JP2020082030A - Dehumidifier and detection device - Google Patents

Abstract

To provide a dehumidifier that can obtain excellent dehumidification performance, and to provide a detection device.SOLUTION: A dehumidifier 100 includes: a first dehumidification unit 1 for dehumidifying a gas; a second dehumidification unit 2 for dehumidifying a gas that has been dehumidified by the first dehumidification unit 1; and a discharge part 30 for discharging a gas that has been dehumidified by the second dehumidification unit 2. The second dehumidification unit 2 includes an ion generator 21 for generating an ion from the gas that has been dehumidified by the first dehumidification unit 1.SELECTED DRAWING: Figure 1

Description

The present invention relates to a dehumidifier and a detection device.

Various studies have been conducted on the detection and analysis of chemical substances by a field asymmetric ion mobility spectroscopy (FAIMS) system. The FAIMS system has an ion filter with a pair of electrodes to which an asymmetric AC signal is applied, and when an ionized chemical substance is passed through the ion filter, it is sorted by the difference in its mobility. The chemical substance can be specified by colliding the chemical substance that has passed through the ion filter with the ion detection electrode and detecting the current generated in the ion detection electrode.

According to the FAIMS system, for example, it is possible to detect the kind and amount of a trace amount of molecules contained in a gas at a ppb to ppt level. On the other hand, if the gas contains% order of water molecules, such a minute amount of molecules will be buried. Moreover, when the humidity of the gas changes, the measured value of the molecule to be detected may change.

On the other hand, a gas analyzer provided with a dehumidifier has been proposed for the purpose of improving analysis accuracy.

However, the dehumidifier provided in the conventional gas analyzer cannot obtain sufficient dehumidification performance, and cannot dehumidify to the extent desired for detection of minute molecules at ppb to ppt levels.

An object of the disclosed technology is to provide a dehumidifier and a detection device that can obtain excellent dehumidification performance.

According to one aspect of the disclosed technique, a dehumidifier includes a first dehumidifying unit that dehumidifies a gas, a second dehumidifying unit that dehumidifies the gas dehumidified by the first dehumidifying unit, and the first dehumidifying unit. And a discharge unit that discharges the gas dehumidified by the dehumidifying unit 2. The second dehumidifying unit has an ion generator that generates ions from the gas dehumidified by the first dehumidifying unit.

According to the disclosed technology, excellent dehumidification performance can be obtained.

It is a schematic diagram which shows the structure of the dehumidifier which concerns on 1st Embodiment. It is sectional drawing which shows the structure of the dehumidification element provided in 1st Embodiment. It is a figure which shows the locus|trajectory of the movement of the ion in an example of an ion filter. It is a figure which shows the electric field strength dependence of the mobility of an ion. It is a figure which shows an example of the electric field waveform generated by an ion filter. It is a schematic diagram which shows the structure of the dehumidifier which concerns on 2nd Embodiment. It is a schematic diagram which shows the structure of the dehumidifier which concerns on 3rd Embodiment. It is a schematic diagram which shows the structure of the dehumidifier which concerns on 4th Embodiment. It is sectional drawing which shows the structure of the laminated dehumidification element provided in 4th Embodiment. It is a schematic diagram which shows the structure of the dehumidifier which concerns on 5th Embodiment. It is a schematic diagram which shows the structure of the dehumidifier which concerns on 6th Embodiment. It is a schematic diagram which shows the structure of the dehumidifier which concerns on 7th Embodiment. It is a schematic diagram which shows the structure of the ion detection apparatus which concerns on 8th Embodiment.

Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. In the present specification and the drawings, components having substantially the same functional configuration are designated by the same reference numerals, and duplicate description may be omitted.

(First embodiment)
First, the first embodiment will be described. The first embodiment relates to a dehumidifier suitable for dehumidifying a sample gas supplied to a FAIMS system. FIG. 1 is a schematic diagram showing the configuration of the dehumidifier according to the first embodiment.

