CN113514515A - Gas concentration detector and bias-voltage-free gas concentration detection method - Google Patents
Gas concentration detector and bias-voltage-free gas concentration detection method Download PDFInfo
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Abstract
The present application relates to a gas concentration detector and a gas concentration detection method without bias voltage, the gas concentration detector of the present application includes: the mounting cover is connected with the mounting shell to form an accommodating cavity, and is provided with a first vent hole communicated with the accommodating cavity; the electrode assembly is arranged in the accommodating cavity and at least comprises a working electrode and a counter electrode; the external piece is arranged outside the mounting shell and is connected with the electrode assembly; the catalytic member is disposed within the first vent and/or on the surface of the working electrode. This application can utilize the catalytic component to turn into the second component with the first component in the initial gas that awaits measuring to need not to adopt the mode that the bias voltage detected, can obtain the concentration of first component through the concentration that detects the second component, simplified the structure and the circuit of gas concentration detector, and improved gas concentration detector's work efficiency.
Description
Technical Field
The present application relates to the field of detector technology, and more particularly, to a gas concentration detector and a method for detecting gas concentration without bias voltage.
Background
A gas sensor, i.e. a gas concentration detector, is a transducer that converts a certain gas volume fraction into a corresponding electrical signal. Among the gas sensors, the most widely used one is an Electrochemical gas sensor (Electrochemical gas sensor), which is a detector that measures a current by oxidizing or reducing a gas to be measured at an electrode to obtain a concentration of the gas to be measured.
In the prior art, when an electrochemical gas sensor detects the concentration of gases such as NO (nitric oxide), a bias voltage of plus 300 millivolts is often required to be added between a working electrode and a reference electrode, so that the concentration of the gases such as NO can be accurately measured by determining the potential on the working electrode. As such, at least two circuits are typically required in an electrochemical gas sensor, one being a bias circuit comprising a working electrode and a reference electrode for determining the potential at the working electrode, and the other being a detection circuit comprising a working electrode and a counter electrode for transporting electrons.
Therefore, the circuit and the structure of the electrochemical gas sensor in the prior art are complex, and the bias circuit is required to be used for controlling to eliminate the interference of voltage on detection in the detection process of the working electrode and the counter electrode, so that the time required for the stability of the electrochemical gas sensor is longer, the use is inconvenient, and the working efficiency of the electrochemical gas sensor is reduced.
Disclosure of Invention
An object of the present application is to provide a gas concentration detector and a gas concentration detection method that do not require a bias voltage, which simplify the structure and circuit of the gas concentration detector.
In order to achieve the above object, the embodiments of the present application are implemented as follows:
in a first aspect, the present application provides a gas concentration detector comprising: the device comprises a mounting shell, a mounting cover, an electrode assembly, an external element and a catalytic element, wherein the mounting cover is connected with the mounting shell to form a containing cavity, and the mounting cover is provided with a first vent hole communicated with the containing cavity; the electrode assembly is arranged in the accommodating cavity and at least comprises a working electrode and a counter electrode; the external connector is arranged outside the mounting shell and is connected with the electrode assembly; the catalytic member is arranged in the first vent hole and/or on the surface of the working electrode.
In one embodiment, the working electrode is fixed on the bottom surface of the mounting cover, and the catalytic element is disposed in the first vent hole and covers the surface of the working electrode opposite to the first vent hole.
In one embodiment, the total volume of the catalytic element is equal to or less than the volume of the first vent hole.
In one embodiment, the catalytic element is disposed in the containing cavity and fixed on the surface of the working electrode.
In one embodiment, the gas concentration detector further comprises: and the auxiliary cover is connected with the mounting cover and arranged in the first vent hole, and a second vent hole is formed in the auxiliary cover.
In one embodiment, the gas concentration detector further comprises: and the dustproof breathable film is connected with the mounting cover and is pressed on the auxiliary cover to shield the second vent hole.
