CN113203790A - Gas detection device and method - Google Patents
Gas detection device and method Download PDFInfo
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- CN113203790A CN113203790A CN202110640064.8A CN202110640064A CN113203790A CN 113203790 A CN113203790 A CN 113203790A CN 202110640064 A CN202110640064 A CN 202110640064A CN 113203790 A CN113203790 A CN 113203790A
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- G01N27/66—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode using wave or particle radiation to ionise a gas, e.g. in an ionisation chamber and measuring current or voltage
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Abstract
The present application relates to a gas detection device and method, the gas detection device of the present application includes: the ionization chamber is configured to enable light emitted by the light emitting component to be emitted into the ionization cavity so as to ionize gas to be detected in the ionization cavity; the measuring chamber is provided with an outlet hole channel which is communicated with the ionization cavity so as to enable the ionized gas to be measured to flow out; the first detection assembly comprises a collecting electrode and a bias electrode; the second detection assembly includes a first electrode, a second electrode, and a third electrode. Therefore, the gas measuring device has selectivity, the flow of the gas to be measured is controlled through the second detection assembly, the contents of different components in the gas to be measured are measured by utilizing different response sensitivities of the first detection assembly and the second detection assembly to the different components in the gas to be measured, the gas to be measured is measured in a targeted manner, and the accuracy of measuring the gas to be measured is improved.
Description
Technical Field
The application relates to the technical field of gas sensors, in particular to a gas detection device and a gas detection method.
Background
A Photo Ionization Detector (PID) is a very sensitive and versatile Detector that can detect Volatile Organic Compounds (VOCs) from very low concentrations of 10ppb (parts per billion) to higher concentrations of 10000ppm (1%) and other toxic gases. The device has the advantages of portability, high precision, high sensitivity, quick response, capability of continuous testing and the like, thereby being widely applied to the fields of industrial safety, environmental protection detection and the like.
The photoionization gas detector is characterized in that a gas to be detected absorbs photons emitted by an ultraviolet lamp and higher than the ionization energy of gas molecules, is ionized into positive ions and negative ions, and then the ions are shifted to form current under the action of an external electric field generated by a metal electrode with potential difference. The photoionization current is proportional to the concentration of VOC in the gas to be measured, and therefore the concentration of VOC in the gas to be measured is known from the detection current value.
However, in the prior art, the photoionization gas detector is not selective, and cannot be used for measuring the gas to be measured in a targeted manner, so that the accuracy of measuring the gas to be measured is improved. For example; when the gas to be measured is the mixed gas of benzene and toluene, the prior art cannot distinguish benzene from toluene and cannot select only to measure benzene.
Disclosure of Invention
The application aims to provide a gas detection device and a gas detection method, which have selectivity, can be used for measuring gas to be detected in a targeted manner, and improve the accuracy of measurement of the gas to be detected.
In order to achieve the above-mentioned objects,
in a first aspect, the present application provides a gas detection apparatus comprising: the ionization chamber comprises a light emitting component, an ionization chamber, a measuring chamber, a first detection component and a second detection component, wherein the light emitting component is used for emitting light; the ionization chamber is provided with an ionization cavity for containing gas to be measured, and is configured to enable light rays emitted by the light-emitting component to be emitted into the ionization cavity so as to ionize the gas to be measured in the ionization cavity; the measuring chamber is provided with an outlet hole passage penetrating through the measuring chamber, and the outlet hole passage is communicated with the ionization cavity so that ionized gas to be measured flows out; the first detection assembly comprises a collecting electrode and a bias electrode, and the collecting electrode and the bias electrode are arranged in the outlet pore channel and are used for detecting the ionized gas to be detected in the outlet pore channel; the second detection assembly comprises a first electrode, a second electrode and a third electrode, the first electrode is arranged in the ionization chamber and far away from the measurement chamber, and the second electrode is arranged in the measurement chamber and is positioned at one end of the outlet pore canal close to the ionization chamber; the third electrode is arranged in the measuring chamber and is positioned at one end of the outlet pore canal far away from the ionization chamber.
In one embodiment, the first electrode, the second electrode and the third electrode are parallel and arranged along the axial direction of the outlet channel. The first electrode is an anode, the second electrode and the third electrode are both cathodes, and the potential of the third electrode is consistent with that of the second electrode.
In one embodiment, the outlet duct is a straight duct arranged transversely, and the axial direction of the outlet duct is intersected with the direction of the light emitted by the light emitting component; the collecting electrode and the bias electrode are arranged on the inner wall of the outlet pore passage and are oppositely arranged.
In one embodiment, the second electrode is provided with at least one second opening, the third electrode is provided with at least one third opening, and the second opening and the third opening are used for communicating the outlet channel with the ionization chamber.
In one embodiment, the outlet duct is a vertically arranged straight duct, and the axial direction of the outlet duct is the same as the direction of the light emitted by the light emitting assembly; the measuring chamber and the light-emitting component are respectively positioned on two sides of the ionization chamber; the collecting electrode and the bias electrode are arranged on the inner wall of the outlet pore passage and are oppositely arranged.
