Lithium iron phosphate rotary kiln sealing failure fault diagnosis method and system

Abstract

The invention belongs to the technical field of industrial automation control and fault diagnosis, and relates to a lithium iron phosphate rotary kiln sealing failure fault diagnosis method and system. The method comprises the steps that the instantaneous pressure of a sealed cavity, the rotation angle of a barrel, the surface temperature and the accumulative operation time are collected; a rotation modulation leakage index is calculated based on the instantaneous pressure and the rotation angle, and periodic respiration effect characteristics caused by cylinder eccentricity are extracted through angle weighting; calculating a thermal creep correction factor based on time and temperature, and quantifying the aging tendency of the material; and the two are fused to calculate a sealing failure risk index, and graded early warning or shutdown control is executed accordingly. According to the method, early deformation leakage can be found in advance when the sealing pressure does not fall to the threshold value, the diagnosis standards under the equipment aging and high-temperature working conditions are corrected in a self-adaptive mode, and the accuracy and timeliness of fault diagnosis are effectively improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of industrial automation control and fault diagnosis, and particularly relates to a lithium iron phosphate rotary kiln sealing failure fault diagnosis method and system. BACKGROUND

[0002] In the sintering process of lithium iron phosphate material, the rotary kiln is the core heating equipment, and its running stability directly determines the crystal structure and electrochemical performance of the product. Since the sintering process is extremely sensitive to oxidation, the kiln must continuously introduce inert gases such as nitrogen to maintain a micro-positive pressure environment to ensure the stability of the material's valence and phase purity. Therefore, the sealing performance of the kiln head and tail of the rotary kiln is crucial to block the entry of external air and prevent the leakage of internal gas.

[0003] For the special working conditions of high temperature and dynamic rotation of the rotary kiln, the current mainstream in the industrial field adopts a composite sealing structure of mechanical sealing and gas sealing. Its working principle is to inject a protective gas with a specific pressure into the cavity formed by the mechanical sealing to build a gas curtain barrier with a pressure higher than that in the kiln and the environment. The existing sealing failure monitoring method mainly relies on a pressure transmitter to monitor the pressure value in the gas seal cavity. When the detected pressure is lower than the preset fixed alarm threshold, the system determines that the sealing leaks and triggers an alarm. However, the rotary kiln is usually tens of meters long, and the suspended section of the cylinder is prone to irreversible material creep and deflection deformation under the dual action of high-temperature thermal stress and its own gravity moment. This deformation causes the cylinder cross-section to gradually degenerate from an ideal circle to an ellipse, producing a periodic eccentric beating during rotation, which causes the sealing gap to periodically expand and contract with the rotation angle, i.e., the so-called breathing effect. The existing monitoring system usually processes the pressure signal through low-pass filtering, regarding the high-frequency pressure fluctuations caused by the periodic changes in the gap as background noise or being arithmetically averaged. This makes the system unable to issue an early warning in a timely manner when the sealing structure is physically damaged, as the average pressure has not fallen below the threshold, leading to the evolution of the fault into a serious accident.

[0004] In addition, the operation of the rotary kiln is a process involving thermal, force, and flow coupling. As the cumulative running time of the equipment increases and the sintering temperature curve is adjusted, the thermal expansion and cumulative creep of the cylinder material will cause the reference gap of the sealing interface to dynamically drift. The existing fixed threshold method cannot adapt to this dynamic working condition and is prone to false negatives during normal thermal expansion or false positives during severe high-temperature creep. The existing technology breaks the internal physical connection between mechanical rotation, material thermal aging characteristics, and sealing cavity pressure, and a single pressure indicator cannot distinguish between transient pressure drop caused by fluctuations in the gas supply source and structural leakage caused by permanent deformation of the cylinder. This lack of diagnostic dimension makes it difficult for field maintenance personnel to quickly locate the root cause of the fault, often missing the best equipment maintenance window. SUMMARY

[0005] The purpose of the present application is to provide a lithium iron phosphate rotary kiln sealing failure fault diagnosis method and system to solve the technical problems that the existing fixed threshold monitoring method cannot identify the periodic leakage caused by the eccentricity of the cylinder, and it is difficult to adapt to the sealing reference drift caused by equipment aging and high temperature creep, thereby causing false positives or false negatives.

