CN115561302B - Intelligent gas detection system - Google Patents
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- 238000001514 detection method Methods 0.000 title claims abstract description 17
- 238000004891 communication Methods 0.000 claims abstract description 10
- 239000003990 capacitor Substances 0.000 claims description 56
- RAHZWNYVWXNFOC-UHFFFAOYSA-N Sulphur dioxide Chemical compound O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 abstract description 54
- 239000007789 gas Substances 0.000 description 42
- 150000002500 ions Chemical class 0.000 description 14
- 230000005684 electric field Effects 0.000 description 7
- 238000001914 filtration Methods 0.000 description 7
- 238000004804 winding Methods 0.000 description 7
- 238000010586 diagram Methods 0.000 description 6
- 230000003321 amplification Effects 0.000 description 4
- 230000008859 change Effects 0.000 description 4
- 238000003199 nucleic acid amplification method Methods 0.000 description 4
- 230000010355 oscillation Effects 0.000 description 4
- 230000009471 action Effects 0.000 description 3
- 230000008901 benefit Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000001824 photoionisation detection Methods 0.000 description 2
- 238000003915 air pollution Methods 0.000 description 1
- JRPBQTZRNDNNOP-UHFFFAOYSA-N barium titanate Chemical compound [Ba+2].[Ba+2].[O-][Ti]([O-])([O-])[O-] JRPBQTZRNDNNOP-UHFFFAOYSA-N 0.000 description 1
- 229910002113 barium titanate Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 230000020169 heat generation Effects 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 238000011897 real-time detection Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 239000007784 solid electrolyte Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/62—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
- G01N27/64—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
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/0004—Gaseous mixtures, e.g. polluted air
- G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
- G01N33/0027—General constructional details of gas analysers, e.g. portable test equipment concerning the detector
- G01N33/0036—General constructional details of gas analysers, e.g. portable test equipment concerning the detector specially adapted to detect a particular component
- G01N33/0042—SO2 or SO3
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/0004—Gaseous mixtures, e.g. polluted air
- G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
- G01N33/0062—General constructional details of gas analysers, e.g. portable test equipment concerning the measuring method or the display, e.g. intermittent measurement or digital display
- G01N33/0067—General constructional details of gas analysers, e.g. portable test equipment concerning the measuring method or the display, e.g. intermittent measurement or digital display by measuring the rate of variation of the concentration
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04Q—SELECTING
- H04Q9/00—Arrangements in telecontrol or telemetry systems for selectively calling a substation from a main station, in which substation desired apparatus is selected for applying a control signal thereto or for obtaining measured values therefrom
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
- H05B41/14—Circuit arrangements
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04Q—SELECTING
- H04Q2209/00—Arrangements in telecontrol or telemetry systems
- H04Q2209/80—Arrangements in the sub-station, i.e. sensing device
- H04Q2209/84—Measuring functions
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Abstract
The invention relates to the technical field of gas detection, and provides an intelligent gas detection system which comprises a light ion gas sensor, a control unit, a communication unit, an ultraviolet driving circuit and a signal receiving circuit, wherein the light ion gas sensor comprises a bias electrode, an ionization chamber, a collecting electrode and an ultraviolet lamp, the input end of the ultraviolet driving circuit is connected with the control unit, the output end of the ultraviolet driving circuit is connected with the ultraviolet lamp, the input end of the signal receiving circuit is connected with the collecting electrode, the output end of the signal receiving circuit is connected with the control unit, and the control unit is connected with an upper computer by means of the communication unit. Through above-mentioned technical scheme, the problem that among the prior art sulfur dioxide gas concentration detector receives the gaseous interference of other components, precision low easily has been solved.
Description
Technical Field
The invention relates to the technical field of gas detection, in particular to an intelligent gas detection system.
Background
While the industry and economy of China are developed at a high speed, people use a large amount of energy such as petroleum and coal to cause more and more harmful gas emission, and the problem of environmental pollution is obvious. In recent years, the national concern about air environment pollution is increasing, and a new requirement is also put forward for ecological environment construction in the fourteen-five planning outline. Sulfur dioxide is a common pollutant gas, which has great influence on human life and health in the aspects of air pollution, ecological environment, safety of food and the like. The real-time detection of sulfur dioxide is a prerequisite for the control and treatment thereof.
