JPH0750703Y2 - Gas analyzer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a gas analyzer capable of simultaneously measuring the concentrations of a plurality of components contained in a sample gas.

[Conventional technology]

A plurality of components to be measured contained in the sample gas (for example,
Conventionally, when measuring the concentrations of CO ₂ gas and CO gas, as shown in FIG. 4, for example, a plurality of non-dispersive infrared analyzers A and B for single component measurement (two in this example) are used. The analyzer A was used to measure the concentration of CO ₂ gas, and the other analyzer B was used to measure the concentration of CO gas.

That is, the infrared analyzers A and B are equipped with the infrared irradiation light sources 21a,
21b, cells 22a, 22b into which sample gas S is introduced
When, the sample gas CO ₂ for detecting the concentration of CO ₂ gas and CO gas in the S, CO for pneumatic detector (condenser microphone detector and the like) 23a, and 23b, in this order, and, They are arranged so that an optical linear relationship is established. Incidentally, 24a and 24b are power sources for the light sources 21a and 21b, respectively, and 25a and 25b are choppers as modulation means interposed between the light sources 21a and 21b and the cells 22a and 22b, respectively.

[Problems to be solved by the device] In the case of such conventional means, since there are two cells, 22a and 22b, it is not possible to introduce the same gas into two different cells at the same time. CO ₂ gas and C
Not only has the basic drawback that it is not possible to simultaneously measure changes in the respective concentrations of (O gas), but since the number of analyzers is the same as the number of components to be measured, the entire instrument becomes extremely expensive and However, there is a drawback that adjustment and maintenance are troublesome and difficult.

On the other hand, as a means for measuring a plurality of components in a sample gas by a single cell, a plurality of detectors composed of solid-state detectors (pyrosensor etc.) are provided in parallel on the other end side of the cell, There is a gas analyzer that measures the concentration of a measurement target component.

However, the solid-state detector in the gas analyzer has a drawback that it is inferior to the pneumatic detector in terms of wavelength selectivity and measurement sensitivity. For example, above
The main absorption wavelength bands of CO ₂ gas and CO gas are very close to 4.3 μm and 4.7 μm, respectively.
Since CO gas has a much smaller absorption coefficient than CO ₂ gas, in such a case, an analyzer using a conductivity type detector or a startup type detector has a small absorption coefficient and the influence of interference from components other than the measurement target. There was a problem in the accuracy of the concentration value of the measurement target component.

The present invention has been made in consideration of the above matters, and an object thereof is to provide a gas analyzer which is inexpensive and can simultaneously measure the concentrations of a plurality of components to be measured with high accuracy. To do.

[Means for Solving the Problems]

In order to achieve the above object, the gas analyzer according to the present invention comprises a light source provided at one end of a cell into which a sample gas is introduced, and a pneumatic detector provided at the other end of the cell. Is characterized in that a light-shielding member having a plurality of detectors is interposed between the detector and the pneumatic detector, and the light-shielding member is movable with respect to the optical path.

[Action]

According to the above-mentioned characteristic configuration, since the infrared rays that have passed through the sample gas are modulated by the chopping action of the light blocking member configured to be movable with respect to the optical path, a plurality of detections provided on the pneumatic detector and the light blocking member are detected. The instrument can measure the concentrations of a plurality of components to be measured simultaneously and with high accuracy. Moreover, since only one analyzer is required regardless of the number of components to be measured, cost reduction can be achieved.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, which is a non-dispersive infrared analyzer for measuring CO ₂ , CO, NO and HC concentrations.

That is, 1 is a light source that emits infrared rays, for example, 2 is a cell into which the sample gas S is introduced, and the other end side of the cell 2 (light source 1
A pneumatic pneumatic detector for NO (condenser micro-fan detector, etc.) 3a for detecting the concentration of NO gas in the sample gas S is arranged on the side opposite to (3).
Immediately before the NO detector 3a, an optical filter (not shown) such as a band-pass filter that passes infrared rays in the characteristic absorption band of NO is provided. In addition, 4 is a power source for the light source 1.

A light blocking member 6 is interposed between the cell 2 and the NO detector 3a so as to be orthogonal to the optical axis. This light blocking member 6
For example, it is composed of a printed circuit board, etc., and on one side thereof, as shown in FIG. 2, for example, four solid state detectors (pyrosensors, etc.) 3b, 3c, 3d, 3e are respectively provided for CO detection and CO detection. It is provided for ₂ detection, HC detection, and comparison.

