Elemental analysis device, mounting jig, and mounting method

Abstract

Provided is an elemental analysis device, a mounting jig, and a mounting method, which enable replacement of only a consumed electrode tip portion of an electrode formed with a housing recess that houses a crucible inside during elemental analysis, an elemental analysis device (100) that sandwiches a crucible (MP) into which a sample is placed between a first electrode (31) and a second electrode (32), heats the sample by causing current to flow between the first electrode (31) and the second electrode (32), the first electrode (31) being provided with: a first electrode main body (31B) formed with a housing recess (311) that houses the crucible (MP); and a first electrode tip (31C) that is detachably provided to the first electrode main body (31B) in such a manner that a portion thereof protrudes into the housing recess (311).

Description

TECHNICAL FIELD

[0001] The present application relates to an elemental analysis device that heats a sample and analyzes elements contained in the sample based on generated sample gas. BACKGROUND

[0002] In order to quantify elements such as nitrogen (N), hydrogen (H), oxygen (O), and the like contained in a sample, an elemental analysis device is used. Such an elemental analysis device heats a graphite crucible in which a sample is housed by a pair of electrodes clamping the crucible, by causing a current to flow directly through the crucible, to heat the crucible and the sample. Sample gas generated by the heating is guided from the heating furnace to the outside, and the concentration of various components is measured by an analysis mechanism composed of an NDIR (Non Dispersive Infrared), a TCD (Thermal Conductivity Detector), or the like.

[0003] For example, the heating furnace of the elemental analysis device described in Patent Literature 1 has an upper electrode in which a housing recess is formed in the inside, and a lower electrode on which the crucible is placed. The crucible is housed in the housing recess in a state of being clamped by the upper electrode and the lower electrode by the lower electrode rising.

[0004] Specifically, the upper electrode has a substantially cylindrical upper electrode main body in which the housing recess is formed, and an upper electrode tip that is brazed and fixed in the upper electrode main body in the housing recess.

[0005] Therefore, if the upper electrode tip is consumed due to repeated elemental analysis, the entire upper electrode must be replaced, and a great deal of time and labor and cost are spent for the replacement.

[0006] PRIOR ART DOCUMENTS

[0007] PATENT LITERATURE

[0008] Patent Literature 1: U.S. Patent Literature No. 9808797 SUMMARY

[0009] PROBLEMS TO BE SOLVED BY THE INVENTION

[0010] The present application has been made in view of the above-described problems, and an object of the present application is to provide an elemental analysis device in which only a consumed electrode tip portion can be replaced for an electrode in which a housing recess in which a crucible is housed in the inside at the time of elemental analysis is formed.

[0011] MEANS FOR SOLVING THE PROBLEMS

[0012] The elemental analysis device of the present application is characterized in that the elemental analysis device sandwiches a crucible into which a sample is put between a first electrode and a second electrode, heats the sample by causing a current to flow between the first electrode and the second electrode, and the first electrode includes a first electrode main body that forms a housing recess in which the crucible is housed, a first electrode tip that is partially exposed into the housing recess of the first electrode main body, and a fixing structure that is provided between the first electrode main body and the first electrode tip and detachably fixes the first electrode tip with respect to the first electrode main body.

[0013] If the elemental analysis device is such, since the first electrode tip is configured to be detachable with respect to the first electrode main body, in the case where the first electrode tip is consumed, only this part can be replaced. Therefore, compared to the case where the entire first electrode is replaced as in the past, the time and labor and cost spent for replacement can be greatly reduced.

[0014] As a specific way for detachably fixing the first electrode tip with respect to the first electrode main body, a first threaded connection structure in which the fixing structure is composed of a male threaded portion and a female threaded portion formed between the first electrode main body and the first electrode tip can be cited.

[0015] In order to enable the first electrode tip to be detachable with respect to the first electrode main body and prevent sample gas generated from the sample from leaking to the outside from between the first electrode tip and the first electrode main body, as long as the first electrode main body further includes a sample insertion hole whose one end is open at the housing recess and is used for inserting the sample into the crucible, and the first threaded connection structure is composed of the male threaded portion and the female threaded portion formed between a part of the sample insertion hole of the first electrode main body and the first electrode tip, it is sufficient.

[0016] In order to rapidly lead sample gas generated from the sample in the crucible into the housing recess and enable the elemental analysis to be correctly performed in a short time, as long as the first electrode tip includes an insertion cylinder in which the male threaded portion is formed on an outer peripheral surface and is inserted into the sample insertion hole of the first electrode main body, a flange portion that is a part exposed into the housing recess and expands in a radial direction on one end side of the insertion cylinder, a through hole formed to pass through the insertion cylinder and the flange portion in an axial direction, and a gas leading groove formed to be open at least one end at the through hole and extend in a radial direction on the flange portion, it is sufficient.

[0017] In order to engage an implement such as a mounting jig with the gas outlet groove, sufficient torque is applied when the first electrode tip is screwed with respect to the first electrode body, as long as the other end of the gas outlet groove is formed to open at the outer lateral surface of the flange portion.

[0018] In order to not cause uneven flow of sample gas and to easily apply torque uniformly at the time of mounting the first electrode tip, as long as the gas outlet groove is formed with a plurality of and is arranged axially symmetrically with respect to the central axis of the first electrode tip.

