JP7000800B2 - Detection device, detection method, and program - Google Patents

Description

The present invention relates to a detection device, a detection method, and a program.

Pumps that suck in and discharge liquids may experience cavitation due to the vaporization of the liquid. Conventionally, a technique for detecting the occurrence of such cavitation by frequency analysis of the discharge pressure of a pump has been known (see, for example, Patent Document 1).
Patent Document 1 Japanese Patent Application Laid-Open No. 64-45975

However, in the technique of Patent Document 1, the arithmetic processing of frequency analysis may become a heavy burden. For example, in a plant equipped with a large number of pumps of several hundreds to several thousand or more, cavitation of each pump may be processed. Therefore, a technique for efficiently detecting cavitation with a small amount of arithmetic processing is desired.

In the first aspect of the present invention, the cavitation of the pump is generated based on the discharge pressure acquisition unit that acquires the discharge pressure data indicating the discharge pressure of the pump and the fluctuation amount of the time waveform of the discharge pressure data during the detection target period. Provided is a detection device, a detection method, and a program including a detection unit for detecting the above.

In the second aspect of the present invention, the suction pressure acquisition unit that acquires the suction pressure data indicating the suction pressure of the pump, the discharge pressure acquisition unit that acquires the discharge pressure data indicating the discharge pressure of the pump, and the suction pressure data Provided are a detection device, a detection method, and a program including a detection unit for detecting whether or not cavitation has occurred in the pump based on discharge pressure data according to a threshold value or less.

In the third aspect of the present invention, based on the difference between the discharge pressure acquisition unit that acquires the discharge pressure data indicating the discharge pressure of the pump, the discharge pressure data during the detection target period, and the discharge pressure data before the detection target period. , A detection device, a detection method, and a program including a detection unit for detecting the occurrence of cavitation of a pump.

The outline of the above invention does not list all the necessary features of the present invention. A subcombination of these feature groups can also be an invention.

A configuration example of the plant 10 provided with the detection device 100 according to the present embodiment is shown. An example of the suction pressure data and the discharge pressure data acquired by the detection device 100 according to the present embodiment is shown. A configuration example of the detection device 100 according to the present embodiment is shown. An example of the operation flow of the detection device 100 according to this embodiment is shown. An example of the fluctuation amount of the discharge pressure data calculated by the fluctuation amount calculation unit 160 in this embodiment is shown. A modification of the detection device 100 according to the present embodiment is shown. A configuration example of a computer 1200 in which a plurality of aspects of the present invention can be embodied is shown.

Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention to which the claims are made. Also, not all combinations of features described in the embodiments are essential to the means of solving the invention.

FIG. 1 shows a configuration example of a plant 10 provided with a detection device 100 according to the present embodiment. The plant 10 is a system that controls the equipment while supplying the liquid to the equipment or the like by a pump. The plant 10 may be at least a part of a factory facility, a mechanical device, a production device, a power generation device, and the like. The plant 10 includes equipment 20, a liquid source 30, a pump 40, a suction pressure gauge 50, a discharge pressure gauge 60, and a control system 70. The plant 10 may include at least a plurality of equipment 20, a liquid source 30, a pump 40, a suction pressure gauge 50, a discharge pressure gauge 60, and a detection device 100.

The equipment 20 is the control target of the plant 10. The equipment 20 may be at least a part of factory equipment, mechanical equipment, production equipment, power generation equipment, storage equipment and the like. The device 20 may include a device that receives a liquid such as water, oil, fuel, a refrigerant, or a chemical and performs a processing operation using the liquid. The device 20 may include a plurality of devices.

The liquid source 30 stores or supplies the liquid supplied to the device 20. The liquid source 30 may be a tank or the like that stores, stores, and maintains the pressure of the liquid. Further, the liquid source 30 may be a well or an oil well provided in an area where resources such as groundwater and an oil field are accumulated or buried. Further, the liquid source 30 may be a river, a pond, a lake, a dam, or the like. Further, the liquid source 30 may be a tank in which a liquid supplied by another pump is stored. Further, the liquid source 30 may be a pipe connected to a tank or the like.

The pump 40 supplies the liquid of the liquid source 30 to the device 20. The pump 40 is connected between the liquid source 30 and the device 20 by using a valve, a pipe, or the like. FIG. 1 shows an example of the direction of movement of the liquid inside the pipe by an arrow from the liquid source 30 to the device 20. The pump 40 may be a centrifugal pump having a blade-shaped rotor (impeller) or the like. Further, the pump 40 may be a diffuser pump, a cascade pump, an axial flow pump, a mixed flow pump, a cross flow pump, or the like. A plurality of pumps 40 may be arranged in the plant 10.

The suction pressure gauge 50 is provided between the liquid source 30 and the pump 40, and measures the suction pressure of the pump 40. The discharge pressure gauge 60 is provided between the device 20 and the pump 40, and measures the discharge pressure of the pump 40. The suction pressure gauge 50 and the discharge pressure gauge 60 are, for example, a differential pressure type flow meter or a pressure transmitter. The suction pressure gauge 50 and the discharge pressure gauge 60 may function as sensors for detecting the operation of the pump 40. The suction pressure gauge 50 and the discharge pressure gauge 60 may be provided for each pump 40. FIG. 1 shows an example in which a liquid source 30, a pump 40, a suction pressure gauge 50, and a discharge pressure gauge 60 are provided in the plant 10 one by one. At least one of the suction pressure gauge 50 and the discharge pressure gauge 60 may be used for controlling the plant 10.

The control system 70 controls a part or all of the equipment 20 and the pump 40 based on the measurement results of measuring instruments such as sensors provided in the plant. Further, the control system 70 may control a valve provided in a pipe or the like provided in the plant. For example, the control system 70 is based on the measurement data measuring the operation of the device 20 and the measurement data such as the pressure, temperature, flow rate, and storage amount of the fluid such as a liquid handled in the plant 10, the device 20 and the pump 40. , And control and / or monitor the operation of valves, etc.

The control system 70 may be connected to the device 20 or the like via a wireless and / or wired communication device, and may be arranged at a position separated from the device 20 or the like. The control system 70 may be constructed as an automated operation system and / or a maintenance system such as a distributed control system (DCS) and a SCADA (Supervision Control And Data Acquisition) system. In this case, the control system 70 may exchange control data and measurement data with each unit at a frequency of about several Hz to several kHz.

