TECHNICAL FIELD
[0001] The present invention relates to a diluter that dilutes particulate matter contained in a
sample gas, an analysis system that analyzes the particulate matter contained in the sample
gas diluted by the diluter, and a method for analyzing the particulate matter using the analysis
5 system.
BACKGROUND ART
[0002] Conventionally, there is known an analysis device that analyzes particulate matter
contained in a sample gas such as atmospheric gas to be measured. For instance, there is
10 known an analysis device, in which a sample gas is blown to a collection filter, such that
particulate matter contained in the sample gas is collected by the collection filter, and
collected amount (mass concentration) of the particulate matter collected by the collection
filter, and/or elements (and their concentrations) contained in the particulate matter are
measured (see, for example, Patent Citation 1).
15 [0003] There is known an analysis device that analyzes particulate matter contained in an
automobile exhaust gas. In this analysis device, a sampled engine exhaust gas is diluted or
vaporized, and then the number concentration of the particulate matter in the exhaust gas is
measured by a particle number counter (see, for example, Patent Citation 2)
20 PRIOR ART CITATIONS
PATENT CITATION
[0004] Patent Citation 1: JP-A-2015-219197
3
Patent Citation 2: JP-A-2010-261938
SUMMARY OF INVENTION
TECHNICAL PROBLEM
5 [0005] Presently, it is studied to use the analysis device described above for a purpose of
analyzing particulate matter contained in an exhaust gas or the like. In general, however, the
exhaust gas contains particulate matter at a high concentration, and if the exhaust gas
containing particulate matter at a high concentration is sampled as it is, there will occur a
problem such as clogging in a collection unit that collects the exhaust gas. Therefore, it is
10 considered that, when using the analysis device described above to analyze particulate matter
contained in the exhaust gas, the analysis device samples the exhaust gas that is diluted by a
diluter.
[0006] In addition, for example, an exhaust gas generated in a combustion process or the
like may contain particulate matter at a high concentration, which has a particle size of a few
15 tens nanometers to a few tens micrometers at a certain concentration. The exhaust gas
containing such particulate matter cannot be diluted appropriately by a conventional diluter.
It is because such particulate matter is easily transported by air but is hardly
dispersed uniformly due to turbulence generated by collision of a dilution gas that dilutes the
particulate matter in a tube.
20 [0007] In addition, if the gas containing the particulate matter contacts with an inner wall
surface of the diluter, the particulate matter contained in the gas adheres to the inner wall
surface and is hardly removed again. In other words, a part of the particulate matter contained
4
in the gas flowing into the diluter remains in the diluter and becomes a loss, and hence the
particulate matter in the gas cannot be diluted at a constant dilution ratio.
[0008] Further, for example, even though it is a combustion process, a gasoline engine may
generate an exhaust gas containing particulate matter having a particle size of a few tens
5 nanometers at a high concentration. Such particulate matter with an order of nanometer
causes dispersion due to Brownian movement, and hence has a tendency to be dispersed
uniformly into a gas more easily than particulate matter having a particle size of a few tens
micrometers.
[0009] On the other hand, if the gas containing the particulate matter with an order of
10 nanometer contacts with the inner wall surface of the diluter, the particulate matter enters into
a micro recess of the inner wall surface and is hardly removed again. In other words, a part of
the particulate matter contained in the gas flowing into the diluter remains in the diluter and
becomes a loss, and hence the particulate matter in the gas cannot be diluted at a constant
dilution ratio.
15 [0010] If the particulate matter to be measured cannot be diluted appropriately in this way, it
is difficult to accurately measure a concentration of the particulate matter.
[0011] It is an object of the present invention to uniformly dilute particulate matter
contained in a sample gas containing the particulate matter, and to minimize a loss of the
particulate matter due to adhesion of the particulate matter to the wall surface during the
20 dilution process, to realize accurate dilution.
TECHNICAL SOLUTION
5
[0012] A plurality of embodiments as means that solves the problem are described below.