In one embodiment, the second electrode is provided with at least one second opening, the third electrode is provided with at least one third opening, and the second opening and the third opening are used for communicating the outlet channel with the ionization chamber. The first electrode is provided with at least one first opening, and the first opening is used for enabling light emitted by the light-emitting component to be emitted into the ionization cavity.
In one embodiment, the gas detecting apparatus further includes: and the light shading piece is arranged between the light emitting component and the first electrode. The light shading piece is provided with a fourth opening, and the fourth opening is used for enabling light emitted by the light emitting component to be emitted into the ionization cavity.
In one embodiment, the gas detecting apparatus further includes: the shell body, ionization chamber, measuring chamber and light emitting component all are equipped with the blow vent on the shell body in locating the shell body.
In one embodiment, the gas detecting apparatus further includes: the waterproof ventilated membrane is arranged at the air vent.
In one embodiment, the gas detecting apparatus further includes: the filter screen is arranged at the air vent.
In one embodiment, a light emitting device includes: the ultraviolet lamp, the first driving electrode, the second driving electrode and the second isolating piece, wherein the first driving electrode is of an annular structure, is sleeved on the ultraviolet lamp and is electrically connected with the ultraviolet lamp; the second driving electrode is of an annular structure, is sleeved on the ultraviolet lamp and is electrically connected with the ultraviolet lamp; the second isolating piece is of an annular structure, is sleeved on the ultraviolet lamp and is clamped between the first driving electrode and the second driving electrode.
In one embodiment, the outer housing includes: the upper cover, the circuit bottom plate and the outer tube, and the vent hole is arranged on the upper cover; the two ends of the outer tube are respectively connected with the upper cover and the circuit bottom plate.
In one embodiment, the circuit bottom board is inserted with a circuit connecting board and a multiport connector, and the circuit connecting board is electrically connected with the first detection assembly and the second detection assembly;
in one embodiment, a plastic inner shell is disposed in the outer tube, a first bracket for fixing the measuring chamber and a lamp sleeve for mounting the ultraviolet lamp are disposed on the plastic inner shell, and a second bracket for fixing the first driving electrode, the second driving electrode and the second spacer is disposed on the lamp sleeve.
In one embodiment, the gas detecting apparatus further includes: and the voltage controller is electrically connected with the first detection assembly and the second detection assembly.
In a second aspect, the present application provides a gas detection method applied to the above gas detection apparatus, the gas detection method including:
acquiring first response sensitivity of a first detection assembly to different components in the gas to be detected and second response sensitivity of a second detection assembly to different components in the gas to be detected;
acquiring a first response current of a first detection assembly and a second response current of a second detection assembly;
and calculating to obtain the component concentration information of the gas to be detected according to the first response sensitivity, the second response sensitivity, the first response current and the second response current.
Compared with the prior art, the beneficial effect of this application is:
this application is through the flow of second determine module control gas that awaits measuring, and utilize first determine module and second determine module to measure the content of different components in the gas that awaits measuring in the response sensitivity difference of different components in the gas that awaits measuring, thereby carry out qualitative and quantitative analysis to complicated gas composition that awaits measuring, distinguish various compositions in the gas that awaits measuring, make this application have the selectivity, can pertinence ground measure the gas that awaits measuring, the accuracy of measuring the gas that awaits measuring has been improved, for example, when the gas that awaits measuring is benzene and toluene gas mixture, prior art can't distinguish benzene and toluene and can't select only to measure benzene, and this application can select only to measure benzene, also can select only to measure toluene, can also measure benzene concentration and toluene concentration in obtaining this gas mixture simultaneously.
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 an exploded view of a gas detection apparatus according to an embodiment of the present application.
Fig. 2 is an exploded view of a gas detection apparatus according to an embodiment of the present application.
Fig. 3 is a schematic structural diagram of a gas detection device according to an embodiment of the present application.
Fig. 4 is a perspective view of a gas detection device according to an embodiment of the present application.
Fig. 5 is a perspective view of a gas detection device according to an embodiment of the present application.
Fig. 6 is a schematic structural diagram of a gas detection device according to an embodiment of the present application.
Fig. 7 is a partial schematic structural diagram of a gas detection device according to an embodiment of the present application.
FIG. 8 is a schematic view of a measurement chamber according to an embodiment of the present application.
Icon: 100-a gas detection device; 200-an ionization chamber; 210-an ionization chamber; 210 b-the outer side wall of the ionization chamber; 210 c-the outer top wall of the ionization chamber; 210 d-an outer bottom wall of the ionization chamber; 210 e-an inner sidewall of the ionization chamber; 201-a first opening; 202-a second opening; 203-a third opening; 204-mounting grooves; 300-a light emitting assembly; 310-an ultraviolet lamp; 320-a first drive electrode; 330-a second drive electrode; 340-a second spacer; 400-a measurement chamber; 410-an outlet port; 510-a first detection component; 511-a collecting electrode; 512-bias electrode; 530-a second detection component; 531 — first electrode; 531 a-first opening; 532-a second electrode; 532 a-second opening; 533-third electrode; 533 a-third opening; 550-a circuit module; 560-a light-shielding member; 561-fourth opening; 600-an outer shell; 610-vent; 630-waterproof breathable film; 640-a filter screen; 601-upper cover; 602-an outer tube; 603-a circuit backplane; 604-plastic inner shell; 605-a first scaffold; 606-a lamp sleeve; 607-a second stent; 608-port connector; 609-circuit connection board; 700-voltage controller.
