JP2011245459A - Hydrogen purification apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a hydrogen purifying apparatus capable of increasing the amount of purified hydrogen taken out per unit time as compared with a conventional hydrogen refining apparatus without reducing the apparatus in hydrogen refining using a palladium alloy thin film and further reducing the thickness of the hydrogen separation membrane. In addition, the present invention provides a hydrogen refining apparatus in which the mechanical strength of the hydrogen separation membrane is less reduced.
SOLUTION: The inside of a cell is partitioned into a primary space and a secondary space by a plurality of palladium alloy thin tubes sealed at one end and a tube plate that supports the thin tube at the open end of the thin tube. Is a hydrogen purifier that introduces hydrogen from the primary side space, permeates the palladium alloy thin tube and takes out purified hydrogen from the secondary side space, the palladium alloy thin tube having an open end, a cylindrical center, and a closed end A hydrogen purifier having a cylindrical diameter larger than the cylindrical diameter at the position of the tube plate at the open end.
[Selection] Figure 1

Description

  The present invention relates to a hydrogen purifier utilizing the hydrogen gas selective permeability of a palladium alloy thin film.

Conventionally, high-purity hydrogen gas has been used in a large amount as an atmospheric gas in a semiconductor manufacturing process. Such a hydrogen gas is required to have an extremely low impurity concentration (ppb level or less) due to an improvement in semiconductor integration.
On the other hand, as a method for industrially producing a large amount of high-purity hydrogen, a reformed gas obtained by a steam reforming reaction from methanol, dimethyl ether, natural gas, liquefied petroleum gas, etc. is subjected to a cryogenic adsorption method or a pressure swing method. For example, a method of obtaining hydrogen by separating it into hydrogen and a gas other than hydrogen is known.

  The cryogenic adsorption method is a purification method in which a hydrogen-containing gas is circulated through an adsorption cylinder filled with an adsorbent that has been cryogenically cooled using liquefied nitrogen as a refrigerant to remove impurities other than hydrogen. This is a purification method in which a hydrogen-containing gas is sequentially circulated through the adsorption cylinder, and impurities other than hydrogen are removed by repeating the operations of pressure increase, impurity adsorption, impurity desorption, and adsorbent regeneration. The reformed gas as described above contains carbon monoxide, carbon dioxide, methane, nitrogen, water, etc. in addition to hydrogen. In the cryogenic adsorption method and the pressure swing method, these impurities are contained at a very low concentration ( It was difficult to remove until the ppb level or lower).

On the other hand, as a method for obtaining extremely high-purity hydrogen gas in a relatively small amount, a hydrogen-containing gas is supplied to a hydrogen separation membrane made of a palladium alloy thin film, and the selective permeability of hydrogen gas is utilized. A method is known in which only hydrogen is extracted by permeation.
Such an apparatus for purifying hydrogen includes a hydrogen-containing gas inlet, a purified hydrogen outlet, and a palladium alloy thin film in a gas flow path between the inlet and the outlet. For example, as shown in FIG. 4, a plurality of palladium alloy capillaries sealed at one end are supported by a tube plate at the open end and stored in the cell, and the cell is formed by the palladium alloy capillaries and the tube plate. This is a hydrogen purifier having a structure that is partitioned into two spaces, a primary space (hydrogen-containing gas supply space) and a secondary space (purified hydrogen extraction space).

JP-A-62-128903 JP-A-1-145302 JP-A-1-145303 JP-A-6-345409

Compared with the cryogenic adsorption method and the pressure swing method, the hydrogen purification method using a hydrogen separation membrane made of a palladium alloy thin film can produce high-purity hydrogen gas as described above, and the equipment can be downsized and simplified. There is an advantage that can be made. However, there are a disadvantage that the material of the separation membrane is expensive and a small amount of purified hydrogen taken out per unit time.
The hydrogen permeation amount Q per unit area of the hydrogen separation membrane is expressed by Q = At ⁻¹ (P ₁ ^1/2 −P ₂ ^1/2 ). (In the formula, A is a numerical value depending on the type of separation membrane, operating conditions, t is a film thickness, P ₁ is a primary hydrogen partial pressure, and P ₂ is a secondary hydrogen partial pressure.)

