CN109884167B - Ionization chamber and spiral path miniature photoionization detection device - Google Patents
Ionization chamber and spiral path miniature photoionization detection device Download PDFInfo
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- CN109884167B CN109884167B CN201910232913.9A CN201910232913A CN109884167B CN 109884167 B CN109884167 B CN 109884167B CN 201910232913 A CN201910232913 A CN 201910232913A CN 109884167 B CN109884167 B CN 109884167B
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- 238000001824 photoionisation detection Methods 0.000 title claims abstract description 11
- 230000005684 electric field Effects 0.000 claims abstract description 12
- 239000002184 metal Substances 0.000 claims abstract description 5
- 229910052751 metal Inorganic materials 0.000 claims abstract description 5
- 238000001914 filtration Methods 0.000 claims description 3
- 150000002500 ions Chemical class 0.000 abstract description 13
- 239000000463 material Substances 0.000 abstract description 4
- 238000000034 method Methods 0.000 abstract description 4
- 238000000752 ionisation method Methods 0.000 abstract description 3
- 239000007789 gas Substances 0.000 description 28
- 230000003321 amplification Effects 0.000 description 3
- 238000001514 detection method Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000003199 nucleic acid amplification method Methods 0.000 description 3
- 238000007791 dehumidification Methods 0.000 description 2
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 2
- 239000010931 gold Substances 0.000 description 2
- 229910052737 gold Inorganic materials 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 229910001220 stainless steel Inorganic materials 0.000 description 2
- 239000010935 stainless steel Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 229910001635 magnesium fluoride Inorganic materials 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- -1 polytetrafluoroethylene Polymers 0.000 description 1
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 1
- 239000004810 polytetrafluoroethylene Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000011896 sensitive detection Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
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- Other Investigation Or Analysis Of Materials By Electrical Means (AREA)
Abstract
The invention discloses an ionization chamber and a spiral path miniature photoionization detection device, wherein the ionization chamber comprises a cavity type shell, a sheet-shaped grounding electrode and a voltage electrode which are correspondingly arranged at the top and the bottom in the shell, and a gas channel which is fixedly arranged in the shell and is correspondingly communicated with the outside, wherein the gas channel is made of a light-transmitting material and is plated with a metal film at the lower half part of the inner wall surface of the gas channel to be used as a collecting plate. Ultraviolet light and an electric field are simultaneously applied in a gas molecule flow path to be detected, and the area of a lighting area and the area of a collecting plate 8 are increased through a spiral gas channel 7, so that the collecting efficiency is greatly increased. In the ionization chamber 2, the ultraviolet light and the applied electric field can act on the VOC molecules at the same time, so that the ionization process and the ion deflection process of the VOC molecules are almost performed at the same time, which will avoid that positive ions are combined with electrons without striking on the acquisition plate.
Description
Technical Field
The invention belongs to the technical field of photoionization detection, and particularly relates to an ionization chamber and a spiral path miniature photoionization detection device.
Background
The principle of a photoionization detector (PID) is that ultraviolet rays are generated by utilizing the vacuum discharge phenomenon of inert gas, and VOC molecules in gas molecules to be detected absorb photons to generate ionization, so that positively charged ions and electrons are generated. In the ionization chamber, ions and electrons rapidly move to the metal electrode under the action of an externally applied electric field, a micro-current signal is generated between the two electrodes, and the concentration of an organic substance is obtained by detecting the amplified current signal through a weak signal amplifying circuit. The photoionization detector (PID) for TVOC detection is a very sensitive detection element, so that it is required to eliminate the influence of electromagnetic interference, humidity, dust as much as possible, and to improve the VOC molecular discharge rate and collection efficiency.
The existing photoionization detector (PID) almost adopts ionization first, and then generated positively charged ions and electrons are introduced into an ionization chamber, so that partial positively charged ions and electrons are combined before entering the ionization chamber to generate no microcurrent signals, meanwhile, charged particles in the existing detector have short passing path in an electric field and too small area of a collection plate, so that the ions cannot move onto the collection plate, and the collection efficiency is greatly reduced.
