[Technical Field]
[0001]
The present invention relates to an elemental analysis device that analyzes
elements contained in a test sample based on a sample gas created by heating the test
5 sample.
[Technical Background]
[0002]
An elemental analysis device is used in order to quantify elements such as, for
10 example, nitrogen (N), hydrogen (H), and oxygen (O) and the like contained in a test
sample. In this type of elemental analysis device, a graphite crucible containing a test
sample is sandwiched inside a heating furnace between a pair of electrodes. Direct
current is then supplied to the crucible so that both the crucible and the test sample are
heated. A mixture gas made up of a sample gas generated by this heating and a carrier gas
15 is then passed through a dust filter so that dust such as soot and the like is filtered out.
Concentrations of various types of components contained in the filtered mixture gas are
then measured by an analysis mechanism in the form of an NDIR (Non-Dispersive
InfraRed) sensor or TCD (Thermal Conductivity Detector) or the like.
[0003]
20 In a case in which a dust filter formed, for example, from quartz wool or the like
has collected a predetermined quantity or more of dust such as soot or the like, then in
order to maintain the accuracy of the measurements made by the analysis mechanism it is
necessary to replace the dust filter. The frequency of replacing this type of dust filter is
often higher than what a user might hope for, so that there is a possibility that the time
25 and labor required for such maintenance will impose a considerable burden on a user.
3
[Documents of the Prior Art]
[Patent Documents]
[0004]
[Patent Document 1] Japanese Unexamined Patent Application (JP-A) No. 2010-32264
5 [Disclosure of the Invention]
[Problems to be Solved by the Invention]
[0005]
The present invention was conceived in view of the above-described problems,
and it is an object thereof to provide an elemental analysis device that enables the dust
10 filter replacement frequency to be reduced, and enables the time and labor required for
maintenance performed by a user to also be reduced.
[Means for Solving the Problem]
[0006]
In other words, an elemental analysis device according to the present invention
15 is characterized in being provided with a heating furnace in which a test sample that is
placed in a crucible is heated so that a sample gas is generated from the test sample, an
inflow path through which a carrier gas is introduced into the heating furnace, an outflow
path through which a mixture gas made up of the carrier gas and the sample gas is led out
from the heating furnace, a dust filter that is provided on the outflow path, an analysis
20 mechanism that is provided on the outflow path on a downstream side from the dust filter,
and that detects one or a plurality of predetermined components contained in the mixture
gas, and a cleaning gas supply mechanism that supplies cleaning gas to the dust filter in
an opposite direction from a direction in which the mixture gas is flowing.
[0007]
25 If this type of structure is employed, then dust such as soot and the like that has
4
collected in the dust filter is flushed out onto the heating furnace side by cleaning gas
supplied by the cleaning gas supply mechanism, so that the dust filter can be restored. As
a result, it is possible to reduce the frequency of maintenance such as replacement and
cleaning of the dust filter to less than what has conventionally been necessary.
5 [0008]
Moreover, because the cleaning gas is made to flow in reverse along the outflow
path from a position between the dust filter and the analysis mechanism on the outflow
path, dust such as soot and the like that has become detached from the dust filter does not
flow into the analysis mechanism. Accordingly, the accuracy of analyses performed by
10 the analysis mechanism can be maintained even when the dust filter is restored.
[0009]
In order to ensure that the cleaning gas flows in reverse along the outflow path
towards the dust filter, and to ensure that cleaning gas does not flow into the analysis
mechanism and that dust such as soot and the like that has become detached from the
15 dust filter does not reach the analysis mechanism, it is preferable that there be further
provided an exhaust flow path that branches off from between the dust filter and the
analysis mechanism on the outflow path, and through which the mixture gas that has
passed through the dust filter is exhausted, and that the cleaning gas supply mechanism
be provided with a flow path switching portion that is equipped with at least a switching
20 valve that is disposed on a branch point between the outflow path and the branch flow
path, and that switches flow paths in such a way that cleaning gas flows in an opposite
direction from a direction in which the mixture gas is flowing along the outflow path, and
a cleaning gas supply portion that supplies cleaning gas to the exhaust flow path or to the
switching valve.
25 [0010]
5
A specific aspect that is intended to cause the cleaning gas to flow in the
opposite direction from the mixture gas to the dust filter and to enable the dust filter to be
restored is a structure in which the cleaning
gas supply portion is provided with a cleaning gas supply source that blows out cleaning
gas at a predetermined pressure, and 5 a cleaning gas supply flow path that connects the
cleaning gas supply source to the exhaust flow path, and in which the flow path
switching portion is provided with a first 3-way valve which serves as the switching
valve, and a second 3-way valve that is disposed at a point of confluence of the exhaust
flow path and the cleaning gas supply flow path. If this type of structure is employed,
10 then because the second 3-way valve which is needed to form part of the cleaning gas
supply portion is disposed on the outflow path, the analysis accuracy can be maintained
without superfluous valves being installed unnecessarily on the outflow path, as is the
case in a conventional elemental analysis device. In other words, if valves other than the
first 3-way valve are additionally installed on the outflow path, then there is an increase
15 in the number of locations where the flow of mixture gas may become sluggish when
analysis is being performed, and there is a possibility that this will cause a deterioration
in the flow of gas to the analysis mechanism when analysis is being performed and may
lead to a reduction in the sensitivity and the like. Moreover, when cleaning gas is being
blown onto the dust filter so as to create a backwash, there is a possibility of components
20 of the cleaning gas remaining in the valves that are provided on the outflow path and of
these cleaning gas components being detected by the analysis mechanism together with
the mixture gas when the subsequent analysis is being performed, so that the accuracy of
the analysis may deteriorate. If the above-described second 3-way valve arrangement is
employed, then problems such as these can be prevented from occurring in the first place.
25 [0011]
6
Another aspect that enables any reduction in the analysis accuracy due to the
number of valves on the outflow path being increased to be avoided, while still enabling
the dust filter to be back-washed by cleaning gas is a structure in which the cleaning gas
supply portion is provided with a cleaning gas supply source that blows out cleaning gas
at a predetermined pressure, and a cleaning gas 5 supply flow path that is connected to the
cleaning gas supply source, and in which, as the switching valve, the flow path switching
portion is provided with a 4-way valve that switches flow paths in such a way that any
one of the analysis mechanism side of the outflow path, the exhaust flow path, or the
cleaning gas supply flow path is connected to the heating furnace side of the outflow
10 path.
[0012]
In order to enable dust such as soot and the like that has been collected by the
cleaning gas supplied by the cleaning gas supply mechanism to become detached and to
thereby enable the dust filter to be easily restored, and to consequently further reduce the
15 maintenance frequency, it is preferable that the dust filter be provided with a membrane
filter, and a filter holder that holds the membrane filter by sandwiching the membrane
filter in a thickness direction thereof. If this type of structure is employed, then in a case
in which the membrane filter can no longer be restored in a cleaning gas, the membrane
filter can simply be removed from the filter holder and replaced with a new membrane
20 filter. Accordingly, the time and labor required for the replacement operation can be
reduced compared to the conventional technology.
