A methane detection experiment device

Abstract

The present application relates to a kind of methane detection experimental device, including halogen tungsten lamp light source, narrow band filter and focusing lens are placed after light source, methane gas and nitrogen are respectively used flowmeter to control flow rate, inlet gas is connected to aluminum alloy gas chamber through "Y" type gas three-way pipe, two pieces of reflector are installed in aluminum alloy gas chamber, light hole after gas chamber is connected single photon avalanche diode detector, oscilloscope is connected after single photon avalanche diode detector and shows data, the present application simple structure, using single photon detection device improves detection sensitivity, using optical detection method, not by electromagnetic interference, using reflection type gas chamber structure, reduce the size of experimental device, improve detection precision.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of methane detection experimental device, belong to gas detection field. BACKGROUND

[0002] Most of the coal mines in China are gas mines, and the main component of gas is methane, which is a flammable and explosive gas. The explosion concentration range in air is 4.9% to 16%. Even if the methane concentration is not within the explosion range, high concentration of methane or long-term inhalation of low concentration of methane can be life-threatening. Methane is also a greenhouse gas, and its greenhouse effect is stronger than other greenhouse gases. High levels of methane in the atmosphere can have some impact on the environment and seriously undermine sustainable development strategies. Therefore, it is necessary to study methane detection devices with good stability and high sensitivity.

[0003] Currently, there are mainly the following types of methane detection devices: thermal conduction type, catalytic combustion type, optical detection type, etc. The existing invention patent with the patent name of "a miniature methane sensor and a methane detection method" with the publication number of CN109239137A is suitable for methane detection in coal mines. The device includes a heating element and multiple measurement elements. The heating element is heated to a high temperature working state alone, and the detection of methane is realized by using the different thermal conductivities of methane gas and air. The defect of the methane detection device of this method is that the device needs to be heated, and the detection sensitivity is not high enough.

[0004] Some people have used the catalytic combustion method to prepare a planar catalytic combustion type methane sensor on an anodic aluminum oxide film (E.K.Evgeny, F.K.Evgeny, A.S.Suchkova, et al. Energy efficient planar catalytic sensor for methane measurement [J]. Sensors and Actuators A; Physical, 2013, 194: 176-180.). The power consumption of this type of methane detection device is generally high, and it is suitable for detecting low concentration methane within the lower explosive limit.

[0005] Traditional methane detection devices made using optical detection principles are mostly based on incandescent lamp-filter-detector structures. These devices require a large amount of power from the light source and cannot overcome the interference of water vapor. The existing invention patent with the patent name of "a low-power methane detection device and method" with the publication number of CN111398203A proposes a methane detection device that uses an LED light source as a detection light, greatly reducing the power consumption of the device. However, the signal is very weak when detecting low concentration methane, and the device sensitivity is not high. SUMMARY

[0006] The technical problem to be solved by the present application is to provide a methane detection experimental device to solve the above-mentioned defects of the prior art.

[0007] The present application solves the technical problem by adopting the following technical scheme:

[0008] The methane detection experimental device comprises a halogen tungsten lamp light source, a narrow-band filter, a focusing lens, methane gas, high-purity nitrogen, a methane flowmeter, a nitrogen flowmeter, a gas flow display instrument, a Y-shaped gas tee, an aluminum alloy gas chamber, a reflector, a quartz glass sheet, a single-photon avalanche diode detector, a voltage stabilizing power supply and an oscilloscope.

[0009] The light inlet hole on the wall of the aluminum alloy gas chamber is arranged on the first gas chamber wall and is 15mm away from the second gas chamber wall in the horizontal direction and is at the center of the first gas chamber wall in the vertical direction.

[0010] The center wavelength of the narrow-band filter is 1650nm and the bandwidth is 12nm.

[0011] The active area of the detection end of the single-photon avalanche diode detector is 30μm in diameter, the dark count rate is less than 10kHz and the single-photon avalanche diode detector is provided with an optical fiber tail fiber.

[0012] The present application has the following beneficial effects:

[0013] (1) By adding single photon avalanche diode detector, the extremely weak detection light signal can be detected, the power consumption of light source is effectively reduced, and the methane detection sensitivity of experimental device is improved.

[0014] (2) By adding a mirror, the length of the interaction between methane gas and light is increased, and the overall size of the gas chamber is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 It is a structure schematic view of the methane detection experimental device of the application.

