Fault detection method, system and device for plate heat exchanger

Abstract

The present invention relates to the field of heat exchanger fault detection, and specifically to a fault detection method, system and device for plate heat exchangers. The method first obtains the temperature signal and the time domain signal of vibration of each metal plate of the plate heat exchanger, and according to the difference in fluctuation between the time domain signal and the temperature signal of the two metal plates adjacent to the target gasket, fuses the time domain signals of the two adjacent metal plates and performs frequency domain conversion to obtain the frequency domain signal of the target gasket; obtains the overall amplitude of the target gasket under temperature interference only, and detects damage to the gasket based on the amplitude difference between the frequency domain signals of the target gasket and other gaskets at the same frequency, as well as the difference between the amplitude of the frequency domain signal of the target gasket at each frequency and the overall amplitude. The present invention can reduce the interference of the vibration signal generated by temperature change on the vibration characteristic analysis caused by gasket damage, and improve the accuracy of gasket damage detection in plate heat exchangers.

Description

Technical Field

[0001] The present invention relates to the field of heat exchanger fault detection, and in particular to a fault detection method, system and device for a plate heat exchanger. Background Art

[0002] Plate heat exchangers are widely used in various industrial fields. They use a series of corrugated metal plates to separate two fluids of different temperatures and exchange heat through the spaces between the plates. Gaskets are key components in plate heat exchangers, preventing fluid leakage, contamination, and equipment damage. They also help ensure heat exchange efficiency, avoid equipment damage, and extend equipment life. Therefore, detecting gasket damage is crucial to maintaining the normal operation of the heat exchanger.

[0003] Fluid leakage caused by gasket damage will generate vibration signals. In related technologies, the vibration signals of the heat exchanger gasket in the time domain are usually monitored and collected, and then converted into frequency domain signals through Fourier transform. The frequency components in the spectrum are then analyzed to identify features related to gasket damage. However, the working principle of the plate heat exchanger is to cause temperature changes through heat exchange, and temperature changes will trigger thermal expansion or contraction effects of the metal plates, resulting in slight bending or deformation of the metal plates, thereby generating vibration signals. These vibration signals generated by temperature changes will overlap with the vibrations caused by fluid leakage due to sealing gasket damage in the spectrum, thereby interfering with the vibration characteristics caused by fluid leakage due to gasket damage, and reducing the accuracy of heat exchanger gasket damage detection. Summary of the Invention

[0004] In order to solve the technical problem that the vibration signal generated by temperature changes interferes with the vibration characteristics caused by gasket damage and fluid leakage, thereby reducing the accuracy of heat exchanger gasket damage detection, the purpose of the present invention is to provide a fault detection method, system and device for plate heat exchangers. The technical solutions adopted are as follows:

[0005] The present invention proposes a fault detection method for a plate heat exchanger, the method comprising:

[0006] Acquire the temperature signal and vibration time domain signal of each metal plate of the plate heat exchanger during operation;

[0007] Taking any gasket of the plate heat exchanger as the target gasket, and taking the two metal plates adjacent to the target gasket as the reference metal plates of the target gasket, obtaining the fusion weight of the time domain signal of each reference metal plate at each moment based on the difference in fluctuation between the time domain signal and the temperature signal of each reference metal plate; according to the fusion weight of the time domain signal of each reference metal plate at each moment, the time domain signals of the reference metal plates are fused and frequency domain converted to obtain the frequency domain signal of the target gasket;

[0008] According to the amplitudes of the frequency domain signals of all gaskets at the same frequency and the serial number corresponding to the target gasket, the overall amplitude of the target gasket under temperature interference only is obtained; according to the amplitude difference at the same frequency between the frequency domain signals of the target gasket and other gaskets except the target gasket, and the difference between the amplitude of the frequency domain signal of the target gasket at each frequency and the overall amplitude, the damage manifestation coefficient of the frequency domain signal of the target gasket at each frequency is obtained; according to the damage manifestation coefficient of the frequency domain signal of the target gasket at all frequencies, the damage possibility of the target gasket is obtained;

[0009] Based on the damage possibility of each gasket, each gasket is inspected for damage.

[0010] Furthermore, obtaining the fusion weight of the time domain signal of each reference metal plate at each moment includes:

[0011] Taking any reference metal sheet as a target reference metal sheet;

[0012] Based on the calculation formula of the effective coefficient, the effective coefficient of the time domain signal of the target reference metal plate at each moment is obtained. The calculation formula of the effective coefficient is:

[0013]

[0014] in, The time domain signal representing the target reference metal plate is The effective coefficient at each moment; The first time domain signal representing the target reference metal plate The moment and The standard deviation of the amplitudes at all moments between ; The first temperature signal representing the target reference metal plate The moment and The standard deviation of the temperature data at all moments between moments; Indicates that except The number of moments other than the moment; Expressed as a natural constant An exponential function with base ; represents the normalization function;

[0015] The effective coefficients of the time domain signal of the target reference metal plate at each moment are normalized to obtain the fusion weight of the time domain signal of the target reference metal plate at each moment, wherein the sum of the fusion weights of the time domain signals of the two reference metal plates of the target gasket at the same moment is equal to the value 1.

[0016] Furthermore, obtaining the frequency domain signal of the target gasket includes:

[0017] Using the fusion weights of the time domain signals of the two reference metal plates of the target gasket at each moment, weighted summing the amplitudes of the time domain signals of the two reference metal plates at each moment is performed to obtain a fused amplitude of the target gasket at each moment, and using a signal composed of the fused amplitudes of the target gasket at all moments as a fused time domain signal of the target gasket regarding vibration;

[0018] Perform Fourier transform on the fused time domain signal of the target gasket regarding vibration to obtain a frequency domain signal of the target gasket.

