KR101762394B1 - Photoionization gas sensor - Google Patents

Abstract

The present invention relates to a photoionization gas sensor, and more particularly, to a photoionization gas sensor, which comprises a housing having an internal space and having at least one through hole communicated with the internal space, a measurement electrode provided adjacent to the through hole and spaced apart from the anode, And at least two accommodating spaces which are disposed in the inner space of the housing and in which inert gas is accommodated and which are partitioned by a plurality of partition walls and which are accommodated in the accommodating space by electrical signals applied to the electrodes disposed in the respective inner spaces At least one ultraviolet ray generating module for irradiating an ultraviolet ray by reacting with an inert gas, and a photo ionizing gas sensor for irradiating ultraviolet rays to the measurement gas introduced into the housing through at least one through hole to ionize the measurement gas do.
According to the present invention, ultraviolet rays are irradiated to a wide region to accelerate the ionization of the measurement gas, and the structure of the measurement electrode provided in a wide section can widen the reaction region of the ionized measurement gas and has excellent linearity. The sensitivity can be improved and at least one ultraviolet ray generating element is provided to realize the ultraviolet ray focusing region, the precision of the optical density of the ultraviolet ray focusing region is high, and the ultraviolet ray generating element having the inert gas is used for precision welding It is possible to reduce the possibility of leakage of the inert gas by performing a finishing treatment with a carbon dioxide gas laser as possible, so that the output of the ultraviolet ray generating element is prevented from deteriorating and it can be used for a long time.

Description

[0001] PHOTOIONIZATION GAS SENSOR [0002]

The present invention relates to a photoionization gas sensor.

Volatile Organic Compounds (VOCs) are a generic name for organic compounds that are easily volatilized and released into the atmosphere due to their high vapor pressure under everyday conditions.

Volatile organic compounds (VOCs) are carcinogens that can be harmful to the nervous system due to inhalation by skin contact or respiratory system. VOCs are highly volatile and easily volatilize into the atmosphere and cause odor and ozone.

At this time, although volatile organic compounds occur in nature, most of them occur due to human industrial activities, and emissions can be made from paints, chemicals, and tobacco, so that concentration regulation for the discharge of volatile organic compounds is required.

In addition, there is a need for gas detection to detect the presence of volatile organic compounds (VOCs) in order to prevent explosion accidents and workers' smothering accidents in the field of industrial activities, and various studies have been conducted on the measurement and analysis of volatile organic compounds .

Typically, a photoionization detector is used to irradiate and ionize ultraviolet rays having ionization energy equal to or higher than the ionization energy of a gas corresponding to a volatile organic compound or other toxic gas introduced into the detector, and the ions of the corresponding gas separated into positive and negative ions There is a method of detecting the concentration by measuring the potential difference generated by moving to the measuring electrode.

As a part of the technique for ionizing the gas measured by the photoionization detector, Korean Patent Registration No. 10-0972474 (Filing Date: 2008. 06. 18, Publication Date: 2010. 07. 26, An inert gas such as xenon (Xe), krypton (Kr), or argon (Ar) is injected into the quartz tube or the glass tube at a pressure lower than the atmospheric pressure and then the quartz tube or the glass tube into which the inert gas is injected is sealed An inert gas filled in an ultraviolet lamp is stimulated by a plasma reaction generated through a magnetic field generated at an RF electromagnetic signal electrode located outside the ultraviolet lamp and irradiated with ultraviolet rays having a wavelength of 100 to 300 nm, And photoionization gas sensor for detecting the concentration of the measurement gas through detection of the ionization electric signal strength of the ionized measurement gas is proposed There is a bar.

However, the photoionization gas sensor of the prior art employs a cylindrical structure in which an inert gas below atmospheric pressure is contained in a quartz tube or a glass tube, and a method in which an ultraviolet transmitting member such as magnesium fluoride (MgF ₂ ) seals a quartz tube or a glass tube It is difficult to maintain the minimum atmospheric pressure for plasma discharge because there is a possibility of leakage of an inert gas injected into the ultraviolet lamp between the ultraviolet lamp and the ultraviolet ray transmitting member, A deterioration reaction may occur in which the output of the ultraviolet lamp is lowered through the blackening reaction of the outer diameter of the ultraviolet lamp.