The traditional sulfur dioxide gas concentration detector mainly comprises a solid electrolyte type, a barium titanate composite oxide capacitance type, a conductivity change type thick film type and the like, and the detection modes have many defects, such as easy interference from other component gases, low precision, frequent calibration, short service life and the like.
Disclosure of Invention
The invention provides an intelligent gas detection system, which solves the problems that a sulfur dioxide gas concentration detector in the prior art is easily interfered by other component gases and has low precision.
The technical scheme of the invention is as follows:
an intelligent gas detection system comprises a light ion gas sensor, a control unit, a communication unit, an ultraviolet drive circuit and a signal receiving circuit,
the light ion gas sensor comprises a bias electrode, an ionization chamber, a collecting electrode and an ultraviolet lamp, the input end of an ultraviolet driving circuit is connected with the control unit, the output end of the ultraviolet driving circuit is connected with the ultraviolet lamp, the input end of a signal receiving circuit is connected with the collecting electrode, the output end of the signal receiving circuit is connected with the control unit, the control unit is connected with an upper computer by means of the communication unit,
the ultraviolet driving circuit comprises a resistor R1, a resistor R2, a triode Q1, a triode Q2, a triode Q3, an inductor L1 and a transformer T1, wherein a base electrode of the triode Q3 is connected with the control unit through the resistor R2, a collector electrode of the triode Q3 is connected with a VCC power supply, an emitter electrode of the triode Q3 is connected with a first end of a first primary coil of the transformer T1, a base electrode of the triode Q1 is connected with an emitter electrode of the triode Q3 through the resistor R1, a base electrode of the triode Q1 is connected with a first end of a second primary coil of the transformer T1, a collector electrode of the triode Q1 is connected with a second end of the first primary coil of the transformer T1, an emitter electrode of the triode Q1 is connected with a first end of the inductor L1, a base electrode of the triode Q2 is connected with a second end of the second primary coil of the transformer T1, a collector electrode of the triode Q2 is connected with a third end of the first primary coil of the transformer T1, a second end of the inductor L1 is grounded, a second end of the transformer T1 is connected with a secondary coil of the ultraviolet lamp, and a secondary coil of the transformer T1 is connected with a ground.
Further, the signal receiving circuit comprises a resistor R7, an operational amplifier U3 and a resistor R13, wherein the first end of the resistor R7 is connected with the collecting electrode, the second end of the resistor R7 is connected with the non-inverting input end of the operational amplifier U3, the inverting input end of the operational amplifier U3 is grounded, the output end of the operational amplifier U3 is connected with the inverting input end of the operational amplifier U3 through the resistor R13, and the output end of the operational amplifier U3 is connected with the control unit.
Further, the signal receiving circuit further comprises a resistor R3, a resistor R5, a rheostat RP1 and an operational amplifier U4, wherein a first end of the resistor R3 is connected to an output end of the operational amplifier U3, a second end of the resistor R3 is connected to a non-inverting input end of the operational amplifier U4, an inverting input end of the operational amplifier U4 is grounded through the resistor R5, an output end of the operational amplifier U4 is connected to a first end of the rheostat RP1, a second end of the rheostat RP1 is connected to an inverting input end of the operational amplifier U4, and an output end of the operational amplifier U4 is connected to the control unit.
Further, the signal receiving circuit of the present invention further includes a resistor R4, a resistor R6, a capacitor C4, an operational amplifier U5, a capacitor C5, a resistor R11, a resistor R12, a capacitor C6, and a capacitor C7, wherein a first end of the resistor R4 is connected to an output end of the operational amplifier U4, a second end of the resistor R4 is connected to a non-inverting input end of the operational amplifier U5 through the resistor R6, a first end of the capacitor C5 is connected to a non-inverting input end of the operational amplifier U5, a second end of the capacitor C5 is grounded, a non-inverting input end of the operational amplifier U5 is connected to a second end of the resistor R4 through the capacitor C4, an output end of the operational amplifier U5 is connected to a non-inverting input end of the operational amplifier U5, an output end of the operational amplifier U5 is connected to a first end of the resistor R11, a second end of the resistor R11 is connected to a first end of the resistor R12, a first end of the capacitor C6 is connected to a first end of the resistor R12, a second end of the capacitor C7 is connected to a second end of the control unit, and the capacitor C7 is grounded.
