JP7601724B2 - Pump monitoring method and monitoring device - Google Patents

Description

The present invention relates to a pump monitoring method and a monitoring device.

The vertical shaft pump disclosed in Patent Document 1 includes a submerged bearing that rotatably supports the rotating shaft inside the pump casing, and a monitoring device outside the pump casing that monitors the wear condition of the submerged bearing. The monitoring device includes a supply mechanism that supplies fluid between the rotating shaft and the submerged bearing, a differential pressure detection unit that detects the differential pressure between the fluid pressure supplied by the supply mechanism and the internal pressure of the pump casing, and a control unit that detects the amount of wear of the submerged bearing based on the detection result of the differential pressure detection unit.

Patent No. 4819028

Detecting wear in underwater bearings using the monitoring device in Patent Document 1 requires testing of multiple underwater bearings individually and in sequence, so inspecting the entire pump requires at least one day (usually two days). Because the pump cannot be operated during this inspection work, there is room for improvement in time-planned maintenance management, which involves inspections at set intervals.

The objective of the present invention is to reduce the period during which the pump is unable to operate due to maintenance management.

One aspect of the present invention provides a pump monitoring method in which vibrations of a drainage mechanism that discharges water from a suction tank are detected by a vibration detection unit, and whether or not wear detection is necessary for the underwater bearing that constitutes the drainage mechanism is determined based on the detection result of the vibration detection unit, and if it is determined that wear detection is necessary, fluid is supplied between the underwater bearing and the rotating shaft by a supply mechanism, the amount of wear of the underwater bearing is determined based on the detection result of a differential pressure detection unit that detects the differential pressure between the fluid pressure supplied by the supply mechanism and the internal pressure of the pump casing , and if the amount of wear is equal to or greater than a set gap alarm value, an alarm is issued by an alarm unit to advise preparations for replacement of the underwater bearing, and if the amount of wear is less than the gap alarm value, an alarm is issued by the alarm unit to advise the possibility of an abnormality other than the underwater bearing .

Another aspect of the present invention is a pump monitoring device that includes a pump casing, a rotating shaft with an impeller attached to a portion located within the pump casing, and a drainage mechanism that has a submersible bearing that rotatably supports the rotating shaft and drains water from a suction tank, the device comprising: a vibration detection unit that detects vibrations of the drainage mechanism; a supply mechanism that supplies fluid between the rotating shaft and the submersible bearing; a differential pressure detection unit that detects the differential pressure between the fluid pressure supplied by the supply mechanism and the internal pressure of the pump casing; a control unit that determines whether wear detection is necessary for the submersible bearing based on the detection result of the vibration detection unit, and if it determines that wear detection is necessary, drives the supply mechanism and determines the amount of wear of the submersible bearing based on the detection result of the differential pressure detection unit ; and an alarm unit for alerting an abnormality in the drainage mechanism , wherein if the amount of wear is equal to or greater than a set gap warning value, the control unit issues an alarm via the alarm unit to encourage the user to prepare to replace the submersible bearing, and if the amount of wear is less than the gap warning value, the alarm unit issues an alarm to encourage the user to detect the possibility of an abnormality other than the submersible bearing .

Since the vibration of the drainage mechanism increases as the wear of the underwater bearing progresses, the amount of wear of the underwater bearing can be predicted (identified) from the detection results of the drainage mechanism during drainage operation. Therefore, by only performing actual wear detection when it is determined that wear detection of the underwater bearing is necessary based on vibration detection of the drainage mechanism, the number of times wear detection of the underwater bearing, which requires a long work process, can be reduced. As a result, the period during which the pump is unable to operate due to maintenance management can be reduced.

This invention can reduce the period during which the pump is unable to operate due to maintenance management.

1 is a cross-sectional view showing a pump facility using a monitoring device according to an embodiment of the present invention. FIG. 4 is a cross-sectional view showing a state in which the drainage mechanism is removed from the pump casing. FIG. 2 is an enlarged cross-sectional view of part III in FIG. 1 . Block diagram of pump equipment. 1 is a graph showing the relationship between the gap of an underwater bearing and the rotation speed of a rotating shaft. 13 is a graph showing the relationship between the clearance of the underwater bearing and the vibration of the drainage mechanism. 1 is a graph showing the wear tendency of a submerged bearing when the slurry concentration is different. 11 is a flowchart of a setting process performed when a pump facility is newly installed. 5 is a flowchart of equipment monitoring processing by a control unit. 9B is a continuation of the flowchart of FIG. 9A.

The following describes an embodiment of the present invention with reference to the drawings.

Figures 1 and 2 show a pump facility equipped with a vertical pump (hereinafter abbreviated as "pump") 10 using a monitoring device 60 according to an embodiment of the present invention. The monitoring device 60 is configured to detect vibrations of a drainage mechanism 40 equipped in the pump 10 attached to an installation floor 1, and to detect the amount of wear of the submerged bearing 56 equipped in the drainage mechanism 40 only when it is determined that wear detection of the submerged bearing 56 equipped in the drainage mechanism 40 is necessary (condition monitoring maintenance).

First, the configuration of the pump 10 will be described with reference to Figures 1 and 2.

The pump 10 comprises a pump casing 20 that forms a drainage channel, and a drainage mechanism 40 for discharging water (liquid) in the suction tank 2 downstream through the pump casing 20. The drainage mechanism 40 comprises a rotating shaft 42, an impeller 48, and an underwater bearing 56. The pump 10 of this embodiment is a pull-out type that allows the drainage mechanism 40 to be removed from the pump casing 20.