In addition, in the conventional photo ionization gas sensor, a gas chamber, which is a section in which a gas entering the gas sensor is collected for detecting an organic compound, is located at the upper end of the gas sensor, and photo ionization The gas ions decomposed due to the reaction are applied with a voltage of several hundred V to the electrode inserted in the gas chamber to collect the ions on the electrode.

At this time, the structure of the electrode is closely related to the performance of the gas sensor such as the sensitivity, linearity, and response time of the sensor. Therefore, in order to improve the performance of the gas sensor, Or it is necessary to increase the reaction area of the gas ions collected in the structure of the electrode inserted in the gas chamber.

However, since the irradiation area of the ultraviolet ray is limited to the size of the ultraviolet ray transmitting member in the conventional structure of the prior art and general photoionization gas sensor, the length of the ultraviolet lamp, In order to increase the reaction area of the gas ions, the size of the electrode for capturing the ions is increased in the gas chamber, which may be a limitation in downsizing the photoionization gas sensor.

In addition to the prior art, in general, an ultraviolet lamp used in a photo ionization gas sensor emits ultraviolet rays by reacting with a magnetic field generated through an electrode and a gas inside the ultraviolet lamp to an ultraviolet lamp that emits ultraviolet rays, The decomposition of the organic compounds in the air is accelerated and the carbonization action is generated. As a result, the output of the ultraviolet lamp is lowered. Since the single ultraviolet lamp is used, the replacement period of the photoionization gas sensor is short.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a photo ionizing gas sensor capable of accurately detecting a measurement gas introduced into a photoionization detector, capable of downsizing, have.

To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided a photoionization gas sensor comprising: a housing having an inner space and having at least one through hole communicating with an inner space; A measuring electrode provided as an anode and a cathode which are disposed adjacent to and spaced from the through-hole in the inner space of the housing; And at least two accommodating spaces which are disposed in the inner space of the housing and in which the inert gas is accommodated and which are partitioned by a plurality of partitions and in which an inert gas And at least one ultraviolet ray generating module for irradiating ultraviolet rays to the inside of the housing through the at least one through hole to ionize the measuring gas by irradiating ultraviolet rays to the measuring gas.

The ultraviolet ray generating module may include at least two ultraviolet ray generating modules each having an ultraviolet ray focusing area concentrated at one point adjacent to the measuring electrode, As shown in FIG.

At this time, a plurality of through holes are formed in a measuring electrode provided adjacent to the ultraviolet ray generating module in the measuring electrode provided as an anode and a cathode, and ultraviolet rays emitted from the ultraviolet ray generating module pass through a space separated by the measuring electrode Can be delivered to the gas.

In addition, the measurement gas passing through the space separated by the measuring electrode by the ultraviolet rays generated from the ultraviolet ray generating module is separated into positive and negative ions, the positive ions are moved to a measuring electrode provided as a negative electrode, Can be moved.

As described above, the present invention has the following effects.

First, compared with the ultraviolet ray transmitting member limited to the size of a single ultraviolet lamp used in the prior art, ultraviolet rays are irradiated on a wide area not limited to the ultraviolet ray focusing region, thereby promoting ionization of the measuring gas. The response time of the ionized measurement gas can be widened, the linearity can be improved, and fast and accurate measurement can be performed, thereby improving the sensitivity of the photoionization gas sensor.

Secondly, when a plurality of ultraviolet ray generating elements are provided to realize an ultraviolet ray focusing region, the optical density of the ultraviolet ray focusing region is high and precision is improved, and a plurality of ultraviolet ray generating elements The optical density of the ultraviolet ray irradiation region can be maintained without a large change, so that the reliability of the measurement result can be improved, and the replacement cycle of the photoionization gas sensor can be prolonged.