Further, the signal receiving circuit further comprises a resistor R8, a resistor R9, a resistor R10 and an operational amplifier U6, wherein the first end of the resistor R8 is connected with the output end of the operational amplifier U5, the second end of the resistor R8 is connected with the non-inverting input end of the operational amplifier U6, the inverting input end of the operational amplifier U6 is grounded through the resistor R9, the output end of the operational amplifier U6 is connected with the inverting input end of the operational amplifier U6 through the resistor R10, and the output end of the operational amplifier U6 is connected with the first end of the resistor R11.
Further, the invention further comprises a bias circuit, wherein the bias circuit comprises a boosting module U1, an inductor L2, a capacitor C2 and a capacitor C8, the input end of the boosting module U1 is connected with a 12V power supply, the output end of the boosting module U1 is connected with the first end of the inductor L2, the second end of the inductor L2 is connected with the bias electrode, the first end of the capacitor C2 is connected with the first end of the inductor L2, the second end of the capacitor C2 is grounded, the first end of the capacitor C8 is connected with the first end of the inductor L2, and the second end of the capacitor C8 is grounded.
The working principle and the beneficial effects of the invention are as follows:
in the invention, the control unit sends an instruction to the ultraviolet driving circuit, the ultraviolet driving circuit outputs a high-voltage driving signal to the ultraviolet lamp after receiving the instruction, then the ultraviolet lamp sends out ultraviolet light, and the offset electrode is used for generating an electric field. The sulfur dioxide gas enters from the upper end of the ionization chamber in a diffusion mode and is discharged from the lower end of the ionization chamber. Sulfur dioxide diffuses to the ionization chamber, and sulfur dioxide gas is irradiated by the ultraviolet lamp in the ionization chamber, wherein organic gas molecules with ionization energy lower than photon energy are ionized after absorbing the photon energy to form positive ions and electrons. The positive ions are absorbed by an ion collecting electrode in the ionization chamber under the action of an electric field, so that weak current is formed. The concentration of the sulfur dioxide gas is in direct proportion to the formed current, and the higher the concentration of the sulfur dioxide gas is, the larger the current formed on the collecting electrode is. Then the current is converted into a voltage signal by the signal receiving circuit and is amplified and then is sent to the control unit. The control unit converts the voltage value into a concentration value corresponding to the sulfur dioxide gas, the concentration value is sent to an upper computer through the communication unit, and relevant workers can check the change of the concentration of the sulfur dioxide gas in real time through the upper computer.
Specifically, the operating principle of the ultraviolet driving circuit is as follows: when the control unit sends a low level to the base of the triode Q3, the triode Q3 is turned off, and the primary coil of the transformer T1 is disconnected from the power supply VCC, so that the ultraviolet lamp 4 does not emit light.
When the control unit sends a high level signal to the base of the triode Q3, the triode Q3 is conducted, and at the moment, the primary coil of the transformer T1 is connected with the power supply VCC. The triode Q1, the triode Q2, the inductor L1 and the primary coil of the transformer T1 form a self-oscillation circuit, and the self-oscillation circuit generates a high-voltage alternating current signal at the secondary coil LC of the transformer T1 to excite the ultraviolet lamp 4 to emit light.
The current flows from the power supply voltage VCC to the inductor L1 through the first primary coil LB of the transformer T1, the triode Q1 or the triode Q2 in sequence, and then flows to the ground from the inductor L1, so that the circuit starts oscillation. The current through the first primary winding LB of the transformer T1 is selected to flow into the two sub-windings LB1 and LB2 of the first primary winding LB of the transformer T1 depending on the conduction of the transistor Q1 or the transistor Q2.
Since the directions of the induced currents through the two sub-coils are opposite, the polarities of the voltages generated at the secondary coil LC of the transformer T1 and the second primary coil (feedback coil LA) of the transformer T1 are opposite. The first end and the second end of the second primary coil (feedback coil LA) of the transformer T1 are respectively connected to the bases of the transistor Q1 and the transistor Q2, and the conduction of the transistor Q1 and the transistor Q2 is determined by the current passing through the bases. In addition, the base of the transistor Q1 is connected to VCC through a resistor R1, so that Q1 is turned on if no current flows through the second primary winding (feedback winding LA) of the transformer T1.
