Kiln waste gas regeneration device and system and kiln system

Abstract

Provided is a kiln exhaust gas regeneration device that regenerates a gas mixture containing a rare gas and an inclusion gas into a reusable gas, the mixture gas being discharged from a kiln that heats a metal storing the inclusion gas and uses an atmosphere containing the rare gas to release the inclusion gas from the metal. The kiln waste gas regeneration device comprises a rare gas extraction mechanism, a gas conversion system receives a gas mixture comprising a rare gas and an inclusion gas discharged from the above kiln and converts the received gas mixture to a gas having an increased concentration of the rare gas using filters having different permeabilities between the inclusion gas and the rare gas and / or fuel cells oxidizing the inclusion gas. In this case, the rare gas is preferably argon. In addition, preferably, the kiln waste gas regeneration device comprises a rare gas delivery mechanism which is used for delivering the gas with the increased rare gas concentration to the kiln or a gas storage tank of the kiln, so that the gas is reused as the atmosphere.

Description

Technical Field

[0001] The present invention relates to a technology for treating gases discharged from a kiln.

[0002] Priority is claimed on Japanese Patent Application No. JP 2023-003071, filed on Jan. 12, 2023, the content of which is incorporated herein by reference in accordance with PCT Rule 20.6. Background Art

[0003] In recent years, rare-earth magnets such as neodymium-iron-boron (Nd-Fe-B) magnets have become important materials essential for manufacturing electric drive systems such as electric motors of electric vehicles, and the demand for such magnets is expected to further increase in the upcoming carbon-neutral society. Such rare-earth magnets are generally manufactured by: (a) coarsely crushing an as-cast alloy block containing rare-earth elements, metal elements, and boron produced by a melting method, (b) making (fine-crushing) it into alloy powder by using a jet mill or the like, and then subjecting the alloy powder to (c) compression molding in a magnetic field, (d) sintering and heat-treating the molded body, and (e) performing various types of treatments. Here, the above-mentioned (a) crushing (coarse crushing) of the as-cast alloy block is quite time-consuming, resulting in a problem of reduced overall productivity.

[0004] To solve this problem, for example, PTL 1 discloses an apparatus for manufacturing coarsely crushed alloy powder by allowing the above-mentioned as-cast alloy block to occlude hydrogen and then heat-treating and crushing the as-cast alloy block. Generally, rare-earth alloys containing rare-earth elements have the property of occluding a large amount of hydrogen. When an as-cast alloy block that has occluded a large amount of hydrogen is heated, further expansion occurs, and at the same time, the bonding strength between metal atoms is weakened due to the presence of hydrogen atoms. As a result, cracks appear in the as-cast alloy block, and self-destruction is promoted to transform into alloy powder.

[0005] The apparatus for manufacturing alloy powder disclosed in PTL 1 is equipped with a rotatable heat-treatment section that heats the alloy powder that has occluded hydrogen and dehydrogenates it, and this heat-treatment section has a gas supply mechanism for introducing argon into the heat-treatment section during heat treatment. When manufacturing alloy powder, the heat-treatment section is rotated, and while introducing argon into the heat-treatment section, the alloy powder that has occluded hydrogen is heated and dehydrogenated. As a result, the hydrogen released from the alloy powder is rapidly discharged together with argon, thereby achieving effective dehydrogenation. List of Cited References Patent Documents

[0006] [PTL 1] Japanese Patent Application Publication No. 2005-163066 Summary of the Invention Technical problem

[0007] Currently, in the manufacture of alloy powders for rare earth magnets, a method of hydrogen occlusion to conversion into alloy powders and dehydrogenation by heating as disclosed in PTL 1 is adopted. Specifically, in a kiln, a raw alloy block occluding hydrogen is roughly pulverized and then heated to several hundred degrees Celsius in an argon atmosphere (non-oxidizing atmosphere) introduced into the kiln for rough pulverization while releasing hydrogen, and then the released hydrogen is discharged to the outside of the kiln together with argon. Incidentally, the roughly pulverized alloy block (i.e., alloy powder) is transferred to the next step in a non-oxidizing atmosphere.

[0008] Here, the argon discharged together with hydrogen is in a state of a gas mixed with hydrogen. Therefore, this argon is difficult to reuse, and conventionally it has been diluted with nitrogen or the like and discharged to the outside and discarded. Therefore, although argon is a noble gas and very expensive, new argon must be introduced for each production cycle, which has been a major obstacle to reducing production costs.

[0009] Therefore, the present invention aims to provide a kiln exhaust gas regeneration device, system, and method for regenerating a mixed gas containing a noble gas and an occluded gas (occluded gas) discharged from a kiln as described above into a reusable gas. The present invention also aims to provide a kiln system for reusing the gas regenerated in this way. Solution to the problem

[0010] According to the present invention, there is provided a kiln exhaust gas regeneration device including a noble gas extraction mechanism configured to receive a mixed gas discharged from a kiln and convert the mixed gas into a gas having an increased noble gas concentration, the mixed gas containing a noble gas and an occluded gas, the kiln heating a metal occluding the occluded gas and releasing the occluded gas from the metal in an atmosphere containing the noble gas, and the noble gas extraction mechanism being configured to convert the mixed gas using: a filter having different permeabilities between the occluded gas and the noble gas; and / or a fuel cell configured to oxidize the occluded gas. It is also preferable that the noble gas is argon.

[0011] It is also preferable that the kiln exhaust gas regeneration device further includes a noble gas delivery mechanism configured to send the gas having an increased noble gas concentration to the kiln or a gas storage tank for the kiln so as to reuse the gas having an increased noble gas concentration as the atmosphere.

[0012] As another embodiment of the kiln waste gas regeneration device according to the present invention, it is further preferred that the rare gas extraction mechanism converts the mixed gas into the gas with an increased rare gas concentration by using the filter and the fuel cell disposed downstream of the outlet of the filtered gas in the filter.

[0013] In addition, in the embodiment just described above, it is further preferred that the rare gas extraction mechanism uses a gas compressor to act on the filter the mixed gas at a high pressure exceeding the atmospheric pressure, and introduces the gas taken out from the outlet of the filtered gas in the filter into the fuel gas chamber of the fuel cell at a high pressure exceeding the atmospheric pressure to oxidize the occluded gas.

[0014] In addition, in the above embodiment, it is further preferred that the rare gas extraction mechanism further uses another filter, which is disposed downstream of the fuel gas chamber of the fuel cell and has different permeabilities between the occluded gas and the rare gas, to convert the mixed gas into the gas with an increased rare gas concentration.

[0015] As another embodiment of the kiln waste gas regeneration device according to the present invention, it is further preferred that the rare gas extraction mechanism uses the fuel cell and the filter disposed downstream of the fuel gas chamber of the fuel cell to convert the mixed gas into the gas with an increased rare gas concentration.

[0016] In addition, in the embodiment just described above (where the filter is disposed downstream of the fuel gas chamber of the fuel cell), it is further preferred that the rare gas extraction mechanism uses a gas compressor to introduce the mixed gas into the fuel gas chamber of the fuel cell at a high pressure exceeding the atmospheric pressure to oxidize the occluded gas, and act on the filter the gas taken out from the fuel gas chamber of the fuel cell at a high pressure exceeding the atmospheric pressure.

[0017] As another embodiment of the filtering method in the present invention, it is further preferred that the rare gas extraction mechanism includes the filter, and the mixed gas acts on the filter at a gas flow rate set to a value for reducing the concentration of the residual occluded gas or within a range of gas flow rate values set to reduce the concentration of the residual occluded gas, and the gas with an increased rare gas concentration is taken out from the filter.

[0018] As another embodiment of the filtering method in the present invention, it is further preferred that the rare gas extraction mechanism includes the filter, and the mixed gas acts on the filter at a gas pressure set to a value for increasing the recovery rate of the rare gas or within a range of gas pressure values set to increase the recovery rate of the rare gas, and the gas with an increased rare gas concentration is taken out from the filter.

[0019] As another embodiment of the filtering method in the present invention, it is further preferred that the rare gas extraction mechanism includes the filter, and the mixed gas acts on the filter at a gas pressure and / or gas flow rate determined as the filtering condition of the filter according to the concentration of the rare gas or the occluded gas in the received mixed gas, and the gas with an increased rare gas concentration is taken out from the filter.

[0020] As another embodiment of the kiln waste gas regeneration device according to the present invention, it is further preferred that the kiln waste gas regeneration device further includes a controller configured to determine which one or both of the filter and the fuel cell to use based on the concentration of the rare gas or the occluded gas in the received mixed gas, based on a preset schedule, or based on an external instruction, and the rare gas extraction mechanism includes the filter and the fuel cell, and the mixed gas is converted into the gas with an increased rare gas concentration by using the determined filter and / or fuel cell.

[0021] In addition, in the embodiment just described above, it is further preferred that based on the concentration of the rare gas or the occluded gas in the received mixed gas, based on a preset schedule, or based on an external instruction, the controller selects a flow path pattern to be used from a group of flow path patterns, the group of flow path patterns including a flow path pattern connecting the filter and the fuel cell downstream thereof, a flow path pattern connecting the fuel cell and the filter downstream thereof, and a flow path pattern including the filter but not including the fuel cell, and the rare gas extraction mechanism includes the filter, the fuel cell, and a flow path switching valve configured to implement each flow path pattern included in the group of flow path patterns, implement the selected flow path pattern, and convert the mixed gas into the gas with an increased rare gas concentration.

[0022] Herein, it is further preferred that the controller first selects the flow path pattern connecting the fuel cell and the filter downstream thereof, and then selects the flow path pattern connecting the filter and the fuel cell downstream thereof.

[0023] In addition, the mixed gas discharged from the kiln received by the rare gas extraction mechanism of the present invention may first have a concentration of the occluded gas higher than the concentration of the rare gas, and then have a concentration of the rare gas higher than the concentration of the occluded gas.

[0024] As another embodiment of the kiln waste gas regeneration device according to the present invention, it is further preferred that the rare gas extraction mechanism includes the filter, the mixed gas acts on the filter, and the gas with an increased concentration of occluded gas is taken out from the outlet of the filtered gas in the filter.

[0025] As another embodiment of the kiln waste gas regeneration device according to the present invention, it is further preferred that the rare gas extraction mechanism converts the mixed gas into the gas with an increased rare gas concentration by using a plurality of filters connected in sequence, wherein the inlets of the second filter and subsequent filters are connected to the outlet of the filtered gas in the previous filter.

[0026] In addition, it is further preferred that the rare gas extraction mechanism of the present invention further includes a buffer tank configured to temporarily store the mixed gas and a blower configured to send the mixed gas to the buffer tank, and the buffer tank and the blower are provided upstream of the gas compressor.

[0027] According to the present invention, there is provided a kiln waste gas regeneration system, which includes a rare gas extraction mechanism configured to receive the mixed gas discharged from the kiln and convert the mixed gas into a gas with an increased rare gas concentration, the mixed gas containing rare gas and occluded gas, the kiln heating the metal containing the occluded gas and releasing the occluded gas from the metal in an atmosphere containing the rare gas, and the rare gas extraction mechanism being configured to convert the mixed gas by using the following: a filter having different permeabilities between the occluded gas and the rare gas; and / or a fuel cell configured to oxidize the occluded gas.

[0028] According to the present invention, there is provided a kiln system, which includes: A kiln configured to heat the metal containing the occluded gas and release the occluded gas from the metal in an atmosphere containing a rare gas; A rare gas extraction mechanism configured to receive the mixed gas discharged from the kiln and containing the rare gas and the occluded gas, and convert the mixed gas into a gas with an increased rare gas concentration by using a filter having different permeabilities between the occluded gas and the rare gas and / or a fuel cell configured to oxidize the occluded gas; and A rare gas delivery mechanism configured to send the gas with an increased rare gas concentration to the kiln or a gas storage tank for the kiln so as to reuse the gas with an increased rare gas concentration as the atmosphere.

