A natural gas reciprocating compressor valve fault diagnosis method and program product

Abstract

The present application relates to the technical field of oil and gas field mobile equipment online monitoring and diagnosis, in particular to a natural gas reciprocating compressor valve fault diagnosis method and program product, the method comprising determining the process parameters of the reciprocating compressor; calculating the pressure correction coefficient, determining the compression process curve, the expansion process curve, the suction process curve, the exhaust process curve and the backflow process curve; obtaining the standard cylinder pressure data; obtaining the actual cylinder pressure data; calculating the deviation coefficient; determining the reciprocating compressor valve fault type according to the deviation coefficient; the present application constructs the working process curve under normal working condition and the backflow process curve under variable load condition after determining the pressure correction coefficient, determines the standard cylinder pressure data according to the process curve, then determines the valve fault type based on the deviation coefficient between the standard cylinder pressure data and the actual cylinder pressure data, realizes the identification of working condition load, completes the typical valve fault early warning, and improves the early warning accuracy.

Description

Technical Field

[0001] This invention relates to the field of online monitoring and diagnostic technology for oil and gas field dynamic equipment, specifically to a method and program product for diagnosing valve faults in a natural gas reciprocating compressor. Background Technology

[0002] The main function of a natural gas reciprocating compressor is to increase the pressure of natural gas to meet the requirements for transportation or storage in oil and gas fields. This type of compressor uses a crankshaft to drive a connecting rod, which in turn drives a piston to compress the gas. Reciprocating compressors have the advantages of high thermal efficiency and low power consumption per unit area, making them particularly suitable for applications requiring large-volume gas compression, and thus widely used in the natural gas industry.

[0003] The structure of a natural gas reciprocating compressor includes major components such as a cylinder, crankshaft and connecting rod mechanism, piston assembly, packing (seals), and valves. The cylinder typically has a smooth surface for lubrication and wear resistance, as well as good thermal conductivity to ensure rapid heat dissipation. The crankshaft and connecting rod mechanism converts the circular motion of the motor into the reciprocating motion of the piston, thus compressing the gas. The piston assembly, including the piston head, piston rings, piston pads, and piston rod, seals the high-pressure gas within the cylinder to prevent leakage. The packing seals the gap between the cylinder seat and the piston rod, preventing radial leakage of gas along the piston rod. As one of the most crucial components of the compressor, the design quality of the valve directly affects the compressor's discharge capacity, power consumption, and operational reliability.

[0004] During operation, the constantly changing operating conditions of the natural gas reciprocating compressor system often lead to problems such as intermittent operation, discontinuous exhaust, and airflow pulsation resonance, resulting in damage to unit components. Natural gas reciprocating compressor units have many vulnerable parts, operate in harsh environments, and are prone to mechanical wear, leading to a high failure rate. Furthermore, the compressed medium is a flammable and explosive gas; failure to detect and eliminate faults promptly can easily cause safety accidents. In addition, the stable and reliable operation of the gas valves directly affects the overall operating efficiency of the compressor unit. Therefore, in actual production, gas valve failures in natural gas reciprocating compressors are frequent. Statistics show that gas valve failures generally account for more than 30% of unplanned downtime factors, making it a major cause of unplanned shutdowns. Therefore, detecting gas valve damage in the early stages of compressor operation is essential for preventing failures.

[0005] Although data-based valve fault early warning methods exist in China, reciprocating compressors are often in variable load conditions due to process adjustments. Purely data-based early warning methods cannot identify the data changes caused by fault conditions and variable load conditions, and therefore cannot accurately predict faults.

[0006] Therefore, this invention proposes a method for early warning of valve failure in reciprocating compressors that integrates data and mechanisms, which can identify the operating load and achieve accurate and precise early warning of valve failure. Summary of the Invention

[0007] The technical problem to be solved by this invention is the inability to accurately predict faults. The purpose is to provide a method and program product for diagnosing valve faults in natural gas reciprocating compressors, thereby effectively reducing the overall failure rate of natural gas reciprocating compressors and ensuring the safe and stable production process of oil and gas fields.

[0008] This invention is achieved through the following technical solution:

[0009] A method for diagnosing valve failures in a natural gas reciprocating compressor includes:

[0010] Determine the process parameters of the reciprocating compressor;

[0011] Calculate the pressure correction factor, which includes: pressure rise correction factor during recirculation, pressure correction factor during intake, and pressure correction factor during exhaust.

