Gas separation and recovery device, gas separation and recovery method, and gas separation and recovery system

Abstract

To provide a gas separation recovery apparatus capable of separating a target component from mixed gas including three or more kinds of components different in a boiling point.SOLUTION: A selected gas separation recovery apparatus 1 comprises: a gas supply path L1 for supplying mixed gas including three or more kinds of components different in a boiling point; a heat exchange part 2 that communicates with the gas supply path L1 and that has a space provided on the inside; a gas discharge path L2 that communicates with the space and that discharges any one or more of the components, included in mixed gas, as gas; and a cooling mechanism 3 for cooling the space.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a gas separation and recovery apparatus, a gas separation and recovery method, and a gas separation and recovery system. [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 in which the target component is highly reactive, such as tungsten hexafluoride, a method of recovering and reusing unreacted gas from exhaust gas is being studied. Patent Document 2 discloses a technology for recovering and reusing unreacted tungsten hexafluoride on the secondary side of a processing device in a semiconductor manufacturing process. [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, the technology disclosed in Patent Document 2 recovers unreacted tungsten hexafluoride on the secondary side of a processing device in a semiconductor manufacturing process, but does not take into consideration by-products contained in exhaust gas. In other words, with the technology disclosed in Patent Document 2, the purity of tungsten hexafluoride is low, making it difficult to supply it to a processing device and reuse it.

[0009] The present invention has been made in consideration of the above problems, and has an objective of providing a gas separation and recovery device, a gas separation and recovery method, and a gas separation and recovery system that are capable of separating a target component from a mixed gas containing three or more components with different boiling points. [Means for solving the problem]

[0010] In order to achieve the above object, the present invention employs the following configuration. [1] A method for separating a target component from a mixed gas containing three or more components with different boiling points that is discharged as exhaust gas from a gas utilization facility, comprising the steps of: a first separation step of cooling the mixed gas in the flow path to separate low-boiling point components from the components as gas and condensing the other components in the flow path; A second separation step of stopping the cooling after the first separation step and separating the components condensed in the flow path into a gas phase and a liquid phase. fruit, The second separation step is a separation step by distillation. Gas separation and recovery methods. [2] The gas separation and recovery method according to [1], wherein the liquid phase is heated in the second separation step. [3] The gas separation and recovery method according to [1] or [2], further comprising recovering and storing any one of the components contained in the mixed gas. [4] The gas separation and recovery method according to [3], wherein the recovered components are supplied to the gas utilization facility. [5] The gas separation and recovery method according to any one of [1] to [4], wherein the component separated as the gas phase in the second separation step is any one of tungsten hexafluoride, molybdenum hexafluoride, molybdenum dioxide dichloride, molybdenum pentachloride, disilane, trisilane, boron trichloride, silicon tetrachloride, trichlorosilane, dichlorosilane, and methyltrichlorosilane. [6] The mixed gas contains nitrogen, tungsten hexafluoride, and hydrogen fluoride; The gas separation and recovery method according to any one of [1] to [5], wherein the tungsten hexafluoride is separated. [7] A gas separation and recovery apparatus for use in the gas separation and recovery method according to any one of [1] to [6]. And, A heat exchange unit having a cooling mechanism and a heating mechanism is provided, The first separation step is performed by cooling the space within the heat exchange unit using the cooling mechanism. A gas separation and recovery apparatus that performs the second separation process by heating the space within the heat exchange section using the heating mechanism, thereby vaporizing the liquid phase of the heat exchange section and causing it to rise, and re-liquefying the gas phase of the heat exchange section and causing it to descend, thereby performing distillation. [8] One or more gas utilization facilities that discharge a mixed gas containing three or more components with different boiling points as exhaust gas; a detoxification device that renders components contained in the exhaust gas harmless; One or more exhaust gas paths located between the gas utilization facility and the abatement device; [7] The gas separation and recovery apparatus according to the present invention, A gas separation and recovery system having one or more exhaust gas paths in which the gas separation and recovery device is disposed. 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 separating a target component from a mixed gas containing three or more components with different boiling points. The gas separation and recovery system of the present invention is capable of separating and reusing a target component from a mixed gas containing three or more components with different boiling points. [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 schematic diagram showing the configuration of the peripheral part of a plate-type heat exchanger used as a heat exchange section. [Figure 4] FIG. 2 is a schematic diagram showing the configuration of a plate-type heat exchanger used as a heat exchange section. [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. 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 7] 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 8] 1 is a system diagram showing a gas separation and recovery system according to an embodiment of the present invention. [Figure 9] FIG. 2 is a schematic diagram showing the configuration of the peripheral part of a shell-and-tube heat exchanger used as a heat exchange section. [Figure 10] FIG. 1 is a schematic diagram showing another configuration of a shell-and-tube heat exchanger used as a heat exchange section. 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 three or more components with different boiling points 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 three or more components with different boiling points as exhaust gas, and examples of such facilities include devices (processing equipment) that perform film formation and etching processes in the semiconductor manufacturing process. Examples of processing equipment 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, and Japanese Patent No. 4212746.

