Boiler drain pipeline inner leakage detection method

Abstract

The invention provides a boiler drainage pipeline inner leakage detection method, and relates to the technical field of pipeline detection, and the method comprises the steps: installing a distributed optical fiber sensor and an acoustic sensor at a key position of a boiler drainage pipeline; transmitting an optical signal in a preset period by using a distributed optical fiber sensor, and receiving and analyzing the transmitted optical signal to obtain highlighted point location information; calculating the temperature change rate of the point location in a continuous period based on a temperature transfer model and the highlighted point location information; collecting sound intensity information by using a distributed acoustic sensor, and analyzing the change rate of the sound intensity information in a continuous period; fusing the temperature change rate and the sound intensity change rate through a preset comprehensive index model, and calculating a comprehensive index; the inner leakage condition of the point location is judged based on the comprehensive index; by fusing the data of the distributed optical fiber sensor and the acoustic sensor, the detection accuracy and reliability are improved, meanwhile, the leakage point can be accurately positioned, and a guarantee is provided for safe operation of the boiler.

Description

Technical Field

[0001] The present invention relates to the technical field of pipeline detection, and particularly to a method for inspecting internal leakage in a boiler drain pipeline. Background Art

[0002] With the development of industrial production, boilers, as important energy conversion devices, are widely used in many fields; the normal operation of boiler drain pipelines is crucial for the safety and efficiency of boilers; however, due to reasons such as pipeline aging, corrosion, and wear, internal leakage problems in drain pipelines occur from time to time; internal leakage not only causes energy loss and increases operating costs, but may also lead to safety accidents;

[0003] In the technical field of pipeline detection, traditional detection methods mainly include manual inspection, ultrasonic detection, infrared thermal imaging detection, etc.; these methods can detect pipeline leakage to a certain extent, but there are some limitations; for example, manual inspection has low efficiency and poor accuracy; ultrasonic detection and infrared thermal imaging detection have high requirements for the surface condition of pipelines, and the detection effect for micro-leakage or internal leakage is not ideal; at the same time, a single sensor detection method is affected by environmental interference, resulting in inaccurate detection results; the data fusion and analysis between different sensors are not sufficient, and their respective advantages cannot be fully utilized; in addition, for some complex pipeline systems, how to accurately locate the leakage point is also an urgent problem to be solved. Summary of the Invention

[0004] The present invention aims to provide a method for inspecting internal leakage in a boiler drain pipeline based on a distributed fiber optic sensor and a distributed acoustic sensor, which improves the accuracy and reliability of detection by fusing the data of the two sensors, and can accurately locate the leakage point at the same time, providing guarantee for the safe operation of the boiler.

[0005] The present invention provides a method for inspecting internal leakage in a boiler drain pipeline, including:

[0006] Step 1, installing a distributed fiber optic sensor and a distributed acoustic sensor at key positions of the boiler drain pipeline;

[0007] Step 2, using the distributed fiber optic sensor to transmit an optical signal at a preset period, and obtaining prominent point information by receiving and analyzing the transmitted optical signal, specifically including temperature information and position information;

[0008] Step 3, calculating the temperature change rate of this point in continuous periods based on the temperature transfer model and the prominent point information;

[0009] Step 4, using the distributed acoustic sensor to collect sound intensity information and analyzing the change rate of the sound intensity information in continuous periods;

[0010] Step Five, fuse the temperature change rate and the sound intensity change rate through a preset comprehensive index model to calculate the comprehensive index;

[0011] Step Six, judge the internal leakage condition of this point based on the comprehensive index.