The dehumidifier 100 according to the first embodiment includes a first dehumidifying unit 1 that dehumidifies a gas, a second dehumidifying unit 2 that dehumidifies a gas dehumidified by the first dehumidifying unit 1, and a second dehumidifying unit 2. The discharging unit 30 that discharges the gas dehumidified by the dehumidifying unit 2. The 1st dehumidification part 1 has the dehumidification element 11 provided with the polymer electrolyte membrane. The 2nd dehumidification part 2 has the ion generator 21, the ion filter 22, the discharge part 23, and the collecting ion electrode 24.

Here, the dehumidifying element 11 will be described. FIG. 2 is a sectional view showing the structure of the dehumidifying element 11.

As shown in FIG. 2, the dehumidifying element 11 has a polymer electrolyte membrane 111, a porous electrode 112 provided on one surface thereof, and a porous electrode 113 provided on the other surface thereof. The porous electrode 112 is arranged inside the housing 60 that constitutes a gas flow path, and the porous electrode 113 is arranged outside the housing 60. Then, a higher electric potential is applied to the porous electrode 112 than the porous electrode 113. For example, the porous electrode 113 is grounded, and a positive voltage is applied to the porous electrode 112 by the DC power supply 12.

In the dehumidifying element 11 thus configured, water molecules contained in the gas in the flow path are absorbed by the porous electrode 112, decomposed on the surface of the polymer electrolyte membrane 111 on the porous electrode 112 side, and generated by decomposition. The generated hydrogen ions permeate the polymer electrolyte membrane 111. The hydrogen ions that have permeated the polymer electrolyte membrane 111 combine with oxygen on the surface of the polymer electrolyte membrane 111 on the side of the porous electrode 113, and become water molecules and are discharged to the outside of the housing 60.

However, although the dehumidifying element 11 is excellent in dehumidifying performance from a gas having high humidity, when the humidity is low, for example, when it is lowered to about 0.1% Rh, the dehumidifying performance is lowered, and the humidity is reduced to a suitable level for the FAIMS system. Cannot be lowered.

Therefore, in the present embodiment, the second dehumidifying unit 2 dehumidifies the gas that has passed through the first dehumidifying unit 1 to further reduce the humidity of the gas. As described above, the second dehumidifying unit 2 has the ion generator 21, the ion filter 22, the discharging unit 23, and the collecting ion electrode 24.

The ion generator 21 has, for example, a planar electrode 211 and a pointed electrode 212. A lower potential than the electrode 211 is applied to the electrode 212. For example, the electrode 211 is grounded, and a negative voltage is applied to the electrode 212 by the DC power supply 25. A high electric field is generated near the tip of the electrode 212, and the gas around the tip of the electrode 212 is ionized. For example, the ion generator 21 can ionize water molecules in the gas.

Here, the ion filter 22 will be described. FIG. 3 is a diagram showing a locus of movement of ions in the example of the ion filter 22. FIG. 4 is a diagram showing the electric field strength dependence of the mobility of ions. FIG. 5 is a diagram showing an example of an electric field waveform generated by the ion filter.

As shown in FIG. 3, the ion filter 22 has a first electrode 221 and a second electrode 222 facing each other, and controls the mobility of passing ions. Note that, here, an XYZ three-dimensional orthogonal coordinate system is used, the traveling direction of the molecule to be analyzed is the +Z direction, and the direction in which the first electrode 221 can be seen from the second electrode 222 is the +Y direction. An asymmetric electric field is applied by the pulse power supply 29 between the first electrode 221 and the second electrode 222.

Under the environment of the electric field E, the ions move at the moving speed V represented by the following equation (1). Here, K is the mobility of the ion.
V=K×E (1)

By the way, the mobility of ions depends on the electric field strength. And this electric field strength dependence differs according to the kind of ion. As an example, FIG. 4 shows the electric field strength dependence of the mobility of three different types of ions (ion 91, ion 92, ion 93). Note that, in FIG. 4, for easy understanding, the mobilities of the respective ions are normalized so that the electric field strength is zero.