[0012] Determine the working process curves of the reciprocating compressor under normal operating conditions. The working process curves include: compression process curve, expansion process curve, intake process curve and exhaust process curve.

[0013] Determine the reflux process curve of the reciprocating compressor under variable load conditions;

[0014] Standard cylinder pressure data of reciprocating compressors under different loads are obtained based on process curves;

[0015] Obtain the actual cylinder pressure data of the reciprocating compressor under operating conditions;

[0016] Calculate the deviation coefficient between the actual cylinder pressure data and the standard cylinder pressure data. The deviation coefficient includes the deviation coefficient for the expansion process, the deviation coefficient for the intake process, the deviation coefficient for the recirculation process, the deviation coefficient for the compression process, and the deviation coefficient for the exhaust process.

[0017] The type of valve failure in a reciprocating compressor can be determined based on the deviation coefficient.

[0018] Specifically, the process parameters of the reciprocating compressor include:

[0019] Calculate cylinder volume, Where V(c) is the clearance volume, D is the piston diameter, r is the crank radius, λ is the crank-connecting rod ratio, V(π) is the cylinder volume when the crank angle is 180°, L is the unit load percentage, and V cy (θ) is the cylinder volume when the crank angle is θ;

[0020] Determine the crank angle θ1 when the reflux process ends, the crank angle θ2 when the intake process begins, the crank angle θ3 when the compression process ends, and the crank angle θ4 when the exhaust process ends.

[0021] Optionally, methods for calculating the pressure correction factor include:

[0022] Correction factor η for pressure rise during reflux process.

[0023] Inhalation pressure correction factor δ,

[0024] Exhaust process pressure correction factor γ,

[0025] Where a is the range parameter, p cy (θ) represents the cylinder pressure when the crank angle is θ, p s p is the actual inhalation pressure. d This represents the actual exhaust pressure.

[0026] Optionally, the range parameter a = 0.9 to 1.1.

[0027] Specifically, the working process curve of the reciprocating compressor is determined, including:

[0028] Compression process curve

[0029] Expansion process curve

[0030] Inhalation process curve

[0031] Exhaust process curve

[0032] Determine the reflux process curve of the reciprocating compressor under variable load conditions;

[0033]

[0034] Where m is the compression exponent, n is the expansion exponent, V(s) is the cylinder volume at the start of the intake process, V(p) is the cylinder volume at the end of the compression process, V(c) is the clearance volume, and V cy (θ) is the cylinder volume when the crank angle is θ, p cy (θ) represents the cylinder pressure when the crank angle is θ, V s p is the intake volume. s This is the actual inhalation pressure.

[0035] Optionally, methods for calculating the deviation coefficient include:

[0036] Expansion process deviation coefficient

[0037] Inhalation process deviation coefficient

[0038] Reflux process deviation coefficient

[0039] Compression process deviation coefficient p′ cy For p cy The first derivative, V ′cy For V cy The first derivative;

[0040] Exhaust process deviation coefficient

[0041] Specifically, methods for determining whether a reciprocating compressor is malfunctioning based on the deviation coefficient include:

[0042] If -0.2 < φ i If the value is less than 0.2 and i = 1, 2, 3, 4, 5, then the reciprocating compressor is in state .

[0043] If φ i ≤-0.2 or φ i If the value is ≥0.2 and i = 1, 2, 3, 4, 5, then the reciprocating compressor is in a fault state.

[0044] Furthermore, the relevant states of the deviation coefficient are set as follows:

[0045] F+=φ i ≥0.2, F-=φ i ≤-0.2, N=-0.2<φ i <0.2;

[0046] The specific fault type determination methods for reciprocating compressors under variable load conditions include:

[0047] If the deviation coefficient of the expansion process is in the F- state, the deviation coefficient of the intake process is in the F+ state, the deviation coefficient of the reflux process is in the F+ state, the deviation coefficient of the compression process is in the F+ state, and the deviation coefficient of the exhaust process is in the F- state, then the fault type of the reciprocating compressor is intake valve leakage.

[0048] If the deviation coefficient of the expansion process is in the F+ state, the deviation coefficient of the intake process is in the F- state, the deviation coefficient of the reflux process is in the F- state, the deviation coefficient of the compression process is in the F- state, and the deviation coefficient of the exhaust process is in the F+ state, then the fault type of the reciprocating compressor is exhaust valve leakage.