[0012] According to a method for inspecting internal leakage of a boiler drain pipe provided by the present invention, the distributed optical fiber sensor and the distributed acoustic sensor include:

[0013] The distributed optical fiber sensor includes an optical fiber, a light source, a detector, and a signal processor; the optical fiber is used to transmit optical signals and a reflection point is set at the end, the light source is used to provide optical signals with a specific wavelength for the optical fiber within each preset period, the detector receives the optical signals reflected by the optical fiber and converts them into electrical signals, and the signal processing unit processes and analyzes the electrical signals to extract prominent point information; the prominent point information includes temperature information and position information;

[0014] The distributed acoustic sensor includes an acoustic probe, a signal amplification circuit, and a data processing module; the acoustic probe is used to detect sound signals in the pipeline, the signal amplification circuit is used to amplify weak sound signals, and the data processing module analyzes and processes the amplified sound signals to extract sound intensity information.

[0015] According to a method for inspecting internal leakage of a boiler drain pipe provided by the present invention, the process of the signal processing unit processing and analyzing the electrical signals to extract prominent point information includes:

[0016] S11, obtain temperature information; calculate the temperature distribution along the optical fiber based on the relationship formula between the intensity ratio of Stokes light and anti-Stokes light in Raman scattering and temperature. The formula is:

[0017]

[0018] where, I as is the intensity of anti-Stokes light, I s is the intensity of Stokes light, both obtained based on the analysis of optical signals; A is a proportionality coefficient set through experience and on-site conditions; h is Planck's constant, v is the Raman shift, k is Boltzmann's constant, all of which are theoretical values; T l is the temperature information, used to reflect the temperature distribution along the optical fiber;

[0019] Obtain the intensity I as of anti-Stokes light and the intensity I s of Stokes light in the optical signal through the signal processor, and substitute them into the formula for calculation to obtain the temperature information T l ; preset a temperature threshold. When the temperature information T lWhen the value exceeds the temperature threshold, it is determined that there is an abnormal temperature situation in the pipeline;

[0020] S12, obtain the position information; when it is determined that there is an abnormal temperature situation in the pipeline, based on the optical time domain reflectometry technology, determine the position where the optical signal is scattered in the optical fiber, that is, the optical fiber point corresponding to the position where the pipeline has an abnormal temperature. The calculation formula is:

[0021]

[0022] Among them, D is the position information, which is used to reflect the optical fiber point corresponding to the position of the abnormal temperature pole in the pipeline; v is the speed of the optical signal transmitted in the optical fiber, which is a theoretical value; τ is the round-trip time interval of the optical signal from the light source to the reflection point;

[0023] Obtain the time interval τ of the optical signal through the signal processor, and substitute it into the formula to calculate the position information D;

[0024] S13, fuse the temperature information and the position information to determine the position where there is an abnormal temperature situation in the pipeline.

[0025] According to a method for inspecting internal leakage of a boiler drain pipeline provided by the present invention, the process of calculating the temperature change rate of a point in a continuous cycle based on a temperature transfer model and prominent point information includes:

[0026] S21, obtain the temperature data of the fluid in the pipe and the basic ambient temperature data through sensors;

[0027] S22, establish the temperature transfer model, and the temperature transfer model is:

[0028]

[0029] Among them, is the temperature change rate, representing the change trend of the temperature in the pipeline, t is the time interval corresponding to a continuous preset cycle; K is the heat transfer coefficient, a and b are undetermined coefficients, set based on the actual situation, and are used to reflect the characteristics of the temperature changing with distance; ΔD is the relative distance of multiple position information D i obtained within a continuous preset cycle; e -b*ΔD represents that the smaller the relative distance of the abnormal temperature pole within a continuous cycle, the greater the change trend of the temperature in the pipeline; T l is the temperature information; T u is the temperature data of the fluid in the pipe;

[0030] S23, substitute the current corresponding data into the temperature transfer model to calculate the temperature change rate

[0031] A method for inspecting internal leakage in a boiler drain pipe provided by the present invention, the process of analyzing the change rate of the sound intensity information in consecutive cycles includes:

[0032] S31. Preset the sound intensity under normal conditions and the ideal sound intensity change threshold;