[0006] To solve the above problems, the technical scheme of the lithium iron phosphate rotary kiln sealing failure fault diagnosis method provided by the present application is: The lithium iron phosphate rotary kiln sealing failure fault diagnosis method comprises the following steps: Collecting the instantaneous pressure of the rotary kiln sealing cavity, the rotation angle of the cylinder, the surface temperature of the cylinder, and the cumulative effective running time of the rotary kiln, and preprocessing the collected data; Based on the instantaneous pressure and the rotation angle, a rotation modulation leakage index is calculated, which is used to represent the periodic fluctuation intensity of the sealing cavity pressure with the rotation angle within one rotation period, so as to identify the structural leakage caused by the eccentric deformation of the cylinder; Based on the cumulative effective running time and the surface temperature of the cylinder, a thermal creep correction factor is calculated, which is used to evaluate the tendency of permanent deformation of the cylinder material under the current temperature and time accumulation; The rotation modulation leakage index and the thermal creep correction factor are used to calculate a sealing failure risk index, which is compared with a preset warning threshold and a shutdown threshold, and a corresponding graded warning or shutdown control strategy is executed according to the comparison result.

[0007] Further, the collection of the instantaneous pressure of the rotary kiln sealing cavity comprises: collecting the instantaneous pressure of the cavity gas at the sealing cavity inlet of the rotary kiln head and tail through a high-frequency pressure transmitter, and the sampling frequency is set to more than 10 times the rotation frequency of the rotary kiln.

[0008] Further, the preprocessing of the collected data comprises: aligning the collected data with time stamps, and filtering out high-frequency electromagnetic noise with a low-pass filter to retain pressure signal components with the same frequency and multiple frequencies as the rotation frequency; set the minimum working pressure threshold, only when the instantaneous pressure is greater than the minimum working pressure threshold, execute the subsequent calculation.

[0009] Further, the rotation modulation leakage index satisfies the expression:

[0010] In the formula, is the rotation modulation leakage index, is the total number of sampling points within one rotation period, is the instantaneous pressure value of the i-th sampling point, is the arithmetic mean of pressure values of all sampling points in the rotation period, is the rotation angle of the i-th sampling point, is the rotation angle of the i-th sampling point, is the gravity phase offset angle.

[0011] Further, the gravity phase offset angle is a constant determined according to the geometric angle between the installation position of the high-frequency pressure transmitter and the maximum gravity subsidence point of the cylinder; the sine term in the expression is used to give higher weight to the pressure fluctuation at the maximum eccentric deformation phase of the cylinder to amplify the periodic leakage characteristics caused by gravity deflection.

[0012] Further, the thermal creep correction factor satisfies the expression:

[0013] In the formula, is the thermal creep correction factor, is the cumulative effective operating time, is the current cylinder surface temperature; is the reference standard temperature for normalizing temperature effects; and is a material empirical coefficient determined according to the cylinder material; the expression is used to reflect the physical characteristics that the creep damage increases logarithmically with time and is accelerated nonlinearly by temperature.

[0014] Further, the reference standard temperature is set to room temperature or the rated operating temperature of the rotary kiln; the material empirical coefficient is used to represent the weight of the rapid development stage of creep at the beginning; the material empirical coefficient is used to represent the acceleration weight of high temperature on steady-state creep.

[0015] Further, the sealing failure risk index is defined as which satisfies the expression: .

[0016] Further, the corresponding hierarchical early warning or shutdown control strategy is executed according to the comparison result, including: When the sealing failure risk index is less than the early warning threshold, it is determined that the rotary kiln is in normal operating condition, and the current control strategy is maintained; When the sealing failure risk index is greater than or equal to the early warning threshold value and less than the shutdown threshold value, it is determined that the rotary kiln is in an early deformation leakage working condition, the inlet valve opening of the sealing gas source is automatically adjusted to increase the gas supply to compensate for the pressure, and a maintenance suggestion for checking the support condition of the rotary kiln roller is generated; When the sealing failure risk index is greater than or equal to the shutdown threshold value, it is determined that the rotary kiln is in a severe sealing structure failure or severe deformation working condition, an audible and light alarm is triggered, the heating power supply is interlocked to reduce the output power, and a safety shutdown program is executed.

