Technical Field
The present invention relates to an analyzing device that
quantitatively analyzes measurement target components contained in a
sample by performing a multivariate analysis using a spectral spectrum
5 obtained by irradiating light to the sample, for example, using a method
of Fourier-transform infrared spectroscopy (FTIR).
Background Art
In a conventional gas analyzing device using the FTIR method,
10 as disclosed in Patent Document 1, a comparative sample or a
measurement sample is respectively accommodated in measurement
cells and infrared light from an infrared light source is irradiated to the
measurement cells so as to measure interferograms of the comparative
samples or measurement sample. Then, these interferograms are
15 respectively Fourier-transformed in an information processing unit so
as to obtain power spectrums. Then, a ratio of the power spectrum of
the measurement sample to the power spectrum of the comparative
sample is calculated. This calculated ratio is then converted to an
absorbance scale to thereby obtain an absorption spectrum. Then,
20 components (single component or multiple components) contained in
the measurement sample are quantitatively analyzed on the basis of
the absorbance at wave number points in this absorption spectrum.
In this FTIR method, since there is a merit that a
1
multi-component analysis of a measurement sample can be
continuously and concurrently performed, this FTIR method is used in
research and development of alternative fuels such as bio-ethanol
mixed fuel and catalysts etc. in an engine exhaust gas field, and it is
5 also used in evaluation of a reforming system by a concurrent analysis
of methanol, carbon monoxide and carbon dioxide in a study of a
fuel-cell methanol reforming system.
However, for example, in the case where a cold-start
10 measurement is performed in an engine exhaust gas test, there is a
problem that components other than measurement target components
(for example, measurement extra-target components such as xylene,
acetylene, propylene (or propane) and normal-hexane) are exhausted
due to such as incomplete combustion of the fuel so that the
15 measurement extra-target components exert interference influence on
the measurement target components. Here, although it is conceivable
to compensate the interference influence of the measurement
extra-target components, the measurement extra-target components
are not always exhausted in the cold-start measurement, and the
20 measurement extra-target components are exhausted, for example, in a
state that the catalyst has not been warmed up to a prescribed
operating temperature (i.e., in an inactive state of the catalyst). If so,
only a simple compensation of the interference influence of the
measurement extra-target components in the cold-start measurement
2
will results in an excessive compensation of the interference influence
even in a state that the measurement extra-target components are no
longer exhausted, and there arises a problem that a measurement error
of the measurement target components becomes large.
5 Citation List
Patent Literature
Patent Document 1: JPA 2000-346801
Summary of Invention
10 Technical Problem
Therefore, the present invention has its essential object that
reduction of the interference influence and reduction of the
measurement error, which are in a trade·off relationship, can be made
compatible in a quantitative analysis of one or more measurement
15 target components in a sample.
Solution to Problem
That is, a sample gas analyzing device pertaining to the present
invention is configured to quantitatively analyze one or more
measurement target components in a sample gas by performing a
20 multivariate analysis using a spectral spectrum obtained by irradiating
light to the sample gas. The sample gas analyzing device includes:
library data including standard spectrum data for each of the one or
more measurement target components for use in the multivariate
analysis; and switching means adapted to switch the library data
3
between a first generation condition which is a sample gas generation
condition in a period of a predetermined time lapse after starting the
sample gas generation and a second generation condition which is a
sample gas generation condition after the predetermined time lapse,
5 wherein, under the first generation condition, the quantitative analysis
of the one or more measurement target components is performed using
first library data obtained by compensating interference influence of
measurement extra-target components which are components other
than the measurement target components; and under the second
10 generation condition, the quantitative analysis of the one or more
measurement target components is performed using second library data
obtained without compensating interference influence of the
measurement extra-target components.
15 With this configuration, under the first generation condition
where the interference influence of the measurement extra-target
components with respect to the measurement target components
largely appears, one or more measurement target components are
quantitatively analyzed using the first library data obtained by
20 compensating the interference influence of the measurement
extra-target components. Whereas, under the second generation
condition where the interference influence of the measurement
extra-target components with respect to the measurement target
components is small in an ignorable degree, one or more measurement
4
target components are quantitatively analyzed using the second library
data obtained without compensating the interference influence of the
measurement extra-target components. Therefore, the reduction in
interference influence and the reduction in measurement error can be
5 made compatible.