[0029] According to the present invention, there is provided a method for regenerating kiln waste gas, which includes: A step of receiving a mixed gas discharged from a kiln, the mixed gas containing a rare gas and an occluded gas, and the kiln heating a metal occluding the occluded gas and causing the occluded gas to be released from the metal in an atmosphere containing the rare gas; and A step of converting the mixed gas into a gas with an increased rare gas concentration by using: a filter having different permeabilities between the occluded gas and the rare gas; and / or a fuel cell configured to oxidize the occluded gas. Advantages of the present invention

[0030] According to the kiln exhaust gas regeneration device, system and method of the present invention, a mixed gas containing a rare gas and an occluded gas (the occluded gas) that has been discharged from a kiln can be regenerated into a reusable gas. The kiln heats a metal that has absorbed the occluded gas and causes the occluded gas to be released from the metal in an atmosphere containing the rare gas. Further, according to the kiln system of the present invention, the gas regenerated in this way can be reused. Description of the drawings

[0031] Figure 1 is a schematic diagram showing an embodiment of the kiln exhaust gas regeneration device / system and the kiln system according to the present invention; Figure 2 (A1) , 2(A2) , 2(B1), 2(B2), 2(C1) and 2(C2) are graphs for illustrating an example of the filtration process according to the present invention; Figure 3 (A) and 3(B) is a table showing the results of measuring the hydrogen concentration at the hydrogen-side outlet in the example shown in Figures 2 (A1) to 2 (C2) ; Figure 4 (A1) , 4(A2) , 4(B), 4(C1) and 4(C2) are graphs for illustrating another example of the filtration process according to the present invention; Figure 5 (A) , 5(B) and 5(C) are schematic diagrams for illustrating respective embodiments of the gas filter arrangement in the filtration unit (U) according to the present invention; Figure 6 is a schematic diagram showing another embodiment of the kiln exhaust gas regeneration device / system according to the present invention; and Figure 7 is a schematic diagram showing yet another embodiment of the kiln exhaust gas regeneration device / system according to the present invention. Detailed description of the invention

[0032] Embodiments for implementing the present invention will be described below with reference to the accompanying drawings. The gas pressure values described below are absolute gas pressure values, where 1 atmosphere (atmospheric pressure) is approximately 0.1 megapascals (MPa).

[0033] [Furnace Exhaust Gas Regeneration Device / System, Furnace System] Figure 1 is a schematic diagram showing an embodiment of a furnace exhaust gas regeneration device / system and a furnace system according to the present invention.

[0034] As an embodiment of the present invention Figure 1 The furnace exhaust gas regeneration device 1 shown in regenerates the furnace exhaust gas discharged from the furnace 91 into a reusable form. This furnace produces alloy powder for rare earth magnets. Here, the rare earth magnet can be, for example, an R-T-B-based permanent magnet such as a neodymium magnet (Nd-Fe-B-based permanent magnet). Such an R-T-B-based permanent magnet is composed of grains having an R2T 14 B-type crystal structure and grain boundaries therebetween. In addition, 'R' in the R-T-B-based permanent magnet represents at least one rare earth element. In addition, 'T' represents iron (Fe), or iron (Fe) and cobalt (Co), but may further represent a metal containing at least one transition metal element selected from those other than iron (Fe) and cobalt (Co). In addition, 'B' represents boron (B), or boron (B) and carbon (C). In addition, the R-T-B-based permanent magnet may contain copper (Cu), aluminum (Al), etc. Adding such elements enables an increase in coercive force, enhancement of corrosion resistance, or improvement of the temperature characteristics of magnetic properties.

[0035] The furnace 91 is a furnace for manufacturing the alloy powder of the above rare earth magnet. Specifically, (a-1) The raw alloy block for the rare earth magnet is occluded with an occluded gas (hydrogen (H2) in the embodiments of the present invention), and this raw alloy block is heated at several hundred degrees Celsius in an atmosphere of an introduced rare gas (argon (Ar) in the embodiments of the present invention) to release the occluded gas (the occluded gas, hydrogen), thereby coarsely pulverizing the raw alloy block in a self-destructive form; (a-2) Then, the released occluded gas (hydrogen) is discharged to the outside of the furnace 91 as furnace exhaust gas together with the rare gas (argon).

[0036] The as-crushed original alloy block in the above (a-1) is, for example, an alloy powder with a diameter of several hundred micrometers (μm), and in the embodiment of the present invention, this alloy powder is recovered in an alloy powder recovery container 93 provided outside the kiln. Then, the recovered alloy powder is finely crushed and further subjected to compression molding, sintering, heat treatment, etc. in a magnetic field to produce a rare earth magnet. It is also possible to directly transfer the alloy powder removed from the kiln 91 to the equipment for fine crushing without passing through the alloy powder recovery container 93.

[0037] Meanwhile, the kiln exhaust gas discharged in the above (a-2) is transferred to a fine powder trap unit (U) 92, where the remaining alloy powder therein is separated and removed, and then the kiln exhaust gas is discharged from the fine powder trap U 92. As described above, such discharged kiln exhaust gas is a mixed gas containing occluded gas (hydrogen) and rare gas (argon). The kiln exhaust gas regeneration device 1 regenerates the kiln exhaust gas into a gas with an increased rare gas (argon) concentration (hereinafter also referred to as a gas with an increased rare gas (argon) concentration).

[0038] Therefore, the kiln exhaust gas regeneration device 1 specifically includes: (A) A rare gas (argon) extraction section (mechanism) 11, which receives the kiln exhaust gas (the kiln exhaust gas is a mixed gas discharged from the kiln 91 and contains rare gas (argon) and occluded gas (hydrogen)), and uses a gas filter 113F and / or a fuel cell 116C (both in Figure 1 ) to convert the kiln exhaust gas into a gas with an increased rare gas (argon) concentration.

[0039] Here, the gas filter 113F (which will be described in detail later) is a filter having different permeabilities between the occluded gas (hydrogen) and the rare gas (argon). By introducing the kiln exhaust gas into this gas filter 113F, at least a part of the occluded gas (hydrogen) is separated from the rare gas (argon), and thus a gas with an increased rare gas (argon) concentration can be taken out.

[0040] In addition, the fuel cell 116C (which will also be described in detail later) is a power generation device that oxidizes the occluded gas (hydrogen) (for example, by converting the occluded gas into an oxide (water) or a positive ion (H + ). By introducing the kiln exhaust gas into this fuel cell 116C, at least a part of the occluded gas (hydrogen) is oxidized and removed from the kiln exhaust gas, enabling the extraction of a gas with an increased rare gas (argon) concentration.

[0041] In addition, by using both such a gas filter 113F and a fuel cell 116C, a gas with an increased concentration of a noble gas (argon) can be generated more effectively, for example, with a higher recovery rate, as will be described in detail later using Figure 1 、 6 and 7. In any case, the kiln exhaust gas regeneration device 1 can regenerate the kiln exhaust gas (which is a mixed gas discharged from the kiln 91 and contains a noble gas (argon) and an occluded gas (hydrogen)) into a reusable gas (a gas with an increased concentration of a noble gas (argon)).

[0042] The kiln exhaust gas regeneration device 1 according to an embodiment of the present invention further includes: (B) A noble gas (argon) delivery section (mechanism) 12 that sends the gas with an increased concentration of the extracted noble gas (argon) to the kiln 91 or a gas storage unit for the kiln 91 (for example, a tank for supplying gas to the kiln 91), so that the gas with an increased concentration of the noble gas (argon) can be reused as a noble gas (argon) atmosphere during the manufacture of alloy powder.

[0043] Therefore, an expensive noble gas (argon) can be reused, which was previously diluted with nitrogen or the like and discharged and discarded to the outside after use. As a result, the use of new noble gas (argon) and nitrogen for dilution can be reduced or eliminated, and the cost of manufacturing alloy powder for rare earth magnets can be reduced. In this case, the kiln exhaust gas regeneration device 1 (noble gas extraction section (argon extraction section) 11, noble gas delivery section (argon delivery section) 12) and the kiln 91 (and possibly also the fine powder collector U 92 and the alloy powder recovery container 93) constitute an embodiment of a kiln system according to the present invention. In this kiln system, the regenerated noble gas (a gas with an increased concentration of a noble gas (argon)) can be reused.

[0044] In addition, when the gas with an increased concentration of the noble gas (argon) is reused in the kiln 91, by making this gas with an increased concentration of the noble gas (argon) a gas with a higher argon concentration (lower hydrogen concentration), the desorption (dehydrogenation) of hydrogen from the raw alloy block can be further promoted, the processing time in the kiln 91 can be shortened, and a more efficient alloy powder manufacturing process can be carried out. In addition, even when expensive pure argon is mixed with the prepared gas with an increased concentration of argon described above in order to obtain the required high purity of argon in such reuse, the amount of pure argon used can be further reduced.

[0045] In addition, when both the gas filter 113F and the fuel cell 116C are used, a mode in which they are provided in separate devices can also be adopted. Additionally, the rare gas delivery section (argon delivery section) 12 can be a component of a device separate from the device including the rare gas extraction section (argon extraction section) 11. In any case, these devices as a whole constitute an embodiment of the kiln exhaust gas regeneration system according to the present invention. The structure of the kiln exhaust gas regeneration device (system) 1 of the embodiment of the present invention will be described in more detail below.

[0046] [Device / System Structure, Kiln Exhaust Gas Regeneration Method] Also as Figure 1 shown, the kiln exhaust gas regeneration device (system) 1 of the embodiment of the present invention includes an argon extraction section (rare gas extraction section) 11, an argon delivery section (rare gas delivery section) 12, and an overall control unit (U) 13. Among these, the argon delivery section 12 has a tank U 121 and a delivery control U 122.

[0047] Furthermore, in the embodiment of the present invention, the argon extraction section 11 includes: (a) A catalytic poison removal U 111; (b) A blower U 112a equipped with a blower 112aa and a buffer tank 112ab, a gas compression U 112b, and a tank U 112c; (c) A filtration U 113 equipped with a gas filter 113F; (d) A pressure control U 114a, a buffer tank U 114b, and an Ar compression U 114c; (e) A buffer tank U 115a, a gas compression U 115b, a tank U 115c, and a gas compression U 115d; (f) A fuel cell U 116 equipped with a fuel cell 116C; (g) A pressure control U 117a, a dehumidification U 117b, and a pressure control U 117c; (h) A filtration U 118 equipped with a gas filter 118F; and (i) A pressure control U 119a, a buffer tank U 119b, and an Ar compression U 119c.

[0048] In addition, the kiln system of the embodiment of the present invention is composed of a kiln exhaust gas regeneration device (system) 1 having these components, a kiln 91, a fine powder collector U 92, and an alloy powder recovery container 93. Incidentally, the transfer of materials and energy and the process flow of the processes performed (by connecting with arrows Figure 1The component shown in the device / system configuration diagram (which can also be understood as an embodiment of the method for regenerating furnace exhaust gas according to the present invention).

[0049] In addition, although such an embodiment is different from the embodiments of the present invention, the argon extraction section 11 may have a filter U113 and component sections (111 to 114c) arranged before and after the filter U113, while not having (omitting) the fuel cell U116 and the component sections (115a to 119c, Figure 1 the gray area in). Even in such an embodiment, the furnace exhaust gas can be regenerated into a gas with an increased concentration of reusable argon.

