JPH079398B2 - Fluid analysis device by multi-fluid modulation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention adopts a unique non-conventional method called a multi-fluid modulation method (this is the name named by the present inventors). Multiple (or shunted to multiple systems) while using only one detector
The purpose of the present invention is to provide a completely new fluid analysis device capable of simultaneously and continuously analyzing a sample fluid.

[Conventional technology]

For example, harmful components such as automobile exhaust gas and factory exhaust gas (NOx, HyC
As a fluid analyzer used when analyzing the concentration (and thus the amount) of z, COx, etc., conventionally, an analyzer equipped with a chemiluminescence detector (CLD) or a flame ion detector is used. (FID) or various non-dispersive infrared analyzers (NDIR) such as condenser microphone type or microflow type pneumatic detectors, thermopile or solid state detectors such as semiconductors A fluid analysis device that employs a detector (sensor) is used.

By the way, when performing the fluid analysis as described above, for example, NO and NO ₂ , or methane (CH ₄ ) and HC other than methane (NMHC), or CO and CO ₂ ,
In many cases, it is necessary to measure the concentration of a plurality of components (two in this case) in the sample fluid simultaneously and continuously. (Two in this case) detectors (sensors) were required.

That is, when simultaneously measuring NO and NO ₂ simultaneously, the sample fluid is divided into two measurement systems, and one system is a first NO detector for measuring the NO concentration in the sample gas by itself. And the other system is provided with a _second NO detector for measuring the total NO concentration in the processed fluid produced by converting NO ₂ in the sample gas into NO. 2
One NO detector is required (NO ₂ concentration is obtained as the difference between the total NO concentration detection value by the _second NO detector and the NO single concentration detection value by the first NO detector, and this method is called the difference method. ), And in the case of simultaneous continuous measurement of methane and HC other than methane (NMHC), the sample fluid is divided into two measurement systems, and one system is divided into the total HC concentration (TH
A first HC detector for measuring C) is provided, and the other system is subjected to a process of catalytically burning and removing HC other than methane in the sample fluid to measure the methane concentration in the produced gas. To install a second HC detector for
One HC detector is required (again, the difference method is used, and NMHC is the THC concentration detection value by the first HC detector and the second HC detector).
(It is obtained as the difference from the detected value of methane concentration by the detector.) Also, when measuring CO and CO ₂ in the sample fluid at the same time, split the sample fluid into two measurement systems and Requires a CO detector and the other system has a CO ₂ detector, and so on. Two different detectors are required, a CO detector and a CO ₂ detector.

Then, by dividing the same sample fluid into a plurality of systems as described above, it is not limited to the case where the simultaneous and continuous analysis of a plurality of components in the sample fluid is performed, and a plurality of different sample fluids are included in each. It is clear that a plurality of detectors (sensors) are also required when attempting simultaneous simultaneous analysis of specific components.

[Problems to be solved by the invention]

However, as described above, when performing simultaneous continuous analysis of a plurality of components in the same sample fluid, or performing simultaneous continuous analysis of a specific component contained in each of a plurality of different sample fluids, as in the conventional device, The fact that multiple detectors (sensors) have to be used not only means that (a) the analyzer becomes large and manufacturing costs are high, but (b) zero detectors are required for each detector. Since adjustments such as span adjustments are required, the labor required for measurement is large and very troublesome. (C) The adjustment of each detector is not sufficient, and zero adjustment error and sensitivity difference between multiple detectors If present, it causes various problems such as a very large measurement error.

Therefore, in order to avoid such problems, an analyzer equipped with only one detector is used to alternately measure a plurality of components in the same sample fluid, or alternatively, a plurality of different sample fluids are alternately measured. It may be possible to use a batch-type analysis method, which is a measure to measure in the same way, but in that case, there is a disadvantage that the measurement data becomes discontinuous because simultaneous and continuous measurement cannot be performed. When the analysis using the difference method is performed, there is a possibility that the measurement system may be greatly deteriorated. Therefore, it is not a good idea to adopt such a batch-type analysis method merely to save the number of detectors, because it may seriously sacrifice the original purpose of fluid analysis.