In order that the effect of the present invention is made more
remarkable, it is preferable that the sample is an engine exhaust gas,
and the first generation condition is a period of a predetermined time
10 lapse after starting the engine. The type of the gas components
contained in the engine exhaust gas in a period of a predetermined time
lapse (for example, a time period of a catalyst reaching a predetermined
operating temperature, etc.) after starting the engine is different from
that in a time period thereafter, and the interference influences thereof
15 are also different. At this time, under the first generation condition, it
is possible to compensate not only the interference influence among a
plurality of measurement target components but also the interference
influence due to various measurement extra-target components (for
example, xylene, acetylene, propylene (or propane) and normal-hexane,
20 etc.) generated by incomplete combustion of the fuel so that the
interference influence can be reduced. Whereas, under the second
generation condition, since the quantitative analysis of the
measurement target components can be performed regardless of
interference influence ofthe measurement extra-target components
5
which are hard to be contained in the engine exhaust gas, the
measurement error of the measurement target components can be
reduced.
5 The measurement extra-target components contained in the
sample gas are different according to the types of the fuel to be burned
by the engine. Therefore, it is desirable that the sample gas analyzing
device further includes a library data storage part for storing the first
library data and the second library data, wherein the library data
10 storage part stores the first library data respectively classified
according to the types of the fuel to be burned by the engine. With this
configuration, since the first library data is prepared for every type fuel,
the interference influence of the measurement target components can
be accurately compensated.
15
It is preferable that the sample gas analyzing device further
includes a fuel type data reception part for receiving fuel type data
indicating the types of the fuel, wherein the first library data
corresponding to the types of the fuel received by the fuel type data
20 reception part is used in the first generation condition. With this
configuration, only by inputting fuel type data, the first library data
corresponding to the type of the fuel can be automatically selected so
that user's usability can be improved.
6
In order that the effect of the present invention is made more
remarkable, it is preferable that the sample gas is a catalyst-passed gas
produced by passing a simulated gas through a catalyst and that the
first generation condition is a period of a predetermined time lapse
5 after starting the passing of the simulated gas through the catalyst.
Since the performance of the catalyst is varied in accordance with the
temperature thereof, the type of the gas components contained in the
catalyst-passed gas in a period of a predetermined time from the
starting time of passing the simulated gas through the catalyst is
10 different from the type thereof after that period, and the interference
influence in the above period is also different from that thereafter.
Thus, by differentiating the library data used under the first generation
condition from that used under the second generation condition, the
reduction in interference influence of the measurement target
15 components and the reduction in measurement error can be made
compatible.
In addition, a computer-readable storage medium storing a
program pertaining to the present invention is used in a sample gas
20 analyzing device that quantitatively analyzes one or more
measurement target components in a sample gas by performing a
multivariate analysis using a spectral spectrum obtained by irradiating
light to the sample gas, the sample gas analyzing device including
library data including standard spectrum data for each of the one or
7
more measurement target components for use in the multivariate
analysis, the program causing a computer to execute functions of.
switching the library data between a first generation condition which is
a sample gas generation condition in a period of a predetermined time
5 lapse after starting the sample gas generation and a second generation
condition which is a sample gas generation condition after the
predetermined time lapse; under the first generation condition,
performing the quantitative analysis of the one or more measurement
target components using first library data obtained by compensating
10 interference influence of measurement extra-target components which
are components other than the measurement target components; and
under the second generation condition, performing the quantitative
analysis of the one or more measurement target components using
second library data obtained without compensating interference
15 influence of the measurement extra-target components.
Advantageous Effects of Invention
According to the present invention configured as described
above, by performing a specific compensation every generation
20 condition in a quantitative analysis of one or more measurement target
components in a sample, it becomes possible to improve the
compensation accuracy of the measurement target components and the
reduction in interference influence and the reduction in measurement
error can be made compatible.
8
Brief Description of Drawings
Fig. 1 is a schematic diagram showing a configuration of a
5 sample gas analyzing device using the FTIR method of the present
embodiment;
Fig. 2 is an equipment configuration diagram of a computing
device of the same embodiment;
Fig. 3 is an equipment configuration diagram of a computing
10 device of the same embodiment;
Fig. 4 is a schematic diagram showing gas components at a cold
start and a library used in the cold start; and
Fig. 5 is a functional block diagram showing a computing device
of a modified embodiment.