These embodiments can be arbitrarily combined as necessary.
A diluter according to an aspect of the present invention includes an inflow portion,
a mixing portion, a discharge portion, a connection portion, and an introduction portion.
5 The inflow portion allows the sample gas containing particulate matter to flow in.
The mixing portion has an inner diameter larger than that of the inflow portion, and
mixes the sample gas flowing in from the inflow portion with a dilution gas in an internal
space, to generate a diluted sample gas.
The discharge portion discharges the diluted sample gas.
10 The connection portion connects the inflow portion and the mixing portion, and has
a first tapered part whose inner diameter increases from a side connected to the inflow
portion toward a side connected to the mixing portion.
The introduction portion introduces the dilution gas into the internal space from a
position downstream of the connection between the first tapered part and the inflow portion.
15 [0013] The diluter described above has the structure in which the introduction portion
introduces the dilution gas from a position downstream of the connection between the first
tapered part and the inflow portion, and hence the dilution gas is introduced after the sample
gas containing the particulate matter is introduced into the internal space of the first tapered
part. In this way, the particulate matter can be uniformly dispersed in the internal space of the
20 mixing portion, and hence the particulate matter contained in the sample gas can be
uniformly diluted.
[0014] The introduction portion may introduce the dilution gas into the internal space in a
6
direction diagonal to an inflow direction of the sample gas into the internal space.
In this way, the particulate matter can be dispersed more uniformly in the internal
space of the mixing portion.
[0015] The introduction portion may introduce the dilution gas into the internal space in a
5 direction perpendicular to the inflow direction of the sample gas into the internal space.
In this way, the structure of the introduction portion can be simpler, while the
particulate matter can be uniformly dispersed in the internal space of the mixing portion.
[0016] The introduction portion may have a plurality of introduction ports arranged along
the inflow direction of the sample gas. In this case, it is preferred that one of the plurality of
10 introduction ports is disposed at a position point-symmetric to another one of the plurality of
introduction ports with respect to the center of a cross section of the mixing portion.
In this way, the dilution gas is introduced from a plurality of positions along the
inflow direction of the sample gas such that the sample gas and the dilution gas can be
uniformly mixed. In addition, the dilution gas introduced from one introduction port collides
15 with the dilution gas introduced from another introduction port that is point-symmetric to the
one introduction port, at the center and its vicinity of the cross section of the mixing portion,
such that the gas in the mixing portion can be prevented from contacting with an inner wall
surface of the mixing portion and that gas flow in the mixing portion can be stabilized. As a
result, the dispersion of the particulate matter in the mixing portion can be stabilized. Further,
20 as the contact of the gas in the mixing portion with the inner wall surface are reduced, a loss
of the particulate matter due to adhesion of the same to the inner wall surface can also be
suppressed.
7
[0017] The introduction portion may have a dilution gas filling space that is communicated
to the internal space of the mixing portion through the plurality of introduction ports and is
filled with the dilution gas.
In this way, the dilution gas can be uniformly introduced from the plurality of
5 introduction ports.
[0018] The introduction portion may be provided with a plurality of introduction tubes each
of which has one end connected to a position downstream of the connection between the first
tapered part and the inflow portion, and the other end that allows the dilution gas to flow in.
In this case, it is preferred that one of the plurality of introduction tubes is disposed at a
10 position point-symmetric to another one of the plurality of the plurality of introduction tubes
with respect to the center of a cross section of the first tapered part.
In this way, the dilution gas can be introduced after the sample gas containing the
particulate matter is introduced into the internal space of the first tapered part. In addition, the
dilution gas introduced from one introduction tube collides with the dilution gas introduced
15 from another introduction tube that is point-symmetric to the one introduction tube at the
center and its vicinity of the cross section of the first tapered part, such that the gas in the
mixing portion can be prevented from contacting with an inner wall surface of the mixing
portion and that gas flow in the mixing portion can be stabilized. As a result, dispersion of the
particulate matter in the mixing portion can be stabilized. Further, as the contact of the gas in
20 the mixing portion with the inner wall surface is reduced, a loss of the particulate matter due
to adhesion of the same to the inner wall surface can also be suppressed.