[0013]
In order to lighten the weight of the dust filter and enable the time and labor
required for the replacement operation to be reduced, it is preferable that the filter holder
25 be formed from resin or glass. In addition, if the filter holder is formed from transparent
7
resin or glass, then because it is possible, for example, to confirm visually how much
dust such as soot and the like has been collected on the membrane filter, it is easy to
determine the period when cleaning gas should be supplied. Because of this, the
frequency of supplying cleaning gas can be reduced to a minimum, and the time and
labor required for 5 the maintenance can be reduced.
[0014]
Instead of having to replace the dust filter, in order to enable it to be used
continuously by means of cleaning gas backwashing and to thereby enable the frequency
of performing maintenance to be reduced, it is preferable that the dust filter be provided
10 with a metal filter and a filter holder to which the metal filter is welded.
[0015] If a structure is employed in which the heating furnace includes a first electrode,
a second electrode that is formed so as to be able to move between a closed-furnace
position where it sandwiches the crucible between itself and the first electrode, and an
open-furnace position that is separated by a predetermined distance from the
15 closed-furnace position, a drive mechanism that causes the second electrode to move
between the closed-furnace position and the open-furnace position, a dust-suction flow
path that opens in the interior of the heating furnace and is equipped with a dust-suction
port that draws in dust, and an ejector that is equipped with an intake port that is
connected to the heating furnace side of the dust-suction flow path, a discharge port that
20 is connected to the discharge side of the dust-suction flow path, and a drive port to which
a working fluid is supplied, and in which the drive mechanism is formed in such a way
that, in a case in which the drive mechanism moves the second electrode from the
closed-furnace position to the open-furnace position, the working fluid flows into the
drive port of the ejector, then the ejector can be made to perform a suction action at the
25 same time as the second electrode is moved from the closed-furnace position to the
8
open-furnace position.
[0016]
Accordingly, dust that is generated in conjunction with the opening of the
heating furnace can be collected via the dust suction flow path from the dust suction port
inside the heating furnace as a consequence 5 of the suction action of the ejector.
[0017]
Moreover, because one characteristic of the ejector is that it is able to suction at
a flow rate that is several times greater than the flow rate of the working fluid that is
being supplied, an extremely high level of suction force can be applied to the interior of
10 the heating furnace so that the dust can be almost completely removed.
[0018]
In order to cause the drive mechanism to operate by means of the working fluid
that is used to make the ejector perform a suction action, and to thereby simplify the
structure of the overall device, it is preferable that the drive mechanism be a hydraulic
15 cylinder that is equipped with a first port through which the working fluid either flows in
or flows out, and is formed in such a way that, in a case in which the working fluid flows
in through the first port, a piston rod is drawn in so that the second electrode is moved to
the open-furnace position side, and is also formed in such a way that, in a case in which
the working fluid flows into the hydraulic cylinder through the first port, the working
20 fluid also flows into the ejector through the drive port.
[0019]
In a case in which the hydraulic cylinder is operated so that the second electrode
is moved to the open-furnace position side, in order to ensure that the working fluid is
supplied at the same time automatically to the ejector without the switching valve
25 needing to be controlled, and to also ensure that the operation to open the heating furnace
9
is performed in conjunction with the suction action performed by the ejector, it is
preferable that there be further provided a first supply line that connects a supply source
for the working fluid to the first port, and a drive line that branches off from the first
supply line and is connected to the drive port.
5 [0020]
In a case in which the second electrode has been moved to the closed-furnace
position, in order to ensure that the crucible can be sandwiched with sufficient strength
between the first electrode and the second electrode, it is preferable that the hydraulic
cylinder be equipped with a second port through which the working fluid either flows in
10 or flows out, and be formed in such a way that, in a case in which the working fluid
flows in through the second port, a piston rod is pushed out so that the second electrode
is moved to the closed-furnace position side.
[0021]
In order to ensure that the working fluid is easily prepared in an environment
15 such as that in which the elemental analysis device is used, and is also easily discarded in
this environment, and so as to also ensure that the suction force exerted by the ejector can
be made sufficiently large, it is preferable that the hydraulic cylinder be an air cylinder,
and that the working fluid be compressed air.
[0022]
20 An example of this type of structure is an elemental analysis device further
provided with a supporting body inside which is formed the dust suction flow path, and
that supports the second electrode, and in which the piston rod of the hydraulic cylinder
is connected to the supporting body.
[0023]
25 In order to ensure that dust can be suctioned evenly from inside the heating
10
furnace, it is preferable that the dust suction flow path be provided with a plurality of
dust suction ports that open onto a surface of the supporting body.
[0024]
An example of a structure that is specifically designed to clean dust adhering to
the first electrode or second electrode after the heating 5 furnace has been opened is a
structure that is further provided with a cleaning mechanism that is formed in such a way
that, in a case in which the second electrode is in the open-furnace position, the cleaning
mechanism moves between the first electrode and the second electrode and removes dust
from the first electrode or the second electrode, wherein the cleaning mechanism is also
10 formed in such a way that the dust removed from the first electrode of the second
electrode by the cleaning mechanism is collected from inside the heating furnace via the
dust suction flow path.
[0025]
In order to ensure that, in a case in which cleaning gas is supplied in order to
15 restore the dust filter, dust that is flowing into the heating furnace through this dust filter
is automatically collected, and the level of cleanliness of the heating furnace is
maintained, it is preferable that a structure be employed in which the heating furnace
includes a first electrode, a second electrode that is formed so as to be able to move
between a closed-furnace position where it sandwiches the crucible between itself and
20 the first electrode, and an open-furnace position that is separated by a predetermined
distance from the closed-furnace position, a drive mechanism that causes the second
electrode to move between the closed-furnace position and the open-furnace position, a
dust-suction flow path that opens in the heating interior of the furnace and is equipped
with a dust-suction port that draws in dust, and an ejector that is equipped with an intake
25 port that is connected to the heating furnace side of the dust-suction flow path, a
11
discharge port that is connected to the discharge side of the dust-suction flow path, and a
drive port to which a working fluid is supplied, and in which the cleaning gas supply
mechanism is formed in such a way that, in a case in which the cleaning gas is flowing to
the dust filter in an opposite direction from a direction in which the mixture gas is
5 flowing, the working fluid flows into the drive port of the ejector.
[Effects of the Invention]
[0026]
As is described above, if an elemental analysis device according to the present
invention is employed, then it is possible to cause dust such as soot and the like that has
10 been collected as a result of cleaning gas being supplied by the cleaning gas supply
mechanism during an analysis to the dust filter in the opposite direction from the
direction in which the mixture gas is being supplied to flow into the heating furnace.
Because of this, it is possible to restore the dust filter and reduce the dust filter
replacement frequency, and to ensure that dust such as soot and the like that has become
15 detached from the dust filter while the dust filter is being restored does not reach the
analysis mechanism so that the analysis accuracy can be maintained.
[Brief Description of the Drawings]
[0027]
[FIG. 1] FIG. 1 is a schematic view showing an overall structure of an elemental
20 analysis device according to an embodiment of the present invention.
[FIG. 2] FIG. 2 is a schematic view showing a heating furnace and peripheral
structure around this heating furnace according to the same embodiment.
[FIG. 3] FIG. 3 is a schematic perspective view showing a peripheral structure
around a lower portion electrode (i.e., a second electrode) according to the same
25 embodiment.
12
[FIG. 4] FIG. 4 is a schematic cross-sectional view showing a structure of an
ejector according to the same embodiment.
