Light intensity self-correcting laser gas telemetering method in working face dust fog environment

Abstract

The invention discloses a light intensity self-correcting laser gas telemetering method in a working face dust fog environment, which relates to the technical field of laser gas telemetering and comprises the following steps: emitting laser matched with a methane absorption spectral line, receiving echoes after the laser is reflected by a target object, and calculating a light intensity change value; environment dust concentration and humidity are detected; establishing an improved light intensity model of the light intensity interference variable, the dust concentration and the humidity; and correcting a light intensity signal by using the improved light intensity model according to the detected dust concentration and humidity, and calculating the gas concentration. On the basis of a traditional laser gas sensor, the dust concentration measurement module and the humidity measurement module are integrated, and a light intensity model is corrected by introducing dust concentration and humidity parameters, so that the calculation result of the gas concentration is corrected. According to the method, the influence of the severe dust fog environment under the coal mine on the laser gas measurement precision can be solved to a certain extent, and the measurement precision is greatly improved compared with that of a traditional method.

Description

Technical Field

[0001] This invention relates to the field of laser gas telemetry technology, and more specifically, to a laser gas telemetry method with self-calibrated light intensity in a dusty and foggy working environment. Background Technology

[0002] Coal mine safety is the core guarantee for the sustainable development of the coal industry, and gas monitoring in underground fully mechanized mining faces is a key link in preventing major accidents such as gas explosions. With the increase in mining depth and mechanization, the average daily coal output of fully mechanized mining faces has exceeded 5,000 tons, while the dust concentration generated can reach 4,000-8,000 mg / m³. 3 In addition, the relatively high humidity underground creates a typical environment with strong dust and fog interference, which poses a severe challenge to the accurate application of laser gas telemetry technology.

[0003] Existing laser gas telemetry technology is mainly based on the principle of tunable semiconductor laser absorption spectroscopy. It realizes concentration inversion by detecting the characteristic absorption spectral lines of methane. Although this technology has advantages such as high accuracy and strong resistance to electromagnetic interference, its stability and reliability are significantly affected in strong dust and fog environments.

[0004] Achieving multi-parameter dynamic correction of laser light intensity signals in environments with heavy dust and fog is a key technological bottleneck for improving the accuracy of methane concentration monitoring. According to the principle of laser methane telemetry, if there is a large amount of dust and water mist in the path of the emitted laser, some of the laser light will experience energy attenuation due to reflection and refraction, and may even fail to return to the laser module and be received by the photodetector. This phenomenon leads to a greater degree of attenuation in the received light intensity signal, causing inaccurate methane concentration measurements. Therefore, addressing the interference of dust and fog on laser light intensity signals in environments with heavy dust and fog is a problem that needs to be solved.

[0005] To address this, we propose a self-calibrating laser gas telemetry method with light intensity in dusty and foggy working environments. Summary of the Invention

[0006] To overcome the aforementioned deficiencies of the prior art, embodiments of the present invention provide a self-calibrating laser gas telemetry method for working face gas monitoring in dusty and foggy environments. This method utilizes laser gas telemetry technology for working face gas monitoring. Addressing the interference of dust and fog on the laser light intensity signal, dust and humidity sensors are used to detect corresponding environmental parameters and correct the light intensity signal, thereby improving the accuracy of gas concentration data.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A self-calibrated laser gas telemetry method with light intensity adjustment in a dusty and foggy working environment includes the following steps: A laser matching the absorption spectrum of methane is emitted, and the echo is received after being reflected by the target object. The change in light intensity is then calculated. Detect environmental dust concentration and humidity; An improved light intensity model was established to address the interference of light intensity with respect to dust concentration and humidity. Based on the detected dust concentration and humidity, the light intensity signal is corrected using the improved light intensity model to calculate the gas concentration.

[0008] Preferably, the step of establishing the correlation model of light intensity interference includes: An initial light intensity model was established based on Beer-Lambert's law. Dust concentration and humidity were introduced as interference variables to construct an improved light intensity model. Through light intensity tests under different dust concentrations and humidity, the relationship function between the background interference of the optical path and the dust concentration and humidity was obtained by fitting.

[0009] Preferably, the step of detecting dust concentration uses a laser scattering dust sensor to convert the scattered light signal into dust mass concentration.

[0010] Preferably, the step of detecting humidity uses a capacitive humidity sensor, which measures the ambient humidity by measuring the change in capacitance caused by the change in the dielectric constant of the moisture-sensing material.

[0011] Preferably, the dust concentration measurement can be performed using any one of a laser scattering dust sensor, a light scattering sensor, or an infrared dust sensor, and the humidity measurement can be performed using any one of a capacitive humidity sensor, a resistive humidity sensor, or an optical humidity sensor.