[0019] If the gas outlet groove doubles as an engagement groove that engages with a jig at the time of detaching the first electrode tip from the first electrode body, the operation of attaching and detaching the first electrode tip with respect to the depth of the housing recess can be performed using the elements required for elemental analysis, and thus there is no need to provide an element such as an engagement groove that engages with a jig separately in the first electrode tip. Thus, the first electrode tip can be attached and detached with respect to the first electrode body, and the flow of gas optimized for elemental analysis is not hindered by elements for attachment and detachment. Thus, elemental analysis can be performed with the same precision as when the entire first electrode is formed as a unit as in the past.

[0020] In order to clamp the crucible with the first electrode and the second electrode inside the housing recess, heat the sample in the enclosed space, and easily lead the entire sample gas produced to the analysis device side, as long as the second electrode can be moved between a first position that clamps the crucible inside the housing recess between the first electrode and the second electrode and a second position that is separated by a prescribed distance from the first position and in which the crucible is arranged outside the housing recess.

[0021] In the elemental analysis device of the present application, a mounting jig is used to mount the first electrode tip to the first electrode body, the mounting jig having a guide that fits into the housing recess, a rotation shaft that is arranged to be rotatable with respect to the guide, and an engagement member that is protrusively arranged in the radial direction at the front end portion of the rotation shaft and engages with the gas outlet groove. If the mounting jig is used, the first electrode tip can be easily mounted in a straight posture even when it is screwed to the depth side of the housing recess.

[0022] Effects of the Invention

[0023] According to the present application, since the first electrode tip is configured to be detachable with respect to the accommodation recess of the first electrode body, only the first electrode tip can be replaced when the first electrode tip is consumed. Therefore, the first electrode does not need to be replaced as a whole, and the time and labor and cost for replacement can be greatly reduced compared to the past. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a schematic diagram of an elemental analysis device according to a first embodiment of the present application.

[0025] Figure 2 is a schematic cross-sectional view showing a state in which a crucible is held by the first electrode and the second electrode according to the first embodiment.

[0026] Figure 3 is a schematic exploded perspective view of the first electrode according to the first embodiment and a schematic view of an end surface of a flange portion.

[0027] Figure 4 is a schematic exploded perspective view of the second electrode according to the first embodiment.

[0028] Figure 5 is a schematic cross-sectional view showing a use state of a mounting jig for an elemental analysis device according to a second embodiment of the present application.

[0029] Figure 6 is a schematic perspective view showing the mounting jig according to the second embodiment.

[0030] Figure 7 is a schematic view showing an example of a first electrode tip according to another embodiment of the present application.

[0031] Figure 8 is a schematic view showing a surface side of a cover of a second electrode according to another embodiment of the present application.

[0032] Figure 9 is a schematic view showing a back side of the cover of the second electrode according to the another embodiment.

[0033] Figure 10 is a schematic view showing another example of the cover of the second electrode.

[0034] Figure 11 is a schematic view showing an exhaust flow passage in a case where an exhaust groove is formed in either one of a female screw portion and a male screw portion.

[0035] REFERENCE NUMERALS

[0036] 100 ••• elemental analysis device

[0037] 1 ••• supply source

[0038] 2... Refiner

[0039] 3... Heating furnace

[0040] 31... First electrode

[0041] 31B... First electrode main body

[0042] 311... Accommodation recess

[0043] 312... Outflow hole

[0044] 313... Sample insertion hole

[0045] 31C... First electrode tip

[0046] 314... Insertion cylinder

[0047] 315... Flange portion

[0048] 316... Through hole

[0049] 317... Gas lead-out groove

[0050] 31S... First threaded connection structure

[0051] 32... Second electrode

[0052] 32B... Second electrode main body

[0053] ST... Step portion

[0054] 322... Recess

[0055] 32C... Second electrode tip

[0056] 32D... Cover

[0057] 32S... Second threaded connection structure

[0058] 323... Exposure port

[0059] 324... Pressing plate

[0060] 325... Vent hole

[0061] 326... Gas discharge groove

[0062] 327... Annular recess

[0063] 32F... Exhaust flow path

[0064] 4... Dust filter

[0065] 5... CO detection portion

[0066] 6. Oxidizer

[0067] 7. CO2 Detection Department

[0068] 8. H2O Detection Department

[0069] 9···Removal mechanism

[0070] 10. Mass Flow Controller

[0071] 11. N2 Testing Department (Thermal Conductivity Analysis Department) Detailed Implementation

[0072] The elemental analysis apparatus 100 of the first embodiment of the present invention will be described with reference to the figures. Figure 1 The diagram shows a schematic of the elemental analysis apparatus 100 according to the first embodiment.

[0073] The elemental analysis apparatus 100 heats and melts a sample, such as a metal sample or a ceramic sample (hereinafter simply referred to as a sample), contained in a graphite crucible MP, and analyzes the sample gas generated during this process to measure the amount of elements contained in the sample. In the first embodiment, C (carbon), H (hydrogen), and N (nitrogen) contained in the sample are the objects of measurement.