In addition, the conventional photoionization detectors (PID) are often of an integrated structure, and are troublesome to maintain when the instrument is in a state.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a spiral micro photoionization detection device, which improves the detection effect.
The invention is realized by the following technical scheme:
The ionization chamber comprises a cavity type shell, a sheet-shaped grounding electrode and a voltage electrode which are correspondingly arranged at the top and the bottom in the shell, and a gas channel which is fixedly arranged in the shell and is correspondingly communicated with the outside, wherein the gas channel is made of a light-transmitting material and is plated with a metal film on the lower half part of the inner wall surface of the gas channel to serve as a collecting plate.
In the above technical scheme, the gas channel comprises a planar spiral section and an L-shaped leading-out section.
In the above technical scheme, the top of casing be provided with ultraviolet lamp mounting hole, with the earth that the mounting hole corresponds on be provided with a plurality of light trap.
In the above technical scheme, the shell comprises a main body with an opening at one side and a side cover fixedly connected with the main body, and two ends of the gas channel are correspondingly fixed on the side cover.
In the above technical solution, the gas channel is made of MgF 2.
In the above technical scheme, slots are respectively arranged at the top and the bottom of the shell to position the grounding electrode and the voltage electrode, or the grounding electrode and the voltage electrode are correspondingly inlaid in the shell.
In the above technical solution, an electromagnetic shielding net is disposed in the housing to shield interference of external electric field.
A spiral path miniature photoionization detection device comprises an ionization chamber, an ultraviolet lamp fixedly connected with the ionization chamber, a dehumidification device and a filter device arranged between the air pump and an air inlet of a gas channel, and a micro-current amplification circuit electrically communicated with a collection plate.
In the technical scheme, the ultraviolet lamp is in threaded connection with the shell.
In the technical scheme, the signal processing circuit of the micro-current amplifying circuit adopts a PCB double-layer layout.
The invention has the advantages and beneficial effects that:
Ultraviolet light and an electric field are simultaneously applied in a gas molecule flow path to be detected, and the area of a lighting area and the area of a collecting plate 8 are increased through a spiral gas channel 7, so that the collecting efficiency is greatly increased. In the ionization chamber 2, the ultraviolet light and the applied electric field can act on the VOC molecules at the same time, so that the ionization process and the ion deflection process of the VOC molecules are almost performed at the same time, which will avoid that positive ions are combined with electrons without striking on the acquisition plate.
Drawings
FIG. 1 is a schematic diagram of a spiral micro photoionization detecting device according to the present invention.
Fig. 2 is a front view of a vacuum ultraviolet lamp structure.
Fig. 3 is a front view of an ionization chamber structure.
Fig. 4 is a schematic view of the structure of the air flow channel.
Fig. 5 is a side view of fig. 4.
Other relevant drawings may be made by those of ordinary skill in the art from the above figures without undue burden.
Detailed Description
In order to make the person skilled in the art better understand the solution of the present invention, the following describes the solution of the present invention with reference to specific embodiments.
Example 1
The invention relates to an ionization chamber, which comprises a cavity type shell 3, such as a cuboid shell supported by polytetrafluoroethylene, a sheet-shaped grounding electrode 5 and a voltage electrode 6 which are correspondingly arranged at the top and the bottom in the shell, and a gas channel 7 fixedly arranged in the shell and correspondingly communicated with the outside, wherein the gas channel is made of a light-transmitting material such as MgF2, and a metal film is plated on the lower half part of the inner wall surface of the gas channel to serve as a collecting plate 8. Preferably, an electromagnetic shielding net 4 is arranged in the shell for shielding the interference of external electric fields. The collecting plate 8 is coated on the lower half part of the inner side of the pipeline of the gas channel 7 by a high-conductivity material in a coating mode, and the thickness of the collecting plate is 0.1mm. The manufacturing process is that the lower half part of the gas channel 7 is placed in gold plating solution, and a layer of uniform and extremely thin gold film is attached to the lower half side of the inner wall of the gas spiral channel 7 by a precipitation method. A circular ultraviolet lamp mounting hole 14 is provided in the housing at a position corresponding to the gas passage. A plurality of light holes are arranged on the grounding electrode corresponding to the mounting holes.