[0049] If the deviation coefficient of the expansion process is in state N, the deviation coefficient of the intake process is in state F-, the deviation coefficient of the reflux process is in state N, the deviation coefficient of the compression process is in state N, and the deviation coefficient of the exhaust process is in state N, then the fault type of the reciprocating compressor is intake valve jamming.

[0050] If the deviation coefficient of the expansion process is in state N, the deviation coefficient of the intake process is in state N, the deviation coefficient of the reflux process is in state N, the deviation coefficient of the compression process is in state N, and the deviation coefficient of the exhaust process is in state F+, then the fault type of the reciprocating compressor is intake valve jamming.

[0051] Furthermore, the relevant states of the deviation coefficient are set as follows:

[0052] F+=φ i ≥0.2, F-=φ i ≤-0.2, N=-0.2<φ i <0.2;

[0053] The methods for determining the specific fault types of reciprocating compressors under normal operating conditions include:

[0054] If the deviation coefficient of the expansion process is in the F- state, the deviation coefficient of the intake process is in the F+ state, the deviation coefficient of the reflux process is in the N state, the deviation coefficient of the compression process is in the F+ state, and the deviation coefficient of the exhaust process is in the F- state, then the fault type of the reciprocating compressor is intake valve leakage.

[0055] If the deviation coefficient of the expansion process is in the F+ state, the deviation coefficient of the intake process is in the F- state, the deviation coefficient of the reflux process is in the N state, the deviation coefficient of the compression process is in the F- state, and the deviation coefficient of the exhaust process is in the F+ state, then the fault type of the reciprocating compressor is exhaust valve leakage.

[0056] If the deviation coefficient of the expansion process is in state N, the deviation coefficient of the intake process is in state F-, the deviation coefficient of the reflux process is in state N, the deviation coefficient of the compression process is in state N, and the deviation coefficient of the exhaust process is in state N, then the fault type of the reciprocating compressor is intake valve jamming.

[0057] If the deviation coefficient of the expansion process is in state N, the deviation coefficient of the intake process is in state N, the deviation coefficient of the reflux process is in state N, the deviation coefficient of the compression process is in state N, and the deviation coefficient of the exhaust process is in state F+, then the fault type of the reciprocating compressor is intake valve jamming.

[0058] A computer program product includes a computer program / instructions that, when executed by a processor, implement a natural gas reciprocating compressor valve fault diagnosis method as described above.

[0059] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0060] This invention constructs a working process curve under normal operating conditions and a return flow process curve under variable load conditions after determining the pressure correction coefficient. Based on the process curves, standard cylinder pressure data is determined. Then, based on the deviation coefficient between the standard cylinder pressure data and the actual cylinder pressure data, the valve fault type is determined, thereby realizing the identification of operating load and completing the early warning of typical valve faults, thus improving the accuracy of the early warning.

[0061] This invention can accurately simulate the working process of a reciprocating compressor under variable load conditions, significantly improving the simulation accuracy of cylinder pressure data. Furthermore, it can perform fault diagnosis based on the cylinder pressure correction coefficient and deviation coefficient under different working conditions, effectively distinguishing between fault data and normal data fluctuations, significantly improving the accuracy of fault warning, and ultimately determining the specific fault type of the valve in real time, which helps to reduce the risk of unplanned shutdown of the reciprocating compressor. Attached Figure Description

[0062] The accompanying drawings illustrate exemplary embodiments of the present invention and, together with the description thereof, serve to explain the principles of the invention. These drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, but do not constitute a limitation on the embodiments of the present invention.

[0063] Figure 1 This is a flowchart illustrating a method and procedure for diagnosing valve faults in a natural gas reciprocating compressor according to the present invention.

[0064] Figure 2 This is a diagram of the actual dynamic pressure data of the unit at 80% load, as described in this invention.

[0065] Figure 3 This is a graph of the expansion process according to the present invention.

[0066] Figure 4 This is a graph of the inhalation process according to the present invention.

[0067] Figure 5 This is a reflux process curve diagram according to the present invention.

[0068] Figure 6 This is a compression process curve according to the present invention.

[0069] Figure 7 This is a graph of the exhaust process according to the present invention.

[0070] Figure 8 This is a graph showing the actual dynamic pressure data and simulation data of the unit under 80% load-valve leakage as described in this invention. Detailed Implementation

[0071] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0072] It should also be noted that, for ease of description, only the parts relevant to the present invention are shown in the accompanying drawings.