[0074] like Figure 1 As shown, the elemental analysis apparatus 100 includes: a heating furnace 3 for heating a sample contained in a crucible MP; an inlet channel L1 for introducing a carrier gas into the heating furnace 3; and an outlet channel L2 for exporting a mixture of the carrier gas and the sample gas from the heating furnace 3. More specifically, the elemental analysis apparatus 100 comprises a heating furnace 3, various devices installed in the inlet channel L1 or the outlet channel L2, and a control calculation unit COM that controls the devices and calculates the measured concentrations, etc. The control calculation unit COM is, for example, a computer equipped with a CPU, memory, A / D converter, D / A converter, and various input / output devices. It executes a program stored in the memory, and various devices cooperate to perform the function of the measurement value calculation unit C1, which will be described later. In addition, the control calculation unit COM also functions as a display unit (not shown) that displays the concentrations of various elements contained in the sample based on the outputs of, for example, the CO detection unit 5, the CO2 detection unit 7, the H2O detection unit 8, and the N2 detection unit 11.

[0075] Each part is described in detail.

[0076] A gas cylinder as a supply source 1 of carrier gas is connected to the base end of the introduction flow path Ll. In the first embodiment, He (helium) is supplied from the supply source 1 into the introduction flow path Ll. In addition, a refiner 2 for removing a small amount of hydrocarbon contained in the carrier gas to improve the purity of the carrier gas is provided on the introduction flow path Ll.

[0077] The refiner 2 is formed of a material having a property of physically adsorbing the hydrocarbon contained in the carrier gas and substantially not adsorbing the carrier gas itself. In addition, the material forming the refiner 2 does not chemically react with the carrier gas and the hydrocarbon. That is, the refiner 2 can be, for example, a refiner used in a gas chromatograph, and as the material forming the refiner 2, for example, a zeolite-based molecular sieve can be used. In addition, as the material forming the refiner 2, silica gel, activated carbon, ascarite, or the like can also be used. The refiner 2 can regenerate its adsorption capacity by, for example, desorbing the adsorbed molecules by heating.

[0078] The heating furnace 3 is configured to hold a graphite crucible MP in which a sample is accommodated with a pair of electrodes, and to heat the crucible MP and the sample by causing a current to flow directly through the crucible MP. When heating the sample, the pressure of the carrier gas is adjusted by a pressure regulating valve (not shown) provided on the upstream side of the heating furnace 3 in such a manner that the pressure in the heating furnace 3 becomes a pressure of 60 kPa or less, more preferably a pressure of 40 kPa or less. Details of the electrodes of the heating furnace 3 are described later.

[0079] Next, each device provided on the discharge flow path L2 will be described.

[0080] On the discharge flow path L2, a dust filter 4, a CO detection section 5, an oxidizer 6, a CO2 detection section 7, an H2O detection section 8, a removal mechanism 9, a mass flow controller 10, and an N2 detection section 11 as a thermal conductivity analysis section are arranged in this order from the upstream side.

[0081] The dust filter 4 filters out soot and the like contained in the sample gas and performs dust removal.

[0082] The CO detection section 5 detects CO (carbon monoxide) contained in the mixed gas that has passed through the dust filter 4, measures the concentration thereof, and is configured of an NDIR (non-dispersive infrared gas analyzer). The CO detection section 5 is effective in acting in a case where oxygen contained in the inside of the sample is at a high concentration, from the viewpoint of the measurement accuracy thereof. Specifically, it is preferable to take 150 ppm or more of CO as a measurement target.

[0083] The oxidizer 6 oxidizes CO and CO2 contained in the mixed gas that has passed through the CO detection section 5, and oxidizes H2 to H2O (water) to generate water vapor. As this oxidizer 6, in the first embodiment, copper oxide is used, and the temperature thereof is maintained at a temperature of 450°C or lower by a heating resistor provided around.

[0084] The CO2 detection section 7 is an NDIR that detects CO2 in the mixed gas that has passed through the oxidizer 6 and measures the concentration thereof. This CO2 detection section 7 is effective in operation in a case where oxygen contained in a sample is at a low concentration (for example, less than 150 ppm) from the viewpoint of measurement accuracy.

[0085] The H2O detection section 8 is an NDIR that detects H2O in the mixed gas that has passed through the CO2 detection section 7 and measures the concentration thereof. In addition, the flow path from the oxidizer 6 to the H2O detection section 8 is configured so that the temperature of the mixed gas is maintained at 100°C or higher, and H2O is maintained in a state of water vapor. By doing so, it becomes possible to prevent measurement errors due to condensation from occurring in the H2O detection section 8.

[0086] The removal mechanism 9 adsorbs and removes CO2 and H2O contained in the mixed gas. This removal mechanism 9 is configured by a sorbent, and for example, the same configuration as the refiner 2 provided on the introduction flow path LI described above is used.

[0087] The mass flow controller 10 is a flow control device in which the flow sensor Ml, the control valve M2, and the flow controller M3 are made into one assembly. This mass flow controller 10 supplies the mixed gas whose flow rate is maintained constant to the N2 detection section 11 located on the downstream side. Therefore, even if the pressure of the mixed gas is changed due to the removal mechanism 9, it becomes possible to maintain the pressure of the mixed gas in the N2 detection section 11 at a value suitable for measurement. In the first embodiment, the mass flow controller 10 is configured to operate at a pressure lower than 60 kPa, for example, even if the pressure difference before and after is 20 kPa, so that it becomes possible to maintain the pressure in the heating furnace 3 at 60 kPa.

