Gas concentration measuring method and measuring system based on self-adaptive wavelength

Abstract

The invention belongs to the technical field of gas detection, and particularly relates to a gas concentration measurement method and system based on adaptive wavelength. The measurement method comprises the following steps: obtaining a waveform curve of a to-be-measured gas absorption signal; if the current waveform curve is distorted, the to-be-detected gas is scanned again after the current scanning interval is widened until the newest waveform curve is not distorted, and the newest waveform curve is subjected to convolution processing to obtain a second reasonable curve; and if K3 continuous sampling points greater than a third set threshold exist in the absorption interval of the second reasonable curve, recording the current second reasonable curve as a third reasonable curve, and calculating the current concentration of the gas to be detected according to the third reasonable curve, on the contrary, the scanning interval corresponding to the current second reasonable curve is narrowed, and then the to-be-detected gas is scanned again. According to the invention, high-efficiency and accurate concentration measurement can be carried out on to-be-measured gases with different concentrations.

Description

A gas concentration measurement method and system based on adaptive wavelength Technical Field

[0001] This application belongs to the field of gas detection technology, and in particular relates to a gas concentration measurement method and system based on adaptive wavelength. Background Technology

[0002] Traditional TDLAS (Tunable Laser Absorption Spectroscopy) gas detection devices are mostly used in laboratories or short-range measurement scenarios. Because each gas has its specific absorption spectral lines, technicians usually pre-set the wavelength range of the laser based on the absorption spectral lines after the composition of the gas to be measured is determined. Therefore, in order to achieve accurate measurement of different gas concentrations and different types of gases, the accuracy of gas concentration measurement is usually improved by changing the optical path, such as switching the length of the gas chamber.

[0003] However, in practice, the size of a gas chamber is limited, and changing the gas chamber is difficult due to constraints such as cost and time. Especially in telemetry scenarios, the size of the gas chamber is usually fixed, and the optical path is determined by the size of the gas chamber and cannot be manually adjusted. This can lead to absorption saturation when measuring the concentration of high-concentration analytes, resulting in a lower-than-expected concentration. Furthermore, with a fixed optical path, it is impossible to simultaneously measure both high and low concentrations.

[0004] Therefore, there is an urgent need for a gas concentration measurement method that can efficiently and accurately measure the concentration of different gases to be measured. Summary of the Invention

[0005] The purpose of this application is to overcome the shortcomings of the prior art and provide a gas concentration measurement method based on adaptive wavelength, which can efficiently and accurately measure the concentration of the gas to be measured at different concentrations without changing the gas chamber.

[0006] To achieve the above objectives, this application adopts the following technical solution: a gas concentration measurement method based on adaptive wavelength, comprising the following steps: S1, scanning the gas to be measured in the gas chamber using a laser whose wavelength continuously varies within the scanning interval, and obtaining the waveform curve of the absorption signal of the gas to be measured; if the current waveform curve is distorted, the current scanning interval is widened and the gas to be measured is scanned again until the latest waveform curve is free from distortion, and the latest waveform curve is recorded as the first reasonable curve and then proceeds to S2; S2, the first reasonable curve is convolved to obtain the second reasonable curve, and the absorption interval of the laser absorbed by the gas to be measured is obtained in the second reasonable curve; if there are K3 consecutive sampling points in the absorption interval that are greater than a third set threshold, the current second reasonable curve is recorded as the third reasonable curve and then proceeds to S3, otherwise the scanning interval corresponding to the current second reasonable curve is narrowed and the gas to be measured is scanned again until the latest second reasonable curve can be recorded as the third reasonable curve and then proceeds to S3; S3, the current concentration of the gas to be measured is calculated using the third reasonable curve.

[0007] Preferably, S1 includes the following sub-steps: S11, after determining the center wavelength of the laser used according to the composition of the gas to be measured, the scanning interval for the first laser scan is determined according to the center wavelength; the scanning interval for the first laser scan is recorded as the reference scanning interval; S12, after the gas to be measured in the gas chamber is scanned for the first time using a laser whose wavelength changes continuously within the reference scanning interval, the waveform curve of the absorption signal of the gas to be measured is obtained; if there are K1 consecutive sampling points exceeding the first set threshold and / or K2 consecutive sampling points less than the second set threshold in any sampling period of the current waveform curve, it is determined that the current waveform curve is distorted, then the current scanning interval is widened and the gas to be measured is scanned again until the latest waveform curve is free of distortion, the latest waveform curve is recorded as the first reasonable curve and S2 is executed.

