Space gas concentration distribution measuring method based on laser telemetering technology

Abstract

The invention relates to a space gas concentration distribution measuring method based on a laser telemetry technology, and belongs to the technical field of coal mine safety. Accumulated gas quantities Q1-Qn, distances R1-Rn and included angles theta 1-theta n of a plurality of light paths are obtained through a methane remote measuring instrument, a laser range finder and a goniometer, average gas concentrations X2-Xn of annular areas between adjacent light paths are solved layer by layer by using a recursion formula with a calibrated light path as a reference, and space gas concentration dot matrix distribution is generated. The detection distance Ri = R1 / cos thetai is dynamically corrected through the light path included angle thetai, the problems that in the prior art, areas (such as a roof and a caving area) difficult to approach by personnel cannot be measured, and the spatial resolution is low are solved, non-contact and high-precision gas concentration three-dimensional distribution modeling is achieved, and reliable data support is provided for coal mine safety monitoring and emergency rescue.

Description

Technical Field

[0001] The invention belongs to the technical field of coal mine safety and relates to a method for measuring spatial gas concentration distribution based on laser telemetry technology. Background Art

[0002] Accurate detection of gas concentration in coal mines is the core link to prevent gas explosions and ensure safe production. Traditional gas detection mainly relies on manual sampling, that is, gas inspectors carry portable detectors into the mine to collect and analyze gas at close range at specific locations. However, this method has significant defects:

[0003] Traditional detection methods cannot be used to detect areas that are inaccessible to personnel or are at risk of collapse, such as the roof of a large mining face, caving areas, and closed goaf areas, causing these areas to become potential risk points for gas accumulation.

[0004] Manual sampling is inefficient and it is difficult to capture the dynamic changes in gas concentration in a timely manner, especially in emergency situations where real-time warnings cannot be provided.

[0005] Tile inspectors need to work deep into dangerous areas and face potential safety threats such as explosions and landslides.

[0006] To overcome the above problems, existing technologies have introduced gas telemeters, which use laser absorption spectroscopy to detect gas concentration over long distances. However, this technology still has the following limitations:

[0007] The telemeter can only measure the average gas concentration (in %·m) along the laser path, and cannot distinguish the concentration differences in different sections of the optical path. For example, when the optical path passes through multiple gas accumulation points, the telemeter cannot locate the specific location of the high-concentration area.

[0008] Existing telemeters lack the fusion analysis of spatial multi-dimensional data and can only provide linear concentration information of a single path. It is difficult to restore the three-dimensional distribution of gas concentration in tunnels or confined spaces, resulting in a lack of accurate data support for emergency rescue.

[0009] Therefore, how to achieve high-resolution, multi-point gas concentration detection in dangerous areas and build a spatial distribution model without relying on human intervention has become a technical problem that needs to be solved in the field of coal mine safety. The present invention proposes a breakthrough solution based on multi-path laser telemetry and recursive calculation. Summary of the invention

[0010] In view of this, an object of the present invention is to provide a method for measuring spatial gas concentration distribution based on laser telemetry technology.

[0011] In order to achieve the above object, the present invention provides the following technical solutions:

[0012] Method for measuring spatial gas concentration distribution based on laser telemetry technology, the method comprising the following steps:

[0013] S1: Calibrate an initial optical path as a calibration optical path (generally select an optical path perpendicular to the roadway wall or roof), measure the distance R1 and the cumulative gas volume Q1 of the calibration optical path, and calculate the average gas concentration X1 of the area corresponding to the calibration optical path;

[0014] S2: Measure the cumulative gas volumes Q2 to Q n corresponding to multiple optical paths in sequence, the corresponding distances R2 to R n and the angles θ2 to θ n with the calibration optical path;

[0015] S3: Calculate the average gas concentrations X2 to X n of the annular regions between adjacent optical paths by a recursive method according to the cumulative gas volume, distance and angle of each optical path;

[0016] S4: Generate dot matrix distribution data of the spatial gas concentration based on the average gas concentrations of all the annular regions.

[0017] Furthermore, the method for calculating X1 in S1 is:

[0018] X1 = Q1 / R1

[0019] wherein, X1 is the gas concentration of the area corresponding to the calibration optical path, Q1 is the cumulative gas volume of the calibration optical path, and R1 is the distance of the calibration optical path.