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 an exploded view of a gas detection apparatus 100 according to an embodiment of the present disclosure. The gas detection apparatus 100 includes: light emitting assembly 300, ionization chamber 200, measurement chamber 400, first detection assembly 510, and second detection assembly 530. The light emitting assembly 300 includes an ultraviolet lamp 310 for emitting light. The ionization chamber 200 and the measurement chamber 400 may be made of a material having light-shielding properties, such as opaque plastic, or may be made of a material having light-transmitting properties, such as glass or transparent plastic.
The ionization chamber 200 has an ionization chamber 210 for containing a gas to be measured, and the ionization chamber 200 is configured to enable light emitted by the light emitting element 300 to be emitted into the ionization chamber 210, so as to ionize the gas to be measured in the ionization chamber 210. In this embodiment, the ionization chamber 200 is a housing structure made of ceramic or PTFE material and having three openings, namely a first opening 201, a second opening 202 and a third opening 203.
Wherein the first opening 201 is provided at the outer sidewall 210b of the ionization chamber for communicating with the measurement chamber 400. A second opening 202 is provided in the outer top wall 210c of the ionization chamber for venting. The third opening 203 is disposed on the outer bottom wall 210d of the ionization chamber and is used for connecting with the light emitting element 300, and the light emitting end of the ultraviolet lamp 310 in the light emitting element 300 extends into the ionization chamber 210 through the third opening 203, so that the third opening 203 can be utilized to make the light emitted by the light emitting element 300 enter the ionization chamber 210. Wherein, a sealing ring can be arranged between the third opening 203 and the ultraviolet lamp 310 for preventing the gas to be measured from leaking.
The measuring chamber 400 is provided with an outlet hole 410 penetrating through the measuring chamber 400, and the outlet hole 410 is communicated with the ionization cavity 210 so as to enable the ionized gas to be measured to flow out; the outlet port 410 may be a straight port or a curved port.
The ionization chamber 200 and the measurement chamber 400 may be an integrally formed pipe structure, the ionization chamber 200 is a hollow cylinder, the measurement chamber 400 is a square pipe or a cylinder, and the axial length of the measurement chamber 400 is greater than that of the inlet pipe 650. The outlet duct 410 is a straight duct arranged transversely, and the axial direction of the outlet duct 410 intersects with the direction of the light emitted by the light emitting assembly 300. In this embodiment, the axial direction of the outlet duct 410 is perpendicular to the direction of the light emitted by the light emitting assembly 300. In another embodiment, the axial direction of the outlet channel 410 is inclined with respect to the direction of the light emitted by the light emitting device 300.
The first detecting assembly 510 includes a collecting electrode 511 and a bias electrode 512, both the collecting electrode 511 and the bias electrode 512 are of an integral structure, and both are disposed on the inner wall of the outlet duct 410, and are disposed in parallel, for detecting the gas to be detected after ionization in the outlet duct 410.
The second detection assembly 530 comprises a first electrode 531, a second electrode 532 and a third electrode 533, the first electrode 531 being arranged inside the ionization chamber 200 and being arranged remote from the measurement chamber 400; a second electrode 532 disposed within the measurement chamber 400 and at an end of the outlet channel 410 proximate to the ionization chamber 200; a third electrode 533 is disposed within the measurement chamber 400 and is located at an end of the outlet channel 410 remote from the ionization chamber 200.
The collecting electrode 511 is perpendicular to the first electrode 531, and the first electrode 531, the second electrode 532 and the third electrode 533 are parallel and arranged along the axial direction (from left to right) of the outlet duct 410.
The second electrode 532 is provided with at least one second opening 532a, the third electrode 533 is provided with at least one third opening 533a, and the second opening 532a and the third opening 533a are used for communicating the outlet channel 410 with the ionization chamber 210. In this embodiment, the second electrode 532 and the third electrode 533 have a ring structure, a semi-ring structure, or a porous honeycomb structure to facilitate ventilation. The second and third electrodes 532, 533 may be attached to the outlet port 410 by bonding, snapping, or embedding.
In order to reduce the chance of the first electrode 531 being irradiated by the ultraviolet light of the ultraviolet lamp 310, the first electrode 531 is embedded in the inner sidewall 210e of the ionization chamber through the groove.
The bias electrode 512 is an anode and is used for receiving electrons and/or negative ions formed after the gas to be detected is ionized; the collecting electrode 511 is a cathode and is used for receiving positive ions formed after the gas to be detected is ionized; a longitudinal first deflecting electric field may be formed between the collecting electrode 511 and the biasing electrode 512 to facilitate detection.
The first electrode 531 is an anode, and the second electrode 532 is a cathode. The first and second electrodes 531 and 532 may generate a transverse first accelerating electric field and are disposed in the same direction as the gas flow direction of the gas to be measured. In the present embodiment, the first accelerating electric field formed by the first electrode 531 and the second electrode 532 drives the electrons and the cations formed after the ionization of the gas to be measured in the ionization chamber 200 to move in an accelerating manner along the transverse direction.