Third, since the ultraviolet ray generating element having an inert gas is subjected to a finishing treatment with a carbon dioxide gas laser which can be used for precision welding, the possibility of leakage of the inert gas can be reduced, so that the amount of the inert gas is kept constant in the ultraviolet ray generating element, The output of the device can be prevented from deteriorating, and the device can be used for a long time.

FIG. 1 schematically shows the structure of a conventional photoionization gas sensor according to an embodiment of the present invention.
2 schematically shows the structure of an ultraviolet ray generating element according to an embodiment of the present invention.
FIG. 3 is a schematic view illustrating an ionization process of a measurement gas through a photoionization gas sensor according to an embodiment of the present invention.

The preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings, in which the technical parts already known will be omitted or compressed for simplicity of explanation.

FIG. 1 schematically shows the structure of a photoionization detector using a conventional photoionization gas sensor 100 according to an embodiment of the present invention.

1, a conventional photoionization gas sensor 100 includes a through hole 111 through which a measurement gas G is introduced and discharged, an anode 121 disposed adjacent to and spaced apart from the through hole 111, A single ultraviolet lamp L for irradiating ultraviolet rays in the direction of the measuring electrode 120, a ultraviolet transmitting member W for attaching in the direction in which ultraviolet rays are irradiated from the ultraviolet lamp L, ).

The measurement electrode 120 may be positioned in the gas chamber C where the measurement gas G for detection of the organic compound through the through hole 111 is captured by the photo ionization gas sensor 100.

Here, when the ultraviolet ray irradiated from the ultraviolet lamp L is larger than the ionization energy of the measurement gas G introduced through the through hole 111, the measurement gas G is separated into the positive ion P and the negative ion N And the negative ions P move to the measuring electrode 120 provided as the cathode 122 and the negative ions N move to the measuring electrode 120 provided as the anode 121. [

Then, the ions moved to the measuring electrode 120 are collected in the measuring electrode, the potential difference of the ions is measured, and the measured result is quantified and expressed in concentration by the photoionization detector.

At this time, a high energy current is applied to an ultraviolet lamp (L) that emits ultraviolet rays to emit ultraviolet rays, thereby promoting deterioration of ultraviolet lamps made of quartz tubes, and promoting decomposition of organic compounds in the atmosphere and carbonization The output of the ultraviolet lamp is lowered, which leads to a problem that the lifetime of the photoionization gas sensor is shortened.

Since the ultraviolet ray irradiation area is limited to the size of the ultraviolet transmitting member W located above the ultraviolet lamp L, in order to increase the output of the ultraviolet lamp L for accurate detection, the size of the ultraviolet lamp L must be large It is difficult to miniaturize the photoionization gas sensor 100 and the replacement period of the photoionization gas sensor is short because the single ultraviolet lamp L is used and the ultraviolet lamp There is also a problem that the gas filled inside can leak.

FIG. 2 is a schematic view illustrating a structure of an ultraviolet ray generating device according to an embodiment of the present invention, and FIG. 3 is a schematic view illustrating an ionization process of a measurement gas through a photoionization gas sensor according to an embodiment of the present invention will be.

2 and 3, in the present embodiment, the photo ionizing gas sensor 100 includes a housing 110 having at least one through-hole 111 communicating with an inner space, an inner space of the housing 110 A measurement electrode 120 provided in the interior space of the housing 110 and provided with an anode 121 and a cathode 122 which are disposed adjacent to and spaced from the through hole 111. The measurement electrode 120 irradiates ultraviolet rays toward the measurement electrode 120 And an ultraviolet ray generating module (130).

The housing 110 is communicated with the internal space and has a through hole 111 through which the measurement gas G can be introduced into the housing 110.

At this time, the through hole 111 through which the measurement gas G may be discharged may be further provided, and the through hole 111 through which the measurement gas is introduced may be provided above the housing.