[0020] Furthermore, in S2, if the distance R i , i = 2 to n, cannot be directly measured, then it is calculated by the formula:

[0021] R i = R1 / cosθ i

[0022] where θ i is the angle between the i-th optical path and the calibration optical path.

[0023] Furthermore, in S3, the formula for calculating the average gas concentration X k of the annular region corresponding to the k-th optical path, k = 2 to n, is:

[0024]

[0025] wherein, R0 = 0, Q k is the cumulative gas volume of the k-th optical path, and R k is the distance of the k-th optical path.

[0026] Further, the annular region between adjacent optical paths is a concentric ring centered at the laser emission point and defined by an inner radius R k-1 and an outer radius R k .

[0027] Further, in S4, the generation method of the dot matrix distribution is as follows: the average gas concentration of each annular region is used as the gas concentration value of all points within that region

[0028] Further, the included angle θ i between the optical paths is measured by a goniometer, the distance R i is measured by a laser rangefinder, and the cumulative gas volume Q i is measured by a methane telemeter

[0029] Further, the number n of the optical paths is n ≥ 3, and the optical paths are radially distributed in space

[0030] Further, the method further includes: drawing a three-dimensional gas concentration distribution map based on the dot matrix distribution data and marking the regions where the concentration exceeds the limit

[0031] Further, the termination condition for the calculation by the recurrence method is: the optical path distance R n reaches the preset maximum detection radius, or the concentration difference between adjacent optical paths is less than the set threshold

[0032] The beneficial effects of the present invention are as follows

[0033] The beneficial effects of the present invention

[0034] (1) Based on laser telemetry technology, it is possible to complete long-distance non-contact detection without personnel entering dangerous areas (such as the roof, caving area), completely eliminating the safety risks and spatial limitations of traditional manual sampling

[0035] (2) By calculating the gas concentration in the annular region between adjacent optical paths layer by layer through a recurrence formula, the average concentration of a single path is decomposed into dot matrix concentrations within concentric rings, and the spatial resolution is dynamically controlled by the optical path density. The denser the optical paths, the closer the dot matrix distribution is to the true concentration field, solving the defect that the telemeter cannot locate small-scale gas accumulation

[0036] (3) Combining a laser rangefinder and a goniometer, the actual detection distance of the inclined optical path is automatically calculated, avoiding measurement errors caused by irregularities in the roadway wall, and is especially suitable for non-uniform spaces such as undulating roofs and collapsed areas

[0037] (4) Through spatial interpolation of multi-optical path data, a three-dimensional gas concentration distribution map can be generated, intuitively marking the regions where the concentration exceeds the limit, providing accurate data support for gas extraction, ventilation optimization, and emergency rescue

[0038] (5) Integrate the methane telemeter, laser rangefinder and goniometer to achieve full-process automation of data acquisition - calculation - modeling, significantly improve the detection efficiency, and meet the requirements of underground real-time monitoring.

[0039] (6) The recursive calculation extrapolates step by step based on the calibrated optical path. Through the error layer-by-layer convergence mechanism, it ensures the stability of concentration calculation in complex environments and avoids the spread of single-point errors to the whole.

[0040] Other advantages, objectives and features of the present invention will be described to some extent in the subsequent specification, and to some extent, will be obvious to those skilled in the art based on the study of the following text, or can be learned from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be described in detail preferably with reference to the accompanying drawings, where:

[0042] Figure 1 is the schematic diagram of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0043] The following specific examples illustrate the embodiments of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the drawings provided in the following embodiments only illustrate the basic concept of the present invention schematically. Without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0044] Among them, the drawings are only for illustrative purposes, showing only schematic diagrams, not physical diagrams, and should not be construed as a limitation to the present invention; in order to better illustrate the embodiments of the present invention, some components in the drawings will be omitted, enlarged or reduced, and do not represent the dimensions of actual products; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0045] In the drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "front", "rear", etc. indicating the orientation or positional relationship, they are based on the orientation or positional relationship shown in the drawings. This is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship in the drawings are only for illustrative purposes and cannot be construed as a limitation of the present invention. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0046] As Figure 1 shown, the present invention is a technology for detecting gas accumulation over a long distance in a region within a roadway or space, belonging to the field of coal mine safety technology. The present invention includes using a methane telemeter, a laser rangefinder, and a goniometer to measure the gas accumulation amounts Q1, Q2, …, Q n on multiple optical paths, measuring the distances R1, R2, …, R n corresponding to the multiple optical paths, measuring the angles θ1, θ2, …, θ n of each optical path relative to a calibrated optical path. When the methane concentration is stable within a small default range of the environment, the gas concentration within the circles with radii R1, R2, …, R n from the measurement point can be measured, so as to realize the dot matrix measurement of the gas in the roadway or space over a long distance, and realize the environmental distribution of the gas concentration in the measurement space. In addition, the denser the measured optical paths are, the denser the gas concentration measurement points in the space are, and the more representative the gas concentration at a certain point is, thus realizing the measurement of the gas concentration in a small range or even at a point.

