JPH0269638A - Fluid analyzing method by double fluid modulating system - Google Patents

Abstract

PURPOSE:To improve the measuring accuracy of such noxious components as exhaust fumes from automobiles, waste gases from factories, etc., contained in the atmosphere by dividing each fume or gas into two flows with a phase difference of 90 deg. in between and performing a synchronous detection rectifying process or smoothing process on each fluid modulated sample simultaneously and continuously made to flow to an analyzing section when the fume or gas is analyzed. CONSTITUTION:Comparison fluids R1 and R2 are prepared from sample fluids S1 and S2 obtained from different fluids or one fluid divided into two systems by setting a phase difference of 90 deg. between the fluids R1 and R2 with a common frequency. Then fluid modulation is performed by alternately passing the sample fluids and comparison fluids. Namely, the fluids S1 and S2 and R1 and R2 are simultaneously and continuously supplied to an analyzing section A provided with one detector D and its preamplifier 2. Then each analysis value is obtained on the fluids S1 and S2 by processing the output signal O (=O1+O2) of the detector D with a signal processing means B constituted of the combination of the 1st and 2nd synchronous detection rectifying means 3a and 3b and the 1st and 2nd smoothing means 4a and 4b.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention employs a unique technique never seen before, called the double fluid modulation method (this is the name given by the inventors). Although only one detector is used, two types (or two systems)
This was done with the aim of providing a completely new fluid analysis method that allows sample fluids to be analyzed simultaneously and continuously.

[Conventional technology]

For example, harmful components such as automobile exhaust gas and factory exhaust gas contained in the atmosphere (No.
Conventionally, a chemical luminescence detector (CLD) has been used as a fluid analysis method when analyzing the concentration (and thus the amount) of H, C, or CO.
) or a flame ion detector (FID).
), or non-dispersive infrared analyzers (NDIR) equipped with pneumatic detectors using a condenser microphone type or micro flow type, or solid state detectors such as thermopiles or semiconductors. A method using a fluid analysis device that employs a detector (sensor) is known.

By the way, when performing the above-mentioned fluid analysis, it is necessary to analyze different types of fluids in the same sample fluid, such as No and NO8, methane (CH4) and HC other than methane (NMHC), or CO and CO□. It is often necessary to measure the concentration of two types of components simultaneously and continuously, but in order to achieve this with the fluid analysis method conventionally used, it is necessary to use two detectors (
sensor) was required.

That is, when simultaneously and continuously measuring N Oh, N Ox, the sample fluid is divided into two measurement systems, and the - system has a first NO detection system for independently measuring the NO concentration in the sample gas. One system is equipped with a second NO detector, and the other system is equipped with a second NO detector for measuring the total NO concentration in the processing fluid generated by converting Not in the sample gas to NO. NO detector is required (
The No□ concentration is obtained as the difference between the total No concentration detected by the second NO detector and the single No concentration detected by the first NO detector (this method is called the difference method), and methane and HC other than methane. (NMHC), the sample fluid is divided into two measurement systems, and one system is equipped with a first HC detector to measure the total HCtlA (THC) in the sample fluid. , the other system is provided with a second HC detector for measuring the methane concentration in the treated gas generated by performing a process to remove HC other than methane in the sample fluid by catalytic combustion. (A difference method is also used in this case, and NMHC is obtained as the difference between the THC concentration detected by the first HC detector and the methane concentration detected by the second HC detector.) Also, CO and CO in the sample fluid
In the case of simultaneous and continuous measurement of A and A, the sample fluid is divided into two measurement systems, and one system is equipped with a CO detector, and the other system is equipped with a CO detector. Two different detectors are required: a detector and a CO2 detector.

By dividing the same sample fluid into two systems as described above, it is not only possible to simultaneously and continuously analyze two types of components in the sample fluid, but also to analyze two different sample fluids in each system. It is clear that a plurality of detectors (sensors) are similarly required when simultaneously and continuously analyzing the specific components contained.

