Gas separation and recovery method

Abstract

To provide a gas separation recovery apparatus that can detect the end of gas separation when separating a target component from a mixed gas that contains a component to be a recovery target.SOLUTION: A gas separation recovery apparatus 1 includes: a gas supply path L1 for supplying a mixed gas that contains a component to be a recovery target; a gas separation part 2 including a space communicated to the gas supply path L1 inside thereof; a gas discharge path L2 communicated to the space and discharging a gas from the space; and one or more first pressure detection means 8 for detecting pressure of the space.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a gas separation and recovery apparatus and a gas separation and recovery method. [Background technology]

[0002] The semiconductor manufacturing process includes various steps such as film formation and etching. In the equipment that performs these steps (hereinafter simply referred to as "processing equipment"), most of the gases supplied are discharged unreacted via pumps. In particular, in the film formation process, only about 1% of the gases supplied to the processing equipment are consumed in forming the thin film, and the remaining 99% or more are discharged as exhaust gas.

[0003] In recent years, with the advancement of miniaturization and three-dimensionalization of semiconductors, the number of processes that use large amounts of valuable gases is increasing, and from the economic and social perspective of sustainability, there is a widespread demand for the recovery of useful gas components. In particular, the demand for tungsten hexafluoride (WF6), which is used to form tungsten thin films, has increased significantly in recent years, but this trend is particularly noticeable due to its lower utilization efficiency.

[0004] In the semiconductor manufacturing process, multiple types of gases including raw material gas are mixed immediately before the processing equipment and then used in the processing equipment, where a specific thin film is formed by a chemical reaction and at the same time, reaction by-products are generated. In addition, nitrogen gas, called ballast, may be used in a pump that exhausts gas containing by-products from the processing equipment. Therefore, in the semiconductor manufacturing process, the gas exhausted from the processing equipment through the pump (hereinafter simply referred to as "exhaust gas") contains at least three or more components, such as unreacted raw material gas, reaction by-product gas, and nitrogen gas.

[0005] In order to reuse useful gas components contained in such exhaust gas, it is necessary to separate (isolate) the target component from a mixed gas containing three or more components. For example, if the target component is a rare gas such as xenon or helium, it is easy to separate because it is highly volatile and inert. Patent Document 1 discloses a technique for separating rare gases using adsorption technology.

[0006] On the other hand, even for gases whose target component is highly reactive, such as tungsten hexafluoride, a method of recovering and reusing unreacted gas from exhaust gas is being considered. Patent Document 2 discloses a technology in a semiconductor manufacturing process in which unreacted tungsten hexafluoride is condensed in a storage tank on the secondary side of a processing device, separated, and reused. Patent Document 2 also discloses a technology in which a weight sensor or a liquid level sensor is used to switch between multiple storage tanks when recovering tungsten hexafluoride. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 4652860 [Patent Document 2] JP 2014-159630 A Summary of the Invention [Problem to be solved by the invention]

[0008] However, in the technology disclosed in Patent Document 2, when tungsten hexafluoride is hardly condensed and the recovery efficiency is low, the weight sensor and the liquid level sensor cannot detect the end point of gas separation, and it is difficult to determine the timing of switching the storage tank. Furthermore, even if recovery is possible, the weight cannot be measured correctly due to the expansion and contraction of the piping caused by temperature changes and the condensation of water on the outer wall of the cooling section. In addition, when the target to be recovered is a corrosive component, the liquid level sensor cannot be used in the first place.

[0009] The present invention has been made in consideration of the above problems, and an object of the present invention is to provide a gas separation and recovery device and a gas separation and recovery method that are capable of detecting the end point of gas separation when separating a target component from a mixed gas containing the component to be recovered. [Means for solving the problem]

[0010] In order to achieve the above object, the present invention employs the following configuration. [1] A gas supply path for supplying a mixed gas containing the component to be recovered; a gas separation unit having an internal space communicating with the gas supply path and separating the components from the mixed gas in the internal space; a gas exhaust path communicating with the space and exhausting gas from the space; A gas separation and recovery apparatus comprising: one or more first pressure detection means for detecting the pressure in the space. [2] The gas separation and recovery apparatus according to the preceding paragraph [1], wherein the first pressure detection means is located in either or both of the gas supply path and the gas exhaust path. [3] The gas separation and recovery apparatus according to the preceding item [1] or [2], further comprising one or more first temperature detection means for detecting the temperature of the space. [4] A gas supply path for supplying a mixed gas containing the components to be recovered; a gas separation unit having an internal space communicating with the gas supply path and separating the components from the mixed gas in the internal space; a gas exhaust path communicating with the space and exhausting gas from the space; A gas separation and recovery apparatus comprising: one or more first temperature detection means for detecting the temperature of the space. [5] The gas separation and recovery apparatus according to the preceding item [3] or [4], wherein the first temperature detection means is located in either or both of the gas supply path and the gas exhaust path. [6] A storage section for storing the component transferred from the space; a transfer path located between the gas separation unit and the storage unit; The gas separation and recovery apparatus according to any one of items [1] to [5] above, further comprising a supply path for supplying the components from the storage section. [7] One or more second pressure detection means for detecting a pressure in the storage portion; The gas separation and recovery apparatus according to item [6] above, wherein the second pressure detection means is located in either one or both of the transfer path and the supply path. [8] One or more second temperature detection means for detecting a temperature in the storage portion; The gas separation and recovery apparatus according to item [6] or [7] above, wherein the second temperature detection means is located in either one or both of the transfer path and the supply path. [9] Located on the secondary side of a gas utilization facility that discharges the mixed gas as exhaust gas; One or more of the gas separation sections; One or more of the storage sections; The gas separation and recovery apparatus according to any one of items [6] to [8], wherein the components are returned from the storage section to the gas utilization facility.

[10] A method for separating a target component from a mixed gas discharged as exhaust gas from a gas utilization facility, comprising: A gas separation and recovery method, comprising: stopping separation of the component in a first space in which the component is separated from the mixed gas when at least one of a pressure and a temperature of the first space reaches a required threshold value.

[11] The gas separation and recovery method described in the preceding paragraph

[10] , wherein when discharging the components from the first space, the discharge of the components from the first space is stopped when at least one of the pressure and temperature of the first space reaches a required threshold value.

[12] A gas separation and recovery method as described in the preceding paragraph

[10] or

[11] , wherein when the component is transferred from the first space to the second space storing the component, the transfer of the component is stopped when at least one of the pressure and temperature of the second space reaches a required threshold value.

