Patent Application
20190390665
The present invention relates to the diagnosis of malfunctioning components in reciprocating compressors via the detection of particular vibration signals. More specifically, but not by way of limitation, the present invention relates to the use of knock sensors for detecting certain vibrational responses in reciprocating compressors for diagnosing particular operating conditions or malfunctioning components.
Reciprocating compressors are used in many industries, including oil refineries, gas pipelines, chemical plants, natural gas processing plants and refrigeration plants. For example, to transport natural gas from production sites to consumers, pipeline operators install large compressors at transport stations along the pipelines. Natural gas pipeline networks connect production operations with local distribution companies through thousands of miles of gas transmission lines. Typically, reciprocating gas compressors are used as the prime mover for pipeline transport operations because of the relatively high pressure ratio required. Reciprocating compressors compress fluid using a piston in a cylinder connected to a crankshaft 13. Crankshaft 13 may be driven by a motor or an engine. A suction valve in the compressor cylinder receives input gas, which is then compressed by the piston and discharged through a discharge valve.
A specific challenge when using high-horsepower, high-speed, variable-speed compressors is failure of the compressor valves. A common type of valve used for reciprocating compressors is a plate-type compressor valve (or “plate valve”). These valves experience high plate impact velocities that often result in fatigue or crack failures and a short operating life, leading to frequent valve replacement. As discussed more below, such valves may exhibit a “flutter” during operation, which negatively impacts performance and may be indicative of defective components within the valve. It would be beneficial to accurately detect such malfunctions and defects so that valve components could be repaired or replaced to avoid costly failures and/or improve compressor performance. For example, a cost-effective way to detect valve flutter in reciprocating compressors may be leverage to improve performance, lower maintenance costs, and extend machine life.
The present application describes a diagnostic system for use with a compressor system having a compressor cylinder. The diagnostic system may include a sensor configured to measure a vibration signal of the compressor cylinder; and a controller having a hardware processor and a machine-readable storage medium on which is stored instructions that cause the hardware processor to execute a diagnostic process. The diagnostic process may include the steps of: storing a signature vibration data; receiving a sample vibration data from the sensor, wherein the sample vibration data is representative of the vibration signal measured by the sensor over an operating period; comparing the sample vibration data to the signature vibration data to determine a similarity therebetween; and based on the determined similarity, diagnosing that the compressor cylinder has a condition. The signature vibration data may include resonance bands clustered within resonance band groups, each of the resonance band groups including a primary resonance band adjacent to a secondary resonance band.
These and other features of the present application will become apparent upon review of the following detailed description of the preferred embodiments when taken in conjunction with the drawings and the appended claims.
These and other features of this invention will be more completely understood and appreciated by careful study of the following more detailed description of exemplary embodiments of the invention taken in conjunction with the accompanying drawings, in which:
One or more specific embodiments of the present invention will be described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure. As will be seen, the techniques described herein include systems and methods in which knock sensors and the like are used to detect a dynamic response of engine components during the operations of a reciprocating compressor. For example, signals from a knock sensor may be collected and analyzed for diagnosing health and operational fitness related plate valves.
Turning to the drawings,
Controller 14 is used to monitor and control operating parameters affecting compressor load and capacity, as well as other functions that will be discussed more below. As indicated, controller 14 may be equipped with a hardware processor 15 and memory 16 (e.g., non-transitory computer readable medium), as well as appropriate input and output devices, and a user interface. Controller 14 may be programmed to perform the various control tasks and deliver control parameters to compressor system 10. Given appropriate input data, output specifications, and control objectives, algorithms for programming controller 14 may be developed and executed. Controller 14 may electronically communicate with sensor 19 and receive data therefrom.
According to exemplary embodiments, sensor 19 is one suitable for detecting noise or vibrational response within compressor system 10 and/or compressor cylinder 12 during operation. For example, sensor 19 may be a conventional knock sensor. More generally, sensor 19 may be any other conventional sensor configured to sense vibration, sound, acceleration, and/or movement caused by the operation of compressor cylinder 12, for example, a Piezo-electric accelerometer, microelectromechanical system sensor, Hall effect sensor, magnetostrictive sensor, etc. As will be seen, sensor 19 may be used to detect a variety of noise or vibration signals for comparison to a signature of vibration data (or “signature vibration data”) that, in accordance with embodiments of the present invention, has been found to correlate to particular valve condition or defect. For example, in one embodiment, a current vibration signal or data sample may be analyzed to determine if it contains the signature vibration data, which then is used to determine whether the corresponding defect or malfunction is likely present within compressor cylinder 12. To do this, sensor 19 may be disposed within compressor system 10. For example, according to preferred embodiments, sensor 19 is attached to compressor cylinder 12. Because of the percussive nature of valve operation within compressor cylinder 12, sensor 19 may be capable of efficiently detecting and measuring vibration signals when positioned in this way. In some embodiments, a single sensor 19 may be used, whereas, in other embodiments, each compressor cylinder 12 may include one or more sensors 19. Sensor 19 is shown communicatively coupled to controller 14. During operations, vibration data representative of the vibration signal measured by sensor 19 is communicated to controller 14 for analysis thereby.
