JP2006177775A - Sampling device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sampling device, constituted so as to remove the effect caused by fluctuations in the concentration of the coexisting component in a sample, using a relatively simple constitution to enhance the measurement accuracy of the target component. <P>SOLUTION: The sampling device is equipped with first and second collection bags B1 and B2, which are housed in the liquid 21 charged in a hermetically closed container 22 and changed in the volume by the flow-in and out of the sample A, a solenoid valve V2a for alternately collecting the sample A in the collection bags B1 and B2 and a solenoid valve V2b, for alternately introducing the sample A collected in the collection bags B1 and B2 into the inflow side of the solenoid valve V1 of a difference quantity-method analyzer 10. The changeover cycles of the solenoid valves V2a and V2b are set the same and are set to 2n (n: natural number) times the changeover cycle of the solenoid valve V1. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a sampling device that is provided in a previous stage of a differential method analyzer and samples a sample.

As is well known, the differential method is an effective measurement method when there is no highly selective analysis method for quantifying a target component, and is classified into two measurement methods. One is a value obtained by subtracting the measurement result of sample B from the measurement result of sample A when sample A contains a target component and a coexisting component (interfering component), and sample B is removed. Is a method of measuring the concentration of the target component.
The other is the conversion of the target component of sample A into another component to generate sample B. The value obtained by subtracting the measurement result of sample A from the measurement result of another component of sample B is the concentration of the target component. It is a measuring method.
As an analyzer using such a difference method, for example, an ozone meter by an ultraviolet absorption method is known as the former measuring method, and as a latter measuring method, catalytic oxidation NDIR (non-dispersed infrared) VOC meters (volatile organic compound analyzers) based on analytical methods, nitrogen dioxide measuring devices based on chemiluminescence, and the like are known.

FIG. 4 is a schematic configuration diagram of a differential method analyzer having a single analysis unit.
4 is an electromagnetic valve (three-way valve) 110 serving as an analyzer switching valve to which a sample A is supplied, and a target component is removed from the sample A or the target component is changed to another component. Instead, the converter 120 for generating the sample B, the sample A directly supplied from the electromagnetic valve 110 via the sampling line 125A, and the sample B supplied from the converter 120 via the sampling line 125B are introduced. A single analyzer 130 for measuring each concentration, and the analyzer 130 alternately measures the concentrations of the sample A and the sample B by switching the electromagnetic valve 110.
FIG. 5 exemplifies the action of the converter 120 according to the type of the difference method analyzer 100 and the measurement substance of the analysis unit 130 as an example of the difference method.

In the difference method analyzer 100 described above, it is premised that the concentrations of the target components and the coexisting components contained in the samples A and B are equal, but the concentrations of the samples A and B are set to a single analyzer 100. As a result of alternately measuring with the analysis cell, there is a problem that an accurate measured value cannot be obtained when the concentration of the target component or coexisting component contained in the original sample A fluctuates before and after switching.
Further, depending on the substance to be measured, the concentration of sample B is higher than the concentration of sample A, and the measured value may be indicated as a negative value.

  These problems can be solved once if analysis units 140 and 150 are provided for samples A and B, respectively, and are simultaneously measured by individual analysis cells, such as a differential method analyzer 100 'shown in FIG. However, since the analysis cells of both the analysis units 140 and 150 are not evenly soiled and the sensitivity is changed, the cell balance is easily lost, and so-called ghost instructions appear. Need to be done frequently. Since these operations are troublesome, the differential method analyzer having the structure shown in FIG. 6 is not so popular. In this case, since two analysis units are required, the cost increases accordingly.

  Similar to FIG. 4, a differential analysis apparatus including a single analysis unit is described in Patent Document 1 described later. In this analyzer, in order to prevent the difference signal from becoming inaccurate due to a shift in signal processing timing of the first and second signal processing circuits input to the differential amplifier circuit of the analysis unit, On the upstream side of the processing circuit, a switch that is turned on and off at the same cycle as the open / close valve for sample introduction is provided.