[0008] Preferably, in S12, the current scanning interval is widened to serve as the scanning interval for the next scan, including the following: consecutive sampling points exceeding a first set threshold and consecutive sampling points less than a second set threshold are both recorded as distorted sampling points; keeping the current center wavelength unchanged, if the proportion of distorted sampling points in any sampling period of the current waveform curve exceeds P1 of the total number of sampling points in one sampling period, then the current scanning interval is widened by M1 times to serve as the scanning interval for the next scan, otherwise the current scanning interval is widened by a set amount to serve as the scanning interval for the next scan.

[0009] Preferably, in S2, each sampling period of the second reasonable curve contains two peak points, which are denoted as the first convex point and the second convex point, respectively; the height of the first convex point is lower than the height of the second convex point; the scanning point interval formed by the first convex point and the K4 scanning points before and after it is denoted as the absorption interval where the laser is absorbed by the gas to be measured.

[0010] Preferably, in step S2, after narrowing the scanning interval corresponding to the current second reasonable curve and re-scanning the gas to be tested, the following steps are also included: Step 1, the scanning interval width of the current second reasonable curve is recorded as the upper limit of the width, and the scanning interval width of the previous scan used to obtain the current second reasonable curve is recorded as the lower limit of the width; Step 2, the average of the upper and lower limits of the width is taken as the width of the narrowed scanning interval, the center wavelength is kept unchanged, and the gas to be tested is re-scanned after obtaining the scanning interval for the next scan to obtain the latest waveform curve; Step 3, if the latest waveform curve has no distortion, the first reasonable curve is updated to the latest waveform curve and step S2 is executed again; if the latest waveform curve has distortion, the lower limit of the width is updated to the scanning interval width of the latest waveform curve and step 2 is returned.

[0011] Preferably, if the number of consecutive executions of steps 2 to 3 exceeds T times, a warning is issued to the technician.

[0012] Preferably, S3 includes the following: based on the third reasonable curve, obtain the absorption range and the sampling point information corresponding to the second convex point and the normalized value of the detector output voltage; and after obtaining the scanning coefficient of the scanning range width corresponding to the third reasonable curve relative to the reference scanning range width, calculate the current concentration of the gas to be measured.

[0013] This application also provides a gas concentration measurement system based on adaptive wavelength, including: a TDLAS system, a first reasonable curve determination module, a convolution module, a third reasonable curve determination module, and a gas concentration calculation module; the TDLAS system is used to scan the gas to be measured in the gas chamber using a laser with a wavelength that changes continuously within the scanning interval, and then sends the waveform curve of the absorption signal of the gas to be measured to the first reasonable curve determination module; the first reasonable curve determination module is used to determine whether the current waveform curve is a first reasonable curve based on the distortion of the current waveform curve; if the current waveform curve is distorted, the first reasonable curve determination module widens the scanning interval of the TDLAS system and rescans the gas to be measured until the first reasonable curve determination module determines that the current waveform curve is a first reasonable curve, and then sends the first reasonable curve into the convolution module. The system comprises several modules: an induction module and a convolution module. The induction module processes the first reasonable curve into a second reasonable curve, which is then sent to the third reasonable curve determination module. The third reasonable curve determination module determines whether the current second reasonable curve is a third reasonable curve based on its absorption range. If not, the third reasonable curve determination module narrows the scanning range of the current second reasonable curve, causing the TDLAS system to rescan the gas to be measured based on the narrowed scanning range. This process continues until the third reasonable curve determination module determines that the current second reasonable curve is a third reasonable curve. At this point, the third reasonable curve is sent to the gas concentration calculation module. The gas concentration calculation module calculates and calibrates the concentration of the gas to be measured based on the third reasonable curve. Each module is programmed or configured to perform the steps of an adaptive wavelength-based gas concentration measurement method as described above.

[0014] This application also provides a computer-readable storage medium storing a computer program programmed or configured to perform a gas concentration measurement method based on an adaptive wavelength as described above.

[0015] This application also provides a computer program product, including a computer program / instructions that, when executed by a processor, implement the steps of the above-described adaptive wavelength-based gas concentration measurement method.

