Kiln exhaust gas regenerating device, system and method, and kiln system

Abstract

To provide a kiln exhausts gas regenerating device that regenerates a gas mixture that contains noble gas and occluded gas into a reusable gas, the mixture gas being exhausted from a kiln that heats a metal storing the occluded gas and uses an atmosphere including the noble gas to cause the occluded gas to be discharged from the metal.SOLUTION: The kiln exhaust gas regeneration device comprises: noble gas extracting means that receives gas mixture including noble gas and occluded gas exhausted from a kiln, and uses a filter with different degrees of permeability for the occluded gas and the noble gas and / or a fuel cell that oxidizes the occluded gas to transform the received gas mixture into a gas with increased noble gas concentration. Here, preferably, the noble gas is argon gas. Additionally preferably, the kiln exhaust gas regeneration device further comprises noble gas delivery means to send the gas with increased noble gas concentration to the kiln or a gas reservoir for the kiln, in order to have the gas reused as the above-described atmosphere.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a technique for treating gas discharged from a furnace. [Background technology]

[0002] In recent years, rare earth magnets such as neodymium-iron-boron (Nd-Fe-B) magnets have become essential materials for the manufacture of electric drive systems such as electric motors for electric vehicles, and demand for them is expected to increase further in the coming carbon-neutral society.

[0003] This rare earth magnet is generally manufactured by (a) coarsely pulverizing a raw alloy block containing rare earth elements, metal elements, and boron produced by a melting method, (b) converting the raw alloy block into alloy powder (finely pulverizing) using a jet mill or the like, (c) compressing and molding the alloy powder in a magnetic field, (d) sintering and heat treating the molded body, and (e) subjecting the molded body to various processes. Here, the above-mentioned (a) crushing of the raw alloy block (coarse crushing) is quite time-consuming, which results in a problem of reduced overall productivity.

[0004] In response to this problem, for example, Patent Document 1 discloses an apparatus for manufacturing a coarsely pulverized alloy powder by absorbing hydrogen into the raw alloy block, then subjecting it to heat treatment and pulverizing it. In general, rare earth alloys containing rare earth elements have the property of absorbing a large amount of hydrogen. When the raw alloy block absorbing a large amount of hydrogen is heated, further expansion occurs while the bonding force between metal atoms is weakened by the presence of hydrogen atoms, which causes cracks in the raw alloy block and the alloy powder is self-destructively converted.

[0005] Here, the alloy powder manufacturing apparatus disclosed in Patent Document 1 is equipped with a rotatable heat treatment section that heats and dehydrogenates the alloy powder that has absorbed hydrogen, and this heat treatment section has a gas supply mechanism for introducing argon gas into the inside during treatment. When manufacturing the alloy powder, this heat treatment section is rotated and argon gas is introduced into the heat treatment section to heat and dehydrogenate the alloy powder that has absorbed hydrogen. As a result, hydrogen released from the alloy powder is quickly discharged together with the argon gas, and efficient dehydrogenation is achieved. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2005-163066 A Summary of the Invention [Problem to be solved by the invention]

[0007] Currently, the process of "hydrogen absorption" followed by "alloy powdering and dehydrogenation by heating" as disclosed in Patent Document 1 is adopted in the manufacture of alloy powder for rare earth magnets. Specifically, in a kiln, the raw alloy block with hydrogen absorption is coarsely crushed, heated to several hundred degrees Celsius in an argon gas atmosphere (non-oxidizing atmosphere) introduced, and coarsely crushed while releasing hydrogen gas, and then the released hydrogen gas is discharged together with argon gas outside the kiln. Incidentally, the coarsely crushed alloy block, i.e., alloy powder, is transferred to the next process in a non-oxidizing atmosphere.

[0008] Here, the argon gas discharged together with the hydrogen gas is in a mixed gas state mixed with hydrogen gas. Therefore, this argon gas is difficult to reuse, and in the past, it was diluted with nitrogen gas or the like and discharged to the outside and discarded. Therefore, even though argon gas is a noble gas and very expensive, it is necessary to introduce new argon gas every time production is carried out, which has been a major obstacle to reducing production costs.

[0009] Therefore, an object of the present invention is to provide an apparatus, system and method for regenerating a mixed gas containing a noble gas and an occluded gas discharged from the above-mentioned furnace into a reusable gas, and also to provide a furnace system for reusing the regenerated gas. [Means for solving the problem]

[0010] According to the present invention, there is provided a furnace exhaust gas regeneration device having a noble gas extraction means for receiving a mixed gas containing the noble gas and the occluded gas discharged from a furnace in which a metal occluded with the occluded gas is heated and the occluded gas is released from the metal in an atmosphere containing the noble gas, and converting the mixed gas into a gas having an increased concentration of the noble gas by using a filter having different permeability for the occluded gas and the noble gas and / or a fuel cell for oxidizing the occluded gas. Here, it is also preferable that the noble gas is argon gas.

[0011] It is also preferred that the kiln exhaust gas regeneration apparatus according to the present invention further comprises a noble gas delivery means for delivering the gas having an increased noble gas concentration to the kiln or a gas reservoir for the kiln so as to reuse the gas as the atmosphere.

[0012] Furthermore, as one embodiment of the kiln exhaust gas regeneration apparatus according to the present invention, it is also preferable that the noble gas extraction means uses the filter and the fuel cell provided downstream of the filtered gas outlet of the filter to convert the mixed gas into a gas with an increased concentration of the noble gas.

[0013] In the above embodiment, it is also preferable that the noble gas extraction means uses a gas compressor, applies the mixed gas to the filter at a high pressure exceeding atmospheric pressure, and further introduces gas extracted from the filtered gas outlet of the filter at a high pressure exceeding atmospheric pressure into the fuel gas chamber of the fuel cell to oxidize the occluded gas.

[0014] Furthermore, in the above embodiment, it is also preferable that the noble gas extraction means further uses another filter having a different degree of permeability for the occluded gas and the noble gas, which is provided downstream of the fuel gas chamber of the fuel cell, to convert the mixed gas into a gas with an increased concentration of the noble gas.

[0015] In another embodiment of the kiln exhaust gas regeneration apparatus according to the present invention, the noble gas extraction means preferably uses the fuel cell and the filter provided downstream of the fuel gas chamber of the fuel cell to convert the mixed gas into a gas having an increased concentration of the noble gas.

[0016] Furthermore, in the above embodiment (in which a filter is provided downstream of the fuel gas chamber of the fuel cell), it is also preferable that the noble gas extraction means uses a gas compressor to introduce the mixed gas at a high pressure exceeding atmospheric pressure into the fuel gas chamber of the fuel cell to oxidize the occluded gas, and furthermore to act on the filter with gas extracted from the combustion gas chamber of the fuel cell at a high pressure exceeding atmospheric pressure.

[0017] In addition, as one embodiment of the filtering process of the present invention, it is also preferable that the noble gas extraction means is equipped with the filter, and the mixed gas is applied to the filter at a gas flow rate of a value set to reduce the residual occluded gas concentration, or a gas flow rate within a gas flow rate value range set to reduce the residual occluded gas concentration, and gas with an increased noble gas concentration is extracted from the filter.

[0018] Furthermore, as another embodiment of the filtering process of the present invention, it is also preferable that the noble gas extraction means is equipped with the filter, and the mixed gas is applied to the filter at a gas pressure set at a value at which the recovery rate of the noble gas is high, or at a gas pressure within a gas pressure value range set at which the recovery rate of the noble gas is high, and gas with an increased concentration of the noble gas is extracted from the filter.

[0019] As yet another embodiment of the filtering process according to the present invention, it is also preferable that the noble gas extraction means is equipped with the filter, and that the mixed gas is applied to the filter with a gas pressure and / or gas flow rate as filtering conditions for the filter, the gas pressure and / or gas flow rate being determined according to the concentration of the noble gas or the occluded gas in the received mixed gas, and that gas with an increased concentration of the noble gas is extracted from the filter.

[0020] In yet another embodiment of the kiln exhaust gas regeneration apparatus according to the present invention, the apparatus further comprises a control means for determining which of the filter and the fuel cell to use based on the concentration of the noble gas or the occluded gas in the received mixed gas, based on a preset time schedule, or based on an external instruction, It is also preferable that the noble gas extraction means comprises the filter and the fuel cell, and the mixed gas is converted into a gas having an increased concentration of the noble gas by using the determined filter and / or the fuel cell.

[0021] In still another embodiment, the control means selects a flow path pattern to be used from a flow path pattern set 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, based on a concentration of the noble gas or the occluded gas in the received mixed gas, based on a preset time schedule, or based on an external instruction, It is also preferable that the noble gas extraction means comprises the filter, the fuel cell, and a flow path switching valve that realizes each flow path pattern included in the flow path pattern set, and realizes the selected flow path pattern to be used to convert the mixed gas into a gas with an increased concentration of the noble gas.

[0022] Furthermore, it is also preferable that the control means first selects a flow path pattern that connects the fuel cell and the filter in the downstream stage, and then selects a flow path pattern that connects the filter and the fuel cell in the downstream stage.

[0023] In addition, the mixed gas discharged from the furnace and received by the noble gas extraction means of the present invention can be a mixed gas in which the concentration of the occluded gas is initially higher than the concentration of the noble gas, and thereafter the concentration of the noble gas becomes higher than the concentration of the occluded gas.

[0024] Furthermore, as yet another embodiment of the kiln exhaust gas regeneration apparatus according to the present invention, it is preferable that the noble gas extraction means is equipped with the filter, the mixed gas is applied to the filter, and gas with an increased concentration of the occluded gas is extracted from the filtered gas outlet of the filter.

[0025] In yet another embodiment of the kiln exhaust gas regeneration apparatus according to the present invention, the noble gas extraction means is preferably a plurality of filters connected in series, with the inlet of the second or subsequent filter being connected to the outlet of the filtered gas of the previous filter, to convert the mixed gas into a gas with an increased concentration of the noble gas.

[0026] Furthermore, it is also preferable that the noble gas extraction means according to the present invention further comprises a buffer tank for temporarily storing the mixed gas, and a blower for sending the mixed gas to the buffer tank, located upstream of the gas compressor.

[0027] The present invention also provides a kiln exhaust gas regeneration system having a noble gas extraction means for receiving a mixed gas containing the noble gas and the occluded gas discharged from a kiln in which a metal that has occluded the occluded gas is heated and the occluded gas is released from the metal in an atmosphere containing the noble gas, and converting the mixed gas into a gas with an increased concentration of the noble gas using filters having different degrees of permeability for the occluded gas and the noble gas and / or a fuel cell that oxidizes the occluded gas.