  If the film thickness t can be particularly reduced by the hydrogen permeation amount equation, it is possible to simultaneously reduce the material cost and increase the amount of purified hydrogen taken out. However, when the film thickness is reduced, the mechanical strength is lowered, and there are inconveniences that minute pinholes (usually 1 to 10 μm in diameter) are likely to be generated in the hydrogen separation membrane. When such a pinhole occurs, the primary side material (hydrogen-containing gas) easily leaks to the secondary side, so impurities are mixed into the extracted purified hydrogen, and the mechanical strength of the hydrogen separation membrane is further increased. The problem was that the hydrogen separation membrane would eventually be destroyed. In addition, due to such problems, it has been impossible to increase the amount of purified hydrogen taken out by increasing the difference between the hydrogen partial pressure on the primary side and the hydrogen partial pressure on the secondary side.

  Therefore, the problem to be solved by the present invention is to provide a hydrogen purifier capable of increasing the amount of purified hydrogen taken out per unit time in a hydrogen refining process using a palladium alloy thin film, without increasing the apparatus. An object of the present invention is to provide a hydrogen purification apparatus in which the mechanical strength of the hydrogen separation membrane is reduced little even if the thickness of the hydrogen separation membrane is reduced.

  As a result of diligent studies to solve these problems, the present inventors have found that a hydrogen purification apparatus using a plurality of palladium alloy thin tubes sealed at one end as a hydrogen separation membrane, the tube at the center of the palladium alloy thin tube By setting the diameter to be larger than the tube diameter at the position of the tube plate at the open end portion, there is no inconvenience when supporting the open end portion of the palladium alloy thin tube on the tube plate, so that per palladium alloy thin tube can be obtained. If the area of the hydrogen separation membrane can be increased and the diameter of the central portion of the palladium alloy thin tube as described above is made large enough to be in contact with the central portion of another thin tube adjacent to each other, a plurality of the thin tubes It was found that the mechanical strength can be improved by bundling the central portion, and the hydrogen purifier of the present invention has been reached.

  That is, in the present invention, the inside of the cell is partitioned into a primary side space and a secondary side space by a plurality of palladium alloy thin tubes sealed at one end and a tube plate that supports the thin tube at the open end of the thin tube, A hydrogen refining device that introduces hydrogen containing impurities from the primary side space, permeates the palladium alloy thin tube and takes out purified hydrogen from the secondary side space, and the palladium alloy thin tube has an open end, a cylindrical center, and a closed port. The hydrogen purifier is characterized in that it comprises an end, and the cylinder diameter at the center of the cylinder is larger than the cylinder diameter at the position of the tube plate at the open end.

  The hydrogen purification apparatus of the present invention uses a palladium alloy thin tube having a tube diameter at the center that is larger than the tube diameter of the tube plate at the open end. Compared with a palladium alloy thin tube, it is possible to increase the amount of purified hydrogen taken out per unit time. In addition, when a plurality of palladium alloy capillaries are bundled together at the center, the mechanical strength of the palladium alloy capillaries (hydrogen separation membrane) can be improved, or the palladium alloy capillaries (hydrogen separation membrane) can be made thin. it can.

  The hydrogen purifying apparatus of the present invention is configured such that the inside of a cell is partitioned into a primary side space and a secondary side space by a palladium alloy thin tube sealed at one end and a tube plate that supports the open end of the thin tube, and hydrogen containing impurities is separated into the primary side. It is applied to a hydrogen refining apparatus that introduces purified hydrogen from the secondary side space through a palladium alloy capillary tube. Moreover, as a raw material (hydrogen-containing gas) applied to the hydrogen purification apparatus of the present invention, a reformed gas obtained by a steam reforming reaction from methanol, dimethyl ether, natural gas, liquefied petroleum gas or the like, or an industrial cylinder or the like Relatively high-purity hydrogen or the like filled in The extremely high purity purified hydrogen obtained by the present invention is used as, for example, an atmospheric gas (carrier gas) in a semiconductor manufacturing process.

  Hereinafter, although the hydrogen purification apparatus of this invention is demonstrated in detail based on FIGS. 1-4, this invention is not limited by these. 1 is a block diagram showing an example of a vertical section of the hydrogen purifier of the present invention, and FIG. 2 is a block diagram showing an example of a horizontal section at the position of the tube plate of the hydrogen purifier of the present invention. FIG. 3 is a configuration diagram showing an example of a horizontal section at the position of the cylindrical central portion of the palladium alloy thin tube of the hydrogen purification apparatus of the present invention, and FIG. 4 is an example of a vertical section of a conventional hydrogen purification apparatus. FIG.