[13] The gas separation and recovery method described in the preceding paragraph

[12] , wherein when discharging the components from the second space, the discharge of the components from the second space is stopped when at least one of the pressure and temperature of the second space reaches a required threshold value. Effect of the Invention

[0011] The gas separation and recovery apparatus and the gas separation and recovery method of the present invention are capable of detecting the end point of gas separation when separating a target component from a mixed gas containing the component to be recovered. [Brief description of the drawings]

[0012] [Figure 1] 1 is a system diagram showing a gas separation and recovery apparatus according to an embodiment of the present invention. [Diagram 2] 1 is a system diagram showing a main part of a gas separation and recovery apparatus according to an embodiment of the present invention. [Diagram 3] FIG. 2 is a system diagram showing the state of the gas separation and recovery apparatus during operation in which separation, recovery, and resupply are continuously performed in the gas separation and recovery method of the present embodiment. [Figure 4] FIG. 2 is a system diagram showing the state of the gas separation and recovery apparatus during operation in which separation, recovery, and resupply are continuously performed in the gas separation and recovery method of the present embodiment. [Diagram 5] FIG. 2 is a system diagram showing the state of the gas separation and recovery apparatus during operation in which separation, recovery, and resupply are continuously performed in the gas separation and recovery method of the present embodiment. [Figure 6] FIG. 4 is a system diagram showing another embodiment of the gas separation section constituting the gas separation and recovery apparatus of the present invention. [Figure 7] FIG. 4 is a system diagram showing another embodiment of the gas separation section constituting the gas separation and recovery apparatus of the present invention. [Figure 8] 2 is a graph for explaining an embodiment of a gas separation and recovery apparatus of the present invention. [Figure 9] 2 is a graph for explaining an embodiment of a gas separation and recovery apparatus of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings showing embodiments. In addition, the drawings used in the following description may show characteristic parts in an enlarged scale for convenience in order to make the features easier to understand, and the dimensional ratios of each component may not necessarily be the same as the actual ones.

[0014] <Gas separation and recovery equipment> First, the configuration of a gas separation and recovery apparatus according to one embodiment of the present invention will be described. Fig. 1 is a system diagram showing a gas separation and recovery apparatus according to an embodiment of the present invention. Fig. 2 is a system diagram showing a main part of the gas separation and recovery apparatus according to an embodiment of the present invention. 1, the gas separation and recovery apparatus 1 of this embodiment is located in an exhaust gas path L100 between a gas utilization facility 200 that discharges a mixed gas containing components to be recovered as exhaust gas, and a detoxification device 300. That is, the gas separation and recovery apparatus 1 is located on the secondary side (rear stage) of the gas utilization facility 200 in the exhaust gas path L100. The gas separation and recovery device 1 separates (isolates) unused (unreacted) components from the exhaust gas of the gas utilization facility 200 and supplies them to the gas utilization facility 200 , and sends unnecessary components to the detoxification device 300 .

[0015] The gas utilization facility 200 is not particularly limited as long as it discharges a mixed gas containing the components to be recovered as exhaust gas, and examples of such facilities include devices (processing devices) that perform film formation and etching processes in the semiconductor manufacturing process. Examples of processing devices include "CONCEPT3" manufactured by Novellus, "ALTUS" manufactured by Lam Research, and "Centura" manufactured by Applied Materials.

[0016] The detoxification device 300 is not particularly limited as long as it renders harmful components contained in exhaust gas harmless. Examples of the detoxification device include those described in JP-A-2004-33132, JP-A-2005-334755, Japanese Patent No. 4212746, etc.

[0017] As shown in Figure 2, the gas separation and recovery apparatus 1 of this embodiment is generally configured to include a gas separation section 2, a cooling mechanism 3, a heating mechanism 4, a storage section 5, a pressure reduction device 6, paths L1 to L4 connected to the gas separation section 2, and paths L5 and L6 connected to the storage section 5.

[0018] 1 and 2, the gas supply line L1 is a gas pipe located between the gas utilization facility 200 and the gas separation and recovery device 1, and constitutes a part of the exhaust gas line L100. That is, the gas supply line L1 supplies a mixed gas containing components to be recovered to the gas separation unit 2. In this embodiment, a case will be described in which a mixed gas containing three or more components having different boiling points is used, and one of the three or more components is to be recovered.

[0019] The gas supply path L1 branches into branch paths L1A and L1B. Each of the branch paths L1A and L1B is provided with an on-off valve, and the flow path can be switched by selecting an open state or a closed state of the on-off valve.

[0020] In the branch paths L1A and L1B, a pressure gauge (first pressure detection means) 8 (8A, 8B) and a thermometer (first temperature detection means) 9 (9A, 9B) are provided on the secondary side of the on-off valve, respectively.

[0021] Pressure gauges 8 (8A, 8B) detect the pressure in the inner space (first space) of gas separation section 2 (2A, 2B).

[0022] Thermometer 9 (9A, 9B) detects the temperature of the inner space (first space) of gas separation section 2 (2A, 2B).

[0023] The gas separation unit 2 (2A, 2B) is a part that has the function of separating components to be recovered from the mixed gas. In addition, the gas separation unit 2 (2A, 2B) has one or more spaces (first spaces) inside. The inner space of the gas separation unit 2 communicates with the gas supply path L1. Specifically, the gas separation unit 2A is connected to the branch path L1A, and the gas separation unit 2B is connected to the branch path L1B.

[0024] The space inside the gas separation section 2 (2A, 2B) is used to condense components other than low-boiling point components (those with boiling points below 0°C at atmospheric pressure) contained in the mixed gas. Therefore, it is preferable that the space has a diameter larger than at least the gas supply path L1 (L1A, L1B) and an appropriate capacity.

[0025] The space inside the gas separation unit 2 (2A, 2B) is used to separate (isolate) the condensed components by distillation (rectification). Therefore, the space inside the gas separation unit 2 is preferably shaped to have an appropriate length in the vertical direction so that the gas phase is located toward the top and the liquid phase is located toward the bottom, and the gas separation unit 2 is preferably arranged so that the long side of the space is in the vertical direction.

[0026] Furthermore, it is preferable that a mechanism for enhancing gas-liquid contact during distillation (rectification) is provided in the space inside the gas separation section 2 (2A, 2B). Examples of such a mechanism include unevenness provided on the surface of the inner wall of the gas separation section 2 (2A, 2B) and a filler placed in the space.

[0027] A commercially available heat exchanger can be applied to the gas separation section 2 (2A, 2B). Examples of the heat exchanger include a plate type heat exchanger, a shell-and-tube type heat exchanger, and a jacket type heat exchanger.

[0028] The gas discharge path L2 is a gas piping located between the gas separation and recovery apparatus 1 and the detoxification apparatus 300, and constitutes a part of the exhaust gas path L100. That is, the gas discharge path L2 sends unnecessary components (exhaust gas) discharged from the gas separation and recovery apparatus 1 to the detoxification apparatus 300.

[0029] The gas exhaust path L2 communicates with the space of the gas separation unit 2 (2A, 2B). The gas exhaust path L2 branches into branch paths L2A and L2B. Specifically, the gas separation unit 2A is connected to the branch path L2A, and the gas separation unit 2B is connected to the branch path L2B. An on-off valve is provided in each of the branch paths L2A and L2B, and the flow path can be switched by selecting an open state or a closed state of the on-off valve.

