signal S5 indicating that it has turned ON is sent to the control circuit 60 (61), which activates the relay 617. This conduction starts the motor 5c, which starts the drainage pump 4 and drains the water. When the water level of the water 1d in the drainage pit 1 drops and reaches standard 4 (for example, a water level 60 cm above the bottom surface 1a of the drainage pit 1), the drainage pump 4 stops. Note that the automatic switch 610 is normally ON, so that the drainage pump 4 starts or stops automatically when the water in the drainage pit 1 reaches the set water level.

[0041] The circuit 63 that controls the drainage pump 2, shown on the left side of Fig. 3, is a pair of an automatic control circuit 63a and a manual control circuit 63b. When testing the drainage pump 2, the manual switch 634 of the control circuit 63 of the drainage pump to be tested is turned ON, and the push button switch 635 is pressed, which operates the relay 638, which in turn turns ON the relay contact 635a, allowing the drainage pump 2 to operate continuously. The drainage pump 2 is stopped by pressing the b-contact push button switch 636, and the drainage pump 2 can also be tested manually; however, in the present invention, further explanation of the manual case will be omitted.

[0042] The automatic control circuit 63a is composed of an automatic switch 630, terminals 631a, 631b, 631c, a limit switch 632, a relay contact 632a, a limit switch 633, a b-contact oil leakage detection switch 637, a relay 638, and a b-contact drainage pump failure detection switch 639. The limit switches 632 and 633 are connected to the water level detection device (wire-type float) 200.

[0043] When the water level in the drainage pit 1 reaches standard 4 (for example, a water level 60 cm from the bottom surface 1c of the drainage pit 1), which is the previous stage of the set standard 1, limit switch 633 turns on, and drainage pump 2 enters standby mode. If the water level continues to rise and reaches set standard 1 (for example, a water level 1.4 m from the bottom surface 1a of the drainage pit 1), water level detection device (wire-type float) 200 sends signal S4 to control circuit 60 (63) indicating that the water level has reached standard 1, limit switch 632 and relay 638 operate, relay contact 632a turns ON in conjunction with each other, and this conduction operates motor 5a, starting drainage pump 2 and draining water. If the water level in the drainage pit 1 drops and reaches standard 4 (for example, a water level 60 cm from the bottom surface 1a of the drainage pit 1), limit switch 633 turns OFF, and drainage pump 2 stops. The automatic switch 630 is normally ON, and when the water level in the drainage pit 1 reaches a set standard, the drainage pump 2 starts or stops automatically.

[0044] The circuit 62 that controls the drainage pump 3 shown in the center of Figure 3 is a pair of automatic control circuit 62a and manual control circuit 62b. When testing the drainage pump 3, turning on the manual switch 624 of the control circuit 62 of the drainage pump to be tested and pressing the push button switch 625 operates the relay 628, which in turn turns on the relay contact 625a, allowing the drainage pump 3 to operate continuously. Pressing the b-contact push button switch 626 stops the drainage pump 3, and the drainage pump 3 can also be tested manually; however, in the present invention, further explanation of the manual method will be omitted.

[0045] Like the automatic control circuit 63a of the circuit 63 that controls the drainage pump 2, the automatic control circuit 62a of the circuit 62 that controls the drainage pump 3 is also composed of an automatic switch 620, terminals 621a, 621b, 621c, a limit switch 622, a relay contact 622a, a limit switch 623, a b-contact oil leakage detection switch 627, a relay 628, and a b-contact drainage pump failure detection switch 629. The limit switches 622 and 623 are connected to the water level detection device (wire-type float) 200.

[0046] When the water level in the drainage pit 1 reaches Reference Value 4 (e.g., a water level 60 cm above the bottom surface 1a of the drainage pit 1), which is the previous stage of the set Reference Value 2, limit switch 623 turns on, and drainage pump 3 enters standby mode. If the water level continues to rise and reaches Set Reference Value 2 (e.g., a water level 1.6 m above the bottom surface 1a of the drainage pit 1), a signal indicating that the water level has reached Reference Value 2 is sent from water level detection device (wire float) 200 to drainage pump control circuit 60 (62), which activates limit switch 622 and relay 628, turning relay contact 622a ON in conjunction with each other. This conduction activates motor 5b, which starts drainage pump 3 and drains water. If the water level in the drainage pit 1 drops and reaches Reference Value 4 (e.g., a water level 60 cm above the bottom surface 1a of the drainage pit 1), limit switch 623 turns off, and drainage pump 3 stops. The automatic switch 620 is normally ON, and when the water level in the drainage pit 1 reaches a set standard, the drainage pump 3 starts or stops automatically.

