JP2021162545A - Gas component detector - Google Patents

Abstract

To shorten the detection time while realizing high detection sensitivity in detecting gas components by gas chromatography.SOLUTION: A gas component detector 10 comprises a first passage 21 and a column 30. The column 30 is arranged upstream of a sensor 42 in the conveyance direction of a carrier gas which is mixed with the gaseous substance to be detected. The first passage 21 is connected between the column 30 and the sensor 42. The column 30 includes a plurality of individual passages 31-34. The cross section area of the whole of passages of the column 30 is larger than a cross sectional area S21 of the first passage 21. Thus, the flow velocity of the carrier gas in the column 30 is slowed down while maintaining the flow velocity of the carrier gas in the first passage 21 at a prescribed velocity.SELECTED DRAWING: Figure 1

Description

The present invention relates to a gas component detection device that detects a gas component by using a gas chromatography technique.

At present, various devices for detecting components by chromatography (see, for example, Patent Document 1) have been put into practical use. And as a kind of chromatography, there is gas chromatography. Gas chromatography detects components contained in a gas.

Conventionally, a gas component detection device using gas chromatography detects a gas component by transporting the gas to be detected by a carrier gas and exposing it to a detector. Then, such a gas component detection device uses a column.

The column is a so-called flow path of a carrier gas mixed with a gas to be detected, and is arranged on the upstream side of the detector. Then, by appropriately setting the specifications of the column, the plurality of components in the gas to be detected and the carrier gas pass through the column at different propagation times. As a result, the time it takes for the plurality of components contained in the gas to be detected to reach the detector differs. Therefore, the detector can detect a plurality of components individually.

Special Table 2005-517197

However, when a specific sensor (semiconductor type, contact combustion type, electrochemical type) is used as the detector, it is not easy to shorten the detection time while ensuring the detection sensitivity at a predetermined level.

Therefore, an object of the present invention is to have high detection sensitivity and shorten the detection time while using a specific sensor such as a semiconductor sensor as a detector.

The gas component detection device of the present invention includes a column, a first flow path, and a delay mechanism. The column is arranged on the upstream side of the semiconductor sensor in the transport direction of the carrier gas mixed with the gas to be detected. The first flow path is connected between the column and the semiconductor sensor. The delay mechanism makes the flow rate of the carrier gas in the column slower than the flow rate of the carrier gas in the first flow path.

In this configuration, the flow velocity of the gas to be detected flowing through the column is slow, and the separability of a plurality of components of the gas to be detected is improved. Further, in this configuration, the flow velocity of the gas to be detected reaching the semiconductor sensor is high, and the detection speed is high.

According to the present invention, the detection time can be shortened while achieving high detection sensitivity.

FIG. 1 is a diagram showing a configuration of a gas component detection device according to an embodiment of the present invention. FIG. 2 is a graph showing the transition state of the output voltage of the semiconductor sensor for each concentration. FIG. 3 is a graph showing the transition state of the output voltage of the semiconductor sensor for each flow velocity in the cavity. FIG. 4 is a diagram showing a chromatogram of gas chromatography according to the configuration of the present invention and a chromatogram according to a comparative configuration. FIG. 5 is a schematic view showing the configuration of a column portion in the gas component detection device according to the embodiment of the present invention.

The gas component detection device according to the embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a configuration of a gas component detection device according to an embodiment of the present invention. Note that FIG. 1 schematically shows an example of a gas component detection device using a functional block or the like.

(Structure of gas component detection device 10)
As shown in FIG. 1, the gas component detection device 10 includes a first flow path 21 and a column 30. Further, the gas component detection device 10 includes a second flow path 22, a third flow path 23, a fourth flow path 24, a fifth flow path 25, a sixth flow path 26, a sensor device 40, a component detection unit 43, and a blower 51. , A filter 52, a charging container 60, a valve 231 and a drive unit 510.

The first flow path 21, the second flow path 22, the third flow path 23, the fourth flow path 24, the fifth flow path 25, and the sixth flow path 26 are tubular with a constant diameter.

One end of the first flow path 21 is connected to the sensor device 40, and the other end of the first flow path 21 is connected to the column 30. One end of the second flow path 22 is connected to the column 30, and the other end of the second flow path 22 is connected to the discharge port of the blower 51.

One end of the third flow path 23 is connected to the second flow path 22, and the other end of the third flow path 23 is connected to the charging container 60. The valve 231 is provided in the third flow path 23. The communication state between the second flow path 22 and the charging container 60 is controlled by opening and closing the valve 231.

