CN110865121A - Device and method for detecting hydrogen concentration in multi-component mixed gas - Google Patents

Abstract

The invention designs a device and a method for detecting the hydrogen concentration in a multi-component mixed gas, wherein an ultrasonic transmitting module and a receiving module are arranged in an acoustic gas chamber, 2 openings are arranged on the acoustic gas chamber, one opening is a gas inlet and is connected with a gas distribution module, the other opening is a gas outlet and is connected with a pressure control module, the pressure control module is used for adjusting the pressure in the acoustic gas chamber, the pressure value range is 1 kPa-100 kPa, and the frequency-pressure ratio, namely the equivalent frequency range of sound waves, can be changed through the adjustment of the pressure. The receiving module receives the ultrasonic waves and measures the pulse transmission time in the acoustic air chamber, and the signal processing module processes the ultrasonic waves to obtain the propagation velocity of the ultrasonic waves. The invention realizes the detection of the hydrogen concentration by detecting parameters such as sound velocity, sound attenuation, environmental temperature, pressure and the like in the gas, has low cost, high precision and high repeatability, and does not generate contact reaction with the gas to be detected.

Description

Detection device and detection method of hydrogen concentration in multi-component mixed gas

technical field

The invention belongs to the technical field of hydrogen concentration detection, and in particular relates to a detection device and a detection method for hydrogen concentration in a multi-component mixed gas.

Background technique

As a clean energy material with high efficiency, no pollution and sustainable development strategy, hydrogen is a new energy with great potential to solve the current energy crisis. Together with solar energy and wind energy, it is called nine new energy sources. It is used in many fields such as automobile, chemical industry, metallurgy, aerospace, cryogenic cooling and electronic industry. Hydrogen can be used as a characteristic detection gas. For low-concentration hydrogen detection, it can be used for early warning and diagnosis of power transformers, which can effectively prevent hydrogen embrittlement in the process of metal smelting, and can also be used for safety detection of nuclear waste. Hydrogen energy has many advantages, but it also has many hidden dangers. Hydrogen is a colorless, odorless, flammable and explosive gas with a very small molecular weight and is prone to leakage. When the hydrogen content in the air reaches more than 4%, a strong explosion is very likely to occur. Therefore, low-concentration hydrogen detection is of great significance for the safe and effective use of the advantages of hydrogen energy. At present, the commonly used hydrogen sensors on the market include optical hydrogen sensors, electrochemical hydrogen sensors, electrical hydrogen sensors, acoustic hydrogen sensors, etc., and the phase difference type hydrogen sensor in the acoustic sensor, due to its low cost, high accuracy and strong repeatability, is not comparable to The gas has a contact reaction, which is more advantageous.

There are still many problems and deficiencies in the practical application of the phase difference type hydrogen sensor, such as being easily affected by ambient temperature and humidity. The calculation results show that every 0.1 degree Celsius temperature deviation will cause a hydrogen concentration measurement error of 250ppm. Among the existing gas acoustic sensors, the Chinese invention patent CN201521130425 realizes the detection of the hydrogen concentration by detecting the change of the resonant frequency in the gas cavity caused by the change of the sound speed, and cannot be used for the hydrogen detection in the multi-component gas. The structure proposed by the Chinese invention patent CN201510426316 uses a hydrogen sensitive resistor, which has a contact reaction with the gas to be measured, and has a limited service life. The structure proposed by the American invention US4457161 does not use the sound velocity detection module, and is not used for hydrogen detection.

The ultrasonic gas sensors of existing literature and inventions basically use the detection of the propagation speed of ultrasonic waves in the gas cavity to realize the detection of the hydrogen concentration in the binary mixed gas. Due to the limitation of the ultrasonic pulse detection accuracy, the accuracy is difficult to improve. There is a lack of effective temperature compensation methods and devices.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a detection device and detection method for hydrogen concentration in a multi-component mixed gas, which can detect the hydrogen concentration by detecting parameters such as sound speed, sound attenuation, ambient temperature and pressure in the gas, and the cost is low. High precision, high repeatability, no contact reaction with the gas to be measured.