[0073] Where there is no conflict, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0074] Example 1

[0075] like Figure 1 As shown, a method for diagnosing valve faults in a natural gas reciprocating compressor includes:

[0076] Determine the process parameters of the reciprocating compressor; process parameters refer to various physical quantities that need to be measured or determined during the operation of the compressor, which usually include the compressor's piston diameter, crank radius, connecting rod ratio, cylinder volume, etc.

[0077] Calculate the pressure correction factor used to adjust the difference between the measured pressure and the theoretical pressure under actual operating conditions. The pressure correction factor includes: pressure rise correction factor during the recirculation process, pressure correction factor during the intake process, and pressure correction factor during the exhaust process. The pressure will change due to different airflow processes (such as recirculation, intake, exhaust, etc.), so correction factors are needed to more accurately reflect the real pressure inside the cylinder.

[0078] Determine the working process curves of the reciprocating compressor under normal operating conditions. The working process curves include: compression process curve (the curve in which the pressure in the cylinder increases as the volume decreases when the gas is compressed), expansion process curve (the curve in which the pressure in the cylinder increases as the volume increases when the gas expands), intake process curve (the pressure change curve when the cylinder draws in gas through the intake valve), and exhaust process curve (the pressure change curve when the compressed gas is discharged through the exhaust valve).

[0079] Determine the reflux process curve of the reciprocating compressor under variable load conditions; the reflux process under variable load conditions refers to the pressure change of the gas reflux process in the cylinder when the load changes. The reflux process refers to the phenomenon in a reciprocating compressor where the gas in the cylinder flows back to the suction side due to the suction valve not closing in time.

[0080] Standard cylinder pressure data of reciprocating compressors under different loads are obtained based on process curves.

[0081] The actual cylinder pressure data of the reciprocating compressor under working conditions can be obtained; in actual operation, the actual cylinder pressure data of the compressor can be obtained in real time through sensors installed on the cylinder.

[0082] Calculate the deviation coefficient between the actual cylinder pressure data and the standard cylinder pressure data. The deviation coefficient includes the deviation coefficient for the expansion process, the intake process, the recirculation process, the compression process, and the exhaust process. The deviation coefficient is a value that measures the difference between the actual pressure data and the standard pressure data.

[0083] The type of valve failure in the reciprocating compressor is determined by the deviation coefficient. If the deviation coefficient exceeds a certain preset threshold, it indicates that there may be valve leakage, jamming, or other faults.

[0084] The working principle of this method lies in calculating the pressure correction coefficient under different operating conditions and comparing the standard cylinder pressure with the actual cylinder pressure to identify potential abnormalities during compressor operation. Valve malfunctions directly affect cylinder pressure changes; therefore, through precise pressure calculations and deviation analysis, the malfunction status of the valves can be effectively determined.

[0085] Example 2

[0086] This embodiment provides a detailed description of Embodiment 1. The process parameters of the reciprocating compressor include:

[0087] Calculate the cylinder volume at different crank angles. Where V(c) is the clearance volume, D is the piston diameter, r is the crank radius, λ is the crank-connecting rod ratio, V(π) is the cylinder volume when the crank angle is 180°, L is the unit load percentage, and V cy (θ) is the cylinder volume when the crank angle is θ.

[0088] Clearance volume refers to the volume remaining in the cylinder when the piston reaches its highest position, i.e., the minimum volume. The crank-connecting rod ratio is equal to the ratio of the connecting rod length to the crank radius. Unit load percentage indicates the proportion of the compressor operating under partial or full load conditions.

[0089] The working process of a compressor can be divided into several stages, such as recirculation, intake, compression, and exhaust. These stages correspond to changes in cylinder volume and cylinder pressure, respectively. Each stage has a key crank angle point, which determines the crank angle θ1 when the recirculation process ends, the crank angle θ2 when the intake process begins, the crank angle θ3 when the compression process ends, and the crank angle θ4 when the exhaust process ends.

[0090] Methods for calculating pressure correction factors include:

[0091] The reflux pressure rise correction factor η is used to correct for pressure changes during the reflux process. The cylinder pressure is compared with the actual intake pressure during the reflow process.

[0092] Inhalation pressure correction factor δ, The cylinder pressure is compared with the intake pressure to correct for deviations in cylinder pressure during actual intake.