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

[0018] 1 and 2, the gas supply path 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 path L100. That is, the gas supply path L1 supplies a mixed gas containing three or more components having different boiling points to the heat exchanger 2.

[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] A pressure gauge 8 (8A, 8B) and a thermometer 9 (9A, 9B) are provided on the secondary side of the on-off valve in each of the branch paths L1A and L1B. The pressure gauges 8 (8A, 8B) indicate the pressure in the space inside the heat exchange section 2 (2A, 2B). The thermometer 9 (9A, 9B) indicates the temperature of the space inside the heat exchange section 2 (2A, 2B).

[0021] The heat exchanger 2 (2A, 2B) has one or more spaces inside. The space inside the heat exchanger 2 communicates with the gas supply path L1. Specifically, the heat exchanger 2A is connected to the branch path L1A, and the heat exchanger 2B is connected to the branch path L1B.

[0022] The space inside the heat exchange 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.

[0023] The space inside the heat exchange section 2 (2A, 2B) is used to separate (isolate) the condensed components by distillation (rectification). Therefore, the space inside the heat exchange section 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 heat exchange section 2 is preferably arranged so that the long side of the space is in the vertical direction.

[0024] Furthermore, it is preferable that a mechanism for enhancing gas-liquid contact during distillation (rectification) is provided in the space inside the heat exchange section 2 (2A, 2B). Examples of such a mechanism include unevenness provided on the surface of the inner wall of the heat exchange section 2 (2A, 2B) and a filler placed in the space.

[0025] A commercially available heat exchanger can be applied to the heat exchange 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.

[0026] 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.

[0027] The gas exhaust path L2 communicates with the space of the heat exchange unit 2 (2A, 2B). The gas exhaust path L2 branches into branch paths L2A and L2B. Specifically, the heat exchange unit 2A is connected to the branch path L2A, and the heat exchange 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.

[0028] The cooling mechanism 3 cools the space inside the heat exchange unit 2 (2A, 2B). Specifically, when a mixed gas is supplied from the gas supply path L1 to the space inside the heat exchange 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.

[0029] 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).

[0030] 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.

[0031] 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 heat exchange parts 2A and 2B and the storage parts 5A and 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.

[0032] The cooling sections (not shown) are located near the heat exchange sections 2 (2A, 2B) and the storage sections 5 (5A, 5B), respectively, and cool the inner spaces of the heat exchange sections 2 (2A, 2B) and the storage sections 5 (5A, 5B), respectively. The cooling section may be located outside (around) the heat exchange section 2 and the storage section 5, or may be located within the space inside the heat exchange section 2 and the storage section 5, as long as it is capable of cooling the space inside the heat exchange section 2 (2A, 2B) and the storage section 5 (5A, 5B).

[0033] 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.

[0034] The heating mechanism 4 heats the space inside the heat exchange section 2 (2A, 2B). Specifically, when components other than the low boiling point components are condensed in the space inside the heat exchange section 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.

[0035] 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).

[0036] 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 heat exchanger 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.

[0037] 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 heat exchange 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.

[0038] The heating units (not shown) are located near the heat exchange units 2 (2A, 2B) and the storage units 5 (5A, 5B), respectively, and heat the inner spaces of the heat exchange units 2 (2A, 2B) and the storage units 5 (5A, 5B), respectively. The heating section may be located outside (around) the heat exchange section 2 and the storage section 5, or may be located within the space inside the heat exchange section 2 and the storage section 5, as long as the heating section is capable of heating the space inside the heat exchange section 2 (2A, 2B) and the storage section 5 (5A, 5B).

[0039] Incidentally, when the components solidified in the space inside the heat exchange section 2 (2A, 2B) are liquefied, they gather in the lower part of the heat exchange section 2 due to gravity. Therefore, it is preferable that the heating section is located toward the lower part of the heat exchange section 2 (2A, 2B). This makes it possible to heat and vaporize the liquid phase part in the heat exchange section 2. The vaporized components are re-liquefied in the upper part of the heat exchange section 2, which promotes gas-liquid contact in the heat exchange section 2 and provides an effect similar to that of rectification. If the heat exchange section 2 has a mechanism for promoting gas-liquid contact, gas-liquid contact in the heat exchange section 2 is further promoted.

[0040] 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.

[0041] The heating mechanism 4 may be configured to include an additional heater near the heat exchange section 2 (2A, 2B) from the viewpoint of effectively separating the condensed components by distillation (rectification) in the space within the heat exchange section 2 (2A, 2B).

[0042] The additional heater is preferably disposed near the lower side of the heat exchange section 2 (2A, 2B). This makes it possible to heat the liquid phase portion in the heat exchange 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.

[0043] 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.

[0044] The transfer path L3 is a pipe for transferring the components isolated in the space within the heat exchange section 2A to the storage section 5 (5A, 5B). Further, the transfer path L4 is a pipe for transferring the components isolated in the space within the heat exchange section 2B to the storage section 5 (5A, 5B).

[0045] The base end of the transfer path L3 is connected to the heat exchanger 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 section 5A and the branch path L3B being connected to the storage section 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.

