A device and method for detecting methane emission of a gas gate station

Abstract

The application provides a device and method for detecting methane emission of a gas gate station. The device comprises a data processing unit installed on a detection vehicle, a methane concentration measuring module, a temperature and air pressure measuring module, a GPS module, a wind speed measuring module and a compass for measuring the driving direction of the detection vehicle connected with the data processing unit, and a gas sampling module connected with the methane concentration measuring module; the data processing unit calculates the methane emission of the gas gate station based on the methane concentration, temperature, air pressure, wind speed, position coordinates and driving direction observation data obtained when the detection vehicle drives through the gas gate station. The application can realize one-time detection of the methane emission of different sizes of gas gate stations in 2-4 minutes, has the advantages of short time consumption, no need of too much manpower investment, fast detection and calculation speed and high precision.

Description

Technical Field

[0001] This invention belongs to the field of natural gas leak detection technology, specifically relating to a device and method for detecting methane emissions at gas gate stations. Background Technology

[0002] Climate change is a major global challenge. Methane, the main component of natural gas and the second largest greenhouse gas after carbon dioxide, has become a key focus for major countries worldwide in recent years in their efforts to address global climate change. Methane emissions from urban gas storage, transportation, and distribution are highly uncertain, yet there is no standardized measurement method. To develop precise and systematic urban gas methane emission reduction plans, detailed estimates of methane emissions from different sources within the urban gas storage, transportation, and distribution system are needed. Gas gate stations, as crucial nodes in this system, represent a potentially significant source of methane emissions; therefore, a comprehensive assessment of methane emissions from gas gate stations is essential.

[0003] Currently, methane emissions from gas gate stations are primarily estimated using the LDAR (Leak Detection and Repair) method. The LDAR method involves operators using a methane infrared thermal imager to detect potential leaks within the gate station. Quantifiable infrared thermal imagers are available to detect methane leakage at leak points. The process involves first compiling a list of all leak points within the gate station, then having specially trained operators enter the station to inspect each leak point individually, and finally summing the results to obtain the overall emission level. This method has two main drawbacks: First, a single gate station often contains numerous leak points, and the distances between them are relatively short, making the quantitative analysis of each leak point extremely time-consuming and labor-intensive. Furthermore, the method suffers from repeated measurements of specific leaks, potentially leading to overall inflated values. Second, due to the significant differences in leak distribution across gate stations, operators must rely on their experience to plan leak detection for each station, making it difficult to establish a standardized measurement plan. The measurement results are easily influenced by the operator's subjective experience, resulting in low reliability. Summary of the Invention

[0004] To address the aforementioned problems in the prior art, this invention provides a device and method for detecting methane emissions at gas gate stations.

[0005] To achieve the above objectives, the present invention adopts the following technical solution.

[0006] In a first aspect, the present invention provides a gas gate station methane emission detection device, comprising: a data processing unit installed on a detection vehicle, and a methane concentration measurement module, a temperature and pressure measurement module, a GPS module, a wind speed measurement module, and a compass for measuring the driving direction of the detection vehicle connected to the data processing unit; and a gas sampling module connected to the methane concentration measurement module. The gas sampling module includes a gas sampling pipeline vertically installed in front of the detection vehicle, with multiple air inlets at different heights on the gas sampling pipeline. Each air inlet is connected to a gas pipeline, and all gas pipelines converge and are connected to the methane measurement module. Each gas pipeline is equipped with a solenoid valve whose control terminal is connected to the data processing unit. The solenoid valves are sequentially turned on to ensure that only one gas pipeline is open at any given time. The data processing unit calculates the methane emission of the gas gate station based on observation data obtained when the detection vehicle is driving at the gas gate station. The observation data includes methane concentration, temperature, pressure, wind speed, the location coordinates of the detection vehicle, and the driving direction.

[0007] Furthermore, the gas sampling pipeline has five air inlets with heights of h1, h2, h3, h4, and h5 respectively.