[0093] Exhaust process pressure correction factor γ, The cylinder pressure is compared with the actual exhaust pressure to correct for pressure changes during the exhaust process.

[0094] Where a is the range parameter, p cy (θ) represents the cylinder pressure when the crank angle is θ, p s p is the actual inhalation pressure. d This represents the actual exhaust pressure.

[0095] The range parameter a = 0.9 to 1.1, and can be selected according to the actual situation.

[0096] Under normal operating conditions, the reciprocating compressor's working process includes expansion, intake, compression, and exhaust processes. The expansion and compression stages are modeled using multivariate equations. The intake and exhaust process curves are treated similarly to the reflux process curves. The working process curves of the reciprocating compressor are thus determined, including:

[0097] Compression process curve

[0098] Expansion process curve

[0099] Inhalation process curve

[0100] Exhaust process curve

[0101] When the reciprocating compressor is under variable load conditions, the suction valve remains open after the suction process is completed. When the reciprocating compressor reaches the load adjustment requirements, the suction valve closes again and the compression and exhaust processes are carried out. Since the gas flow path in the return process is the same as that in the suction process, only in the opposite direction, the gas in the return process does very little work. The pressure rise coefficient can be corrected according to the actual data. Therefore, the return process curve of the reciprocating compressor under variable load conditions is determined.

[0102] Where m is the compression process index reflecting the gas state during compression, which can be determined experimentally or set according to compressor characteristics. n is the expansion process index reflecting the gas state during expansion, which can be determined experimentally or set according to compressor characteristics. V(s) is the cylinder volume at the beginning of the intake process, V(p) is the cylinder volume at the end of the compression process, V(c) is the clearance volume, and V... cy (θ) is the cylinder volume when the crank angle is θ, p cy (θ) represents the cylinder pressure when the crank angle is θ, V s p is the intake volume. s This represents the actual inhalation pressure. m and n need to be selected based on the actual situation, typically between 1.2 and 1.4.

[0103] After determining the working curve, standard cylinder pressure data can be generated based on the working curve. For the entire crank angle range θ = 0 to 360°, p at each θ is calculated according to the method described above. cy (θ), all calculated p cy (θ) The data is sorted according to crank angle to obtain a complete standard cylinder pressure dataset. Using the calculated p... cy (θ) and V cy (θ) data, plot pressure-volume (PV) curves.

[0104] Deviation coefficients are used to measure the difference between actual operating conditions and standard operating conditions. Specifically, they include deviation coefficients for the expansion, intake, recirculation, compression, and exhaust processes. Methods for calculating deviation coefficients include:

[0105] Expansion process deviation coefficient

[0106] Inhalation process deviation coefficient

[0107] Reflux process deviation coefficient The reflux process is the process by which a portion of the gas flows back to the inhalation end after the inhalation is completed.

[0108] Compression process deviation coefficient p′ cy For p cy The first derivative, V′ cy For V cy The first derivative.

[0109] Exhaust process deviation coefficient

[0110] Deviation coefficients are obtained by comparing actual values ​​with theoretical values ​​to obtain a specific numerical value. Methods for determining whether a reciprocating compressor is malfunctioning based on the deviation coefficient include:

[0111] If -0.2 < φ i If the value is less than 0.2 and i = 1, 2, 3, 4, 5, then the reciprocating compressor is in state .

[0112] If φ i ≤-0.2 or φ i If the value is ≥0.2 and i = 1, 2, 3, 4, 5, then the reciprocating compressor is in a fault state.

[0113] Example 3

[0114] After determining whether the compressor valve is in a faulty state in Embodiments 1 and 2, this embodiment provides a method for determining the specific fault type.

[0115] For ease of description later, the relevant state of the deviation coefficient is set as: F+=φ i ≥0.2, F-=φ i ≤-0.2, N=-0.2<φ i <0.2.

[0116] The specific fault type determination methods for reciprocating compressors under variable load conditions include:

[0117] If the deviation coefficient of the expansion process is in the F- state, the deviation coefficient of the intake process is in the F+ state, the deviation coefficient of the reflux process is in the F+ state, the deviation coefficient of the compression process is in the F+ state, and the deviation coefficient of the exhaust process is in the F- state, then the fault type of the reciprocating compressor is intake valve leakage.

