JP2014084250A - Hydrogen purifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydrogen purifier capable, on an occasion for purifying hydrogen by using a palladium alloy film, of unprecedentedly increasing the takeout yield of purified hydrogen per unit time without entailing apparatus enlargement and a hydrogen purifier accompanied, even if the thickness of a palladium alloy film is reduced, by scarce mechanical strength losses of hydrogen-permeable capillaries.SOLUTION: The provided hydrogen purifier is a hydrogen purifier of which the interior of a cell is compartmentalized into a primary space and a secondary space by multiple hydrogen-permeable capillaries each having one sealed terminal and a tubular plate supporting the capillaries on the open terminal side of the capillaries, in which a hydrogen gas including impurities is introduced into the primary space and permeated through the capillaries, and in which a purified hydrogen gas is retrieved from the secondary space; the capillary is a metallic pipe having one sealed terminal and possessing multiple holes on its profile plane and is laser-welded with a palladium alloy film wrapped around the profile plane.

Description

  The present invention relates to a hydrogen purifier incorporating a hydrogen permeable thin tube utilizing the hydrogen gas selective permeability of a palladium alloy membrane.

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 (hydrogen permeable capillaries), which are sealed at one end, are supported by a tube plate at the open end portion and accommodated in a cell. The hydrogen purifier has a configuration in which the inside of the cell is partitioned into two spaces, a primary side space (hydrogen-containing gas supply side space) and a secondary side space (purified hydrogen take-out side space) by a tube plate.

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 purification using a palladium alloy membrane without increasing the apparatus, and further palladium. An object of the present invention is to provide a hydrogen purification apparatus in which the mechanical strength of a hydrogen-permeable capillary tube is little reduced even when the thickness of the alloy film is reduced.

  As a result of intensive studies to solve these problems, the present inventors have found that a palladium alloy film is attached to the side surface portion of a metal pipe sealed at one end and having a plurality of holes on the side surface, and the periphery is laser welded. In addition, it is possible to weld a palladium alloy film that is precise and less distorted on the surface of a metal pipe, and in the hydrogen purification apparatus using a plurality of hydrogen permeable capillaries sealed at one end, the aforementioned tubules are used as hydrogen permeable capillaries. Thus, it was found that even if the thickness of the palladium alloy film was reduced, a decrease in the mechanical strength of the hydrogen permeable capillary tube against the hydrogen partial pressure or the like could be suppressed, and the hydrogen purifier of the present invention was reached.

  That is, in the present invention, the inside of the cell is partitioned into a primary space and a secondary space by a plurality of hydrogen permeable capillaries sealed at one end and a tube plate that supports the capillaries at the open end of the capillaries, A hydrogen refining apparatus for introducing hydrogen containing impurities from a primary side space, allowing the fine tube to permeate and taking out purified hydrogen from the secondary side space, wherein the thin tube is sealed at one end and has a plurality of holes on the side surface A hydrogen purifier characterized in that a palladium alloy film is applied to the side surface of a pipe and laser-welded.

  The hydrogen purification apparatus of the present invention uses a hydrogen permeable thin tube formed by laser welding a palladium alloy film on the side surface of a metal pipe, which can suppress a decrease in mechanical strength, and therefore uses a palladium alloy film thinner than a conventional palladium alloy film. And the amount of purified hydrogen taken out per unit time can be increased.

  The hydrogen purifying apparatus of the present invention includes a hydrogen permeable thin tube sealed at one end and a tube plate supporting the open end of the thin tube, the inside of the cell is partitioned into a primary side space and a secondary side space, and hydrogen containing impurities is separated into the primary side. The present invention is applied to a hydrogen refining apparatus that introduces purified hydrogen from a secondary side space through a hydrogen permeation 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. 1-6, 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. 3 is a block diagram showing an example of a metal pipe used in the present invention, FIG. 4 is a block diagram showing an example of a laser welded portion in the metal pipe, and FIG. 5 is a diagram when a palladium alloy film is applied to the side surface of the metal pipe. FIG. 6 is a configuration diagram showing an example of a laser welding apparatus used in the present invention.

