JP5686527B2 - Recovery method of residual gas - Google Patents

Description

  The present invention relates to a method for recovering residual gas.

  Currently, there are various types of special gases used in the semiconductor field, typically hydride gases such as monosilane, monogermane, arsine, phosphine, and hydrogen selenide. Of these gases, monosilane, monogermane, arsine, phosphine, hydrogen selenide and the like are highly toxic and flammable gases and are very difficult to handle.

  In particular, the hydride-based gas is used as a high purity gas by itself, but is also widely used as a mixed gas diluted with a gas such as hydrogen or helium.

  Here, for example, a mixed gas diluted with hydrogen or the like can be safely used by separating it into hydrogen and special gas in the immediate vicinity of the equipment using the mixed gas, and sending only the special gas to the gas using equipment. Are known.

  Generally, special gas is filled in a cylinder (cylinder), but depending on the type of special gas, it is known that the special gas itself may have a larger filling amount than the pure gas that is not diluted. ing.

  When returning a used cylinder filled with a diluted mixed gas, the cylinder is generally returned as a residual gas while leaving some gas in the cylinder. By separating and recovering the residual gas into the gas for diluting and the special gas, the expensive special gas can be reused and the processing cost of the residual gas can be reduced.

On the other hand, when not separated and recovered, the remaining gas returned while remaining in the cylinder is discharged to the atmosphere after all appropriate detoxification treatment has been performed.
As the treatment of the residual gas, for example, xenon, krypton, etc. that are not produced domestically are diluted and released into the atmosphere. Toxic and flammable gases such as monosilane, monogermane, arsine, phosphine, and hydrogen selenide are also subjected to appropriate detoxification treatment, diluted and released into the atmosphere.

  Here, due to the recent increase in interest in environmental problems, it is required as a corporate social responsibility that rare special gases are recycled and special gases that are highly toxic and flammable are safely removed.

  For example, in the case of these semi-pure gases such as xenon and krypton which are rare gases that are not produced in Japan, the residual gas can be recovered relatively easily. In the case of a gas that is diluted and mixed with helium or the like, the current situation is that the recovery is not performed in view of the time for separating the diluted gas and the special gas.

  Similar problems occur in the case of hydride gases such as monosilane and monogermane. Moreover, even when performing safe and appropriate removal treatment without separation and recovery, especially in the case of gases diluted and mixed with hydrogen, these gases can be removed with a combustion removal device, a dry removal device, etc. When the detoxification treatment is performed, combustion heat and reaction heat are generated due to the influence of hydrogen, which not only imposes a burden on the detoxification device, but also has problems such as safety concerns and cost.

  As a process that does not separate and recover the residual gas that has been returned while remaining in the cylinder, an automated facility (see Patent Document 1) is used to reduce the labor required for releasing the residual gas and evacuation. A facility for releasing a residual gas of a certain gas (see Patent Documents 2 and 3) and the like.

  In addition, as a method of recovering and processing the gas used in the gas using facility, the used gas is temporarily stored in a gas bag or the like, transported to a place where the recovery processing facility is located, and then recovered and processed there. (Refer to patent documents 4) Or the equipment and method (refer patent documents 4-7) which install gas recovery processing equipment in the immediate vicinity of gas use equipment, and collect and process the gas used there are mentioned.

  Furthermore, as a method of separating the mixed gas using the separation membrane, a method of separating the hydride-based gas from hydrogen, helium, etc. using a polyimide membrane, a polyaramid membrane, a polysulfone membrane or the like (see Patent Documents 8 to 10). Etc.

Japanese Patent No. 3188502 JP-A-6-201097 JP 2007-24300 A Japanese Patent No. 3925365 JP 2001-353420 A Japanese Patent No. 4112659 JP 2000-325732 A JP-A-7-171330 JP 2002-308608 A Japanese Patent No. 2615265

  However, the above-described prior art has not disclosed any method for recovering the residual gas of the mixed gas that is returned while remaining in the cylinder gas.

  An object of the present invention is to provide a method for recovering a residual gas that can be more appropriately detoxified and recycled by efficiently separating and recovering the mixed gas remaining in the cylinder. In particular, it is an object to separate and recover a mixed gas in which a hydride gas is diluted and mixed with hydrogen, helium or the like safely and easily.

According to the first aspect of the present invention, a gas separation having a molecular sieving action is performed on a mixed gas of a gas component having a large molecular diameter and a gas component having a small molecular diameter that has a component concentration of 10% or more remaining in a used cylinder. is supplied to the separation membrane module comprising a membrane, a small gas component and after separation in a large gas component of the molecular size, a small gas component and the molecular size of large gas component of the molecular diameters of the molecular diameters of the mixed gas A residual gas recovery method for recovering
The gas component having a large molecular diameter is composed of any one or two or more of hydride gases composed of arsine, phosphine, hydrogen selenide, monosilane, monogermane,
The separation membrane module is
Close the non-permeate gas outlet provided in the sealed container containing the gas separation membrane so as to communicate with the space on the non-permeate side of the gas separation membrane, and communicate with the space on the permeate side of the gas separation membrane. In a state where the permeated gas discharge port provided is opened, the gas supply port is opened to supply a mixed gas containing a gas component having a small molecular diameter and a gas component having a large molecular diameter into the sealed container. A first process of charging,
When a predetermined time has elapsed from the start of the supply of the mixed gas or when the inside of the sealed container reaches a predetermined pressure, the gas supply port is closed to stop the supply of the mixed gas, and the state is maintained. The second process,
When a predetermined time has elapsed from the start of the holding state or when the inside of the sealed container has reached a predetermined pressure, the gas having a large molecular diameter is opened from the non-permeated gas discharge port. A third step of recovering the mixed gas containing the components;
When a predetermined time has elapsed from the start of the recovery or when the inside of the closed container reaches a predetermined pressure, an operation cycle consisting of a fourth process of closing the non-permeate gas outlet is continuously repeated. This is a residual gas recovery method for separating the gas and recovering the residual gas.

According to the second aspect of the present invention, a gas separation having a molecular sieving action is performed on a mixed gas of a gas component having a large molecular diameter and a gas component having a small molecular diameter that has a component concentration of 10% or more remaining in a used cylinder. is supplied to the separation membrane module comprising a membrane, a small gas component and after separation in a large gas component of the molecular size, a small gas component and the molecular size of large gas component of the molecular diameters of the molecular diameters of the mixed gas A residual gas recovery method for recovering
The gas component having a large molecular diameter is composed of any one or two or more of hydride gases composed of arsine, phosphine, hydrogen selenide, monosilane, monogermane,
Connecting two or more separation membrane modules in parallel;
One separation membrane module
Close the non-permeate gas outlet provided in the sealed container containing the gas separation membrane so as to communicate with the space on the non-permeate side of the gas separation membrane, and communicate with the space on the permeate side of the gas separation membrane. In a state where the permeated gas discharge port provided is opened, the gas supply port is opened to supply a mixed gas containing a gas component having a small molecular diameter and a gas component having a large molecular diameter into the sealed container. A first process of charging,
When a predetermined time has elapsed from the start of the supply of the mixed gas or when the inside of the sealed container reaches a predetermined pressure, the gas supply port is closed to stop the supply of the mixed gas, and the state is maintained. The second process,
When a predetermined time has elapsed from the start of the holding state or when the inside of the sealed container has reached a predetermined pressure, the gas having a large molecular diameter is opened from the non-permeated gas discharge port. A third step of recovering the mixed gas containing the components;
When a predetermined time has elapsed from the start of the recovery or when the inside of the sealed container reaches a predetermined pressure, an operation cycle consisting of a fourth process of closing the unpermeated gas discharge port is continuously repeated. Drive,
Other separation membrane module, one of the separation membrane the remaining gas of the gas, characterized in that the driving respectively the operating cycle operating cycle shifted by a predetermined interval to recover separated by residual gas module It is a collection method.