[0118] If the deviation coefficient of the expansion process is in the F+ state, the deviation coefficient of the intake process is in the F- state, the deviation coefficient of the reflux process is in the F- state, the deviation coefficient of the compression process is in the F- state, and the deviation coefficient of the exhaust process is in the F+ state, then the fault type of the reciprocating compressor is exhaust valve leakage.

[0119] If the deviation coefficient of the expansion process is in state N, the deviation coefficient of the intake process is in state F-, the deviation coefficient of the reflux process is in state N, the deviation coefficient of the compression process is in state N, and the deviation coefficient of the exhaust process is in state N, then the fault type of the reciprocating compressor is intake valve jamming.

[0120] If the deviation coefficient of the expansion process is in state N, the deviation coefficient of the intake process is in state N, the deviation coefficient of the reflux process is in state N, the deviation coefficient of the compression process is in state N, and the deviation coefficient of the exhaust process is in state F+, then the fault type of the reciprocating compressor is intake valve jamming.

[0121] The methods for determining the specific fault types of reciprocating compressors under normal operating conditions include:

[0122] If the deviation coefficient of the expansion process is in the F- state, the deviation coefficient of the intake process is in the F+ state, the deviation coefficient of the reflux process is in the N state, the deviation coefficient of the compression process is in the F+ state, and the deviation coefficient of the exhaust process is in the F- state, then the fault type of the reciprocating compressor is intake valve leakage.

[0123] If the deviation coefficient of the expansion process is in the F+ state, the deviation coefficient of the intake process is in the F- state, the deviation coefficient of the reflux process is in the N state, the deviation coefficient of the compression process is in the F- state, and the deviation coefficient of the exhaust process is in the F+ state, then the fault type of the reciprocating compressor is exhaust valve leakage.

[0124] If the deviation coefficient of the expansion process is in state N, the deviation coefficient of the intake process is in state F-, the deviation coefficient of the reflux process is in state N, the deviation coefficient of the compression process is in state N, and the deviation coefficient of the exhaust process is in state N, then the fault type of the reciprocating compressor is intake valve jamming.

[0125] If the deviation coefficient of the expansion process is in state N, the deviation coefficient of the intake process is in state N, the deviation coefficient of the reflux process is in state N, the deviation coefficient of the compression process is in state N, and the deviation coefficient of the exhaust process is in state F+, then the fault type of the reciprocating compressor is intake valve jamming.

[0126] The table is as follows.

[0127]

[0128] Example 5

[0129] This embodiment provides a specific example.

[0130] First, the process parameters for the compressor are provided, as shown in the table below:

[0131] Parameter name numerical values Parameter name numerical values Crankshaft radius (mm) 90 Valve plate moving mass (Kg) 0.05 Linkage length (mm) 450 Motor speed (r / min) 500 Piston rod radius (mm) 22.5 Number of the same type of air valve 2 Piston radius (mm) 125 Piston radius (mm) 125 External clearance volume (mm3) 1.26E+06 Inhalation temperature (°C) 27 Inner clearance volume (mm3) 1.22E+06 Valve spring pre-compression (mm) 4 Inspiratory pressure (kPa) 100 Valve lift (mm) 2.1 Exhaust pressure (kPa) 300 Gas constant (m² / sec²·k) 287 Adiabatic process index 1.4 The sum of the circumferences of all rings of the valve seat is twice (m). 1.18 Valve seat passage area (m2) 0.0043 Inhalation temperature (°C) 27

[0132] Figure 2 This is the actual dynamic pressure data of the unit at 80% load. A dynamic pressure sensor is installed on the pressure tap of the unit's cylinder block to monitor the dynamic pressure data in real time, and pressure data under different loads is obtained with the help of the unit's flow regulation system.

[0133] Based on dynamic pressure data and unit structural parameters, the reflux process mechanism model is combined with actual data. The dynamic pressure data is calculated below using 80% load as an example:

[0134] Cylinder volume calculation:

[0135]

[0136] Based on V(s) = 0.0031m 3 pd =0.25MPa, n=0.14 to obtain as follows Figure 3 The expansion process curve shown:

[0137] According to p s =0.86MPa,

[0138] Obtain as Figure 4 The inhalation process curve is shown.

[0139] according to K = 1 - 0.8 = 0.2, V s =0.0031m 3 p cy = -7836492.7V cy +42730.7216 obtained as follows Figure 5 The reflux process curve shown is shown.

[0140] According to V p =0.0038 to obtain as Figure 6 The compression process curve shown is shown.