The third electrode 533 is a cathode, and the potential of the third electrode 533 is equal to the potential of the second electrode 532, and the potential of the bias electrode 512 is higher than the second electrode 532. With such an arrangement, the transverse electric field generated between the second electrode 532 and the third electrode 533 is zero, electrons and cations formed after the gas to be measured is ionized move at a constant speed along the transverse direction after entering the measurement chamber 400, and the electrons and cations formed after the gas to be measured is ionized are driven by the first deflection electric field to deflect along the longitudinal direction.
In an operation process, when the gas to be detected enters the ionization chamber 200 from the second opening 202, the VOC gas molecules in the gas to be detected are irradiated by the ultraviolet lamp 310 and then dissociated into electrons and cations, the electrons move toward the first electrode 531 of the anode in an accelerated manner under the action of the first accelerating electric field, and the cations move toward the second electrode 532 of the cathode in an accelerated manner under the action of the first accelerating electric field. A portion of the cations will be captured by the second electrode 532 and a further portion of the cations will pass through the second electrode 532 into the measurement chamber 400 through the second aperture 532 a.
Since the potential of the third electrode 533 is the same as the potential of the second electrode 532, the positive ions accelerated by the first accelerating electric field move at a constant speed in the transverse direction after entering the measuring chamber 400, meanwhile, the electrons and the positive ions in the gas flow are deflected under the action of the first deflecting electric field, the positive ions flow to the collecting electrode 511 and are captured by the collecting electrode 511, the electrons flow to the biasing electrode 512 and are captured by the biasing electrode 512, and the residual gas flow and the residual electrons and positive ions can flow out through the third opening 533a of the third electrode 533.
Therefore, the present embodiment can extract two sets of measurement signals: one set is the signal from the second electrode 532 in the second sensing assembly 530, the second electrode 532 being responsive to all ions in the gas mixture, the efficiency of the second electrode 532 in capturing different ions being related to the voltage between the first and second electrodes 531, 532, the structure of the first and second electrodes 531, 532, and the mass-to-charge ratio of the ions; the other set is the signal from the collecting electrode 511, and the collecting electrode 511 has a different capture efficiency from the second electrode 532. Therefore, the present embodiment can selectively measure a certain component in the mixed gas by using the two sets of signals.
Furthermore, because the second detecting element 530 is designed to make the ions move at a constant speed in the direction perpendicular to the collecting electrode 511 and the biasing electrode 512 after entering the measuring chamber, and the speed is related to the first accelerating electric field, the present embodiment can control the first accelerating electric field by controlling the voltage of the second detecting element 530, so as to control the flow rate of the gas to be measured.
Specifically, the flow of the gas to be detected can be controlled by the second detection assembly 530, the contents of different components in the gas to be detected are measured by using different response sensitivities of the first detection assembly 510 and the second detection assembly 530 to the different components in the gas to be detected, so that qualitative and quantitative analysis is performed on the components of the complex gas to be detected, and various components in the gas to be detected are distinguished, so that the gas to be detected has selectivity, the gas to be detected can be measured specifically, and the accuracy of measurement on the gas to be detected is improved.
Fig. 2 is an exploded view of the gas detecting device 100 according to an embodiment of the present disclosure. The gas detection apparatus 100 further includes: the voltage controller 700, the voltage controller 700 is electrically connected to the first detecting element 510 and the second detecting element 530 for controlling the voltage. In one embodiment, the voltage controller 700 may further include a voltage sensor for detecting a voltage.
In one embodiment, the voltage controller 700 may control the voltage between the collecting electrode 511 and the bias electrode 512, between the first electrode 531 and the second electrode 532, and between the first electrode 531 and the third electrode 533 to be constant.
In an embodiment, the voltage controller 700 may also regulate and control the voltages between the collecting electrode 511 and the bias electrode 512, between the first electrode 531 and the second electrode 532, and between the first electrode 531 and the third electrode 533 to reach a specified voltage value, so as to flexibly adjust the voltages, thereby satisfying more complex measurement requirements.
Fig. 3 is a schematic structural diagram of a gas detection apparatus 100 according to an embodiment of the present disclosure. Please refer to fig. 4 and fig. 5, which are perspective views of a gas detecting apparatus 100 according to an embodiment of the present application from two viewing angles, respectively. The gas detection apparatus 100 further includes: the outer casing 600, the ionization chamber 200, the measuring chamber 400 and the light emitting assembly 300 are all arranged in the outer casing 600, and the top surface of the outer casing 600 is provided with a vent 610 communicated with the ionization chamber 210 and the outlet duct 410. The material of the outer case 600 may include plastic and metal. In this embodiment, the air vent 610 is communicated with the second opening 202 and the air outlet channel of the ionization chamber 200 through the air vent 610 having a shape of a large circular hole only provided at the top of the outer case 600, and is used for air outlet of the air inlet and outlet channels 410 of the ionization chamber 210.
The gas detection apparatus 100 further includes: a waterproof and breathable membrane 630 and a filter screen 640. The waterproof breathable membrane 630 and the filter screen 640 are both cylindrical, are arranged in the vent hole 610 at the top of the outer shell 600, and are in contact with the side wall of the ionization chamber 200 and the measurement chamber 400. The filter screen 640 is made of metal.