[0030] The cooling mechanism 3 cools the space inside the gas separation unit 2 (2A, 2B). Specifically, when mixed gas is supplied from the gas supply path L1 to the space inside the gas separation unit 2 (2A, 2B), the mixed gas in the space is cooled by the cooling mechanism 3. In addition, the cooling mechanism 3 cools the space inside the storage unit 5 (5A, 5B). Specifically, when a component isolated from the mixed gas is supplied to the space inside the storage unit 5 (5A, 5B), the component in the space is cooled by the cooling mechanism 3.

[0031] The cooling mechanism 3 includes a cooling source 30, coolant supply paths L31 to L34, a cooling unit (not shown), and a coolant discharge path (not shown).

[0032] The cooling source 30 is a supply source of a refrigerant. The refrigerant is not particularly limited as long as it can cool the components contained in the mixed gas to a temperature at which the components other than the low boiling point components are condensed (i.e., a fluid that does not solidify at atmospheric pressure and -120°C). Examples of such refrigerants include nitrogen controlled to a temperature between -120°C and 20°C, and "Thermal C2" manufactured by Julabo.

[0033] The refrigerant supply paths L31-L34 are pipes for supplying the refrigerant from the cooling source 30 to the cooling parts, and are connected to the cooling parts located in the gas separation parts 2A, 2B and the storage parts 5A, 5B, respectively. Also, the refrigerant supply paths L31-L34 are each provided with an on-off valve, and are configured so that the flow path can be switched by selecting an open state or a closed state of the on-off valve.

[0034] The cooling sections (not shown) are located near the gas separation sections 2 (2A, 2B) and the storage sections 5 (5A, 5B), respectively, and cool the inner spaces of the gas separation sections 2 (2A, 2B) and the storage sections 5 (5A, 5B), respectively. The cooling section may be located outside (around) the gas separation section 2 and the storage section 5, or may be located within the space inside the gas separation section 2 and the storage section 5, as long as it is capable of cooling the space inside the gas separation section 2 (2A, 2B) and the storage section 5 (5A, 5B).

[0035] The refrigerant discharge path (not shown) is a pipe that discharges the used refrigerant (after heat exchange) from the cooling unit. The used refrigerant may be collected and reused.

[0036] The heating mechanism 4 heats the space inside the gas separation unit 2 (2A, 2B). Specifically, when components other than the low boiling point components are condensed in the space inside the gas separation unit 2 (2A, 2B), the condensed components in the space are heated by the heating mechanism 4. In addition, the heating mechanism 4 heats the space inside the storage unit 5 (5A, 5B). Specifically, when a component isolated from the mixed gas is supplied to the space inside the storage unit 5 (5A, 5B), the component in the space is heated by the heating mechanism 4.

[0037] The heating mechanism 4 includes a heat source 40, heat medium supply paths L41 to L44, a heating section (not shown), and a heat medium discharge path (not shown).

[0038] The heating source 40 is a supply source of a heat medium. The heat medium is not particularly limited as long as it can heat the solidified components in the space of the gas separation section 2 to a temperature at which the components separate into gas and liquid. Examples of such heat medium include gases such as nitrogen controlled at a temperature between 25°C and 200°C, and liquids such as water, ethylene glycol, and "Thermal HL90" manufactured by Julabo.

[0039] The heat medium supply paths L41 to L44 are pipes for supplying the heat medium from the heat source 40 to the heating parts, and are connected to the heating parts located in the gas separation parts 2A and 2B and the storage parts 5A and 5B, respectively. Each of the heat medium supply paths L41 to L44 is provided with an on-off valve, and is configured so that the flow path can be switched by selecting an open state or a closed state of the on-off valve.

[0040] The heating units (not shown) are located near the gas separation units 2 (2A, 2B) and the storage units 5 (5A, 5B), respectively, and heat the inner spaces of the gas separation units 2 (2A, 2B) and the storage units 5 (5A, 5B), respectively. The heating section may be located outside (around) the gas separation section 2 and the storage section 5, or within the space inside the gas separation section 2 and the storage section 5, as long as it is capable of heating the space inside the gas separation section 2 (2A, 2B) and the storage section 5 (5A, 5B).

[0041] Incidentally, when the components solidified in the space inside the gas separation section 2 (2A, 2B) are liquefied, they gather in the lower part of the gas separation section 2 due to gravity. Therefore, it is preferable that the heating section is located toward the lower part of the gas separation section 2 (2A, 2B). This makes it possible to heat and vaporize the liquid phase part in the gas separation section 2. The vaporized components are reliquefied in the upper part of the gas separation section 2, so that gas-liquid contact is promoted in the gas separation section 2, and an effect similar to that of rectification is obtained. If the gas separation section 2 has a mechanism for promoting gas-liquid contact, gas-liquid contact in the gas separation section 2 is further promoted.

[0042] The heat medium discharge path (not shown) is a pipe that discharges the used (after heat exchange) heat medium from the heating section. The used heat medium may be recovered and reused.

[0043] The heating mechanism 4 may be configured to include an additional heater near the gas separation section 2 (2A, 2B) in order to effectively separate the condensed components by distillation (rectification) in the space within the gas separation section 2 (2A, 2B).

[0044] The additional heater is preferably disposed near the lower side of the gas separation section 2 (2A, 2B). This makes it possible to heat the liquid phase portion in the gas separation section 2 and promote separation of the condensed components by distillation (rectification). The additional heater is not particularly limited, but examples thereof include an electric heater, an IH (electromagnetic induction heating), a lamp heater (radiation heating), and the like.

[0045] The gas separation and recovery apparatus 1 of the present embodiment may be configured to share some or all of the components of the cooling mechanism 3 and the heating mechanism 4, excluding the cooling source 30 and the heating source 40. This allows the entire apparatus to be made smaller.

[0046] Transfer path L3 is a pipe for transferring the components isolated in the space within gas separation section 2A to storage section 5 (5A, 5B). Moreover, the transfer path L4 is a pipe for transferring the components isolated in the space within the gas separation section 2B to the storage section 5 (5A, 5B).

[0047] The base end of the transfer path L3 is connected to the gas separation unit 2A. The tip of the transfer path L3 branches into branch paths L3A and L3B, with the branch path L3A being connected to the storage unit 5A and the branch path L3B being connected to the storage unit 5B. The branch paths L3A and L3B are each provided with an on-off valve, and are configured so that the flow path can be switched by selecting an open state or a closed state of the on-off valve.

[0048] The base end of the transfer path L4 is connected to the gas separation unit 2B. The tip of the transfer path L4 branches into branch paths L4A and L4B, with the branch path L4A being connected to the storage unit 5A and the branch path L4B being connected to the storage unit 5B. The branch paths L4A and L4B are each provided with an on-off valve, and are configured so that the flow path can be switched by selecting an open state or a closed state of the on-off valve.

