JP4063626B2 - Infrared gas analyzer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an infrared gas analyzer.
[0002]
[Prior art]
[Patent Document 1]
JP, 2-124448, A Conventionally, Freon gas is generally used for the refrigerant especially used for refrigerators, such as a refrigerator and a cooler. In addition to the old refrigerant CFC and HCFC, there is a new refrigerant HFC. However, there is a problem of ozone layer destruction and global warming, and it is obliged to collect and recycle Freon gas. Moreover, it is required to reliably destroy chlorofluorocarbons that cannot be recycled.
[0003]
On the other hand, typical new refrigerants include Freon 410A, Freon 407C, Freon 404A, and Freon 507A. These include a plurality of single-component Freon gases [Flon 32 (R32), Freon 125 (R125), Freon 134a (R134a). , Freon 143a (R143a)] is a so-called mixed refrigerant in which several kinds of CFCs are mixed at a predetermined ratio.
[0004]
And, as a means for measuring the CFC gas concentration, for example, as described in Patent Document 1, there is a gas analyzer (infrared gas analyzer) conforming to the NDIR method. According to this infrared gas analyzer, It has been found that it can also be used to analyze the ratio of each refrigerant component contained in the mixed refrigerant.
[0005]
By the way, in the infrared gas analyzer, it is necessary to set the cell length (optical path length) according to the absorbance of the gas component to be measured in the measurement principle. This is to obtain measurable sensitivity and to suppress the curve of the calibration curve within a predetermined range. In infrared gas analyzers, it is widely used to simultaneously analyze a plurality of components to be measured contained in a sample gas. In such a case, the magnitude of the absorbance of each component to be measured is determined. For this reason, in the past, for example, as shown in FIG. 4, the analysis was performed using an infrared gas analyzer having a plurality (two in the illustrated example) of analysis unit units 51 and 52 having the same configuration. .
[0006]
That is, in FIG. 4, 51 and 52 are analysis unit units. One analysis unit 51 includes a cell 51a, an infrared light source 51b and an optical chopper 51c provided on one window 51a1 side of the cell 51a, a cell 51a includes a detection unit 51d provided on the other window 51a2 side. The other analysis unit 52 includes a cell 52a, an infrared light source 52b and an optical chopper 52c provided on the one window 52a1 side of the cell 52a. And a detector 52d provided on the other window 52a2 side of the cell 52a. The cell 51a of one analysis unit 51 and the cell 52a of the other analysis unit 52 are connected such that the sample gas S is supplied in series. The detectors 51d and 52d of the analyzer units 51 and 52 are provided with detectors for detecting components to be measured having similar (near) absorbances, respectively.
[0007]
According to the infrared gas analyzer having the above configuration, the cell lengths of the cells 51a and 51b are set to be optimal for the absorbance of the measurement target components detected by the detection units 51 and 52, respectively. The component to be measured can be analyzed in an optimal state.
[0008]
[Problems to be solved by the invention]
However, in the infrared gas analyzer having the above-described configuration, it is necessary to provide a plurality of analysis unit units 51 and 52 (three or more depending on the combination of components to be measured) having the same configuration. Since the analysis unit is formed individually, it is necessary to individually perform corrections such as drift correction, and there is a drawback that the work and configuration for these corrections are complicated accordingly.
[0009]
The present invention has been made in consideration of the above-described matters, and an object thereof is to provide an infrared gas analyzer capable of accurately measuring a plurality of measurement target components simultaneously with a compact configuration. .
[0010]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, a cell to which a sample gas containing a plurality of components to be measured is supplied, an infrared light source for irradiating the cell with infrared light, and infrared light transmitted through the cell A plurality of bandpass filters that transmit infrared light having a wavelength that matches the infrared absorption spectrum of each measurement target component, and a plurality of detections that respectively measure the intensity of infrared light that has passed through these bandpass filters. In the infrared gas analyzer configured to analyze a plurality of components to be measured at the same time, the sample gas introduction part and the lead-out part are aligned with each other on a pair of opposite side surfaces as the cell. is formed as, and to respond to the infrared light source and the detector on opposite sides to each other in the direction orthogonal to the direction of flow of the sample gas to the outlet portion from said inlet portion The cell block inside the space where the cell window is formed, a flat first spacer consisting of IR transmission material through holes in half from the middle of the flow direction of the sample gas is formed, the first The sample gas flow includes a plate-like second spacer made of a light-shielding material in which a through hole is formed over substantially the entire length in the flow direction of the sample gas, including a through hole having the same size as the through hole in one spacer. A single unit configured to form a space having a plurality of different cell lengths in the cell block from the upstream side to the downstream side in the flow direction of the sample gas by overlapping each other in a direction orthogonal to the direction. while using the cell, a predetermined cell length in accordance with said plurality of band pass filters and detectors, the absorbance of a plurality of measurement target components, each of which detects It is characterized in that arranged so as to correspond to (claim 1).
