CN100414290C - Safety door inspector based on photoionization detecting technology - Google Patents
Safety door inspector based on photoionization detecting technology Download PDFInfo
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- CN100414290C CN100414290C CNB2006100650611A CN200610065061A CN100414290C CN 100414290 C CN100414290 C CN 100414290C CN B2006100650611 A CNB2006100650611 A CN B2006100650611A CN 200610065061 A CN200610065061 A CN 200610065061A CN 100414290 C CN100414290 C CN 100414290C
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Abstract
The present invention discloses a safety door detection device based on a photoionization detector technology. The device comprises a vacuum pump, a preheating gas chamber, an electromagnetic valve, a photoionization detector, a digital display and a power supply system, wherein the gas inlet of the preheating gas chamber is communicated with the gas outlet of the vacuum pump, the gas outlet of the preheating gas chamber is communicated with a gas inlet pipeline of the photoionization detector through the electromagnetic valve, and the power supply system provides power for the vacuum pump, the preheating gas chamber, the electromagnetic valve, the photoionization detector and the digital display. The present invention can be used for detecting weak ions approximately reaching the order of magnitude of 10<-10> ampere, and the signal-to-noise ratio of a gas chromatogram of the gas to be detected is good. The present invention adopts unique technologies of sample injection and the preheating gas chamber, and the sensitivity of detecting organic volatile matter gas is enhanced. The power supply system adopts integrated design, and has the advantages of small interference, low noise and good system stability.
Description
Technical field
The present invention relates to a kind of chemical analysis instrument, specifically, relate to a kind of pick-up unit of trace organic substance class Hazardous Chemical Substances.
Background technology
As everyone knows, the detection of dangerous material is in the important effect of play more and more in actual life, and it is directly connected to personal safety and social stability.Existing safety detection device is not high enough to the accuracy of detection of organism class Hazardous Chemical Substances, is difficult to satisfy securities of system such as civil aviaton, railway and detects the needs that department is detected trace materials.
Portable photo-ionization detecting device (PID) is a kind of detecting instrument of working at normal temperatures and pressures.Its principle is: two parallel electrodes are placed in ionization chamber the inside, and the interpolar mutually insulated also is connected respectively to the positive and negative terminal of power supply high pressure.Vacuum pump gas suction detector after, detection lamp emission ultraviolet light in sensing chamber bombards gas molecule, make it ion and electronegative electronics that ionization is positively charged, under the electric field action of polarization pole plate, ion and electronics are respectively to the two poles of the earth drift, bump, the induced charge amount that causes the passive electrode plate changes, and can be detected faint gas current thereby form.According to this principle, can be made into free-air ionization chamber as shown in Figure 1.
But, because collecting plate directly is connected with power supply, power supply burns out amplifier easily on the one hand, and the various noises of power supply are added to the input end of micro current amplifier by the passive electrode plate on the other hand, useful signal influence to detection is very big, has weakened the sensitivity that detects.
In addition, because dangerous articles package is tight, the concentration of leakage is extremely low, and conventional input mode is difficult to satisfy the detection requirement, and therefore seeking suitable input mode just seems particularly urgent.
Summary of the invention
Technical matters to be solved by this invention just is to overcome and has the defective that collecting plate directly is connected with power supply in traditional photoionization detector, conventional input mode is difficult to adapt to the detection requirement now, and a kind of safety door detection device based on the photoionization detector technology is provided.
The technical solution adopted for the present invention to solve the technical problems is: a kind of safety door detection device based on the photoionization detector technology comprises vacuum pump, preheating air chamber, solenoid valve, photoionization detector, digital wash and power-supply system.The preheating air inlet of air chamber is communicated with the vacuum pump gas outlet, and preheating air chamber gas outlet is communicated with the photoionization detector admission line by solenoid valve, and power-supply system provides power supply for vacuum pump, preheating air chamber, solenoid valve photoionization detector and digital wash.
Described preheating air chamber adopts multilevel hierarchy, and the preheating gas chamber outer wall is a silica glass material, is tied with electrical heating wire outside it.