[0049] In this embodiment, the base ends of the transfer paths L3 and L4 are directly connected to the gas separation unit 2 (2A, 2B) as an example, but the present invention is not limited thereto. The transfer paths L3 and L4 only need to have their respective ends connected to the storage unit 5 (5A, 5B), and the base ends may be connected to a gas path connected to the gas separation unit 2 (2A, 2B). That is, the transfer paths L3 and L4 may branch off from the gas supply path L1 or the gas exhaust path L2. Even in this case, the transfer paths L3 and L4 can transfer the components isolated in the space in the gas separation unit 2 (2A, 2B) to the storage unit 5 (5A, 5B) via the gas supply path L1 or the gas exhaust path L2.

[0050] The storage section 5 (5A, 5B) stores any one of the components contained in the mixed gas isolated in the space within the gas separation section 2 (2A, 2B). The inner spaces of the storage sections 5A, 5B are connected to the spaces within the gas separation sections 2A, 2B via the transfer paths L3, L4, respectively.

[0051] The exhaust path L5 is a pipe for discharging the gas phase sucked from the space within the gas separation unit 2 (2A, 2B) via the gas exhaust path L2 before the components isolated in the space within the gas separation unit 2 (2A, 2B) are transferred to the storage unit 5 (5A, 5B).

[0052] The base end of the exhaust path L5 branches into branch paths L5A and L5B, with the branch path L5A being connected to the storage section 5A and the branch path L5B being connected to the storage section 5B. The tip of the exhaust path L5 is connected to the gas exhaust path L2. The branch paths L5A and L5B are each provided with an on-off valve, and are configured so that the flow path can be switched by selecting an open state or a closed state of the on-off valve.

[0053] The pressure reducing device 6 is located in the exhaust path L5. By operating the pressure reducing device 6, the gas phase can be sucked from the space in the gas separation unit 2 (2A, 2B) via the exhaust path L5 (L5A, L5B), the storage unit 5 (5A, 5B), and the transfer paths L3, L4, and discharged to the gas discharge path L2. The pressure reducing device 6 is not particularly limited, and a vacuum pump, a Venturi tube, or the like can be used.

[0054] The return path (supply path) L6 is a pipe for supplying (returning) the components stored in the storage section 5 (5A, 5B) to the gas utilization facility 200. The base end of the return path L6 branches into branch paths L6A and L6B, with the branch path L6A being connected to the storage unit 5A and the branch path L6B being connected to the storage unit 5B. The tip of the return path L6 is connected to the gas utilization facility 200. The branch paths L6A and L6B are each provided with an on-off valve, and are configured so that the flow path can be switched by selecting an open state or a closed state of the on-off valve.

[0055] In the branch paths L6A and L6B, a pressure gauge (second pressure detection means) 10 (10A, 10B) and a thermometer (second temperature detection means) 11 (11A, 11B) are provided on the primary side of the on-off valve, respectively.

[0056] Pressure gauge 10 (10A, 10B) detects the pressure in the inner space (second space) of storage portion 5 (5A, 5B).

[0057] Thermometer 11 (11A, 11B) detects the temperature of the inner space (second space) of storage section 5 (5A, 5B).

[0058] The gas separation and recovery apparatus 1 of this embodiment is equipped with two gas separation sections 2A, 2B, two storage sections 5A, 5B, branched gas paths L1 to L6, pressure gauges 8A, 8B, 10A, 10B, and thermometers 9A, 9B, 11A, 11B, and is configured to enable continuous operation by detecting the end points of gas separation and gas supply and switching between the gas separation sections 2A, 2B and the storage sections 5A, 5B at appropriate times.

[0059] <Gas separation and recovery method> Next, the gas separation and recovery method of the present invention will be described with reference to the drawings. The gas separation and recovery method of the present invention is a method for separating (isolating) a target component from a mixed gas containing a component to be recovered, which is discharged as an exhaust gas from a gas utilization facility 200 as shown in FIG. Moreover, in the gas separation and recovery method of the present invention, any one of the components contained in the mixed gas is recovered and stored in the storage section 5 (5A, 5B). Furthermore, the gas separation and recovery method of the present invention supplies the recovered components to a gas utilization facility 300 .

[0060] The mixed gas contains components to be recovered. In this embodiment, a mixed gas containing three or more components having different boiling points is used, and one of the three or more components is to be recovered. The mixed gas preferably contains one or more low boiling point components and two or more components other than the low boiling point components (condensed components), and more preferably contains one low boiling point component and two condensed components with different boiling points, for a total of three components.

[0061] The low boiling point component may have a boiling point of less than 0°C at atmospheric pressure, preferably less than -40°C, and more preferably less than -120°C. Such low boiling point components include components that are generally used as carrier gases, specifically, nitrogen, hydrogen, helium, argon, and carbon dioxide.

[0062] The components other than the low boiling point components (condensed components) may have a boiling point at atmospheric pressure in the range of -70 to 200°C, preferably in the range of -20 to 90°C, and more preferably in the range of 0 to 80°C. The difference in boiling points between the two condensed components may be 60° C. or more, preferably 100° C. or more, and more preferably 190° C. or more.

[0063] Such condensed components include raw material gases used for forming thin films in the semiconductor manufacturing process, and specific examples thereof include tungsten hexafluoride, molybdenum hexafluoride, molybdenum dioxide dichloride, molybdenum pentachloride, disilane, trisilane, boron trichloride, silicon tetrachloride, trichlorosilane, dichlorosilane, and methyltrichlorosilane. Condensed components include by-products generated during thin film formation in the semiconductor manufacturing process, and specific examples include hydrogen fluoride, hydrogen chloride, and silicon tetrafluoride.

[0064] Examples of a method for using a mixed gas containing three or more components with different boiling points and separating a target component from among the three or more components include a gas separation and recovery method including a first separation step in which the mixed gas in a flow path is cooled to separate low-boiling point components contained in the mixed gas as gas and condense the other components in the flow path, and a second separation step in which, after the first separation step, the cooling is stopped and the components condensed in the flow path are separated into a gas phase and a liquid phase.

[0065] (1st separation step) In the first separation step, the mixed gas in the flow channel is cooled to separate low-boiling point components from among the components contained in the mixed gas as gas, and the other components are condensed in the flow channel. 1, first, the supply of the mixed gas from the gas supply path L1 to the gas separation section 2 is started. At this time, the cooling mechanism 3 is used to cool the space inside the gas separation section 2 to a temperature higher than the boiling point of the low boiling point component contained in the mixed gas and lower than the boiling points of components other than the low boiling point component. As a result, components other than the low boiling point components are condensed in the space inside the gas separation section 2, and the low boiling point components are discharged from the gas separation section 2.

[0066] When the low boiling point component is the target component, the on-off valve of the gas discharge path L2 is closed and the on-off valve of the transfer path L3 (or L4) is opened. As a result, the low boiling point component discharged from the gas separation unit 2 is transferred to the storage unit 5 via the transfer path L3 (or L4) and collected in the storage unit 5.

[0067] On the other hand, if the low boiling point component is not the target component, the on-off valve of the gas exhaust line L2 is opened and the on-off valve of the transfer line L3 (or L4) is closed. As a result, the low boiling point component discharged from the gas separation unit 2 is transferred to the decomposition device 300 via the gas exhaust line L2.