[0019] Furthermore, obtaining the overall amplitude of the target gasket under temperature interference alone includes:

[0020] Construct an overall amplitude function for each gasket, which is:

[0021]

[0022] in, Indicates about The overall amplitude function of the gasket, whose independent variable is the The serial number of each gasket ; 、 、 and Represent four unknown parameters respectively; represents a natural constant;

[0023] According to the amplitude of the same frequency of the frequency domain signals of all gaskets and the overall amplitude function, an error function is constructed, and the error function includes 、 、 and Four unknown parameters;

[0024] Use the least squares method to minimize the error function and calculate 、 、 and The values of the four unknown parameters and 、 、 and The values of the four unknown parameters and the serial number corresponding to the target gasket are substituted into the overall amplitude function to obtain the overall amplitude of the target gasket under temperature interference only.

[0025] Furthermore, the constructing error function includes:

[0026] Performing negative correlation mapping on each frequency value of the frequency domain signal to obtain a reference weight for each frequency of the frequency domain signal;

[0027] Construct an error function, which is:

[0028]

[0029] in, represents the error function; The frequency domain signal The reference weight of each frequency; Indicates the The frequency domain signal of the gasket is The amplitude of the frequency; Indicates about The overall amplitude function of each gasket; It indicates the number of frequencies contained in the frequency domain signal. The number of frequencies contained in the frequency domain signal of each gasket is equal. Indicates the number of spacers.

[0030] Furthermore, obtaining the damage representation coefficient of the frequency domain signal of the target gasket at each frequency includes:

[0031] Taking any frequency of the frequency domain signal as the target frequency, and taking the absolute value of the difference in amplitude between the frequency domain signal of the target gasket and each other gasket at the target frequency as the amplitude difference value between the frequency domain signal of the target gasket and each other gasket at the target frequency;

[0032] Taking the average of the amplitude difference values between the frequency domain signals of the target gasket and all other gaskets at the target frequency as the amplitude difference degree of the frequency domain signal of the target gasket at the target frequency;

[0033] The absolute value of the difference between the amplitude of the frequency domain signal of the target gasket at the target frequency and the overall amplitude of the target gasket is used as the degree to which the frequency domain signal of the target gasket is not affected by temperature at the target frequency;

[0034] The amplitude difference degree and the degree of non-temperature interference are combined to obtain a damage representation coefficient of the frequency domain signal of the target gasket at the target frequency.

[0035] Furthermore, obtaining the damage probability of the target gasket includes:

[0036] Taking the product value of each frequency value of the frequency domain signal of the target gasket and the damage manifestation coefficient of the frequency domain signal of the target gasket at each frequency as the adjusted damage manifestation degree of the frequency domain signal of the target gasket at each frequency;

[0037] The average value of the adjusted damage representation degree of the frequency domain signal of the target gasket at all frequencies is normalized to obtain the damage possibility of the target gasket.

[0038] Furthermore, the damage detection of each gasket includes:

[0039] The gasket whose damage possibility is greater than the preset possibility threshold is regarded as a damaged gasket.

[0040] The present invention also proposes a fault detection system for a plate heat exchanger, the system comprising:

[0041] A data acquisition module is used to obtain the temperature signal and time domain signal of vibration of each metal plate of the plate heat exchanger during operation;

[0042] The first analysis module is configured to use any gasket of the plate heat exchanger as a target gasket, and two metal plates adjacent to the target gasket as reference metal plates for the target gasket, and obtain a fusion weight of the time domain signal of each reference metal plate at each moment based on the difference in fluctuations between the time domain signal and the temperature signal of each reference metal plate; and to fuse the time domain signals of the reference metal plates and perform frequency domain conversion based on the fusion weight of the time domain signal of each reference metal plate at each moment to obtain a frequency domain signal of the target gasket;

[0043] The second analysis module is configured to obtain the overall amplitude of the target gasket under temperature interference only based on the amplitudes of the frequency domain signals of all gaskets at the same frequency and the serial number corresponding to the target gasket; obtain the damage manifestation coefficient of the frequency domain signal of the target gasket at each frequency based on the amplitude difference between the frequency domain signals of the target gasket and other gaskets other than the target gasket at the same frequency, and the difference between the amplitude of the frequency domain signal of the target gasket at each frequency and the overall amplitude; and obtain the damage possibility of the target gasket based on the damage manifestation coefficient of the frequency domain signal of the target gasket at all frequencies;

[0044] The damage detection module is used to perform damage detection on each gasket based on the damage possibility of each gasket.

[0045] The present invention also proposes a fault detection device for a plate heat exchanger, which includes a memory, a processor, and a computer program stored in the memory and runnable on the processor. When the processor executes the computer program, it implements any one of the steps of a fault detection method for a plate heat exchanger.

[0046] The present invention has the following beneficial effects:

[0047] The present invention takes into account that the vibration signal generated by temperature change will interfere with the vibration characteristics caused by fluid leakage due to gasket damage, thereby reducing the accuracy of heat exchanger gasket damage detection. Therefore, the temperature signal and the time domain signal of vibration of each metal plate of the plate heat exchanger are first obtained, and the reference value of the amplitude of the time domain signal of each reference metal plate at each moment during subsequent signal fusion is reflected by the obtained fusion weight, so that the fused time domain signal can better represent the time domain signal of vibration of the target gasket and accurately obtain the frequency domain signal of the target gasket. Since the vibration signal generated by temperature change will interfere with the vibration signal generated when the target gasket is damaged, the frequency domain signal of the target gasket cannot accurately express the vibration characteristics when it is damaged. Therefore, the overall amplitude is first obtained to reflect the overall level of the amplitude of the frequency domain signal of the target gasket when it is only affected by temperature, which is convenient for subsequent reduction The interference of low temperature changes on damage analysis is that when the damage and temperature changes of the target gasket are not considered, the amplitudes of the frequency domain signals of each gasket at the same frequency tend to be consistent, and the greater the difference between the amplitude of the frequency domain signal of the target gasket at a certain frequency and the overall amplitude, the less the frequency domain signal is affected by the temperature change at this frequency. At the same time, when the amplitude of the frequency domain signals between the target gasket and other gaskets shows poor consistency at this frequency, it means that the target gasket shows more obvious damage characteristics at this frequency. Therefore, the damage manifestation coefficient can be used to reflect the degree of target gasket damage shown by the frequency domain signal of the target gasket at each frequency, thereby reducing the interference of the vibration signal generated by temperature change on the vibration characteristic analysis of gasket damage, and then reflecting the possibility of damage to the target gasket through the damage possibility. Damage detection of each gasket is performed based on the damage possibility, thereby improving the accuracy of damage detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the technical solutions and advantages of the embodiments of the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0049] Figure 1A flow chart of a fault detection method for a plate heat exchanger provided in one embodiment of the present invention;