The technical scheme adopted by the present invention to solve the technical problem is as follows: first, a detection device for hydrogen concentration in a multi-component mixed gas is provided, which includes an acoustic gas chamber, a pressure control module, an ultrasonic transmitting module, a receiving module and a signal processing module, and an ultrasonic transmitting module . The receiving module is set in the acoustic air chamber, and two openings are set on the acoustic air chamber, one of which is the air inlet, which is connected to the air distribution module, and the other is the air outlet, which is connected to the pressure control module. The pressure control module is used for The pressure adjustment in the acoustic air chamber, the pressure value ranges from 1kPa to 100kPa, and the frequency-pressure ratio can be changed through the adjustment of the pressure, that is, the equivalent frequency range of the sound wave can be changed. The receiving module receives the ultrasonic wave and measures the pulse transmission time in the acoustic air chamber, and the signal processing module processes it to obtain the propagation speed of the ultrasonic wave. According to the corresponding relationship between the gas concentration and the sound speed, the corresponding concentration of each component gas in the mixed gas is calculated to realize the detection of the hydrogen concentration in the binary mixed gas. The acoustic air chamber is integrated with the ultrasonic transmitter module and receiver module on a single PCB, which can maximize space saving and facilitate miniaturized applications and packaging.

According to the above technical solution, the receiving module is also used to receive the ultrasonic wave and obtain the frequency spectrum of its amplitude in the acoustic air chamber, and the signal processing module processes it to obtain the acoustic attenuation value of the ultrasonic wave. Thereby, the detection of the hydrogen concentration in the ternary mixed gas is realized.

According to the above technical scheme, the receiving module includes an amplifier circuit, a filter circuit, a zero-crossing comparison circuit, and a shaping circuit. The acoustic wave signal passing through the acoustic air chamber is converted into a sinusoidal signal after passing through these circuits, and the ultrasonic wave is obtained by reading the peak value change of the sinusoidal signal. The attenuation of the ultrasonic wave in the acoustic air chamber is obtained by reading the count value of the timer.

According to the above technical scheme, the ultrasonic transmitting module is controlled by STM32 to transmit 8 square wave signals from the CPLD, and after processing, it becomes a sine wave to drive the ultrasonic transducer to transmit. The ultrasonic transducer converts the sound pressure signal into a voltage signal. The frequency of the ultrasonic transducer is 300kHz, and its divergence angle is small and the directionality is good. In the hydrogen detection system, the rubber pipe and the gas chamber interface are sealed and fixed.

According to the above technical solution, a timer is also included to record the time of the ultrasonic wave from the ultrasonic transmitting module to the receiving module. The output end of the timer is connected to the receiving module. 5cm-8cm, there are two openings on the side of the acoustic air chamber. 2XZ-4 vacuum pump can be used. Keep the pressure in the acoustic air chamber below 10kPa. The connection between the outlet of the acoustic air chamber and the vacuum pump is controlled by a valve. The attenuation of the ultrasonic wave can be obtained by reading the peak-to-peak change of the sinusoidal signal, and the transmission time of the ultrasonic wave in the air chamber can be obtained by reading the count value of the timer.

According to the above technical solution, a temperature sensor is also included, which is arranged in the acoustic gas chamber, and the collected temperature signal is transmitted to the signal processing system, and the influence of temperature drift on the hydrogen concentration measurement value is eliminated through a linear compensation algorithm. Added a temperature sensor that operates from -40 to 85°C with a resolution of 0.001°C. Model can choose MS5611.

The present invention also provides a method for detecting the concentration of hydrogen in a multi-component mixed gas based on claim 1. The method includes the following steps. In step 1, the air inlet of the acoustic air chamber is connected to the air distribution module for air intake. The air outlet is connected to the pressure control module, and the pressure control module is used to adjust the pressure in the acoustic air chamber to keep the pressure value in the range of 1kPa to 100kPa; step 2, the ultrasonic transmitter module transmits ultrasonic waves in the acoustic air chamber; step 3, the receiving module Receive the pulse transmission time of the ultrasonic wave in the acoustic gas chamber, and the signal processing module processes it to obtain the propagation speed of the ultrasonic wave; step 4, according to the corresponding relationship between the gas concentration and the sound speed, calculate the corresponding concentration of each component gas in the mixed gas to achieve Detection of hydrogen concentration in binary mixed gas.

According to the above technical solution, the following step 5 is also included: the receiving module receives the ultrasonic wave and obtains the frequency spectrum of its amplitude propagating in the acoustic air chamber, and the signal processing module processes it to obtain the acoustic attenuation value of the ultrasonic wave, and realizes the ternary mixed gas. Detection of hydrogen concentration.

