CN105319173B - Gas remote sensing device and method - Google Patents

Abstract

The invention provides a gas telemetering device and a method, wherein the gas telemetering device comprises: the wavelength of the measuring light emitted by the light source covers the absorption spectral lines of the gas to be measured and the gas in the gas pool; the beam splitting device is used for splitting the measuring light into a first light beam and a second light beam, and the first light beam penetrates through an area to be measured; the light deflection module is used for changing the traveling direction of the first light beam; a gas cell through which the second beam passes, the gas cell containing a known concentration of a gas; the first detector is used for converting the measuring light passing through the area to be measured into a first electric signal and transmitting the first electric signal to the processor; the second detector is used for converting the second light beam passing through the gas cell into a second electric signal and transmitting the second electric signal to the processor; the processor is used for adjusting the working parameters of the light source to ensure that the drift of the light source corresponding to the first electric signal does not exceed the standard; the device is used for adjusting the inclination angle of the light deflection module relative to the incident first light beam, so that the interference of the first light beam on the reflected light of the reflector in the region to be measured does not exceed the standard. The invention has the advantages of high precision, simple structure, low cost and the like.

Description

Gas remote sensing device and method

technical field

The invention relates to photoelectric analysis, in particular to a gas remote measurement device and method.

Background technique

Natural gas is a flammable and explosive gas, its main component is methane, and its explosion limit is 5%-16%. In recent years, explosion accidents caused by gas pipeline leakage have occurred frequently all over the country, posing a huge threat to the safety of residents' lives and property. For this reason, the gas company needs to conduct regular safety inspections and irregular spot checks on the leakage of natural gas users' indoor natural gas equipment.

The laser telemeter is currently a widely used device for remote detection of indoor natural gas leakage through windows. The telemeter adopts wavelength modulation spectroscopy (WMS) technology. The basic principle is: fix the laser frequency near a certain absorption peak of methane, and cosine the laser frequency Modulation, detection is performed according to the correlation between the frequency modulation harmonic signal and the gas concentration, so as to obtain the information of the gas to be measured on the optical path. This type of telemeter has many disadvantages, such as:

1. Since the center wavelength of the laser will drift with temperature, it will lead to errors in gas concentration measurement;

2. It cannot be used for the detection of indoor gases on each floor of the building. For indoor telemetry with windows, the existing technology cannot determine the distance from the glass window to the wall, that is, the gas content in the room cannot be obtained;

For the detection of indoor gas above the second floor of the building, the existing telemeter is powerless;

3. Due to the barrier of the glass, the incident laser beam will generate reflected beam 1 and reflected beam 2 on both sides of the window glass, and the reflected beams will form interference on the detector, which greatly reduces the detection accuracy of the characteristic absorption peak of the gas.

Contents of the invention

In order to solve the shortcomings in the above-mentioned prior art solutions, the present invention provides a gas remote measurement device with high precision, low cost, wide application fields and strong functions.

The purpose of the present invention is achieved through the following technical solutions:

A gas telemetry device, the gas telemetry device comprising:

Light source, the wavelength of the measurement light emitted by the only light source covers the absorption line of the gas to be measured and the gas whose concentration in the gas cell is known;

a beam splitting device, the beam splitting device is used to split the measurement light into a first beam and a second beam, and the first beam passes through the region to be measured;

a light deflection module, the light deflection module is used to change the traveling direction of the first light beam;

a gas cell through which the second light beam passes, the gas cell containing a gas of known concentration;

a first detector, the first detector is used to convert the first light beam passing through the area to be measured into a first electrical signal, and transmit it to the processor;

a second detector for converting a second light beam passing through the gas cell into a second electrical signal and transmitting it to a processor;

A processor, the processor is used to adjust the working parameters of the light source so that the drift of the light source corresponding to the second electrical signal does not exceed the standard; it is used to adjust the inclination angle of the light deflection module relative to the incident first light beam, so that The interference between the reflected light of the first light beam corresponding to the first electrical signal on the reflector in the region to be measured does not exceed the standard.

