JPH11211630A - Gas sample collecting device and its use method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the concentration of a constituent from decreasing, and to improve the reliability and accuracy in an analysis by intentionally adsorbing or absorbing the gas sample constituent from a large-volume supply source (large gas bag) for a capturing container (compact gas bag) and a channel. SOLUTION: A lid 10 for sampling a gas sample is opened, and a compact gas bag 2 with an empty valve is arranged in a vacuum chamber 3, the port of the gas bag 2 is connected to a connector 11 with a valve at the termination part of a pipe A, and then a valve is opened. A pipe E is connected to a large gas bag 1 and the valve is opened. The valve position of a three-way solenoid valve 5 is controlled so that a sample gas in the gas bag 1 flows toward the gas bag 2 with a valve in the chamber 3 through the pipe A. A pressure sensor 12 senses a negative pressure in an exhaust system when air in the chamber 3 is evacuated and the pressure is reduced and can be used with timer control so that a compact gas bag with a valve where the sample gas is being introduced cannot be burst. Therefore, the sample gas can be taken in portion from the bag 1 to the bag 2 through a portion-taking operation and is supplied for analysis.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for collecting a gas sample for an analysis test and a method of using the same, and more particularly to a gas sample once collected in a large gas bag for an analysis test of engine exhaust gas. The present invention relates to a gas sample collection device used for collecting a sample into a small gas bag to supply the sample to an analytical test instrument, and a method of using the same.

[0002]

2. Description of the Related Art Testing of an engine, for example, a diesel engine is performed, for example, in a 13-mode operation pattern in a cycle of 50 minutes. In this case, the composition analysis of exhaust gas is one of important inspection items. Substances to be analyzed are trace components such as benzene, 1,3-butadiene, and other hydrocarbon compounds that exist in the order of ppb (parts per billion) in exhaust gas samples. There are many. In an engine test, an exhaust gas sample is generally supplied to a large plastic bag (for example, having an internal volume of about 100 l to several hundred l) through a dilution tunnel device attached for sampling the exhaust gas at an appropriate position in the exhaust pipe. Once collected and stored in a small gas bag (e.g., about 10 l or less in internal volume) from the large gas bag for supply to analytical test equipment (e.g., a gas chromatograph). You. Plastic materials for producing these gas bags are usually polyolefin-based polymers and copolymers such as polyethylene and polypropylene.

An important thing to note in such a sample collection operation in chemical analysis of exhaust gas is the collection of a trace amount of a component, so that the target component is adsorbed on the inner surface of a collection container (for example, a small gas bag). Concentration reduction has a significant effect on analytical accuracy and reliability. Alternatively, if a small gas bag is filled with a sample and released, the concentration of the trace components in the sample tends to gradually decrease and fluctuate. Is the adsorption and absorption of trace components. The tendency of the concentration of the trace components in a large gas bag to fluctuate is extremely small as compared with a small gas bag made of the same material, and can be ignored in most cases. That is, in the case of a large gas bag made of plastic for sampling exhaust gas that is currently in practical use, the ratio between the volume of the contained gas and the surface area of the bag is relatively large, so even if trace components are adsorbed and absorbed on the inner surface. Even so, the rate of change in the concentration of the trace component is negligibly small. On the other hand, in the case of small gas bags made of plastic for sample collection, the ratio of the volume of the contained gas to the surface area of the bag becomes relatively small, and the chance of the trace component molecules colliding with the bag inner surface also increases, so that adsorption, It is considered that the rate of change in the concentration of the trace component due to absorption is large.

Another important matter regarding exhaust gas sampling in an engine test is that, as described above, since the engine test is performed according to a mode cycle for a certain period of time, an exhaust gas sample that accurately represents the mode in each mode is required. It must be collected without delay and supplied to analytical test equipment.

