Pump Monitoring Using Acoustical Characterizations

Abstract

An audio detection unit inside of the pump can be used to capture acoustic waveforms from the pump during operation and, when compared to characterized data, can accurately determine an operating condition of the pump. Such operating conditions can include whether the pump is operating as expected, if it has lost prime, if it has a failure, or if it can be determined that failure is likely to occur in the near future.

Description

TECHNICAL FIELD

The present disclosure is directed to an apparatus and method to monitor a metering pump using acoustical characterizations.

BACKGROUND OF THE INVENTION

Metering pumps are typically used to move a specified volume of liquid in a specified time to provide an accurate flow rate. Many precision metering pumps use a flexible diaphragm mechanism and checkball configuration to transfer fluid from a source tank to a process fluid tank for treatment. During a suction stroke, the diaphragm and checkball(s) generally create a negative pressure scenario that lifts the fluid from the source tank into the suction tube toward the suction end of the pump. During the discharge stroke, the diaphragm and checkball(s) generally create a positive pressure differential to move the fluid towards the discharge end of the pump. The amount and speed of fluid movement through the tubing is primarily dependent on the diaphragm displacement during each stroke cycle and the rate of cycling the diaphragm between suction and discharge positions. Such metering pumps can pump chemicals, solutions, or other liquids.

Metering pumps typically require intermittent service and routine maintenance to ensure proper operation and minimize downtime. Certain maintenance is performed in a preventative fashion to counteract failure, whereas other service may be required post-failure. Ideally, any service will be performed prior to failure in the field to ensure proper treatment of process fluids and effective plant operation. Accordingly, there is a need to provide an easier and more efficient method to detect maintenance conditions for metering pumps.

Additionally, metering pumps may experience a loss of prime condition. The initial priming sequence of the pump is the process of filling the injection tubing with fluid. Typically, this process takes several pumping cycles to fill the tubing adequately prior to being able to inject fluid into the process fluid tank. In some instances, diaphragm metering pumps may be subject to a loss of prime condition where the tubing is not filled with liquid, and air or gas has built up in the cavity. During a loss of prime condition, the pressure vacuum in the tubing may be lost and the fluid may reverse flow from the tubing back into the source tank. This may particularly occur in low duty cycle pumping applications or if the pump is turned off for an extended amount of time. When prime is lost in the system, the air can be removed and replaced with liquid to re-prime the system through suction/discharge strokes of the metering pump. However, this re-priming requires manual intervention, and may be time consuming and may result in under treating the process fluid. Accordingly, there is also a need to provide an easier and more efficient method to detect a loss of prime condition for metering pumps.

BRIEF SUMMARY OF THE INVENTION

An audio detection unit inside of the pump can be used to capture acoustic waveforms from the pump during operation and, when compared to characterized data, can accurately determine if a pump is operating as expected, if it has lost prime, if it has a failure, or if it may be determined that failure is likely to occur in the near future.

In one embodiment, a method of detecting an operating condition of a pump may comprise detecting an acoustic waveform emitted by the pump during operation of the pump; determining an acoustic characteristic of the acoustic waveform; and comparing the acoustic characteristic with a predetermined acoustic characteristic.

Another method of detecting an operating condition of a pump may comprise detecting an acoustic waveform of the pump during operation by an audio detection unit within the pump; determining an acoustic characteristic of the acoustic waveform; comparing the acoustic characteristic with a predetermined acoustic characteristic; and determining the operating condition of the pump based on the compared acoustic characteristic.

A pump may comprise a mechanical drive unit comprising a drive mechanism; a liquid end comprising a diaphragm, wherein the drive mechanism is configured to translate the diaphragm; an electronic drive unit coupled with the mechanical drive unit such that the electronic drive unit is configured to operate the mechanical drive unit; and an audio detection unit positioned within the pump configured to detect audible noise emitted by the pump during operation, wherein the audio detection unit is coupled with the electronic drive unit such that the electronic drive unit is configured to receive the detected audible noise from the audio detection unit.

The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims. The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:

FIG. 1A depicts a schematic of a metering pump system.

FIG. 1B depicts a schematic of the metering pump system of FIG. 1A in a primed configuration.

FIG. 2 depicts a schematic of a pump for use with the metering pump system of FIG. 1A.

FIG. 3 depicts a schematic of an acoustic waveform of the pump of FIG. 2 running at a normal condition.

FIG. 4 depicts a schematic of another acoustic waveform of the pump of FIG. 2 in a loss of prime condition.