(Pump casing configuration)
1 and 2, the pump casing 20 is inserted from above into the through hole 1a of the installation floor 1 and fixed to the installation floor 1. The pump casing 20 is cylindrical as a whole and includes a lifting pipe 21 disposed in the suction tank 2 and a discharge pipe 25 disposed on the installation floor 1. A motor stand 30 is further removably attached to the upper side of the discharge pipe 25.

The lift pipe 21 hangs vertically from the installation floor 1 into the suction tank 2. The lift pipe 21 includes a lift pipe body 22, a vane case 23, and a bell mouth 24, which are connected in this order from top to bottom. The lift pipe body 22 is a straight pipe, and the overall length of the lift pipe 21 can be changed by changing the overall length or number. Inside the vane case 23, a plurality of support plates 23a that support the bowl bush 54 described later are provided at intervals in the circumferential direction. The bell mouth 24 is a conical cylinder that gradually widens from the upper end to the lower end. The lower end of the bell mouth 24 is an intake port 24a that draws in water from the suction tank 2, and is disposed at an interval from the bottom of the suction tank 2 (not shown).

The discharge pipe 25 has a delivery bend 26 connected to the upper end of the lift pipe 21. The delivery bend 26 has a first straight pipe section 27 that extends vertically along the axis of the lift pipe 21, and a second straight pipe section 28 that extends horizontally. The inside of the first straight pipe section 27 and the inside of the second straight pipe section 28 are spatially connected, and the pumped water flows in from the lower end of the first straight pipe section 27 and flows out from the discharge port 28a of the second straight pipe section 28.

The upper end of the first straight pipe section 27 is a circular opening 27a. The center of the opening 27a is located on the axis of the lift pipe 21, and the diameter of the opening 27a is larger than the outer shape of the impeller 48 when the rotating shaft 42 is viewed in the axial direction.

A base plate 29 for fixing to the installation floor 1 is provided at the bottom of the first straight pipe section 27. However, the base plate 29 may also be provided at the top of the lift pipe body 22.

The motor stand 30 is attached to the upper end of the first straight pipe section 27 by bolting and includes a closure plate 31 that closes the opening 27a. The motor stand 30 also includes a cylindrical first frame section 32 that surrounds the closure plate 31, a partition plate 33 attached to the upper end of the first frame section 32, a cylindrical second frame section 34 attached to the upper side of the partition plate 33, and an end plate 35 attached to the upper end of the second frame section 34. The motor stand 30 further includes a guide plate 36 that is disposed within the first straight pipe section 27 and guides the pumped water that has flowed into the first straight pipe section 27 to the second straight pipe section 28.

An electric drive motor 37 is attached to the end plate 35. The output shaft of the drive motor 37 passes through the end plate 35 and is disposed between the end plate 35 and the partition plate 33 so that its axis is aligned in the same line as the axis of the lift pipe 21.

The closure plate 31 has a through hole through which the rotating shaft 42 passes, and this through hole is blocked by the base of the shaft seal device 38. The shaft seal device 38 provides a watertight seal between the rotating shaft 42 and the closure plate 31.

(Configuration of drainage mechanism)
1 and 2, the drainage mechanism 40 includes the rotating shaft 42, the impeller 48, and the underwater bearing 56 as described above. The drainage mechanism 40 also includes a suspension pipe (inner cylinder) 50 that surrounds the rotating shaft 42, and a bowl bush 54 that prevents the impeller 48 from whirling is attached to the suspension pipe 50. The underwater bearing 56 is attached to the suspension pipe 50 and the bowl bush 54, respectively.

The rotating shaft 42 passes through the motor stand 30 and is arranged along the axis of the pumping pipe 21. The rotating shaft 42 has an inner part 42a arranged inside the pump casing 20 and an outer part 42b arranged inside the motor stand 30. In this embodiment, the rotating shaft 42 is composed of multiple shaft members 43 (three in this embodiment) and shaft couplings 44 that connect adjacent shaft members 43.

The lower end of the inner part 42a passes through the bowl bush 54 and is disposed between the bowl bush 54 and the suction port 24a. The upper end of the outer part 42b is disposed between the partition plate 33 and the end plate 35 of the motor stand 30, and is mechanically connected to the output shaft of the drive motor 37 via a coupling 45. The outer part 42b is supported by a rolling bearing 46 disposed on the partition plate 33.

The impeller 48 is disposed below the bowl bush 54 and is attached to the lower end of the inner portion 42a of the rotating shaft 42. The outer shape of the impeller 48 when viewed from the axial direction of the rotating shaft 42 is smaller than the diameter (outer shape) of the opening 27a. When the rotating shaft 42 is rotated by the drive motor 37, the impeller 48 rotates integrally with the rotating shaft 42 and discharges water from the suction tank 2 downstream through the pump casing 20.

The hanging pipe 50 extends downward from the motor base 30 and surrounds the inner portion 42a of the rotating shaft 42 above the bowl bush 54 (impeller 48). The hanging pipe 50 is attached to the motor base 30 by bolting. More specifically, the hanging pipe 50 is bolted to the base of the shaft seal device 38, and the base is bolted to the closure plate 31.

The suspension pipe 50 of this embodiment is composed of multiple (two) cylinders 51 and a cylindrical connecting member 52 that connects adjacent cylinders 51. The upper end of the uppermost cylinder 51 is attached to the base (closure plate 31) of the shaft seal device 38 by bolting as described above. The lower end of the lowermost cylinder 51 is connected to the bowl bush 54 via the connecting member 52. The connecting member 52 is composed of a holder that holds the underwater bearing 56.