Described solenoid valve is a two-port valve, constitutes free-running multivibrator by 555 timers, produces cut-offfing of the adjustable drop-out voltage control electromagnetic valve of pulsewidth.
Described photoionization detector comprises vacuum UV lamp, photoionization chamber, combined electrode structure etc.; Photoionization chamber links to each other with admission line, outlet pipe respectively, and a vacuum pump has been installed on the outlet pipe; The photoionization chamber interior adopts combined electrode structure, comprise zero potential electrode plate, passive electrode plate and polarized potential battery lead plate, three battery lead plates are parallel to each other, the rectangular structure of proper alignment, and the passive electrode plate is between zero potential electrode plate and polarized potential battery lead plate; The passive electrode plate links to each other with micro current amplifier,, micro current amplifier both had been output to digital wash after the electric signal of collecting is amplified, and also can deliver to Computer Analysis and processing by data collecting card; Zero potential electrode plate links to each other with power supply ground, and the polarized potential battery lead plate links to each other with the negative pole of negative high voltage circuit, and polarizing voltage is less than-300V; Vacuum UV lamp is installed in a side of photoionization chamber, and the irradiation mouth is between zero potential electrode plate and passive electrode plate.
Dehumidifying and filtration unit are arranged on the described photoionization detector admission line, are respectively water absorbing agent silica gel, sponge coarse filtration layer, high-precision metal micro dust filter net, double medium filtration compound papery dirt bag and glass fibre air filter paper.
The zero potential electrode plate length of described photoionization chamber interior is 5～20mm, and width is 1～5mm, and thickness is 0.2～2.0mm.Passive electrode plate length is 5～20mm, and width is 1～5mm, and thickness is 0.2～2.0mm.Polarized potential battery lead plate length is 5～20mm, and width is 1～5mm, and thickness is 0.2～2.0mm.Spacing between zero potential electrode plate and the polarized potential battery lead plate is 3～8mm.Battery lead plate all adopts materials such as gold, silver, gold-plated, silver-plated or stainless steel.
The energy of photon that described vacuum UV lamp produces is 10.6 electron-volts, and wavelength is the ultraviolet light of 117 nanometers.
Described electric power system is input as the 220V alternating current, and by the AC-DC module, output ± 15V DC voltage is right; Pass through direct-current switch power supply, output+12V DC voltage simultaneously.AC-DC module output ± the 15V DC voltage is to directly linking to each other with the power input of micro current amplifier; AC-DC module output+the 15V DC voltage links to each other with negative high voltage power source small modules power input and boosts to-1500V, and this output voltage is connected to uviol lamp by the resistance of a 1.5M Ω; The output of AC-DC module+the 15V DC voltage is through the LM7805CV chip, and output+5V DC voltage is for digital wash provides operating voltage.Direct-current switch power supply output+the 12V DC voltage is respectively electrical heating wire, 555 timers and the solenoid valve that vacuum pump, quartz glass twine outward.
Principle of work of the present invention is:
When article to be measured pass through monitor station, if the dangerous material in the inside, then it can be evacuated to first order air chamber and carry out elementary preheating by the big pump of powerful suction cleaner, then by first order solenoid control, enters the places level preheating of going forward side by side of second level air chamber by vacuum pump.Because taked absorption, concentrate and added the dimethyl siloxane film in second level air chamber inflow point, so second level air chamber has improved the concentration of gas to be measured, quantity can improve about 10～100.By second level solenoid control, gas to be measured enters ionization chamber again.
Gas to be measured enters ionization chamber, by VUV emission ultraviolet light gas molecule is bombarded, and makes organic molecule ionization wherein become ion and electronics.Under the electric field action of polarization pole plate, ion and electronics clash into to pole plate, and formation can be by the detected faint gas current of high sensitivity micro current amplifier.After current signal is zoomed into voltage signal by the high sensitivity micro current amplifier, under the master control of MCU (single-chip microcomputer), sample through data collecting card, both voltage signal can be converted to the corresponding concentration value according to matched curve and deliver to display unit, also can send into computing machine, utilize chromatographic work station that measurement result is analyzed and handled by the I/O interface.