One end of the fourth flow path 24 is connected to the sensor device 40, and the other end of the fourth flow path 24 is the discharge port 240.

One end of the fifth flow path 25 is connected to the suction port of the blower 51, and the other end of the fifth flow path 25 is connected to the filter 52. One end of the sixth flow path 26 is connected to the filter 52, and the other end of the sixth flow path 26 is connected to the carrier gas intake port 260.

The column 30 includes an individual flow path 31, an individual flow path 32, an individual flow path 33, and an individual flow path 34. The first end of the individual flow path 31, the first end of the individual flow path 32, the first end of the individual flow path 33, and the first end of the individual flow path 34 are connected by the flow path connecting portion 301. The second end of the individual flow path 31, the second end of the individual flow path 32, the second end of the individual flow path 33, and the second end of the individual flow path 34 are connected by the flow path coupling portion 302. The flow path coupling portion 301 is connected to the first flow path 21, and the flow path coupling portion 302 is connected to the second flow path 22. The column 30, that is, the individual flow path 31, the individual flow path 32, the individual flow path 33, and the individual flow path 34 is made of a flexible material and does not react with the gas to be detected. The specific configuration of the column 30 will be described later.

The sensor device 40 includes a cavity 41 and a sensor 42. The cavity 41 is a space formed by the housing of the sensor device 40, and includes an inflow port 411 and an outflow port 412. The inflow port 411 communicates with the first flow path 21, and the outflow port 412 communicates with the fourth flow path 24.

The sensor 42 has a detection surface 420. The sensor 42 is arranged in the housing of the sensor device 40 so that the detection surface 420 is exposed in the cavity 41. The sensor 42 outputs a voltage having an intensity corresponding to the concentration of the gas component in contact with the detection surface 420 from the output terminal 421. Specifically, the sensor 42 is, for example, a semiconductor type sensor. The sensor 42 is not limited to the semiconductor type sensor, and may be a contact combustion type or an electrochemical type sensor.

The component detection unit 43 detects the component of the gas to be detected and its concentration by using the output voltage of the sensor 42. The component detection unit 43 has a known configuration, and a specific description thereof will be omitted.

The blower 51 is a device that conveys a fluid in one direction, and is, for example, a blower using a piezoelectric material. The blower 51 can be miniaturized by using a blower using a piezoelectric material. A drive unit 510 is connected to the blower 51. The drive unit 510 supplies drive power to the blower 51. The blower 51 is driven by this driving power and conveys the fluid from the suction port to the discharge port.

The filter 52 is a gas purification filter, and filters impurities such as dust and fine particles contained in air, for example. The charging container 60 contains the gas to be detected. For example, in the case of a device used by a gas component detecting device to detect a specific component (for example, an acetone component) in human exhaled breath, human exhaled breath is stored in a charging container 60 in advance.

(Transportation of gas to be detected and method for detecting component in gas component detection device 10)
In the above configuration, the blower 51 is driven to open the valve 231. As a result, the air that is the source of the carrier gas flows into the sixth flow path 26 from the carrier gas intake port 260 and is filtered by the filter 52. As a result, a carrier gas is generated. The carrier gas is conveyed from the filter 52 to the fifth flow path 25 and is sucked into the blower 51. The blower 51 discharges the carrier gas into the second flow path 22.

When the carrier gas flows through the second flow path 22, the gas to be detected flows into the second flow path 22 from the charging container 60 via the third flow path 23. As a result, the gas to be detected is mixed with the carrier gas, and the carrier gas mixed with the gas to be detected (hereinafter, referred to as a mixed gas for convenience of explanation) is conveyed from the second flow path 22 to the column 30.

The mixed gas carried into the column 30 is separated into the individual flow path 31, the individual flow path 32, the individual flow path 33, and the individual flow path 34 at the flow path coupling portion 302. The mixed gas flows into the individual flow path 31, the individual flow path 32, the individual flow path 33, and the individual flow path 34, respectively. At this time, the flow velocity of the mixed gas flowing through the individual flow paths 31-34 decreases. The mixed gas flowing through the individual flow path 31, the individual flow path 32, the individual flow path 33, and the individual flow path 34 is combined at the flow path coupling portion 301 and flows into the first flow path 21. By merging the mixed gas flowing in the individual flow paths 31-34, the flow velocity of the mixed gas in the first flow path 21 becomes high again.