[0016] The beneficial effects of this application are: (1) The gas concentration measurement method based on adaptive wavelength of this application can efficiently and accurately measure the concentration of the gas to be measured at different concentrations by adjusting the width of the scanning interval without replacing the gas chamber; it saves costs by not rebuilding the gas chamber; it is especially suitable for remote telemetry scenarios such as environmental telemetry, industrial safety and energy extraction.

[0017] (2) The gas concentration measurement method of this application avoids the problem of absorption saturation caused by the fixed scanning range during the TDLAS measurement process, thus avoiding the problem of low measured concentration caused by waveform image distortion.

[0018] (3) The gas concentration measurement method of this application can dynamically measure different concentrations of gas in the gas chamber and achieve continuous measurement from low concentration to high concentration because the width of the scanning interval can be adaptively adjusted according to the gas to be measured.

[0019] (4) In the process of widening the adaptive scanning interval, this application first widens the baseline scanning interval to ensure that the waveform image of the gas to be tested with a high concentration will not be distorted after scanning; then, by narrowing the widened scanning interval, it ensures that the absorption interval of the gas to be tested can be clearly and accurately identified, and will not fail to be accurately identified due to the low concentration of the gas to be tested; and it is precisely because the scanning interval satisfies these two constraints that the concentration of the gas to be tested calculated by the waveform curve used in this application is sufficiently accurate and reliable.

[0020] (5) The methods for widening and narrowing the scanning interval in this application ensure that this application does not need to perform multiple rescanning verifications after widening or narrowing the interval. Instead, it can quickly obtain a suitable interval width and find a suitable waveform curve to calculate the concentration of the gas to be measured in the shortest time, which greatly improves the calculation efficiency of the concentration of the gas to be measured: ① The method of widening the scanning interval ensures that a suitable scanning interval width can be found with as few rescannings as possible, so that the waveform curve will not be distorted; ② The method of narrowing the scanning interval ensures that the waveform curve will not be distorted after each narrowing of the scanning interval, and effectively narrows the scanning interval width with as few loops as possible, thereby improving the efficiency of selecting a suitable scanning interval width; ③ Only by selecting a suitable scanning interval width (not too narrow or too wide) can the waveform curve obtained after scanning the gas to be measured in the gas chamber with a laser whose wavelength changes continuously within this scanning interval be accurately calculated to determine the concentration of the gas to be measured. Attached Figure Description

[0021] Figure 1 is a flowchart of a gas concentration measurement method based on adaptive wavelength; Figure 2 is a schematic diagram of the effect of widening the scanning interval on the waveform curve; Figure 3 is a schematic diagram of the effect of different scanning intervals on the waveform curve; Figure 4 is a schematic diagram of the curve obtained after convolution processing of the waveform curve in Figure 3; Figure 5 is a schematic diagram of the overall architecture of the TDLAS system. Detailed Implementation

[0022] To make the technical solution of this application clearer and more explicit, the application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Solutions derived by those skilled in the art through equivalent substitution and conventional reasoning of the technical features of the technical solution of this application without creative effort all fall within the protection scope of this application.

[0023] Figure 1 shows a flowchart of a gas concentration measurement method based on adaptive wavelength according to this application, including: S1, scanning the gas to be measured in the gas chamber using a laser with a wavelength that changes continuously within the scanning interval to obtain the waveform curve of the absorption signal of the gas to be measured; if the current waveform curve is distorted, the current scanning interval is widened and the gas to be measured is scanned again until the latest waveform curve is free of distortion, and the latest waveform curve is recorded as the first reasonable curve and then S2 is executed; S2, the first reasonable curve is convolved to obtain the second reasonable curve, and the absorption interval of the laser absorbed by the gas to be measured is obtained in the second reasonable curve; if there are K3 consecutive sampling points in the absorption interval that are greater than a third set threshold, the current second reasonable curve is recorded as the third reasonable curve and then S3 is executed, otherwise the scanning interval corresponding to the current second reasonable curve is narrowed and the gas to be measured is scanned again until the latest second reasonable curve can be recorded as the third reasonable curve and then S3 is executed; S3, the current concentration of the gas to be measured is calculated using the third reasonable curve.