  As shown in FIG. 1, the hydrogen purifier of the present invention comprises a plurality of hydrogen-permeable tubules 1 sealed at one end, and a tube plate 7 that supports the tubules at the open end 6 of the tubules. Is a hydrogen purification device that is partitioned into a primary side space 8 and a secondary side space 9, introduces hydrogen containing impurities from the primary side space 8, passes through the thin tube 1 and takes out purified hydrogen from the secondary side space 9. As shown in FIGS. 3 to 5, the narrow tube 1 is laser-welded with a palladium alloy film 4 attached to the side surface of a metal pipe 3 sealed at one end and having a plurality of holes 2 on the side surface. This is a hydrogen purifier.

  The outer diameter of the metal pipe used in the present invention is usually 1.5 to 20 mm, preferably 1.5 to 10 mm. Moreover, the length of a metal pipe is 50-2000 mm normally, Preferably it is 100-1000 mm. The constituent material of the metal pipe is not particularly limited as long as welding with a palladium alloy is possible. For example, carbon steel, manganese steel, chromium steel, molybdenum steel, stainless steel, nickel steel, and nickel ( Among them, nickel steel (including 95 to 99 wt% nickel) or nickel is preferable in terms of good weldability with a palladium alloy.

  The shape of the hole in the metal pipe is usually a square, a rectangle, a circle, an ellipse, or a similar shape. When the shape of the hole of the metal pipe is square or rectangular, one side is usually 0.05 to 3 mm, preferably one side is 0.1 to 1 mm, and the shape of the hole is circular or elliptical. In this case, the diameter is usually 0.05 to 3 mm, preferably 0.1 to 1 mm. When the hole size of the metal pipe is less than the above lower limit value, there is a risk of pressure loss during hydrogen purification, and when the hole size exceeds the above upper limit value, a palladium alloy may be used during hydrogen purification. There is a possibility that the film is distorted and the mechanical strength is lowered. In addition, when satisfy | filling the said conditions, a pipe made from a sintered metal can be used. In the present invention, the number of holes, the size, and the interval between the holes are set so that the area ratio of the ventilation surface to the entire side surface of the metal pipe is usually about 50 to 80%. When the area ratio of the ventilation surface is less than 50%, the hydrogen permeation flow rate decreases, and when the area ratio of the ventilation surface exceeds 80%, the mechanical strength of the hydrogen permeable capillary tube decreases.

  Moreover, the film thickness of the palladium alloy film used in the present invention is usually 10 to 50 μm, preferably 12 to 30 μm. Examples of the constituent component of the alloy of the palladium alloy film 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.

  As shown in FIG. 5, the palladium alloy film is formed by attaching a palladium alloy film to the side surface of a metal pipe and temporarily fixing it with an adhesive or the like, for example, and then attaching a laser emitting unit 16 as shown in FIG. It welds with the laser welding apparatus which has. In this laser welding apparatus, the metal pipe 15 to which the palladium alloy film is attached can be fixed by the thin tube holder 17 movable in the central axis direction, and the metal pipe can be rotated by the rotation motor 18. Device. With such an apparatus, laser welding can be easily performed on the upper part of the line parallel to the central axis on the side surface of the metal pipe and the upper part of the circumferential line on the side surface of the metal pipe. The welds are linear, but when a large number of welds are provided, the welds adjacent to each other are preferably parallel and equally spaced. The laser welding location is not particularly limited as long as it is a portion without a hole, but as shown in FIG. 4, at least a welded portion 5 provided on the upper portion of the line parallel to the central axis of the side surface of the metal pipe, Then, laser welding is performed on the circumferential line upper part 5 'on the side surfaces of both ends of the metal pipe. In that case, it is preferable that the welding part 5 is provided in the range of the overlapping part of a palladium alloy film. The hydrogen-permeable tubule thus manufactured is attached to the tube plate in the form as shown in FIGS.

