JP2007108021A - Automatic gas sampling device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas sampling device capable of automatically and continuously sampling a sample gas inside a closed circulation system in a short time, allowing improvement of durability of the device, and allowing diversification of a sampling pattern. <P>SOLUTION: This automatic gas sampling device has: the closed circulation system 1; a sampling loop 3 connected to the closed circulation system 1 through valves V1, V2, and connected to an exhaust device partitioned by a valve V3; and a carrier gas line 5 connected to the sampling loop 3 through valves V4, V5. By combining the plurality of valves and controlling opening/closing of the valves, a carrier gas is introduced to the sampling loop to collect the sample gas inside the closed circulation system and the carrier gas. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sampling apparatus that continuously and automatically collects gas generated in a closed circulation system in a catalytic reaction or the like in order to analyze or measure the gas.

In a conventional gas sampling device, a glass or Teflon (registered trademark) six-way valve or three-way cock is attached to the pipe, and this is rotated to move the sampling channel from the discharge part of the reaction system or the sample container. The gas is qualitatively and quantitatively analyzed by switching to an analysis system such as a gas chromatograph (see Patent Documents 1 and 2, for example).
JP 2003-4714 A JP 2000-9610 A

In conventional gas sampling devices, it has been difficult to automate sampling due to the nature of the cock used. For example, a glass hexagonal cock has little leakage of outside air and is very suitable for gas analysis under reduced pressure. However, its strength is low due to its material, and there is a drawback that it can be easily broken if rotation is automated by a motor or the like. On the other hand, the Teflon (registered trademark) hexagonal cock is suitable for automatic rotation using a motor, but the Teflon (registered trademark) rubbing part has poor durability, and gas leakage easily occurs when used for a long time. To do.
In addition, in a system using a hexagonal cock, the sampling loop is filled with carrier gas, so the sample gas in the closed circulatory system diffuses slowly into the sampling loop during sampling, and the sampling time is long. In particular, when the inside of the closed circulatory system is under reduced pressure, the carrier gas flows into the closed circulatory system, and the pressure and composition in the closed circulatory system vary greatly every sampling.

  Therefore, an object of the present invention is to automatically and continuously sample the sample gas in the closed circulation system in a gas sampling apparatus in a short time (including intermittent, the same applies hereinafter), and further, the durability of the apparatus. An object of the present invention is to provide an apparatus capable of improving the sampling rate and diversifying the sampling pattern.

In order to achieve the above object, the present inventors have switched the flow path by combining a plurality of electromagnetic valves or compressed air valves in a gas automatic sampling apparatus from a closed circulation system, and these are remotely controlled by a program controller. It was found that the automatic operation enables continuous automatic sampling and improves the durability of the apparatus itself.
That is, the present invention
(1) A closed circulatory system, a sampling loop connected to the closed circulatory system via a valve and connected to an exhaust device partitioned by the valve, and connected to the sampling loop via a valve A gas comprising: a carrier gas line, wherein a plurality of valves are combined to control opening and closing of the valves, thereby introducing a carrier gas into the sampling loop and collecting a sample gas in a closed circulation system Automatic sampling device,
(2) A buffer section partitioned by a valve is further provided between the closed circulatory system and the sampling loop to minimize the pressure change in the closed circulatory system when the sample gas is introduced from the closed circulatory system into the sampling loop. (1) The gas automatic sampling device according to (1),
(3) The gas automatic sampling device according to (1) or (2), wherein the sampling loop side is set to a lower pressure than the closed circulation system when the sample gas is introduced from the closed circulation system into the sampling loop.
(4) The gas automatic sampling device according to any one of (1) to (3), wherein the valve opening / closing is centrally controlled by program control, and
(5) A plurality of units of the automatic gas sampling device described in the above (1) or (2) are combined, and the opening and closing of the valve is programmed and controlled to continuously and automatically supply the sample gas in the plurality of closed circulation systems. Automatic gas sampling device characterized by enabling accurate gas analysis,
Is to provide.

The automatic gas sampling device of the present invention has the following effects.
Qualitative analysis / quantitative analysis of gas in a closed circulation system can be easily automated by introducing a sample gas and a carrier gas and switching gas flow paths using a plurality of controlled valves. .
By using a highly durable electromagnetic valve and compressed air valve without using a hexagonal cock, the durability of the gas sampling device can be dramatically improved and long-term continuous automatic sampling is possible. . In addition, by selecting an optimal valve, sampling can be performed regardless of whether the closed circulation system is in a pressurized state or a reduced pressure state.
Furthermore, when combined with an exhaust device that uses a vacuum pump, the sampling loop can be evacuated in advance, so that the specimen gas diffusion time into the sampling loop can be greatly reduced, and during sampling. The backflow of the carrier gas into the closed circulation system can be prevented.