The measuring electrode 120 is provided as an anode 121 and a cathode 122 and is spaced apart from the through hole 111 by a predetermined distance. The anode 121 and the cathode 122 of the measuring electrode 120, The measurement gas G flowing through the through-holes 111 can pass through the spaces provided separately from each other.

Here, the distance d between the anode 121 and the cathode 122 may have a distance between 0.5 mm and 1.5 mm.

At this time, the anode 121 or the cathode 122 located at the portion irradiated with ultraviolet rays is provided with a plurality of holes through which ultraviolet rays can pass to prevent the ultraviolet rays emitted from the ultraviolet ray generating element 131 from being disturbed Can be.

The measurement electrode 120 is disposed adjacent to and spaced apart from the through hole 111. The measurement gas G for detecting an organic compound is provided through the through hole 111, (C), which is an area where the gas is captured by the photoionization gas sensor (100).

At this time, the position of the gas chamber C may be changed according to the arrangement of the measuring electrode 120 and the ultraviolet ray generating module 130, which will be described later, in the photo ionizing gas sensor 100.

The ultraviolet ray generating module 130 has an inert gas accommodated therein and has at least two accommodating spaces partitioned by a plurality of partitions 131d.

At this time, the receiving space means a unit structure of the ultraviolet ray generating module 130, and an inert gas accommodated in the receiving space reacts with ultraviolet rays by an electrical signal applied to the electrodes disposed in the respective receiving spaces.

Referring to FIG. 2, the ultraviolet ray generating devices 131 defined as one unit structure of the ultraviolet ray generating module 130 include a front substrate 131a and a rear substrate 131b spaced apart from each other by a predetermined distance, A partition wall 131d provided on a side surface of the partition wall 131b forms an inner space and an inert gas is accommodated in the inner water space.

At this time, the barrier rib 131d defines one unit structure region, and the ultraviolet ray generating element 131 in the ultraviolet ray generating module 130, which will be described later, can be defined as a unit structure.

In this embodiment, the pair of electrodes 131c, which generate a plasma discharge by flowing an electric current to the inert gas in the internal space, are disposed on the front substrate 131a and the rear substrate 131b, May be disposed on at least one of the substrate 131a and the rear substrate 131b.

At this time, the electrode 131c is surrounded by the dielectric film 131e, and the reflection film 131f may be positioned on the rear substrate 131b. When the inert gas contained in the ultraviolet ray generator 131 generates ultraviolet rays by plasma discharge, The generated ultraviolet rays can be irradiated toward the front substrate 131a.

Further, in order to prevent leakage of inert gas contained in the ultraviolet ray generating element 131, a carbon dioxide gas laser which can be used for precise welding when sealing the front substrate 131a and the rear substrate 131b after sealing them is used It can be closed.

Generally, an inert gas such as argon (Ar), krypton (Kr), or xenon (Xe) is injected into the ultraviolet ray generating element 131. When an electric current is supplied to the ultraviolet ray generating element 131, Emits the energy of the wavelength band.

At this time, when the xenon is contained in the ultraviolet ray generating element 131 as an inert gas, an electric current is supplied to the ultraviolet ray generating element 131 to generate ultraviolet rays when a plasma discharge phenomenon occurs and an ultraviolet ray having an energy of 9 eV to 10 eV Is irradiated in the direction of the measuring electrode 120.

Here, benzene, which is a volatile organic compound, has an ionization energy lower than that of xenon by 9.2 eV, so that xenon can be ionized by ultraviolet rays emitted from the accommodated ultraviolet ray generating element 131.

The ultraviolet ray generating element 131 may be provided in the form of one ultraviolet ray generating module 130 coupled with at least two or more of the ultraviolet ray generating elements 131. In order to realize the ultraviolet ray irradiation area in the photoionization gas sensor 100, Module 130 may be used.