[0017] The technical scheme of the lithium iron phosphate rotary kiln sealing failure fault diagnosis system provided by the present application is: The lithium iron phosphate rotary kiln sealing failure fault diagnosis system comprises a processor and a memory, and the memory stores computer program instructions.

[0018] The beneficial effects of the present application are: by constructing the rotation modulation leakage index, the pressure signal of the rotary kiln sealing cavity is associated with the rotation angle of the cylinder, and the periodic pressure fluctuation characteristics caused by the breathing effect can be specifically extracted.

[0019] The present application introduces a thermal creep correction factor, dynamically adjusts the sealing failure judgment standard according to the cumulative effective running time and real-time surface temperature of the rotary kiln.

[0020] In view of the technical pain point that the suspended section of the rotary kiln is prone to gravity sinking, the angle-pressure coupling analysis method is used to effectively distinguish the gas supply fluctuation of the gas source and the structural deformation of the cylinder, and provide a clear mechanical adjustment direction for on-site maintenance. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is the step flow chart of the lithium iron phosphate rotary kiln sealing failure fault diagnosis method of the present application; Figure 2 is the correlation characteristic diagram of the rotary angle of the rotary kiln and the sealing cavity pressure; Figure 3 is the whole life cycle evolution trend diagram of the sealing failure risk index; Figure 4 This is a comparison chart of the timeliness of fault diagnosis between the present invention and existing technologies. Detailed Implementation

[0022] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0023] Specific embodiments of the fault diagnosis method for lithium iron phosphate rotary kiln seal failure proposed in this invention: like Figure 1 As shown, the fault diagnosis method for the seal failure of a lithium iron phosphate rotary kiln includes steps S1 to S4, which are as follows: S1. Collect the instantaneous pressure of the rotary kiln sealing cavity, the rotation angle of the cylinder, the surface temperature of the cylinder, and the cumulative effective operating time of the rotary kiln, and preprocess the collected data.

[0024] Specifically, high-frequency pressure transmitters are installed at the air inlets of the sealed cavities at the kiln head and tail of the rotary kiln to collect the instantaneous pressure of the gas inside the cavities in real time. To capture minute pressure fluctuations with rotation angle, the sampling frequency is set to more than 10 times the rotation frequency. An absolute encoder is installed on the drive motor shaft or the cylinder transmission gear of the rotary kiln to obtain the current rotation angle of the cylinder in real time, with the rotation angle ranging from 0° to 360°. An infrared thermometer or patch thermocouple is deployed on the cylinder surface near the sealing position to monitor the surface temperature of the cylinder in real time. The cumulative effective operating time of the equipment since the last major overhaul or seal replacement is read through the PLC control system.

[0025] The collected data is timestamped and a low-pass filter is used to remove high-frequency electromagnetic noise, retaining pressure signal components that are in sync with or have harmonics of the rotation frequency. A minimum working pressure threshold is set, and the system only initiates subsequent calculations when the rotary kiln speed is stable and the instantaneous pressure exceeds the minimum working pressure threshold. In practical applications, the minimum working pressure threshold is set to 2 kPa.

[0026] Thus, high-frequency synchronous acquisition and preprocessing ensured the spatiotemporal consistency and signal-to-noise ratio of the data for subsequent analysis, laying the foundation for the accurate extraction of rotation-related features.

[0027] S2. Calculate the rotation modulation leakage index based on the instantaneous pressure and rotation angle. The rotation modulation leakage index is used to characterize the intensity of the periodic fluctuation of the pressure in the sealed cavity with the rotation angle within one rotation cycle, so as to identify structural leakage caused by the eccentric deformation of the cylinder.

[0028] Specifically, the discretized weighted root mean square algorithm is used to calculate the first... Rotational modulation leakage index within one rotation cycle It satisfies the following expression:

[0029] wherein, is the rotation modulation leakage index; is the total number of sampling points collected within one rotation cycle; is the instantaneous pressure value of the th sampling point; is the arithmetic mean of pressure values of all sampling points within the rotation cycle, i.e. ; is the rotation angle of the th sampling point; is the gravity phase offset angle.