[0005] Therefore, as a means for reducing the change in the concentration of the trace components of the sample gas in the small gas bag due to the adsorption and absorption of the trace components to be analyzed on the inner surface of the small gas bag, the sample is collected from the large gas bag. After allowing the trace components to be adsorbed or absorbed on the inner surface of the small gas bag containing the exhaust gas sample, the inside surface is once saturated with the trace components or brought into a nearly stabilized state, and then the gas is removed from the small gas bag. When the fresh exhaust gas sample from the large gas bag is again introduced into the small gas bag, the inner surface is no longer saturated with the trace components or in a stabilized state close to it, so the small gas Little or no change in the concentration of the trace components in the bag occurs, and accurate analysis can be performed. Such operations as “introduction of sample gas into a small gas bag” → “saturation or stabilization by adsorption and absorption of the analysis target component to the inner surface” → “gas discharge” may be repeated as necessary. Should be returned. However, the introduction and filling of a sample gas into a small gas bag and the discharge of the sample gas from the bag are often difficult due to the flexibility of the material of the gas bag, and especially the discharge of the sample gas from the gas bag is significant. Without some external assistance, such as creating a significant pressure differential, it is extremely difficult to achieve rapid and complete discharge. Therefore, samples are quickly collected in small gas bags in synchronization with the mode cycle of the engine test, and the “saturation (stabilization)” process described above is performed. Providing ready equipment means is convenient and useful for the analysis of exhaust gases, especially those associated with engine tests.

[0006]

SUMMARY OF THE INVENTION The present invention is intended to prevent a change in the concentration of a trace component to be analyzed in a sample gas such as an exhaust gas of an engine (for example, a decrease in concentration due to adsorption, absorption, etc.)
It is a main object of the present invention to provide a gas sample collection device that quickly supplies an accurate representative sample to an analytical test instrument. It is another object of the present invention to improve the accuracy and reliability of analysis by using such a device. The present invention can also improve the accuracy and reliability of analysis by flushing a pipe system connecting a large gas bag containing a sample and a small gas bag for sample collection simultaneously with the small gas bag, and then collecting the sample in the small gas bag. The purpose is.

[0007]

SUMMARY OF THE INVENTION Accordingly, in order to achieve the above-mentioned object, the present invention provides a gas sample trap for collecting a gas sample collected in a large gas bag into a small gas bag for supplying to an analytical test instrument. (B) a vacuum chamber for accommodating a small gas bag, (b) a pipe connected to a large gas bag outside the device; a three-way solenoid valve; and a terminal end projecting into the vacuum chamber. And a gas sample introduction system which connects each element of the pipe for connecting the small gas bag to the terminal end thereof. (C) The small gas of (b) for discharging the gas sample in the small gas bag. Bag connection pipe; (b)
A three-way solenoid valve; another three-way solenoid valve; an exhaust pump; a gas sample discharge system connecting the respective elements; (d) a solenoid valve for shutting off the vacuum chamber from the atmosphere and opening it to the atmosphere;
(E) an exhaust system in which the vacuum chamber is connected to the exhaust pump through another three-way solenoid valve described in (c) for decompression of the vacuum chamber, and (e) a timer for controlling the opening / closing of each solenoid valve and the operation time of the exhaust pump. A pressure sensor for detecting the degree of vacuum in the gas sample discharge system; a pressure sensor for detecting the degree of vacuum in the vacuum chamber; and a control system comprising: a gas sensor.