The light emitting device 300 includes an ultraviolet lamp 310, a first driving electrode 320, and a second driving electrode 330 electrically connected to each other. A second spacer 340 is interposed between the first driving electrode 320 and the second driving electrode 330. The first driving electrode 320, the second driving electrode 330 and the second spacer 340 are all ring structures, and are all sleeved on the ultraviolet lamp 310. The second spacer 340 is made of an insulating material such as rubber. In this embodiment, the first driving electrode 320 is a cathode, and the second driving electrode 330 is an anode.
The outer shell 600 comprises an upper cover 601, an outer tube 602 and a circuit bottom plate 603 which are connected in sequence, and the vent 610 is arranged on the upper cover 601; both ends of the outer tube 602 are connected to the upper cover 601 and the circuit board 603, respectively. A plastic inner shell 604 is arranged in the outer tube 602, a first support 605 for fixing the measuring chamber 400 is arranged on the plastic inner shell 604, a lamp sleeve 606 for mounting the ultraviolet lamp 310 is further arranged in the plastic inner shell 604, and a second support 607 for fixing the first driving electrode 320, the second driving electrode 330 and the second spacer 340 is arranged on the lamp sleeve 606. The material of the upper cover 601, the first bracket 605, the lamp sleeve 606 and the second bracket 607 may be plastic.
The Circuit Board 603 may be a Printed Circuit Board Assembly (PCBA), and the Circuit Board 603 may be plugged with other Circuit connection boards 609 and a multiport connector 608. The circuit module 550 is disposed on the circuit connection board 609, the circuit connection board 609 is electrically connected to the first detection assembly 510 and the second detection assembly 530 through the circuit module 550, and the circuit module 550 includes an amplification circuit and a signal processor.
In one embodiment, the gas detection apparatus 100 further comprises a control center including a communicator, a memory, a current sensor, a processor, and a human-computer interaction component, connected to the circuit module 550, the voltage controller 700, the first detection assembly 510, and the second detection assembly 530, for detecting the current.
Fig. 6 is a schematic structural diagram of a gas detection apparatus 100 according to an embodiment of the present disclosure. Fig. 7 is a schematic partial structure diagram of a gas detection apparatus 100 according to an embodiment of the present disclosure. The outlet duct 410 is a straight duct vertically arranged, and the axial direction of the outlet duct 410 is the same as the direction of the light emitted by the light emitting assembly 300; the measuring chamber 400 and the light emitting assembly 300 are respectively positioned at two sides of the ionization chamber 200; the collecting electrode 511 and the bias electrode 512 are disposed on the inner wall of the outlet channel 410 and are disposed oppositely.
The gas detection apparatus 100 further includes: the light shielding member 560 is disposed between the light emitting element 300 and the first electrode 531, and is used for shielding light, so as to reduce the risk of damage to the second detecting element 530 due to long-term irradiation of light emitted by the light emitting element 300, thereby prolonging the service life of the second detecting element 530, improving the accuracy of measurement, effectively reducing the baseline current, and improving the baseline stability of the gas detecting device 100.
The first electrode 531 is provided with at least one first opening 531a, the light shielding member 560 is provided with a fourth opening 561, and the first opening 531a and the fourth opening 561 are used for allowing the light emitted by the light emitting assembly 300 to enter the ionization chamber 210. In this embodiment, the light shielding member 560 may be made of a material capable of shielding ultraviolet light. The light shielding member 560, the first electrode 531, the second electrode 532, and the third electrode 533 are all annular perforated sheets, and have the same shape and size.
In this embodiment, the light shielding member 560, the first electrode 531, the second electrode 532, and the third electrode 533 have an outer diameter equal to an inner diameter of the outlet channel 410. In another embodiment, the light shielding member 560, the first electrode 531, the second electrode 532, and the third electrode 533 are not annular perforated sheets, but have a rounded shape, and have a partial structure with respect to a radial cross section of the outlet channel 410.
The second electrode 532 is provided with at least one second opening 532a, the third electrode 533 is provided with at least one third opening 533a, and the second opening 532a and the third opening 533a are used for communicating the outlet channel 410 with the ionization chamber 210.
In this embodiment, the vent 610 is connected to the outlet duct 410, and is used for both air inlet of the ionization chamber 210 and air outlet of the outlet duct 410, so that the gas can be measured in a diffusion mode, and the measurement accuracy is improved. The diffusion mode refers to that the gas to be measured diffuses from top to bottom, and ions move from bottom to top under the action of an electric field.
The ionization chamber 200 is a housing structure having two openings, a first opening 201 and a third opening 203.
Wherein a first opening 201 is provided in the outer top wall 210c of the ionization chamber for communication and venting with the measurement chamber 400. A third opening 203 is provided in the outer bottom wall 210d of the ionization chamber for connection to the light emitting assembly 300.
The inner diameter of the first opening 201 is smaller than the inner diameter of the third opening 203, forming a recess for mounting the uv lamp 310, and the inner diameter of the first opening 201 is smaller than the inner diameter of the outlet duct 410, forming a stepped surface for mounting the second electrode 532.