  In addition, although it is not a prior art related to a differential method analyzer, a plurality of solenoid valves and two sampling containers arranged in a sampling line are provided for the purpose of saving labor in analyzing gas accompanied by a change in component concentration over time. The operation of moving the water filled in one sampling container to the other sampling container is interlocked with the switching of the electromagnetic valve, so that the gas sampling operation by one sampling container and the analyzer by the other sampling container are transferred to the analyzer. A gas sampling method for analysis that simultaneously performs the gas supply operation is described in Patent Document 2 below.

Japanese Patent Laid-Open No. 10-274639 (paragraphs [0009] to [0012], FIG. 1, FIG. 2, etc.) JP-A-57-88341 (first page, lower right column, line 13 to page 2, lower left column, line 10)

In the prior art shown in FIG. 4, in order to reduce the influence of fluctuations in the concentration of coexisting components in the sample A as much as possible, a buffer is provided in the sampling line, or errors due to fluctuations in density are reduced by arithmetic processing. Possible countermeasures.
However, it is difficult for a measurement system having a greater concentration fluctuation to cope with these methods alone, and it is insufficient to eliminate measurement errors.

The prior art described in Patent Document 1 is intended to eliminate delays in electrical signal processing, and does not take into account variations in the concentration of target components and coexisting components.
Furthermore, the conventional technique described in Patent Document 2 requires a large number of solenoid valves, water pumps, and the like, and there is a problem in that they cause a complicated structure and an increase in cost.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a sampling apparatus that improves the measurement accuracy of a target component by removing the influence of the concentration of the target component and coexisting component in the sample by a relatively simple configuration.

In order to solve the above-mentioned problem, the invention described in claim 1 includes an operation of supplying the introduced sample A directly to a single analysis unit for analysis, and a sample B generated from the sample A via a converter. Are alternately executed to analyze the target component contained in the sample A based on the analysis results, and the sample A is analyzed on the analyzer side and the converter side. In the sampling device provided in the front stage of the differential method analyzer equipped with the analyzer switching valve for switching to
First and second collection bags that are accommodated in a fluid filled in a sealed container and whose volume changes with the inflow and outflow of the sample A;
A first sampling switching valve for alternately collecting the sample A in the first and second collection bags;
A second sampling switching valve for alternately introducing the sample A collected in the first and second collection bags into the inflow side of the analyzer switching valve;
The switching cycles of the first and second sampling switching valves are made the same, and these switching cycles are 2n (n is a natural number) times the switching cycle of the analyzer switching valve.

According to the second aspect of the present invention, the introduced sample A is directly supplied to the single analyzer and analyzed, and the sample B generated from the sample A via the converter is supplied to the analyzer. And an analyzer for alternately analyzing the target component contained in the sample A based on the analysis results and switching the sample A between the analysis unit side and the converter side. In the sampling device provided in the front stage of the differential method analyzer equipped with a switching valve for
First and second collection bags that are accommodated in a fluid filled in a sealed container and whose volume changes with the inflow and outflow of the sample A;
For the third sampling, the operation for collecting the sample A in the first collection bag and the operation for introducing the collected sample A into the inflow side of the analyzer switching valve are alternately performed. A switching valve;
For collecting the sample A in the second collection bag while the sample A in the first collection bag is being introduced into the inflow side of the analyzer switching valve by the third sampling switching valve. While the sample A is being collected in the first collection bag by the operation and the third sampling switching valve, the sample A in the second collection bag is introduced into the inflow side of the analyzer switching valve. And a fourth sampling switching valve that alternately performs the operation for
The switching cycles of the third and fourth sampling switching valves are the same, and these switching cycles are 2n (n is a natural number) times the switching cycle of the analyzer switching valve.

  The invention described in claim 3 is the fluid according to claim 1 or 2, wherein the fluid is an incompressible fluid such as water or oil.