That is, an optical filter such as a bandpass filter that passes infrared rays in the characteristic absorption band of only the target component is provided immediately before each solid-state detector 3b, 3c, 3d, 3e (not shown). For example, the optical filter of CO detector 3b is CO
It consists of a band-pass filter that passes infrared rays in the characteristic absorption band. The same applies to the other CO ₂ and HC detectors 3c and 3d. On the other hand, the optical filter of the comparison detector 3e is CO, CO ₂ , HC,
It consists of a band-pass filter that allows infrared rays with wavelengths where there is no absorption band to pass through. The detector is not limited to the pyrosensor, and other thermal detectors, quantum detectors, etc. may be used.

Further, the light shielding member 6 reciprocates in the direction of arrow P at a constant cycle (for example, 1 to 10 Hz) by the two arms 9 and 10 via the joint portion 8 as the motor 7 rotates, and , Is configured to interrupt the optical path. 11 is the NO detector 3a
, 12 is a signal amplifier for the signals from CO, CO ₂ , HC and the detectors for comparison 3b, 3c, 3d, 3e.

Thus, according to the infrared analyzer having the above-described configuration, the infrared rays that have passed through the sample gas S are detected by the light-shielding member 6 that interrupts the optical path, and the NO detector 3a and the detectors 3b and 3c installed on the light-shielding member 6. , 3d, 3e respectively, and the movement of the light-shielding member 6 also serves as a chopping action for each detector, so that the infrared rays incident on each detector are modulated, and N
The O, CO, CO ₂ , and HC detectors 3a, 3b, 3d respectively output the signals of the measurement target components.

13 is a signal processing circuit for the output signals of the detectors 3a, 3b, 3c, 3d, 3e.
It is configured as shown in the block circuit diagram of the figure, for example, the signal V _S from the NO detector 3a will be described as an example.
Comparative detector amplified by the signal amplifier 12 of FIG.
Amplified by the signal V _R and the signal amplifier 11 from 3e
Volumes 14a, 14 for adjusting the signal V _S from the NO detector 3a
b and the output signals of the volumes 14a and 14b from the basic signal V
Bandpass filters 15a and 15b for extracting only _R1 and V _S1 ,
Basic signals output from bandpass filters 15a and 15b
Rectifier 16a that rectifies V _R1 and V _S1 to obtain rectified signals V _R2 and V _S2
16b and the rectified signal V _R2 input from the rectifier 16a to the rectifier 1
The subtractor 17 for subtracting the rectified signal V _R2 input from 6b and the smoother 18 for smoothing the output signal V ′ from the subtractor 17 are provided. Is supplied to a display device or the like (not shown) and is displayed as the concentration value of the measurement target component (NO in this example) contained in the sample gas. Although not shown, other CO detectors 3b, CO
The signals from the _second detector 3c and the HC detector 3d are processed in the same manner to obtain the concentration value of the measurement target component.

As described above, in the present embodiment, the case of four types of measurement target components has been described, but the present invention can also be performed when a plurality of other components are measured. Needless to say, the present invention can be applied not only to infrared gas analyzers but also to gas analyzers using light sources of other wavelengths.

[Effect of device]

As described above, according to the present invention, since the infrared rays that have passed through the sample gas are modulated by the chopping action of the light shielding member that is configured to be movable with respect to the optical path, it is installed in the pneumatic detector and the light shielding member. The concentrations of the plurality of components to be measured can be simultaneously measured with high accuracy by the plurality of detectors. Moreover, since only one analyzer is required regardless of the number of components to be measured, cost reduction is possible.

[Brief description of drawings]

FIG. 1 is an overall schematic configuration diagram showing an embodiment of a gas analyzer according to the present invention, FIG. 2 is a partial configuration diagram, and FIG. 3 is a block diagram showing a signal processing circuit of the gas analyzer. FIG. 4 is an overall schematic configuration diagram of a conventional gas analyzer. 1 ... Light source, 2 ... Cell, 3a ... Pneumatic detector, 3b, 3c, 3d, 3e ... Detector, 6 ... Shading member, S ...
… Sample gas.

Claims (1)

[Scope of utility model registration request] 1. A light source is provided at one end of a cell into which a sample gas is introduced, and a pneumatic detector is provided at the other end of the cell, and a plurality of detections are provided between the cell and the pneumatic detector. A gas analyzer, characterized in that a light-shielding member provided with a container is interposed and the light-shielding member is movable with respect to the optical path.