CN219799232U - Single-light-path self-compensating absorption spectrum methane detection system - Google Patents
Single-light-path self-compensating absorption spectrum methane detection system Download PDFInfo
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- CN219799232U CN219799232U CN202321162018.2U CN202321162018U CN219799232U CN 219799232 U CN219799232 U CN 219799232U CN 202321162018 U CN202321162018 U CN 202321162018U CN 219799232 U CN219799232 U CN 219799232U
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- 238000001514 detection method Methods 0.000 title claims abstract description 55
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 title claims abstract description 52
- 238000000862 absorption spectrum Methods 0.000 title claims abstract description 25
- 238000010521 absorption reaction Methods 0.000 claims abstract description 31
- 238000001914 filtration Methods 0.000 claims description 14
- 230000003287 optical effect Effects 0.000 claims description 12
- 238000006243 chemical reaction Methods 0.000 claims description 7
- 229910000530 Gallium indium arsenide Inorganic materials 0.000 claims description 3
- 230000005540 biological transmission Effects 0.000 abstract description 3
- 238000012937 correction Methods 0.000 abstract description 3
- 238000013461 design Methods 0.000 abstract description 3
- 239000007789 gas Substances 0.000 description 12
- 238000005516 engineering process Methods 0.000 description 6
- 238000004458 analytical method Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 230000004044 response Effects 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- 230000003595 spectral effect Effects 0.000 description 2
- 238000003860 storage Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
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- 238000009776 industrial production Methods 0.000 description 1
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- 230000004048 modification Effects 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 239000003345 natural gas Substances 0.000 description 1
- 238000010606 normalization Methods 0.000 description 1
- 239000013307 optical fiber Substances 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
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Abstract
The utility model relates to a single-light-path self-compensating absorption spectrum methane detection system, and belongs to the technical field of gas detection. The system comprises a signal generator, a laser driving and temperature controller, a DFB laser, an air chamber, a photoelectric detector, a band-pass filter, a low-pass filter and a singlechip, wherein the signal generator, the laser driving and temperature controller, the DFB laser, the air chamber and the photoelectric detector are sequentially connected, and the photoelectric detector is connected with the singlechip through the band-pass filter and the low-pass filter respectively. The signal generator can utilize sine wave to carry out low-frequency scanning, compared with triangular wave or sawtooth wave, the sine wave has very clear frequency component, can easily separate the scanning baseline from the absorption information, and utilizes the band-pass filter and the low-pass filter to acquire the absorption curve and the scanning baseline from the transmission signal, thereby realizing the design of a single-light path system, having compact structure and being capable of easily realizing power correction.
Description
Technical Field
The utility model relates to a single-light-path self-compensating absorption spectrum methane detection system, and belongs to the technical field of gas detection.
Background
In the production process in the fields of coal, petroleum, natural gas and the like, methane gas leakage can cause great influence on environment and safety production, and even cause fire and poisoning. To reduce such hazards, they should be accurately detected. Among the technologies, the tunable diode laser absorption spectrum technology has the advantages of good selectivity, high sensitivity, strong anti-interference capability and the like, wherein the direct absorption spectrum technology is widely applied to industrial production due to the simple system structure.
In a direct absorption spectrum gas sensing system, the most critical step in acquiring the concentration information of the target gas is to recover an absorption curve from a transmitted light signal, so that the intensity of incident light needs to be measured in advance, a differential absorption spectrum technology is generally adopted, a light source is split into a reference arm and a detection arm through a 1x2 optical fiber coupler, the reference arm and the detection arm are respectively used for detecting the reference signal and the detection signal, and then the absorption curve is acquired through a differential demodulation circuit.
The differential absorption spectrum technology suppresses common-mode interference by adding a reference signal, but is very sensitive to light power fluctuation, even if the light source slightly drifts, the balance of a differential circuit is destroyed, in order to avoid distortion of a demodulated absorption curve, a reference arm can be used for monitoring laser power fluctuation, and normalization of power drift is realized, so that influence of the power fluctuation on a light signal is eliminated, but the system is more complicated, the system cost is increased, and meanwhile, the differential absorption spectrum technology adopts triangular waves or sawtooth waves as low-frequency scanning signals, and abrupt changes of the triangular waves or the sawtooth waves can cause instantaneous changes of the light power, so that the working stability of a laser is influenced. For this purpose, the present utility model is proposed.