[0024] The measurement method of this application relies on a TDLAS system, as shown in Figure 5: A gas chamber is located between the laser and the detector, filled with the gas to be measured. The microcontroller uses a digital-to-digital converter to output a scanning signal to the drive circuit. The drive circuit drives the laser to emit a laser signal based on the scanning signal. The laser signal propagates through the gas in the gas chamber and is received by the detector at the other end of the chamber. After being filtered and amplified by a filtering and amplification circuit, it is sent to an analog-to-digital converter for conversion. The converted analog signal is then sent to the microcontroller for signal processing. The overall architecture of the TDLAS system is shown in Figure 5; the components are existing technologies and will not be described in detail here.

[0025] S1 also includes the following sub-steps: S11, after determining the center wavelength of the laser used according to the composition of the gas to be measured, the scanning interval for the first laser scan is determined according to the center wavelength; the scanning interval for the first laser scan is recorded as the reference scanning interval; S12, after the gas to be measured in the gas chamber is scanned for the first time using a laser whose wavelength changes continuously within the reference scanning interval, the waveform curve of the absorption signal of the gas to be measured is obtained; if there are K1 consecutive sampling points exceeding the first set threshold and / or K2 consecutive sampling points less than the second set threshold in any sampling period of the current waveform curve, it is determined that the current waveform curve is distorted, then the current scanning interval is widened and the gas to be measured is scanned again until the latest waveform curve is free of distortion, the latest waveform curve is recorded as the first reasonable curve and then S2 is executed.

[0026] K1 and K2 are both positive integers, and their specific values ​​are preset by technical personnel.

[0027] In S11: The width of the reference scan interval is preset by the technician.

[0028] In S12: The horizontal axis of the waveform curve of this application is the serial number corresponding to the sampling point at the relative wavelength, and the vertical axis is the light intensity collected by the detector at the other end of the gas chamber; the vertical axis can also be the output voltage value of the detector. The detector is used to detect the light intensity after the laser is absorbed by the gas to be tested. Therefore, the output voltage value of the detector is proportional to the light intensity collected. Therefore, the first set threshold and the second set threshold are both set in advance by the technician according to the center wavelength of the emitted laser.

[0029] If the current waveform curve is distorted, it indicates that the concentration of the gas to be measured in the gas chamber is high and has already reached concentration saturation relative to the width of the current reference scanning range. Using a laser with a wavelength that continuously varies within the reference scanning range for scanning and measurement will result in a final measured concentration that is lower than the actual concentration. Therefore, we need to widen the current scanning range.

[0030] In S12, the current scanning interval is widened to serve as the scanning interval for the next scan. This also includes the following: consecutive sampling points exceeding the first set threshold and consecutive sampling points less than the second set threshold are both recorded as distorted sampling points. Keeping the current center wavelength unchanged, if the proportion of distorted sampling points in any sampling period of the current waveform curve exceeds P1 of the total number of sampling points in one sampling period, then the current scanning interval is widened by M1 times to serve as the scanning interval for the next scan. Otherwise, the current scanning interval is widened by a set amount to serve as the scanning interval for the next scan.

[0031] In this application, M1 is a positive number. In this embodiment, M1=1; the broadening setting is 0.1nm; P1=20%.

[0032] On the same waveform curve, the waveform curve segment in each sampling period is identical, and the number of sampling points contained in each sampling period is the same; a waveform curve contains at least one sampling period. The number of sampling points contained in each sampling period is determined by the sampling frequency of the analog-to-digital converter connected to the detector side.

[0033] For ease of understanding, as shown in Figure 2, the horizontal axis represents the serial number of the sampling point at the relative wavelength, and the vertical axis represents the output voltage value of the detector. The black curve is the waveform curve obtained by scanning the gas to be tested in the gas chamber using a laser that continuously changes within the reference scanning range, and it can be seen that severe distortion has occurred. The red curve is the waveform curve obtained by scanning again after widening the reference scanning range, and it can be seen that there is no distortion. That is, the red curve at this time is the first reasonable curve.

[0034] The method of widening the scanning interval ensures that a suitable scanning interval width can be found with as few rescans as possible, so that the waveform curve will not be distorted.

[0035] In S2, it needs to be explained that if the concentration of the gas to be measured in the current chamber is too high relative to a certain scanning interval, the waveform curve will be distorted. Therefore, directly performing convolution processing on the obtained waveform curve will not clearly show the absorption interval and the second convex point containing the intensity of the signal light in the convolutioned curve. So we must first use S1 and its sub-steps to automatically and quickly and reasonably widen the scanning interval so that the concentration of the gas to be measured is not too high relative to the scanning interval.