[FIG. 5] FIG. 5 is a schematic view showing an enlargement of a periphery of a
cleaning gas supply mechanism at a time when gas is being exhausted according to the
5 same embodiment.
[FIG. 6] FIG. 6 is a schematic view showing an enlargement of the periphery of
the cleaning gas supply mechanism at a time when measurements are being made
according to the same embodiment.
[FIG. 7] FIG. 7 is a schematic view showing an enlargement of the periphery of
10 the cleaning gas supply mechanism at a time when analysis is being performed according
to the same embodiment.
[FIG. 8] FIG. 8 is a schematic perspective view showing a structure of a dust
filter according to the same embodiment.
[FIG. 9] FIG. 9 is a schematic cross-sectional view showing a variant example
15 of a dust filter.
[FIG. 10] FIG. 10 is a schematic cross-sectional view showing another variant
example of a dust filter.
[FIG. 11] FIG. 11 is a schematic view showing an enlargement of a periphery of
a cleaning gas supply mechanism according to another embodiment of the present
20 invention.
[FIG. 12] FIG. 12 is a schematic view showing a heating furnace and peripheral
structure around this heating furnace according to yet another embodiment of the present
invention.
25 [Description of the Reference Numerals]
13
[0028]
100 … Elemental Analysis Device
1 … Supply Source
2 … Purifier
5 3 … Heating Furnace
31 … Upper Portion Electrode (First Electrode)
32 … Lower Portion Electrode (Second Electrode)
33 … Supporting Body
34 … Air Cylinder
10 35 … Piston Rod
36 … Cylinder
37 … Ejector
DL … Dust Suction Flow Path
DP … Dust Suction Port
15 4 … Dust Filter
41 … Membrane Filter, Metal Filter, Metal Mesh Filter
42 … Filter Holder
5 … CO Detection Portion
6 … Oxidizer
20 7 … CO2 Detection Portion
8 … H2O Detection Portion
9 … Removal Mechanism
10 … Mass Flow Controller
11 … N2 Detection Portion (Thermal Conductivity Analysis Portion)
25 R … Cleaning Gas Supply Mechanism
14
RS … Cleaning Gas Supply Portion
RC … Flow Path Switching Portion
R1 … Cleaning Gas Supply Source
R2 … Cleaning Gas Supply Flow Path
5 R3 … First 3-Way Valve
R4 … Second 3-Way Valve
[Best Embodiments for Implementing the Invention]
10 [0029]
An elemental analysis device 100 according to an embodiment of the present
invention will now be described with reference to the respective drawings. An outline of
the elemental analysis device 100 of the present embodiment is shown in FIG. 1. The
elemental analysis device 100 applies heat to, for example, a metal test sample or a
15 ceramic test sample or the like (hereinafter, referred to simply as a test sample) that is
contained in a graphite crucible MP so as to melt this test sample, and then analyzes
sample gases that are generated at this time so as to measure quantities of elements that
are contained in the test sample. In the first embodiment, the elements being measured
are O (oxygen), H (hydrogen), and N (nitrogen) that are contained in the test sample.
20 [0030]
More specifically, as is shown in FIG. 1, the elemental analysis device 100 is
provided with a heating furnace 3 in which the test sample contained in the crucible MP
is heated, an inflow path L1 through which a carrier gas is introduced into the heating
furnace 3, and a outflow path L2 through which a mixture gas made up of a carrier gas
25 and a sample gas is led out from the heating furnace 3. More specifically, the elemental
15
analysis device 100 is formed by the heating furnace 3, various devices that are provided
on the inflow path L1 and the outflow path L2, and a control and calculation mechanism
COM that controls the various instruments and governs calculation processing for the
concentrations and the like that have been measured. The control and calculation
mechanism COM is, for example, a computer 5 having a CPU, memory, A/D converters,
D/A converters, and various types of input and output devices. As a result of programs
stored in the memory being executed and the various instruments operating in mutual
collaboration with each other, the control and calculation mechanism COM is able to
perform functions of a measurement value calculation portion C1 and a mode setter C2
10 (described below). In addition, the control and calculation mechanism COM also
performs functions of a display portion (not shown in the drawings) that displays
concentrations of various types of elements contained in a test sample based on outputs
from, for example, a CO detection portion, 5, a CO2 detection portion 7, an H2O
detection portion 8, and an N2 detection portion 11 (these are described below in detail).
15 [0031]
Each portion will now be described in detail.
[0032]
A gas canister, which is serving as a carrier gas supply source 1, is connected to
a base end of the inflow path 1. In the first embodiment, He (helium) is supplied from the
20 supply source 1 to the inside of the inflow path L1. In addition, a purifier 2 that removes
minute quantities of hydrocarbons contained in the carrier gas so as to raise the purity
thereof is provided on the inflow path L1.
[0033]
The purifier 2 is formed from a material whose characteristics include an ability
25 to cause hydrocarbons contained in the carrier gas to physically adhere thereto, while
16
essentially preventing the carrier gas itself from adhering thereto. Note that the material
forming the purifier 2 does not react chemically either with the carrier gas or with the
hydrocarbons. In other words, the purifier 2 is also used, for example, in gas
chromatography, and, for example, a zeolite-based molecular sieve or the like may be
used as the material forming the purifier 2. Additionally, 5 it is also possible for silica gel,
activated carbon, or Ascarite or the like to be used as the material forming the purifier 2.
[0034]
The heating furnace 3 is formed so as to sandwich the graphite crucible MP
containing a test sample between a pair of electrodes in the form of a first electrode and a
10 second electrode, and to then supply direct current to the crucible MP so as to heat both
the crucible MP and the test sample contained therein. More specifically, as is shown in
FIG. 2 and the like, the heating furnace 3 is provided with an upper portion electrode 31,
which is a circular-cylinder shaped first electrode in which an internal space is formed,
and a lower portion electrode 32, which is a circular-column shaped second electrode that
15 is inserted into the internal space and that sandwiches the crucible MP between itself and
the upper portion electrode 31.
[0035]
A through-hole extending in an up-down direction that is used to supply carrier
gas supplied from the inflow path L1 into the internal space is formed in the upper
20 portion electrode 31. In addition, a mixture gas that is formed by a sample gas created
from the test sample and the carrier gas flows via a through-hole formed in a side surface
of the upper portion electrode 31 into the outflow path L2.
[0036]
Furthermore, as is shown in FIG. 2, the lower portion electrode 32 is formed so
25 as to be advanced and withdrawn in an up-down direction by an air cylinder 34, which is
17
a linear-motion hydraulic cylinder. In other words, more specifically, in a case in which a
test sample is heated inside the crucible MP, the lower portion electrode 32 is moved
upwards by the air cylinder 34, and is inserted into the internal space in the upper portion
electrode 31. In this state, the crucible MP is sandwiched between the upper portion
electrode 31 and the lower portion electrode 5 32. Moreover, the lower portion electrode 32
seals off a lower-side aperture in the upper portion electrode 31 with an airtight seal by
means of a sealing portion that is provided on a side surface thereof so as to protrude
outwards in a circumferential direction. As a result, the mixture gas that is formed by
mixing together the sample gas generated as a result of the test sample being heated and
10 the carrier gas flows from the side-surface side of the upper portion electrode 31 into the
outflow path L2.