The mixed gas that has flowed through the first flow path 21 flows into the cavity 41 from the inflow port 411, and is discharged from the discharge port 240 from the outflow port 412 via the fourth flow path 24. At this time, the mixed gas comes into contact with the detection surface 420 of the sensor 42 in the cavity 41, so that the component of the gas to be detected is detected.

Since the plurality of components of the gas to be detected have different flow velocities in the column 30, the sensor 42 can detect the plurality of components individually.

(Specific configuration of column 30)
As described above, the column 30 includes an individual flow path 31, an individual flow path 32, an individual flow path 33, and an individual flow path 34. The individual flow path 31, the individual flow path 32, the individual flow path 33, and the individual flow path 34 are connected in parallel between the flow path coupling portion 301 and the flow path coupling portion 302.

The individual flow path 31, the individual flow path 32, the individual flow path 33, and the individual flow path 34 are tubular with a constant diameter. The flow path cross-sectional area S31 of the individual flow path 31, the flow path cross-sectional area S32 of the individual flow path 32, the flow path cross-sectional area S33 of the individual flow path 33, and the flow path cross-sectional area S34 of the individual flow path 34 are the same. .. In the present application, the flow path cross-sectional area is the area of the cut surface of the internal space when the pipe is cut on a plane orthogonal to the extending direction of the pipe, and the column has a plurality of individual flow paths. In the case, it refers to the area obtained by adding the cross-sectional areas of each of these individual flow paths.

Further, the internal structure of the individual flow path 31, the internal structure of the individual flow path 32, the internal structure of the individual flow path 33, and the internal structure of the individual flow path 34 are the same. The same internal structure means, for example, that the material and thickness of the adsorbent or carrier formed on the inner wall surface of the pipe are the same. Compared with the structure in which the adsorbent or the carrier is filled in the pipe, the individual flow path 31, the individual flow path 32, the individual flow path 33, and the individual flow path 33 are formed by forming the adsorbent or the carrier on the inner wall surface of the tube. It is easy and effective to make the internal structure of the individual flow path 34 more accurate and the same. As the column 30, either a packed column or a capillary column may be used. As the stationary phase and the liquid phase, known ones can be used.

In such a configuration, the flow path cross-sectional area S31 of the individual flow path 31, the flow path cross-sectional area S32 of the individual flow path 32, the flow path cross-sectional area S33 of the individual flow path 33, and the flow path cross-sectional area of the individual flow path 34. S34 is the same as the flow path cross-sectional area S21 of the first flow path 21.

The flow path cross-sectional area as the column 30 is the flow path cross-sectional area S31 of the individual flow path 31, the flow path cross-sectional area S32 of the individual flow path 32, the flow path cross-sectional area S33 of the individual flow path 33, and the individual flow path 34. It is an area obtained by adding the flow path cross-sectional area S34. Therefore, the flow path cross-sectional area of the column 30 is larger than the flow path cross-sectional area S21 of the first flow path 21. As a result, the flow velocity of the mixed gas flowing through the column 30 becomes slower than the flow velocity of the mixed gas flowing through the first flow path 21. That is, the column 30 functions as a delay mechanism.

(Action and effect due to the configuration of the gas component detection device 10)
By providing the gas component detection device 10 with the above-described configuration, the following effects can be obtained.

FIG. 2 is a graph showing the transition state of the output voltage of the semiconductor sensor for each concentration. FIG. 2 shows a case where one kind of component (for example, acetone) to be detected is detected. In FIG. 2, the horizontal axis represents the elapsed time from the start of detection, and the vertical axis represents the voltage difference ΔV with respect to the baseline voltage. FIG. 2 shows the cases of the concentration DE1, the concentration DE2, the concentration DE3, and the concentration DE4. The concentration DE3 is higher than the concentration DE4, the concentration DE2 is higher than the concentration DE3, and the concentration DE1 is higher than the concentration DE2. That is, there is a relationship of concentration DE1> concentration DE2> concentration DE3> concentration DE4.

As shown in FIG. 2, when the sensor 42 is used, the higher the concentration of the component to be detected, the higher the voltage difference ΔV at the time of saturation. Therefore, the gas component detection device 10 can detect the concentration of the component from the magnitude of the voltage difference ΔV.