In an embodiment, the first vent hole includes a first hole section, a second hole section and a third hole section, which are connected in sequence, the aperture of the first hole section is larger than that of the second hole section, the aperture of the second hole section is larger than that of the third hole section, the auxiliary cover is disposed on the second hole section, the dustproof and breathable film is disposed on the third hole section, and the total volume of the catalytic element is equal to or smaller than that of the third hole section.
In an embodiment, a fixing convex ring is convexly arranged on the inner wall of one end of the third hole section, which is connected with the second hole section.
In one embodiment, the electrode assembly further comprises: and the reference electrode is connected with the external connector.
In one embodiment, the catalytic element comprises manganese dioxide.
In one embodiment, the catalytic member is in the form of a tablet, block, strip, granule, powder, or granule.
In a second aspect, the present application provides a bias-free gas concentration detection method, comprising: converting a first component in the initial gas to be detected into a second component to obtain final gas to be detected; and detecting to obtain the concentration of the second component in the final gas to be detected.
In one embodiment, the initial gas to be measured is a pure gas including only the first component.
In one embodiment, the initial gas to be measured is a mixture gas, and further includes a second component; before converting the first component in the initial gas to be measured into the second component to obtain the final gas to be measured, the method further comprises the following steps: detecting to obtain the concentration of a second component in the initial gas to be detected; after the second component concentration in the final gas to be detected is detected, the method further comprises the following steps: and calculating the concentration of the first component in the initial gas to be measured according to the concentration of the second component in the final gas to be measured and the concentration of the second component in the initial gas to be measured.
Compared with the prior art, the beneficial effect of this application is:
this application can turn into the second component with the first component in the initial gas that awaits measuring through having add the catalysis piece to need not to adopt the mode that the bias voltage detected, can obtain the concentration of first component through the concentration that detects the second component, simplified gas concentration detector's structure and circuit, and improved gas concentration detector's work efficiency.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained from the drawings without inventive effort.
FIG. 1 is a graph of current potential in the prior art.
Fig. 2 is a sectional view of the gas concentration detector 1 according to an embodiment of the present application.
Fig. 3 is a sectional view of the gas concentration detector 1 according to an embodiment of the present application.
FIG. 4 is a graph of response voltage versus NO gas concentration for a prior art gas sensor without a bias voltage.
Fig. 5 is a graph showing the response of a gas concentration detector provided in an embodiment of the present application to different concentrations of NO gas.
FIG. 6 is a graph of a fitted function of response voltage and NO gas concentration of a gas concentration detector provided in an embodiment of the present application.
Icon: 1-a gas concentration detector; 100-mounting a housing; 110-a containment chamber; 200-mounting a cover; 210-a first vent; 211 — a first bore section; 212-a second bore section; 213-third pore section; 214-a stationary collar; 215-chamfering; 300-an electrode assembly; 310-a working electrode; 320-counter electrode; 330-mesh sheet; 340-a barrier film; 350-reference electrode; 400-external connector; 500-a catalytic member; 600-an auxiliary cover; 610-a second vent; 700-dustproof and breathable film.
Detailed Description
The terms "first," "second," "third," and the like are used for descriptive purposes only and not for purposes of indicating or implying relative importance, and do not denote any order or order.
Furthermore, the terms "horizontal", "vertical", "overhang" and the like do not imply that the components are required to be absolutely horizontal or overhang, but may be slightly inclined. For example, "horizontal" merely means that the direction is more horizontal than "vertical" and does not mean that the structure must be perfectly horizontal, but may be slightly inclined.
In the description of the present application, it should be noted that the terms "inside", "outside", "left", "right", "upper", "lower", and the like indicate orientations or positional relationships based on orientations or positional relationships shown in the drawings or orientations or positional relationships that are conventionally arranged when products of the application are used, and are used only for convenience in describing the application and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the application.
In the description of the present application, unless expressly stated or limited otherwise, the terms "disposed," "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements.
The technical solution of the present application will be clearly and completely described below with reference to the accompanying drawings.