The invention according to claim 3 is characterized in that the gas separation membrane is any one of a silica membrane, a zeolite membrane, and a carbon membrane, and the residual gas according to claim 1 or 2 This is a recovery method.

Invention according to claim 4, wherein the small gas component having a molecular size of hydrogen, according to any one of claims 1 to 3, characterized in that a mixture of any one or more of helium This is a method for recovering residual gas.

  According to the residual gas recovery method of the present invention, the mixed gas remaining in the returned cylinder can be efficiently separated and recovered. Thereby, suitable detoxification processing and recycling can be performed simply.

It is a systematic diagram which shows an example of the collection | recovery apparatus used for the collection method of the residual gas which is the 1st Embodiment of this invention. It is an expanded sectional view of the separation membrane module used for the collection device of a 1st embodiment of the present invention. It is a systematic diagram which shows an example of the collection | recovery apparatus used for the collection method of the residual gas which is the 2nd Embodiment of this invention. It is an expanded sectional view of the separation membrane module used for the collection | recovery apparatus of the 2nd Embodiment of this invention. It is a systematic diagram which shows an example of the collection | recovery apparatus used for the collection method of the residual gas which is the 3rd Embodiment of this invention. It is an expanded sectional view of a separation membrane module unit used for a recovery device of a 3rd embodiment of the present invention. Reference Example 1 of the present invention, the residual gas pressure (≒ back pressure) and the flow behavior and monosilane in the gas (SiH ₄₎ is a diagram showing the concentration relationship. In Example 2 of this invention, it is a figure which shows an example of the timing chart in batch operation when the residual gas pressure (≒ filling pressure) is 0.2 MPaG. In Example 2 of this invention, it is a figure which shows an example of the timing chart in batch operation when the residual gas pressure (≒ filling pressure) is 0.05 MPaG.

<First Embodiment>
Hereinafter, a first embodiment to which the present invention is applied will be described in detail with reference to FIGS. 1 and 2.
An example of a recovery apparatus used in the residual gas recovery method according to the first embodiment to which the present invention is applied is shown in FIG. In this example of the recovery device, a carbon membrane module is used as an example of the separation membrane module. In this carbon membrane module, a carbon membrane is used as a gas separation membrane.

  As shown in FIG. 1, the recovery device 31 of this embodiment includes a cylinder 21 in which a mixed gas to be separated and recovered, a carbon membrane module 20 that separates the mixed gas, and a recovery that recovers the separated gas components. It is schematically configured with facilities 24 and 25.

  Specifically, the cylinder 21 and the supply port 3 provided in the carbon membrane module 20 are connected by a mixed gas supply path L1. A pressure reducing valve 22 and a flow meter 23 are disposed in the mixed gas supply path L1. Thereby, the mixed gas remaining in the cylinder 21 can be supplied to the carbon membrane module 20 while controlling the pressure and flow rate.

  Further, the permeate gas outlet 4 provided in the carbon membrane module 20 and the recovery facility 24 are connected by a permeate gas recovery path L4. Thereby, the permeated gas component separated by the carbon membrane module 20 can be recovered in the recovery facility 24.

  Further, the non-permeate gas outlet 5 provided in the carbon membrane module 20 and the recovery facility 25 are connected by a non-permeate gas recovery path L2. Thereby, the non-permeated gas component separated by the carbon membrane module 20 can be recovered in the recovery facility 25.

  Furthermore, the sweep gas supply port 8 provided in the carbon membrane module 20 is connected to a sweep gas supply source (not shown). Thereby, the sweep gas can be supplied into the carbon membrane module.

  As shown in FIG. 2, the carbon membrane module 20 is generally composed of a sealed container 6 and a carbon membrane unit (gas separation membrane) 2 provided in the sealed container 6.

  The sealed container 6 has a hollow cylindrical shape, and the carbon membrane unit 2 is accommodated in an internal space. A gas supply port 3 is provided at one end in the longitudinal direction of the sealed container 6, and an unpermeated gas discharge port 5 is provided at the other end. Further, on the peripheral surface of the sealed container 6, a permeated gas discharge port 4 and a sweep gas supply port 8 are provided on the peripheral surface of the sealed container 6.

  The carbon membrane unit 2 is composed of a number of hollow fiber-like carbon membranes 2a, which are gas separation membranes, and a pair of resin walls 7 that bind and fix both ends of the hollow fiber-like carbon membranes 2a. The resin wall 7 is hermetically fixed to the inner wall of the sealed container 6 using an adhesive or the like. In addition, openings of hollow fiber-like carbon membranes 2a are formed in the pair of resin walls 7, respectively.

The inside of the sealed container 6 is divided into three spaces of a first space 11, a second space 12, and a third space 13 by a pair of resin walls 7. The first space 11 is a space between one end of the sealed container 6 provided with the gas supply port 3 and the resin wall 7, and the second space 12 is paired with the peripheral surface of the sealed container 6. The third space 13 is a space between the resin wall 7 and the resin wall 7. The third space 13 is a space between the other end of the sealed container 6 provided with the non-permeated gas discharge port 5 and the resin wall 7.
In addition, a pressure gauge 14a is provided in the first space 11, a pressure gauge 14b is provided in the second space 12, and a pressure gauge 14c is provided in the third space 13, so that the internal pressure can be measured. Has been.

  The gas supply port 3 is provided so as to communicate with the first space 11 in the sealed container 6. The gas supply port 3 is provided with an open / close valve 3a. Then, by opening the on-off valve 3a, the mixed gas can be supplied into the first space 11 from the mixed gas supply path L1 through the gas supply port 3.

  The non-permeated gas discharge port 5 is provided so as to communicate with the third space 13 in the sealed container 6. The non-permeate gas outlet 5 is provided with an opening / closing valve 5a and a back pressure valve 15. Then, by opening the opening / closing valve 5a, the non-permeated gas can be discharged from the third space 13 to the non-permeated gas recovery path L2 via the non-permeated gas discharge port 5.

  The permeate gas discharge port 4 and the sweep gas supply port 8 are provided so as to communicate with the second space 12 in the sealed container 6. The permeate gas discharge port 4 is provided with an open / close valve 4a, and the sweep gas supply port 8 is provided with an open / close valve 8a. Then, by opening the on-off valve 4a, the permeated gas can be discharged from the second space 12 to the permeated gas recovery path L4 via the permeated gas discharge port 4. On the other hand, by opening the on-off valve 8a, the sweep gas can be supplied from the sweep gas supply path L3 to the second space 12 through the sweep gas supply port 8.

