JPH0873201A - Hydrogen separating membrane unit - Google Patents

Abstract

PURPOSE: To improve strength, durability to repetitive use and hydrogen permeation performance by using metallic or allay foil provided with many recessed parts in hydrogen permeating parts of a hydrogen permeable membrane. CONSTITUTION: The hydrogen permeable membrane 1 formed with the recessed parts 3 in a square-meshed form is sandwiched by metallic frames 4 joined with supporting plates 2 consisting of perforated metallic plates and are joined by joining parts 5. The hydrogen permeable membrane l consists of Pd and alloys, such as Pd-Ag, Pd-Y, Pd-Ni and Pd-Cu and is so formed as to attain to >t2 =t3 -t1 when the film thickness is defined as 30 to 50μm(t3 )de, the depth of the recessed parts as t1 , the film thickness of the recessed parts as t2 and the film thickness by the conventional method as t0 . The pitch of the recessed parts 3 is determined by taking the ratio (30 to 90%) of the area of the recessed parts 3 to the area over the entire part of the hydrogen permeable membrane and the strength, etc., over the entire part of the membrane into consideration. The recessed parts 3 described above may be formed on any of the gaseous raw material side, refined hydrogen side and both sides of the hydrogen permeable membrane 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrogen separation membrane unit applied to a hydrogen refining device or a hydrogen producing device.

[0002]

2. Description of the Related Art FIG. 8 is a cross section of a conventional hydrogen separation membrane unit.
An example of the figure is shown. In the hydrogen separation membrane unit of FIG.
Metal porous material (wire mesh
Between the support plates 2 made of hydrogen (H₂) Only transparent
Hydrogen Permeation Made of Pd or Pd Alloy Foil with Properties
For sandwiching the membrane 1 and brazing, diffusion bonding, welding, etc. at the joint 5
Is more joined. At the time of operation, at high temperature, to the raw material gas side
Only hydrogen is selected by flowing a source gas containing hydrogen
Passing through the hydrogen permeable membrane from the source gas side to the purified hydrogen side
It diffuses and moves, and high-purity hydrogen is obtained on the purified hydrogen side.
The hydrogen permeation rate at this time is inversely proportional to the thickness t of the hydrogen permeable film.
For example, the thinner the membrane thickness t, the higher the hydrogen separation performance.
Is obtained. Also, the pressure P on the raw material gas side₁And purified hydrogen side
Pressure P₂Differential pressure with ΔP = P₁−P ₂Hydrogen is larger
The permeation rate is high and the performance is high.

[0003]

In the hydrogen separation membrane unit as shown in FIG. 8, the support plate 2 is joined to the frame 4 by welding. In the case of such a joining, as shown in FIG. 7 which is an enlarged view showing the state of the portion A in FIG. A step a is formed between the parallel surfaces. In addition, the surface of the support plate 2 formed of a perforated metal plate including a wire net has many irregularities. In such a hydrogen separation membrane unit,
If ΔP is increased and t is decreased in order to improve the hydrogen separation performance, the following problems occur. (1) There is a possibility that the hydrogen permeable film 1 may be broken due to local strain 6 at the step a. (2) The hydrogen permeable membrane 1 may be pressed against the support plate 2, and the recesses on the surface of the support plate may not fit into the support plate 2, and may receive large strain and break.

In view of the above-mentioned state of the art, the present invention is to provide a hydrogen separation membrane unit capable of preventing breakage of a hydrogen permeable membrane in the prior art.

[0005]

According to the present invention, (1) a hydrogen-permeable membrane made of a metal or alloy foil is fixed on both sides by a metal frame, and the hydrogen-permeable membrane has at least a purified hydrogen side. In a hydrogen separation membrane unit whose surface is supported by a supporting plate made of a metal porous material whose periphery is joined to the metal frame,
A hydrogen separation membrane unit comprising a metal or alloy foil hydrogen permeable membrane having a large number of depressions in the hydrogen permeable portion is used as the hydrogen permeable membrane, and (2) the depressions provided in the hydrogen permeable membrane are dimples. The hydrogen separation membrane unit according to (1) above, which is formed in a square shape or a grid shape.

In the hydrogen separation membrane unit of the present invention,
A hydrogen permeable membrane having a thickness of 30 to 50 μm is used instead of the hydrogen permeable membrane having a thickness of about 20 μm conventionally used in this type of hydrogen separation membrane unit. This increases the strength of the hydrogen permeable membrane, so that it is possible to prevent breakage due to local strain due to the step difference at the joint between the frame and the support plate, and it is possible to reduce the bite into the recess on the surface of the support plate. . Thickness is 3
If it is less than 0 μm, there is no effect of improving the strength, and if it exceeds 50 μm, it is difficult to process the recess thinly.

