Natural gas leakage detection method and device based on cavity ring-down laser technology

Abstract

The invention discloses a natural gas leakage detection method and device based on an optical cavity ring-down laser technology. The method comprises the following steps: sucking leaked sample gas into an optical ring-down cavity through a sucking pump; high-energy short light pulses emitted by a laser are modulated through a laser modulator, and pulse laser with set wavelength is generated; inputting the pulse laser with the set wavelength into the optical ring-down cavity, so that the pulse laser with the set wavelength is subjected to laser ring-down treatment in the optical ring-down cavity filled with the leaked sample gas; after the laser ring-down treatment, the light ring-down cavity escapes a set light intensity; inputting the set light intensity into a receiver, and obtaining a light intensity proportional signal through the receiver; according to the light intensity proportional signal, calculation is carried out through a set algorithm, and the leakage concentration of the leaked sample gas is obtained; and after leakage concentration detection is completed, the leaked sample gas is discharged into the atmosphere through the sucking pump. The light source intensity fluctuation immunity is improved, and the stability of a detection system is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of gas detection, and in particular to a natural gas leakage detection method and device based on cavity ring-down laser technology. Background Art

[0002] Natural gas pipeline leakage can bring many hazards. When it reaches a certain concentration (5%-15%) in the air, it will cause an explosion when it encounters a fire source. Natural gas leakage will not only cause fires and explosions, but also have a serious impact on the environment and climate. The hazards of natural gas leakage cannot be ignored, and effective leakage detection methods need to be adopted.

[0003] At present, the existing pipeline natural gas leak detection technology generally adopts TDLAS detection technology and ICOS measurement technology. The traditional technology of laser absorption spectroscopy technology is tunable diode laser absorption spectroscopy (TDLAS) detection technology. TDLAS technology uses current and temperature to precisely tune and control the laser, scan one or several absorption lines of the gas molecules to be measured, and invert the concentration of the gas to be measured according to the difference in laser intensity before and after the gas to be measured produces characteristic absorption of the incident light. At present, TDLAS has a path length of 20 meters and 40 meters, which limits its detection sensitivity and accuracy. Another is the integral cavity absorption spectroscopy technology (ICOS), which is a measurement technology based on absorption intensity. In order to determine the absorption path length, ICOS must use time-based attenuation measurement at the end of each spectral absorption scan, which is often limited by laser noise and drift. It uses laser current to modulate the wavelength of the laser, which is itself nonlinear. These nonlinear conditions are directly converted to absorption spectrum measurement and may cause concentration calculation errors. Due to the current detection method or due to the problem of the detection optical path or the influence of laser noise or drift, the accuracy and stability of natural gas leakage measurement will be greatly affected.

[0004] Therefore, how to invent a natural gas leak detection method based on cavity ring-down laser technology to improve immunity to light source intensity fluctuations and increase the stability of the detection system has become an urgent problem to be solved. Summary of the invention

[0005] To this end, the present invention provides a natural gas leak detection method and device based on cavity ring-down laser technology. The cavity ring-down detection technology CRDS is used to be immune to light source intensity fluctuations, thereby increasing the stability of the detection system. The ultra-long optical path can achieve high-precision measurement with an accuracy level of ppb.

[0006] The leaked sample gas is sucked into the optical ring-down cavity through a vacuum pump;

[0007] The high-energy short light pulses emitted by the laser are modulated by a laser modulator to generate pulsed lasers of a set wavelength;

[0008] Inputting the set wavelength pulse laser into the optical ring-down cavity, so that the set wavelength pulse laser performs laser ring-down processing in the optical ring-down cavity filled with the leaked sample gas;

[0009] After the laser ring-down processing, the optical ring-down cavity emits a set light intensity; the set light intensity is input into a receiver, and a light intensity proportional signal is obtained through the receiver;

[0010] According to the light intensity proportional signal, a leakage concentration of the leakage sample gas is obtained by calculating through a set algorithm;

[0011] After the leakage concentration detection is completed, the leakage sample gas is discharged into the atmosphere through the vacuum pump.