The mobilities of the three ions (ion 91, ion 92, and ion 93) are almost unchanged at a low electric field strength of 9 kV/cm or less. As the electric field strength increases from about 10 kV/cm, the characteristics peculiar to the ion type appear in the mobility. The mobility of the ions 91 greatly increases as the electric field strength increases, and becomes maximum at a positive high electric field (Emax). The mobility of the ions 92 hardly changes regardless of the electric field strength. The mobility of the ions 93 gradually decreases. In this way, the characteristics of the three parties are shown. The ion filter 22 selects ions by utilizing the difference between the mobility at low electric field strength and the mobility at high electric field strength.

FIG. 3 shows a locus of movement of three ions (ions 91, 92, and 93) between the first electrode 221 and the second electrode 222 of the ion filter 22. Note that here, for the sake of simplicity, the first electrode 221 and the second electrode 222 are parallel plates made of a conductor for convenience.

By making the waveform of the electric field generated between the first electrode 221 and the second electrode 222 an asymmetric electric field waveform, only arbitrary ions (in FIG. 3, the ions 92) can pass through the ion filter 22. it can. Although the first electrode 221 is grounded in FIG. 3, an asymmetric voltage may be applied to the first electrode 221.

FIG. 5 shows an example of an electric field waveform generated between the first electrode 221 and the second electrode 222. In this electric field waveform, a positive high electric field (Emax) and a negative low electric field (Emin) are alternately repeated. The high electric field period (t1) is shorter than the low electric field period (t2), and the ratio of t1 to t2 is 1:3 to 1:5. In this way, the electric field waveform is asymmetric in the vertical direction. This asymmetric electric field waveform is set so that the time average electric field is zero and the following expression (2) is established.
|Emax|×t1=|Emin|×t2 (2)

That is, the area of the area 81 and the area of the area 82 in FIG. 5 are set to be the same.

In the following, the value of |Emax|×t1 and the value of |Emin|×t2 are set to β as shown in the following expression (3).
|Emax|×t1=|Emin|×t2=β (3)

By the way, the velocity (Vup) of ions moving in the Y-axis direction during the high electric field period (t1) is expressed by the following equation (4). Here, K(Emax) is the mobility of ions at a high electric field (Emax).
Vup=K(Emax)×|Emax| (4)

For example, when |Emax| is about 10 kV/cm or more, three ions (ion 91, ion 92, ion 93) have different mobilities for each ion, so that the three ions have different transfer velocities (Vup). Different in three ways. That is, as shown in FIG. 3, the inclinations of the trajectories of the three ions are different from each other in the high electric field period (t1).

The displacement (yup), which is the distance that the ions move in the Y-axis direction during the high electric field period (t1), is expressed by the following equation (5).
yup=Vup×t1 (5)

On the other hand, the velocity (Vdown) of ions moving in the Y-axis direction during the low electric field period (t2) is represented by the following equation (6). Here, K(Emin) is the mobility of ions at a low electric field (Emin).
Vdown=−K(Emin)×|Emin| (6)

For example, when |Emin| is about 5 kV/cm or less, the mobility of three ions (ion 91, ion 92, ion 93) is almost the same, and therefore the moving speeds (Vdown) of the three ions are almost the same. Is. That is, as shown in FIG. 3, in the low electric field period (t2), the inclinations of the trajectories of the three ions are almost the same.

The displacement (ydown), which is the distance that the ions move in the Y-axis direction during the low electric field period (t2), is expressed by the following equation (7).
ydown=Vdown×t2 (7)

Within one cycle (T) of the asymmetric electric field waveform, the ions move in the +Z direction, move in the +Y direction during the period (t1), and move in the −Y direction during the period (t2).