  As shown in FIG. 1, the hydrogen purifier of the present invention comprises a plurality of palladium alloy capillaries 1 sealed at one end, and a tube plate 5 that supports the capillaries at the open end 2 of the capillaries. Is a hydrogen purification apparatus that is partitioned into a primary side space and a secondary side space, introduces hydrogen containing impurities from the primary side space, permeates the palladium alloy thin tube 1 and takes out purified hydrogen from the secondary side space, The alloy thin tube 1 is composed of an open end 2, a cylindrical central portion 3, and a closed end 4, and the cylindrical diameter of the cylindrical central portion 3 is larger than the cylindrical diameter at the position of the tube plate of the open end 2. This is a hydrogen purifier.

  In the hydrogen purification apparatus of the present invention, the horizontal cross section at the position of the tube sheet is as shown in FIG. The thin tube 1 is supported by the tube plate 5 at the open end 2. The arrangement of the palladium alloy thin tubes 1 in the tube plate 5 is the same as that of a conventional hydrogen purifier. If the tube diameter a at the position of the tube plate at the opening end of the palladium alloy thin tube is too large, the tube diameter at the center of the cylinder of the palladium alloy thin tube also increases, and the mechanical strength of this portion decreases. Since it becomes difficult to manufacture and process the thin tube, it is usually set to 1.0 to 2.0 mm. Also, if the interval b between adjacent palladium alloy capillaries is too large, the number of palladium alloy capillaries decreases, so the amount of purified hydrogen taken out per unit time decreases, and if it is too small, the distance to the tube plate of the palladium alloy capillaries is reduced. Since attachment becomes difficult and support fixation becomes weak, it is usually set to 1.0 to 2.5 mm.

  The hydrogen purification apparatus of the present invention sets the interval b between adjacent palladium alloy capillaries at the position of the tubeplate to be relatively large so that the palladium alloy capillaries can be easily and firmly attached to the tubeplate, and the palladium alloy capillaries The cylinder diameter of one cylindrical central portion 3 is set to be large so as to increase the amount of purified hydrogen taken out per unit time. The thickness of the palladium alloy thin tube (hydrogen separation membrane) 1 is usually 70 μm or less, preferably 20 to 70 μm, and the tube diameter (average value) of the cylindrical central portion 3 is usually the tube plate at the open end of the thin tube. It is 1.05 to 2.0 times the cylinder diameter at the position. Moreover, the space | interval of the palladium alloy thin tubes in the position of a tube sheet becomes like this. Preferably it is 1.2-2.5 mm. The length of the palladium alloy thin tube is usually 200 to 2000 mm, and the cylindrical central portion 3 (portion where the tube diameter is constant) of the palladium alloy thin tube 1 is usually 70% or more, preferably 90% of the total length. It is said above. Moreover, the thickness of a tube sheet is 5-50 mm normally.

Further, in the hydrogen purification apparatus of the present invention, as shown in FIG. 3, the cylinder diameter of the cylindrical central portion of the palladium alloy thin tube is set to such an extent that it contacts the cylindrical central portion of the other adjacent thin tubes. The mechanical strength of the palladium alloy thin tube can be improved by using three or more palladium alloy thin tubes and bundling the periphery. By adopting such a configuration, it is possible to further reduce the thickness of the palladium alloy thin tube and increase the amount of purified hydrogen taken out per unit time. When the palladium alloy thin tubes are bundled, the thickness of the palladium alloy thin tubes can be reduced by about 30% as compared with the case where the palladium alloy thin tubes are not bundled.
In the present invention, usually 3 to 1000 palladium alloy capillaries are used in one hydrogen purifier. Even if there is one palladium alloy thin tube whose cylindrical diameter at the center of the cylinder is larger than the cylindrical diameter at the position of the tube plate at the open end, the hydrogen purification apparatus is included in the hydrogen purification apparatus of the present invention.

  Examples of the constituent component of the palladium alloy used in the present invention include an alloy mainly composed of palladium and copper, an alloy mainly composed of palladium and silver, and an alloy mainly composed of palladium, silver and gold. . When these alloys are used, an alloy of palladium 50 to 70 wt% and copper 30 to 50 wt%, an alloy of palladium 60 to 90 wt% and silver 10 to 40 wt%, palladium 60 to 80 wt%, silver 10 to 37 wt% and gold A 3-10 wt% alloy is preferred. The palladium alloy may contain other metals, but the metal is usually contained in an amount of 95 wt% or more, preferably 99 wt% or more.