According to the above gas remote measurement device, optionally, the gas remote measurement device further includes:

An unmanned aerial vehicle, the light source, the first and second detectors, the light deflection module, and the gas pool are installed on the unmanned aerial vehicle.

According to the above-mentioned gas telemetry device, optionally, the light deflection module further includes:

a wedge-shaped transmission device, the wedge-shaped transmission device is fixed on one side of the connector, and the first light beam passes through the wedge-shaped transmission device;

A connecting piece, at least two distance adjusters are fixed on the other side of the connecting piece;

At least two distance adjusters, the length of which is adjustable, are used to adjust the degree of inclination of the connecting member relative to the first light beam.

According to the above gas remote measurement device, preferably, the distance adjuster is made of piezoelectric material.

According to the above gas remote measurement device, preferably, the light source is a laser.

According to the above gas remote measurement device, optionally, the gas to be measured and the gas with known concentration are the same or different gases.

The object of the present invention is also to provide a gas telemetry method with high precision, wide application fields and powerful functions, and the object of the invention is realized through the following technical solutions:

A gas telemetry method, the gas telemetry method comprising the following steps:

(A1) The measuring light emitted by the light source is divided into a first beam and a second beam, and the wavelength of the measuring light covers the absorption line of the gas to be measured and the gas whose concentration is known;

(A2) The first light beam passes through the light deflection module, and then enters the area to be measured, and the first detector converts the first light beam absorbed by the gas to be measured into a first electrical signal, and transmits it to the processor;

The second light beam passes through the gas with known concentration, and the second detector converts the emitted second light beam into a second electrical signal and transmits it to the processor;

(A3) The processor obtains the drift of the light source according to the second electrical signal, and if the drift exceeds the standard, adjusts the working parameters of the light source, and enters step (A1); if it does not exceed the standard, enters step (A4);

The processor obtains the interference signal between the reflected light of the first light beam on the reflector in the area to be measured according to the first electrical signal, and if the interference exceeds the limit, adjusts the inclination angle of the light deflection module relative to the incident first light beam , go to step (A1); if not exceed the standard, go to step (A4);

(A4) The processor processes the first electrical signal according to a spectroscopic technique, so as to obtain the content of the gas to be measured.

According to the gas telemetry method above, optionally, in step (A4), the processor selects direct absorption spectroscopy or wavelength modulation absorption spectroscopy to process the first electrical signal.

According to the above-mentioned gas telemetry method, optionally, the adjustment mode of the light deflection module is:

Adjusting the length of at least two distance regulators installed on one side of the connecting piece, so that the inclination of the wedge-shaped transmission device installed on the other side of the connecting piece relative to the measurement light changes, thereby adjusting the transmission of the measurement light through the wedge-shaped The deflection angle behind the device.

According to the above gas remote measurement method, preferably, the distance adjuster is made of piezoelectric material.

According to the above-mentioned gas remote measurement method, preferably, in step (A2), if the interference exceeds a threshold value, the voltage value applied to the distance regulator is adjusted.

Compared with prior art, the beneficial effect that the present invention has is:

1. By setting the feedback optical path, the output wavelength of the laser is locked at the central wavelength of the absorption peak of the gas to be measured, so as to avoid wavelength drift and make the measurement results more accurate;

Real-time monitoring of the interference between the reflected beams of the measuring light on the window glass. When the noise generated by the interference exceeds the threshold, the incident angle of the first beam on the window glass is adjusted by adjusting the deflection degree of the first beam to avoid interference. , that is, to ensure the detection accuracy;

2. It has two working modes of scanning wavelength direct absorption (scanning DA) and wavelength modulation spectroscopy (WMS). The measurement accuracy is high, and the measurement concentration range is large.