Therefore, as shown in FIG. 3, one that goes to the first electrode 221 while repeating the zigzag motion (ion 91), one that goes toward the second electrode 222 while repeating the zigzag motion (ion 93), and the +Y direction. Is balanced with the displacement in the −Y direction, and is classified as those that pass through the ion filter 22 (ions 92).

By the way, the average displacement (ΔyRF) of the ion in the Y-axis direction in one cycle (T) in the asymmetric electric field waveform is expressed by the following equation (8).
ΔyRF=yup+ydown
=K(Emax)×|Emax|×t1−K(Emin)×|Emin|×t2
(8)

Then, the expression (8) can be expressed as the following expression (9) using the expression (3).
ΔyRF=β{K(Emax)−K(min)} (9)

Here, when K(Emax)−K(min) is set to ΔK, the above equation (9) is expressed as the following equation (10).
ΔyRF=βΔK (10)

β is a constant determined by the asymmetric electric field applied between the first electrode 221 and the second electrode 222. Therefore, the displacement of the ion in the Y-axis direction per period (T) of the asymmetric electric field waveform depends on ΔK which is the difference between the mobility in the low electric field (Emin) and the mobility in the high electric field (Emax).

Assuming that only the carrier gas transports the ions in the Z-axis direction, when the ions stay between the first electrode 221 and the second electrode 222, the displacement of the ions in the Y-axis direction (Y ) Is represented by the following equation (11). Here, tres is an average time during which the ions stay between the first electrode 221 and the second electrode 222 (average ion stay time).

The average ion residence time tres is expressed by the following equation (12). Here, A is the cross-sectional area of the ion path in the ion filter 22, L is the electrode length (electrode depth) in the Z-axis direction, and Q is the volumetric flow rate of the carrier gas. V is the volume (=A×L) of the ion filter 22.

The above equation (11) can be expressed as the following equation (13) using the above equation (12) and the above equation (3). Here, D is the duty of the asymmetric electric field waveform, and D=t1/T.

The high electric field (Emax) in the asymmetric electric field waveform, the volume (V) of the ion path in the ion filter 22, the duty (D) of the asymmetric electric field waveform, and the volume flow rate (Q) of the carrier gas are the same for all ion species. If the value is used, the displacement (Y) can be proportional to the difference ΔK between the mobility in the low electric field (Emin) and the mobility in the high electric field (Emax) peculiar to the ion species from the equation (13). Recognize.

In FIG. 3, the displacement (Y) of the ion 92 is the smallest, and only the ion 92 passes through the ion filter 22. Therefore, by changing the duty (D) so that the ions generated from the water molecules become the ions 92, the ions generated from the water molecules can be passed through the ion filter 22.

Further, the ions 91 and 93 that have contacted the first electrode 221 or the second electrode 222 before passing through the ion filter 22 are neutralized to become molecules. The molecules are released from the emission unit 30 together with the non-ionized molecules, and are supplied as a sample gas to a gas analyzer such as a FAIMS system.

In this way, the ion filter 22 can separate ions generated from water molecules from other ions.

The discharging unit 23 has a collecting ion electrode 24 and a pump 26. A positive voltage is applied to the collecting ion electrode 24 from the DC power supply 27. That is, a voltage having a polarity opposite to that of ions (anions) generated from water molecules is applied. Further, a negative voltage is applied to the housing 60 between the ion filter 22 and the collecting ion electrode 24 by the DC power supply 28. Since the lines of electric force gather on the collecting ion electrode 24, the ions that have passed through the ion filter 22, for example, the ions generated from water molecules are attracted to the collecting ion electrode 24. Then, these ions are discharged out of the system by the pump 26.

According to the second dehumidifying unit 2 configured in this way, the humidity of the gas dehumidified by the first dehumidifying unit 1 to about 0.1% Rh can be further reduced. For example, the humidity can be reduced to 0.01% Rh or less. Then, the gas dehumidified in this way is supplied as a sample gas to a gas analyzer such as a FAIMS system through the emission unit 30.