[0011]
In the infrared gas analyzer having the above-described configuration, a single cell in which a plurality of different cell lengths are formed in the internal space of one cell block is used as a cell to which the sample gas is supplied. Since the filter and the detector are arranged so as to correspond to a predetermined cell length according to the absorbance of the measurement target component to be detected by each, only one analyzer is required, and the entire apparatus can be configured compactly. In addition, drift correction and the like can be easily performed, and running costs can be reduced.
[0012]
Then, in order to form a plurality of different cell lengths in the one cell, the first plate-shaped first made of an infrared light transmitting material in which a through hole is formed in half of the middle in the flow direction of the sample gas . A spacer and a flat plate-like second spacer made of a light-shielding material in which a through hole is formed over almost the entire length in the flow direction of the sample gas, including a through hole having the same size as the through hole in the first spacer. Since it is set as the structure arrange | positioned together, since the thickness of flat 1st, 2nd spacer becomes cell length, the setting (change) of several cell length can be performed accurately.
[0014]
In addition, a plurality of detectors can be arranged in an array according to the absorbance of the measurement target component detected by each detector (claim 2).
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the details of the present invention will be described with reference to the drawings. 1 to 3 show an embodiment of the present invention. FIG. 1 schematically shows an example of the configuration of the infrared gas analyzer of the present invention. In this embodiment, the refrigerant mixture can be measured for each refrigerant component. Is shown. In FIG. 1, reference numeral 1 denotes a cell to which a sample gas S is supplied. Here, the sample gas S is a mixed refrigerant. The detailed structure of the cell 1 will be described later.
[0016]
An infrared light source 2 is provided on one side of the cell 1 and emits infrared light IR toward the cell 1, and 3 is an optical chopper interposed between the cell 1 and the infrared light source 2. (Not shown), the motor rotates in a predetermined direction at a constant cycle. Reference numeral 4 denotes a detector unit, which will be described in detail later.
[0017]
Next, the configuration of the cell 1 will be described in detail with reference to FIGS. The cell 1 is configured to have two cell lengths La and Lb as schematically shown in FIG. That is, FIG. 2 shows the cross-sectional shape of the cell 1, and FIG. 3 shows the shape of the spacer incorporated in the cell 1. First, in FIG. 2, 5 is a cell block, and the external shape is a rectangular parallelepiped, for example, is made of a material having excellent chemical resistance such as stainless steel, and a space is formed inside. Reference numerals 6a and 6b denote an introduction part and a lead-out part for the sample gas S respectively formed on a pair of opposite side faces (side faces in the direction of arrow A in FIG. 2) of the cell block 5, and are arranged so as to be in line with each other. ing. Reference numerals 7 and 8 denote cell windows formed on surfaces facing each other in the B direction orthogonal to the A direction. One cell window 7 corresponds to the infrared light source 2 side, and the other cell window 8 corresponds to the detector section 4. Are provided to correspond to each. These cell windows 7 and 8 are made of a material having good infrared transparency such as Si. 9 is a window pressing member made of, for example, stainless steel, and 10 is a sealing member made of, for example, ethylene propylene rubber. In FIG. 2, a direction perpendicular to the paper surface, that is, a direction perpendicular to the A direction and the B direction is referred to as a C direction (see FIG. 3).
[0018]
The space of the cell block 5 in the state where the cell windows 7 and 8 are mounted is a rectangular parallelepiped, and the length (cell length) between the opposed cell windows 7 and 8 is single. In FIG. 2, cell spaces 5a and 5b having two different cell lengths La and Lb are formed as follows. That is, 11 and 12 are a first spacer and a second spacer. As shown in FIGS. 3A and 3B, these spacers 11 and 12 have the same shape in plan view (outer shape) and are rectangular. It consists of a flat plate. These spacers 11 and 12 are formed so as to completely fit the space in the cell block 5 with no gap when they are overlapped with each other.
[0019]
More specifically, the first spacer 11 is a flat plate having an appropriate thickness (for example, 0.5 mm) made of a material having good infrared transparency such as Si, and as shown in FIG. The right half of the middle of the direction is the infrared light transmitting portion 11a as it is, but the left half of the middle has a through-hole (infrared light passage hole) 11b having an isosceles trapezoidal shape in plan view. For example, it is formed by a technique such as etching.