[0141] according to Obtain as Figure 7 The exhaust process curve shown is shown.

[0142] Figure 8 This data includes actual and simulated dynamic pressure data for the unit at 80% load with valve leakage. Taking the unit at 80% load as an example, the intake valve disc was intentionally damaged, causing a valve leakage fault.

[0143] Example 6

[0144] A computer program product includes a computer program / instructions that, when executed by a processor, implement the above-described method for diagnosing valve faults in a natural gas reciprocating compressor.

[0145] Computer program products include computer programs or instruction sets used to perform specific tasks or achieve specific functions. These programs or instructions are designed to be executed by a processor to implement a series of predefined steps or operations. The program product may be stored in various forms of computer storage media, such as memory, hard disks, solid-state drives, optical discs, or other forms of digital storage devices. It may exist in the form of compiled binary code or in the form of scripts or bytecode that can be executed by an interpreter. Through carefully designed algorithms and logical instructions, the program product enables the processor to process data in a specific order and manner, performing various functions such as data analysis, user interaction, and device control.

[0146] In the description of this specification, the references to terms such as "one embodiment / mode," "some embodiments / modes," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment / mode or example is included in at least one embodiment / mode or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment / mode or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments / modes or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments / modes or examples described in this specification, as well as the features of different embodiments / modes or examples.

[0147] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0148] Those skilled in the art should understand that the above embodiments are merely for illustrating the present invention and are not intended to limit the scope of the invention. Those skilled in the art can make other changes or modifications based on the above invention, and these changes or modifications still fall within the scope of the present invention.

Claims

1. A method for diagnosing valve faults in a natural gas reciprocating compressor, characterized in that, include: Determine the process parameters of the reciprocating compressor; Calculate the pressure correction factor, which includes: pressure rise correction factor during recirculation, pressure correction factor during intake, and pressure correction factor during exhaust. Determine the working process curves of the reciprocating compressor under normal operating conditions. The working process curves include: compression process curve, expansion process curve, intake process curve and exhaust process curve. Determine the reflux process curve of the reciprocating compressor under variable load conditions; Standard cylinder pressure data of reciprocating compressors under different loads are obtained based on process curves; Obtain the actual cylinder pressure data of the reciprocating compressor under operating conditions; Calculate the deviation coefficient between the actual cylinder pressure data and the standard cylinder pressure data. The deviation coefficient includes the deviation coefficient for the expansion process, the deviation coefficient for the intake process, the deviation coefficient for the recirculation process, the deviation coefficient for the compression process, and the deviation coefficient for the exhaust process. The type of valve failure in a reciprocating compressor can be determined based on the deviation coefficient.

2. The method for diagnosing valve faults in a natural gas reciprocating compressor according to claim 1, characterized in that, The process parameters for reciprocating compressors include: Calculate cylinder volume, Where V(c) is the clearance volume, D is the piston diameter, r is the crank radius, λ is the crank-connecting rod ratio, V(π) is the cylinder volume when the crank angle is 180°, L is the unit load percentage, and V cy (θ) is the cylinder volume when the crank angle is θ; Determine the crank angle θ1 when the reflux process ends, the crank angle θ2 when the intake process begins, the crank angle θ3 when the compression process ends, and the crank angle θ4 when the exhaust process ends.

3. The method for diagnosing valve faults in a natural gas reciprocating compressor according to claim 2, characterized in that, Methods for calculating pressure correction factors include: Correction factor η for pressure rise during reflux process. Inhalation pressure correction factor δ, Exhaust process pressure correction factor γ, Where a is the range parameter, p cy (θ) represents the cylinder pressure when the crank angle is θ, p s p is the actual inhalation pressure. d This represents the actual exhaust pressure.

4. The method for diagnosing valve faults in a natural gas reciprocating compressor according to claim 3, characterized in that, The range parameter a = 0.9 to 1.

1.

5. The method for diagnosing valve faults in a natural gas reciprocating compressor according to claim 3, characterized in that, Determine the working process curve of the reciprocating compressor, including: Compression process curve Expansion process curve Inhalation process curve Exhaust process curve Determine the reflux process curve of the reciprocating compressor under variable load conditions; Where m is the compression exponent, n is the expansion exponent, V(s) is the cylinder volume at the start of the intake process, V(p) is the cylinder volume at the end of the compression process, V(c) is the clearance volume, and V cy (θ) is the cylinder volume when the crank angle is θ, p cy (θ) represents the cylinder pressure when the crank angle is θ, V s p is the intake volume. s This is the actual inhalation pressure.