[0047] Furthermore, when the water level of the drainage pumps 2, 3, and 4 drops to standard 4 (for example, a water level of 60 cm from the bottom surface 1a of the drainage pit 1), which is set as the lower limit water level (for example, lower limit water level H1 in Figure 5) from the bottom surface 1b of the drainage pit 1, the control circuit 60 causes the limit switches 633 and 623 of each circuit 61, 62, and 63, which were previously conducting, to stop conducting, and as a result, the relays 617, 638, and 628 also stop, and the drainage pumps 2 and 3 stop.

[0048] The control circuit 60 (61, 62, 63) described above is configured so that the drainage pump 4 starts when the water level reaches 1.2 m from the bottom surface 1 a of the drainage pit 1, the drainage pump 2 starts when the water level reaches 1.4 m from the bottom surface 1 a of the drainage pit 1, and the drainage pump 3 starts when the water level reaches 1.6 m from the bottom surface 1 a of the drainage pit 1. This makes it possible to start the drainage pump 4 first among the drainage pumps 2, 3, and 4. Accordingly, by using a drainage pump with a lower discharge volume per predetermined time than the drainage pumps 2 and 3 as the drainage pump 3 and by using a float switch as the water level detection device 20 to prompt the start of the drainage pump 3, it is possible to prevent the water surface of the drainage pit 9 from being inadvertently stirred up when the drainage pump 3, which was started first and reliably, discharges water from the drainage pit 1 to the drainage pit 9, thereby preventing the oil detection device 8 from malfunctioning.

[0049] In the present invention, three drainage pumps (drainage pumps 2, 3, and 4) have been described, but the number is not limited to three as long as drainage pump 4, which is started first, starts reliably.

[0050] Furthermore, the specific standards 1 to 5 for the water level of the drainage can be changed to values ​​appropriate to the situation, environment, etc., and are not limited to the values ​​indicated in the present invention.

[0051] Furthermore, in the present invention, an example has been given in which a hanging float switch is used as the water level detection device 200, but a water level detection device with a different structure may be used as long as it can achieve the same effect as the present invention. [Explanation of symbols]

[0052] 1 Drainage pit (first drainage pit) 2 Drainage pump (first drainage pump) 3 Drainage pump (second drainage pump) 4. Drainage pump (third drainage pump) 60 Drainage pump control circuit 8 Oil detection device 9 Drainage pit (second drainage pit) 20 Hanging float switch (second water level detection device) 80 Drainage route 81 Drainage route 82 Drainage route 200 Wire type float (first water level detection device)

Claims

1. a first drainage pit for storing water from equipment in a power plant; a second drainage pit arranged in a drainage path from the first drainage pit to a drainage destination for storing water from the first drainage pit; a first drainage pump arranged in the first drainage pit for sending water from the first drainage pit to the second drainage pit; a second drainage pump arranged in the first drainage pit for sending water from the first drainage pit to the second drainage pit, the second drainage pump being different from the first drainage pump; a first water level detection device for detecting when the level of water accumulated in the first drainage pit has reached a predetermined standard and prompting the first and second drainage pumps to start; and an oil detection device installed in the second drainage pit for detecting oil in the water accumulated in the second drainage pit, A drainage pump facility characterized in that a third drainage pump, which has a smaller discharge volume per specified time into the second drainage pit than the first and second drainage pumps, is further placed in the first drainage pit as a pump for transporting water from the first drainage pit to the second drainage pit, and the third drainage pump starts up before the first and second drainage pumps.

2. The drainage pump equipment described in claim 1, characterized in that the first drainage pit has a second water level detection device different from the first water level detection device, and the second water level detection device detects when the water level in the first drainage pit reaches a second standard that is shallower than the predetermined standard used in the first water level detection device, and prompts the third drainage pump to start up.

3. The drainage pump equipment described in claim 2, characterized in that the second water level detection device has a float attached to the tip of a linear member suspended from above the first drainage pit toward the accumulated water, and detects that the water accumulated in the first drainage pit has reached the second standard by displacement of the float, and prompts the third drainage pump to start.

Images