It is desirable that the above plant 10 can control, maintain, and manage the equipment 20 including the pump 40. For example, the pump 40 may cause cavitation and the like, which may cause noise and cause deterioration and / or destruction of the pump 40. It is desirable that the plant 10 can monitor the operation of the pump 40 and perform control, maintenance, management and the like in order to suppress the occurrence of such unstable operation as much as possible.

In order to monitor the operation of the pump 40, numerical processing such as Fourier transform is executed on the discharge pressure data acquired from the discharge pressure gauge 60, and an abnormality on the frequency axis is detected to detect the abnormality of the pump 40. It is known to detect cavitation. However, it is difficult to detect an abnormality on the frequency axis unless the unstable operation of the pump 40 progresses until a clear fluctuation characteristic of a specific frequency or a specific frequency band occurs in the discharge pressure data. That is, there may be a time lag between the occurrence of cavitation and the detection, making it difficult to deal with cavitation.

Further, the plant 10 as shown in FIG. 1 may be a large-scale control system equipped with hundreds to thousands or more of pumps 40, and each pump 40 may be provided with a processing circuit for executing numerical processing. , The cost will be high. Further, since the plant 10 communicates with each part at a frequency of about several Hz to several kHz, it is difficult to execute data storage, numerical processing, analysis of results, and the like at high speed. Therefore, in such a plant 10, it has been desired to detect cavitation in real time and to predict the occurrence of cavitation while preventing an increase in cost.

Therefore, the detection device 100 is provided in such a plant 10 and detects cavitation in real time based on the temporal fluctuation of the discharge pressure data. The detection device 100 is configured to be applicable to an existing plant 10 or the like, and can acquire discharge pressure data or the like to detect cavitation. The detection device 100 may be included in the control system 70. Further, the detection device 100 may be included in a measuring instrument such as a sensor provided in the plant 10. FIG. 1 shows an example in which the detection device 100 is included in the control system 70. First, the suction pressure data and the discharge pressure data acquired by the detection device 100 will be described.

FIG. 2 shows an example of suction pressure data and discharge pressure data acquired by the detection device 100 according to the present embodiment. The horizontal axis of FIG. 2 indicates time, and the vertical axis indicates suction pressure and discharge pressure. FIG. 2 is an example showing changes in each measurement data corresponding to substantially the same time lapse by showing the suction pressure data and the discharge pressure data on substantially the same time scale. The suction pressure data is an example of the measurement result of the suction pressure gauge 50, and the discharge pressure data is an example of the measurement result of the discharge pressure gauge 60.

The suction pressure data may become a pressure lower than the atmospheric pressure (negative pressure) as the pump 40 operates. FIG. 2 shows an example in which the suction pressure data gradually decreases to a pressure lower than the atmospheric pressure after time _t0 . As described above, when the suction pressure becomes lower than the atmospheric pressure, the pressure of the liquid supplied by the pump 40 to the device 20 becomes equal to or lower than the saturated vapor pressure, and cavitation may occur due to the vaporization of the liquid.

As shown in FIG. 2, when a noise component is superimposed on the suction pressure data, the suction pressure data may have a pressure lower than the atmospheric pressure before the time t ₀ . Therefore, it is desirable that the detection device 100 execute filtering processing such as averaging, smoothing, noise removal, and / or high frequency removal of suction pressure data. Further, the suction pressure gauge 50 and the discharge pressure gauge 60 may supply the data obtained by performing such a filtering process.

The discharge pressure data is gradually reduced in accordance with the gradual decrease of the suction pressure data. FIG. 2 shows an example in which the suction pressure data continues to gradually decrease with the passage of time, and unstable fluctuations occur in the discharge pressure data from about time _tun . It should be noted that the discharge pressure data after the time t _n vibrates due to unstable fluctuations, and although the amplitude value gradually increases, clear vibrations of a specific frequency or a specific frequency band occur. It is not in a state of being. That is, for example, even if the discharge pressure data of the period T between the time t _n and the time t _n + T is Fourier transformed, the amplitude intensity of a specific frequency band has a frequency characteristic in which a difference occurs as compared with other bands. In some cases, the detection device 100 is also required to be robust.

Therefore, when the discharge pressure data is converted into the frequency axis, cavitation cannot be detected until a clear frequency signal is generated after a lapse of time beyond the time range shown in FIG. Therefore, the detection device 100 according to the present embodiment can detect the occurrence of cavitation in the time range shown in FIG. 2 based on the time waveform as shown in FIG. Such a detection device 100 will be described below.

FIG. 3 shows a configuration example of the detection device 100 according to the present embodiment. FIG. 3 shows a configuration example in which the detection device 100 detects cavitation generated in the pump 40 based on the suction pressure data and the discharge pressure data. The detection device 100 may be connected to the suction pressure gauge 50, the discharge pressure gauge 60, and the control system 70 by wire or wirelessly, respectively. The detection device 100 may be connected to these via a network or the like. The detection device 100 includes a discharge pressure acquisition unit 110, a suction pressure acquisition unit 120, and a detection unit 130.

The discharge pressure acquisition unit 110 acquires discharge pressure data indicating the discharge pressure of the pump 40. The discharge pressure acquisition unit 110 may be connected to the discharge pressure gauge 60 and receive discharge pressure data from the discharge pressure gauge 60. When the discharge pressure data is stored in an external database or the like, the discharge pressure acquisition unit 110 may access the database or the like to acquire the discharge pressure data. Further, the discharge pressure acquisition unit 110 may acquire discharge pressure data from the control system 70. The discharge pressure acquisition unit 110 supplies the acquired discharge pressure data to the detection unit 130.

The suction pressure acquisition unit 120 acquires suction pressure data indicating the suction pressure of the pump 40. The suction pressure acquisition unit 120 may be connected to the suction pressure gauge 50 and receive suction pressure data from the suction pressure gauge 50. When the suction pressure data is stored in a database or the like, the suction pressure acquisition unit 120 may access the database or the like to acquire the suction pressure data. Further, the suction pressure acquisition unit 120 may acquire suction pressure data from the control system 70. The suction pressure acquisition unit 120 supplies the acquired suction pressure data to the detection unit 130.