[0012] The technical effects and advantages of the self-calibrated laser gas telemetry method for working face dust and fog environments of the present invention are as follows: This invention integrates a dust concentration measurement module and a humidity measurement module into a traditional laser gas sensor. By introducing dust concentration and humidity parameters, the light intensity model is corrected, thereby correcting the calculated gas concentration. This method can significantly improve the accuracy of laser gas measurement compared to traditional methods, reducing the impact of the harsh dust and fog environment in underground coal mines on the accuracy of laser gas measurement.

[0013] Because this invention integrates dust and humidity measurement modules, the design can take into account the measurement of three environmental parameters: gas, dust, and humidity, thus making the downhole detection equipment more integrated. Attached Figure Description

[0014] Figure 1 This is a schematic diagram illustrating the principle framework of a self-calibrating laser gas telemetry method for working face dust and fog environments according to the present invention. Detailed Implementation

[0015] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] This invention utilizes laser gas telemetry technology for working face gas monitoring. To address the interference of dust and fog on the laser light intensity signal, dust and humidity sensors are used to detect corresponding environmental parameters and correct the light intensity signal, thereby improving the accuracy of gas concentration data.

[0017] Reference Figure 1 To address the aforementioned issues, this invention introduces dust concentration and humidity measurement modules into the traditional laser gas measurement module, constructing a model based on the correlation between laser light intensity attenuation and dust / fog concentration. The aim is to correct the received light intensity model through dust / fog concentration measurement, establish an improved light intensity model, and achieve correction of gas measurement results in dusty / foggy environments.

[0018] A self-calibrated laser gas telemetry method with light intensity in dusty and foggy working environments; This invention relates to the measurement of gas concentration, dust concentration, and humidity.

[0019] Specifically: ①Gas concentration measurement: This invention measures methane concentration using laser-based remote methane telemetry. The implementation includes a methane concentration measurement module that employs a tunable semiconductor laser to emit near-infrared laser light with a wavelength precisely matched to the absorption spectrum of methane molecules. When the laser beam passes through methane-containing gas, the methane molecules absorb light energy at a specific wavelength, causing the laser intensity to attenuate. The degree of attenuation is exponentially related to the methane concentration. The laser echo reflected from a target object (such as a coal wall or a wall) is used to receive the reflected light signal through a photodetector, and the change in light intensity is calculated. A built-in algorithm, combined with Beer-Lambert's law, converts the light intensity attenuation into a path integral concentration, enabling the measurement of methane concentration along the laser measurement path.

[0020] ② Dust concentration measurement: Dust concentration measurement is based on a laser scattering dust sensor. This invention incorporates a dust concentration measurement module that uses a laser light source (such as an infrared or visible light source) to emit a parallel beam, forming a stable light field. When dust-laden gas flows through this light field, dust particles interact with the incident light, resulting in scattering. The scattering direction is related to the wavelength of the light, particle size, and shape. A photodetector (such as a photodiode or phototransistor) captures the scattered light signal at a specific angle (typically 90° or a forward angle). Using a pre-calibrated scattering model (such as Mie theory), the signal intensity is converted into a dust mass concentration value. This ultimately enables real-time measurement of airborne dust concentration in the downhole environment.

[0021] ③ Humidity measurement: Humidity measurement is based on a capacitive humidity sensor. In this invention, a humidity measurement module is provided. The change in the capacitance value of the capacitor caused by the change in the dielectric constant of the moisture-sensing material indirectly measures the ambient humidity.

[0022] Example 1 I. Laser Gas Detection Principle and Intensity Model First, establish a light intensity model; According to Beer-Lambert's law, when a beam of parallel light with intensity I0(λ) passes through a gas chamber containing the gas to be measured, if the spectrum of the light source covers one or more absorption lines of the gas, then the relationship between the transmitted light intensity I(λ), the incident light intensity I0(λ), and the gas concentration C is as follows: (1) (1) In the formula: α(λ) represents the absorption coefficient of the medium; L represents the length of the light-absorbing gas; P represents the total pressure of the gas medium; S(T) represents the line intensity of the characteristic spectral line of the gas, which represents the absorption intensity of the spectral line and is only related to the temperature; Φ(λ) represents the line shape function, which represents the shape of the measured absorption spectral line and is related to the temperature, total pressure and the content of each component in the gas.

[0023] After performing a logarithmic operation on both sides of equation (1) and integrating over the entire frequency domain, we obtain: (2) Therefore, the gas concentration can be directly calculated using the following formula: (3) Given parameters such as pressure, absorption line intensity, and effective length of the light-absorbing gas, the gas concentration value can be obtained by substituting the integral value of -ln(I⁄I0) in the frequency domain into equation (3). Typically, the spectral absorbance signal is not directly integrated; instead, a corresponding linear function is used for fitting, and the integral value is accurately obtained from the linear fitting result, reducing the influence of measurement errors during direct integration. In practical sensor design, it is generally assumed that the gas pressure and absorption line are constants, and the concentration of the gas to be measured can be determined simply by measuring the change in light intensity before and after absorption. A light intensity model is then established. To improve the accuracy and reliability of the model measurement, temperature and pressure compensation are required.

