Equipment for detecting methane content, carbon dioxide content and relative density of natural gas

Abstract

The utility model discloses equipment for detecting methane content, carbon dioxide content and relative density of natural gas. The equipment comprises a microprocessor, a laser controller, a semiconductor laser, a collimating lens and an electronic valve, the output end of the microprocessor is fixedly connected with a laser controller and a photoelectric signal processing collector, the output end of the laser controller is fixedly connected with a thermoelectric refrigeration sheet, the outer wall of one side of the thermoelectric refrigeration sheet is fixedly connected with a semiconductor laser, the output end of the semiconductor laser is provided with a collimating lens, and the output end of the collimating lens is sleeved with a gas chamber; the output end of the photoelectric signal processing collector is fixedly connected with an infrared detector, and the output end of the infrared detector is fixedly connected with an optical attenuation piece. According to the utility model, the simple detection device main body is designed, the gas source is pollution-free and reusable in the detection process, and the equipment is free of consumables, easy to operate and low in cost; and meanwhile, an outlet gas detection device is designed to detect gas discharged by the device.

Description

Technical Field

[0001] The utility model relates to the technical field of air detection, in particular to a device for detecting the content and relative density of methane and carbon dioxide in natural gas. Background Art

[0002] Carbon dioxide is a colorless and odorless or colorless and odorless gas at room temperature and pressure, and its aqueous solution has a slightly sour taste. It is also a common greenhouse gas. Carbon dioxide can generally be produced by high-temperature calcination of limestone or by the reaction of limestone and dilute hydrochloric acid. It is mainly used in refrigerating perishable foods, as a refrigerant, making carbonized soft drinks and as a solvent for homogeneous reactions. Low concentrations of carbon dioxide are non-toxic, but high concentrations of carbon dioxide can cause animal poisoning. Natural gas is mainly composed of methane (85%) and a small amount of ethane (9%), propane (3%), nitrogen (2%) and butane (1%). It is mainly used as fuel and is also used to make acetaldehyde, acetylene, ammonia, carbon black, and ethanol. , formaldehyde, hydrocarbon fuels, hydrogenated oil, methanol, nitric acid, synthesis gas and vinyl chloride and other chemicals raw materials. Natural gas is compressed into liquid for storage and transportation. Coal miners, nitric acid manufacturers, power plant workers, organic chemical synthesizers, gas users, petroleum refiners, etc. have the opportunity to come into contact with this product. It mainly enters the human body through the respiratory tract. It is a simple asphyxiating gas. When the concentration is high, it causes hypoxia due to air replacement, leading to shortness of breath and loss of consciousness. In severe cases, people may suffocate to death due to low blood oxygen. High-pressure natural gas can cause frostbite, and incomplete combustion can produce carbon monoxide. Therefore, the detection of methane, carbon dioxide content and relative density of natural gas has been ongoing.

[0003] However, traditional natural gas methane, carbon dioxide content and relative density detection equipment cannot meet people's needs, and it has the following defects: First, there is no simple detection device designed. Traditional gas detection requires the use of a large number of lasers and different gas chambers for detection, which consumes a lot of resources. The detection process is relatively cumbersome and time-consuming, and has certain requirements on the operation of the detection personnel, so that the detection efficiency does not meet people's needs; second, there is no outlet gas detection device designed, and there is no corresponding detection for the gas discharged by the device. If there is an abnormality in the device, it cannot be detected whether the discharged gas is harmful, and the health of the operator cannot be guaranteed. Utility Model Content

[0004] The purpose of the utility model is to provide a device for detecting the content of methane and carbon dioxide and the relative density of natural gas, so as to solve the problems raised in the above background technology.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions: a device for detecting the methane, carbon dioxide content and relative density of natural gas, including a microprocessor, the output end of the microprocessor is fixedly connected to a laser controller and a photoelectric signal processing collector, the output end of the laser controller is fixedly connected to a thermoelectric cooling plate, a semiconductor laser is fixedly connected to one side outer wall of the thermoelectric cooling plate, the output end of the semiconductor laser is a collimating lens, the output end of the collimating lens is sleeved with an air chamber, the output end of the photoelectric signal processing collector is fixedly connected to an infrared detector, the output end of the infrared detector is fixedly connected to an optical attenuation plate, and the optical attenuation plate is sleeved on one side outer wall of the air chamber.

[0006] As a further technical solution of the present invention, a sample gas inlet is fixedly connected to the upper surface of the air chamber, a pressure sensor is fixedly connected to the outer wall on one side of the sample gas inlet, and the pressure sensor is fixedly connected to the upper surface of the air chamber, a temperature sensor is fixedly connected to the outer wall on one side of the pressure sensor, and the temperature sensor is fixedly connected to the upper surface of the air chamber.