According to the above technical scheme, the receiving module includes an amplifier circuit, a filter circuit, a zero-crossing comparison circuit, and a shaping circuit. The acoustic wave signal passing through the acoustic air chamber is converted into a sinusoidal signal after passing through these circuits, and the ultrasonic wave is obtained by reading the peak value change of the sinusoidal signal. The attenuation of the ultrasonic wave in the acoustic air chamber is obtained by reading the count value of the timer. The ultrasonic transmitting module (CPLD controlled by STM32) transmits 8 square wave signals, which become sine waves after processing to drive the ultrasonic transducer to transmit. . The ultrasonic transducer converts the sound pressure signal into a voltage signal. The frequency of the ultrasonic transducer is 300kHz, and its divergence angle is small and the directionality is good. In the hydrogen detection system, the rubber pipe and the gas chamber interface are sealed and fixed.

According to the above technical solution, a timer is also included to record the time of the ultrasonic wave from the ultrasonic transmitting module to the receiving module. The output end of the timer is connected to the receiving module. 5cm-8cm, there are two openings on the side of the acoustic air chamber, and a 2XZ-4 vacuum pump can be used. The pressure in the acoustic air chamber is achieved below 10kPa. The connection between the outlet of the acoustic air chamber and the vacuum pump is controlled by a valve. The attenuation of the ultrasonic wave can be obtained by reading the peak-to-peak value of the sinusoidal signal, and the transmission time of the ultrasonic wave in the air chamber can be obtained by reading the count value of the timer. It also includes a temperature sensor, which is arranged in the acoustic gas chamber, and the temperature signal collected by it is transmitted to the signal processing system, and the influence of temperature drift on the hydrogen concentration value is eliminated through a linear compensation algorithm. Added a temperature sensor that operates from -40 to 85°C with a resolution of 0.001°C. Model can choose MS5611.

The beneficial effects of the invention are: hydrogen concentration detection is realized by detecting parameters such as sound velocity, sound attenuation, ambient temperature and pressure in the gas, the cost is low, the precision is high, the repeatability is high, and there is no contact reaction with the gas to be measured. .

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings and embodiments, in which:

1 is a schematic structural diagram of a detection device for hydrogen concentration in a multi-component mixed gas according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of hydrogen detection and adjustment according to an embodiment of the present invention.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.

In the embodiment of the present invention, in view of the problems of contact reaction, limited gas types and accuracy that can be detected in the existing hydrogen detection technology, a low-cost and high-precision method is provided, which can realize the hydrogen concentration detection in mixed gas and has the advantages of low cost and high accuracy. The hydrogen detection system with temperature compensation function, as shown in Figure 1, first provides a detection device for hydrogen concentration in a multi-component mixed gas, including an acoustic gas chamber, a pressure control module, an ultrasonic transmitter module, a receiver module and a signal processing module. The module and the receiving module are set in the acoustic air chamber, and two openings are set on the acoustic air chamber, one of which is the air inlet, which is connected to the air distribution module, and the other is the air outlet, which is connected to the pressure control module, which is used for the pressure control module. In the pressure adjustment in the acoustic air chamber, the pressure value ranges from 1kPa to 100kPa, and the frequency-pressure ratio can be changed through the adjustment of the pressure, that is, the equivalent frequency range of the sound wave can be changed. The receiving module receives the ultrasonic wave and measures the pulse transmission time in the acoustic air chamber, and the signal processing module processes it to obtain the propagation speed of the ultrasonic wave. According to the corresponding relationship between the gas concentration and the sound speed, the corresponding concentration of each component gas in the mixed gas is calculated to realize the detection of the hydrogen concentration in the binary mixed gas. The acoustic air chamber is integrated with the ultrasonic transmitter module and receiver module on a single PCB, which can maximize space saving and facilitate miniaturized applications and packaging.

The receiving module is also used to receive the ultrasonic wave and obtain the frequency spectrum of the amplitude in the acoustic air chamber, and the signal processing module processes it to obtain the acoustic attenuation value of the ultrasonic wave. Thereby, the detection of the hydrogen concentration in the ternary mixed gas is realized. The receiving module includes an amplifier circuit, a filter circuit, a zero-crossing comparison circuit, and a shaping circuit. The sound wave signal passing through the acoustic air chamber is converted into a sinusoidal signal after passing through these circuits, and the attenuation of the ultrasonic wave is obtained by reading the peak value change of the sinusoidal signal. Take the count value of the timer to get the transmission time of the ultrasonic wave in the acoustic air chamber.