[0036] Figure 3 shows the undistorted waveform curves corresponding to different scanning intervals. The gas to be measured in the gas chamber remains constant in Figure 3. The vertical axis represents the normalized detector output voltage value, so it has no unit and its value is between 0 and 1. The four curves of different colors in Figure 3 represent waveform curves under different scanning intervals. The center wavelengths of these four scanning intervals are the same, but the interval width decreases sequentially from the first to the fourth scanning interval. In Figure 3, regardless of the waveform curve, it is clear that there is a dip near the left side of the waveform curve during its ascent, forming the first relative low point; near the right side of the waveform curve, there is a step-like drop followed by a gradual rise, forming the second relative low point. The interval containing the first relative low point is the absorption interval, and the second relative low point contains the laser type and intensity information. If the waveform curve is distorted due to excessively high concentration of the gas to be measured, it is impossible to clearly and definitively see the two relative low points within one cycle as in Figure 3. Instead, the waveform curve will have multiple undulations of varying sizes, and excessively wide flat areas at the bottom or top, as shown by the black curve in Figure 2.

[0037] The convolution processing performed in S2 is a prior art technique and will not be described in detail here.

[0038] Compared to the first reasonable curve, the second reasonable curve obtained after convolution processing is more convenient for technicians to determine whether the current scanning range is reasonable based on the absorption range.

[0039] In S2: Each sampling period of a second reasonable curve contains two peak points. The lower peak point on the ordinate is designated as the first convex point, and the higher peak point is designated as the second convex point, as shown in Figure 4. On the green curve, the first convex point is point Z1, and the second convex point is point Z2. The scanning point interval formed by the first convex point and the K4 scanning points before and after it is designated as the absorption interval where the laser is absorbed by the gas to be measured. As can be seen in Figure 4, regardless of the curve, the first convex point is always on the left, while the second convex point is on the right. The horizontal and vertical axes of Figure 4 are the same as those of Figure 3. It is evident that the first convex point in Figure 4 corresponds to the position of the first relatively low point in Figure 3, and the second convex point in Figure 4 corresponds to the position of the second relatively low point in Figure 3.

[0040] K3 is a positive integer, and its specific value is preset by technical personnel.

[0041] In this embodiment, the center wavelength of the scanning interval is 2.0 μm, K1=100, K2=20, and K3=50.

[0042] In step S2, after narrowing the scanning interval corresponding to the current second reasonable curve, the gas to be tested is scanned again. This also includes the following steps: Step 1, the scanning interval width of the current second reasonable curve is recorded as the upper limit of the width, and the scanning interval width of the previous scan that obtained the current second reasonable curve is recorded as the lower limit of the width; Step 2, the average of the upper and lower limits of the width is taken as the width of the narrowed scanning interval, the center wavelength is kept unchanged, and the scanning interval of the next scan is obtained, and the gas to be tested is scanned again to obtain the latest waveform curve; Step 3, if the latest waveform curve has no distortion, the first reasonable curve is updated to the latest waveform curve and step S2 is executed again; if the latest waveform curve has distortion, the lower limit of the width is updated to the scanning interval width of the latest waveform curve and step 2 is returned.

[0043] Optionally, if the loop of steps 2 to 3 is executed consecutively more than T times, a warning is issued to the technician. In this embodiment, T=5. In this case, further narrowing of the scanning interval width generally cannot meet the requirements for accurate calculation of gas concentration. Therefore, once the operation of narrowing the scanning interval width has been looped consecutively for T times, it is unnecessary to continue looping. At this time, a warning needs to be issued to the technician. The accuracy of measuring the gas under test in the current gas chamber is not high under this situation, and the only option is to consider changing the gas chamber.

[0044] It's important to note that while S1 and its sub-steps have broadened the scanning interval to a width that prevents waveform distortion in the shortest possible time, this width may not be optimal. An excessively wide scanning interval will result in an overly flat absorption range after convolution. This can lead to interference from high-frequency noise, affecting the accuracy of the absorption range determination and directly impacting the calculation of the analyte gas concentration. Therefore, S2 needs to narrow the broadened scanning interval from S1 to enhance the resolution of low-concentration signals, ensuring they are clearly and accurately displayed on the waveform. Similarly, when the analyte gas concentration is too low, while widening the scanning interval is unnecessary in S1, narrowing it directly in S2 may be necessary. Figure 4 clearly shows that the absorption range of the curve corresponding to the fourth scanning interval exhibits more pronounced fluctuations.