The present invention adopts vacuum UV lamp as ionization source, produces the photon of 10.6ev, can ionization ionization energy be lower than the molecule of 10.6ev, but can not ionization N
2, O
2Be higher than the molecule of 10.6ev with ionization energy such as water vapour, significantly reduced the kind that ion produces, obtain gem-pure determinand spectrogram, thereby strengthened the sensitivity that detects and the degree of stability of work.In addition, organic volatile gas can not destroy the structure and the character of original gas because after the vacuum UV lamp photoionization, meeting is compound to original state.
Designing requirement to ionization chamber is: the big measurement volumes of trying one's best and the little electrode separation of trying one's best, also to consider suitable voltage across poles.Because ionization organic volatile compound generation positive and negative ion is right in the ionization chamber, positive and negative ion moves to the two poles of the earth under the Electrode Field effect, forms output current signal at external circuit.According to theory of electrolytic dissociation, the charge collection efficiency of ionization chamber reduces and increases with electrode separation d's, and increases and collect voltage and can improve collection efficiency (but overtension can increase the expense of power supply.)
General ionization chamber die opening just can make the ionization chamber collection efficiency reach more than 99% greater than the polarizing voltage of 200V when 3～8mm.In addition, according to Gauss's Law in the electric field and the constitutive relation in the medium, can derive an important conclusions, that is: collecting plate can be done greatly in theory, can produce more electric charge q like this, so that improve the sensitivity of ionization chamber.
The invention has the beneficial effects as follows and adopt the design of PID ionization chamber, have integrated, microminiaturized and modular characteristics, highly versatile, highly sensitive and detection threshold is low; Detect faint ion and can reach 10
-10The order of magnitude of ampere, the gas chromatogram signal to noise ratio (S/N ratio) of gas to be measured is good; Adopt unique preheating air chamber technology, the material of micro-concentrations is kept temperature and concentrated, also adopted solenoid closure to increase the preheating air chamber pressure, solenoid valve is connected to the ionization chamber sample introduction, improves the sensitivity of organic volatile gas detection greatly.Power-supply system adopts integrated design, disturb little, noise is low, has improved the reliability and stability of system works.
Description of drawings
Fig. 1 is free-air ionization chamber's illustraton of model.
Fig. 2 is the photoionization detector structural representation.
Fig. 3 is a photoionization detector ionization chamber horizontal section structural drawing.
Fig. 4 is a photoionization detector ionization chamber longitudinal profile structural drawing.
Fig. 5 is the VUV lamp ionization chamber embodiment vertical with the gas circuit direction.
Fig. 6 is the VUV lamp ionization chamber embodiment parallel with the gas circuit direction.
Fig. 7 is a principle of work block diagram of the present invention.
Fig. 8 is the workflow diagram of one embodiment of the invention.
Embodiment
The present invention is further described below in conjunction with drawings and Examples.
As depicted in figs. 1 and 2, vacuum pump 14 is detectable gas 6 suction, enter photoionization chamber 10 through admission line 12, vacuum UV lamp 3 emission ultraviolet lights bombard gas molecule, and making it ionization is the ion 7 and the electronegative electronics 8 of positively charged, polarization pole plate 1,2 electric field action under, ion 7 and electronics 8 drift about to the two poles of the earth respectively, and bump the two poles of the earth 1,2, cause that the induced charge amount of collecting plate 11 changes, can be detected faint gas current thereby form.After current signal is zoomed into voltage signal by high sensitivity micro current amplifier 4, enter and analyze and processing unit 5.Gas recombination after having detected is discharged through outlet pipe 13 to original state gas 9.
The present invention has adopted photoionization chamber 10 as shown in Figure 3, between polarized potential battery lead plate 1 and the zero potential electrode plate 2 is 7 millimeters apart from d1, between passive electrode plate 11 and the zero potential electrode plate 2 is 5 millimeters apart from d2, voltage difference U between polarized potential battery lead plate 1 and the zero potential electrode plate 2 is 300 volts, E ≈ 4.286 * 10
4Volt/rice, potential difference (PD) is about 214.3 volts between passive electrode plate 11 and the zero potential electrode plate 2.