The gas channel comprises a planar spiral section and an L-shaped leading-out section for further enlarging the gas flow working area. The diameter of the air channel 7 is 4mm, the maximum radius of the spiral section of the air channel 7 is slightly smaller than that of the ultraviolet lamp mounting hole 14, and the air vent 11 and the air outlet 12 are arranged. The adoption of the planar spiral effectively improves the actual operation stroke and the detection effect.
Ultraviolet light and an electric field are simultaneously applied in a gas molecule flow path to be detected, and the area of a lighting area and the area of a collecting plate 8 are increased through a spiral gas channel 7, so that the collecting efficiency is greatly increased. In the ionization chamber 2, the ultraviolet light and the applied electric field can act on the VOC molecules at the same time, so that the ionization process and the ion deflection process of the VOC molecules are almost performed at the same time, which will avoid that positive ions are combined with electrons without striking on the acquisition plate.
Example two
The shell comprises a main body with an opening at one side and a side cover 15 fixedly connected with the main body, and two ends of the gas channel are correspondingly fixed on the side cover. The right side cover 15 of the ionization chamber housing is provided with the gas spiral passage 7 and is integrally formed on the right side of the main body by embedding or screwing. The side cover 15 of the ionization chamber housing is detachable, so that the inside of the ionization chamber 2 can be conveniently inspected, and damaged parts can be replaced.
The top and the bottom of the shell are respectively provided with a slot for positioning the grounding electrode and the voltage electrode, or the grounding electrode and the voltage electrode are correspondingly embedded in the shell. Specifically, the grounding electrode 5 is made of stainless steel, embedded inside the top of the ionization chamber housing 3 and has a thickness of 1mm, a plurality of light passing holes 13 are formed in the part facing the ultraviolet lamp mounting holes 14, the voltage electrode 6 is made of stainless steel,
Example III
A spiral path miniature photoionization detection device comprises an ionization chamber, an ultraviolet lamp fixedly connected with the ionization chamber, a dehumidification device and a filter device arranged between the air pump and an air inlet of a gas channel, and a micro-current amplification circuit electrically communicated with a collection plate.
Wherein, the ultraviolet lamp is in threaded connection with the shell, namely, the top of the ionization chamber shell 3 is provided with a circular hole 14, and the hole wall is provided with a thread groove 9. The vacuum ultraviolet lamp 1 is provided with threads 10 on the outer shell, and the vacuum ultraviolet lamp 1 is assembled on the ionization chamber shell 3 through the threads 10. The vacuum ultraviolet lamp 1 is connected with the shell 3 of the ionization chamber 2 through threads 10, which is convenient for collecting and checking the instrument,
The working first half of the invention is as follows: the gas to be tested firstly passes through the dehumidifying device to keep the gas dry, and then passes through the filtering device, so that particles possibly contained in the gas to be tested are filtered, the influence on experimental results is prevented, and meanwhile, a certain protection effect on instruments is also achieved. The treated gas to be tested then enters the ionization chamber 2 through the air vent 11, and the VOC molecules are ionized to generate positive ions and electrons due to ultraviolet light in the ionization chamber 2; at the same time, a high voltage electric field is also applied vertically downwards in the ionization chamber 2, so that positive ions are subjected to downward acting force, and fall on the acquisition plate 8 positioned in the spiral path pipeline, and micro-current is generated.
The invention is in the working half: the signal processing circuit of the micro-current amplifying circuit adopts a PCB double-layer layout, and the top-layer and bottom-layer electronic devices are uniformly arranged. The amplifier selects a high-performance logarithmic amplifier to amplify weak voltage signals. According to the advantages of the logarithmic amplifier, the amplification factor of the signal can be widened, and meanwhile, the error of the amplified signal can be reduced by the high-performance logarithmic amplifier. The signal amplifying circuit is integrated on a special PCB double-layer board, and weak current signals entering the circuit are subjected to I-U conversion and then filtered by a filtering network in the figure to remove clutter and enter the amplifying part. The whole circuit layout strictly requires symmetrical layout and standardizes wiring.