[0045] However, the narrowing of the scanning interval cannot be too narrow, otherwise the waveform curve may be distorted due to absorption saturation. Therefore, this application sets up steps 1 to 3. On the one hand, it is to ensure that the waveform curve is not distorted after each narrowing of the scanning interval. On the other hand, it is to effectively narrow the scanning interval width with as few loops as possible, so as to improve the efficiency of selecting a suitable scanning interval width. Furthermore, only when the width of the scanning interval is appropriate (neither too narrow nor too wide) can the waveform curve obtained after scanning the gas to be measured in the gas chamber with a laser whose wavelength changes continuously within this scanning interval (this waveform curve becomes the third reasonable curve after convolution processing) be able to accurately calculate the concentration of the gas to be measured.

[0046] In S2, the determination of whether the current second reasonable curve is the third reasonable curve is made by determining whether there are K3 consecutive sampling points in the absorption interval that are greater than the third set threshold. This can effectively avoid the influence of high-frequency noise pollution on the determination of the third reasonable curve.

[0047] S3 also includes the following: based on the third reasonable curve, obtain the absorption range and the sampling point information corresponding to the second convex point, as well as the normalized value of the detector output voltage; and after obtaining the scanning coefficient of the scanning range width corresponding to the third reasonable curve relative to the reference scanning range width, calculate the current concentration of the gas to be measured.

[0048] It should be noted that: by using the width of the reference scanning interval as a reference, the scanning coefficient of the scanning interval width corresponding to the third reasonable curve relative to the width of the reference scanning interval can be obtained. Furthermore, the concentration of the gas to be measured can be calculated based on the sampling point information corresponding to the absorption interval and the second convex point, the normalized value of the detector output voltage, and the scanning coefficient. This is an existing technology and will not be elaborated here.

[0049] The scanning coefficient is used for calibration during the calculation of the gas concentration. Because when the center wavelength remains constant, different scanning intervals with different widths will produce different waveforms (accompanied by the stretching or compression of the waveform). In order to ensure the accuracy of the final gas concentration calculation, we need to use the scanning coefficient for calibration in the calculation.

[0050] The absorption region needs to be used together with the second convex point to calculate the gas concentration. This is because the laser intensity changes as the laser is used for a longer period of time, which causes the position of the first convex point in the absorption region to drift. The second convex point contains the laser intensity information. Therefore, the absorption region and the second convex point are used together to calculate the gas concentration, which can effectively eliminate the adverse effects of laser intensity changes on the gas concentration calculation.

[0051] This application presents a gas concentration measurement method based on adaptive wavelength, which can efficiently and accurately measure the concentration of gas under different concentrations by adjusting the width of the scanning interval without replacing the gas chamber; it saves costs by eliminating the need to rebuild the gas chamber; and it is particularly suitable for remote telemetry scenarios such as environmental telemetry, industrial safety, and energy extraction.

[0052] The gas concentration measurement method of this application avoids the problem of absorption saturation caused by the fixed scanning range during TDLAS measurement, thus avoiding the problem of low measured concentration caused by waveform image distortion.

[0053] The gas concentration measurement method of this application can dynamically measure different concentrations of gas in the gas chamber and achieve continuous measurement from low to high concentrations because it can adaptively adjust the width of the scanning interval according to the gas to be measured.

[0054] In the process of widening the adaptive scanning interval, this application first widens the baseline scanning interval to ensure that the waveform image of the analyte gas with a high concentration will not be distorted after scanning; then, it narrows the widened scanning interval to ensure that the absorption range of the analyte gas can be clearly and accurately identified, and will not fail to be accurately identified due to the low concentration of the analyte gas. It is precisely because the scanning interval satisfies both of these constraints that the concentration of the analyte gas calculated from the waveform curve used in this application is sufficiently accurate and reliable.

[0055] The methods for widening and narrowing the scanning interval in this application ensure that the application does not need to rescan and verify the interval multiple times after widening or narrowing. Instead, it can quickly obtain a suitable interval width and find a suitable waveform curve to calculate the concentration of the gas to be measured in the shortest time, which greatly improves the calculation efficiency of the concentration of the gas to be measured.