[0033] S32. Determine a plurality of sound intensities S obtained within consecutive preset cycles i , and substitute them into the following formula:

[0034]

[0035] where, is the sound intensity change rate, used to reflect the change trend of the sound signal caused by pipeline leakage; n is the number of a plurality of sound intensities S obtained within consecutive preset cycles i , S 0 is the sound intensity under normal conditions, and ΔS thre is the ideal sound intensity change threshold;

[0036] S33. Output the sound intensity change rate

[0037] A method for inspecting internal leakage in a boiler drain pipe provided by the present invention, the comprehensive index model is:

[0038]

[0039] where, I is the comprehensive index, used to comprehensively reflect the temperature change rate and the sound intensity change rate as well as the relationship between the ambient temperature T v and the leak point temperature T l ; ω 1 , ω 2 , ω 3 are weight coefficients, set based on the on-site situation.

[0040] A method for inspecting internal leakage in a boiler drain pipe provided by the present invention, the process of judging the internal leakage situation at this point based on the comprehensive index includes:

[0041] Preset the standard index threshold, and compare it with the calculated comprehensive index I;

[0042] When the comprehensive index I exceeds the standard index threshold, it is determined that there is an internal leakage situation in the area corresponding to the distributed optical fiber sensor, and the internal leakage point is near the pipe corresponding to the optical fiber position D;

[0043] When the comprehensive index I does not exceed the standard index threshold, it is determined that there is no internal leakage situation.

[0044] A method for inspecting internal leakage of a boiler drain pipe provided by the present invention further includes: triggering an alarm signal when the comprehensive index I exceeds the standard index threshold, and notifying personnel to arrive at the scene for handling.

[0045] A method for inspecting internal leakage of a boiler drain pipe provided by the present invention, wherein the distributed optical fiber sensor and the distributed acoustic sensor are arranged behind the electric valve of the boiler drain pipe.

[0046] Compared with the prior art, the beneficial effects of the present application are as follows:

[0047] The data fusion of the distributed optical fiber sensor and the distributed acoustic sensor is realized, which can obtain pipeline information more comprehensively, effectively reduce the influence of environmental interference on a single sensor, and thus significantly improve the accuracy and reliability of detection;

[0048] The leakage point can be accurately located. With the temperature detection and position determination functions of the distributed optical fiber sensor, combined with the sound intensity detection of the acoustic sensor, the leakage point can be found and accurately located in time, which is convenient for taking effective repair measures and reducing potential losses;

[0049] It has the ability of real-time monitoring. The distributed optical fiber sensor can monitor the temperature change of the pipeline in real time, and the acoustic sensor can synchronously collect the sound intensity information to ensure the timely monitoring of the internal leakage situation of the pipeline, so as to quickly discover problems and handle them;

[0050] It is applicable to complex pipeline systems, can give full play to the advantages of the two sensors, effectively overcome the limitations of traditional detection methods in complex pipeline systems, and provide a more effective solution for pipeline detection;

[0051] It helps to reduce the operation cost. By timely discovering and repairing the internal leakage problem of the pipeline, energy waste can be reduced, the operation cost can be reduced, and the production efficiency can be improved;

[0052] It ensures the safe operation of the boiler. Accurately detecting the internal leakage situation of the pipeline and handling it in time can effectively prevent safety accidents caused by internal leakage and provide guarantee for the stable and safe operation of the boiler.

[0053] Other features and advantages of the present invention will be described in the following specification, and part of them will become obvious from the specification, or be understood by implementing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the structure specifically pointed out in the written specification and the drawings.

