JP2005144362A - Hydrogen separator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that the flow in the through-holes formed to a porous body turns into a laminar flow and boundary layers are formed on the surfaces of metal plating layers to lower hydrogen permeability. <P>SOLUTION: The porous body 12 is constituted so as to be divided into a plurality of porous bodies in the gas flow directions of the through-holes 13 and stepped parts 14 are formed between the joining surfaces of the respective through-holes of the adjacent porous bodies. Since the stepped parts are formed between the through-holes of the respective joining parts of a plurality of of the porous bodies, turbulence is caused at the time of the flow of gas through the stepped parts to prevent the formation of the boundary layers. Accordingly, the concentration of the hydrogen mixed gas flowing through the through-holes becomes uniform to increase a hydrogen permeation rate. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a hydrogen separator that diffuses and separates hydrogen from a hydrogen mixed gas using a metal having hydrogen separation ability.

  A conventional hydrogen separator as shown in Patent Document 1 is known. This hydrogen separator has a configuration in which a surface of a porous substrate having a large number of through-holes is coated with a metal having hydrogen separation ability such as Pd by chemical plating.

For example, by passing a hydrogen mixed gas generated by reforming from a hydrocarbon-based fuel through this hydrogen separator, hydrogen is absorbed by the metal plating layer on the substrate surface and separated from other gas components.
JP-A-8-38863

  In the conventional hydrogen separator, the through hole formed in the porous substrate has a right cylindrical wall shape. For this reason, the flow in the through-hole at the time of gas supply becomes a laminar flow, a boundary layer is formed on the surface of the metal plating layer, and a large concentration gradient is generated. This means that the hydrogen partial pressure decreases, and as a result, the hydrogen permeability decreases.

  In this invention, the hydrogen separator which coat | covered the metal which has hydrogen separation ability on the surface of the through-hole formed in the porous body is comprised. However, the porous body is divided into a plurality of parts in the gas flow direction of the through holes, and a step is formed between the joint surfaces of the through holes of the adjacent porous bodies.

  According to the present invention, since the step is formed between the through holes at each joint portion of the plurality of porous bodies, turbulence occurs when the gas flows through the step portion, and a boundary layer is formed. Disappear. For this reason, the concentration of the hydrogen mixed gas flowing in the through hole becomes uniform, and the hydrogen permeation rate is improved.

  In the present invention, since a plurality of porous bodies are joined in the gas flow direction, through holes having a complicated shape including a stepped portion are easily formed depending on the combination of the porous bodies and the setting of the cross-sectional shape. be able to.

Hereinafter, some embodiments of the present invention will be described with reference to the drawings. The same parts are denoted by the same reference numerals in each embodiment.
(First embodiment)
1-1 to 2-4 show the first embodiment. As shown in FIG. 1, the hydrogen separator 11 of this embodiment is composed of three cylindrical porous bodies 12 connected in the axial direction (gas flow direction). Each porous body 12 is formed from a ceramic material such as alumina or silica. Each porous body 12 has a large number of through holes 13 penetrating between both end faces. Each through-hole 13 is formed in a right cylindrical surface parallel to the gas flow direction.

  Each of the porous bodies 12 has the same cross section and outer diameter, but as shown in FIG. 1-2, a pair of adjacent porous bodies 12 are arranged at a predetermined angle around the center line. By shifting and joining so that the opening cross section of each through-hole 13 may overlap partially, the level | step difference 14 (refer FIG. 2-2) is formed between the adjacent through-holes 13 in the said junction part. is there.

  FIGS. 2-2 to 2-4 show the manufacturing procedure of the hydrogen separator 11. First, as described above, the three porous bodies 12 before firing are arranged in the axial direction with an angle set so that the positions of the through holes 13 are shifted between adjacent porous bodies 12 (FIG. 2-2). Next, they are baked and joined together with pressure applied from both ends (FIGS. 2-3). Next, a metal having hydrogen separation ability such as Pd, V, Nb, and Ta is chemically plated on the end face of each joined porous body 12 and the inner surface of the through hole 13 to form a hydrogen separation membrane 15 (FIG. 2-4). . Since the step 14 is difficult to be plated, the hydrogen separation membrane 15 may be formed on the porous body 12 in advance before bonding.