When the triode Q1 is turned on, the gradually increased current in the sub-coil LB1 of the first primary coil LB of the transformer T1 induces a current in the second primary coil (feedback coil LA) of the transformer T1, which turns off the triode Q1 and turns on the triode Q2; when the transistor Q2 is turned on, the gradually increasing current of the sub-coil LB2 of the first primary coil LB of the transformer T1 induces a current in the feedback coil LA in a direction opposite to that of the current when the transistor Q1 is turned on, and the current turns off the transistor Q2 and turns on the transistor Q1. Therefore, the triode Q1 and the triode Q2 are periodically switched on and off with a phase difference of 180 °, so that the currents of the two sub-coils LB1 and LB2 of the first primary coil LB of the transformer T1 are changed, and finally, an alternating voltage is induced at the secondary coil LC of the transformer T1 to excite the ultraviolet lamp to emit light. The capacitor C1 determines the frequency of the conduction and the cut-off of the transistor Q1 and the transistor Q2, thereby further controlling the oscillation frequency.
The invention detects the gas to be detected by a photoionization detection technology. Compared with the traditional sulfur dioxide gas concentration detector, the sulfur dioxide concentration detector has the advantages of stable performance, high precision and small size.
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
Drawings
FIG. 1 is a block diagram of the present invention;
FIG. 2 is a circuit diagram of the UV driver circuit of the present invention;
FIG. 3 is a circuit diagram of a signal receiving circuit according to the present invention;
FIG. 4 is a circuit diagram of an amplifying circuit according to the present invention;
FIG. 5 is a circuit diagram of a filter circuit according to the present invention;
FIG. 6 is a circuit diagram of a bias circuit of the present invention.
In the figure: 1. bias electrode, 2, ionization chamber, 3, collection electrode, 4, ultraviolet lamp, 5, light ion gas sensor.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any inventive step, are intended to be within the scope of the present invention.
Example 1
As shown in fig. 1-2, this embodiment provides an intelligent gas detection system, which includes a photo-ion gas sensor 5, a control unit, a communication unit, an ultraviolet driving circuit and a signal receiving circuit, where the photo-ion gas sensor 5 includes a bias electrode 1, an ionization chamber 2, a collecting electrode 3 and an ultraviolet lamp 4, an input end of the ultraviolet driving circuit is connected to the control unit, an output end of the ultraviolet driving circuit is connected to the ultraviolet lamp 4, an input end of the signal receiving circuit is connected to the collecting electrode 3, an output end of the signal receiving circuit is connected to the control unit, the control unit is connected to an upper computer by the communication unit, the ultraviolet driving circuit includes a resistor R1, a resistor R2, a triode Q1, a triode Q2, a triode Q3, an inductor L1 and a transformer T1, a base of the triode Q3 is connected to the control unit through the resistor R2, the VCC power is connected to triode Q3's collecting electrode, the first end of the first primary coil of transformer T1 is connected to triode Q3's projecting pole, triode Q1's base passes through resistance R1 and connects triode Q3's projecting pole, the first end of transformer T1 second primary coil is connected to triode Q1's base, the second end of the first primary coil of transformer T1 is connected to triode Q1's collecting electrode, inductance L1's first end is connected to triode Q1's projecting pole, the second end of transformer T1 second primary coil is connected to triode Q2's base, the third end of the first primary coil of transformer T1 is connected to triode Q2's collecting electrode, inductance L1's first end is connected to triode Q2's projecting pole, inductance L1's second end ground connection, ultraviolet lamp 4 is connected to transformer T1 secondary coil's first end, transformer T1 secondary coil's second end ground connection.
When sulfur dioxide is detected, the control unit sends an instruction to the ultraviolet driving circuit, the ultraviolet driving circuit outputs a high-voltage driving signal to the ultraviolet lamp 4 after receiving the instruction, then the ultraviolet lamp 4 sends out ultraviolet light, and the offset electrode 1 is used for generating an electric field. The sulfur dioxide gas enters from the upper end of the ionization chamber 2 in a diffused manner and is discharged from the lower end of the ionization chamber 2. Sulfur dioxide diffuses towards the ionization chamber 2, where it is irradiated by the ultraviolet lamp, where organic gas molecules with ionization energy lower than photon energy are ionized after absorbing the photon energy, forming positive ions and electrons. The positive ions are absorbed by the ion collecting electrode 3 in the ionization chamber 2 under the action of the electric field, so that a weak current is formed. The concentration of the sulfur dioxide gas is in direct proportion to the magnitude of the formed current, and the higher the concentration of the sulfur dioxide gas is, the larger the current formed at the collecting electrode 3 is. Then the current is converted into a voltage signal by the signal receiving circuit, amplified and sent to the control unit. The control unit converts the voltage value into a concentration value corresponding to the sulfur dioxide gas, the concentration value is sent to the upper computer through the communication unit, and relevant workers can check the change of the sulfur dioxide gas concentration in real time through the upper computer.