[0054] The technical solution of the present invention will be further described in detail below through the drawings and embodiments. Description of the Drawings

[0055] The accompanying drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention, and do not constitute a limitation to the present invention. In the accompanying drawings:

[0056] Figure 1 It is a schematic flowchart of a method for inspecting internal leakage in a boiler drain pipeline provided by an embodiment of the present invention. Detailed implementation manners

[0057] The following describes the preferred embodiments of the present invention with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0058] Embodiment 1:

[0059] This embodiment provides a method for inspecting internal leakage in a boiler drain pipeline. Please refer to Figure 1 , including:

[0060] Step 1, install a distributed optical fiber sensor and a distributed acoustic sensor at key positions of the boiler drain pipeline;

[0061] Step 2, use the distributed optical fiber sensor to transmit optical signals at a preset period, and obtain prominent point information by receiving and analyzing the transmitted optical signals, specifically including temperature information and position information;

[0062] Step 3, calculate the temperature change rate of this point in continuous periods based on the temperature transfer model and the prominent point information;

[0063] Step 4, use the distributed acoustic sensor to collect sound intensity information and analyze the change rate of the sound intensity information in continuous periods;

[0064] Step 5, fuse the temperature change rate and the sound intensity change rate through a preset comprehensive index model to calculate the comprehensive index;

[0065] Step 6, judge the internal leakage situation of this point based on the comprehensive index.

[0066] The principle of the above embodiment is as follows: The distributed optical fiber sensor obtains temperature information and position information by transmitting optical signals and analyzing the changes in the optical signals; the temperature information is calculated based on the relationship between the intensity ratio of Stokes light and anti-Stokes light in Raman scattering and temperature, and the position information is determined by optical time domain reflectometry technology; then, based on the temperature transfer model and this prominent point information, the temperature change rate of this point in continuous periods is calculated; the distributed acoustic sensor is used to collect sound intensity information and analyze its change rate in continuous periods; finally, the temperature change rate and the sound intensity change rate are fused through a preset comprehensive index model to calculate the comprehensive index, so as to judge the internal leakage situation of this point.

[0067] The beneficial effects of the above embodiments are as follows: By integrating the data of distributed fiber optic sensors and distributed acoustic sensors, pipeline information can be comprehensively obtained, reducing the influence of environmental interference on a single sensor and improving the detection accuracy and reliability. Combining the temperature and position detection of distributed fiber optic sensors with the sound intensity detection of acoustic sensors can accurately determine the location of leakage points, facilitating timely repair measures and reducing losses. The two sensors can obtain pipeline temperature and sound intensity information in real time, promptly detect internal leakage in the pipeline, and improve the response speed. By giving full play to the advantages of the two sensors and overcoming the limitations of traditional detection methods in complex pipeline systems, a more effective detection solution is provided.

[0068] To further optimize the above embodiments, the distributed fiber optic sensor and the distributed acoustic sensor include:

[0069] The distributed fiber optic sensor includes an optical fiber, a light source, a detector, and a signal processor; the optical fiber is used to transmit optical signals and a reflection point is set at the end. The light source is used to provide optical signals with a specific wavelength for the optical fiber within each preset period. The detector receives the optical signal reflected by the optical fiber and converts it into an electrical signal. The signal processing unit processes and analyzes the electrical signal to extract prominent point information; the prominent point information includes temperature information and position information;

[0070] The distributed acoustic sensor includes an acoustic probe, a signal amplification circuit, and a data processing module; the acoustic probe is used to detect sound signals in the pipeline, the signal amplification circuit is used to amplify weak sound signals, and the data processing module analyzes and processes the amplified sound signals to extract sound intensity information.

[0071] It should be noted that the distributed fiber optic sensor and the distributed acoustic sensor respectively detect optical signals and sound signals to obtain temperature and sound information in the pipeline, thereby realizing the inspection of internal leakage in the boiler drain pipeline.