3. Wide range of applications and safety

The optical system is installed on the UAV, and the UAV flies to different heights, so as to measure the indoor gas content in different floors through telemetry, which expands the application field; the inspection personnel do not need to enter the room, ensuring the safety of the inspection personnel;

4. Powerful function

The measured content information can be sent to the owner's communication terminal in real time, so that the indoor gas content can be known even outside the home, and natural gas leakage information can be detected early to eliminate potential safety hazards.

Description of drawings

The disclosure of the present invention will become more comprehensible with reference to the accompanying drawings. Those skilled in the art can easily understand that these drawings are only used to illustrate the technical solution of the present invention, and are not intended to limit the protection scope of the present invention. In the picture:

Fig. 1 is a basic structural diagram of a gas telemetry device according to an embodiment of the present invention;

Fig. 2 is a basic structural diagram of an optical deflection module according to Embodiment 2 of the present invention.

Detailed ways

1-2 and the following description describe alternative embodiments of the invention to teach those skilled in the art how to implement and reproduce the invention. In order to teach the technical solutions of the present invention, some conventional aspects have been simplified or omitted. It should be understood by those skilled in the art that modifications or substitutions from these embodiments will be within the scope of the present invention. Those skilled in the art will appreciate that the features described below can be combined in various ways to form multiple variations of the invention. As such, the invention is not limited to the alternative embodiments described below, but only by the claims and their equivalents.

Example 1:

Fig. 1 schematically provides the basic structural diagram of the gas telemetry device of the embodiment of the present invention, as shown in Fig. 1, described gas telemetry device comprises:

A light source, such as a laser, the wavelength of the measurement light emitted by the only light source covers the absorption line of the gas to be measured, such as methane, and a gas with a known concentration in the gas cell;

A beam-splitting device, such as a half-mirror, is coated with a reflective film on a part of the incident surface of the converging lens, and the beam-splitting device is used to split the measuring light into a first beam and a second beam, the the first light beam passes through the area to be measured;

A light deflection module, such as a transmissive device with a wedge angle between the light incident surface and the light exit surface, the light deflection module is used to change the traveling direction of the first light beam;

a gas cell through which the second light beam passes, the gas cell containing a gas of known concentration, such as a test gas or a surrogate gas of known concentration;

a first detector, the first detector is used to convert the first light beam passing through the area to be measured into a first electrical signal, and transmit it to the processor;

a second detector for converting a second light beam passing through the gas cell into a second electrical signal and transmitting it to a processor;

A processor, the processor is used to adjust the working parameters of the light source, so that the wavelength of the output of the light source corresponding to the second electrical signal does not exceed the standard drift; it is used to adjust the inclination of the light deflection module relative to the incident first light beam angle, so that the interference between the reflected light of the first light beam corresponding to the first electrical signal on the reflector in the area to be measured does not exceed the limit.

In order to detect the content of indoor gases on different floors, further, the gas telemetry device further includes:

An unmanned aerial vehicle, such as a multi-rotor unmanned aerial vehicle, the light source, the first and second detectors, the light deflection module, and the gas pool are installed on the unmanned aerial vehicle, and the unmanned aerial vehicle flies to different floor heights to detect different The gas content in the floor room.

In order to reduce the load capacity of the UAV to improve the endurance of the UAV, further, the processor is arranged in the monitoring room or in the monitoring vehicle; the first and second detectors wirelessly output the electrical signal sent to the processor.

The gas remote measurement method of the embodiment of the present invention, that is, the working process of the above-mentioned gas remote measurement device, the gas remote measurement method includes the following steps:

(A1) The measuring light emitted by the light source is divided into a first beam and a second beam, and the wavelength of the measuring light covers the absorption line of the gas to be measured and the gas whose concentration is known;

(A2) The first light beam passes through the light deflection module, and then enters the area to be measured, and the first detector converts the first light beam absorbed by the gas to be measured into a first electrical signal, and transmits it to the processor;

The second light beam passes through the gas with known concentration, and the second detector converts the emitted second light beam into a second electrical signal and transmits it to the processor;

(A3) The processor obtains the drift of the output wavelength of the light source according to the second electrical signal, if the drift exceeds the standard, then adjust the working parameters of the light source, and enter step (A1); if it does not exceed the standard, enter step (A4) ;

The processor obtains the interference signal between the reflected light of the first light beam on the reflector in the area to be measured according to the first electrical signal, and if the interference exceeds a threshold, adjusts the inclination of the light deflection module relative to the incident first light beam Angle, enter step (A1); if the threshold is not exceeded, enter step (A4);

(A4) The processor processes the first electrical signal according to a spectroscopic technique, so as to obtain the content of the gas to be measured.