[0008] Furthermore, the method for calculating methane emissions from gas gate stations includes:

[0009] Establish a rectangular coordinate system with the initial position of the inspection vehicle as the origin, the distance L of the inspection vehicle relative to the initial position as the abscissa, and the height h as the ordinate.

[0010] Furthermore, the distance traveled by the detection vehicle relative to its initial position is calculated using the following formula:

[0011]

[0012]

[0013] In the formula, L n To detect the distance traveled by the car relative to its initial position at time n, l i Let x be the distance traveled at time i relative to time i-1. i y i Let x and y be the latitude and longitude coordinates of the detection vehicle measured by the GPS module at time i, respectively, where R is the Earth's radius, and x are the initial latitude and longitude coordinates. 0 y 0 .

[0014] Furthermore, the method for calculating methane emissions from gas gate stations also includes:

[0015] The detection area located in the first quadrant of the Cartesian coordinate system is divided into rectangular grids of the same size;

[0016] The observation data within each grid is determined based on the center coordinates of each grid.

[0017] For grids with missing observation data, interpolation is used to supplement the missing observation data.

[0018] Furthermore, the nearest neighbor interpolation method is used to interpolate the grids with missing vehicle driving direction data. The vehicle driving direction data of the grid whose center position x-coordinate is closest to the center position x-coordinate of the grid to be interpolated is used as the vehicle driving direction data of the grid to be interpolated.

[0019] Furthermore, linear interpolation is used to interpolate the grid of missing temperature or pressure data, with the following formula:

[0020]

[0021] In the formula, S P For the temperature or pressure data of the grid P to be interpolated, S P-1 S P+1 The x-coordinates of the center positions are L and L respectively. P-1 L P+1 Temperature or pressure data from two grids, L P-1 L P+1 The x-coordinate of the center position of P is L. P The x-coordinates of the centers of the two closest grid cells, and L P-1 <L P <L P+1 .

[0022] Furthermore, Kriging interpolation is used to interpolate the grid containing missing methane concentration data, as follows:

[0023] Obtain methane concentration data C from N grids where methane concentration data is known. i , i = 1, 2, ..., N;

[0024] Calculate the center distance equal to r kj The semivariance γ(r) of the methane concentration data in the grid kj This yields a set of distance r-semivariance γ data pairs (r, γ), as shown in the following formula:

[0025]

[0026]

[0027] In the formula, r kj For the k-th grid center (L k ,h k ) and the j-th grid center (L j ,hj The distance C(X) is equal to the distance C(X). i ), C(X) i +r kj ) represents the i-th pair of centers whose distance is equal to r. kj The methane concentrations of the two grids, k = 1, 2, ..., N, j = 1, 2, ..., N, k ≠ j, i = 1, 2, ..., n kj n kj The center distance is equal to r kj The number of grid pairs;

[0028] Based on the data pair (r, γ), a spherical model of Kriging interpolation is used for fitting, and the fitting coefficients c0, c, and a of Kriging interpolation are obtained. The spherical model is as follows:

[0029]

[0030] The methane concentration C of the interpolated grid P is calculated using the following formula. P :

[0031]

[0032] In the formula, W i W is the weighting coefficient. i Based on data pairs (γ(r) ij ),γ(r Pj By solving the following, with W i The system of equations for the unknowns yields:

[0033]

[0034] In the formula, r ij r Pj Calculated according to equation (5), r ij r Pj Substituting into equation (6), we get γ(r) ij ), γ(r) Pj ).

[0035] Furthermore, the methane emissions Q from the gas gate station are calculated using the following formula:

[0036]

[0037] In the formula, C mi Let u be the methane mass concentration of the i-th grid. i Let n be the wind speed vector of the i-th grid. f i S represents the unit normal vector of the methane concentration measurement section of the i-th grid facing outward from the emission source, where "·" indicates the vector dot product operation. iLet be the area of ​​the i-th grid, where i = 1, 2, ..., I, and I is the number of grids;

[0038] methane mass concentration C mi The calculation formula is:

[0039]

[0040] In the formula, C i Let T be the methane concentration in the i-th grid, expressed as a volume fraction. i p i Here, represents the temperature and pressure values ​​of the i-th grid, and M is the molar mass of methane.