The present invention has been made in view of such conventional circumstances, and an object thereof is to use a plurality of (or a plurality of system divided) sample fluids while using only one detector. The object is to develop a fluid analysis device that can perform simultaneous and continuous and accurate analysis.

[Means for solving problems]

In order to achieve the above-mentioned object, the fluid analysis device by the multi-fluid modulation method according to the present invention is clear from the basic conceptual diagram shown in FIG. 1 and the specific configuration diagram (claim correspondence diagram) of the main part shown in FIG. , A plurality of sample fluids S1, S2, ..., Sn (which may be different from each other originally or a single sample fluid may be divided into a plurality of systems), respectively. , The comparison fluids R1, R2, ..., Rn have different frequencies F1, F2 ,.
Fluid modulation means V1, V2, for fluid modulation with Fn (Hertz)
, Vn and only one detector D, and the analysis unit A to which the fluid-modulated sample fluids S1, S2, ..., Sn are simultaneously and continuously supplied, and the analysis unit A Output signal O from detector D
By appropriately using frequency separating means and signal rectifying / smoothing means (which is conceptually shown in FIG. 1), the respective modulation frequencies F1, F2, for the respective sample fluids S1, S2, ..., Sn.
,, Fn signal components O1, O2, ..., On are separated and subjected to rectification and smoothing processing, respectively, so that the sample fluids S1, S2,
,, and signal processing means B for obtaining an analysis value regarding Sn. Further, in the signal processing means B, the output from the detector D is as specifically shown in FIG. From the signal O to each of the modulation frequencies
A plurality of band-pass filters a1, a2, ..., An that pass only signals in the bands near F1, F2, ..., Fn are provided in parallel with each other, and each of the band-pass filters a1 (a2, ..., An) In the latter stage,
From the bandpass filter a1 (a2, ..., an) in synchronization with the actual fluid modulation operation by the fluid modulation means V1 (V2, ..., Vn) corresponding to the passband frequency F1 (F2, ..., Fn) To provide a synchronous detection rectifier b1 (b2, ..., bn) for detecting and rectifying the output signal of, and for smoothing the output signal from each synchronous detection rectifier b1 (b2, ..., bn) Smoothing element c1 (c2, ..., c
n) is provided.

[Action]

The action exerted by such a characteristic configuration is as follows.

That is, in the fluid analysis device using the multi-fluid modulation method according to the present invention, as will become more apparent from the description of the embodiments described later, for example, a rotary valve, a three-way switching solenoid valve, a four-way switching solenoid valve, or the like. , Vn using appropriate fluid modulation means V1, V2, ..., Vn
A plurality of sample fluids S1, S2, ..., Sn, which are fluid-modulated at different frequencies F1, F2, ..., Fn by R2 ,. By simultaneously and continuously supplying to the analysis unit A having the following, first, from the single detector D, individual measurement signal components (O1, O1) corresponding to all the sample fluids S1, S2 ,.
O2, ..., On) is one measurement signal O
(= O1 + O2 + ... + On) is obtained by adopting a peculiar method which was not considered at all in the conventional common sense, and next, the output signal O from the single detector D is illustrated in FIG. 1, for example. As described above, by using the signal processing means B configured by appropriately combining the frequency separating means and the signal rectifying / smoothing means, the sample fluids S1 and S
Signal component O of each modulation frequency F1, F2, ..., Fn for 2, ..., Sn
By performing signal processing of separating into 1, O2, ..., On and performing rectification and smoothing respectively, the sample fluid S
Since the analytical values for 1, S2, ..., Sn are obtained, even if simultaneous analysis of a plurality of components in the same sample fluid is performed,
Alternatively, when performing simultaneous continuous analysis of specific components contained in a plurality of different sample fluids,
Since only one detector (sensor) is required, it is easy to reduce the size and simplification of the entire device and reduce the cost compared with the conventional general fluid analysis device that required multiple detectors. In addition, the detector can be adjusted easily and in a short time, and zero adjustment error and sensitivity difference between multiple detectors cannot occur as in the past, so that good measurement accuracy can always be ensured. Became.