In order to expand the detection range of the gas concentration, optionally, in step (A4), the processor selects direct absorption spectroscopy (to deal with high-concentration gas to be measured) or wavelength-modulated absorption spectroscopy (to process low-concentration gas to be tested) to process the first electrical signal.

In order to detect the content of indoor gas on different floors, further, the drone carries the light source, detector, light deflection module, and gas pool to fly outside, and the light emitted by the light source enters the room.

In order to reduce the loading capacity of the UAV to improve the endurance of the UAV, further, the processor is arranged in the monitoring room or in the monitoring vehicle; the detector transmits the output electric signal to the processing unit by wireless device.

In order to allow the owner to grasp the indoor safety situation and discover safety hazards such as natural gas leakage early, further, the gas remote measurement method further includes the following steps:

(A5) If the content C of the gas to be measured is not zero and shows an increasing trend, an alarm will be prompted and the content information will be sent to the owner's communication terminal.

Example 2:

An application example of the gas remote measurement device and method according to Embodiment 1 of the present invention in the detection of natural gas leakage in rooms on each floor of a residential building.

In this application example, the only light source uses a DFB laser, and the wavelength of the measured light includes 1651nm (corresponding to the absorption line of methane); the output wavelength is modulated by adjusting the driving current and operating temperature of the laser; the beam splitter adopts half Transmissive mirror; use converging lens to collect the light reflected by windows and walls, and the converging light is received by the first detector; the gas pool is sealed with a known concentration of methane; drones use DJI drones; lasers, Detectors and light deflection modules, gas pools, and processors are all installed on the UAV.

Fig. 2 schematically shows the basic structural diagram of the light deflection module according to the embodiment of the present invention. As shown in Fig. 2, the light deflection module includes:

A wedge-shaped transmission device 11 with a wedge angle between the light incident surface and the light exit surface is fixed on one side of the connector 21, and the first light beam passes through the wedge-shaped transmission device; at least two distance adjustment devices are fixed on the other side of the connector. Devices 31, 32; the length of at least two distance regulators (using piezoelectric material) is adjustable, and the length of the regulator is changed by adjusting the voltage applied to the distance regulator, thereby adjusting the connecting member relative to the first light beam The degree of inclination is to adjust the incident angle of the first light beam relative to the light incident surface of the wedge-shaped transmission device.

During operation of the telemetry device:

(B1) The drone carries the light source, detector, light deflection module, gas pool and processor to fly outdoors;

Positioning step: It is necessary to adjust the position of the drone, and take a template image at a suitable detection position outside the window on the first floor of the building and store it;

The drone climbs to a certain height, which is approximately equal to the floor height of a building. The height of climb can be controlled by GPS, or an approximate height estimated by the operator. After the drone hovers, the camera it carries takes an image, and the software extracts the corner points of the windows on the image (the corner point extraction can use the Harris algorithm or other similar image feature extraction algorithms), and then compares it with the corner points of the windows on the template image. If the position of the corner point in the image and the mutual angle and distance are basically consistent with the template (three comparison thresholds can be set, when the position, angle and distance are all less than the given threshold, it is considered consistent), then match If successful, it means that the positioning is successful, and the telemetry step is entered. If the above information is quite different, it means that the positioning fails.

If the positioning fails, try to rotate the drone or the camera carried by a certain angle, take an image again, and match it with the template image according to the above matching method. If the matching is successful, it means that the positioning is successful, and enter the telemetry step.