The bowl bush 54 has a generally elliptical cylindrical shape smaller than the outer shape of the impeller 48 when viewed in the axial direction of the rotating shaft 42, and can be inserted and removed through the opening 27a of the pump casing 20. When attached to the inside of the pump casing 20, the bowl bush 54 is supported by the support plate 23a and is arranged coaxially within the vane case 23. This makes it possible to suppress whirling of the impeller 48 arranged below the bowl bush 54.

The underwater bearing 56 is attached to the two connecting members 52 of the hanging tube 50 and the insertion portion 54a of the bowl bush 54, and rotatably supports the rotating shaft 42. The underwater bearing 56 has a cylindrical sliding member 57 that slides against the outer circumferential surface of the rotating shaft 42.

Referring to FIG. 3, the sliding member 57 has a communication hole 57a penetrating in the radial direction. The communication hole 57a is in spatial communication with the connection port 52a of the connection member 52. The sliding member 57 arranged in the bowl bush 54 also has a communication hole, which is in communication with the connection port of the insertion part 54a. This allows compressed air supplied from a supply mechanism 63 (described later) to be supplied between the sliding member 57 (underwater bearing 56) and the rotating shaft 42 through the connection port 52a and the communication hole 57a.

During normal drainage operation, clean water (clean water) may be poured into the suspension pipe 50 as a lubricating liquid for the submerged bearing 56. By supplying lubricating liquid between the submerged bearing 56 and the rotating shaft 42, it is possible to prevent them from seizing and to suppress wear of the submerged bearing 56. The suspension pipe 50 used in this manner is also called a protective pipe, and separates the internal lubricating liquid from the external pumped water. However, the suspension pipe 50 may be provided with a number of water holes through which pumped water can flow in without injecting lubricating liquid.

Referring to Figures 1 and 2, in the drainage mechanism 40 configured in this manner, the internal piping 74 described below penetrates the motor base 30 and is arranged inside the pump casing 20 along the rotating shaft 42 and is integrated with it.

As shown in Figure 2, when the rotating shaft 42 and the drive motor 37 (see Figure 1) are disconnected, the axial movement of the rotating shaft 42 including the impeller 48 is restricted by the underwater bearing 56, the movement of the underwater bearing 56 is restricted by its attachment to the connecting member 52 (suspension tube 50), the movement of the suspension tube 50 is restricted by its attachment to the motor stand 30, and the movement of the internal piping 74 is restricted by its connection to the connecting member 52 (underwater bearing 56).

Therefore, when the discharge pipe 25 and the motor base 30 are disconnected by removing the bolts, the drainage mechanism 40 can be removed from the pump casing 20 together with the internal piping 74 through the opening 27a by lifting any of the motor base 30, the rotating shaft 42, the hanging pipe 50, and the internal piping 74. At this time, the pump casing 20 remains fixed to the installation floor 1 and does not need to be disassembled.

However, if the ceiling (height) of the building including the installation floor 1 is lower than the overall height of the drainage mechanism 40, the drainage mechanism 40 including the internal piping 74 may be divided into multiple compartments in the vertical direction and disassembled in stages.

Next, the monitoring device 60 for the pump 10 will be described with reference to Figures 1 and 4.

(Configuration of monitoring device)
The monitoring device 60 detects the amount of wear in the submersible bearing 56 and determines when to replace it, and monitors abnormalities in the pump 10 caused by factors other than the submersible bearing 56. Specifically, the monitoring device 60 includes a vibration sensor 61 that detects vibrations in the drainage mechanism 40, a wear detection unit 62 that detects wear in the submersible bearing 56, a flow rate detection unit 77 that detects the pump discharge flow rate during drainage operation, and a control unit 80 that controls these.

The vibration value of the drainage mechanism 40 during drainage operation is correlated with the wear amount of the underwater bearing 56, and increases as the wear amount of the underwater bearing 56 increases. In addition, the vibration value of the drainage mechanism 40 during drainage operation is correlated with the pump discharge flow rate, and changes according to changes in the pump discharge flow rate. Therefore, in the monitoring device 60 of this embodiment, the wear amount of the underwater bearing 56 is predicted (identified) based on the detection result by the vibration sensor 61 detected during drainage operation and the detection result by the flow detection unit 77. Then, if the vibration value (identified wear amount) does not exceed the allowable value, the drainage operation is continued, and if the vibration value exceeds the allowable value, the drainage operation is interrupted and the actual wear amount of the underwater bearing 56 is detected by the wear detection unit 62. This reduces the number of times the drainage operation is stopped, and makes it possible to determine abnormalities in the drainage mechanism 40 caused by factors other than the underwater bearing 56.

The configurations of the vibration sensor (vibration detection unit) 61, wear detection unit 62, flow rate detection unit 77, and control unit 80 are described in detail below.

The vibration sensor 61 is a vibration sensor that detects vibrations of the drainage mechanism 40 and outputs the detection results to the electrically connected control unit 80. Any type of vibration sensor can be used as long as it is configured to detect vibrations of the drainage mechanism 40. In this embodiment, the vibration sensor 61 is disposed on the bracket of the rolling bearing 46. In other words, the axial vibration of the drainage mechanism 40 is identified by detecting the bracket vibration of the rolling bearing 46 with the vibration sensor 61. However, vibrations of parts other than the bracket of the rolling bearing 46 may be detected as long as the part indicates a good condition of the drainage mechanism 40.