[0012] As a preferred solution of a natural gas leak detection method based on cavity ring-down laser technology, in the process of sucking the leakage sample gas into the optical ring-down cavity, the leakage sample gas enters the optical ring-down cavity through a sample gas filter.

[0013] As a preferred solution of a natural gas leak detection method based on optical cavity ring-down laser technology, four high-reflectivity mirrors are provided in the optical ring-down cavity. The four high-reflectivity mirrors are placed at set angles so that the set wavelength pulse laser is continuously reflected in the four mirrors to form oscillation.

[0014] As a preferred solution of a natural gas leak detection method based on cavity ring-down laser technology, in the process of calculating and obtaining the leakage concentration of the leaked gas sample by the set algorithm, the calculation formula of the leakage concentration is:

[0015]

[0016] Where C is the concentration of natural gas leakage; c is the speed of light; α is the absorption coefficient of the gas; τ is the ring-down time of light in the ring-down cavity with gas; τ 0 is the ring-down time of light in the ring-down cavity when there is no gas.

[0017] As a preferred solution of a natural gas leak detection method based on cavity ring-down laser technology, in the process of calculating and obtaining the leakage concentration of the leaked sample gas through the set algorithm, the calculation formula of the ring-down time is:

[0018]

[0019] Where L is the cavity length and R is the reflectivity of the cavity mirror.

[0020] The present invention also provides a natural gas leak detection device based on cavity ring-down laser technology, which adopts the above natural gas leak detection method based on cavity ring-down laser technology, including:

[0021] A leakage sample gas suction module is used to suck the leakage sample gas into the optical ring-down cavity through a vacuum pump;

[0022] The laser modulation processing module is used to modulate the high-energy short light pulses emitted by the laser through a laser modulator to generate a pulsed laser of a set wavelength;

[0023] A laser ring-down processing module, used for inputting the set wavelength pulse laser into the optical ring-down cavity, so that the set wavelength pulse laser performs laser ring-down processing in the optical ring-down cavity filled with the leaked sample gas;

[0024] A receiver processing module, used for setting the light intensity emitted from the optical ring-down cavity after the laser ring-down processing; inputting the set light intensity into a receiver, and obtaining a light intensity proportional signal through the receiver;

[0025] A leakage concentration calculation module, used to calculate the leakage concentration of the leakage sample gas by setting an algorithm according to the light intensity proportional signal;

[0026] The leakage sample gas discharge module is used to discharge the leakage sample gas into the atmosphere through the vacuum pump after completing the leakage concentration detection.

[0027] As a preferred solution of a natural gas leak detection device based on cavity ring-down laser technology, in the leakage sample gas intake module, during the process of sucking the leakage sample gas into the optical ring-down cavity, the leakage sample gas enters the optical ring-down cavity through a sample gas filter.

[0028] As a preferred solution for a natural gas leak detection device based on cavity ring-down laser technology, in the laser ring-down processing module, four high-reflectivity mirrors are provided in the optical ring-down cavity, and the four high-reflectivity mirrors are placed at set angles so that the set wavelength pulse laser is continuously reflected in the four mirrors to form oscillation.

[0029] As a preferred solution of a natural gas leak detection device based on cavity ring-down laser technology, in the leakage concentration calculation module, in the process of calculating and obtaining the leakage concentration of the leaked gas sample by the set algorithm, the calculation formula of the leakage concentration is:

[0030]

[0031] Where C is the concentration of natural gas leakage; c is the speed of light; α is the absorption coefficient of the gas; τ is the ring-down time of light in the ring-down cavity with gas; τ 0 is the ring-down time of light in the ring-down cavity when there is no gas.

[0032] As a preferred solution of a natural gas leak detection device based on cavity ring-down laser technology, in the leakage concentration calculation module, in the process of calculating and obtaining the leakage concentration of the leaked gas sample by the set algorithm, the calculation formula of the ring-down time is:

[0033]

[0034] Where L is the cavity length and R is the reflectivity of the cavity mirror.