[0068] In the present invention, when at least one of the pressure and temperature in the inner space (first space) of the gas separation section 2, which separates the target component from the mixed gas, reaches a required threshold value, the supply of the mixed gas from the gas supply path L1 to the gas separation section 2 is stopped, and separation of the target component in the space (first space) within the gas separation section 2 is stopped.

[0069] Specifically, by using at least one of a pressure gauge 8 as a pressure detection means and a thermometer 9 as a temperature detection means, the end point of the first separation process can be determined when the measured value of the pressure or temperature in the space (first space) within the gas separation section 2 reaches a required threshold value.

[0070] The required threshold pressure in the space (first space) inside the gas separation section 2 can be appropriately selected depending on the desired recovery amount. Specifically, a value increased by 10% or more can be set as the threshold pressure. Furthermore, the required threshold value for the temperature in the space (first space) inside the gas separation section 2 can be appropriately selected depending on the desired recovery amount. Specifically, a value increased by 5° C. can be set as the threshold value.

[0071] (Second separation step) In the second separation step, after the first separation step, the cooling is stopped and the components condensed in the flow path are separated into a gas phase and a liquid phase. Specifically, first, the end point of the first separation step is detected using at least one of the pressure gauge 8 as pressure detection means and the thermometer 9 as temperature detection means, and then the supply of the mixed gas from the gas supply path L1 to the gas separation unit 2 is stopped. Next, cooling of the gas separation unit 2 by the cooling mechanism 3 is stopped. As a result, some of the components condensed in the space inside the gas separation section 2 (condensed components) evaporate, and are separated into a gas phase and a liquid phase.

[0072] Here, a part of the liquid phase located toward the bottom in gas separation section 2 vaporizes and becomes an ascending gas that rises within gas separation section 2. On the other hand, a part of the gas phase located toward the top in gas separation section 2 re-liquefies and becomes a descending liquid that descends within gas separation section 2. That is, due to gas-liquid contact in gas separation section 2, among the components contained in the condensed components, components with lower boiling points are concentrated in the gas phase, and components with higher boiling points are concentrated in the liquid phase.

[0073] In the second separation step, it is preferable to heat the space inside the gas separation section 2 using the heating mechanism 4, and it is preferable to heat the lower portion (i.e., the liquid phase portion) of the gas separation section 2. This promotes gas-liquid contact in the gas separation section 2, and enables each component to be concentrated to a high concentration on the gas phase side and the liquid phase side.

[0074] Here, when the component concentrated in the gas phase side is the target component, first, the on-off valve of the gas exhaust line L2 is closed, and the on-off valves of the transfer line L3 (or L4) and the exhaust line L5 are opened, and the pressure reducing device 6 is operated. As a result, the low boiling point components remaining in the gas phase components in the gas separation section 2 are transferred to the decomposition device 300 via the gas exhaust line L2. Next, the on-off valves of the exhaust path L5 and the return path L6 are closed. As a result, the gas phase components in the gas separation unit 2 are transferred to the storage unit 5 via the transfer path L3 (or L4) and collected in the storage unit 5. Furthermore, by cooling reservoir 5 using cooling mechanism 3, the separated (isolated) components can be stored in reservoir 5 in a liquid or solid state.

[0075] On the other hand, if the component concentrated in the gas phase is not the target component, the on-off valve of the gas exhaust line L2 is opened and the on-off valve of the transfer line L3 (or L4) is closed. As a result, the component discharged from the gas separation unit 2 is transferred to the detoxification device 300 via the gas exhaust line L2.

[0076] When the component concentrated on the liquid phase side is the target component, first, the on-off valve of the gas exhaust path L2 is opened and the on-off valve of the transfer path L3 (or L4) is closed, and the gas phase component in the gas separation unit 2 is discharged and transferred to the decontamination device 300 via the gas exhaust path L2. Next, the on-off valve of the gas exhaust path L2 is closed and the on-off valve of the transfer path L3 (or L4) is opened, and then the liquid phase is evaporated using the heating mechanism 4. As a result, the liquid phase component in the gas separation unit 2 is transferred to the storage unit 5 via the transfer path L3 (or L4) and collected in the storage unit 5. Furthermore, by cooling reservoir 5 using cooling mechanism 3, the separated (isolated) components can be stored in reservoir 5 in a liquid or solid state. When a path for withdrawing the liquid phase is provided below gas separation section 2, the liquid may be transferred to storage section 5 as a liquid.

[0077] On the other hand, if the component concentrated in the liquid phase is not the target component, the valve of the gas exhaust path L2 can be opened and the valve of the transfer path L3 (or L4) can be closed, and then the liquid phase can be evaporated using the heating mechanism 4 and transferred to the decomposition device 300 via the gas exhaust path L2. Furthermore, when a path for withdrawing the liquid phase is provided near the lower side of the gas separation section 2, the liquid may be discharged from the gas separation section 2 as it is.

[0078] In the second separation process, when discharging the target component from the inner space (first space) of the gas separation section 2, at least one of a pressure gauge 8 as a pressure detection means and a thermometer 9 as a temperature detection means can be used, and the end point of the discharge of the target component from the gas separation section 2 can be determined when at least one of the pressure and temperature in the inner space of the gas separation section 2 reaches a required threshold value. In other words, after detecting the end point of the discharge of the target component from the gas separation section 2 using at least one of the pressure gauge 8, which is a pressure detection means, and the thermometer 9, which is a temperature detection means, the discharge of the target component from the gas separation section 2 is stopped. The required threshold pressure in the space (first space) inside the gas separation section 2 can be appropriately selected depending on the desired recovery amount and the pressure resistance of the first space. Specifically, a value increased by 10% or more can be set as the threshold pressure. Furthermore, the required threshold value for the temperature in the space inside the gas separation section 2 (first space) can be appropriately selected according to the desired recovery amount. Specifically, the threshold value can be a value that decreases by 1° C. / min.

[0079] In addition, in the second separation process, when the target component is transferred from the space inside the gas separation section 2 (first space) to the space inside the storage section 5 (second space), at least one of a pressure gauge 10 as a pressure detection means and a thermometer 11 as a temperature detection means is used, and the end point of the transfer of the target component from the gas separation section 2 to the storage section 5 can be determined when at least one of the pressure and temperature in the space within the storage section 5 reaches a required threshold value. In other words, the end point of the transfer of the target component from the gas separation section 2 to the storage section 5 is detected using at least one of the pressure gauge 10, which is a pressure detection means, and the thermometer 11, which is a temperature detection means, and then the transfer of the target component from the gas separation section 2 to the storage section 5 is stopped. The required threshold value for the pressure in the space (second space) inside the storage section 5 can be appropriately selected depending on the desired recovery amount and the pressure resistance of the first space. Specifically, a value increased by 10% or more can be set as the threshold value. Furthermore, the required threshold value for the temperature of the space (second space) inside the storage section 5 can be appropriately selected according to the desired recovery amount. Specifically, the threshold value can be a value that increases by 1° C. / min.

