JP5108711B2 - Gas sampling method and apparatus - Google Patents

Description

    TECHNICAL FIELD The present invention relates to a gas sampling method and a sampling apparatus, and more particularly, a gas sampling method and a sampling including a gas containing a highly dangerous component such as a flammable gas, a toxic gas, and a special high-pressure gas, and a gas containing dust and moisture such as combustion exhaust gas. Relates to the device.

The following three methods are known as gas sampling methods.
(1) A method in which the inside of the vacuum vessel is previously evacuated, the valve is opened, the target gas is sucked and collected.
The vacuum container is made of a material such as glass, metal, resin, etc., and is manufactured with strength that can withstand vacuum.
Therefore, the amount of gas collected must be less than the internal volume of the vacuum container, and the container is heavy, so it is not suitable for collecting a large amount of gas. Even if the inside of the vacuum container is contaminated, it takes time to clean the inside. There have been problems such as this being impossible or impossible to clean.
(2) A method in which gas is sucked using a pump and collected in a sample bag.
This method is the most versatile, and various types of gases can be collected by arbitrarily selecting the type of pump, the material of the gas contact part, and the material and capacity of the sample bag.
However, when collecting gas containing highly dangerous components such as flammable gas, toxic gas, special high pressure gas, or when collecting gas containing dust or moisture such as combustion exhaust gas, There were problems such as difficult material selection and significant contamination and deterioration of the gas contact part.

(3) A method in which a sample bag is placed in a sample box, and the sample box is decompressed with a pump to collect gas in the sample bag.
Although the pump is not polluted by the gas, the suction pressure of the pump is higher than the pressure resistance of the sample bag, and there is a problem that the sample bag is damaged when a gas exceeding the specified volume of the sample bag is collected.
Therefore, a method for collecting a specified volume of sample back gas by adding a timer stop function and a mass flow control function to the pump has been put into practical use.
However, pumps with these functions are expensive, and there are problems such as the possibility of collecting excessive gas and damaging the sample bag due to human error such as incorrect setting.
JP-A-5-52719 JP-A-8-110287 Japanese Patent Laid-Open No. 8-313412 JP-A-11-153525 JP 2003-57155 A

  The present invention eliminates the problems of the above-mentioned known techniques, minimizes contamination and deterioration of the gas contact part, does not use expensive functions, and prevents damage to the sample bag due to human error. It is an object to provide a sampling method and a sampling apparatus.

In order to solve the above problems, in the present invention, a sample bag connected to an intake pipe is accommodated in a sample box connected to an exhaust pipe having an airtight structure, and the gas in the sample box is discharged. Then, in the method of collecting gas in the sample bag, a vacuum container having a volume equal to or less than a specified volume of the sample bag is connected to an exhaust pipe of the sample box, and the gas in the sample box is sucked. A gas collecting method is characterized in that gas is collected in a sample bag.
In the gas sampling method, the intake pipe may replace the gas in the pipe with an inert gas before and after collecting the gas in the sample bag, and the sample box is provided in the box. The gas may be replaced with an inert gas before collecting the gas in the sample bag.

In the present invention, the sample bag connected to the intake pipe is accommodated in a sample box connected to an exhaust pipe having an airtight structure, and the gas in the sample box is discharged, thereby In the gas sampling apparatus, the gas sampling apparatus is characterized in that a vacuum vessel having an opening / closing valve having a volume equal to or less than a specified volume of the sample bag is connected to an exhaust pipe of the sample box.
In the gas sampling device, the intake pipe, the sample bag, the sample box, the exhaust pipe, and the vacuum vessel are detachable, and the sample box is opened and closed so that the sample bag can be exchanged and the confidentiality is maintained. In addition, the vacuum vessel, the exhaust pipe, the sample box or the on-off valve may be provided with a mechanism for adjusting the suction speed of the gas in the sample box.

  According to the present invention, since it is only the intake pipe and the sample bag that are contaminated with the sampled gas, the cleaning effort can be reduced, and an accident in which an excessive amount of gas is sampled by human error and the sample bag is damaged. Can be prevented.