[0041] Secondly, the present invention provides a method for detecting methane emissions at a gas gate station using the aforementioned device, comprising the following steps performed in a data processing unit while the detection vehicle is traveling at the gas gate station:

[0042] Real-time acquisition of latitude and longitude coordinates of the detection vehicle measured by the GPS module;

[0043] Real-time acquisition of temperature and pressure observation data measured by the temperature and pressure measurement module;

[0044] Real-time acquisition of wind speed observation data measured by the wind speed measurement module;

[0045] Real-time acquisition of observation data on the driving direction of the inspection vehicle measured by the compass;

[0046] Real-time acquisition of methane concentration observation data at different distances and heights measured by the methane concentration measurement module;

[0047] The methane emissions from the gas gate station were calculated based on the observed data.

[0048] Compared with the prior art, the present invention has the following beneficial effects.

[0049] This invention features a data processing unit mounted on a testing vehicle, along with connected modules for methane concentration measurement, temperature and pressure measurement, GPS, wind speed measurement, and a compass for measuring the vehicle's direction of travel. A gas sampling module is also connected to the methane concentration measurement module. The data processing unit calculates the methane emissions from the gas station based on observational data, including methane concentration, obtained while the testing vehicle is traveling through the gas station, thus achieving automatic detection and calculation of methane emissions. Applying this invention typically requires only 2-4 minutes to detect methane emissions from gas stations of varying sizes. It is time-efficient, requires minimal manpower, and offers advantages such as high detection and calculation speed and high accuracy. Attached Figure Description

[0050] Figure 1This is a block diagram of a gas gate station methane emission detection device according to an embodiment of the present invention. In the figure, 1-data processing unit, 2-temperature and pressure measurement module, 3-methane concentration measurement module, 4-GPS module, 5-compass, 6-wind speed measurement module, and 7-gas sampling module.

[0051] Figure 2 This is a schematic diagram of the actual configuration of the detection device.

[0052] Figure 3 This is a schematic diagram of the measurement cross-section surrounding the emission source.

[0053] Figure 4 This is a flowchart illustrating a method for detecting methane emissions at a gas gate station using the aforementioned device, according to an embodiment of the present invention. Detailed Implementation

[0054] To make the objectives, technical solutions, and advantages of this invention clearer and more understandable, the invention will be further described below in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0055] Figure 1 This is a block diagram of a gas gate station methane emission detection device according to an embodiment of the present invention. It includes: a data processing unit 1 installed on a detection vehicle, and connected to the data processing unit 1 are a methane concentration measurement module 3, a temperature and pressure measurement module 2, a GPS module 4, a wind speed measurement module 6, and a compass 5 for measuring the driving direction of the detection vehicle; and a gas sampling module 7 connected to the methane concentration measurement module 3. The gas sampling module 7 includes a gas sampling pipeline vertically installed in front of the detection vehicle. Multiple air inlets are opened at different heights on the gas sampling pipeline, each inlet connecting to a gas pipeline. All gas pipelines converge and are connected to the methane measurement module. Each gas pipeline is equipped with a solenoid valve whose control terminal is connected to the data processing unit 1. The solenoid valves are sequentially activated to ensure that only one gas pipeline is open at any given time. The data processing unit 1 calculates the methane emission of the gas gate station based on observation data obtained when the detection vehicle is driving at the gas gate station. The observation data includes methane concentration, temperature, pressure, wind speed, the location coordinates of the detection vehicle, and the driving direction.

[0056] In this embodiment, the device mainly consists of a data processing unit 1, a methane concentration measurement module 3, a temperature and pressure measurement module 2, a GPS module 4, a wind speed measurement module 6, a compass 5, and a gas sampling module 7. The connection relationships of each part are as follows: Figure 1 As shown below. Each part will be described in detail below.

[0057] The methane concentration measurement module 3 is mainly used for real-time measurement of methane concentration data in the detection environment. The methane concentration measurement module 3 can use common methane measuring instruments to obtain methane concentration observation data, which is generally expressed as volume fraction (ppm).