  One end of the hollow fiber-like carbon membrane 2a... Is fixed to one resin wall 7 and opened, and the other end is fixed to the other resin wall 7 and opened. Thereby, in the part where hollow fiber-like carbon membrane 2a ... is fixed by one resin wall 7, one opening part of hollow fiber-like carbon membrane 2a ... is connected with the 1st space 11, and the other opening part is It communicates with the third space 13. Thereby, the 1st space 11 and the 3rd space 13 are connected via the internal space of hollow fiber-like carbon membrane 2a .... On the other hand, the first space 11 and the second space 12 communicate with each other via the carbon membrane unit 2.

  The hollow fiber-like carbon film 2a is formed by forming an organic polymer film and then sintering it. For example, a film-forming stock solution is prepared by dissolving polyimide, which is an organic polymer, in an arbitrary solvent, and a solvent that is insoluble in polyimide is prepared by mixing with the solvent of the film-forming stock solution. Next, the film-forming stock solution is extruded from the circumferential annular port of the hollow fiber spinning nozzle having a double-pipe structure, and the solvent is simultaneously extruded into the coagulating liquid from the central circular port of the spinning nozzle to form a hollow fiber shape. Manufacturing organic polymer membranes. Next, the obtained organic polymer film is carbonized after being infusibilized to form a carbon film.

  The carbon membrane is used by selecting an optimal form such as a carbon membrane coated only on a porous support and a carbon membrane coated on a gas separation membrane other than the carbon membrane. Examples of the porous support include ceramic-based alumina, silica, zirconia, magnesia, zeolite, and metal-based filters. Application to the support has effects such as improvement of mechanical strength and simplification of carbon film production.

In the present embodiment, the gas separation membrane is used when performing a separation operation in a steady state. On the other hand, as in the second and third embodiments to be described later, when the pressure swing is used like PSA, it has a good stability against the pressure swing, that is, the mechanical strength is higher than the conventional one. Is also required for gas separation membranes.
Therefore, in the present invention, it is preferable to use an inorganic gas separation membrane such as a silica membrane, a zeolite membrane or a carbon membrane rather than a general polymer membrane gas separation membrane.

  The organic polymer used as the raw material for the carbon film includes polyimide (aromatic polyimide), polyphenylene oxide (PPO), polyamide (aromatic polyamide), polypropylene, polyfurfuryl alcohol, polyvinylidene chloride (PVDC), phenol resin, Examples thereof include cellulose, lignin, polyetherimide, and cellulose acetate.

  Among the above carbon film materials, polyimide (aromatic polyimide), cellulose acetate, and polyphenylene oxide (PPO) can be easily formed into a hollow fiber carbon film. Polyimide (aromatic polyimide) and polyphenylene oxide (PPO) have particularly high separation performance. Furthermore, polyphenylene oxide (PPO) is less expensive than polyimide (aromatic polyimide).

Next, the residual gas recovery method of this embodiment using the recovery device 31 shown in FIG. 1 will be described.
In the method for recovering a residual gas according to this embodiment, the mixed gas remaining in the cylinder 21 is continuously supplied to a separation membrane module including a separation membrane having a molecular sieving action, and the mixed gas is supplied to a gas component having a small molecular diameter and a molecule. In this method, the gas component having a small molecular diameter and the gas component having a large molecular diameter are recovered in the recovery facilities 24 and 25 after being separated into gas components having a large diameter. In the present embodiment, a case will be described in which the separation membrane module is a carbon membrane module 20 having a molecular sieving action, and the mixed gas to be separated is a mixed gas of a dilution gas and a hydride-based gas. Here, the molecular sieving action is an action in which the mixed gas is separated into a gas having a small molecular diameter and a gas having a large molecular diameter depending on the molecular diameter of the gas and the pore diameter of the separation membrane.

  The gas to be separated and recovered in this embodiment is a hydride gas such as monosilane, monogermane, arsine, phosphine, hydrogen selenide, or a special gas typified by a rare gas such as xenon or krypton. These are mixed gases diluted and mixed with a diluent gas such as hydrogen or helium.

  Here, a dilution gas such as hydrogen or helium is a gas component having a relatively small molecular diameter, and a hydride gas such as monosilane or monogerman, or a rare gas such as xenon or krypton is a gas having a relatively large molecular diameter. Can be classified into components.

  That is, the mixed gas to be separated and recovered is a mixture of two or more of a gas component having a small molecular diameter and a gas component having a large molecular diameter. Any combination of gas components may be used as long as there is a difference in molecular diameter between them. The greater the difference between these molecular diameters, the shorter the processing time for the separation operation.

  As the gas component having a small molecular diameter in the mixed gas, it is preferable to use a gas component having a molecular diameter of 3 mm or less. On the other hand, the gas component having a large molecular diameter in the mixed gas is preferably a gas component having a molecular diameter larger than 3 mm, preferably 4 mm or larger, more preferably 5 mm or larger.

  The mixed gas is not limited to a two-component system, and may be a mixture of a plurality of gas components. In order to sufficiently separate each gas component on either the permeation side or the non-permeation side of the separation membrane, it is preferable that the gas components are largely classified into a gas component group having a large molecular diameter and a gas component group having a small molecular diameter. The pore diameter of the carbon film may be between the molecular diameter of the gas component group having a large molecular diameter and the molecular diameter of the gas component group having a small molecular diameter. The pore diameter of the carbon film can be adjusted by changing the firing temperature during carbonization.

  Further, the residual gas remaining in the cylinder 21 is usually 1 MPaG or less in many cases. In the residual gas recovery method of the present embodiment, the residual gas is supplied to the carbon membrane unit 2 and held at an appropriate separation / recovery pressure by the back pressure valve 15 installed at the rear stage of the carbon membrane module 20. By utilizing the pressure difference between the non-permeate side 20 and the permeate side as a drive source for moving the gas component molecules, a molecular sieving action is performed to separate the mixed gas.

Next, a gas separation operation using the carbon membrane module 20 shown in FIG. 2 will be described.
Specifically, as shown in FIG. 2, first, the open / close valve 5a provided in the non-permeate gas discharge port 5 corresponding to the high pressure side (non-permeate side) of the carbon film is opened, and the back pressure valve 15 is set to the adjustment pressure. To do. Then, the open / close valve 3a of the mixed gas supply port 3 is opened, and the mixed gas is supplied and charged into the carbon membrane module 20 from the low pressure state until a predetermined pressure is reached. At this time, the open / close valve of the sweep gas supply port 8 on the low pressure side (permeation side) of the carbon membrane module 20 is closed, and the open valve 4a of the permeate gas discharge port 4 is opened. As a result, only a gas component having a small molecular diameter is selectively and preferentially permeated to the low pressure side (second space 12) of the carbon membrane module 20 from the mixed gas supplied to the non-permeation side (first space 11). And can be discharged from the permeate gas discharge port 4. On the other hand, a mixed gas containing a large amount of gas components having a large molecular diameter can be discharged from the non-permeated gas discharge port 5.