[0046] The base end of the transfer path L4 is connected to the heat exchanger 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 section 5A and the branch path L4B being connected to the storage section 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.

[0047] In this embodiment, the base ends of the transfer paths L3 and L4 are directly connected to the heat exchanger 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 tips connected to the storage section 5 (5A, 5B), and the base ends may be connected to a gas path connected to the heat exchanger 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 heat exchanger 2 (2A, 2B) to the storage section 5 (5A, 5B) via the gas supply path L1 or the gas exhaust path L2.

[0048] The storage section 5 (5A, 5B) stores any one of the components contained in the mixed gas isolated in the space in the heat exchange section 2 (2A, 2B). The inner spaces of the storage sections 5A, 5B are connected to the spaces in the heat exchange sections 2A, 2B via the transfer paths L3, L4, respectively.

[0049] The exhaust path L5 is a pipe for discharging the gas phase portion sucked in from the space within the heat exchange section 2 (2A, 2B) via the gas exhaust path L2 before the components isolated in the space within the heat exchange section 2 (2A, 2B) are transferred to the storage section 5 (5A, 5B).

[0050] 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.

[0051] 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 heat exchange unit 2 (2A, 2B) through the exhaust path L5 (L5A, L5B), the storage unit 5 (5A, 5B), and the transfer paths L3, L4, and discharged to the gas exhaust path L2. The pressure reducing device 6 is not particularly limited, and a vacuum pump, a Venturi tube, or the like can be used.

[0052] The return 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.

[0053] A pressure gauge 10 (10A, 10B) and a thermometer 11 (11A, 11B) are provided on the primary side of the on-off valve in each of the branch paths L6A and L6B. Pressure gauge 10 (10A, 10B) indicates the pressure in the space inside storage portion 5 (5A, 5B). Thermometer 11 (11A, 11B) indicates the temperature of the space inside storage portion 5 (5A, 5B).

[0054] The gas separation and recovery apparatus 1 of this embodiment is equipped with two heat exchange sections 2A, 2B, two storage sections 5A, 5B, and branched paths L1 to L6, and is configured to enable continuous operation by switching between these at appropriate times.

[0055] (Heat exchange part) Next, a case where a plate type heat exchanger is applied as the heat exchange section 2 constituting the gas separation and recovery apparatus 1 of this embodiment will be described. Fig. 3 is a schematic diagram showing the configuration of the peripheral part of the plate type heat exchanger 20 constituting the gas separation and recovery apparatus 1 of this embodiment. Also, Fig. 4 is a schematic diagram showing the configuration of the plate type heat exchanger 20.

[0056] As shown in FIG. 3, the plate heat exchanger 20 is provided with terminals 2a to 2d, with a gas supply path L1 connected to the upper terminal 2a and a gas exhaust path L2 connected to the lower terminal 2b. Similarly, a supply path L30 communicating with the cooling source 30 is connected to the lower terminal 2c, and a supply path L40 communicating with the heating source 40 is connected to the upper terminal 2d. Both the supply path L30 and the supply path L40 are shared as supply paths for the refrigerant and the heat medium. The transfer path L3 branches off from the gas supply path L1, and a back pressure valve 13 is located on the transfer path L3. The reservoir 5 is connected to a transfer path L3 and a return path L6. The exhaust path L5 branches off from the return path L6, and a vacuum pump serving as a pressure reducing device 6 is disposed on the exhaust path L5. A heater 7 is disposed below the plate-type heat exchanger 20.

[0057] 4(a), the plate type heat exchanger 20 has two or more heat exchange plates 21 and two or more heat exchange plates 22, and has a layered structure in which the heat exchange plates 21 and the heat exchange plates 22 are alternately stacked. In the plate type heat exchanger 20, the heat exchange plates 21 and 22 are arranged so that the long axes of the heat exchange plates 21 and 22 are vertical, and the overlapping direction of the heat exchange plates 21 and 22 is horizontal.

[0058] Each of the heat exchange plates 21 has a space inside. A mixed gas is supplied to the space inside the heat exchange plate 21. That is, the plate type heat exchanger 20 has two or more spaces to which the mixed gas is supplied. The heat exchange plates 21 are connected to the terminals 2a and 2b, respectively. As a result, in the plate-type heat exchanger 20, the mixed gas supplied from the terminal 2a is branched and supplied to the multiple heat exchange plates 21, and then the mixed gas is reunited from the multiple heat exchange plates 21 and discharged from the terminal 2b.

[0059] Each of the heat exchange plates 22 has a space inside. A refrigerant from a cooling source 30 or a heat medium from a heating source 40 is supplied to the space inside the heat exchange plate 22. That is, the heat exchange plate 22 constitutes a cooling part of the cooling mechanism 3 and a heating part of the heating mechanism 4. The heat exchange plates 22 are disposed between the heat exchange plates 21, respectively. The heat exchange plate 22 communicates with the terminals 2c and 2d, respectively.