The ionization light source that the present invention adopts adopts vacuum UV lamp 3, and its energy that produces photon is 10.6ev, and respective wavelength is 117 nanometers.Zero potential electrode plate 2 ground connection, passive electrode plate 11 is unsettled not to be contacted with other pole plate, and polarized potential battery lead plate 1 attachment belongs to negative high voltage-1500 that power supply provides volt.Collecting board electrode 11 links to each other with micro current amplifier 4, when vacuum pump 14 with outside gas to be measured continuously when admission line 12 sucks, gas at first will be through the metal filter screen that adheres on the draft tube road junction 12 with dehumidifying, blocks dust and foreign matter; Gas enters photoionization chamber 10 then, under the irradiation of vacuum UV lamp 3 ionization takes place.Negative ions moves along direction of an electric field between zero potential electrode plate and the passive electrode plate approximately under-300 volts the polarized electric field effect, forms faint ionization current to collecting board electrode 11 bumps, and the size of this signal characterizes the concentration of the interior test substance of detecting device.Signal can output to oscillograph, display and multimeter and observe after high sensitivity micro current amplifier 4 amplifies, or handles by the platforms such as chromatographic work station that data collecting card is delivered to computer-internal.
The ionization chamber that the present invention adopts is a cylindrical shape, middle parallel placement nickel sheet or pure stainless steel substrates, as shown in Figure 4.There is an admission line 12 ionization chamber 45 lower ends, there is an outlet pipe 13 side, in electrode stem 46 is arranged, ionization chamber 45 is positioned at ionization chamber outer cover 47, vacuum UV lamp 3 is positioned at ionization chamber 45 upper ends, and there are pad 15 and 44 in the centre, and a stainless steel sleeve 41 is arranged outside the vacuum UV lamp 3, the centre is separated with a poly-tetrafluoro circle 42, by the total fastening bolt 43 on the stainless steel sleeve 41 vacuum UV lamp 3 and ionization chamber 45 is fixed in the cavity of stainless steel sleeve 41 and ionization chamber outer cover 47 formations.For improving sensitivity and ion collection efficient, the volume of cylinder should be suitably a little bit smaller, and diameter is 20 millimeter.
Because the light path of ultraviolet light beam is about 10mm, if the VUV lamp is vertical with the gas circuit direction, as shown in Figure 5, can cause ultraviolet light beam light path scope to be confined in the limited distance from the lamp surface to the ionization chamber locular wall (we adopt be about 3mm), the efficient of ionization can be very not high.If the ultraviolet light beam is parallel with the gas circuit direction, as shown in Figure 6, the probability that gas molecule can ionization is greatly increased.
Fig. 7 is a principle of work block diagram of the present invention.Described electric power system always is input as the 220V alternating current, and by AC-DC module U1, output ± 15V DC voltage is right; Pass through direct-current switch power supply U10, output+12V DC voltage simultaneously.± 15V DC voltage is to directly linking to each other with the power input of micro current amplifier U3.+ 15V DC voltage pair links to each other with negative high voltage power source small modules U2 power input and boosts to-1500V, and this output voltage is connected to uviol lamp U5 by the resistance of a 1.5M Ω.+ 15V direct current crimping LM7805CV chip input generation+5V DC voltage, U9 provides operating voltage for digital wash.Direct-current switch power supply U10 output+the 12V DC voltage is respectively electrical heating wire U7,555 timers, solenoid valve U6, vacuum pump U8 and the U4 power supply that quartz glass twines outward.
Fig. 8 is the workflow diagram of one embodiment of the invention.When article to be measured pass through monitor station, if the dangerous material in the inside, then it can be evacuated to first order air chamber and carry out elementary preheating by the big pump of powerful suction cleaner, then by first order solenoid control, enters the places level preheating of going forward side by side of second level air chamber by vacuum pump.Second level air chamber inflow point has taked absorption, concentrated and has added the dimethyl siloxane film, improve the concentration of gas to be measured at second level air chamber after, enter ionization chamber by second level solenoid control gas to be measured again.