[0050] Figure 2 A schematic diagram of temperature signals of two adjacent metal plates provided by an embodiment of the present invention;

[0051] Figure 3 A schematic diagram of a time domain signal of vibration of two adjacent metal plates provided by an embodiment of the present invention;

[0052] Figure 4 A schematic diagram of a fused time domain signal of vibration of a target gasket provided by one embodiment of the present invention;

[0053] Figure 5 A schematic diagram of a frequency domain signal of a target gasket provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0054] To further illustrate the technical means and effectiveness of the present invention in achieving its intended objectives, the following, in conjunction with the accompanying drawings and preferred embodiments, provides a detailed description of a fault detection method, system, and device for a plate heat exchanger according to the present invention, including its specific implementation, structure, features, and effectiveness. In the following description, references to "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics of one or more embodiments may be combined in any suitable manner.

[0055] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0056] The following describes in detail a method, system and device for fault detection of a plate heat exchanger provided by the present invention with reference to the accompanying drawings.

[0057] See also Figure 1 , which shows a flow chart of a fault detection method for a plate heat exchanger provided by one embodiment of the present invention, the method comprising:

[0058] Step S1: Acquire the temperature signal and the time domain signal of vibration of each metal plate of the plate heat exchanger during operation.

[0059] Plate heat exchangers are typically composed of metal plates, channels, and sealing gaskets. Sealing gaskets are typically installed between adjacent metal plates to isolate and seal the fluids, preventing mixing or leakage between channels.

[0060] In the embodiment of the present invention, an acceleration sensor and a temperature sensor are first installed on each metal plate. The acceleration sensor is used to collect the time domain signal of the vibration of each metal plate of the plate heat exchanger during operation, that is, the vibration signal in the time domain. Figure 3 , which shows a schematic diagram of the time domain signal of vibration of two adjacent metal plates provided by an embodiment of the present invention, wherein the time domain signal includes the amplitude at different times, and then the temperature signal of each metal plate of the plate heat exchanger during operation is collected by a temperature sensor, see Figure 2 , which shows a schematic diagram of temperature signals of two adjacent metal plates provided by an embodiment of the present invention, wherein the temperature signals include temperature data at different moments.

[0061] It should be noted that the data acquisition frequency of the acceleration sensor and the temperature sensor is the same. In one embodiment of the present invention, the data acquisition frequency of the two is set to 100 Hz. The specific value of the data acquisition frequency can also be set by the implementer according to the specific implementation scenario and is not limited here.

[0062] It should be noted that multiple metal plates of a plate heat exchanger are arranged to form a channel, and the fluid flows in the channel. In order to facilitate the calculation and analysis of subsequent steps, in the embodiment of the present invention, after the fluid enters the channel, the gaskets of the plate heat exchanger are numbered according to the order in which the fluid flows. For example, after the fluid enters the channel, the serial number of the first gasket it flows through is set to the value 1, the serial number of the second gasket it flows through is set to the value 2, and so on.

[0063] Step S2: Take any gasket of the plate heat exchanger as the target gasket, and take the two metal plates adjacent to the target gasket as the reference metal plates of the target gasket. According to the difference in fluctuations between the time domain signal and the temperature signal of each reference metal plate, obtain the fusion weight of the time domain signal of each reference metal plate at each moment; according to the fusion weight of the time domain signal of each reference metal plate at each moment, fuse the time domain signals of the reference metal plates and perform frequency domain conversion to obtain the frequency domain signal of the target gasket.

[0064] The embodiment of the present invention needs to detect whether the gasket is damaged and causes fluid leakage by analyzing the vibration characteristics of the gasket. Therefore, any gasket of the plate heat exchanger is first used as the target gasket. Since the embodiment of the present invention arranges the sensor on the metal plate, it is necessary to use the vibration signal of the metal plate to analyze the vibration signal of the gasket. When analyzing the vibration signal of the target gasket, its two adjacent metal plates are in direct contact with the target gasket. Therefore, the reference of the two metal plates adjacent to the target gasket is the greatest. Therefore, the two metal plates adjacent to the target gasket can be used as reference metal plates for the target gasket.

[0065] Since metal materials have thermal expansion characteristics, when the temperature rises, the metal plate will expand, resulting in changes in its shape and size. Especially when the temperature fluctuates rapidly, the metal plate will expand and contract rapidly with the temperature change. This rapid expansion and contraction will cause the plate to deform violently, thereby increasing the fluctuation of the vibration amplitude. Therefore, the temperature fluctuation is directly proportional to the change of the vibration amplitude, that is, the more violent the temperature fluctuation, the more obvious the change of the vibration amplitude. Therefore, the more consistent the fluctuation between the time domain signal and the temperature signal of a reference metal plate is, the more the temperature change affects the time domain signal of the reference metal plate. The more consistent and stable the time domain signal of the reference metal plate is, the greater the reference value of the time domain signal of the reference metal plate in the subsequent fusion process. Therefore, the fusion weight of the time domain signal of each reference metal plate at each moment can be obtained according to the difference in fluctuations between the time domain signal and the temperature signal of each reference metal plate, and the amplitude difference between the time domain signals of the two reference metal plates at the same moment. The fusion weight reflects the reference value of the amplitude of the time domain signal of each reference metal plate at each moment when the signal fusion is performed subsequently, so that the fused time domain signal can better represent the time domain signal of the target gasket about vibration, and accurately obtain the frequency domain signal of the target gasket.