[0037]
In other words, the lower portion electrode 32 is formed so as to be able to move
between a closed-furnace position where, as is shown in FIG. 2 (a), it sandwiches the
15 crucible between itself and the upper portion electrode 31, and an open-furnace position
which, as is shown in FIG. 2 (b), is separated by a predetermined distance from the
closed-furnace position. In the present embodiment, the closed-furnace position is
located below the open-furnace position. In the closed-furnace position, a door (not
shown in the drawings) in the heating furnace 3 is closed so that the sample gas
20 generated inside the heating furnace 3 does not leak out to the outside. In contrast, in the
open-furnace position, the door (not shown in the drawings) is opened so that
replacement of the crucible MP, or internal cleaning and maintenance of the heating
furnace 3 can be performed. In other words, in a case in which the dust filter 4 (described
below) is to be cleaned, or the test sample is to be replaced, the lower portion electrode
25 32 is moved downwards by the air cylinder 34 and is placed on the outside of the internal
18
space in the upper electrode 31.
[0038]
In a state in which the heating furnace 3 has been opened in this way, the
internal space inside the heating furnace 3 is in communication with a suction source P of
a cleaning mechanism or the like. In 5 this structure, when the lower portion electrode 32
moves to the open-furnace position and the heating furnace 3 is opened up, the interior of
the heating furnace 3 is automatically suctioned so that any dust such as soot and the like
that is adhering to the upper portion electrode 31 and the lower portion electrode 32 and
the like is collected.
10 [0039]
Hereinafter, structure relating to a suction operation in the heating furnace 3 will
be described in detail.
[0040]
The lower portion electrode 32 is supported by a supporting body 33 having a
15 bottom surface portion that is formed having a flat, rectangular parallelepiped shaped
outline. A piston rod 35 of the air cylinder 34 is connected to an outer side of this
supporting body 33, and the lower portion electrode 32 is moved between the
closed-furnace position and the open-furnace position as a result of the supporting body
33 being moved in an up-down direction by the air cylinder 34.
20 [0041]
A first port SP1 and a second port SP2 through which a working fluid in the
form of compressed air is able to flow in or flow out are formed in a side surface of a
cylinder 36 of the air cylinder 34. In a case in which compressed air is flowing in through
the first port SP1, the piston rod 35 is drawn back into the cylinder 36. In a case in which
25 compressed air is flowing in through the second port SP2, the piston rod 35 is pushed to
19
the outside of the cylinder 36. In other words, within the cylinder 36, a first chamber that
communicates with the first port SP1 and a second chamber that communicates with the
second port SP2 are mutually demarcated by the piston rod 35. The distance that the
piston rod 35 is pushed out from the cylinder 36 is controlled by altering the pressure
differential between the first chamber 5 and the second chamber using this inflow and
outflow of compressed air. In the present embodiment, a supply source for the
compressed air and the first port SP1 are connected together by a first supply line SL1,
while this supply source and the second port SP2 are connected together by a second
supply line SL2. Control such as determining whether to supply compressed air from the
10 supply source to the first port SP1 or to the second port SP2, as well as the quantity of
compressed air to be supplied is performed by a compressed air control mechanism
provided in the supply source. Note that this compressed air control mechanism is
formed so as to perform operations that are prescribed in advance, for example, in
accordance with a furnace-opening command or a furnace-closing command for the
15 heating furnace 3 that is input from a mode setter C2.
[0042]
Moreover, as is shown in FIG. 3, a plurality of dust suction ports DP through
which dust is suctioned are provided in a furnace-interior side surface of the bottom
surface portion of the supporting body 33. More specifically, the lower portion electrode
20 32 is supported in the center of the bottom surface portion of the supporting body 33, and
the respective dust suction ports DP are formed in each of the four corners thereof. In
addition, as is shown in FIG. 2, a dust suction flow path DL that is equipped with the
above-described dust suction ports DP is formed in an interior portion of the supporting
body 3.
25 [0043]
20
In the present embodiment, an ejector 37 is provided on the dust suction flow
path DL that is formed within the supporting body 33 so that the inner portion side of the
heating furnace 3 and an intake port VP are connected together. In addition, a drive port
AP of the ejector 37 and the first supply line SL1 are connected together by a drive line
AL that branches off from the first supply 5 line SL1. In other words, a structure is
employed in which, when compressed air is supplied from the compressed air supply
source to the first port SP1 of the air cylinder 34, then in parallel with this, compressed
air is also supplied to the drive port AP of the ejector 37. In addition, a discharge port EP
of the ejector 37 is connected to an exhaust side of the dust suction flow path DL where,
10 for example, a dust box or the like is located.
[0044]
A more detailed description of the ejector 37 of the present embodiment will
now be given. As is shown in FIG. 4, the ejector 37 is formed having a circular-cylinder
shaped configuration having the intake port VP formed at one end surface thereof, and
15 the discharge port EP formed at another end surface thereof. Moreover, the drive port AP
through which compressed air, which is serving as a working fluid, is able to flow in is
formed in a side surface of the ejector 37. The drive port AP communicates with a nozzle
(not shown in the drawings) that is formed in an internal portion of the ejector 37 and, as
is shown in FIG. 4 (a), gas is suctioned through the intake port VP by the air
20 decompression that is generated as a result of the compressed air passing through the
nozzle. In addition, the compressed air flowing in through the drive port AP and the gas
taken in through the intake port VP are discharged to the outside through the discharge
port EP in a state of being mixed together. Here, the flow rate of the mixture gas
discharged through the discharge port EP is, for example, approximately 3~4 times the
25 flow rate of the compressed air flowing in through the drive port AP. In other words, the
21
flow rate of the gas taken in through the intake port VP is approximately 2~3 times the
flow rate of the compressed air flowing in through the drive port AP. In this way, by
causing compressed air to flow in through the drive port AP, the ejector 37 is able to
generate suction force in the intake port VP, and cause dust to be suctioned from inside
5 the heating furnace 3 through the dust suction ports DP.
[0045]
Next, a description will be given of each of the devices provided on the outflow
path L2.
[0046]
10 As is shown in FIG. 1, the dust filter 4 through which the mixture gas led out
from the heating furnace 3 flows in, and an analysis mechanism AM that detects either
one or a plurality of predetermined components contained in the mixture gas passing
through the dust filter 4 are provided on the outflow path L2. In the present embodiment,
the analysis mechanism AM includes a CO detection portion 5, an oxidizer 6, a CO2
15 detection portion 7, an H2O detection portion 8, a removal mechanism 9, a mass flow
controller 10, and an N2 detection portion 11 which is serving as a thermal conductivity
analysis portion. These devices are each arranged on the outflow path L2 in the above
sequence from the upstream side. In addition, a cleaning gas supply mechanism R that
supplies cleaning gas to the dust filter 4 in the opposite direction from the direction in
20 which the mixture gas is flowing is also provided on the outflow path L2. The cleaning
gas supply mechanism R is formed so as to supply cleaning gas to the dust filter 4 via an
exhaust flow path L3 that branches off from a point between the dust filter 4 and the CO
detection portion 5 which is located furthest to the upstream side in the analysis
mechanism AM.
25 [0047]
22
Each of the aforementioned portions will now be described in detail.
