阅读说明：本技术 一种混合气体中氢气浓度传感装置、检测装置及检测方法 (Sensing device, detection device and detection method for hydrogen concentration in mixed gas ) 是由 黄延楷 王福 林志强 覃敏航 王兵杰 夏景霖 杨升 李艳 于 2020-11-24 设计创作，主要内容包括：本发明公开了一种混合气体中氢气浓度传感装置、检测装置及检测方法,涉及气体微量检测技术领域。混合气体中氢气浓度传感装置,包括：热敏电阻、正极板、负极板、电极、催化剂和反应室,其中,所述热敏电阻两端通过电路分别与所述正极板和负极板连接；所述催化剂设置于所述电极上,用于催化气体电化反应；所述电极通过电路分别与所述正极板和负极板连接；所述热敏电阻、正极板、负极板、电极和催化剂设置于所述反应室中,所述反应室包括进气口和出气口。本发明提供的传感装置,可以降低检测投入成本,减少仪器数据分析难度,同时整体结构简单,操作使用方便,防护水平高,故障概率低,拆卸维修方便。(The invention discloses a sensing device, a detection device and a detection method for hydrogen concentration in mixed gas, and relates to the technical field of gas trace detection. A sensing device for hydrogen concentration in a mixed gas, comprising: the device comprises a thermistor, a positive plate, a negative plate, an electrode, a catalyst and a reaction chamber, wherein two ends of the thermistor are respectively connected with the positive plate and the negative plate through circuits; the catalyst is arranged on the electrode and is used for catalyzing gas electrochemical reaction; the electrode is respectively connected with the positive plate and the negative plate through a circuit; the thermistor, the positive plate, the negative plate, the electrode and the catalyst are arranged in the reaction chamber, and the reaction chamber comprises an air inlet and an air outlet. The sensing device provided by the invention can reduce the detection investment cost and the data analysis difficulty of instruments, and has the advantages of simple integral structure, convenience in operation and use, high protection level, low fault probability and convenience in disassembly and maintenance.)

1. A sensing device for sensing the concentration of hydrogen in a gas mixture, comprising:

a thermistor (1), a positive plate (2), a negative plate (3), an electrode (4), a catalyst (5) and a reaction chamber (6),

two ends of the thermistor (1) are respectively connected with the positive plate (2) and the negative plate (3) through circuits;

the catalyst (5) is arranged on the electrode (4) and is used for catalyzing gas electrochemical reaction;

the electrode (4) is respectively connected with the positive plate (2) and the negative plate (3) through a circuit;

the thermistor (1), the positive plate (2), the negative plate (3), the electrode (4) and the catalyst (5) are arranged in the reaction chamber (6), and the reaction chamber (6) comprises an air inlet (11) and an air outlet (12).

2. The apparatus for sensing the concentration of hydrogen in a mixed gas according to claim 1, wherein the gas inlet (11) and the gas outlet (12) are disposed diagonally along the reaction chamber (6).

3. A device for detecting the concentration of hydrogen in a gas mixture, comprising a device for sensing the concentration of hydrogen in a gas mixture according to any one of claims 1 to 2, and a current detection system connected to the positive electrode plate (2) and the negative electrode plate (3).

4. The apparatus for detecting the concentration of hydrogen in a mixed gas according to claim 3, wherein the current detection system comprises a current detection device (7), an amplification circuit (8) and a fixed-value resistor (9).

5. A method for detecting a hydrogen concentration in a mixed gas, characterized by applying the apparatus for detecting a hydrogen concentration in a mixed gas according to any one of claims 3 to 4, comprising the steps of:

standard state output measurement, wherein hydrogen is pumped into the reaction chamber (6), the hydrogen generates electrochemical reaction under the action of the catalyst (5), and the current detection system performs output measurement;

the state of the mixed gas is output and measured, the mixed gas is pumped into the reaction chamber (6), the mixed gas generates electrochemical reaction under the action of the catalyst (5), and the current detection system carries out output measurement;

and (4) measuring and comparing, wherein the current detection system outputs a measurement result according to the state of the mixed gas and outputs the measurement result according to the standard state to detect the concentration of the hydrogen in the mixed gas.

6. An apparatus comprising a sensing device of a hydrogen concentration in a mixed gas, characterized by comprising the sensing device of a hydrogen concentration in a mixed gas according to any one of claims 1 to 2.

7. An apparatus comprising a device for detecting a hydrogen concentration in a mixed gas, characterized by comprising the device for detecting a hydrogen concentration in a mixed gas according to any one of claims 3 to 4.

Technical Field

The invention relates to the technical field of gas trace detection, in particular to a sensing device, a detection device and a detection method for hydrogen concentration in mixed gas.