Fig. 1 is a current potential graph in the prior art. Prior art gas sensors include a working electrode, a reference electrode, and a counter electrode. When a gas to be detected containing NO is introduced into the gas sensor in the prior art, the NO gas undergoes an oxidation reaction at the working electrode: NO +2H2O→HNO3+3H++3e-(ii) a A reduction reaction takes place at the counter electrode:
the concentration of NO gas can thus be measured by detecting the reaction current of electron formation on the working electrode and the counter electrode.
As shown in fig. 1, when the reaction voltage (voltage) between the working electrode and the counter electrode, that is, the potential at the working electrode changes, the reaction current (current) also changes. Generally, the larger the reaction voltage, the larger the reaction current, but within a certain voltage range (V1-V2), the current potential curve is relatively gentle, the change of the reaction current is small and almost constant, and this voltage range (V1-V2) is referred to as a current plateau region for transport diffusion control, when the reaction current is completely controlled by mass transport or flow diffusion of the gas to be detected, i.e., the electroactive gas, in which the redox reaction occurs.
Therefore, if the reaction voltage between the working electrode and the counter electrode is controlled between the current plateau regions (V1-V2), the reaction current generated at this time can eliminate the interference of the voltage, i.e., the potential on the working electrode 310, and thus the concentration of the gas such as NO can be accurately measured.
In the prior art, a bias circuit formed by a working electrode and a reference electrode is needed to be debugged in the detection process of the working electrode and the counter electrode, and a bias voltage is added between the working electrode and the reference electrode for control to ensure that the potential on the working electrode is in the current platform region (V1-V2), so that the interference of reaction voltage on detection can be eliminated. The process of bias control makes the electrochemical gas sensor require a long time to stabilize, is inconvenient to use, and reduces the working efficiency of the electrochemical gas sensor.
Meanwhile, bias debugging has high requirements on the circuit design of the gas sensor, and at least two loops are required to be designed, wherein one loop is a bias loop consisting of a working electrode and a reference electrode and used for determining the potential on the working electrode, and the other loop is a detection loop consisting of the working electrode and a counter electrode and used for transmitting electrons, so that the gas sensor in the prior art has high circuit complexity and correspondingly improves the structural complexity of the gas sensor.
Fig. 2 is a cross-sectional view of a gas concentration detector 1 according to an embodiment of the present application. The gas concentration detector 1 includes: installation shell 100, installation lid 200, electrode subassembly 300 and external piece 400, installation lid 200 and installation shell 100 pass through modes sealing connection such as joint, cup joint, welding or bolt fastening and be in the same place, and installation lid 200 and installation shell 100 form the chamber 110 that holds of placing electrolyte. The cross-section of the mounting case 100 and the mounting cover 200 may be circular, square or other shapes, and the axis of the mounting case 100 and the axis of the mounting cover 200 coincide. Wherein a direction in which the mounting cover 200 is directed toward the mounting case 100 is defined as downward.
The mounting cover 200 is provided with first ventilation holes 210 penetrating the upper and lower surfaces of the mounting cover 200. Is communicated with the containing cavity 110 and is used for introducing gas to be measured. The cross-section of the first vent 210 may be circular, square, or other shape.
The electrode assembly 300 includes at least a working electrode 310 and a counter electrode 320; the electrode assembly 300 is disposed in the receiving cavity 110. The working electrode 310 and the counter electrode 320 may be formed of an electrode film and a wire electrode, and the material of the working electrode 310 and the counter electrode 320 may be a noble metal such as platinum, palladium, rhodium, silver, or ruthenium, so that the working electrode 310 and the counter electrode 320 may be used as a catalyst, so that the gas to be measured may be oxidized or reduced at the working electrode 310 and the counter electrode 320 to form a reaction current.