[0019] The mixing portion may include a second tapered part whose inner diameter
8
decreases from an upstream side to a downstream side, and a third tapered part whose inner
diameter increases from a side of the second tapered part toward the downstream side.
In this way, the particulate matter can be further dispersed in the internal space of the
mixing portion.
5 [0020] The diluter may further include a sampling portion configured to sample the diluted
sample gas from the internal space. In this way, the diluted sample gas can be sampled from
the internal space of the mixing portion.
[0021] The sampling portion may be disposed on the upstream side of the discharge portion.
In this way, it is possible to sample the diluted sample gas in which the particulate matter is
10 uniformly dispersed.
[0022] A ratio between a cross-sectional area of the sampling portion and that of the internal
space at a position where the sampling portion is disposed may be determined such that a
flow velocity of the diluted sample gas in the sampling portion is more than that in the
internal space.
15 In this way, a dispersed state of the particulate matter in a vicinity of the position
where the sampling portion is disposed can be substantially the same as that in the internal
space of the mixing portion.
[0023] The diluter described above may further include a vibration portion. The vibration
portion vibrates the mixing portion. In this way, the particulate matter, which is adhered to the
20 inside of a side wall of the mixing portion during dilution of the sample gas, can be removed.
[0024] The diluter described above may further include a heating portion. The heating
portion heats the mixing portion, the connection portion, and the introduction portion.
9
In this way, even if the sample gas includes volatile organic components and/or
moisture, the heating enables the components and/or moisture in the diluter to volatilize, thus
the condensation thereof can be suppressed.
[0025] An analysis system according to another aspect of the present invention includes a
5 diluter and an analyzing portion.
The diluter mixes a sample gas containing particulate matter with a dilution gas to
generate a diluted sample gas.
The analyzing unit analyzes the particulate matter contained in the diluted sample
gas.
10 In the analysis system described above, the diluter includes an inflow portion, a
mixing portion, a discharge portion, a connection portion, and an introduction portion.
The inflow portion allows the sample gas to flow in.
The mixing portion has an inner diameter larger than that of the inflow portion, and
mixes the sample gas flowing in from the inflow portion with a dilution gas in an internal
15 space to generate a diluted sample gas.
The discharge portion discharges the diluted sample gas.
The connection portion connects the inflow portion and the mixing portion, and has
a first tapered part whose inner diameter increases from a side connected to the inflow
portion toward a side connected to the mixing portion.
20 The introduction portion introduces the dilution gas into the internal space from a
position downstream of the connection between the first tapered part and the inflow portion.
[0026] The diluter provided to the analysis system described above has the structure in
10
which the introduction portion introduces the dilution gas from a position downstream of the
connection between the first tapered part and the inflow portion, and hence the dilution gas is
introduced after the sample gas containing the particulate matter is introduced into the
internal space of the first tapered part. In this way, the particulate matter can be uniformly
5 dispersed in the internal space of the mixing portion, and hence the particulate matter
contained in the sample gas can be uniformly diluted.
In addition, the analyzing portion analyzes the particulate matter contained in the
diluted sample gas in which the particulate matter contained in the sample gas at a high
concentration is diluted, and hence the particulate matter can be accurately analyzed.
10 [0027] The analysis system described above may include a collection unit. The collection
unit samples the diluted sample gas and collects the particulate matter contained in the
sampled diluted sample gas to a collection filter.
In this way, the particulate matter to be analyzed can be accurately analyzed in the
state collected by the collection filter.
15 [0028] The analyzing portion may include a collected amount measuring unit. The collected
amount measuring unit measures a collected amount of the particulate matter collected by the
collection filter.
In this way, it is possible to obtain accurate information about the collected amount
of the particulate matter collected by the collection filter.