Background

Hydrogen gradually enters the eyeball as an efficient and environment-friendly energy source, meets the strategic national requirements on sustainable development, and is one of emerging energy sources for solving the current energy crisis. Fuel cells are receiving wide attention at home and abroad as a new power generation technology using hydrogen energy. The fuel cell has the advantages of energy conservation, environmental protection, long service life and the like, but has a plurality of hidden dangers. The hydrogen is a flammable and explosive article, and the safety risk brought by the hydrogen is not negligible while the hydrogen has the first-yield heat value; meanwhile, the characteristics of light weight and quick diffusion bring great inconvenience to storage and transportation. When the content of hydrogen in the air reaches more than 4 percent, explosion is easy to occur. Therefore, the method has important significance for the management and detection of hydrogen.

At present, a few detection instruments for hydrogen in the market are adopted, a general combustible gas detection device is mostly adopted, and hydrogen is regarded as combustible gas to be detected by an electrochemical method. In the detection of the hydrogen concentration in the mixed gas, a method of putting a large number of sensors or using high-precision instruments and equipment is often used for analyzing the components of the mixed gas, the input cost is high, the analysis difficulty is high, the fault repair rate is low, and the practicability is poor.

A mixed gas concentration detection device (Chinese patent CN209690162U) is characterized in that a nitrogen detector, an infrared light source driver, a temperature detector and an infrared detection device are added in a gas chamber, the nitrogen sensor in the gas chamber is used for detecting the concentration of real-time nitrogen gas, the temperature sensor is used for collecting temperature data, infrared signals absorbed by gas are converted into electric signals through the infrared detection device, and the electric signals are conditioned for data analysis, as shown in figure 4. The method has the advantages that the gas type detection is comprehensive, and the detection precision is high; the defect is that the concentration of the gas is converted into an electric signal which is easily influenced by the purity of the gas, the judgment of the circular flow influence of the mixed gas in the gas chamber can be caused due to the equidirectional arrangement of the gas inlet and the gas outlet, and meanwhile, the investment cost of a large number of sensors is high, the number of variables to be processed is large, and the analysis difficulty is large.

The device for detecting the concentration of a target gas in a mixed gas (Chinese patent CN210198953U) uses a light source (1), a detector (2) and a filter mechanism (3) as shown in FIG. 5, can detect an interference gas which has a superposed absorption band with the target gas in a spectrum absorption region in the mixed gas, and analyzes the gas components and concentration from multiple angles by rotating a filter (303) and 305 of the filter mechanism. The method has the advantages of high sensitivity and high detection precision; the defects are complex process, high use difficulty, high precision of optical instruments, poor water, dust and vibration resistance, high failure rate, difficult failure maintenance and treatment and limited practical application environment.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a sensing device, a detection device and a detection method for the concentration of hydrogen in mixed gas, which are used for reducing the investment cost and the difficulty in analyzing instrument data, and are simple in integral structure, convenient to operate and use, high in protection level, low in failure probability and convenient to disassemble and maintain.

In order to achieve the purpose, the technical scheme of the invention is as follows:

a sensing device for sensing the concentration of hydrogen in a gas mixture, comprising:

a thermistor, a positive plate, a negative plate, an electrode, a catalyst and a reaction chamber, wherein,

two ends of the thermistor are respectively connected with the positive plate and the negative plate through circuits;

the catalyst is arranged on the electrode and is used for catalyzing gas electrochemical reaction;

the electrode is respectively connected with the positive plate and the negative plate through a circuit;

the thermistor, the positive plate, the negative plate, the electrode and the catalyst are arranged in the reaction chamber, and the reaction chamber comprises an air inlet and an air outlet.

Further, the air inlet and the air outlet are arranged diagonally along the reaction chamber.

The invention also provides a device for detecting the concentration of hydrogen in the mixed gas, which comprises a hydrogen concentration sensing device in the mixed gas and a current detection system connected with the positive plate and the negative plate.

Further, the current detection system comprises a current detection device, an amplifying circuit and a constant value resistor.

The invention also provides a method for detecting the concentration of hydrogen in the mixed gas, and the device for detecting the concentration of hydrogen in the mixed gas comprises the following steps:

performing standard state output measurement, namely pumping hydrogen into the reaction chamber, performing electrochemical reaction on the hydrogen under the action of the catalyst, and performing standard state output measurement by using the current detection system;

the mixed gas state output measurement is carried out, the mixed gas is pumped into the reaction chamber, the mixed gas generates electrochemical reaction under the action of the catalyst, and the current detection system carries out the mixed gas state output measurement;

and (4) measuring and comparing, wherein the current detection system outputs a measurement result according to the state of the mixed gas and outputs the measurement result according to the standard state to detect the concentration of the hydrogen in the mixed gas.