By the way, as the signal processing means B, a computer capable of performing arithmetic processing of numerical analysis such as Fourier analysis (corresponding to frequency separation processing) and absolute value averaging processing (corresponding to rectification / smoothing processing) is used. , Or
Although it is possible to configure appropriate means by various software or hardware such as using an electric circuit such as a lock-in amplifier, in the device of the present invention, in particular, the bandpass filter a1 (a2, ..., an) , A synchronous detection rectifier b1 (b2, ..., bn) and a smoothing element (for example, a low-pass filter or a capacitor) c1 (c2, ..., cn) are connected in series, and a plurality of signal processing sequences are provided in parallel. Therefore, as compared with the above-mentioned means using a computer or a lock-in amplifier, not only is it very simple and inexpensive, but the bandpass filter a1
(A2, ..., an) is not enough to supplement the separation action with the synchronous detection rectifier b1 (b2, ..., bn) so that more accurate separation can be achieved. , For example, compared to the one that simply rectifies the absolute value immediately after frequency separation using only a bandpass filter, it is possible to obtain a significantly superior signal processing performance (S / N ratio). is there.

〔Example〕

Hereinafter, a specific embodiment of the fluid analysis apparatus using the multi-fluid modulation method according to the present invention will be described with reference to the drawings (FIGS. 3 to 8).

FIG. 3 shows an overall schematic configuration of a fluid analysis device by the multi-fluid modulation method according to the first embodiment, which is, for example, NOx or HyCz contained in a sample fluid such as an exhaust fluid from the atmosphere or a production facility. It is used when the concentration of is analyzed.

Now, as shown, a plurality (two in this case) of sample fluids S1, S2 (this may be different in nature, or (Which may be split into a plurality of systems) by using the fluid modulation means V1 and V2, respectively, and different frequencies F1 and F2 (compared to zero gas) by the reference fluids R1 and R2 (generally zero gas is used). Hertz) (for example, F1 = 1 Hz, F2 = 2 Hz) after fluid modulation (that is, the sample fluid and the reference fluid are alternately passed at a predetermined frequency), and then the fluid-modulated sample fluids S1 and S2 (R1, R2) is the only detector D
It is configured to supply the analysis unit A having a (sensor) simultaneously and continuously. In this case, the detector D in the analysis unit A is generally a chemical luminescence detector (CLD) for NO detection or a flame ion detector (FI) for hydrocarbon (HC) detection.
Since the type in which the sample fluid directly passes, such as D), is used, both the fluid-modulated sample fluids S1 and S2 (R1, R2) are supplied to the detector D in a mixed state. .

Therefore, the signal O output from the detector D via the preamplifier 2 has individual measurement signal components (O1, O2) corresponding to both sample fluids S1, S2, as schematically shown in the figure.
One measurement signal (O = O1 + O2) in which
Will be obtained as.

Therefore, the output signal O from the detector D, as conceptually illustrated in FIG.
And the signal rectifying circuit 4 are combined to form a signal processing means B composed of an electric circuit.
By performing signal processing in which signal components O1 and O2 of modulation frequencies F1 and F2 for S1 and S2 are separated and rectified respectively, analytical values for the sample fluids S1 and S2 are obtained.

The specific circuit configuration of the signal processing means B is the fourth.
It is as shown in the figure.

That is, the signal O output from the detector D through the preamplifier 2 is branched into a plurality of signal processing sequences (two sequences in this example) provided in parallel with each other, and one signal processing sequence includes a sample Modulation frequency for fluid S1 (F1 Hertz)
The bandpass filter a1 for separating and extracting (passing) only the signal O1 of is provided, and at the subsequent stage,
Due to the synchronization signal from the synchronization signal generator 1a attached to the fluid modulation means V1 for the sample fluid S1 (the signal representing the actual fluid modulation operation by the fluid modulation means V1: F1 Hertz), the bandpass filter a1 alone is not sufficient. The output signal O1 from the band-pass filter a1 can be converted at the same time as a more accurate separation by supplementing the frequency separation action which may be
Is provided with a synchronous detection rectifier b1 for synchronously rectifying
In the subsequent stage, a low-pass filter as a smoothing element c1 for smoothing the output signal from the synchronous detection rectifier b1 and removing high frequency noise is provided, and the other signal processing series is for the sample fluid S2. In addition to providing a bandpass filter a2 for separating and extracting (passing) only the signal O2 of the modulation frequency (F2 Hertz),
At the subsequent stage, the bandpass filter a2 is supplied with a synchronization signal from the synchronization signal generator 1b attached to the fluid modulation means V2 for the sample fluid S2 (a signal representing the actual fluid modulation operation by the fluid modulation means V2: F2 Hertz). There is a possibility that it may be insufficient only by supplementing the frequency separation effect to perform more accurate separation, and at the same time, to convert the separated AC into DC, the output signal O2 from the bandpass filter a2. Synchronous detection rectifier b2 for synchronous rectification of
Further, a low pass filter as a smoothing element c2 for smoothing the output signal from the synchronous detection rectifier b2 and removing high frequency noise is provided at the subsequent stage.