The electrode assembly 300 may further include a separation film 340 made of a non-conductive material, the separation film 340 being disposed between the working electrode 310 and the counter electrode 320 for separating the working electrode 310 and the counter electrode 320. The electrode assembly 300 may further include a mesh 330, the mesh 330 is fixedly connected to the mounting cap 200, and the separator 340, the working electrode 310, and the counter electrode 320 are interposed between the mesh 330 and the mounting cap 200. The electrode assembly 300 may also include components such as absorbent paper.
The external connector 400 may include a plurality of pins, which are disposed on the bottom surface of the mounting case 100, and one end of each pin extends into the accommodating cavity 110, and the other end of each pin extends out of the mounting case 100. The plurality of pins are connected to the electrode assembly 300, and are used for deriving response signals such as reaction current, so that the concentration information of the gas to be measured can be obtained through the magnitude of the reaction current. The gas concentration detector 1 may further include a detection unit including a current amplifier and the like for amplifying the reaction current, so that the reaction current may be represented by a load voltage (i.e., a response voltage) of the detection unit. The gas concentration detector 1 may further include a processor or the like for converting the load voltage into the concentration information of the gas to be measured.
In another embodiment, the external device 400 may further include a circuit board, a plurality of pins are disposed on the circuit board, and the electrode wires of the electrode assembly 300 are electrically connected to the circuit board for guiding the reaction current.
The gas concentration detector 1 further includes a catalyst member 500, and the catalyst member 500 includes manganese dioxide MnO2So that NO gas entering the gas concentration detector 1 can be converted into NO2Gas, thereby facilitating the detection of NO gas.
Wherein, the catalytic element 500 can be disposed in the first vent 210 and/or on the surface of the working electrode 310, i.e. on the path of the gas to be measured to the working electrode 310, so that the NO gas entering the gas concentration detector 1 is converted into NO before reaching the working electrode 3102A gas.
The true bookIn the embodiment, the upper surface of the working electrode 310 and the bottom surface of the mounting cover 200 are connected together by heat melting, welding, adhering or clamping, and the catalytic element 500 is disposed in the first vent hole 210 and covers the entire area of the upper surface of the working electrode 310 in the first vent hole 210. Since the catalytic member 500 entirely covers the region of the working electrode 310 exposed through the first vent hole 210, NO gas must completely pass through the catalytic member 500, i.e., be converted into NO2The gas can reach the working electrode 310 for a corresponding electrochemical reaction to generate a detectable electrical signal, so as to ensure the accuracy and reliability of the final detection result.
In another embodiment, the working electrode 310 may be fixed on the mounting cover 200 or the mounting case 100, and the catalytic element 500 is disposed in the accommodating cavity 110 and fixed on the surface of the working electrode 310 by means of adhesion or the like. With this arrangement, the NO gas introduced into the gas concentration detector 1 can be converted into NO before reaching the working electrode 3102A gas.
The catalytic member 500 serves as a catalyst, so that the conversion rate of NO gas can be increased, and the catalytic member 500 does not participate in the final reaction product, so that repeated addition is not needed, and the use is convenient. And the catalytic element 500 does not participate in the final reaction product, the total volume of the catalytic element 500 may be equal to or less than the volume of the first vent hole 210, and the catalytic element 500 may or may not fill the first vent hole 210.
The catalyst member 500 may be in the form of a sheet, a block, a strip, a granule, a powder, or a granule. In this example, the catalyst 500 is MnO2The nano particles can increase the contact area of the catalytic element 500 and the gas to be detected, and are beneficial to the comprehensive conversion of NO gas.
In a specific operation process, the gas concentration detector 1 is disposed on other circuit boards through the external connector 400, so that the gas to be measured containing NO enters the accommodating chamber 110 through the first vent hole 210, since the chemical reaction of the gas to be measured is determined by the selection of the catalyst material. NO gas is first MnO2Under the action of the catalytic member 500, the NO gas undergoes an oxidation reaction in the first vent hole 210: 2NO + O2→2NO2(ii) a When NO gas is converted to NO2After the gas, NO again under zero bias2The gas undergoes an electrochemical reduction reaction at the working electrode 310: NO2+H++2e-→NO+2H2O; an oxidation reaction of water occurs at the counter electrode 320 to balance the reduction reaction of the working electrode 310:
NO can be obtained by detecting the reaction current of electron formation on the working electrode 310 and the counter electrode 320 at this time2Concentration of gas, NO obtained2The gas concentration is the concentration of NO gas.