[0072] To further optimize the above embodiments, the process by which the signal processing unit processes and analyzes the electrical signal to extract prominent point information includes:

[0073] S11, obtaining temperature information; calculating the temperature distribution along the optical fiber based on the relationship formula between the intensity ratio of Stokes light and anti-Stokes light in Raman scattering and temperature. The formula is:

[0074]

[0075] where I as is the intensity of anti-Stokes light, and I sis the Stokes light intensity, both obtained based on the analysis of the optical signal; A is a proportionality coefficient, set through experience and on-site conditions; h is Planck's constant, v is the Raman frequency shift, k is Boltzmann's constant, all of which are theoretical values; T l is temperature information, used to reflect the temperature distribution along the optical fiber;

[0076] The anti-Stokes light intensity I as and the Stokes light intensity I s in the optical signal are obtained by the signal processor and substituted into the formula for calculation to obtain the temperature information T l ; A temperature threshold is preset. When the value of the temperature information T l exceeds the temperature threshold, it is determined that there is an abnormal temperature situation in the pipeline;

[0077] S12, obtaining the position information; when it is determined that there is an abnormal temperature situation in the pipeline, based on the optical time domain reflectometry technology, the position where the optical signal is scattered in the optical fiber is determined, that is, the optical fiber point corresponding to the position where there is an abnormal temperature in the pipeline. The calculation formula is:

[0078]

[0079] where D is the position information, used to reflect the optical fiber point corresponding to the position of the abnormal temperature pole in the pipeline; v is the transmission speed of the optical signal in the optical fiber, which is a theoretical value; τ is the round-trip time interval of the optical signal from the light source to the reflection point;

[0080] The time interval τ of the optical signal is obtained by the signal processor and substituted into the formula to calculate the position information D;

[0081] S13, fusing the temperature information and the position information to determine the position where there is an abnormal temperature situation in the pipeline.

[0082] It should be noted that when light propagates in the optical fiber, various scattering phenomena will occur, including Rayleigh scattering, Raman scattering, Brillouin scattering, etc.; these scattering effects are closely related to the environmental temperature where the optical fiber is located; in the distributed optical fiber temperature sensor, in this embodiment, the intensity ratio of Stokes light and anti-Stokes light in Raman scattering is used to measure the temperature; the anti-Stokes light is very sensitive to temperature, and its intensity increases with the increase of temperature; while the Stokes light is relatively insensitive to temperature; by measuring the intensities of these two lights and using their specific relationship, the temperature distribution along the optical fiber can be calculated;

[0083] By transmitting pulsed optical signals into the optical fiber and measuring the time delay and intensity of the reflected light, the scattering signals at different positions along the optical fiber can be determined; by combining the relationship between temperature and optical signals, distributed measurement of the temperature along the optical fiber can be achieved; when the pulsed optical signal propagates in the optical fiber, reflected light is generated when encountering different scattering points (caused by temperature changes); according to the propagation time of light, the position of the scattering point can be calculated; by analyzing the intensity and characteristics of the reflected light, the temperature information at that position can be determined.

[0084] To further optimize the above embodiments, the process of calculating the temperature change rate of a point position under continuous cycles based on the temperature transfer model and prominent point position information includes:

[0085] S21, obtaining the in-pipe fluid temperature data and basic ambient temperature data through sensors;

[0086] S22, establishing a temperature transfer model, and the temperature transfer model is:

[0087]

[0088] Wherein, is the temperature change rate, representing the change trend of the temperature inside the pipeline, t is the time interval corresponding to continuous preset cycles; K is the heat transfer coefficient, a and b are undetermined coefficients set based on the actual situation, used to reflect the characteristics of temperature change with distance; ΔD is the relative distance of multiple position information D i obtained within continuous preset cycles; e -b*ΔD represents that the smaller the relative distance of the abnormal temperature poles within continuous cycles, the greater the change trend of the temperature inside the pipeline; T l is the temperature information; T u is the in-pipe fluid temperature data;

[0089] S23, substituting the current corresponding data into the temperature transfer model to calculate the temperature change rate