In the example of
In an example of operation, plate valve 20 begins in a closed state. In this state, fluid flow in one direction is prevented as sealing plate 23 is held by springs 24 against sealing surfaces of seat 21. When the differential of pressures acting upon the two sides of sealing plate 23 overcomes the force of springs 24 holding it against seat 21, valve 20 begins to open as sealing plate 23 dislodges from seat 21, which allows gas to start flowing through the passages of sealing plate 23. Opening further, sealing plate 23 continue its movement away from seat 21 until such movement is prevented when sealing plate 23 impacts guard 22. It is desirable for sealing plate 23 to settle upon guard 22 so that valve 20 quickly attains a fully open state. However, for a variety of reasons, the impact with guard 22 may result in sealing plate 23 bouncing or fluttering so that repeated impacts, which generally decrease in size, occur before sealing plate 23 settles against guard 22 and the fully open state is achieved. The process then reverses when the differential of pressures acting upon the two sides of sealing plate 23 is overcome by the force of springs 24. When this happens, sealing plate 23 dislodges and moves away from guard 22. This movement is then finally arrested when sealing plate 23 impacts seat 21. As before, it is desirable for sealing plate 23 to quickly settle against seat 21 so that the fully closed state is quickly attained. However, the impact against seat 21 also may result in sealing plate 23 bouncing or fluttering before properly coming to rest.
In this way, sealing plate and the associated springs within a plate valve constitute a potentially oscillating system, with the excitation necessary to give rise to such oscillations being provided by the interaction of this system with the flow and the alternating impacts occurring between the sealing plate and the seat/guard components. When the oscillation of the sealing plate is excessive, it is referred to as “valve flutter” or, simply, “flutter”. Flutter is an undesirable condition as it can lead to premature valve plate failures, degraded seals, and poor performance. Further, flutter often is an indicator that components within the plate seal are not functioning properly due to some defect or degradation. For example, flutter within such valves can indicate that springs are worn or not sized properly or that the seal plate is cracked or excessively fatigued. As will be appreciated, early diagnosis of such flutter is advantageous in that corrective action can be taken to improve performance and avoided component failure.
Turning now to
In regard to
Referring now to
According to the present disclosure, certain aspects of amplitude curve 94 of
A first of these characteristics is the presence of what will be referred to herein as resonance bands. Instead of the more regular amplitude data shown in
Further, between occurrences of resonance band groups 104, the signature vibration data may have an intervening signal 95, which is characterized by a more regular amplitude, which is significantly lower than an amplitudes of the included resonance bands 100. That is, between resonance bands groups 104, the amplitude of the vibration data may return to a more regular pattern, such as that shown in
When amplitude curve 94 is compared to plate position curve 96, it is seen that resonance bands 100 generally coincide with the transition from closed state 98 to open state 99 and that resonance bands 100 occur primarily during open state 99. It should be appreciated that, depending on the behavior of the system, a sealing plate could exhibit fluttering when transitioning from open state 99 to closed state 98 (i.e., when the sealing plate impacts the seat during closing, instead of the guard during opening). In such cases, resonance bands 100 and resonance band groups 104 would coincide with this transition and, thus, would occur primarily within closed state 98 of the valve. It should be understood that the techniques described herein are applicable to diagnosing flutter in either situation.
For example, according to an embodiment of the present disclosure, diagnostic process 110 may include an initial step 115 at which a signature vibration data is stored, for example, within memory 16 of controller 14. The signature vibration data, for example, may include resonance bands clustered within resonance band groups, as already described. At a step 120, process 110 may include receiving, for example, at controller 14, a sample vibration data from sensor 19, where the sample vibration data is representative of the vibration signal measured by sensor 19 over a particular operating period. At a step 125, diagnostic process 110 may include comparing the sample vibration data against the signature vibration data to determine a similarity therebetween. Then, at a step 130, based on the determined similarity, diagnostic process 110 may include diagnosing that the compressor cylinder does or does not have a particularly condition. As described in detail above, the condition may be valve flutter or flutter, e.g., the bouncing or fluttering of a sealing plate within a plate valve. Alternatively, the diagnosed condition may be that there is an increased likelihood that the sealing plate is fluttering within the plate valve.
At a step 135, diagnostic process 110 may further include providing an alert regarding the diagnosed condition. For example, controller 14 may prepare an electronic communication regarding valve flutter or increased likelihood of valve flutter and the particular compressor cylinder for which the test results apply. The electronic communication, such as email, text, and the like, may then be transmitted to a user device (e.g., computer, phone, tablet) of a specified person, such as an operator, associated with the maintenance of the compressor system.
Technical effects of the invention include detecting vibrations via certain sensors, such as knock sensors, within compressor cylinders and diagnosing valve defects and actions related to such diagnoses, i.e., the sending of alerts. It should be understood that the many varying features and configurations described above in relation to the several exemplary embodiments may be further selectively applied to form other possible embodiments of the present invention. For the sake of brevity and taking into account the abilities of one of ordinary skill in the art, all possible iterations are not provided or discussed in detail, though all combinations and possible embodiments embraced by the several claims below or otherwise are intended to be part of the present application. For instance, features illustrated or described as part of one embodiment may be used on another embodiment to yield a still further embodiment. In addition, from the above description of several exemplary embodiments of the invention, those skilled in the art will perceive improvements, changes and modifications. Such improvements, changes and modifications within the skill of the art are intended to be covered by the appended claims. Numerous changes and modifications may be made to the exemplary embodiments provided herein without departing from the spirit and scope of the application as defined by the following claims and the equivalents thereof.