[0048]
The dust filter 4 filters out and removes dust such as soot and the like that is
contained in the mixture gas. As is shown in FIG. 8, the dust filter 4 is provided with a
membrane filter 41 made, for example, from 5 PTFE or the like, and with a filter holder 42
that holds the membrane filter 41 by sandwiching it in the thickness direction thereof.
The filter holder 42 is formed as a flange fitting on the outflow path L2, and is formed by
an upstream-side holder 4A and a downstream-side holder 4B that are each formed
having a substantially circular-disk shaped configuration. A mesh sheet screen 4C is
10 formed in a central portion of the downstream-side holder 4B, and the membrane filter
41 is placed on this sheet screen 4C so as to be sandwiched between the sheet screen 4C
and the upstream-side holder 4A. Note that the upstream-side holder 4A and the
downstream-side holder 4B are fastened together via their respective outer
circumferential portions by means of nuts and bolts (not shown in the drawings). The
15 filter holder 42 is formed from a transparent resin such as, for example, an acrylic resin
or the like so that it is possible to observe the state of the membrane filter 41 from the
outer side of the filter holder 42.
[0049]
As is shown in FIG. 5 through FIG. 7, the cleaning gas supply mechanism R is
20 formed so as to blow opposing jets of cleaning gas at a predetermined pressure or greater
onto the dust filter 4 from the exhaust flow path L3 that branches off from a point on the
outflow path L2 between the dust filter 4 and the CO detection portion 5. In other words,
the cleaning gas supply mechanism R is provided with a cleaning gas supply portion RS
that supplies cleaning gas to the exhaust flow path L3, and with a flow path switching
25 portion RC that is formed by two switching valves. This flow path switching portion RC
23
is controlled, for example, by the mode setter C2, and the points to which the respective
switching valves are connected are altered in accordance with the mode that has been set.
[0050]
The cleaning gas supply portion RS is provided with a cleaning gas supply
source R1 that blows jets of, for example, an 5 inert gas as the cleaning gas at a
predetermined pressure, and with a cleaning gas supply flow path R2 that connects the
cleaning gas supply source R1 and the exhaust flow path L3 together. The cleaning gas
supply flow path R2 is provided so as to merge with the exhaust flow path on the
upstream side from a capillary that is provided on the downstream-end side thereof. Here,
10 it is preferable that the inert gas blown from the inert gas supply source R1 is not able to
be detected by the analysis mechanism AM and, for example, He, which is also used as
the carrier gas in the present embodiment, may be used. If this type of cleaning gas is
used, then even if residual cleaning gas components remain in the dust filter 4 or the first
3-way valve R3 (described below) on the outflow path L2, it is difficult for these to have
15 any effect on the accuracy of the analysis. Note that, depending on the desired analysis
accuracy or on the type of element being measured, it may also be possible for Ar or N2,
which are different components from the carrier gas, to be used as the inert gas.
[0051]
The flow path switching portion RC is provided with a first 3-way valve R3 that
20 is provided at the branching point where the exhaust flow path L3 branches off from the
outflow path L2, and with a second 3-way valve R4 that is provided at the merging point
where the exhaust gas supply flow path R2 merges with the exhaust flow path. As is
shown in FIG. 2 through FIG. 4, by switching the states of the first 3-way valve R3 and
the second 3-way valve R4, it is possible to alter the type of gas that is flowing and also
25 the direction in which the gas is flowing. In other words, by switching the flow path
24
switching portion RC, any of an exhaust mode shown in FIG. 5, an analysis mode shown
in FIG. 6, or a cleaning mode shown in FIG. 7 can be set.
[0052]
In the exhaust mode shown in FIG. 5, the first 3-way valve R3 places the
outflow path L2 and the exhaust flow 5 path L3 in mutual communication with each other
and also closes off the analysis mechanism AM side of the outflow path L2, and the
second 3-way valve R4 closes the cleaning gas supply flow path R2. As a result, mixture
gas that is led out from the heating furnace 3 is exhausted via the exhaust flow path L3
without passing through the analysis mechanism AM. The exhaust mode is employed in
10 order to enable heat to be applied to the crucible MP without a test sample having been
placed therein, so that any impurities contained in the crucible MP are vaporized and
exhausted to the outside via the exhaust flow path L3 without entering the analysis
mechanism AM.
[0053]
15 In the analysis mode shown in FIG. 6, the first 3-way valve R3 closes the
exhaust flow path L3, and allows mixture gas to flow into the analysis mechanism AM.
The analysis mechanism AM measures the concentrations of various components in the
inflowing mixture gas.
[0054]
20 In the cleaning mode shown in FIG. 7, the first 3-way valve R3 places the
outflow path L2 and the exhaust flow path L3 in mutual communication with each other
and closes off the analysis mechanism AM side of the outflow path L2. Moreover, the
second 3-way valve R4 places the exhaust flow path L3 and the cleaning gas supply flow
path R2 in mutual communication with each other and closes off the exit-side of the
25 exhaust flow path L3. In addition, in the heating furnace 3, the lower portion electrode 32
25
is lowered downwards, and cleaning gas that has been blown from the cleaning gas
supply source R1 flows in reverse through the dust filter 4, and thereafter a flow path is
formed extending from inside the heating furnace 3 to a suction source P. If cleaning gas
is supplied to the dust filter 4 in this cleaning mode, then dust such as soot and the like
that has collected on the upstream-side surface 5 of the membrane filter 41 in the dust filter
4 is made to flow into the heating furnace 3. The cleaning gas and dust that have flowed
into the heating furnace 3 are then suctioned out by the suction source P so that a state of
cleanliness is maintained within the heating furnace 3.
[0055]
10 Next, the analysis mechanism AM will be described in detail with reference to
FIG. 1.
[0056]
The CO detection portion 5 detects CO (carbon monoxide) contained in the
mixture gas passing through the dust filter 4 and measures the concentration of this CO,
15 and is formed by an NDIR (non-dispersive infrared gas analyzer). From the standpoint of
measurement accuracy, this CO detection portion 5 operates most effectively in cases in
which there is a high concentration of oxygen contained in the test sample. More
specifically, it is preferable that a concentration of not less than 150 ppm of CO be
measured.
20 [0057]
The oxidizer 6 oxidizes CO and CO2 contained in the mixture gas that has
passed through the CO detection portion 5, and also generates water vapor by oxidizing
H2 into H2O (i.e., water). In the first embodiment, copper oxide is used as the oxidizer 6,
and the temperature of the oxidizer is held to a temperature of not more than 450C by a
25 heat element provided around the oxidizer.
26
[0058]
The CO2 detection portion 7 is an NDIR that detects CO2 in the mixture gas that
has passed through the oxidizer 6, and measures the concentration thereof. From the
standpoint of measurement accuracy, this CO2 detection portion 7 operates most
effectively in cases in which there is 5 a low concentration of oxygen contained in the test
sample (for example, less than 150 ppm).
[0059]
The H2O detection portion 8 is an NDIR that detects H2O in the mixture gas that
has passed through the CO2 detection portion 7, and measures the concentration thereof.
10 Note that the flow path from the oxidizer 6 to the H2O detection portion 8 is formed in
such a way that the temperature of the mixture gas is held at 100C or more, and such
that the H2O is maintained in a water vapor state. In this way, measurement errors caused
by condensation are prevented from occurring in the H2O detection portion 8.