[0060] The technical scope of the present invention is not limited to the above-mentioned embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, the plate-type heat exchanger 20 has two types of heat exchange plates 21 and 22, and the heat exchange plate 22 serves both as the cooling section of the cooling mechanism 3 and the heating section of the heating mechanism 4. However, the present invention is not limited to this. It may have three types of heat exchange plates, and the cooling section of the cooling mechanism 3 and the heating section of the heating mechanism 4 may use independent heat exchange plates.

[0061] In the plate-type heat exchanger 20, the number and size of the heat exchange plates 21, 22 may be appropriately selected according to the components contained in the mixed gas. This allows any component contained in the mixed gas to be appropriately isolated and recovered (a high recovery rate can be obtained).

[0062] <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 three or more components with different boiling points, which is discharged as 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 200 .

[0063] A mixed gas contains three or more components with different boiling points. 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] The gas separation and recovery method of the present invention includes 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.

[0068] (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 heat exchange section 2 is started. At this time, the cooling mechanism 3 is used to cool the space inside the heat exchange 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 the components other than the low boiling point component. As a result, components other than the low boiling point component are condensed in the space inside the heat exchange section 2, and the low boiling point component is discharged from the heat exchange section 2.

[0069] 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 heat exchanger 2 is transferred to the storage section 5 via the transfer path L3 (or L4) and collected in the storage section 5.

[0070] On the other hand, if the low boiling point component is not the target component, 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. As a result, the low boiling point component discharged from the heat exchanger 2 is transferred to the decomposition device 300 via the gas exhaust path L2.

[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 supply of the mixed gas from the gas supply path L1 to the heat exchange section 2 is stopped. Next, the cooling of the heat exchange section 2 by the cooling mechanism 3 is stopped. As a result, a part of the components condensed in the space inside the heat exchange section 2 (condensed components) evaporates and separates into a gas phase and a liquid phase.

[0072] Here, a part of the liquid phase located toward the bottom in the heat exchange section 2 vaporizes and becomes an ascending gas that rises within the heat exchange section 2. On the other hand, a part of the gas phase located toward the top in the heat exchange section 2 re-liquefies and becomes a descending liquid that descends within the heat exchange section 2. That is, due to gas-liquid contact in the heat exchange 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 heat exchange section 2 using the heating mechanism 4, and it is preferable to heat the lower portion (i.e., the liquid phase portion) of the heat exchange section 2. This promotes gas-liquid contact in the heat exchange section 2, and each component can 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 path L2 is closed, and the on-off valves of the transfer path L3 (or L4) and the exhaust path 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 heat exchanger 2 are transferred to the decomposition device 300 via the gas exhaust path 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 heat exchange section 2 are transferred to the storage section 5 via the transfer path L3 (or L4) and collected in the storage section 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 exhausted from the heat exchanger 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 heat exchanger 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 heat exchanger 2 is transferred to the storage portion 5 via the transfer path L3 (or L4) and collected in the storage portion 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 extracting the liquid phase is provided below the heat exchange section 2, the liquid may be transferred to the 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. In addition, when a path for withdrawing the liquid phase is provided near the lower side of the heat exchange section 2, the liquid phase may be discharged from the heat exchange section 2 as it is.

[0078] (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 200 via the return path L6. In addition, 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.

[0079] In the gas separation and recovery method of this embodiment, 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.

[0080] (Method using a heat exchanger) Next, a gas separation and recovery method when a plate-type heat exchanger 20 is used as the heat exchange section 2 will be described with reference to FIGS.

[0081] "First separation step" As shown in FIG. 4( a ), a heat exchange plate 22 is used as a cooling part of a cooling mechanism 3 . Specifically, the refrigerant is supplied to the heat exchange plate 22 via the terminal 2c. The supplied refrigerant is branched and supplied to the multiple heat exchange plates 22, and then rejoins the multiple heat exchange plates 22 and is discharged from the terminal 2d. At this time, in the plate-type heat exchanger 20, heat exchange is promoted by countercurrent flow between the mixed gas and the refrigerant, and the low boiling point components contained in the mixed gas are discharged from the heat exchange plate 21 through the terminal 2b to the gas discharge path L2, and the components other than the low boiling point components are condensed within the heat exchange plate 21.

[0082] "Second separation process" First, the supply of refrigerant to the heat exchange plate 22 is stopped. As a result, the components (condensed components) other than the low boiling point components condensed in the heat exchange plate 21 are partially evaporated. As shown in Fig. 4(b), in the space inside the heat exchange plate 21, a gas phase 21A is located near the top, and a liquid phase 21B is located near the bottom.

[0083] Next, in a state in which the gas phase 21A and the liquid phase 21B exist within the heat exchange plate 21, the heat exchange plate 22 is used as a heating part of the heating mechanism 4. Specifically, the heat medium is supplied to the heat exchange plate 22 via the terminal 2d. The supplied heat medium is branched and supplied to the multiple heat exchange plates 22, and then rejoins the multiple heat exchange plates 22 and is discharged from the terminal 2c. At this time, in the plate-type heat exchanger 20, the inside of the heat exchange plate 21 is heated by the heat medium, the liquid phase 21B vaporizes and rises inside the heat exchange plate 21, and the gas phase 21A re-liquefies and descends inside the heat exchange plate 21. As a result, among the components contained in the condensed components, the low boiling point components are concentrated on the gas phase 21A side, and the high boiling point components are concentrated on the liquid phase 21B side.