15
Description of Embodiments
The following describes a sample gas analyzing device 100 using
a FTIR method pertaining to the present invention with reference to
20 the accompanying drawings.
The sample gas analyzing device 100 using the FTIR method of
the present embodiment is intended for automobile exhaust gas in
order to continuously measure a multi-component concentration
contained in the exhaust gas (sample gas) exhausted from an engine of
9
the automobile.
In specific, as shown in Fig. 1, this analyzing device 100
includes an analyzing part 1 which outputs an interferogram and a
5 computing device 2 which processes the interferogram outputted from
the analyzing part 1.
The analyzing part 1 includes: an infrared light source 3
configured to emit infrared light rays in parallel; an interference
10 mechanism 4 interfering the infrared light rays from the infrared light
source 3 to be outputted; a measurement cell 5 irradiated with the
infrared light rays from the infrared light source 3 via the interference
mechanism 4; and a semiconductor detector 6 for receiving the infrared
light rays which have passed through the measurement cell 5. The
15 interference mechanism 4 includes a fixed mirror 7, a beam splitter 8
and a movable mirror 9 which moves, for example, in parallel to the XY
direction by a drive mechanism (not shown).
As shown in Fig. 2, the computing device 2 is a general-purpose
20 or dedicated computer provided with a CPU 201, a memory 202, an I/O
interface 203, an AID converter 204, input means 205, a display and the
like. This computer cooperates the CPU 201 and peripheral
equipment and the like according to a prescribed program stored in a
predetermined region of the memory 202 so as to exhibit functions as
10
the library storage part Dl, the quantitative analyzing part 21 etc. as
shown in Fig. 3.
The library data storage part D1 stores library data including
5 known standard spectral data for each of a plurality of measurement
target components (for example, ethanol, water, formaldehyde, etc.) for
use in multivariate analysis and calibration curve data and the like.
In specific, the library storage part D1 stores the first library
10 data corresponding to the first generation condition (0 :'S t :'S Tx) which is
an exhaust gas generation condition from a starting time of an engine
up to a predetermined time Tx lapse in an engine exhaust gas test, and
the second library data corresponding to the second generation
condition (t> Tx) which is an exhaust gas generation condition after the
15 predetermined time Tx lapse.
The first library data is library data including standard spectral
data obtained by compensating interference influence of the
measurement extra-target components
It should be noted that the present invention is not limited to
the above embodiment.
15
For example, although the sample gas analyzing device using
the FTIR method for automobile exhaust gas is described in the above
embodiment, the present invention can be used for various other
applications such as a sample gas analyzing device using a FTIR
20 method for a reforming system of fuel cell methanol. In addition, the
present invention can be also applied to an analyzing device using an
Iep light emission analyzing method or an analyzing device in which
measurement components are affected by interference components such
as an analyzing device using a Raman spectroscopy.
16
•
In addition, the sample gas analyzing device of the present
invention can be also used in combination with a catalyst evaluation
device that generates a simulated exhaust gas for performing an
5 evaluation test of a catalyst and passes the simulated exhaust gas
through the catalyst to be tested. In this case, the sample gas is
catalyst-passed gas which has passed through the catalyst and the first
generation condition is a predetermined time elapsed from a start up of
the simulated exhaust gas passing through the catalyst.
10
Furthermore, although the quantitative analyzing part is
configured to automatically switch a plurality of types of library data in
the above embodiment, the library data may be manually switched by a
user.
15
Moreover, the types ofthe measurement extra-target
components contained in the engine exhaust gas are also different in
accordance with the types of the fuel to be burned in the engine under
the first generation condition. For example, in the case of using
20 gasoline or diesel fuel, propylene is a measurement target component
and propane is a measurement extra-measurement component.
However, in the case of using eNG (compressed natural gas), propane is
a measurement target component and propylene is a measurement
extra-measurement component. As the other fuels, alcohol fuel and
17
•
dimethyl ether etc. may be considered. Therefore, the first library
data to be stored in the library data storage part D1 may be prepared in
separation by types of the fuels to be burned by an engine. In addition,
Fig. 5 shows a case of preparing the library data as the first library data
5 for each of fuel types A to D. With this arrangement, since the first
library data is prepared for each type of fuels, the interference influence
of the measurement target components under the first generation
condition can be accurately compensated for every type of fuels .