[0020]
Further, the second spacer 12 is a flat plate having an appropriate thickness (for example, 0.4 mm) made of a light-shielding material such as stainless steel, for example, as shown in FIG. A through hole (infrared light passage hole) 12b is formed. The infrared light passage hole 12b has holes 12b1, 12b2 having the same size (same shape) as the isosceles trapezoidal infrared light passage hole 11b in the first spacer 11 (the hole 12b2 is symmetrical with the hole 12b1). It is formed line-symmetrically. Rectangular grooves 12c and 12d are formed on the right and left sides of the infrared light passage hole 12b. The infrared light passage hole 12b and the grooves 12c and 12d are formed by a technique such as etching. Reference numeral 12a denotes a light blocking portion in the second spacer 12.
[0021]
As shown in FIG. 2, the first spacer 11 is on the window 7 (infrared light source 2) side, and the second spacer 12 is on the window 8 (detector section 4) side. When overlapping and arranging in the cell block 5, the first spacer 11 has no infrared light passage hole on the side close to the gas introduction part 6 a of the cell block 5, and the infrared light of the second spacer 12. Only the passage hole 12b2 exists, and therefore, the cell space 5a is formed by the infrared light passage hole 12b2, and the cell length La is the thickness of the second spacer 12, that is, 0.4 mm in this embodiment. On the other hand, since the infrared light passage holes 11b and 12b1 exist in the first spacer 11 and the second spacer 12 on the side close to the gas outlet 6b of the cell block 5, respectively, therefore, these infrared light passage holes 11b. , 12b1 forms a cell space 5b, and its cell length Lb is the sum of the thicknesses of both spacers 11, 12, that is, 0.9 mm in this embodiment.
[0022]
As described above, inside the cell block 5, two cell spaces 5a and 5b having different cell lengths La and Lb are formed stepwise from the upstream side to the downstream side in the sample gas S supply direction. That is, in the cell block 5, as shown in FIGS. 1 and 2, a space (short cell portion) 5a having a short cell length La is formed on the upstream side close to the gas introduction portion 6a, and is close to the gas outlet portion 6b. A space (long cell portion) 5b having a long cell length Lb is formed on the downstream side.
[0023]
The configuration of the detector unit 4 provided so as to face the cell window 8 of the cell 1 configured as described above will be described with reference to FIG. It is composed of detector units 4A and 4B optically arranged in parallel, and is provided so as to correspond to the short cell portion 5a and the long cell portion 5b, respectively. In the case of consisting of various types of refrigerant components, the seven types of refrigerant components can be detected separately.
[0024]
For example, it is assumed that the seven types of refrigerant components have three types of absorbance and four types of small absorbance. In this case, the detector unit 4A corresponding to the short cell portion 5a has three pyroelectric detectors 13a, 13b, 13c and three detectors in order to detect three refrigerant components having relatively large absorbance and similar to each other. The bandpass filters 14a, 14b, and 14c are arranged concentrically so as to divide the circumference into three equal parts so as to make a pair, and the absorbance is compared with the detector unit 4B corresponding to the long cell portion 5b. In order to detect four refrigerant components that are small and similar to each other, the four pyroelectric detectors 13d, 13e, 13f, and 13g and the four band-pass filters 14d, 14e, 14f, and 14g are paired. It arrange | positions on the concentric circle so that a circumference may be divided into 4 equally. In FIG. 1, the pyroelectric detectors 13a to 13c and the band pass filters 14a to 14c, and the pyroelectric detectors 13d to 13g and the band pass filters 14d to 14g are shown in a state of being arranged on a straight line for convenience. .
[0025]
Needless to say, the seven band-pass filters 14a to 14g are set so that the central wavelength to be transmitted falls within a predetermined range in accordance with the infrared absorption spectra of the seven types of refrigerant components.
[0026]
And the output of the said detector part 4 is comprised so that it may input into the calculation control apparatus (for example, personal computer) which performs the density | concentration calculation (component ratio calculation) of each refrigerant | coolant component.
[0027]
In the infrared gas analyzer having the above configuration, since the cell 1 having a partially changed cell length is used, a single analyzer unit may be configured, and the entire apparatus can be configured compactly. In addition, drift correction and the like can be easily performed, and running costs can be reduced. Even if the sample gas S includes a plurality of measurement target components, the detectors 13a to 13g for detecting the plurality of measurement target components separately and the plurality of bandpass filters 14a to 14g are respectively paired. Furthermore, they are arranged so as to correspond to a predetermined cell length according to the absorbance of the measurement target component detected by each. That is, each of the measurement target components detected by each has a large absorbance corresponding to the short cell portion 5a and the small absorbance corresponding to the long cell portion 5b. When measuring separately, it is possible to obtain the sensitivity necessary for measurement, and the curve of the calibration curve is suppressed within a predetermined range, and a plurality of components to be measured can be measured individually in a preferable state suitable for each. it can.