[0084] In the second separation step, a heater 7 may be further used. As shown in Fig. 3, the heater 7 is disposed near the lower side of the plate-type heat exchanger 20, and therefore the liquid phase 21B in the heat exchange plate 21 can be heated more effectively. This can promote separation of the condensed components in the heat exchange plate 21.

[0085] Next, as shown in FIG. 3, the gas phase 21A in the heat exchange plate 21 is extracted from the terminal 2a, and then is stored in the storage section 5 via the gas supply path L1 and the transfer path L3. On the other hand, the liquid phase 21B in the heat exchange plate 21 can be extracted from the terminal 2b.

[0086] (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. 5 to 7 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. 5 to Fig. 7, the open valves indicate the open state, and the black valves indicate the closed state. Hereinafter, as shown in Figs. 1 and 5 to 7, a gas separation and recovery apparatus 1 having two heat exchange 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.

[0087] 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 open / close states of the on-off valves located in the paths L1-L6, the refrigerant supply paths L31-L34, and the heat medium supply paths L41-L44 are controlled to select each path, and the two heat exchange sections 2A, 2B and the two storage sections 5A, 5B are operated while being switched between them. 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 heat exchange section 2 to the detoxification device 300 via the exhaust path L2 in the first separation step. Moreover, tungsten hexafluoride contained in the mixed gas is concentrated on the gas phase side of the heat exchange 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 heat exchange section 2 in the second separation step, and is discharged from the heat exchange section 2 by any means.

[0088] "Operating condition A" In the operating state A of the gas separation and recovery apparatus 1 at any time, as shown in Fig. 5, 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 heat exchange section 2A, and a second separation process is carried out in the heat exchange section 2B, and while tungsten hexafluoride is being transferred from the heat exchange 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).

[0089] When a required time has elapsed since the start of the operating state A, one or both of the first separation step in the heat exchange section 2A and the second separation step in the heat exchange section 2B are completed. As a result, the gas separation and recovery apparatus 1 transitions from the operating state A to the operating state B (i.e., switching between the heat exchange sections 2A and 2B).

[0090] Here, the end point of the first separation step in the heat exchange section 2A can be detected by the pressure gauge 8A located on the gas supply path L1A. Specifically, the pressure value in the heat exchange section 2A is measured by the pressure gauge 8A, and the point at which the pressure value increases significantly due to clogging of the heat exchange section 2A with the condensed components is determined as the end point of the first separation step.

[0091] On the other hand, the end point of the second separation process in the heat exchange section 2B can be detected by the pressure gauge 10A or the thermometer 11A located on the return path 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 process 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 process is the point at which the temperature stops decreasing.

[0092] "Driving situation B" Next, in the operating state B 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 L3A, the exhaust path L5A, and the transfer path L6B are in an open state, and these paths are selected, as shown in Fig. 6. 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 heat exchange section 2A and the first separation process is carried out in the heat exchange section 2B, and while tungsten hexafluoride is being transferred from the heat exchange 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).

[0093] 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).

[0094] 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 is observed at a predetermined rate of anomaly.

[0095] 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.

[0096] "Driving status C" Next, in the operating state C of the gas separation and recovery apparatus 1, the on-off valves 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 open, and these paths are selected, as shown in Fig. 7. Also, the on-off valves in the refrigerant supply paths L32, L34, and the heat medium supply paths L41, L44 are open, 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 heat exchange section 2A and the first separation process is carried out in the heat exchange section 2B, and while tungsten hexafluoride is being transferred from the heat exchange 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).

[0097] When a required time has elapsed since the start of the operating state C, one or both of the second separation step in the heat exchanger 2A and the first separation step in the heat exchanger 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 heat exchangers 2A and 2B).

[0098] As described above, in the gas separation and recovery method of this embodiment, by selecting 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, and operating the two heat exchange units 2A, 2B and the two storage units 5A, 5B while switching between them, it is possible to separate (isolate) tungsten hexafluoride from the mixed gas and continuously supply it to the gas utilization facility 200.

[0099] <Gas separation and recovery system> Next, the configuration of a gas separation and recovery system according to an embodiment of the present invention will be described. Fig. 8 is a system diagram showing a gas separation and recovery system according to an embodiment of the present invention. As shown in FIG. 8, the gas separation and recovery system 100 of this embodiment is roughly configured to include one or more gas utilization equipment 200A, 200B...200N that discharges a mixed gas containing three or more components with different boiling points as exhaust gas, a detoxification equipment 300 that neutralizes the components contained in the exhaust gas, one or more exhaust gas paths L100A, L100B...L100N located between the gas utilization equipment 200A, 200B...200N and the detoxification equipment 300, and gas separation and recovery equipment 1A, 1B...1N.