Here, the vibration of the drainage mechanism 40 is at a minimum at the point of maximum efficiency based on the pump head and efficiency. Both the axial vibration of the drainage mechanism 40 and the bracket vibration of the rolling bearing 46 depend on the pump discharge flow rate, so they change with changes in the pump discharge flow rate and reach a maximum value at the shutoff point. The relationship between the axial vibration of the drainage mechanism 40 and the bracket vibration of the rolling bearing 46 with respect to the pump discharge flow rate is the same. In other words, there is a high correlation between the axial vibration of the drainage mechanism 40 and the bracket vibration of the rolling bearing 46. These correlations can be calculated using a linear approximation even if the pump discharge flow rate is changed. Therefore, by keeping the pump discharge flow rate roughly constant and measuring the bracket vibration of the rolling bearing 46, the change over time in the axial vibration of the drainage mechanism 40 can be estimated.

The wear detection unit 62 includes a supply mechanism 63 that supplies compressed air (fluid) between the rotating shaft 42 and the underwater bearing 56, and a differential pressure sensor (differential pressure detection unit) 75 that detects the differential pressure between the air pressure supplied by the supply mechanism 63 and the internal pressure of the pump casing 20.

The supply mechanism 63 includes a blower 64, a switching valve 65, a constant flow valve 66, and a check valve 67. The supply mechanism 63 further includes a pressure sensor 68 that detects the supply pressure of the blower 64, and a pressure tank 69 that supplements the air supply of the blower 64. The supply mechanism 63 also includes three types of piping 72 to 74.

The blower 64 is driven by commands from the electrically connected control unit 80 and expels air taken in from the outside into the connecting pipe 72.

The switching valve 65 selectively connects one of the multiple underwater bearings 56 to the blower 64 in response to a command from the electrically connected control unit 80. In this embodiment, since three underwater bearings 56 are used, a four-way valve is used for the switching valve 65. One inlet of the switching valve 65 is connected to a connection pipe 72 (blower 64), and the three outlets are each connected to an external pipe 73 (underwater bearings 56). The external pipe 73 is placed on the installation floor 1 and is connected to an internal pipe 74 within the motor stand 30.

The internal pipe 74 is disposed within the pump casing 20 so as to be aligned with the rotating shaft 42. One end (upper end) of the internal pipe 74 is disposed within the motor base 30 through the closure plate 31, and is separably connected to the external pipe 73. The other end (lower end) of the internal pipe 74 is connected to either the connection port 52a of the connection member 52 or the connection port of the bowl bush 54. In other words, the internal pipe 74 in this embodiment is integrated with the drainage mechanism 40 as described above, and is removable from the pump casing 20 together with the drainage mechanism 40.

The constant flow valves 66 are installed in the external piping 73 and keep the flow rate of compressed air supplied to the underwater bearings 56 constant.

The check valves 67 are installed in the external piping 73 downstream of the constant flow valves 66, allowing air to flow from the constant flow valves 66 toward the underwater bearings 56 and preventing air from flowing in the opposite direction.

The pressure sensor 68 is installed in the connection pipe 72 and outputs the detection result (the supply pressure of the blower 64) to the control unit 80.

The pressure tank 69 is connected to a branch of the connecting pipe 72 between the pressure sensor 68 and the switching valve 65. A solenoid valve 70 and a check valve 71 are connected in parallel to the branch pipe. Air discharged by the blower 64 passes through the check valve 71 and is stored in the pressure tank 69 at a set volume. If there is insufficient air supply from the blower 64, the solenoid valve 70, which is closed, is opened by command from the control unit 80, and the air stored in the pressure tank 69 is supplied to the switching valve 65 (submerged bearing 56).

One end of the differential pressure sensor 75 is connected to the connection pipe 72 between the branch connection of the pressure tank 69 and the switching valve 65, and the other end is inserted into a differential pressure measurement pipe 76 that penetrates the base (closure plate 31) and is arranged inside the suspension pipe 50. The differential pressure sensor 75 detects the difference between the supply pressure from the blower 64 to the underwater bearing 56 and the internal pressure of the suspension pipe 50, and outputs the detection result (differential pressure) to the electrically connected control unit 80.

Here, when the gap between the underwater bearing 56 and the rotating shaft 42 is small (when the underwater bearing 56 has little wear), the detection value Ps by the differential pressure sensor 75 is larger than the detection value Ps when the gap between the underwater bearing 56 and the rotating shaft 42 becomes larger. In other words, the detection value Ps by the differential pressure sensor 75 gradually decreases as the underwater bearing 56 wears. Therefore, the amount of wear of the underwater bearing 56 can be determined by comparing the detection value Ps of the differential pressure sensor 75 with a pre-stored data table of wear amounts.

The flow rate detection unit 77 detects the pump discharge flow rate, i.e., the amount of water pumped through the pump casing 20, and outputs the detection result (pump discharge flow rate) to the electrically connected control unit 80. In this embodiment, the flow rate detection unit 77 is composed of a first pressure sensor 78 that detects the pressure above the guide plate 36 within the first straight pipe section 27, and a second pressure sensor 79 that detects the pressure within the second straight pipe section 28.

During drainage operation, the pressure P1 detected by the first pressure sensor 78 is smaller than the pressure P2 detected by the second pressure sensor 79. The pressure difference (P2-P1) depends on the pump discharge flow rate, and increases as the pump discharge flow rate increases. Therefore, the pump discharge flow rate can be determined by comparing the pressure difference (P1-P2) with a pre-stored data table of pump discharge flow rates.

Referring to FIG. 4, the control unit 80 is electrically connected to the drive motor 37, the vibration sensor 61, the blower 64, the switching valve 65, the pressure sensor 68, the solenoid valve 70, the differential pressure sensor 75, the first pressure sensor 78, the second pressure sensor 79, and the notification unit 82. Based on the detection results of the connected sensors 61, 68, 75, 78, and 79, the control unit 80 controls the drive motor 37, the blower 64, the switching valve 65, the solenoid valve 70, and the notification unit 82.

