JP2002131301A - Purge-and-trap device and scavenging tube for purge- and-trap device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a purge-and-trap device using a scavenging tube having a high temperature rising speed and suppressing heat generation not contributing to heating the scavenging tube itself. SOLUTION: An insulating tube 60 is used as the scavenging tube 10. An electroconductive film 62 is stuck on an inner wall thereof and supplied with an electric current via feeders 70, current terminals 68, and conduction members 66, and thus a filler 62 can be effectively heated by a small current.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas chromatograph (GC), a gas chromatograph mass spectrometer (G).
The present invention relates to a purge and trap device used in a pretreatment section of a device for measuring a substance present in a gaseous state such as a CMS) and an odor measurement device. The present invention relates to a purge and trap device for guiding unnecessary components such as moisture and the like to a detection unit of a measurement device.

[0002]

2. Description of the Related Art Purge and trap devices are frequently used in various gas analyses for the purpose of efficiently collecting a sample gas. FIG. 4 is a diagram showing the entire configuration of a conventional odor identification device. As shown in the figure, the odor discriminating apparatus includes a pre-processing unit 10, a detection unit 20, and a PC 30 (control computer) for controlling the entire operation. Of these, the pre-processing unit 10 is for collecting the sample gas and concentrating the collected sample gas,
The preprocessing unit 10 and a PC that controls the operation of the preprocessing unit 10
30 constitute a purge and trap device. In the figure, reference numeral 1 denotes a collecting tube, which is filled with an adsorbent (for example, Tenax) and has a heating mechanism for heating the collecting tube. Reference numeral 2 denotes an odor sensor such as an oxide semiconductor. Reference numeral 11 denotes a first opening for gas introduction provided in the pre-processing unit. A valve 12, a T-shaped branching unit 13, and a valve 14 are connected downstream of the first opening, and a gas inlet end of the odor sensor 2 is provided downstream of the valve 14. Is connected. The gas outlet of the odor sensor is connected to the outlet 21. Reference numeral 15 denotes a second opening for gas introduction provided in the pre-processing unit, and a valve 16 and a T
The branching portion 17 and the valve 18 are connected, and the latter part of the valve 18 is connected to the outlet 22. And T-shaped branch 1
The other flow paths branched at 3 and the T-shaped branch 17 are connected to both ends of the collection tube 1 respectively. Here, detection unit 2
When a separation column is used in place of the odor sensor 2 of 0, the measurement is replaced with a gas chromatograph or a gas chromatograph mass spectrometer. Next, the operation of this device will be described. In this device, the following (1) to (4)
Are sequentially performed, whereby the odor measurement is repeated. (1) Sampling Step The valves 12 and 18 are opened, the valves 14 and 16 are closed, the collection tube 1 is set at a predetermined temperature T ₀ , the sample gas is supplied from the first opening 11 and discharged from the discharge port 22. As a result, the components in the sample gas are adsorbed and held by the adsorbent in the collection tube 1 and concentrated in the collection tube. Here, the predetermined temperature T
₀ is usually room temperature, but in the case of measuring a low-boiling substance such as hydrogen sulfide, the temperature is cooled to room temperature or lower (for example, about -20 degrees Celsius). In the case of measuring a high-boiling substance, for example, 1 degree Celsius
Heat to about 00 degrees. In short determine the temperature T ₀ of the time of sampling in accordance with the substance to be measured. (2) drying the step valve 12, 16 opens, the valve 14 and 18 are closed, the collecting tube 1 is dried _{N 2} from the second opening 15 in the predetermined temperature _{T 0}
Gas is introduced and discharged from the first opening 11. As a result, a dry purge is performed, and the moisture coexisting in the sample can be driven out. (3) Heat removal process (measurement process) The valves 16 and 14 are opened, the valves 12 and 18 are closed, and the collection tube 1 is collected by heating the collection tube 1 and introducing dry N ₂ gas from the second opening 15. The accumulated gas in the pipe is desorbed and led to the odor sensor 1. As a result, the odor sensor detects the odor component, and a sensor output is obtained. The heating temperature is equal to or higher than the temperature T ₁ (> T ₀ ) at which the substance to be measured can be desorbed. (4) Cleaning step after measurement The valves 16 and 14 are opened, the valves 12 and 18 are closed, and the collection tube 1 is heated to a high temperature. The collection tube 1 and the odor sensor 2 are cleaned by heating and introducing dry N ₂ gas from the second opening 15. High temperature heating temperature _{T 2} is above _{T 1.}

In FIG. 4, the piping configuration of the pretreatment section is the simplest structure, and in order to make it more practical, for example, Japanese Patent Application No. It is needless to say that each of the steps of sampling, drying, heating and ejection, and cleaning can be executed even with a six-way valve as disclosed in Japanese Patent Application No. 9-299382. In short, the collection tube filled with the adsorbent is kept at a low temperature, the sample gas is passed through the collection tube to adsorb the components in the sample gas, and then the adsorbent is rapidly heated to rapidly absorb the components. A device having a function of concentrating and sending out the gas is called a purge and trap device.