The ultrasonic transmitter module is controlled by STM32 to transmit 8 square wave signals from the CPLD, and after processing, it becomes a sine wave to drive the ultrasonic transducer to transmit. The ultrasonic transducer converts the sound pressure signal into a voltage signal. The frequency of the ultrasonic transducer is 300kHz, and its divergence angle is small and the directionality is good. In the hydrogen detection system, the rubber pipe and the gas chamber interface are sealed and fixed. It also includes a timer to record the time of ultrasonic waves from the ultrasonic transmitting module to the receiving module. The output end of the timer is connected to the receiving module. The pressure control module is a vacuum pump. ), there are two 2mm holes on the side of the acoustic air chamber. 2XZ-4 vacuum pump can be used to make the pressure in the acoustic air chamber below 10kPa. The connection between the outlet of the acoustic air chamber and the vacuum pump is controlled by a valve. The attenuation of the ultrasonic wave can be obtained by reading the peak-to-peak change of the sinusoidal signal, and the transmission time of the ultrasonic wave in the air chamber can be obtained by reading the count value of the timer. It also includes a temperature sensor, which is arranged in the acoustic gas chamber, and the temperature signal collected by it is transmitted to the signal processing system, and the influence of temperature drift on the hydrogen concentration value is eliminated through a linear compensation algorithm. Added a temperature sensor that operates from -40 to 85°C with a resolution of 0.001°C. Model can choose MS5611.

Structurally, the gas chamber of the present invention includes a sound velocity measurement, frequency tuning and monitoring device for the measurement of sound speed and sound attenuation spectrum; a temperature sensor for temperature compensation of the gas chamber; and a sound signal attenuation monitoring device in the gas cavity.

An embodiment of the present invention also provides a method for detecting the concentration of hydrogen in a multi-component mixed gas, including the following steps. Step 1: Connect the air inlet of the acoustic air chamber to the air distribution module for air intake, and the air outlet of the acoustic air chamber and the pressure Connect the control module, use the pressure control module to adjust the pressure in the acoustic air chamber, and keep the pressure value in the range of 1kPa ~ 100kPa; step 2, the ultrasonic transmitter module transmits ultrasonic waves in the acoustic air chamber; step 3, the receiving module receives ultrasonic waves in the acoustic chamber The pulse transmission time in the gas chamber is processed by the signal processing module to obtain the propagation speed of the ultrasonic wave; in step 4, the corresponding concentration of each component gas in the mixed gas is calculated according to the corresponding relationship between the gas concentration and the sound speed, so as to realize the binary mixed gas detection of hydrogen concentration. It also includes the following step 5. The receiving module receives the ultrasonic wave and obtains the frequency spectrum of its amplitude propagating in the acoustic gas chamber, and the signal processing module processes it to obtain the acoustic attenuation value of the ultrasonic wave, so as to realize the detection of the hydrogen concentration in the ternary mixed gas.

The receiving module includes an amplifier circuit, a filter circuit, a zero-crossing comparison circuit, and a shaping circuit. The sound wave signal passing through the acoustic air chamber is converted into a sinusoidal signal after passing through these circuits, and the attenuation of the ultrasonic wave is obtained by reading the peak value change of the sinusoidal signal. Take the count value of the timer to get the transmission time of the ultrasonic wave in the acoustic air chamber. The ultrasonic transmitting module is controlled by STM32 to control the CPLD to transmit 8 square wave signals. After processing, it becomes a sine wave to drive the ultrasonic transducer to transmit. The ultrasonic transducer converts the sound pressure signal into a voltage signal. The frequency of the ultrasonic transducer is 300kHz, and its divergence angle is small and the directionality is good. In the hydrogen detection system, the rubber pipe and the gas chamber interface are sealed and fixed. It also includes a timer to record the time of ultrasonic waves from the ultrasonic transmitting module to the receiving module. The output end of the timer is connected to the receiving module. The pressure control module is a vacuum pump. ), there are two 2mm holes on the side of the acoustic air chamber, and the 2XZ-4 vacuum pump can be used. The pressure in the acoustic air chamber is achieved below 10kPa. The connection between the outlet of the acoustic air chamber and the vacuum pump is controlled by a valve. The attenuation of the ultrasonic wave can be obtained by reading the peak-to-peak value of the sinusoidal signal, and the transmission time of the ultrasonic wave in the air chamber can be obtained by reading the count value of the timer. It also includes a temperature sensor, which is arranged in the acoustic gas chamber, and the temperature signal collected by it is transmitted to the signal processing system, and the influence of temperature drift on the hydrogen concentration value is eliminated through a linear compensation algorithm. Added a temperature sensor that operates from -40 to 85°C with a resolution of 0.001°C. Model can choose MS5611.