  Here, when the mixed gas is supplied from the cylinder 21 to the carbon membrane module 20, the pressure of the cylinder 21 decreases. In this case, if necessary, the pressure on the supply side (non-permeation side) is brought close to atmospheric pressure by evacuating the permeate side of the carbon membrane module 20 or supplying the sweep gas from the sweep gas supply port 8 as necessary. Even then, separation and recovery can be performed efficiently.

  By the separation and concentration operation using such a carbon membrane module 20, a gas component having a large molecular diameter, for example, a hydride gas such as monosilane or a rare gas such as xenon is concentrated and separated on the non-permeate side of the separation membrane. On the other hand, a gas component having a small molecular diameter, for example, a diluted gas component such as hydrogen or helium, is continuously recovered from the permeation side of the separation membrane.

  Concentrated and separated gas components such as monosilane and xenon are introduced into a recovery facility 25 installed at a later stage. And according to the property of gas, it collects in a container as it is, it cools, and it collects appropriately by liquefaction recovery, gas recovery using a compressor, etc.

  On the other hand, gas components such as hydrogen and helium recovered by the permeation-side recovery facility 24 are similarly recovered by an appropriate recovery method.

  The gas recovered in the recovery facility 24 and the gas recovered in the recovery facility 25 are subjected to a detoxification process and recycling according to the respective purposes.

  As described above, according to the residual gas recovery method of the present embodiment, the mixed gas remaining in the returned cylinder 21 can be efficiently separated and recovered. Thereby, suitable detoxification processing and recycling can be performed simply.

  In the present embodiment, since the remaining gas is continuously supplied from the cylinder 21 to the carbon membrane module 20, the remaining gas can be separated and recovered by a very simple operation.

<Second Embodiment>
Next, a second embodiment to which the present invention is applied will be described. This embodiment has a different configuration from the residual gas recovery method of the first embodiment. Therefore, the residual gas recovery method of this embodiment will be described with reference to FIGS. 3 and 4. About the collection | recovery apparatus and carbon membrane module which are used for collection | recovery of the residual gas of this embodiment, the same code | symbol is attached | subjected about the same component as 1st Embodiment, and description is abbreviate | omitted.

The recovery device 32 used in the residual gas recovery method of the present embodiment shown in FIG. 3 is different from the recovery device 31 in the first embodiment shown in FIG. 1 in that the carbon membrane module 1 is used.
As shown in FIG. 4, the carbon membrane module 1 used in the present embodiment has a flow meter in place of the back pressure valve 15 provided in the rear stage of the non-permeate gas discharge port 5 in the carbon membrane module 20 in the first embodiment. The difference is that 9 is installed.

  Here, as a pressure control method related to the separation membrane, when continuous membrane separation is performed as in the residual gas recovery method of the first embodiment, a back pressure valve 15 is provided at the outlet of the non-permeation side of the separation membrane. It is common to do so by installing etc.

On the other hand, in the present embodiment, as will be described later, since batch-type gas separation is performed, it is not particularly necessary to provide a back pressure valve for controlling the pressure of the separation membrane. As shown in FIG. 3, in the carbon membrane module 1 of this embodiment, the pressure control of the gas separation membrane (carbon membrane unit 2) can be performed by closing the opening / closing valve 5a of the non-permeate gas discharge port 5.
When taking out the non-permeate gas held on the non-permeate side of the gas separation membrane, it is preferable to provide a flow meter 9 or the like at the non-permeate gas outlet 5 and take out the non-permeate gas at an appropriate constant flow rate. If the open / close valve 5a of the non-permeate gas discharge port 5 is opened at a time (once) and the non-permeate gas is taken out without controlling the flow rate of the non-permeate gas, the separation membrane may be seriously damaged.

Next, the residual gas recovery method of the present embodiment using the recovery device 32 shown in FIG. 3 will be described.
The residual gas recovery method of the present embodiment performs gas separation by a method different from the first embodiment in which a mixed gas is continuously supplied from the cylinder 21 to the carbon membrane module 20.

  In the residual gas recovery method of the present embodiment, the carbon membrane module 1 is operated by continuously repeating the operation cycle including the following first to fourth processes.

(First process)
First, in the supply process, which is the first process, an unsealed container 6 that is provided to communicate with the third space 13 (the space on the non-permeate side of the gas separation membrane) of the sealed container 6 in which the carbon membrane unit 2 is accommodated. With the on-off valve 5a of the permeate gas discharge port 5 closed, the on-off valve 4a of the permeate gas discharge port 4 provided to communicate with the second space 12 (the space on the permeate side of the gas separation membrane) is opened. The open / close valve 3a of the gas supply port 3 is opened, and the mixed gas is supplied into the sealed container 6 from the mixed gas supply path L1 and charged.

In the first process, the mixed gas is supplied from the gas supply port 3 into the sealed container 6 at a controlled flow rate (for example, a constant flow rate). Here, since the non-permeate gas discharge port 5 on the non-permeate side of the sealed container 6 is closed, the pressure (supply pressure) of the first space 11 rises when the mixed gas is supplied at a constant flow rate. Accordingly, the pressure (non-permeation pressure) in the third space 13 on the non-permeation side of the carbon membrane unit 2 in the sealed container 6 also increases.
On the other hand, since the permeate gas discharge port 4 on the permeate side of the sealed container 6 is open, the pressure (permeate pressure) in the second space 12 does not change. In addition, since the dilution gas in the mixed gas passes through the carbon membrane unit 2 and moves to the second space 12 and is discharged from the permeate gas discharge port 4 to the permeate gas discharge path L4, the permeate flow rate is increased. It becomes constant.
The supply pressure is measured with a pressure gauge 14a, the non-permeation pressure is measured with a pressure gauge 14c, and the permeation pressure is measured with a pressure gauge 14b.

The time required for the first process (T ₁ ) is not particularly limited, and the volume (V) of the hermetic container 6, the performance (P, S) of the carbon membrane unit 2, the supply flow rate of the mixed gas ( F) and filling pressure (A) can be appropriately selected according to each condition.

  Here, if the volume (V) of the airtight container 6 increases, the amount of the mixed gas supplied to the airtight container 6 increases, and the time required for the first process becomes longer if the supply flow rate of the mixed gas does not change. Further, since the amount of gas mixture to be supplied increases, the recovered amount after separation increases.

  As the filling pressure (A) increases, the amount of mixed gas supplied to the sealed container 6 increases, and the time required for the first process increases unless the supply flow rate of the mixed gas changes. Further, since the amount of gas mixture to be supplied increases, the recovered amount after separation increases. However, if the filling pressure is too high, the carbon membrane unit 2 may be damaged or the like, and therefore the filling pressure is preferably 1 MPaG or less. Furthermore, in the case of the hydride gas which is the separation object of the present invention, it is preferable not to raise the pressure so much in terms of safety, so that it is more preferably 0.5 MPaG or less, and 0.2 MPaG or less. Further preferred.

  The performance of the carbon membrane unit 2 (permeation rate of the permeation component) (P) represents the permeation rate of the component that passes through the carbon membrane 2a constituting the carbon membrane unit 2. For example, when the permeation component is hydrogen, the required time becomes longer as the permeation rate of hydrogen increases. This is because hydrogen escapes simultaneously with charging.