FIG. 3 is a graph showing the transition state of the output voltage of the semiconductor sensor for each flow velocity in the cavity. FIG. 3 shows a case where one kind of component (for example, acetone) to be detected is detected. In FIG. 3, the horizontal axis represents the elapsed time from the start of detection, and the vertical axis represents the voltage difference ΔV with respect to the baseline voltage. FIG. 3 shows the case of the flow velocity FV1, the flow velocity FV2, the flow velocity FV3, and the flow velocity FV4. The flow velocity FV3 is higher than the flow velocity FV4, the flow velocity FV2 is higher than the flow velocity FV3, and the flow velocity FV1 is higher than the flow velocity FV2. That is, there is a relationship of flow velocity FV1> flow velocity FV2> flow velocity FV3> flow velocity FV4.

As shown in FIG. 3, when the sensor 42 is used, the higher the flow velocity of the mixed gas containing the component to be detected, the faster the time for the voltage difference ΔV (output voltage) with respect to the baseline voltage to saturate. That is, the transient response is high. Therefore, the higher the flow velocity, the shorter the time required to detect the component to be detected. That is, the detection time can be shortened by increasing the flow velocity of the first flow path 21.

Here, for example, in a conventional column not provided with the configuration of the present application, the flow velocity of the column becomes equivalent to the flow velocity of the first flow path 21. When the flow velocity in the column is high, the separability of the component of the gas to be detected in the column is lowered, and the desired sensitivity with respect to the component to be detected cannot be obtained.

However, in the gas component detection device 10 of the present invention, as described above, the flow velocity in the column 30 can be slower (lower) than the flow velocity in the first flow path 21. As a result, it is possible to suppress a decrease in the separability of the component of the gas to be detected in the column 30, and it is possible to detect the component to be detected with high sensitivity.

FIG. 4 is a diagram showing a chromatogram having a gas chromatography structure of the present invention and a chromatogram having a comparative structure. The comparative configuration does not include the column 30 having a large flow path cross-sectional area as in the present invention, has the same flow path cross-sectional area as the first flow path 21, and has the length of the individual flow paths 31-34 of the column 30. A configuration with columns of the same length as the total value is shown. As shown in FIG. 4, by providing the configuration of the present application, the signal strength of the component to be detected becomes higher than that of the comparative configuration. Therefore, the gas component detection device 10 of the present application can detect the component to be detected with high sensitivity.

As described above, by providing the configuration of the present embodiment, the gas component detection device 10 can shorten the detection time while detecting the component to be detected with high sensitivity.

Further, as shown in FIG. 2B, the relationship between the concentration and the voltage difference ΔV is the same as in the saturated state even during the transient response period. Therefore, it is possible to detect the concentration of the component to be detected with high accuracy even during the transient response period. Thereby, for example, as in the measurement time tm in FIG. 2, the component can be detected within the transient response period before the voltage difference ΔV is saturated, and the gas component detection device 10 can further shorten the detection time.

At this time, the flow path cross-sectional area S21 of the first flow path 21 is set based on the transient response characteristic of the detection of the sensor 42, that is, the reaction speed, and the flow path cross-sectional area of the column 30 (each individual flow path 31). , 32, 33, 34 (the sum of the flow path cross-sectional areas S31, S32, S33, S34)) may be set based on the separability of the components of the gas to be detected. That is, the ratio of the flow path cross-sectional area S21 of the first flow path 21 to the flow path cross-sectional area of the column 30 is required for the column 30 and the optimum measurement time tm that can maintain the accuracy in the sensor 42 and shorten the time. It is better if it is set based on the separability.

Further, in the above-mentioned column 30, the length L31 of the individual flow path 31, the length L32 of the individual flow path 32, the length L33 of the individual flow path 33, and the length L34 of the individual flow path 34 are as much as possible. It is preferable that they are the same. As a result, the difference in separation ability between the individual channels 31, 32, 33, and 34 is small or eliminated, and the component to be detected can be detected with higher sensitivity. However, the length L31 of the individual flow path 31, the length L32 of the individual flow path 32, the length L33 of the individual flow path 33, and the length L34 of the individual flow path 34 require the gas component detection device 10. It may be different within the range of the minimum resolution to be performed. It should be noted that this concept can be applied to the cross-sectional area of the flow path and the internal structure, and may be different within the allowable range of the separability, but it is preferable that they are the same as much as possible.

Further, the detection surface 420 of the sensor 42 is preferably parallel to the transport direction of the mixed gas in the cavity 41. By making the detection surface 420 parallel to the transport direction, the variation in the baseline of the signal strength is reduced. This is because, for example, the temperature change of the detection surface 420 of the sensor 42 due to the contact of the mixed gas can be suppressed.

Thereby, the SN ratio of the output voltage of the sensor 42 can be improved. Therefore, the gas component detection device 10 can detect the component to be detected with higher accuracy.