As described above, according to the dehumidifier 100 according to the first embodiment, the humidity of the gas supplied as the sample gas to the gas analyzer such as the FAIMS system can be significantly reduced. Moreover, since only water molecules can be removed, molecules to be analyzed can be supplied to the gas analyzer. Therefore, the gas analyzer can perform highly accurate analysis without being affected by humidity.

The material of the casing 60 is not particularly limited, but an insulator that absorbs less water molecules, is chemically stable, and reduces ion loss is desirable. For example, polytetrafluoroethylene (PTFE) can be used. Alternatively, a metal such as stainless steel may be used. However, when a conductive material is used, it is desirable to reduce the loss of ions as much as possible by applying a voltage having the same polarity as the ions generated from water molecules.

(Second embodiment)
Next, a second embodiment will be described. The second embodiment is different from the first embodiment in the configuration of the discharge unit 23. FIG. 6 is a schematic diagram showing the configuration of the dehumidifier according to the second embodiment.

In the dehumidifier 200 according to the second embodiment, a coolable ion collecting electrode 224 is provided instead of the ion collecting electrode 24 and the pump 26, and a drain pipe 225 is arranged below the ion collecting electrode 224. A cooling unit 226 that cools the collecting ion electrode 224 is also provided. The drain pipe 225 is an example of a discarding unit.

Other configurations are similar to those of the first embodiment.

In the dehumidifier 200, by cooling the collecting ion electrode 224 with a cooling device, it is possible to cause the ions coming toward the collecting ion electrode 224 to be moleculed to cause dew condensation. Then, the liquefied water molecules are discharged out of the system through the drain pipe 225.

Also according to the second embodiment, the humidity of the gas supplied as the sample gas to the gas analyzer such as the FAIMS system can be significantly reduced. Moreover, since only water molecules can be removed, molecules to be analyzed can be supplied to the gas analyzer. Therefore, the gas analyzer can perform highly accurate analysis without being affected by humidity.

(Third Embodiment)
Next, a third embodiment will be described. The third embodiment is different from the first embodiment in the configuration of the discharge unit 23. FIG. 7: is a schematic diagram which shows the structure of the dehumidifier which concerns on 3rd Embodiment.

In the dehumidifier 400 according to the third embodiment, the metal mesh 31 is provided at the entrance of the discharge part 30. A voltage having the same polarity as the case 60 is applied to the metal mesh 31. That is, a negative potential is applied to the metal mesh 31 from the DC power supply 28.

Other configurations are similar to those of the first embodiment.

With the dehumidifier 400, the same effect as that of the first embodiment can be obtained. Further, according to the dehumidifier 400, it is possible to more reliably suppress the outflow of the ions generated from the water molecules and passing through the ion filter 22 to the emission unit 30.

(Fourth Embodiment)
Next, a fourth embodiment will be described. The fourth embodiment differs from the first embodiment in the configuration of the first dehumidifying section 1. FIG. 8: is a schematic diagram which shows the structure of the dehumidifier which concerns on 4th Embodiment.

In the dehumidifier 500 according to the fourth embodiment, a laminated dehumidifying element 511 is provided instead of the dehumidifying element 11. FIG. 9 is a sectional view showing the structure of the laminated dehumidifying element 511.