[0050] <Rare gas extraction configuration: upstream of filter U113> Similarly in Figure 1 the catalytic poison removal unit U111 removes catalytic poisons (which poison the catalyst to be used later in the fuel cell 116C) from the furnace exhaust gas (a mixed gas containing argon (rare gas) and hydrogen (occluded gas)) discharged from the furnace 91 (fine powder trap U92). Specifically, in the embodiment of the present invention, the catalytic poison removal unit U111 uses an oxidation catalyst or a selective oxidation catalyst to remove carbon monoxide (CO) gas, which is a catalytic poison, from the furnace exhaust gas. In fact, it has been confirmed that carbon monoxide (CO) gas is mainly removed from the furnace exhaust gas at a temperature of 90 °C using a metal honeycomb body (model D3PT2S40C) manufactured by Tanaka Kikinzoku Kogyo Co., Ltd. In addition, the catalytic poison removal unit U111 may further include equipment for removing substances harmful to the gas filter 113F.

[0051] Here, it is also preferable to provide a fine powder trap mechanism or a fine powder filter mechanism upstream of the catalytic poison removal unit U111 to remove the remaining rare earth magnet fine powder in the furnace exhaust gas. This makes it possible to prevent the fine powder from adversely affecting the subsequent filtration process and fuel cell reaction process.

[0052] Similarly as Figure 1 shown, in the embodiment of the present invention, the blower U112a uses the blower 112aa to temporarily store the furnace exhaust gas from which the catalytic poison has been removed in the buffer tank 112ab at a static pressure (>0.1 MPa), and then transfers the furnace exhaust gas to the gas compression U112b. In this way, by temporarily storing the furnace exhaust gas in the buffer tank 112ab using the blower 112aa, fluctuations in the gas pressure (of the mixed gas) inside the furnace 91 can be suppressed.

[0053] Here, it is actually known that when the gas pressure inside the furnace 91 fluctuates significantly, the particle size and comminution characteristics of the produced alloy powder will change, making it difficult to stably perform subsequent fine comminution, molding, sintering, and heat treatment. To solve this problem, the furnace exhaust gas is temporarily stored in the buffer tank 112ab by using the blower 112aa, so that the outlet pressure of the furnace exhaust gas discharged from the furnace 91 (fine powder trap U 92) can be stabilized to a substantially constant value, thereby suppressing the fluctuation of the gas pressure inside the furnace 91.

[0054] Incidentally, the outlet pressure of the furnace 91 (fine powder trap U 92) can be set to a value, for example, in the range of 0.080 MPa to 0.110 MPa (about 0.790 atm to 1.086 atm). In addition, the deviation from this set value is preferably maintained within ±0.02 MPa, more preferably within ±0.01 MPa, and even more preferably within ±0.005 MPa.

[0055] Specifically, the blower 112aa is preferably an inverter-controlled blower that can adjust the blower capacity in response to fluctuations in the flow rate of the furnace exhaust gas discharged from the furnace 91 (fine powder trap U 92) so as to keep the outlet pressure of the furnace exhaust gas as constant as possible as described above. It is also preferable to switch between a plurality of blowers with different blower capacities (for example, two blowers, namely a large blower with a blower capacity of 3 m 3 / min or more and a small blower with a blower capacity of 0.5 m 3 / min or more) depending on the flow rate of the furnace exhaust gas. Of course, these blowers can also be inverter-controlled blowers.

[0056] Also in Figure 1 the gas compression U 112b receives the furnace exhaust gas from the blower U 112a (buffer tank 112ab), and after pressurizing the received furnace exhaust gas using a set compressor (compatible with hydrogen and argon), transfers the furnace exhaust gas to the mixed gas tank provided in the tank U 112c. As a result, in the embodiment of the present invention, the furnace exhaust gas is stored in this mixed gas tank at a high gas pressure of, for example, 1.1 MPa or slightly lower. In the case where the compressor of the gas compression U 112b is compatible with negative pressure and is an inverter-controlled compressor that can also handle fluctuations in the inlet flow rate, the above-mentioned blower U 112a can be omitted.

[0057] In addition, in the embodiments of the present invention, the tank U 112c transfers the furnace exhaust gas (a mixed gas containing argon and hydrogen) stored in the mixed gas tank to the filter U 113, while adjusting the flow rate with the provided gas regulator and mass flow controller (or flow switch). Here, in the embodiments of the present invention, the gas pressure of the furnace exhaust gas introduced into the filter U 113 is controlled to be 0.3 MPa to 0.9 MPa by the pressure control U 114a (provided downstream of the filter U 113) described later. It is also preferable that the tank U 112c is equipped with a hydrogen concentration meter (or argon concentration meter) ArH, which can measure the hydrogen concentration (or argon concentration) of the mixed gas stored in the mixed gas tank. The hydrogen concentration (argon concentration) measured here is used, for example, to set the filtration conditions in the filtration process performed by the gas filter 113F described below.

[0058] <Rare gas extraction configuration: Filter U 113> Also in Figure 1 the filter U 113 uses the provided gas filter 113F to convert the introduced furnace exhaust gas into a gas with an increased argon concentration that can be reused, which is high-purity argon in the embodiments of the present invention.

[0059] In the embodiments of the present invention, the gas filter 113F is provided with: (a) A filter inlet 113Fc for receiving the high-pressure (0.3 MPa to 0.9 MPa in the embodiments of the present invention) furnace exhaust gas (a mixed gas containing argon and hydrogen) and introducing the received gas into the hollow fiber 113Fd as described below; (b) A hollow fiber 113Fd having different permeabilities between argon (Ar) and hydrogen (H2); (c) An argon-side outlet 113Fa, which is an outlet for the gas that has passed through the hollow fiber 113Fd (high-purity argon in the embodiments of the present invention); and (d) A hydrogen-side outlet 113Fb, which is an outlet for the gas that has permeated through the hollow fiber 113Fd (i.e., the filtered gas).

[0060] Among these, the hollow fiber 113Fd in the above (b) is a hollow polymer fiber that preferentially transports hydrogen molecules (H2) over argon atoms (Ar). When the high-pressure (0.3 MPa to 0.9 MPa) furnace exhaust gas flows through the hollow fiber 113Fd from the filter inlet 113Fc, the hydrogen molecules selectively permeate through the polymer fiber and leave, so that a gas with an increased argon concentration that can be reused (which is high-purity argon in the embodiments of the present invention) can finally be taken out from the argon-side outlet 113Fa.

[0061] Incidentally, it has been confirmed that the UBE N2 separator manufactured by UBE Corporation (formerly Ube Industries Co., Ltd.) and using aromatic polyimide hollow fibers or the N2 membrane module nitrogen gas filter manufactured by Polyplastics-Evonik Corporation and also using aromatic polyimide hollow fibers (both of which are essentially filters for nitrogen) can be used as the gas filter 113F (which is a filter for argon).

[0062] will be used Figures 2 (A1) to 2 (C2) 、 Figure 3 (A) and 3(B) 、as well as Figures 4 (A1) to 4 (C2) to describe an example of filtering hydrogen from a mixed gas equivalent to furnace exhaust gas. In the example shown in these figures, the above-mentioned UBE N2 separator (2-inch diameter) is used as the gas filter 113F.

[0063] The furnace exhaust gas discharged from the furnace 91 is usually a mixed gas in which the concentration of hydrogen (occluded gas) is initially higher than that of argon, and then the concentration of argon becomes higher than that of hydrogen (occluded gas). In fact, in the furnace 91, a large amount of occluded hydrogen is initially released from the coarsely crushed raw alloy block. As a result, the concentration (proportion) of hydrogen in the furnace exhaust gas is 90 vol% or more (i.e., argon is 10 vol% or less).

[0064] In the case where the amount of hydrogen released therefrom decreases, the amount of argon introduced to further discharge hydrogen from the raw alloy block increases, and finally the concentration (proportion) of hydrogen in the furnace exhaust gas becomes 10 vol% or less (i.e., argon becomes 90 vol% or more).

[0065] The filtering conditions (gas pressure, gas flow rate, etc.) in the filtering process are designed to appropriately extract argon from the furnace exhaust gas, in which the hydrogen concentration (hydrogen concentration) fluctuates over time. In the following examples, these suitable filtering conditions are specifically shown.

[0066] Figure 2 (A1) 、 2(A2) 、2(B1), 2(B2), 2(C1) and 2(C2) are graphs for clarifying an example of the filtering process according to the present invention.

[0067] Figures 2 (A1) to 2 (C2) Shows the results obtained when (a) Each of a mixed gas (argon (Ar): hydrogen (H2) = 30 vol%: 70 vol%) (which is assumed to correspond to the furnace exhaust gas discharged in the first half of the process in furnace 91) and a mixed gas (argon (Ar): hydrogen (H2) = 70 vol%: 30 vol%) (which is assumed to correspond to the furnace exhaust gas discharged in the second half) is introduced into the filter inlet 113Fc of the gas filter 113F; (b) A filtration process is performed, in which each mixed gas is made to act on the hollow fiber 113Fd under each condition of an outlet pressure having values of 0.4 MPa and 0.7 MPa (the gas pressure at the argon-side outlet 113Fa) and an outlet flow rate having values of 1.0 liter (L) / minute, 3.0 L / min, and 5.0 L / min (the gas flow rate at the argon-side outlet 113Fa); and (c) The dependence of the residual hydrogen concentration (ppm, parts per million by volume) on the elapsed treatment time is investigated, where the residual hydrogen concentration is the hydrogen concentration in the gas taken out from the argon-side outlet 113Fa.

[0068] According to Figure 2 (A1) 、 2(B1) and 2(C1), when the outlet pressure is 0.4 MPa, for all mixed gases, the smaller the outlet flow rate, the smaller the asymptotic value of the residual hydrogen concentration (hydrogen concentration asymptotic value) during the elapsed treatment time. In addition, for each outlet flow rate, the mixed gas (Ar:H2 = 70 vol%: 30 vol%) shows a smaller hydrogen concentration asymptotic value than the mixed gas (Ar:H2 = 30 vol%: 70 vol%). Incidentally, when the outlet flow rate is 1.0 L / min, the hydrogen concentration asymptotic value of the mixed gas (Ar:H2 = 70 vol%: 30 vol%) is below the measurement limit of the concentration meter ArH and cannot be measured.

[0069] Furthermore, according to Figure 2 (A2) 、 2(B2) and 2(C2), even when the outlet pressure is 0.7 MPa, the hydrogen concentration asymptotic value also becomes smaller as the outlet flow rates of the two mixed gases decrease. In addition, this hydrogen concentration asymptotic value is smaller than the hydrogen concentration asymptotic value when the outlet pressure is 0.4 MPa and the outlet flow rates are the same (i.e., the higher the outlet pressure, the smaller the residual hydrogen concentration).

[0070] In addition, when the outlet pressure is 0.7 MPa, which is different from when the outlet pressure is 0.4 MPa, the asymptotic values of the hydrogen concentration of the mixed gas (Ar:H2 = 30 vol%:70 vol%) and the asymptotic values of the hydrogen concentration of the mixed gas (Ar:H2 = 70 vol%:30 vol%) are substantially the same at each outlet flow rate. Incidentally, when the outlet flow rate is 1.0 L / min, the asymptotic values of the hydrogen concentration of both mixed gases are lower than the measurement limit of the concentration meter ArH and cannot be measured.

[0071] Based on the above results, it can be understood that it is also preferable to perform the filtration treatment under the following filtration conditions: (a1) When the outlet pressure is set relatively low (for example, 0.4 MPa as described above), in the initial stage when the hydrogen concentration of the furnace exhaust gas is relatively high, the filtration treatment is performed at the minimum possible outlet flow rate in order to achieve the target (or required) sufficiently low residual hydrogen concentration; and (a2) Thereafter, within the range where the target (or required) sufficiently low residual hydrogen concentration can be achieved, according to the continuously decreasing hydrogen concentration value in the furnace exhaust gas (or according to the elapsed treatment time), the outlet flow rate is gradually (or continuously) increased to a sufficiently large value as desired.

