Submersible pump monitoring system and submersible pump monitoring method

Abstract

To provide a submerged pump monitoring system and a submerged pump monitoring method capable of determining whether water content is increasing or whether fine particles such as iron powder or mud are increasing in a shaft seal oil of a shaft seal device of a submerged pump.SOLUTION: A submerged pump monitoring system includes a light emitting unit 15 that irradiates a shaft seal oil L of a submerged pump with light, a light receiving unit 16 provided to detect the light of the light emitting unit 15 through the shaft seal oil L, and a determining unit that determines whether the shaft seal oil is contaminated with moisture or nontranslucent particles by determining whether a change in the intensity of the light received by the light receiving unit 16 follows an exponential function or a power function.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a system and method for determining and monitoring the condition of shaft seal oil in submersible pumps used in fields such as wastewater treatment and civil engineering. [Background technology]

[0002] A conventional submersible pump 1P, as shown in Figure 13, comprises a pump chamber 5 which houses an impeller 2 and has an inlet 3 and an outlet 4, a motor base 6 connected to a casing 5a which forms the pump chamber 5, a motor chamber 7 formed by the motor base 6 and a motor frame 7a connected to it, a stator 8 fixed within the motor chamber 7, a rotor 10 having a motor shaft 9, a seal housing 11 which closes a recess 6a formed in the lower part of the motor base 6, and a shaft seal device (mechanical seal) 12 attached to the motor shaft 9 within the recess 6a of the motor base 6 which is closed by the seal housing 11, and the recess 6a is closed by the seal housing 11 to form an oil chamber 13, which is filled with shaft seal oil L and the shaft seal device 12 is immersed in the shaft seal oil L.

[0003] The shaft seal device 12 is a consumable part and is therefore replaced periodically, but if the shaft seal device 12 deteriorates before the periodic replacement, it can lead to a breakdown of the submersible pump.

[0004] The most common failure in this type of submersible pump is caused by deterioration of the shaft seal device 12, which causes water or fine particles such as metal powder and mud to get into the oil chamber 13.

[0005] Conventionally, an electrode 14 is inserted into the shaft seal oil L, which is essentially an insulator, and the electrical resistance (insulation resistance) between the electrode 14 and earth (the grounded motor frame 7a) is measured to detect a decrease in the insulation resistance value due to water mixing into the shaft seal oil.A threshold value is set, and when the insulation resistance value falls below a set value (e.g., 0.1 MΩ), it is determined that a malfunction has occurred due to water entering the shaft seal oil L (Patent Documents 1, 2, etc.).

[0006] However, the water ingress detection method of measuring the insulation resistance value of the seal oil alone cannot clearly detect the presence of metal powder such as iron powder in the seal oil as water, nor can it detect fine mud particles in the seal oil. Therefore, the inventors previously proposed a submersible pump monitoring system that uses an oil sensor equipped with a light-emitting element that irradiates light onto the seal oil and a light-receiving element that detects the intensity of the light that passes through the seal oil from the light-emitting element, and can detect changes in the intensity of the received light, thereby detecting the presence of fine particles such as metal powder and mud in the seal oil (Patent Document 3). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-310091 [Patent Document 2] Japanese Unexamined Patent Publication No. 54-1083 [Patent Document 3] Japanese Patent Application Publication No. 2019-203799 Summary of the Invention [Problem to be solved by the invention]

[0008] However, in the above-mentioned conventional monitoring system, the received light intensity may change even when the moisture content increases, making it difficult to determine whether the change in received light intensity is due to moisture or an increase in foreign matter such as iron powder.

[0009] Therefore, the main object of the present invention is to provide an underwater pump monitoring system and an underwater pump monitoring method that can determine whether there is an increase in water or an increase in fine particles such as iron powder or mud in the sealing oil of the shaft seal device of an underwater pump. [Means for solving the problem]

[0010] In order to achieve the above-mentioned object, one embodiment of the present invention provides an underwater pump monitoring system comprising: an emitting unit that irradiates light onto the shaft seal oil of an underwater pump; a light receiving unit that is configured to detect the light from the emitting unit through the shaft seal oil; and a determining unit that determines whether the change in intensity of the light received by the light receiving unit follows an exponential function or a power function, thereby determining whether water or non-transparent fine particles are mixed into the shaft seal oil.

[0011] In addition, an underwater pump monitoring method according to one aspect of the present invention includes the steps of irradiating light from a light-emitting unit onto the shaft seal oil of an underwater pump, detecting the light from the light-emitting unit through the shaft seal oil, and determining whether the change in intensity of the detected light follows an exponential function or a power function, thereby determining whether water or non-transparent fine particles have been mixed into the shaft seal oil.