[0080] (Resupply process) In the re-supply step, the components separated (isolated) from the mixed gas and stored in the storage section 5 are returned to the gas utilization facility 200. Specifically, first, the on-off valve of the transfer path L3 (or L4) is closed, and the on-off valve of the return path L6 is opened. As a result, the components collected in the storage section 5 are supplied to the gas utilization facility 300 via the return path L6. When the recovered components are stored in a liquid or solid state in the storage section 5, the recovered components can be supplied to the gas utilization equipment 200 as a gas by heating the storage section 5 using the heating mechanism 4.

[0081] In the re-supply process, when the target component stored in the storage section 5 is returned to the gas utilization equipment 200 (i.e., when the target component is discharged from the inner space (second space) of the storage section 5), at least one of a pressure gauge 10 serving as a pressure detection means and a thermometer 11 serving as a temperature detection means can be used to determine that the return of the target component from the storage section 5 to the gas utilization equipment 200 ends when at least one of the pressure and temperature in the space within the storage section 5 reaches a required threshold value. In other words, after detecting the end point of the target component discharge from the storage section 5 using at least one of the pressure gauge 10, which is a pressure detection means, and the thermometer 11, which is a temperature detection means, the return (discharge) of the target component from the storage section 5 to the gas utilization equipment 200 is stopped. The required threshold value for the pressure in the space (second space) inside the storage section 5 can be appropriately selected depending on the desired recovery amount and the pressure resistance of the first space. Specifically, a value increased by 10% or more can be set as the threshold value. Furthermore, the required threshold value for the temperature of the space (second space) inside the storage section 5 can be appropriately selected according to the desired recovery amount. Specifically, the threshold value can be a value that decreases by 1° C. / min.

[0082] In the gas separation and recovery method of the present invention, the component separated as a gas phase in the second separation step is preferably any one of tungsten hexafluoride, molybdenum hexafluoride, molybdenum dioxide dichloride, molybdenum pentachloride, disilane, trisilane, boron trichloride, silicon tetrachloride, trichlorosilane, dichlorosilane, and methyltrichlorosilane. These are components used as raw materials in gas utilization equipment 200 such as a thin film forming device, and can be recovered and returned as a high-concentration gas by concentrating them in the gas phase side, which is easy to isolate and purify, from the mixed gas.

[0083] (Continuous supply method) Next, a gas separation and recovery method according to one embodiment of the present invention will be described, in which separated (isolated) and recovered components are continuously supplied to a gas utilization facility. 3 to 5 are system diagrams showing the state of the gas separation and recovery apparatus when separation, recovery, and resupply are continuously performed in the gas separation and recovery method of this embodiment. In Fig. 3 to Fig. 5, the open valves indicate the open state, and the black valves indicate the closed state. Hereinafter, as shown in FIG. 1 and FIG. 3 to FIG. 5, a gas separation and recovery apparatus 1 having two gas separation sections 2A, 2B and two storage sections 5A, 5B is used to explain an example of separating tungsten hexafluoride from a mixed gas containing nitrogen, tungsten hexafluoride, and hydrogen fluoride.

[0084] In order to separate (isolate) tungsten hexafluoride from a mixed gas using the gas separation and recovery apparatus 1 and continuously supply it to the gas utilization facility 200, the pressure gauges 8A, 8B, 10A, 10B and thermometers 9A, 9B, 11A, 11B are used to detect the end points of gas supply and gas discharge, and the open / closed states of the on-off valves located in the paths L1 to L6, the refrigerant supply paths L31 to L34, and the heat medium supply paths L41 to L44 are controlled to select each path, thereby switching between the two gas separation units 2A, 2B and the two storage units 5A, 5B during operation. Nitrogen gas at -120°C is used as the refrigerant, and nitrogen gas at 35°C is used as the heat medium. As a result, the nitrogen contained in the mixed gas is sent as a low boiling point component from the gas separation section 2 to the detoxification device 300 via the discharge path L2 in the first separation step. Moreover, tungsten hexafluoride contained in the mixed gas is concentrated in the gas phase side of the gas separation section 2 in the second separation step, and is stored in the storage section 5 via the transfer path L3 (L4). On the other hand, hydrogen fluoride contained in the mixed gas is concentrated in the liquid phase side of the gas separation section 2 in the second separation step, and is discharged from the gas separation section 2 by any means.

[0085] "Operating condition A" In the operating state A of the gas separation and recovery apparatus 1 at any time, as shown in Fig. 3, the on-off valves in the gas supply path L1A, the gas exhaust path L2A, the transfer path L4A, the exhaust path L5A, and the transfer path L6B are open, and these paths are selected. In addition, the on-off valves in the refrigerant supply paths L31 and L33 and the heat medium supply paths L42 and L43 are open, and these paths are selected. As a result, in the operating state A of the gas separation and recovery apparatus 1, a first separation process is carried out in the gas separation section 2A, and a second separation process is carried out in the gas separation section 2B, and while tungsten hexafluoride is being transferred from the gas separation section 2B to the storage section 5A, tungsten hexafluoride is being supplied from the storage section 5B to the gas utilization equipment 200 (re-supply process).

[0086] When a required time has elapsed since the start of operating state A, one or both of the first separation step in gas separation unit 2A and the second separation step in gas separation unit 2B are completed. As a result, the gas separation and recovery apparatus 1 transitions from operating state A to operating state B (i.e., switching between gas separation units 2A and 2B).

[0087] Here, the end point of the first separation step in gas separation unit 2A can be detected by pressure gauge 8A located on gas supply path L1A. Specifically, the pressure value in gas separation unit 2A is measured by pressure gauge 8A, and the point at which the pressure value increases significantly due to clogging of gas separation unit 2A by condensed components is determined to be the end point of the first separation step.

[0088] On the other hand, the end point of the second separation step in the gas separation section 2B can be detected by the pressure gauge 10A or the thermometer 11A located on the return line L6A. Specifically, the pressure value in the storage section 5A is measured by the pressure gauge 10A, and the end point of the second separation step is the point at which the pressure value stops decreasing. In addition, the temperature in the storage section 5A is measured by the thermometer 11A, and the end point of the second separation step is the point at which the temperature stops decreasing.

[0089] "Driving situation B" Next, in the operating state B of the gas separation and recovery apparatus 1, as shown in Fig. 4, the on-off valves located in the gas supply path L1B, the gas exhaust path L2B, the transfer path L3A, the exhaust path L5A, and the transfer path L6B are in an open state, and these paths are selected. Also, the on-off valves located in the refrigerant supply paths L32, L33, and the heat medium supply paths L41, L43 are in an open state, and these paths are selected. As a result, in operating state B of the gas separation and recovery apparatus 1, the second separation process is carried out in the gas separation section 2A and the first separation process is carried out in the gas separation section 2B, and while tungsten hexafluoride is being transferred from the gas separation section 2A to the storage section 5A, tungsten hexafluoride is being supplied from the storage section 5B to the gas utilization equipment 200 (re-supply process).