FIG. 5 depicts a schematic of another acoustic waveform of the pump of FIG. 2 in a stalled condition.

FIG. 6 depicts a schematic of a method of operating the pump of FIG. 2 based on an acoustic waveform of the pump.

FIG. 7 depicts a schematic of a display screen for displaying conditions of the pump of FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIG. 1A, an exemplary system using a metering pump is described. Metering pump system (10) for pumping a specified volume of liquid in a specified time includes a storage tank (2), a metering pump (50), and a process fluid tank (8). The metering pump (50) is fluidly coupled with the storage tank (2) by suction tubing (4), and the metering pump (50) is fluidly coupled with the process fluid tank (8) by injection tubing (6). Accordingly, the metering pump (50) can be operated to pump fluid from the storage tank (2) to the process fluid tank (8), as shown in FIG. 1B, in a specified time at a desired flow rate. The initial priming sequence of the pump (50) is the process of filling the tubing (4, 6) with fluid to a primed condition shown in FIG. 1B. Typically, this process takes several pumping cycles to fill the tubing (4, 6) adequately prior to being able to inject fluid into the process fluid tank (8). Although any type of metering pump can be incorporated into the metering pump system (10) to pump any type of fluid (i.e., chemicals, solutions, water, etc.), a diaphragm metering pump will be discussed in more detail below.

I. An Embodiment of a Pump

Referring to FIG. 2, a mechanical pump (50) for use with the metering pump system (10) includes a mechanical drive unit (54) that can comprise a drive mechanism such as a piston or solenoid and clapper assembly. The mechanical drive unit (54) is used to move a diaphragm in a liquid end (56) to create pressure differentials in a pumping chamber which alternately draws in fluid and expels fluid from the pumping chamber. An electronic drive (52), which can also be referred to as control electronics, both controls the operation of the mechanical drive unit (54) and include sensors to monitor the status of the pump (50). As a result of their normal operation, mechanical pumps make audible noise (51) during operation. The current operation of the pump (50) can be determined based on the audible sounds it is emitting and comparing that to historical audible patterns of the pump (50).

An audio detection unit (60) inside of the pump (50) can be used to capture the acoustic waveforms and, when compared to characterized data, can accurately determine if a pump (50) is operating as expected, if it has lost prime, if it has a failure, or if it may be determined that failure is likely to occur in the near future. The audio detection unit (60) may include, but is not limited to a microphone, a sound level meter, an integrating sound level meter, and a noise dosimeter. One or more audio detection units (60) may be placed at any select one or more positions within the pump (50). For instance, an audio detection unit (60) may be positioned near or in between any of the electronic drive (52), mechanical drive (54), and/or the diaphragm in the liquid end (56) of the pump (50). Still other suitable configurations for the audio detection units (60) will be apparent to one with ordinary skill in the art in view of the teachings herein.

In an attempt to identify potential problems on pumps, historically a multitude of sensors would be attached to detect changes from normal behavior. Such sensors may include thermal sensors, current meters, accelerometers, gyroscopes, etc. Acoustic detection can be as reliable as having precision sensors applied at a much lower cost, with a smaller footprint, and not require direct coupling to monitored elements.

A. Normal Condition of the Pump

Some examples of acoustic waveforms that may be detected by the audio detection unit (60) in the pump (50) are shown in FIGS. 3-5 for illustrative purposes. While these examples are based on data collected from a solenoid-driven pump, the methodology could apply to other drive technologies, such as brushless DC, stepper motor, induction, etc. For instance, FIG. 3 shows an acoustic waveform (70) of a pump (50) running at normal conditions. Such normal conditions may include operating the pump to sufficiently and/or accurately pump to pump fluid from the storage tank (2) to the process fluid tank (8). This waveform (70) comprises waveform characteristics that may include, but is not limited to, a waveform shape, a period, an amplitude, noise levels, and slope. In the illustrated embodiment, the acoustic waveform (70) comprises two acoustic bursts for each stroke. The first acoustic burst (70a) has a shorter amplitude, such as between about +/−0.5 decibels from a reference level, and a shorter duration of time, such as about 0.05 seconds. This first acoustic burst (70a) represents the discharge stroke of the pump (50). The second acoustic burst (70b) has a larger amplitude, such as between about +/−1 decibel from a reference level, and a longer duration of time, such as about 0.1 seconds. The second acoustic burst (70b) represents a good suction stroke. The electronic drive (52) of the pump (50) may command the stroke, allowing the electronic drive (52) to align each acoustic burst with the corresponding commanded action. Of course, the waveform (70) can have varying shapes, periods, amplitudes, and/or noise levels, and/or other suitable waveform characteristics. The waveform characteristics for an acoustic waveform (70) of a pump (50) running at normal conditions may vary based on the type of pump, selected speed, system backpressure, operating temperature, chemical viscosity, altitude of the pump (50) and/or other operating characteristics.