[0012] The light emitting section preferably emits red light. [Effects of the Invention]

[0013] According to the present invention, by determining whether the change in the intensity of the light received by the light receiving element follows an exponential function or a power function, it is possible to distinguish whether the moisture content of the shaft seal oil is increasing or whether the amount of fine particles other than moisture is increasing. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a central vertical cross-sectional view showing an embodiment of a submersible pump used in the present invention. [Figure 2] 2 is a circuit diagram showing an embodiment of a measurement circuit for the submersible pump of FIG. 1. [Figure 3] FIG. 2 is an enlarged cross-sectional view showing a part of FIG. 1. [Figure 4] FIG. 1 is a schematic diagram showing a simulation test device. [Figure 5] 10 is a graph showing the relationship between the amount of increased iron powder in the shaft sealing oil and the intensity of received light. [Figure 6]10 is a graph showing the relationship between the amount of increased iron powder in the shaft sealing oil and the intensity of received light. [Figure 7] 10 is a graph showing the relationship between the amount of increased iron powder in the shaft sealing oil and the intensity of received light. [Figure 8] 10 is a graph showing the relationship between the amount of moisture increase in the shaft sealing oil and the intensity of received light. [Figure 9] 10 is a graph showing the relationship between the amount of moisture increase in the shaft sealing oil and the intensity of received light. [Figure 10] 10 is a graph showing the relationship between the amount of moisture increase in the shaft sealing oil and the intensity of received light. [Figure 11] 1 is a flowchart showing a determination process in the submersible pump monitoring system according to the present invention. [Figure 12] 1 is a system showing one embodiment of a submersible pump monitoring system according to the present invention. [Figure 13] FIG. 1 is a central vertical cross-sectional view showing a conventional submersible pump. DETAILED DESCRIPTION OF THE INVENTION

[0015] An embodiment of a submersible pump monitoring system according to the present invention will be described below with reference to Figures 1 to 12. Note that the same or similar components are designated by the same reference numerals throughout all figures and all examples, including those of the prior art.

[0016] Fig. 1 is a longitudinal cross-sectional view showing one embodiment of a submersible pump equipped with a submersible pump monitoring system according to the present invention. Referring to Fig. 1, the submersible pump 1 includes a motor chamber 7 that houses a rotor 10 and a stator 8, a pump chamber 5 that has a suction port 3 and a discharge port 4 and houses an impeller 2, an oil chamber 13 that is arranged between the motor chamber 7 and the pump chamber 5, a motor shaft 9 that is connected to the rotor 10 and extends from the motor chamber 7 through the oil chamber 13 into the pump chamber 5, and a shaft seal device 12 that seals the motor shaft 9 within the oil chamber 13.

[0017] Shaft seal oil L is sealed in the oil chamber 13. The submersible pump 1 is equipped with a light-emitting unit 15 that irradiates light onto the shaft seal oil L, and a light-receiving unit 16 that is arranged to receive the light emitted from the light-emitting unit 15 through the shaft seal oil L. The light-receiving unit 16 receives the light emitted from the light-emitting unit 15 and outputs a signal according to the intensity of the received light.

[0018] The light-emitting unit 15 is composed of a light-emitting diode. Instead of a light-emitting diode, other light-emitting elements such as a laser diode can be used for the light-emitting unit 15. The light-receiving unit 16 is composed of a photodiode. A photodetector such as a phototransistor can also be used for the light-receiving unit 16.

[0019] The light received by the light receiving unit 16 is output as a current corresponding to the intensity of the received light. Figure 2 shows the measurement circuit 17 that measures the output of the light receiving unit 16, and the intensity of the light received by the light receiving unit 16 is measured by measuring the voltage across resistor R2 with a voltmeter V. The measurement data of the voltmeter V is recorded in a data logger D.

[0020] 3, the light emitting unit 15 is attached to a first support 18 that is fixed so as to hang down within the oil chamber 13. The light emitting unit 15 is not limited to the first support 18 shown in the figure, and can be disposed within the oil chamber 13 by any suitable means.

[0021] The light-emitting unit 15 can also be disposed outside the oil chamber 13. In this case, a transmission window (not shown) can be provided in a part of the wall surface that constitutes the oil chamber 13, and the light-emitting unit 15 can be disposed outside the oil chamber 13 so that light enters the oil chamber 13 through the transmission window.