The inner side wall 210e of the ionization chamber is provided with a mounting groove 204, the light-shielding member 560 is tightly attached or adhered to the first electrode 531, and the light-shielding member 560 and the first electrode 531 are embedded in the inner side wall 210e of the ionization chamber through the mounting groove 204.
Please refer to fig. 8, which is a schematic diagram of a measurement chamber 400 according to an embodiment of the present disclosure. The measuring chamber 400 and the ionization chamber 200 are of a split structure and can be connected together in a bolt connection, welding or insertion connection mode and the like. The measuring chamber 400 is a square tube structure, the collecting electrode 511 is located above the bias electrode 512, and the collecting electrode 511 and the bias electrode 512 are attached to the inner wall of the outlet duct 410 by means of adhesion or embedding. The size of the transverse cross-section of the collecting electrode 511, the size of the transverse cross-section of the biasing electrode 512, and the size of the transverse cross-section of the measuring chamber 400 are the same.
The width of the transverse section of the outlet channel 410, the width of the transverse section of the collecting electrode 510 and the width of the transverse section of the biasing electrode 520 are all a, the length of the transverse section of the outlet channel 410, the length of the transverse section of the collecting electrode 510 and the length of the transverse section of the biasing electrode 520 are all L, and the distance between the collecting electrode 510 and the biasing electrode 520 and the height of the outlet channel 410 are all d.
The time required for the gas to be measured to pass through the outlet orifice 410 of the measurement chamber 400 can be calculated using equation (1):
wherein τ is the time required for the gas to be measured to pass through the outlet orifice 410 of the measurement chamber 400; V-adL is the volume of outlet port 410; ad is the cross-sectional area of the outlet duct 410 in the vertical gas flow direction; f is the gas volume flow after the gas to be measured enters the measuring chamber.
When any one of the embodiments of fig. 1 to 7 is adopted, since the ions enter the measurement chamber and then move at a constant speed in the direction perpendicular to the collecting electrode 511 and the bias electrode 512 through the structural design of fig. 1 to 7, the linear velocity v of the ions F and the ions in the gas to be measured entering the measurement chamber after being accelerated by the first accelerating electric field generated by the first electrode 531 and the second electrode 532 in the transverse directionsIt is related. In an ideal case, F ═ AvsThen, then
The field strength E of the electric field generated between the collecting electrode 511 and the biasing electrode 512 can be calculated using equation (2):
wherein U is a voltage applied between the collecting electrode 511 and the bias electrode 512; d is the distance between the collecting electrode 511 and the bias electrode 512.
The charged ions i include cations generated by ionization of the gas to be measured, and after the charged ions i are introduced into the measurement chamber 400 from the ionization chamber 200, the charged ions i are deflected under the action of an electric field generated between the collecting electrode 511 and the bias electrode 512, not all the ions are collected by the collecting electrode 511, wherein the charged ions i are collected by the collecting electrode 511 for a time tiIn relation to the vertical distance between the charged ions i and the collecting electrode 511 after entering the measurement chamber 400.
The time t required for the charged ions i to be collected by the collecting electrode 511iThe calculation can be performed using equation (3):
wherein m isiThe mass of charged ions i in the gas to be measured; q. q.siThe charged quantity of the charged ions i; u is the voltage applied between the collector electrode 511 and the bias electrode 512, yiThe perpendicular distance of the charged ions i from the collecting electrode 511.
As can be seen from the formula (3), the time required for the charged ions i near the collecting electrode 511 to be collected by the collecting electrode 511 is short, and the time required for the charged ions i far from the collecting electrode 511 to be collected is long. When the charged ion i is at a vertical distance y from the collecting electrode 511iIs equal to the distance d between the collecting electrode 511 and the bias electrode 512, i.e. yiWhen d, the time t required for the charged ions i to be collected by the collecting electrode 511iThe longest.
When the maximum time required for the charged ions i to be collected by the collecting electrode 511 is less than the time τ required for the gas to be measured to pass through the outlet port 410 of the measuring chamber 400, i.e., the time τ required for the charged ions i to be collected by the collecting electrode
At this time, all the charged ions i entering the measurement chamber 400 are collected by the collecting electrode 511, and the collecting electrode 511 has the highest collecting efficiency and the highest sensitivity.
When the maximum time required for the charged ions i to be collected by the collecting electrode 511 is longer than the time τ required for the gas to be measured to pass through the outlet port 410 of the measuring chamber 400, i.e., the time τ required for the charged ions i to be collected by the collecting electrode
At this time, only a part of the charged ions i entering the measuring chamber 400 is collected by the collecting electrode 511, and at this time, only the charged ions i are vertically spaced from the collecting electrode 511 by the vertical distance yiSatisfy the requirement of
Is collected, and the charged ions i are at a vertical distance y from the collecting electrode 511iSatisfy the requirement of
Is not collected.
The ion ratio of the charged ions i collected according to the above relationship can be calculated by using equation (4):
wherein R isiThe proportion of the charged ions i collected by the collecting electrode 511; y isi(τ) is the maximum distance charged ion i can be collected by the collecting electrode 511 from the electrode; m isiThe mass of charged ions i in the gas to be measured; q. q.siThe charged quantity of the charged ions i; u is the voltage applied between the collector electrode 511 and the bias electrode 512, yiThe perpendicular distance of the charged ions i from the collecting electrode 511.