[0030] The gravity phase offset angle is a constant determined according to the geometric angle between the installation position of the high-frequency pressure transmitter and the maximum gravity subsidence point of the cylinder; the sine term in the expression is used to give higher weight to the pressure fluctuation at the maximum eccentric deformation phase of the cylinder to amplify the periodic leakage characteristics caused by gravity deflection.

[0031] A simple calculation example is given below to demonstrate the calculation process of the expression: Suppose the number of sampling points within one rotation cycle , the average pressure kPa, and the gravity phase offset angle .

[0032] wherein the rotation angle of the cylinder at the 1st sampling point , the sine term is ; the instantaneous pressure value kPa, which is equal to the average pressure, indicating that there is no pressure fluctuation at this position, and term 1 is: .

[0033] The rotation angle of the cylinder at the 2nd sampling point , the sine term is ; the instantaneous pressure value , which is less than the average pressure, indicating that there is a significant pressure drop due to leakage at this position. Since this angle corresponds to the position of the maximum gravity weight, the leakage signal is significantly amplified by the algorithm, and term 2 is: .

[0034] The rotation angle of the cylinder at the 3rd sampling point , the sine term is ; the instantaneous pressure value kPa, which is close to the average level, and there is no pressure fluctuation, and term 3 is 0.

[0035] The rotation angle of the cylinder at the 4th sampling point , the sine term is , the instantaneous pressure value kPa, higher than the average pressure, although there is a pressure deviation with the same amplitude as sampling point 2, but because the fluctuation occurs in the non-sensitive phase, the algorithm determines that it is not a structural leakage characteristic, so the fluctuation signal is suppressed. At this time, term 4 is: .

[0036] Summing the above four terms, the result is 0.005, divided by the number of sampling points 4, 0.00125, and finally the square root is calculated to obtain the rotary modulation leakage index .

[0037] As can be seen, if the traditional variance or root mean square algorithm is used, the sine weight term does not exist, sampling point 2 and sampling point 4 will be considered as equal degree of fluctuation and superimposed, resulting in misjudgment. But in the algorithm of the embodiment, the sine term is introduced to realize selective processing of the signal: At a specific sensitive angle, such as the position where the gravity causes the cylinder to sink the most, i.e. , the pressure abnormal fluctuation is given a higher weight, so that the deformation leakage is sharply captured; at a non-sensitive angle, such as , even if there is a pressure fluctuation, it is considered as an interference signal and is filtered out. This mechanism ensures that the rotary modulation leakage index can accurately represent the structural leakage caused by the rotation of the cylinder.

[0038] This step can extract the pressure fluctuation characteristics that are strongly related to the rotation angle by constructing the rotary modulation leakage index, which directly reflects the periodic change of the sealing gap caused by the eccentricity of the cylinder.

[0039] S3, based on the cumulative effective running time and the cylinder surface temperature, a thermal creep correction factor is calculated, which is used to evaluate the tendency of the cylinder material to permanently deform under the current temperature and time accumulation.

[0040] Specifically, the thermal creep correction factor satisfies the following expression:

[0041] is the thermal creep correction factor, is the cumulative effective running time, is the current cylinder surface temperature; is the reference standard temperature, used for normalizing the temperature effect; and are material empirical coefficients determined according to the cylinder material; the expression is used to reflect the physical properties that the creep damage increases logarithmically with time and is accelerated nonlinearly by temperature.

[0042] In order to verify the dynamic adjustment ability of the thermal creep correction factor , the following calculation parameters are set: the empirical coefficient determined according to the material characteristics of the cylinder , , and the reference standard temperature is set to .

[0043] Scenario one is the initial operation stage of the rotary kiln. In this scenario, the rotary kiln is in a brand-new state just after being put into use, and the cumulative effective running time is 0 hours; at the same time, the rotary kiln is in a cold or normal temperature state, and the cylinder surface temperature is maintained at . Substituting the above formula gives: The result shows that in the ideal state of a new machine and low temperature, the thermal creep correction factor is extremely small, the system has a higher tolerance to pressure fluctuations, and only the basic material safety factor is retained.