[0022] 3, the light receiving unit 16 is attached to a second support 19 that is suspended and fixed within the oil chamber 13. The second support 19 is disposed parallel to and spaced apart from the first support 18. The light receiving unit 16 is not limited to being disposed on the second support 19 shown in the figure, and can be disposed within the oil chamber 13 by any suitable means.

[0023] Similarly to the light-emitting unit 15, the light-receiving unit 16 can also be disposed outside the oil chamber 13. In this case, a transmission window (not shown) can be provided in a part of the wall surface that constitutes the oil chamber 13, and the light-receiving unit 16 can be disposed outside the oil chamber 13 so as to receive light emitted from the oil chamber 13 through the transmission window.

[0024] The relationship between the light receiving intensity of the light receiving section 16 and the water or iron powder in the shaft sealing oil will be described below using a simulation test device.

[0025] Figure 4 shows a schematic configuration of the simulation test device 20. The measurement circuit is the same as that shown in Figure 2, with the voltage VCC set to 5 V, the resistor R1 set to 1 kΩ, and the resistor R2 set to 10 kΩ. The test conditions are as follows:

[0026] Light-emitting unit 15: OptoSupply light-emitting diode, model number OS5RKA3131A, center wavelength 624 nm Photodetector 16: Hamamatsu Photonics Co., Ltd. photodiode, model number S7183, sensitivity wavelength range 300 to 1000 nm Distance between light-emitting unit 15 and light-receiving unit 16: 6 cm The light emitting part 15 and the light receiving part 16 are fixed to supports 22 and 23, respectively, which are installed in a container 21 filled with shaft sealing oil L.

[0027] First, iron powder was added to 1.8 L of shaft sealing oil filled in a container 21 in increments of 0.1 g from 0 g to 0.6 g, and then in increments of 0.2 g from 0.6 g to 1 g, and the voltage of the light receiving part was measured while stirring with the stirrer 24 set to 2000 rpm. This measurement was also performed when 0 ml, 10 ml, and 20 ml of water were mixed in.

[0028] The measurement results are shown in Figures 5 to 7. Figure 5 shows 0 ml of water, Figure 6 shows 10 ml of water, and Figure 7 shows 20 ml of water. The graphs in Figures 5 to 7 plot the output of the light-receiving unit 16 and display the approximate curves. The approximate curves in Figures 5 to 7 are all approximated by exponential functions.

[0029] When the light from the light-emitting element 15 hits the iron powder, it is reflected and scattered, resulting in the light reaching the light-receiving element 16 being attenuated and the output (voltage) decreasing. Furthermore, this phenomenon occurs more frequently as the amount of iron powder mixed in increases, which is thought to be the reason for the test results shown above. The following formula is established according to the Beer-Lambert law.

[0030]

number

[0031] 5 to 7, the amount of iron powder mixed in the shaft sealing oil can be estimated by measuring the output (voltage) of the light receiving unit 16 with the measuring circuit 17. The approximate curve in Fig. 5 is expressed by the following equation 2 when the amount of water is 0 g.

[0032]

number

[0033]

number

[0034] Next, using the above-mentioned simulation equipment, 1.8 L of shaft sealing oil was placed in container 21, and 5 ml, 10 ml, 20 ml, 30 ml, 40 ml, and 80 ml of water were mixed in. The rotation speed of agitator 24 was set to 2000 rpm, and the voltage of voltmeter V was measured while stirring. The results of this measurement when 0 g, 0.1 g, and 0.5 g of iron powder were mixed in are shown in Figures 8 to 10. Figure 8 shows the case where the amount of iron mixed in is 0 g, Figure 9 shows the case where the amount of iron mixed in is 0.1 g, and Figure 10 shows the case where the amount of iron mixed in is 0.5 g.

[0035] The graphs in Figures 8 to 10 show a tendency for voltage to decrease as the moisture content increases. The amount of moisture in the shaft seal oil is difficult to distinguish visually, but there is a clear difference in the voltage of the received light. In other words, by measuring the output (voltage) of the light receiving unit (photodiode), it is possible to read the amount of moisture contained in the shaft seal oil. This is thought to be due to the fact that water and shaft seal oil do not mix completely and the absorption spectrum. Furthermore, since water has the property of easily absorbing red light, it is thought that the agitated water absorbs the light from the red light-emitting diode, causing the voltage to decrease. The graphs in Figures 8 to 10 are all approximated by a power function.