20 [0029] The analyzing unit may include a component analyzing unit. The component
analyzing unit analyzes components contained in the particulate matter collected by the
collection filter.
11
In this way, accurate information about components contained in the particulate
matter collected by the collection filter can be obtained.
[0030] The analyzing unit may include a counting unit. The counting unit counts the
number of particulate matter (particulate number (PN)). In this way, accurate information
5 about particle number concentration of the particulate matter contained in the diluted sample
gas can be obtained.
[0031] The analyzing unit may include a diffusion charger sensor (DCS) that determines
mass concentration. In this way, the particle number concentration of the particulate matter
can be determined.
10 [0032] An analysis method according to still another aspect of the present invention is an
analysis method using an analysis system including a diluter and an analyzing unit. The
diluter includes an inflow portion, a mixing portion having an inner diameter larger than that
of the inflow portion, a discharge portion, a connection portion configured to connect the
inflow portion and the mixing portion and to have a first tapered part whose inner diameter
15 increases from a side connected to the inflow portion toward a side connected to the mixing
portion, an introduction portion configured to introduce a dilution gas from a position
downstream of the connection between the first tapered part and the inflow portion. The
analysis method includes:
mixing a sample gas containing particulate matter flowing in from the inflow portion
20 with the dilution gas introduced through the introduction portion, in the internal space of the
mixing portion, to generate a diluted sample gas; and
analyzing the particulate matter contained in the diluted sample gas using the
12
analyzing unit.
[0033] The diluter used in the analysis method described above has the structure in which
the introduction portion introduces the dilution gas from a position downstream of the
connection between the first tapered part and the inflow portion, and hence the dilution gas is
5 introduced after the sample gas containing the particulate matter is introduced into the
internal space of the first tapered part. In this way, the particulate matter can be uniformly
dispersed in the internal space of the mixing portion, and hence the particulate matter
contained in the sample gas can be uniformly diluted.
In addition, by analyzing the particulate matter contained in the diluted sample gas,
10 the particulate matter can be accurately analyzed.
ADVANTAGEOUS EFFECTS
[0034] As the dilution gas is introduced after the sample gas containing the particulate
matter is introduced into the internal space of the first tapered part, the particulate matter can
15 be uniformly dispersed in the internal space of the mixing portion. As a result, the particulate
matter contained in the sample gas can be uniformly diluted.
BRIEF DESCRIPTION OF DRAWINGS
[0035] Fig. 1 is a schematic diagram illustrating a structure of an analysis system.
20 Fig. 2 is a perspective view of a diluter according to a first embodiment.
Fig. 3 is a side view of the diluter according to the first embodiment.
Fig. 4 is a cross-sectional view in a length direction of the diluter according to the
13
first embodiment.
Fig. 5A is a cross-sectional view in a radial direction of the diluter, at a part where
introduction ports are disposed in a left and right direction, according to the first embodiment.
Fig. 5B is a cross-sectional view in the radial direction of the diluter, at a part where
5 the introduction ports are disposed in an up and down direction, according to the first
embodiment.
Fig. 6 is a diagram illustrating a simulation result of a dispersed state of the
particulate matter in the internal space of the mixing portion.
Fig. 7 is a diagram illustrating a specific structure of an analysis device.
10 Fig. 8 is a flowchart illustrating an analysis operation of the particulate matter in the
analysis system.
Fig. 9 is a diagram illustrating a structure of Example 1 of the analysis system.
Fig. 10 is a diagram illustrating a structure of Example 2 of the analysis system.
Fig. 11 is a cross-sectional view in the length direction of the diluter according to a
15 second embodiment.
Fig. 12 is a side view of the diluter according to a third embodiment.
Fig. 13 is a cross-sectional view at a connection part between a first tapered part and
an introduction portion of the diluter according to the third embodiment.
Fig. 14 is a diagram illustrating another example of the analysis system.