[0072] In addition, as another filtration condition, it can be understood that: (b) When the outlet pressure is set sufficiently high (for example, 0.7 MPa as described above), it is also preferable to set the outlet flow rate to a sufficiently large value as desired within the range where the target (or required) sufficiently low residual hydrogen concentration can be achieved, regardless of the fluctuation of the hydrogen concentration of the furnace exhaust gas. In any case, it is also preferable to set the outlet pressure to a relatively large value within the settable range.

[0073] As clarified above, the filtration U 113 determines the outlet pressure and / or the outlet flow rate as the filtration conditions based on the (time-varying) concentration of argon or hydrogen in the received furnace exhaust gas, and performs the filtration treatment on the furnace exhaust gas at the determined outlet pressure and / or outlet flow rate to produce high-purity argon with a target (or required) sufficiently low residual hydrogen concentration.

[0074] In other words, the filtration U 113 performs the filtration treatment on the furnace exhaust gas at a gas flow rate set to reduce the residual hydrogen concentration or within a range of gas flow rate values set to reduce the residual hydrogen concentration (a sufficiently large gas flow rate as desired), which enables the production of high-purity argon with a target (or required) sufficiently low residual hydrogen concentration. It is also preferable that during this filtration treatment, the outlet pressure is set to a relatively large value within the settable range.

[0075] Incidentally, in the example of the present invention, when the outlet pressure is set to 0.4 MPa, for example, in the first half of the process in the kiln 91 (e.g., when the hydrogen concentration in the kiln exhaust gas is 70 vol%), the outlet flow rate is maintained at about 3.0 L / min, and in the second half of the process (e.g., when the hydrogen concentration in the kiln exhaust gas is 30 vol%), the outlet flow rate increases to about 5.0 L / min, so that high-purity argon gas with a residual hydrogen concentration in the range of 10 3 ppm can be always produced. Additionally, for example, when the outlet pressure is set to 0.7 MPa, even if the outlet flow rate is always set to a large value of 5.0 L / min, high-purity argon gas with a residual hydrogen concentration in the range of 10 1 ppm can be produced.

[0076] Figure 3 (A) and 3(B) are tables showing the results of measuring the hydrogen concentration at the hydrogen-side outlet 113Fb in the example shown in Figures 2 (A1) to 2 (C2) . Here, as described above, the gas that has permeated the hollow fiber 113Fd (i.e., the filtered gas) is discharged from the hydrogen-side outlet 113Fb of the gas filter 113F. Fig. 3(A) shows the hydrogen concentration of this filtered gas when the (argon-side) outlet pressure is 0.4 MPa. Fig. 3(B) shows the hydrogen concentration of this filtered gas when the (argon-side) outlet pressure is 0.7 MPa.

[0077] According to Fig. 3(A), under the condition that the outlet pressure is 0.4 MPa, the hydrogen concentration of the filtered gas generated from the mixed gas (Ar:H2 = 30 vol%:70 vol%) increases from 70.7 vol% (approximately equal to 70 vol% of the original mixed gas) to 92.0 vol% as the (argon-side) outlet flow rate increases in the order of 0, 1.0, 2.0, 3.0, 5.0, and 10.0 L / min. In addition, the hydrogen concentration of the filtered gas generated from the mixed gas (Ar:H2 = 30 vol%:70 vol%) also shows a similar trend regarding the increase in the (argon-side) outlet flow rate.

[0078] Furthermore, as shown in Fig. 3(B), even under the condition that the outlet pressure is 0.7 MPa, the hydrogen concentration of each filtered gas also shows a similar trend regarding the increase in the (argon-side) outlet flow rate. Incidentally, Figure 3 (A) and 3(B) the (argon-side) outlet flow rate of "0" in means that the argon-side outlet 113a of the gas filter 113F is blocked and then the mixed gas is introduced into the gas filter 113F. When the outlet pressure is 0.7 MPa, at the same outlet flow rate, the hydrogen concentration of each filtered gas is less than that when the outlet pressure is 0.4 MPa.

[0079] According to Figure 3 (A) and 3(B) the results shown in, since hydrogen selectively passes through the hollow fiber 113Fd, the hydrogen concentration in the filtered gas is higher than that in the original mixed gas (70 vol%, 30 vol%), and the difference becomes larger as the outlet flow rate is higher. However, it is also understandable that due to the characteristics of the hollow fiber 113Fd (gas filter 113F), the filtered gas contains a considerable amount of argon. Therefore, in the embodiment of the present invention, the fuel cell U 116 is used to further recover the argon contained in this filtered gas, as will be described in detail later.

[0080] Herein, the use of Figure 4 (A1) 、 4(A2) 、4(B), 4(C1) and 4(C2) will illustrate the examples implemented to find the filtration conditions for reducing the argon concentration in the filtered gas. Figures 4 (A1) to 4 (C2) is a graph for illustrating another example of the filtration process according to the present invention.

[0081] Herein, Figure 4 (A1) and 4(B) are graphs showing the dependencies of the argon emission ratios from the argon-side outlet 113Fa on the (argon-side) outlet flow rate and the (argon-side) outlet pressure, respectively. The argon introduced into the hollow fiber 113Fd from the filter inlet 113Fc (in the mixed gas) is discharged from either the argon-side outlet 113Fa or the hydrogen-side outlet 113Fb. The argon emission ratio from the argon-side outlet 113Fa refers to the ratio of the argon discharged from the argon-side outlet 113Fa.

[0082] In addition, in Fig. 4(C2), the hydrogen emission ratio from the hydrogen-side outlet 113Fb is the ratio of the hydrogen (in the mixed gas) discharged from the hydrogen-side outlet 113Fb. In addition, the emission ratios in the remaining figures are quantities that can be determined in the same manner. Incidentally, in the example of the present invention, a mixed gas (Ar:H2 = 50 vol%:50 vol%) is used as the mixed gas introduced into the gas filter 113F.

[0083] According to Fig. 4(A1), the argon emission ratio from the argon-side outlet 113Fa increases as the outlet flow rate increases. Additionally, among the cases where the outlet pressure is 0.4, 0.5, 0.6, and 0.7 MPa, the emission ratio is the highest when the outlet pressure is 0.5 MPa. At the same time, not unexpectedly, the argon emission ratio from the hydrogen-side outlet 113Fb shows a reverse result with respect to the above results, as shown in Fig. 4(A2).

[0084] Here, FIG. 4(B) shows how the argon discharge ratio from the argon-side outlet 113Fa is the highest when the outlet pressure is 0.5 MPa. Incidentally, in this figure, the outlet flow rate is 10.3 L / min, but as can be seen from FIG. 4(A1), for other outlet flow rate values (except 0.1 L / min), the curve will be substantially the same.

[0085] As can be understood from FIG. 4(B), under the condition that the outlet flow rate is 10.3 L / min, when the outlet pressure is 0.5 MPa, the argon discharge ratio from the argon-side outlet 113Fa is 100%. In other words, under these conditions, (almost) 100% of the argon can be recovered from the argon-side outlet 113Fa. Additionally, it should be understood that such an outlet flow rate range of approximately 10.3 L / min and such an outlet pressure range of approximately 0.5 MPa can be specified and set so that the recovery rate of argon from the argon-side outlet 113Fa becomes, for example, 99% or higher.

[0086] Furthermore, under the above-mentioned conditions of the outlet flow rate and the outlet pressure, the filtered gas discharged from the hydrogen-side outlet 113Fb is (almost) 100% hydrogen, or high-purity hydrogen mixed with, for example, 1% or less of argon in terms of the discharge ratio. Therefore, in this case, high-purity hydrogen can also be recovered from the hydrogen-side outlet 113Fb and reused, for example, as the occluding gas to be occluded in the original alloy block.

[0087] In addition, by reusing the filtered gas with a higher hydrogen concentration (lower argon concentration) in the kiln 91, it is also possible to promote the occlusion of hydrogen (hydrogen absorption) into the original alloy block, shorten the processing time in the kiln 91, and perform a more efficient alloy powder manufacturing process. Moreover, in such reuse, even when the pre-prepared expensive pure hydrogen is mixed with the above-mentioned filtered gas to obtain the required high-purity hydrogen, the amount of such pure hydrogen used can be reduced.

[0088] In summary, the filter U 113 filters the kiln exhaust gas at a gas pressure set to increase the argon recovery rate (the ratio of argon discharged from the argon-side outlet 113Fa) or within a gas pressure value range set to increase the argon recovery rate, so that argon can be recovered with a sufficiently high target (or required) recovery rate (to take out the gas with an increased argon concentration). In this case, by increasing the outlet flow rate as much as possible, a high argon recovery rate, such as close to 100%, can also be achieved.

[0089] In addition, the filtration U 113 can also cause the furnace exhaust gas to act on the gas filter 113F, and cause the gas with an increased hydrogen concentration to be taken out from the hydrogen-side outlet 113b. In particular, in this case, by performing the filtration treatment under the above filtration conditions for increasing the argon recovery rate, high-purity hydrogen that can be reused can also be recovered.

[0090] Next, Figure 4 (C1) and 4(C2) will be used to clarify the hydrogen emission ratio (at the argon-side outlet 113Fa and the hydrogen-side outlet 113Fb). According to FIG. 4(C1), the hydrogen emission ratio from the argon-side outlet 113Fa becomes lower as the outlet flow rate becomes smaller and as the outlet pressure becomes higher. At the same time, not unexpectedly, the hydrogen emission ratio from the hydrogen-side outlet 113Fb shows the opposite result to the above result, as shown by FIG. 4(C2).

[0091] Therefore, in the case where the outlet flow rate increases, as can be seen from the results shown in Figure 4 (A1) and 4(A2) , the recovery rate of argon (from the argon-side outlet 113Fa) increases, but at the same time, the amount of hydrogen discharged from the argon-side outlet 113Fa increases. In addition, regarding the outlet pressure, the amount of hydrogen discharged from the argon-side outlet 113Fa is not minimized at the outlet pressure that maximizes the argon recovery rate.

[0092] Based on the above, it should be understood that by performing the filtration treatment, for example, under the following filtration conditions: (a) at the outlet pressure within the pressure range that maximizes the recovery rate of argon from the argon-side outlet 113Fa (for example, the range of about 0.5 MPa shown in FIG. 4(B)); and (b) in the case of the maximum outlet flow rate among the outlet flow rates at which the hydrogen concentration of the gas discharged from the argon-side outlet 113Fa drops below the target (or required) upper limit value (for example, 1.0×10 3 ppm), as much high-purity argon as possible can be produced with a high recovery rate.

[0093] In addition, when further recovering argon using the fuel cell 116C, as in the embodiment of the present invention, it is also preferable to give priority to reducing the hydrogen concentration in the filtration U 113 and performing the filtration treatment at the outlet flow rate of the above (b) under the highest possible outlet pressure. At the same time, in another embodiment where argon is only recovered through the gas filter 113F without using the fuel cell 116C, it is possible to give priority to increasing the recovery rate and performing the filtration treatment at the largest possible outlet flow rate under the outlet pressure of the above (a).

[0094] Figure 5 (A) 、 5(B) and 5(C) are schematic diagrams for illustrating various embodiments of the gas filter arrangement in the filter U 113 according to the present invention.

[0095] Figure 5(A) shows the arrangement of a gas filter 133F (as described above). The filter U 113 can be used for filtration in this way with one gas filter 133F, but it is also preferred to perform the filtration by arranging and connecting two or three or more gas filters in parallel, as shown in Figure 5(B), in order to filter a larger amount (flow rate) of furnace exhaust gas.