[0044] Scenario two is the long-term high-temperature operation stage of the rotary kiln. In this scenario, the rotary kiln has been continuously running for a long period, and the cumulative effective running time reaches 1000 hours, and the rotary kiln is in a high-load heating state, and the cylinder surface temperature is raised to . Substituting the above formula gives: , which reflects the basic damage caused by the accumulation of material fatigue over time; , which reflects the nonlinear acceleration effect of the high-temperature environment on the creep characteristics of the material; Finally, .

[0045] Comparing the above two scenarios, the thermal creep correction factor rises from the initial 0.05 to 0.827, an increase of more than 16 times. This significant change intuitively reflects the gradual weakening of the stability of the rotary kiln material as the running time accumulates and the working temperature rises.

[0046] By introducing the thermal creep correction factor, the system can dynamically adjust the diagnostic standard according to the different stages of the rotary kiln in its entire life cycle: in the case of device aging or high-temperature working conditions, is automatically increased, thereby amplifying the risk index of sealing failure. This means that for the same amplitude of pressure fluctuations, the alarm sensitivity of the aging device will be significantly higher than that of the new device, thereby effectively avoiding the risk of false negatives due to fixed thresholds, and ensuring the accuracy and timeliness of fault diagnosis.

[0047] S4, calculating a sealing failure risk index by using the rotary modulation leakage index and the thermal creep correction factor, comparing the sealing failure risk index with preset early warning threshold and shutdown threshold, and executing corresponding graded early warning or shutdown control strategy according to the comparison result.

[0048] Specifically, the sealing failure risk index is defined as , which satisfies the expression: The formula adopts a multiplication coupling model, is the performance of the risk, is the amplifier of the risk.

[0049] The system presets an early warning threshold and a shutdown threshold , and .

[0050] When , it is determined that the rotary kiln is in a normal running condition, and the current control strategy is maintained; When , it is determined that the rotary kiln is in an early deformation leakage condition, the inlet valve opening degree of the sealing gas source is automatically increased to increase the gas supply amount for pressure compensation, and a maintenance suggestion of checking the support condition of the rotary kiln roller is sent to the central control room.

[0051] When , it is determined that the rotary kiln is in a sealing structure serious failure or cylinder serious deformation condition, an audible and light alarm is triggered, the heating power supply is controlled in interlock to reduce the output power, and a safety shutdown program is executed.

[0052] The technical solutions and technical effects of the present application are further described below in combination with Figure 2 , Figure 3 and Figure 4 .

[0053] As shown in Figure 2 , the dashed line in the figure represents that the rotary kiln is in a new machine or healthy state. At this time, the sealing pressure is maintained near the baseline of 100 kPa, only showing random small fluctuations, and there is no obvious correlation with the rotation angle, indicating that the sealing gap is uniform and the pressure is stable. The solid line in the figure represents the state after the cylinder occurs eccentric deformation, and the pressure curve presents a significant sinusoidal periodic fluctuation, i.e. breathing effect, especially when rotating to about 180° to 270° phase interval, the pressure appears a large amplitude drop. This highly coupled fluctuation characteristic with the rotation angle is the physical basis for calculating the rotary modulation leakage index of the present application.

[0054] Figure 3 The evolution trend of each monitoring index in the whole life cycle of the rotary kiln is shown. Figure 3The dotted line in the figure represents the rotation modulation leakage index, with the increase of the running time, the physical deformation of the cylinder, the rotation modulation leakage index is linearly slow rising, reflecting the physical accumulation of the leakage amount. The dotted line represents the thermal creep correction factor, and the curve thereof increases exponentially with time, objectively reflecting the non-linear acceleration characteristics of the structural vulnerability caused by material aging in high temperature environment with time. The thick solid line represents the final sealing failure risk index, which presents a nonlinear rapid rising trend in the later running period, indicating that the system can automatically adjust the alarm sensitivity according to the aging degree of the equipment, and give higher weight to the small risk in the end of the equipment life, effectively preventing the sudden failure of the aging equipment.