[0100] According to the gas separation and recovery system of this embodiment, the system is configured to have one or more exhaust gas paths L100 located between the gas utilization equipment 200 and the detoxification equipment 300, and in which the gas separation and recovery equipment 1 is arranged on the secondary side of the gas utilization equipment 200. The gas separation and recovery equipment 1 can separate and recover any component from the mixed gas discharged from the gas utilization equipment 200 and resupply it to the gas utilization equipment 200, thereby reducing the amount of gas used in the gas utilization equipment 200 and reducing the amount of processing in the detoxification equipment 300.

[0101] As described above, according to the gas separation and recovery apparatus 1 and the gas separation and recovery method of the present embodiment, a target component can be separated from a mixed gas containing three or more components with different boiling points.

[0102] Moreover, the gas separation and recovery apparatus 1 and the gas separation and recovery method of this embodiment are provided with a heat exchange section 2 having a space inside and a cooling mechanism 3, and by cooling the space in the heat exchange 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 heat exchange section 2A with the heating mechanism 4, it is possible to make the space in the heat exchange 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 heat exchange section 2A, and allows the device to be made compact.

[0103] Furthermore, according to the gas separation and recovery apparatus 1 and the gas separation and recovery method of this embodiment, 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 (hydrogen fluoride) such as by-products, and the highly reactive raw material gas (tungsten hexafluoride) can be continuously re-supplied to the gas utilization facility 200.

[0104] According to the gas separation and recovery system 100 of this embodiment, a target component can be separated from a mixed gas containing three or more components with different boiling points and reused. In addition, according to the gas separation and recovery system 100 of this embodiment, the gas separation and recovery device 1 is small and can be installed immediately after the gas utilization equipment 200 (secondary side), so that even highly reactive gases contained in the mixed gas can be continuously recovered and re-supplied to the gas utilization equipment 200. Furthermore, according to the gas separation and recovery system 100 of this embodiment, the amount of gas used in the gas utilization facility 200 can be reduced, so that the load on the abatement device 300 can be reduced.

[0105] Although 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, the present invention is not limited to these embodiments. Each configuration and their combination in the above-mentioned embodiments are merely examples, and addition, omission, substitution, and other modifications of the configurations are possible within the scope of the present invention.

[0106] In the gas separation and recovery apparatus 1 of the embodiment described above, a case has been described in which a commercially available plate type heat exchanger 20 is used as the heat exchange section 2, but the present invention is not limited to this. As the heat exchange section 2, a commercially available shell-and-tube heat exchanger may be used. FIG. 9 is a schematic diagram showing the configuration of the peripheral part of a shell-and-tube heat exchanger 20 ′ used as the heat exchange section 2 .

[0107] As shown in FIG. 9, a shell-and-tube heat exchanger 20' has a configuration in which a spiral pipe through which a refrigerant and a heat medium are supplied is disposed inside a vertical container to which a mixed gas is supplied. A gas supply path L1 is connected to the upper side of the side wall of the vertical vessel, and a gas discharge path L2 is connected to the upper side of the opposing side wall. A packing material 12 is disposed in the space inside the vertical vessel as a mechanism for promoting gas-liquid contact. A drainage path L7 is connected to the lower part of the vertical vessel for discharging the liquid phase stored in the lower part of the vertical vessel. One end of the spiral piping is connected to the cooling source 30 and the heating source 40, and the other end serves as an outlet for the refrigerant and the heat medium. The spiral piping is shared as a supply path for the refrigerant and the heat medium. The transfer path L3 branches off from the gas exhaust path L2, and a back pressure valve 13 is located on the transfer path L3. The reservoir 5 is connected to a transfer path L3 and a return path L6. The exhaust path L5 branches off from the return path L6, and a vacuum pump serving as a pressure reducing device 6 is disposed on the exhaust path L5. A heater 7 is disposed near the bottom of the side wall of the vertical container.

[0108] 9 shows an example of a shell-and-tube heat exchanger 20' used as the heat exchange section 2, in which a mixed gas is supplied to the inside of a vertical vessel, and a refrigerant and a heat medium are supplied to a spiral pipe, but the present invention is not limited to this. As shown in FIG 10, the shell-and-tube heat exchanger 20' may have a configuration in which a refrigerant and a heat medium are supplied to the inside of a vertical vessel, and a mixed gas is supplied to a spiral pipe.

[0109] In the first separation step of the shell-and-tube heat exchanger 20' shown in Fig. 10, a refrigerant is supplied to the inside of the vertical vessel, and a mixed gas is supplied to the spiral pipe from the gas supply path L1. As a result, components other than the low boiling point components are condensed in the spiral pipe, and the low boiling point components are discharged from the spiral pipe to the gas discharge path L2 (see Fig. 10(a)). In the second separation step, the supply of the mixed gas from the gas supply path L1 to the spiral pipe is stopped, and the supply of the refrigerant to the inside of the vertical vessel is stopped. As a result, some of the components condensed in the spiral pipe (condensed components) evaporate, and the gas phase components (tungsten hexafluoride in the figure) are discharged to the transfer path L3. At this time, by supplying the heat medium to the inside of the vertical vessel, gas-liquid contact in the spiral pipe is promoted, and each component is highly concentrated on the gas phase side and the liquid phase side (see FIG. 10(b)).