[0066] Preferably, in one embodiment of the present invention, the method for obtaining the fusion weight of the time domain signal of each reference metal plate at each moment specifically includes:

[0067] Taking any reference metal sheet as a target reference metal sheet;

[0068] Based on the calculation formula of the effective coefficient, the effective coefficient of the time domain signal of the target reference metal plate at each moment is obtained. The calculation formula of the effective coefficient is:

[0069]

[0070] in, The time domain signal representing the target reference metal plate is The effective coefficient at each moment; The first time domain signal representing the target reference metal plate The moment and The standard deviation of the amplitudes at all moments between ; The first temperature signal representing the target reference metal plate The moment and The standard deviation of the temperature data at all moments between moments; Indicates that except The number of moments other than the moment; Expressed as a natural constant An exponential function with base , used for negative correlation mapping; Represents a normalization function for normalization processing. In one embodiment of the present invention, the normalization processing can be specifically, for example, maximum and minimum value normalization processing, and the normalization in subsequent steps can all adopt maximum and minimum value normalization processing. In other embodiments of the present invention, other normalization methods can be selected according to the specific range of numerical values, which will not be described in detail.

[0071] It should be noted that the The moment and All moments between the moments including the The moment and A moment.

[0072] in, The smaller it is, the higher the time domain signal of the target reference metal plate is. The moment and The amplitude fluctuation between the moments, and the temperature signal at the The moment and The greater the consistency of the temperature data fluctuation between the moments, the greater the consistency of the time domain signal of the target reference metal plate. The greater the amplitude at each moment, the greater the reference value in subsequent signal fusion.

[0073] It should be noted that in other embodiments of the present invention, negative correlation mapping may be achieved through other basic mathematical operations, which will not be described in detail here.

[0074] The effective coefficient of the time domain signal of each reference metal plate at each moment can be obtained by the same method as above.

[0075] Then, the effective coefficients of the time domain signal of the target reference metal plate at each moment can be normalized to obtain the fusion weight of the time domain signal of the target reference metal plate at each moment, wherein the sum of the fusion weights of the time domain signals of the two reference metal plates of the target gasket at the same moment is equal to the value 1.

[0076] In one embodiment of the present invention, the effective coefficient of the time domain signal of the target reference metal plate at each moment can be used as the numerator, the sum of the effective coefficients of the time domain signals of the two reference metal plates at each moment can be used as the denominator, and the ratio can be used as the fusion weight of the time domain signal of the target reference metal plate at each moment, thereby achieving normalization processing of the effective coefficient of the time domain signal of the target reference metal plate at each moment, and ensuring that the sum of the fusion weights of the time domain signals of the two reference metal plates of the target gasket at the same moment is equal to the value 1.

[0077] As an example, in one embodiment of the present invention, the expression of the fusion weight of the time domain signal of the target reference metal plate at each moment can be specifically, for example, as follows:

[0078]

[0079] in, The time domain signal representing the target reference metal plate is The fusion weight at each moment; The time domain signal representing the target reference metal plate is The effective coefficient at each moment; The time domain signal of another reference metal plate representing the target gasket in addition to the target reference metal plate is in the first The effective coefficient at a certain moment.

[0080] The same method as above can be used to obtain the time domain signal of each reference metal plate. The fusion weight of each moment. For a certain moment, the larger the fusion weight of the time domain signal of a reference metal plate at that moment is, the larger the reference value of the amplitude of the time domain signal of the reference metal plate at that moment is in the process of fusing the time domain signals of the two reference metal plates. At the same time, when performing damage detection based on the vibration characteristics of the gasket, it is usually necessary to convert the time domain signal of the vibration into the frequency domain. Therefore, according to the fusion weight of the time domain signal of each reference metal plate at each moment, the time domain signals of the reference metal plates can be fused and converted into the frequency domain to obtain the frequency domain signal of the target gasket. Subsequently, damage detection of the target gasket can be performed based on the frequency domain signal.

[0081] Preferably, in one embodiment of the present invention, the method for acquiring the frequency domain signal of the target gasket specifically includes:

[0082] Using the fusion weights of the time domain signals of the two reference metal plates of the target gasket at each moment, perform weighted summation on the amplitudes of the time domain signals of the two reference metal plates at each moment to obtain the fusion amplitude of the target gasket at each moment. The signal composed of the fusion amplitudes of the target gasket at all moments is used as the fusion time domain signal of the target gasket regarding vibration. Figure 4 , which shows a schematic diagram of a fused time domain signal of vibration of a target gasket provided by an embodiment of the present invention.

[0083] As an example, in one embodiment of the present invention, the expression of the fusion amplitude of the target gasket at each moment can be specifically, for example, as follows:

[0084]

[0085] in, Indicates that the target gasket is in The fusion amplitude at each moment; The time domain signal of one of the reference metal sheets representing the target gasket is The fusion weight at each moment; The time domain signal of another reference metal plate representing the target gasket is The fusion weight at each moment; The time domain signal of one of the reference metal sheets representing the target gasket is The amplitude at each moment; The time domain signal of another reference metal plate representing the target gasket is The amplitude at a moment.