[0090] It should be noted that, indicates that under the current heat transfer conditions, the temperature detected by the optical fiber per second will increase (if it is a positive value) or decrease (if it is a negative value) degrees Celsius, which reflects the high temperature T at the leakage point lThe heat transfer rate between the current temperature. The heat transfer coefficient determines the rate of this change. On the other hand, this result is of great significance for judging whether there is leakage in the pipeline and the severity of the leakage. If the change rate is large, it indicates that the temperature difference between the leak point and the optical fiber detection position is large, and the heat transfer is relatively intense, which may imply that the leakage is relatively serious; conversely, if the change rate is small, the leakage may be less severe; at the same time, by continuously monitoring this change rate, the dynamic change of the pipeline leakage situation can be understood in real time, so as to take corresponding measures for treatment in a timely manner.

[0091] To further optimize the above embodiments, the process of analyzing the change rate of sound intensity information in consecutive periods includes:

[0092] S31, preset the sound intensity in the normal state and the ideal sound intensity change threshold;

[0093] S32, determine multiple sound intensities S obtained within consecutive preset periods i , and substitute them into the following formula:

[0094]

[0095] where, is the sound intensity change rate, used to reflect the change trend of the sound signal caused by pipeline leakage; n is the number of multiple sound intensities S obtained within consecutive preset periods i of, S 0 is the sound intensity in the normal state, ΔS thre is the ideal sound intensity change threshold;

[0096] S33, output the sound intensity change rate

[0097] It should be noted that the sound intensity in the normal state is determined according to the sound characteristics of the pipeline during normal operation, and the ideal sound intensity change threshold is set according to experience or experimental data to judge whether the change of the sound intensity exceeds the normal range; determine multiple sound intensities obtained within consecutive preset periods and substitute them into the formula for calculation; the purpose of this formula is to calculate the change rate of the sound intensity within consecutive periods to reflect the change trend of the sound signal caused by pipeline leakage; where, n represents the number of multiple sound intensities obtained within consecutive preset periods, used to calculate the average sound intensity; S 0 is the sound intensity in the normal state, used to compare with the average sound intensity; ΔS threis the ideal threshold for the change in sound intensity, used to determine whether the change in sound intensity exceeds an acceptable range; this change rate can be an important indicator for judging whether there is a leak in the pipeline; if the change rate of sound intensity exceeds the set threshold, it may mean that there is a leak problem in the pipeline.

[0098] To further optimize the above embodiments, the comprehensive index model is:

[0099]

[0100] where I is the comprehensive index, used to comprehensively reflect the temperature change rate and the change rate of sound intensity as well as the ambient temperature T v and the relationship with the leak point temperature T l ; ω 1 、ω 2 、ω 3 are weight coefficients, set based on the actual situation.

[0101] It should be noted that the comprehensive index comprehensively reflects the temperature change rate, the change rate of sound intensity, and the relationship between the ambient temperature and the leak point temperature. By considering these factors comprehensively, the internal leakage situation of the pipeline can be evaluated more comprehensively; the weight coefficients are set based on the actual situation. The role of these weight coefficients is to adjust the relative importance of each factor in the comprehensive index. For example, if in a certain actual application scenario, the temperature change rate is more critical for judging the internal leakage situation, then the value of ω 1 can be appropriately increased to improve the weight of the temperature change rate in the comprehensive index. Similarly, according to the actual situation, ω 2 、ω 3 can be adjusted accordingly to ensure that the comprehensive index can accurately reflect the internal leakage situation of the pipeline.

[0102] To further optimize the above embodiments, the process of judging the internal leakage situation of this point based on the comprehensive index includes:

[0103] Preset a standard index threshold and compare it with the calculated comprehensive index I;

[0104] When the comprehensive index I exceeds the standard index threshold, it is determined that there is an internal leakage situation in the area corresponding to the distributed optical fiber sensor, and the internal leakage point is near the pipeline corresponding to the optical fiber position D; and when the comprehensive index I exceeds the standard index threshold, an alarm signal is triggered to notify the personnel to come to handle it;

[0105] When the comprehensive index I does not exceed the standard index threshold, it is determined that there is no internal leakage situation.