The detection unit 130 detects whether or not cavitation has occurred in the pump 40 based on the discharge pressure data according to the suction pressure data becoming equal to or less than the threshold value. The detection unit 130 detects the occurrence of cavitation in the pump 40, for example, based on the amount of fluctuation of the time waveform of the discharge pressure data during the detection target period. The detection unit 130 includes a storage unit 140, a comparison unit 150, a fluctuation amount calculation unit 160, and a determination unit 170.

The storage unit 140 stores suction pressure data and discharge pressure data. Further, the storage unit 140 may be able to store the data processed by the detection device 100. The storage unit 140 may store intermediate data, calculation results, parameters, and the like calculated (or used) in the process of generating the detection result by the detection device 100. Further, the storage unit 140 may supply the stored data to the request source in response to the request of each unit in the detection device 100. As an example, the storage unit 140 supplies the stored suction pressure data to the comparison unit 150 in response to the request of the comparison unit 150.

The comparison unit 150 compares the suction pressure data with a predetermined threshold value. The threshold value may be, for example, a pressure data value corresponding to atmospheric pressure. The comparison unit 150 notifies the fluctuation amount calculation unit 160 of the comparison result when the suction pressure data becomes equal to or less than the threshold value. That is, the comparison unit 150 may notify the fluctuation amount calculation unit 160 that the suction pressure data has changed from the value indicating the positive pressure to the value indicating the negative pressure.

The fluctuation amount calculation unit 160 calculates the fluctuation amount of the discharge pressure data during the detection target period. For example, the fluctuation amount calculation unit 160 reads the discharge pressure data from the storage unit 140 in response to the notification from the comparison unit 150, and calculates the fluctuation amount of the discharge pressure data. The fluctuation amount calculation unit 160 may set the reference pressure data and calculate the fluctuation amount of the discharge pressure data from the difference between the reference pressure data and the discharge pressure data. Here, the fluctuation amount calculation unit 160 uses, for example, the discharge pressure data acquired by the discharge pressure acquisition unit 110 before the detection target period as the reference pressure data. The fluctuation amount calculation unit 160 supplies the calculated fluctuation amount to the determination unit 170.

The determination unit 170 determines that cavitation has occurred in the pump 40 on condition that the fluctuation amount calculated by the fluctuation amount calculation unit 160 is equal to or greater than the reference fluctuation amount. The determination unit 170 notifies the control system 70 of the determination result in response to the determination of the occurrence of cavitation.

As described above, the detection device 100 according to the present embodiment detects the occurrence of cavitation based on the fluctuation amount of the discharge pressure data. A more specific operation of such a detection device 100 will be described below. FIG. 4 shows an example of the operation flow of the detection device 100 according to the present embodiment. The detection device 100 executes the operation flow shown in FIG. 4 to detect the occurrence of cavitation.

First, the detection device 100 acquires the discharge pressure data and the suction pressure data (S410). That is, the discharge pressure acquisition unit 110 acquires the discharge pressure data, and the suction pressure acquisition unit 120 acquires the suction pressure data. The discharge pressure acquisition unit 110 and the suction pressure acquisition unit 120 may store the acquired pressure data in the storage unit 140, respectively. The discharge pressure acquisition unit 110 and the suction pressure acquisition unit 120 may acquire pressure data each time the suction pressure gauge 50 and the discharge pressure gauge 60 sample pressure data, respectively, and instead of this, a predetermined number of samplings may be obtained. You may acquire them all at once.

Next, the comparison unit 150 compares the suction pressure data with the threshold value (S420). For example, when the suction pressure data exceeds the threshold value (S420: No), the comparison unit 150 determines that the tendency of cavitation is not detected. In this case, the detection device 100 returns to S410 and acquires the discharge pressure data and the suction pressure data sampled at the next time.

When the suction pressure acquisition unit 120 acquires the suction pressure data at the next time and stores it in the storage unit 140, the suction pressure data at the past time may be erased. In this case, the suction pressure acquisition unit 120 may overwrite the suction pressure data at the time immediately before stored in the storage unit 140 with the suction pressure data at the next time.

Further, the discharge pressure acquisition unit 110 may erase the discharge pressure data at a time before the predetermined period T. As an example, when the next time is tk _{+ 1} , the discharge pressure acquisition unit 110 erases the discharge pressure data before the time tk _−T . In this case, the discharge pressure acquisition unit 110 may overwrite the discharge pressure data stored in the storage unit 140 at a time before the time tk ₊ T with the discharge pressure data at the next time tk _{+ 1} . In this way, when the storage unit 140 acquires the pressure data at the time tk, the suction pressure data and the discharge pressure data at the time _tk and the time _tk -T before the time _tk by the period T are _timed . At least the discharge pressure data acquired up to _tk is stored.

The discharge pressure acquisition unit 110, the suction pressure acquisition unit 120, and the comparison unit 150 repeat the acquisition of the pressure data and the comparison of the suction pressure data and the threshold value until the suction pressure data becomes equal to or less than the threshold value. Then, when the suction pressure data becomes equal to or less than the threshold value (S420: Yes), the comparison unit 150 determines that the tendency is shifting to the cavitation tendency, and notifies the comparison result to the fluctuation amount calculation unit 160. Here, the threshold value is a pressure data value corresponding to the atmospheric pressure, and the comparison unit 150 notifies the fluctuation amount calculation unit 160 that the suction pressure data at time t ₀ is equal to or less than the threshold value, as shown in FIG. An example of doing so will be described.

Next, the fluctuation amount calculation unit 160 sets the reference pressure data (S430). Here, let t ₀ -T be the time before the time t ₀ by the period T. The fluctuation amount calculation unit 160 reads, for example, the discharge pressure data acquired between the time t ₀ -T and the time t ₀ from the storage unit 140 and sets it as the reference pressure data. That is, the fluctuation amount calculation unit 160 uses the data including the discharge pressure data acquired corresponding to the timing t ₀ when the suction pressure data changes from the value exceeding the threshold value to the value below the threshold value as the reference pressure data. .. In this example, the fluctuation amount calculation unit 160 uses the discharge pressure data acquired from the past timing t ₀ -T to the timing t ₀ by a predetermined period T from the timing t ₀ as a reference. An example of using it as pressure data will be described.

The fluctuation amount calculation unit 160 may store the set reference pressure data in the storage unit 140. When the past reference pressure data is stored in the storage unit 140, the fluctuation amount calculation unit 160 may overwrite the newly set reference pressure data.