The invention also provides a device comprising the hydrogen concentration sensing device in the mixed gas, which comprises the hydrogen concentration sensing device in the mixed gas.

The invention also provides a device comprising the device for detecting the concentration of the hydrogen in the mixed gas, which comprises the device for detecting the concentration of the hydrogen in the mixed gas.

Compared with the prior art, the invention has the following beneficial effects:

1. the sensing device provided by the invention utilizes the current released by gas electrochemical reaction as a sensing signal, and automatically corrects the detection parameter error caused by impurity gas by using the built-in thermistor, and has the advantages of simple integral structure, convenient operation and use, high protection level, low fault probability and convenient disassembly and maintenance;

2. the sensing device does not need to use a large number of sensors as a judgment and analysis means, and reduces the investment cost and the data analysis and processing difficulty due to the switching flow of internal programs.

Drawings

FIG. 1 is a schematic structural diagram of a sensing device and a detection device for hydrogen concentration in a mixed gas according to an embodiment of the present invention;

FIG. 2 is an electrical schematic diagram of an embodiment of the present invention without a thermistor;

FIG. 3 is an electrical schematic diagram of a thermistor according to an embodiment of the present invention;

FIG. 4 is a drawing of a mixed gas concentration detecting apparatus in the background art;

FIG. 5 is a diagram of a device for detecting the concentration of a target gas in a mixed gas in the prior art;

FIG. 6 is a diagram showing the relationship between the resistance of the gas mixture thermistor and the hydrogen gas ratio in the embodiment of the present invention.

FIG. 7 is a graph showing the relationship between the mixed gas thermistor and the internal temperature rise in the example of the present invention.

In the figure, 1-thermistor, 2-positive plate, 3-negative plate, 4-electrode, 5-catalyst, 6-reaction chamber, 7-current detection device, 8-amplification circuit, 9-constant value resistor, 10-vacuum pump, 11-gas inlet, 12-gas outlet and 13-gas to be detected.

Detailed Description

In order to explain the technical content, the achieved objects and the effects of the present invention in detail, the following description is made in conjunction with the embodiments and the accompanying drawings.

Fig. 1 shows a sensing device for sensing the concentration of hydrogen in a mixed gas and a corresponding detecting device, wherein:

the sensing device includes:

a thermistor 1, a positive plate 2, a negative plate 3, an electrode 4, a catalyst 5 and a reaction chamber 6, wherein,

two ends of the thermistor 1 are respectively connected with the positive plate 2 and the negative plate 3 through circuits;

the catalyst 5 is arranged on the electrode 4, is mixed with adsorbing material active carbon and then is coated on the electrode 4 and is used for catalyzing the gas to be detected to generate electrochemical reaction;

the electrode 4 is respectively connected with the positive plate 2 and the negative plate 3 through a circuit;

the thermistor 1, the positive electrode plate 2, the negative electrode plate 3, the electrode 4 and the catalyst 5 are disposed in the reaction chamber 6, and the reaction chamber 6 includes an inlet 11 and an outlet 12.

Besides the sensing device, the detection device also comprises a current detection system connected with the positive plate 2 and the negative plate 3, the current detection system is connected with the thermistor 1 in parallel, and the current detection system outputs corresponding hydrogen concentration information according to detected current signals.

In a preferable scheme, the current detection system comprises a current detection device 7, an amplifying circuit 8 and a fixed value resistor 9, wherein the fixed value resistor 9 is used for protecting the current detection device 7 from being directly connected with a signal power supply; because the current generated by the electrical reaction in the sensing device is generally very small, the amplifying circuit 8 amplifies the current output by the sensing device, so that the current detection device 7 can conveniently detect the current change; the current detection means 7 converts the detected current information into hydrogen concentration information.

Preferably, in the device for sensing the concentration of hydrogen in the mixed gas, the gas inlet 11 and the gas outlet 12 are arranged along opposite angles of the reaction chamber 6, so that the gas to be detected can stably flow through the electrode 4 and the catalyst 5, and the detection error is reduced.

The working principle of the sensing device for the hydrogen concentration in the mixed gas and the corresponding detection device is as follows:

and the gas outlet 12 of the reaction chamber 6 is communicated with a vacuum pump 10, and the vacuum pump 10 works and can input the gas to be measured 13 into the reaction chamber 6 from the gas inlet 11.