[0055] Figure 4 The present application and the alarm timeliness of the prior art fault diagnosis are compared intuitively. In the figure, the traditional sealing average pressure monitoring curve is averaged due to the pressure fluctuation caused by the breathing effect, and the average pressure decreases extremely slowly, which has obvious hysteresis, and the alarm is triggered until the running time reaches about 900 hours. At this time, the device is often at the edge of serious leakage. The sealing failure risk index curve of the present application benefits from the extraction of the periodic fluctuation characteristics and the correction of the thermal creep factor. The index breaks through the early warning threshold near 500 hours. Compared with the prior art, the present application discovers the potential fault hidden danger about 400 hours in advance, reserves sufficient mechanical adjustment and preventive maintenance window for on-site maintenance, and greatly reduces the risk of unplanned shutdown.

[0056] In this way, by fusing the dynamic leakage characteristics and the structural vulnerability, and implementing hierarchical control, not only the potential mechanical failure can be warned in advance, but also the equipment running time can be automatically adjusted to prolong the running time at the early stage of failure, and finally the production safety is ensured.

[0057] The specific embodiments of the lithium iron phosphate rotary kiln sealing failure fault diagnosis system provided by the present application are as follows: The lithium iron phosphate rotary kiln sealing failure fault diagnosis system comprises a processor and a memory, and the memory stores computer program instructions. When the computer program instructions are executed by the processor, the lithium iron phosphate rotary kiln sealing failure fault diagnosis method in each embodiment is realized.

[0058] The lithium iron phosphate rotary kiln sealing failure fault diagnosis system further comprises a communication bus and a communication interface and other components familiar to those skilled in the art. The settings and functions thereof are known in the art, and therefore will not be described here.

[0059] In this description, the term "application" also means any computer program product storing such a program for use with or in connection with a computer system, apparatus or device. The program can be stored on any apparatus-readable medium, for example, but not limited to, any volatile memory or non-volatile memory. In this description, the term "memory" also means any computer program product storing such a program for use with or in connection with a computer system, apparatus or device. The program can be stored on any apparatus-readable medium, for example, but not limited to, any volatile memory or non-volatile memory. In this description, the term "computer-readable medium" means any tangible medium that stores, communicates, or otherwise provides data that can be used by an instruction execution system, apparatus or device. The computer-readable medium can be any suitable magnetic storage medium or magneto-optical storage medium, such as, for example, resistive random access memory (RRAM), dynamic random access memory (DRAM), static random access memory (SRAM), enhanced dynamic random access memory (EDRAM), high-bandwidth memory (HBM), hybrid memory cube (HMC), etc., or any other medium that can be used to store the desired information and that can be accessed by an application, module or both. Any such computer storage media can be part of the device or accessible or connectable thereto. Any application or module described in this description can be implemented by computer-readable / executable instructions stored or otherwise held by such computer-readable media.

[0060] In the description of the present description, the meaning of "a plurality of" is at least two, for example, two, three or more, etc., unless otherwise explicitly specified.

[0061] Although the present description has shown and described several embodiments of the present application, it will be apparent to those skilled in the art that many modifications, changes and substitutions can be made thereto without departing from the spirit and scope of the present application.

Claims

1. A lithium iron phosphate rotary kiln seal failure diagnostic method, characterized by, The method comprises the following steps: collecting instantaneous pressure of a sealing cavity of a rotary kiln, rotation angle of a cylinder, cylinder surface temperature, and cumulative effective running time of the rotary kiln, and pre-processing the collected data; calculating a rotation modulation leakage index based on the instantaneous pressure and the rotation angle, the rotation modulation leakage index being used to represent periodic fluctuation intensity of the sealing cavity pressure with the rotation angle in a rotation period, so as to identify structural leakage caused by cylinder eccentric deformation; calculating a thermal creep correction factor based on the cumulative effective running time and the cylinder surface temperature, the thermal creep correction factor being used to evaluate the tendency of permanent deformation of the cylinder material under current temperature and time accumulation; calculating a sealing failure risk index by using the rotation modulation leakage index and the thermal creep correction factor, comparing the sealing failure risk index with preset warning threshold and shutdown threshold, and executing corresponding graded warning or shutdown control strategy according to the comparison result.