[0090] When a required time has elapsed since the start of the operating state B, one or both of the transfer of tungsten hexafluoride to the storage section 5A and the supply of tungsten hexafluoride from the storage section 5B (the re-supply step) are completed. As a result, the gas separation and recovery apparatus 1 transitions from the operating state B to the operating state C (i.e., switching between the storage sections 5A and 5B).

[0091] Here, the end point of the transfer of tungsten hexafluoride to the storage section 5A can be detected by the pressure gauge 10A or the thermometer 11A located on the return line L6A. Specifically, the pressure value in the storage section 5A is measured by the pressure gauge 10A, and the end point is the point where the pressure value reaches a predetermined pressure or higher. In addition, the temperature in the storage section 5A is measured by the thermometer 11A, and the end point is the point where a temperature rise at a predetermined rate or higher is observed.

[0092] On the other hand, the end point of the re-supply process in the storage section 5B can be detected by a pressure gauge 10B or a thermometer 11B located on the return path L6B. Specifically, the pressure value in the storage section 5B is measured by the pressure gauge 10B, and the end point of the re-supply process is the point where the pressure value reaches a predetermined pressure or less. In addition, the temperature in the storage section 5B is measured by the thermometer 11B, and the end point of the re-supply process is the point where a temperature drop at a predetermined rate or more is observed.

[0093] "Driving status C" Next, in the operating state C of the gas separation and recovery apparatus 1, the on-off valves located in the gas supply path L1B, the gas exhaust path L2B, the transfer path L3B, the exhaust path L5B, and the transfer path L6A are in an open state, and these paths are selected, as shown in Fig. 5. In addition, the on-off valves located in the refrigerant supply paths L32, L34, and the heat medium supply paths L41, L44 are in an open state, and these paths are selected. As a result, in the operating state C of the gas separation and recovery apparatus 1, the second separation process is carried out in the gas separation section 2A and the first separation process is carried out in the gas separation section 2B, and while tungsten hexafluoride is being transferred from the gas separation section 2A to the storage section 5B, tungsten hexafluoride is being supplied from the storage section 5A to the gas utilization equipment 200 (re-supply process).

[0094] When a required time has elapsed from the start of the operating state C, one or both of the second separation step in the gas separation unit 2A and the first separation step in the gas separation unit 2B are completed. As a result, the gas separation and recovery apparatus 1 transitions from the operating state C to the operating state A' (i.e., switching between the gas separation units 2A and 2B).

[0095] According to the gas separation and recovery method of this embodiment, the pressure gauges 8A, 8B, 10A, 10B and the thermometers 9A, 9B, 11A, 11B are used to detect the end points of gas supply and gas discharge, and the open / close states of the on-off valves located in the paths L1 to L6, the refrigerant supply paths L31 to L34, and the heat medium supply paths L41 to L44 are selected. The two gas separation units 2A, 2B and the two storage units 5A, 5B are operated while being switched between, so that tungsten hexafluoride can be separated (isolated) from the mixed gas and continuously supplied to the gas utilization facility 200.

[0096] As described above, the gas separation and recovery apparatus 1 and the gas separation and recovery method of the present invention make it possible to detect the end point of gas separation when separating a target component from a mixed gas containing the component to be recovered.

[0097] Furthermore, the gas separation and recovery apparatus 1 and gas separation and recovery method of the present invention are provided with a gas separation section 2 having a space inside and a cooling mechanism 3, and by cooling the space in the gas separation section 2A with the cooling mechanism 3, it is possible to separate low boiling point components contained in the mixed gas from other components (condensed components). Furthermore, by providing a heating mechanism 4 and heating the condensed components in the gas separation section 2A with the heating mechanism 4, it is possible to make the space in the gas separation section 2A function as a distillation column, and therefore it is possible to concentrate the target components to a high purity. This eliminates the need for equipment for purifying the condensed components in the gas separation section 2A, and allows the device to be made compact.

[0098] Furthermore, according to the gas separation and recovery apparatus 1 and the gas separation and recovery method of the present invention, the highly reactive raw material gas (tungsten hexafluoride) can be easily isolated and recovered from a mixed gas containing a carrier gas (nitrogen), a highly reactive raw material gas (tungsten hexafluoride), and high-boiling-point impurities such as by-products (hydrogen fluoride), and the highly reactive raw material gas (tungsten hexafluoride) can be continuously re-supplied to the gas utilization facility 200.

[0099] The gas separation and recovery apparatus 1 and the gas separation and recovery method of the present invention have been described above with reference to the embodiments, but the present invention is not limited to these embodiments. Each configuration and their combinations in the above embodiments are merely examples, and addition, omission, substitution, and other modifications of the configurations are possible within the scope of the present invention. For example, in the above-mentioned embodiment, a configuration using a pressure gauge as a pressure detection means has been described as an example, but this is not limiting. Instead of a pressure gauge, a configuration using a back pressure valve provided in a path may also be used.

[0100] In the gas separation and recovery apparatus 1 of the above embodiment, the pressure gauge and thermometer of the gas separation unit 2 and the storage unit 5 are provided in a path connected to the primary side of the gas separation unit 2 and the storage unit 5, but the present invention is not limited to this. The pressure gauge and thermometer may be provided in a path connected to the secondary side of the gas separation unit 2 and the storage unit 5, or may be provided on both the primary side and the secondary side. When provided on both the primary side and the secondary side, the end points of gas supply and gas discharge can be detected more accurately when two or more gas separation units 2 and storage units 5 are switched and continuously operated.

[0101] In addition, in the gas separation and recovery apparatus 1 of the above-mentioned embodiment, a configuration including two each of the gas separation section 2 and the storage section 5 has been described as an example, but is not limited thereto. Either one or both of the gas separation section 2 and the storage section 5 may be configured to include one, or either one or both may be configured to include three or more.

[0102] In the gas separation and recovery apparatus 1 of the above embodiment, a commercially available plate-type heat exchanger is used as the gas separation section 2, but the present invention is not limited to this. A membrane separator made of a porous membrane may be used as the gas separation section.

[0103] 6 and 7 are system diagrams showing other embodiments of the gas separation section constituting the gas separation and recovery apparatus of the present invention. 6 and 7 differs in configuration from the gas separation and recovery apparatus 1 of the above-described embodiment in that a membrane separator made of a porous membrane 21 is used as the gas separation section 20. In addition, among the paths connected to the gas separation section 20 and the storage section 5, the paths on the primary side and the secondary side with respect to the flow of the mixed gas (gas) are provided with pressure gauges (pressure detection means) 8, 8', 10, 10' and thermometers (temperature detection means) 9, 9', 11, 11'.

[0104] In the gas separation section 20, one or more components contained in the mixed gas are precipitated as a solid on the membrane surface of the porous membrane 21, and other components are allowed to permeate, thereby separating (isolating) the target component. The target component may be on the permeate side (permeate) as shown in Fig. 6, or on the non-permeate side (retentate) as shown in Fig. 7.