[0060]
15 The removal mechanism 9 employs adhesion to remove CO2 and H2O contained
in the mixture gas. The removal mechanism 9 is formed by an adhesive agent and, for
example, the same material as that used for the above-described purifier 2 provided on
the inflow path L1 may be used. Accordingly, for example, a zeolite-based molecular
sieve may be used as the adhesive agent forming the removal mechanism 9. Additionally,
20 it is also possible for silica gel, activated carbon, or Ascarite or the like to be used as the
material forming the removal mechanism 9.
[0061]
The mass flow controller 10 is a flow rate control device in which a flow rate
sensor, a control valve, and a flow rate controller (none of these are shown in the
25 drawings) have been packaged into a single device. This mass flow controller 10 supplies
27
mixture gas at a constantly maintained set flow rate to the N2 detection portion 11 located
on the downstream side thereof.
[0062]
The N2 detection portion 11 is a TCD (thermal conductivity detector) that
measures changes in the thermal conductivity 5 of the mixture gas, and also measures the
concentration of N2, which is a predetermined component contained in the mixture gas,
from the flow rate of the mixture gas being supplied. In other words, because the mixture
gas supplied to the N2 detection portion 11 is substantially formed solely by a carrier gas
and N2, the concentration of the N2 contained in the mixture gas is a value that
10 corresponds to changes in the thermal conductivity. Moreover, in the first embodiment,
no flow rate meter is provided on the downstream side from the N2 detection portion 11,
and the downstream side of the N2 detection portion 11 is directly connected to the
exhaust port of the outflow path L2.
[0063]
15 An analysis flow of the elemental analysis device 100 that is formed in the
above-described manner will now be described with reference to FIG. 1.
[0064]
Direct current is supplied to the crucible MP containing a test sample inside the
heating furnace 3 so as to heat the crucible MP by means of energization. While this
20 heating is being performed, carrier gas is continuously supplied from the inflow path L1
in such a way as to ensure that the differential pressure within the heating furnace 3 is
raised not more than 60 kPa relative to the atmospheric pressure and is maintained at this
pressure. The sample gas that is generated by thermal decomposition and reduction inside
the heating furnace 3 is led out by the carrier gas to the outflow path L2.
25 [0065]
28
A mixture gas made up of the sample gas and the carrier gas led out from the
heating furnace 3 passes through the dust filter 4, and is then guided to the CO detection
portion 5. Here, the components that may possibly be contained in the sample gas guided
to the CO detection portion 5 are CO, H2, and N2. The concentration of CO is measured
5 in the CO detection portion 5.
[0066]
Next, the mixture gas that has passed through the CO detection portion 5 is
guided to the oxidizer 6. Here, CO contained in the mixture gas is oxidized to CO2, and
the H2 is oxidized to H20. Accordingly, the components that may possibly be contained in
10 the sample gas that has passed through the oxidizer 6 are CO2, H2O, and N2.
[0067]
The mixture gas that has passed through the oxidizer 6 is guided to the CO2
detection portion 7. The concentration of CO2 contained in the mixture gas is then
measured by the CO2 detection portion 7.
15 [0068]
The mixture gas that has passed through the CO2 detection portion 7 is guided to
the H2O detection portion 8, and the concentration of H2O contained in the mixture gas is
then measured.
[0069]
20 The mixture gas that has passed through the H2O detection portion 8 is guided to
the removal mechanism 9. In the removal mechanism 9, because CO2 and H2O are
removed by adhesion, the only component that may possibly be contained in the sample
gas that has passed through the removal mechanism 9 is N2.
[0070]
25 The mixture gas that has passed through the removal mechanism 9 is guided,
29
while being held at a constantly maintained set flow rate, to the N2 detection portion 11
by the mass flow controller 10. In the N2 detection portion 11, the concentration of N2 is
measured.
[0071]
Measurement signals showing the concentrations 5 of the respective components
obtained by the respective detection portions are input into the measurement value
calculation portion C1. Based on the respective measurement signals, the measurement
value calculation portion C1 calculates the concentrations of O, H, and N contained in
the test sample. Note that when the measurement value calculation portion C1 is
10 calculating the concentration of oxygen contained in the test sample, in a case in which
the oxygen concentration within the test sample is equal to or greater than a
predetermined threshold value (150 ppm), then the oxygen concentration obtained by the
CO detection portion 5 is set as the output value, while in a case in which the oxygen
concentration within the test sample is less than a threshold value, then the oxygen
15 concentration obtained by the CO2 detection portion 7 is set as the output value.
[0072]
According to the elemental analysis device 100 that is formed in the
above-described manner, because, as a result of the cleaning mode being executed,
cleaning gas is blown onto the dust filter 4 by the cleaning gas supply mechanism R in
20 the opposite direction from the direction in which the mixture gas flows when the device
is in analysis mode, it is possible to desorb collected dust such as soot and the like and
restore the functioning of the dust filter without having to remove the membrane filter 41
from the filter holder 42. Because of this, it is possible to greatly increase the number of
times elemental analysis can be performed without the membrane filter 41 having to be
25 replaced, and to thereby reduce frequency of performing maintenance as well as the time
30
and labor required for such maintenance.
[0073]
Moreover, because the dust filter 4 uses the membrane filter 41, dust such as
soot and the like is deposited almost entirely solely on the heating furnace 3-side surface
of the membrane filter 41. Accordingly, 5 by supplying cleaning gas towards the heating
furnace 3 side of the membrane filter 41, any collected dust such as soot and the like is
substantially prevented from flowing onto the analysis mechanism AM side thereof, and
is instead returned to the heating furnace 3 side where it is recovered by the suction
source P. As a result, this cleaning mode enables the analysis accuracy of the analysis
10 mechanism AM to be maintained even when the membrane filter has been restored.
[0074]
Furthermore, by employing this membrane filter 41, compared to a case in
which quartz wool or the like is used as a filter, it is difficult for any dust or any of the
material forming the filter itself to flow onto the analysis mechanism AM side. In
15 addition, even in cases when repeated analyses are performed so that there such a
reduction in the performance of the membrane filter 41 that the membrane filter 41
cannot be restored by implementing the cleaning mode, the membrane filter can be
replaced easily by simply inserting and sandwiching a new membrane filter in the filter
holder 42. Because of this, it is easy to prevent dust such as soot and the like from
20 leaking onto the analysis device side due to poor maintenance.
[0075]
Furthermore, as is shown in FIG. 2 (b), if compressed air is supplied to the first
port SP1 of the air cylinder 34 in order to move the lower portion electrode 32 to the
open-furnace position, then compressed air is also supplied to the drive port AP of the
25 ejector 37 as well. Accordingly, without operating separate cleaning devices and the like,
31
it is possible to suction dust from inside the heating furnace 3 via the dust suction ports
DP at the same time as the heating furnace 3 is being opened. Accordingly, it is possible
to prevent the interior of the heating furnace 3 from being contaminated by dust as a
result of this opening operation.
5 [0076]
Moreover, simply by providing the ejector 37 on the dust suction flow path DL,
and connecting the first supply line SL1, which causes the air cylinder 34 to operate, to
the drive port AP of the ejector 37 by means of the drive line AL, it is possible to suction
the interior of the heating furnace 3 in conjunction with the operation to open the heating
10 furnace 3. Accordingly, there is no need to employ a high-level controller in order to link
the opening and closing operations with the suctioning of the interior of the heating
furnace 3. Moreover, because it is possible to use a common motive power source to
operate both the air cylinder 34 and the ejector 37, any dust within the heating furnace 3
can be collected using a simple structure.