[Problem to be solved by the invention]

However, as mentioned above, when performing simultaneous and continuous analysis of two types of components in the same sample fluid, or simultaneous and continuous analysis of specific components contained in two different sample fluids, it is difficult to use the conventional method. The need to use two detectors (sensors) in this way not only poses the problem of (a) increasing the size of the analyzer and increasing manufacturing costs, but also (b) requiring the use of two detectors each. (1) The adjustment of each detector is insufficient and there may be zero adjustment errors between the two detectors. If there is a difference in sensitivity or difference in sensitivity, a very large measurement error will occur, causing various problems.

In order to avoid such problems, it is recommended to alternately measure two types of components in the same sample fluid using an analyzer equipped with only one detector, or to measure two different types of sample fluids alternately. A so-called batch-like analysis method in which measurements are taken alternately can be considered, but in that case, the disadvantage is that the measurement data becomes discontinuous because simultaneous and continuous measurements cannot be performed. When performing analysis using a quantitative method, there is a risk that measurement accuracy will be significantly degraded. Therefore, adopting such a batch analysis method simply to save the number of detectors is
This is not a good idea as it may lead to a major sacrifice of the original purpose of fluid analysis.

Therefore, in view of the conventional situation, the present inventors have conducted intensive research and have developed a method that allows for detection of only one fluid by adopting an innovative method called a multi-fluid modulation method in which the fluid modulation frequency for each sample fluid is different. We have developed a completely new fluid analysis method and device that can simultaneously and continuously analyze multiple sample fluids (or divided into multiple systems) using only a single device. Regarding its basic concept, please refer to December 1986.
The date of May 11 has already been proposed in many earlier applications, including Japanese Patent Application No. 1983-314806.

That is, the fluid analysis method and apparatus using the multi-fluid modulation method according to the earlier application has multiple components, as is clear from the basic conceptual diagram shown in FIG. 10 and the specific configuration diagram of main parts shown in FIG. 11. (in this example, two) sample fluids 31 and 32 (these may be originally different or may be a single sample fluid divided into two systems) are respectively Different frequencies Fl
(1 Hz in this example), fluid modulation means Vl, V2 for fluid modulation at F2 (2 Hz in this example), and only one detector d, and each fluid modulated sample fluid Sl, An analysis section a to which S2 is simultaneously and continuously supplied, and an output signal 0 from the detector d in the analysis section a are suitably frequency separated means and signal rectification/smoothing means (first
(shown conceptually in Figure 0), each modulation frequency Fl, F for each sample fluid SL, S2 is
By separating the two signal components 01°o2 and rectifying and smoothing them, each of the sample fluids 31. S2
The signal processing means consists of a signal processing means for obtaining an analytical value for the signal, and as specifically shown in FIG. Two band pass filters al and a2 are provided in parallel with each other, which selectively pass only signals in bands around the respective modulation frequencies Fl and F2 from the output signal O, and each of the band pass filters al ( After a2), in synchronization with the actual fluid modulation operation by the fluid modulation means vl (V2) corresponding to the passband frequency Fl (F2),
A synchronous detection rectifier bl (b2) for detecting and rectifying the output signal from the band pass filter al (a2) is provided, and a synchronous detection rectifier bl (b2) is provided at the subsequent stage of each of the synchronous detection rectifiers bt (b2) for smoothing the output signal therefrom. The smoothing circuit cl (c2
) is provided.

In other words, in a fluid analysis device using a multi-fluid modulation method having such a configuration, a comparative fluid is R1,
Two sample fluids Sl and S2 (or divided into two systems) fluid-modulated at different frequencies Fl and F2 by R2 are simultaneously and continuously sent to an analysis section a having only one detector d. By supplying, first,
From that single detector d, all sample fluid Sl
, 32, the individual measurement signal components (ol, o2) are superimposed within the -shaft as one measurement signal 0 (=o 1
+02), which was completely unthinkable in the conventional wisdom, and next, the output signal O from the single detector d is exemplified in FIG. 10, for example. Using a signal processing means constructed by appropriately combining a frequency separation means and a signal rectification/smoothing means, the sample fluids 31 and 32 are separated into signal components olO2 of each modulation frequency Fl and F2. By performing signal processing such as rectification and smoothing processing, the analytical values for each of the sample fluids Sl and S2 are obtained. Therefore, even if two types of components in the same sample fluid are analyzed simultaneously or continuously, , even when performing simultaneous and continuous analysis of specific components contained in two different sample fluids, only one detector (
It is only necessary to provide a sensor (sensor) d, and therefore, compared to conventional fluid analysis devices that require two detectors, the entire device can be made smaller and more cylindrical, and costs can be reduced. Detector d can be adjusted easily and quickly, and zero adjustment errors and sensitivity differences between multiple detectors do not occur as in conventional methods, so good measurement accuracy can always be ensured. Therefore, the conventional problem as mentioned above (
It has the fundamentally excellent advantage of being able to eliminate all of A), (B), and (T) at once.