[0028] According to the present invention, there is further provided a furnace for heating the metal having the occluded gas and releasing the occluded gas from the metal in an atmosphere containing a noble gas; a noble gas extraction means for receiving a mixed gas containing the noble gas and the occluded gas discharged from a furnace, and converting the mixed gas into a gas having an increased concentration of the noble gas by using a filter having different permeability for the occluded gas and the noble gas and / or a fuel cell for oxidizing the occluded gas; a noble gas delivery means for delivering the gas having an increased noble gas concentration to a kiln or a gas reservoir for the kiln so as to reuse the gas as the atmosphere; A furnace system is provided having:

[0029] According to the present invention, the method further comprises the steps of: receiving a mixed gas containing the noble gas and the occluded gas discharged from a furnace in which a metal having an occluded gas is heated and the occluded gas is released from the metal in an atmosphere containing the noble gas; converting the mixed gas into a gas having an increased concentration of the noble gas by using a filter having different permeability for the stored gas and the noble gas and / or a fuel cell for oxidizing the stored gas; A method for regenerating kiln flue gas comprising the steps of: Effect of the Invention

[0030] According to the kiln exhaust gas regeneration device, system and method of the present invention, a mixed gas containing a noble gas and an occluded gas discharged from a kiln in which a metal occluded with an occluded gas is heated and the occluded gas is released from the metal in an atmosphere containing a noble gas can be regenerated into a reusable gas. Furthermore, according to the kiln system of the present invention, it is possible to reuse the regenerated gas. [Brief description of the drawings]

[0031] [Figure 1] 1 is a schematic diagram showing one embodiment of a kiln exhaust gas regeneration device / system and a kiln system according to the present invention. FIG. [Diagram 2]4 is a graph for explaining an embodiment of a filtering process according to the present invention. [Diagram 3] 3 is a table showing the results of measuring the hydrogen concentration at the hydrogen side outlet in the embodiment of FIG. 2. [Figure 4] 10 is a graph for explaining another embodiment of the filtering process according to the present invention. [Diagram 5] 2A to 2C are schematic diagrams for explaining various embodiments of the arrangement of gas filters in the filtering unit (U) according to the present invention. [Figure 6] FIG. 2 is a schematic diagram showing another embodiment of a kiln exhaust gas regeneration device / system according to the present invention. [Figure 7] FIG. 4 is a schematic diagram showing yet another embodiment of a kiln exhaust gas regeneration device / system according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. Note that the gas pressure values ​​described below are absolute gas pressure values, with 1 atmosphere (atmospheric pressure) being approximately 0.1 megapascals (MPa).

[0033] [Kiln exhaust gas regeneration equipment / system, kiln system] FIG. 1 is a schematic diagram showing one embodiment of a kiln exhaust gas regeneration device / system and a kiln system according to the present invention.

[0034] The kiln exhaust gas regeneration device 1 according to one embodiment of the present invention shown in FIG. 1 is a device that regenerates kiln exhaust gas discharged from a kiln (kiln) 91 that produces alloy powder for rare earth magnets, into a reusable form. The rare earth magnets here can be, for example, RTB permanent magnets such as neodymium magnets (Nd-Fe-B permanent magnets). These RTB permanent magnets are R2T 14It is composed of crystal grains of a B-type crystal structure and the grain boundaries between them. In addition, 'R' in the RTB permanent magnet represents at least one rare earth element. Furthermore, 'T' represents iron (Fe), or iron (Fe) and cobalt (Co), but may represent the further inclusion of at least one transition metal element other than iron (Fe) or cobalt (Co). Furthermore, 'B' represents boron (B), or boron (B) and carbon (C). Furthermore, the RTB permanent magnet may contain copper (Cu), aluminum (Al), etc. The addition of such elements makes it possible to increase the coercive force, increase the corrosion resistance, or improve the temperature characteristics of the magnetic properties.

[0035] The kiln 91 is a furnace for producing alloy powder of rare earth magnets as described above. Specifically, (a-1) A raw alloy block for a rare earth magnet is made to absorb an absorbed gas (hydrogen (H2) gas in this embodiment), and this raw alloy block is subjected to a heat treatment at several hundred degrees Celsius in an atmosphere of an introduced noble gas (argon (Ar) gas in this embodiment) to release the absorbed gas (hydrogen gas), thereby roughly pulverizing the raw alloy block in a manner that causes it to self-disintegrate; (a-2) The released occluded gas (hydrogen gas) is then discharged outside the kiln 91 together with the noble gas (argon gas) as "furnace exhaust gas."

[0036] Incidentally, the raw alloy ingot coarsely pulverized in (a-1) above becomes alloy powder having a diameter of, for example, several hundred micrometers (μm), and in this embodiment, this alloy powder is collected in an alloy powder recovery container 93 provided outside the kiln. The collected alloy powder is then subjected to a fine pulverization process, and further to a compression molding process in a magnetic field, sintering, heat treatment, etc., to produce a rare earth magnet. It is also possible to transfer the alloy powder removed from the kiln 91 directly to a fine pulverization device without passing through the alloy powder recovery container 93.

[0037] Meanwhile, the "furnace exhaust gas" discharged in (a-2) above is transferred to the fine particle trap unit (U) 92, where the alloy powder remaining therein is separated and removed, and then the gas is discharged from the fine particle trap U92. As described above, this discharged "furnace exhaust gas" is a mixed gas containing the occlusion gas (hydrogen gas) and the noble gas (argon gas). The furnace exhaust gas regeneration device 1 regenerates this "furnace exhaust gas" into a gas with an increased concentration of noble gas (argon gas) (hereinafter also referred to as "noble gas (argon) concentration increased gas").

[0038] Therefore, the kiln exhaust gas regeneration device 1 specifically: (A) A noble gas extraction unit (argon gas extraction unit) 11 receives the "furnace exhaust gas" which is a mixed gas containing a noble gas (argon gas) and an occluded gas (hydrogen gas) discharged from the kiln 91, and converts the "furnace exhaust gas" into a "noble gas (argon) concentration increased gas" using either or both of a "gas filter" 113F and a "fuel cell" 116C (both in FIG. 1). It has.

[0039] Here, the "gas filter" 113F, which will be described in detail later, is a filter that has different degrees of permeability for the occluded gas (hydrogen gas) and the noble gas (argon gas). By introducing the "furnace exhaust gas" into this "gas filter" 113F, at least a portion of the occluded gas (hydrogen gas) is separated from the noble gas (argon gas), and thus a "noble gas (argon) concentration increased gas" can be extracted.

[0040] The "fuel cell" 116C, which will also be described in detail later, oxidizes the stored gas (hydrogen gas) (for example, converting it into oxides (water) or converting it into positive ions (H + By introducing the "furnace exhaust gas" into this "furnace fuel cell" 116C, at least a part of the occluded gas (hydrogen gas) is oxidized and removed from the "furnace exhaust gas", thereby making it possible to extract "gas with increased noble gas (argon) concentration".

[0041] Furthermore, by using both the "gas filter" 113F and the "fuel cell" 116C, it is possible to generate the "noble gas (argon) concentration increased gas" more effectively, for example with a higher recovery rate, as will be described in detail later with reference to Figures 1, 7 and 8. In any case, the kiln exhaust gas regeneration device 1 can regenerate the "kiln exhaust gas", which is a mixed gas containing the noble gas (argon gas) and the occlusion gas (hydrogen gas) discharged from the kiln 91, into a reusable gas ("noble gas (argon) concentration increased gas").

[0042] In addition, the furnace exhaust gas regeneration device 1 of this embodiment further includes: (B) A noble gas delivery unit (argon gas delivery unit) 12 that delivers the extracted "noble gas (argon) concentration-enhanced gas" to the kiln 91 or a gas reservoir for the kiln 91 (e.g., a gas supply tank for the kiln 91) so that the gas can be reused as a noble gas (argon gas) atmosphere during the production of alloy powder. It also has

[0043] This allows the reuse of expensive noble gas (argon gas), which has been used once and then diluted with nitrogen gas or the like and discharged to the outside for disposal. As a result, the use of new noble gas (argon gas) and nitrogen gas 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 gas extraction section) 11, noble gas delivery section (argon gas delivery section) 12), the kiln 91 (and possibly also the fine powder trap U92 and the alloy powder recovery container 93) constitute one embodiment of the kiln system according to the present invention. In this kiln system, the regenerated noble gas (noble gas (argon) concentration increased gas) can be reused.

[0044] Furthermore, when the "noble gas (argon) concentration-enriched gas" is reused in the kiln 91, by making the "noble gas (argon) concentration-enriched gas" a gas with a higher argon concentration (lower hydrogen concentration), it is possible to further promote the desorption (dehydrogenation) of hydrogen from the raw alloy block, shorten the processing time in the kiln 91, and perform a more efficient alloy powder manufacturing process. Furthermore, in such a reuse, even when expensive pure argon gas that has been prepared is mixed with the above-mentioned "argon concentration-enriched gas" to obtain the required high purity argon gas, it is possible to further reduce the amount of pure argon gas used.

[0045] In addition, when both the "gas filter" 113F and the "fuel cell" 116C are used, it is also possible to adopt a form in which they are provided in separate devices. Also, the noble gas delivery section (argon gas delivery section) 12 may be a component of a device separate from the noble gas extraction section (argon gas extraction section) 11. In any case, these devices as a whole constitute one embodiment of the kiln exhaust gas regeneration system according to the present invention. The configuration of the kiln exhaust gas regeneration device (system) 1 of this embodiment will be described in more detail below.

[0046] [Equipment / system configuration, kiln exhaust gas regeneration method] 1, the furnace exhaust gas regeneration device (system) 1 of this embodiment has an argon gas extraction section (noble gas extraction section) 11, an argon gas delivery section (noble gas delivery section) 12, and an overall control unit (U) 13. Of these, the argon gas delivery section 12 has a tank U121 and a delivery control U122.

[0047] In this embodiment, the argon gas extraction unit 11 is (a) a catalytic poison removal unit U111; (b) a blower U112a equipped with a blower 112aaa and a buffer tank 112ab, a gas compressor U112b, and a tank U112c; (c) filtering U113 with gas filter 113F; (d) Pressure control U114a, buffer tank U114b, and Ar compression U114c; (e) Buffer tank U115a, gas compressor U115b, tank U115c, gas compressor U115d, (f) fuel cell U116 having a fuel cell 116C; (g) Pressure control U117a, dehumidification U117b, and pressure control U117c, (h) filtering U118 with gas filter 118F; (i) Pressure control U119a, buffer tank U119b, and Ar compression U119c It has.

[0048] Furthermore, the kiln system of this embodiment is made up of the kiln exhaust gas regeneration device (system) 1 having these components, a kiln 91, a fine powder trap U92, and an alloy powder recovery container 93. Incidentally, the transfer of material and energy and the flow of the processes performed, which are shown by connecting the components in the device / system configuration diagram of Figure 1 with arrows, can also be understood as one embodiment of the kiln exhaust gas regeneration method of the present invention.