Hereinafter, the present invention will be specifically described with reference to the drawings.
First, a known technique will be described with reference to FIG. 2. FIG. 2 (a) shows before gas collection, and FIG. 2 (b) shows after gas collection.
FIG. 2 shows that the sample bag 2 connected to the intake pipe 1 is accommodated in the sample box 3, and the gas in the sample box 3 is discharged by the exhaust means 4 connected to the exhaust pipe 5. It is a method to collect.
The gas in the sample box 3 is exhausted by the exhaust means 4 through the exhaust pipe 5, and gas is collected in the sample bag 2 through the intake pipe 1 accordingly.
In this method, since the internal volume of the sample box 3 is larger than the specified volume of the sample bag 2, the exhaust pressure of the exhaust means 4 is higher than the withstand pressure of the sample back 2, and the exhaust amount by the exhaust means 4 is the sample back 2. If the volume exceeds the specified volume, the sample bag will break.

Next, the present invention will be described with reference to FIG.
FIG. 1 shows a first embodiment of the present invention, in which FIG. 1 (a) is before gas collection, and FIG. 1 (b) is after gas collection.
FIG. 1 shows that a sample bag 2 connected to an intake pipe 1 is accommodated in a sample box 3, and an open / close valve 7 of a vacuum vessel 6 connected to an exhaust pipe 5 is opened to suck gas in the sample box 3. In this way, gas is collected in the sample bag 2.
In this method, the internal volume of the sample box 3 is larger than the specified volume of the sample bag 2, but the internal volume of the vacuum container 6 is less than or equal to the specified volume of the sample bag 2, and the sample bag 2 contains the contents of the vacuum container 6. Since only the gas amount less than the product is collected, the sample bag 2 is not damaged.
Furthermore, even if the sample bag 2 is damaged for some reason, the gas stays in the sample box 3, so that highly dangerous gas can be safely collected.

Also, the sample box shown in FIG. 1 can be opened and closed and has an airtight structure, and the intake pipe, the sample bag, the sample box, the exhaust pipe, and the vacuum container are detachable, and the vacuum container is shown in the figure. By repeatedly depressurizing with no vacuum pump and replacing the sample bag sequentially, gas can be collected repeatedly.
Further, by using joints having different shapes for the attachment / detachment mechanism of the intake pipe, the sample box, and the sample bag, and the attachment / detachment mechanism of the sample box, the exhaust pipe, and the vacuum vessel, erroneous connection can be prevented.

The intake pipe and the exhaust pipe can be made of a material such as rubber, polyethylene resin, fluororesin, or stainless steel, and preferably have flexibility. The inner volume of the intake pipe is preferably 5% or less of the specified volume of the sample bag. The smaller the inner volume of the intake pipe relative to the specified volume of the sample bag, the more undiluted gas can be collected. By setting the inner volume of the intake pipe to 5% or less of the specified volume of the sample bag, the gas concentration collected in the sample bag can be 95% or more of the sampled gas concentration, and the analysis error can be reduced. .
The intake pipe is preferably replaced with an inert gas before and after collecting the gas in the pipe into the sand bag.
In particular, when a natural gas such as silane is collected, the silane oxidation or ignition combustion can be prevented by replacing the gas in the tube with an inert gas.
Nitrogen, argon, carbon dioxide or the like can be used as the inert gas.

The sample bag can be made of a material such as vinyl fluoride resin, a copolymer of tetrafluoroethylene and hexafluoropropylene, nylon, polyethylene, aluminum, or polystyrene.
As the sample box, a container such as a vinyl chloride resin, an acrylic resin, or a metal can be used. The sample box is openable and airtight, and preferably has a structure in which an intake pipe, a sample bag, and an exhaust pipe can be attached and detached. Further, the internal volume is preferably 2.0 times or less, more preferably 1.5 times or less that of the sample bag.

  Since the inside of the sample box is uniformly depressurized by the vacuum container, the amount of gas that can be collected in the sample bag increases as the internal volume of the sample box decreases. The internal volume of the sample box is 3 times the specified volume of the sample bag, the internal volume of the vacuum container is the same as the specified volume of the sample bag, the pressure of the vacuum container is -90 kPa by gauge pressure, and the pressure of the sampled gas is -3 kPa When the internal volumes of the intake pipe and the exhaust pipe are ignored, the amount of gas that can be collected in the sample bag remains at 81% of the specified volume. On the other hand, the internal volume of the sample box is twice the specified volume of the sample bag, the internal volume of the vacuum container is the same volume as the specified volume of the sample bag, the pressure of the vacuum container is -90 kPa by gauge pressure, and the pressure of the sampled gas is- When the internal volume of the intake pipe and the exhaust pipe is ignored at 3 kPa, 84% of the specified volume of gas can be collected in the sample bag. Furthermore, the internal volume of the sample box is 1.5 times the specified volume of the sample bag, the internal volume of the vacuum container is the same volume as the specified volume of the sample bag, the pressure of the vacuum container is -90 kPa in terms of gauge pressure, When the pressure is −3 kPa and the internal volumes of the intake pipe and the exhaust pipe are ignored, 87% of the specified volume of gas can be collected in the sample bag.

