JPH05330803A - Hydrogen purifier provided with a substrate made of alloy of composition being the same composition as alloy of pipe - Google Patents

Abstract

PURPOSE: To provide a hydrogen purifying device which can allow extremely a lot of cycles while more improving the reliability without degradation.

CONSTITUTION: This device is a device for separating hydrogen from gaseous hydrogen-containing mixtures or purifying gaseous hydrogen. The device is provided with an outer casing 2 filled with a plurality of tubes 3 made of a suitable palladium based alloy in which the one ends of tubes are closed and the other ends 5 are opened. These tubes 3 are fixed in a substantially seal-tight manner at the open end side 5 to a part at least of a supporting base 6 made of a metal alloy of which the composition is such that its expansion coefficient in hydrogen is substantially equal to that of the alloy of the tubes 3. The supporting base 6 can be a single member composed of the above-mentioned alloy. Or, the supporting base 6 can be provided with an annular body having substantially the same composition as that of the tubes 3 and the annular body is joined to the tubes 3 by autogenous soldering. This device is especially applied to electronic industries.

COPYRIGHT: (C)1993,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for separating hydrogen in a gas mixture containing hydrogen, or an apparatus for purifying gaseous hydrogen.

This device was produced, inter alia, by the electronics industry to obtain ultrapure hydrogen containing, for example, less than 1 ppm of other gases, meteorology using hydrogen-expanded sounding balloons, steam reforming or electrolysis of methanol. It is applied to the separation of hydrogen, the production of standard gas for analysis, the isotope separation, or the refining of vegetable oils.

[0003]

Prior art and problems to be solved
-A-2,961,062, US-A-3,368,329, US-A-3,509,694, and JP-A-61 / 077602 (World Patent Index AN 86-141,337
Derwent Publication Ltd. London, GB).

At low flow rates, which are generally 0.1 to 100 standard cubic meters per hour (Nm ³ / h), the epurateurs commonly found in this industry utilize the principle of hydrogen permeation through a palladium-based alloy membrane. is doing. This membrane is selectively hydrogen permeable and acts as a filter. This allows pure hydrogen to pass through the membrane, while impeding the passage of gas impurities, or other components of the gas mixture.

In a practical application of this method, the filter is usually arranged in the form of a tube with one open end. This tube, or preferably a series of tubes, is grouped in an outer jacket made of stainless steel or other material that is inert to the action of the gas or gas mixture so as to form a diffusion cell. Has been.
The impure hydrogen gas or gas mixture enters under pressure in the jacket where it contacts the outer surface of the tube or tubes. Pure hydrogen diffuses through one or more walls towards the inside of the tube, then passes through one or more open ends of the tube or tubes and is recovered externally to the device. It

These tubes generally have a small thickness, for example
50-200 micrometers, preferably arranged in parallel on a perforated metal disk (or embase) made of stainless steel or nickel, for example.

The assembly is carried out using a braze containing palladium and silver so that a virtually perfect hermeticity is created between the tube and the perforated support. Soldering alloys are generally very silver rich.

The working temperature and pressure of these tubes are respectively at least 200 ° C., eg 200-700 ° C., and 2 ° C.
~ 50 bar (1 bar = 0.1 MPa). The combined effects of temperature and pressure difference between the inside and outside of the tube,
This may distort or flatten the tube. This is due to at least one stiffening (r), such as a helical spring, that allows the passage of gas while maintaining the lateral stiffness of the tube.
aidissement) elements can be reduced by incorporating them inside the tube (this technique is for example French patent FR-B
-1352751).

It is known that palladium-based alloys containing silver, regardless of composition, expand at very high values (approximately 3% linearly) in the presence of hydrogen. Furthermore, only the palladium-silver alloy containing 74-79% silver has no phase change (α to β or β to α) in the presence of hydrogen. This change is accompanied by the sintering of the alloy and the appearance of cracks. This results in the appearance of leaks.

Refining equipment, such as those currently on the market based on palladium-silver, exhibit a life limited by the number of cycles including frequent start and stop steps. The reason for this may be as follows: -The tubes are made of, for example, a palladium-silver alloy, which expands under hydrogen by 3% and fixes them in the holes of the support in which they are placed. It is tightened by doing so that it cannot expand freely. This causes the tube to undergo ecrouissage and significant metal fatigue; -a soldering alloy with a composition very different from that of the tube diffuses into the tube during cell manufacture. , Thus changing the composition of the alloy of the tube over a certain depth, so that at this location a phase change can be avoided during the absorption of hydrogen,
The desired silver proportion is no longer present.

This results in sintering, deterioration of the physical properties of the alloy and signs of cracking.

The object of the present invention is to eliminate these drawbacks, so that a refiner is produced which is more reliable and which can tolerate a very large number of cycles without deterioration. It is to be.