Disclosure of Invention
Aiming at the defects of the prior art, the utility model provides a single-light-path self-compensating absorption spectrum methane detection system, which utilizes a sine wave generated by a signal generator to carry out low-frequency scanning, and compared with a triangular wave or a sawtooth wave, the sine wave has very clear frequency components and can easily separate a scanning baseline from absorption information; meanwhile, a single light path design is adopted, an absorption curve and a scanning baseline are obtained from a transmission signal by utilizing a band-pass filter and a low-pass filter, and the system has a compact structure, can easily realize power correction, effectively improves the power fluctuation interference resistance of the system, simplifies the system structure and reduces the cost of the system.
The technical scheme of the utility model is as follows:
a single-light path self-compensating absorption spectrum methane detection system comprises a signal generator, a laser driving and temperature controller, a DFB laser, a gas chamber, a photoelectric detector, a band-pass filter, a low-pass filter and a singlechip,
the signal generator, the laser drive and temperature controller, the DFB laser, the air chamber and the photoelectric detector are connected in sequence, and the photoelectric detector is connected with the singlechip through the band-pass filter and the low-pass filter respectively;
the signal generator is used for sending out sine scanning signals, and the signals are transmitted to the laser driving and temperature controller;
the laser driving and temperature controller is used for controlling the driving current and the temperature of the DFB laser;
the DFB laser is used for generating laser, and the laser enters the air chamber for detection;
the photoelectric detector is used for carrying out photoelectric conversion on the transmitted light signal from the air chamber to obtain an original detection signal;
the band-pass filter is used for carrying out band-pass filtering on the original detection signal to obtain an absorption curve signal;
the low-pass filter is used for carrying out low-pass filtering on the original detection signal to obtain a scanning baseline signal;
the singlechip is used for collecting an absorption curve signal and a scanning baseline signal, and correcting the absorption curve signal by using the scanning baseline signal.
According to the utility model, the signal generator is a commercial FY6300 waveform generator module, and provides a 100-500 Hz sinusoidal scanning signal with a peak value of 0-3V.
According to the utility model, the laser driving and temperature controller is a commercial LDC501 controller and controls the driving current and temperature of the DFB laser.
According to the utility model, the DFB laser is preferably a SWLD-1653 type laser, the center wavelength is 1653.7nm, the spectral linewidth is 3MHz, the temperature tuning coefficient of the wavelength is 0.09 nm/DEG C, and the current tuning coefficient of the wavelength is 0.01nn/mA when the working temperature is 25 ℃, and the methane gas is detected by using the DFB laser.
According to the utility model, the air chamber is a JSXH-81030315 type air chamber, the optical path of the air chamber is 3m, a storage space for the air to be detected is provided for the detection system, and the air to be detected enters from the air inlet and is discharged from the air outlet.
According to the utility model, the photodetector is preferably an InGaAs PIN photodiode of LSIPD-A75, the wavelength response range is 800-1700nm, the responsivity is 0.90mA/mW, the saturated light power is 3.5mW, and the transmitted light signal from the air chamber is subjected to photoelectric conversion to obtain an original detection signal.
According to the utility model, the band-pass filter is preferably a UAF42 band-pass module, the passband range of which is 300Hz to 12kHz, and the band-pass filter is used for carrying out band-pass filtering on the original detection signal so as to obtain an absorption curve signal.
According to the utility model, the NE5532 module is used as the low-pass filter, the cut-off frequency of which is 120Hz, and the original detection signal is subjected to low-pass filtering to obtain a scanning baseline signal.
According to the utility model, the singlechip is an STM32F103 singlechip, the absorption curve signal and the scanning baseline signal are collected, the absorption curve signal is corrected by utilizing the scanning baseline signal, and then data is transmitted to the industrial personal computer for recording and subsequent analysis.
The working method of the single-light path self-compensating absorption spectrum methane detection system comprises the following steps:
the detection system is arranged in a region to be detected, methane gas enters the air chamber through the air inlet, a 100Hz sinusoidal scanning signal is generated by the signal generator and then is sent to the laser driving and temperature controller, the laser driving and temperature controller controls the driving current and the temperature of the DFB laser, the DFB laser generates laser to enter the air chamber for detection, the photoelectric detector performs photoelectric conversion on a transmitted light signal coming out of the air chamber to obtain an original detection signal, the band-pass filter performs band-pass filtering on the original detection signal to obtain an absorption curve signal, the low-pass filter performs low-pass filtering on the original detection signal to obtain a scanning baseline signal, the singlechip collects the absorption curve signal and the scanning baseline signal, corrects the absorption curve signal by using the scanning baseline signal, and then transmits data to the industrial personal computer for recording and subsequent analysis.
The utility model has the beneficial effects that:
1. the methane detection system of the utility model uses sine waves for low-frequency scanning, compared with triangular waves or saw-tooth waves, the sine waves have very clear frequency components, and the scanning base line can be easily separated from the absorption information.