  Examples of the laser used in the present invention include a carbon dioxide gas laser and a YAG (yttrium / aluminum / garnet) laser, and a YAG laser is preferably used. Moreover, in order to avoid that a welding part becomes high temperature during laser welding, it is preferable that it is a pulsed laser. The welding heat input to the hydrogen permeable thin tube during laser welding is usually 0.05 to 0.5 J (joule) / pulse, preferably 0.1 to 0.3 J / pulse. The amount of heat input is not limited. The welding heat input per unit weld line is usually 0.5 to 20 J / mm, preferably 1 to 10 J / mm, but is not limited to such welding heat input. Furthermore, the shape of the laser welding irradiation spot is a circle, a quadrangle, etc., and the size is usually about 0.1 to 1 mm. When a pulsed laser is used, it is usually 10 to 200 pulses / second.

  When purifying hydrogen using the hydrogen purifier of the present invention, a source gas (hydrogen-containing gas) is supplied from the inlet 10 to the primary side of the cell heated by the heater 14. The source gas comes into contact with the palladium alloy membrane of the hydrogen permeable capillary tube 1, and only hydrogen is permeated to the secondary side of the cell and recovered from the purified hydrogen outlet 11. Further, the gas that does not permeate the palladium alloy membrane of the hydrogen permeable thin tube is recovered from the gas outlet 12 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, it is preferable to supply the source gas (hydrogen-containing gas) at a pressure higher than atmospheric pressure, and to set the pressure on the cell secondary side to a pressure 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 palladium alloy membrane during the 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 hydrogen permeation tubules)
The side surface of a grid-like pipe (outer diameter: 3.0 mm, length: 245 mm, thickness: 0.1 mm) made of nickel (purity 99% or more) having one end sealed and a plurality of square holes of 1.0 mm on one side Next, after plating a 20 μm-thick palladium alloy film (made of a ternary alloy of palladium, silver, and gold) as shown in FIG. 5, a laser welding apparatus as shown in FIG. Welding is performed by emitting a YAG laser at a line upper portion 5 parallel to the central axis on the side surface and a circumferential line upper portion 5 'on the side surface of the metal pipe, and the area ratio of the ventilation surface to the entire side surface of the metal pipe is approximately A 70% hydrogen permeation tubule was produced. Welding was avoided at locations with holes, and welding to the upper part 5 'of the circumferential line was performed on the overlapping portion of the palladium alloy film. When the obtained hydrogen permeation thin tube was visually inspected, defects such as scratches, dents and pinholes were not confirmed, and abnormalities such as burning due to welding were not confirmed. Further, the mechanical strength was sufficient.

(Production of hydrogen purification equipment)
Next, a nickel tube plate having a disc shape with a diameter of 50 mm and a thickness of 5 mm, and having 35 through-holes with a diameter of 3.1 mm provided on a flat plate portion excluding the peripheral portion on a plurality of concentric circles at equal intervals. In addition, after welding the 35 hydrogen-permeable tubules manufactured as described above, a raw material gas inlet, a purified hydrogen outlet, a gas outlet other than hydrogen, and a heater are provided, and the inner diameter is 50 mm and the height is 400 mm. In a cell made of SUS316L, a hydrogen purifier having a configuration as shown in FIGS. 1 and 2 was manufactured.

(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 impurities (nitrogen, oxygen, carbon dioxide, etc.) are reduced while controlling the pressure in the primary space to 0.6 MPaG and the pressure in the secondary space to 0.2 MPaG. As a result of introducing hydrogen containing 500 ppm from the primary side space and purifying the hydrogen, 0.85 Nm ³ / hr of purified hydrogen was obtained. During this time, impurities were measured by sampling hydrogen from the purified hydrogen outlet, but no impurities were detected.