By passing the mixed gas containing hydrogen through the through-hole 13 of the hydrogen separator 11 formed in this way, the flow is disturbed at the step 14 of the through-hole 13, so that the partial pressure is reduced due to the concentration gradient. The hydrogen permeability coefficient can be increased by suppressing
(Second Embodiment)
FIG. 3 and FIGS. 3-1 to 3-4 show a second embodiment. The difference from the first embodiment will be described. In this embodiment, as shown in the figure, the through hole 13 is formed in a tapered shape whose inner diameter gradually changes in the gas flow direction.

  Since the through holes 13 are tapered, in this embodiment, the porous bodies 12 adjacent to each other are joined so that the positions on the cross sections of the respective through holes 13 coincide with each other, and the adjacent through holes 13 on the joint surfaces are joined. The step 14 is formed by the difference in inner diameter.

  The manufacturing procedure of the hydrogen separator 11 is the same as that of the first embodiment. FIGS. 3-2 to 3-4 correspond to the steps of FIGS. 2-2 to 2-4, respectively.

  According to this embodiment, since the through-hole 13 is tapered, when the hydrogen mixed gas flows through the through-hole 13, not only the step 14 but also the middle portion of the through-hole 13 is disturbed by the change in inner diameter. Therefore, the uniform hydrogen concentration is further promoted.

Further, in this embodiment, when the gas flow direction is a flow from the left to the right in the drawing, the through hole 13 is set to gradually expand in diameter toward the downstream side. This is because the hydrogen permeation amount tends to decrease in the downstream region of the hydrogen separator, so that the wall thickness of the porous body 12 can be reduced while the inner diameter of the through-hole 13 is increased to increase the surface area of the hydrogen separation membrane 15. This makes it possible to secure a required hydrogen permeation amount even in a low hydrogen concentration state. However, the effect of turbulence can be expected even when gas is flowed in the opposite direction.
(Third embodiment)
FIG. 4 shows a third embodiment. As shown in the figure, the through holes 13 are formed at the same position in the cross section in each of the three porous bodies 12, but the inner diameter is set to be larger toward the downstream side. A joint portion where the inner diameter of each through-hole 13 changes becomes a step 14.

According to this embodiment, the same functions and effects as those of the second embodiment can be obtained by setting the inner diameter of the through hole 13 to be larger in the porous body 12 on the downstream side.
(Fourth embodiment)
A fourth embodiment is shown in FIGS. In this hydrogen separator 11, each porous body 12 is joined via a cylindrical member 16 formed of the same material as that of the porous body 12 and having the same outer diameter so that a predetermined interval is provided between the end faces. It is.

  The manufacturing procedure of the hydrogen separator 11 is the same as that of the first embodiment. FIGS. 5-2 to 5-4 correspond to the steps of FIGS. 2-2 to 2-4, respectively. The hydrogen separation membrane 15 is also formed on the inner surface of the cylindrical member 16.

  According to this embodiment, since the passage cross-sectional area changes abruptly between the through hole 13 and the cylindrical member 16 of each porous body 12, a large gas turbulence occurs and the hydrogen permeation coefficient increases.

In this embodiment, since the hydrogen separation membrane 15 is also formed on the inner surface of the cylindrical member 16, the amount of hydrogen treatment can be increased accordingly. However, the cylindrical member 16 may be formed of a material having low gas permeability, for example, high-density ceramics, and the inner surface of the cylindrical member 16 may not be covered with the hydrogen permeable film 15. Can be reduced.
(Fifth embodiment)
FIGS. 6-1 to 6-3 show a fifth embodiment. This is because Pd is previously coated on the joining end face of each porous body 12, and further a metal film 17 having a higher strength than Pd, such as Ni, Cu, and Ag. By hot pressing the porous body 12, a metal film having a higher strength than Pd is formed, and the adhesive strength between the porous bodies 12 is further improved.
(Sixth embodiment)
FIGS. 7-1 to 7-3 show a sixth embodiment. This is a material in which a material 18 having the same cross-sectional shape as the end surface and having a low gas permeability, for example, a member 18 made of high-density ceramic is applied to the end surface of each porous body 12 by sintering, bonding, or the like. is there. The hydrogen permeable membrane 15 is formed after the porous bodies 12 are joined with the membrane 18 interposed therebetween.

  When the hydrogen separation membrane 15 is plated after joining the plurality of porous bodies 12, the step 14 is a right-angled corner, so that the plating process is difficult and plating defects are likely to occur. In this embodiment, a coating film 18 having a low gas permeability is formed only on the step portion, and the coating film 18 is joined before the plating process to ensure the sealing performance. Since the coating 18 and the end face of the porous body 12 forming the coating 18 have the same cross-sectional shape, there is no step between them. Therefore, according to this embodiment, even if a plating failure occurs in the vicinity of the step 14, it is possible to prevent the inconvenience of gas leakage from the defective portion.