[0058] Temperature and pressure measurement module 2 is mainly used for real-time measurement of temperature and pressure data in the detection environment. Since the methane emission calculation in this embodiment uses methane mass concentration, it is necessary to convert the concentration, expressed as a volume fraction, into methane mass concentration (mg / m³) based on the real-time measured temperature and pressure data. 3 ).

[0059] GPS module 4 is primarily used for real-time measurement of the vehicle's position coordinates. GPS module 4 can use a US-made GPS receiver, or a domestically produced BeiDou receiver can be used instead. The position coordinates obtained by GPS module 4 are in latitude and longitude.

[0060] The wind speed measurement module 6 is mainly used for real-time wind speed measurement. The wind speed measurement module 6 can employ an anemometer mounted on the testing vehicle. The anemometer measures the wind speed relative to the testing vehicle, and generally needs to be converted into the wind speed relative to the ground based on the vehicle's travel speed. The wind speed is a vector quantity, representing both the wind speed magnitude (m / s) and direction.

[0061] Compass 5 is primarily used for real-time measurement of the inspection vehicle's direction of travel. The vehicle's speed can be calculated based on the vehicle's position coordinates output by GPS module 4.

[0062] Gas sampling module 7 is mainly used to sample air (potentially containing methane) at different distances and heights in real time during the movement of the testing vehicle. Figure 2 As shown, the gas sampling module 7 includes a vertical gas sampling pipeline installed at the front of the testing vehicle. Multiple air inlets are located at different heights along the gas sampling pipeline to sample air at different altitudes. Each air inlet connects to a gas pipeline, and all gas pipelines converge and connect to the methane measurement module. To control the on / off state of the gas pipelines, a solenoid valve is installed on each gas pipeline. The control terminal of the solenoid valve is connected to the data processing unit 1, and the on / off state of the gas pipeline is controlled by the solenoid valve. Under the control of the data processing unit 1, the solenoid valves are sequentially activated to ensure that only one gas pipeline is open at any given time, while the others are closed. The on / off cycle of the solenoid valves is determined empirically, for example, each solenoid valve can be activated for 8 seconds before deactivating. To meet the spatial resolution requirements for data acquisition during the testing vehicle's movement, the measurement frequency of various measuring instruments must be no less than 1 Hz. Z .

[0063] Data processing unit 1 is the data processing and control center of the device. It coordinates the work of other modules by outputting various control signals (e.g., controlling the on / off state of solenoid valves) and completes data processing tasks. In this embodiment, the data processing task is mainly based on various observation data obtained by other modules when the detection vehicle is slowly moving through the gas gate station, such as methane concentration, temperature, gas pressure, wind speed, detection vehicle position coordinates, and driving direction, to calculate the methane emissions of the gas gate station.

[0064] As an optional embodiment, the gas sampling pipeline has five air inlets with heights of h1, h2, h3, h4, and h5 respectively.

[0065] This embodiment defines the characteristics of the air inlets on the gas sampling pipeline. In this embodiment, the sampling pipeline has 5 air inlets, and the distances of the 5 air inlets from the ground are h1, h2, h3, h4, and h5, respectively. Figure 2 As shown. It is worth noting that this embodiment only provides a preferred implementation method and does not exclude or deny other feasible implementation methods, such as more or fewer than 5 air inlets, and air inlets set at heights different from h1 to h5, etc.

[0066] As an optional embodiment, the method for calculating methane emissions from a gas gate station includes:

[0067] Establish a rectangular coordinate system with the initial position of the inspection vehicle as the origin, the distance L of the inspection vehicle relative to the initial position as the abscissa, and the height h as the ordinate.

[0068] This embodiment presents a scheme for establishing a Cartesian coordinate system. Due to the involvement of the test vehicle's ground position and air intake height, existing technologies generally establish a three-dimensional Cartesian coordinate system (o-xyz). To simplify calculations, this embodiment establishes a planar Cartesian coordinate system with the test vehicle's initial position at the start of testing as the origin, the distance L traveled by the test vehicle relative to the initial position as the abscissa, and the height h as the ordinate. Essentially, it transforms the test vehicle's two-dimensional coordinates on the ground into a one-dimensional coordinate system representing the travel distance.