However, even in the fluid analysis method using the multi-fluid modulation method according to the prior art which has such excellent advantages (however, the fluid modulation frequency for each sample fluid is different, so to speak, a frequency separation method), (1) Since the fluid modulation frequency for the sample fluid is different, it is inevitable that differences in frequency characteristics will occur, which may cause measurement errors. Of the modulation means, the fluid modulation frequency is the lowest (in the above example, Fl-
1 Hz), while the durability of the fluid modulation means is determined by the highest fluid modulation frequency (F2-2 Hz in the above example). It was found that there is a problem in that it is difficult to optimally design the modulation frequency.

The present invention was made as a result of further research in view of the above circumstances, and its purpose is to use only one detector, but to divide the flow into two types (or into two systems). ) A fluid analysis method using a double fluid modulation method that can simultaneously and continuously measure a sample fluid,
Moreover, by making the fluid modulation frequency constant for each sample fluid, it is possible to obtain even better measurement accuracy and to improve the durability of the entire device. .

[Means for solving problems]

In order to achieve the above object, the fluid analysis method using the double fluid modulation method according to the present invention is based on the basic conceptual diagram shown in FIG.
As shown in the claim correspondence diagram), two types of sample fluids Sl and S2 (this may be originally different, or a single sample fluid may be divided into two systems) are fluid-modulated by reference fluids R1 and R2 at a predetermined frequency F (Hertz) and with a phase relationship that is 90° or approximately 90@ different from each other, and an analysis section A has only one detector. simultaneously and continuously supplying each of the fluid-modulated sample fluids 31 and 32 to
01+02) are subjected to synchronous detection rectification and smoothing processing using synchronous signals corresponding to each fluid modulation operation for each of the sample fluids S1 and S2, thereby obtaining each analysis value regarding each of the sample fluids St and 32. It is characterized by

(Effects) The effects achieved by employing such distinctive means are as follows.

That is, in the fluid analysis method using the double fluid modulation method according to the present invention, for example, rotary pulp, a 3-way switching solenoid valve, a 4-way switching solenoid valve, etc. Two types of fluids are modulated by comparative fluids R1 and R2 at a predetermined (common) frequency F and with a phase relationship that is different from each other by 90° or approximately 90° using appropriate fluid modulating means consisting of: (or split into two systems) sample fluid S1. By simultaneously and continuously supplying S2 to the analysis section A, which has only one detector, the individual measurement signals corresponding to both sample fluids Sl and S2 are first obtained from that single detector. We adopted a more unique method of obtaining a single measurement signal 0 (-01+02) in which components 01 and 02 were superimposed all at once, and then obtained an output signal 0 (O1+02) from the single detector. ), for example, by using an appropriate signal processing means configured by combining a synchronous detection rectification means and a smoothing means as exemplified in the figure.

Since each analysis value for each of the sample fluids SL and S2 is obtained by performing synchronous detection rectification and smoothing processing using a synchronous signal that matches each fluid modulation operation for S2, even if two Only one detector (sensor) is required for simultaneous and continuous analysis of different types of components, or for simultaneous and continuous analysis of specific components contained in two different sample fluids.
It is possible to use a simple and inexpensive analyzer equipped with only D, and therefore the entire apparatus can be made smaller and simpler than conventional fluid analysis methods that require two detectors. In addition, it is easy to reduce costs, the detector can be adjusted easily and in a short time, and there is no zero adjustment error or sensitivity difference between two detectors as in the past, so it is always possible to achieve good results. It is now possible to ensure measurement accuracy, and unlike the fluid analysis method using the frequency-separated multi-fluid modulation method according to the prior art described above, it is possible to make the phase relationship of the fluid modulation for two sample fluids different from each other. By adopting a phase-separated double fluid modulation method, the fluid modulation frequency for both sample fluids can be kept constant, making it easy to set the most suitable fluid modulation frequency for the analyzer. Therefore, it has become possible to further improve the measurement accuracy and the durability of the device as a whole.