In addition, the opening and closing of each valve can be collectively controlled by program control, and the opening and closing time can be set to an optimum value according to the sample gas used, the type of the closed circulation system, and the like.
Then, the gas automatic sampling device is made into one unit, and by connecting and controlling a plurality of units, the analysis of the sample gas in the plurality of closed circulation systems can be automatically and continuously performed using one gas chromatograph. Is possible.

Embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a diagram for schematically showing the configuration of an automatic gas sampling apparatus according to the present invention. A sampling loop 3 is connected to a closed circulation system 1 via a buffer unit 4. The closed circulation system 1 and the buffer unit 4 are separated by a valve V1, the buffer unit 4 and the sampling loop 3 are separated by a valve V2, and the sampling loop 3 is connected to a vacuum pump by the valve V3. (Not shown).
A carrier gas line 5 through which the carrier gas 6 flows to the gas chromatograph exists in parallel with the sampling loop 3. Then, by opening and closing valves V4 and V5 provided in the sampling loop 3 and valves V6 and V7 provided in the carrier gas line 5, the flow path of the carrier gas is changed to the carrier gas line 5 side and the sampling loop 3 side. Can be switched.

  After the sample gas is introduced from the closed circulation system into the sampling loop by the combination of opening and closing of the valve, the carrier gas in the carrier gas line is introduced into the sampling loop, and the sample gas is merged with the carrier gas. Sample gas is collected by connecting to a carrier gas line connected to a gas chromatograph, and qualitative analysis / quantitative analysis of gas components is performed.

Hereinafter, the sampling procedure will be described with reference to the flowchart shown in FIG.
The valve is set to the initial position (step 1). This initial position is a state in which the valves V1, V4, V5 are closed and the valves V6, V7 are open, and the closed circulation system 1, the buffer unit 4, the sampling loop 3, and the carrier gas line 5 are partitioned. .
Here, as shown in FIG. 1, the valves V2 and V3 are opened and sucked by a working vacuum pump (not shown) (step 2), and the inside of the buffer unit 4 and the sampling loop 3 is evacuated by the vacuum pump. The carrier gas 6 flows through the carrier gas line 5 to a gas chromatograph (not shown).

  Next, as shown in FIG. 2, the sample gas 2 is introduced from the closed circulation system 1 to the buffer unit 4 by closing the valve V2 and opening the valve V1 (step 3). The buffer unit 4 is in a vacuum state in advance, and the gas introduction time of the specimen gas 2 can be extremely short. Here, it is preferable to reduce the volume of the buffer unit 4 in order to minimize the pressure / composition change of the specimen gas 2 in the closed circulation system 1. However, when there is no need to consider the pressure / composition change of the specimen gas 2 in the closed circulation system 1, the buffer unit 4 and the valve V2 can be omitted, and a simpler structure can be obtained.

Next, as shown in FIG. 3, the valves V1 and V3 are closed, the pump suction is stopped, and the valve V2 is opened to diffuse the sample gas 2 from the buffer unit 4 to the sampling loop 3 (step 4). Also in this case, since the inside of the sampling loop 3 is previously evacuated, the diffusion time of the specimen gas 2 from the buffer unit 4 proceeds in a considerably short time. The volume ratio between the buffer unit 4 and the sampling loop 3 is desirably set according to the sensitivity of the target sample gas in the gas chromatograph.
Even when the buffer unit 4 is omitted, the sampling loop 3 is connected to a vacuum pump via the valve V3 and is evacuated before sampling, so that the sample gas is diffused from the closed circulation system to the sampling loop. The time can be greatly shortened, and the carrier gas can be prevented from flowing into the closed circulation system.

Finally, as shown in FIG. 4, by closing the valves V2, V6, V7 and opening the valves V4, V5, the flow of the carrier gas 6 is switched from the carrier gas line 5 to the sampling loop 3, and the sampling loop The carrier gas 6 is introduced into the sample gas in 3 and merged to flow into a gas chromatograph (not shown) (step 5).
After the analysis by the gas chromatograph is completed, the valves V4 and V5 are closed and the valves V6 and V7 are opened (step 6) to return to the initial state.
In this way, sampling can be performed continuously.

Next, an automatic gas sampling apparatus in which the sampling apparatus as described above is one unit and a plurality of units are combined will be described.
Each of the plurality of units is set as a unit A and a unit B, and the flowchart shown in FIG. 5 is set as a sampling control A for the unit A and a sampling control B for the unit B. When a series of sampling procedures for one unit (flowchart FIG. 5) is completed, it is preferable to control another unit by the same sampling procedure. These can be performed, for example, by setting alternating sampling with ABABAB or various combinations such as AABAAB and AABBAABB.
Further, when it is desired to set the sampling interval to a short time, the sampling control A and the sampling control B can be performed in parallel. For example, as illustrated in FIG. 6, one step when the control is performed in parallel is shown. When unit A is sampling the sample gas (corresponding to FIG. 4 described above), unit B diffuses the sample gas ( (Corresponding to FIG. 3) can be controlled to be performed simultaneously.