2. In the utility model, a band-pass filter and a low-pass filter are utilized to acquire an absorption curve and a scanning baseline from a transmission signal, and the acquired scanning baseline is utilized to normalize the absorption curve, so that the design of a single-light path system is realized; the system has compact structure, can easily realize power correction, effectively improves the power fluctuation interference resistance of the system, simplifies the system structure and reduces the cost of the system.
Drawings
FIG. 1 is a single optical path self-compensating absorption spectrum methane detection system provided in the present utility model;
FIG. 2 is a schematic circuit diagram of the present utility model;
the device comprises a signal generator 1, a laser driving and temperature controller 2, a DFB laser 3, a DFB laser 4, an air chamber 5, a photoelectric detector 6, a band-pass filter 7, a low-pass filter 8 and a singlechip;
4-1 parts of air inlet, 4-2 parts of air outlet.
Detailed Description
The utility model will now be further illustrated by way of example, but not by way of limitation, with reference to the accompanying drawings.
Example 1:
as shown in fig. 1-2, the embodiment provides a single-optical-path self-compensating absorption spectrum methane detection system, which comprises a signal generator 1, a laser driving and temperature controller 2, a DFB laser 3, an air chamber 4, a photoelectric detector 5, a band-pass filter 6, a low-pass filter 7 and a singlechip 8, wherein,
the signal generator 1, the laser drive and temperature controller 2, the DFB laser 3, the air chamber 4 and the photoelectric detector 5 are sequentially connected, and the photoelectric detector 5 is connected with the singlechip 8 through the band-pass filter 6 and the low-pass filter 7 respectively.
The signal generator 1 is used for sending sine scanning signals, and the signals are transmitted to the laser driving and temperature controller;
the laser driving and temperature controller 2 is used for controlling the driving current and the temperature of the DFB laser;
the DFB laser 3 is used for generating laser, and the laser enters the air chamber 4 for detection;
the photoelectric detector 5 is used for performing photoelectric conversion on the transmitted light signal coming out of the air chamber to obtain an original detection signal;
the band-pass filter 6 is used for carrying out band-pass filtering on the original detection signal to obtain an absorption curve signal;
the low-pass filter 7 is used for carrying out low-pass filtering on the original detection signal to obtain a scanning baseline signal;
the singlechip 8 is used for collecting an absorption curve signal and a scanning baseline signal, and correcting the absorption curve signal by using the scanning baseline signal.
The signal generator 1 is a commercial FY6300 waveform generator module and provides a sinusoidal scanning signal of 100-500 Hz with a peak value of 0-3V.
The laser driving and temperature controller 2 is a commercial LDC501 controller, and controls the driving current and temperature of the DFB laser.
The DFB laser 3 is a SWLD-1653 laser, when the working temperature is 25 ℃, the central wavelength is 1653.7nm, the spectral linewidth is 3MHz, the temperature tuning coefficient of the wavelength is 0.09 nm/DEG C, the current tuning coefficient of the wavelength is 0.01nn/mA, and the methane gas is detected by using the DFB laser.
The air chamber 4 is a JSXH-81030315 type air chamber, the optical path is 3m, a storage space for the gas to be detected is provided for the detection system, the gas to be detected enters from the air inlet 4-1, and the gas to be detected is discharged from the air outlet 4-2.
The photodetector 5 uses an InGaAs PIN photodiode of LSIPD-A75, the wavelength response range is 800-1700nm, the responsivity is 0.90mA/mW, the saturated optical power is 3.5mW, and the transmitted optical signal from the air chamber is subjected to photoelectric conversion to obtain an original detection signal.
The band-pass filter 6 selects a UAF42 band-pass module, the band-pass range of which is 300Hz to 12kHz, and carries out band-pass filtering on the original detection signal so as to obtain an absorption curve signal.
The low-pass filter 7 selects an NE5532 module, the cut-off frequency of which is 120Hz, and performs low-pass filtering on the original detection signal to obtain a scanning baseline signal.
The singlechip 8 is an STM32F103 type singlechip, acquires the absorption curve signal and the scanning baseline signal, corrects the absorption curve signal by utilizing the scanning baseline signal, and then transmits data to the industrial personal computer for recording and subsequent analysis.