[0096] Specifically, in the embodiment shown in Figure 5(B), three gas filters 113F1, 113F2, and 113F3 are provided. The (high-pressure) furnace exhaust gas is separated and introduced into each gas filter (113F1, 113F2, 113F3), and the gas taken out from the argon-side outlet of the gas filters (113F1, 113F2, 113F3) is combined to form a gas with an increased argon concentration, which is high-purity argon in the embodiment of the present invention. Here, the gas discharged from the hydrogen-side outlet of the gas filters (113F1, 113F2, 113F3) is also combined and then processed as the above-mentioned filtered gas.

[0097] By filtering the furnace exhaust gas using a plurality of gas filters arranged in parallel in this way, the outlet flow rate of each gas filter can be reduced while maintaining the desired large total outlet flow rate, and thereby the hydrogen concentration of the gas discharged from the argon-side outlet can be suppressed to a target (or required) small value.

[0098] Here, an example performed on the embodiment shown in Figure 5(B) will be described. In the above-mentioned Figures 2 (A1) to 2 (C2) 、 Figure 3 (A) and 3(B) as well as Figures 4 (A1) to 4 (C2)In the example shown, a gas filter (UBE N2 separator) equipped with aromatic polyimide hollow fibers having a diameter of 2 inches was used. In contrast, a gas filter equipped with aromatic polyimide hollow fibers having a diameter of 4 inches (a nitrogen filter manufactured by Polyplastics Evonik Corporation) was used as a gas filter capable of achieving the same effect as the parallel arrangement of the gas filter in Fig. 5(B), and hydrogen was filtered from a mixed gas equivalent to furnace exhaust gas. Specifically, the mixed gas (Ar:H2 = 70 vol%:30 vol%) was introduced into a 4-inch gas filter 113F (manufactured by Polyplastics Evonik Corporation), and the hydrogen concentration of the gas (high-purity argon) discharged from the argon-side outlet 113Fa was measured.

[0099] As a result, it was found that the hydrogen concentration decreased as the outlet pressure increased and the outlet flow rate decreased, similar to the above example ( Figures 2 (A1) to 2 (C2) ). However, because large-diameter (4-inch diameter) hollow fibers 113Fd were used, high-purity argon with a very low hydrogen concentration of about 1 ppm could be taken out from the argon-side outlet 113Fa even at a relatively low (argon-side) outlet pressure of 0.28 MPa and a relatively large (argon-side) outlet flow rate of 10 L / min, for example.

[0100] As yet another embodiment, as shown in Fig. 5(C), the filtration treatment can also be carried out by connecting two, or three or more (four in Fig. 5(C)) gas filters in a multi-stage cascade. Specifically, in the embodiment shown in Fig. 5(C), furnace exhaust gas was introduced into the first-stage gas filter 113F1, then the gas (filtered gas) discharged from the hydrogen-side outlet of this gas filter 113F1 was introduced into the second-stage gas filter 113F2, then the gas (filtered gas) discharged from the hydrogen-side outlet of this gas filter 113F2 was introduced into the third-stage gas filter 113F3, then the gas (filtered gas) discharged from the hydrogen-side outlet of this gas filter 113F3 was introduced into the fourth-stage gas filter 113F4, and the gas discharged from the hydrogen-side outlet of this gas filter 113F4 was treated as the above-mentioned filtered gas.

[0101] In addition, the gases taken out from the gas filters (113F1, 113F2, 113F3, 113F4) are combined to form a gas with an increased argon concentration, which is high-purity argon in the embodiment of the present invention. In this way, by filtering the kiln exhaust gas using a plurality of gas filters arranged in cascade, argon can be further taken out (extracted) from the gas discharged from the hydrogen-side outlet at a larger outlet flow rate or the maximum outlet flow rate among the outlet flow rates at which the hydrogen concentration drops below the target (or required) upper limit value, and as a result, the recovery rate of argon from the kiln exhaust gas can be increased.

[0102] Herein, a specific example of the recovery rate of argon when the embodiment shown in Fig. 5(C) is adopted will be described. Incidentally, the recovery rate of argon is calculated below as the ratio of (a) the argon-side outlet flow rate of argon (= (the gas flow rate at the argon-side outlet) × (the argon concentration at the argon-side outlet)) to (b) the inlet flow rate of argon (= (the gas flow rate at the inlet) × (the argon concentration at the inlet)).

[0103] First, the following specific example will be described, in which each of the above-mentioned 4-inch diameter nitrogen filters manufactured by Polyplastics Evonik Co., Ltd. is used as the gas filter (113F1, 113F2, 113F3, 113F4) in the embodiment shown in Fig. 5(C). Through this nitrogen filter, it is known that, for example, when the inlet pressure is 0.32 MPa and the inlet flow rate of argon is within a predetermined range, the recovery rate of argon is approximately 0.34 (about 34%). Therefore, in this specific example, the inlet pressure and inlet flow rate of each gas filter (113F1, 113F2, 113F3, 113F4) are adjusted by using buffer tanks and compressors installed before and after these gas filters, so that the recovery rate of argon for each gas filter (113F1, 113F2, 113F3, 113F4) is set to approximately 34%.

[0104] In this case, the proportion of the argon recovered from the argon-side outlet of the four-stage gas filters (113F1, 113F2, 113F3, 113F4) to the argon introduced into the gas filter 113F1 (i.e., the recovery rate of this four-stage structure) reaches approximately 81%.

[0105] Next, a specific example of using the above-described 2-inch diameter UBE N2 separator as each gas filter (113F1, 113F2, 113F3, 113F4) in this four-stage structure will be elucidated. Through this nitrogen filter, it is known that the argon recovery rate is approximately 60% under predetermined conditions. Therefore, also in this specific example, the inlet pressure and inlet flow rate of each gas filter (113F1, 113F2, 113F3, 113F4) are adjusted by using buffer tanks and compressors installed before and after these gas filters, such that the recovery rate of argon in each gas filter (113F1, 113F2, 113F3, 113F4) is set to approximately 60%.

[0106] In this case, the recovery rate of this four-stage structure reaches approximately 97%. Furthermore, the recovery rates of the three-stage structure and the two-stage structure using the same nitrogen filter (UBE N2 separator with a 2-inch diameter) are also high, approximately 94% and approximately 84% respectively. Here, the fewer the number of stages, the lower the introduction cost, and the easier it is to adjust the pressure and flow rate.

[0107] Specific examples of increasing the recovery rate of argon by using a gas filter having a multi-stage cascade structure have been elucidated above. Here, in the case where the target (or required) recovery rate (e.g., 90%) is not achieved, it is also preferable to use the fuel cell U116 to further extract and recover argon from the filtered gas taken out from this multi-stage cascade structure, as will be elucidated later.

[0108] <Noble gas extraction configuration: downstream of filtration U 113> Return Figure 1 , in the embodiment of the present invention, the pressure control U 114a provided downstream of the filtration U 113 is equipped with a back pressure valve and a pressure gauge, and controls the outlet pressure of the gas with an increased argon concentration (high-purity argon in the embodiment of the present invention) discharged from the argon-side outlet 113Fa of the gas filter 113F, and thus controls the gas pressure of the furnace exhaust gas introduced into the filtration U 113.

[0109] Then, the high-purity argon (gas with an increased argon concentration) that has passed through the pressure control U 114a is temporarily held in an argon buffer tank provided in the buffer tank U 114b (where the internal tank pressure is, for example, about 0.2 MPa), and then pressurized by a compressor (compatible with argon) provided in the Ar compression U 114c, and thus transferred to an argon tank provided in the tank U 121, where it is stored.

[0110] The above-described filtration process for filtering hydrogen in U 113 is described. The following clarifies the conversion of the filtered gas taken out from the gas filter 113F into a gas with an increased argon concentration (high-purity argon in the following embodiments) by using the fuel cell 116C.

[0111] <Rare gas extraction configuration: Upstream of the fuel cell U 116> Also in Figure 1 , the filtered gas (a mixed gas containing argon and hydrogen) discharged from the hydrogen-side outlet 113Fb of the gas filter 113F is temporarily held in a mixed gas buffer tank (tank internal pressure: for example, about 0.2 MPa) provided in the buffer tank U 115a, and then pressurized by a compressor (compatible with argon and hydrogen) provided in the gas compressor U 115b, and thus transferred to a gas tank for the mixed gas provided in the tank U 115c, where it is stored.

[0112] Then, in the embodiment of the present invention, this stored mixed gas is transferred to the fuel gas chamber-side inlet of the fuel cell U 116 at a high gas pressure of 0.2 MPa to 1.0 MPa. Here, this gas pressure is controlled by a pressure controller U117a (downstream of the fuel cell U 116) described later. In addition, when the gas is transferred to the fuel gas chamber-side inlet, the gas flow rate is controlled by a gas regulator and a mass flow controller (or flow switch) provided in the tank U 115c.

[0113] Also in Figure 1 , in the embodiment of the present invention, the gas compressor U 115d sucks in air from the atmosphere, for example, and transfers the air to the oxidizing gas chamber-side inlet of the fuel cell U 116 at a high gas pressure of 0.2 MPa to 1.0 MPa by means of the provided compressor. In addition, of course, the compressed air can be first stored in the provided air tank before being transferred to the fuel cell U116.

[0114] <Rare gas extraction configuration: Fuel cell U 116> Also in Figure 1 , in the fuel cell U 116, the fuel cell 116C is used to oxidize hydrogen (H2) in the mixed gas (containing argon and hydrogen) introduced into the fuel gas chamber (for example, into water (H2O) or positive ions (H + )), thereby converting the introduced mixed gas into a gas with an increased argon concentration (or high-purity argon).

[0115] More specifically, in the fuel cell U 116 of the embodiment of the present invention, (a) The mixed gas containing argon and hydrogen (filtered gas) transferred from the tank U 115c is inhaled into the fuel gas chamber of the fuel cell 116C at a high gas pressure of 0.2 MPa to 1.0 MPa, and (b) The air transferred from the gas compressor U 115d is inhaled into the oxidizing gas chamber of the fuel cell 116C at a high gas pressure of 0.2 MPa to 1.0 MPa (the same pressure as the mixed gas in (a) above), and (c) A fuel cell reaction is induced between the hydrogen contained in the mixed gas in (a) above and the oxygen contained in the air in (b) above through the electrolyte layer provided between the fuel gas chamber and the oxidizing gas chamber.

[0116] Then, as a result of the fuel cell reaction, the fuel cell U 116 outputs: (d) Exhaust gas with a reduced hydrogen concentration (i.e., a gas with an increased argon concentration) discharged from the outlet on the fuel gas chamber side (hydrogen electrode) of the fuel cell 116C; (e) Exhaust gas with a reduced oxygen concentration discharged from the outlet on the oxidizing gas chamber side (oxygen electrode) of the fuel cell 116C; (f) Electric power (electromotive force) generated between the hydrogen electrode in the fuel gas chamber and the oxygen electrode in the oxidizing gas chamber; and (g) Heat (a certain amount of heat) as the chemical reaction heat generated by the fuel cell reaction.

[0117] Among these, the electric power in (f) above is supplied to the kiln 91 and can be used as, for example, the electric power for the heating process in the kiln 91. In addition, the heat in (g) above can also be supplied to the kiln 91 using a heat exchange configuration and used as, for example, the basic heat for the heating process in the kiln 91.

[0118] Here, in the embodiment of the present invention, both the hydrogen contained in the mixed gas in (a) above and the oxygen contained in the air in (b) above participate in the fuel cell reaction that occurs at a high pressure of 0.2 MPa to 1.0 MPa (i.e., at a higher physical density) through the electrolyte layer, as described above. As a result, the efficiency of the fuel cell reaction is improved, and the exhaust gas in (a) above becomes a gas with an increased argon concentration with a further reduced hydrogen concentration (and thus a further increased argon concentration).