In one embodiment, when F ═ AvsThen, then
R can be obtained from the formula (4)iIn relation to the mass-to-charge ratio of the charged ions i, the flow rate of the gas to be detected, the collection voltages applied in the first and second sensing elements 510 and 530, and the electrode structure design of the gas sensing device 100,under the condition that the structure of the gas detection apparatus 100 is fixed, the charged ions i with different mass-to-charge ratios are collected on the collecting electrode 511 in different proportions, so that the charged ions i with the smaller mass-to-charge ratio are collected more and the charged ions i with the larger mass-to-charge ratio are collected less.
The following conditions are satisfied in equation (4): (1) the ionization chamber 200 is separated from the measurement chamber 400 in the gas detection apparatus 100; (2) the gas to be measured flows through the measuring chamber 400 at a fixed flow rate; (3) the bias electrode 512 and the collecting electrode 511 are both vertical to the airflow direction of the gas to be measured; (4) the sizes of the structures of the bias electrode 512 and the collecting electrode 511 can be designed according to the characteristics of the gas to be measured; (5) the voltage between the bias electrode 512 and the collecting electrode 511 can be adjusted according to the characteristics of the gas to be measured.
The present application is designed by the structures of fig. 1 to 7, so that the above several conditions for the establishment of the fixed equation (4) are satisfied. Accordingly, on the premise that the structural design and the voltage of the fixed gas detection device 100 are fixed, the first detection component 510 and the second detection component 530 (such as the structures of fig. 1 to 7) can be used for measurement, so as to solve the concentration of different gases in the mixed gas, and realize the selective measurement of the target gas in the complex gas environment.
Therefore, the gas detection method can selectively measure the VOC gas according to the characteristics and can also measure the contents of different components in the mixed gas.
In an embodiment, the gas detection method may be applied to a control center of the gas detection apparatus 100, and the gas detection method includes the following steps:
the above-mentioned step S110 to step S130 will be described by taking the measurement of the mixed gas of benzene and toluene as an example.
Step S110: a first response sensitivity of the first detection element 510 to different components in the gas under test and a second response sensitivity of the second detection element 530 to different components in the gas under test are obtained.
Step S120: a first response current of the first sensing component 510 and a second response current of the second sensing component 530 are obtained.
Step S130: and calculating to obtain the component concentration information of the gas to be detected according to the first response sensitivity, the second response sensitivity, the first response current and the second response current.
When the device of the embodiment shown in fig. 1-5 is employed, the voltage controller 700 controls the voltages between the collecting electrode 511 and the biasing electrode 512, between the first electrode 531 and the second electrode 532, and between the first electrode 531 and the third electrode 533 to be constant. Two cations generated after benzene and toluene in the mixed gas are ionized by the ultraviolet lamp 310 are captured by the collecting electrode 511 and the second electrode 532, but the response sensitivities of the two cations are different, and the collecting electrode 511 and the second electrode 532 satisfy the following relation:
I301∶k301CC6H6+K301CC7H8 (5)
I302＝k302CC6H6+K302CC7H8 (6)
wherein, CC6H6To measure the benzene concentration in the gas, CC7H8To determine the concentration of toluene in the gas I301Is a first response current, k, of the collecting electrode 511301For a first response sensitivity, K, of the collecting electrode 511 to benzene301First response sensitivity, I, of the collecting electrode 511 to toluene on the left side, respectively302Is a second response current, k, of the second electrode 532302Is a second response sensitivity, K, of the second electrode 532 to benzene302Is the second response sensitivity of the second electrode 532 to toluene.
In this example, the collecting electrode 511 and the second electrode 532 capture part of benzene and toluene ions respectively, but the capturing ratio is different, and the ion amount of the gas to be measured after reaching the collecting electrode 511 changes to different degrees, which is represented as k301And K301The ratio is varied in different ways, so that the concentrations of benzene and toluene can be determined by simultaneous equations (5) and (6).
In the present example, the first response sensitivity in step S310 refers to k in formula (5)301And K301(ii) a The second response sensitivity refers to k in equation (6)302And K302，k301、K301、k302And K302The parameters can be known in advanceMeasured, tested or calculated. The first response current in step S320 refers to I in formula (5)301The second response current is I in formula (6)302，I301And I302May be measured during operation by a sensing means such as a current sensor. The component concentration information of the gas to be measured in step S330 refers to C in formula (5) and formula (6)C6HAnd CC7H. The constant collection voltage controlled by the voltage controller 700 is a known parameter and can be obtained by measuring, testing or calculating by applying the formula (4) in advance.
The gas to be measured may be a gas sample containing Volatile Organic Compounds (VOCs), among others.