When the thickness of the hydrogen permeable membrane is increased in this way
Since the hydrogen permeability deteriorates, a large number of
A concave portion, that is, a thin film portion is provided to ensure hydrogen permeability.
To keep. Depth t of recess₁Is the film thickness of the part without the recess t
₃, The thickness of the recess is t₂, The film thickness in the conventional method
t₀And t₀> T₂= T₃-T₁So that
It is desirable to do. There is no particular limitation on the shape of the recess.
4 and the dimple-like film shown in FIG.
An appropriate shape may be used depending on the material, shape, and the like. hydrogen
Pitch of concave part of permeable membrane (l₁) Is hydrogen permeation in the area of the recess
Considering the ratio to the area of the entire surface and the strength of the entire film, etc.
It may be set appropriately. The metal support used as a support plate
The surface of the holding plate also has irregularities. Usually, the concave part of the metal perforated plate
The pitch is not clear, but the general trend is that
Chi (l₂) And l₂<L₁When it comes to hydrogen permeable membrane
May be easily damaged, so (l₁) Is a support plate
Pitch of surface recess (l ₂) Be smaller
Is desirable. Also, the area of the recess is the surface of the entire hydrogen permeable surface.
30 to 90% of the product. Hydrogen permeation below 30%
It is not good, and strength exceeds 90%, so strength is reduced.
No

The material of the hydrogen permeable membrane in the hydrogen separation membrane unit of the present invention is Pd, Pd-Ag, Pd-.
Pd alloy such as Y, Pd-Ni, Pd-Cu or P
It is also possible to use a ternary alloy in which the above-mentioned additional metal such as Ag is added in combination with d.

The recesses may be provided on either the raw material gas side or the purified hydrogen side of the hydrogen permeable membrane, or on both sides. Such a recess can be formed by a method such as etching after patterning.

In the hydrogen separation membrane unit of the present invention, a metal frame in which a supporting plate made of a metal porous material is bonded to both sides of a portion of the hydrogen permeable membrane around which the concave portion is provided and where the concave portion is not formed is joined. It is fixed by scissors, brazing, diffusion bonding or welding. The support plate on the side of the raw material gas may be omitted depending on the usage conditions. Further, the metal porous material referred to here includes a wire mesh shape or a non-woven cloth shape.

A cross-sectional view of an example of the hydrogen separation membrane unit of the present invention is shown in FIG. In FIG. 1, the hydrogen permeable membrane 1 in which the grid-shaped concave portions 3 are formed is sandwiched by the metal frame 4 to which the supporting plate 2 made of a porous metal material is joined, in the portion where the concave portions are not formed, and the joint portion 5 is formed. Are joined together. In this example, the recess is formed on the raw material gas side.

2 and 3 show other examples of the hydrogen separation membrane unit of the present invention. FIG. 2 shows an example in which the grid-shaped concave portions 3 of the hydrogen-permeable film 1 are formed on the purified hydrogen side. As a holding mode of the hydrogen permeable membrane 1, as shown in FIG. 1, a concave portion 3 is provided on the raw material gas side, the purified hydrogen side is flattened, and the surface thereof is supported by the support plate 2
Although it is desirable to hold it in contact with hydrogen, there is no difference in hydrogen permeation performance. FIG. 3 is an example in which the support plate 2 on the side of the source gas in the structure of FIG. 1 is omitted, but the hydrogen permeation performance and the membrane holding effect are the same.

[0013]

By using a hydrogen permeable membrane thicker than that conventionally used, the local portion shown in FIG. 7 can be seen as shown in FIG. 6 which is an enlarged view of portion B in FIG. 1 when used. The occurrence of the specific strain 6 is suppressed, and even if ΔP is increased, it becomes difficult to break. Further, by providing the concave portion in the hydrogen permeable portion, rigidity close to that of a hydrogen permeable film having a thickness corresponding to the thickness t ₃ of the convex portion can be obtained, and the thickness t _{1 of the} concave portion can be obtained.
Excellent hydrogen permeation performance close to that of a hydrogen permeable membrane having a thickness equivalent to

[0014]

The present invention will be described in more detail with reference to the following examples. A hydrogen separation membrane unit having the shape shown in FIG. 1 was produced and a performance evaluation test was conducted. First, the SUS316 frame 4 and SUS
Made of 316 with a thickness of 0.8 mm and an average hole diameter (concave pitch)
l ₂ is about 30 μm porous metal (average fiber diameter 1.5 μm
m, and a support plate 2 made of a non-woven fabric having an average pore diameter of 30 μm) was joined by welding. As shown in FIG. 4, a square having a side of 15 μm and a depth of 25 is provided between the frames 4 to which the support plates 2 are joined.
Approximately 120 mm x 70 m, which was bonded by sandwiching a hydrogen permeable membrane 1 made of a Pd-20 wt% Ag alloy pressure-sensitive foil having a thickness of 40 μm in which μm grid-shaped recesses were formed at a pitch of 25 μm.
A hydrogen separation membrane unit having a size of m was produced. In this example, the step corresponding to a in FIG. 6 was 20 μm.