[0049] Also, different from this embodiment, the argon gas extraction unit 11 may have a filtering unit U113 and components (111-114c) provided before and after the filtering unit U113, but may not have (omit) a fuel cell U116 and components (115a-119c, the gray area in FIG. 1) provided before and after the fuel cell U116. Even in such an embodiment, it is possible to regenerate the furnace exhaust gas into a reusable argon concentration increased gas.

[0050] <Noble gas extraction means: Pre-filtering U113> Also in FIG. 1, the catalytic poison removal unit U111 performs a process for removing catalytic poisons that poison the catalyst of the fuel cell 116C to be used later from the kiln exhaust gas (mixed gas containing argon gas (noble gas) and hydrogen gas (absorption gas)) discharged from the kiln 91 (fine powder trap U92). Specifically, in this embodiment, 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 kiln exhaust gas. In fact, it has been confirmed that carbon monoxide (CO) gas is almost completely removed from the kiln exhaust gas at a temperature of 90° C. using a metal honeycomb (model D3PT2S40C) manufactured by Tanaka Kikinzoku Kogyo Co., Ltd. In addition, the catalytic poison removal unit U111 may further include a device for removing substances harmful to the gas filter 113F.

[0051] Here, it is also preferable to further provide a fine powder trap mechanism or fine powder filter mechanism for removing fine rare earth magnet powder remaining in the furnace exhaust gas at the upstream of the catalytic poison removal unit U111, thereby preventing the fine powder from adversely affecting the subsequent filtering process and fuel cell reaction process.

[0052] 1, in this embodiment, the blower U112a uses the blower 112aa to temporarily store the kiln exhaust gas from which the catalytic poison has been removed in a buffer tank 112ab for static pressure (>0.1 MPa), and then transfers it to the gas compressor U112b. In this way, by temporarily storing the kiln exhaust gas in the buffer tank 112ab via the blower 112aa, it is possible to suppress fluctuations in the gas pressure (of the mixed gas) in the kiln 91.

[0053] In fact, it has been found that if the gas pressure inside the kiln 91 fluctuates significantly, the particle size and crushability of the generated alloy powder will change, making it difficult to stably carry out the subsequent fine crushing, molding, sintering, and heat treatment processes. In response to this, the kiln exhaust gas is temporarily stored in a buffer tank 112ab via a blower 112aa, so that the outlet pressure of the kiln exhaust gas discharged from the kiln 91 (fine powder trap U92) can be stabilized to a roughly constant value, thereby suppressing fluctuations in the gas pressure inside the kiln 91.

[0054] Incidentally, the outlet pressure of the kiln 91 (fine powder trap U92) may be set to a value within a range of, for example, 0.080 to 0.110 MPa (approximately 0.790 to approximately 1.086 atm.) Moreover, the variation from this set value is preferably kept 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 capable of adjusting the blower capacity in response to fluctuations in the flow rate of the kiln exhaust gas discharged from the kiln 91 (fine powder trap U92) in order to keep the outlet pressure of the kiln exhaust gas as constant as possible as described above. 3 Large blowers with a blowing capacity of 0.5m / min or more 3 It is also preferable to use two small blowers (one each with a blowing capacity of 1000 / min or more) that can be switched according to the flow rate of the furnace exhaust gas. Of course, these blowers may also be inverter-controlled blowers.

[0056] Also in FIG. 1, the gas compressor U112b receives the furnace exhaust gas from the blower U112a (its buffer tank 112ab) and pressurizes it using a compressor (compatible with hydrogen gas and argon gas) provided therein, before transferring it to a mixed gas tank provided in the tank U112c. In this embodiment, the furnace exhaust gas is stored in the mixed gas tank at a high gas pressure of, for example, 1.1 MPa or slightly lower. If the compressor of the gas compressor U112b is an inverter-controlled compressor that can handle negative pressure and can also handle fluctuations in the inlet flow rate, the blower U112a described above can be omitted.

[0057] In this embodiment, the tank U112c transfers the furnace exhaust gas (mixed gas containing argon gas and hydrogen gas) stored in the mixed gas tank to the filtering U113 while adjusting the flow rate with the gas regulator and mass flow controller (or flow switch) provided. Here, the gas pressure when introduced into the filtering U113 is controlled to 0.3 to 0.9 MPa in this embodiment by the pressure control U114a (after the filtering U113) described later. It is also preferable that the tank U112c is provided with a hydrogen concentration meter (or argon concentration meter) ArH that 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 to set filtering conditions in the filtering process by the gas filter 113F described later, for example.

[0058] <Noble gas extraction means: Filtering U113> Also in FIG. 1, the filtering U113 uses the gas filter 113F provided to convert the introduced furnace exhaust gas into a reusable argon enriched gas, in this embodiment high purity argon gas.

[0059] In this embodiment, the gas filter 113F is (a) a filter inlet 113Fc for taking in the received high-pressure (0.3 to 0.9 MPa in this embodiment) furnace exhaust gas (a mixed gas containing argon gas and hydrogen gas) and introducing it into the hollow fiber 113Fd described below; (b) Hollow fiber 113Fd having different permeabilities for argon (Ar) and hydrogen (H2); (c) an argon side outlet 113Fa which is an outlet for the gas (high purity argon gas in this embodiment) that has passed through the hollow fiber 113Fd; (d) The hydrogen side outlet 113Fb is an outlet for the gas that has permeated the hollow fiber 113Fd, i.e., the "filtered gas" It is equipped with:

[0060] Among these, the hollow fiber fiber 113Fd of (b) is a hollow fiber polymer fiber that preferentially transmits hydrogen molecules (H2) over argon atoms (Ar). As high-pressure (0.3 to 0.9 MPa) furnace exhaust gas flows from the filter inlet 113Fc through the hollow fiber fiber 113Fd, hydrogen molecules selectively permeate the polymer fiber and exit, so that a reusable argon-enriched gas, or in this embodiment, high-purity argon gas, can be finally extracted from the argon-side outlet 113Fa.

[0061] Incidentally, it has been confirmed that the following nitrogen gas filters can be used as the gas filter 113F (an argon gas filter): the UBE N2 separator made by UBE (formerly Ube Industries) which uses aromatic polyimide hollow fibers; and the N2 membrane module nitrogen gas filter made by Polypla-Evonik which also uses aromatic polyimide hollow fibers.

[0062] Hereinafter, an embodiment of the filtering process of hydrogen from a mixed gas equivalent to a furnace exhaust gas will be described with reference to Figures 2 to 4. In the embodiment shown in Figures 2 to 4, the above-mentioned UBE N2 separator (2 inch diameter) is used as the gas filter 113F.

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

[0064] Subsequently, as the amount of hydrogen released decreases, the amount of argon gas introduced is increased to further expel hydrogen from the raw alloy block, and eventually the concentration (proportion) of hydrogen gas in the furnace exhaust gas becomes 10 vol% or less (i.e., argon gas becomes 90 vol% or more).

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

[0066] FIG. 2 is a graph for explaining an embodiment of the filtering process according to the present invention.

[0067] In Fig. 2(A1)-(C2), (a) A mixed gas of "argon gas (Ar):hydrogen gas (H2)=30vol%:70vol%" simulating the kiln exhaust gas discharged in the first half (of the process in the kiln 91), and a mixed gas of "argon gas (Ar):hydrogen gas (H2)=70vol%:30vol%" simulating the kiln exhaust gas discharged in the second half are introduced into the filter inlet 113Fc of the gas filter 113F, (b) For each mixed gas, a filtering process is performed by acting the mixed gas on hollow fiber 113Fd under conditions in which the outlet pressure (gas pressure at argon side outlet 113Fa) is 0.4 MPa and 0.7 MPa, and the outlet flow rate (gas flow rate at argon side outlet 113Fa) is 1.0 liters (L) / min, 3.0 L / min, and 5.0 L / min, respectively; (c) The dependence of the residual hydrogen concentration (ppm, parts per million by volume) in the gas extracted from the argon side outlet 113Fa on the elapsed treatment time was investigated. The results are shown.

[0068] According to Figures 2 (A1), (B1) and (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 (asymptotic hydrogen concentration) over the treatment time. In addition, for all outlet flow rates, the mixed gas "Ar:H2=70vol%:30vol%" shows a smaller asymptotic hydrogen concentration value than the mixed gas "Ar:H2=30vol%:70vol%". Incidentally, when the outlet flow rate is 1.0 L / min, the asymptotic hydrogen concentration value of the mixed gas "Ar:H2=70vol%:30vol%" was below the measurement limit of the concentration meter ArH and could not be measured.

[0069] 2(A2), (B2), and (C2) show that even when the outlet pressure is 0.7 MPa, the smaller the outlet flow rate for both mixed gases, the smaller the asymptotic hydrogen concentration value becomes. This asymptotic hydrogen concentration value is smaller than that when the outlet pressure is 0.4 MPa and the outlet flow rate is the same (i.e., the higher the outlet pressure, the smaller the residual hydrogen concentration).

[0070] Furthermore, when the outlet pressure is 0.7MPa, unlike the above case where the outlet pressure is 0.4MPa, at each outlet flow rate, the hydrogen concentration asymptotic value of the mixed gas of "Ar:H2=30vol%:70vol%" and the hydrogen concentration asymptotic value of the mixed gas of "Ar:H2=70vol%:30vol%" are roughly the same. Incidentally, when the outlet flow rate is 1.0L / min, the hydrogen concentration asymptotic values ​​of both mixed gases were below the measurement limit of the ArH concentration meter and could not be measured.

[0071] From the above results, one filtering condition is: (A1) When the outlet pressure is set relatively low (for example, 0.4 MPa as mentioned above), when the hydrogen concentration of the furnace exhaust gas is initially high, filtering is performed with as small an outlet flow rate as possible in order to achieve the target (or required) sufficiently low residual hydrogen concentration. (a2) After that, in accordance with the decreasing hydrogen concentration value in the furnace exhaust gas (or as the treatment time passes), the outlet flow rate is increased stepwise (or continuously) to a desired sufficiently large value within a range that allows the target (or required) sufficiently low residual hydrogen concentration to be achieved. It can also be seen that this is preferable.

[0072] In addition, as another filtering condition, (a) When the outlet pressure is set to a sufficiently large value (for example, 0.7 MPa as mentioned above), the outlet flow rate is set to a desired sufficiently large value within a range that can achieve the target (or required) sufficiently low residual hydrogen concentration regardless of fluctuations in the hydrogen concentration of the furnace exhaust gas. In any case, it is also preferable that the outlet pressure is set to a larger value within the settable range.