According to the present invention, by maintaining the valve switching cycle in a predetermined relationship, the sample A collected by one collection bag is used to analyze the sample A, and the sample B generated from the sample by the converter. Analysis can be performed alternately, and the concentration of samples A and B, and consequently the concentration of the target component, can be measured with high accuracy by the differential method without being affected by the concentration fluctuations of the target component and coexisting components. To.
In addition, since the sampling device includes only a pair of collection bags and valves accommodated in the fluid filled in the hermetic container, the structure is not likely to be complicated and provided at a low cost. Is possible.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, FIG. 1 is a schematic configuration diagram showing a first embodiment of the present invention.

In FIG. 1, reference numeral 10 denotes a differential method analyzer such as a VOC meter, a nitrogen dioxide measuring device, an ozone meter or the like. This analyzer 10 includes a solenoid valve V1, which is a three-way valve as an analysis switching valve to which a sample A is supplied, as in FIG. 4, a conversion unit 12 that removes or converts a target component, and sampling lines 17A and 17B. And an analyzer 13 for measuring the concentration of the target component by a differential method. The analysis unit 13 is provided with a pump 16 for introducing the sample A through the electromagnetic valve V1.
Reference numeral 18 denotes a pressure gauge for measuring the pressure of the analyzer 13 (the suction pressure of the sample A).

On the other hand, 20 is a sampling apparatus according to the present embodiment.
The sampling device 20 includes a sampling line 23 to which a sample A is supplied, an electromagnetic valve V2a that is a three-way valve as a first sampling switching valve connected to the sampling line 23 on the inflow side, and the electromagnetic valve V2a. The first and second collection bags B1 and B2 having the same volume connected to the pair of discharge sides, respectively, and the second sampling in which the pair of inflow sides are connected to the outlets of the collection bags B1 and B2, respectively. An electromagnetic valve V2b, which is a three-way valve as a switching valve, and a sampling line 24 connected to the discharge side thereof are provided, and an inflow side of the electromagnetic valve V1 is connected to an outlet of the sampling line 24. V2 is a solenoid valve pair composed of solenoid valves V2a and V2b.
In addition, at least the collection bags B <b> 1 and B <b> 2 among the components of the sampling device 20 are immersed in a liquid 21 such as water or oil as an incompressible fluid filled in the inside of the sealed container 22. These collection bags B1 and B2 are formed of a material such as a fluororesin whose volume changes as the sample A flows in and out.
The solenoid valves V1, V2a, and V2b are each provided with a solenoid as a valve opening / closing means, and one side of the three-way valve is in a normally open state in which the valve is open with no electrical continuity (off state). The other side is in a normally closed state where the valve is closed with no electrical conduction.

Here, the solenoid valves V1, V2a, and V2b in FIG. 1 are shown in black in the “open” state and white in the “closed” state. In FIG. 1, the sampling line 23, the collection bag B2, and the collection bag B1 are shown. The sampling line 24, the sampling line 24, and the sampling lines 17A and 17B (the output side of the converter 12) are in communication with each other.
The electromagnetic valves V2a and V2b are switched so as to communicate with one of the collection bags B1 or B2 alternately in the same cycle. For convenience, the state of FIG. 1 is changed to the electromagnetic valve V2a and V2b. It is assumed that the valve pair V2 is in the “off” state (the state where there is no electrical conduction). Therefore, when the solenoid valve pair V2 is in an “on” state (a state where there is electrical conduction), the sampling line 23 and the collection bag B1, and the collection bag B2 and the sampling line 24 are switched to communicate with each other.
For the solenoid valve V1, the state shown in FIG. 1 is set to the “on” state.

Further, regarding the relationship between the switching cycle of the solenoid valve V1 and the solenoid valve pair V2, the switching cycle of the solenoid valve pair V2 is 2n · t _S (n is a natural number) with respect to the switching cycle t _S of the solenoid valve V1. That is, the solenoid valve pair V2 is driven in synchronism so that on and off are switched at a frequency of 1 / 2n of the solenoid valve V1.
Here, assuming that n = 1, the solenoid valve pair V2 is switched at a frequency half that of the solenoid valve V1.