[0069] As an optional embodiment, the travel distance of the detection vehicle relative to its initial position is calculated using the following formula:

[0070]

[0071]

[0072] In the formula, L n To detect the distance traveled by the car relative to its initial position at time n, l i Let x be the distance traveled at time i relative to time i-1. i y iLet x0 and y0 be the latitude and longitude coordinates of the detection vehicle measured by GPS module 4 at the i-th time, respectively, where R is the Earth's radius and the initial latitude and longitude coordinates are x0 and y0, respectively.

[0073] This embodiment provides a technical solution for calculating the travel distance of the detection vehicle relative to its initial position. This embodiment obtains the travel distance of the detection vehicle relative to its initial position by summing the travel distances for each data acquisition cycle (i.e., between two adjacent acquisition times). Specific formulas are shown in equations (1) and (2), which will not be elaborated further here.

[0074] As an optional embodiment, the method for calculating methane emissions from a gas gate station further includes:

[0075] The detection area located in the first quadrant of the Cartesian coordinate system is divided into rectangular grids of the same size;

[0076] The observation data within each grid is determined based on the center coordinates of each grid.

[0077] For grids with missing observation data, interpolation is used to supplement the missing observation data.

[0078] This embodiment presents a technical solution for supplementing missing observation data by dividing the data into grids. For ease of calculation, this embodiment first performs grid division (the methane emissions from all grids are summed to obtain the methane emissions from the gas station). Since the travel distance L and altitude h are both positive values ​​in this embodiment, the grid division is actually performed in the first quadrant of the previously established Cartesian coordinate system. The large rectangular area with the origin as one vertex is divided into multiple rectangular grids of the same size, for example, each grid is a 0.5m × 0.5m square. After grid division, the observation data for each grid is determined based on the center coordinates of each grid. Only one value is taken from the observation data within a grid, i.e., the observation data at the center of the grid is used as the grid's observation data. In actual measurements, it cannot be guaranteed that all observation data can be measured in each grid (some grids may not have any observation data). For example, methane concentration measurements at different altitudes are performed sequentially during the vehicle's movement (i.e., cyclic measurement). For the first L value, data is only available at altitude h, while data at other altitudes are missing. To ensure data integrity, this embodiment uses interpolation to supplement the missing observation data within the grid.

[0079] As an optional embodiment, the nearest neighbor interpolation method is used to interpolate the grid with missing detection vehicle driving direction data. The detection vehicle driving direction data of the grid whose center position x-coordinate is closest to the center position x-coordinate of the grid to be interpolated is used as the detection vehicle driving direction data of the grid to be interpolated.

[0080] This embodiment presents a technical solution for interpolating missing vehicle travel direction data. The vehicle travel direction data is consistent at all heights h, but may vary at different travel distances L; therefore, interpolation is performed only along the travel distance L. Due to the low speed of the vehicle, the data acquisition rate is required to be no less than 1H. Z The distance between two adjacent driving direction data points in the L direction is generally no more than 1m. Therefore, the interpolation method between grids (1m) can be the nearest neighbor interpolation, that is, the driving direction data of the detection vehicle of the grid whose center position x-coordinate is closest to the center position x-coordinate of the grid to be interpolated is used as the driving direction data of the detection vehicle of the grid to be interpolated.

[0081] As an optional embodiment, linear interpolation is used to interpolate the grid containing missing temperature or pressure data, with the following formula:

[0082]

[0083] In the formula, S P For the temperature or pressure data of the grid P to be interpolated, S P-1 S P+1 The x-coordinates of the center positions are L and L respectively. P-1 L P+1 Temperature or pressure data from two grids, L P-1 L P+1 The x-coordinate of the center position of P is L. P The x-coordinates of the centers of the two closest grid cells, and L P-1 <L P <L P+1 .