As a specific preferred embodiment of the present invention, a gas sample to be collected in a small gas bag with a valve (2) for supplying a gas sample collected in a large gas bag (1) to an analytical test instrument is provided. A collecting device comprising: (a) a vacuum chamber (3) for accommodating a small gas bag (2) with a valve; (b) a pipe with a valve and a connector connected to a large gas bag (1) outside the device. (E); a three-way solenoid valve (5); and a pipe (A) provided with a connector (11) for projecting a terminal portion into the vacuum chamber and connecting a small gas bag with a valve to the terminal portion. Gas sample introduction system connecting elements, (c)
The pipe (A); the three-way solenoid valve (5); the pipe (B); the three-way solenoid valve (6); an exhaust pump with an inlet-side pipe (4) for discharging a gas sample in a small gas bag with a valve. And a gas sample discharge system connecting the elements of the exhaust pipe (D); (d) shutting off and opening the atmosphere which causes the main operation of gas sample introduction and discharge in a small gas bag with a valve in a vacuum chamber. Each element of a pipe with a solenoid valve (7); an exhaust pipe (C) for depressurizing a vacuum chamber; the three-way solenoid valve (6); an exhaust pump (4) with an inlet pipe; and an exhaust pipe (D). (E) a pressure sensor (8) attached to the pipe (B) for detecting the degree of vacuum of exhaust gas; a vacuum chamber (3) attached to the exhaust pipe (C)
A pressure sensor (12) for detecting the pressure of the air; a control system comprising a timer (9) for controlling the opening and closing of the solenoid valves (5), (6) and (7) and the operation time of the exhaust pump (4); Wherein the gas sample collecting device is provided.

The schematic structure of an example of the device of the present invention is shown in FIG. The device of this example has a single vacuum chamber (3) and is made of transparent plastic for internal observation (eg:
Acrylic) lid (10). For gas sample collection, the lid (10) is opened, an empty small gas bag with a valve (2) is placed in a vacuum chamber (3), and the mouth of the small gas bag with a valve is connected to a pipe ( Connect to the valved connectors (11) at the end of A) and open those valves. However, those valves can be omitted as appropriate. The pipe (E) is connected to the large gas bag (1) containing the already collected gas sample outside the apparatus. Next, the valve of the pipe (E) is opened. The valve position of the three-way solenoid valve (5) is controlled so that the sample gas in the large gas bag (1) flows through the pipe (A) toward the small gas bag with valve (2) in the vacuum chamber (3). I do.
Since the air pressure in the large gas bag (1) is almost atmospheric pressure, the electromagnetic valve (7) of the vacuum chamber (3) is set to promote the flow of the gas sample into the small gas bag with valve (2). As a closed state, the air in the vacuum chamber (3) is exhausted to the atmosphere by an exhaust pump (4) with an inlet pipe through a pipe (C) and a three-way solenoid valve (6),
This reduces the pressure inside the chamber (3). This operation is performed by driving the pump (4) with the inlet side pipe for a predetermined time under the control of the timer (9) or the pressure sensor (12) attached to the pipe (C). ) Is filled or nearly full. The pressure sensor (12) evacuates the air in the vacuum chamber (3), senses a negative pressure in the exhaust system when the pressure is reduced, and prevents the small gas bag with a valve into which the gas sample is being introduced from bursting. When the intensity of the sensed negative pressure becomes too large, the control for stopping the decompression of the vacuum chamber is performed, and can be used together with the timer control. At this stage, components in the gas sample, particularly trace components having a low absolute concentration, are absorbed or absorbed by the inner wall of the pipes or the inner surface of the small gas bag, causing a large concentration fluctuation (decrease). Gas samples in small valved gas bags are not suitable for analysis or other testing.

Therefore, it is appropriate to discharge the gas sample first collected in the small gas bag with a valve as described above. The discharge of the gas sample from the small gas bag with a valve is performed by opening the solenoid valve (7) provided on the wall of the chamber (3) under the control of the timer (9), and allowing the air to flow into the chamber. Return the reduced pressure to atmospheric pressure, and at the same time, two three-way solenoid valves (5) and (6)
Is switched so that the small gas bag with valve (2) communicates with the exhaust pump with inlet pipe (4) via the pipes (A) and (B), and drives the exhaust pump (4), The gas that has been sorted and held in the small gas bag with valve (2) is removed from the system by a pipe (D) until a vacuum sensor (8), for example, a pressure switch detects a predetermined degree of vacuum.