[0056] This application also provides a gas concentration measurement system based on adaptive wavelength, including a TDLAS system, a first reasonable curve determination module, a convolution module, a third reasonable curve determination module, and a gas concentration calculation module. The TDLAS system uses a laser with a continuously varying wavelength within the scanning range to scan the gas to be measured in the gas chamber, obtaining a waveform curve of the gas absorption signal, which is then sent to the first reasonable curve determination module. The first reasonable curve determination module determines whether the current waveform curve is a first reasonable curve based on its distortion. If the current waveform curve is distorted, the first reasonable curve determination module widens the scanning range of the TDLAS system and rescans the gas to be measured until the first reasonable curve determination module determines the current waveform curve. When the first reasonable curve is obtained, it is sent to the convolution module. The convolution module processes the first reasonable curve into a second reasonable curve, which is then sent to the third reasonable curve determination module. The third reasonable curve determination module determines whether the current second reasonable curve is the third reasonable curve based on the absorption range of the second reasonable curve. If not, the third reasonable curve determination module narrows the scanning range of the current second reasonable curve, and then the TDLAS system rescans the gas to be measured based on the narrowed scanning range until the third reasonable curve determination module determines that the current second reasonable curve is the third reasonable curve. At this point, the third reasonable curve is sent to the gas concentration calculation module. The gas concentration calculation module calculates and calibrates the concentration of the gas to be measured based on the third reasonable curve.

[0057] Each module is programmed or configured to perform the steps of an adaptive wavelength-based gas concentration measurement method as described above.

[0058] This application also provides a computer-readable storage medium storing a computer program programmed or configured to perform a gas concentration measurement method based on an adaptive wavelength as described above.

[0059] This application also provides a computer program product, including a computer program / instructions that are executed by a processor to implement the steps of the above-described adaptive wavelength-based gas concentration measurement method.

[0060] The technologies, shapes, and structures not described in detail in this application are all well-known technologies. It should also be noted that the above are merely preferred embodiments of this application and are not intended to limit the scope of this application. The components or steps in the embodiments of this application can be decomposed and / or recombined, and these decompositions and / or recombinations should be considered as equivalent solutions of this application and should all fall within the protection scope of this application.

Claims

1. A gas concentration measurement method based on adaptive wavelength, characterized in that, The process includes the following steps: S1, scanning the gas to be tested in the gas chamber using a laser with a wavelength that continuously varies within the scanning range to obtain the waveform curve of the absorption signal of the gas to be tested; if the current waveform curve is distorted, the current scanning range is widened and the gas to be tested is scanned again until the latest waveform curve is free of distortion, and the latest waveform curve is recorded as the first reasonable curve and then S2 is executed; S2, the first reasonable curve is convolved to obtain the second reasonable curve, and the absorption range in which the laser is absorbed by the gas to be tested is obtained in the second reasonable curve; if there are K3 consecutive sampling points in the absorption range that are greater than a third set threshold, the current second reasonable curve is recorded as the third reasonable curve and then S3 is executed, otherwise the scanning range corresponding to the current second reasonable curve is narrowed and the gas to be tested is scanned again until the latest second reasonable curve can be recorded as the third reasonable curve and then S3 is executed; S3, the current concentration of the gas to be tested is calculated using the third reasonable curve.

2. The gas concentration measurement method based on adaptive wavelength according to claim 1, characterized in that, S1 includes the following sub-steps: S11, after determining the center wavelength of the laser used based on the composition of the gas to be measured, the scanning interval for the first laser scan is determined based on the center wavelength; the scanning interval for the first laser scan is recorded as the reference scanning interval; S12, after the gas to be measured in the gas chamber is scanned for the first time using a laser whose wavelength changes continuously within the reference scanning interval, the waveform curve of the absorption signal of the gas to be measured is obtained; if there are K1 consecutive sampling points exceeding the first set threshold and / or K2 consecutive sampling points less than the second set threshold in any sampling period of the current waveform curve, it is determined that the current waveform curve is distorted, then the current scanning interval is widened and the gas to be measured is scanned again until the latest waveform curve is free of distortion, the latest waveform curve is recorded as the first reasonable curve and then S2 is executed.