[0007] As a further technical solution of the present invention, a sample gas outlet is fixedly connected to the lower surface of the gas chamber, a gas detector is fixedly connected to the outer wall on one side of the sample gas outlet, and the gas detector is fixedly connected to the lower surface of the gas chamber, and the output end of the gas detector is fixedly connected to a connecting circuit.

[0008] As a further technical solution of the present invention, one end of the connecting circuit is fixedly connected to a gas alarm controller, and the gas alarm controller is fixedly connected to an outer wall of one side of the gas chamber, and the output end of the gas alarm controller is fixedly connected to an alarm light.

[0009] As a further technical solution of the present invention, a concave reflector is fixedly connected to an outer wall of one side of the air chamber, and a microphone is sleeved on the lower surface of the air chamber.

[0010] As a further technical solution of the present invention, a bracket is fixedly connected to an outer wall of one side of the air chamber.

[0011] As a further technical solution of the present invention, an electronic valve is fixedly connected to an outer wall on one side of the sample gas outlet.

[0012] Compared with the existing technology, the beneficial effects achieved by the present invention are: the present invention is designed with a simple detection device body, uses a single laser with a single gas chamber to simultaneously detect methane concentration, carbon dioxide concentration and relative density, reduces the resources required for detection, and the detection process is relatively simple, reducing the time required for detection. The detection process does not pollute the gas source and can be reused, the equipment has no consumables, is easy to operate, and has low cost; at the same time, an outlet gas detection device is designed to detect the gas discharged from the device to determine whether the discharged gas meets the standard. In the event of an abnormality in the device, it can accurately determine whether the gas is harmful and issue an alarm to ensure the health of the operator. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0014] Figure 1 This is a schematic diagram of the overall three-dimensional structure of the utility model;

[0015] Figure 2 This is a schematic diagram of the overall front structure of the utility model;

[0016] Figure 3 This is a schematic diagram of the overall rear view structure of the utility model;

[0017] Figure 4 This is a schematic diagram of the overall structure of the utility model when viewed from above;

[0018] Figure 5 It is a schematic diagram of the overall three-dimensional cutaway structure of the utility model.

[0019] In the figure: 1. Microprocessor; 2. Laser controller; 3. Photoelectric signal processing and acquisition device; 4. Thermoelectric cooling plate; 5. Semiconductor laser; 6. Collimating lens; 7. Temperature sensor; 8. Sample gas inlet; 9. Gas chamber; 10. Concave reflector; 11. Microphone; 12. Sample gas outlet; 13. Optical attenuation plate; 14. Infrared detector; 15. Pressure sensor; 16. Bracket; 17. Gas detector; 18. Connection circuit; 19. Gas alarm controller; 20. Alarm light; 21. Electronic valve. DETAILED DESCRIPTION

[0020] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] Please see the attached Figure 1 -Attached Figure 5 The present invention provides an embodiment of a device for detecting the methane and carbon dioxide content and relative density of natural gas, comprising a microprocessor 1, wherein the output end of the microprocessor 1 is fixedly connected to a laser controller 2 and a photoelectric signal processing collector 3, the output end of the laser controller 2 is fixedly connected to a thermoelectric cooling plate 4, a semiconductor laser 5 is fixedly connected to the outer wall of one side of the thermoelectric cooling plate 4, the output end of the semiconductor laser 5 is connected to a collimating lens 6, the output end of the collimating lens 6 is sleeved with an air chamber 9, the output end of the photoelectric signal processing collector 3 is fixedly connected to an infrared detector The output end of the infrared detector 14 is fixedly connected to an optical attenuation sheet 13, and the optical attenuation sheet 13 is sleeved on one side of the outer wall of the air chamber 9; the upper surface of the air chamber 9 is fixedly connected to a sample gas inlet 8, and a pressure sensor 15 is fixedly connected to one side of the outer wall of the sample gas inlet 8, and the pressure sensor 15 is fixedly connected to the upper surface of the air chamber 9. The outer wall of one side of the pressure sensor 15 is fixedly connected to a temperature sensor 7, and the temperature sensor 7 is fixedly connected to the upper surface of the air chamber 9. The pressure sensor 15 and the temperature sensor 7 are respectively used to measure the gas to be measured in the air chamber 9 The pressure and temperature of the gas sample outlet 12 are fixedly connected to monitor the working status of the equipment in real time; the lower surface of the gas chamber 9 is fixedly connected to a sample gas outlet 12, and a gas detector 17 is fixedly connected to the outer wall of one side of the sample gas outlet 12, and the gas detector 17 is fixedly connected to the lower surface of the gas chamber 9, and the output end of the gas detector 17 is fixedly connected to a connecting circuit 18, and the gas detector 17 is used to monitor the state of the gas discharged from the sample gas outlet 12 to see whether it meets the emission standards; one end of the connecting circuit 18 is fixedly connected to a gas alarm controller 19, and the gas alarm controller 19 is fixedly connected to one end of the gas chamber 9. On the side outer wall, the output end of the gas alarm controller 19 is fixedly connected to an alarm light 20, which sounds an alarm to promptly remind the operator to adjust the device; a concave reflector 10 is fixedly connected to the outer wall of one side of the gas chamber 9, and a microphone 11 is sleeved on the lower surface of the gas chamber 9, and the microphone 11 is used to collect the sound wave signal generated when the gas vibrates; a bracket 16 is fixedly connected to the outer wall of one side of the gas chamber 9, and the bracket 16 is used to fix the device body; an electronic valve 21 is fixedly connected to the outer wall of one side of the sample gas outlet 12, and the electronic valve 21 is used to close the sample gas outlet 12.