[0119] Of course, the fuel cell U 116 may be the one that conducts the fuel cell reaction under normal conditions that are not the high-pressure conditions described above. However, by introducing the mixed gas of (a) and the air of (b) above into the fuel cell 116C at a pressure exceeding atmospheric pressure (about 0.1 MPa), more preferably at a pressure of 0.2 MPa or higher, a gas with an increased argon concentration (or high-purity argon) with a further reduced hydrogen concentration can be taken out.

[0120] In addition, the fuel cell 116C may have a known configuration. For example, a configuration in which a plurality of cells having a structure in which an electrolyte layer is sandwiched between an air electrode (oxygen electrode, negative electrode, cathode) and a hydrogen electrode (fuel electrode, positive electrode, anode) are stacked (laminated) with a separator inserted therebetween. In this case, each cell has a structure in which an oxidation gas chamber is provided on the air electrode side and a fuel gas chamber is provided on the hydrogen electrode side with the electrolyte layer sandwiched therebetween.

[0121] In addition, in an embodiment of the present invention, the fuel cell 116C may be a polymer electrolyte fuel cell (PEFC). The PEFC operates at a relatively low temperature and can be made compact in terms of cell size, and is thus used, for example, in many fuel cell vehicles. However, of course, a solid oxide fuel cell (SOFC), a phosphoric acid fuel cell (PAFC), a molten carbonate fuel cell (MCFC), etc. may be used as the fuel cell 116C. Among these, the SOFC has high power generation efficiency and generally operates at about 700 °C to 1000 °C, enabling the exhaust gas, that is, the gas with an increased argon concentration, to be supplied at a rather high temperature.

[0122] Incidentally, it has been confirmed that in the fuel cell 116C, even if argon that does not act on the fuel cell reaction (is not oxidized) is mixed in the fuel gas chamber, electricity is generated according to the amount of hydrogen in the fuel gas chamber and the amount of oxygen in the oxidation gas. In other words, it is known that argon in the mixed gas generally has no negative impact on the fuel cell reaction, even if its concentration is about 70 vol%. This fact enables the fuel cell 116C to oxidize hydrogen in the mixed gas and generate a gas with an increased argon concentration (or high-purity argon) by performing its inherent function.

[0123] <Rare gas extraction configuration: downstream of the fuel cell U 116> Similarly as Figure 1As shown in [Fig.], the exhaust gas with a reduced hydrogen concentration (i.e., a gas with an increased argon concentration or high-purity argon) discharged from the fuel gas chamber-side outlet of the fuel cell 116C removes some condensed water at the discharge port Da, and the gas pressure of the exhaust gas (as the back pressure of the fuel cell 116C) is controlled by the pressure control U117a equipped with a back pressure valve and a pressure gauge. Thereafter, the exhaust gas is dehumidified in the dehumidification U117b, and in the embodiment of the present invention, the exhaust gas is transferred to the filtration U118 described later.

[0124] Here, in the embodiment of the present invention, the dehumidification U117b is a unit that uses a dry filter with a water vapor-permeable hollow fiber membrane to reduce or remove moisture and water vapor in the mixed gas. In this case, the gas pressure of the gas with an increased argon concentration introduced into the dry filter (0.3 MPa to 0.9 MPa in the embodiment of the present invention) is controlled by the pressure control U119a (downstream of the filtration U118) described later. In a modified embodiment, the dehumidification U117b can be a unit that uses a dehumidifier containing silica gel or zeolite, a dehumidification device equipped with a pressurizing mechanism, a gas-liquid separator, etc. to reduce or remove moisture and water vapor in the mixed gas.

[0125] Meanwhile, the exhaust gas (as low-oxygen air) discharged from the oxidizing gas chamber removes condensed water to a certain extent at the discharge port Db and is discarded (released) into the atmosphere in the embodiment of the present invention after its gas pressure (as the back pressure of the fuel cell 116C) has been controlled by the pressure control U117c equipped with a back pressure valve and a pressure gauge.

[0126] As another embodiment, the gas dehumidified by the dehumidification U117b (discharged from the fuel gas chamber-side outlet) can be transferred as a gas with an increased argon concentration (or high-purity argon) to the buffer tank 119b through the pressure control U119a described later and further transferred to the tank U121 without passing through the filtration U118 described later. For example, when obtaining a gas with an increased argon concentration having a target (or required) high argon concentration through the treatment in the fuel cell U116, such an embodiment is also preferably adopted.

[0127] <Rare gas extraction configuration: Filtration U118> Similarly, in Figure 1 In the filtration U118, the provided gas filter 118F is used to convert the gas with an increased argon concentration discharged from the fuel gas chamber of the fuel cell 116C and introduced through the pressure control U117a and the dehumidification U117b into a gas with an even higher argon concentration, which is high-purity argon in the embodiment of the present invention.

[0128] Here, in an embodiment of the present invention, the gas filter 118F may be the same as the above-described gas filter 113F. In the filtration unit 118, such a gas filter 118F is preferably used for filtration under filtration conditions set based on the residual hydrogen concentration of the gas with an increased argon concentration introduced, and these filtration conditions are the same as those (outlet pressure, outlet flow rate, etc.) described for the gas filter 113F (using Figures 2 (A1) to 2 (C2) , Figure 3 (A) and 3(B) and Figures 4 (A1) to 4 (C2) ). In an embodiment of the present invention, the gas flow rate to the gas filter 118F is controlled by a gas regulator and a mass flow controller (or flow switch) provided in the dehumidification unit 117b.

[0129] In addition, the filtration unit 118 may also use a plurality of gas filters 118F arranged and connected in the same manner as shown in Figure 5 (B) and 5(C) to produce high-purity argon (gas with an increased argon concentration). It is also preferable to return the filtered gas discharged from the hydrogen-side outlet of the gas filter 118F to the buffer tank U 115a (before) and reprocess it in the fuel cell U 116. This makes it possible to further reduce the hydrogen content in the filtered gas and also reduce the amount of argon discarded (released), thereby increasing the final recovery rate of argon.

[0130] In any case, in an embodiment of the present invention, the filtration unit 118 (like the above-described filtration unit 113) can output high-purity argon with a residual hydrogen concentration in the range of, for example, 10 1 ppm to 10 3 ppm from the argon-side outlet of the gas filter 118F.

[0131] <Rare gas extraction configuration: downstream of the filtration unit 118> Similarly, in Figure 1 , in an embodiment of the present invention, the pressure control unit 119a provided downstream of the filtration unit 118 is equipped with a backpressure valve and a pressure gauge, and controls the outlet pressure of the high-purity argon (gas with an increased argon concentration) discharged from the argon-side outlet of the gas filter 118F, and thus controls the gas pressure of the gas with an increased argon concentration introduced into the filtration unit 118. In an embodiment of the present invention, the pressure control unit 119a also controls the gas pressure of the gas with an increased argon concentration introduced into the dehumidification unit 117b (including a dry filter in an embodiment of the present invention) provided downstream of the filtration unit 118.

[0132] In an embodiment of the present invention, high-purity argon gas (gas with increased argon concentration) that has passed through pressure control U119a is then temporarily stored in an argon buffer tank provided in buffer tank U119b, and if necessary, is pressurized by a compressor (compatible with argon) provided in Ar compression U119c, and then transferred to an argon tank provided in tank U121, where it is stored.

[0133] As described in detail above, in the argon extraction section 11 of the embodiment of the present invention, by using a fuel cell U116 (and also filter U118 in the embodiment of the present invention) provided downstream of filter U113 (hydrogen-side outlet 113Fb of the gas filter 113F provided therein), the recovery rate of argon from furnace exhaust gas can be further increased.

[0134] In the argon extraction section 11 of the embodiment of the present invention, the gas pressure of the furnace exhaust gas (mixed gas) to be processed is 0.3 MPa to 0.9 MPa in filter U113, 0.2 MPa to 1.0 MPa in the fuel cell U116 provided downstream thereof, and 0.3 MPa to 0.9 MPa in the filter U118 provided downstream thereof. In addition, in the units and the flow paths between them (and also in the fuel cell U116, dehumidification U117b (equipped with a dry filter), and filter U118), a gas pressure exceeding atmospheric pressure (about 0.1 MPa), which is a high gas pressure of 0.2 MPa or more in the embodiment of the present invention, is maintained. In other words, in the embodiment of the present invention, the argon extraction section 11 is a system including a series of high-pressure gas treatments.

[0135] This promotes the filtration process and fuel cell reaction necessary for the extraction and recovery of argon, and enables the production of a relatively large amount (e.g., a larger gas flow rate) of gas with increased argon concentration (high-purity argon) having a higher argon concentration. The final recovery rate of argon (from furnace exhaust gas) can also be further increased. However, as already mentioned, of course, the fuel cell 116C can be operated in a normal state (not under high pressure as in the embodiment of the present invention). In this case, gas compression U is provided immediately before filter U118.

[0136] <Noble gas delivery configuration: Tank U, Delivery control U> Also in Figure 1In this case, the tank U121 stores (a) high-purity argon gas (gas with increased argon concentration) transferred from the Ar compressor U114c and (b) high-purity argon gas (gas with increased argon concentration) transferred from the Ar compressor U119c under a predetermined gas pressure. Here, in the embodiment of the present invention, when supplying high-purity argon gas (gas with increased argon concentration) to the kiln 91, this predetermined gas pressure is set according to the set (or required) supply gas pressure.

[0137] Similarly, in Figure 1 the delivery control U122 is a unit equipped with a gas regulator and a mass flow controller (or flow switch) and supplies the high-purity argon gas (gas with increased argon concentration) taken out from the tank U121 to the kiln 91 at a set (or required) predetermined gas flow rate.

[0138] <Overall control configuration> Similarly, in Figure 1 the embodiment of the present invention, the overall control U13 is equipped with a memory storing an overall control program and a processor (computer), further includes a communication interface that can communicate with predetermined units provided in the argon extraction section 11 and the argon delivery section 12, and can: (a) Send a control signal to the filter U113 and predetermined units before and after it, and set and adjust the filtering conditions (outlet pressure, outlet flow rate, etc.) according to the content (hydrogen concentration or argon concentration) of the monitoring signal received from the hydrogen concentration meter (or argon concentration meter) ArH provided in the tank U112c and the buffer tank U114b during the filtering process; (b) Control the start and end of the fuel cell reaction in the fuel cell U116, send a control signal to the fuel cell U116 and predetermined units before and after it, and set and adjust various conditions of the fuel cell reaction (such as the flow rate and pressure of the gas introduced into the fuel cell 116C); (c) Send a control signal to the filter U118 and predetermined units before and after it, and set and adjust the filtering conditions (outlet pressure, outlet flow rate, etc.) according to the content (hydrogen concentration or argon concentration) of the monitoring signal received from the hydrogen concentration meter (or argon concentration meter) ArH provided in the dehumidifier U117b and the buffer tank U119b during the filtering process; and (d) Receive an instruction to supply high-purity argon gas (gas with increased argon concentration) from the outside, send a control signal to the delivery control U122, and cause the delivery control U122 to send (supply) the high-purity argon gas (gas with increased argon concentration) to the kiln 91 at a specified gas flow rate.

[0139] The above control processes (a) to (d) are implemented by a processor (computer) installed in the overall control U13 and executing the above overall control program.

[0140] [Another Embodiment of the Kiln Exhaust Gas Regeneration Device / System] Figure 6 FIG. is a schematic diagram showing another embodiment of the kiln exhaust gas regeneration device / system according to the present invention.