At this time, the ultraviolet ray generating element 131 defined as one unit structure of the ultraviolet ray generating module 130 can uniformly output ultraviolet rays per one unit structure, and deterioration due to the plasma discharge can be reduced.

Here, the at least one ultraviolet ray generating module 130 may include at least one ultraviolet ray condensing area A such that the ultraviolet rays irradiated from the respective ultraviolet ray generating modules 130 have an ultraviolet ray focusing area A concentrated at one point adjacent to the measuring electrode 120, Generating modules 130 are arranged with different predetermined angles.

In this case, at least one ultraviolet ray generating module 130 may be formed in a U-shape, and the ultraviolet ray focusing area A is not limited to this embodiment, so that the size of the ultraviolet ray focusing area A, And the like.

Since the optical density of the ultraviolet focusing region A is high in order to realize the ultraviolet focusing region A by arranging the plurality of ultraviolet generating modules 130, the ionization process can be performed smoothly, The accuracy in detecting the concentration of the measurement gas G used can be improved.

The plurality of ultraviolet ray generating modules 130 implementing the ultraviolet ray focusing area A having a higher optical density than the prior art in which the size of the ultraviolet lamp L has to be increased in order to increase the output of ultraviolet rays can be miniaturized, The photoionization detecting apparatus of the present invention can be used.

The optical density of the ultraviolet ray focusing area A may be slightly reduced by a plurality of ultraviolet ray generating elements 131 that operate properly when a failure occurs in the ultraviolet ray generating elements 131 constituting the ultraviolet ray generating module 130 The ultraviolet focusing region A can be maintained without a large change to increase the reliability of the measurement result and the replacement cycle of the photo ionizing gas sensor 100 can be prolonged.

In the prior art and general photoionization gas sensor 100, only the ultraviolet lamp (L) can be replaced, but the ultraviolet lamp (L) has a short replacement period since it has a short life.

In this case, since the heat sink can be attached according to the heat radiation design, deterioration of the ultraviolet ray generating module 130 for irradiating the ultraviolet rays can be suppressed when the heat sink is attached, so that the ultraviolet ray generating module 130 can be replaced, The present invention can be applied to a photo ionization gas sensor 100 having a long lifetime instead of a replacement method of the ultraviolet ray generating module 130.

In the prior art, since a single ultraviolet lamp (L) is used, the ionization reaction time is limited by the ultraviolet ray transmitting member (W) limited to the size of the ultraviolet lamp (L) Could be.

However, the ultraviolet rays generated by the ultraviolet ray generating module 130 are formed by the arrangement of the plurality of ultraviolet ray generating modules 130, so that the ultraviolet ray focusing region A having a high optical density is formed adjacent to the measuring electrode 120, Since the region where the ultraviolet rays are irradiated is present in addition to the region A to accelerate the ionization of the measurement gas G, the measuring electrode 120 can be irradiated with the ultraviolet rays to be irradiated by the ultraviolet ray generating module 130, A plurality of holes through which ultraviolet rays can pass may be formed in the anode 121 or the cathode 122 located at the irradiated portion and the structure of the measuring electrode 120 provided in a wide section may be a measurement gas G, The sensitivity of the photoionization gas sensor 110 can be improved because the response time of the photoionization gas sensor 110 can be widened to have excellent linearity and quick and accurate measurement can be performed.

At this time, due to the structure of the measuring electrode 120 provided in a wide section, the photo ionizing gas sensor G in this embodiment has excellent linearity, so that one concentration corresponding to the measured result value is detected.

Although not shown in FIG. 3, a cover (not shown) may be further provided adjacent to the measuring electrode 120 so that ultraviolet rays can be transmitted through the gap to prevent the measurement gas G from flowing into a section where the ultraviolet ray generating module 130 is located. , The sensitivity of the photo ionizing gas sensor 100 can be improved since the size is not limited as compared with the prior art.