Specifically, the operating principle of the ultraviolet driving circuit is as follows: when the control unit sends a low level to the base of the triode Q3, the triode Q3 is turned off, and the primary coil of the transformer T1 is disconnected from the power supply VCC, so that the ultraviolet lamp 4 does not emit light.
When the control unit sends a high level signal to the base electrode of the triode Q3, the triode Q3 is conducted, and at the moment, the primary coil of the transformer T1 is connected with the power supply VCC. The triode Q1, the triode Q2, the inductor L1 and the primary coil of the transformer T1 form a self-oscillation circuit, and the self-oscillation circuit generates a high-voltage alternating-current signal at the secondary coil LC of the transformer T1 to excite the ultraviolet lamp 4 to emit light.
The current flows from the power supply voltage VCC to the inductor L1 through the first primary coil LB of the transformer T1, the triode Q1 or the triode Q2 in sequence, and then flows to the ground from the inductor L1, so that the circuit starts oscillation. The current passing through the first primary coil LB of the transformer T1 is determined by the conduction of the transistor Q1 or the transistor Q2 to select the two sub-coils LB1 and LB2 flowing into the first primary coil LB of the transformer T1.
Since the directions of the induced currents through the two sub-coils are opposite, the polarities of the voltages generated at the secondary coil LC of the transformer T1 and the second primary coil (feedback coil LA) of the transformer T1 are opposite. The first end and the second end of the second primary coil (feedback coil LA) of the transformer T1 are respectively connected to the base electrodes of the transistor Q1 and the transistor Q2, and the conduction of the transistor Q1 and the transistor Q2 is determined by the current of the first primary coil and the second primary coil. In addition, the base of the transistor Q1 is connected to VCC through a resistor R1, so that Q1 is turned on if no current flows through the second primary winding (feedback winding LA) of the transformer T1.
When the triode Q1 is turned on, the gradually increased current in the sub-coil LB1 of the first primary coil LB of the transformer T1 induces a current in the second primary coil (feedback coil LA) of the transformer T1, which turns off the triode Q1 and turns on the triode Q2; when the transistor Q2 is turned on, the gradually increasing current of the sub-coil LB2 of the first primary coil LB of the transformer T1 induces a current in the feedback coil LA in a direction opposite to that of the current when the transistor Q1 is turned on, and the current turns off the transistor Q2 and turns on the transistor Q1. Therefore, the transistor Q1 and the transistor Q2 are periodically turned on and off with a phase difference of 180 °, so that the currents of the two sub-coils LB1 and LB2 of the first primary coil LB of the transformer T1 change, and finally an alternating voltage is induced at the secondary coil LC of the transformer T1 to excite the ultraviolet lamp 4 to emit light. The capacitor C1 determines the frequency of the conduction and the cut-off of the transistor Q1 and the transistor Q2, thereby further controlling the oscillation frequency.
In this embodiment, the control unit uses an LPC1758 chip.
The photoionization gas sensor 5 detects a gas to be detected by a photoionization detection technique. The light ion gas sensor 5 adopts an ultraviolet lamp 4 as a light source, the detected gas is introduced into the ionization chamber 2, and is irradiated by the ultraviolet lamp 4 to be ionized into detectable signals, namely electrons and ions. The electric field created by the biasing electrode 1 forces the electrons and ions to drift towards the respective electrodes to form a current. Compare traditional sulfur dioxide gas concentration detector, this embodiment has the advantage that the performance is stable, and the precision is high, and is small.
As shown in fig. 3, in this embodiment, the signal receiving circuit includes a resistor R7, an operational amplifier U3 and a resistor R13, the first end of the resistor R7 is connected to the collecting electrode 3, the second end of the resistor R7 is connected to the non-inverting input terminal of the operational amplifier U3, the inverting input terminal of the operational amplifier U3 is grounded, the output terminal of the operational amplifier U3 is connected to the inverting input terminal of the operational amplifier U3 through the resistor R13, and the output terminal of the operational amplifier U3 is connected to the control unit.