〔Example〕

Hereinafter, a specific embodiment of the fluid analysis method using the double fluid modulation method according to the present invention will be described with reference to the drawings (FIGS. 2 to 9).

FIG. 2 relates to the first embodiment, and shows NOx contained in a sample fluid such as the atmosphere or exhaust fluid from production equipment.
Alternatively, it shows a schematic configuration of a fluid analysis device using a double fluid modulation method, which is configured by applying the method of the present invention when analyzing the concentration of H, C, etc.

Now, as shown in the figure, two types of sample fluids 31
．． S2 (which may be different in nature or may be a single sample fluid split into two systems, as detailed below), into the first and second systems, respectively. Using the fluid modulation means la, lb, the comparative fluid R
1 and R2 (generally zero fluid is used), at a predetermined common frequency F (set to 1 Hz in this example) and with mutually different phase relationships (phase difference θ between the two). 90” or approximately 906) (i.e., passing the sample fluid and the reference fluid alternately), each of the fluid-modulated sample fluids 31
．． S2 (R1, R2) are simultaneously and continuously supplied to an analysis section A having only one detector D (sensor) and a preamplifier 2 for it. In this case, the detector in the analysis section A is -a,
Chemical luminescence detector (CLD) for NO detection
Alternatively, since a type of flame ion detector (FID) through which the sample fluid passes directly is used, such as a flame ion detector (FID) for detecting hydrocarbons (HC), both sample fluids modulated as described above are Sl, S2 (R1,
R2) is supplied to the detector in a mixed state.

Therefore, the signal O outputted from the detector via the preamplifier 2 has individual measurement signal components Of corresponding to both sample fluids St and S2, as schematically shown in the figure.
, 02 are collectively superimposed on one measurement signal (o=0
1+02).

Therefore, the output signal 0 (-01+02) from the detector D (preamplifier 2) is transferred to the first and second synchronous detection rectification means 3, for example, as conceptually illustrated in FIG.
a (3b) and a first and second smoothing means 4a (4b).

By performing synchronous detection rectification using a synchronous signal corresponding to each fluid modulation operation for S2, the sample fluids S1 and S2 are separated into signal components 0f02, and then the respective signal components 01 and 02 are smoothed. By performing signal processing, each of the sample fluids SL, S
In this example, each analysis value related to 2 is obtained.

FIG. 3 relates to the second embodiment, and shows COx contained in a sample fluid such as the atmosphere or exhaust fluid from production equipment.
This figure shows a schematic apparatus of a main part of a fluid analysis method using a double fluid modulation method, which is configured by applying the method of the present invention to the case of analyzing 4 degrees.

In this case, the analysis section A of the device consists of a non-dispersive infrared analyzer (NDIR) at -m, and therefore a detector D
As the sensor, a type through which the sample fluid does not pass directly is used, such as a condenser microphone type or microflow type detector, or a solid state detector such as a thermopile or semiconductor. However, as shown in this figure, when the analysis section A is configured with a so-called single cell type NDIR using only one cell C, the fluid modulation is also performed as in the case of the first embodiment. Both sample fluids S
l, 32 (R1, R2) are the cells C in a mixed state.
The absorbance of infrared rays for measurement passing through the cell C is measured by a detector.

Regarding other configurations in this example,
Since it is the same as that of the first embodiment, the same reference numerals are given to the members having the same functions, and the explanation thereof will be omitted.

FIG. 4 relates to the third embodiment, and this is also a schematic device of the main part of the fluid analysis method using the double fluid modulation method, which is configured by applying the method of the present invention when analyzing COX etc. once. It shows.

In this case, the analysis section A is replaced with a so-called double cell type non-dispersive infrared analyzer (ND) having two cells ClC2.
IR), both fluid-modulated sample fluids S1 and S2 (R1°R2) are supplied into separate cells CI and C2 without being mixed with each other. The absorbance of each measuring infrared ray that has passed through both cells CI and C2 is simultaneously measured by one detector. Although not shown, the two cells CI,
C2 has, for example, a solid filter for CO measurement on one side, and a solid filter for CO□ measurement on the other side.