3, the ultraviolet rays emitted from the plurality of ultraviolet ray generating modules 130 have different ultraviolet ray focusing areas A converged at one point adjacent to the measuring electrode 120, And the ionized measurement gas G is separated into the positive ions P and the negative ions N and moves to the measurement electrode 120. The measurement electrode

The ions of the measurement gas G move to the measurement electrode 120 provided with the positive electrode 121 and the measurement electrode 120 provided with the positive ion P and the negative electrode N, And the measuring electrode 120 measures the potential difference of the ions and is transmitted to a circuit connected to the inside or the outside of the photo ionizing gas sensor 110 to detect the concentration of the measuring gas G. [

In this case, the circuit connected to the inside or the outside of the photoionization gas sensor 110 may include an amplifier for amplifying the measured signal.

The circuit for measuring the concentration of the measurement gas G located inside the photoionization gas detection device may be located inside the photoionization gas sensor 100 or may be located outside the photoionization gas sensor 100 It may be electrically connected to the photoionization gas sensor 100.

As a result, the present invention is capable of widening the reaction zone of the ionized measurement gas with the structure of the measuring electrode provided in a wide section, thereby accelerating the ionization of the measuring gas by irradiating ultraviolet rays to a wide region, The sensitivity of the photoionization gas sensor can be improved and the optical density of the ultraviolet focusing region can be improved by providing at least one ultraviolet generating element to realize the ultraviolet focusing region, The optical density of the ultraviolet ray irradiation region can be maintained without a large change by the large number of ultraviolet ray generating elements that operate properly and reliability of the measurement result can be enhanced and the replacement period of the photoionization gas sensor becomes long, A carbon dioxide gas laser, which can be used for precise welding, The possibility of leakage of the inert gas can be reduced, and the output of the ultraviolet ray generating element is prevented from being lowered, thereby providing a photo ionizing gas sensor which can be used for a long time.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. And the scope of the present invention should be understood as the following claims and their equivalents.

100: Photoionization gas sensor
110: Housing
111: Through hole
120: measuring electrode
121: anode
122: cathode
130: ultraviolet ray generating module
131: ultraviolet ray generating element
131a: front substrate
131b: rear substrate
131c: electrode
131d:
131e: Dielectric film
131f:
P: cation
N: negative ion
G: Measuring gas
L: Ultraviolet lamp
W: Ultraviolet ray transmitting member
A: Ultraviolet focusing region
C: gas chamber

Claims (4)

A housing having an inner space and formed with at least one through hole communicating with the inner space;
A measuring electrode provided as an anode and a cathode which are disposed adjacent to and spaced from the through-hole in the inner space of the housing; And
An inert gas accommodated in the accommodating space is accommodated in the accommodating space by means of an electric signal applied to an electrode disposed in each accommodating space and having at least two accommodating spaces which are disposed in an inner space of the housing and in which inert gas is accommodated, And at least one ultraviolet ray generating module which reacts and irradiates ultraviolet rays,
The measurement gas is ionized by irradiating ultraviolet rays to the measurement gas introduced into the housing through the at least one through hole,
A plurality of through holes are formed in one of the electrodes disposed adjacent to the ultraviolet ray generating module in the measuring electrode provided for the positive electrode and the negative electrode so that the ultraviolet rays irradiated from the ultraviolet ray generating module are passed through the spaced- Characterized in that
Photoionization gas sensor.
The method according to claim 1,
Wherein each of the ultraviolet ray generating modules has at least two ultraviolet ray generating modules arranged in the inner space of the housing so that the ultraviolet rays emitted from the respective ultraviolet ray generating modules have ultraviolet ray focusing areas concentrated at one point adjacent to the measuring electrode Are arranged at different predetermined angles
Photoionization gas sensor.
delete 3. The method of claim 2,
The measurement gas passing through the space separated by the measuring electrode by the ultraviolet rays generated from the ultraviolet ray generating module is separated into positive and negative ions and the positive ions are moved to the measuring electrode provided as the negative electrode and the negative ions are moved to the measuring electrode provided as the positive electrode Characterized by
Photoionization gas sensor.

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