The current signal formed on the collecting electrode 3 is converted into a voltage signal through the resistor R7, and then the voltage signal is added to the non-inverting input end of the operational amplifier U3, the operational amplifier U3 forms a voltage follower, the purpose is to improve the stability of the circuit, and the resistor R13 is used for impedance matching. And finally, sending the electric signal output by the operational amplifier U3 to a control unit. Wherein, resistance R7 and electric capacity C3 constitute low pass filter circuit for the high frequency clutter signal on the filtering collection electrode 3 makes the signal of telecommunication more stable that obtains.
As shown in fig. 4, the signal receiving circuit of this embodiment further includes a resistor R3, a resistor R5, a varistor RP1, and an operational amplifier U4, wherein a first end of the resistor R3 is connected to an output end of the operational amplifier U3, a second end of the resistor R3 is connected to a non-inverting input end of the operational amplifier U4, an inverting input end of the operational amplifier U4 is grounded through the resistor R5, an output end of the operational amplifier U4 is connected to a first end of the varistor RP1, a second end of the varistor RP1 is connected to an inverting input end of the operational amplifier U4, and an output end of the operational amplifier U4 is connected to the control unit.
The current signal formed on the collecting electrode 3 is very weak, the operational amplifier U3 mainly functions to realize impedance matching of the front and rear stages, and does not have a good gain amplification effect, so that if the output value of the operational amplifier U3 is directly sent to the control unit, an expected detection effect cannot be obtained. Therefore, an amplifying circuit is added between the operational amplifier U3 and the control unit.
The resistor R3, the resistor R5, the rheostat RP1 and the operational amplifier U4 form an amplifying circuit, and the amplification factor can be changed by adjusting the resistance value of the rheostat RP 1.
As shown in fig. 5, in this embodiment, the signal receiving circuit further includes a resistor R4, a resistor R6, a capacitor C4, an operational amplifier U5, a capacitor C5, a resistor R11, a resistor R12, a capacitor C6 and a capacitor C7, a first end of the resistor R4 is connected to an output end of the operational amplifier U4, a second end of the resistor R4 is connected to a non-inverting input end of the operational amplifier U5 through the resistor R6, a first end of the capacitor C5 is connected to a non-inverting input end of the operational amplifier U5, a second end of the capacitor C5 is grounded, a non-inverting input end of the operational amplifier U5 is connected to a second end of the resistor R4 through the capacitor C4, an output end of the operational amplifier U5 is connected to a non-inverting input end of the operational amplifier U5, an output end of the operational amplifier U5 is connected to a first end of the resistor R11, a second end of the resistor R11 is connected to a first end of the resistor R12, a first end of the capacitor C6 is connected to a first end of the resistor R12, a second end of the capacitor C6 is grounded, a second end of the resistor R12 is connected to a control unit, a first end of the capacitor C7 is grounded.
The current signal formed on the collecting electrode 3 is converted into a voltage signal, and then the voltage signal corresponding to the concentration of sulfur dioxide is formed after impedance matching and amplification, but the signal contains a large amount of noise signals, and if the amplified voltage signal is directly sent to the control unit, the detection precision of the concentration of sulfur dioxide gas is seriously influenced. Therefore, in order to obtain a more accurate sulfur dioxide gas concentration signal, a filter circuit is added between the operational amplifier U4 and the control unit to filter noise interference.
In the embodiment, filtering processing is performed by adopting a mode of matching active filtering and passive filtering, wherein a resistor R4, a resistor R6, a capacitor C4, an operational amplifier U5 and a capacitor C5 form a preceding-stage active second-order low-pass filter circuit; the resistor R11, the resistor R12, the capacitor C6 and the capacitor C7 form a rear-stage passive second-order low-pass filter circuit. The active second-order low-pass filter circuit firstly carries out primary noise reduction processing, then the passive second-order low-pass filter circuit carries out high-capacity filtering, and finally the filtered electric signal is sent to the control unit. After the two-stage filtering treatment, useless signals in the output signals of the operational amplifier U4 can be filtered, and the useful signals are reserved, so that the detection precision of the concentration of the sulfur dioxide gas is improved.