The present embodiment can convert the first component (NO gas) in the initial test gas into the second component (NO gas) through the catalyst 5002Gas), measured in this example is NO2If the gas is not NO, then it is not necessary to ensure that the potential at working electrode 310 is in the current plateau region (V1-V2) shown in FIG. 1, and thus the concentration of the first component can be determined by detecting the concentration of the second component without the need for bias detection. In addition, the present embodiment omits the process of bias control, shortens the time required for the gas concentration detector 1 to stabilize, is convenient to use, and improves the working efficiency of the gas concentration detector 1.
It should be noted that the electrode assembly 300 of the gas concentration detector 1 of the present embodiment further includes a reference electrode 350, the reference electrode 350 is connected to the external connector 400, and the reference electrode 350 is disposed between the working electrode 310 and the counter electrode 320. The reference electrode 350 in the present embodiment is mainly used to improve the stability of the gas concentration detector 1 so that it can operate continuously.
The reference electrode 350 may also be composed of an electrode film and a wire electrode. The separators 340 are provided in 2 numbers, respectively provided between the working electrode 310 and the reference electrode 350 and between the reference electrode 350 and the counter electrode 320, for separating the working electrode 310 and the reference electrode 350 and the counter electrode 320, respectively.
In another embodiment, the gas concentration detector 1 does not need the reference electrode 350, thereby simplifying the structure and the circuit of the gas concentration detector 1. The number of the separators 340 is 1, and is disposed between the working electrode 310 and the counter electrode 320.
Fig. 3 is a cross-sectional view of the gas concentration detector 1 according to an embodiment of the present application. The gas concentration detector 1 further includes: the auxiliary cover 600, the auxiliary cover 600 is connected with the mounting cover 200, and is arranged in the first vent hole 210, the auxiliary cover 600 is provided with a second vent hole 610, and the second vent hole 610 penetrates through the upper and lower surfaces of the auxiliary cover 600 and is used for introducing gas to be measured. The auxiliary cover 600 may be coupled to the mounting cover 200 by interference fit, snap fit, hinge, or bolt. In one embodiment, the catalytic member 500 is in the form of a block or a sheet, and the outer diameter of the catalytic member 500 is larger than the aperture of the second vent hole 610, and the aperture of the second vent hole 610 is smaller than the aperture of the first vent hole 210, so that the auxiliary cover 600 can prevent the catalytic member 500 from being removed from the first vent hole 210 when the gas concentration detector 1 is turned over.
The gas concentration detector 1 further includes: and the dustproof breathable film 700 is connected with the mounting cover 200, and is pressed on the auxiliary cover 600 to shield the second breathable hole 610. The connection mode of the dust-proof and air-permeable membrane 700 and the mounting cover 200 can be interference fit, snap connection, hinge connection or bolt fixation. The dustproof breathable film 700 may be a Polytetrafluoroethylene (PTFE) breathable film having waterproof and breathable properties for preventing condensation and dust, so as to reduce the influence of temperature change, dust, dirt, and moisture on the measurement result. The dust-proof gas-permeable membrane 700 also prevents the catalyst 500, which is in any shape such as a sheet, a block, a strip, a granule, a powder, or a granule, from coming out of the first vent hole 210 when the gas concentration detector 1 is inverted.
Wherein, the third hole section 213 is provided with a fixing convex ring 214 protruding on the inner wall of one end (top end) connected with the second hole section 212. The fixing protrusion ring 214 abuts against the auxiliary cap 600.