[0088] The N2 detection section 11 is a TCD (thermal conductivity detector) that measures the concentration of N2 as a prescribed component contained in the mixed gas, based on the change in the thermal conductivity of the mixed gas and the flow rate of the mixed gas supplied. That is, since the mixed gas supplied to the N2 detection section 11 is basically composed of only the carrier gas and N2, the concentration of N2 contained in the mixed gas becomes a value corresponding to the change in the measured thermal conductivity. In addition, in the first embodiment, a flow meter is not provided on the downstream side of the N2 detection section 11, and the downstream side of the N2 detection section 11 is directly connected to the exhaust port of the discharge flow path L2.

[0089] Measurement signals indicating the concentration of each component obtained from each detection unit are input to the measurement value calculation unit C1. The measurement value calculation unit C1 calculates the concentrations of O, H, and N contained in the sample based on each measurement signal. Furthermore, when calculating the oxygen concentration contained in the sample, the measurement value calculation unit C1 uses the oxygen concentration obtained from the CO detection unit 5 as the output value if the oxygen concentration inside the sample is above a predetermined threshold (150 ppm), and uses the oxygen concentration obtained from the CO2 detection unit 7 as the output value if it is below the threshold.

[0090] Finally, the pair of electrodes set in the heating furnace 3 are described in detail.

[0091] like Figure 2 Cross-sectional view Figure 3 as well as Figure 4 As shown in the perspective view, the heating furnace 3 includes: a first electrode 31, which is an upper electrode fixed above; and a second electrode 32, which is a lower electrode disposed below, and is a lower electrode for placing the crucible MP.

[0092] like Figure 3 As shown in (a), the first electrode 31 is a generally two-section cylindrical electrode with a thin cylindrical upper side and a flat disc-shaped lower side. The first electrode 31 includes: a first electrode body 31B, as shown in (a). Figure 2 As shown in the cross-sectional view, a hollow cylindrical receiving recess 311 is formed in the lower central portion to house the crucible MP; and a first electrode tip 31C is provided within the receiving recess 311 so that it can be attached to and detached from the first electrode body 31B. The first electrode tip 31C is the portion that directly contacts the upper edge of the generally cylindrical crucible MP and is consumed due to repeated elemental analysis. Furthermore, the first electrode body 31B is formed, for example, of copper, and the first electrode tip 31C is formed, for example, of a copper alloy containing tungsten. That is, the first electrode tip 31C is formed of a material with a higher hardness than the first electrode body 31B.

[0093] The first electrode body 31B has the shape of the first electrode 31, such as Figure 2 As shown in the cross-sectional view, the cylindrical receiving recess 311 is formed to extend vertically from the center of the flat disc-shaped portion. Additionally, a sample gas outlet hole 312 extending horizontally is formed with an opening on the side of the receiving recess 311. Furthermore, a sample insertion hole 313 for placing a sample into the crucible MP is formed on the upper side of the receiving recess 311. The sample insertion hole 313 is a generally thin, hollow cylindrical hole with a diameter smaller than that of the receiving recess 311, and is formed to extend vertically along the central axis of the first electrode 31.

[0094] like Figure 2 as well as Figure 3As shown in (a), the first electrode tip 31C is roughly a two-stage cylindrical shape, and includes a thin cylindrical insertion cylinder 314 that is inserted into the sample insertion hole 313 of the first electrode main body 31B, and a flat plate-shaped flange portion 315 that is expanded in the radial direction on the lower end side of the insertion cylinder 314. In addition, the first electrode tip 31C also includes a through hole 316 that is formed so as to pass through the insertion cylinder 314 and the flange portion 315 in the axial direction, and a gas discharge groove 317 that is formed so as to extend in the radial direction with one end opening on the side surface of the through hole 316 and on the flange portion 315. As shown in (b), the gas discharge groove 317 is provided with four grooves that are arranged at 90° intervals with respect to the central axis in an axially symmetric manner. As shown in (c), the radially inner end portion of the gas discharge groove 317 is open on the inner side of the crucible MP. In addition, in the first embodiment, the other end portion of the gas discharge groove 317 is open on the outer side of the flange portion 315. That is, the sample gas that is generated from the sample in the crucible MP flows out from the inside of the crucible MP to the outside of the crucible MP via the gas discharge groove 317. Thereafter, the sample gas flows out from the accommodation recess 311 to the discharge flow passage L2 via the discharge hole 312 formed in the first electrode main body 31B. Figure 3 As shown in (b), the radially inner end portion of the gas discharge groove 317 is open on the inner side of the crucible MP. In addition, in the first embodiment, the other end portion of the gas discharge groove 317 is open on the outer side of the flange portion 315. That is, the sample gas that is generated from the sample in the crucible MP flows out from the inside of the crucible MP to the outside of the crucible MP via the gas discharge groove 317. Thereafter, the sample gas flows out from the accommodation recess 311 to the discharge flow passage L2 via the discharge hole 312 formed in the first electrode main body 31B. Figure 2 As shown in (c), the radially inner end portion of the gas discharge groove 317 is open on the inner side of the crucible MP. In addition, in the first embodiment, the other end portion of the gas discharge groove 317 is open on the outer side of the flange portion 315. That is, the sample gas that is generated from the sample in the crucible MP flows out from the inside of the crucible MP to the outside of the crucible MP via the gas discharge groove 317. Thereafter, the sample gas flows out from the accommodation recess 311 to the discharge flow passage L2 via the discharge hole 312 formed in the first electrode main body 31B.