As shown in fig. 5, in this embodiment, the signal receiving circuit further includes a resistor R8, a resistor R9, a resistor R10 and an operational amplifier U6, the first end of the resistor R8 is connected to the output end of the operational amplifier U5, the second end of the resistor R8 is connected to the non-inverting input end of the operational amplifier U6, the inverting input end of the operational amplifier U6 is grounded through the resistor R9, the output end of the operational amplifier U6 is connected to the inverting input end of the operational amplifier U6 through the resistor R10, and the output end of the operational amplifier U6 is connected to the first end of the resistor R11.
Because the current signal formed on the collecting electrode 3 is very weak, the amplification factor of an amplifying circuit formed by the operational amplifier U4 is very high, the resistance value of the feedback resistor (the rheostat RP 1) is very high, the noise signal introduced when the resistance value of the feedback resistor is too high is increased, meanwhile, when the feedback resistor is too large, the requirement on the precision of the resistor is greatly increased, and the detection precision of the sulfur dioxide gas concentration is influenced if the precision of the feedback resistor cannot be met.
Therefore, in order to reduce the pressure of an amplifying circuit formed by the operational amplifier U4, a second-stage amplifying circuit is added between the active second-order low-pass filter circuit and the passive second-order low-pass filter circuit, the resistor R8, the resistor R9, the resistor R10 and the operational amplifier U6 form the second-stage amplifying circuit, and a voltage signal output by the operational amplifier U4 is finally sent to the control unit after filtering-amplifying-filtering.
As shown in fig. 6, the present embodiment further includes a bias circuit, the bias circuit includes a boost module U1, an inductor L2, a capacitor C2, and a capacitor C8, an input end of the boost module U1 is connected to the 12V power supply, an output end of the boost module U1 is connected to the first end of the inductor L2, the second end of the inductor L2 is connected to the bias electrode 3, the first end of the capacitor C2 is connected to the first end of the inductor L2, the second end of the capacitor C2 is grounded, the first end of the capacitor C8 is connected to the first end of the inductor L2, and the second end of the capacitor C8 is grounded.
The bias circuit is used for providing high-voltage bias voltage for the bias electrode 1 in the ionization chamber 2 to form an electric field, and ions and electrons generated by ionizing gas molecules to be detected under the action of the electric field respectively move towards the collecting electrode 3 to form weak ion current. It can be seen that the bias circuit plays an important role in the formation of the current.
In order to improve the charge collection efficiency of the ionization chamber 2, the voltage between the electrode plates needs to be sufficiently large, so that the voltage boosting module U1 in this embodiment is a 5V-200VDC-DC voltage boosting module WRB12200MD with small heat generation, high efficiency and small volume.
A large ripple is superimposed on the output voltage of the boost module U1, and therefore a filter circuit needs to be connected to filter the output voltage. Because the boost module WRB12200MD has weak load capacity and small current, an LC filter circuit is connected to the output end of the boost module U1 to filter the output voltage of the boost module. The capacitor C2, the inductor L2 and the capacitor C8 form an LC filter circuit.
The present invention is not limited to the above preferred embodiments, and any modifications, equivalent substitutions, improvements, etc. within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (3)
1. An intelligent gas detection system is characterized by comprising a light ion gas sensor (5), a control unit, a communication unit, an ultraviolet drive circuit and a signal receiving circuit,
the light ion gas sensor (5) comprises a bias electrode (1), an ionization chamber (2), a collecting electrode (3) and an ultraviolet lamp (4), the input end of the ultraviolet drive circuit is connected with the control unit, the output end of the ultraviolet drive circuit is connected with the ultraviolet lamp (4), the input end of the signal receiving circuit is connected with the collecting electrode (3), the output end of the signal receiving circuit is connected with the control unit, the control unit is connected with an upper computer by means of the communication unit,