[0047] The method mainly includes the following steps:

[0048] S1: Calibrate an optical path perpendicular to the roadway wall / roof as the calibrated optical path. The distance of the optical path from the laser emission point to the roadway wall / roof is R1, the cumulative gas amount of the optical path R1 is measured as Q1, and the optical path angle θ1 is 0. Calculate the average gas concentration X1 of the optical path R1. Assuming that the gas concentration within the radius R1 of the laser emission point is consistent, it is considered that the gas concentration at all points within the radius R1 is X1;

[0049] Q1 = R1·X1 (1)

[0050] Then it can be obtained that:

[0051] X1 = Q1 / R1 (2)

[0052] In the formula: Q1 represents the cumulative gas amount on the optical path R1 measured by the methane telemeter, and the unit is %·m;

[0053] R1 represents the distance from the laser emission point to the roadway wall / roof, with the unit of m;

[0054] X1 represents the average gas concentration of the R1 optical path, with the unit of %;

[0055] S2: Measure the cumulative gas volume on the second optical path as Q2, the optical path distance from the laser emission point to the roadway wall / roof is R2, and the included angle between the optical path and the calibrated optical path is θ2; calculate the average gas concentration X2 within the ring from R1 to R2. Assume that the gas concentration is consistent within the range from radius R1 to radius R2, then consider the gas concentration at all points within the range of the ring from R1 to R2 as X2;

[0056] Q2 = R1·X1 + (R2 - R1)·X2 (3)

[0057] When R2 cannot be measured, the included angle between R1 and R2 can be used to calculate R2.

[0058] R2 = R1 / cosθ2 (4)

[0059] Then it can be obtained that:

[0060] X2 = (Q2 - R1·X1) / (R2 - R1) = (Q2 - Q1) / (R2 - R1) (5)

[0061] In the formula: Q2 represents the cumulative gas volume on the R2 optical path measured by the methane telemeter, with the unit of %·m;

[0062] R2 represents the distance from the laser emission point to the roadway wall / roof, with the unit of m;

[0063] θ2 represents the included angle that can be used between R1 and R2, with the unit of °;

[0064] X2 represents the average gas concentration of the R2 optical path, with the unit of %;

[0065] S3: Measure the cumulative gas volume on the third optical path as Q3, the optical path distance from the laser emission point to the roadway wall / roof is R3, and the included angle between the optical path and the calibrated optical path is θ3; calculate the average gas concentration X3 within the ring from R2 to R3. Assume that the gas concentration is consistent within the range from the R2 radius to the R3 radius, then consider the gas concentration at all points within the range of the ring from R2 to R3 as X3;

[0066] Q3 = R1·X1 + (R2 - R1)·X2 + (R3 - R2)·X3 (5)

[0067] When R3 cannot be measured, the included angle between R1 and R3 can be used to calculate R3.

[0068] R3 = R1 / cosθ3 (4)

[0069] Then it can be obtained that:

[0070] X3 = (Q3 - Q2) / (R3 - R2) (6)

[0071] ……

[0072] Sn: The cumulative gas volume measured on the nth optical path is Q n , and the optical path distance from the laser emission point to the roadway wall / roof is R n , and the angle between the optical path and the calibrated optical path is θ n ; Calculate R n-1 from R n to R n The average gas concentration X within the ring n-1 , assuming that the gas concentration within the range from the radius of R n to the radius of R n-1 is consistent, then it is considered that the gas concentration at all points within the range from R n to R n in the ring is X

[0073] Q n = R1·X1 + (R2 - R1)·X2 + …… + (R n - R n-1 )·X n (5)

[0074] When R n cannot be measured, the included angle between R1 and R n can be used to calculate R n .