[0073] As described above, the filtering U113 determines the outlet pressure and / or outlet flow rate as filtering conditions according to the (time-varying) concentration of argon gas or hydrogen gas in the received furnace exhaust gas, and performs a filtering process on the furnace exhaust gas with the determined outlet pressure and / or outlet flow rate to produce high-purity argon gas with a target (or required) sufficiently low residual hydrogen concentration.

[0074] In other words, the filter U113 performs filtering processing on the furnace exhaust gas with a gas flow rate set to reduce the residual hydrogen concentration, or with a gas flow rate (a desired sufficiently large gas flow rate) within a gas flow rate range set to reduce the residual hydrogen concentration, thereby producing a high-purity argon gas with a target (or required) sufficiently low residual hydrogen concentration. In this filtering processing, it is also preferable to set the outlet pressure to a larger value within a settable range.

[0075] In this embodiment, for example, when the outlet pressure is set to 0.4 MPa, the outlet flow rate is suppressed to about 3.0 L / min in the first half of the treatment in the kiln 91 (for example, when the hydrogen concentration in the kiln exhaust gas is 70 vol%), and the outlet flow rate is increased to about 5.0 L / min in the second half (for example, when the hydrogen concentration in the kiln exhaust gas is 30 vol%), thereby consistently maintaining the residual hydrogen concentration at 10 3 It is possible to generate high-purity argon gas in the ppm range. In addition, when the outlet pressure is set to 0.7 MPa, for example, even if the outlet flow rate is consistently set to a large value of 5.0 L / min, the residual hydrogen concentration is only 10 1 It is possible to produce high-purity argon gas in the ppm range.

[0076] Fig. 3 is a table showing the results of measuring the hydrogen concentration at the hydrogen side outlet 113Fb in the embodiment of Fig. 2. Here, as described above, gas that has permeated the hollow fiber 113Fd, i.e., "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), the hydrogen concentration of the "filtered gas" generated from the mixed gas of "Ar:H2=30vol%:70vol%" increases from 70.7vol% (roughly matching the original mixed gas of 70vol%) to 92.0vol% as the (argon side) outlet flow rate increases in the order of 0, 1.0, 2.0, 3.0, 5.0 and 10.0L / min under the condition of an outlet pressure of 0.4MPa. The hydrogen concentration of the "filtered gas" generated from the mixed gas of "Ar:H2=30vol%:70vol%" also shows a similar trend with increasing (argon side) outlet flow rate.

[0078] Furthermore, as shown in Fig. 3(B), even under the condition of an outlet pressure of 0.7 MPa, the hydrogen concentrations of both "filtered gases" show a similar tendency with respect to an increase in the (argon side) outlet flow rate. Incidentally, the (argon side) outlet flow rate of "0" in Figs. 3(A) and (B) means that the argon side outlet 113a of the gas filter 113F is blocked and the mixed gas is introduced into the gas filter 113F. Note that the hydrogen concentrations of each "filtered gas" are smaller at the same outlet flow rate when the outlet pressure is 0.7 MPa than when it is 0.4 MPa.

[0079] 3(A) and (B), the hydrogen concentration of the "filtered gas" is higher than that of the original mixed gas (70 vol%, 30 vol%) as a result of hydrogen selectively passing through the hollow fiber fiber 113Fd, and the difference is larger as the outlet flow rate is higher. However, due to the characteristics of the hollow fiber fiber 113Fd (gas filter 113F), it can also be seen that the "filtered gas" contains a considerable amount of argon gas. Therefore, in this embodiment, in order to further recover the argon gas contained in the "filtered gas", a fuel cell U116 is used, as will be described in detail later.

[0080] Hereinafter, an embodiment in which filtering conditions for reducing the argon concentration in the "filtered gas" were obtained and carried out will be described with reference to Fig. 4. Fig. 4 is a graph for explaining another embodiment of the filtering process according to the present invention.

[0081] Here, Figures 4 (A1) and (B) are graphs showing the dependence of the "argon gas discharge rate from the argon side outlet 113Fa" on the (argon side) outlet flow rate and the (argon side) outlet pressure, respectively. The argon gas (in the mixed gas) introduced from the filter inlet 113Fc to the hollow fiber fiber 113Fd is discharged from either the "argon side outlet 113Fa" or the "hydrogen side outlet 113Fb." The "argon gas discharge rate from the argon side outlet 113Fa" refers to the rate of that discharged from the "argon side outlet 113Fa."

[0082] Also, the "hydrogen gas discharge ratio from hydrogen side outlet 113Fb" in Fig. 4(C2) is the ratio of hydrogen gas (in the mixed gas) discharged from the "hydrogen side outlet 113Fb". Furthermore, the "discharge ratio" in the remaining graphs is an amount that can be grasped in a similar manner. Incidentally, in this embodiment, a mixed gas of "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 gas discharge rate from the argon side outlet 113Fa" increases as the outlet flow rate increases. In addition, among the cases where the outlet pressure is 0.4, 0.5, 0.6, and 0.7 MPa, the rate is the highest when the outlet pressure is 0.5 MPa. Meanwhile, as is to be expected, the "argon gas discharge rate from the hydrogen side outlet 113Fb" has the opposite result to the above, as shown in Fig. 4(A2).

[0084] Here, Fig. 4(B) shows that the "argon gas discharge rate from the argon side outlet 113Fa" is 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), the graph is roughly the same for other outlet flow rate values ​​(except for 0.1 L / min).

[0085] According to FIG. 4(B), it can be seen that the "argon gas discharge rate from argon side outlet 113Fa" is 100% when the outlet flow rate is 10.3 L / min and the outlet pressure is 0.5 MPa. In other words, under these conditions, it is possible to recover (almost) 100% of the argon gas from argon side outlet 113Fa. It can also be seen that it is possible to specify and set a "predetermined range" such that the recovery rate of argon gas from argon side outlet 113Fa is, for example, 99% or more, if the outlet flow rate is in a "predetermined range" of about 10.3 L / min and the outlet pressure is in a "predetermined range" of about 0.5 MPa.

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

[0087] Furthermore, by reusing the "filtered gas" with a higher hydrogen concentration (lower argon concentration) in the kiln 91, it is possible to promote the absorption of hydrogen (hydrogen absorption) into the raw alloy block, shorten the processing time in the kiln 91, and perform a more efficient alloy powder manufacturing process. Furthermore, in such a case of mixing expensive pure hydrogen gas that has been prepared with the "filtered gas" to obtain hydrogen gas of the required high purity, it is possible to reduce the amount of pure hydrogen gas used.

[0088] In summary, the filtering U113 performs a filtering process on the furnace exhaust gas with a gas pressure set to increase the argon gas recovery rate (the proportion discharged from the argon side outlet 113Fa), or with a gas pressure within a range of gas pressure values ​​set to increase the argon gas recovery rate, thereby making it possible to recover argon gas at a target (or required) sufficiently high recovery rate (gas with an increased argon concentration can be extracted). In this case, by making the outlet flow rate as large as possible, it is also possible to achieve a high argon gas recovery rate, for example, close to 100%.

[0089] Furthermore, the filter U113 can apply the furnace exhaust gas to the gas filter 113F and extract gas with an increased hydrogen concentration from the hydrogen outlet 113b. In this case, by carrying out the filtering process under filtering conditions that increase the recovery rate of the argon gas described above, it is also possible to recover reusable high-purity hydrogen gas.

[0090] Next, the hydrogen gas discharge rate (at the argon side outlet 113Fa and the hydrogen side outlet 113Fb) will be explained using Figures 4 (C1) and (C2). According to Figure 4 (C1), the "hydrogen gas discharge rate from the argon side outlet 113Fa" becomes lower as the outlet flow rate becomes smaller and as the outlet pressure becomes higher. Meanwhile, as is to be expected, the "hydrogen gas discharge rate from the hydrogen side outlet 113Fb" has the opposite result to the above, as shown in Figure 4 (C2).

[0091] 4(A1) and (A2), the recovery rate of argon gas (from the argon-side outlet 113Fa) increases when the outlet flow rate is increased, but the amount of hydrogen gas discharged from the argon-side outlet 113Fa increases. Also, with regard to the outlet pressure, the amount of hydrogen gas discharged from the argon-side outlet 113Fa is not minimized at the outlet pressure at which the recovery rate of argon gas is maximized.

[0092] For the above reasons, the filtering conditions are, for example, (a) Under an outlet pressure in a pressure range (for example, the range of about 0.5 MPa shown in FIG. 4(B)) that maximizes the recovery rate of argon gas from the argon side outlet 113Fa, (b) The hydrogen concentration of the gas discharged from the argon side outlet 113Fa is within the target (or required) upper limit (e.g., 1.0×10 3 The maximum outlet flow rate among the outlet flow rates that are below 1 ppm It can be seen that by performing the filtering process, it is possible to produce as much high-purity argon gas as possible with a high recovery rate.

[0093] Furthermore, when the argon gas is further recovered using the fuel cell 116C as in this embodiment, it is also preferable to prioritize reduction of the hydrogen concentration in the filter U113 and perform the filtering process at the outlet flow rate of (b) above under the outlet pressure as high as possible. On the other hand, in another embodiment in which the argon gas is recovered only by the gas filter 113F without using the fuel cell 116C, it is also possible to prioritize improvement of the recovery rate and perform the filtering process at the outlet pressure of (a) above and with the outlet flow rate as high as possible.

[0094] FIG. 5 is a schematic diagram for explaining various embodiments of the gas filter arrangement in the filtering U113 according to the present invention.

[0095] Fig. 5(A) shows the arrangement of one gas filter 133F (as described above). The filtering U113 may perform filtering using one gas filter 133F in this way, but it is also preferable to perform filtering by arranging and connecting two or more gas filters in parallel as shown in Fig. 5(B) in order to perform filtering on a larger amount (of flow rate) of furnace exhaust gas.

[0096] Specifically, in the embodiment of Fig. 5(B), three gas filters 113F1, 113F2, and 113F3 are provided, and the (high-pressure) furnace exhaust gas is introduced separately into each gas filter (113F1, 113F2, 113F3), and the gases extracted from the argon side outlets of each gas filter (113F1, 113F2, 113F3) are combined to form an argon concentration-enriched gas, which is high-purity argon gas in this embodiment. Here, the gases discharged from the hydrogen side outlets of each gas filter (113F1, 113F2, 113F3) are also combined and then treated as the above-mentioned "filtered gas".

[0097] In this way, by filtering the furnace exhaust gas using multiple gas filters arranged in parallel, it is possible to reduce the outlet flow rate of each gas filter while maintaining the desired large overall outlet flow rate, thereby making it possible to suppress the hydrogen concentration of the gas discharged from the argon side outlet to a targeted (or required) low value.