Next, the operation of this embodiment will be described. FIG. 2 is a time sequence showing the operation of the difference method analyzer 10 and the sampling device 20.
First, in step i, the solenoid valve V1 is on and the solenoid valve pair V2 is off, which is in the state of FIG. At this time, due to the suction operation of the pump 16, the sample A collected in the previous step from the one collection bag B1 is passed through the electromagnetic valve V2b, the sampling line 24, the electromagnetic valve V1, and the sampling line 17A. Introduced directly into. For this reason, the analysis part 13 can measure the density | concentration of the sample A containing the target component and a coexistence component.

Further, as the sample A is discharged from the collection bag B1, the inside of the sealed container 22 becomes a negative pressure from the atmosphere, so that it has the same capacity as the sample A introduced from the collection bag B1 to the analyzer 10 side. The sample A is collected in the other collection bag B2 through the sampling line 23 and the electromagnetic valve V2a.
Here, in the present embodiment, the inside of the sealed container 22 is filled with a liquid 21 such as water or oil as an incompressible fluid, but when the flow rate of introduction into the analyzer 10 is small, the sealed container 22 is used. What is necessary is just to fill gas, such as air, as a compressive fluid in an airtight state.

  Next, in step ii, the solenoid valve V1 is turned off, but the solenoid valve pair V2 remains off. By the operation of the pump 16, the sample A is continuously introduced into the analyzer 10 from the collection bag B1, but the sample A is introduced into the converter 12 because the electromagnetic valve V1 is off. Accordingly, the converter 12 performs oxidation, reduction, etc. according to the analyzer 10 as in the conventional case, and removes the target component or generates the sample B in which the target component is converted to another component. Thus, the analysis unit 13 can measure the concentration of the sample B. During this time, the sample A is continuously collected in the other collection bag B2 via the sampling line 23 and the electromagnetic valve V2a.

  Thus, in this embodiment, since the switching cycle of the solenoid valve V1 and the solenoid valve pair V2 is different, the analysis is performed using the same sample A stored in the collection bag B1 by the previous collection step. The concentration measurement of the sample A by the unit 13, the generation of the sample B by the converter 12, and the concentration measurement of the sample B by the analysis unit 13 can be performed alternately, and are affected by fluctuations in the concentration of the target component and coexisting components. Therefore, it is possible to accurately measure the concentrations of the samples A and B. Therefore, the concentration of the target component can be measured with high accuracy based on the concentrations of the samples A and B.

  In steps iii and iv, the electromagnetic valve V1 is turned on and off, respectively, and during this time, the electromagnetic valve pair V2 maintains the on state. Thereby, in step iii, the introduction of the sample A from the collection bag B2 and the concentration measurement of the sample A by the analysis unit 13 and the collection of the sample A by the collection bag B1 are performed simultaneously. In step iv, the collection is performed. The introduction of the sample A from the collection bag B2, the generation of the sample B by the converter 12, the concentration measurement of the sample B by the analysis unit 13, and the collection of the sample A by the collection bag B1 are performed simultaneously.

That is, in steps iii and iv, the collection bag B1 is switched to the sample A collection side, and the collection bag B2 is switched to the sample A introduction side.
In these steps iii and iv, using the sample A stored in the collection bag B2 in steps i and ii, the concentration measurement of the sample A by the analysis unit 13 and the generation and analysis unit 13 of the sample B by the converter 12 are performed. Since the measurement of the concentration of the sample B can be performed alternately, the concentration of the target component can be measured accurately.

  Thereafter, after steps v and vi, the operations after steps i and ii are repeated, so that the concentration measurement of samples A and B is alternately and continuously performed while switching the collection bag for collection and introduction of sample A. Is to be executed.