Further, the above-mentioned control of the flow velocity is realized by the blower 51 arranged on the upstream side of the second flow path 22. The flow path cross-sectional area S22 of the second flow path 22 is the same as the flow path cross-sectional area S21 of the first flow path 21. As a result, the flow velocity of the first flow path 21 can be easily controlled by arranging a current meter or the like in the second flow path 22, measuring the flow velocity, and feeding it back to the drive unit 510. By arranging the current meter on the upstream side of the connection position of the second flow path 22 with the third flow path 23, it is possible to prevent the current meter from being exposed to the gas to be detected.

Further, in the above configuration, the flow velocity is temporarily reduced in the column 30 after the same flow velocity as that of the first flow path 21 is obtained in the second flow path 22. Then, the third flow path 23 is connected to the second flow path 22 having a high flow velocity. As a result, the gas to be detected from the charging container 60 is drawn into the second flow path 22 by a high flow velocity, and the gas component detection device 10 can efficiently draw the gas to be detected.

Further, the third flow path 23 can be connected to a plurality of individual flow paths 31-34 of the column 30. However, as described above, by connecting the third flow path 23 to the second flow path 22, the drawing of the gas to be detected becomes efficient.

Further, in the above description, a mode is shown in which the flow path cross-sectional area of the column 30 is made larger than the flow path cross-sectional area S21 of the first flow path 21 by forming the column 30 with a plurality of individual flow paths 31-34. rice field. However, it is also possible to apply, for example, another aspect as shown in FIG. FIG. 5 is a schematic view showing the configuration of a column portion in the gas component detection device according to the embodiment of the present invention.

As shown in FIG. 5, the column 30A is a tubular having a diameter larger than that of the first flow path 21 and the second flow path 22. That is, the flow path cross-sectional area S30A of the column 30A is larger than the flow path cross-sectional area S21 of the first flow path 21 and the flow path cross-sectional area S22 of the second flow path 22.

Even with such a configuration, the gas component detection device can shorten the detection time while realizing high detection sensitivity.

It is also possible to combine the configuration shown in FIG. 1 and the configuration shown in FIG. 5 above. That is, the flow path cross-sectional area of the individual flow paths of the columns shown in FIG. 1 may be larger than the flow path cross-sectional area S21 of the first flow path 21. Further, if the flow path cross-sectional area as a column is larger than the flow path cross-sectional area S21 of the first flow path 21, the flow path cross-sectional area of the individual flow paths is relative to the flow path cross-sectional area S21 of the first flow path 21. It may be different, such as small.

10: Gas component detection device 21: 1st flow path 22: 2nd flow path 23: 3rd flow path 24: 4th flow path 25: 5th flow path 26: 6th flow path 30, 30A: Columns 31, 32 , 33, 34: Individual flow path 40: Sensor device 41: Cavity 42: Sensor 43: Component detection unit 51: Blower 52: Filter 60: Input container 231: Valve 240: Discharge port 260: Carrier gas intake port 301: Flow Road coupling unit 302: Flow path coupling unit 411: Inflow port 412: Outflow port 420: Detection surface 421: Output terminal 510: Drive unit

Claims (6)

A sensor that detects the components of the gas to be detected and
In the transport direction of the carrier gas mixed with the gas to be detected, the column arranged on the upstream side of the sensor and the column.
A first flow path connected between the column and the sensor,
With
The column includes a delay mechanism that slows the flow rate of the carrier gas in the column to be slower than the flow rate of the carrier gas in the first flow path.
Gas component detector. The delay mechanism
The column has a channel cross-sectional area larger than that of the first channel.
The gas component detection device according to claim 1. The delay mechanism
The column is composed of a plurality of individual flow paths.
The plurality of individual flow paths are connected to one flow path at the first end and the second end, respectively.
The first end includes the one connected to the first flow path.
The gas component detection device according to claim 2. The flow velocity of the column is set based on the separability of the components of the gas to be detected.
The flow velocity of the first flow path is set based on the reaction speed of the sensor.
The gas component detection device according to any one of claims 1 to 3. The sensor is a semiconductor type sensor.
The sensor and a sensor device having a cavity in which the detection surface of the sensor is incorporated.
With
The detection surface of the sensor is parallel to the transport direction of the carrier gas in the cavity.
The gas component detection device according to any one of claims 1 to 4. A detection unit for detecting a component of the gas to be detected from the output signal of the sensor is provided.
The detection unit detects the component from the transient response of the sensor.
The gas component detection device according to claim 5.

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