  The performance (separation performance) (S) of the carbon membrane unit 2 represents the performance of separation into a component that permeates the carbon membrane constituting the carbon membrane unit 2 and a component that does not permeate (residual component). For example, when the permeation component is hydrogen and the residual component is monosilane, the required time is shortened if the separation performance for hydrogen and monosilane is large. This is because the monosilane remains without passing through the carbon film constituting the carbon membrane unit 2, that is, the permeation rate of the monosilane is small, so that the monosilane is charged faster.

  Further, if the supply flow rate (F) is large, the required time is shortened. However, since there is a risk of damage such as breakage to the carbon membrane unit 2, it is preferable to supply at a linear velocity of 10 cm / sec or less. More preferably, it is 1 cm / sec or less. However, this is not the case when a resistance plate or a diffusion plate is introduced so that the gas flow does not directly hit the carbon film 2a.

From the above-described conditions, the required time (T ₁ ) of the first process is related as shown in the following formula (1).
T ₁ ∝ (V × A × P) / (S × F) (1)

For example, the membrane area 1114 cm ² (membrane performance: hydrogen permeation rate = 5 × 10 ⁻⁵ cm ³ (STP) / cm ² / sec / cmHg, (hydrogen / monosilane separation factor) = approximately shown in the examples described later. In the case of a closed container having a carbon membrane unit of 5000) sufficiently dense, when a mixed gas of 10% monosilane and 90% hydrogen is supplied at a flow rate of 150 sccm, the filling value becomes 0. It will reach 2 MPaG.

(Second process)
Next, in the separation process, which is the second process, when a predetermined time has elapsed since the start of the supply of the mixed gas, or when the pressure in the sealed container 6 (supply pressure or non-permeation pressure) reaches a predetermined pressure, The open / close valve 3a of the gas supply port 3 is closed to stop the supply of the mixed gas, and this state is maintained.
As a result, only the dilution gas, which is a gas component having a small molecular diameter, is selectively and preferentially separated from the mixed gas supplied to the non-permeate side (first and third spaces 11 and 13) of the carbon membrane unit 2. It is possible to allow the hydride gas, which is a gas component having a large molecular diameter, to remain on the non-permeating side while permeating to the low pressure side (second space 12) of the membrane.

In the second process, the supply flow rate becomes zero because the supply of the mixed gas from the gas supply port 3 into the sealed container 6 is stopped. At this time, the open / close valves 3a and 5a of the gas supply port 3 and the non-permeate gas discharge port 5 on the non-permeate side of the sealed container 6 are closed, but the dilution gas in the mixed gas permeates the carbon membrane unit 2. Since the gas is discharged from the permeate gas discharge port 4 to the permeate gas discharge path L4, the supply pressure and the non-permeate pressure gradually decrease.
On the other hand, the permeate gas outlet 4 on the permeate side of the sealed container 6 is open, and the pressure (permeate pressure) in the second space 12 does not change. However, the permeate flow rate of the dilution gas discharged from the permeate gas discharge port 4 to the permeate gas discharge path L4 gradually decreases.

The time required for the second process (T ₂ ) is not particularly limited, and the volume (V) of the sealed container 6, the filling pressure (A), the predetermined pressure at the end of separation (also referred to as discharge pressure, B), can be appropriately selected according to the performance (P, S) of the carbon membrane unit 2 and the composition (Z) of the supply gas.

Here, the volume (V), the filling pressure (A), and the performance (separation performance) (S) of the carbon membrane unit 2 are as described in the first step.
The performance of the carbon membrane unit 2 (permeation rate of the permeation component) (P) is shorter when the permeation rate is higher, for example, when the permeation component is hydrogen. This is because hydrogen escapes quickly.

  If the discharge pressure (B) is high, the time required for the second process is shortened. However, if the pressure is higher than the ideal discharge pressure, the pressure is not sufficiently separated, and the purity of the recovered gas does not become high purity or high concentration.

  The composition (Z) of the supply gas is an index representing the gas composition and is the amount of permeated gas component / the amount of residual gas component. When this index (Z) is large, the partial pressure of the permeate gas component is small, so the discharge pressure (B) is small.

From the above-described conditions, the time required for the second process (T ₂ ) is related as shown in the following formula (2).
T ₂ ∝ (V × A) / (B × P × S) (2)

Further, the discharge pressure (B) is related as shown in the following formula (3).
Discharge pressure (B) ∝1 / (F × Z) (3)

Here, if the supply flow rate (F) of the mixed gas is large, the discharge pressure (B) is small. This means that if the supply flow rate (F) of the mixed gas is large, the filling pressure is reached sooner, so that the ratio of separation in the first process becomes small, and most of the separation is separated in the second process.
On the other hand, if the supply flow rate (F) of the mixed gas is small, the discharge pressure (B) increases. This is because the supply flow rate (F) of the mixed gas is small, and it is sufficiently separated in the first process and almost reaches the filling pressure with the residual gas component, so the filling pressure (A) and the discharge pressure (B) This means that the difference between is small.

For example, the membrane area 1114 cm ² (membrane performance: hydrogen permeation rate = 5 × 10 ⁻⁵ cm ³ (STP) / cm ² / sec / cmHg, (hydrogen / monosilane separation factor) = approximately shown in the examples described later. When a mixed gas of 10% monosilane and 90% hydrogen is charged at a charging pressure value of 0.2 MPaG into a sealed container having a carbon membrane unit of 5000) sufficiently dense, the discharge pressure is 0 in about 5 minutes. It will reach 12 MPaG.

(Third process)
Next, in the discharging process, which is the third process, when a predetermined time has elapsed from the start of the holding state, or the inside of the sealed container 6 (that is, the first space 11 and the third space 13 on the non-permeable side) is predetermined. When this pressure is reached, the on-off valve 5a of the non-permeate gas discharge port 5 is opened, and the mixed gas containing the hydride-based gas is discharged from the non-permeate gas discharge port 5 and recovered.
As a result, a mixed gas containing a hydride-based gas concentrated (purified) than the hydride-based gas concentration in the mixed gas supplied to the carbon membrane module 1 is obtained.

Here, when the inside of the sealed container 6 (that is, the first space 11 and the third space 13 on the non-permeate side) reaches a predetermined pressure, the supply pressure and the non-permeate pressure on the high pressure side are reduced. Indicates that it has stopped. That is, among the mixed gases supplied to the high pressure side, only the mixed gas containing the hydride-based gas that has been concentrated by passing through the carbon film 2a through all of the dilution gas is retained on the high pressure side.
Therefore, in the third process, it can be determined that the separation of the gas component having a small molecular diameter has been completed when the pressure drop on the non-permeate side in the sealed container 6 stops.

In the third process, the flow rate of the non-permeate gas increases simultaneously with the opening of the opening / closing valve 5a of the non-permeate gas discharge port 5. At the same time, the supply pressure and the non-permeation pressure of the first and third spaces 11 and 13 which are the non-transmission side space gradually decrease.
On the other hand, there is no change in the pressure (permeation pressure) in the second space 12, and the value of the permeate flow rate of the dilution gas from the permeate gas discharge port 4 is very small.