15 [0077]
In addition, even without increasing the flow rate of the compressed air supplied
to the drive port AP to any considerable degree, because the ejector 37 is used it is still
possible to achieve sufficient suction force to suction out dust from inside the heating
furnace 3.
20 [0078]
Additional embodiments of the present invention will now be described.
[0079]
The dust filter that is employed is not restricted to being a membrane filter. For
example, a membranous filter made from a material other than resin, or a filter created by
25 filling a vessel with quartz wool may also be used. Even if filters such as these are used,
32
dust collected by the cleaning gas supply mechanism can still be desorbed and the
functioning of the filter can be restored, so that the frequency of performing maintenance,
as well as the time and labor required for such maintenance, can be reduced.
[0080]
Moreover, it is also possible to 5 provide a vibrator that imparts a vibration to the
dust filter, and to then cause the dust filter to vibrate when the dust filter is in cleaning
mode. In other words, cleaning gas can be supplied to the dust filter after the dust filter
has been made to vibrate so as to make it easier for the dust to be desorbed.
[0081]
10 The filter holder that is used to hold the membrane filter is not restricted to the
object described in the foregoing embodiment. For example, it is also possible for the
filter holder to be made out of metal. More specifically, as is shown in FIG. 9, it is also
possible for a metal filter 41 to be used in the dust filter 4. In other words, the dust filter 4
may be formed by sandwiching an outer circumferential portion of a thin, circular-plate
15 shaped metal filter 41 between an upstream-side holder 4A and a downstream-side holder
4B that are each formed from metal so as to have a flange-shaped configuration, and by
then fixing these together via welds W. Alternatively, as is shown in FIG. 10, instead of
using a thin, circular-plate shaped filter, it is possible to use a metal mesh filter 41 that is
formed in a circular-cylinder shape. In a case such as this, in order to ensure that an
20 adequate backwashing effect can be produced by the cleaning gas, the metal mesh filter
41 may be fixed by welds W to the downstream-side holder 4B. In particular, in a case in
which both the metal filter 41 and the metal mesh filter 41 are used, it is possible to
eliminate the actual task of replacing the filter, so that the frequency at which
maintenance needs to be performed can be greatly reduced.
25 [0082]
33
Any cleaning gas supply mechanism may be employed provided that it be able
to blow cleaning gas onto the dust filter in the opposite direction from the direction in
which the mixture gas is flowing. For example, it is possible to use a cleaning gas supply
mechanism that, instead of supplying cleaning gas via the exhaust flow path, supplies
cleaning gas directly to the 5 portion of the outflow path between the dust filter and the
analysis mechanism. In addition, the flow path switching portion that is used to form part
of the cleaning gas supply mechanism may be provided with only a single switching
valve. For example, as is shown in FIG. 11, using a single 4-way valve R5, it is possible
to employ a structure in which any one of the analysis mechanism AM side of the
10 outflow path L2, the exhaust flow path L3, or the cleaning gas supply flow path R2 may
be connected to the heating furnace 3 side of the outflow path L2.
[0083]
As is shown in FIG. 12, it is also possible to further provide a cleaning
mechanism 38 that, in a case in which the lower portion electrode 32 is placed in the
15 open-furnace position, is formed so as to move between the upper portion electrode 31
and the lower portion electrode 32 and brush dust from the upper portion electrode 31 or
the lower portion electrode 32. This cleaning mechanism 38 is provided with an upper
portion brush 38A that, when placed inside the heating furnace 3, is in contact with the
upper portion electrode 31, a lower portion brush 38B that, when placed inside the
20 heating furnace 3, is in contact with the lower portion electrode 32,an actuator 38C that
causes the upper portion brush 38A and the lower portion brush 38B to rotate, and a dust
collection vessel 38D that is located so as to be in communication with the respective
dust suction ports DP, and so as to receive the dust brushed from the upper portion brush
38A or the lower portion brush 38B. If this type of cleaning mechanism 38 is employed,
25 then the dust brushed from the upper portion brush 38A or the lower portion brush 38B
34
can be rapidly collected via the dust suction flow path DL before it is able to contaminate
the surrounding portions.
[0084]
Moreover, it is also possible to employ a structure that, in a state in which, as is
shown in FIG. 12 (c), the interior of the 5 heating furnace 3 is being cleaned by the
cleaning mechanism 38, creates a backwash by supplying cleaning gas to the dust filter 4,
and supplies a working fluid to the drive port AP of the ejector 37 so that dust that has
become detached from the dust filter 4 and traveled into the heating furnace 3 can be
collected from the dust suction flow path DL. If this type of structure is employed, then it
10 is possible to efficiently collect the detached dust while simultaneously cleaning both the
interior of the heating furnace 3 and the dust filter 4.
[0085]
As is described above, the timing when compressed air, which is serving as a
working fluid, is supplied to the drive port AP of the ejector 37 is not restricted to the
15 timing when the lower portion electrode 32, which is serving as the second electrode,
moves to the open-furnace position, and may instead be the timing when the dust filter 4
is back-washed, or may be another timing. Moreover, the cleaning gas that is used for
back-washing the dust filter 4 may also be compressed air that is supplied from the same
supply source as that used for the working fluid supplied to the ejector. This enables the
20 same gas to be used in common for all operations relating to cleaning in the elemental
analysis device, and thereby enables the structure to be further simplified.
[0086]
In the above-described embodiments, the purifier may be formed from heated
copper oxide/reduced copper, and a CO2/H2O desorption agent may be provided on the
25 downstream side thereof between the purifier and the heating furnace on the inflow path.
35
In addition, the removal mechanism is not restricted to mechanisms that remove CO2 and
H2O by means of adsorption, and mechanisms that remove CO2 and H2O by means of a
chemical reaction using a reagent may also be employed.
[0087]
The elemental analysis 5 device is not restricted to devices that measure oxygen
(O), hydrogen (H), and nitrogen (N) as elements. In other words, the analysis mechanism
may also be a mechanism that only measures hydrogen (H). More specifically, the
elemental analysis device may be one that uses Ar as the carrier gas, and in which a dust
filter, an oxidizer, a removal mechanism, a separation column, a mass flow controller,
10 and an H2 detection portion, which is serving as a thermal conductivity analysis portion,
are provided in the above sequence from the upstream side of the outflow path. Moreover,
in this type of embodiment, a room-temperature oxidizing agent may be used as the
oxidizer, and a removal mechanism that uses an adsorption agent to remove only CO2
may be used as the removal mechanism. In addition, an analysis device that includes
15 carbon (C) as an analysis subject may also be used.
[0088]
The analysis mechanism is not restricted to that described in the foregoing
embodiments. For example, instead of a mass flow controller, it is also possible to
provide a needle valve and to thereby maintain a constant aperture. Furthermore, the
20 analysis mechanism may be one that detects a plurality of components, or may be one
that detects only a single component.