FIG. 3 shows the main part of the second embodiment of the present invention, and only the sampling device 25 is shown.
In this sampling device 25, the sampling line 23 is divided into branch lines 23a and 23b in the sealed container 22, each of which is a solenoid valve V3a, which is a three-way valve as a third sampling switching valve, and a fourth sampling switching. It is connected to the branch lines 24a and 24b via a solenoid valve V3b which is a three-way valve as a valve. The remaining ports of the electromagnetic valves V3a and V3b are connected to the collection bags B1 and B2, respectively, and the branch lines 24a and 24b are combined and connected to the sampling line 24. Here, the solenoid valves V3a and V3b constitute a solenoid valve pair V3.
The point that the airtight container 22 is filled with a liquid 21 such as water or oil as an incompressible fluid is the same as in the first embodiment.

Also in this embodiment, the solenoid valves V3a and V3b are turned on and off at the same period, and the collection bags B1 and B2 communicating with the sampling line 23 or 24 are alternately switched. Now, assuming that the solenoid valve pair V3 including the solenoid valves V3a and V3b is in the “off” state, the collection bag B2 is in communication with the sampling line 23 and captures the sample A. The collecting bag B1 is in communication with the sampling line 24 and the sample A is introduced into the analyzer 10.
Accordingly, when the solenoid valve pair V3 is in the “on” state, the solenoid valves V3a and V3b are switched so that the sampling line 23 and the collection bag B1, and the collection bag B2 and the sampling line 24 communicate with each other.
Further, when the electromagnetic valve pair V3 is in the state as shown in FIG. 3, the electromagnetic valve V1 in the analyzer 10 is in the same state as in FIG.

Further, the relationship between the switching periods of the solenoid valve V1 and the solenoid valve pair V3 is synchronized so that the solenoid valve pair V3 is switched on and off at a frequency 1 / 2n that of the solenoid valve V1, as in the first embodiment. Driven. For example, when n = 1, the solenoid valve pair V3 is switched at a frequency half that of the solenoid valve V1.
For this reason, the time sequence of the entire apparatus is substantially the same as that of FIG. 2, and “electromagnetic valve pair V2” in FIG. 2 may be replaced with “electromagnetic valve pair V3”.

  Also in this embodiment, due to the difference in switching cycle between the electromagnetic valve V1 and the electromagnetic valve pair V3, the analysis unit 13 uses the same sample A stored in one collection bag by the previous collection step. The concentration measurement of the sample A by the converter 12, the generation of the sample B by the converter 12, and the concentration measurement of the sample B by the analysis unit 13 can be performed alternately, without being affected by fluctuations in the concentration of the target component and coexisting components. The concentration of samples A and B can be accurately measured. Therefore, the concentration of the target component can be measured with high accuracy based on the concentrations of the samples A and B.

In each of the embodiments described above, the minimum necessary volume of the collection bags B1 and B2 is determined by the product of the flow rate of the sample A introduced into the analyzer 10 and the open time of the solenoid valve V1, but in practice it is the product. The excess volume may be used in the same manner as a conventional buffer.
Here, an example of a method for determining the volume of the collection bags B1 and B2 will be described. The sample container of the collection bags B1 and B2 is filled with a fluid in which pressure is applied to the inside of the hermetic container 22 with the atmosphere open. After that, if one collection bag, for example, the inlet / outlet of B1 is closed and the fluid in the sealed container 22 is removed to the required amount, the other collection bag B2 opened to the atmosphere is inflated by the amount corresponding to that amount. The required volume is secured by the collection bag B2. Thereafter, the secured volume is alternately secured between the collection bags B1, B2 by the switching operation of the electromagnetic valves V1, V2a, V2b or V1, V3a, V3b described above.

  Further, when the entire apparatus is turned on, the volume of the sample A remaining in the collection bags B1 and B2 is unknown, so that the electromagnetic valve V1 and the electromagnetic valve pair V2 or V3 are difficult to synchronize. In this case, if the suction operation is performed with respect to one of the collection bags while monitoring the pressure of the analysis unit 13 with the pressure gauge 18 when the power is turned on, and the time when the pressure suddenly decreases is set as the synchronization start time, It can be easily synchronized.