3. The gas concentration measurement method based on adaptive wavelength according to claim 2, characterized in that, In S12, the current scanning interval is widened to serve as the scanning interval for the next scan, including the following: continuous sampling points exceeding the first set threshold and continuous sampling points less than the second set threshold are all recorded as distorted sampling points; keeping the current center wavelength unchanged, if the proportion of distorted sampling points in any sampling period of the current waveform curve exceeds P1 of the total number of sampling points in one sampling period, then the current scanning interval is widened by M1 times to serve as the scanning interval for the next scan, otherwise the current scanning interval is widened by the set amount to serve as the scanning interval for the next scan.

4. The gas concentration measurement method based on adaptive wavelength according to claim 1, characterized in that, In S2, each sampling period of the second reasonable curve contains two peak points, which are denoted as the first convex point and the second convex point, respectively. The height of the first convex point is lower than the height of the second convex point. The scanning point interval formed by the first convex point and the K4 scanning points before and after it is denoted as the absorption interval where the laser is absorbed by the gas to be measured.

5. The gas concentration measurement method based on adaptive wavelength according to claim 1, characterized in that, In step S2, after narrowing the scanning interval corresponding to the current second reasonable curve, the gas to be tested is scanned again. This also includes the following steps: Step 1, the scanning interval width of the current second reasonable curve is recorded as the upper limit of the width, and the scanning interval width of the previous scan that obtained the current second reasonable curve is recorded as the lower limit of the width; Step 2, the average of the upper and lower limits of the width is taken as the width of the narrowed scanning interval, the center wavelength is kept unchanged, and the scanning interval of the next scan is obtained, and the gas to be tested is scanned again to obtain the latest waveform curve; Step 3, if the latest waveform curve has no distortion, the first reasonable curve is updated to the latest waveform curve and step S2 is executed again; if the latest waveform curve has distortion, the lower limit of the width is updated to the scanning interval width of the latest waveform curve and step 2 is returned.

6. The gas concentration measurement method based on adaptive wavelength according to claim 5, characterized in that: If the loop of steps 2 to 3 is executed consecutively more than T times, a warning will be issued to the technical staff.

7. The gas concentration measurement method based on adaptive wavelength according to claim 4, characterized in that, S3 includes the following: based on the third reasonable curve, obtain the absorption range and the sampling point information corresponding to the second convex point, as well as the normalized value of the detector output voltage; and after obtaining the scanning coefficient of the scanning range width corresponding to the third reasonable curve relative to the reference scanning range width, calculate the current concentration of the gas to be measured.

8. A gas concentration measurement system based on adaptive wavelength, characterized in that, include: The TDLAS system includes a first reasonable curve determination module, a convolution module, a third reasonable curve determination module, and a gas concentration calculation module. The TDLAS system uses a laser with a continuously varying wavelength within the scanning range to scan the gas in the gas chamber, obtaining a waveform curve of the gas absorption signal. This waveform curve is then sent to a first reasonable curve determination module. The first reasonable curve determination module determines whether the current waveform curve is a first reasonable curve based on its distortion. If the current waveform curve is distorted, the first reasonable curve determination module widens the scanning range of the TDLAS system and rescans the gas until it determines that the current waveform curve is a first reasonable curve. At this point, the first reasonable curve is sent to a convolution module. The convolution module processes the first reasonable curve into a second reasonable curve, which is then sent to a third reasonable curve determination module. The third reasonable curve determination module is used to determine whether the current second reasonable curve is the third reasonable curve based on the absorption range of the second reasonable curve. If not, the third reasonable curve determination module narrows the scanning range of the current second reasonable curve, and then the TDLAS system re-scans the gas to be measured based on the narrowed scanning range until the third reasonable curve determination module determines that the current second reasonable curve is the third reasonable curve. Then, the third reasonable curve is sent to the gas concentration calculation module. The gas concentration calculation module calculates and calibrates the concentration of the gas to be measured based on the third reasonable curve. Each module is programmed or configured to perform the steps of the gas concentration measurement method based on adaptive wavelength as described in any one of claims 1-7.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program that is programmed or configured to perform a gas concentration measurement method based on an adaptive wavelength as described in any one of claims 1-7.

10. A computer program product comprising a computer program / instructions, characterized in that: When the computer program / instructions are executed by the processor, they implement the steps of a gas concentration measurement method based on adaptive wavelength as described in any one of claims 1-7.

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