Next, the detection device 100 acquires the discharge pressure data and the suction pressure data at the next sampling time (S440). That is, the discharge pressure acquisition unit 110 acquires the discharge pressure data, and the suction pressure acquisition unit 120 acquires the suction pressure data. If the discharge pressure acquisition unit 110 and the suction pressure acquisition unit 120 have just passed the time t ₀ , the discharge pressure acquisition unit 110 and the suction pressure acquisition unit 120 may continue to acquire the pressure data until the time t ₀ + T when the period T elapses.

Next, the comparison unit 150 compares the suction pressure data with the threshold value (S450). When the suction pressure data exceeds the threshold value (S450: Yes), the detection device 100 may determine that the normal operation state has been restored due to the tendency of cavitation, and may return to S410. In this case, the comparison unit 150 may erase the information of the reference pressure data from the storage unit 140.

It is desirable that the threshold value compared by the comparison unit 150 in S450 is different from the threshold value used in S420. For example, when the threshold value used in S420 is the first threshold value, the second threshold value used in S450 is a threshold value larger than the first threshold value by a predetermined value. That is, the comparison unit 150 may execute the comparison having hysteresis in order to reduce the influence of noise and the like superimposed on the suction pressure data. As an example, the second threshold value is a value obtained by adding an acceptable noise or the like to the first threshold value.

When the suction pressure data is equal to or less than the threshold value (S450: No), the comparison unit 150 may determine that the tendency of cavitation is continuing and notify the fluctuation amount calculation unit 160. Next, the fluctuation amount calculation unit 160 calculates the fluctuation amount of the discharge pressure data (S460). The fluctuation amount calculation unit 160 is the timing _t from the past timing t2 _- T that goes back by a predetermined period T from the latest detection timing t2 of the discharge pressure data acquired by the discharge pressure acquisition unit 110 in S440. The period up to ₂ is the detection target period. When the discharge pressure acquisition unit 110 continues to acquire the pressure data until the time t ₀ + T, the fluctuation amount calculation unit 160 may set the period from the time t ₀ to the time t ₀ + T as the detection target period.

Then, the fluctuation amount calculation unit 160 calculates the difference between the discharge pressure data and the reference pressure data during the detection target period as the fluctuation amount. In this way, the fluctuation amount calculation unit 160 may calculate the difference between the discharge pressure data during the detection target period and the reference pressure data having the same time length T as the detection target period as the fluctuation amount. The fluctuation amount calculation unit 160, for example, relatively shifts the time axes of the discharge pressure data and the reference pressure data, and calculates the difference between the discharge pressure data and the reference pressure data corresponding to each time.

The fluctuation amount calculation unit 160 may use a value obtained by summing (integrating) the differences between the discharge pressure data and the reference pressure data as the fluctuation amount. Further, the fluctuation amount calculation unit 160 may use a value obtained by summing up the absolute values of the differences between the discharge pressure data and the reference pressure data as the fluctuation amount. When the change in the discharge pressure data during the detection target period does not occur or is relatively small, the fluctuation amount calculated by the fluctuation amount calculation unit 160 is a value of about the difference between the integrated noise values. For example, in the detection target period from the time _tm to the time _tm + T in FIG. 2, the discharge pressure data does not change so much that the occurrence of cavitation is recognized. That is, the difference between the discharge pressure data in the detection target period and the reference pressure data from time t ₀ to time t ₀ is about noise.

Next, the determination unit 170 compares the fluctuation amount calculated by the fluctuation amount calculation unit 160 with the reference fluctuation amount (S470). Here, the reference fluctuation amount may be predetermined according to the fluctuation amount of the discharge pressure data to be detected. Further, the reference fluctuation amount may be a value of about the value obtained by integrating the noise values allowed in the discharge pressure data by the number of samplings during the period T. As an example, when the fluctuation amount is less than the reference fluctuation amount (S470: No) as in the detection target period from the time _tm to the time _tm + T, the detection device 100 returns to S440 and the discharge pressure data at the next time. And acquire suction pressure data.

The discharge pressure acquisition unit 110, the suction pressure acquisition unit 120, and the detection unit 130 compare the fluctuation amount of the discharge pressure data and the reference fluctuation amount in the next target period. The next target period may be a period between the timing that goes back by the period T from the next sampling timing of the pressure data to the sampling timing. That is, the next target period may be a period deviated by one sampling timing as compared with the previous target period.

Instead, the next target period may be a period shifted by N sampling timings from the previous target period (N is an integer of 2 or more). In this case, in S440, the discharge pressure acquisition unit 110 and the suction pressure acquisition unit 120 acquire the result of sampling the pressure data N times. It is desirable that the period for executing N samplings is shorter than the period T.

The discharge pressure acquisition unit 110, the suction pressure acquisition unit 120, and the detection unit 130 until the fluctuation amount of the discharge pressure data in the next target period becomes equal to or more than the reference fluctuation amount (or until the determination of Yes in S450). The operation of S440 to S470 is repeated. Then, when the fluctuation amount of the discharge pressure data becomes equal to or more than the reference fluctuation amount (S470: Yes), the determination unit 170 determines that cavitation has occurred (S480).

For example, during the detection target period from time t _n to time t _n + T in FIG. 2, the discharge pressure data changes so that the occurrence of cavitation is recognized, so that the fluctuation amount of the discharge pressure data is equal to or more than the reference fluctuation amount. Become. In this case, the determination unit 170 determines that cavitation has occurred and notifies the control system 70. As described above, the fluctuation amount calculation unit 160 according to the present embodiment discharges T having the same time length T as the detection target period immediately before the timing when the suction pressure data changes from the value indicating the positive pressure to the value indicating the negative pressure. The pressure data is used as the reference pressure data which is the data during the normal operation of the pump 40. The fluctuation amount of the discharge pressure data based on the reference pressure data and the discharge pressure data of the target period will be described below.

FIG. 5 shows an example of the fluctuation amount of the discharge pressure data calculated by the fluctuation amount calculation unit 160 in the present embodiment. In FIG. 5, the horizontal axis represents time and the vertical axis represents discharge pressure. FIG. 5 shows an example in which the fluctuation amount calculation unit 160 relatively shifts the time axes of the discharge pressure data and the reference pressure data. That is, FIG. 5 shows an example in which the start timing of the discharge pressure data and the reference pressure data is set to the time t ₀₁ and the end timing is set to the time t ₀₂ . The time t ₀₂ is a time when only the time T has elapsed from the time t ₀₁ .