[0004]

FIG. 2 shows a conventional example of a collecting tube used for a purge and trap device. Collection tube 40
Is composed of a glass tube and is filled with an adsorbent (for example, Tenax). A heater wire 44 for heating the adsorbent is wound around the outer periphery of the glass tube. A Teflon (registered trademark) pipe 46 is connected to both ends of the glass tube (the other end of the Teflon pipe is connected to T
To the branch portions 13 and 17), whereby the sample gas and the dry N ₂ gas are supplied into the collection tube. Although the collection tube 40 having this structure can be manufactured at low cost, the heating is performed by a heater wound around the outside of the glass tube, so that the filler cannot be efficiently heated, and unnecessary unnecessary heating is not effective. Because there was also a lot of heat (the amount of heat radiated outside the heater hardly contributes to heating),
The rate of temperature rise of the collection tube could not be increased. It is advantageous to elevate the sample gas concentrated in the collection tube in a short period of time as high as possible in order to increase the signal intensity of the measurement signal. , It is necessary to raise the temperature of the collection tube sharply,
As described above, if the heating rate is low, it is disadvantageous in that the signal strength is increased. Further, since the time required for one measurement is increased because the heating rate does not increase, the time required to complete all measurements in the case of continuous measurement is increased. Further, in the purge and trap device for the odor measuring device, it is desirable that the device itself be driven by a battery to make it compact and usable regardless of the place (especially in the case of outdoor measurement, portability is required). In this case, it is necessary to reduce the energy consumed by the purge and trap device as a pretreatment unit as much as possible. However, when the above-described collection tube is used, heat is radiated from the heater 44 not only inside the heater but also outside the heater,
Since radiant energy emitted toward the outside of the heater does not contribute to heating of the glass tube 40 at all, a large amount of energy is wasted when driving the battery, which is a factor that hinders compactness due to the battery driving. I have.

FIG. 3 shows another conventional example. The collection tube 50 is a stainless steel tube (filled with an adsorbent) instead of glass as the collection tube material. Current terminals 52 are provided near both ends of the collection tube 50, and a power supply line 54 connected to an external power supply is provided. The stainless steel tube itself is used as a heater. Teflon piping 56 is connected to both ends of the stainless steel tube so that a sample gas or the like is supplied. Since the stainless steel tube can be heated by applying an electric current to the stainless steel tube itself, the temperature rising rate can be increased as compared with that of FIG. However, since a metal tube is used as the material of the collection tube, the electric resistance value of this portion is low, the required current value is large, and it becomes difficult to drive the battery.
Further, heat radiation to the outside of the stainless steel tube cannot be ignored, and an unnecessary amount of heat is required.

Accordingly, the present invention is to increase the temperature rising speed of the collecting tube and reduce unnecessary heat which does not contribute to the heating of the collecting tube, thereby enabling battery driving. It is an object of the present invention to provide a purge and trap device and a collection tube therefor.

[0007]

A purge and trap apparatus according to the present invention, which has been made to solve the above-mentioned problem, comprises supplying a sample gas to a collection tube filled with an adsorbent in an unheated state. In the purge and trap apparatus for removing the concentrated sample gas by supplying the carrier gas while heating the collection tube, wherein the collection tube has an insulating material. Is used, a conductive film is attached to the inner wall surface thereof, and a current introducing terminal is attached at both ends of the collection tube via conductive members electrically connected to the conductive film, respectively. The collector tube is heated by supplying an electric current to the collector tube. Further, in order to solve the above problem, the collecting tube of the present invention uses an insulating material for the collecting tube, has a conductive film adhered to the inner wall surface thereof, and has the conductive film at both ends of the collecting tube. A current introduction terminal is attached via a conductive member electrically connected to the conductive film,
By supplying a current to the current introduction terminal, the collection tube is heated.