[0084] This embodiment provides a technical solution for interpolating missing temperature or air pressure data. Temperature and air pressure data are generally referred to as meteorological data. Since the trend of meteorological data variation is not obvious at altitudes close to the ground, it is possible to consider installing a meteorological data measuring instrument (temperature and air pressure measuring module 2) at only a single altitude, and using the meteorological data acquired at that single altitude as the meteorological data for all altitudes. For meteorological data, interpolation is also performed only in the direction of travel distance L, and the interpolation method is linear interpolation. The specific interpolation formula is shown in formula (3).

[0085] As an optional embodiment, Kriging interpolation is used to interpolate the grid containing missing methane concentration data, as follows:

[0086] Obtain methane concentration data C from N grids where methane concentration data is known. i , i = 1, 2, ..., N;

[0087] Calculate the center distance equal to r kjThe semivariance γ(r) of the methane concentration data in the grid kj This yields a set of distance r-semivariance γ data pairs (r, γ), as shown in the following formula:

[0088]

[0089]

[0090] In the formula, r kj For the k-th grid center (L k ,h k ) and the j-th grid center (L j ,h j The distance C(X) is equal to the distance C(X). i ), C(X) i +r kj ) represents the i-th pair of centers whose distance is equal to r. kj The methane concentrations of the two grids, k = 1, 2, ..., N, j = 1, 2, ..., N, k ≠ j, i = 1, 2, ..., n kj n kj The center distance is equal to r kj The number of grid pairs;

[0091] Based on the data pair (r, γ), a spherical model of Kriging interpolation is used for fitting, and the fitting coefficients c0, c, and a of Kriging interpolation are obtained. The spherical model is as follows:

[0092]

[0093] The methane concentration C of the interpolated grid P is calculated using the following formula. P :

[0094]

[0095] In the formula, W i W is the weighting coefficient. i Based on data pairs (γ(r) ij ),γ(r Pj By solving the following, with W i The system of equations for the unknowns yields:

[0096]

[0097] In the formula, r ij r Pj Calculated according to equation (5), r ij r Pj Substituting into equation (6), we get γ(r) ij ), γ(r) Pj ).

[0098] This embodiment provides a technical solution for interpolating missing methane concentration data. Since methane concentration observation data involves two dimensions of information (travel distance L and altitude h), a simple one-dimensional linear interpolation method cannot be used for interpolation calculation. Therefore, this embodiment uses the ordinary Kriging interpolation method to interpolate the grid of missing methane concentration data. Because the methane concentration distribution around a methane emission source represents the influence of the emission source, the spatial distribution characteristics of its complete region need to be determined before it can be used for flux calculation through the Lh two-dimensional plane. This spatial distribution characteristic can be described by Kriging interpolation. The specific steps of the Kriging interpolation algorithm are described above. It is worth noting that when the number of known methane concentration data points N is large, the calculation of the semivariance will be very large, seriously affecting the data processing speed and increasing the error. For example, when N = 200, r in formula (4)... kj The number is as high as C 2 200 =19900! To reduce the computational load, we can first calculate all the r values. kj , will r kj Arrange them in ascending order and divide them into multiple groups, for example, 10 groups, each with 1990 r. kj Then, calculate each r for each group. kj The corresponding semivariance γ(r) kj ), and calculate the average, so that each group gets a result from r. kj and γ(r) kj The average values ​​of the data were used to form 1990 data pairs. Finally, the data pairs were used to fit a spherical model using Kriging interpolation to obtain the fitting coefficients of Kriging interpolation.

[0099] As an optional embodiment, the methane emission Q at the gas gate station is calculated using the following formula:

[0100]

[0101] In the formula, C mi Let u be the methane mass concentration of the i-th grid. i Let n be the wind speed vector of the i-th grid. f i S represents the unit normal vector of the methane concentration measurement section of the i-th grid facing outward from the emission source, where "·" indicates the vector dot product operation. i Let be the area of ​​the i-th grid, where i = 1, 2, ..., I, and I is the number of grids;

[0102] methane mass concentration C mi The calculation formula is:

[0103]

[0104] In the formula, C i Let T be the methane concentration in the i-th grid, expressed as a volume fraction. i p i Here, represents the temperature and pressure values ​​of the i-th grid, and M is the molar mass of methane.