Here, the fluctuation amount calculation unit 160 may adjust the offset of the discharge pressure data and the reference pressure data. For example, the fluctuation amount calculation unit 160 shifts the reference pressure data relative to the discharge pressure data during the detection target period, and sets the average value of the reference pressure data to the average value of the discharge pressure data during the detection target period. May match. Further, the fluctuation amount calculation unit 160 may perform a filtering process such as a high-pass filter to remove the DC component. Further, the suction pressure gauge 50 and the discharge pressure gauge 60 may supply the data obtained by performing the filtering process.

The fluctuation amount calculation unit 160 may calculate the difference between the discharge pressure data and the reference pressure data during the detection target period in which the average values are matched as the fluctuation amount. In FIG. 5, the shaded area is an example of the difference between the discharge pressure data and the reference pressure data. As shown in FIG. 5, even in the initial stage of cavitation in which the discharge pressure data during the detection target period changes, the difference between the discharge pressure data and the reference pressure data may be larger than the noise.

That is, the detection device 100 according to the present embodiment can detect the occurrence of cavitation by using the time waveform of the discharge pressure data even before the occurrence of clear vibration of a specific frequency or frequency band. can. Even the pressure data acquired from the plant 10 in the normal operating state may pulsate. For example, if the liquid flowing through the pump 40 is a mixture, pulsations may occur in the pressure data as the mixing ratio changes. In addition, pulsation may occur in the pressure data due to environmental changes in the plant 10. As described above, even the pressure data in the normal state may have a fluctuation range in a certain range. Therefore, as in the present embodiment, the period of the reference pressure data is substantially the same as the period T of the detection target period. By doing so, the influence of the swing width can be reduced.

Further, since the detection device 100 does not execute numerical processing such as Fourier transform, it can be realized at low cost without using a complicated circuit, a high-performance CPU, or the like. Further, since the detection device 100 sequentially compares the next data while deleting unnecessary data in the past, the storage capacity of the data can be reduced.

As described with reference to FIG. 5, the detection device 100 according to the present embodiment has described an example of comparing the time waveforms of the reference pressure data and the discharge pressure data having the same time length, but the present invention is limited to this. There is no. The detection device 100 may use the reference pressure data having a time length shorter than the time waveform of the discharge pressure data in the target period. In this case, the fluctuation amount calculation unit 160 may calculate the difference between the average value of the reference pressure data and the individual data of the discharge pressure data in the target period.

Further, the fluctuation amount calculation unit 160 uses one discharge pressure data acquired corresponding to the timing t ₀ when the suction pressure data changes from a value exceeding the threshold value to a value below the threshold value as reference pressure data. May be good. That is, the fluctuation amount calculation unit 160 may use the discharge pressure data acquired corresponding to the timing at which the suction pressure data changes from the value indicating the positive pressure to the value indicating the negative pressure as the reference pressure data. In this case, the fluctuation amount calculation unit 160 may calculate the difference between the reference pressure data of one sample and the individual data of the discharge pressure data in the target period.

As described above, the detection device 100 may use the discharge pressure data such as the period or time closer to the timing t ₀ when the suction pressure data changes from the value exceeding the threshold value to the value below the threshold value as the reference pressure data. desirable. As a result, the time difference between the reference pressure data and the discharge pressure data during the detection target period can be made shorter. That is, even if a pulsation occurs in the pressure data, the fluctuation range of the fluctuation generated in the reference pressure data and the discharge pressure data during the detection target period can be made the same, and the influence of the pulsation can be reduced.

Although it has been described that the detection device 100 according to the above embodiment can detect the occurrence of cavitation, the present invention is not limited to this. The detection device 100 may further predict the occurrence of cavitation. Further, the detection device 100 may provide information on maintenance and management of the pump 40. Such a detection device 100 will be described below.

FIG. 6 shows a modified example of the detection device 100 according to the present embodiment. In the detection device 100 of this modification, the same reference numerals are given to those substantially the same as the operation of the detection device 100 according to the present embodiment shown in FIG. 3, and the description thereof will be omitted. In the detection device 100 of this modification, the detection unit 130 further includes a forecast unit 210, a fluctuation amount storage unit 220, and a maintenance management unit 230.

The forecast unit 210 predicts the occurrence of cavitation of the pump 40 according to the suction pressure data becoming equal to or less than the threshold value. In this case, the comparison unit 150 notifies the fluctuation amount calculation unit 160 and the forecast unit 210 of the comparison result when the suction pressure data becomes equal to or less than the threshold value. For example, the forecasting unit 210 predicts the occurrence of cavitation in response to the change of the suction pressure data from the value indicating the positive pressure to the value indicating the negative pressure.

As described in FIG. 2, the suction pressure data taper off to negative pressure prior to the occurrence of cavitation. Therefore, the forecasting unit 210 can predict the occurrence of cavitation in the future depending on whether or not the value of the suction pressure data has changed to a negative pressure. As a result, the control system 70 can perform control for preventing the occurrence of cavitation, preparation for control for cavitation, and the like in advance before the occurrence of cavitation. Therefore, the control system 70 can reduce the occurrence of cavitation, and can promptly respond to the occurrence of cavitation.

In the present embodiment, an example in which the threshold value is set to a value corresponding to the atmospheric pressure has been described, but the present invention is not limited to this. Depending on the type, characteristics, individual differences of the pump 40, the design of the control system 70, etc., the values of the suction pressure data that should be judged to be prone to cavitation may differ, so the threshold value corresponds to these. It may be predetermined. Further, the comparison unit 150 sets different threshold values for the threshold value used when determining whether or not to notify the fluctuation amount calculation unit 160 and the threshold value used when determining whether or not to notify the forecast unit 210. May be good.

The fluctuation amount storage unit 220 calculates the cumulative value of the fluctuation amount of the discharge pressure data. The fluctuation amount storage unit 220 may receive the fluctuation amount calculated by the fluctuation amount calculation unit 160 and calculate the cumulative value. Further, the variable amount accumulating unit 220 may calculate a cumulative value for each occurrence of cavitation. In addition, the fluctuation amount accumulating unit 220 may also count the number of occurrences of cavitation, the duration, and the like. The variable amount storage unit 220 may store the accumulated cavitation information in the storage unit 140.