[0095] A fixing structure that detachably fixes the first electrode tip 31C to the first electrode main body 31B is provided between the first electrode tip 31C and the first electrode main body 31B. More specifically, a first screw connection structure 31S that is composed of a male screw portion S1 and a female screw portion S2 is formed as the fixing structure between the outer side surface of the insertion cylinder 314 of the first electrode tip 31C and the inner side surface of the sample insertion hole 313 of the first electrode main body 31B. With this first screw connection structure 31S, the first electrode tip 31C is configured to be detachable with respect to the first electrode main body 31B. In addition, there is no groove cut in the thread direction on the thread of the first screw connection structure 31S. Therefore, in a state in which the first screw connection structure 31S is completely screwed, the flange portion 315 is in close contact with the upper side wall surface of the accommodation recess 311, and the male screw portion S1 and the female screw portion S2 are in a state of being in close contact without a gap. Therefore, it is possible to prevent the sample gas that flows out from the crucible MP from accumulating or flowing back in the gap between the first electrode main body 31B and the first electrode tip 31C.

[0096] Next, the second electrode 32 will be described with reference to Figure 2 and Figure 4

[0097] ​The second electrode 32 is configured to be movable in the up-and-down direction by a cylinder not shown, and a part thereof is inserted into the housing recess 311 together with the placed crucible MP. Specifically, the second electrode 32 is configured to be movable between a first position at which the crucible located in the housing recess 311 is sandwiched between the first electrode 31 and a second position at which the crucible is disposed outside of the housing recess 311 by a prescribed distance from the first position.

[0098] Further, the second electrode 32 includes a second electrode main body 32B which is a substantially two-stage cylindrical shape, a second electrode tip 32C which is provided at a front end surface of the second electrode main body 32B and is a thin disc shape, and a cap 32D which fixes the second electrode tip 32C with respect to the second electrode main body 32B and is formed with a revealing port for revealing a contact surface of the second electrode tip 32C which contacts the crucible MP to the outside. Further, the second electrode main body 32B and the cap 32D are formed of copper, and the second electrode tip 32C is formed of a copper alloy including tungsten.

[0099] In this way, the second electrode 32 is configured of three separate parts, and is configured to be able to replace only the second electrode tip 32C. More specifically, a second threaded connection structure 32S which is configured of a male threaded portion S1 and a female threaded portion S2 is formed between an outer side peripheral surface of a front end portion of the second electrode main body 32B and an inner side peripheral surface of the cap 32D.

[0100] The structure of the second threaded connection structure 32S is different from the structure of the first threaded connection structure 31S formed in the first electrode 31. That is, as shown in Figure 4 the male threaded portion S1 of the second threaded connection structure 32S is formed so as to extend in the pitch direction of the thread and cut off a part of the thread. The air release groove 321 is configured to cut off the thread to the height of the thread bottom, for example, but can be formed shallower. Further, the air release groove 321 is provided at every 90° so as to be axially symmetrical with respect to the center axis of the second electrode 32, and is provided four times. The number of the air release groove 321 is not limited to four, and can be fewer or more. Further, it is not necessarily configured to be axially symmetrical.

[0101] Due to the formation of the air release groove 321, even if air accumulated in the gap between the threads of the second threaded connection structure 32S at the time of attachment of the cap 32D is present between the threads, for example, at the time of replacement of the air present in the heating furnace 3 with carrier gas, the air in the second electrode 32 can be released from the air release groove 321 to the outside of the second electrode 32.

[0102] The second electrode main body 32B is formed with a recess 322 which is formed so as to substantially fit the back surface side of the second electrode tip 32C at the front end surface, and as shown in Figure 2As shown, a step portion ST is formed on the front end side opposite the edge of the cover 32D. The front end face of the second electrode 32 on which the second electrode tip 32C is mounted is formed to have the smallest diameter, and the portion of the step portion ST is enlarged to have an outer diameter substantially the same as the outer diameter of the mounted O-ring SL.

[0103] Specifically, by being in a state in which the second electrode tip 32C is embedded in the recess portion 322 in advance, the alignment of the second electrode tip 32C with respect to the second electrode body 32B can be performed. Further, in a state in which the position of the second electrode tip 32C is determined, by threadedly connecting the cover 32D to the second electrode body 32B, the position of the second electrode tip 32C can be fixed while being maintained at the correct position.