[0086] Then, the fused time domain signal of the target gasket about vibration is subjected to Fourier transform to obtain the frequency domain signal of the target gasket. The Fourier transform is a technical means well known to those skilled in the art, which can transform the time domain signal into the frequency domain. It will not be described in detail here. Please refer to Figure 5 , which shows a schematic diagram of a frequency domain signal of a target gasket provided by an embodiment of the present invention, wherein the frequency domain signal includes amplitudes of different frequencies.

[0087] The frequency domain signal of each gasket can be obtained by the same method as above. It should be noted that after the fused time domain signal of each gasket is converted into a frequency domain, the frequency range and quantity of the frequency domain signal of each gasket are the same.

[0088] Step S3: Based on the amplitudes of the frequency domain signals of all gaskets at the same frequency and the serial number corresponding to the target gasket, obtain the overall amplitude of the target gasket under temperature interference only; based on the amplitude difference at the same frequency between the frequency domain signals of the target gasket and other gaskets except the target gasket, and the difference between the amplitude of the frequency domain signal of the target gasket at each frequency and the overall amplitude, obtain the damage manifestation coefficient of the frequency domain signal of the target gasket at each frequency; based on the damage manifestation coefficient of the frequency domain signal of the target gasket at all frequencies, obtain the damage possibility of the target gasket.

[0089] When a plate heat exchanger begins operation, hot fluid typically enters from one inlet, while cold fluid enters from another. The two fluids flow through the channels formed by the alternating metal plates, passing through each metal plate and the gaskets between the metal plates, and exchanging heat through the thin walls between each metal plate. In the initial stage of the fluid entering the channel, due to the large temperature difference between the hot and cold fluids, the temperature difference between the metal plates is also significant. The large temperature difference makes heat transfer more rapid and the temperature fluctuations between the metal plates more intense, thereby causing strong vibration with a large amplitude. As the hot and cold fluids exchange some heat and continue to flow through subsequent metal plates, the temperature difference gradually decreases, resulting in a decrease in the frequency and amplitude of the vibration. Therefore, the embodiment of the present invention first obtains the overall amplitude of the target gasket under temperature interference based on the amplitude of the frequency domain signals of all gaskets at the same frequency and the serial number corresponding to the target gasket. The overall amplitude reflects the overall level of the amplitude of the frequency domain signal of the target gasket under the influence of temperature alone, which facilitates the subsequent reduction of the interference of temperature changes on damage analysis.

[0090] Preferably, in one embodiment of the present invention, the method for obtaining the overall amplitude of the target gasket only under temperature interference specifically includes:

[0091] From the above analysis, we can see that after the fluid enters the channel, as the fluid flows through each gasket, the vibration amplitude of the gasket closer to the back becomes smaller, that is, the vibration amplitude of the gasket with a larger sequence number becomes smaller. Based on this rule, the overall amplitude function of each gasket can be constructed. The overall amplitude function is:

[0092]

[0093] in, Indicates about The overall amplitude function of the gasket, whose independent variable is the The serial number of each gasket ; 、 、 and Represent four unknown parameters respectively; Represents a natural constant.

[0094] Then, the error function is constructed based on the amplitude of the same frequency of the frequency domain signal of all gaskets and the overall amplitude function, where the error function contains 、 、 and Four unknown parameters.

[0095] Preferably, in one embodiment of the present invention, the method for constructing the error function specifically includes:

[0096] For the frequency domain signal of the gasket, the thermal expansion and contraction effects caused by temperature changes are usually concentrated in the low-frequency area. The amplitude of the low-frequency part of the frequency domain signal contributes more to the analysis of the overall amplitude. Therefore, each frequency value of the frequency domain signal is first negatively correlated to obtain the reference weight of each frequency of the frequency domain signal.

[0097] Then construct the error function, which is:

[0098]

[0099]

[0100] in, represents the error function; The frequency domain signal The reference weight of each frequency; Indicates the The frequency domain signal of the gasket is The amplitude of the frequency; Indicates about The overall amplitude function of each gasket; It indicates the number of frequencies contained in the frequency domain signal. The number of frequencies contained in the frequency domain signal of each gasket is equal. Indicates the number of gaskets; The frequency domain signal frequency values; Indicates the preset adjustment parameter, used to prevent the denominator from being 0 The value range is set to In one embodiment of the present invention, Set to 0.01, The specific value of can also be set by the implementer according to the specific implementation scenario and is not limited here.

[0101] It should be noted that in other embodiments of the present invention, negative correlation mapping may be achieved through other basic mathematical operations, which will not be described in detail here.

[0102] Finally, the least squares method is used to minimize the error function and calculate 、 、 and The values of the four unknown parameters and 、 、 and The values of the four unknown parameters and the serial number corresponding to the target gasket are substituted into the overall amplitude function to obtain the overall amplitude of the target gasket under temperature interference only. The least squares method is a technical means well known to those skilled in the art and will not be described in detail here.

[0103] Under normal operating conditions of the plate heat exchanger, if the vibration effects of sealing gasket damage and temperature changes are not considered, the frequency domain signal of the gasket is generated by the overall working environment and system dynamic characteristics of the plate heat exchanger. Since all gaskets are subjected to similar fluid flows under the same operating conditions, the pressure fluctuations and turbulence generated when the fluid flows in each channel will have similar vibration effects on each gasket. In addition, the gaskets are usually arranged symmetrically, and their structures, sizes and materials are the same or very similar. These factors make the mechanical loads and vibration sources of each gasket very similar. Therefore, without considering the effects of damage and temperature, the amplitudes of the frequency domain signals of each gasket at the same frequency tend to be consistent, and the greater the difference between the amplitude of the frequency domain signal of the target gasket at a certain frequency and the overall amplitude, the higher the vibration effect. The frequency domain signal is less affected by the temperature change at this frequency. At the same time, when the amplitude of the frequency domain signals between the target gasket and other gaskets at this frequency is less consistent, it means that the target gasket shows more obvious damage characteristics at this frequency. Therefore, the damage manifestation coefficient of the frequency domain signal of the target gasket at each frequency can be obtained based on the amplitude difference between the frequency domain signals of the target gasket and other gaskets except the target gasket at the same frequency, as well as the difference between the amplitude of the frequency domain signal of the target gasket at each frequency and the overall amplitude. The damage manifestation coefficient reflects the degree of target gasket damage shown by the frequency domain signal of the target gasket at each frequency, thereby reducing the interference of the vibration signal generated by temperature change on the vibration characteristic analysis caused by gasket damage, and improving the accuracy of subsequent gasket damage detection.