20
DESCRIPTION OF EMBODIMENTS
[0036] 1. First Embodiment
14
(1) Analysis System
Hereinafter, an analysis system 100 according to this embodiment is described. The
analysis system 100 is a system that can be used as a continuous emission monitoring system
(CEMS), which continuously analyzes particulate matter FP generated in various combustion
5 processes (such as a combustion process in a thermal power plant, an iron manufacturing
plant, or an incinerator, or a combustion process of coal). The particulate matter FP that can
be measured includes, for example, unburned matter in ash generated by the combustion
process of coal, and fly ash generated in various combustion processes.
[0037] In addition, without limiting to the particulate matter FP generated in combustion
10 processes, for example, dust generated from various transportation devices (such as
automobiles and ships) (dust from brakes, tires, internal combustion engines, steam engines,
exhaust gas purification devices, or motors) can be the particulate matter FP to be measured
by the analysis system 100. Further, dust (such as volcanic ash) generated by volcanic
eruption or other natural disaster, dust generated by mine development, and the like can also
15 be the particulate matter FP to be measured.
[0038] Hereinafter, with reference to Fig. 1, a structure of the analysis system 100 according
to the first embodiment is described. Fig. 1 is a schematic diagram illustrating a structure of
the analysis system. The analysis system 100 illustrated in Fig. 1 is a system configured to
analyze the particulate matter FP contained in an exhaust gas generated in the combustion
20 process, which is a gas to be measured (hereinafter referred to as a sample gas SG).
The analysis system 100 mainly includes a sampling probe 1, a diluter 3, and an
analysis device 5.
15
[0039] The sampling probe 1 is fixed at a predetermined position on a side wall of a flue FL,
to sample the sample gas SG from the flue FL in which the sample gas SG flows.
The sampling probe 1 samples from the flue FL the sample gas SG at a flow rate,
which is determined from a gas suction rate of a first pump P1 connected via the diluter 3, a
5 gas suction rate of a second pump P2 connected via the diluter 3 and the analysis device 5,
and a feed rate of a dilution gas AR (described later) to the diluter 3.
[0040] The diluter 3 is connected to the sampling probe 1 via a first gas line L1, and is
connected to a feeding device 7 that feeds the dilution gas AR via a second gas line L2. The
diluter 3 mixes the sample gas SG sampled by the sampling probe 1 with the dilution gas AR
10 fed from the feeding device 7 to generate a diluted sample gas DG. In other words, the diluter
3 generates the diluted sample gas DG in which concentration of the particulate matter FP is
reduced to less than that of the sample gas SG.
[0041] In this embodiment, the dilution gas AR is air. In this case, the feeding device 7 is a
device that adjusts flow rate of instrument air and feeds the same as the dilution gas AR, for
15 example. Other than that, the feeding device 7 may be a device that adjusts flow rate of
nitrogen or air supplied from a nitrogen cylinder or a (dried) air cylinder and feeds the same
as the dilution gas AR.
Other than that, for example, air in an atmospheric gas sucked by a pump may be fed
as the dilution gas AR after removing dust by a dust filter, removing moisture by a drying
20 treatment device, and adjusting flow rate thereof. In this way, even if the instrument air, the
cylinder, or the like cannot be used, for example, the dilution gas AR can be fed.
[0042] In addition, the diluter 3 is connected to the first pump P1 via a third gas line L3, and
16
is connected to the analysis device 5 via the fourth gas line L4. A part of the diluted sample
gas DG generated by the diluter 3 is sampled by the analysis device 5 via a fourth gas line L4,
and the other part of the diluted sample gas DG is sucked by the first pump P1 and is
discharged.
5 It should be noted that the analysis device 5 is connected to the second pump P2 via
a fifth gas line L5, to sample the diluted sample gas DG by a sucking force of the second
pump P2.