[0022] Working principle: When using the utility model for gas detection, in order to solve the problems of slow response and complex detection system in the existing natural gas multi-component content and relative density measurement, the utility model provides a method for real-time online detection of methane content, CO2 content and natural gas relative density using only a single laser while maintaining high-precision measurement. The method, procedure and equipment are convenient and flexible to operate, highly automated and intelligent, easy to use, with a wide range of applications, high application value, low cost and easy to popularize and promote. The utility model provides a laser detection system for natural gas methane, carbon dioxide content and relative density, which consists of a laser emitting device, a detection gas chamber 9, a sound signal and light signal receiving and processing device and a signal analysis module. Composition: First, the required detection gas is allowed to enter the gas chamber 9 through the sample gas inlet 8. The detection gas chamber 9 is a stainless steel cylindrical sealed gas chamber 9 with a diameter of about 80 mm and a length of about 200 mm. It is used to store the gas to be tested, so that the laser can interact with the gas to be tested in the gas chamber 9. The gas is processed by the concave reflector 10 in the gas chamber 9. The concave reflector 10 can reflect the laser, increase the distance at which the laser interacts with the gas to be tested in the gas chamber 9, and thus allow more gas molecules to absorb the laser, increase the vibration signal of the gas molecules after being excited, and facilitate signal acquisition. The parameters of the device are set by the microprocessor 1, and a stable laser emission signal with modulation is generated by the laser emitting device composed of the laser controller 2 and the semiconductor laser 5. The conductor laser 5 and the long optical path detection chamber 9 can effectively enhance the intensity of the sound signal, increase the sensitivity and accuracy of the equipment detection, and act on the gas in the chamber 9 through the collimating lens 6. The heat generated by the laser controller 2 and the semiconductor laser 5 during operation is absorbed by the thermoelectric cooling plate 4 to achieve the purpose of cooling. The signal receiving device composed of the microphone 11 and the processing circuit collects the sound wave signal generated when the gas vibrates, and the photoelectric signal processing collector 3 receives the collected data. The optical attenuation plate 13 attenuates the high-power laser energy value to a linear region acceptable to the rear-end detector, thereby increasing the service life of the equipment. The infrared detector 14 detects the energy of the emitted laser absorbed by the gas and the attenuated energy, and detects the component to be measured, carbon dioxide. The content of gas is measured by the pressure sensor 15 and the temperature sensor 7 near the sample gas inlet 8, respectively, which are used to measure the pressure and temperature of the gas to be measured in the gas chamber 9. The working status of the equipment is monitored in real time. The status of the gas discharged from the sample gas outlet 12 is monitored by the gas detector 17 to see whether the emission standards are met. If the requirements are not met, an alarm can be issued through the connection circuit 18, the gas alarm controller 19 and the alarm light 20 to promptly remind the operator to adjust the device and close the sample gas outlet 12 through the electronic valve 21. The utility model is based on the absorption spectrum theory of gas molecules. When a laser of a specific wavelength acts on the gas, since each gas molecule has a unique structure and motion law, the gas molecule will absorb light energy to achieve energy level transition, from the ground state to the excited state;The wavelength of a DFB laser varies linearly with the injected current. By varying the laser's drive current, the laser wavelength can be swept across the absorption spectrum of the gas to be measured. Further processing of the emitted light intensity signal yields the direct absorption signal of the gas to be measured. Combined with the Lambert-Beer law, the concentration of carbon dioxide can be determined. After absorbing light energy and transitioning to a higher energy level, the excited molecules quickly return to their ground state via a non-radiative transition. During this process, the molecules release heat energy, causing the gas to expand. Periodically modulating the laser also causes the gas to expand periodically, generating acoustic waves. According to photoacoustic spectroscopy theory, the intensity of the photoacoustic signal is proportional to the absorbance of the gas to be measured, provided the laser power and photoacoustic cell constant remain constant.