The notification unit 82 is a means for notifying the operator of an abnormal state of the drainage mechanism 40, and includes, for example, audio output, text display on a monitor, and display using a rotating light. The abnormal state of the drainage mechanism 40 may also be configured to be transmitted to a remote centralized control center.

The control unit 80 is configured by a personal computer. The control unit 80 may also be configured by a single or multiple microcomputers and other electronic devices. The control unit 80 includes a memory unit 81 that stores a control program, as well as a data table of judgment values and threshold values used in the control program.

The judgment values stored in the memory unit 81 include a data table of vibration values corresponding to the detection results by the vibration sensor 61 (hereinafter referred to as "vibration measurement value Vmv"), a data table of wear amounts corresponding to the detection results by the wear detection unit 62 (hereinafter referred to as "gap measurement value Gmv"), and a data table of pump discharge flow rates corresponding to the detection results by the flow detection unit 77 (hereinafter referred to as "flow measurement value Fmv").

The thresholds stored in the memory unit 81 include a vibration warning value Vav for the vibration measurement value Vmv detected by the vibration sensor 61, and a gap warning value Gav and a gap limit value Glv for the gap measurement value Gmv detected by the wear detection unit 62. Of these, the vibration warning value Vav is set for each different flow measurement value Fmv (pump discharge flow rate).

The relationship between the gap (clearance) of the underwater bearing 56 and the dangerous rotation speed of the drainage mechanism 40 is shown in Figure 5, and the relationship between the gap of the underwater bearing 56 and the axial vibration of the drainage mechanism 40 is shown in Figure 6. In Figure 5, the vertical axis shows the dangerous rotation speed of the drainage mechanism 40, and the horizontal axis shows the gap of the underwater bearing 56. In Figure 6, the vertical axis shows the bearing surface pressure, contact transition surface pressure, and axial vibration, and the horizontal axis shows the gap of the underwater bearing 56.

The axial vibration of the drainage mechanism 40 decreases as the difference (detuning) between the rotation speed and natural frequency of the drainage mechanism 40 increases. Referring to FIG. 5, the gap of the underwater bearing 56 increases due to wear, etc., and the natural frequency of the drainage mechanism 40 decreases accordingly. The point where the critical speed (dangerous rotation speed) of the drainage mechanism 40 and the natural frequency coincide is the first critical speed, at which the drainage mechanism 40 will whirl due to resonance, damaging the area around the underwater bearing 56 and the installation floor 1.

Referring to FIG. 6, the gap of the underwater bearing 56 and the axial vibration of the drainage mechanism 40 are correlated as described above, and the gap of the underwater bearing 56 can be identified by recording the axial vibration of the drainage mechanism 40. Specifically, the axial vibration of the drainage mechanism 40 increases as the gap of the underwater bearing 56 increases, and after passing its peak, it decreases as the gap of the underwater bearing 56 increases. However, when the axial vibration reaches its peak, the impact on the area around the underwater bearing 56 and the installation floor 1 is too great, and further operation of the drainage mechanism 40 is hindered. In other words, the underwater bearing 56 needs to be replaced before the axial vibration of the drainage mechanism 40 reaches its peak.

The gap limit value Glv is set to the amount of wear at an appropriate time (for example, the gap "2.0" in Figs. 5 and 6) before the time when the critical speed and natural frequency of the drainage mechanism 40 coincide and the axial vibration of the drainage mechanism 40 reaches its peak (the gap "2.5" in Figs. 5 and 6). The gap alarm value Gav is set to the amount of wear at a time before the gap limit value Glv (for example, the gap "1.5" in Figs. 5 and 6). The vibration alarm value Vav is set by converting the vibration value ("0.2" in Fig. 6) corresponding to the gap alarm value Gav for each different flow measurement value Fmv (pump discharge flow rate). These threshold values Vav, GVA, and GVL are set based on the actual detection results when the pump 10 is newly installed on the installation floor 1.

The memory unit 81 stores a set number of vibration measurement values Vmv detected by the vibration sensor 61 in reverse chronological order. When the number of stored values reaches the upper limit, the oldest vibration measurement value Vmv is deleted and the newest vibration measurement value Vmv is stored. The stored vibration measurement values Vmv are used to calculate the increase gradient IG of the vibration value.

The memory unit 81 further stores an alarm gradient WG to be compared with the calculated increase gradient IG. When the pump 10 is newly installed, the alarm gradient WG is set based on the slurry concentration contained in the water actually discharged. As shown in FIG. 7, the vibration amplitude of the drainage mechanism 40 increases as the vibration time history progresses. In addition, the amount of wear of the submerged bearing 56 is correlated with the slurry concentration contained in the pumped water, and as the slurry concentration increases, the amount of wear of the submerged bearing 56 increases and the slope of the vibration amplitude with respect to the time history becomes steeper. On the other hand, the slurry concentration contained in the wastewater differs depending on the drainage pumping station where the pump 10 is installed. Therefore, the alarm gradient WG is set based on the actual slurry concentration of the drainage pumping station.

Next, referring to FIG. 8, we will explain how to set the thresholds Vav, Gav, and Glv, and the alarm gradient WG after installing the new pump 10.

When installation of the pump 10 is complete, the drive motor 37 is started in step S1, and the rotation speed of the drive motor 37 is set in step S2 so that it is one of the multiple pump discharge flow rates (flow measurement value Fmv) required to determine the vibration warning value Vav. After that, in step S3, the vibration sensor 61 detects (measures) the vibration value Vb (Qi), and then in step S4, the measurement result (Vb (Qi)) is stored.