[0098] Here, an example carried out in relation to the embodiment of FIG. 5(B) will be described. In the examples shown in FIGS. 2 to 4, as described above, a gas filter (UBE N2 separator) equipped with aromatic polyimide hollow fiber fibers having a diameter of 2 inches was used. In contrast, a gas filter (nitrogen gas filter manufactured by Polypla-Evonik Co., Ltd.) equipped with aromatic polyimide hollow fiber fibers having a diameter of 4 inches was used as a gas filter capable of achieving the same effect as the parallel arrangement of gas filters in FIG. 5(B), and hydrogen was filtered from a mixed gas equivalent to a furnace exhaust gas. Specifically, a mixed gas of "Ar:H2=70vol%:30vol%" was introduced into a 4-inch gas filter (manufactured by Polypla-Evonik Co., Ltd.) and the hydrogen concentration of the gas (high-purity argon gas) 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, as in the embodiment described above (FIG. 2). However, because a large-diameter (4-inch diameter) hollow fiber 113Fd was used, high-purity argon gas with a very low hydrogen concentration of about 1 ppm could be extracted from the argon-side outlet 113Fa even at a relatively low (argon-side) outlet pressure of, for example, 0.28 MPa and a relatively high (argon-side) outlet flow rate of, for example, 10 L / min.

[0100] As another embodiment, as shown in Fig. 5(C), it is also possible to perform filtering by connecting two or more (four in Fig. 5(C)) gas filters in a multi-stage cascade. Specifically, in the embodiment of Fig. 5(C), the furnace exhaust gas is introduced into the first-stage gas filter 113F1, then the gas (filtered gas) discharged from the hydrogen side outlet of this gas filter 113F1 is introduced into the second-stage gas filter 113F2, and further the gas (filtered gas) discharged from the hydrogen side outlet of this gas filter 113F2 is introduced into the third-stage gas filter 113F3, and further the gas (filtered gas) discharged from the hydrogen side outlet of this gas filter 113F3 is introduced into the fourth-stage gas filter 113F4, and the gas discharged from the hydrogen side outlet of this gas filter 113F4 is treated as the above-mentioned "filtered gas".

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

[0102] Here, a specific example of the recovery rate of argon gas when the embodiment of Fig. 5(C) is adopted will be described. Incidentally, hereinafter, the recovery rate of argon gas is calculated as the ratio of (a) the argon gas outlet flow rate (= (gas flow rate at the argon gas outlet) x (argon concentration at the argon gas outlet)) to (b) the argon gas inlet flow rate (= (gas flow rate at the inlet) x (argon concentration at the inlet)).

[0103] First, a specific example will be described in which the above-mentioned 4-inch diameter nitrogen gas filter manufactured by Polypla-Evonik is used as each gas filter (113F1, 113F2, 113F3, 113F4) in the embodiment of FIG. 5(C). It is known that with this nitrogen gas filter, for example, when the inlet pressure is 0.32 MPa and the inlet flow rate of argon gas is within a predetermined range, the recovery rate of argon gas is about 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 a buffer tank and a compressor (compressor) provided before and after the gas filter, so that the recovery rate of argon gas of each gas filter (113F1, 113F2, 113F3, 113F4) is set to about 34%.

[0104] In this case, the proportion of argon gas recovered from the argon side outlets of the four-stage gas filters (113F1, 113F2, 113F3, 113F4) out of the argon gas introduced into the gas filter 113F1, that is, the recovery rate of this four-stage configuration, reaches approximately 81%.

[0105] Next, a specific example will be described in which the above-mentioned 2-inch diameter UBE N2 separator is used as each of the gas filters (113F1, 113F2, 113F3, 113F4) in this four-stage configuration. It is known that this nitrogen gas filter has an argon gas recovery rate of about 60% under specified conditions. Therefore, in this specific example, the inlet pressure and inlet flow rate of each gas filter (113F1, 113F2, 113F3, 113F4) are adjusted by a buffer tank and a compressor (compressor) provided before and after the gas filter, so that the argon gas recovery rate of each gas filter (113F1, 113F2, 113F3, 113F4) is set to about 60%.

[0106] In this case, the recovery rate of this four-stage configuration reaches approximately 97%. Furthermore, the recovery rates of a three-stage configuration and a two-stage configuration using the same nitrogen gas filter (a two-inch diameter UBE N2 separator) are also high, at approximately 94% and 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] The above describes a specific example of increasing the recovery rate of argon gas using a gas filter with a multi-stage cascade configuration. If the target (or required) recovery rate (e.g., 90%) is not achieved, it is also preferable to further extract and recover argon gas from the "filtered gas" extracted from this multi-stage cascade configuration using a fuel cell U116, as will be described later.

[0108] <Noble gas extraction means: after filtering U113> Returning to FIG. 1, in this embodiment, the pressure control U114a provided downstream of the filtering U113 is equipped with a back pressure valve and a pressure gauge, and controls the outlet pressure of the argon concentration increased gas (high purity argon gas in this embodiment) discharged from the argon side outlet 113Fa of the gas filter 113F, and thus the gas pressure of the furnace exhaust gas introduced into the filtering U113.

[0109] Here, the high-purity argon gas (argon concentration increased gas) that has passed through the pressure control U114a is then temporarily stored in an argon gas buffer tank (with an internal tank pressure of, for example, about 0.2 MPa) provided in the buffer tank U114b, and is then pressurized by a compressor (compatible with argon gas) provided in the Ar compression U114c, before being transferred to the argon gas tank provided in the tank U121, where it is stored.

[0110] The above has explained the filtering process of hydrogen gas in the filter U113. Below, we will explain the process of converting the "filtered gas" extracted from the gas filter 113F into an argon concentration increased gas (high purity argon gas in the following embodiment) using the fuel cell 116C.

[0111] <Noble gas extraction means: Front stage of fuel cell U116> Also in FIG. 1, the "filtered gas" (mixed gas containing argon gas and hydrogen gas) discharged from the hydrogen side outlet 113Fb of the gas filter 113F is first stored in a mixed gas buffer tank (internal tank pressure: for example, approximately 0.2 MPa) provided in the buffer tank U115a, and then is pressurized by a compressor (compatible with argon gas and hydrogen gas) provided in the gas compressor U115b, before being transferred to the mixed gas gas tank provided in the tank U115c, where it is stored.

[0112] Thereafter, the stored mixed gas is transferred to the fuel gas chamber side inlet of the fuel cell U116 at a high gas pressure of 0.2 to 1.0 MPa in this embodiment. Here, this gas pressure is controlled by a pressure controller U117a (at the rear stage of the fuel cell U116) which will be described later. Also, the gas flow rate when transferred to the fuel gas chamber side inlet is controlled by a gas regulator and a mass flow controller (or a flow switch) provided in the tank U115c.

[0113] 1, in this embodiment, the gas compressor U115d takes in air, for example, from the atmosphere, and transfers the air to the oxidizing gas chamber side inlet of the fuel cell U116 at a high gas pressure of 0.2 to 1.0 MPa using a compressor provided in the gas compressor. Of course, the compressed air may first be stored in an air tank provided and then transferred to the fuel cell U116.

[0114] <Method of extracting noble gas: Fuel cell U116> Also in FIG. 1, the fuel cell U116 uses the fuel cell 116C to oxidize hydrogen (H2) in the mixed gas (containing argon gas and hydrogen gas) introduced into the fuel gas chamber (for example, to convert it into water (H2O) or to generate positive ions (H + ) to convert the introduced mixed gas into an argon-enriched gas (or high-purity argon gas).

[0115] More specifically, the fuel cell U116 of this embodiment has: (a) A mixed gas (filtered gas) containing argon gas and hydrogen gas transferred from the tank U115c is introduced into the fuel gas chamber of the fuel cell 116C at a high gas pressure of 0.2 to 1.0 MPa, while (b) The air transferred from the gas compressor U115d is taken into the oxidizing gas chamber of the fuel cell 116C at a high gas pressure of 0.2 to 1.0 MPa, which is equivalent to the gas pressure of the mixed gas in (a) above. (c) A fuel cell reaction is caused between the hydrogen contained in the mixed gas of (a) above and the oxygen contained in the air of (b) above via an electrolyte layer provided between the fuel gas chamber and the oxidizing gas chamber.

[0116] As a result of this fuel cell reaction, fuel cell U116 then: (d) Exhaust gas with reduced hydrogen concentration (i.e., argon concentration-enriched gas) discharged from the fuel gas chamber side (hydrogen electrode) outlet of the fuel cell 116C, (e) Exhaust gas with reduced oxygen concentration discharged from the outlet of the oxidizing gas chamber side (oxygen electrode) of the fuel cell 116C; (f) The electric power (electromotive force) generated between the hydrogen electrode in the fuel gas chamber and the oxygen electrode in the oxidizing gas chamber, (g) Heat (calorie) generated by the fuel cell reaction as heat of chemical reaction It outputs:

[0117] Of these, the electric power (f) above may be provided to the kiln 91 and used as electric power for, for example, heat treatment in the kiln 91. The heat (g) above may also be provided to the kiln 91 using a heat exchange means and used as the base heat for, for example, heat treatment in the kiln 91.

[0118] In this embodiment, both the hydrogen contained in the mixed gas (a) and the oxygen contained in the air (b) participate in the fuel cell reaction via the electrolyte layer at a high pressure of 0.2 to 1.0 MPa, i.e., at a higher physical density, as described above. As a result, the efficiency of the fuel cell reaction is improved, and the exhaust gas (a) becomes an argon-enriched gas with a reduced hydrogen concentration (and therefore a higher argon concentration).

[0119] Of course, the fuel cell U116 may be one in which the fuel cell reaction proceeds under normal conditions other than the above high pressures. However, by introducing the above (a) mixed gas and the above (b) air 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 more, it is also possible to extract an argon-enriched gas (or high-purity argon gas) with a reduced hydrogen concentration.

[0120] The fuel cell 116C may have a known configuration, for example, a configuration in which a plurality of cells, each 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 with a separator interposed therebetween. In this case, each cell has a structure in which an oxidizing gas chamber on the air electrode side and a fuel gas chamber on the hydrogen electrode side are provided so as to sandwich an electrolyte layer therebetween.

[0121] Furthermore, the fuel cell 116C may be a polymer electrolyte fuel cell (PEFC) in this embodiment. PEFCs operate at relatively low temperatures and can be made compact in cell size, and are therefore used in many fuel cell vehicles, for example. However, it is of course possible to use solid oxide fuel cells (SOFCs), phosphoric acid fuel cells (PAFCs), molten carbonate fuel cells (MCFCs), and the like, as the fuel cell 116C. Among these, SOFCs have high power generation efficiency, usually operate at about 700 to about 1000°C, and are capable of supplying considerably high-temperature exhaust gas, i.e., argon-enriched gas.