[0013]

More particularly, the present invention relates to an exterior containing at least one tube (3), preferably a plurality of tubes (3) made of a suitable alloy based on palladium. In a device for the separation of hydrogen from a gas mixture containing hydrogen, or a device for the purification of gaseous hydrogen, which comprises a jacket (2), one or more tubes (3) have at least one of their ends underneath the hydrogen. Is substantially airtightly secured to at least a portion of a support (6) consisting of an alloy having a coefficient of expansion substantially equal to that of the tube alloy, preferably a palladium-based alloy. The present invention relates to a device characterized in that

According to a first embodiment of this device, the support may consist of a single piece, of substantially the same composition as the alloy used to form the tube. These tubes are preferably gas-welded (soudu), for example by laser light or with a plasma or electric microtorch.
re autogene) or by a suitable adhesive that can withstand temperature, medium and working pressure, such as a polyimide adhesive sold under the trade name SYNTHORG-IP605 by CEMOTA of Solaize (France). Adhered airtightly.

The support may be secured to the jacket in a substantially airtight manner by at least one flange which clamps at least one joint of suitable composition. These joints, in particular, must withstand a temperature of 500 ° C, especially in a reducing atmosphere, and have a diameter of 1
-10%, eg 0.1-5 mm for a support with a diameter of 15 mm
It must be capable of sliding on the sides of the support and must have appropriate elasticity.

For example, joints that may have these features include carbon densifie joints, and metal shroud rings incorporating springs.
e) With joints.

According to a second embodiment of this device, the support may comprise the following two parts: A first member having a composition substantially the same as that of the tube and containing an alloy surrounding the tube, and surrounding the first member and consisting of only one metal, such as nickel, copper or iron, or The second metal member is made of an alloy having a composition different from that of the alloy forming the one member. The members of the support are adhered to one another in a substantially gas-tight manner, for example using an adhesive as described above, whose melting temperature is lower than that of the metal parts to be assembled, or by brazing. Excellent results have been obtained with soldering.

Furthermore, the support may be secured to the jacket in a substantially airtight manner by welding, soldering or any other suitable fastening means, such as a flange.

In general, the tube and the support (first member or the entire support) comprise 45 to 95% by weight of palladium, preferably 65 to
It consists of an alloy containing 90%, preferably 70-80%.

This alloy contains Ag, Sn, Sb, Ce and R.
It may contain at least one metal selected from the group consisting of u, Rh, Cu, Au and Y. Preferably silver is used in a proportion of 20 to 30% by weight. However, binary alloys such as Pd-Ce: 92.3-7.7 or Pd
-Au: 90-10% can also be used.

When at least two metals are combined with palladium to form an alloy, silver is advantageously a large part of these two metals.

Mention may be made, for example, of ternary alloys: Pd-Ag-Ni: 85-13-2 (%) Pd-Ag-Rh: 70-20-10 Pd-Ag-Au: 73-24-3.

Mention may be made, for example, of the quaternary alloys: Pd-Ag-Au-Ru: 73.74 -20-5-1.26.
(%) Pd-Ag-Au-Ru: 68-25-5-2.

In particular, Pd / containing 74-79% by weight of palladium
When an Ag alloy is used, various hydrogen pressures (eg 0.1 to 50)
Under absolute bar), no phase change is observed during temperature fluctuations.

[0025]

BRIEF DESCRIPTION OF THE DRAWINGS The invention is better understood by looking at the drawing, which shows a non-limiting illustration of this device.

FIG. 1 is a vertical sectional view of a hydrogen purifier.

FIG. 2 shows a method of fixing the support. The support comprises a plurality of distribution pipes.

FIG. 3 shows another embodiment of the support according to the invention.

According to FIG. 1, the hydrogen purifier (1) comprises an outer jacket (2), for example in the form of a cylinder. The jacket contains several distribution pipes (3), which may consist of an alloy of 77% palladium and 23% silver. These tubes are closed at one end (4) and open at the other end (5). These are 140 c in length
It may have a diameter of 2 mm and a thickness of 60 to 150 micrometers. These tubes have the open end side
They are grouped in parallel on a metal disk (6) or on a perforated support made of a suitable alloy that defines a closed vessel in which hydrogen purification is carried out. The jacket (2) consists of a support at the end of the enclosure, i.e. the inlet (7) for the gas mixture containing hydrogen to be purified, which is connected to the closed end of the tube, and the opposite end of the enclosure. A first outlet opening (8) for collecting contaminants of the gas mixture, which is located near the.