[0023]

[0024] Where A is the vibration amplitude of the photoacoustic signal, is the laser modulation frequency, is the total absorbance of the sample gas, P is the laser power, and F is the photoacoustic cell constant. The laser bands we selected are mainly 1312~1317, 1320~1325, 1430~1435, 1435~1440, 1635~1640, 1645~1650, and 1652~1657. The selected scanning range includes both methane absorption and carbon dioxide absorption. Therefore, the photoacoustic signal intensity we received is the result of the co-production and superposition of methane and carbon dioxide. According to the direct absorption spectroscopy method, the concentration of carbon dioxide components can be easily obtained. The methane concentration can be obtained by equivalently deducting the photoacoustic signal intensity generated by the known concentration of carbon dioxide from the photoacoustic signal intensity. In the gas, sound waves are transmitted as longitudinal waves, and the sound speed formula is:

[0025]

[0026] Where c is the speed of sound, c p is the specific heat of natural gas at constant pressure, Z is the natural gas compressibility factor, R = 8314.472 MJ / kmol, T is the gas temperature, c v is the constant volume specific heat of natural gas, and M is the gas molecular weight; when the gas type does not change significantly, the sound speed can be considered to be proportional to the square root of the medium density. By measuring the time from the start of laser modulation to the ability to directionally capture the sound signal at the modulation frequency, the density of the medium can be accurately calculated; wherein the bracket 16 is used to fix the device body.

[0027] In the description of this utility model, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections; direct connections, indirect connections through an intermediate medium, and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on the specific circumstances.

[0028] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, i.e., they may be located in one location or distributed across multiple network units. Some or all of the modules may be selected based on actual needs to achieve the objectives of the present embodiment. Persons of ordinary skill in the art will be able to understand and implement the present invention without inventive effort.

[0029] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A device for detecting the content and relative density of methane and carbon dioxide in natural gas, comprising a microprocessor (1), characterized in that: The output end of the microprocessor (1) is electrically connected to a laser controller (2) and a photoelectric signal processing collector (3); the output end of the laser controller (2) is fixedly connected to a thermoelectric cooling plate (4); a semiconductor laser (5) is fixedly connected to an outer wall of one side of the thermoelectric cooling plate (4); a collimating lens (6) is provided at the output end of the semiconductor laser (5); an air chamber (9) is sleeved on the output end of the collimating lens (6); an infrared detector (14) is fixedly connected to the output end of the photoelectric signal processing collector (3); an optical attenuation plate (13) is fixedly connected to the outer wall of one side of the air chamber (9).

2. The device for detecting the methane and carbon dioxide content and relative density of natural gas according to claim 1, characterized in that: The upper surface of the gas chamber (9) is fixedly connected to a sample gas inlet (8); a pressure sensor (15) is fixedly connected to an outer wall of one side of the sample gas inlet (8); and the pressure sensor (15) is fixedly connected to the upper surface of the gas chamber (9); a temperature sensor (7) is fixedly connected to an outer wall of one side of the pressure sensor (15); and the temperature sensor (7) is fixedly connected to the upper surface of the gas chamber (9).

3. The device for detecting the methane and carbon dioxide content and relative density of natural gas according to claim 2, characterized in that: The lower surface of the gas chamber (9) is fixedly connected to a sample gas outlet (12), a gas detector (17) is fixedly connected to an outer wall of one side of the sample gas outlet (12), and the gas detector (17) is fixedly connected to the lower surface of the gas chamber (9), and an output end of the gas detector (17) is fixedly connected to a connection circuit (18).

4. The device for detecting the methane and carbon dioxide content and relative density of natural gas according to claim 3, characterized in that: One end of the connecting circuit (18) is fixedly connected to a gas alarm controller (19), and the gas alarm controller (19) is fixedly connected to an outer wall of one side of the gas chamber (9), and an output end of the gas alarm controller (19) is fixedly connected to an alarm light (20).

5. The device for detecting the methane and carbon dioxide content and relative density of natural gas according to claim 3, characterized in that: A concave reflector (10) is fixedly connected to an outer wall of one side of the air chamber (9), and a microphone (11) is sleeved on the lower surface of the air chamber (9).

6. The device for detecting the methane and carbon dioxide content and relative density of natural gas according to claim 5, characterized in that: A bracket (16) is fixedly connected to one side outer wall of the air chamber (9).

7. The device for detecting the methane and carbon dioxide content and relative density of natural gas according to claim 3, characterized in that: An electronic valve (21) is fixedly connected to an outer wall of one side of the sample gas outlet (12).

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