[0105] This embodiment presents a technical solution for calculating methane emissions from a gas gate station. The methane concentration measurement cross-section is shown below. Figure 3 As shown. According to the Gaussian divergence theorem and the law of conservation of mass, the methane flux on the measuring section is equal to the methane emission within the section. For small emission sources, under conditions of weak turbulence, a height of 4.5m (sampling line height) is sufficient to capture the diffuse plume of the entire emission source. Therefore, the overall emission of the emission source can be obtained by calculating the methane emission flux within all grids of the measuring section. The calculation method is shown in formula (9). Since formula (9) requires the methane mass concentration, and the methane concentration measurement module 3 obtains the concentration data expressed as a volume fraction, it is necessary to convert the concentration data expressed as a volume fraction into a mass concentration according to formula (10).

[0106] Figure 4 This is a flowchart illustrating a method for detecting methane emissions at a gas gate station using the aforementioned device, according to an embodiment of the present invention. The flowchart includes the following steps performed in the data processing unit 1 while the detection vehicle is traveling at the gas gate station:

[0107] Step 101: Real-time acquisition of latitude and longitude coordinate observation data of the detection vehicle measured by GPS module 4;

[0108] Step 102: Real-time acquisition of temperature and pressure observation data measured by temperature and pressure measurement module 2;

[0109] Step 103: Real-time acquisition of wind speed observation data measured by wind speed measurement module 6;

[0110] Step 104: Real-time acquisition of observation data on the driving direction of the detection vehicle measured by compass 5;

[0111] Step 105: Real-time acquisition of methane concentration observation data at different distances and heights measured by methane concentration measurement module 3;

[0112] Step 106: Calculate the methane emissions of the gas gate station based on the observed data.

[0113] The method in this embodiment is similar to... Figure 1 The implementation principle and technical effect of the device embodiment shown are similar to those of the other embodiments, and will not be repeated here.

[0114] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A methane emission detection device for a gas gate station, characterized in that, include: The system includes a data processing unit installed on the testing vehicle, along with a methane concentration measurement module, a temperature and pressure measurement module, a GPS module, a wind speed measurement module, and a compass for measuring the vehicle's direction of travel. It also includes a gas sampling module connected to the methane concentration measurement module. The gas sampling module comprises a gas sampling pipeline vertically installed at the front of the testing vehicle. Multiple air inlets are located at different heights on the gas sampling pipeline, each connecting to a gas pipe. All gas pipes converge and connect to the methane concentration measurement module. Each gas pipe is equipped with a solenoid valve whose control terminal is connected to the data processing unit. These solenoid valves are sequentially activated to ensure that only one gas pipe is open at any given time. The data processing unit calculates the methane emissions from the gas gate station based on observation data obtained while the testing vehicle is traveling at the gas gate station. This observation data includes methane concentration, temperature, pressure, wind speed, the testing vehicle's location coordinates, and its direction of travel. The method for calculating methane emissions from gas gate stations includes: Establish a rectangular coordinate system with the initial position of the detection vehicle as the origin, the distance L of the detection vehicle relative to the initial position as the abscissa, and the height h as the ordinate; The method for calculating methane emissions from gas gate stations also includes: The detection area located in the first quadrant of the Cartesian coordinate system is divided into rectangular grids of the same size; The observation data within each grid is determined based on the center coordinates of each grid. For grids with missing observation data, interpolation is used to supplement the missing observation data; Kriging interpolation was used to interpolate the grid containing missing methane concentration data, as follows: Obtain methane concentration data C from N grids where methane concentration data is known. i , i=1,2,...,N; Calculate the center distance equal to r kj The semivariance γ(r) of the methane concentration data in the grid kj This yields a set of distance r-semivariance γ data pairs (r, γ), as shown in the following formula: (4) (5) In the formula, r kj For the k-th grid center (L k ,h k ) and the j-th grid center (L j ,h j The distance C(X) is equal to the distance C(X). i ), C(X) i +r kj ) represents the i-th pair of centers whose distance is equal to r. kj The methane concentrations in the two grids are k=1,2,...,N, j=1,2,...,N, k≠j, i=1,2,...,n. kj n kj The center distance is equal to r kj The number of grid pairs; Based on the data pair (r, γ), a spherical model of Kriging interpolation is used for fitting, and the fitting coefficients c0, c, and a of Kriging interpolation are obtained. The spherical model is as follows: (6) The methane concentration C of the interpolated grid P is calculated using the following formula. P : (7) In the formula, W i W is the weighting coefficient. i Based on data pairs (γ(r) ij ),γ(r Pj By solving the following, with W i The system of equations for the unknowns yields: (8 ) In the formula, r ij r Pj Calculated according to equation (5), r ij r Pj Substituting into equation (6), we get γ(r) ij ), γ(r) Pj ).