Wherein, the third hole section 213 is provided with a chamfer 215 at an end (bottom end) facing away from the second hole section 212, and the provision of the chamfer 215 can increase the contact area between the catalytic member 500 and the working electrode 310, thereby further ensuring that NO gas is converted into NO after having to completely pass through the catalytic member 5002The gas can reach the working electrode 310 for a corresponding electrochemical reaction to generate a detectable electrical signal, so as to ensure the accuracy and reliability of the final detection result.
In another embodiment, the third hole section 213 may also be provided with a protruding ring protruding on the inner wall of the end (bottom end) facing away from the second hole section 212.
In another embodiment, the gas concentration detector 1 further comprises a filter element disposed between the auxiliary cover 600 and the fixing convex ring 214 or disposed in the third hole section 213, wherein the filter element can be a powder or block solid of activated carbon or potassium permanganate filter for filtering and removing the interference gas.
Fig. 4 is a graph showing response voltage and NO gas concentration of a gas sensor in the prior art without bias voltage. Fig. 5 is a graph showing the response of the gas concentration detector 1 to different concentrations of NO gas according to an embodiment of the present application. Fig. 6 is a graph showing a fitting function of the response voltage and the NO gas concentration of the gas concentration detector 1 according to an embodiment of the present application.
In one embodiment, applicants have tested the gas concentration detector 1 shown in fig. 2 or 3, as well as a prior art gas sensor.
Test materials: different known concentrations of NO gas. Wherein the concentration comprises: 0.5ppm (i.e., 0.5 cm)3/m3) 1ppm, 1.5ppm and 3 ppm.
The test process comprises the following steps:
for the first time, prior art gas sensors were used without adding bias voltages in the working and reference electrodes, leaving them in the unbiased condition. And sequentially introducing NO gas with the concentration of 1ppm, NO gas with the concentration of 3ppm, NO gas with the concentration of 0.5ppm, NO gas with the concentration of 1ppm and NO gas with the concentration of 1.5ppm, and acquiring a response signal of the gas sensor. The response signal may be a voltage or a current. It should be noted that the gas concentration detector 1 shown in fig. 3 after the catalyst member 500 is removed may be used in the first test.
Second, using the gas concentration detector 1 of FIG. 3 with the catalyst 500 retained, the bias voltages in the working electrode 310 and the reference electrode 350 are not added, also in the case of no bias voltage. NO gas with the concentration of 1ppm, NO gas with the concentration of 3ppm, NO gas with the concentration of 0.5ppm, NO gas with the concentration of 1ppm and NO gas with the concentration of 1.5ppm are sequentially introduced, and response signals of the gas concentration detector 1 are obtained. The response signal may be a voltage or a current.
The test results are shown in fig. 4, 5 and 6.
Referring to fig. 4, the ordinate of the graph shows the response voltage between the working electrode 310 and the counter electrode 320 of the gas sensor, the abscissa of the graph shows the test time, and the curve shows the change of the response voltage when different concentrations of NO gas are introduced at different times.
In the curve, the response voltage does not change much when NO gas with different concentrations is introduced at different times, so that it can be concluded that the gas sensor has almost NO response to NO gas and cannot detect the concentration of NO gas under the conditions of NO bias voltage and NO catalytic element 500.
Referring to fig. 5, the ordinate of the graph shows the response voltage between the working electrode 310 and the counter electrode 320 of the gas concentration detector 1, the abscissa of the graph shows the test time, and the curve shows the change of the response voltage when different concentrations of NO gas are introduced at different times.
The change of response voltage is bigger when different concentrations of NO gas are let in at different times in this curve, and comparatively regular, and NO concentration is big more, and the response voltage change is big more to can draw the conclusion adopt in the condition that does not have offset voltage, set up under the condition of catalysis piece 500, the gas sensor is comparatively regular to NO gas's response, thereby can detect NO gas's concentration.