[0028]
In the above embodiment, when the sample gas S is introduced into the cell 1, the sample gas S is introduced from the narrow side (short cell 5a side) and then flows to the wide side (long cell 5b side). Therefore, the sample gas S is reliably diffused in the cell 1 and can be reliably irradiated with the infrared light IR from the infrared light source 2. Moreover, it is smoothly discharged from the cell 1.
[0029]
In the above-described embodiment, the cell block 5 is made of an infrared transmissive material and has a spacer 11 formed with an infrared light passage hole 11b in a part thereof. The cell block 5 has two different cell lengths La and Lb by superimposing the spacer 12 on which the infrared light passage hole 12b is formed so as to include a portion corresponding to the outside light passage hole 11b. Although a space is formed, a space having three or more different cell lengths can be formed by increasing the number of stacked spacers. In the cell 1 configured as described above, since the thickness of the spacer becomes the cell length, the cell length can be set (changed) with high accuracy.
[0030]
[0031]
[0032]
Furthermore, in the said embodiment, although the optical chopper 3 was provided between the infrared light source 2 and the cell 1 as an infrared gas analyzer, it replaces with this and the optical chopper 3 is the cell 1 and the detector part. 4 may be provided. Further, it may be configured as follows. That is, for example, the infrared light source 2 may be a thin film light source, and power may be intermittently supplied to the infrared light source 2 to intermittently emit infrared light IR. In the infrared gas analyzer configured as described above, the mechanical working portion is eliminated and the configuration is further reduced in size.
[0033]
In addition, it cannot be overemphasized that the infrared gas analyzer of this invention can be widely used not only for the component ratio analysis of the said mixed refrigerant but for various gas analysis.
[0034]
【The invention's effect】
As described above, according to the infrared gas analyzer of the present invention, a plurality of components to be measured can be simultaneously measured with high accuracy while having a compact configuration, and can be widely used for various gas analyses.
[Brief description of the drawings]
FIG. 1 schematically shows an example of the configuration of an infrared gas analyzer according to the present invention.
FIG. 2 is a diagram showing a cross-sectional shape of a cell of the infrared gas analyzer.
FIG. 3 is a diagram showing a shape of a spacer incorporated in the cell.
FIG. 4 is a diagram for explaining a conventional technique.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Cell, 2 ... Infrared light source, 5 ... Sensor block , 5a ... Short cell part, 5b ... Long cell part, 7, 8 ... Cell window, 11 ... 1st spacer, 11b ... Through-hole ( infrared light passage hole) ), 12 ... second spacer, 12b ... through-hole (infrared light passing hole), 13a to 13g ... detector, 14a-14g ... bandpass filter, IR ... infrared light, La, Lb ... cell length, S ... Sample gas.

Claims (2)

A cell to which a sample gas containing a plurality of measurement target components is supplied, an infrared light source for irradiating the cell with infrared light, and infrared absorption of each measurement target component among the infrared light transmitted through the cell A plurality of band-pass filters that transmit infrared light having a wavelength matched to the spectrum; and a plurality of detectors that respectively measure the intensity of infrared light that has passed through these band-pass filters. In an infrared gas analyzer configured to analyze simultaneously,
As the cell, the sample gas introduction part and the lead part are formed in a straight line on a pair of opposite side surfaces , and in a direction orthogonal to the flow direction of the sample gas from the introduction part to the lead part Infrared in which a through hole is formed in the space in the cell block in which cell windows corresponding to the infrared light source and the detector are formed on the surfaces facing each other in the middle of the flow direction of the sample gas. A light- shielding material in which a through-hole is formed over substantially the entire length in the flow direction of the sample gas, including a flat plate-like first spacer made of a light-transmitting material and a through-hole having the same size as the through-hole in the first spacer a plate-shaped second spacer become more, by superimposing one another arranged in a direction perpendicular to the flow direction of the sample gas, the San the cell block While using a single cell configured such that a space having a plurality of different cell length toward the downstream side is formed from the flow direction upstream of Rugasu,
An infrared gas analyzer, wherein the plurality of band-pass filters and detectors are arranged so as to correspond to a predetermined cell length according to the absorbance of a plurality of measurement target components detected by each of the plurality of band-pass filters and detectors.   The infrared gas analyzer according to claim 1, wherein a plurality of detectors are arranged in an array according to the absorbance of the measurement target component detected by each detector.

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