Spatially relative terms, such as "upper," "lower," "left," "right," and the like, may be used in the embodiments for ease of description to describe one element or feature's relationship to another element or feature's illustrated in the figures. It will be understood that the spatial terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "under" other elements or features would then be oriented "over" the other elements or features. Thus, the exemplary term "lower" may encompass both an upper and lower orientation. The device may be otherwise positioned (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
Moreover, relational terms such as "first" and "second", and the like, may be used solely to distinguish one element from another element having the same name, without necessarily requiring or implying any actual such relationship or order between such elements.
The foregoing has described exemplary embodiments of the invention, it being understood that any simple variations, modifications, or other equivalent arrangements which would not unduly obscure the invention may be made by those skilled in the art without departing from the spirit of the invention.
Claims (8)
1. The utility model provides an ionization chamber, its characterized in that includes cavity formula casing, corresponds the sheet form earthing pole and the voltage pole of setting in top and bottom in the casing to and the fixed gas passage that sets up in the casing and correspond outside intercommunication, gas passage make and plate the metal film in gas passage's internal face lower half and regard as the collection board, gas passage be including planar spiral section and L shape leading-out section, the top of casing be provided with ultraviolet lamp mounting hole, be provided with a plurality of light trap on the earthing pole that corresponds with the mounting hole.
2. The ionization chamber of claim 1 wherein said housing comprises a body having an opening at one side and a side cover fixedly attached to said body, said gas passage having opposite ends secured to said side cover.
3. The ionization chamber of claim 1 wherein said gas channel is made of MgF 2.
4. The ionization chamber of claim 1 wherein slots are provided in the top and bottom of the housing to position the ground and voltage poles, respectively, or the ground and voltage poles are embedded in the housing, respectively.
5. An ionization chamber according to claim 1, wherein an electromagnetic shielding net (4) is arranged in the housing for shielding external electric field disturbances.
6. A spiral path miniature photoionization detection device is characterized in that: comprising an ionization chamber according to any one of claims 1-5, an ultraviolet lamp fixedly connected to said ionization chamber, a dehumidifying device and a filtering device arranged between the air pump and the air inlet of the air channel, and a microcurrent amplifying circuit in electrical communication with said acquisition board.
7. The spiral miniature photoionization detection device of claim 6, wherein: the ultraviolet lamp is in threaded connection with the shell.
8. The spiral miniature photoionization detection device of claim 6, wherein: the signal processing circuit of the micro-current amplifying circuit adopts a PCB double-layer layout.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910232913.9A CN109884167B (en) | 2019-03-26 | 2019-03-26 | Ionization chamber and spiral path miniature photoionization detection device |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910232913.9A CN109884167B (en) | 2019-03-26 | 2019-03-26 | Ionization chamber and spiral path miniature photoionization detection device |
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| Publication Number | Publication Date |
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| CN109884167A CN109884167A (en) | 2019-06-14 |
| CN109884167B true CN109884167B (en) | 2024-05-24 |
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Citations (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4028617A (en) * | 1975-01-16 | 1977-06-07 | Hitachi, Ltd. | Ionization detector utilizing electric discharge |
| US4377749A (en) * | 1981-02-25 | 1983-03-22 | Young Robert A | Photoionizer |
| DE19641177A1 (en) * | 1996-09-24 | 1998-03-26 | Inst Bioprozess Analysenmesst | Measuring chamber for photo-ionisation meter for gas or atmosphere analysis |
| DE19838759A1 (en) * | 1998-08-26 | 2000-03-09 | Inst Umwelttechnologien Gmbh | Analyzing trace gas comprises measuring the ionization currents at points which are at different distances from a UV light source |
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| US8922219B2 (en) * | 2010-11-30 | 2014-12-30 | General Electric Company | Photo-ionization detectors and associated methods thereof |
| WO2016179291A1 (en) * | 2015-05-05 | 2016-11-10 | The Regents Of The University Of Michigan | Microfluidic photoionization detector |
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