6. The method for diagnosing valve faults in a natural gas reciprocating compressor according to claim 5, characterized in that, Methods for calculating the deviation coefficient include: Expansion process deviation coefficient Inhalation process deviation coefficient Reflux process deviation coefficient Compression process deviation coefficient p′ cy For p cy The first derivative, V′ cy For V cy The first derivative; Exhaust process deviation coefficient 7. A method for diagnosing valve faults in a natural gas reciprocating compressor according to claim 6, characterized in that, Methods for determining whether a reciprocating compressor is malfunctioning based on the deviation coefficient include: If -0.2 < φ i If the value is less than 0.2 and i = 1, 2, 3, 4, 5, then the reciprocating compressor is in state . If φ i ≤-0.2 or φ i If the value is ≥0.2 and i = 1, 2, 3, 4, 5, then the reciprocating compressor is in a fault state.

8. A method for diagnosing valve faults in a natural gas reciprocating compressor according to claim 7, characterized in that, The relevant states of the deviation coefficient are set as follows: F+=φ i ≥0.2,F-=φ i ≤-0.2,N=-0.2<φ i <0.2; The specific fault type determination methods for reciprocating compressors under variable load conditions include: If the deviation coefficient of the expansion process is in the F- state, the deviation coefficient of the intake process is in the F+ state, the deviation coefficient of the reflux process is in the F+ state, the deviation coefficient of the compression process is in the F+ state, and the deviation coefficient of the exhaust process is in the F- state, then the fault type of the reciprocating compressor is intake valve leakage. If the deviation coefficient of the expansion process is in the F+ state, the deviation coefficient of the intake process is in the F- state, the deviation coefficient of the reflux process is in the F- state, the deviation coefficient of the compression process is in the F- state, and the deviation coefficient of the exhaust process is in the F+ state, then the fault type of the reciprocating compressor is exhaust valve leakage. If the deviation coefficient of the expansion process is in state N, the deviation coefficient of the intake process is in state F-, the deviation coefficient of the reflux process is in state N, the deviation coefficient of the compression process is in state N, and the deviation coefficient of the exhaust process is in state N, then the fault type of the reciprocating compressor is intake valve jamming. If the deviation coefficient of the expansion process is in state N, the deviation coefficient of the intake process is in state N, the deviation coefficient of the reflux process is in state N, the deviation coefficient of the compression process is in state N, and the deviation coefficient of the exhaust process is in state F+, then the fault type of the reciprocating compressor is intake valve jamming.

9. A method for diagnosing valve faults in a natural gas reciprocating compressor according to claim 7, characterized in that, The relevant states of the deviation coefficient are set as follows: F+=φ i ≥0.2,F-=φ i ≤-0.2,N=-0.2<φ i <0.2; The methods for determining the specific fault types of reciprocating compressors under normal operating conditions include: If the deviation coefficient of the expansion process is in the F- state, the deviation coefficient of the intake process is in the F+ state, the deviation coefficient of the reflux process is in the N state, the deviation coefficient of the compression process is in the F+ state, and the deviation coefficient of the exhaust process is in the F- state, then the fault type of the reciprocating compressor is intake valve leakage. If the deviation coefficient of the expansion process is in the F+ state, the deviation coefficient of the intake process is in the F- state, the deviation coefficient of the reflux process is in the N state, the deviation coefficient of the compression process is in the F- state, and the deviation coefficient of the exhaust process is in the F+ state, then the fault type of the reciprocating compressor is exhaust valve leakage. If the deviation coefficient of the expansion process is in state N, the deviation coefficient of the intake process is in state F-, the deviation coefficient of the reflux process is in state N, the deviation coefficient of the compression process is in state N, and the deviation coefficient of the exhaust process is in state N, then the fault type of the reciprocating compressor is intake valve jamming. If the deviation coefficient of the expansion process is in state N, the deviation coefficient of the intake process is in state N, the deviation coefficient of the reflux process is in state N, the deviation coefficient of the compression process is in state N, and the deviation coefficient of the exhaust process is in state F+, then the fault type of the reciprocating compressor is intake valve jamming.

10. A computer program product comprising a computer program / instructions, characterized in that, When the computer program / instructions are executed by the processor, they implement the method as described in any one of claims 1-9.

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