[0141] As Figure 6 shown, in the kiln exhaust gas regeneration device (system) 2 of the embodiment of the present invention, the kiln exhaust gas discharged from the kiln 91 (fine powder collector U 92) is first treated in the fuel cell U 216 and converted into a gas with an increased argon concentration (high-purity argon). Then, this gas with an increased argon concentration (high-purity argon) is treated in the filter U 213 downstream of the outlet provided on the fuel gas chamber side (hydrogen electrode side) of the fuel cell 216C (provided in the fuel cell U 216) to produce high-purity argon (gas with an increased argon concentration).

[0142] Specifically, the kiln exhaust gas regeneration device (system) 2 includes an argon extraction section (rare gas extraction section) 21, an argon delivery section (rare gas delivery section) 22, and an overall control U 23. Among these, the argon delivery section 22 has a tank U 221 and a delivery control U 222. In addition, in the embodiment of the present invention, the argon extraction section 21 includes: (a) A catalytic poison removal unit U 211; (b) A buffer tank U 215a, a gas compressor U 215b, a tank U 215c, and a gas compressor U 215d; (c) A fuel cell U 216 equipped with a fuel cell 216C; (d) A pressure control U 217a, a dehumidifier U 217b, and a pressure control U 217c; (e) A filter U 213 equipped with a gas filter 213F; and (f) A pressure control U 214a, a buffer tank U 214b, and an Ar compressor U 214c.

[0143] Here, the above components '(name) 2**(*)' (where * is a number or letter) can be considered to have the same structure and function as the components '(name) 1**(*)' of the kiln exhaust gas regeneration device (system) 1 shown in Figure 1 FIG., which have the same '(name)' and '**(*)' as those of '(name) 2**(*)'. For example, the fuel cell 216C and the fuel cell U 216 can respectively have the same structure as the fuel cell 116C (Figure 1 ) and the fuel cell U 116( Figure 1 ) have the same structure and function. However, in the embodiment of the present invention, the buffer tank U 215a is a unit that includes not only the buffer tank (215ab) but also the blower 215aa. Here, the blower 215aa and the buffer tank 215ab respectively have the same structure and function as the blower 112aa and the buffer tank 112ab of the blower U 112a( Figure 1 ) have the same structure and function.

[0144] Through this kiln exhaust gas regeneration device (system) 2, the kiln exhaust gas can also be regenerated into a reusable gas with an increased argon concentration, that is, high-purity argon in the embodiment of the present invention.

[0145] In the embodiment of the present invention, the filtered gas discharged from the hydrogen-side outlet 213F of the gas filter 213F provided in the filter U 213 can preferably be returned to the buffer tank U 215a (right before) and reprocessed in the fuel cell U 216. This makes it possible to reduce the amount of argon to be discarded (released) and increase the final recovery rate of argon.

[0146] Furthermore, also in the argon extraction section 21 of the embodiment of the present invention, the gas pressure of the kiln exhaust gas (mixed gas) to be processed is 0.2 MPa to 1.0 MPa in the fuel cell U 216, and 0.3 MPa to 0.9 MPa in the filter U 213 provided downstream thereof. Furthermore, in the units and the flow paths between them (and also in the fuel cell U 216, the dehumidification U 217b (equipped with a dry filter), and the filter U 213), a gas pressure exceeding the atmospheric pressure (about 0.1 MPa) is maintained, which is a high gas pressure of 0.2 MPa or more in the embodiment of the present invention. In other words, in the embodiment of the present invention, the argon extraction section 21 is also a system including a series of high-pressure gas treatments.

[0147] This promotes the filtration process and the fuel cell reaction necessary for the extraction and recovery of argon, and makes it possible to produce a relatively large amount (for example, a larger gas flow rate) of a gas with an increased argon concentration (high-purity argon) having a higher argon concentration. The final recovery rate of argon (from the kiln exhaust gas) can also be further increased. However, as already mentioned, of course, the fuel cell 216C can be operated in a normal state (not under high pressure as in the embodiment of the present invention). In this case, gas compression U is provided immediately before the filter U 213.

[0148] Figure 7 is a schematic diagram showing still another embodiment of the kiln exhaust gas regeneration device / system according to the present invention.

[0149] AsFigure 7 As shown in Figure 7 , in the kiln waste gas regeneration device (system) 3 of the embodiment of the present invention, based on the argon concentration or hydrogen concentration of the kiln waste gas discharged from the kiln 91 (fine powder collector U 92), based on a preset schedule, or based on an external instruction, it is determined which one or both of the filter U 313 and the fuel cell U 316 (and another filter U 318) are to be used, and the received kiln waste gas is regenerated into a reusable gas with an increased argon concentration (which is high-purity argon in the embodiment of the present invention) using the determined filter U 313 and / or fuel cell U 316 (and another filter U 318).

[0150] In the embodiment of the present invention, the kiln waste gas regeneration device (system) 3 includes a plurality of components '(name) 3**(*)' (where * is a number or an English letter), and each of these components corresponds to the component '(name) 1**(*)' of the kiln waste gas regeneration device (system) 1( Figure 1 ) and the component '(name) 3**(*) can be considered a component having the same structure and function as the component '(name) 1**(*) (which has the same '(name)' and '**(*) as those of '(name) 3**(*)').

[0151] However, in the embodiment of the present invention, the buffer tank U 315a is a unit that includes not only the buffer tank (315ac) but also the blower 315aa and the buffer tank 315ab. Here, the blower 315aa and the buffer tank 315ab respectively have the same structure and function as the blower 112aa and the buffer tank 112ab of the blower U112a( Figure 1 ) and the buffer tank 315ac has the same structure and function as the buffer tank of the buffer tank U 115( Figure 1 ). In addition, in the embodiment of the present invention, the buffer tank U 315a also has a flow path switching valve that switches the flow path so that the buffer tank 315ac can be used in the case of <flow path 1> described later, while the blower 315aa and the buffer tank 315ab can be used in the case of <flow path 2> described later.

[0152] The kiln waste gas regeneration device (system) 3 of the embodiment of the present invention further includes: (a) A flow path switching valve SW1, which is provided between the catalytic poison removal U 311 and the blower U 312a and can transfer the gas transferred from the catalytic poison removal U 311 to one of the blower U 312a and the flow path switching valve SW3 described below that is determined; (b) A flow path switching valve SW2, which is provided between the tank U 312c and the filter U 313 and can transfer the gas transferred from one of the tank U312c and the flow path switching valve SW4 described below to the filter U 313; (c) A flow path switching valve SW3, which is provided between the hydrogen-side outlet 313Fb (provided in the filter U 313) of the gas filter 313F and the buffer tank U 315a and can transfer the gas transferred from one of the gas filter 313F and the above flow path switching valve SW1 to the buffer tank U 315a; and (d) A flow path switching valve SW4, which is provided between the dehumidifier U 317b and the filter U 318 and can transfer the gas transferred from the dehumidifier U 317b to one of the filter U 318 and the above flow path switching valve SW2.

[0153] In an embodiment of the present invention, the overall control U 33 determines a control signal for controlling the switching by the flow path switching valves SW1 to SW4 based on the following items: (a) The content of the monitoring signal (hydrogen concentration or argon concentration) received from the hydrogen concentration meter (or argon concentration meter) ArH provided in the catalytic poison removal U 311; (b) A preset switching schedule; or (c) The content of the instruction received from the outside (the content specifying one of the flow paths 1 to 3 shown below), and Send the control signal to the flow path switching valves SW1 to SW4 to implement one of the following flow paths (flow path modes) 1 to 3 as appropriate.

[0154] <Flow path 1> Furnace 91 (fine powder collector 92) → Catalytic poison removal U 311 to tank U 312c → Filter U313 → Pressure control U 314a to Ar compression U314c → Tank U 321 → Delivery control U 322; and Filter U 313 → Buffer tank U 315a (buffer tank 315ac) to tank U 315c → Fuel cell U 316 → Pressure control U 317a → Dehumidifier U 317b → Filter U 318 → Pressure control U 319a to Ar compression U 319c → Tank U 321 → Delivery control U 322; <Flow path 2>Kiln 91 (fine powder collector 92) → Catalytic poison removal U311 → Buffer tank U315a (blower 315aa and buffer tank 315ab) to tank U315c → Fuel cell U316 → Pressure control U317a → Dehumidification U317b → Filtration U313 → Pressure control U314a to Ar compression U314c → Tank U321 → Delivery control U322 (in this case, the flow path switching valve SW3 only releases (discards) the gas from the hydrogen-side outlet 313Fb); <Flow path 3>Kiln 91 (fine powder collector 92) → Catalytic poison removal U311 to tank U312c → Filtration U313 → Pressure control U314a to Ar compression U314c → Tank U321 → Delivery control U322 (fuel cell U316 not used).

[0155] In the modified embodiment, filtration U318 in the above <Flow path 1> may also not be provided (can be omitted). In this case, the gas with an increased argon concentration (high-purity argon) transferred from the dehumidification U317b downstream of the fuel cell U316 passes through the flow path switching valve SW4 and through the pressure control U319a and is transferred to, for example, the buffer tank U319b.

[0156] Here, it is also preferable that the overall control U33 performs, for example, the following control: (A) When the hydrogen concentration of the received kiln exhaust gas is greater than a predetermined threshold (for example, 50 vol%), first implement <Flow path 2>, where the fuel cell reaction process is initially carried out to sufficiently reduce the hydrogen concentration, and thus high-purity argon (gas with an increased argon concentration) is produced; and (B) When the hydrogen concentration of the received kiln exhaust gas is equal to or less than the predetermined threshold (for example, 50 vol%), <Flow path 1> is implemented, where the filtration process is initially carried out to produce argon with a smaller absolute value of hydrogen concentration (i.e., argon with a higher (absolute) purity), and thus high-purity argon (gas with an increased argon concentration) is produced.

[0157] Incidentally, the kiln exhaust gas in the above (A) corresponds to the gas discharged in the first half of the alloy powder manufacturing process in the kiln 91 (for example, the time period of several tens of minutes from the start of the process). In the first half, a large amount of occluded hydrogen is released through heat treatment in the kiln 91, and the flow rate of the argon introduced into the kiln 91 is still small (compared with the second half, which will be described below), so the kiln exhaust gas in the first half has a high hydrogen concentration (for example, 60 vol% to 90 vol%).

[0158] Meanwhile, the furnace exhaust gas in the above (B) corresponds to the gas discharged in the latter half of the alloy powder manufacturing process in furnace 91 (e.g., the time period from this point when several tens of minutes have elapsed since the start of the process to the end of the process). In the latter half, the flow rate of the introduced argon increases significantly (e.g., several to several tens of times higher than that in the first half), and the release of the occluded hydrogen is nearly complete, so the furnace exhaust gas has a low hydrogen concentration (e.g., 30 vol% or less).

[0159] Therefore, it is also preferable that the overall control of U 33 is performed by controlling in the following manner: select <Flow path 2> in the above (A) when initially receiving the furnace exhaust gas from furnace 91 (fine powder collector U92), and then when the hydrogen concentration of the furnace exhaust gas drops below a predetermined threshold (e.g., 50 vol%) or when a predetermined time (e.g., several tens of minutes) has elapsed since the selection of <Flow path 2>, select <Flow path 1> in the above (B). By performing such control, it is possible to always and stably produce high-purity argon (gas with an increased argon concentration) having a desired (or required) high argon concentration despite significant changes in the hydrogen concentration (argon concentration) of the furnace exhaust gas discharged from furnace 91.

[0160] Furthermore, according to the above control, it is also preferable that both buffer tank 312ab and buffer tank 315ab are provided with a first half tank for storing the furnace exhaust gas discharged in the first half of the alloy powder manufacturing process and a second half tank for storing the furnace exhaust gas discharged in the second half, and when receiving the furnace exhaust gas discharged in the first half (second half), the furnace exhaust gas is stored in the first half tank (second half tank). Here, it is also preferable that the second half tank has a larger (e.g., several to several tens of times) capacity than the first half tank in order to accommodate the higher flow rate of the furnace exhaust gas in the second half.