The gas 13 to be detected is subjected to electrochemical reaction in the reaction chamber 6 under the action of the catalyst 5, electrons lost in the reaction reach the positive plate 2 through a circuit, finally a current signal is formed and output to a current detection system connected with the positive plate 2 and the negative plate 3, and the current detection system converts detected current information into concentration information. The electrochemically generated electron current can be regarded as a signal power source, and the signal passing through the current detection system is a detection signal, as shown in fig. 2.

At the same time, heat is also generated when the gas undergoes an electrochemical reaction in the reaction chamber 6. In the reaction chamber 6 with constant space and volume and negligible other influence, the heat release is only related to the composition ratio of the mixed gas, the temperature in the reaction chamber 6 is changed due to the heat released, the thermistor 1 reacts to the temperature change, the resistance of the thermistor is adjusted, impurity electrons generated in the mixed gas in the electrochemical reaction of other gases except hydrogen are shunted by the thermistor 1, so that the current flowing through the current detection system just reflects the concentration information of the hydrogen in the mixed gas, and the effect of correcting the detection result is achieved, as shown in fig. 3.

The following takes the mixed gas of hydrogen and methane as an example, and specifically describes the principle of generating a detection signal by the sensing device and the principle of detecting the hydrogen concentration in the mixed gas by the detection device.

The combustible gas generates combustion reaction and emits electrons, the electrons flow in a circuit after passing through the polar plate to form current, and the current is a detection signal. The different content of combustible gas in the mixed gas per unit volume can lead to different quantity of emitted electrons, thus causing the change of the magnitude of the detection signal, thereby being capable of representing the concentration of the measured gas.

Firstly, when the gas 13 to be measured is only hydrogen (1mol) inputted into the reaction chamber 6, the following chemical reaction occurs under the action of the catalyst 5,

H₂+O₂＝＝H₂O，

with simultaneous electron-loss reaction H₂-2e^-＝＝2H⁺Electrons lost in the reaction reach the positive plate 2 through a circuit to form a current signal, and the main circuit current generated by the electrochemical reaction is assumed to be I₁Constant value resistance of R₁The thermistor value is R₂The current through the current sensing system is I. 1mol of hydrogen is completely reacted outThe heat quantity of (2) was 285.5kJ, and the number of electrons emitted was 2 mol. This state is the standard state.

When the gas in the reaction chamber 6 is hydrogen and methane, the following chemical reaction occurs under the action of the catalyst 5

H₂+O₂＝＝H₂O (main reaction)

CH₄+2O₂＝＝CO₂+2H₂O (side reaction).

At the same time, in the main reaction, electron-losing reaction H occurs₂-2e^-＝＝2H⁺In the side reaction, electron-losing reaction CH occurs₄-8e^-+2O₂＝＝C⁴⁺+4H⁺. Electrons lost in the reaction can reach the positive plate 2 through a circuit to form a current signal, and supposing that the main circuit current generated by the electrochemical reaction is I₂Constant value resistance of R₁(constant value resistor, same as standard state, constant value), the thermistor 1 resistance is R.

n_(methane)+n_(Hydrogen)1 (assuming a total of 1mol of methane and hydrogen species)

IR₁＝(I₁-I)R₂(parallel circuits equal voltage, standard state)

The current magnitude is proportional to the number of electrons emitted:

I₂：I₁＝(2·n_(Hydrogen)+8·n_(methane))：2，

I₂＝(n_(Hydrogen)+4·n_(methane))I₁

n_(Hydrogen)·IR₁＝{I₂-n_(Hydrogen)I } R (parallel circuit voltage equal after mixed gas is introduced)

R is the resistance value of the thermistor 1 in the mixed gas state. N on the left_(Hydrogen)I represents the resistance R passing through a constant value₁Is equal to n in relation to the standard state current I_(Hydrogen)，n_(Hydrogen)Is not only the ratio of hydrogen in the mixed gas, but also passes through a constant value resistor R when the hydrogen is equal to the mixed gas state₁Current and standard state through a constant value resistor R₁The ratio of the currents.So by detecting the constant value resistance R₁The ratio of the current in the mixed gas state to the current in the standard state can be known.

Obtained by the above calculation

R＝R₂/[1+4n_(methane)I₁/n_(Hydrogen)(I₁-I)]

Wherein n is_(methane)And n_(Hydrogen)Respectively represents the ratio of two gases in the mixed gas of unit volume, is the independent variable of the formula, n_(methane)＝1-n_(Hydrogen)。

R1 is a constant value resistor, the resistance value is constant and is a known constant value.

R2 is the thermistor resistance value in the standard state, and the value is measured and is a known constant value.

R is the resistance value of the thermistor when the mixed gas is introduced, and is a dependent variable of the formula.