Referring to fig. 6, the ordinate represents the response voltage between the working electrode 310 and the counter electrode 320 of the gas concentration detector 1, the abscissa represents the NO gas concentration, and the solid points in the graph represent the results of several tests of fig. 5. The dashed line in the graph represents the fitted function between the NO gas concentration and the response voltage.
The fitting function of fig. 6 was analyzed from the test results of fig. 5, leading to a conclusion: the relation between the concentration of the NO gas and the response voltage is a linear relation, and the fitting function of the relation is 0.0396x + 0.0151; where y represents the response voltage and x represents the NO gas concentration.
Wherein the degree of fit R of the dotted line in FIG. 6 to the test results of FIG. 52The value is 0.9994, which indicates that the fitting function has high degree of fitting and high reliability.
In summary, the gas concentration detector 1 of the present application does not need to set a bias voltage by adding the catalytic element 500, performs bias control, and thus has good response linearity to NO gases with different concentrations, and can realize accurate measurement of the NO gas concentration. In addition, the present embodiment omits the process of bias control, shortens the time required for the gas concentration detector 1 to stabilize, is convenient to use, and improves the working efficiency of the gas concentration detector 1.
In one embodiment, the method for detecting a concentration of a gas without a bias includes the steps of: step S110-step S120.
Step S110: and converting the first component in the initial gas to be detected into the second component to obtain the final gas to be detected.
In this step, the initial gas to be measured is pure gas and includes only the first component. The first component may be N0 and the second component is NO2N0 gas was first MnO2And (3) carrying out an oxidation reaction under the action of a catalyst: 2NO + O2→2NO2So that the N0 gas is converted into NO2A gas.
Step S120: and detecting to obtain the concentration of the second component in the final gas to be detected.
The concentration of the second component in the final sample gas obtained in step S120 is equal to the concentration of the first component in the initial sample gas. In this step, the final gas to be measured can be oxidized or reduced at the electrode to measure the current, and the concentration of the second component in the final gas to be measured can be obtained. For example, NO may be at zero bias2The gas undergoes an electrochemical reduction reaction at the working electrode 310: NO2+H++2e-→NO+2H2O; an oxidation reaction of water occurs at the counter electrode 320 to balance the reduction reaction of the working electrode 310:
NO can be obtained by detecting the reaction current of electron formation on the working electrode 310 and the counter electrode 320 at this time2Concentration of gas, NO obtained2The gas concentration is the concentration of N0 gas.
Therefore, the first component in the initial gas to be detected can be converted into the second component which is easy to detect through the catalytic element 500, so that the concentration of the first component can be obtained by detecting the concentration of the second component without adopting a bias detection mode.
The gas concentration detector 1 shown in fig. 2 or 3 may be used in steps S110 to S120, or other devices may be used. For example, the oxidation may be performed in step S110 by a reaction chamber provided with a catalyst (catalyst 500) independently, and the detection in step S120 may be performed by a semiconductor gas sensor, a catalytic combustion gas sensor, a thermal conductivity gas sensor, an infrared gas sensor, a solid electrolyte gas sensor, or the like.
In one embodiment, the method for detecting a concentration of a gas without a bias includes the steps of: step S210-step S240.
Step S210: and detecting to obtain the concentration of the second component in the initial gas to be detected.
The initial gas to be measured is a mixed gas comprising a first component and a second component. In this step, the concentration of the original second component in the initial gas to be measured is measured for the subsequent calculation in step S240.
Step S220: and converting the first component in the initial gas to be detected into the second component to obtain the final gas to be detected. Please refer to step S110 for detailed description.
Step S230: and detecting to obtain the concentration of the second component in the final gas to be detected. Please refer to step S120 for detailed description.
Step S240: and calculating the concentration of the first component in the initial gas to be measured according to the concentration of the second component in the final gas to be measured and the concentration of the second component in the initial gas to be measured.
The concentration of the second component in the final gas to be measured is calculated as the sum of the concentration of the first component in the initial gas to be measured and the concentration of the second component in the initial gas to be measured in step S230. Therefore, the concentration of the first component in the initial gas to be measured can be obtained by subtracting the value obtained in step S210 from the value obtained in step S230.