[0104] Preferably, in one embodiment of the present invention, the method for obtaining the damage representation coefficient of the frequency domain signal of the target gasket at each frequency specifically includes:

[0105] First, any frequency of the frequency domain signal is taken as the target frequency, and the absolute value of the difference in amplitude between the frequency domain signals of the target gasket and each other gasket at the target frequency is taken as the amplitude difference value between the frequency domain signals of the target gasket and each other gasket at the target frequency, and the average value of the amplitude difference between the frequency domain signals of the target gasket and all other gaskets at the target frequency is taken as the amplitude difference degree of the frequency domain signal of the target gasket at the target frequency. The greater the amplitude difference degree, the poorer the consistency of the amplitude of the frequency domain signals between the target gasket and other gaskets at the target frequency, and the more likely the frequency domain signal of the target gasket is to show damage characteristics at the target frequency.

[0106] Then, the absolute value of the difference between the amplitude of the frequency domain signal of the target gasket at the target frequency and the overall amplitude of the target gasket is used as the degree to which the frequency domain signal of the target gasket is not affected by temperature interference at the target frequency. The greater the degree to which the frequency domain signal of the target gasket is not affected by temperature interference, the less the amplitude of the frequency domain signal of the target gasket at the target frequency is affected by temperature changes. At this time, if the amplitude difference of the frequency domain signal of the target gasket at the target frequency is greater, the frequency domain signal of the target gasket is more likely to show damage characteristics at the target frequency rather than temperature change characteristics.

[0107] Therefore, the degree of amplitude difference and the degree of non-temperature interference can be combined to obtain the damage performance coefficient of the frequency domain signal of the target gasket at the target frequency.

[0108] In an embodiment of the present invention, the sum or product of the amplitude difference and the degree of non-temperature interference can be used as the damage performance coefficient of the frequency domain signal of the target gasket at the target frequency, thereby achieving a combination of the two, which is not limited here.

[0109] As an example, in one embodiment of the present invention, the expression of the damage representation coefficient of the frequency domain signal of the target gasket at the target frequency can be specifically, for example, as follows:

[0110]

[0111] in, The damage performance coefficient of the frequency domain signal of the target gasket at the target frequency; Indicates the amplitude of the frequency domain signal of the target gasket at the target frequency; represents the overall amplitude of the target gasket; Indicates the degree to which the frequency domain signal of the target gasket is not affected by temperature at the target frequency; Indicates the first The amplitude of the frequency domain signal of the other gaskets at the target frequency; Indicates the target pad and the The amplitude difference between the frequency domain signals of the other gaskets at the target frequency; Indicates the degree of amplitude difference of the frequency domain signal of the target gasket at the target frequency; Indicates the number of shims other than the target shim.

[0112] The damage performance coefficient of the frequency domain signal of the target gasket at each frequency can be obtained by the same method as above, and then the damage possibility of the target gasket can be obtained according to the damage performance coefficient of the frequency domain signal of the target gasket at all frequencies.

[0113] Preferably, in one embodiment of the present invention, the method for obtaining the damage possibility of the target gasket specifically includes:

[0114] Since gasket damage is generally localized, such as cracks, wear, or local deformation, fluid leakage caused by these localized damages will lead to higher-frequency vibrations. In addition, gasket damage often causes nonlinear behavior of the system. Nonlinear characteristics can enhance high-frequency signal components. For example, when microcracks appear on the surface of the gasket, the pressure fluctuations caused by fluid leakage may cause local nonlinear phenomena such as friction and impact, generating high-frequency vibrations. Therefore, for the frequency domain signal of the target gasket, the high-frequency damage representation coefficient can better reflect the damage characteristics of the target gasket.

[0115] Therefore, the product value of each frequency value of the frequency domain signal of the target gasket and the damage performance coefficient of the frequency domain signal of the target gasket at each frequency can be used as the adjusted damage performance of the frequency domain signal of the target gasket at each frequency, and then the average value of the adjusted damage performance of the frequency domain signal of the target gasket at all frequencies is normalized, and the calculation result is limited to range, thereby obtaining the damage possibility of the target gasket.

[0116] As an example, in one embodiment of the present invention, the expression for the damage probability of the target gasket may be specifically, for example, as follows:

[0117]

[0118] in, Indicates the damage possibility of the target gasket; The frequency domain signal frequency values; The frequency domain signal representing the target gasket is The damage performance coefficient of each frequency; The frequency domain signal representing the target gasket is Adjustment of damage performance of each frequency; Indicates the number of frequencies contained in the frequency domain signal; Represents the normalization function, used for normalization processing.

[0119] The damage probability of each gasket can be obtained by the same method as above.

[0120] Step S4: Based on the damage possibility of each gasket, perform damage detection on each gasket.

[0121] The greater the damage possibility of a gasket, the more likely it is that the gasket will be damaged and cause fluid leakage. Therefore, based on the damage possibility of each gasket, damage detection can be performed on each gasket to improve the accuracy of gasket damage detection in plate heat exchangers.