10 In this case, as shown in Fig. 5, the computing device 2 of the
sample gas analyzing device 100 includes a fuel type data reception
part 22 for receiving fuel type data indicative of a fuel type, and it is
considered that the quantitative analyzing part 21 is configured to
acquire the first library data corresponding to a type of the fuel
15 indicated by the fuel type data from the library data storage part D1 on
the basis of the fuel type data received by the fuel type data reception
part 22. With this configuration, only by inputting the fuel type data
by a user, the first library data corresponding to the type of the fuel can
be automatically selected so that the usability of the user can be
20 improved.
Moreover, although the library data of the above embodiment is
prepared for each of the first generation condition and the second
generation condition by separating the cold"start measurement into the
first generation condition and the second generation condition with
18
II
time lapse, it may be also possible to prepare a plurality of types of
library data by differentiating the measurement method and
measurement target etc. so that each of the different measurement
methods and measurement targets is used as each of the generation
5 conditions.
In addition, under the first generation condition, other than
calculating the concentration of the measurement target components
obtained by compensating the interference influence of the
10 measurement extra-target components with respect to the
measurement target components, it may be configured that the
concentration of the measurement extra-target components is
calculated. In this case, the first library data includes standard
spectral data of the measurement extra-target components.
15
In addition, the present invention should not be limited to the
embodiment described above, and various modifications are of course
possible within the scope unless departing from the intended spirit
thereof.
20 Reference Signs List
100 Sample gas analyzing device
D1 Library data storage part
21 Quantitative analyzing part
22 Fuel type data reception part

CLAIMS
WE CLAIM:
1. A sample gas analyzing device that quantitatively analyzes
5 one or more measurement target components in a sample gas by
performing a multivariate analysis using a spectral spectrum obtained
by irradiating light to the sample gas, comprising:
library data including standard spectrum data for each of the
one or more measurement target components for use in the
10 multivariate analysis; and
switching means adapted to switch the library data between a
first generation condition which is a sample gas generation condition in
a period of a predetermined time lapse after starting the sample gas
generation and a second generation condition which is a sample gas
15 generation condition after the predetermined time lapse, wherein
under the first generation condition, the quantitative analysis of
the one or more measurement target components is performed using
first library data obtained by compensating interference influence of
measurement extra-target components which are components other
20 than the measurement target components; and
under the second generation condition, the quantitative
analysis of the one or more measurement target components is
performed using second library data obtained without compensating
interference influence of the measurement extra-target components.
20
2. The sample gas analyzing device as claimed in claim 1,
wherein the sample gas is an engine exhaust gas exhausted from an
engine, and wherein the first generation condition is a period of a
5 predetermined time lapse after starting the engine.
3. The sample gas analyzing device as claimed in claim 2 further
comprising a library data storage part for storing the first library data
and the second library data, wherein the library data storage part
10 stores the first library data respectively classified according to types of
fuel to be burned by the engine.
4. The sample gas analyzing device as claimed in claim 3 further
comprising a fuel type data reception part for receiving fuel type data
15 indicating the types of the fuel, wherein the first library data
corresponding to the types of fuel received by the fuel type data
reception part is used in the first generation condition.
5. The sample gas analyzing device as claimed in claim 1,
20 wherein the sample gas is a catalyst-passed gas produced by passing a
simulated gas through a catalyst, and wherein the first generation
condition is a period of a predetermined time lapse after starting the
passing of the simulated gas through the catalyst.
21
6. A computer-readable storage medium storing a program for
use in a sample gas analyzing device that quantitatively analyzes one
or more measurement target components in a sample gas by performing
a multivariate analysis using a spectral spectrum obtained by
5 irradiating light to the sample gas, the sample gas analyzing device
including library data including standard spectrum data for each of the
one or more measurement target components for use in the
multivariate analysis, the program causing a computer to execute
functions of.
10 switching the library data between a first generation condition
which is a sample gas generation condition in a period of a
predetermined time lapse after starting the sample gas generation and
a second generation condition which is a sample gas generation
condition after the predetermined time lapse;
15 under the first generation condition, performing the
quantitative analysis of the one or more measurement target
components using first library data obtained by compensating
interference influence of measurement extra-target components which
are components other than the measurement target components; and
20 under the second generation condition, performing the
quantitative analysis of the one or more measurement target
components using second library data obtained without compensating
interference influence of the measurement extra-target components.