It should be noted that the detection in step S210 may be performed by NO that does not respond to NO gas2The special measurement sensor can be a semiconductor gas sensor, an electrochemical gas sensor, a catalytic combustion gas sensor, a thermal conductivity gas sensor, an infrared gas sensor, a solid electrolyte gas sensor and the like.
The gas concentration detector 1 shown in fig. 2 or fig. 3 may be used in steps S220 to S240, and other devices may be used. For example, the oxidation may be performed in step S220 by a reaction chamber provided with a catalyst (catalyst 500) independently, and the detection in step S230 may be performed by a semiconductor gas sensor, a catalytic combustion gas sensor, a thermal conductivity gas sensor, an infrared gas sensor, a solid electrolyte gas sensor, or the like. The calculation of step S240 may be performed by a processor of the gas concentration detector 1 or by manual calculation.
It should be noted that the features of the embodiments in the present application may be combined with each other without conflict.
The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims (10)
1. A gas concentration detector, comprising:
mounting a shell;
the mounting cover is connected with the mounting shell to form an accommodating cavity, and is provided with a first vent hole communicated with the accommodating cavity;
the electrode assembly is arranged in the accommodating cavity and at least comprises a working electrode and a counter electrode;
the external connecting piece is arranged outside the mounting shell and is connected with the electrode assembly; and
and the catalytic piece is arranged in the first vent hole and/or on the surface of the working electrode.
2. The gas concentration detector according to claim 1, wherein the upper surface of the working electrode is connected to the bottom surface of the mounting cover, and the catalytic member is disposed in the first vent hole so as to entirely cover a region of the upper surface of the working electrode in the first vent hole.
3. The gas concentration detector according to claim 2, wherein a total volume of the catalytic member is equal to or smaller than a volume of the first vent hole.
4. The gas concentration detector according to claim 1, wherein the catalytic member is provided in the accommodation chamber and fixed to a surface of the working electrode.
5. The gas concentration detector according to claim 1, further comprising:
the auxiliary cover is connected with the mounting cover and arranged in the first vent hole, and a second vent hole is formed in the auxiliary cover; and
and the dustproof breathable film is connected with the mounting cover and is pressed on the auxiliary cover to shield the second ventilation hole.
6. The gas concentration detector according to claim 5, wherein the first vent hole includes a first hole section, a second hole section, and a third hole section connected in this order, the first hole section has a larger pore diameter than the second hole section, the second hole section has a larger pore diameter than the third hole section, the auxiliary cover is provided in the second hole section, the dust-proof gas-permeable membrane is provided in the third hole section, and the total volume of the catalyst member is equal to or smaller than the volume of the third hole section.
7. The gas concentration detector according to claim 1, wherein the electrode assembly further comprises: and the reference electrode is connected with the external connector.
8. The gas concentration detector according to any one of claims 1 to 7, wherein the catalytic member includes manganese dioxide;
the catalytic member is in the shape of a sheet, a block, a strip, a particle, a powder or a powder particle.
9. A method for detecting a concentration of a gas without a bias, comprising:
converting a first component in the initial gas to be detected into a second component to obtain final gas to be detected;
and detecting to obtain the concentration of the second component in the final gas to be detected.
10. The method of claim 9, wherein the initial gas to be measured further comprises a second component;
before converting the first component in the initial gas to be measured into the second component to obtain the final gas to be measured, the method further comprises the following steps:
detecting to obtain the concentration of a second component in the initial gas to be detected;
after the second component concentration in the final gas to be detected is detected, the method further comprises the following steps:
and calculating the concentration of the first component in the initial gas to be measured according to the concentration of the second component in the final gas to be measured and the concentration of the second component in the initial gas to be measured.
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| CN1186238A (en) * | 1996-06-06 | 1998-07-01 | 株式会社理研 | NOx sensors |
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