As shown in FIG. 9, the laminated dehumidifying element 511 includes a polymer electrolyte membrane 521, a porous electrode 522 provided on one surface thereof, and a porous electrode 523 provided on the other surface thereof. The laminated dehumidifying element 511 further has a polymer electrolyte membrane 531, a porous electrode 532 provided on one surface thereof, and a porous electrode 533 provided on the other surface thereof. The laminated dehumidifying element 511 further includes an intermediate layer 512 provided between the porous electrode 532 and the porous electrode 523. The intermediate layer 512 is a layer containing oxygen, for example, an air layer. The porous electrode 522 is arranged inside the housing 60 that constitutes the gas flow path, and the porous electrode 533 is arranged outside the housing 60. Then, a higher potential than that of the porous electrodes 523 and 533 is applied to the porous electrodes 522 and 532. For example, the porous electrodes 523 and 533 are grounded, and a positive voltage is applied to the porous electrodes 522 and 532 by the DC power supply 12. As described above, the first dehumidifying unit 1 has the laminated dehumidifying element 511 in which a plurality of dehumidifying elements are stacked.

In the dehumidifying element 11, when the humidity outside the housing 60 is significantly higher than the humidity inside the housing 60, the dehumidifying performance may deteriorate. For example, if the humidity outside the housing 60 is about 80% Rh, hydrogen ions may not easily move between the porous electrode 112 and the porous electrode 113 with the polymer electrolyte membrane 111 sandwiched therebetween. .. On the other hand, in the laminated dehumidifying element 511, since the intermediate layer 512 contains oxygen and dehumidification can be performed in two stages, it is possible to reduce the difference in humidity between each stage. For example, when the humidity of the intermediate layer 512 is, for example, about 10% Rh to 15% Rh, the movement of hydrogen ions between the porous electrode 522 and the porous electrode 523 is also caused by the porous electrode 532 and the porous electrode 533. The movement of hydrogen ions during the period can also be maintained in a good state.

Other configurations are similar to those of the first embodiment. The number of dehumidifying elements included in the laminated dehumidifying element 511 is not limited and may be 3 or more.

Even with the dehumidifier 500, the same effect as that of the first embodiment can be obtained. Furthermore, according to the dehumidifier 500, even when the humidity outside the housing 60 is significantly higher than the humidity inside the housing 60, it becomes easy to maintain excellent dehumidification performance.

(Fifth Embodiment)
Next, a fifth embodiment will be described. The fifth embodiment differs from the first embodiment in the configuration of the first dehumidifying section 1. FIG. 10: is a schematic diagram which shows the structure of the dehumidifier which concerns on 5th Embodiment.

In the dehumidifier 600 according to the sixth embodiment, a variable DC power supply 612 is provided instead of the DC power supply 12. Further, the first dehumidifying unit 1 has a humidity control circuit 611 and a humidity detecting unit 613. The humidity detector 613 is provided between the dehumidifying element 11 and the ion generator 21, and detects the humidity of the gas that has passed through the dehumidifying element 11. The humidity control circuit 611 feedback-controls the voltage of the variable DC power supply 612 based on the humidity detected by the humidity detector 613. For example, the humidity control circuit 611 controls the dehumidifying element 11 through the voltage of the variable DC power supply 612 so that the humidity of the gas supplied to the ion generator 21 is substantially constant.

With the dehumidifier 600, the same effect as that of the first embodiment can be obtained. Further, according to the dehumidifier 600, even if the humidity of the gas supplied to the dehumidifier 600 greatly changes, the humidity of the gas supplied to the gas analyzer as the sample gas can be stabilized. Therefore, in the gas analyzer, highly accurate analysis can be performed without being affected by the fluctuation of humidity.

For the humidity detection unit 613, for example, a dew point meter, a resistance type humidity sensor, a capacitance type humidity sensor, or the like can be used. Of these, a capacitance type humidity sensor that is particularly excellent in detecting low humidity is desirable.

(Sixth Embodiment)
Next, a sixth embodiment will be described. The sixth embodiment differs from the fifth embodiment in the configuration of the second dehumidifying section 2. FIG. 11: is a schematic diagram which shows the structure of the dehumidifier which concerns on 6th Embodiment.