Next, in step S5, it is confirmed whether the vibration value Vb (Qi) has been measured for all pump discharge flow rates. If not, the process returns to step S2, and steps S2 to S4 are repeated until all remaining pump discharge flow rates have been measured.

When the bracket vibration value Vb (Qi) has been measured at all pump discharge flow rates, the drive motor 37 is stopped in step S6, and then the axial vibration of the drainage mechanism 40 is calculated from the detected bracket vibration value Vb (Qi) in step S7. Then, in step S8, vibration frequency analysis and dominant frequency selection are performed by Fourier transform to determine whether there is an abnormality due to a cause other than the underwater bearing 56. Next, in step S9, the supply mechanism 63 is driven, and the actual gap value C is measured by the differential pressure sensor 75.

Next, in step S10, the following formula is determined (set) from the vibration value Vb (Qi), the clearance value C, and the correlation therebetween, measured for each different pump discharge flow rate.
(Equation 1)
C=f(Vb(Qi))
C: Underwater bearing clearance Vb (Qi): Vibration value at a specified flow rate f: Function obtained from the measured underwater bearing clearance and vibration value

Finally, in step S11, the vibration warning value Vav, the gap warning value Gav, and the gap limit value Glv are determined, and the warning gradient WG is determined based on the slurry concentration contained in the actual water being discharged, and these are stored in the memory unit 81.

In this way, the vibration warning value Vav, gap warning value Gav, gap limit value Glv, and warning gradient WG are set for each actual drainage pumping station where the pump 10 is installed, thereby preventing unexpected pump failures.

Next, the equipment monitoring process by the control unit 80 will be explained with reference to Figures 9A and 9B.

The equipment monitoring process by the control unit 80 starts at the same time that the drainage operation of the pump 1 is started. In step S21, the control unit 80 waits until a set measurement time T has elapsed. The measurement time T is, for example, the time it takes for the pump vibration to reach a steady value, and since the transient time to reach this steady value differs depending on the pump 10, it is set by the setting procedure in FIG. 8. Then, when the measurement time arrives, in step S22, the vibration sensor 61 detects the vibration measurement value Vmv of the drainage mechanism 40, and then in step S23, the flow detection unit 77 detects the flow measurement value Fmv of the pump 10. Then, in step S24, the measurement results Vmv and Fmv are stored in the memory unit 81.

Then, it is determined whether wear detection is necessary based on the detected vibration measurement value Vmv. Specifically, in step S25, it is determined whether the vibration measurement value Vmv by the vibration sensor 61 indicates a vibration warning value Vav or more.

If the vibration measurement value Vmv is equal to or greater than the vibration warning value Vav, the control unit 80 determines that wear detection by the wear detection unit 62 is necessary to clarify the cause of the vibration, and proceeds to step S28 (wear detection).

If the vibration measurement value Vmv is less than the vibration warning value Vav, in step S26, the increase gradient IG is calculated based on the vibration measurement value Vmv stored in the memory unit 81. Then, based on the calculated increase gradient IG, it is determined whether or not wear detection is required. Specifically, in step S27, it is determined whether or not the calculated increase gradient IG is equal to or greater than the stored warning gradient WG.

If the increase gradient IG is equal to or greater than the warning gradient WG, that is, if the vibration measurement value Vmv is less than the vibration warning value Vav but the increase gradient IG is equal to or greater than the warning gradient WG, the control unit 80 determines that wear detection by the wear detection unit 62 is necessary to clarify the cause of the vibration, and proceeds to step S28 (wear detection).

If the increase gradient IG is less than the warning gradient WG, that is, if the vibration measurement value Vmv is less than the vibration warning value Vav and the increase gradient IG is less than the warning gradient WG, the control unit 80 determines that the pump 10 is healthy and that wear detection by the wear detection unit 62 is unnecessary, and returns to step S21 to continue the drainage operation.

When detecting wear on the underwater bearings 56, the control unit 80 stops the drive motor 37 and interrupts the drainage operation in step S28. Next, in step S29, in order to measure the amount of wear (gap) of the underwater bearings 56, the control unit 80 drives the supply mechanism 63 and causes the differential pressure sensor 75 to detect the differential pressure (gap measurement value Gmv). More specifically, the control unit 80 switches the connection state between the blower 64 and the three underwater bearings 56 in sequence using the switching valve 65, and individually determines the amount of wear on all of the underwater bearings 56.

Then, the presence or absence of an abnormality in the underwater bearing 56 is determined based on the detected gap measurement value Gmv. Specifically, in step S30, it is determined whether the gap measurement value Gmv by the wear detection unit 62 indicates a value equal to or greater than the gap limit value Glv. In this embodiment, since three underwater bearings 56 are used, the three gap measurement values Gmv are compared with the gap limit value Glv.

If any one of the three gap measurements Gmv is equal to or greater than the gap limit value Glv, the control unit 80 determines that the wear of the underwater bearing 56 has reached its limit, and in step S31, the notification unit 82 issues a notification to notify the user of an abnormality in the underwater bearing 56, and the equipment monitoring process ends. This stops the drainage operation of the pump 10. In addition, the operator who has been notified of the abnormality in the underwater bearing 56 pulls out the drainage mechanism 40 from the pump casing 20, replaces the underwater bearing 56, and inspects and repairs the parts around the underwater bearing 56.

If all three gap measurement values Gmv are less than the gap limit value Glv, the control unit 80 determines in step S32 whether the gap measurement value Gmv by the wear detection unit 62 is greater than or equal to the gap warning value Gav.