Such normal operating conditions of the pump (50) can be characterized for a selected pump (50). For instance, the pump (50) may be set to a desired pump load with the electronic drive (52) and the resulting acoustic waveform (70) of the pump (50) may be detected by the audio detection unit (60). By monitoring the acoustic waveform (70), any repeatable and/or load dependent waveform characteristics can be identified. The measured data can be stored, such as by the electronic drive (52). The waveform characteristics can then be analyzed. For instance, the waveform shape, period, amplitude, noise levels and/or slope of the waveform (70) can be measured and stored to identify pump scenarios. From the monitored waveforms, a typical acoustic waveform (70) for normal operating conditions can be determined. A sample of pumps (50) may be used for comparison purposes to characterize a typical waveform (70) for a pump (50) over a select duration of time. Still other suitable methods for determining a characterized acoustic waveform (70) for normal conditions of a pump (50) will be apparent to one with ordinary skill in the art in view of the teachings herein.

B. Maintenance Condition of the Pump

In addition to varying over different operating conditions, the acoustic signature or waveform (70) of a ‘normal’ operating pump will also adjust over time as certain parts wear, friction increases, or seals deteriorate. Certain common maintenance items may be immediately recognized based on its acoustic signature. Just as a trained auto mechanic can listen to an engine to pin point problems, an audio detection unit (60) in a pump (50) can quickly identify sounds associated with common problems. Because an audio detection unit (60) can assist in capturing the acoustic waveforms, it will be easier and more reliable to identify subtle changes and identify problems before they become catastrophic as opposed to relying on a human ear or noticing drastic changes in performance. This continues to become increasingly more reliable as the number of units in the field increase so that anomalies and characteristics across a very large sample can be used to compare behaviors. Preventative maintenance items that are identified can then be relayed to the operator, service partner, or distributor to ensure parts and maintenance is provided prior to failure resulting in down-time. The data captured from the install base may be uploaded to a central database and utilize data science or machine learning to automatically identify typical pump acoustic signatures.

Utilizing known acoustic signatures or waveforms associated with failures is one method to detect problems. Another method is detecting any deviation from a normal operating mode signature (70). A learning algorithm can be implemented to analyze logged data from different pump installations to identify the acoustic signature or waveform (70) of normal operation. The pump (50) can then monitor for any deviation from the normal signature (70) and alert the user of the potential for required maintenance. For instance, a weakening diaphragm of the pump (50) may become less rigid, causing the acoustic waveform of the pump (50) to have a lower amplitude on the first acoustic burst (70a). Loose bolts can alter the acoustic signal of the pump as they vibrate or rattle, further loose bolts on the liquid end (56) can expand the fluid cavity and change the volume of fluid being pumped which might also change the acoustic signature as the walls for reflecting soundwaves are shifted. Bearing wear on motor-driven pumps can also be detected with acoustic signature as the rough or non-uniform surfaces worn bearings will generate more noise than smooth bearing resulting in additional detectible frequencies being emitted by rotating mechanisms. Still other types of maintenance or pump conditions may be detected based on monitoring the acoustic waveform of the pump (50), as will be apparent to one with ordinary skill in the art in view of the teachings herein.

If a pump acoustic waveform is trending away from normal operating mode over time in a manner that is atypical or unexpected it may be indicative that something is wrong with that particular unit. This can alert the operator, service partner, or distributor that the pump should be inspected. If a problem is identified, this can be logged as potentially exhibiting this particular acoustic signature. As future pumps have this same problem and if they exhibit similar acoustic behaviors, this signature can be assigned to this problem. Once assigned, this identification can be added to all pump models so that if any pump exhibits this behavior in the future, the operator can be notified immediately of the problem and steps to resolve. Accordingly, if a maintenance condition of the pump (50) is detected based on a deviation of the acoustic waveform of the pump (50) compared to the acoustic waveform (70) of the pump (50) at normal operation, the pump (50) can be programmed to alert the user of the potential maintenance condition and/or the pump (50) can change the operation of the pump (50) such as by reducing the speed of the pump (50) or shutting down the pump (50). Still other suitable actions may be used.