[0122] Incidentally, it has been confirmed that in the fuel cell 116C, even if argon that does not contribute to the fuel cell reaction (is not oxidized) is mixed in the fuel gas chamber, power is generated according to the amount of hydrogen in the fuel gas chamber and the amount of oxygen in the oxidizing gas. In other words, it is known that argon in the mixed gas does not generally have a negative effect on the fuel cell reaction, even if its concentration is about 70 vol%. This fact also makes it possible for the fuel cell 116C to use its inherent function to oxidize hydrogen in the mixed gas and generate argon concentration-enhanced gas (or high-purity argon gas).

[0123] <Noble gas extraction means: after the fuel cell U116> As also shown in FIG. 1, the exhaust gas with reduced hydrogen concentration, i.e., argon concentration increased gas (or high purity argon gas), discharged from the fuel gas chamber side outlet of the fuel cell 116C, then has some condensed water removed in the drain Da, has the gas pressure (as the back pressure of the fuel cell 116C) controlled by a pressure control U117a equipped with a back pressure valve and a pressure gauge, is subjected to a dehumidification process in the dehumidification U117b, and is then transferred to the filtering U118, which will be described later in this embodiment.

[0124] In this embodiment, the dehumidifier U117b is a unit that reduces or removes moisture and water vapor in the mixed gas using a dry filter having a water vapor permeable hollow fiber membrane. In this case, the gas pressure (0.3 to 0.9 MPa in this embodiment) of the argon concentration increased gas introduced into the dry filter is controlled by a pressure controller U119a (after the filtering U118) to be described later. In a modified embodiment, the dehumidifier U117b may be a unit that reduces or removes moisture and water vapor in the mixed gas using a dehumidifier containing silica gel or zeolite, a dehumidifying device equipped with a pressurizing mechanism, a gas-liquid separator, or the like.

[0125] On the other hand, the exhaust gas (as low-oxygen air) discharged from the oxidizing gas chamber then has some condensation water removed in the drain Db, and the gas pressure (as the back pressure of the fuel cell 116C) is controlled by the pressure control U117c, which is equipped with a back pressure valve and a pressure gauge, before being discarded (released) into the atmosphere in this embodiment.

[0126] As another embodiment, the gas dehumidified in the dehumidifier U117b (discharged from the fuel gas chamber side outlet) may be transferred as argon concentration increased gas (or high purity argon gas) via a pressure controller U119a (described later) to a buffer tank 119b and further to a tank U121 without passing through a filtering unit U118 (described later). For example, when an argon concentration increased gas having a targeted (or required) high argon concentration can be obtained by processing in the fuel cell U116, it is preferable to adopt such an embodiment.

[0127] <Noble gas extraction method: Filtering U118> Also in FIG. 1, the filtering U118 uses the gas filter 118F provided to convert the argon concentration increased gas discharged from the fuel gas chamber of the fuel cell 116C and introduced via the pressure control U117a and dehumidification U117b into an argon concentration increased gas having an increased argon concentration, which in this embodiment is high purity argon gas.

[0128] Here, in this embodiment, the gas filter 118F can be the same as the gas filter 113F described above. It is also preferable that the filtering U118 uses such a gas filter 118F and performs filtering processing under filtering conditions (outlet pressure, outlet flow rate, etc.) that are set based on the residual hydrogen concentration of the introduced argon concentration-enriched gas and are the same as those described for the gas filter 113F (using FIGS. 2 to 4). In this embodiment, the gas flow rate to the gas filter 118F is controlled by a gas regulator and a mass flow controller (or a flow switch) provided in the dehumidification U117b.

[0129] Furthermore, the filtering U118 may also use a plurality of gas filters 118F arranged and connected in the same manner as in the configurations shown in Fig. 5(B) and Fig. 5(C) to generate high-purity argon gas (argon-enriched gas). It is also preferable that the "filtered gas" discharged from the hydrogen-side outlet of the gas filter 118F is returned to the buffer tank U115a (just before the buffer tank) and processed again in the fuel cell U116. This can further reduce the amount of hydrogen gas in the "filtered gas", and can also reduce the amount of argon gas to be discarded (released), thereby increasing the final recovery rate of argon gas.

[0130] In any case, in this embodiment, the filtering U118 is similar to the filtering U113 described above, and filters, for example, gas having a residual hydrogen concentration of 10 1 ~10 3 It is also possible to output high-purity argon gas in the ppm range.

[0131] <Noble gas extraction means: after filtering U118> 1, the pressure control U119a provided in the rear stage of the filtering U118 includes a back pressure valve and a pressure gauge in this embodiment, and controls the outlet pressure of the high purity argon gas (argon concentration increased gas) discharged from the argon side outlet of the gas filter 118F, and in turn the gas pressure of the argon concentration increased gas introduced into the filtering U118. Note that in this embodiment, the pressure control U119a also controls the gas pressure of the argon concentration increased gas introduced into the dehumidification U117b (including a dry filter in this embodiment) in the front stage of the filtering U118.

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

[0133] As described above in detail, according to the argon gas extraction unit 11 of this embodiment, by using the fuel cell U116 (and in this embodiment also the filtering U118) provided downstream of the filtering U113 (the hydrogen side outlet 113Fb of the gas filter 113F provided in the filtering U113), it is possible to further increase the recovery rate of argon gas from the furnace exhaust gas.

[0134] In the argon gas extraction unit 11 of this embodiment, the gas pressure of the furnace exhaust gas (mixed gas) to be treated is 0.3 to 0.9 MPa in the filtering U113, 0.2 to 1.0 MPa in the fuel cell U116 at the rear stage, and 0.3 to 0.9 MPa in the filtering U118 at the rear stage. In addition, the gas pressure in the units and flow paths between them is kept at a gas pressure exceeding atmospheric pressure (about 0.1 MPa), and in this embodiment, a high gas pressure of 0.2 MPa or more (including the fuel cell U116, the dehumidifier U117b (equipped with a dry filter), and the filtering U118). That is, the argon gas extraction unit 11 of this embodiment is a series of high-pressure gas treatment systems.

[0135] This promotes the filtering process and fuel cell reaction, which are essential for the extraction and recovery of argon gas, and makes it possible to generate a larger amount (for example, at a larger gas flow rate) of argon-enriched gas (high-purity argon gas) with a higher argon concentration. It also makes it possible to increase the final recovery rate of argon gas (from the furnace exhaust gas). However, as already mentioned, it is of course possible to operate the fuel cell 116C under normal conditions (not under high pressure as in this embodiment). In this case, a gas compressor U is provided immediately before the filtering U 118.

[0136] <Precious gas delivery means: Tank U, delivery control U> 1, the tank U121 stores (a) high-purity argon gas (argon-enriched gas) transferred from the Ar compressor U114c and (b) high-purity argon gas (argon-enriched gas) transferred from the Ar compressor U119c at a predetermined gas pressure. Here, in this embodiment, this predetermined gas pressure is set according to the set (or required) supply gas pressure when the high-purity argon gas (argon-enriched gas) is supplied to the kiln 91.

[0137] Also in FIG. 1, the discharge control U122 is a unit equipped with a gas regulator and a mass flow controller (or flow switch) for supplying high-purity argon gas (argon-enriched gas) taken out of the tank U121 to the kiln 91 at a set (or required) specified gas flow rate.

[0138] <Overall control means> Also in FIG. 1, in this embodiment, the overall control U13 is equipped with a memory that stores an overall control program and a processor (computer), and further includes a communication interface that can communicate with predetermined units provided in the argon gas extraction unit 11 and the argon gas delivery unit 12. (a) Based on the contents of the monitor signal (hydrogen concentration or argon concentration) received from the hydrogen concentration meter (or argon concentration meter) ArH installed in the tank U112c and the buffer tank U114b, a control signal is sent to the filtering unit U113 and the specified units before and after it to set and adjust the filtering conditions (outlet pressure, outlet flow rate, etc.) during the filtering process, (b) Controlling the start and end of the fuel cell reaction in the fuel cell U116, sending control signals to the fuel cell U116 and to specific units before and after it, to 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) Based on the contents of the monitor signal (hydrogen concentration or argon concentration) received from the hydrogen concentration meter (or argon concentration meter) ArH installed in the dehumidifier U117b and the buffer tank U119b, a control signal is sent to the filtering unit U118 and the units before and after it to set and adjust the filtering conditions (outlet pressure, outlet flow rate, etc.) during the filtering process. (d) Upon receiving a supply command for high-purity argon gas (gas with increased argon concentration) from the outside, a control signal is sent to the delivery control U122 to deliver (provide) high-purity argon gas (gas with increased argon concentration) at a specified gas flow rate to the kiln 91. It is possible.

[0139] Here, the above control processes (a) to (d) are realized by a processor (computer) mounted in the overall control U13 executing the above overall control program.

[0140] [Other embodiments of the kiln exhaust gas regeneration device / system] FIG. 6 is a schematic diagram showing another embodiment of a furnace exhaust gas regeneration device / system according to the present invention.

[0141] As shown in Fig. 6, the kiln exhaust gas regeneration device (system) 2 of this embodiment first converts the kiln exhaust gas discharged from the kiln 91 (fine powder trap U92) into an argon-enriched gas (high-purity argon gas) by treating it in the fuel cell U216. Next, this argon-enriched gas (high-purity argon gas) is treated in a filtering U213 provided at the rear of the outlet of the fuel gas chamber side (hydrogen electrode side) of the fuel cell 216C (provided in the fuel cell U216) to generate high-purity argon gas (argon-enriched gas).

[0142] Specifically, the furnace exhaust gas regeneration device (system) 2 includes an argon gas extraction unit (noble gas extraction unit) 21, an argon gas delivery unit (noble gas delivery unit) 22, and an overall controller U23. Of these, the argon gas delivery unit 22 includes a tank U221 and a delivery controller U222. In this embodiment, the argon gas extraction unit 21 includes: (a) a catalytic poison removal unit U211; (b) Buffer tank U215a, gas compressor U215b, tank U215c, gas compressor U215d, (c) fuel cell U216 comprising fuel cell 216C; (d) Pressure control U217a, dehumidification U217b, and pressure control U217c; (e) filtering U213 with gas filter 213F; (f) Pressure control U214a, buffer tank U214b, and Ar compression U214c It has.

[0143] Here, the above-mentioned components: "(name)2**(*)" (* is a number or an English letter) may be components having the same structure and function as those of the components: "(name)1**(*)" of the kiln exhaust gas regeneration device (system) 1 shown in FIG. 1, which have the same (name) and (**(*)). For example, the fuel cell 216C and the fuel cell U216 may have the same structure and function as the fuel cell 116C (FIG. 1) and the fuel cell U116 (FIG. 1), respectively. However, in this embodiment, the buffer tank U215a is a unit equipped with not only the buffer tank (215ab) but also the blower 215aa. Here, the blower 215aa and the buffer tank 215ab have the same structure and function as the blower 112aa and the buffer tank 112ab of the blower U112a (FIG. 1), respectively.