[0043] As illustrated in Fig. 1, the third gas line L3, in which the diluted sample gas DG
flows to be discharged, is connected to a first buffer tank BT1, a first flow rate adjuster FC1,
10 and a filter FI. The first buffer tank BT1 suppresses gas ripples in the third gas line L3. The
first flow rate adjuster FC1 adjusts flow rate of the diluted sample gas DG that is discharged.
The filter FI collects particles contained in the diluted sample gas DG, and minimizes the
particulate matter FP contained in the gas that is discharged outside.
It should be noted that if it is supposed that the sample gas SG and/or the dilution
15 gas AR contain a lot of moisture, a device such as a drain pot for eliminating moisture from
the gas may be provided to the third gas line L3.
[0044] In addition, the third gas line L3 is provided with a three-way valve V between the
filter FI and the first flow rate adjuster FC1. The three-way valve V is a valve that switches
connection and disconnection of gas between the first pump P1 and the diluter 3. It should be
20 noted that, when the three-way valve V disconnects between the first pump P1 and the diluter
3, it connects between the first pump P1 and the atmospheric gas.
While the dilution gas AR is fed from the feeding device 7, by disconnecting
17
between the first pump P1 and the diluter 3 by the three-way valve V, the dilution gas AR
from the diluter 3 passes through the first gas line L1 and is discharged from the sampling
probe 1 into the flue FL, so that the particulate matter FP accumulated and adhered to the
sampling probe 1 and the first gas line L1 can be removed and discharged into the flue FL
5 (blowback).
[0045] In addition, when the blowback described above is performed, the dilution gas AR
also passes through the fourth gas line L4 and flows to the analysis device 5, and hence the
particulate matter FP accumulated and adhered to the fourth gas line L4 can also be removed
simultaneously.
10 [0046] On the other hand, the fifth gas line L5 that connects the analysis device 5 and the
second pump P2 is connected to a second flow rate adjuster FC2 and a second buffer tank
BT2. The second flow rate adjuster FC2 adjusts flow rate of the diluted sample gas DG
sampled by the analysis device 5. The second buffer tank BT2 suppresses gas ripples in the
fifth gas line L5.
15 [0047] In this embodiment, the first gas line L1 that connects the sampling probe 1 and the
diluter 3, and the fourth gas line L4 that connects the diluter 3 and the analysis device 5 are
conductive gas lines, which are connected to a ground. In this way, it is possible to suppress
adhesion of the particulate matter FP contained in the sample gas SG and the diluted sample
gas DG to the first gas line L1 and the fourth gas line L4 until the particulate matter FP
20 reaches the analysis device 5.
As the conductive gas line that can be used as the first gas line L1 and the fourth gas
line L4, for example, there is a conductive tube made of rubber mixed with conductive
18
carbon.
[0048] The analysis device 5 is a device that analyzes the particulate matter FP contained in
the diluted sample gas DG sampled from the diluter 3. In this embodiment, the analysis
device 5 collects the particulate matter FP contained in the diluted sample gas DG to a
5 collection filter 51 (Fig. 7), measures collected amount (mass concentration) of the particulate
matter FP collected to the collection filter 51, and performs content analysis of the particulate
matter FP.
[0049] (2) Diluter
(2-1) Specific Structure of Diluter
10 Hereinafter, the diluter 3 is described in detail, which realizes a function of diluting
the particulate matter FP contained in the sample gas SG with the dilution gas AR in the
analysis system 100 described above. First, with reference to Figs. 2 to 5B, a specific
structure of the diluter 3 is described. Fig. 2 is a perspective view of the diluter according to
the first embodiment. Fig. 3 is a side view of the diluter according to the first embodiment.
15 Fig. 4 is a cross-sectional view in a length direction of the diluter according to the first
embodiment. Fig. 5A is a cross-sectional view of the diluter according to the first
embodiment, in a radial direction at a part where introduction ports are disposed in a left and
right direction. Fig. 5B is a cross-sectional view of the diluter according to the first
embodiment, in the radial direction at a part where the introduction ports are disposed in an
20 up and down direction