[0122] Preferably, in one embodiment of the present invention, the method for detecting damage to each gasket specifically includes:

[0123] The gasket with a damage probability greater than the preset probability threshold is regarded as a damaged gasket, wherein the value range of the preset probability threshold is In one embodiment of the present invention, the preset possibility threshold is set to 0.6. The specific value of the preset possibility threshold can also be set by the implementer according to the specific implementation scenario and is not limited here.

[0124] After the damaged gasket is detected, it can be replaced to prevent further damage to the plate heat exchanger.

[0125] One embodiment of the present invention provides a fault detection system for a plate heat exchanger, the system comprising:

[0126] The first analysis module is used to take any gasket of the plate heat exchanger as a target gasket and two metal plates adjacent to the target gasket as reference metal plates for the target gasket. Based on the difference in fluctuations between the time domain signal and the temperature signal of each reference metal plate, the fusion weight of the time domain signal of each reference metal plate at each moment is obtained. Based on the fusion weight of the time domain signal of each reference metal plate at each moment, the time domain signals of the reference metal plates are fused and frequency domain converted to obtain the frequency domain signal of the target gasket.

[0127] The second analysis module is used to obtain the overall amplitude of the target gasket under temperature interference only based on the amplitudes of the frequency domain signals of all gaskets at the same frequency and the serial number corresponding to the target gasket; obtain the damage manifestation coefficient of the frequency domain signal of the target gasket at each frequency based on the amplitude difference between the frequency domain signals of the target gasket and other gaskets except the target gasket at the same frequency, and the difference between the amplitude of the frequency domain signal of the target gasket at each frequency and the overall amplitude; obtain the damage possibility of the target gasket based on the damage manifestation coefficient of the frequency domain signal of the target gasket at all frequencies;

[0128] The damage detection module is used to perform damage detection on each gasket based on the damage possibility of each gasket.

[0129] One embodiment of the present invention provides a fault detection device for a plate heat exchanger, the device comprising a memory, a processor, and a computer program, wherein the memory is used to store the corresponding computer program, and the processor is used to run the corresponding computer program. When the computer program runs in the processor, it can implement the method described in steps S1 to S4.

[0130] It should be noted that the order in which the embodiments of the present invention are described above is for illustrative purposes only and does not necessarily represent the superiority or inferiority of the embodiments. The processes depicted in the accompanying drawings do not necessarily require the specific order or sequential order shown to achieve the desired results. In certain embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0131] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on the differences from other embodiments.

Claims

1. A fault detection method for a plate heat exchanger, characterized in that: The method comprises: Acquire the temperature signal and vibration time domain signal of each metal plate of the plate heat exchanger during operation; Taking any gasket of the plate heat exchanger as the target gasket, and taking the two metal plates adjacent to the target gasket as the reference metal plates of the target gasket, obtaining the fusion weight of the time domain signal of each reference metal plate at each moment based on the difference in fluctuation between the time domain signal and the temperature signal of each reference metal plate; according to the fusion weight of the time domain signal of each reference metal plate at each moment, the time domain signals of the reference metal plates are fused and frequency domain converted to obtain the frequency domain signal of the target gasket; According to the amplitudes of the frequency domain signals of all gaskets at the same frequency and the serial number corresponding to the target gasket, the overall amplitude of the target gasket under temperature interference only is obtained; according to the amplitude difference at the same frequency between the frequency domain signals of the target gasket and other gaskets except the target gasket, and the difference between the amplitude of the frequency domain signal of the target gasket at each frequency and the overall amplitude, the damage manifestation coefficient of the frequency domain signal of the target gasket at each frequency is obtained; according to the damage manifestation coefficient of the frequency domain signal of the target gasket at all frequencies, the damage possibility of the target gasket is obtained; Based on the damage possibility of each gasket, each gasket is tested for damage; The step of obtaining the fusion weight of the time domain signal of each reference metal plate at each moment includes: Taking any reference metal sheet as a target reference metal sheet; Based on the calculation formula of the effective coefficient, the effective coefficient of the time domain signal of the target reference metal plate at each moment is obtained. The calculation formula of the effective coefficient is: in, The time domain signal representing the target reference metal plate is The effective coefficient at each moment; The first time domain signal representing the target reference metal plate The moment and The standard deviation of the amplitudes at all moments between ; The first temperature signal representing the target reference metal plate The moment and The standard deviation of the temperature data at all moments between moments; Indicates that except The number of moments other than the moment; Expressed as a natural constant An exponential function with base ; represents the normalization function; Normalizing the effective coefficients of the time domain signal of the target reference metal sheet at each moment to obtain a fusion weight of the time domain signal of the target reference metal sheet at each moment, wherein the sum of the fusion weights of the time domain signals of the two reference metal sheets of the target gasket at the same moment is equal to 1; The obtaining of the overall amplitude of the target gasket under temperature interference only includes: Construct an overall amplitude function for each gasket, which is: in, Indicates about The overall amplitude function of the gasket, whose independent variable is the The serial number of each gasket ; 、 、 and Represent four unknown parameters respectively; represents a natural constant; According to the amplitude of the same frequency of the frequency domain signals of all gaskets and the overall amplitude function, an error function is constructed, and the error function includes 、 、 and Four unknown parameters; Use the least squares method to minimize the error function and calculate 、 、 and The values of the four unknown parameters and 、 、 and The values of the four unknown parameters and the serial number corresponding to the target gasket are substituted into the overall amplitude function to obtain the overall amplitude of the target gasket under temperature interference only.