[0035] The present invention has the following advantages: the present invention sucks the leaking sample gas into the optical ring-down cavity through the vacuum pump; the high-energy short light pulse emitted by the laser is modulated by the laser modulator to generate a set wavelength pulse laser; the set wavelength pulse laser is input into the optical ring-down cavity, so that the set wavelength pulse laser is subjected to laser ring-down processing in the optical ring-down cavity filled with the leaking sample gas; after the laser ring-down processing, the optical ring-down cavity escapes the set light intensity; the set light intensity is input into the receiver, and the light intensity proportional signal is obtained through the receiver; according to the light intensity proportional signal, the leakage concentration of the leaking sample gas is obtained by calculation through the set algorithm; after completing the leakage concentration detection, the leaking sample gas is discharged into the atmosphere through the vacuum pump. The present invention adopts the optical cavity ring-down spectroscopy technology to make up for the problems of the traditional absorption spectroscopy technology being affected by the light source fluctuation and the low measurement accuracy in the natural gas pipeline leakage detection. In particular, the special structure of the ring-down cavity design is adopted to greatly improve the effective optical path, which has incomparable advantages over the traditional ring-down cavity, and realizes high-precision and high-throughput gas detection through a more reasonable cavity mirror structure and a cavity mirror with higher reflectivity. In the control system, the software algorithm developed by ourselves can continuously measure the two gases methane and ethane, and distinguish the interference caused by natural gas, biogas, and automobile exhaust in real time, so as to distinguish the methane places of biological origin such as sewage wells and landfills, and obtain the accurate gas pipeline leakage point. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0037] The structures, proportions, sizes, etc. illustrated in this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with the technology. They are not used to limit the conditions under which the present invention can be implemented, and therefore have no substantial technical significance. Any structural modification, change in proportion or adjustment of size shall still fall within the scope of the technical contents disclosed in the present invention without affecting the effects and purposes that can be achieved by the present invention.

[0038] Figure 1 This is a flow chart of a natural gas leak detection method based on cavity ring-down laser technology provided in Example 1 of the present invention;

[0039] Figure 2 This is a schematic diagram of a specific implementation process of a natural gas leak detection method based on cavity ring-down laser technology provided in Example 1 of the present invention;

[0040] Figure 3 This is a schematic diagram of the structure of a four-mirror optical ring-down cavity in a natural gas leak detection method based on optical cavity ring-down laser technology provided in Example 1 of the present invention; wherein, 1, a reflector; 2, a detection sample gas inlet; 3, an optical ring-down cavity; 4, a reflector; 5, an optical receiver interface; 6, a reflector; 7, a laser modulator interface; 8, a detection sample gas outlet; 9, a reflector;

[0041] Figure 4 This is a schematic diagram of the architecture of a natural gas leak detection device based on cavity ring-down laser technology provided in Example 2 of the present invention. DETAILED DESCRIPTION

[0042] The following is a description of the implementation of the present invention by specific embodiments. People familiar with the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] Example 1

[0044] See also Figure 1 and Figure 2 Embodiment 1 of the present invention provides a natural gas leak detection method based on cavity ring-down laser technology, comprising the following steps:

[0045] S1, suck the leaked sample gas into the optical ring-down cavity through the vacuum pump;

[0046] S2, modulating the high-energy short light pulses emitted by the laser through a laser modulator to generate a pulsed laser of a set wavelength;

[0047] S3, inputting the set wavelength pulse laser into the optical ring-down cavity, so that the set wavelength pulse laser performs laser ring-down processing in the optical ring-down cavity filled with the leaked sample gas;

[0048] S4, after the laser ring-down processing, the optical ring-down cavity emits a set light intensity; the set light intensity is input into a receiver, and a light intensity proportional signal is obtained through the receiver;

[0049] S5. Calculate the leakage concentration of the leakage sample gas by setting an algorithm according to the light intensity proportional signal;

[0050] S6. After the leakage concentration detection is completed, the leakage sample gas is discharged into the atmosphere through the vacuum pump.

[0051] In this embodiment, in step S1, the leaked sample gas is sucked into the optical ring-down cavity by a vacuum pump;

[0052] Specifically, in the process of sucking the leakage sample gas into the optical ring-down cavity, the leakage sample gas enters the optical ring-down cavity through a sample gas filter.

