High-precision laser methane concentration measuring method

Abstract

The invention discloses a high-precision laser methane concentration measurement method, which comprises the following steps: S1, acquiring detection values: continuously penetrating a plurality of lasers with different wavelengths through methane gas in a preset time period, and receiving through a photoelectric receiver to obtain a plurality of groups of detection values, each group of detection values corresponding to the laser with one wavelength; s2, array acquisition: sampling the detection value according to a predetermined sampling frequency, and digitizing the detection value to obtain a plurality of arrays; s3, data cleaning: removing deviating data in each array to obtain a cleaned array; s4, array screening: calculating the numerical value intensity of the cleaned array; and S5, determining the methane concentration: comparing the array with the maximum numerical value intensity with the methane concentration reference table to obtain a methane concentration value. According to the invention, measurement errors caused by interference and the like can be effectively eliminated, and the measurement precision is improved.

Description

Technical Field

[0001] The present invention relates to the field of measurement technology, and in particular to a high-precision laser methane concentration measurement method. Background Art

[0002] Based on the principle that the absorption of light by gas at its characteristic absorption wavelength changes with concentration, the laser penetrates the methane gas and is absorbed. The methane concentration is measured by detecting the attenuation of the laser after penetrating the methane gas.

[0003] Due to the interference of instantaneous drift or noise of the measuring equipment circuit, measurement errors may occur, thereby affecting the measurement accuracy. Summary of the Invention

[0004] To overcome the above-mentioned drawbacks, the present invention aims to provide a high-precision laser methane concentration measurement method, which can effectively eliminate the measurement errors caused by the above-mentioned situation and improve the measurement accuracy.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A high-precision laser methane concentration measurement method comprises the following steps:

[0007] S1. Obtaining detection values: Continuously passing a plurality of lasers of different wavelengths through the methane gas during a predetermined time period, and receiving a plurality of groups of detection values through a photoelectric receiver, each group of detection values corresponding to a wavelength of laser light;

[0008] S2. Obtaining arrays: sampling the detection values according to a predetermined sampling frequency, digitizing the measurement values, and obtaining a plurality of arrays;

[0009] S3, data cleaning: remove the deviating data in each array to obtain the cleaned array;

[0010] S4, array screening: calculate the numerical density of the cleaned array;

[0011] S5. Determine the methane concentration: Compare the array with the highest numerical density with a methane concentration reference table to obtain a methane concentration value. The methane concentration reference table is established based on historical measurement data. The methane concentration reference table includes sub-tables corresponding to the plurality of lasers of different wavelengths. The sub-tables store the historical measurement data and the methane concentration reference values corresponding to the historical measurement data.

[0012] Furthermore, after step S5, the following steps are further included:

[0013] S6. Update the methane concentration reference table: add the methane concentration value and the corresponding measurement data as the methane concentration reference value and historical measurement data to the methane concentration reference table.

[0014] Preferably, in step S1, the output power of the laser emitting laser light of each wavelength is constant; and the output of the photoelectric receiver is a voltage value.

[0015] Preferably, in step S3, the arithmetic mean of the arithmetic group is calculated, and the deviation data is data whose difference with the arithmetic mean reaches a predetermined threshold.

[0016] Preferably, in step S4, the method for calculating the numerical density of the cleaned array is as follows:

[0017]

[0018] Among them, q i is the numerical density of the ith cleaned array, p j is the jth element of the cleaned array, p0 is the arithmetic mean of all elements of the cleaned array, and n is the number of elements in the cleaned array; q i The smaller the value, the greater the density of the values.

[0019] Furthermore, step S5 includes the following sub-steps:

[0020] S5.1. Compare the numerical density of all cleaned arrays and extract the arithmetic mean of the cleaned array with the largest numerical density as the comparison value;

[0021] S5.2. Compare the comparison value with the historical measurement data in the corresponding sub-table, and obtain the methane concentration value according to the comparison result. The corresponding sub-table is a sub-table with the same wavelength as the wavelength of the cleaned array with the largest value density.

[0022] Preferably, in sub-step S5.2, the method for obtaining the methane concentration value based on the comparison result is as follows:

[0023] When the comparison value is the same as a historical measurement data in the sub-table, the methane concentration reference value corresponding to the historical measurement data is used as the measurement result of this measurement;

[0024] When the comparison value is different from any historical measurement data in the subtable, the middle value between the methane concentration reference values corresponding to the left value and the right value in the subtable is taken as the measurement result of this measurement, the left value is the historical measurement data in the subtable that is closest to the comparison value and is smaller than the comparison value, and the right value is the historical measurement data in the subtable that is closest to the comparison value and is larger than the comparison value.