The pin 1 of the signal generator is connected with the pin 2 of the laser driving and temperature controller, the pin 2 of the signal generator is connected with the pin 1 of the laser driving and temperature controller, the pin 3, the pin 4, the pin 5 and the pin 6 of the laser driving and temperature controller are respectively correspondingly connected with the pin 14, the pin 13, the pin 11 and the pin 10 of the DFB laser, the pin 7, the pin 8 and the pin 9 of the laser driving and temperature controller are respectively correspondingly connected with the pin 5, the pin 2 and the pin 1 of the DFB laser, the laser emission ports PD+ and PD-emitted laser of the DFB laser enter the air chamber, and the laser is transmitted in the air chamber and is physically transmitted, so that the air chamber is not shown in the circuit diagram of fig. 2, the photoelectric detector receives transmitted light signals from the air chamber, the pin 6 and the pin 7 of the photoelectric detector are connected with the pin 3 of the band-pass filter, the pin 8 of the band-pass filter is connected with the pin 20 of the singlechip, the pin 8 and the pin 9 of the photoelectric detector are connected with the resistor 60 of the low-pass filter, and the pin 7 of the low-pass filter is connected with the pin 43 of the singlechip.
The working method of the single-light path self-compensating absorption spectrum methane detection system comprises the following steps:
the detection system is arranged in a region to be detected, methane gas enters the air chamber through the air inlet, a 100Hz sinusoidal scanning signal is generated by the signal generator and then is sent to the laser driving and temperature controller, the laser driving and temperature controller controls the driving current and the temperature of the DFB laser, the DFB laser generates laser to enter the air chamber for detection, the photoelectric detector performs photoelectric conversion on a transmitted light signal coming out of the air chamber to obtain an original detection signal, the band-pass filter performs band-pass filtering on the original detection signal to obtain an absorption curve signal, the low-pass filter performs low-pass filtering on the original detection signal to obtain a scanning baseline signal, the singlechip collects the absorption curve signal and the scanning baseline signal, corrects the absorption curve signal by using the scanning baseline signal, and then transmits data to the industrial personal computer for recording and subsequent analysis.
The foregoing is merely illustrative of specific embodiments of the present utility model, and the scope of the utility model is not limited thereto, but any modifications, equivalents, improvements and alternatives falling within the spirit and principles of the present utility model will be apparent to those skilled in the art within the scope of the present utility model.
Claims (9)
1. A single-light path self-compensating absorption spectrum methane detection system is characterized by comprising a signal generator, a laser driving and temperature controller, a DFB laser, an air chamber, a photoelectric detector, a band-pass filter, a low-pass filter and a singlechip,
the signal generator, the laser drive and temperature controller, the DFB laser, the air chamber and the photoelectric detector are connected in sequence, and the photoelectric detector is connected with the singlechip through the band-pass filter and the low-pass filter respectively;
the signal generator is used for sending out sine scanning signals, and the signals are transmitted to the laser driving and temperature controller;
the laser driving and temperature controller is used for controlling the driving current and the temperature of the DFB laser;
the DFB laser is used for generating laser, and the laser enters the air chamber for detection;
the photoelectric detector is used for carrying out photoelectric conversion on the transmitted light signal from the air chamber to obtain an original detection signal;
the band-pass filter is used for carrying out band-pass filtering on the original detection signal to obtain an absorption curve signal;
the low-pass filter is used for carrying out low-pass filtering on the original detection signal to obtain a scanning baseline signal;
the singlechip is used for collecting an absorption curve signal and a scanning baseline signal, and correcting the absorption curve signal by using the scanning baseline signal.
2. The single optical path self-compensating absorption spectrum methane detection system of claim 1, wherein the signal generator is a commercial FY6300 waveform generator module.
3. The single optical path self-compensating absorption spectrum methane detection system of claim 1, wherein the laser driver and temperature controller is a commercial LDC501 controller.
4. The single optical path self-compensating absorption spectrum methane detection system of claim 1, wherein the DFB laser is a SWLD-1653 type laser.
5. The single-optical-path self-compensating absorption spectrum methane detection system of claim 1, wherein the air chamber is a JSXH-81030315 type air chamber.
6. The single optical path self-compensating absorption spectrum methane detection system of claim 1, wherein the photodetector is an InGaAs PIN photodiode of LSIPD-a 75.
7. The single optical path self-compensating absorption spectrum methane detection system of claim 1, wherein the bandpass filter is a UAF42 bandpass module.
8. The single optical path self-compensating absorption spectrum methane detection system of claim 1, wherein the low pass filter is a NE5532 module.
9. The single optical path self-compensating absorption spectrum methane detection system as claimed in claim 1, wherein the singlechip is an STM32F103 type singlechip.
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| CN202321162018.2U CN219799232U (en) | 2023-05-15 | 2023-05-15 | Single-light-path self-compensating absorption spectrum methane detection system |
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