Normally, after the above-described gas sample collection and discharge operations, the ability of the inner surface of the small gas bag with a valve to adsorb or absorb the components to be analyzed is greatly reduced. If a gas sample is collected again from a large gas bag into a small gas bag with gas, for example, the analysis accuracy by gas chromatography is significantly adversely affected.
Little or no change (decrease) in the component concentration in the gas sample is observed. Therefore, the gas sample can be collected again from the large gas bag (1) to the small gas bag with valve (2) by the above-described sorting operation, and can be used for analysis or other tests. However, when particularly desired or required (for example, when the concentration of a specific component further varies), the above-described separation and discharge operations are further repeated one or more times to provide a small gas with a valve. After sufficient stabilization of the inside surface of the bag, sample collection for analytical testing may be performed.

Thus, the present invention relates to a method for collecting a gas sample using the gas sample collecting apparatus of the present invention, comprising the steps of: (a) placing a small gas bag (2) with an empty valve in a vacuum chamber (3); ), The mouth of the small gas bag with a valve is connected to the connector (11) at the end of the pipe (A) and the valve is opened; (b) a large gas bag containing a gas sample outside the device ( A pipe (E) is connected to 1), and a three-way solenoid valve (5) and a three-way electromagnetic valve are formed so as to form a gas sample introduction system flow path toward the small gas bag with valve (2) via the pipe (A). Valve (5)
(C) operating the solenoid valve (7) so as to isolate the vacuum chamber (3) from the atmosphere; (d) exhaust pipe (C) and a three-way solenoid valve (6) from the vacuum chamber (3). (3) operating the three-way solenoid valve (6) so as to form an exhaust gas passage toward the exhaust pump (4) with the inlet side pipe via the above (e) operating the exhaust pump (4) with the inlet side pipe to vacuum The air in the chamber (3) is exhausted through the exhaust pipe (D) to create a reduced pressure in the vacuum chamber (3), and the reduced pressure acts to form the large gas bag (1) from the above (b). The gas sample is introduced into the small gas bag with valve (2) through the flow path of the gas sample introduction system by a timer (9) or a pressure sensor (12) for an appropriate period of time, and the small gas bag with valve (2) is used as a gas sample. Charge Then, the gas introduction is stopped by operating the three-way solenoid valve (5); Leaving the small gas bag with gas introduction valve (2) for a period of time until the absorption or adsorption to the inside surface of the bag (2) decreases and the inside surface of the valve (2) is sufficiently stabilized; G) Thereafter, the solenoid valve (7) of the vacuum chamber (3) is opened to open the vacuum chamber (3) to the atmosphere, and the three-way solenoid valve (5) and the three-way solenoid valve (6) are operated. Exhaust pump with pipe on inlet side from small gas bag with valve (2) via pipe (A), three-way solenoid valve (5), pipe (B) and three-way solenoid valve (6)
And a gas sample discharge system flow path is formed, and an exhaust pump (4) with an inlet side pipe is operated to discharge a gas sample from a small gas bag (2) with a valve from an exhaust pipe (D); If necessary, repeat the above operations (b) to (g) for stabilizing the inside surface of the small gas bag; (ii) Perform the above operations (b) to (e) for the small gas bag with valve (2) whose inside surface has been stabilized. (V) The vacuum chamber (3) in a reduced pressure state is opened to the atmosphere by a solenoid valve (7), and the valve of the small gas bag (2) with a valve containing the gas sample is closed. And removing from the pipe (A) and removing from the vacuum chamber (3).

FIG. 2 shows the flow of the sampled gas sample and the flow of the exhaust gas from the vacuum chamber at the time of the gas sample collection operation of the gas sample collection device of FIG. The flow of the exhaust gas sample and the flow of the atmosphere to the vacuum chamber are indicated by thick broken arrows. In any case, a pressure difference occurs between the inside and outside of the small gas bag in the vacuum chamber, and the inflow and discharge of gas are promoted.