[0025] As a preference, the intermediate value is a median value.

[0026] As another preferred embodiment, the middle value is the linear mean of the methane concentration reference values corresponding to the left value and the right value, respectively. The linear mean is calculated as follows:

[0027]

[0028] Where a is the linear mean, b0 is the comparison value, b2 is the right value, b1 is the left value, c2 is the reference value of methane concentration corresponding to the right value, and c1 is the reference value of methane concentration corresponding to the left value.

[0029] The beneficial effects of the present invention are as follows:

[0030] 1. The present invention can effectively eliminate interference and improve measurement accuracy.

[0031] 2. The present invention uses multiple wavelength lasers for measurement, which can effectively avoid the limitations of single wavelength lasers.

[0032] 3. The present invention uses historical measurement data as a reference and updates the reference table, so that the measurement accuracy can be improved during the correction process. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Flow chart of the method of the present invention. DETAILED DESCRIPTION

[0034] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings.

[0035] Example 1

[0036] like Figure 1 As shown, this embodiment discloses a high-precision laser methane concentration measurement method, comprising the following steps:

[0037] S1. Obtaining detection values: Continuously passing a plurality of lasers of different wavelengths through the methane gas during a predetermined time period, and receiving a plurality of groups of detection values through a photoelectric receiver, each group of detection values corresponding to a wavelength of laser light;

[0038] S2. Obtaining arrays: sampling the detection values according to a predetermined sampling frequency, digitizing the measurement values, and obtaining a plurality of arrays;

[0039] S3, data cleaning: remove the deviating data in each array to obtain the cleaned array;

[0040] S4, array screening: calculate the numerical density of the cleaned array;

[0041] S5. Determine the methane concentration: Compare the array with the highest numerical density with a methane concentration reference table to obtain a methane concentration value. The methane concentration reference table is established based on historical measurement data. The methane concentration reference table includes sub-tables corresponding to the plurality of lasers of different wavelengths. The sub-tables store the historical measurement data and the methane concentration reference values corresponding to the historical measurement data.

[0042] in:

[0043] The output power of the laser emitting laser light of each wavelength is constant; the output of the photoelectric receiver is a voltage value.

[0044] In step S3, the arithmetic mean of the arithmetic group is calculated, and the deviating data is the data whose difference with the arithmetic mean reaches a predetermined threshold. The deviating data is caused by interference, sudden changes in the environment, and instantaneous drift of the measurement circuit. It is unreliable data and affects the measurement accuracy and needs to be eliminated.

[0045] In step S4, the method for calculating the numerical density of the cleaned array is as follows:

[0046]

[0047] Among them, q i is the numerical density of the ith cleaned array, p j is the jth element of the cleaned array, p0 is the arithmetic mean of all elements of the cleaned array, and n is the number of elements in the cleaned array; q i The smaller the value, the greater the density of the values.

[0048] Step S5 includes the following sub-steps:

[0049] S5.1. Compare the numerical density of all cleaned arrays and extract the arithmetic mean of the cleaned array with the largest numerical density as the comparison value;

[0050] S5.2. Compare the comparison value with the historical measurement data in the corresponding sub-table, and obtain the methane concentration value according to the comparison result. The corresponding sub-table is a sub-table with the same wavelength as the wavelength of the cleaned array with the largest value density.

[0051] In sub-step S5.2, the method for obtaining the methane concentration value based on the comparison result is as follows:

[0052] When the comparison value is the same as a historical measurement data in the sub-table, the methane concentration reference value corresponding to the historical measurement data is used as the measurement result of this measurement;

[0053] If the comparison value differs from any of the historical measurement data in the subtable, the middle value between the methane concentration reference values corresponding to the left and right values in the subtable is taken as the measurement result for this measurement. The left value is the historical measurement data in the subtable that is closest to the comparison value and smaller than the comparison value, and the right value is the historical measurement data in the subtable that is closest to the comparison value and larger than the comparison value. Then, step S6 is executed to update the methane concentration reference table, adding the methane concentration value and the corresponding measurement data as the methane concentration reference value and historical measurement data to the methane concentration reference table.

[0054] In this embodiment, the middle value is the median value, that is, the arithmetic mean of the methane concentration reference values corresponding to the left value and the right value is used as the middle value.