(Example 2)
In the production of the hydrogen permeable thin tube of Example 1, a stainless steel pipe (outer diameter 3.0 mm, length 245 mm, thickness 0.1 mm) having a plurality of circular holes with a diameter of 0.5 mm was used as a metal pipe. Other than that, a hydrogen permeation capillary similar to that of Example 1 was manufactured. The area ratio of the ventilation surface to the entire side surface of the metal pipe was about 50%. A hydrogen purification apparatus was manufactured in the same manner as in Example 1 except that 35 hydrogen permeable capillaries were used, and a hydrogen purification test was conducted in the same manner as in Example 1. As a result, 0.66 Nm ³ / hr of purified hydrogen was obtained. Obtained.

(Comparative Example 1)
A hydrogen permeable thin tube (thick tube made of a palladium alloy film having the same composition as in Example 1) having an outer diameter of 3.0 mm and a length of 245 mm and having a film thickness sealed at 70 μm was manufactured. A hydrogen purification apparatus was manufactured in the same manner as in Example 1 except that 35 hydrogen permeable capillaries were used, and a hydrogen purification test was conducted in the same manner as in Example 1. As a result, 0.41 Nm ³ / hr of purified hydrogen was obtained. Obtained.

  As described above, the hydrogen purifier of the example of the present invention can increase the amount of purified hydrogen taken out per unit time as compared with the hydrogen purifier of the comparative example.

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 metal pipe used in this invention Configuration diagram showing an example of a laser weld in a metal pipe The perspective view which shows an example of the aspect at the time of soldering a palladium alloy film on the side part of a metal pipe Configuration diagram showing an example of a laser welding apparatus used in the present invention

DESCRIPTION OF SYMBOLS 1 Hydrogen permeation thin tube 2 Hole 3 Metal pipe 4 Palladium alloy film 5 Welding part provided in the upper part of the line parallel to the central axis of the side surface of metal pipe 5 'Welding part provided in the upper part of the circumferential line of the side surface of metal pipe 6 Open end 7 Tube plate 8 Primary side space 9 Secondary side space 10 Source gas inlet 11 Purified hydrogen outlet 12 Gas outlet other than hydrogen 13 Cell side wall 14 Heater 15 Palladium alloy film was plated Metal pipe 16 Laser emission unit 17 Narrow tube holder 18 Motor for rotation 19 Bearing part

Claims (7)

  The inside of the cell is partitioned into a primary side space and a secondary side space by a plurality of hydrogen permeable capillaries sealed at one end and a tube plate that supports the capillaries at the open end of the capillaries, so that hydrogen containing impurities can be separated. A hydrogen purification apparatus that is introduced from a primary side space, passes through the thin tube and takes out purified hydrogen from the secondary side space, wherein the thin tube is sealed at one end and has a plurality of holes on the side surface. Further, a hydrogen purification apparatus characterized in that a palladium alloy film is applied and laser-welded.   The hydrogen purifier according to claim 1, wherein the metal pipe is made of nickel.   The hydrogen purifier according to claim 1, wherein the hole of the metal pipe is a square or a rectangle having a side of 0.05 to 3 mm.   The hydrogen purifier according to claim 1, wherein the hole of the metal pipe has a circular or elliptical shape having a diameter of 0.05 to 3 mm.   The hydrogen purifier according to claim 1, wherein laser welding is performed on an upper portion of the line parallel to the central axis on the side surface of the metal pipe and an upper portion of the circumferential line on the side surface of the metal pipe.   The hydrogen purifier according to claim 5, wherein the laser welded portion provided on the upper part of the line parallel to the central axis of the side surface of the metal pipe is an overlapping portion of palladium alloy films.   The hydrogen purifier according to claim 1, wherein the palladium alloy film has a thickness of 10 to 50 μm.

Images