  In the present invention, the processing method related to the open end of the palladium alloy thin tube and the central portion of the cylinder is not particularly limited. For example, the central axes of two elongated cylindrical shapes having different inner diameters are the same. By using a heat-resistant molding device having a continuous and continuous shape, a flat palladium alloy thin tube is inserted into the punched portion of the molding device in a heated state and molded. It can be processed into a desired shape. Alternatively, a heat-resistant molding device having a shape that penetrates the outer shape of the palladium alloy capillary having a desired shape in the present invention is used, and the palladium alloy capillary that has been sealed at one end is used for the above molding. After being inserted into the punched-out portion of the apparatus, it can be processed into a desired shape by blowing high pressure gas into the palladium alloy thin tube in a heated state. In such processing, the thickness of the palladium alloy thin tube can be reduced by up to about 50%.

  When purifying hydrogen using the hydrogen purifier of the present invention, a raw material gas (hydrogen-containing gas) is supplied from the inlet 6 to the primary side of the cell heated by the heater 10. The source gas comes into contact with the hydrogen separation membrane of the palladium alloy capillary tube, and only hydrogen is permeated to the secondary side of the cell and recovered from the purified hydrogen outlet 7. Further, the gas that does not permeate the hydrogen separation membrane of the palladium alloy thin tube is collected from the gas outlet 8 for a gas other than hydrogen. The larger the difference in hydrogen partial pressure between the cell primary side and the cell secondary side, the larger the hydrogen permeation amount per unit time. Therefore, in the present invention, the raw material gas (hydrogen-containing gas) is usually supplied at a pressure higher than atmospheric pressure so that the pressure on the cell secondary side becomes lower than atmospheric pressure.

  In the present invention, the hydrogen separation membrane during hydrogen purification has a higher hydrogen permeation amount per unit time as the temperature is higher, but is limited in terms of heat-resistant temperature. When the temperature is low, the hydrogen separation membrane absorbs a large amount of hydrogen, which may cause damage to the device due to expansion and deformation. Therefore, the temperature of the hydrogen separation membrane at the time of hydrogen purification is usually 250 to 500 ° C, preferably 300 to 450 ° C. In addition, it is preferable to heat the raw material gas (hydrogen-containing gas) to the above temperature in advance by a preheater or the like and then introduce it into the hydrogen purifier of the present invention.

  EXAMPLES Next, although an Example demonstrates this invention concretely, this invention is not limited by these.

Example 1
(Production of palladium alloy thin tubes)
A cylindrical punching portion with an outer diameter of 1.61 mm and a length of 20 mm and a cylindrical punching portion with an outer diameter of 1.81 mm and a length of 100 mm are passed through a punching portion of a gently inclined column base, A heat-resistant molding apparatus having a configuration in which these central axes are continuously connected so as to coincide with each other was manufactured. In addition, the other end of a flat palladium alloy thin tube (outer diameter 1.8 mm, thickness 70 μm, palladium, gold, and silver ternary alloy) that has been sealed at one end is heated. The tip was processed so as to be thinner than 1.6 mm.

  Next, after raising the punched-out portion of the molding apparatus to a predetermined temperature, this palladium alloy thin tube is heated and inserted into the large-diameter punched-out portion of the molding device from the tip of the thin tube, and the small diameter A part was pulled out from the exit of the punched-in part and molded. As a result, an opening end portion having an outer diameter of 1.6 mm and a length of 20 mm, an outer diameter of 1.8 mm, a length of 278 mm, and a central portion of a cylinder having a thickness of 70 μm (inclination having a diameter of 1.6 mm to 1.8 mm and a length of 10 mm) And a palladium alloy capillary having a closed end with a length of 2 mm was obtained.

(Production of hydrogen purification equipment)
After welding 35 palladium alloy capillaries manufactured as described above to a disc-shaped SUS316L tube plate having a diameter of 25 mm and a thickness of 15 mm on a plurality of concentric circles, an SUS316L cell having an inner diameter of 25 mm and a height of 400 mm is formed. The hydrogen purifier having the configuration as shown in FIGS. 1 and 2 was produced. In addition, the space | interval of adjacent palladium alloy thin tubes in the position of a tube sheet was 1.2 mm-1.5 mm. Moreover, the space | interval of palladium alloy thin tubes in a cylindrical center part was 0.8 mm-1.1 mm.

(Hydrogen purification test)
The temperature in the cell was raised to 600 ° C. and hydrogen was introduced, and heat treatment was performed for 10 hours. Subsequently, the temperature is lowered to 420 ° C., and hydrogen containing about 500 ppm of impurities (nitrogen, oxygen, carbon dioxide, etc.) is primary while controlling the differential pressure between the primary side space and the secondary side space to be 1.0 MPa. Hydrogen was purified by introducing from the side space. As a result, 850 L (liter) of purified hydrogen was obtained after treatment for 1 hour.