[0055] Example 2

[0056] The difference between this embodiment and embodiment 1 is that:

[0057] The middle value is the linear mean of the methane concentration reference values corresponding to the left and right values, respectively. The linear mean is calculated as follows:

[0058]

[0059] Where a is the linear mean, b0 is the comparison value, b2 is the right value, b1 is the left value, c2 is the reference value of methane concentration corresponding to the right value, and c1 is the reference value of methane concentration corresponding to the left value.

[0060] The rest of this embodiment is the same as that of Embodiment 1, and therefore will not be described in detail.

[0061] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art may make various corresponding changes and modifications based on the present invention, but these corresponding changes and modifications should all fall within the scope of protection of the claims attached to the present invention.

Claims

1. A high-precision laser methane concentration measurement method, characterized in that: The following steps are involved: S1. Obtaining detection values: Continuously passing a plurality of lasers of different wavelengths through the methane gas during a predetermined time period, and receiving a plurality of groups of detection values through a photoelectric receiver, each group of detection values corresponding to a wavelength of laser light; S2. Obtaining arrays: sampling the detection values according to a predetermined sampling frequency, digitizing the measurement values, and obtaining a plurality of arrays; S3, data cleaning: remove the deviating data in each array to obtain the cleaned array; S4, array screening: calculate the numerical density of the cleaned array; S5. Determine the methane concentration: Compare the array with the highest numerical density with a methane concentration reference table to obtain a methane concentration value. The methane concentration reference table is established based on historical measurement data. The methane concentration reference table includes sub-tables corresponding to the plurality of lasers of different wavelengths. The sub-tables store the historical measurement data and the methane concentration reference values corresponding to the historical measurement data.

2. The high-precision laser methane concentration measurement method according to claim 1, characterized in that: After step S5, the following steps are also included: S6. Update the methane concentration reference table: add the methane concentration value and the corresponding measurement data as the methane concentration reference value and historical measurement data to the methane concentration reference table.

3. The high-precision laser methane concentration measurement method according to claim 1 or 2, characterized in that: In step S1 , the output power of the laser emitting laser light of each wavelength is constant; and the output of the photoelectric receiver is a voltage value.

4. The high-precision laser methane concentration measurement method according to claim 3, characterized in that: In step S3, the arithmetic mean of the arithmetic group is calculated, and the deviation data is the data whose difference with the arithmetic mean reaches a predetermined threshold.

5. The high-precision laser methane concentration measurement method according to claim 3, characterized in that: In step S4, the method for calculating the numerical density of the cleaned array is as follows: Among them, q i is the numerical density of the ith cleaned array, p j is the jth element of the cleaned array, p0 is the arithmetic mean of all elements of the cleaned array, and n is the number of elements in the cleaned array; q i The smaller the value, the greater the density of the values.

6. The high-precision laser methane concentration measurement method according to claim 3, characterized in that: Step S5 includes the following sub-steps: S5.

1. Compare the numerical density of all cleaned arrays, and extract the arithmetic mean of the cleaned array with the largest numerical density as the comparison value; S5.

2. Compare the comparison value with the historical measurement data in the corresponding sub-table, and obtain the methane concentration value according to the comparison result. The corresponding sub-table is a sub-table with the same wavelength as the wavelength of the cleaned array with the largest value density.

7. The high-precision laser methane concentration measurement method according to claim 6, characterized in that: In sub-step S5.2, the method for obtaining the methane concentration value based on the comparison result is as follows: When the comparison value is the same as a historical measurement data in the sub-table, the methane concentration reference value corresponding to the historical measurement data is used as the measurement result of this measurement; When the comparison value is different from any historical measurement data in the subtable, the middle value between the methane concentration reference values corresponding to the left value and the right value in the subtable is taken as the measurement result of this measurement, the left value is the historical measurement data in the subtable that is closest to the comparison value and is smaller than the comparison value, and the right value is the historical measurement data in the subtable that is closest to the comparison value and is larger than the comparison value.

8. The high-precision laser methane concentration measurement method according to claim 7, characterized in that: The intermediate value is the median.

9. The high-precision laser methane concentration measurement method according to claim 7, characterized in that: The middle value is the linear mean of the methane concentration reference values corresponding to the left and right values, respectively. The linear mean is calculated as follows: Where a is the linear mean, b0 is the comparison value, b2 is the right value, b1 is the left value, c2 is the reference value of methane concentration corresponding to the right value, and c1 is the reference value of methane concentration corresponding to the left value.

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