[0106] It should be noted that the standard index threshold is determined based on actual experience and the specific conditions of the pipeline. The setting of this threshold requires comprehensive consideration of various factors, such as the pipeline material, operating environment, historical data, etc. By reasonably setting the standard index threshold, the accuracy and reliability of internal leakage judgment can be improved; and the process of judging the internal leakage situation at this point based on comprehensive indicators is a process that comprehensively considers various factors, and reasonable setting and judgment are required according to the actual situation to ensure the safe operation of the pipeline.

[0107] To further optimize the above embodiment, the distributed optical fiber sensor and the distributed acoustic sensor are arranged behind the electric valve of the boiler drain pipeline.

[0108] It should be noted that according to the temperature characteristics, the leakage of the boiler drain valve mainly causes the temperature behind the valve to rise. Setting the temperature measurement optical fiber behind the electric valve can monitor whether there is a leakage point in the valve, and along the water conveyance direction of the pipeline, the water temperature in the distance is higher than that in the vicinity. When the temperature difference between the steam and water in the pipe and the external environment is large, the temperature monitoring effect is good; as the temperature difference decreases, the effect becomes less obvious and the monitoring error becomes larger.

[0109] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for inspecting internal leakage of a boiler drain pipe, characterized in that: include: Step 1: Install distributed optical fiber sensors and distributed acoustic sensors at key locations of boiler drain pipes; Step 2: using a distributed optical fiber sensor to transmit an optical signal at a preset period, and receiving and analyzing the transmitted optical signal to obtain information on the protruding point, including temperature information and location information; Step 3, based on the temperature transfer model and the prominent point information, calculate the temperature change rate of the point in the continuous cycle; Step 4: using distributed acoustic sensors to collect sound intensity information and analyzing the rate of change of the sound intensity information in continuous cycles; Step 5: The temperature change rate and the sound intensity change rate are integrated through a preset comprehensive index model to calculate a comprehensive index; Step six, determine the internal leakage situation of the point based on comprehensive indicators.

2. A boiler drain pipe internal leakage inspection method according to claim 1, characterized in that: The distributed optical fiber sensor and the distributed acoustic sensor include: The distributed optical fiber sensor includes an optical fiber, a light source, a detector and a signal processor; the optical fiber is used to transmit an optical signal, and a reflection point is set at the end; the light source is used to provide an optical signal of a specific wavelength to the optical fiber in each preset period; the detector receives the optical signal reflected by the optical fiber and converts it into an electrical signal; the signal processing unit processes and analyzes the electrical signal to extract the protruding point information; the protruding point information includes temperature information and position information; The distributed acoustic sensor includes an acoustic probe, a signal amplification circuit and a data processing module; the acoustic probe is used to detect the sound signal in the pipeline, the signal amplification circuit is used to amplify the weak sound signal, and the data processing module analyzes and processes the amplified sound signal to extract the sound intensity information.