The maintenance management unit 230 determines at least one of the maintenance time and the replacement time of the pump 40 based on the cumulative value of the fluctuation amount of the discharge pressure data, the number of occurrences of cavitation, and / or the duration of cavitation. Since the cavitation generated in the pump 40 damages the pump 40, it is considered that the life of the pump 40 is affected. Since the fluctuation amount of the discharge pressure data corresponds to the amplitude intensity of the vibration of the cavitation, it can be used as an index of the damage received by the pump 40. Therefore, by accumulating and recording the fluctuation amount of the discharge pressure data, it is possible to determine the inspection timing and the replacement timing of the pump 40.

The maintenance management unit 230 determines the inspection timing and the replacement timing of the pump 40, for example, by comparing the cumulative value of the fluctuation amount of the discharge pressure data with a predetermined threshold value or the like. The maintenance management unit 230 may notify the control system 70 of the inspection timing and / or the replacement timing according to the cumulative value exceeding the threshold value. The maintenance management unit 230 may set the threshold value for determining the inspection timing and the threshold value for determining the replacement timing to different values. Further, the maintenance management unit 230 may set the threshold value in advance based on the data such as the failure of the pump 40 and the life of the pump 40 that actually occurred.

As described above, the detection device 100 according to the modified example can perform cavitation forecasting and maintenance and management of the pump 40 at low cost in addition to detecting cavitation. The detection device 100 may execute only the forecast of cavitation, or may execute only the maintenance and management of the pump 40.

The above-mentioned example of the detection device 100 according to the present embodiment has been described in which the calculation of the fluctuation amount of the discharge pressure data is started in response to the suction pressure data becoming equal to or less than the threshold value. As a result, the detection device 100 can omit unnecessary calculations and the like in the range where the suction pressure data is normal, and can prevent the power consumption from increasing. Further, since the detection device 100 can reduce the amount of calculation, even if it is mounted on the control system 70, it can be prevented from being affected as a load of the control system 70. Further, even if the detection device 100 is included in a measuring instrument such as a sensor provided in the plant 10, it is possible to prevent the detection device 100 from being affected as a load of these operations. Further, since the detection device 100 does not detect cavitation in the range where the suction pressure data is normal, the frequency of erroneous detection due to noise or the like can be reduced.

In consideration of such low power consumption and reduction of the frequency of erroneous detection, the detection device 100 is not limited to the comparison of time waveforms. For example, the detection device 100 may execute frequency analysis of the discharge pressure data according to the suction pressure data becoming equal to or less than the threshold value. In this case, the fluctuation amount calculation unit 160 may perform a Fourier transform on the discharge pressure data. Further, the determination unit 170 may determine whether or not an abnormality has occurred in a specific wavelength or a specific band in the frequency characteristics of the discharge pressure data. The determination unit 170 determines the occurrence of an abnormality using, for example, a predetermined threshold value for a specific wavelength or a specific band. As described above, the detection device 100 starts the frequency analysis when there is a tendency of cavitation, so that the amount of calculation can be reduced.

In this way, when the detection unit 130 executes the frequency analysis, the operation flow shown in FIG. 4 may be changed as follows. In S430, the fluctuation amount calculation unit 160 sets the frequency characteristic of the reference pressure data according to the suction pressure data becoming equal to or less than the threshold value. That is, the discharge pressure data acquired between the time t ₀ -T and the time t ₀ is read from the storage unit 140, the Fourier transform (FFT as an example) is executed, and the data is set as the reference data.

Further, in S460, when it is determined that the tendency of cavitation continues, the fluctuation amount calculation unit 160 calculates the frequency characteristic of the discharge pressure data in the detection target period. Then, the fluctuation amount calculation unit 160 calculates the difference between the frequency characteristic of the detection target period and the reference data on the frequency axis. Thereby, in S470, the determination unit 170 can determine the occurrence of an abnormality depending on whether or not a specific wavelength or a specific band of the frequency characteristic of the difference exceeds the threshold value.

Instead of this, the operation flow shown in FIG. 4 may be changed as follows. In S460, the fluctuation amount calculation unit 160 frequency-converts the waveform data of the difference between the discharge pressure data and the reference pressure data during the detection target period. Thereby, in S470, the determination unit 170 can determine the occurrence of an abnormality depending on whether or not a specific wavelength or a specific band of the frequency characteristic of the difference exceeds the threshold value.

Although it has been described that the detection device 100 according to the above embodiment detects cavitation by using the suction pressure data and the discharge pressure data, the present invention is not limited to this. If there is a margin in the power consumption of the plant 10, the calculation of the fluctuation amount of the discharge pressure data may be continued even in the range where the suction pressure data is normal. That is, the detection device 100 may detect cavitation using only the discharge pressure data.

For example, the detection device 100 may execute the calculation of the fluctuation amount of the discharge pressure data regardless of the change of the suction pressure data. In this case, the detection device 100 may not have the suction pressure acquisition unit 120 and the comparison unit 150. In this case, the detection unit 130 detects the occurrence of cavitation in the pump 40 based on the amount of fluctuation of the discharge pressure data during the detection target period. The detection unit 130 uses, for example, the discharge pressure data acquired when the operation of the pump 40 and / or the detection device 100 starts, as the reference pressure data.

Further, the detection unit 130 may use the discharge pressure data acquired in advance when the pump 40 is operating normally as the reference pressure data. Further, the detection unit 130 may use predetermined values such as a design value and an empirical value as reference pressure data.

As described above, when the detection device 100 calculates the fluctuation amount of the discharge pressure data regardless of the change of the suction pressure data, the operation flow shown in FIG. 4 may be changed as follows. That is, the operations of S420 and S450 regarding the suction pressure data are not executed. Further, in order to acquire the pressure data of S410 and S440, the discharge pressure acquisition unit 110 only needs to acquire the discharge pressure data. As a result, the detection device 100 can detect the occurrence of cavitation based on the time waveform of the discharge pressure data.

In this way, the detection unit 130 may detect the occurrence of cavitation in the pump based on the difference between the discharge pressure data during the detection target period and the discharge pressure data before the detection target period. In this case, the detection unit 130 may detect the occurrence of pump cavitation, for example, based on the difference between the discharge pressure data during the detection target period and the discharge pressure data immediately before the detection target period.