If any one of the three gap measurement values Gmv indicates a gap warning value Gav or greater, the control unit 80 stores the judgment result in the memory unit 81 in step S33, and then issues a warning via the notification unit 82 in step S34 to prompt the user to prepare for replacement of the underwater bearings 56. The process then returns to step S21 to continue the drainage operation. Note that the judgment result may be stored for each of multiple underwater bearings 56, or may be stored for all underwater bearings 56 together. This allows the operator to arrange for an unused underwater bearing 56 and prepare for replacement.

If all three gap measurements Gmv are less than the gap warning value Gav, that is, if the wear of the underwater bearing 56 is within the allowable range but the vibration of the drainage mechanism 40 is greater than the allowable value or shows an excessively increasing tendency, the control unit 80 issues a warning to alert the user to the possibility of an abnormality other than that of the underwater bearing 56 in step S35 using the warning unit 82, and ends the equipment monitoring process. This stops the drainage operation of the pump 10. The operator who has been notified of an abnormality other than that of the underwater bearing 56 identifies the cause and mechanism of the vibration from the multiple vibration measurement values Vmv stored in the memory unit 81, determines whether the vibration is likely to increase in the future, and plans and prepares vibration reduction measures from the perspective of factors other than the underwater bearing 56. In addition, if it is unclear whether the vibration is likely to increase in the future, the operation of the pump 10 is resumed, regular vibration detection and wear detection are continued, and the frequency of vibration detection is increased if necessary (the measurement period is shortened).

The pump 10 configured in this manner has the following features:

Since the vibration of the drainage mechanism 40 increases as the wear of the underwater bearing 56 progresses, the amount of wear of the underwater bearing 56 can be predicted (identified) from the vibration measurement value Vmv of the drainage mechanism 40 detected during drainage operation. Therefore, by only performing actual wear detection when it is determined that wear detection of the underwater bearing 56 is necessary based on vibration detection of the drainage mechanism 40, the number of times wear detection of the underwater bearing 56 by the wear detection unit 62, which requires a long operation time, can be reduced. As a result, the period during which the pump 10 is unable to operate due to maintenance management can be reduced.

When the vibration measurement value Vmv by the vibration sensor 61 is equal to or greater than the set vibration warning value Vav, or when the detection result of the vibration sensor 61 is less than the vibration warning value Vav but the increase gradient IG of the vibration measurement value Vmv is equal to or greater than the set warning gradient WG, it is determined that wear detection is actually necessary. Therefore, it is possible to detect abnormalities such as when a large amount of slurry gets mixed into the wastewater due to unexpected weather conditions and the submerged bearing 56 wears excessively, thereby improving the reliability of the pump 10.

If the result of wear detection of the underwater bearing 56 shows that the gap measurement value Gmv of the underwater bearing 56 is equal to or greater than the gap warning value Gav, an alert is issued to encourage preparation for replacement of the underwater bearing 56. On the other hand, if the vibration measurement value Vmv is equal to or greater than the vibration warning value Vav but the gap measurement value Gmv of the underwater bearing 56 is less than the gap warning value Gav, this means that there is a cause of vibration other than the underwater bearing 56, and in such a case an alert is issued to encourage the possibility of an abnormality other than that of the underwater bearing 56. This makes it possible to prevent unexpected breakdowns of the pump 10.

The allowable vibration value of the drainage mechanism 40 and the amount of wear of the underwater bearing 56 vary depending on the drainage pumping station where the pump is actually installed, even for the same model of pump. In response to this, the vibration warning value Vav and the gap warning value Gav are set based on the detection results Vmv and Gmv of the vibration sensor 61 and the wear detection unit 62, respectively, when the pump 10 is installed, so that failures of the pump 10 can be effectively suppressed.

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

For example, the vibration sensor 61 is not limited to one, and multiple vibration sensors 61 may be arranged at different locations in the drainage mechanism 40. In this case, wear detection of the underwater bearing 56 by the wear detection unit 62 may be performed when any one of the multiple vibration sensors 61 exceeds the vibration warning value Vav, or when more than half of the multiple vibration sensors 61 exceed the vibration warning value Vav.

The vibration warning value Vav, the gap warning value Gav, the gap limit value Glv, and the warning gradient WG are set for each drainage pumping station when a new pump 10 is installed, but they may be common to all drainage pumping stations.

Even if the vibration measurement value Vmv by the vibration sensor 61 is less than the vibration warning value Vav, if the increase gradient IG of the vibration measurement value Vmv is equal to or greater than the set warning gradient WG, it is determined that wear detection is necessary, but the increase gradient IG may not be taken into consideration.

The monitoring device 60 is not limited to a configuration in which the wear state of the underwater bearing 56 is monitored by supplying air (gas), and may also monitor the wear state of the underwater bearing 56 by supplying water (liquid). In addition, although the internal piping 74 for supplying fluid between the rotating shaft 42 and the underwater bearing 56 is arranged inside the pump casing 20, the piping structure for supplying fluid can be changed as necessary.

The pump 10 is of a pull-out type in which the drainage mechanism 40 can be removed from the pump casing 20, but it may also be of a fixed type in which it cannot be removed.