(Example 2)
By repeatedly processing a palladium alloy thin tube made of the same material as in Example 1, an open end with an outer diameter of 1.6 mm, a length of 20 mm, an outer diameter of 2.8 mm, a length of 278 mm, and a thickness of 50 μm in the center of the cylinder A palladium alloy thin tube comprising a part (including an inclined part having a diameter of 1.6 mm to 1.8 mm and a length of 20 mm) and a closed end part having a length of 2 mm was obtained.
A 37 SUS316L cell having an inner diameter of 25 mm and a height of 400 mm was formed by closely bonding and welding 37 palladium alloy thin tubes manufactured as described above to the same tube plate as in Example 1 at the center of the cylinder of the thin tube. The hydrogen purifier having a horizontal cross section at the position of the cylindrical central portion of the palladium alloy thin tube as shown in FIG. 3 was manufactured. In addition, the space | interval of adjacent palladium alloy thin tubes in the position of a tube sheet was 1.2 mm.
Subsequently, a hydrogen purification test was conducted in the same manner as in Example 1. As a result, 2000 L (liter) of purified hydrogen was obtained after 1 hour of treatment.

(Comparative Example 1)
Other than using 35 conventional flat palladium alloy capillaries (outer diameter 1.6mm, total length 300mm, thickness 70μm, palladium, gold, and silver ternary alloy) sealed at one end In the same manner as in Example 1, a hydrogen purification apparatus having a configuration as shown in FIG. 4 was produced. In addition, the space | interval of adjacent palladium alloy thin tubes in the position of a tube sheet was 1.2 mm-1.5 mm, and the space | interval of palladium alloy thin tubes in a cylindrical center part was also 1.2 mm-1.5 mm.
Subsequently, a hydrogen purification test was performed in the same manner as in Example 1. As a result, 770 L (liter) of purified hydrogen was obtained after 1 hour of treatment.

  As described above, the hydrogen purification apparatus of the present invention has a large hydrogen separation membrane area at the center of the palladium alloy thin tube, and the amount of purified hydrogen taken out per unit time is increased compared to the conventional flat palladium alloy thin tube. Can be made. In addition, by mechanically bundling a plurality of palladium alloy capillaries at the center thereof, the mechanical strength is improved, and the palladium alloy capillaries (hydrogen separation membrane) can be made thinner.

The block diagram which shows an example of the cross section of the perpendicular direction of the hydrogen purification apparatus of this invention The block diagram which shows an example of the cross section of the horizontal direction in the position of the tube sheet of the hydrogen purification apparatus of this invention The block diagram which shows an example of the cross section of the horizontal direction in the position of the cylindrical center part of the palladium alloy thin tube of the hydrogen purification apparatus of this invention The block diagram which shows an example of the cross section of the perpendicular direction of the conventional hydrogen purification apparatus

DESCRIPTION OF SYMBOLS 1 Palladium alloy thin tube 2 Open end part 3 Cylindrical center part 4 Closed end part 5 Tube plate 6 Raw material gas inlet 7 Purified hydrogen outlet 8 Non-hydrogen gas outlet 9 Cell side wall 10 Heater

Claims (5)

  The inside of the cell is partitioned into a primary side space and a secondary side space by a plurality of palladium alloy capillaries sealed at one end and a tube plate supporting the capillaries at the open end of the capillaries. A hydrogen purification apparatus that introduces from the primary side space, permeates the palladium alloy thin tube and takes out purified hydrogen from the secondary side space, the palladium alloy thin tube comprising an open end, a cylindrical central portion, and a closed end, A hydrogen purifier characterized in that the cylinder diameter at the center of the cylinder is larger than the cylinder diameter at the position of the tube plate at the open end.   2. The hydrogen purifier according to claim 1, wherein the cylindrical diameter of the central portion of the palladium alloy thin tube is 1.05 to 2.0 times the cylindrical diameter at the position of the tube plate at the open end.   The hydrogen purifier according to claim 1, wherein three or more palladium alloy thin tubes are used and are bundled most closely in a cylindrical central portion of the thin tube.   The hydrogen purifier according to claim 1, wherein the primary space is outside the palladium alloy thin tube.   The hydrogen purifier according to claim 1, wherein the alloy film of the palladium alloy thin tube has a thickness of 70 μm or less.

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