2. The lithium iron phosphate rotary kiln seal failure diagnostic method of claim 1, wherein, The collecting of the instantaneous pressure of the sealing cavity of the rotary kiln comprises: collecting the instantaneous pressure of the gas in the cavity at the sealing cavity gas inlet at the rotary kiln head and tail by a high-frequency pressure transmitter, and the sampling frequency is set to be more than 10 times of the rotary frequency of the rotary kiln.

3. The lithium iron phosphate rotary kiln seal failure diagnostic method of claim 1, wherein, The pre-processing of the collected data comprises: time stamp alignment of the collected data, filtering of high-frequency electromagnetic noise by using a low-pass filter, and reservation of pressure signal components with the same frequency and multiple frequencies as the rotary frequency; and setting of a minimum working pressure threshold, and only when the instantaneous pressure is greater than the minimum working pressure threshold, the subsequent calculation is executed.

4. The lithium iron phosphate rotary kiln seal failure diagnostic method of claim 2, wherein, The rotation modulation leakage index satisfies the expression: In the formula, The rotation modulation leakage index, The total number of sampling points within one rotation cycle. For the first Instantaneous pressure values ​​at each sampling point It is the arithmetic mean of the pressure values ​​at all sampling points within this rotation cycle. For the first The rotation angle of the cylinder corresponding to each sampling point This is the gravity phase offset angle.

5. The lithium iron phosphate rotary kiln seal failure diagnostic method of claim 4, wherein, The gravity phase bias angle is a constant determined by the geometric angle between the installation position of the high-frequency pressure transmitter and the maximum gravity subsidence point of the cylinder; the sine term in the expression is used to give higher weight to the pressure fluctuation at the maximum eccentric deformation phase of the cylinder to amplify the periodic leakage characteristics caused by gravity deflection.

6. The lithium iron phosphate rotary kiln seal failure diagnostic method of claim 4, wherein, The thermal creep correction factor satisfies the expression: wherein, is the thermal creep correction factor, is the cumulative effective operating time, is the current barrel surface temperature; is the reference standard temperature for normalizing the temperature effect; and is the material empirical coefficient determined according to the barrel material; this expression is used to reflect the physical characteristics that the creep damage increases logarithmically with time and is accelerated by temperature nonlinearly.

7. The lithium iron phosphate rotary kiln seal failure diagnostic method of claim 6, wherein, said reference standard temperature set to ambient temperature or to the rated working temperature of the rotary kiln; material experience coefficient for characterizing the rapid development phase of the incipient creep, said material experience coefficient for characterizing the acceleration of the steady-state creep by the high temperature.

8. The lithium iron phosphate rotary kiln seal failure diagnostic method of claim 6, wherein, The sealing failure risk index is defined as which satisfies the expression: 。 9. The lithium iron phosphate rotary kiln seal failure diagnostic method of claim 1, wherein, The execution of the corresponding graded warning or shutdown control strategy according to the comparison result comprises: when the sealing failure risk index is less than the warning threshold, it is determined that the rotary kiln is in a normal running condition, and the current control strategy is maintained; when the sealing failure risk index is greater than or equal to the warning threshold and less than the shutdown threshold, it is determined that the rotary kiln is in an early deformation leakage condition, the inlet valve opening of the sealing gas source is automatically increased to increase the gas supply amount for pressure compensation, and a maintenance suggestion for checking the supporting condition of the rotary kiln riding wheel is generated; when the sealing failure risk index is greater than or equal to the shutdown threshold, it is determined that the rotary kiln is in a sealing structure serious failure or cylinder serious deformation condition, an audible and light alarm is triggered, the heating power supply is controlled to reduce the output power, and a safety shutdown program is executed.

10. A lithium iron phosphate rotary kiln seal failure diagnostic system, characterized by, The method comprises a processor and a memory, and the memory stores computer program instructions, when the computer program instructions are executed by the processor, the lithium iron phosphate rotary kiln sealing failure fault diagnosis method in any one of claims 1-9 is realized.

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