The whole equation is the thermistor theory map.

In summary, I₁And R₂Is a measurable constant value in a standard state, R value and the hydrogen ratio n in the mixed gas_(Hydrogen)There is a definite relationship, as described in fig. 6. In practical use, the temperature rise and the hydrogen gas ratio n in the reaction chamber 6_(Hydrogen)In positive correlation, the temperature in the reaction chamber 6 increases with the increase of the hydrogen ratio, and the R-hydrogen ratio curve can be further converted into an R-temperature curve according to the following conversion principle:

assuming a reaction chamber volume of 1m³The medium is air, and knowing that 1290J heat needs to be absorbed for every 1 ℃ rise of air, the hydrogen complete combustion heat release is 285.5kJ/mol, and the methane complete combustion heat release is 133.02kJ/mol, the following equation is given: x is n_(Hydrogen)；y＝n_(methane)

Total heat evolved from the reaction of the mixed gases: w ═ (285.5x +133.02y)/1.29

Other conditions were the same as in example: x + y is 1

The following can be obtained: w221.8 x +103.12

FIG. 7 can be obtained by combining the relationship between the hydrogen ratio and the thermistor value in FIG. 6

This calculation is convenient for expanding the value by a plurality of times, and in actual use, the reaction chamber volume and the gas introduction amount become small, but this does not affect the calculation of the curves of fig. 6 and 7. The theory of calculation is still valid.

As long as the thermistor R in the reaction chamber 6 satisfies the R value-temperature curve relationship, as shown in FIG. 7, the resistance R can be determined by measuring the resistance R₁And the ratio of the current in the mixed gas state to the current I in the standard state is used for knowing the proportion of the hydrogen in the mixed gas.

The electron current generated by the electrochemical reaction is regarded as a signal power source, and the current changes with the composition and the proportion of the reaction gas. During the detection process, the total number of electrons lost by the main and side reactions is only related to the components and the proportion of the gas to be detected.

The formula is calculated by taking a mixed gas of hydrogen and methane as an example, in the actual application process, the impurity components of the mixed gas are not limited to methane, but the mathematical relationship between the reaction heat release and the loss of electrons is similar to that of methane, the error part comes from the internal stress of a molecular structure (not explained further), and the error range is below the required precision and can be ignored.

In summary, the signal power supply and the thermistor 1 are only related to the gas components and the proportion absorbed by the reaction chamber 6, and with the adoption of the sensing device, in the reaction chamber 6, along with the difference of the gas components and the proportion in the mixed gas, under the action of heat generated by electrochemical reaction, the thermistor 1 can correspondingly adjust the resistance value of the mixed gas to shunt impurity electrons, so that the current signal output by the sensing device just reflects the hydrogen concentration information in the mixed gas.

The sensing device provided by the invention utilizes the current released by gas electrochemical reaction as a sensing signal, automatically corrects the detection parameter error caused by impurity gas by using the built-in thermistor, and has the advantages of simple integral structure, convenience in operation and use, high protection level, low fault probability and convenience in disassembly and maintenance.

The sensing device does not need to use a large number of sensors as a judgment and analysis means, and reduces the investment cost and the data analysis and processing difficulty due to the switching flow of internal programs.

The sensing device is a relatively independent device, can be according to the composition of mist and account for automatic generation and revise the sensing current signal, in the use, only need carry out composition discernment to the mist at the source of admitting air, according to the mist composition again, choose for use corresponding thermistor sensing device, need not to change current detection system internal program. The sensing device can also be connected with other devices to provide sensing signals for other devices, and the application range is wide.

Based on the device for detecting the concentration of hydrogen in the mixed gas, the invention also provides a method for detecting the concentration of hydrogen in the mixed gas, which comprises the following steps:

performing standard state output measurement, namely pumping hydrogen into the reaction chamber 6, performing electrochemical reaction on the hydrogen under the action of the catalyst 5, and performing output measurement by the current detection system;

the state of the mixed gas is output and measured, the mixed gas is pumped into the reaction chamber 6, the mixed gas generates electrochemical reaction under the action of the catalyst 5, and the current detection system carries out output measurement;

and (4) measuring and comparing, wherein the current detection system outputs a measurement result according to the state of the mixed gas and outputs the measurement result according to the standard state to detect the concentration of the hydrogen in the mixed gas.

The embodiment provides a sensing device and a corresponding detection device for the concentration of hydrogen in mixed gas, and in other embodiments, the sensing device or the detection device can be used in combination with other devices.

Although the present invention has been described in detail with reference to specific embodiments thereof, it will be apparent to one skilled in the art that modifications and improvements can be made based on the present invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.