The time required for the third process (T ₃ ) is not particularly limited, and the volume (V), discharge pressure (B), and exhaust gas flow rate (also referred to as discharge flow rate, G) of the sealed container 6 is not limited. It can be selected as appropriate according to the conditions.
Here, the volume (V) of the sealed container 6 is as described in the first step.
The higher the discharge pressure (B), the longer the time required for the third process. This is because the amount of residual gas components is increasing.

  If the discharge flow rate (G) is large, the time required for the third process is shortened, but the carbon membrane unit 2 may be damaged. For this reason, the linear velocity is preferably supplied at 10 cm / sec or less, and more preferably at a linear velocity of 1 cm / sec or less. However, this is not the case when a resistance plate or a diffusion plate is introduced so that the gas flow does not directly hit the carbon film 2a.

When the required time (T ₃ ) of the third process is expressed from each condition described above, it is related as shown in the following formula (4).
T ₄ ∝ (V × B) / (G) (4)

For example, the membrane area 1114 cm ² (membrane performance: hydrogen permeation rate = 5 × 10 ⁻⁵ cm ³ (STP) / cm ² / sec / cmHg, (hydrogen / monosilane separation factor) = approximately shown in the examples described later. In the case of discharging from a discharge pressure of 0.12 MPaG to about 100 sccm into a sealed container having a sufficiently dense carbon membrane unit of 5000), the pressure reaches 0 MPaG in about 2 minutes.

(Fourth process)
Next, when a predetermined time has elapsed from the start of the recovery of the mixed gas containing the hydride-based gas, or the inside of the sealed container 6 (that is, the first space 11 and the third space 13 on the non-permeate side) is maintained at a predetermined pressure. When reaching, the open / close valve 5a of the non-permeate gas outlet 5 is closed. As a result, the state immediately before the start of the first process is restored.

In addition, when the required time (T) of the operation cycle in the operation method of the gas separation device of the present invention is expressed by the required time of each process described above, it can be expressed as the following formula (5).
T = T ₁ + T ₂ + T ₃ (5)

In the residual gas recovery method of the present embodiment, the carbon membrane module 1 is continuously repeated with an operation cycle composed of such separation operations (hereinafter referred to as “batch operation”) in the first to fourth steps (this is referred to as “batch operation”). This method is called “batch method”.
By such batch operation, the hydride gas having a large molecular diameter is concentrated and separated on the high pressure side (carbon membrane non-permeation side) of the carbon membrane unit 2 in the first and second processes, and in the third process. To be recovered. On the other hand, dilution gases such as hydrogen and helium having a small molecular diameter are continuously recovered in the first to fourth processes from the low-pressure side (carbon membrane permeation side) of the carbon membrane unit 2.

  By the way, in the residual gas recovery method of the first embodiment described above, for example, a mixed gas of 90% hydrogen with a small molecular diameter and 10% monosilane with a large molecular diameter is continuously supplied to a carbon membrane as a separation membrane. In the case (continuous gas separation method), the separation performance was about 100% hydrogen on the permeate side and about 60% monosilane (40% hydrogen) on the non-permeate side.

  In contrast, according to the residual gas recovery method of the present embodiment using a batch type gas separation method, hydrogen is approximately 100% on the permeate side and monosilane is approximately 90% or more on the non-permeate side (10% hydrogen). The separation operation can be performed with the following separation performance.

As described above, according to the residual gas recovery method of the present embodiment, the same effects as those of the first embodiment described above can be obtained.
Further, in this embodiment, since a configuration using a batch type gas separation method is used, it is possible to perform an operation with a sufficient separation performance with a smaller membrane area than in the first embodiment.

<Third Embodiment>
Next, a third embodiment to which the present invention is applied will be described. This embodiment has a configuration that is partially different from the residual gas recovery method of the first and second embodiments. About the collection | recovery apparatus and carbon membrane module which are used for collection | recovery of the residual gas of this embodiment, about the same component as 1st and 2nd embodiment, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  Whereas the recovery devices 31 and 32 of the first and second embodiments use the carbon membrane module alone, the recovery device 33 used in the residual gas recovery method of the present embodiment is shown in FIG. Thus, the difference is that a carbon membrane module unit 10 composed of two carbon membrane modules 1A and 1B is used. Further, the collection devices 31 and 32 of the first and second embodiments are connected to one cylinder 21, whereas the collection device 33 of the third embodiment is connected to two. ing.

  As shown in FIG. 6, the carbon membrane module used in the present embodiment is a carbon in which two carbon membrane modules 1A and 1B are connected in parallel by paths L1A to L4A and paths L1B to L4B branched from paths L1 to L4. The membrane module unit 10 is configured.

Next, the residual gas recovery method of the present embodiment using the recovery device 33 including the carbon membrane module unit 10 described above will be described.
In the residual gas recovery method of the present embodiment, first, among the carbon membrane modules connected in parallel, for example, the carbon membrane module 1A is operated by the first to fourth processes described in the second embodiment. Operate the cycle continuously.

Next, the other carbon membrane module 1B connected in parallel is operated in the same operation cycle shifted by a predetermined interval with respect to the operation cycle of the one carbon membrane module 1A.
Specifically, when two carbon membrane modules are connected in parallel, it is preferable to shift the phase of the operation cycle of the carbon membrane module 1B by ½ cycle with respect to the carbon membrane module 1A.
Further, when two carbon membrane modules are connected in parallel and the operation cycle is shifted by 1/2 period, in the above formula (5), T ₁ = 1 / 2T, that is, T ₁ = T ₂ + T The relationship of ₃ is preferable.

  When the mixed gas is supplied to the carbon membrane module unit 10 from the cylinder 21A first and the residual pressure in the cylinder 21A decreases, the mixed gas is continuously supplied to the carbon membrane module unit 10 by switching to the cylinder 21B. Can be supplied with. In addition, the cylinder 21A that has been collected can be removed and the next cylinder attached.

As described above, according to the residual gas recovery method of the present embodiment, the same effects as those of the second embodiment described above can be obtained.
Moreover, in this embodiment, since it becomes the structure using the carbon membrane module unit which connected two carbon membrane modules in parallel, it becomes possible to perform continuous isolation | separation operation as the collection | recovery apparatus 33 whole.

  The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the recovery device 33 of the above-described third embodiment, two carbon membrane modules are connected in parallel, but there is no particular limitation, and three or more carbon membrane modules may be connected in parallel. Good. Further, two or more carbon membrane modules may be connected in series to form a middle unit, and two or more carbon membrane modules may be connected in parallel.

When a plurality of carbon membrane modules are connected in parallel and a continuous separation operation is performed by a batch system, the time required for one cycle (T) is a value obtained by grading the time required for the first process (T ₁ ). The above integer value (N) is the number of required separation membrane modules.
N ≧ T / T ₁ (6)

When a plurality of carbon membrane modules are connected in parallel and a continuous separation operation is performed by a batch method, T ₁ = 1 / 2T may not be achieved.
In this case, since the time required for the third process (T ₃ ) is a time required for the process of recovering the mixed gas from the non-permeated gas discharge port, the gas separation membrane apparatus can perform a continuous separation operation by a batch method. By adding the adjustment time.

The adjustment time is determined as follows.
For example, when T ₁ = 3, T ₂ = 20, T ₃ = 5, and T = 28, N ≧ 9.333... From Equation (6), and the number of carbon membrane modules is 10.