  In addition, in the said structure, the joining number and cross-sectional shape of the porous body 12 are not restricted to what was shown to each embodiment, A various selection is possible.

1 is an external perspective view of a first embodiment of the present invention. Explanatory drawing which shows the positional relationship of the adjacent porous body of 1st Embodiment. The longitudinal cross-sectional view of the porous body of 1st Embodiment. The 1st longitudinal cross-sectional view which shows the manufacturing process of 1st Embodiment. The 2nd longitudinal cross-sectional view which shows the manufacturing process of 1st Embodiment. The 3rd longitudinal cross-sectional view which shows the manufacturing process of 1st Embodiment. The longitudinal cross-sectional view of the 2nd Embodiment of this invention. The longitudinal cross-sectional view of the porous body of 2nd Embodiment. The 1st longitudinal cross-sectional view which shows the manufacturing process of 2nd Embodiment. The 2nd longitudinal cross-sectional view which shows the manufacturing process of 2nd Embodiment. The 3rd longitudinal cross-sectional view which shows the manufacturing process of 2nd Embodiment. The longitudinal cross-sectional view of the 3rd Embodiment of this invention. The longitudinal cross-sectional view of the 4th Embodiment of this invention. The 1st longitudinal cross-sectional view which shows the manufacturing process of 4th Embodiment. The 2nd longitudinal cross-sectional view which shows the manufacturing process of 4th Embodiment. The 3rd longitudinal cross-sectional view which shows the manufacturing process of 4th Embodiment. The 1st longitudinal cross-sectional view which shows the manufacturing process of the 5th Embodiment of this invention. The 2nd longitudinal cross-sectional view which shows the manufacturing process of 5th Embodiment. The 3rd longitudinal cross-sectional view which shows the manufacturing process of 5th Embodiment. Explanatory drawing which showed the part which plating defect produces in the longitudinal cross-section. The 1st longitudinal cross-sectional view which shows the manufacturing process of the 6th Embodiment of this invention. The 2nd longitudinal cross-sectional view which shows the manufacturing process of 6th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Hydrogen separator 12 Porous body 13 Through-hole 14 Step 15 Hydrogen separation membrane 16 Cylindrical member 17 High-strength metal membrane 18 Member

Claims (12)

In the hydrogen separator in which the surface of the through hole formed in the porous body is coated with a hydrogen separation membrane made of a metal having hydrogen separation ability,
A hydrogen separator having a structure in which the porous body is divided into a plurality of through holes in the gas flow direction, and a step is formed between the joint surfaces of the through holes of adjacent porous bodies.   The plurality of porous bodies each have the same cross-sectional shape, and are formed by joining adjacent porous bodies so that the openings of the through holes partially overlap each other on the cross section. Item 2. The hydrogen separator according to Item 1.   The hydrogen separator according to claim 1, wherein the through hole is formed in a tapered shape whose inner diameter gradually changes in a gas flow direction.   The hydrogen separator according to claim 3, wherein the through hole is set so that an inner diameter gradually increases in a gas flow direction.   2. The hydrogen separation according to claim 1, wherein the through hole is formed in a right cylindrical surface at the same position in cross section for each of a plurality of porous bodies, and the inner diameters of adjacent porous bodies are set to be different. vessel.   The hydrogen separator according to claim 5, wherein the through hole is set so that the inner diameter of the porous body on the downstream side becomes larger.   The hydrogen separator according to any one of claims 1 to 6, wherein the porous body has a metal membrane having a strength higher than that of the hydrogen separation membrane formed on a hydrogen separation membrane coated on an end surface thereof.   7. The hydrogen separator according to claim 1, wherein a member made of a material having the same cross-sectional shape as the end surface and having low gas permeability is formed on the end surface of the porous body.   2. The hydrogen separator according to claim 1, wherein the porous body is joined via a cylindrical member so that a predetermined interval is provided between the end faces.   The hydrogen separator according to claim 9, wherein the cylindrical member is formed of a material having low gas permeability.   The hydrogen separator according to claim 9, wherein the cylindrical member has an inner surface covered with a hydrogen separation membrane.   The hydrogen separator according to any one of claims 9 to 11, wherein the porous body and the cylindrical member are formed in a cylindrical shape having the same outer diameter.

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