C. Loss of Prime Condition of the Pump

Because it may be desirable to maintain fluid in the tubing (4, 6) of the pumping system (10) such that the pump (50) is in a primed condition, an automatic prime detection function is provided by monitoring the acoustic characteristics of the pump (50). For instance, FIG. 4 shows an acoustic waveform (72) of a pump (50) running in a loss of prime condition. This waveform (72) comprises waveform characteristics that may include, but is not limited to, a waveform shape, a period, an amplitude, noise levels, and slope. In the illustrated embodiment, the acoustic waveform (72) comprises two acoustic bursts for each stroke. The first acoustic burst (72a) corresponding to the discharge stroke of the pump (50) has a higher amplitude than when fluid is present during normal conditions because there is no resistance on the discharge stroke. The second acoustic burst (72b) corresponding to the suction stroke of the pump (50) has a shorter duration of time than when fluid is present during normal conditions. Accordingly, the acoustic waveform (72) can be characterized as a loss of prime condition of the pump (50).

If a loss of prime condition is detected, the pump (50) can automatically re-prime the system by maximizing the stroke speed of the pump (50) for a selected amount of time. If the acoustic waveform of the pump returns to the acoustic waveform (70) corresponding to normal operation, the pump (50) can continue normal operation. If the acoustic waveform of the pump (50) remains at the acoustic signature for a loss of prime condition, the pump (50) can alert the user of the loss of prime condition and/or the pump (50) can change the operation of the pump (50) such as by reducing the speed of the pump (50) or shutting down the pump (50). Still other suitable actions may be used.

D. Stalled Condition of the Pump

An example of an acoustic waveform (74) of a pump (50) running in a stalled condition is shown in FIG. 5. Accordingly, if the pump (50) is in a stalled state, meaning that the pump (50) while trying to move liquid to the process tank out of its output port cannot overcome the back pressure exerted on the pump at the output, it will have an acoustic signature similar to the “stalled” acoustic signature shown. A stalled pump might occur due to blockage or a stuck valve or simply high back pressure in the process tank. As shown in the illustrated embodiment, the acoustic waveform (74) has only one acoustic burst (74a) per stroke. Because the discharge stroke is unable to finish, only the suction stroke is audible. Accordingly, the acoustic waveform (74) can be characterized as a stalled condition of the pump (50). If stalled condition is detected, the pump (50) can alert the user of the stalled condition and/or the pump (50) can change the operation of the pump (50) such as by reducing the speed of the pump (50) or shutting down the pump (50). Still other suitable actions may be used.

II. Operation of the Pump

By detecting that the acoustic signature of the pump (50) has deviated from a normal condition, such as to a maintenance condition, a loss of prime condition, and/or a stalled condition, it can be accurately detected that the pump (50) is no longer sufficiently injecting chemical into the process fluid (8). Referring to FIG. 6, this detection can be determined by detecting an acoustic waveform of the pump (50), such as by the audio detection unit (60) within the pump (50). An acoustic characteristic of the detected acoustic waveform may then be determined or calculated. Such an acoustic characteristic may include, but is not limited to, a waveform shape, a period, an amplitude, an acoustic burst, noise levels, and slope. The calculated acoustic characteristic may then be compared with a predetermined acoustic characteristic of the pump (50). Such a predetermined acoustic characteristic may correspond to an acoustic characteristic of the pump (50) in normal operating conditions. This predetermined acoustic characteristic may be theoretical or measured from one or pumps (50) over a duration of time. The comparison between the calculated acoustic characteristic and the predetermined acoustic characteristic may be used to determine whether the calculated acoustic characteristic has deviated from the predetermined acoustic characteristic. For example, the system may be programmed to detect any change greater than a predetermined percentage from a nominal value, or the system may require that it remain outside a safety range for a certain period of time before identifying that it's problematic. The system may also be programmed to detect a gradual change over time so measurement to measurement may be within x % but when looking at a longer time period that a problem can be identified as the acoustic signature has slowly deviated from the expected point. Other mechanisms or combinations of any of the mechanisms can also be used to determine a deviation that requires action.

This awareness by the pump (50) may alert the operator via an alarm, text message, email, or similar. The pump (50) may also attempt to self-correct the issue by entering an auto-priming mode (where the pump increases speed to maximum) until it detects the acoustic signature that the pump has returned to normal operation. Other suitable methods for operating a pump (50) based on an acoustic characteristic of the pump (50) will be apparent to one with ordinary skill in the art in view of the teachings herein.