[0016] Figure 2 It is an internal view of the gas chamber.

[0017] Figure 3 It is a principle view of the internal light path of the gas chamber.

[0018] 1-halogen tungsten lamp light source, 2-narrow band filter, 3-focusing mirror, 4-aluminum alloy gas chamber, 5-gas outlet, 6-single photon avalanche diode detector, 7-Y type gas tee, 8-flow display instrument, 9-methane flow meter, 10-nitrogen flow meter, 11-methane gas, 12-high-purity nitrogen, 13-oscilloscope, 14-stabilized power supply, 15-mirror, 16-light inlet hole, 17-light outlet hole, 18-gas inlet, 19-first gas chamber wall, 20-second gas chamber wall, 21-third gas chamber wall, 22-fourth gas chamber wall DETAILED DESCRIPTION

[0019] As Figure 1The device structure schematic diagram of the application. Including halogen tungsten lamp light source 1, narrow band filter 2, focusing lens 3, methane gas 11, high purity nitrogen 12, methane flowmeter 9, nitrogen flowmeter 10, gas flow display instrument 8, "Y" type gas tee 7, aluminum alloy gas chamber 4, single photon avalanche diode detector 6, voltage stabilizing power supply 14, oscilloscope 13, the center wavelength of the narrow band filter 2 is 1650nm, the bandwidth is 12nm, the dark count rate of the single photon avalanche diode detector 6 is less than 10kHz, the active area diameter is 30μm, the narrow band filter 2 is placed behind the halogen tungsten lamp light source 1 and directly opposite the light source light outlet, the focusing lens 3 is placed behind the narrow band filter 2, the methane gas 11 is connected with the gas inlet end of the methane flowmeter 9, the high purity nitrogen 12 is connected with the gas inlet end of the nitrogen flowmeter 10, the control ports of the two flowmeters are connected with the gas flow display instrument 8, the gas outlet ends of the two flowmeters are connected with the two same side gas inlets of the "Y" type gas tee 7, the "Y" type gas tee 7 is connected with the aluminum alloy gas chamber 4, the detection end of the single photon avalanche diode detector 6 is connected with the aluminum alloy gas chamber 4, the voltage stabilizing power supply 14 is connected with the power supply pin of the single photon avalanche diode detector 6, and the oscilloscope 13 is connected behind the single photon avalanche diode detector 6.

[0020] As Figure 2 The gas chamber internal diagram of the application. Including reflector 15, light inlet hole 16, light outlet hole 17, gas inlet 18, gas outlet 5, first gas chamber wall 19, second gas chamber wall 20, third gas chamber wall 21, fourth gas chamber wall 22, the light inlet hole 16 is arranged on the first gas chamber wall 19 and the horizontal distance from the second gas chamber wall 20 is 15mm, the vertical direction is in the center of the first gas chamber wall 19, the light outlet hole 17 is arranged on the third gas chamber wall 21 and the horizontal distance from the fourth gas chamber wall 22 is 15mm, the vertical direction is in the center of the third gas chamber wall 21, the gas inlet 18 is arranged on the second gas chamber wall 20 and the horizontal distance from the first gas chamber wall 19 is 20mm, the vertical direction is in the center of the second gas chamber wall 20, the gas outlet 5 is arranged on the fourth gas chamber wall 22 and the horizontal distance from the third gas chamber wall 21 is 20mm, the vertical direction is in the center of the fourth gas chamber wall 22, the light inlet hole 16 and the light outlet hole 17 are circular holes with a diameter of 8mm, the gas inlet 18 and the gas outlet 5 are circular holes with a diameter of 12mm. The reflector 15 is installed on the first gas chamber wall 19 and the third gas chamber wall 21 and is close to the light inlet hole 16 and the light outlet hole 17.

[0021] As Figure 3 The gas chamber internal light path principle diagram of the application. The light incident into the gas chamber from the light inlet hole 16 will be reflected multiple times by the two reflectors 15 and finally emitted from the light outlet hole 17, which can increase the optical path.

[0022] As Figure 1 The experimental device diagram shown, the detection steps of the application are as follows:

[0023] S1: Adjust the light path, adjust the oscilloscope 13, adjust the zero gas flow display instrument 8, and test the dark count rate K0 of the single photon avalanche diode detector 6.