Although the gas collecting apparatus according to the present invention having a single vacuum chamber has been described with reference to FIGS. 1 and 2, the apparatus according to the present invention has two or more vacuum chambers. Can be configured so that gas sample collection can be performed efficiently. An example is shown in the flowchart of FIG. 3 (the timer control system is omitted in this figure for simplicity). The device of FIG. 3 is slightly different in design from the device of FIG. 1 in the number of three-way solenoid valves and the control system lines and piping associated with the addition of the vacuum chamber, The basic configuration is the same. In FIG. 4, in the apparatus of FIG. 3, the flow of the sample gas sample and the flow of the exhaust gas from the chamber when the gas sample is collected into the small gas bag 1 are indicated by thick solid arrows, and the discharge during the discharge operation is performed. The flow of the gas sample and the flow of the atmosphere to the chamber are indicated by thick broken arrows. With this disclosure, FIG.
In the apparatus described above, a gas sample is collected in the small gas bag 2,
The flow of the gas sample and the flow of the atmosphere when discharging it,
It will be apparent to those skilled in the art. Those skilled in the art will also readily understand design changes and operation methods when the number of vacuum chambers is further increased.

When a device having a plurality of vacuum chambers connected in series is used, even when a sample of exhaust gas is frequently collected in a large gas bag as in a multi-mode engine test, the plurality of vacuum chambers are switched and used. By doing so, the gas sample can be collected in a small gas bag without delay for a limited time, and the gas sample can be sequentially supplied to the analytical test equipment.

As described above, according to the apparatus of the present invention, the components of the gas sample from the large-volume supply source (large gas bag) are intentionally (or are) supplied to the collection container (small gas bag) and the flow path. Aggressive) Adsorption or absorption to prevent further concentration reduction of components
The basic operation of fractionation and the repetitive operation as required can be automatically and quickly performed, and the reliability and accuracy of analysis can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view of an example of a gas collecting device according to the present invention.

FIG. 2 is a longitudinal sectional view of FIG. 1 in which gas flows during operation are shown.

FIG. 3 is a flow sheet of the continuous gas collecting apparatus according to the present invention.

FIG. 4 is a flow sheet of FIG. 3 in which gas flows during operation are entered.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Large gas bag 2 Small gas bag 3 Vacuum chamber 4 Pump (exhaust) 5, 6 Three-way solenoid valve 7 Solenoid valve 8 Vacuum sensor 9 Timer control device 10 Lid (transparent acrylic plate) 11 Connector 12 Pressure sensor A, B, C , D, E pipe

Claims (4)