The automatic gas sampling device of the present invention can arbitrarily set the sampling time and amount (specimen gas diffusion time, etc.), the sampling interval (how many times the sampling is repeated), etc., according to the type of closed circulation system. Yes, many control patterns of sampling are possible even in the case of a single unit.
Further, in order to combine a plurality of units of the automatic gas sampling device, for example, as shown in FIG. 6, the units can be combined in series, or the carrier gas lines 5 can be connected in parallel, and the units can be combined in parallel. . For a plurality of units, various sampling control patterns can be made for each specimen as described above, such as sampling time / amount, sampling interval, and mutual control interval. Therefore, qualitative / quantitative analysis of a desired sample can be performed very accurately by optimal sampling.

  The closed circulation system which is the object of gas sampling of the present invention is a system comprising a reaction part for performing a catalytic reaction (including a photocatalyst) and a circulation part having a constant volume for circulating the reactant and product. is there. This closed circulatory system has the advantages of both the so-called badge type and flow type reaction systems. The reaction gas is repeatedly passed through the reaction section, and the qualitative and quantitative determination of the gas components generated in the circulation section is performed at regular intervals. Analyzing makes it easy to study the speed and mechanism of the reaction and is a powerful tool for the development of catalytic reactions. As a specific example, (a) a reaction part in which a semiconductor photocatalyst such as titanium oxide is suspended in an aqueous solution containing a reaction product is irradiated with light, and a gas component generated therefrom is diffused into the circulation part, and is periodically Suspension photocatalytic reaction for qualitative and quantitative determination of gas components, or (b) Various oxides and metal catalysts are heated in the reaction section, and nitrogen oxide (NOx) and other gases are repeated in the circulation section and reaction section. By circulating, there is a catalytic reaction that observes the decomposition process of nitrogen oxide gas components.

  The sampling apparatus according to the present invention uses a valve, and can satisfactorily sample gas even when the inside of the closed circulation system is in a pressurized state or a reduced pressure state as well as a normal pressure. And, by using a diaphragm type, solenoid type, etc., it is possible to minimize wear during driving, and the durability is dramatically improved compared to the conventional 6-way cock type. .

Opening and closing of each valve is controlled from the controller by an electric signal or compressed air. The timing of opening and closing can be freely changed by a program, and an optimum sampling process can be set in accordance with the characteristics of the sample gas and the closed circulation system to be used.
When the sample gas is ignitable or flammable, it is preferable to avoid the risk of explosion by controlling the opening and closing of the valve with compressed air.
The material for the introduction line from the closed circulation system, the carrier gas line, the sampling loop, and the valve can be selected from Teflon (registered trademark), stainless steel, glass and the like according to the sample gas.

It is the schematic of the gas automatic sampling apparatus of this invention. It is a figure which shows the state of the sample gas introduction | transduction to the buffer part of the gas automatic sampling device of this invention. It is a figure which shows the spreading | diffusion state of the sample gas to the sampling loop of the gas automatic sampling device of this invention. It is a figure which shows the sampling state by switching of the carrier gas flow path of the automatic gas sampling device of this invention. It is an example of the control flowchart of gas automatic sampling of the present invention. It is the schematic of an example which combined multiple units of the gas automatic sampling device of this invention.

Explanation of symbols

1 Closed circulation system 2 Sample gas
3 Sampling loop
4 Buffer section 5 Carrier gas line 6 Carrier gas V1, V2, V3, V4, V5, V6, V7 Valve

Claims (5)

  A closed circulatory system, a sampling loop connected to the closed circulatory system via a valve and connected to an exhaust device partitioned by the valve, and a carrier gas line connected to the sampling loop via the valve A gas automatic sampling apparatus for collecting a sample gas in a closed circulation system by introducing a carrier gas into the sampling loop by combining the plurality of valves and controlling the opening and closing of the valves .   A buffer section partitioned by a valve is further provided between the closed circulatory system and the sampling loop to minimize pressure changes in the closed circulatory system when the sample gas is introduced from the closed circulatory system into the sampling loop. The automatic gas sampling apparatus according to claim 1, wherein:   3. The automatic gas sampling apparatus according to claim 1, wherein, when the sample gas is introduced from the closed circulatory system into the sampling loop, the sampling loop side has a lower pressure than the closed circulatory system.   4. The automatic gas sampling apparatus according to claim 1, wherein opening and closing of the valve is centrally controlled by program control. Combining a plurality of units of the automatic gas sampling device according to claim 1 or 2 and controlling the opening and closing of the valve by program control enables continuous and automatic gas analysis of the sample gas in a plurality of closed circulation systems. An automatic gas sampling device characterized by that.

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