[0075] R3 = R1 / cosθ n (4)

[0076] Then it can be obtained that:

[0077] X n = (Q n - Q n-1 ) / (R n - R n-1 ) (6)

[0078] Complete the measurement of the gas concentration and the measurement of the gas concentration distribution at each spatial point within the measurement range.

[0079] Let θ i (i = 2, 3, …, n) represent the angle between the ith optical path and the calibrated optical path (θ1 = 0°), indicating the inclination angle of any non-calibrated optical path.

[0080] θ n represents the angle between the nth optical path (i.e., the last optical path) and the calibrated optical path, which is a specific example of θ i when i = n.

[0081] Example 1: Detection of Gas Concentration Distribution in the Flat Area of the Roof of a Coal Mine Roadway

[0082] Workflow:

[0083] 1. Equipment Deployment: Install a methane telemeter, a laser rangefinder, and a goniometer on the side wall of the roadway. Adjust the laser emission direction perpendicular to the roof, calibrate the initial optical path (θ1 = 0°), measure the distance R1 = 10 m, and the cumulative gas volume Q1 = 5%·m.

[0084] 2. Calculate the Concentration in the Calibrated Area:

[0085] X1 = Q1 / R1 = 5%·m / 10 m = 0.5%

[0086] It is determined that the gas concentration within the radius range of 0 - 10 m is 0.5%.

[0087] 3. Measure the Second Optical Path: Adjust the laser emission angle θ2 = 30°, and measure Q2 = 7%·m. Calculate the actual detection distance:

[0088] R2 = R1 / cosθ2 = 10 m / cos30° ≈ 11.55 m

[0089] 4. Solve the Concentration in the Annular Area:

[0090] X2 = (Q2 - Q1) / (R2 - R1) = (7 - 5) / (11.55 - 10) ≈ 1.29%

[0091] It is determined that the gas concentration within the annular area of 10 - 11.55 m is 1.29%.

[0092] 5. Extended Detection: Sequentially adjust θ3 = 45°, θ4 = 60°, repeat steps 3 - 4, calculate the concentration of each annular area, and finally generate a gas concentration dot matrix distribution map within the radius of 0 - 15 m.

[0093] Example 2: The roof collapses, resulting in an uneven surface, and the laser needs to be emitted obliquely

[0094] Workflow:

[0095] 1. Calibrate the Initial Optical Path: Measure R1 = 8 m and Q1 = 4%·m perpendicular to the roof, and calculate X1 = 0.5%.

[0096] 2. Measure the Oblique Optical Path: The laser is tilted towards the collapsed area at θ2 = 50°. Since it is impossible to directly measure the distance due to the roof collapse, obtain θ2 through the goniometer and calculate:

[0097] R2 = R1 / cosθ2 = 8 m / cos50° ≈ 12.45 m

[0098] Measure Q2 = 9.5%·m.

[0099] 3. Calculate the concentration in the subsidence area:

[0100] X2 = (9.5 - 4) / (12.45 - 8) ≈ 1.23%

[0101] It is determined that the gas concentration in the subsidence area (8 - 12.45 m) is relatively high and needs to be processed preferentially.

[0102] 4. Verify from multiple angles: Add optical paths with θ3 = 60° and θ4 = 70°, calculate the concentration distribution, and confirm the gas accumulation range in the subsidence area.

[0103] Example 3: Dynamic monitoring of gas diffusion in a sealed goaf

[0104] Workflow:

[0105] 1. Layout of optical paths in multiple directions: Arrange a laser emission device at the entrance of the goaf, and emit 16 optical paths (θ = 0° - 150°) in different directions at intervals of 10°, and obtain the Q of each optical path i , R i .

[0106] 2. Recursively calculate the concentration:

[0107] Independently calculate the concentration X of the annular region for each optical path i (as in Example 1).

[0108] Input the annular concentration data of the 16 optical paths into a three-dimensional interpolation algorithm to generate a three-dimensional cloud map of the gas concentration in the goaf.

[0109] 3. Emergency decision-making: The cloud map shows that the concentration in the area of 10 - 15 m in the southwest direction exceeds the limit (> 1.5%). The system automatically marks the dangerous area to guide the rescue personnel to avoid this path.