In addition, regarding other configurations in this example,
Since it is the same as that of the first and second embodiments, members having the same functions will be given the same reference numerals and their explanation will be omitted.

By the way, both sample fluids S1. S2 is, for example, 2
They may be originally different, as in the case where each sample fluid is introduced separately from two exhaust channels, or a single sample fluid SO may be divided into two systems, as illustrated in Fig. 5. It may be. This generally refers to CO and COt or No and NOx in the same sample fluid SO.
It is applied when simultaneously and continuously measuring methane and HC other than methane (NMHC), but in that case,
As shown in the figure, at least one of the systems is equipped with a converter 5 for converting NO□ to NO or CO to CO8, and a non-methane removal device or other necessary components, although not shown in the figure. Usually, a filter or the like is provided. Note that, as illustrated in FIG. 5, a common comparison fluid RO (for example, zero fluid) may be used for the comparison fluids R1 and R2.

Further, each of the fluid modulation means 1a, lb may have any configuration as long as it can alternately switch between the sample fluid 5l (S2) and the comparison fluid R1 (R2) at a predetermined frequency. For example, , as shown in FIG. 6(a), it may be constructed of a rotary pulp in which the internal rotor is driven by a motor M, for example, or as shown in FIG. 6(a).
It may be configured with a four-way switching solenoid valve as shown in b), or it may be configured using a three-way switching solenoid valve, although not shown.

As shown in FIGS. 6(a) and 6(b), one or both of the fluid modulating means 1a and 1b detects the actual fluid modulating operation and generates a corresponding synchronizing signal. A synchronizing signal generator 9 (9a, 9b) is attached to generate the synchronous signal.

FIG. 7 shows a specific example of the configuration of the signal processing means B, in which the signal O output from the detector via the preamplifier 2 is converted into a signal O corresponding to the fluid modulation frequency F.
After noise components of other frequencies are removed in advance by passing through a band pass filter 6 having a center frequency of Hertz, the signal processing system branches into two signal processing systems installed in parallel with each other, and one signal processing system includes: 1st t-body modulation means 1a
As shown in FIGS. 6(a) and 6(b), the synchronizing signal from the first synchronizing signal generator 9a attached to the first fluid modulating means 1a is , a first synchronous detection rectifier circuit 7a is provided for synchronously rectifying the output signal O from the band pass filter 6, and further, at a subsequent stage, the output signal from the first synchronous detection rectifier circuit 7a is smoothed and A low-pass filter (L, P, F) as an example of the first smoothing circuit 8a for removing high-frequency noise is provided, and the other signal processing series includes a 22i! The signal representing the actual fluid modulation operation by the L-body modulation means 1b is generated from the second synchronous signal generator 9b attached to the second fluid modulation means 1b, as shown in FIGS. 6(a) and 6(b). synchronous signal> for synchronously rectifying the output signal O from the bandpass filter 6.
A synchronous detection rectifier circuit 7b is provided, and a second smoothing circuit 8b is provided at the subsequent stage for smoothing the output signal from the second synchronous detection rectifier circuit 7b and removing high frequency noise.
A low pass filter (L.

P, F).

It should be noted that the signal processing means B shown in FIG.
This is an example of a circuit configuration when a synchronizing signal generator 9 is attached to only one of the fluid modulating means (for example, the first fluid modulating means 1a), as shown in FIG. A signal whose phase differs by θ (90' or approximately 90°) from a synchronization signal (a signal representing the actual fluid modulation operation of the first fluid modulation means 1a) obtained from the signal generator 9 (a signal representing the actual fluid modulation operation of the second fluid modulation means 1b). The configuration may be such that a phase shift circuit 10 is provided that generates a signal representing a fluid modulation operation.