[0053] In this embodiment, in step S2, the high-energy short light pulse emitted by the laser is modulated by a laser modulator to generate a pulsed laser of a set wavelength;

[0054] Specifically, the laser emits high-energy short light pulses, which pass through a laser modulator to obtain pulsed lasers that meet wavelength requirements and enter an optical ring-down cavity.

[0055] In this embodiment, in step S3, the set wavelength pulse laser is input into the optical ring-down cavity, so that the set wavelength pulse laser performs laser ring-down processing in the optical ring-down cavity filled with the leaked sample gas;

[0056] Specifically, Figure 3 As shown, the optical ring-down cavity is provided with four high-reflectivity mirrors, which are placed at set angles so that the set wavelength pulse laser is continuously reflected in the four mirrors to form oscillation, and its intensity is continuously attenuated through continuous reflection.

[0057] In this embodiment, in step S4, after the laser ring-down process, the optical ring-down cavity emits a set light intensity; the set light intensity is input into a receiver, and a light intensity proportional signal is obtained through the receiver;

[0058] Specifically, the receiver detection is used to detect a small amount of light intensity escaping from one of the reflectors, generate a signal proportional to the light intensity in the cavity, and record the attenuation process of the laser pulse in the cavity. When the reflectivity of the cavity mirror is known, the change in gas concentration in the cavity can be calculated.

[0059] In this embodiment, in step S5, the leakage concentration of the leakage sample gas is obtained by calculating according to the light intensity proportional signal through a set algorithm;

[0060] Specifically, the calculation formula for leakage concentration is:

[0061]

[0062] Where C is the concentration of natural gas leakage; c is the speed of light; α is the absorption coefficient of the gas; τ is the ring-down time of light in the ring-down cavity with gas; τ 0 is the ring-down time of light in the ring-down cavity when there is no gas.

[0063] From the above formula, we can know that the concentration of the measured natural gas is only related to the ring-down time with or without medium and the absorption coefficient of the medium. The absorption coefficient of the substance at a specific wavelength can be accurately measured by conventional absorption methods and can be found in the literature. Therefore, the concentration of the substance can be determined by measuring the difference between the reciprocal of the ring-down time with or without medium (i.e., the decay rate).

[0064] The calculation formula of ring-down time is:

[0065]

[0066] Where L is the cavity length and R is the reflectivity of the cavity mirror.

[0067] It can be seen that the accuracy of natural gas leakage concentration measurement is related to the measurement of ring-down time and the chamber design and cavity mirror design of the ring-down cavity.

[0068] In this embodiment, Figure 2 As shown, the control system consists of an optical path control board, a computer and application software. The optical path control board is used to control the operation of the laser, laser modulator and receiver, and detect and record parameters such as the transmitted light intensity of the optical path system. The computer system receives data signals from the optical path control board, and measures the reflectivity of the cavity mirror by measuring the projected light intensity, and then measures the equivalent optical path of the system and calculates the cavity ring-down time. The specific algorithm uses Fourier transform method and trapezoidal integration method for calculation, and then fits the calculated data to obtain the most accurate data:

[0069] The Fourier transform has the following expression for analyzing ring-down variation data:

[0070] f(n)=e -βnΔt

[0071]

[0072] In the formula, β is the attenuation constant; n is the integer of sampling points; Δt is the interval time between data sampling points;

[0073] f(n) = e -βnΔt After Fourier transform, we can derive:

[0074]

[0075] ωk=2πk / NΔt

[0076] Where K is an arbitrary integer (0 to N-1) for sampling; N is the number of sampling points.

[0077] The trapezoidal integration method is to remove the offset from the ring-down signal and take the logarithm:

[0078]

[0079] t i =iΔt

[0080] Where A is the amplitude;

[0081] After calculation and deduction, we get:

[0082]

[0083] In the formula, a 1 is the coefficient,

[0084] The coefficients are identified as

[0085] The accurate decay time τ is obtained by calculating and fitting the two decay constants 0 and τ values, and then the detected gas concentration is obtained.