Structurally, the gas chamber of the present invention includes a sound velocity measurement, frequency tuning and monitoring device for spectrum measurement of sound speed and sound absorption; a temperature sensor for temperature compensation of the gas chamber; and a signal attenuation monitoring device in the acoustic gas cavity.

In one embodiment of the present invention, the working process is as follows: for a binary mixed gas, when the acoustic wave pulse emitted by the ultrasonic transducer passes through the acoustic gas chamber containing the two mixed gases, the sensor at the receiving end will receive the time, temperature, The pressure and other signals are fed back to the signal processing system, and the hydrogen concentration value after temperature compensation is obtained through calculation.

The invention realizes the measurement of the hydrogen concentration in the ternary mixed gas based on the detection of sound speed and sound attenuation. Due to the different molecular weights of different gases, the propagation speed of ultrasonic waves in different gases is different. The molecular weight of hydrogen is the smallest, and the ultrasonic wave fluctuates the fastest in hydrogen, so the speed of sound is the fastest, and the speed of sound is very sensitive to the change of hydrogen concentration. The corresponding relationship between the number of pulses and the gas concentration can be established by detecting the number of sound wave pulses recorded by the timer:

The length of the acoustic cell is represented by L, α ₁ , α ₂ are the concentrations of H ₂ and CH ₄ respectively, γ is the specific heat ratio, R is the universal constant, T is the temperature, N is the number of acoustic pulses, and M is the molecular weight. In the present invention, L is 4.9 cm, γ is 1.4, and the molecular weights of H ₂ , N ₂ and CH ₄ are 2.02, 28.01 and 16.04, respectively.

For the detection of the hydrogen concentration in the ternary mixed gas, in addition to the sound speed, it is also necessary to measure the sound absorption (sound attenuation) coefficient in order to obtain the hydrogen concentration value. According to the theoretical model of D-L, the molecular collision and energy transfer process in the multi-component mixed gas were analyzed, and the theoretical relationship between the acoustic absorption coefficient and the sound wave frequency and the gas concentration of each component in the ternary mixed gas was established. The total sound absorption includes two parts, classical sound absorption and relaxation sound absorption, expressed as:

where γ is the specific heat ratio, that is the wavelength of the λ sound wave, η is the viscosity of the gas, C _P is the constant pressure specific heat, f is the frequency of the sound wave, P is the pressure inside the gas, a is the speed of sound, and f is the frequency of the sound wave , D _i and f _i represent the relaxation strength and relaxation frequency of the corresponding gas molecular vibrational modes, respectively. Specific analysis is required for mixed gases of different compositions.

In the present invention, the demodulation process is shown in FIG. 2 : the ternary mixed gas containing hydrogen, taking H ₂ , CH ₄ and N ₂ as examples, can make H ₂ − The relationship curve of CH ₄ concentration (solid line); in the same way, according to the measured sound absorption coefficient, a curve (dotted line) about H ₂ -CH ₄ concentration can also be obtained, and the two curves are drawn on the same plane. , and the coordinate value corresponding to the intersection point is the concentration of H ₂ and CH ₄ that satisfy both the sound absorption condition and the sound velocity condition. The abscissa of the intersection point represents the actual H ₂ concentration, and the ordinate represents the actual CH ₄ concentration. So far, the detection of the hydrogen concentration is realized.

It should be understood that, for those skilled in the art, improvements or changes can be made according to the above description, and all these improvements and changes should fall within the protection scope of the appended claims of the present invention.

Claims (10)