3. A boiler drain pipe internal leakage inspection method according to claim 2, characterized in that: The process of the signal processing unit processing and analyzing the electrical signal to extract the protruding point information includes: S11, obtaining temperature information; calculating the temperature distribution along the optical fiber based on the relationship between the intensity ratio of Stokes light and anti-Stokes light in Raman scattering and temperature, the formula is: Among them, I as is the anti-Stokes light intensity, I s is the Stokes light intensity, which is obtained based on the analysis of the optical signal; A is the proportionality coefficient, which is set based on experience and actual conditions; h is the Planck constant, v is the Raman frequency shift, and k is the Boltzmann constant, which are all theoretical values; T l It is the temperature information, which is used to reflect the temperature distribution along the optical fiber; The anti-Stokes light intensity I in the optical signal is obtained by the signal processor as and Stokes light intensity I s , and substitute it into the formula to calculate and get the temperature information T l ; Preset the temperature threshold, when the temperature information T l When the value exceeds the temperature threshold, it is determined that the pipeline has abnormal temperature; S12, obtaining position information; when it is determined that the pipeline has an abnormal temperature, the position causing the light signal to be scattered in the optical fiber is determined based on the optical time domain reflectometry technology, that is, the optical fiber point corresponding to the position where the pipeline has an abnormal temperature. The calculation formula is: Among them, D is the position information, which is used to reflect the optical fiber point corresponding to the position of the abnormal temperature extreme point in the pipeline; v is the speed of light signal transmission in the optical fiber, which is a theoretical value; τ is the round-trip time interval of the light signal from the light source to the reflection point; The signal processor obtains the time interval τ of the optical signal and substitutes it into the formula to calculate the position information D; S13, fusing the temperature information and the position information to determine the position where the abnormal temperature exists in the pipeline.

4. A boiler drain pipe internal leakage inspection method according to claim 3, characterized in that: The process of calculating the temperature change rate of the point in a continuous cycle based on the temperature transfer model and the prominent point information includes: S21, obtaining temperature data of the fluid in the pipe and basic environment temperature data through a sensor; S22, establishing the temperature transfer model, the temperature transfer model is: in, is the temperature change rate, representing the temperature change trend in the pipeline, t is the time interval corresponding to the continuous preset cycle; K is the heat transfer coefficient, a and b are undetermined coefficients, which are set based on the actual situation and are used to reflect the characteristics of temperature change with distance; ΔD is the multiple position information D obtained in the continuous preset cycle i The relative distance of -b*ΔD The smaller the relative distance between the abnormal temperature extremes in the continuous cycle, the greater the change trend of the temperature in the pipeline; T l is the temperature information; T u is the temperature data of the fluid in the pipe; S23, substituting the current corresponding data into the temperature transfer model to calculate the temperature change rate 5. A boiler drain pipe internal leakage inspection method according to claim 4, characterized in that: The process of analyzing the change rate of the sound intensity information in a continuous period includes: S31, presetting the sound intensity in a normal state and the ideal sound intensity change threshold; S32, determining a plurality of sound intensities S obtained within a continuous preset period i , substituting it into the following formula: in, is the sound intensity change rate, which is used to reflect the change trend of the sound signal caused by pipeline leakage; n is the multiple sound intensities S obtained in a continuous preset period i The number of, S0 is the sound intensity in normal state, ΔS thre is the ideal threshold of sound intensity change; S33, output sound intensity change rate 6. A boiler drain pipe internal leakage inspection method according to claim 5, characterized in that: The comprehensive indicator model is: Among them, I is a comprehensive index, which is used to comprehensively reflect the temperature change rate. and the rate of change of sound intensity And the ambient temperature T v and leakage point temperature T l ω1, ω2, and ω3 are weight coefficients, which are set based on actual conditions.

7. A boiler drain pipe internal leakage inspection method according to claim 6, characterized in that: The process of judging the internal leakage of the point based on the comprehensive index includes: Pre-set the threshold of the standard indicator and compare it with the calculated comprehensive indicator I; When the comprehensive index I exceeds the standard index threshold, it is determined that the area corresponding to the distributed optical fiber sensor has internal leakage, and the internal leakage point is near the pipeline corresponding to the optical fiber position D; When the comprehensive index I does not exceed the standard index threshold, it is determined that there is no internal leakage.

8. A boiler drain pipe internal leakage inspection method according to claim 7, characterized in that: Also includes: When the comprehensive index I exceeds the standard index threshold, an alarm signal is triggered to notify personnel to come to the scene for processing.

9. A boiler drain pipe internal leakage inspection method according to claim 8, characterized in that: The distributed optical fiber sensor and the distributed acoustic sensor are arranged behind the electric door of the boiler drain pipe.

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