Another use for the acoustic characterization data may be to optimize the pump efficiency. For instance, the electronic drive (52) may be used to decrease the drive current until a stall threshold is detected as described above. Using this threshold as a lower limit, the electronic drive (52) may increase the drive current by a set margin and continuously monitor the acoustical nature until the electronic drive (52) detects that the pump (50) is operating reliably. This may allow the pump (50) to operate more efficiently by using only a sufficient amount of power required to drive the pump (50) and dynamically adapt to changing system backpressure, operating temperature, and/or chemical viscosity.

In some instances, a backpressure estimation can be calculated based on the amount of time needed to discharge the fluid and the drive current needed to overcome the system backpressure. Accordingly, the amount of time needed to discharge the fluid can be determined by the electronic drive (52) from the acoustic waveform detected by the audio detection unit (60) by calculating the duration of the first acoustic burst of the pump (50). The backpressure estimation can then be displayed on the pump screen (80), as shown in FIG. 7. The backpressure estimation can also be used to adjust the estimated flow rate of the pump (50), which is a function of backpressure. A backpressure calibration can be performed by the user or in the factory to run the pump (50) at two different backpressures. The pump output can thereby be dynamically adjusted to speed up the pump (50) in high pressure situations to maintain the user-selected flow rate.

Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.

Claims

1. A method of detecting an operating condition of a pump comprising: detecting an acoustic waveform emitted by the pump during operation of the pump;comparing the acoustic waveform with a signature waveform, the signature waveform representing normal operation; and generating an alert when the acoustic waveform deviates from the signature waveform.

2. The method of claim 1, wherein the acoustic waveform is detected by an audio detection unit inside of the pump.

3. The method of claim 1, wherein comparing the acoustic waveform comprising comparing one or more acoustic characteristics of the acoustic waveform, the one or more acoustic characteristics including one or more of an acoustic burst, an amplitude, a duration, a shape, and a period of the acoustic waveform.

4. The method of claim 3, wherein the predetermined acoustic characteristic is based on an acoustic characteristic determined from an acoustic waveform of the pump operating in a normal condition over a select duration of time.

5. The method of claim 1, further comprising sending the alert to a user.

6. The method of claim 1, further comprising adjusting the operation of the pump if the acoustic waveform deviates from the signature waveform.

7. The method of claim 1, further comprising determining a maintenance condition of the pump when the acoustic waveform deviates from the signature waveform.

8. The method of claim 1, further comprising determining a loss of prime condition when the acoustic waveform deviates from the signature waveform.

9. The method of claim 8, further comprising increasing a stroke speed of the pump for a select amount of time when the loss of prime condition is determined.

10. The method of claim 1, further comprising determining a stalled condition when the acoustic waveform deviates from the signature waveform.

11. A method of detecting an operating condition of a pump comprising: detecting an acoustic waveform of the pump during operation by an audio detection unit within the pump;determining an acoustic characteristic of the acoustic waveform;comparing the acoustic characteristic with a predetermined acoustic characteristic; anddetermining the operating condition of the pump based on the compared acoustic characteristic.

12. A pump comprising: a mechanical drive unit comprising a drive mechanism;a liquid end comprising a diaphragm, wherein the drive mechanism is configured to translate the diaphragm;an electronic drive unit coupled with the mechanical drive unit such that the electronic drive unit is configured to operate the mechanical drive unit; andan audio detection unit positioned within the pump configured to detect audible noise emitted by the pump during operation, wherein the audio detection unit is coupled with the electronic drive unit such that the electronic drive unit is configured to receive the detected audible noise from the audio detection unit.

13. The pump of claim 12, wherein the audio detection unit comprises a microphone.

14. The pump of claim 12, wherein the audio detection unit is positioned near a select one or both of the liquid end and the mechanical drive unit.

15. The pump of claim 12, wherein the detected audible noise comprises an acoustic waveform.

16. The pump of claim 15, wherein the electronic drive unit is operable to compare the acoustic waveform with a characterized acoustic waveform.

17. The pump of claim 16, wherein the electronic drive is operable to determine an operating condition of the pump.

18. The pump of claim 17, wherein the operating condition comprises a select one or more of a normal condition, a loss of prime condition, a maintenance condition, and a stalled condition.

19. The pump of claim 17, wherein the electronic drive is operable to alert a user of the determined operating condition.

20. The pump of claim 17, wherein the electronic drive is operable to adjust the drive mechanism based on the determined operating condition.