[0024] II. Conduct correlation analysis between light intensity signal and dust distribution. To achieve accurate laser gas detection in the context of strong dust and fog in underground mines, the influence of dust distribution on laser light intensity was further studied. An improved light intensity model with dust concentration and particle size as independent variables was established, thus providing support for studying the correlation characteristics between light intensity signal and dust distribution.

[0025] Considering the impact of dust and fog interference on light intensity signals, an improved light intensity model is proposed: (4) In the formula, β(y, r) is the relationship function between the background interference of the optical path and the dust concentration y and humidity r. To further simplify the model, the typical dust particle size distribution characteristics of the working face were investigated, and the influence of particle size was ignored under specific particle size conditions. For specific absorption spectra and concentrations of methane, light intensity signal tests were conducted under different dust concentrations and humidity levels, resulting in an improved light intensity model for the interference β as a function of dust concentration y and humidity r.

[0026] III. Laser Gas Telemetry Based on Integrated Module with Self-calibrated Intensity Based on the above analysis, the gas concentration measurement module, dust concentration measurement module, and humidity measurement module used for measuring gas concentration, dust concentration, and humidity are integrated into one unit. While measuring gas concentration, the dust concentration measurement module and humidity measurement module are used to test the ambient humidity and dust concentration. The parameters are substituted into the improved light intensity model with interference β, which is to obtain the improved light intensity signal model (Equation (4)), thereby correcting the gas concentration calculation model of Equation (3). Substituting the transmitted light intensity I(λ) into the corrected Equation (3) yields the corrected concentration C measurement value.

[0027] Example 2 When selecting dust concentration measurement modules, in addition to laser scattering dust sensors, light scattering sensors, infrared dust sensors, etc. can also be selected to flexibly meet the needs of real-time measurement, continuous online monitoring, high temperature and high humidity environments, and low-cost networking.

[0028] When selecting humidity measurement modules, in addition to capacitive humidity sensors, resistive humidity sensors, thermal conductivity humidity sensors, optical humidity sensors, etc. can also be selected. Different selections can meet the requirements of sensitivity, high temperature resistance, low cost, etc.

[0029] Regardless of the module chosen, the key point of this invention is to use an integrated module to measure parameters such as dust concentration and humidity in order to correct the gas concentration measurement results.

[0030] This invention integrates gas, dust, and humidity measurement modules to construct a correlation model between light intensity interference and dust concentration, achieving high-precision correction of gas concentration in strong dust and fog environments. This reduces measurement errors and response time compared to traditional methods, minimizes installation space for integrated design, and adapts to complex underground environments. Dust measurement covers small particle sizes and a certain range of humidity, improving detection performance. It provides real-time data support for coal mine safety monitoring through multi-parameter fusion, promoting the upgrading of underground monitoring.

[0031] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0032] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for self-calibrating laser gas telemetry in dusty and foggy working environments, characterized in that, The steps include: A laser matching the absorption spectrum of methane is emitted, and the echo is received after being reflected by the target object. The change in light intensity is then calculated. Detect environmental dust concentration and humidity; An improved light intensity model was established to address the interference of light intensity with respect to dust concentration and humidity. Based on the detected dust concentration and humidity, the light intensity signal is corrected using the improved light intensity model to calculate the gas concentration.

2. The method for self-calibrating laser gas telemetry in a dusty and foggy working environment according to claim 1, characterized in that, The steps for establishing the correlation model of light intensity interference include: An initial light intensity model was established based on Beer-Lambert's law. Dust concentration and humidity were introduced as interference variables to construct an improved light intensity model. Through light intensity tests under different dust concentrations and humidity, the relationship function between the background interference of the optical path and the dust concentration and humidity was obtained by fitting.

3. The method for self-calibrating laser gas telemetry in a dusty and foggy working environment according to claim 1, characterized in that, The step of detecting dust concentration uses a laser scattering dust sensor to convert the scattered light signal into dust mass concentration.

4. The method for self-calibrating laser gas telemetry in a dusty and foggy working environment according to claim 1, characterized in that, The humidity detection step uses a capacitive humidity sensor, which measures the ambient humidity by changing the capacitance value caused by the change in the dielectric constant of the moisture-sensing material.

5. The method for self-calibrating laser gas telemetry in a dusty and foggy working environment according to claim 1, characterized in that, The dust concentration measurement can be performed using any one of a laser scattering dust sensor, a light scattering sensor, or an infrared dust sensor, and the humidity measurement can be performed using any one of a capacitive humidity sensor, a resistive humidity sensor, or an optical humidity sensor.

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