[0110] In addition, in the gas separation and recovery apparatus 1 of the above-mentioned embodiment, a configuration including two heat exchange sections 2 and two storage sections 5 has been described as an example, but is not limited thereto. Either one or both of the heat exchange sections 2 and the storage sections 5 may be configured to include one, or either one or both may be configured to include three or more.

[0111] In the gas separation and recovery apparatus 1 of the above embodiment, the pressure gauge and thermometer of the heat exchange section 2 and the storage section 5 are provided in the path connected to the primary side of the heat exchange section 2 and the storage section 5, but the present invention is not limited to this. The pressure gauge and thermometer may be provided in the path connected to the secondary side of the heat exchange section 2 and the storage section 5, or may be provided on both the primary side and the secondary side. EXAMPLES

[0112] The present invention will be described in detail below with reference to verification tests, but the present invention is not limited thereto.

[0113] <Verification Test 1> The components contained in the mixed gas were isolated using a plate-type heat exchanger 20 shown in Figs. 3 and 4 as the heat exchange section. (heat exchanger) The plate-type heat exchanger used for the test consisted of 10 heat exchange plates, with the flow path of each plate (channel) being 42 mm wide, 2 mm high on average, and 172 mm long. The heat exchange plates through which the mixed gas flows and the heat exchange plates through which the refrigerant flows were stacked alternately. (mixed gas) The composition of the mixed gas was 1 volume % tungsten hexafluoride (WF6) and 99 volume % nitrogen. The amount of the mixed gas supplied to the plate heat exchanger 20 was set to a flow rate of 16 slpm. (Refrigerant) The refrigerant used was cold nitrogen cooled to -80 to -115°C. (Test Method) Tungsten hexafluoride was isolated and recovered from the mixed gas by changing the temperature of the coolant supplied to the heat exchanger. The amount of tungsten hexafluoride collected in the heat exchanger per cycle (collection amount) and the ratio of the amount of tungsten hexafluoride collected to the total amount of tungsten hexafluoride supplied (collection rate) at each coolant temperature are shown in Table 1 below.

[0114] [Table 1]

[0115] As shown in Table 1, when a plate-type heat exchanger was used as the heat exchanger, it was confirmed that the amount of collected gas per cycle increased and the collection rate improved by using a lower temperature refrigerant.

[0116] <Verification Test 2> The components contained in the mixed gas were separated using a shell-and-tube heat exchanger 20' shown in FIG. 10 as the heat exchange section. (heat exchanger) The shell-and-tube heat exchanger used for the test had a structure in which a piping through which the mixed gas flows was installed inside the flow path through which the refrigerant flows. The piping through which the mixed gas flows had a tubular structure with an inner diameter of 3.15 mm and a length of 3 m. (mixed gas) The composition of the mixed gas was 1 volume % tungsten hexafluoride (WF6) and 99 volume % nitrogen. The amount of the mixed gas supplied to the shell-and-tube heat exchanger 20' was set to a flow rate of 16 slpm. (Refrigerant) The refrigerant used was ethylene glycol cooled to -60 to -100°C. (Test Method) The temperature of the coolant supplied to the heat exchanger was changed to isolate and recover tungsten hexafluoride from the mixed gas. The amount of tungsten hexafluoride collected in the heat exchanger per cycle (collection amount) and the ratio of the amount of collected tungsten hexafluoride to the total amount of tungsten hexafluoride supplied (collection rate) at each coolant temperature are shown in Table 2 below.

[0117] [Table 2]

[0118] As shown in Table 2, when a shell-and-tube heat exchanger was used as the heat exchange section, it was confirmed that the amount of collected gas per cycle was reduced and the collection rate was improved by using a lower temperature refrigerant.

[0119] <Verification Test 3> Using a plate-type heat exchanger 20 shown in Figures 3 and 4 and a shell-and-tube heat exchanger 20' shown in Figure 9 as the heat exchange section, components contained in a mixed gas were isolated, and the effect of promoting gas-liquid contact in the heat exchange section was verified.

[0120] (Plate type heat exchanger) The plate-type heat exchanger used for the test was the same as that used in the verification test 1. The following test was carried out for a case where the inner surface of the heat exchange plate was not uneven (no gas-liquid contact promotion) and a case where the inner surface was uneven (gas-liquid contact promotion). (Shell and tube heat exchanger) The shell-and-tube heat exchanger used for the tests had a cylindrical tube with a diameter of 100 mm and a height of 430 mm, inside which was wound a piping with a diameter of 6.2 mm and a length of 4,000 mm, forming a coil with a diameter of 70 mm and a height of 200 mm. The shell-and-tube heat exchanger is designed so that the refrigerant flows inside the coil tube and the mixed gas flows inside the cylindrical tube (outside the coil tube). The following tests were conducted on a shell-and-tube heat exchanger in which the lower part of the cylindrical tube was simply left hollow (no gas-liquid contact promotion), and on which a filler was introduced into the lower part of the cylindrical tube (with gas-liquid contact promotion). (mixed gas) The composition of the mixed gas was 1 volume % tungsten hexafluoride (WF6), 1 volume % hydrogen fluoride, and 98 volume % nitrogen. The flow rate of the mixed gas supplied to the plate heat exchanger 20 and the shell-and-tube heat exchanger 20' was set to 16 slpm. (Refrigerant) The coolant used was cold nitrogen cooled to -100°C. (Heating method) Heating was performed using electric heat or nitrogen heated to 35°C. For heating using an electric heating wire, the following tests were conducted in two cases: when the entire heat exchanger was heated (full heating) and when only the lower part of the heat exchanger was heated (partial heating).