[0086] In this embodiment, in step S6, after the leakage concentration detection is completed, the leakage sample gas is discharged into the atmosphere through the air pump.

[0087] In this embodiment, generally speaking, natural gas contains a certain proportion of ethane (about 1-3%), while methane of biological origin in sewage wells, landfills, etc. does not contain ethane. The present invention can continuously measure both methane and ethane gases, and can accurately and real-time distinguish the interference caused by fuel gas, biogas, and automobile exhaust. Through self-developed algorithms, the false detection rate and detection efficiency are effectively improved.

[0088] In summary, the present invention sucks the leaking sample gas into the optical ring-down cavity through an air pump; modulates the high-energy short light pulses emitted by the laser through a laser modulator to generate a set wavelength pulse laser; inputs the set wavelength pulse laser into the optical ring-down cavity, so that the set wavelength pulse laser performs laser ring-down processing in the optical ring-down cavity filled with the leaking sample gas; after the laser ring-down processing, the optical ring-down cavity escapes a set light intensity; inputs the set light intensity into a receiver, and obtains a light intensity proportional signal through the receiver; calculates according to the light intensity proportional signal through a set algorithm to obtain the leakage concentration of the leaking sample gas; after completing the leakage concentration detection, the leaking sample gas is discharged into the atmosphere through the air pump. The present invention uses optical cavity ring-down spectroscopy technology to make up for the problems of traditional absorption spectroscopy technology being affected by light source fluctuations and low measurement accuracy in natural gas pipeline leakage detection. In particular, the special structure of the ring-down cavity design greatly improves the effective optical path, which has incomparable advantages over the traditional ring-down cavity. Through a more reasonable cavity mirror structure and a cavity mirror with higher reflectivity, high-precision and high-throughput gas detection is achieved. In the control system, the software algorithm developed by ourselves can continuously measure the two gases methane and ethane, and distinguish the interference caused by natural gas, biogas, and automobile exhaust in real time, so as to distinguish the methane places of biological origin such as sewage wells and landfills, and obtain the accurate gas pipeline leakage point.

[0089] It should be noted that the method of the embodiment of the present disclosure can be performed by a single device, such as a computer or a server. The method of the present embodiment can also be applied in a distributed scenario and completed by multiple devices cooperating with each other. In the case of such a distributed scenario, one of the multiple devices can only perform one or more steps in the method of the embodiment of the present disclosure, and the multiple devices will interact with each other to complete the described method.

[0090] It should be noted that the above describes some embodiments of the present disclosure. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in an order different from that in the above embodiments and still achieve the desired results. In addition, the processes depicted in the accompanying drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0091] Example 2

[0092] See also Figure 4 Embodiment 2 of the present invention further provides a natural gas leak detection device based on cavity ring-down laser technology, comprising:

[0093] The leakage sample gas suction module 001 is used to suck the leakage sample gas into the optical ring-down cavity through a vacuum pump;

[0094] The laser modulation processing module 002 is used to modulate the high-energy short light pulses emitted by the laser through a laser modulator to generate a pulsed laser of a set wavelength;

[0095] The laser ring-down processing module 003 is used to input the set wavelength pulse laser into the optical ring-down cavity, so that the set wavelength pulse laser performs laser ring-down processing in the optical ring-down cavity filled with the leakage sample gas;

[0096] A receiver processing module 004 is used for setting the light intensity emitted from the optical ring-down cavity after the laser ring-down processing; inputting the set light intensity into a receiver, and obtaining a light intensity proportional signal through the receiver;

[0097] The leakage concentration calculation module 005 is used to calculate the leakage concentration of the leakage sample gas according to the light intensity proportional signal by setting an algorithm;

[0098] The leakage sample gas discharge module 006 is used to discharge the leakage sample gas into the atmosphere through the vacuum pump after completing the leakage concentration detection.

[0099] In this embodiment, in the leakage sample gas inhalation module 001, during the process of inhaling the leakage sample gas into the optical ring-down cavity, the leakage sample gas enters the optical ring-down cavity through the sample gas filter.