FIG. 9 shows the operation of each part and a signal timing chart in the fluid analysis method using the double fluid modulation method configured as described above, and as is clear from this diagram, the first synchronous detection rectifier circuit 7a In the first smoothing circuit 8a, the detection signal corresponding to the sample fluid S2 is canceled and only the detection signal corresponding to the sample fluid Sl is output as a significant signal related to the concentration signal, while the second synchronous detection In the rectifier circuit 7b and the second smoothing circuit 8b, the detection signal corresponding to the sample fluid Sl is canceled, and only the detection signal corresponding to the sample fluid S2 is output as a significant signal regarding the concentration signal.

〔Effect of the invention〕

As is clear from the detailed description above, according to the fluid analysis method using the double fluid modulation method according to the present invention, the sample fluid (divided into two types or systems) can be
Fluid modulation is performed using a comparative fluid at a predetermined common frequency and with a phase relationship different from each other by 90' or approximately 90°, and all sample fluids subjected to fluid modulation are
By simultaneously and continuously supplying the analyzer with a single detector, the individual measurement signal components corresponding to all the sample fluids from that single detector were first superimposed all at once. Try to get one measurement signal,
The output signal from the single detector is then subjected to synchronous transverse rectification and smoothing processing by synchronous signals corresponding to each fluid modulation operation for each sample fluid, respectively. Since analytical values are obtained, even when performing simultaneous and continuous analysis of two types of components in the same sample fluid, or simultaneous and continuous analysis of specific components contained in two different sample fluids. , it is possible to use a simple and inexpensive fluid analysis device equipped with just one detector (sensor), compared to conventional fluid analysis methods that require two detectors. , the entire device can be easily miniaturized and simplified, and costs can be reduced, and the detector can be adjusted easily and in a short time, and
Since there is no zero adjustment error or sensitivity difference between the two detectors as in the past, it is possible to always ensure good measurement accuracy. Unlike fluid analysis methods that use multi-fluid modulation, we use a phase-separated multi-fluid modulation method in which the phase relationship of fluid modulation for two sample fluids is different, so that fluid modulation for both sample fluids is possible. The frequency can now be kept constant, making it easy to set the most suitable fluid modulation frequency for the analyzer, thereby further improving measurement accuracy and the durability of the device as a whole. It is possible to achieve a remarkable effect.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram (diagram corresponding to claims) of the basic concept and operation of the fluid analysis method using the double fluid modulation method according to the present invention, and FIGS. 2 to 9 illustrate various specific embodiments. 2 is an overall schematic configuration diagram of a fluid analysis device according to a first embodiment configured by applying the method of the present invention, and FIG. 3 is a schematic configuration diagram of main parts of a fluid analysis device according to a second embodiment. , FIG. 4 is a schematic diagram of the main parts of the fluid analysis device according to the third embodiment, FIG. 5 is a schematic diagram of the main parts for supplementary explanation of each embodiment, and FIGS. 6 (a) and (b) 7 is a schematic configuration diagram of main parts for further supplementary explanation of each embodiment, and FIG. 8 is a modification of FIG. 7. FIG. 9 is a schematic configuration diagram of main parts corresponding to an example, and a timing chart for explaining the operation common to each of the above embodiments. Also, Figure 10 and Figure 1! The figures are for explaining the technical background of the present invention and problems in the prior art, and FIG. A schematic circuit configuration diagram of the main part thereof is shown. SL, S2: sample fluid, R1, R2: comparison fluid, la, lb: fluid modulation means, F: predetermined fluid modulation frequency, θ
: Phase difference of fluid modulation operation, 9 (9a, 9b):
Synchronous signal generator, A: Analysis section, D: Detector, B: Signal processing means, ? a, 7b: Synchronous detection rectifier circuit, 8a, 8b
: Smoothing circuit. Applicant Horiba Manufacturing Co., Ltd. Representative Patent Attorney Hideo Fujimoto

Claims (1)

[Scope of Claims] Two types of sample fluids (or divided into two systems) are controlled by a comparative fluid at a predetermined frequency and with a phase relationship that is different from each other by 90° or approximately 90°. simultaneously and continuously supplying each of the fluid-modulated sample fluids to an analysis section having only one detector, and output signals from the detectors in the analysis section to an analysis section having only one detector; A fluid analysis method using a double fluid modulation method, characterized in that each analysis value for each sample fluid is obtained by performing synchronous detection rectification and smoothing processing using a synchronization signal that matches each fluid modulation operation.