The hydrogen permeable film having the recesses formed was manufactured as follows. That is, Pd-20w having a thickness of 40 μm
The t% Ag alloy pressure-sensitive foil is ultrasonically cleaned in an alkaline cleaning solution, dried in vacuum, and then a positive type resist material (TSMR8800 manufactured by Tokyo Ohka Co., Ltd.) is applied on both sides by a coater.
After heating and drying at 0 ° C for 30 minutes, pitch 25μm, side 15
After using a square mask of μm to expose one surface to ultraviolet rays, the resist material in a square portion having a side of 15 μm was removed in a resist stripping solution (NMD-W manufactured by Tokyo Ohka Kabushiki Kaisha). afterwards,
It was kept in hydrofluoric acid at 120 ° C. for 30 minutes to remove a square portion having a side of 15 μm by etching. As a result, the depth of the square recess was about 25 μm.

A hydrogen permeable membrane 1 having a thickness of 20 μm is used as a comparative sample.
A hydrogen separation membrane unit having the structure shown in FIG. 8 was produced in the same manner as described above except that a Pd-20 wt% Ag alloy coated foil of m was used.

The performance of the sample thus produced was evaluated by a foil breaking test and hydrogen permeation performance. First, regarding the breakage of the foil, the pressure difference ΔP = P ₁ −P ₂ = 9 kgf / c between the raw material side (P ₁ ) and the purified hydrogen side (P ₂ ) in Ar.
m ² (P ₂ is vacuum) 6 at a heating rate of 300 ° C./Hr
After heating to 00 ° C and holding for 30 minutes, cooling rate 300 ° C /
The history of lowering to room temperature with Hr was repeated. The hydrogen permeation performance was 9 kgf / cm ² differential pressure and 99% on the source gas side.
The hydrogen permeation rate was measured from the amount of hydrogen permeating to the purified hydrogen side at 550 ° C. using standard hydrogen gas containing hydrogen in an amount of at least%.

Table 1 shows the shapes of the samples used in the test and the results of the performance evaluation test. As can be seen from Table 1, in the breaking test, in the sample of the comparative example by the conventional method, the foil was broken at the ninth time and the pressure of P ₂ was increased. In contrast, the samples of the examples according to the present invention did not break even after being repeated 50 times. The hydrogen permeation rate is 180 cm ^{3 in the} comparative example.
/ Contrast is ^{(cm 2 · min · atm 0.} 5), in the embodiment of the present invention ^{230cm 3 / (cm 2 · min} · a
A high value of tm ^0.5 ) was obtained.

[0019]

[Table 1]

[0020]

As compared with the conventional hydrogen separation membrane unit, the hydrogen separation membrane unit of the present invention has remarkably improved strength, is remarkably excellent in resistance to repeated use for a long time, and has the same hydrogen permeation performance. That is all.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a hydrogen separation membrane unit of the present invention.

FIG. 2 is a cross-sectional view showing another example of the hydrogen separation membrane unit of the present invention.

FIG. 3 is a sectional view showing another example of the hydrogen separation membrane unit of the present invention.

FIG. 4 is an enlarged view showing an example of a grid-shaped concave portion of the hydrogen-permeable film according to the present invention.

FIG. 5 is an enlarged view showing an example of a dimple-shaped concave portion of the hydrogen-permeable film according to the present invention.

FIG. 6 is an enlarged view showing a state when the portion B in FIG. 1 is used.

FIG. 7 is an enlarged view showing a state when the portion A in FIG. 8 is used.

FIG. 8 is a sectional view showing an example of a conventional hydrogen separation membrane unit.

Claims (2)

[Claims] 1. A metal or alloy foil hydrogen permeable membrane is fixed from both sides by a metal frame, and at least the purified hydrogen side surface of the hydrogen permeable membrane is surrounded by the metal frame. In a hydrogen separation membrane unit supported by a support plate made of a bonded metal porous material, a hydrogen permeable membrane made of metal or alloy foil having a large number of recesses in the hydrogen permeable portion is used as the hydrogen permeable membrane. Characteristic hydrogen separation membrane unit. 2. The hydrogen-permeable film is provided with recesses formed in a dimple shape or a grid shape.
The hydrogen separation membrane unit according to 1.