[0104] Further, the annular groove RT formed between the step portion ST of the second electrode body 32B and the edge of the cover 32D is provided with the O-ring SL. That is, in a state before the cover 32D is mounted, there is no member that restricts the movement of the O-ring SL in the axial direction. Further, the annular groove RT is formed to be slightly larger than the thickness dimension of the O-ring SL. In order to grip the crucible MP with each electrode and flow a current, during the process of inserting the second electrode 32 into the housing recess portion 311 of the first electrode body 31B, the O-ring SL slides and abuts against the edge side of the cover 32D, thereby forming a seal inside the housing recess portion 311. As thus configured, it is not necessary to mount the O-ring SL in a state in which the inner diameter thereof is greatly enlarged as in the past, and the mounting operation of the O-ring SL can be simplified.

[0105] The cover 32D has a top surface portion D1 and a side surface portion D2. The top surface portion D1 is provided with a revealing port 323 that reveals the second electrode tip 32C to the outside, and a pressing plate 324 that is provided around the revealing port 323 and presses the second electrode tip 32C toward the front end face of the second electrode body 32B in a state in which the cover 32D is threadedly connected to the second electrode body 32B. In the side surface portion D2, a female screw portion S1 is formed on the inner peripheral surface. Further, a gap is formed between the end surface of the side surface portion D2 and the second electrode body 32B, and even in a state in which the cover 32D is completely threadedly connected to the second electrode body 32B, the air that has passed through the exhaust groove 321 is not hindered from being discharged to the outside of the second electrode 32 from the edge on the lower side of the cover 32D.

[0106] If the elemental analysis device 100 is thus configured, since the first electrode tip 31C is configured to be detachable with respect to the first electrode body 31B by the first thread connection structure 31S, in a case in which the first electrode tip 31C is consumed due to repeated elemental analysis, only the first electrode tip 31C can be replaced. Therefore, it is not necessary to replace the entire first electrode 31 including the first electrode body 31B as in the past.

[0107] In addition, the second electrode tip 32C is configured to be detachable by the second screw connection structure 32S formed between the second electrode main body 32B and the cover 32D, so that only the second electrode tip 32C can be replaced when it is consumed.

[0108] As such, the time and labor and cost required for replacement of consumables for continuous elemental analysis in the heating furnace 3 can be greatly reduced compared to the past.

[0109] In addition, since the second screw connection structure 32S has the exhaust groove 321 that penetrates each thread in the pitch direction of the thread, by filling the carrier gas in the heating furnace 3 before heating the sample, the air in the second electrode 32 can be exhausted to the outside from the exhaust groove 321. Furthermore, the air in the second electrode 32 can be made not to exist at the time of heating the sample, and the air that has been expanded by heat is not leaked from the second electrode 32 as in the past when the sample gas is generated. That is, the air containing nitrogen (N) that becomes a cause of error is not leaked from the second electrode 32 at the time of generation of the sample gas, so the measurement accuracy of the trace amount of nitrogen (N) contained in the sample gas can be improved at the N2 detection unit 11.

[0110] Next, the mounting jig 200 for the elemental analysis device of the second embodiment of the present application will be described with reference to Figure 5 and Figure 6 Next, the mounting jig 200 for the elemental analysis device of the second embodiment of the present application will be described with reference to

[0111] The mounting jig 200 of the second embodiment is used to mount the first electrode tip 31C with respect to the first electrode main body 31B of the elemental analysis device 100 described in the first embodiment. That is, the first electrode tip 31C formed as an axisymmetric member needs to be mounted to the deepest part of the accommodation recess 311 of the first electrode main body 31B, and since the hardness of the first electrode tip 31C is higher than that of the first electrode main body 31B, if the mounting is performed in a state where the mounting jig 200 is not present, there is a possibility that the first electrode tip 31C cuts the first electrode main body 31B and is mounted obliquely. In order to solve such a problem, it is necessary to rotate the first electrode tip 31C in the state where the axis direction of the first electrode tip 31C coincides with the axis direction of the first electrode main body 31B and perform screw connection in the accommodation recess 311 of the first electrode main body 31B.

[0112] Specifically, as Figure 5 a cross-sectional view and Figure 6As shown in a perspective view of FIG. 2, the mounting jig 200 includes a cylindrical guide 20A that is fitted into the housing recess 311, a rotation shaft 20B that is a cylindrical rod-shaped member installed so as to coincide with the axial direction of the guide 20A and is configured to be rotatable with respect to the guide 20A, and a fitting member 20C that is provided so as to protrude in the radial direction at the front end of the rotation shaft 20B and has a substantially cuboid shape that is fitted into the gas discharge groove 317 of the first electrode tip 31C.

[0113] In the second embodiment, the guide 20A has an outer diameter that is substantially the same as the maximum diameter of the housing recess 311, and by fitting the guide 20A into the housing recess 311, the axial direction of the guide 20A and the rotation shaft 20B can be made to substantially coincide with the axial direction of the housing recess 311 and the sample insertion hole 313 of the first electrode main body 31B. By rotating the rotation shaft 20B with respect to the guide 20A in this state, the first electrode tip 31C, which is fitted into the gas discharge groove 317 and the fitting member 20C, can be rotated while maintaining the correct posture and be threadedly connected to the first electrode main body 31B.