Since the fluctuation amount of the discharge pressure data gradually increases and deteriorates after the occurrence of cavitation, the detection device 100 can detect the occurrence of cavitation by comparing the discharge pressure data before and after the time. In this case, the operation flow shown in FIG. 4 may be further changed as follows. That is, in S470, when the fluctuation amount is less than the reference fluctuation amount (S470: No), the process returns to S430 instead of S440, the discharge pressure data in the target period is used as the reference pressure data, and then the discharge pressure data in the next target period is used. Acquire (S440).

As a result, the detection device 100 can detect the occurrence of cavitation by comparing the discharge pressure data before and after the time without using the suction pressure data. That is, the detection device 100 can detect the occurrence of cavitation with a simpler configuration. Further, the detection device 100 can detect a change in cavitation in real time.

Considering the detection of such a change in cavitation in real time, the detection device 100 is not limited to detecting the occurrence of cavitation by comparing the difference in time waveform with the reference fluctuation amount. For example, the detection device 100 may detect cavitation by frequency-converting the difference between the discharge pressure data during the detection target period and the discharge pressure data before the detection target period.

In this case, the fluctuation amount calculation unit 160 may calculate the difference between the discharge pressure data and the reference pressure data in the detection target period, and then Fourier transform the difference. The determination unit 170 may determine whether or not an abnormality has occurred in a specific wavelength or a specific band in the frequency characteristics calculated by the fluctuation amount calculation unit 160. The determination unit 170 determines the occurrence of an abnormality using, for example, a predetermined threshold value for a specific wavelength or a specific band. This operation can be realized by further modifying S460 and S470.

The above-mentioned detection device 100 according to the present embodiment has described an example of acquiring pressure data from a pressure gauge such as a suction pressure gauge 50 and a discharge pressure gauge 60. In addition to this, the detection device 100 may acquire failure information of the pressure gauge and the like from the suction pressure gauge 50 and / or the discharge pressure gauge 60. Since it is difficult to accurately detect the occurrence of cavitation when a failure or the like has occurred in the pressure gauge, the detection device 100 does not have to execute the detection of cavitation when the failure information or the like of the pressure gauge is acquired. .. Instead, the detection device 100 may add the failure information to the cavitation detection result and notify the control system 70.

The example in which the detection device 100 according to the present embodiment is provided in the plant 10 has been described. The plant 10 is an example of a system using a pump 40 for transferring a liquid, and the system provided with the detection device 100 is not limited to the plant 10. Since cavitation can occur in a pump 40 that transfers a liquid, a detection device 100 may be provided in a system, an apparatus, an apparatus, a site of use, or the like in which the pump 40 is used to detect cavitation.

FIG. 7 shows a configuration example of a computer 1200 in which a plurality of aspects of the present invention can be embodied in whole or in part. The program installed on the computer 1200 causes the computer 1200 to function as an operation associated with the device according to an embodiment of the present invention or as one or more "parts" of the device, or the operation or the one or more "parts". A unit can be run and / or a computer 1200 can be run a process according to an embodiment of the invention or a step in the process. Such a program may be executed by the CPU 1212 to cause the computer 1200 to perform a specific operation associated with some or all of the blocks of the flowcharts and block diagrams described herein.

The computer 1200 according to this embodiment includes a CPU 1212, a RAM 1214, a graphic controller 1216, and a display device 1218, which are interconnected by a host controller 1210. The computer 1200 also includes input / output units such as a communication interface 1222, a hard disk drive 1224, a DVD-ROM drive 1226, and an IC card drive, which are connected to the host controller 1210 via the input / output controller 1220. The computer also includes legacy input / output units such as the ROM 1230 and keyboard 1242, which are connected to the input / output controller 1220 via the input / output chip 1240.

The CPU 1212 operates according to the programs stored in the ROM 1230 and the RAM 1214, thereby controlling each unit. The graphic controller 1216 acquires image data generated by the CPU 1212 in a frame buffer or the like provided in the RAM 1214 or the graphic controller 1216 itself, and displays the image data on the display device 1218.

The communication interface 1222 communicates with other electronic devices via the network. The hard disk drive 1224 stores programs and data used by the CPU 1212 in the computer 1200. The DVD-ROM drive 1226 reads the program or data from the DVD-ROM 1201 and provides the program or data to the hard disk drive 1224 via the RAM 1214. The IC card drive reads the program and data from the IC card and / or writes the program and data to the IC card.

The ROM 1230 internally stores a boot program or the like executed by the computer 1200 at the time of activation, and / or a program depending on the hardware of the computer 1200. The input / output chip 1240 may also connect various input / output units to the input / output controller 1220 via a parallel port, a serial port, a keyboard port, a mouse port, and the like.

The program is provided by a computer-readable storage medium such as a DVD-ROM 1201 or an IC card. The program is read from a computer-readable storage medium, installed in a hard disk drive 1224, RAM1214, or ROM1230, which is also an example of a computer-readable storage medium, and executed by the CPU 1212. The information processing described in these programs is read by the computer 1200 and provides a link between the program and the various types of hardware resources described above. The device or method may be configured to implement the operation or processing of information in accordance with the use of the computer 1200.

For example, when communication is executed between the computer 1200 and an external device, the CPU 1212 executes a communication program loaded in the RAM 1214, and performs communication processing on the communication interface 1222 based on the processing described in the communication program. You may order. Under the control of the CPU 1212, the communication interface 1222 reads and reads transmission data stored in a transmission buffer area provided in a recording medium such as a RAM 1214, a hard disk drive 1224, a DVD-ROM 1201, or an IC card. The data is transmitted to the network, or the received data received from the network is written to the reception buffer area or the like provided on the recording medium.

Further, the CPU 1212 makes the RAM 1214 read all or necessary parts of the file or the database stored in the external recording medium such as the hard disk drive 1224, the DVD-ROM drive 1226 (DVD-ROM1201), and the IC card. Various types of processing may be performed on the data on the RAM 1214. The CPU 1212 may then write back the processed data to an external recording medium.