In the dehumidifier 700 according to the sixth embodiment, a variable DC power supply 725 is provided instead of the DC power supply 25. Further, the second dehumidifying unit 2 has a humidity control circuit 721 and a humidity detecting unit 723. The humidity detector 723 is provided in the discharger 30 and detects the humidity of the gas flowing through the discharger 30. The humidity control circuit 721 feedback-controls the voltage of the variable DC power supply 725 based on the humidity detected by the humidity detector 723. For example, the humidity control circuit 721 controls the ion filter 22 through the voltage of the variable DC power supply 725 so that the humidity of the gas supplied as the sample gas to the gas analyzer is substantially constant.

With the dehumidifier 700, the same effect as that of the fifth embodiment can be obtained. Further, if the ion generator 21 deteriorates, the ionization rate of water molecules may decrease, but even in such a case, the humidity of the gas flowing through the discharge part 30 can be stabilized. Therefore, in the gas analyzer, highly accurate analysis can be performed without being affected by the fluctuation of humidity.

Although the configuration of the humidity detecting unit 723 is not limited, for example, by providing a polymer electrolyte membrane in the humidity detecting unit 723 and utilizing the characteristic that the amount of current consumed changes depending on the humidity when the polymer electrolyte membrane electrolyzes water. It is desirable to have a configuration in which humidity is detected. For the humidity detector 723, for example, a capacitance type humidity sensor or the like may be used.

(Seventh embodiment)
Next, a seventh embodiment will be described. The seventh embodiment is different from the fifth embodiment in the configuration of the second dehumidifying section 2. FIG. 12 is a schematic diagram showing the configuration of the dehumidifier according to the seventh embodiment.

In the dehumidifier 800 according to the seventh embodiment, a variable DC power supply 725 is provided instead of the DC power supply 25. Further, the second dehumidifying unit 2 has a humidity control circuit 821 and an ammeter 822. The ammeter 822 measures the current flowing through the collector electrode 24. The humidity control circuit 821 feedback-controls the voltage of the variable DC power supply 725 based on the current measured by the ammeter 822. For example, the humidity control circuit 821 controls the voltage of the variable DC power supply 725 so that the difference between the humidity of the gas supplied to the ion generator 21 and the humidity calculated from the current flowing through the collecting ion electrode 24 becomes substantially constant. The ion filter 22 is controlled.

With the dehumidifier 800, the same effect as that of the fifth embodiment can be obtained. Furthermore, the measurement result by the ammeter 822 reflects the amount of water dehumidified by the second dehumidifying unit 2. Therefore, the humidity of the gas flowing through the emission unit 30 can be calculated from the difference between the humidity measured by the humidity detection unit 613 and the humidity calculated from the current flowing through the collecting electrode 24. Therefore, even if the humidity of the gas flowing through the discharging unit 30 is so low that the humidity detecting unit 723 of the dehumidifier 700 cannot detect it, the humidity of the gas flowing through the discharging unit 30 can be stabilized. Therefore, in the gas analyzer, highly accurate analysis can be performed without being affected by the fluctuation of humidity.

In controlling the humidity, it is desirable to use the absolute humidity. Therefore, it is desirable to measure the absolute humidity as well as the temperature by detecting the humidity and control the dehumidifying element 11 and the ion filter 22 based on the absolute humidity.

(Eighth Embodiment)
Next, an eighth embodiment will be described. FIG. 13 is a schematic diagram showing the configuration of the ion detection device according to the eighth embodiment.

The ion detection device 900 according to the eighth embodiment includes an ion filter 910, an ion detection electrode (ion detection unit) 920, and a dehumidifier 930. The ion filter 910 has a first electrode 911 and a second electrode 912 which face each other, and controls the mobility of passing ions. The ion filter 910 has, for example, a configuration similar to that of the ion filter 22 and functions similarly to the ion filter 22. The ion passing through the ion filter 910 collides with the ion detecting electrode 920. That is, the passing ions come into contact with the ion detection electrode 920. Then, the ion detection electrode 920 detects passing ions and outputs an electric characteristic value according to the strength of contact. Examples of the electrical characteristic value include a current value, a voltage value and a resistance value. The ion detection electrode 920 is an example of an output unit. The dehumidifier 930 is the dehumidifier of any of the first to seventh embodiments, and the sample gas 935 containing the ions emitted from the emission unit 30 is supplied to the ion filter 910.