[0114] In this way, according to the mounting jig 200 of the second embodiment, it becomes easy to install the first electrode tip 31C straight into the deepest part of the housing recess 311, and the end surface of the flange portion 315 of the first electrode tip 31C comes to be in complete contact with the edge of the crucible MP. Therefore, it is possible to prevent a situation in which sufficient current cannot flow and the sample cannot be heated as intended due to insufficient contact between the flange portion 315 and the crucible MP.

[0115] Further embodiments of the present application will be described.

[0116] As Figure 7 As shown in each of the drawings, the shape of the gas discharge groove 317 formed in the first electrode tip 31C is not limited to the shapes described in each of the embodiments. For example, only one end of the gas discharge groove 317 can be opened with respect to the through-hole 316, and the other end of the gas discharge groove 317 can not be opened at the outer side circumferential surface of the flange portion 315. In addition, the number of the gas discharge grooves 317 is not limited to four, and can be two or three.

[0117] Various diameters can be prepared for the through hole of the first electrode tip. For example, if the sample being inserted is rod-shaped, the diameter can be changed to an appropriate size to prevent blockage between the sample insertion hole in the first electrode body and the crucible. That is, since the diameter of the sample channel can be appropriately changed simply by replacing the first electrode tip, it is easy to replace it with a diameter suitable for the shape and properties of the sample. Furthermore, the fixing structure that detachably fixes the first electrode tip relative to the first electrode body is not limited to the first threaded connection structure. The fixing structure can also be, for example, an engaging structure or a fitting structure consisting of engaging claws and engaging grooves formed between the first electrode tip and the first electrode body.

[0118] like Figure 8 of (a), Figure 8 (b) Figure 9 As shown in the figures, as a variation of the cover 32D of the second electrode 32, the cover 32D may also include: a vent 325, which opens on the top part D1, further outward than the exposure opening 323 used to expose a part of the second electrode tip 32C to the outside; an exhaust groove 321, which extends in the pitch direction of the thread and is formed in the female thread portion S2 by cutting off a part of the thread; and a gas discharge groove 326, which extends in the radial direction on the lower end face of the side part D2, which is the edge of the cover 32D.

[0119] like Figure 8 As shown in (b), the vent 325 is configured to communicate between the inside and outside of the second electrode 32 when the cover 32D is threadedly connected to the second electrode body 32B and the second electrode tip 32C is fixed. That is, in this embodiment, the vent 325 is formed as a cut extending radially from the exposed opening 323, extending to a point further outward than the outermost periphery of the thin disc-shaped second electrode tip 32C fixed by the cover 32D. In addition, four vents 325 are provided at 90° intervals in a manner symmetrical about the central axis of the second electrode 32.

[0120] like Figure 9 As shown, the exhaust groove 321 and the gas discharge groove 326 are also arranged in a manner symmetrical about the central axis at 90° intervals, and there are four of them, so as to be arranged in a manner that is approximately in phase with the vent 325. The vent 325 and the exhaust groove 321 are close to each other at their respective ends, and the exhaust groove 321 and the gas discharge groove 326 form orthogonal and uninterrupted grooves.

[0121] If the vent hole 325 is thus formed in the top surface portion Dl of the lid 32D, air in the gap between the threads of the second threaded connection structure 32S can be more easily discharged from the top surface portion Dl side at the time of installation of the lid 32D. Also, by the gas discharge groove 326, it becomes easy to discharge air from between the edge of the lid 32D and the O-ring SL as well. Therefore, even if heat is applied to the second electrode 32 due to repeated analysis, causing the gas discharge groove 321 to deform or dust to accumulate, it is possible to make it difficult to reduce the gas discharge performance.

[0122] Next, another modification example of the lid 32D will be shown in Figure 10 . Instead of being formed as a cutout, the vent hole 325 can be formed as a through-hole, for example. The position at which the through-hole is formed can be the outside of the second electrode tip 32C to which the lid 32D is pressed. Also, for the lid 32D shown in Figure 8 to Figure 10 , the respective positions of the three of the vent hole 325, the gas discharge groove 321, and the gas discharge groove 326 are arranged in phase, but the respective positions can be staggered with respect to the circumferential direction. Also, the lid 32D can have at least one of the vent hole 325, the gas discharge groove 321, and the gas discharge groove 326. For example, the lid 32D can have either the vent hole 325 or the gas discharge groove 326, and the gas discharge groove 321 can be formed only in the second electrode body 32B. Furthermore, it can be configured so that the outer dimensions of the lid 32D itself are reduced, the gap between the outside of the side surface portion D2 and the inside surface of the first electrode 31 is made to be a prescribed value or more, and air is more easily discharged from the gas discharge groove 326.

[0123] As shown in Figure 11 , since the gas discharge flow passage 32F that communicates the inside of the second threaded connection structure 32S with the outside of the second electrode 32 is formed, air in the gap between the threads can be quickly discharged to the outside of the second electrode 32 when the lid 32D is installed with respect to the second electrode body 32B. Specifically, when the gas discharge groove 321 is formed in the female threaded portion S2 of the lid 32D, as shown in Figure 11 (a), air present in the gap between the threads can be discharged from the upper side of the lid 32D through the vent hole 325 from the gas discharge groove 321, and can also be discharged from the lower side of the lid 32D through the gas discharge groove 326.