1. the detection device of hydrogen concentration in a multi-component mixed gas, it is characterized in that, comprise acoustic air chamber, pressure control module, ultrasonic transmitting module, receiving module and signal processing module, ultrasonic transmitting module, receiving module are arranged in acoustic air chamber , There are 2 openings on the acoustic air chamber, one of which is the air inlet, which is connected to the air distribution module, and the other is the air outlet, which is connected to the pressure control module. The pressure control module is used for the pressure adjustment in the acoustic air chamber. The pressure value The range is 1kPa～100kPa, the receiving module receives the ultrasonic wave and measures the pulse transmission time in the acoustic air chamber, and the signal processing module processes it to obtain the propagation speed of the ultrasonic wave. 2. The detection device of hydrogen concentration in the multi-component mixed gas according to claim 1, wherein the receiving module is also used to receive the ultrasonic wave and obtain the frequency spectrum of its amplitude in the acoustic gas chamber, and the signal processing module processes it Obtain the sound attenuation value of the ultrasonic wave. 3. The detection device of hydrogen concentration in the multi-component mixed gas according to claim 2, wherein the receiving module comprises an amplifier circuit, a filter circuit, a zero-crossing comparison circuit, a shaping circuit, and the sound wave signal passing through the acoustic gas chamber is passed through these After the circuit is converted into a sinusoidal signal, the attenuation of the ultrasonic wave is obtained by reading the peak value of the sinusoidal signal, and the transmission time of the ultrasonic wave in the acoustic air chamber is obtained by reading the count value of the timer. 4. The detection device for hydrogen concentration in the multi-component mixed gas according to claim 1 or 2, wherein the ultrasonic transmitting module transmits 8 square wave signals, which become sinusoidal waves to drive the ultrasonic transducer to transmit after being processed. 5. the detection device of hydrogen concentration in the multi-component mixed gas according to claim 1 and 2, is characterized in that, also comprises timer, records the time of ultrasonic wave from ultrasonic wave transmitting module to receiving module, the output end of timer and receiving module Connection, the pressure control module is a vacuum pump, the acoustic air chamber is a cylinder, the section diameter is 2cm, and the height is 5cm-8cm, and two openings are provided on the side of the acoustic air chamber. 6. The device for detecting the hydrogen concentration in the multi-component mixed gas according to claim 1 or 2, characterized in that, it further comprises a temperature sensor, which is arranged in the acoustic gas chamber, and the temperature signal collected by it is transmitted to the signal processing system, and the temperature signal is collected by linear compensation. The algorithm eliminates the effect of temperature drift on hydrogen concentration measurements. 7. A method for detecting hydrogen concentration in a multi-component mixed gas based on claim 1, wherein the method comprises the following steps, and in step 1, the air inlet of the acoustic air chamber is connected to the air distribution module for air intake, and the acoustic air The air outlet of the chamber is connected to the pressure control module, and the pressure control module is used to adjust the pressure in the acoustic air chamber to keep the pressure value in the range of 1kPa to 100kPa; step 2, the ultrasonic transmitter module emits ultrasonic waves in the acoustic air chamber; step 3, The receiving module receives the pulse transmission time of the ultrasonic wave in the acoustic gas chamber, and the signal processing module processes it to obtain the propagation speed of the ultrasonic wave; Step 4: Calculate the corresponding concentration of each component gas in the mixed gas according to the corresponding relationship between the gas concentration and the sound speed , to realize the detection of hydrogen concentration in binary mixed gas. 8. the detection method of hydrogen concentration in the multi-component mixed gas according to claim 7, is characterized in that, also comprises following step 5, receiving module receives ultrasonic wave and obtains the frequency spectrum of its amplitude propagating in acoustic gas chamber, signal processing module It is processed to obtain the acoustic attenuation value of the ultrasonic wave, and the detection of the hydrogen concentration in the ternary mixed gas is realized. 9. The detection method of hydrogen concentration in the multi-component mixed gas according to claim 8, wherein the receiving module comprises an amplifier circuit, a filter circuit, a zero-crossing comparison circuit, a shaping circuit, and the sound wave signal passing through the acoustic gas chamber is passed through these After the circuit is converted into a sinusoidal signal, the attenuation of the ultrasonic wave is obtained by reading the peak value change of the sinusoidal signal, and the transmission time of the ultrasonic wave in the acoustic air chamber is obtained by reading the count value of the timer. The ultrasonic transmitting module transmits 8 square wave signals. After processing, it becomes a sine wave to drive the ultrasonic transducer to emit. 10. the detection method of hydrogen concentration in the multi-component mixed gas according to claim 8, is characterized in that, also comprises timer, records the time of ultrasonic wave from ultrasonic transmitting module to receiving module, the output end of timer is connected with receiving module, The pressure control module is a vacuum pump, and the acoustic air chamber is a cylinder with a cross-sectional diameter of 2cm and a height of 5cm-8cm. There are two openings on the side of the acoustic air chamber, and a temperature sensor is also included. The signal is sent to the signal processing system, and the influence of temperature drift on the hydrogen concentration value is eliminated through a linear compensation algorithm.

Images