the ultraviolet driving circuit comprises a resistor R1, a resistor R2, a triode Q1, a triode Q2, a triode Q3, an inductor L1 and a transformer T1, wherein the base of the triode Q3 is connected with the control unit through the resistor R2, the collector of the triode Q3 is connected with a VCC power supply, the emitter of the triode Q3 is connected with the first end of the first primary coil of the transformer T1, the base of the triode Q1 is connected with the emitter of the triode Q3 through the resistor R1, the base of the triode Q1 is connected with the first end of the second primary coil of the transformer T1, the collector of the triode Q1 is connected with the second end of the first primary coil of the transformer T1, the emitter of the triode Q1 is connected with the first end of the inductor L1, the base of the triode Q2 is connected with the second end of the second primary coil of the transformer T1, the collector of the triode Q2 is connected with the third end of the first primary coil of the transformer T1, the emitter of the triode Q2 is connected with the first end of the inductor L1, the second end of the inductor L1 is grounded, the second end of the transformer T1 is connected with the secondary coil of the transformer T1, the second end of the transformer T1 is connected with the secondary coil of the transformer T4, and the transformer T1 is grounded, and the secondary end of the secondary coil of the transformer T1 is connected with the transformer T1,
the signal receiving circuit comprises a resistor R7, an operational amplifier U3 and a resistor R13, wherein the first end of the resistor R7 is connected with the acquisition electrode (3), the second end of the resistor R7 is connected with the non-inverting input end of the operational amplifier U3, the inverting input end of the operational amplifier U3 is grounded, the output end of the operational amplifier U3 is connected with the inverting input end of the operational amplifier U3 through the resistor R13, the output end of the operational amplifier U3 is connected with the control unit,
the signal receiving circuit further comprises a resistor R3, a resistor R5, a rheostat RP1 and an operational amplifier U4, wherein the first end of the resistor R3 is connected with the output end of the operational amplifier U3, the second end of the resistor R3 is connected with the non-inverting input end of the operational amplifier U4, the inverting input end of the operational amplifier U4 is grounded through the resistor R5, the output end of the operational amplifier U4 is connected with the first end of the rheostat RP1, the second end of the rheostat RP1 is connected with the inverting input end of the operational amplifier U4, the output end of the operational amplifier U4 is connected with the control unit,
the signal receiving circuit further comprises a resistor R4, a resistor R6, a capacitor C4, an operational amplifier U5, a capacitor C5, a resistor R11, a resistor R12, a capacitor C6 and a capacitor C7, wherein the first end of the resistor R4 is connected with the output end of the operational amplifier U4, the second end of the resistor R4 is connected with the in-phase input end of the operational amplifier U5 through the resistor R6, the first end of the capacitor C5 is connected with the in-phase input end of the operational amplifier U5, the second end of the capacitor C5 is grounded, the inverting input end of the operational amplifier U5 is connected with the second end of the resistor R4 through the capacitor C4, the output end of the operational amplifier U5 is connected with the inverting input end of the operational amplifier U5, the output end of the operational amplifier U5 is connected with the first end of the resistor R11, the second end of the resistor R11 is connected with the first end of the resistor R12, the first end of the capacitor C6 is connected with the first end of the resistor R12, the second end of the capacitor C6 is grounded, the second end of the resistor R12 is connected with the second end of the control unit, the second end of the capacitor C7 is connected with the second end of the resistor R7.
2. The intelligent gas detection system according to claim 1, wherein the signal receiving circuit further comprises a resistor R8, a resistor R9, a resistor R10 and an operational amplifier U6, wherein a first end of the resistor R8 is connected to an output end of the operational amplifier U5, a second end of the resistor R8 is connected to a non-inverting input end of the operational amplifier U6, an inverting input end of the operational amplifier U6 is grounded through the resistor R9, an output end of the operational amplifier U6 is connected to an inverting input end of the operational amplifier U6 through the resistor R10, and an output end of the operational amplifier U6 is connected to a first end of the resistor R11.
3. The intelligent gas detection system according to claim 1, further comprising a bias circuit, wherein the bias circuit comprises a voltage boost module U1, an inductor L2, a capacitor C2, and a capacitor C8, an input terminal of the voltage boost module U1 is connected to a 12V power supply, an output terminal of the voltage boost module U1 is connected to the first terminal of the inductor L2, the second terminal of the inductor L2 is connected to the bias electrode, the first terminal of the capacitor C2 is connected to the first terminal of the inductor L2, the second terminal of the capacitor C2 is grounded, the first terminal of the capacitor C8 is connected to the first terminal of the inductor L2, and the second terminal of the capacitor C8 is grounded.
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Denomination of invention: An intelligent gas detection system Granted publication date: 20230303 Pledgee: Cangzhou Bank Co.,Ltd. Luanzhou Branch Pledgor: HEBEI XUNHUI TECHNOLOGY CO.,LTD. Registration number: Y2024980021401 |
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