In the present invention, the collection tube is made of an insulating material, and the inner surface thereof is coated with a conductive film. The conductive film is thin and has a higher resistance than a metal tube. Therefore, when a current is caused to flow through this conductive film to heat the collection tube, heating can be performed with a relatively small current value, which is suitable for battery operation. In addition, since heat conduction is relatively poor outside the conductive film and there is an insulating material that does not transmit infrared rays, efficient heating can be performed. In addition, since the conductive film serves as the inner surface of the collection tube, it can be in close contact with the filler, and the filler can be directly heated by heat conduction or radiation.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a collecting pipe portion of a purge and trap device showing one embodiment of the present invention. The purge and trap device itself is basically the same as that shown in FIG. 4 shown in the conventional example, and the description thereof will be omitted by retaining the same reference numerals. The collection tube 60 is formed of an insulating tube made of an insulating material such as glass. As the insulating tube, for example, Kovar glass is preferable. The inside of the insulating tube is filled with a filler (for example, Tenax) having an ability to adsorb the sample gas. A conductive film 64 is formed on the inner wall of the insulating tube. As the conductive film material, any material such as platinum and nichrome may be used as long as it has conductivity. However, depending on the type of the sample gas, corrosion resistance or the like is required in addition to conductivity. For example, gold is preferably used. The deposition of gold on the inner surface of Kovar glass can be performed by a coating process such as electroless plating. At both ends of the insulating tube, a tubular conductive member 66 is provided.
Is attached. When the insulating member is made of Kovar glass, the conductive member 66 is preferably made of metal Kovar. The conductive member 66 is inserted into the end of the insulating tube 60 so as to be electrically connected to the gold on the inner surface of the glass. In the case of a combination of Kovar glass and metal Kovar, it can be welded, so that the problem of poor conduction hardly occurs, which is convenient. When Kovar is not used, for example, an insulating material such as an alumina tube or Macor glass is suitable. On the other hand, as the conducting member, a stainless steel tube or the like is suitable instead of metal Kovar. Then, the conductive member 66
A current terminal 68 is formed on an outer portion of the cable which is not inserted into the insulating tube 60, and a power supply line 70 connected to an external power supply (not shown) is connected to the current terminal 68.

Next, the operation of the present apparatus will be described. The collection tube having the above structure is connected to a collection tube attachment portion of the purge and trap device (two T-shaped branch portions 13 in the device of FIG. 4).
17), and the components in the sample gas are adsorbed and dried in the collection tube by executing the above-described sampling step and drying step. Subsequently, a current is passed from the power supply line 70 connected to a power supply (not shown) to the conductive film 64 via the terminal 68 and the conductive member 66 to heat the collection tube. The conductive film 64 itself is much thinner than the tube material and has a higher resistance, so that it can be heated only by passing a small current.

The purge and trap device of the present embodiment
It was used for the odor measurement device, but not limited to this.
It goes without saying that the present invention may be applied to pretreatment of other gas analyzers such as a gas chromatograph, a gas chromatograph mass spectrometer, and the like.

[0012]

As described above, in the purge and trap apparatus of the present invention, steep heating can be performed only by passing a small current. Therefore, the components adsorbed in the collection tube can be sent to the detection unit attached at the subsequent stage at a stretch, and the signal intensity can be increased. In addition, since the purge and trap device can be driven with a small current, it is possible to drive the battery.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a collection pipe portion of a purge and trap device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a collecting pipe portion of a conventional purge and trap device.

FIG. 3 is a configuration diagram of a collecting pipe portion of another conventional purge and trap device.

FIG. 4 is a configuration diagram of an odor measurement device using a purge and trap device.

[Explanation of symbols]

1: Collection tube 2: Odor sensor 10: Pretreatment section (main part of purge and trap device) 11: First opening 12, 14, 16, 18: Valve 13, 17: T-shaped branch section 15: Second opening Reference Signs List 20: detection unit 21, 22: discharge port 30: PC unit (control unit of purge and trap device) 60: insulating tube 62: filler 64: conductive film 66: conductive member 68: current terminal 70: power supply line

Claims (2)

[Claims] 1. A sample gas is supplied to a collection tube filled with an adsorbent, thereby concentrating the sample gas by adsorbing the sample gas on the adsorbent, and then supplying a carrier gas while heating the collection tube. In the purge and trap apparatus for taking out the concentrated sample gas, an insulating material is used for the collection tube, and a conductive film is attached to an inner wall surface of the collection tube. A purge and feed terminal, wherein a current introduction terminal is attached via a conductive member electrically connected to the membrane, and a current is supplied to the current introduction terminal to heat the collection tube. Trap device. 2. An insulating material is used for the collection tube main body, and a conductive film is attached to an inner wall surface of the collection tube main body, and conductive members electrically connected to the conductive film at both ends of the collection tube main body, respectively. A collecting tube for a purge and trap device, wherein a current introducing terminal is attached through the intermediary terminal and a current is supplied to the current introducing terminal to heat the collecting tube.