[0121] (Test Method) Tungsten hexafluoride was isolated and recovered from the mixed gas using a heat exchanger, a heat exchange section with or without gas-liquid contact promotion, and a heating method, as shown in Table 3 below. The purity of the recovered tungsten hexafluoride is shown in Table 3 below.

[0122] [Table 3]

[0123] As shown in Table 3, it was confirmed that high-purity tungsten hexafluoride (WF6) gas can be obtained by promoting gas-liquid contact in the heat exchange section.

[0124] <Verification Test 4> Using a shell-and-tube heat exchanger 20' shown in FIG. 9 as the heat exchange section, arbitrary components contained in various mixed gases were isolated.

[0125] (heat exchanger) The shell-and-tube heat exchanger used for the test was the same as that used in Verification Test 3, in which a filler was introduced into the lower part of the cylindrical tube. (mixed gas) As shown in Table 4 below, the composition of the mixed gas was 1% by volume of the gas to be recovered and 99% by volume of other components. The amount of the mixed gas supplied to the heat exchanger 20' was set to a flow rate of 16 slpm. (Refrigerant) The refrigerant used was either cold nitrogen cooled to -100 to -30°C or nitrogen at room temperature (25°C). (Heating method) Using electric heat, only the lower part of the heat exchanger was heated to the temperature (heating temperature) shown in Table 4.

[0126] (Test Method) The target gas was isolated and recovered from the mixed gas using a heat exchanger with a combination of refrigerant temperature and heating temperature as shown in Table 4. The recovery rate of the target gas relative to the amount of mixed gas supplied to the heat exchanger and the purity of the target gas are shown in Table 4.

[0127] [Table 4]

[0128] As shown in Table 4, it was confirmed that the gas separation and recovery apparatus and gas separation and recovery method of the present invention are useful even when isolating and recovering any component contained in various mixed gases. [Explanation of symbols]

[0129] 1. Gas separation and recovery equipment 2,2A,2B...Heat exchange 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 12...Filling material 13 Back pressure valve 20 Plate type heat exchanger 20' Shell and Tube Heat Exchanger 21, 22...Heat exchange plate 21A Gas phase 21B...Liquid phase 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 L7: Drainage pathway L100 Exhaust gas route

Claims

1. A method for separating a target component from a mixed gas containing three or more components having different boiling points, which is discharged as an exhaust gas from a gas utilization facility, comprising the steps of: a first separation step of cooling the mixed gas in the flow path to separate low-boiling point components from the components as gas and condensing the other components in the flow path; A second separation step of stopping the cooling after the first separation step and separating the components condensed in the flow path into a gas phase and a liquid phase, The gas separation and recovery method, wherein the second separation step is a separation step by distillation.

2. The gas separation and recovery method according to claim 1 , wherein the liquid phase is heated in the second separation step.

3. The gas separation and recovery method according to claim 1 or 2, further comprising recovering and storing any one of the components contained in the mixed gas.

4. The gas separation and recovery method according to claim 3, wherein the recovered components are supplied to the gas utilization facility.

5. 5. The gas separation and recovery method according to claim 1, wherein the component separated as the gas phase in the second separation step is any one of tungsten hexafluoride, molybdenum hexafluoride, molybdenum dioxide dichloride, molybdenum pentachloride, disilane, trisilane, boron trichloride, silicon tetrachloride, trichlorosilane, dichlorosilane, and methyltrichlorosilane.

6. the mixed gas includes nitrogen, tungsten hexafluoride, and hydrogen fluoride; The gas separation and recovery method according to any one of claims 1 to 5, further comprising separating the tungsten hexafluoride.

7. A gas separation and recovery apparatus used in the gas separation and recovery method according to any one of claims 1 to 6, A heat exchange unit having a cooling mechanism and a heating mechanism is provided, The first separation step is performed by cooling the space within the heat exchange unit using the cooling mechanism. A gas separation and recovery apparatus that performs the second separation process by heating the space within the heat exchange section using the heating mechanism, thereby vaporizing the liquid phase of the heat exchange section and causing it to rise, and re-liquefying the gas phase of the heat exchange section and causing it to descend, thereby performing distillation.

8. One or more gas utilization facilities that discharge a mixed gas containing three or more components with different boiling points as an exhaust gas; a detoxification device that renders components contained in the exhaust gas harmless; One or more exhaust gas paths located between the gas utilization facility and the abatement device; The gas separation and recovery apparatus according to claim 7, A gas separation and recovery system having one or more exhaust gas paths in which the gas separation and recovery device is disposed.

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