[0124] Also, as shown in Figure 11In the case where the exhaust groove 321 is formed not in the female screw portion S2 of the cap 32D but in the male screw portion S1 of the electrode main body 32B, the same exhaust flow passage 32F can be formed as shown in (b). Specifically, a ring-shaped recessed portion 327 is formed in the vicinity of the base end of the male screw portion S1, and the ring-shaped recessed portion 327 is formed so as to communicate with both the exhaust groove 321 and the gas discharge groove 326. That is, the second electrode main body 32B is cut inward in the peripheral direction to form the ring-shaped recessed portion 327, for example, to a depth approximately the same as the height of the threads of the male screw portion S1. In this way, even in the case where the exhaust groove 321 is formed in the male screw portion S1, the air present between the threads can be rapidly discharged to the outside of the second electrode 32 through the vent hole 325 of the cap 32D or the gas discharge groove 326.

[0125] The shapes of the second electrode tip and the cap are not limited to those shown in the embodiments. For example, in order to easily adjust the position of the exhaust groove of the second threaded connection structure to an appropriate position, the mark indicating the mounting direction of the cap can not be circular but can be partially formed with a notch. In addition, the exhaust groove of the second threaded connection structure formed in the second electrode can be formed not only in the male screw portion but also in the female screw portion. These exhaust grooves can be synchronized in such a manner that the circumferential positions substantially coincide in a state where the cap and the second electrode main body are completely threadedly connected. That is, the exhaust grooves formed in both the male screw portion and the female screw portion can be made to coincide so as to increase the area through which air can pass. Furthermore, the exhaust groove can be formed only in the female screw portion.

[0126] The positional relationship and the moving direction of the first electrode and the second electrode are not limited to those shown in the embodiments. For example, the second electrode can be moved in the horizontal direction with respect to the fixed first electrode, and the crucible can be housed in the housing recess.

[0127] Furthermore, various modifications of the embodiments and combinations of parts of the embodiments can be made without departing from the spirit of the present application.

[0128] Industrial Applicability

[0129] According to the present application, an elemental analysis device can be provided which does not require replacement of the entire first electrode and which can greatly reduce the time and labor and cost required for replacement compared to the past.

Claims

1. An elemental analysis apparatus, characterized in that, The elemental analysis apparatus holds a crucible containing the sample between the first and second electrodes, and heats the sample by flowing an electric current between the first and second electrodes. The first electrode has: The first electrode body has a receiving recess for receiving the crucible; The first electrode tip is configured such that a portion of it protrudes into the receiving recess of the first electrode body; as well as A fixing structure is disposed between the first electrode body and the first electrode tip, thereby detachably fixing the first electrode tip relative to the first electrode body. The first electrode tip, which is the part that directly contacts the upper edge of the crucible, is made of a material with a higher hardness than the main body of the first electrode. The fixing structure is a first threaded connection structure consisting of a male threaded portion and a female threaded portion formed between the first electrode body and the first electrode tip. The first electrode body also has a sample placement hole, one end of which opens into the receiving recess for placing the sample into the crucible. The first electrode head has: An insertion tube has a male threaded portion formed on its outer circumferential surface, into which the sample inserted into the first electrode body is placed; The flange portion is the part that protrudes into the receiving recess and extends radially at one end of the insertion tube. A through hole is formed to pass through the insertion cylinder and the flange portion in the axial direction; as well as A gas outlet groove is formed on the flange portion such that at least one end opens in the through hole and extends in the radial direction.

2. The elemental analysis apparatus according to claim 1, characterized in that, The first threaded connection structure consists of a male thread portion and a female thread portion formed between a portion of the sample insertion hole in the first electrode body and the first electrode tip.

3. The elemental analysis apparatus according to claim 1, characterized in that, The other end of the gas outlet groove is formed by opening on the outer peripheral surface of the flange.

4. The elemental analysis apparatus according to claim 1, characterized in that, The gas outlet grooves are formed in multiple portions and are arranged symmetrically with respect to the central axis of the first electrode tip.

5. The elemental analysis apparatus according to claim 1, characterized in that, The gas outlet groove also serves as an engagement groove that engages with the clamp when the first electrode tip is removed from the first electrode body.

6. The elemental analysis apparatus according to any one of claims 1 to 3, characterized in that, The second electrode is movable between a first position where it clamps the crucible within the receiving recess between itself and the first electrode, and a second position where it is located a predetermined distance away from the first position and the crucible is positioned outside the receiving recess.

7. A mounting clamp, characterized in that, In the elemental analysis apparatus according to any one of claims 1 to 6, the mounting clamp is used to mount the first electrode terminal to the first electrode body. The mounting fixture includes: The guide element engages with the receiving recess. A rotating shaft is configured to rotate relative to the guide; and The engaging component protrudes radially from the front end of the rotating shaft and engages with the gas outlet groove.

8. An installation method, characterized in that, The first electrode tip is mounted relative to the first electrode body using the mounting clamp as described in claim 7. The installation method includes: The step of fitting the guide member into the receiving recess; The steps of engaging the engaging component with the gas outlet groove; and The step of rotating the rotating shaft relative to the guide.

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