If you still fail to adjust the attitude of the drone and the camera, you need to adjust the height of the drone, rise or fall a certain distance, and then repeat the above steps until the positioning is successful;

(A1) The measurement light emitted by the laser is divided into a first beam and a second beam, the wavelength of the measurement light covers the absorption line of methane;

(A2) The first light beam passes through the light deflection module, then passes through the window glass and enters the room, and the first detector converts the first light beam absorbed by the methane in the room and then reflected into a first electrical signal, and transmits it to the processor;

The second light beam passes through the methane with known concentration in the gas pool, and the second detector converts the emitted second light beam into a second electrical signal and transmits it to the processor;

(A3) The processor processes the second electrical signal to obtain the deviation between the wavelength corresponding to the methane absorption line and the methane absorption line when the ratio of the intensity of the methane absorption second harmonic signal to the intensity of the first harmonic signal is the maximum (in methane At the absorption line of the methane absorption line, the ratio of the intensity of the second harmonic signal absorbed by methane to the intensity of the first harmonic signal is the largest, which is pre-stored in the processor), that is, the drift of the output wavelength of the light source is obtained, if the drift If the standard is exceeded, adjust the working parameters of the light source, such as the laser operating temperature or operating current, and enter step (A1); if not exceed the standard, enter step (A4);

The processor obtains the interference signal between the reflected light of the first light beam on the window glass according to the first electrical signal, if the interference exceeds the standard, adjusts the inclination angle of the light deflection module relative to the incident first light beam, and enters the step ( A1); if not exceeding the standard, enter step (A4);

(A4) The processor selects direct absorption spectroscopy technology (for processing high-concentration methane) or wavelength-modulated absorption spectroscopy technology (for processing low-concentration methane) to process the first electrical signal, thereby obtaining the indoor methane content;

(A5) If the content C of methane is not zero and shows an increasing trend, an alarm will be prompted and the content information will be sent to the owner's communication terminal.

Example 3:

According to the application example of the gas remote measurement device and method in embodiment 1 of the present invention in the detection of natural gas leakage in rooms on each floor of a residential building, the difference from embodiment 2 is:

1. The gas cell and the second detector are integrated together. There is a substitute gas sealed in the gas cell. The absorption lines of the substitute gas and methane are both within the output wavelength scanning range of the laser. Gas, the ratio of the intensity of the second harmonic signal absorbed by the gas to the intensity of the first harmonic signal is the maximum at the absorption line of the substitute gas, and the maximum value is pre-stored in the processor; in the telemetry process, by analyzing the first The second electrical signal output by the second detector, the deviation between the corresponding wavelength and the absorption line of the substitute gas when the ratio of the intensity of the second harmonic signal absorbed by the substitute gas to the intensity of the first harmonic signal is the maximum is obtained, that is, A shift in the output wavelength of the light source is derived.

2. Coating a reflective film on a partial area of the incident surface of the light converging lens, so that the measurement light incident on this area is reflected, so that the measurement light is divided into the first light beam passing through the light converging lens and the second light beam reflected by the reflective film. Two beams.

3. The processor is installed in the monitoring vehicle, and communicates wirelessly with the driver module of the laser and the detector.

The above-mentioned embodiment has only given the situation of detecting methane in the indoor air as an example, of course it can also be other gases, such as benzene series, formaldehyde, coal gas and other toxic, harmful gases and flammable and explosive gases. For those skilled in the art, the specific implementation manners of these gas detections can be obtained on the basis of the above-mentioned embodiments without any creativity.