FIG. 5 shows a schematic configuration of a main part of a fluid analysis device using the multi-fluid modulation method according to the second embodiment. This is, for example, COx contained in a sample fluid such as exhaust fluid from the atmosphere or production equipment. It is used when analyzing the concentration.

In this case, the analysis unit A of the apparatus is generally composed of a non-dispersive infrared analyzer (NDIR), and therefore the detector D (sensor) is a pneumatic type such as a condenser microphone type or a microflow type. A type such as a detector, a thermopile, or a solid-state detector such as a semiconductor, through which a sample fluid does not directly pass is used. However, as shown in this figure, the analysis unit A
Is constructed by a so-called single-cell type NDIR using only one cell C, the fluid-modulated sample fluids S1, S2 (R
1, R2) are supplied to the cell C in a mixed state, and the absorbance of the infrared ray for measurement passing through the cell C is measured by the detector D.

In addition, regarding other configurations and the like in this embodiment,
Since it is similar to that of the first embodiment, the members having the same functions are designated by the same reference numerals, and the description thereof will be omitted.

FIG. 6 shows a schematic structure of a main part of a fluid analysis device by a multi-fluid modulation system according to the third embodiment, which is also used when analyzing the concentration of COx or the like.

In this case, the analysis unit A is a so-called double cell type non-dispersive infrared analyzer (NDIR) having two cells C1 and C2.
Since it is composed of
1, S2 (R1, R2) will be supplied to the separate cells C1 and C2 without being mixed with each other.
The absorbance of each infrared ray for measurement passing through 1 and C2 is simultaneously measured by one detector D. Although not shown, the two cells C1 and C2 may have, for example, a C in one of them.
A solid filter for measuring O and a solid filter for measuring CO ₂ are attached to each other.

Also, regarding other configurations and the like in this embodiment,
Since it is similar to that of the first and second embodiments, the members having the same functions are designated by the same reference numerals, and the description thereof will be omitted.

By the way, the plurality of sample fluids S1 and S2 may be different from each other, as in the case where they are individually guided from a plurality of exhaust flow paths, or, as illustrated in FIG. 7, A single sample fluid S0 may be divided into a plurality of systems. This is generally applied to the case where CO and CO ₂ in the same sample fluid S0, NO and NO _2, or methane and HC other than methane (NMHC) are simultaneously measured continuously. In that case, , A converter 5 for converting NO ₂ to NO or CO to CO ₂ in at least one system as shown, or a non-methane removal device (not shown), Alternatively, a required filter or the like is usually provided. As shown in FIG. 7, the comparative fluid R
Also for R1 and R2, the common R0 (for example, zero gas) may be used.

Further, each of the fluid modulation means V1 and V2 is connected to the sample fluid S1 (S
2) and the comparative fluid R1 (R2) can be switched alternately at a predetermined frequency, the configuration is arbitrary. For example, a rotary valve as shown in FIG. Alternatively, it may be constituted by a 4-way switching solenoid valve as shown in FIG. 8B, or, although not shown, it may be constructed by using a 3-way switching solenoid valve. There is no.