2. The gas gate station methane emission detection device according to claim 1, characterized in that, The gas sampling pipeline has five air inlets with heights of h1, h2, h3, h4, and h5.

3. The gas gate station methane emission detection device according to claim 1, characterized in that, Calculate the distance traveled by the test vehicle relative to its initial position using the following formula: (1) (2) In the formula, L n To detect the distance traveled by the car relative to its initial position at time n, l i Let x be the distance traveled at time i relative to time i-1. i y i Let x0 and y0 be the latitude and longitude coordinates of the detection vehicle measured by the GPS module at the i-th time, respectively, where R is the Earth's radius, and the initial latitude and longitude coordinates are x0 and y0, respectively.

4. The gas gate station methane emission detection device according to claim 1, characterized in that, The nearest neighbor interpolation method is used to interpolate the grid with missing detection vehicle driving direction data. The detection vehicle driving direction data of the grid whose center position x-coordinate is closest to the center position x-coordinate of the grid to be interpolated is used as the detection vehicle driving direction data of the grid to be interpolated.

5. The gas gate station methane emission detection device according to claim 1, characterized in that, Linear interpolation is used to interpolate the grid of missing temperature or pressure data. The formula is as follows: (3) In the formula, S P For the temperature or pressure data of the grid P to be interpolated, S P-1 S P+1 The x-coordinates of the center positions are L and L respectively. P-1 L P+1 Temperature or pressure data from two grids, L P-1 L P+1 The x-coordinate of the center position of P is L. P The x-coordinates of the centers of the two closest grid cells, and L P-1 <L P <L P+1 .

6. The gas gate station methane emission detection device according to claim 1, characterized in that, Calculate the methane emissions Q at the gas gate station using the following formula: (9) In the formula, C mi Let u be the methane mass concentration of the i-th grid. i Let n be the wind speed vector of the i-th grid. f i S represents the unit normal vector of the methane concentration measurement section of the i-th grid facing outward from the emission source, where "·" denotes the vector dot product operation. i Let be the area of ​​the i-th grid, where i = 1, 2, ..., I, and I is the number of grids; methane mass concentration C mi The calculation formula is: (10) In the formula, C i T represents the methane concentration in the i-th grid, expressed as a volume fraction. i p i Here, represents the temperature and pressure values ​​of the i-th grid, and M is the molar mass of methane.

7. A method for detecting methane emissions at a gas gate station using the device described in claim 1, characterized in that, This includes the following steps performed in the data processing unit while the testing vehicle is traveling at the gas gate station: Real-time acquisition of latitude and longitude coordinates of the detection vehicle measured by the GPS module; Real-time acquisition of temperature and pressure observation data measured by the temperature and pressure measurement module; Real-time acquisition of wind speed observation data measured by the wind speed measurement module; Real-time acquisition of observation data on the driving direction of the inspection vehicle measured by the compass; Real-time acquisition of methane concentration observation data at different distances and heights measured by the methane concentration measurement module; The methane emissions from the gas gate station were calculated based on the observed data.

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