[0100] In this embodiment, in the laser ring-down processing module 003, four high-reflectivity mirrors are provided in the optical ring-down cavity, and the four high-reflectivity mirrors are placed at set angles so that the set wavelength pulse laser is continuously reflected in the four mirrors to form oscillation.

[0101] In this embodiment, in the leakage concentration calculation module 005, in the process of calculating and obtaining the leakage concentration of the leakage sample gas through the set algorithm, the calculation formula of the leakage concentration is:

[0102]

[0103] Where C is the concentration of natural gas leakage; c is the speed of light; α is the absorption coefficient of the gas; τ is the ring-down time of light in the ring-down cavity with gas; τ 0 is the ring-down time of light in the ring-down cavity when there is no gas.

[0104] In this embodiment, in the leakage concentration calculation module 005, in the process of calculating and obtaining the leakage concentration of the leakage sample gas by the set algorithm, the calculation formula of the ring-down time is:

[0105]

[0106] Where L is the cavity length and R is the reflectivity of the cavity mirror.

[0107] It should be noted that the information interaction, execution process and other contents between the modules of the above-mentioned system are based on the same concept as the method embodiment in Example 1 of the present application, and the technical effects they bring are the same as those of the method embodiment of the present application. For specific contents, please refer to the description in the method embodiment shown above in the present application, and will not be repeated here.

[0108] Example 3

[0109] Embodiment 3 of the present invention provides a non-transitory computer-readable storage medium, in which a program code for a natural gas leak detection method based on cavity ring-down laser technology is stored. The program code includes instructions for executing embodiment 1 or any possible implementation method of a natural gas leak detection method based on cavity ring-down laser technology.

[0110] The computer-readable storage medium may be any available medium that can be accessed by a computer or a data storage device such as a server or a data center that includes one or more available media. The available medium may be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid-state drive (SSD)).

[0111] Example 4

[0112] Embodiment 4 of the present invention provides an electronic device, including: a memory and a processor;

[0113] The processor and the memory communicate with each other via a bus; the memory stores program instructions that can be executed by the processor, and the processor calls the program instructions to execute a natural gas leak detection method based on cavity ring-down laser technology in Example 1 or any possible implementation thereof.

[0114] Specifically, the processor can be implemented by hardware or by software. When implemented by hardware, the processor can be a logic circuit, an integrated circuit, etc.; when implemented by software, the processor can be a general-purpose processor implemented by reading software codes stored in a memory. The memory can be integrated in the processor or can be located outside the processor and exist independently.

[0115] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present invention is generated in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable systems. The computer instructions can be stored in a computer-readable storage medium, or transmitted from a computer-readable storage medium to another computer-readable storage medium, for example, the computer instructions can be transmitted from a website site, computer, server or data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) mode to another website site, computer, server or data center.

[0116] Obviously, those skilled in the art should understand that the above modules or steps of the present invention can be implemented by a general computing system, they can be concentrated on a single computing system, or distributed on a network composed of multiple computing systems, and optionally, they can be implemented by a program code executable by a computing system, so that they can be stored in a storage system and executed by the computing system, and in some cases, the steps shown or described can be executed in a different order than here, or they can be made into individual integrated circuit modules, or multiple modules or steps therein can be made into a single integrated circuit module for implementation. Thus, the present invention is not limited to any specific combination of hardware and software.

[0117] Although the present invention has been described in detail above by general description and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements can be made to the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all belong to the scope of protection claimed by the present invention.

Claims

1. A natural gas leak detection method based on cavity ring-down laser technology, characterized in that: include: The leaked sample gas is sucked into the optical ring-down cavity through a vacuum pump; The high-energy short light pulses emitted by the laser are modulated by a laser modulator to generate pulsed lasers of a set wavelength; Inputting the set wavelength pulse laser into the optical ring-down cavity, so that the set wavelength pulse laser performs laser ring-down processing in the optical ring-down cavity filled with the leaked sample gas; After the laser ring-down processing, the optical ring-down cavity emits a set light intensity; the set light intensity is input into a receiver, and a light intensity proportional signal is obtained through the receiver; According to the light intensity proportional signal, a leakage concentration of the leakage sample gas is obtained by calculating through a set algorithm; After the leakage concentration detection is completed, the leakage sample gas is discharged into the atmosphere through the vacuum pump.