Claims (8)

1. The gas telemetry device in the room is characterized in that: the gas telemetry device includes: Light source, the wavelength of the measurement light emitted by the only light source covers the absorption line of the gas to be measured and the gas whose concentration in the gas cell is known; a beam splitting device, the beam splitting device is used to split the measurement light into a first beam and a second beam, and the first beam passes through the region to be measured; A light deflection module, the light deflection module is used to change the traveling direction of the first light beam; the light deflection module includes: a wedge-shaped transmission device, the wedge-shaped transmission device is fixed on one side of the connector, and the first light beam passes through the wedge-shaped transmission device; A connecting piece, at least two distance adjusters are fixed on the other side of the connecting piece; at least two distance adjusters, the length of the at least two distance adjusters is adjustable, and is used to adjust the degree of inclination of the connecting member relative to the first light beam; a gas cell through which the second light beam passes, the gas cell containing a gas of known concentration; a first detector, the first detector is used to convert the first light beam passing through the area to be measured into a first electrical signal, and transmit it to the processor; a second detector for converting a second light beam passing through the gas cell into a second electrical signal and transmitting it to a processor; A processor, the processor processes the second electrical signal to obtain the wavelength corresponding to when the ratio of the intensity of the second harmonic signal absorbed by the gas in the gas cell to the intensity of the first harmonic signal is the maximum, and then obtains the The deviation between the wavelength and the absorption line of the gas in the gas cell, if the deviation exceeds the standard, the processor is used to adjust the working parameters of the light source so that the drift of the light source corresponding to the second electrical signal does not exceed the standard; The processor is used to adjust the inclination angle of the light deflection module relative to the incident first light beam, so that the interference between the reflected light of the first light beam corresponding to the first electrical signal on the reflector in the area to be measured does not exceed the standard, and the reflected The body is the window glass. 2. The gas remote measurement device according to claim 1, characterized in that: the gas remote measurement device further comprises: An unmanned aerial vehicle, the light source, the first and second detectors, the light deflection module, and the gas pool are installed on the unmanned aerial vehicle. 3. The gas remote measurement device according to claim 1, characterized in that the distance adjuster is made of piezoelectric material. 4. The gas remote measurement device according to claim 1, characterized in that: the gas with known concentration and the gas to be measured are the same or different gases. 5. The gas remote measurement device according to claim 1, wherein the light source is a laser. 6. A gas telemetry method in a room, the gas telemetry method comprising the following steps: (A1) The measuring light emitted by the light source is divided into a first beam and a second beam, and the wavelength of the measuring light covers the absorption line of the gas to be measured and the gas whose concentration is known; (A2) The first light beam passes through the light deflection module, and then enters the area to be measured, and the first detector converts the first light beam absorbed by the gas to be measured into a first electrical signal, and transmits it to the processor; The second light beam passes through the gas with known concentration, and the second detector converts the emitted second light beam into a second electrical signal and transmits it to the processor; (A3) The processor obtains the drift of the light source according to the second electrical signal, if the drift exceeds the standard, then adjust the working parameters of the light source, and enter step (A1); if it does not exceed the standard, enter step (A4); The drift is obtained in the following manner: the processor processes the second electrical signal, and obtains that when the ratio of the intensity of the second harmonic signal absorbed by the gas with known concentration to the intensity of the first harmonic signal is the maximum The corresponding wavelength, and then obtain the deviation between the wavelength and the absorption line of the gas whose concentration is known; The processor obtains the interference signal between the reflected light of the first light beam on the reflector in the area to be measured according to the first electrical signal, and if the interference exceeds the limit, adjusts the inclination angle of the light deflection module relative to the incident first light beam , enter step (A1); if not exceeding the standard, enter step (A4); the reflector is window glass; the adjustment method of the light deflection module is: Adjusting the lengths of at least two distance adjusters installed on one side of the connecting piece, so that the inclination of the wedge-shaped transmission device installed on the other side of the connecting piece relative to the measurement light changes, thereby adjusting the first beam to pass through the wedge-shaped deflection angle after transmission device; (A4) The processor processes the first electrical signal according to a spectroscopic technique, so as to obtain the content of the gas to be measured. 7. The gas remote measurement method according to claim 6, characterized in that: in step (A4), the processor selects direct absorption spectroscopy or wavelength modulation absorption spectroscopy to process the first electrical signal. 8. The gas remote measurement method according to claim 6, characterized in that the distance adjuster is made of piezoelectric material.