Claims (10)
1. the safety door detection device based on the photoionization detector technology comprises vacuum pump, preheating air chamber, solenoid valve, photoionization detector and power-supply system; It is characterized in that: the preheating air inlet of air chamber is communicated with the vacuum pump gas outlet, preheating air chamber gas outlet is communicated with the photoionization detector admission line by solenoid valve, and power-supply system provides power supply for vacuum pump, preheating air chamber, solenoid valve and photoionization detector, digital indicator.
2. a kind of safety door detection device based on the photoionization detector technology according to claim 1 is characterized in that: described preheating air chamber adopts multilevel hierarchy, and the preheating gas chamber outer wall is a silica glass material, is tied with electrical heating wire outside it.
3. a kind of safety door detection device according to claim 1 based on the photoionization detector technology, it is characterized in that: described solenoid valve is a two-port valve, constitute free-running multivibrator by 555 timers, produce cut-offfing of the adjustable drop-out voltage control electromagnetic valve of pulsewidth.
4. a kind of safety door detection device according to claim 1 based on the photoionization detector technology, it is characterized in that: described photoionization detector comprises vacuum UV lamp, photoionization chamber, combined electrode structure; Photoionization chamber links to each other with admission line, outlet pipe respectively, and a vacuum pump has been installed on the outlet pipe; The photoionization chamber interior adopts combined electrode structure, comprise zero potential electrode plate, passive electrode plate and polarized potential battery lead plate, three battery lead plates are parallel to each other, the rectangular structure of proper alignment, and the passive electrode plate is between zero potential electrode plate and polarized potential battery lead plate; The passive electrode plate links to each other with micro current amplifier, and micro current amplifier both had been output to digital wash after the electric signal of collecting is amplified, and also can deliver to Computer Analysis and processing by data collecting card; The zero potential electrode plate earthing, the polarized potential battery lead plate links to each other with the negative pole of negative high voltage circuit, and polarizing voltage is less than-300V; Vacuum UV lamp is installed in a side of photoionization chamber, and the irradiation mouth is between zero potential electrode plate and passive electrode plate.
5. according to claim 1 or 4 described a kind of safety door detection devices based on the photoionization detector technology, it is characterized in that: be separately installed with dehydrating unit and filtration unit on the described photoionization detector admission line, wherein dehydrating unit is a water absorbing agent silica gel, and filtration unit is sponge coarse filtration layer, high-precision metal micro dust filter net, double medium filtration compound papery dirt bag and glass fibre air filter paper.
6. a kind of safety door detection device based on the photoionization detector technology according to claim 4 is characterized in that: the zero potential electrode plate length of described photoionization chamber interior is 5～20mm, and width is 1～5mm, and thickness is 0.2～2.0mm; Passive electrode plate length is 5～20mm, and width is 1～5mm, and thickness is 0.2～2.0mm; Polarized potential battery lead plate length is 5～20mm, and width is 1～5mm, and thickness is 0.2～2.0mm; Spacing between zero potential electrode plate and the polarized potential battery lead plate is 3～8mm; Battery lead plate all adopts gold, silver, gold-plated, silver-plated or stainless steel material.
7. a kind of safety door detection device based on the photoionization detector technology according to claim 4 is characterized in that: it is that 10.6 electron-volts, wavelength are the ultraviolet light of 117 nanometers that described vacuum UV lamp produces photon energy.
8. a kind of safety door detection device according to claim 1 based on the photoionization detector technology, it is characterized in that: described electric power system is input as the 220V alternating current, right by AC-DC module output ± 15V DC voltage, simultaneously by direct-current switch power supply generation+12V DC voltage.