[Claims] 1. A gas sample collection device for collecting a gas sample collected in a large gas bag into a small gas bag for supplying to an analytical test device, comprising: (a) for accommodating a small gas bag; (B) a pipe connected to a large gas bag outside the device;
(C) a small gas bag that connects each element of a three-way solenoid valve; and a pipe for projecting an end into the vacuum chamber and connecting the small gas bag to the end. A gas sample discharge system connecting the small gas bag connection pipe of (b) to discharge the gas sample in the above; the three-way solenoid valve of (b); another three-way solenoid valve; an exhaust pump; (D) a solenoid valve for shutting off the vacuum chamber from the atmosphere and opening it to the atmosphere; and connecting the vacuum chamber to the exhaust pump via another three-way solenoid valve of (c) for depressurizing the vacuum chamber. (E) a timer for controlling the opening and closing of each solenoid valve and the operation time of the exhaust pump; or a pressure sensor for detecting the degree of vacuum in the gas sample discharge system; a pressure sensor for detecting the degree of vacuum in the vacuum chamber; Ranaru control system, the gas sample collector which comprises a. (A) a vacuum chamber (3) for accommodating a small gas bag (2) with a valve; (b) a valve and a pipe (E) connected to a large gas bag (1) outside the apparatus. ); Three-way solenoid valve (5);
And a pipe (A) provided with a connector with a valve (11) for projecting a terminal portion into the vacuum chamber and connecting a small gas bag with a valve to the terminal portion. (C) The pipe (A); the three-way solenoid valve (5); the pipe (B); the three-way solenoid valve (6); an exhaust pump with an inlet-side pipe for discharging a gas sample in a small gas bag with a valve. (4); and a gas sample discharge system connecting the respective elements of an exhaust pipe (D); (d) air shut-off and main operation for introducing and discharging a gas sample in a small gas bag with a valve in a vacuum chamber. A pipe with an electromagnetic valve (7) for opening; an exhaust pipe (C) for depressurizing a vacuum chamber; the three-way electromagnetic valve (6); an exhaust pump (4) with an inlet-side pipe; and the exhaust pipe (D); Consists of the following elements (E) a pressure sensor (8) attached to the pipe (B) for detecting the degree of vacuum of the exhaust gas; a pressure attached to the exhaust pipe (C) for detecting the pressure of the vacuum chamber (3) A sensor (12); the solenoid valve (5),
2. The gas sample collecting apparatus according to claim 1, further comprising a control system including a timer (9) for controlling opening / closing of (6) and (7) and operating time of the exhaust pump (4). 3. The gas sample collecting apparatus according to claim 1, wherein a plurality of vacuum chambers are connected in series, and a three-way solenoid valve for switching the vacuum chambers is added. 4. A method for collecting a gas sample using the gas sample collection device according to claim 2, wherein (a) a small gas bag (2) with an empty valve is placed in a vacuum chamber (3). (B) opening the valve of the pipe (A) and the small gas bag (2) by connecting the mouth of the small gas bag with the valve to the connector (11) with the valve at the end of the pipe (A); A pipe (E) is connected to a large gas bag (1) containing a gas sample outside the apparatus, and a gas sample introduction system is directed to a small gas bag (2) with a valve via a three-way solenoid valve (5) and a pipe (A). Three-way solenoid valve to form a flow path (5)
(C) operating the solenoid valve (7) so as to isolate the vacuum chamber (3) from the atmosphere; (d) exhaust pipe (C) and a three-way solenoid valve (6) from the vacuum chamber (3). (3) operating the three-way solenoid valve (6) so as to form an exhaust gas passage toward the exhaust pump (4) with the inlet side pipe via the above (e) operating the exhaust pump (4) with the inlet side pipe to vacuum The air in the chamber (3) is exhausted through the exhaust pipe (D) to create a reduced pressure in the vacuum chamber (3), and the reduced pressure acts to form the large gas bag (1) from the above (b). The gas sample is introduced into the small gas bag with valve (2) through the flow path of the gas sample introduction system by the pressure sensor (12) or the timer (9) for an appropriate time, and the small gas bag with valve (2) is converted into the gas sample. Charge Thereafter, the gas introduction is stopped by operating the three-way solenoid valve (5); (f) The introduced gas sample is brought into contact with the inner surface of the small gas bag with valve (2), and the small gas with the valve of the components in the gas sample is removed. Leaving the small gas bag with gas introduction valve (2) for a period of time until the absorption or adsorption to the inside surface of the bag (2) decreases and the inside surface of the valve (2) is sufficiently stabilized; G) Thereafter, the solenoid valve (7) of the vacuum chamber (3) is opened to open the vacuum chamber (3) to the atmosphere, and the three-way solenoid valve (5) and the three-way solenoid valve (6) are operated. Exhaust pump with pipe on inlet side from small gas bag with valve (2) via pipe (A), three-way solenoid valve (5), pipe (B) and three-way solenoid valve (6)
And a gas sample discharge system flow path is formed, and an exhaust pump (4) with an inlet side pipe is operated to discharge a gas sample from a small gas bag (2) with a valve from an exhaust pipe (D); If necessary, repeat the above operations (b) to (g) for stabilizing the inner surface of the small gas bag with a valve; (E) The sample gas is collected by repeating (e). (V) The vacuum chamber (3) under reduced pressure is opened to the atmosphere by the solenoid valve (7), and the valve of the small gas bag (2) with a valve containing the gas sample is opened. The gas sample is collected from the pipe (A) and taken out of the vacuum chamber (3).