According to the eighth embodiment, since the humidity of the sample gas 935 is extremely low, it is possible to perform highly accurate analysis without being affected by humidity.

1 1st dehumidification part 2 2nd dehumidification part 11 Dehumidification element 21 Ion generator 22 Ion filter 23 Exhaust part 24, 224 Collection ion electrode 30 Discharge part 31 Metal mesh 100, 200, 400, 500, 600, 700, 800 Dehumidifier 225 Drain pipe 226 Cooling unit 511 Multilayer dehumidifying element 611, 721, 821 Humidity control circuit 613, 723 Humidity detection unit 822 Ammeter 900 Ion detection device 910 Ion filter 920 Ion detection electrode 930 Dehumidifier

JP, 2005-158368, A

Claims (12)

A first dehumidifying unit for dehumidifying gas,
A second dehumidifying section for dehumidifying the gas dehumidified by the first dehumidifying section;
A discharge part for discharging the gas dehumidified by the second dehumidifying part;
Have
The said 2nd dehumidification part has an ion generator which produces|generates an ion from the gas dehumidified by the said 1st dehumidification part, The dehumidifier characterized by the above-mentioned. The dehumidifier according to claim 1, wherein the first dehumidifying section has a dehumidifying element having a polymer electrolyte membrane. The dehumidifier according to claim 2, wherein the first dehumidifying unit has a plurality of the dehumidifying elements stacked on each other. The first dehumidifying section,
A first humidity detector that detects the humidity of the gas that has passed through the dehumidifying element;
A first controller for controlling the dehumidifying element based on the humidity detected by the first humidity detector;
The dehumidifier according to claim 2 or 3, further comprising: The said 2nd dehumidification part has the 1st electrode and 2nd electrode which oppose, and is equipped with the ion filter which controls the mobility of the ion produced|generated by the said ion generator. The dehumidifier according to any one of items 1 to 4. The dehumidifier according to claim 5, wherein the ion filter passes only ions generated from water molecules among ions generated by the ion generator. The dehumidifier according to claim 5 or 6, wherein the second dehumidifying unit has a collecting ion electrode that attracts ions that have passed through the ion filter. The second dehumidifying section,
A cooling unit for cooling the collecting ion electrode,
A discarding unit for discarding water liquefied by the collecting ion electrode,
The dehumidifier according to claim 7, further comprising: The second dehumidifying section,
A second humidity detector for detecting the humidity of the gas flowing through the discharge part;
A second controller that controls the ion filter based on the humidity detected by the second humidity detector;
The dehumidifier according to any one of claims 5 to 8, further comprising: The first dehumidifying section,
A dehumidifying element having a polymer electrolyte membrane,
A first humidity detector that detects the humidity of the gas that has passed through the dehumidifying element;
A first controller for controlling the dehumidifying element based on the humidity detected by the first humidity detector;
Have
The second dehumidifying section,
An ion filter having a first electrode and a second electrode facing each other, and controlling the mobility of ions generated by the ion generator;
A collecting ion electrode that attracts ions that have passed through the ion filter;
An ammeter for measuring a current flowing through the collecting ion electrode,
A third controller for controlling the ion filter based on the humidity calculated from the current measured by the ammeter,
The dehumidifier according to claim 1, further comprising: The dehumidifier according to any one of claims 1 to 10, further comprising a member that is provided at the entrance of the discharge unit and to which a negative potential is applied. A dehumidifier according to any one of claims 1 to 11,
An output unit that contacts the ions that have passed through the dehumidifier and outputs an electrical characteristic value according to the strength of the contact,
A detection device comprising:

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