[0161] By using such buffer tanks 312ab and 315ab, high-purity argon (gas with an increased argon concentration) can be more effectively produced by appropriately accommodating the increase in the furnace exhaust gas flow rate in the second half of the alloy powder manufacturing process in furnace 91. It is also possible to stabilize the gas pressure in furnace 91, and thus contribute to the realization of an effective or low-cost alloy powder manufacturing process. Naturally, buffer tank 112ab ( Figure 1 ) and buffer tank 215ab ( Figure 6 ) can also be equipped with the first half tank and the second half tank as described above and set to switch between the first half tank and the second half tank to be used as described above.

[0162] In addition, as another embodiment related to the selection of the flow path (flow path pattern), the overall control U33 can determine the argon concentration, gas flow rate, and recovery rate (dependency on the hydrogen concentration of the furnace exhaust gas) of the gas with increased argon concentration generated in each flow path (flow path pattern) through previous experiments (where the hydrogen concentration of the furnace exhaust gas is changed), and can use the determined content to select and implement the flow path (flow path pattern) based on the received hydrogen concentration of the furnace exhaust gas (and the required specifications of the gas with increased argon concentration).

[0163] In addition, when the target (required) argon concentration (purity), gas flow rate, recovery rate, etc. can be achieved by only using the filtration U313, the overall control U33 can be set to implement <Flow Path 3> and generate high-purity argon (gas with increased argon concentration) when receiving an external instruction specifying <Flow Path 3>. In addition, in this case, the setting can be to select <Flow Path 3> instead of <Flow Path 1> in (B) of the above embodiment. In addition, when receiving an external instruction specifying a predetermined flow path due to reasons such as maintenance, testing, or unit failure, the overall control U33 can be set to implement the predetermined flow path (flow path pattern) and generate high-purity argon (gas with increased argon concentration).

[0164] When selecting the flow path (flow path pattern) including the fuel cell U316, it is also preferable to return the exhaust gas (gas with increased argon concentration) discharged from the fuel gas chamber-side outlet of the fuel cell 316C and dehumidified by the dehumidification U317b to the buffer tank U315a (right before) and process it again through the fuel cell U316. This enables further reduction of the hydrogen content in the exhaust gas and an increase in the final recovery rate of argon.

[0165] Here, specifically, the flow path switching valve can be provided right after the dehumidification U317b and right before the buffer tank U315a, and the exhaust gas can be returned to the buffer tank U315a (right before) a predetermined number of times (within a predetermined time period) by switching these flow path switching valves as appropriate and controlling the gas transfer from the buffer tank U315a as appropriate. Naturally, the same treatment as above can also be performed on the exhaust gas from the fuel gas chamber-side outlet of the fuel cell U116( Figure 1 ) or the fuel cell U216( Figure 6 ) to further reduce the hydrogen content in the exhaust gas.

[0166] In addition, in a case where a target (or required) high argon concentration or high recovery rate can be achieved by returning the exhaust gas to the fuel cell U 316 as described above, a flow path pattern <flow path 4> in which the filtration U 313 (and the pressure control U 314a) in the above-described flow path 2 is omitted can be achieved, and high-purity argon (gas with an increased argon concentration) is produced using this <flow path 4>.

[0167] As described in detail above, according to the present invention, a mixed gas (furnace exhaust gas) containing rare gases and occluded gases (occluded gases) discharged from a furnace can be regenerated into a reusable gas. In addition, a furnace system that reuses the regenerated gas can be provided. In addition, the gas with an increased concentration of the produced rare gas (argon) can be used in various fields other than the furnace.

[0168] In addition, although limited to the case of the embodiment using a fuel cell, with the increasing social demand for reducing carbon dioxide emissions, it is expected that the demand for fuel cells and, for example, neodymium (Nd-Fe-B) magnets manufactured using a furnace will further increase. In other words, fuel cells and rare earth magnets manufactured using a furnace are well matched to and suitable for the upcoming carbon-neutral society. In addition, for this reason, the embodiments of the present invention in which a fuel cell is used to treat furnace exhaust gas are very suitable for the above social demands, which will only increase in the future.

[0169] The foregoing embodiments are merely examples of this disclosure and are not intended to be limiting thereto, and thus many widely different alternatives and modifications of this disclosure can be constructed. Therefore, this disclosure is defined only as defined by the following claims and their equivalents. List of Reference Numerals

[0170] 1 Furnace Exhaust Gas Regeneration Device (Furnace Exhaust Gas Regeneration System); 111, 211, 311 Catalyst Poison Removal Unit (U); 112a, 312a Blower U; 112aa, 215aa, 312aa, 315aa Blowers; 112ab, 215ab, 312ab, 315ab, 315ac Buffer Tanks; 112b, 312b Gas Compression U; 112c, 312c Tank U; 113, 118, 213, 313, 318 Filtration U; 113F, 113F1, 113F2, 113F3, 113F4, 118F, 213F, 313F, 318F Gas Filters; 114a, 214a, 314a Pressure Control U; 114b, 214b, 314b buffer tanks U; 114c, 214c, 314c Ar compressors U; 115a, 215a, 315a buffer tanks U; 115b, 215b, 315b gas compressors U; 115c, 215c, 315c tanks U; 115d, 215d, 315d gas compressors U; 116, 216, 316 fuel cells U; 116C, 216C, 316C fuel cells; 117a, 217a, 317a pressure controllers U; 117b, 217b, 317b dehumidifiers U; 117c, 217c, 317c pressure controllers U; 119a, 319a pressure controllers U; 119b, 319b buffer tanks U; 119c, 319c Ar compressors U; 121, 221, 321 tanks U; 122, 222, 322 delivery controllers U; 13, 23, 33 overall controllers U; 91 kiln; 92 fine powder collectors U; and 93 alloy powder recovery containers.

Claims

1. A kiln waste gas regeneration device, which includes a rare gas extraction mechanism configured to receive the mixed gas discharged from the kiln and convert the mixed gas into a gas with an increased rare gas concentration. The mixed gas contains rare gas and occluded gas. The kiln heats the metal occluding the occluded gas and causes the occluded gas to be released from the metal in an atmosphere containing the rare gas. And the rare gas extraction mechanism is configured to convert the mixed gas by using the following: a filter that has different permeabilities for the occluded gas and the rare gas; and / or a fuel cell configured to oxidize the occluded gas.

2. The kiln waste gas regeneration device according to claim 1, further including a rare gas delivery mechanism configured to send the gas with an increased rare gas concentration to the kiln or a gas storage tank for the kiln, so as to reuse the gas with an increased rare gas concentration as the atmosphere.

3. The kiln waste gas regeneration device according to claim 1, wherein, The rare gas extraction mechanism converts the mixed gas into the gas with an increased rare gas concentration by using the filter and the fuel cell disposed downstream of the outlet of the filtered gas in the filter.

4. The kiln waste gas regeneration device according to claim 3, wherein, The rare gas extraction mechanism uses a gas compressor to make the mixed gas act on the filter under a high pressure exceeding atmospheric pressure, and introduces the gas taken out from the outlet of the filtered gas in the filter into the fuel gas chamber of the fuel cell under a high pressure exceeding atmospheric pressure to oxidize the occluded gas.

5. The kiln waste gas regeneration device according to claim 3, wherein, The rare gas extraction mechanism further uses another filter disposed downstream of the fuel gas chamber of the fuel cell and having different permeabilities for the occluded gas and the rare gas to convert the mixed gas into the gas with an increased rare gas concentration.

6. The kiln waste gas regeneration device according to claim 1, wherein, The rare gas extraction mechanism uses the fuel cell and the filter disposed downstream of the fuel gas chamber of the fuel cell to convert the mixed gas into the gas with an increased rare gas concentration.

7. The kiln waste gas regeneration device according to claim 6, wherein, The rare gas extraction mechanism uses a gas compressor to introduce the mixed gas into the fuel gas chamber of the fuel cell under a high pressure exceeding atmospheric pressure to oxidize the occluded gas, and makes the gas taken out from the fuel gas chamber of the fuel cell act on the filter under a high pressure exceeding atmospheric pressure.

8. The kiln waste gas regeneration device according to any one of claims 1 to 7, wherein, The rare gas extraction mechanism includes the filter, makes the mixed gas act on the filter at a gas flow rate set to a value for reducing the concentration of the residual occluded gas or within a range of gas flow rate values set to reduce the concentration of the residual occluded gas, and takes out the gas with an increased rare gas concentration from the filter.

9. The kiln waste gas regeneration device according to any one of claims 1 to 7, wherein, The rare gas extraction mechanism includes the filter, makes the mixed gas act on the filter at a gas pressure set to a value for increasing the recovery rate of the rare gas or within a range of gas pressure values set to increase the recovery rate of the rare gas, and takes out the gas with an increased rare gas concentration from the filter.

10. The kiln waste gas regeneration device according to claim 1, wherein, The rare gas extraction mechanism includes the filter, and causes the mixed gas to act on the filter under gas pressure and / or gas flow rate determined according to the concentration of the rare gas or the occluded gas in the received mixed gas as the filtering condition of the filter, and extracts the gas with increased rare gas concentration from the filter.

11. The kiln waste gas regeneration device according to claim 1, further comprising a controller configured to determine which one or both of the filter and the fuel cell to use based on the concentration of the rare gas or the occluded gas in the received mixed gas, based on a preset schedule, or based on an external instruction. The rare gas extraction mechanism includes the filter and the fuel cell, and converts the mixed gas into the gas with increased rare gas concentration by using the determined filter and / or fuel cell.

12. The kiln waste gas regeneration device according to claim 11, wherein, Based on the concentration of the rare gas or the occluded gas in the received mixed gas, based on a preset schedule, or based on an external instruction, the controller selects a flow path pattern to be used from a group of flow path patterns, the group of flow path patterns including a flow path pattern connecting the filter and the fuel cell downstream thereof, a flow path pattern connecting the fuel cell and the filter downstream thereof, and a flow path pattern including the filter but not including the fuel cell, and wherein the rare gas extraction mechanism includes the filter, the fuel cell, and a flow path switching valve configured to implement each flow path pattern included in the group of flow path patterns, implements the selected flow path pattern to be used, and converts the mixed gas into the gas with increased rare gas concentration.

13. The kiln waste gas regeneration device according to claim 12, wherein, The controller first selects the flow path pattern connecting the fuel cell and the filter downstream thereof, and then selects the flow path pattern connecting the filter and the fuel cell downstream thereof.

14. A kiln waste gas regeneration system, comprising a rare gas extraction mechanism configured to receive a mixed gas discharged from a kiln and convert the mixed gas into a gas with increased rare gas concentration, the mixed gas containing a rare gas and an occluded gas, the kiln heating a metal occluding the occluded gas and causing the occluded gas to be released from the metal in an atmosphere containing the rare gas, and the rare gas extraction mechanism being configured to convert the mixed gas by using: a filter having different permeabilities for the occluded gas and the rare gas; and / or a fuel cell configured to oxidize the occluded gas.

15. A kiln system, comprising: a kiln configured to heat a metal occluding an occluded gas and cause the occluded gas to be released from the metal in an atmosphere containing a rare gas; Noble gas extraction mechanism, which is configured to receive a mixed gas discharged from the kiln and containing the noble gas and the occluded gas, and convert the mixed gas into a gas with an increased noble gas concentration by using a filter with different permeabilities for the occluded gas and the noble gas and / or a fuel cell configured to oxidize the occluded gas; and Noble gas delivery mechanism, which is configured to send the gas with an increased noble gas concentration to the kiln or a gas storage tank for the kiln so as to reuse the gas with an increased noble gas concentration as the atmosphere.

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