[0105] When a target component is separated from a mixed gas using the gas separation section 20, one or more components contained in the mixed gas precipitate as a solid on the membrane surface of the porous membrane 21, thereby degrading the performance of the porous membrane 21. At this time, the pressure in the space located on the upstream side (primary side) of the porous membrane 21 among the spaces within the gas separation section 20 increases, and the pressure can be detected by the pressure gauge 8, which is a pressure detection means. Therefore, the precipitation status of solids in the porous membrane 21 can be monitored by pressure.

[0106] 6 and 7, in the gas separation section 20, a regenerated gas supply path L7 is connected to the permeate side of the porous membrane 21. In addition, in the gas separation section 20, an impurity discharge path L8 is connected. By supplying an inert gas such as nitrogen or other reactive gas that removes solids into the gas separation section 20 from the regeneration gas supply path L7, the solids precipitated on the membrane surface of the porous membrane 21 can be removed and the porous membrane 21 can be regenerated. As described above, even in a gas separation and recovery device that uses a membrane separator made of a porous membrane as the gas separation section 20, the end point of gas separation can be detected when separating a target component from a mixed gas containing the component to be recovered.

[0107] In addition, in the gas separation and recovery apparatus 1 of the above-mentioned embodiment, a configuration including a gas separation section 2 and a storage section 5 has been described, and the components contained in the mixed gas are separated in the gas separation section 2 and then stored in the storage section 5, but this is not limited thereto. In cases such as when the mixed gas contains two components, the target component may be separated in the gas separation section 2 and then stored, and the gas may be returned from the gas separation section 2 to the gas utilization facility 200. In this case, the storage section 5 is not necessary, and the space inside the gas separation section 2 serves as a space for gas separation (first space) and a space for gas storage (second space). Even in such a configuration, the end point of gas separation and the end point of gas supply can be detected by either one of the pressure detection means and the temperature detection means, so that continuous operation can be performed while switching between two or more gas separation sections 2. EXAMPLES

[0108] The present invention will be described in detail below with reference to verification tests, but the present invention is not limited thereto.

[0109] <Verification Test 1> Using the gas separation and recovery apparatus 1 shown in FIG. 2, components contained in a mixed gas were isolated. Specifically, a mixed gas containing 1% tungsten hexafluoride and 99% nitrogen was supplied to a gas separation section 2 cooled to -80°C, and it was verified whether the end point of gas separation could be detected using a pressure gauge 8 located in the gas supply path L1, which is the upstream path. FIG. 8 is a graph showing the behavior of the pressure value at the inlet of the gas separation section 2. In FIG. 8, the X-axis shows the recovery amount relative to the collection capacity of the gas separation section 2, and the Y-axis shows the pressure value at the inlet of the gas separation section 2.

[0110] As shown in Figure 8, when the amount of tungsten hexafluoride recovered exceeded a certain value (70% of the collection capacity), the pressure gauge 8 detected an increase in the pressure upstream of the gas separation unit 2. Furthermore, it was confirmed that the pressure value increased significantly when the amount of tungsten hexafluoride recovered exceeded 80% of the collection capacity, and then reached a predetermined pressure value (130 kPa). Therefore, it was confirmed that it is possible to detect the end point of gas separation in the gas separation unit 2 by monitoring the pressure value in the gas separation unit 2 using the pressure gauge 8.

[0111] <Verification Test 2> A gas separation and recovery device equipped with a pressure gauge and a thermometer was used on the transfer path L3, which is the upstream path of the storage section 5, to isolate components contained in the mixed gas in the gas separation section 2 and transfer the isolated components from the gas separation section 2 to the storage section 5. Specifically, after tungsten hexafluoride was solidified and separated in the gas separation section 2, the gas separation section 2 was heated to gasify tungsten hexafluoride, and transfer to the pre-cooled storage section 5 was started. At that time, it was verified whether the end point of the gas transfer could be detected using a pressure gauge and a thermometer located on the transfer path L3, which is the upstream path of the storage section 5. FIG. 9 is a graph showing the behavior of the pressure value and temperature value at the inlet of the storage section 5. In FIG. 9, the X-axis shows the time when the time from the transfer start to the transfer end point is set to 1, and the Y-axis shows the measured pressure and temperature values ​​at the inlet of the storage section 5.

[0112] As shown in Figure 9, the temperature decreased as the transfer of tungsten hexafluoride progressed, and the temperature became constant when the transfer was completed. Therefore, the end point of the transfer can be determined when the temperature drop at that location has ended, and it was confirmed that the end point of gas transfer can be detected using a thermometer.

[0113] When a pressure gauge was used, the pressure also decreased as the gas evaporated, so there was a time lag between the point at which the pressure fluctuations ceased and the point at which the temperature drop finished. By understanding the existence of this time lag, it was confirmed that it is possible to detect the end point of gas transfer even when a pressure gauge is used. [Explanation of symbols]

[0114] 1. Gas separation and recovery equipment 2, 2A, 2B, 20 Gas separation section 3...Cooling mechanism 4... Heating mechanism 5, 5A, 5B... Storage section 6. Pressure reducing device 7. Heater 8, 8A, 8B... Pressure gauge 9,9A,9B...Thermometer 10, 10A, 10B... Pressure gauge 11,11A,11B...Thermometer 21. Porous 100 Gas separation and recovery system 200 Gas utilization equipment 300...Abatement equipment L1, L1A, L1B Gas supply path L2, L2A, L2B...Gas exhaust path L3, L3A, L3B...Transportation route L4, L4A, L4B...Transportation route L5, L5A, L5B...Exhaust path L6, L6A, L6B... Return route (supply route) L7 Regenerative gas supply route L8: Impurity gas exhaust path L100 Exhaust gas route

Claims

1. A gas separation and recovery method for separating and recovering target components from a mixed gas discharged as exhaust gas from a gas utilization facility using a gas separation unit, the method comprising the steps of: The gas separation unit is a plate heat exchanger or a shell-and-tube heat exchanger, a condensation step of supplying the mixed gas to the gas separation section, and cooling the supplied mixed gas to condense the target components to be recovered and high-boiling components having a boiling point higher than that of the target components to be recovered within the gas separation section, and discharging a low-boiling component having a boiling point lower than that of the target components to be recovered from the gas separation section for disposal; an evaporation step of heating the condensed components to evaporate the components to be recovered, transferring them from the gas separation section to a storage section and recovering them, and leaving the high boiling point components in the gas separation section as a liquid phase; A gas separation and recovery method, wherein the condensation step is terminated when the pressure in the gas separation section increases due to clogging of the gas separation section by the condensed components.

2. A gas separation and recovery method as described in claim 1, wherein after the condensation process is completed and before the evaporation process is started, the pressure within the gas separation section is reduced, and the low boiling point components remaining in the gas separation section are discharged from the gas separation section and discarded.

3. A gas separation and recovery method as described in claim 1 or 2, wherein the evaporation process is terminated when the pressure in the storage section increases due to the desired recovery amount of the target component being recovered in the storage section.

Images