2. The natural gas leak detection method based on cavity ring-down laser technology according to claim 1 is characterized in that: In the process of sucking the leakage sample gas into the optical ring-down cavity, the leakage sample gas enters the optical ring-down cavity through the sample gas filter.

3. The natural gas leak detection method based on cavity ring-down laser technology according to claim 2 is characterized in that: The optical ring-down cavity is provided with four high-reflectivity mirrors, which are placed at set angles so that the set wavelength pulse laser is continuously cyclically reflected in the four mirrors to form oscillation.

4. The natural gas leak detection method based on cavity ring-down laser technology according to claim 3 is characterized in that: In the process of calculating and obtaining the leakage concentration of the leakage sample gas by using the set algorithm, the calculation formula of the leakage concentration is: Where C is the natural gas leakage concentration; c is the speed of light; α is the absorption coefficient of the gas; τ is the ring-down time of light in the ring-down cavity with gas; τ0 is the ring-down time of light in the ring-down cavity without gas.

5. The natural gas leak detection method based on cavity ring-down laser technology according to claim 4 is characterized in that: In the process of calculating and obtaining the leakage concentration of the leakage sample gas by using the set algorithm, the calculation formula of the ring-down time is: Where L is the cavity length and R is the reflectivity of the cavity mirror.

6. A natural gas leak detection device based on cavity ring-down laser technology, using a natural gas leak detection method based on cavity ring-down laser technology as claimed in any one of claims 1 to 5, characterized in that: include: A leakage sample gas suction module is used to suck the leakage sample gas into the optical ring-down cavity through a vacuum pump; The laser modulation processing module is used to modulate the high-energy short light pulses emitted by the laser through a laser modulator to generate a pulsed laser of a set wavelength; A laser ring-down processing module, used for inputting the set wavelength pulse laser into the optical ring-down cavity, so that the set wavelength pulse laser performs laser ring-down processing in the optical ring-down cavity filled with the leaked sample gas; A receiver processing module, used for setting the light intensity emitted from the optical ring-down cavity after the laser ring-down processing; inputting the set light intensity into a receiver, and obtaining a light intensity proportional signal through the receiver; A leakage concentration calculation module, used to calculate the leakage concentration of the leakage sample gas by setting an algorithm according to the light intensity proportional signal; The leakage sample gas discharge module is used to discharge the leakage sample gas into the atmosphere through the vacuum pump after completing the leakage concentration detection.

7. A natural gas leak detection device based on cavity ring-down laser technology according to claim 6, characterized in that: In the leakage sample gas inhalation module, during the process of inhaling the leakage sample gas into the optical ring-down cavity, the leakage sample gas enters the optical ring-down cavity through the sample gas filter.

8. The natural gas leak detection device based on cavity ring-down laser technology according to claim 7 is characterized in that: In the laser ring-down processing module, four high-reflectivity mirrors are arranged in the optical ring-down cavity, and the four high-reflectivity mirrors are placed at set angles so that the set wavelength pulse laser is continuously reflected in the four mirrors to form oscillation.

9. The natural gas leak detection device based on cavity ring-down laser technology according to claim 8, characterized in that: In the leakage concentration calculation module, in the process of calculating and obtaining the leakage concentration of the leakage sample gas through the set algorithm, the calculation formula of the leakage concentration is: Where C is the natural gas leakage concentration; c is the speed of light; α is the absorption coefficient of the gas; τ is the ring-down time of light in the ring-down cavity with gas; τ0 is the ring-down time of light in the ring-down cavity without gas.

10. A natural gas leak detection device based on cavity ring-down laser technology according to claim 9, characterized in that: In the leakage concentration calculation module, in the process of calculating and obtaining the leakage concentration of the leakage sample gas through the set algorithm, the calculation formula of the ring-down time is: Where L is the cavity length and R is the reflectivity of the cavity mirror.

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