[0110] Example 4: High-precision determination of the gas leakage point in the working face.

[0111] Workflow:

[0112] 1. Dense layout of optical paths: Emit 36 radial optical paths (θ = 0° - 180°) at intervals of 5°, and the maximum detection radius R = 20 m.

[0113] 2. High-density calculation:

[0114] Each optical path is segmented and calculated at intervals of 0.5 m (i.e., the ring width is 0.5 m), with a total of 40 annular regions.

[0115] Calculate the X value of each ring through the recurrence formula to generate a high-resolution lattice of 0.5 m × 5°.

[0116] 3. Leak point location: The dot matrix data shows that at θ = 45°, R = 12.5 - 13 m, X = 2.1%, accurately locating the leak point with an error range ≤ 0.3 m.

[0117] 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 preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the purpose and scope of the present technical solution, and they should all be covered by the scope of the claims of the present invention.

Claims

1. A method for measuring the spatial distribution of gas concentration based on laser telemetry technology, characterized in that: The method comprises the following steps: S1: Calibrate an initial optical path perpendicular to the roadway wall or roof as the calibration optical path, measure the distance R1 and the cumulative gas volume Q1 of the calibration optical path, and calculate the average gas concentration X1 of the area corresponding to the calibration optical path; S2: Sequentially measure the cumulative gas volumes Q2 to Q of multiple optical paths n , the corresponding distances R2 to R n and the angles θ2 to θ with the calibrated optical path n ; S3: Calculate the average gas concentration X2 to X in the annular area between adjacent optical paths by means of recursion based on the cumulative gas volume, distance, and included angle of each optical path. n ; S4: Generate dot matrix distribution data of the spatial gas concentration based on the average gas concentrations of all the annular areas.

2. The method for measuring the spatial gas concentration distribution based on laser telemetry technology according to claim 1, characterized in that: The method for calculating X1 in S1 is as follows: X1 = Q1 / R1 Wherein, X1 is the gas concentration of the area corresponding to the calibration optical path, Q1 is the cumulative gas volume of the calibration optical path, and R1 is the distance of the calibration optical path.

3. The method for measuring the spatial gas concentration distribution based on laser telemetry technology according to claim 1, wherein: In S2, if the distance R cannot be directly measured i , where i = 2 to n, then through the formula: R i = R1 / cosθ i It is calculated that where θ i is the angle between the i-th optical path and the calibrated optical path.

4. The method for measuring the spatial gas concentration distribution based on laser telemetry technology according to claim 1, wherein: In the step S3, calculate the average gas concentration X of the annular region corresponding to the k-th optical path, where k = 2 to n, and the formula is: k , k = 2 to n, and the formula is: Among them, R0 = 0, Q k is the cumulative gas volume of the k-th optical path, R k is the distance of the k-th optical path.

5. The method for measuring the spatial gas concentration distribution based on laser telemetry technology according to claim 1, characterized in that: The annular region between adjacent optical paths is a concentric circular ring centered at the laser emission point and defined by an inner radius R k-1 and an outer radius R k .

6. The method for measuring the spatial gas concentration distribution based on laser telemetry technology according to claim 1, wherein: In S4, the generation mode of the dot matrix distribution is: using the average gas concentration of each annular area as the gas concentration value of all points within the area.

7. The method for measuring the spatial distribution of gas concentration based on laser telemetry technology according to claim 1, characterized in that: The included angle θ of the optical path i is measured by a goniometer, and the distance R i is measured by a laser rangefinder, and the cumulative gas volume Q i is measured by a methane telemeter.

8. The method for measuring the spatial gas concentration distribution based on laser telemetry technology according to claim 1, wherein: The number n of the optical paths is n≥3, and the optical paths are radially distributed in space.

9. The method for measuring the spatial gas concentration distribution based on laser telemetry technology according to claim 1, wherein: The method further comprises: drawing a three-dimensional distribution diagram of the gas concentration according to the dot matrix distribution data and marking the areas with excessive concentration.

10. The method for measuring the spatial gas concentration distribution based on laser telemetry technology according to claim 1, wherein: The termination condition for the calculation by the recursive method is: the optical path distance R n reaches the preset maximum detection radius, or the concentration difference between adjacent optical paths is less than the set threshold value.

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