The purified hydrogen that has diffused through the wall of the tube and entered the interior of the tube re-emerges from there via the open end,
Second outlet opening connected to the jacket closure cap
Recovered through (9). The Pd / Ag metal tube has a coefficient of expansion under hydrogen of laser beam, plasma micro torch, electric welding or any other gas welding method.
With a composition that is as close as possible to the expansion coefficient of the tube alloy,
Welded onto a metal support (6) made of Pd / Ag (77/23) alloy or any other metal. This metal support is
According to FIG. 2, it may have a thickness of 0.1 to 15 mm and is mounted in a substantially airtight manner by a high-density carbon joint (10) between the jacket and the head of the refiner. These joints are located on both sides of the support and by means of the flange (11) and tightening bolt device,
It guarantees airtightness to the outside. The reinforcement device (13)
The stress exerted by the internal hydrogen pressure, which ensures the retention of the support on which the Pd / Ag tube is welded in a gas-tight manner, and which can reach up to 40 bar, preferably 20-25 bar. Can withstand.

According to another embodiment illustrated by FIG. 3, the metal support (6) is made of nickel, stainless steel or any other metallic material and is welded to the jacket in a substantially airtight manner. Has been done. At the level of the support, the annular body (14) surrounding the end of the Pd / Ag (77/23) alloy tube and having a coefficient of expansion close to that of the alloy of the tube under hydrogen is a laser beam, or Glue to the open end of the tube by gas welding (15) performed by any other gas welding means. This inner diameter is such that it allows passage of the tube. This outer diameter is generally, for example, 0.2 to 15 mm larger than the inner diameter. The height of the annular body (14) is usually at most the same as the thickness of the support at most. Most often it is preferable to have as many tubes (3) as possible. It is therefore recommended that the annulus (14) have a height which is at most equal to half the thickness of the support, so as to obtain the arrangement as shown in FIG. Preferably, the height of the annulus (14) surrounding each tube (3) will be from about 5% to about 45% of the thickness of the support, and better still from about 10% to about 40%. Two members of the support of different composition surround the tube,
Bonding is generally by soldering (16), preferably at the component level furthest from the distribution pipe.

The tube thus fixed undergoes virtually no change in its composition during this production and when placed under hydrogen, and also no phase change. That is, since the tube is arranged in an annular body having substantially the same expansion coefficient as the tube, it experiences minimal stress due to differential expansion.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a hydrogen purifier according to the present invention.

FIG. 2 is a detailed view showing a method of fixing a support.

FIG. 3 is a diagram showing an embodiment of a support.

[Explanation of symbols]

 (1)… hydrogen purifier (2)… outer jacket (3)… tube (4)… closed end (5)… open end (6)… support (7)… gas mixture inlet (8) )… First outlet opening (9)… Second outlet opening (10)… Joint (11)… Flange (13)… Reinforcement device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor André Bison French Tassan-la-Dumiryn Monte de Werdern 20 (72) Inventor Philippe Legois France France Bondi av New Annatall France 44-2

Claims (12)

[Claims] 1. At least one tube (3), preferably a plurality of tubes made of a suitable alloy based on palladium.
In a device for separating hydrogen from a gas mixture containing hydrogen, or a device for purifying gaseous hydrogen, which comprises an outer jacket (2) containing (3), tubes (3) are provided at at least one of their ends. , At least in part on a support (6) comprising an alloy whose expansion coefficient under hydrogen is substantially equal to that of the tube alloy, preferably a palladium-based alloy. A device characterized by being fixed in an airtight manner. 2. The support comprises a single portion having a composition substantially the same as the composition of the alloy used to form the tube, the tube being substantially airtightly adhered to the support. Device according to claim 1. 3. The support comprises two parts:
The first portion (14) has the same composition as the tube and surrounds the tube, the second portion being a metal or a composition different from the composition of the alloy forming the first portion. 7. The device according to claim 1, wherein said device comprises a second alloy of the said and said portions of the support adhere to each other in a substantially gas-tight manner. 4. The two parts of the support are brazed.
A device according to claim 3 glued by sure (16). 5. The pipe is bonded to the support or a part of the support by gas welding (soudure autogene),
Device according to one of claims 1 to 4. 6. The support is fixed to the jacket (2) in a substantially gas-tight manner by at least one flange (11) fastening at least one joint (10) of suitable composition. Device according to one of the five. 7. The support is secured to the jacket (2) in a substantially airtight manner by welding, soldering or any suitable fastening means.
A device according to one of the: 8. An alloy in which the tube (3) and the first member (14) of the support, or the entire support, comprises 45-95% by weight of palladium, advantageously 65-90%, preferably 70-80%. Consists of,
Device according to one of claims 1 to 7. 9. The palladium-based alloy comprises:
Device according to one of the preceding claims, comprising at least one metal selected from the group consisting of Ag, Sn, Sb, Ce, Ru, Rh, Cu, Au and Y, and preferably silver. 10. A device according to claim 1, wherein the alloy comprises palladium and 20-30% silver. 11. The tube comprises at least one raidissement element suitable for maintaining lateral stiffness under the temperature and pressure conditions to which the tube is subjected.
A device according to one of the items 10 to 10. 12. The device according to claim 3, 4, or 7, wherein the support comprises at least one stiffening device (13) ensuring the maintenance of the support in the jacket.