[0036] From the above test results, if the output of the light receiving unit 16 decreases according to a power function, it can be determined that there is an increase in water content in the shaft seal oil. On the other hand, if the output of the light receiving unit 16 decreases according to an exponential function, it can be determined that there is an increase in foreign matter (particles) such as iron powder in the shaft seal oil L that reflects and scatters light without transmitting it. Note that water includes freshwater and seawater. Particles other than water that do not transmit light (opaque) include metal powders such as iron powder as well as mud particles.

[0037] The above determination is performed in the determination unit 25 (FIG. 2). The determination unit 25 may include a CPU, memory, timer circuit, etc. (not shown), and receives measurement data of the received light intensity (voltage signal) measured by the measurement circuit 17 from the data logger D, and performs calculations on the measurement data in the CPU using an application (analysis software) stored in the memory to determine whether the amount of water in the shaft sealing oil L has increased or whether the amount of foreign matter such as iron has increased.

[0038] FIG. 11 is a flowchart showing the judgment process in the judgment unit 25. In step S1, the judgment unit 25 reads and stores the voltage output V1 of the measurement circuit 17 at a predetermined time interval t. In step S2, the judgment unit 25 judges whether the output V1 has dropped to a predetermined threshold value. In step S3, when the output V1 falls below the predetermined threshold value, the judgment unit 25 calculates and generates an approximation function using the least squares method or the like. In step S4, it is determined from the generated approximation function whether the approximation function is an exponential function or a power function, thereby judging whether there is an increase in moisture in the shaft sealing oil or an increase in foreign matter (fine particles) other than moisture, such as iron powder. The judgment result can be displayed on a monitor.

[0039] If it is determined that there is an increase in fine particles (solids) such as iron powder in the seal oil, it is highly likely that the condition of the shaft seal device (mechanical seal) is deteriorating, so by pulling the submersible pump out of the water and inspecting it early, it is possible to determine whether maintenance should be performed before the shaft seal device breaks down.On the other hand, if it is determined that there is an increase in water rather than iron powder, there is no need to inspect it immediately, but if there is a large amount of water, there is a risk of water entering the motor room, so a certain threshold can be set and the submersible pump can be inspected when the amount of water exceeds the threshold.

[0040] In one embodiment of the submersible pump monitoring system, the submersible pump 1 is equipped with a wireless communication module 26 (FIG. 1) that transmits the signal output of the light receiving unit 16. The wireless communication module 26 can be installed inside the motor room 7 as shown in FIG. 1, or, although not shown, can be connected by wire to an external part of the submersible pump 1, for example, inside a power control device 27 (FIG. 12) that controls the submersible pump 1. When the wireless communication module 26 is installed inside the motor room 7, a cable can be drawn from the submersible pump 1 and an external antenna (not shown) can be connected to it.

[0041] The measurement data from the measurement circuit 17 of the light receiving unit 16 is stored in a data logger, wirelessly transmitted by a wireless communication module 26, and as shown in Fig. 12, sent to a server 31 via a gateway 28, a mobile communication base station 29, and a network line 30, where it can be stored in the server 31. The measurement data stored in the server 31 is read into a personal computer 32 connected via a line such as the Internet, and analyzed by software installed on the personal computer 32, making it possible to determine whether the amount of water in the shaft sealing oil has increased or whether there has been an increase in non-transparent fine particles other than water, such as iron.

[0042] The present invention should not be construed as being limited to the above-described embodiment, and various modifications are possible within the scope of the present invention. [Explanation of symbols]

[0043] 1. Submersible pump 5. Pump Room 7 Motor Room 12 Shaft sealing device 13 Oil chamber 15 Light-emitting part 16 Light receiving part 25 Judgment section

Claims

1. a light-emitting unit that irradiates light onto the shaft seal oil of the submersible pump; a light receiving unit configured to detect light from the light emitting unit through the shaft sealing oil; a determining unit that determines whether the change in intensity of the light received by the light receiving unit follows an exponential function or a power function, thereby determining whether water or non-transparent fine particles are mixed in the shaft sealing oil; A submersible pump monitoring system comprising:

2. The submersible pump monitoring system of claim 1 , wherein the light-emitting unit emits red light.

3. A step of irradiating light from a light emitting unit onto shaft sealing oil of the submersible pump; detecting light from the light emitting unit through the shaft sealing oil; determining whether the change in the detected light intensity follows an exponential function or a power function, thereby determining whether water or non-transparent fine particles are mixed in the shaft sealing oil; A method for monitoring a submersible pump, comprising:

4. The submersible pump monitoring method according to claim 3 , wherein the light-emitting unit emits red light.

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