9. a kind of safety door detection device based on the photoionization detector technology according to claim 8 is characterized in that: AC-DC module output ± the 15V DC voltage is to directly linking to each other with the power input of micro current amplifier; AC-DC module output+the 15V DC voltage links to each other with negative high voltage power source small modules power input and boosts to-1500V, and this output voltage is connected to uviol lamp by the resistance of a 1.5M Ω; The output of AC-DC module+the 15V DC voltage is through the LM7805CV chip, and output+5V DC voltage is for digital wash provides operating voltage.
10. a kind of safety door detection device based on the photoionization detector technology according to claim 8 is characterized in that: the output of described direct-current switch power supply+the 12V DC voltage is respectively electrical heating wire, 555 timers and the solenoid valve that vacuum pump, quartz glass twine outward.
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| CNB2006100650611A CN100414290C (en) | 2006-03-17 | 2006-03-17 | Safety door inspector based on photoionization detecting technology |
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| CNB2006100650611A CN100414290C (en) | 2006-03-17 | 2006-03-17 | Safety door inspector based on photoionization detecting technology |
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| CN100414290C true CN100414290C (en) | 2008-08-27 |
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Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101592628B (en) * | 2009-06-30 | 2014-10-15 | 上海华质生物技术有限公司 | Device and method for increasing photoionization efficiency |
| CN101887042B (en) * | 2009-07-21 | 2012-11-07 | 上海工程技术大学 | Multifunctional environment simulation test chamber for on-line detecting textile material total organic volatile |
| CN105140095A (en) * | 2015-07-30 | 2015-12-09 | 安徽中杰信息科技有限公司 | One-dimensional structure diffusion ionization chamber for photoionization detection of volatile gas |
| CN109752232B (en) * | 2017-11-06 | 2023-11-07 | 广州禾信仪器股份有限公司 | Gas-solid separation device |
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| US5220284A (en) * | 1991-03-13 | 1993-06-15 | Asea Brown Boveri Ltd. | Method and device for measuring the concentration of particles in a gas by ionization of the particles |
| US5773833A (en) * | 1996-03-22 | 1998-06-30 | Rae Systems, Inc. | Photo-ionization detector for volatile gas measurement |
| EP0995989A1 (en) * | 1998-10-22 | 2000-04-26 | Rae Systems, Inc. | Photo-ionization detector for volatile gases |
| JP2003066008A (en) * | 2001-05-29 | 2003-03-05 | Rae Systems Inc | Photoionization detector and method for continuous operation and real time self cleaning |
| US20030137306A1 (en) * | 2002-01-24 | 2003-07-24 | Dolgov Boris N. | Plug-in photoionization sensor |
| CN1456882A (en) * | 2003-05-19 | 2003-11-19 | 北京清科园环境科技有限公司 | Photoionization gas analyzer (gas chromatograph) |
| US20040080321A1 (en) * | 2002-10-24 | 2004-04-29 | Reavell Kingsley St. John | Electrostatic particle measurement |
-
2006
- 2006-03-17 CN CNB2006100650611A patent/CN100414290C/en not_active Expired - Fee Related
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5220284A (en) * | 1991-03-13 | 1993-06-15 | Asea Brown Boveri Ltd. | Method and device for measuring the concentration of particles in a gas by ionization of the particles |
| US5773833A (en) * | 1996-03-22 | 1998-06-30 | Rae Systems, Inc. | Photo-ionization detector for volatile gas measurement |
| EP0995989A1 (en) * | 1998-10-22 | 2000-04-26 | Rae Systems, Inc. | Photo-ionization detector for volatile gases |
| JP2003066008A (en) * | 2001-05-29 | 2003-03-05 | Rae Systems Inc | Photoionization detector and method for continuous operation and real time self cleaning |
| US20030137306A1 (en) * | 2002-01-24 | 2003-07-24 | Dolgov Boris N. | Plug-in photoionization sensor |
| US20040080321A1 (en) * | 2002-10-24 | 2004-04-29 | Reavell Kingsley St. John | Electrostatic particle measurement |
| CN1456882A (en) * | 2003-05-19 | 2003-11-19 | 北京清科园环境科技有限公司 | Photoionization gas analyzer (gas chromatograph) |
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