LIST OF SYMBOLS 1 Installation floor 1a Through hole 2 Suction tank 10 Vertical pump 20 Pump casing 21 Lifting pipe 22 Lifting pipe body 23 Vane case 23a Support plate 24 Bell mouth 24a Suction port 25 Discharge pipe 26 Derivend 27 First straight pipe section 27a Opening 28 Second straight pipe section 28a Discharge port 29 Base plate 30 Motor stand 31 Closing plate 32 First frame section 33 Partition plate 34 Second frame section 35 End plate 36 Guide plate 37 Drive motor 38 Shaft seal device 40 Drain mechanism 42 Rotating shaft 42a Inner portion 42b Outer portion 43 Shaft member 44 Shaft joint 45 Coupling 46 Rolling bearing 48 Impeller 50 Suspension pipe 51 Cylinder 52 Connection member 52a Connection port 54 Bowl bush 54a Insertion portion 56 Underwater bearing 57 Sliding contact member 57a Communication hole 60 Monitoring device 61 Vibration sensor (vibration detection portion)
62 Wear detection unit 63 Supply mechanism 64 Blower 65 Switching valve 66 Constant flow valve 67 Check valve 68 Pressure sensor 69 Pressure tank 70 Solenoid valve 71 Check valve 72 Connection pipe 73 External pipe 74 Internal pipe 75 Differential pressure sensor (differential pressure detection unit)
76 Differential pressure measurement pipe 77 Flow rate detection unit 78 First pressure sensor 79 Second pressure sensor 80 Control unit 81 Memory unit 82 Notification unit

Claims (8)

A vibration detection unit detects vibrations of a drainage mechanism that discharges water from the suction tank,
determining whether or not wear detection of the underwater bearing constituting the drainage mechanism is necessary based on the detection result of the vibration detection unit;
When it is determined that the wear detection is necessary, a supply mechanism supplies fluid between the underwater bearing and the rotating shaft, and the amount of wear of the underwater bearing is determined based on the detection result of a differential pressure detection unit that detects the differential pressure between the fluid pressure supplied by the supply mechanism and the internal pressure of the pump casing ,
When the amount of wear is equal to or greater than a predetermined gap warning value, a warning unit issues a warning to encourage preparation for replacement of the underwater bearing, and when the amount of wear is less than the gap warning value, a warning unit issues a warning to encourage the possibility of an abnormality other than that of the underwater bearing .
How to monitor your pump. A determination is made as to whether or not a measurement time has elapsed for determining whether or not wear detection is required for the submersible bearing that constitutes a drainage mechanism that drains water from the suction tank;
When the measurement time has elapsed, a vibration detection unit detects vibration of the drainage mechanism;
determining whether or not wear detection of the underwater bearing is necessary based on the detection result of the vibration detection unit;
When it is determined that the wear detection is necessary, a fluid is supplied between the underwater bearing and the rotating shaft by a supply mechanism, and the amount of wear of the underwater bearing is determined based on the detection result of a differential pressure detection unit that detects the differential pressure between the fluid pressure supplied by the supply mechanism and the internal pressure of the pump casing.
How to monitor your pump. If the amount of wear is equal to or greater than a predetermined gap alarm value, a notification is issued to prompt the user to prepare for replacement of the underwater bearing.
If the amount of wear is less than the gap alarm value, a warning is given to warn of the possibility of an abnormality other than that of the underwater bearing.
The method for monitoring a pump according to claim 2 . A pump monitoring method according to any one of claims 1 to 3, further comprising determining that wear detection is necessary when the detection result of the vibration detection unit is equal to or greater than a predetermined vibration warning value, or when the detection result of the vibration detection unit is less than the vibration warning value but the increasing gradient of the detection result is equal to or greater than a predetermined warning gradient. 5. The pump monitoring method according to claim 4 , wherein the vibration warning value is set based on a detection result of the vibration detection section and a detection result of the differential pressure detection section when the pump casing is installed. 4. The pump monitoring method according to claim 1 , wherein the gap alarm value is set based on a detection result of the vibration detection section and a detection result of the differential pressure detection section when the pump casing is installed. A pump casing;
a drainage mechanism that has a rotating shaft with an impeller attached to a portion disposed within the pump casing, and a submerged bearing that rotatably supports the rotating shaft, and that drains water from a suction tank,
a vibration detection unit that detects vibration of the drainage mechanism;
a supply mechanism for supplying a fluid between the rotating shaft and the underwater bearing;
a differential pressure detection unit that detects a differential pressure between the fluid pressure supplied by the supply mechanism and the internal pressure of the pump casing;
a control unit that determines whether or not wear detection of the underwater bearing is necessary based on the detection result of the vibration detection unit, and when it determines that wear detection is necessary, drives the supply mechanism and determines the amount of wear of the underwater bearing based on the detection result of the differential pressure detection unit ;
a notification unit for notifying an abnormality in the drainage mechanism;
Equipped with
The control unit of the pump monitoring device is configured so that, when the amount of wear is equal to or greater than a set gap warning value, the alarm unit issues an alert to encourage preparation for replacement of the underwater bearing, and when the amount of wear is less than the gap warning value, the alarm unit issues an alert to encourage the possibility of an abnormality other than the underwater bearing . A pump casing;
a drainage mechanism that has a rotating shaft with an impeller attached to a portion disposed within the pump casing and a submerged bearing that rotatably supports the rotating shaft, and that drains water from within the suction tank;
A pump monitoring device comprising:
a vibration detection unit that detects vibration of the drainage mechanism;
a supply mechanism for supplying a fluid between the rotating shaft and the underwater bearing;
a differential pressure detection unit that detects a differential pressure between the fluid pressure supplied by the supply mechanism and the internal pressure of the pump casing;
a control unit that judges whether a measurement time for judging whether wear detection of the underwater bearing is necessary has elapsed, and when the measurement time has elapsed, judges whether wear detection of the underwater bearing is necessary based on the detection result of the vibration detection unit, and when it is judged that wear detection is necessary, drives the supply mechanism and judges the amount of wear of the underwater bearing based on the detection result of the differential pressure detection unit;
A pump monitoring device comprising:

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