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 detection apparatus, comprising:
a light emitting assembly for emitting light;
the ionization chamber is provided with an ionization cavity for containing gas to be detected, and the ionization chamber is configured to enable light rays emitted by the light emitting component to be emitted into the ionization cavity so as to ionize the gas to be detected in the ionization cavity;
the measuring chamber is provided with an outlet hole passage penetrating through the measuring chamber, and the outlet hole passage is communicated with the ionization cavity so as to enable the ionized gas to be measured to flow out;
the first detection assembly comprises a collecting electrode and a bias electrode, and the collecting electrode and the bias electrode are arranged in the outlet pore channel and are used for detecting the ionized gas to be detected in the outlet pore channel; and
the second detection assembly comprises a first electrode, a second electrode and a third electrode, the first electrode is arranged in the ionization chamber and is far away from the measurement chamber, and the second electrode is arranged in the measurement chamber and is positioned at one end of the outlet pore canal close to the ionization chamber; the third electrode is arranged in the measuring chamber and is positioned at one end of the outlet pore canal far away from the ionization chamber.
2. The gas detection apparatus according to claim 1, wherein the first electrode, the second electrode, and the third electrode are parallel and arranged along an axial direction of the outlet port;
the first electrode is an anode, the second electrode and the third electrode are both cathodes, and the potential of the third electrode is consistent with that of the second electrode.
3. The gas detection device according to claim 2, wherein the outlet duct is a straight duct arranged transversely, and an axial direction of the outlet duct intersects with a direction of the light emitted by the light emitting assembly; the collecting electrode and the bias electrode are arranged on the inner wall of the outlet pore passage and are oppositely arranged;
the second electrode is provided with at least one second opening, the third electrode is provided with at least one third opening, and the second opening and the third opening are used for communicating the outlet pore passage with the ionization cavity.
4. The gas detection device according to claim 2, wherein the outlet duct is a straight duct vertically arranged, and an axial direction of the outlet duct is the same as a direction of the light emitted by the light emitting assembly; the collecting electrode and the bias electrode are arranged on the inner wall of the outlet pore passage and are oppositely arranged; the measuring chamber and the light-emitting component are respectively positioned at two sides of the ionization chamber;
the ionization chamber comprises a first electrode, a second electrode, an ionization chamber and a light emitting component, wherein at least one first opening is formed in the first electrode, at least one second opening is formed in the second electrode, at least one third opening is formed in the third electrode, the second opening and the third opening are used for enabling the outlet hole channel to be communicated with the ionization chamber, and the first opening is used for enabling light emitted by the light emitting component to be emitted into the ionization chamber.
5. The gas detection apparatus of claim 4, further comprising:
the shading piece is arranged between the light emitting assembly and the first electrode;
and a fourth opening is formed in the light shading piece and used for enabling light rays emitted by the light emitting assembly to be emitted into the ionization cavity.
6. The gas detection apparatus according to any one of claims 1 to 5, further comprising:
the ionization chamber, the measuring chamber and the light-emitting component are all arranged in the outer shell, and a vent is arranged on the outer shell;
the waterproof breathable film is arranged on the air vent; and
the filter screen is arranged on the air vent.
7. The gas detection apparatus of claim 6, wherein the light emitting assembly comprises:
an ultraviolet lamp;
the first driving electrode is of an annular structure, sleeved on the ultraviolet lamp and electrically connected with the ultraviolet lamp;
the second driving electrode is of an annular structure, is sleeved on the ultraviolet lamp and is electrically connected with the ultraviolet lamp; and
the second isolating piece is of an annular structure, is sleeved on the ultraviolet lamp and is clamped between the first driving electrode and the second driving electrode.
8. The gas detection apparatus of claim 7, wherein the outer housing comprises:
the air vent is arranged on the upper cover;
the circuit bottom plate is inserted with a circuit connecting plate and a multi-port connector, and the circuit connecting plate is electrically connected with the first detection assembly and the second detection assembly;
the lamp sleeve is provided with a first support used for fixing the measuring chamber and a second support used for fixing the first driving electrode, the second driving electrode and the second isolating piece.
9. The gas detection apparatus of claim 1, further comprising:
and the voltage controller is electrically connected with the first detection assembly and the second detection assembly.
10. A gas detection method applied to the gas detection apparatus according to any one of claims 1 to 9, the gas detection method comprising:
acquiring first response sensitivity of the first detection assembly to different components in the gas to be detected and second response sensitivity of the second detection assembly to different components in the gas to be detected;
acquiring a first response current of the first detection assembly and a second response current of the second detection assembly;
and calculating to obtain the component concentration information of the gas to be detected according to the first response sensitivity, the second response sensitivity, the first response current and the second response current.
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|---|---|---|---|
| CN202110640064.8A CN113203790A (en) | 2021-06-08 | 2021-06-08 | Gas detection device and method |
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| CN202110640064.8A CN113203790A (en) | 2021-06-08 | 2021-06-08 | Gas detection device and method |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113793798A (en) * | 2021-10-13 | 2021-12-14 | 盛密科技(上海)有限公司 | Light emitting device and photoionization measuring apparatus |
| TWI794057B (en) * | 2022-03-17 | 2023-02-21 | 群邁通訊股份有限公司 | Device and method for gas measuring and system for air cleaning |
-
2021
- 2021-06-08 CN CN202110640064.8A patent/CN113203790A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113793798A (en) * | 2021-10-13 | 2021-12-14 | 盛密科技(上海)有限公司 | Light emitting device and photoionization measuring apparatus |
| TWI794057B (en) * | 2022-03-17 | 2023-02-21 | 群邁通訊股份有限公司 | Device and method for gas measuring and system for air cleaning |
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