Various types of information, such as various types of programs, data, tables, and databases, may be stored on recording media for information processing. The CPU 1212 describes various types of operations, information processing, conditional judgment, conditional branching, unconditional branching, and information retrieval described in various parts of the present disclosure with respect to the data read from the RAM 1214. Various types of processing may be performed, including / replacement, etc., and the results are written back to the RAM 1214. Further, the CPU 1212 may search for information in a file, database, or the like in the recording medium. For example, when a plurality of entries each having an attribute value of the first attribute associated with the attribute value of the second attribute are stored in the recording medium, the CPU 1212 is the first of the plurality of entries. The attribute value of the attribute of is searched for the entry that matches the specified condition, the attribute value of the second attribute stored in the entry is read, and the attribute value of the second attribute is changed to the first attribute that satisfies the predetermined condition. You may get the attribute value of the associated second attribute.

The program or software module according to the above description may be stored on a computer 1200 or in a computer-readable storage medium near the computer 1200. Further, a recording medium such as a hard disk or RAM provided in a dedicated communication network or a server system connected to the Internet can be used as a computer-readable storage medium, whereby the program can be sent to the computer 1200 via the network. offer.

Although the present invention has been described above using the embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various changes or improvements can be made to the above embodiments. It is clear from the description of the claims that the form with such changes or improvements may be included in the technical scope of the present invention.

The order of execution of each process such as operation, procedure, step, and step in the apparatus, system, program, and method shown in the claims, specification, and drawings is particularly "before" and "prior to". It should be noted that it can be realized in any order unless the output of the previous process is used in the subsequent process. Even if the scope of claims, the specification, and the operation flow in the drawings are explained using "first", "next", etc. for convenience, it means that it is essential to carry out in this order. It's not a thing.

10 plants, 20 equipment, 30 liquid sources, 40 pumps, 50 suction pressure gauges, 60 discharge pressure gauges, 70 control systems, 100 detectors, 110 discharge pressure acquisition units, 120 suction pressure acquisition units, 130 detector units, 140 storage units. , 150 comparison unit, 160 fluctuation amount calculation unit, 170 judgment unit, 210 forecast unit, 220 fluctuation amount storage unit, 230 maintenance management unit, 1200 computer, 1201 DVD-ROM, 1210 host controller, 1212 CPU, 1214 RAM, 1216 graphic Controller, 1218 display device, 1220 I / O controller, 1222 communication interface, 1224 hard disk drive, 1226 DVD-ROM drive, 1230 ROM, 1240 I / O chip, 1242 keyboard

Claims (8)

A discharge pressure acquisition unit that acquires discharge pressure data indicating the discharge pressure of the pump,
A suction pressure acquisition unit that acquires suction pressure data indicating the suction pressure of the pump, and a suction pressure acquisition unit.
A detection unit that detects the occurrence of cavitation in the pump based on the amount of fluctuation in the time waveform of the discharge pressure data during the detection target period .
Equipped with
The detector is
A fluctuation amount calculation unit that calculates the difference between the discharge pressure data and the reference pressure data during the detection target period as the fluctuation amount,
A determination unit that determines that cavitation has occurred in the pump, provided that the calculated fluctuation amount is equal to or greater than the reference fluctuation amount.
Have,
The fluctuation amount calculation unit uses the discharge pressure data before the detection target period, which is acquired corresponding to the timing when the suction pressure data changes from a value exceeding the threshold value to a value below the threshold value, as the reference pressure. A detection device used as data . Claim 1 uses the discharge pressure data acquired corresponding to the timing at which the suction pressure data changes from a value indicating a positive pressure to a value indicating a negative pressure as the reference pressure data. The detection device described in. The detection device according to claim 1 or 2 , wherein the fluctuation amount calculation unit uses discharge pressure data having the same time length in the detection target period immediately before the timing as the reference pressure data. A discharge pressure acquisition unit that acquires discharge pressure data indicating the discharge pressure of the pump,
A detection unit that detects the occurrence of cavitation in the pump based on the amount of fluctuation in the time waveform of the discharge pressure data during the detection target period .
Equipped with
The detector is
A fluctuation amount calculation unit that calculates the difference between the discharge pressure data and the reference pressure data during the detection target period as the fluctuation amount,
A determination unit that determines that cavitation has occurred in the pump, provided that the calculated fluctuation amount is equal to or greater than the reference fluctuation amount.
Have,
The fluctuation amount calculation unit is
The reference pressure data is shifted relative to the discharge pressure data during the detection target period, and the average value of the reference pressure data is matched with the average value of the discharge pressure data during the detection target period.
The difference between the discharge pressure data and the reference pressure data during the detection target period in which the average values are matched is calculated as the fluctuation amount.
Detection device. The fluctuation amount accumulation part that calculates the cumulative value of the fluctuation amount, and
The detection device according to any one of claims 1 to 4 , further comprising a maintenance management unit for determining at least one of a maintenance time and a replacement time of the pump based on the cumulative value of the fluctuation amount. Acquiring discharge pressure data indicating the discharge pressure of the pump,
Acquiring suction pressure data indicating the suction pressure of the pump and
It is provided with detecting the occurrence of cavitation of the pump based on the fluctuation amount of the time waveform of the discharge pressure data during the detection target period .
The detection is
The difference between the discharge pressure data and the reference pressure data during the detection target period is calculated as the fluctuation amount, and
It is determined that cavitation has occurred in the pump on condition that the calculated fluctuation amount is equal to or more than the reference fluctuation amount.
Have,
To calculate the fluctuation amount, the discharge pressure data before the detection target period, which is acquired corresponding to the timing when the suction pressure data changes from a value exceeding the threshold value to a value below the threshold value, is used. Detection method used as reference pressure data . Acquiring discharge pressure data indicating the discharge pressure of the pump,
It is provided with detecting the occurrence of cavitation of the pump based on the fluctuation amount of the time waveform of the discharge pressure data during the detection target period .
The detection is
The difference between the discharge pressure data and the reference pressure data during the detection target period is calculated as the fluctuation amount, and
It is determined that cavitation has occurred in the pump on condition that the calculated fluctuation amount is equal to or more than the reference fluctuation amount.
Have,
To calculate the fluctuation amount
The reference pressure data is shifted relative to the discharge pressure data during the detection target period, and the average value of the reference pressure data is matched with the average value of the discharge pressure data during the detection target period.
A detection method for calculating the difference between the discharge pressure data and the reference pressure data during the detection target period in which the average values are matched as the fluctuation amount . A program that causes a computer to function as the detection device according to any one of claims 1 to 5 .

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