2. A fault detection method for a plate heat exchanger according to claim 1, characterized in that: The obtaining of the frequency domain signal of the target gasket comprises: Using the fusion weights of the time domain signals of the two reference metal plates of the target gasket at each moment, weighted summing the amplitudes of the time domain signals of the two reference metal plates at each moment is performed to obtain a fused amplitude of the target gasket at each moment, and using a signal composed of the fused amplitudes of the target gasket at all moments as a fused time domain signal of the target gasket regarding vibration; Perform Fourier transform on the fused time domain signal of the target gasket regarding vibration to obtain a frequency domain signal of the target gasket.

3. A fault detection method for a plate heat exchanger according to claim 1, characterized in that: The error function construction includes: Performing negative correlation mapping on each frequency value of the frequency domain signal to obtain a reference weight for each frequency of the frequency domain signal; Construct an error function, which is: in, represents the error function; The frequency domain signal The reference weight of each frequency; Indicates the The frequency domain signal of the gasket is The amplitude of the frequency; Indicates about The overall amplitude function of each gasket; It indicates the number of frequencies contained in the frequency domain signal. The number of frequencies contained in the frequency domain signal of each gasket is equal. Indicates the number of spacers.

4. A fault detection method for a plate heat exchanger according to claim 1, characterized in that: The damage performance coefficient of the frequency domain signal of the target gasket at each frequency is obtained by: Taking any frequency of the frequency domain signal as the target frequency, and taking the absolute value of the difference in amplitude between the frequency domain signal of the target gasket and each other gasket at the target frequency as the amplitude difference value between the frequency domain signal of the target gasket and each other gasket at the target frequency; Taking the average of the amplitude difference values between the frequency domain signals of the target gasket and all other gaskets at the target frequency as the amplitude difference degree of the frequency domain signal of the target gasket at the target frequency; The absolute value of the difference between the amplitude of the frequency domain signal of the target gasket at the target frequency and the overall amplitude of the target gasket is used as the degree to which the frequency domain signal of the target gasket is not affected by temperature at the target frequency; The amplitude difference degree and the degree of non-temperature interference are combined to obtain a damage representation coefficient of the frequency domain signal of the target gasket at the target frequency.

5. A fault detection method for a plate heat exchanger according to claim 1, characterized in that: The damage possibilities of obtaining the target gasket include: Taking the product value of each frequency value of the frequency domain signal of the target gasket and the damage manifestation coefficient of the frequency domain signal of the target gasket at each frequency as the adjusted damage manifestation degree of the frequency domain signal of the target gasket at each frequency; The average value of the adjusted damage representation degree of the frequency domain signal of the target gasket at all frequencies is normalized to obtain the damage possibility of the target gasket.

6. A fault detection method for a plate heat exchanger according to claim 1, characterized in that: The damage detection of each gasket includes: The gasket whose damage possibility is greater than the preset possibility threshold is regarded as a damaged gasket.

7. A fault detection system for a plate heat exchanger, characterized in that: The system comprises: A data acquisition module is used to obtain the temperature signal and time domain signal of vibration of each metal plate of the plate heat exchanger during operation; The first analysis module is configured to use any gasket of the plate heat exchanger as a target gasket, and two metal plates adjacent to the target gasket as reference metal plates for the target gasket, and obtain a fusion weight of the time domain signal of each reference metal plate at each moment based on the difference in fluctuations between the time domain signal and the temperature signal of each reference metal plate; and to fuse the time domain signals of the reference metal plates and perform frequency domain conversion based on the fusion weight of the time domain signal of each reference metal plate at each moment to obtain a frequency domain signal of the target gasket; The second analysis module is configured to obtain the overall amplitude of the target gasket under temperature interference only based on the amplitudes of the frequency domain signals of all gaskets at the same frequency and the serial number corresponding to the target gasket; obtain the damage manifestation coefficient of the frequency domain signal of the target gasket at each frequency based on the amplitude difference between the frequency domain signals of the target gasket and other gaskets other than the target gasket at the same frequency, and the difference between the amplitude of the frequency domain signal of the target gasket at each frequency and the overall amplitude; and obtain the damage possibility of the target gasket based on the damage manifestation coefficient of the frequency domain signal of the target gasket at all frequencies; A damage detection module is used to perform damage detection on each gasket based on the damage possibility of each gasket; The step of obtaining the fusion weight of the time domain signal of each reference metal plate at each moment includes: Taking any reference metal sheet as a target reference metal sheet; Based on the calculation formula of the effective coefficient, the effective coefficient of the time domain signal of the target reference metal plate at each moment is obtained. The calculation formula of the effective coefficient is: in, The time domain signal representing the target reference metal plate is The effective coefficient at each moment; The first time domain signal representing the target reference metal plate The moment and The standard deviation of the amplitudes at all moments between ; The first temperature signal representing the target reference metal plate The moment and The standard deviation of the temperature data at all moments between moments; Indicates that except The number of moments other than the moment; Expressed as a natural constant An exponential function with base ; represents the normalization function; Normalizing the effective coefficients of the time domain signal of the target reference metal sheet at each moment to obtain a fusion weight of the time domain signal of the target reference metal sheet at each moment, wherein the sum of the fusion weights of the time domain signals of the two reference metal sheets of the target gasket at the same moment is equal to 1; The obtaining of the overall amplitude of the target gasket under temperature interference only includes: Construct an overall amplitude function for each gasket, which is: in, Indicates about The overall amplitude function of the gasket, whose independent variable is the The serial number of each gasket ; 、 、 and Represent four unknown parameters respectively; represents a natural constant; According to the amplitude of the same frequency of the frequency domain signals of all gaskets and the overall amplitude function, an error function is constructed, and the error function includes 、 、 and Four unknown parameters; Use the least squares method to minimize the error function and calculate 、 、 and The values of the four unknown parameters and 、 、 and The values of the four unknown parameters and the serial number corresponding to the target gasket are substituted into the overall amplitude function to obtain the overall amplitude of the target gasket under temperature interference only.

8. A fault detection device for a plate heat exchanger, the device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 6 are implemented.

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