[0089]
While preferred embodiments of the invention have been described and
illustrated above, it should be understood that these are exemplary of the invention and
25 are not to be considered as limiting. Additions, omissions, substitutions, and other
36
modifications can be made without departing from the spirit or scope of the present
invention. Accordingly, the invention is not to be considered as limited by the foregoing
description and is only limited by the scope of the appended claims.
[Industrial Applicability]
5 [0090]
According to the present invention, it is possible to provide an elemental
analysis device that enables the dust filter replacement frequency to be reduced, and
enables the time and labor required for maintenance performed by a user to also be
reduced.

We claim:
1. An elemental analysis device comprising:
a heating furnace in which a test sample that is placed in a crucible is heated so
5 that a sample gas is generated from the test sample;
an inflow path through which a carrier gas is introduced into the heating
furnace;
an outflow path through which a mixture gas made up of the carrier gas and the
sample gas is led out from the heating furnace;
10 a dust filter that is provided on the outflow path;
an analysis mechanism that is provided on the outflow path on a downstream
side from the dust filter, and that detects one or a plurality of predetermined components
contained in the mixture gas; and
a cleaning gas supply mechanism that supplies cleaning gas to the dust filter in
15 an opposite direction from a direction in which the mixture gas is flowing.
2. The elemental analysis device as claimed in Claim 1, further comprising an
exhaust flow path that branches off from between the dust filter and the analysis
mechanism on the outflow path, and through which the gas that has passed through the
dust filter is exhausted, wherein
20 the cleaning gas supply mechanism comprises:
a flow path switching portion that is equipped with at least a switching
valve that is disposed on a branch point between the outflow path and the branch flow
path, and that switches flow paths in such a way that cleaning gas flows in an opposite
direction from a direction in which the mixture gas is flowing along the outflow path;
25 and
38
a cleaning gas supply portion that supplies cleaning gas to the exhaust
flow path or to the switching valve.
3. The elemental analysis device as claimed in Claim 2, wherein
the cleaning gas supply portion comprises:
a cleaning gas supply 5 source that blows out cleaning gas at a
predetermined pressure; and
a cleaning gas supply flow path that connects the cleaning gas supply
source to the exhaust flow path, and wherein
the flow path switching portion comprises:
10 a first 3-way valve which serves as the switching valve; and
a second 3-way valve that is disposed at a merging point where the
exhaust flow path and the cleaning gas supply flow path merge.
4. The elemental analysis device as claimed in Claim 2, wherein
the cleaning gas supply portion comprises:
15 a cleaning gas supply source that blows out cleaning gas at a
predetermined pressure; and
a cleaning gas supply flow path that connects the cleaning gas supply
source to the exhaust flow path, and wherein
the flow path switching portion comprises:
20 a 4-way valve serving as the switching valve that switches flow paths in
such a way that any one of the analysis mechanism side of the outflow path, the exhaust
flow path, or the cleaning gas supply flow path is connected to the heating furnace side
of the outflow path.
5. The elemental analysis device as claimed in any one of Claims 1 through 4,
25 wherein the dust filter comprises:
39
a membrane filter; and
a filter holder that holds the membrane filter by sandwiching the
membrane filter in a thickness direction thereof.
6. The elemental analysis device as claimed in Claim 5, wherein the filter holder is
5 formed from resin or glass.
7. The elemental analysis device as claimed in any one of Claims 1 through 4,
wherein the dust filter comprises:
a metal filter; and
a filter holder to which the metal filter is welded.
10 8. The elemental analysis device as claimed in any one of Claims 1 through 7,
wherein the heating furnace comprises:
a first electrode;
a second electrode that is formed so as to be able to move between a
closed-furnace position where it sandwiches the crucible between itself and the first
15 electrode, and an open-furnace position that is separated by a predetermined distance
from the closed-furnace position;
a drive mechanism that causes the second electrode to move between
the closed-furnace position and the open-furnace position;
a dust-suction flow path that opens in the interior of the heating furnace
20 and is equipped with a dust-suction port that draws in dust; and
an ejector that is equipped with an intake port that is connected to the
heating furnace side of the dust-suction flow path, a discharge port that is connected to
the discharge side of the dust-suction flow path, and a drive port to which a working fluid
is supplied, wherein,
25 the drive mechanism is formed in such a way that, in a case in which the drive
40
mechanism moves the second electrode from the closed-furnace position to the
open-furnace position, the working fluid flows into the drive port of the ejector.
9. The elemental analysis device as claimed in Claim 8, wherein the drive
mechanism is a hydraulic cylinder that is equipped with a first port through which the
working fluid either flows in or flows out, and 5 is formed in such a way that, in a case in
which the working fluid flows in through the first port, a piston rod is drawn in so that
the second electrode is moved to the open-furnace position side, and
is also formed in such a way that, in a case in which the working fluid flows into
the hydraulic cylinder through the first port, the working fluid also flows into the ejector
10 through the drive port.
10. The elemental analysis device as claimed in Claim 9, further comprising:
a first supply line that connects a supply source for the working fluid to the first
port; and
a drive line that branches off from the first supply line and is connected to the
15 drive port.
11. The elemental analysis device as claimed in Claim 9 or 10, wherein the
hydraulic cylinder is equipped with a second port through which the working fluid either
flows in or flows out, and is formed in such a way that, in a case in which the working
fluid flows in through the second port, a piston rod is pushed out so that the second
20 electrode is moved to the closed-furnace position side.
12. The elemental analysis device as claimed in any one of Claims 9 through 11,
wherein the hydraulic cylinder is an air cylinder, and the working fluid is compressed air.
13. The elemental analysis device as claimed in any one of Claims 9 through 12,
further comprising a supporting body inside which is formed the dust suction flow path,
25 and that supports the second electrode, wherein
41
the piston rod of the hydraulic cylinder is connected to the supporting body.
14. The elemental analysis device as claimed in Claim 13, wherein the dust suction
flow path comprises a plurality of dust suction ports that open onto a surface of the
supporting body.
15. The elemental analysis device 5 as claimed in any one of Claims 8 through 14,
further comprising a cleaning mechanism that is formed in such a way that, in a case in
which the second electrode is in the open-furnace position, the cleaning mechanism
moves between the first electrode and the second electrode, and removes dust from the
first electrode or the second electrode, wherein
10 the cleaning mechanism is also formed in such a way that the dust removed from
the first electrode of the second electrode by the cleaning mechanism is collected from
inside the heating furnace via the dust suction flow path.
16. The elemental analysis device as claimed in any one of Claims 1 through 7,
wherein the heating furnace comprises:
15 a first electrode;
a second electrode that is formed so as to be able to move between a
closed-furnace position where it sandwiches the crucible between itself and the first
electrode, and an open-furnace position that is separated by a predetermined distance
from the closed-furnace position;
20 a drive mechanism that causes the second electrode to move between
the closed-furnace position and the open-furnace position;
a dust-suction flow path that opens in the interior of the heating furnace
and is equipped with a dust-suction port that draws in dust; and
an ejector that is equipped with an intake port that is connected to the
25 heating furnace side of the dust-suction flow path, a discharge port that is connected to
42
the discharge side of the dust-suction flow path, and a drive port to which a working fluid
is supplied, wherein,
the cleaning gas supply mechanism is formed in such a way that, in a case in
which the cleaning gas is flowing to the dust filter in an opposite direction from a
direction in which the mixture gas 5 is flowing, the working fluid flows into the drive port
of the ejector.