[0144] Such a furnace exhaust gas regeneration device (system) 2 can also regenerate the furnace exhaust gas into a reusable argon concentration-enriched gas, or in this embodiment, high-purity argon gas.

[0145] In this embodiment, it is also preferable that the "filtered gas" discharged from the hydrogen side outlet 213Fb of the gas filter 213F provided in the filtering U213 is returned to (just before) the buffer tank U215a and processed again in the fuel cell U216. This reduces the amount of argon gas to be discarded (released), and also makes it possible to increase the final recovery rate of argon gas.

[0146] Furthermore, in the argon gas extraction unit 21 of this embodiment, the gas pressure of the furnace exhaust gas (mixed gas) to be treated is 0.2 to 1.0 MPa in the fuel cell U216, and 0.3 to 0.9 MPa in the subsequent filtering U213. In addition, in the units and flow paths between them, a gas pressure exceeding atmospheric pressure (about 0.1 MPa) is maintained, and in this embodiment, a high gas pressure of 0.2 MPa or more (including the fuel cell U216, the dehumidifier U217b (equipped with a dry filter), and the filtering U213) is maintained. In other words, the argon gas extraction unit 21 of this embodiment also constitutes a series of high-pressure gas treatment systems.

[0147] This promotes the filtering process and fuel cell reaction, which are essential for the extraction and recovery of argon gas, and makes it possible to generate a larger amount (for example, at a larger gas flow rate) of argon-enriched gas (high-purity argon gas) with a higher argon concentration. It also makes it possible to increase the final recovery rate of argon gas (from the furnace exhaust gas). However, as already mentioned, it is of course possible to operate the fuel cell 216C under normal conditions (not under high pressure as in this embodiment). In this case, a gas compressor U is provided immediately before the filtering U 213.

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

[0149] As shown in FIG. 7, the kiln exhaust gas regeneration device (system) 3 of this embodiment determines which of the filtering U313 and the fuel cell U316 (and further the filtering U318) to use based on the argon concentration or hydrogen concentration in the kiln exhaust gas discharged from the kiln 91 (fine powder trap U92), based on a preset time schedule, or based on instructions from outside, and uses the determined filtering U313 and / or fuel cell U316 (and further the filtering U318) to regenerate the received kiln exhaust gas into a reusable argon concentration-enhanced gas, which in this embodiment is high-purity argon gas.

[0150] In this embodiment, the kiln exhaust gas regeneration apparatus (system) 3 has a plurality of components: "(name)3**(*)" each of which corresponds to a component: "(name)1**(*)" (where * is a number or an English letter) of the kiln exhaust gas regeneration apparatus (system) 1 (Figure 1), and the components: "(name)3**(*)" can have the same structure and function as the components: "(name)1**(*)" having the same (name) and (**(*)).

[0151] However, in this embodiment, the buffer tank U315a is a unit including 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 have the same structure and function as the blower 112aa and the buffer tank 112ab of the blower U112a (FIG. 1), respectively, and the buffer tank 315ac has the same structure and function as the buffer tank of the buffer tank U115 (FIG. 1). Furthermore, in this embodiment, the buffer tank U315a also includes a flow path switching valve that switches the flow path so that the buffer tank 315ac is 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] In addition, the furnace exhaust gas regeneration device (system) 3 of this embodiment further includes: (a) a flow path switching valve SW1 provided between the catalytic poison removal unit U311 and the blower U312a, capable of transferring gas transferred from the catalytic poison removal unit U311 to a selected one of the blower U312a and a flow path switching valve SW3 described later; (b) a flow path switching valve SW2 provided between the tank U312c and the filtering U313, capable of transferring gas transferred from a selected one of the tank U312c and a flow path switching valve SW4 described later to the filtering U313; (c) a flow path switching valve SW3 that is provided between the hydrogen side outlet 313Fb of the gas filter 313F (provided in the filtering unit U313) and the buffer tank U315a and that is capable of transferring gas transferred from a selected one of the gas filter 313F and the flow path switching valve SW1 described above to the buffer tank U315a; (d) a flow path switching valve SW4 provided between the dehumidifier U317b and the filtering U318, capable of transferring the gas transferred from the dehumidifier U317b to a selected one of the filtering U318 and the flow path switching valve SW2 described above; It has.

[0153] In this embodiment, the overall control U33: (a) Based on the content of the monitor signal (hydrogen concentration or argon concentration) received from the hydrogen concentration meter (or argon concentration meter) ArH provided in the catalyst poison remover U311, (b) based on a pre-established changeover time schedule; or (c) Based on the contents of the instruction received from the outside (designating one of the flow paths 1 to 3 shown below), A control signal relating to the switching control of the flow path switching valves SW1 to SW4 is determined, and this control signal is sent to the flow path switching valves SW1 to SW4 to appropriately realize one of the flow paths (flow path patterns) 1 to 3 shown below.

[0154] <Path 1> Kiln 91 (fine powder trap 92) → catalyst poison removal U311 ~ tank U312c → "filtering U313" → pressure control U314a ~ Ar compression U314c → tank U321 → discharge control U322, and "filtering U313" → buffer tank U315a (buffer tank 315ac) ~ tank U315c → "fuel cell U316" → pressure control U317a → dehumidification U317b → "filtering U318" → pressure control U319a ~ Ar compression U319c → tank U321 → discharge control U322 <Path 2> Kiln 91 (fine powder trap 92) → catalyst poison removal U311 → buffer tank U315a (blower 315aa and buffer tank 315ab) ~ tank U315c → "fuel cell U316" → pressure control U317a → dehumidification U317b → "filtering U313" → pressure control U314a ~ Ar compression U314c → tank U321 → discharge control U322 (in this case, the path switching valve SW3 releases (discards) only gas from the hydrogen side outlet 313Fb) <Path 3> Kiln 91 (fine powder trap 92) → catalyst poison removal U311 ~ tank U312c → "filtering U313" → pressure control U314a ~ Ar compression U314c → tank U321 → discharge control U322 (fuel cell U316 is not used)

[0155] As a modification, it is possible not to provide (omit) the filtering U318 in the above <flow path 1>. In this case, the argon concentration increased gas (high purity argon gas) transferred from the dehumidifier U317b in the rear stage of the fuel cell U316 passes through the flow path switching valve SW4 and is transferred to, for example, a buffer tank U319b via the pressure control U319a.

[0156] Here, the overall control U33 may, for example, (a) If the hydrogen concentration of the received furnace exhaust gas is greater than a predetermined threshold (e.g., 50 vol%), First, in order to sufficiently reduce the hydrogen concentration, the fuel cell reaction process is first carried out through <flow path 2>, and high-purity argon gas (argon concentration-enhanced gas) is generated. (a) When the hydrogen concentration of the received furnace exhaust gas is equal to or lower than a predetermined threshold value (e.g., 50 vol%), a filtering process is first performed in order to generate argon gas having a smaller absolute value of hydrogen concentration, i.e., a higher (absolute) purity of argon, by implementing a <flow path 1>, high purity argon gas (argon concentration increased gas) is generated. It is also preferable to perform the following control.

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

[0158] On the other hand, the kiln exhaust gas in (a) above corresponds to that discharged in the latter half of the alloy powder manufacturing process in the kiln 91 (for example, the period from several tens of minutes after the start of the process to the end of the process). In this latter half, the flow rate of the introduced argon gas increases significantly (for example, to several to several dozen times higher than in the first half), and the release of the absorbed hydrogen approaches completion, so that this kiln exhaust gas has a low hydrogen concentration (for example, 30 vol% or less).

[0159] Therefore, it is also preferable that the overall control U33 selects the above-mentioned (A) <path 2> when the kiln exhaust gas is first received from the kiln 91 (fine powder trap U92), and then selects the above-mentioned (B) <path 1> when the hydrogen concentration of the kiln exhaust gas becomes equal to or lower than a predetermined threshold value (e.g., 50 vol%), or when a predetermined time (e.g., several tens of minutes) has elapsed since the selection of <path 2>. By performing such control, it becomes possible to consistently and stably generate high-purity argon gas (argon-enhanced gas) with a target (or required) high argon concentration, even though the hydrogen concentration (argon concentration) of the kiln exhaust gas discharged from the kiln 91 changes significantly.

[0160] In accordance with the above-mentioned control, it is also preferable that both the buffer tank 312ab and the 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 that when the furnace exhaust gas discharged in the first half (second half) is received, 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 capacity, for example, several times to several tens of times, than the first half tank in order to handle the larger furnace exhaust gas flow rate in the second half.

[0161] By using such buffer tank 312ab or buffer tank 315ab, it is possible to more efficiently generate high purity argon gas (gas with increased argon concentration) by appropriately dealing with an increase in the flow rate of the furnace exhaust gas in the latter half of the alloy powder manufacturing process in kiln 91. It is also possible to stabilize the gas pressure in kiln 91, contributing to efficient or low-cost alloy powder manufacturing process. Naturally, buffer tank 112ab (FIG. 1) or buffer tank 215ab (FIG. 6) may also be provided with a first half tank and a second half tank as described above, and these tanks may be configured to be switched and used as described above.

[0162] As another embodiment of the flow path (flow path pattern) selection, the overall control U33 may determine the argon concentration, gas flow rate, and recovery rate (dependence of the hydrogen concentration in the kiln exhaust gas) of the argon concentration-enhanced gas generated for each flow path (flow path pattern) through prior experiments in which the hydrogen concentration of the kiln exhaust gas is changed, and use these determinations to select and implement a flow path (flow path pattern) based on the hydrogen concentration of the received kiln exhaust gas (and the required specifications of the argon concentration-enhanced gas).

[0163] Furthermore, the overall control U33 may be set to receive an external instruction specifying <flow path 3> and realize <flow path 3> to generate high purity argon gas (argon concentration increased gas) when the target (required) argon concentration (purity), gas flow rate, recovery rate, etc. can be achieved by using only the filtering U313. In such a case, the overall control U33 may be set to select <flow path 3> instead of <flow path 1> in (A) of the above embodiment. Furthermore, the overall control U33 may be set to receive an external instruction specifying a specific flow path for reasons such as maintenance, testing, unit failure, etc., and realize this specific flow path (flow path pattern) to generate high purity argon gas (argon concentration increased gas).