〔The invention's effect〕

As is clear from the above detailed description, according to the fluid analysis device by the multi-fluid modulation method according to the present invention, a plurality of sample fluids are provided with fluid modulation means for performing fluid modulation at different frequencies by comparison fluids, respectively, By constructing such that all the fluid-modulated sample fluids are simultaneously and continuously supplied to the analysis section having only one detector, first, all the sample fluids are produced from that one detector. To obtain a single measurement signal in which the individual measurement signal components corresponding to are collectively superposed, and then separate the single measurement signal into signal components of respective modulation frequencies for the respective sample fluids and rectify them respectively. It is completely unthinkable in the conventional wisdom that an analysis value for each sample fluid is obtained by performing signal processing such as smoothing processing. Since it employs a unique method that was not available, even when performing simultaneous continuous analysis of multiple components in the same sample fluid, or simultaneous analysis of specific components contained in each of multiple different sample fluids. However, only one detector (sensor) needs to be provided. Therefore, the measurement system can be made smaller and simpler and the cost can be reduced as compared with the conventional general fluid analysis device that requires a plurality of detectors. It is possible to easily adjust the detectors easily and in a short time, and zero adjustment error and sensitivity difference between multiple detectors as in the conventional method cannot occur, ensuring good measurement accuracy at all times. In addition, as the signal processing means, a plurality of signal processing sequences each including a bandpass filter, a synchronous detection rectifier, and a smoothing element connected in series are provided in parallel. Because it has a,
Compared with other means using a computer or a lock-in amplifier, for example, it can be constructed very simply and inexpensively, and a bandpass filter alone may not be enough to supplement the frequency separation effect with a synchronous detection rectifier. Since it is configured so that more accurate separation can be performed, it is significantly superior to, for example, a structure in which the absolute value rectification is performed immediately after frequency separation using only a bandpass filter. Signal processing performance (S / N
Ratio) can be obtained, which is a remarkably excellent effect.

[Brief description of drawings]

FIG. 1 and FIG. 2 are explanatory views (claim correspondence diagram) of the basic concept and operation of the fluid analysis apparatus by the multi-fluid modulation method according to the present invention, and the specific configuration of the main part thereof.
Is. Also, FIGS. 3 to 8 show various specific embodiments of the fluid analysis device by the multi-fluid modulation method according to the present invention,
FIG. 3 is an overall schematic configuration diagram of the first embodiment, FIG. 4 is a specific circuit configuration diagram of an essential part thereof, FIG. 5 is a schematic configuration diagram of an essential part of the second embodiment, and FIG. FIG. 7 is a schematic configuration diagram of a main part of the embodiment, and FIG. 7 is a schematic configuration diagram of a main part for supplementary description of each embodiment. FIGS. 8A and 8B are other supplementary descriptions of the respective embodiments. 3 is a schematic configuration diagram of a main part for FIG. S1, S2, ...: Sample fluid, R1, R2, ...: Comparative fluid, F1, F2, ...: Modulation frequency, V1, V2, ...: Fluid modulation means A: Analytical unit, D: Detector, B: Signal processing Means, O: output signal from detector D, O1, O2, ...: Signal components of each modulation frequency F1, F2, ... for each sample fluid S1, S2, ..., a1, a2, ...: Bandpass filter, b1 , b2,…: Synchronous detection rectifier, c1, c2,…: Low pass filter.

Claims (1)

[Claims] 1. A fluid modulation means for fluid-modulating a plurality of sample fluids (or divided into a plurality of systems) at frequencies different from each other by a reference fluid, and a single detector and An analysis section to which each fluid-modulated sample fluid is supplied simultaneously and continuously, and an output signal from the detector in the analysis section is separated into signal components of each modulation frequency for each sample fluid and rectified respectively. And signal processing means for obtaining an analysis value for each of the sample fluids by performing a smoothing process. Further, in the signal processing means, the output signal from the detector is used to adjust each of the modulation frequencies. A plurality of band-pass filters that pass only signals in the vicinity of the band are provided in parallel with each other, and at the subsequent stage of each band-pass filter. In synchronization with the actual fluid modulation operation by the fluid modulation means corresponding to the pass band frequency, a synchronous detection rectifier for detecting and rectifying the output signal from the band pass filter is provided, and, in the subsequent stage of each synchronous detection rectifier, A fluid analysis device by a multi-fluid modulation method, characterized in that a smoothing element for smoothing an output signal from the fluid analysis device is provided.