[0024] S2: Open the nitrogen flow meter 10, adjust the flow display instrument 8 to the maximum flow, close the methane flow meter 9, and pass nitrogen into the aluminum alloy gas chamber 4 for a period of time.

[0025] S3: Turn on the halogen tungsten lamp light source 1, and the emitted light with a wavelength range of 360-2500 nm passes through the narrow-band filter 2, the focusing lens 3, and then enters the aluminum alloy gas chamber 4. The emitted light is received by the single photon avalanche diode detector 6, and the signal is read out to the oscilloscope 13. The oscilloscope 13 shows the reference count rate (without methane) K1 at this time.

[0026] S4: Open the methane flow meter 9, control the concentration Ci of methane passed in each time by adjusting the flow ratio of methane to nitrogen displayed by the flow display instrument 8, repeat the S3 step, and the oscilloscope 13 displays the measurement count rate Ki under different methane concentrations.

[0027] S5: Compare the measurement count rate Ki recorded in the S4 step with the reference count rate K1 recorded in the S3 step, and obtain a series of relative count rates Kx.

[0028] S6: Obtain the curve relationship between the relative count rate Kx and the methane concentration Ci according to the above steps.

[0029] S7: Pass the methane gas to be tested into the methane detection experimental device of the embodiment of the application, and the single photon avalanche diode detector 6 detects and reads out, and the oscilloscope 13 displays the photon count rate at this time. Compare the count rate at this time with the reference count rate, and finally obtain the concentration of the methane to be tested according to the relationship between the relative count rate and the methane concentration.

Claims

1. A methane detection experimental apparatus, characterized in that: The system includes a halogen tungsten lamp light source, a narrowband filter, a focusing lens, methane gas, high-purity nitrogen gas, a methane flow meter, a nitrogen flow meter, a gas flow display, a "Y"-shaped gas tee, an aluminum alloy gas chamber, a reflector, a quartz glass plate, a single-photon avalanche diode detector, a regulated power supply, and an oscilloscope. The aluminum alloy gas chamber has a light inlet, a light outlet, an air inlet, an air outlet, and a sealed gas chamber cover on its four sides. The light inlet is located on the first gas chamber wall and is 15mm horizontally from the second gas chamber wall, and vertically... The light-emitting aperture is located at the center of the first gas chamber wall, 15mm horizontally from the fourth gas chamber wall and vertically at the center of the third gas chamber wall. The air inlet is located at the center of the second gas chamber wall, 20mm horizontally from the first gas chamber wall and vertically at the center of the second gas chamber wall. The air outlet is located at the center of the fourth gas chamber wall, 20mm horizontally from the third gas chamber wall and vertically at the center of the fourth gas chamber wall. The light-emitting and light-emitting apertures are 8mm diameter circular holes, and the air inlet and air outlet are 12mm diameter circular openings. Reflectors are installed on either side of the light-emitting and light-emitting apertures on the inner walls of the gas chambers. Quartz glass plates are installed at the light-emitting and light-emitting apertures on the inner walls of the gas chambers. A narrow-band filter is placed after the halogen tungsten lamp light source, directly facing the light-emitting port. A focusing lens is placed after the narrow-band filter and aligned with the light-emitting aperture of the aluminum alloy gas chamber. The narrow-band filter has a center wavelength of 1650nm and a bandwidth of 12nm, used to filter out stray light in parallel light while maintaining high transmittance to the halogen tungsten lamp light source. The methane gas and methane flow... The inlet of the flow meter is connected to the inlet of the high-purity nitrogen flow meter. The control ports of the two flow meters are connected to the gas flow display. The outlets of the two flow meters are connected to the two vents on the same side of the "Y"-shaped gas tee. The "Y"-shaped gas tee is connected to the inlet of the aluminum alloy gas chamber. The detection end of the single-photon avalanche diode detector is connected to the light outlet of the aluminum alloy gas chamber. The oscilloscope is connected to the output end of the single-photon avalanche diode detector. The regulated power supply is connected to the power supply pin of the single-photon avalanche diode detector.

2. The methane detection experimental apparatus according to claim 1, characterized in that: The single-photon avalanche diode detector has an active region with a diameter of 30 μm, a dark count rate of less than 10 kHz, and an optical fiber pigtail, and is used to detect weak single-photon level light signals and perform photoelectric signal conversion.

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