[0164] When a flow path (flow path pattern) including the fuel cell U316 is selected, it is also preferable that the exhaust gas (argon concentration increased gas) discharged from the fuel gas chamber side outlet of the fuel cell 316C and dehumidified in the dehumidifier U317b is returned to the buffer tank U315a (just before the buffer tank) and processed again in the fuel cell U316. This makes it possible to further reduce the amount of hydrogen gas in the exhaust gas and to increase the final recovery rate of argon gas.

[0165] Specifically, flow path switching valves may be provided immediately after the dehumidifier U317b and immediately before the buffer tank U315a, and the flow path switching valves may be appropriately switched and the gas transfer from the buffer tank U315a may be appropriately controlled to return the exhaust gas to the buffer tank U315a (immediately before the buffer tank) a predetermined number of times (predetermined period). Naturally, the same process as above may also be performed on the exhaust gas from the fuel gas chamber side outlet of the fuel cell U116 (FIG. 1) or the fuel cell U216 (FIG. 6) to further reduce the hydrogen gas content in the exhaust gas.

[0166] Furthermore, if the targeted (or required) high argon concentration or high recovery rate can be achieved by returning the exhaust gas to the fuel cell U316 as described above, it will be possible to realize a flow path pattern <flow path 4> in which the "filtering U313 (and pressure control U314a)" is omitted from the above flow path 2, and to use this <flow path 4> to generate high-purity argon gas (argon concentration increased gas).

[0167] As described above in detail, according to the present invention, a mixed gas (furnace exhaust gas) containing a noble gas and an occluded gas discharged from a furnace can be regenerated into a reusable gas. Furthermore, a furnace system for reusing the regenerated gas can be provided. The generated noble gas (argon) concentration-enriched gas can be used in various fields other than furnaces.

[0168] In addition, in the case of an embodiment using a fuel cell, the demand for fuel cells, as well as neodymium (Nd-Fe-B) magnets manufactured using a kiln, is expected to further increase as the social demand for reducing carbon dioxide emissions increases. In other words, fuel cells and rare earth magnets manufactured using a kiln are well suited to the coming carbon-neutral society. Therefore, the embodiment of the present invention in which a fuel cell is used to treat kiln exhaust gas is well suited to meet the above-mentioned social demands, which will continue to increase in the future.

[0169] It should be noted that all of the above-described embodiments are illustrative of the present invention and are not limiting, and the present invention can be embodied in various other modified and altered forms. Therefore, the scope of the present invention is defined only by the claims and their equivalents. [Explanation of symbols]

[0170] 1. Kiln exhaust gas regeneration device (kiln exhaust gas regeneration system) 111, 211, 311 Catalytic Poison Removal Unit (U) 112a, 312a Blower U 112aa, 215aa, 312aa, 315aa blower 112ab, 215ab, 312ab, 315ab, 315ac Buffer tank 112b, 312b Gas Compression U 112c, 312c Tank U 113, 118, 213, 313, 318 Filtering U 113F, 113F1, 113F2, 113F3, 113F4, 118F, 213F, 313F, 318F Gas Filters 114a, 214a, 314a Pressure Control U 114b, 214b, 314b Buffer Tank U Compression U for 114c, 214c, 314c Ar 115a, 215a, 315a Buffer Tank U 115b, 215b, 315b Gas Compression U 115c, 215c, 315c Tank U 115d, 215d, 315d Gas Compression U 116, 216, 316 Fuel cell U 116C, 216C, 316C fuel cell 117a, 217a, 317a Pressure Control U 117b, 217b, 317b Dehumidification U 117c, 217c, 317c Pressure control U 119a, 319a Pressure Control U 119b, 319b Buffer Tank U Compressed U for 119c, 319c Ar 121, 221, 321 Tank U 122, 222, 322 Sending control U 13, 23, 33 Overall Control U 91 Kiln 92 Fine Powder Trap U 93 Alloy powder collection container

Claims

1. A kiln exhaust gas regeneration device characterized by having a noble gas extraction means that receives a mixed gas containing the noble gas and the occluded gas discharged from a kiln in which a metal that has occluded the occluded gas is heated and the occluded gas is released from the metal in an atmosphere containing the noble gas, and converts the mixed gas into a gas with an increased concentration of the noble gas using filters that have different degrees of permeability for the occluded gas and the noble gas and / or a fuel cell that oxidizes the occluded gas.

2. 2. The furnace exhaust gas regeneration apparatus according to claim 1, wherein the noble gas is argon gas.

3. 2. The kiln exhaust gas regeneration apparatus according to claim 1, further comprising a noble gas delivery means for delivering 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 as the atmosphere.

4. 2. The furnace exhaust gas regeneration apparatus according to claim 1, wherein the noble gas extraction means converts the mixed gas into a gas having an increased concentration of the noble gas by using the filter and the fuel cell provided downstream of the filtered gas outlet of the filter.

5. The furnace exhaust gas regeneration apparatus according to claim 4, characterized in that the noble gas extraction means uses a gas compressor to apply the mixed gas to the filter at a high pressure exceeding atmospheric pressure, and further introduces gas extracted from an outlet of the filtered gas in the filter at a high pressure exceeding atmospheric pressure into a fuel gas chamber of the fuel cell to oxidize the occluded gas.

6. The furnace exhaust gas regeneration device according to claim 4, characterized in that the noble gas extraction means further uses another filter having a different degree of permeability for the occluded gas and the noble gas, which is provided downstream of the fuel gas chamber of the fuel cell, to convert the mixed gas into a gas with an increased concentration of the noble gas.

7. 2. The furnace exhaust gas regeneration apparatus according to claim 1, wherein the noble gas extraction means converts the mixed gas into a gas having an increased concentration of the noble gas by using the fuel cell and the filter provided downstream of the fuel gas chamber of the fuel cell.

8. The kiln exhaust gas regeneration apparatus according to claim 7, characterized in that the noble gas extraction means uses a gas compressor to introduce the mixed gas at a high pressure exceeding atmospheric pressure into the fuel gas chamber of the fuel cell to oxidize the occluded gas, and furthermore causes gas extracted from the combustion gas chamber of the fuel cell to act on the filter at a high pressure exceeding atmospheric pressure.

9. The noble gas extraction means is provided with the filter, and the mixed gas is applied to the filter at a gas flow rate set to reduce the residual occluded gas concentration or at a gas flow rate within a range of gas flow rates set to reduce the residual occluded gas concentration, and gas with an increased noble gas concentration is extracted from the filter.

10. The noble gas extraction means is provided with the filter, and the mixed gas is applied to the filter at a gas pressure set at a value at which the recovery rate of the noble gas is high, or at a gas pressure within a range of gas pressure values ​​set at which the recovery rate of the noble gas is high, and gas with an increased concentration of the noble gas is extracted from the filter.

11. The noble gas extraction means is provided with the filter, and the mixed gas is applied to the filter at a gas pressure and / or gas flow rate determined according to the concentration of the noble gas or the occluded gas in the received mixed gas, and gas with an increased concentration of the noble gas is extracted from the filter.

12. a control means for determining which of the filter and the fuel cell to use based on a concentration of the noble gas or the occluded gas in the received mixed gas, based on a preset time schedule, or based on an external instruction; The kiln exhaust gas regeneration device according to claim 1, wherein the noble gas extraction means is equipped with the filter and the fuel cell, and the mixed gas is converted into a gas having an increased concentration of the noble gas by using the determined filter and / or fuel cell.

13. the control means selects a flow path pattern to be used from a flow path pattern set 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, based on a concentration of the noble gas or the occluded gas in the received mixed gas, based on a preset time schedule, or based on an external instruction; The noble gas extraction means comprises the filter, the fuel cell, and a flow path switching valve that realizes each flow path pattern included in the flow path pattern set, and realizes the selected flow path pattern to be used to convert the mixed gas into a gas with an increased concentration of the noble gas.

14. The furnace exhaust gas regeneration device according to claim 13, characterized in that the control means first selects a flow path pattern connecting the fuel cell and the filter in the downstream stage, and then selects a flow path pattern connecting the filter and the fuel cell in the downstream stage.

15. 15. The kiln exhaust gas regeneration device according to claim 1, 2, 3, 4, 5, 6, 7, 8, 11, 12, 13 or 14, characterized in that the mixed gas discharged from the kiln and received by the noble gas extraction means is a mixed gas in which the concentration of the occluded gas is initially higher than the concentration of the noble gas, and thereafter the concentration of the noble gas becomes higher than the concentration of the occluded gas.

16. The kiln exhaust gas regeneration apparatus according to claim 1, 2, 3, 4, 5, 6, 7, 8, 11, 12, 13 or 14, characterized in that the noble gas extraction means is provided with the filter, the mixed gas is made to act on the filter, and gas with an increased concentration of the occluded gas is extracted from an outlet of the filtered gas in the filter.

17. The kiln exhaust gas regeneration device according to claim 1, 2, 3, 4, 5, 6, 7, 8, 11, 12, 13 or 14, characterized in that the noble gas extraction means is a plurality of filters connected in series, with the inlet of the second or subsequent filter being connected to the outlet of the filtered gas of the previous filter, to convert the mixed gas into a gas with an increased concentration of the noble gas.

18. The furnace exhaust gas regeneration apparatus according to claim 5 or 8, characterized in that the noble gas extraction means further comprises a buffer tank for temporarily storing the mixed gas, and a blower for sending the mixed gas to the buffer tank, located upstream of the gas compressor.

19. A kiln exhaust gas regeneration system comprising: a kiln which heats a metal that has absorbed an absorbed gas, and causes the absorbed gas to be released from the metal in an atmosphere containing a noble gas; a mixed gas containing the noble gas and the absorbed gas is received from the kiln; and the mixed gas is converted into a gas having an increased concentration of the noble gas by using filters having different degrees of permeability for the absorbed gas and the noble gas, and / or a fuel cell which oxidizes the absorbed gas.

20. a furnace for heating a metal having an occluded gas and releasing the occluded gas from the metal in an atmosphere containing a noble gas; a noble gas extraction means for receiving a mixed gas containing the noble gas and the occluded gas discharged from the furnace, and converting the mixed gas into a gas having an increased concentration of the noble gas by using a filter having different permeability for the occluded gas and the noble gas and / or a fuel cell for oxidizing the occluded gas; a noble gas delivery means for delivering the gas having an increased noble gas concentration to the furnace or a gas reservoir for the furnace so as to be reused as the atmosphere; A furnace system comprising:

21. receiving a mixed gas containing the noble gas and the occluded gas discharged from a furnace in which a metal having an occluded gas is heated and the occluded gas is released from the metal in an atmosphere containing the noble gas; converting the mixed gas into a gas having an increased concentration of the noble gas by using a filter having different permeability for the stored gas and the noble gas and / or a fuel cell for oxidizing the stored gas; A method for regenerating furnace exhaust gas, comprising:

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