When the first process is completed in the first carbon membrane module, the first process is sequentially started in the second, third,. One cycle after the first process starts in the last tenth carbon membrane module, one cycle of the first carbon membrane module ends. Since 10-th of the middle of the carbon membrane module is still the first step, the adjustment time to the first of T ₃ carbon membrane module (the waiting time) by providing 2 minutes, the gas separation membrane device batchwise Continuous separation operation can be performed.
Similarly to the first carbon membrane module, the second and subsequent carbon membrane modules also take adjustment time into account.

  When returning a used cylinder filled with a diluted mixed gas, it is generally returned as a residual gas with some gas left in the cylinder. When returned, the cylinder pressure (residual gas pressure) varies depending on the intended use of the diluted mixed gas, the diluted gas, and the type of gas to be diluted. Generally, the residual gas pressure is at most 1 MPaG, usually about 0.5 MPaG.

  In the residual gas recovery method of the present embodiment, the residual gas pressure itself becomes an operation pressure for separation by the separation membrane. For this reason, when the residual gas pressure is high, it is possible to perform separation very efficiently and separation with excellent separation performance. However, when the residual gas pressure decreases, it becomes difficult to perform separation efficiently, resulting in a decrease in separation performance.

If the continuous gas separation method and the batch type gas separation method are compared from the viewpoint of the residual gas pressure, the former is more influenced by the residual gas pressure than the latter. Although the latter has a considerable influence, maintaining the separation performance by increasing the proportion of the second step in the entire process (by increasing the time required for the second step to some extent). Can do.
Although the former is greatly affected, it is possible to maintain the separation performance as much as possible by reducing the flow rate of the supply gas (unpermeated gas) according to the decrease in the back pressure using the flow meter 9. is there.

  In the residual gas recovery method of the present invention, the temperature (operation temperature) for performing the above-described separation operation of the carbon membrane module is not particularly limited, and can be appropriately set according to the separation performance of the separation membrane. The operating temperature here assumes peripheral operation of the separation membrane module, and a temperature range of −20 ° C. to 120 ° C. is appropriate. When the operation temperature is increased, the permeate flow rate can be increased and the processing time of the batch operation can be shortened.

  In the residual gas recovery method of the present invention, the pressure (operating pressure) (on the high pressure side of the carbon membrane unit) is not particularly limited, and can be set as appropriate according to the separation performance of the separation membrane. Specifically, the pressure of the gas supplied to the carbon membrane module can be set to 1 MPaG or more if a support is used, and normally a pressure of about 0.5 MPaG is maintained. This support is a member that prevents the carbon film from being crushed. If the operation pressure is increased, the permeate flow rate can be increased, and the processing time of the batch operation can be shortened.

  In the second and third embodiments described above, in the carbon membrane module 1 shown in FIG. 4, the second space 12 on the low pressure side (permeation side) of the carbon membrane unit 2 is preferably evacuated. . Pulling the second space 12 to a vacuum also has the effect of increasing the pressure difference between the high-pressure side (non-permeation side) of the carbon membrane unit 2 and the low-pressure side (permeation side) of the carbon membrane unit 2. The pressure ratio between the high pressure side (non-permeation side) of the unit 2 and the low pressure side (permeation side) of the separation membrane unit 2 can be particularly increased. Note that both the pressure difference and the pressure ratio are preferably large for the separation performance by the separation membrane, but the pressure ratio affects the separation performance.

Further, in the carbon membrane module 1 shown in FIG. 4, flowing a sweeping gas to the low pressure side (permeation side) of the carbon membrane unit 2 can provide the same effect as evacuation. The open / close valve of the sweep gas supply port 8 is opened, and the sweep gas is supplied into the second space 12 at a predetermined flow rate.
The sweep gas is the same component as the permeate gas (that is, a diluted component of the mixed gas), so that the gas on the permeate side can be efficiently recovered. Further, a part of the permeated gas recovered from the permeated gas discharge port 4 may be used as the sweep gas.

  In the residual gas recovery method of the present invention, the mixed gas is supplied to the carbon membrane modules 1 and 20 as follows. For example, in the case of the hollow fiber as described above, a high-pressure gas is introduced into the hollow fiber-shaped separation membrane. Two patterns are conceivable: a case of supplying (core side supply) and a case of supplying high pressure gas around the hollow fiber-shaped separation membrane (outside supply), as shown in FIGS. The supply is preferred because it can be operated with improved separation performance.

  In the method for recovering residual gas of the present invention, in order to increase the gas throughput per one carbon membrane module 1, the membrane area is increased (in the case of a hollow fiber-like carbon membrane, the number is increased), the second space 12. There are ways to reduce the volume of In the latter case, it is necessary to devise the structure in the space or add a mixer in order to bring the gas and the separation membrane into sufficient contact.

  Specific examples are shown below. However, the present invention is not limited to the following examples.

( Reference Example 1)
Recovery of residual gas (continuous gas separation) was performed using the separation membrane module shown in FIG.

  The mixed gas was continuously supplied to the separation membrane module under the following conditions. Moreover, the gas composition of the non-permeation | transmission side and the permeation | transmission side was measured, respectively. In addition, the gas concentration (GC-TCD) provided with a thermal conductivity detector was used for the volume concentration measurement. The results are shown in Table 1.

(Separation membrane module)
-Hollow fiber carbon membrane tube-Total surface area of the tube: 1114 cm ²
・ Hold at 25 ℃ (mixed gas)
-Gas composition: Monosilane 10.3% by volume
: Hydrogen 89.7% by volume
(Operating conditions)
-Supply gas flow rate: about 150 sccm of the mixed gas
-Residual gas initial pressure: 0.2 MPaG
-Permeation pressure: -0.088MPaG (uses vacuum pump, vacuum generator, etc.)
・ Back pressure valve: Set to a value that is equal to or slightly lower than the pressure depending on the residual gas pressure.

As shown in FIG. 7, at the initial stage (0.2 MPaG) where the residual gas pressure is sufficiently high, the monosilane (SiH ₄ ) concentration in the non-permeated gas is about 60 vol. % Could be concentrated. On the other hand, when the residual gas pressure is 0.05 MPaG, the concentration of monosilane (SiH ₄ ) in the non-permeated gas is 30 vol. % Concentration.

(Example 2)
Using the separation membrane module shown in FIG. 4, the residual gas was recovered (batch type gas separation).

The mixed gas was supplied batchwise to the separation membrane module under the following conditions, and three cycles were performed. As a result, when the residual gas pressure (filling pressure) is 0.2 MPaG, the exhaust pressure is 0.12 MPaG, and the breakdown of the time required for one cycle is about 7 minutes for the first process (supply process) and the second process (separation). Process) It took about 5 minutes and the third process (discharge process) was about 2 minutes.
Further, when the residual gas pressure (filling pressure) is 0.05 MPaG, the discharge pressure is 0.02 MPaG, and the required time for one cycle is the first process (supply process) for about 2 minutes and the second process (separation process). The third process (discharge process) took about 1 minute for about 5 minutes.

  Moreover, the gas composition of the non-permeation | transmission side and the permeation | transmission side was measured, respectively. In addition, the gas concentration (GC-TCD) provided with a thermal conductivity detector was used for the volume concentration measurement. The results are shown in Table 1.