The gas in the sample box is preferably replaced with an inert gas before collecting the gas.
In particular, when a natural gas such as silane is collected, replacement with an inert gas can prevent ignition and combustion of the natural gas even if the sample bag is defective or damaged.
As the vacuum container, a container made of vinyl chloride resin, acrylic resin, metal, or the like can be used. The pressure resistance of the vacuum vessel is preferably -90 kPa or less, more preferably -101 kPa, in terms of gauge pressure.
When the pressure resistance of the vacuum container is low, the inside of the vacuum container cannot be sufficiently depressurized, and the amount of gas that can be collected in the sample bag is reduced.
As a mechanism for adjusting the suction speed of the gas in the sample box, a needle valve, an orifice tube, or the like can be used.

Example 1
The amount of collected gas was compared between the conventional example shown in FIG. 2 and the example of the present invention shown in FIG.
A fluororesin pipe was used for the intake pipe and the exhaust pipe, and a cubic transparent vinyl chloride container having an internal volume of 10 L was used for the sample box.
For the pump of the exhaust means, a suction pressure of −30 kPa and an exhaust amount of 2.4 L / min when released to the atmosphere were used.
A metal container with an internal volume of 4 L was used as the vacuum container, an orifice and a valve were attached, and the inside was set to a gauge pressure of -90 kPa.
A sample bag having a specified volume of 5 L in which the outer periphery of the resin multilayer film was fused was used.
The experimental results are shown in Table 1.

従来例では、吸引ガス圧力０ｋＰａの場合、採取時間２．６分でサンプルバッグが破損し、吸引ガス圧力−３ｋＰａの場合、採取時間３．３分でサンプルバッグが破損した。
一方、本発明の例ではサンプルバッグは破損しなかった。

In the conventional example, when the suction gas pressure was 0 kPa, the sample bag was broken at a collection time of 2.6 minutes, and when the suction gas pressure was -3 kPa, the sample bag was broken at a collection time of 3.3 minutes.
On the other hand, the sample bag was not damaged in the example of the present invention.

The block diagram which shows an example of the sampling device of the gas of this invention. The block diagram which shows an example of the well-known gas extraction apparatus.

Explanation of symbols

1: Intake pipe, 2: Sample back, 3: Sample box,
4: exhaust means, 5: exhaust pipe, 6: vacuum vessel, 7: valve

Claims (6)

  A method of collecting gas in the sample bag by storing the sample bag connected to the intake pipe in a sample box connected to an exhaust pipe having an airtight structure and discharging the gas in the sample box In the method, a vacuum container having a predetermined volume or less of the sample bag is connected to an exhaust pipe of the sample box, and gas is collected in the sample bag by sucking the gas in the sample box. How to collect gas.   The gas sampling method according to claim 1, wherein the intake pipe replaces the gas in the pipe with an inert gas before and after collecting the gas in the sample bag.   The gas sampling method according to claim 1 or 2, wherein the sample box replaces the gas in the box with an inert gas before collecting the gas in the sample bag.   An apparatus for collecting gas in the sample bag by accommodating the sample bag connected to the intake pipe in a sample box connected to an exhaust pipe having a gastight structure and discharging the gas in the sample box The gas sampling apparatus according to claim 1, wherein a vacuum container having an opening / closing valve having a volume equal to or less than a specified volume of the sample bag is connected to the exhaust pipe of the sample box.   The intake pipe, the sample bag, the sample box, the exhaust pipe, and the vacuum container are detachable, respectively, and the sample box has a structure that can be opened and closed so that the sample bag can be exchanged and maintain airtightness. The gas sampling device according to claim 4.   The gas sampling apparatus according to claim 4 or 5, wherein the vacuum container, the exhaust pipe, the sample box or the on-off valve is provided with a mechanism for adjusting a suction speed of the gas in the sample box.

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