Note that the pressure gauge 18 shown in FIG. 1 is normally provided in this type of analyzer 10 and therefore does not need to be newly prepared.
Further, in the case where the pressure gauge 18 is not provided, in an analyzer that does not interfere with the sample inlet (sampling line 24) being blocked for a short time, a time sufficiently longer than the switching cycle of the solenoid valve pair V2 or V3 (for example, collection) The time point when the sample A is sucked by the time required for sucking the sample A from one of the bags B1 and B2) can also be set as the synchronization start point.

  Each of the above embodiments is directed to the differential method analyzer 10 to which a gas sample is supplied, but the present invention can be similarly applied to sampling of a liquid sample.

1 is a schematic configuration diagram illustrating a first embodiment of the present invention. It is a time sequence which shows operation | movement of the difference method analyzer and sampling device in FIG. It is a block diagram which shows the principal part of 2nd Embodiment of this invention. It is a schematic block diagram which shows a prior art. It is explanatory drawing of the example of the difference method. It is a schematic block diagram which shows a prior art.

Explanation of symbols

10: difference method analyzer 12: converter 13: analyzer 16: pump 17A, 17B: sampling line 18: pressure gauge 20, 25: sampling device 21: liquid (incompressible fluid)
22: Sealed container 23, 24: Sampling line V1, V2a, V2b, V3a, V3b: Solenoid valve V2, V3: Solenoid valve pair B1, B2: Collection bag

Claims (3)

The operation of supplying the introduced sample A directly to a single analysis unit and performing the analysis and the operation of supplying the sample B generated from the sample A via a converter to the analysis unit and performing the analysis alternately are performed. A differential method comprising an analyzer switching valve for analyzing the target component contained in the sample A based on the analysis results and switching the sample A between the analysis unit side and the converter side. In the sampling device provided in the front stage of the analyzer,
First and second collection bags that are accommodated in a fluid filled in a sealed container and whose volume changes with the inflow and outflow of the sample A;
A first sampling switching valve for alternately collecting the sample A in the first and second collection bags;
A second sampling switching valve for alternately introducing the sample A collected in the first and second collection bags into the inflow side of the analyzer switching valve;
Sampling characterized in that the switching cycles of the first and second sampling switching valves are the same, and these switching cycles are 2n (n is a natural number) times the switching cycle of the analyzer switching valve. apparatus. The operation of supplying the introduced sample A directly to a single analysis unit and performing the analysis and the operation of supplying the sample B generated from the sample A via a converter to the analysis unit and performing the analysis alternately are performed. A differential method comprising an analyzer switching valve for analyzing the target component contained in the sample A based on the analysis results and switching the sample A between the analysis unit side and the converter side. In the sampling device provided in the front stage of the analyzer,
First and second collection bags that are accommodated in a fluid filled in a sealed container and whose volume changes with the inflow and outflow of the sample A;
For the third sampling, the operation for collecting the sample A in the first collection bag and the operation for introducing the collected sample A into the inflow side of the analyzer switching valve are alternately performed. A switching valve;
For collecting the sample A in the second collection bag while the sample A in the first collection bag is being introduced into the inflow side of the analyzer switching valve by the third sampling switching valve. While the sample A is being collected in the first collection bag by the operation and the third sampling switching valve, the sample A in the second collection bag is introduced into the inflow side of the analyzer switching valve. And a fourth sampling switching valve that alternately performs the operation for
Sampling characterized in that the switching cycles of the third and fourth sampling switching valves are the same, and these switching cycles are 2n (n is a natural number) times the switching cycle of the analyzer switching valve. apparatus. The sampling device according to claim 1 or 2,
The sampling apparatus, wherein the fluid is an incompressible fluid such as water or oil.

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