(Separation membrane module)
-Hollow fiber carbon membrane tube-Total surface area of the tube: 1114 cm ²
・ Hold at 25 ℃ (mixed gas)
-Gas composition: Monosilane 10.3% by volume
: Hydrogen 89.7% by volume
(Operating conditions)
-Supply gas flow rate: about 150 sccm of the mixed gas
-Residual gas initial pressure: 0.2 MPaG
-Permeation pressure: -0.088MPaG (uses vacuum pump, vacuum generator, etc.)
・ Back pressure valve: Set to a value that is equal to or slightly lower than the pressure depending on the residual gas pressure.
・ Exhaust gas flow rate: about 100 sccm or less

As shown in FIG. 8, when the residual gas pressure is sufficiently high (0.2 MPaG), the concentration of monosilane (SiH ₄ ) in the non-permeated gas is about 87.5 vol. % Could be concentrated. On the other hand, as shown in FIG. 9, when the residual gas pressure is approximately 0 (0.05 MPaG), the monosilane (SiH ₄ ) concentration in the non-permeated gas is 78.6 vol. % Concentration.

  The total time required was 14 minutes when the residual gas pressure was 0.2 MPaG and 8 minutes when the residual gas pressure was 0.05 MPaG.

  The recovered amount was 91.7 cc when the residual gas pressure was 0.2 MPaG, and 22 cc when the residual gas pressure was 0.05 MPaG.

As shown in Table 1, Reference Example 1 and Example 2 are compared. In Example 2 in which batch-type gas separation was performed, the monosilane concentration in the non-permeated gas composition could be greatly improved as compared with Reference Example 1 in which continuous gas separation was performed.

  In particular, even when the cylinder residual pressure decreased, the monosilane concentration in the non-permeated gas composition could be greatly increased with the batch system of Example 2.

  On the other hand, the total discharge flow rate (the total discharge amount × the monosilane concentration in the non-permeated gas) is small in Example 2. In order to maintain the total discharge amount, a plurality of separation membrane modules may be connected in parallel and separated and recovered. Although it takes time, it is possible to maintain the total discharge by continuously performing batch-type gas separation.

  The present invention relates to a method of operating a gas separation apparatus that can perform gas separation with high gas separation performance even with a small membrane area and a small number of separation membrane modules. In particular, it is very useful when separating a gas component having a large molecular diameter and a gas component having a small molecular diameter (hydrogen, helium, etc.).

1 (1A, 1B), 20 ... carbon membrane module (separation membrane module)
2. Carbon membrane unit (separation membrane unit)
2a: hollow fiber carbon membrane (gas separation membrane)
3 ... Gas supply port 3a ... Open / close valve 4 ... Permeate gas discharge port 4a ... Open / close valve 5 ... Non-permeate gas discharge port 5a ... Open / close valve 6 ... Sealed container 7 ... Resin wall 8 ... Sweep gas supply port 8a ... Open / close valve 9 ... Flow meter 10 ... Carbon membrane module unit 11 ... First space 12 ... Second space 13 ... Third spaces 14a, 14b, 14c ... Pressure gauge 15 ... Back pressure valve (pressure reducing valve)
31, 32, 33 ... recovery device

Claims (4)

Supply a mixed gas of a gas component having a large molecular diameter and a gas component having a small molecular diameter with a component concentration of 10% or more remaining in a used cylinder to a separation membrane module having a gas separation membrane having a molecular sieving action. after separating the mixed gas into a large gas component of the molecular diameters small gas component of the molecular diameter, the recovery of the residual gas in which the molecular diameter as small gas component of the molecule diameter to recover a large gas component respectively A method,
The gas component having a large molecular diameter is composed of any one or two or more of hydride gases composed of arsine, phosphine, hydrogen selenide, monosilane, monogermane,
The separation membrane module is
Close the non-permeate gas outlet provided in the sealed container containing the gas separation membrane so as to communicate with the space on the non-permeate side of the gas separation membrane, and communicate with the space on the permeate side of the gas separation membrane. In a state where the permeated gas discharge port provided is opened, the gas supply port is opened to supply a mixed gas containing a gas component having a small molecular diameter and a gas component having a large molecular diameter into the sealed container. A first process of charging,
When a predetermined time has elapsed from the start of the supply of the mixed gas or when the inside of the sealed container reaches a predetermined pressure, the gas supply port is closed to stop the supply of the mixed gas, and the state is maintained. The second process,
When a predetermined time has elapsed from the start of the holding state or when the inside of the sealed container has reached a predetermined pressure, the gas having a large molecular diameter is opened from the non-permeated gas discharge port. A third step of recovering the mixed gas containing the components;
When a predetermined time has elapsed from the start of the recovery or when the inside of the closed container reaches a predetermined pressure, an operation cycle consisting of a fourth process of closing the non-permeate gas outlet is continuously repeated. A residual gas recovery method for separating the gas characterized by the above and recovering the residual gas. Supply a mixed gas of a gas component having a large molecular diameter and a gas component having a small molecular diameter with a component concentration of 10% or more remaining in a used cylinder to a separation membrane module having a gas separation membrane having a molecular sieving action. after separating the mixed gas into a large gas component of the molecular diameters small gas component of the molecular diameter, the recovery of the residual gas in which the molecular diameter as small gas component of the molecule diameter to recover a large gas component respectively A method,
The gas component having a large molecular diameter is composed of any one or two or more of hydride gases composed of arsine, phosphine, hydrogen selenide, monosilane, monogermane,
Connecting two or more separation membrane modules in parallel;
One separation membrane module
Close the non-permeate gas outlet provided in the sealed container containing the gas separation membrane so as to communicate with the space on the non-permeate side of the gas separation membrane, and communicate with the space on the permeate side of the gas separation membrane. In a state where the permeated gas discharge port provided is opened, the gas supply port is opened to supply a mixed gas containing a gas component having a small molecular diameter and a gas component having a large molecular diameter into the sealed container. A first process of charging,
When a predetermined time has elapsed from the start of the supply of the mixed gas or when the inside of the sealed container reaches a predetermined pressure, the gas supply port is closed to stop the supply of the mixed gas, and the state is maintained. The second process,
When a predetermined time has elapsed from the start of the holding state or when the inside of the sealed container has reached a predetermined pressure, the gas having a large molecular diameter is opened from the non-permeated gas discharge port. A third step of recovering the mixed gas containing the components;
When a predetermined time has elapsed from the start of the recovery or when the inside of the sealed container reaches a predetermined pressure, an operation cycle consisting of a fourth process of closing the unpermeated gas discharge port is continuously repeated. Drive,
Other separation membrane module, one of the separation membrane the remaining gas of the gas, characterized in that the driving respectively the operating cycle operating cycle shifted by a predetermined interval to recover separated by residual gas module Collection method. The residual gas recovery method according to claim 1 or 2 , wherein the gas separation membrane is any one of a silica membrane, a zeolite membrane, and a carbon membrane. The method for recovering a residual gas according to any one of claims 1 to 3 , wherein the gas component having a small molecular diameter is one or a mixture of two or more of hydrogen and helium.

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