JPH038809B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a high-purity hydrogen purification device that can be used, for example, in an impurity removal process in a nuclear fusion reactor fuel supply and exhaust system, a semiconductor manufacturing process, and the like.

Conventional technology Conventionally, a method using a palladium alloy membrane has been known as a method for refining high-purity hydrogen, and this method takes advantage of the extremely high hydrogen permeability of palladium to separate impurities and hydrogen. It is something.
In other words, a palladium-based alloy membrane is heated, and only the hydrogen in hydrogen gas containing impurities permeates through the membrane to purify high-purity hydrogen. This method is the most pure hydrogen available today. It is said that this is a possible method.

By the way, in conventional hydrogen purification equipment using palladium alloy membranes, one end of the Pd-Ag alloy membrane tube is directly welded to the main body, such as stainless steel, and the other end is sealed with the same material. A heater is provided on the outside (ie, the primary side) of the alloy membrane tube, and stainless steel powder or the like may be added to the tube to make the heating temperature uniform. Hydrogen gas to be treated is supplied to the outside of the Pd-Ag alloy membrane tube, so that only hydrogen permeates from the outside of the tube to the inside and is drawn out to the secondary side.

However, in conventional equipment like this, palladium alloy is extremely brittle, and as mentioned above, when a Pd-Ag alloy membrane tube is welded directly to a main body made of stainless steel, etc., cracks tend to form in the weld, which can cause leaks. However, there is a risk that impurities may flow into the secondary side (high-purity hydrogen side). Furthermore, since such Pd--Ag alloy membrane tubes are usually manufactured using a mechanical method, both the inside and outside of the tubes are considerably contaminated with oil and fat. Therefore, with a structure in which the tip is sealed, the inside of the tube cannot be sufficiently cleaned, and impurity gas is generated on the secondary side, causing a decrease in the purity of hydrogen. Furthermore, if the primary side is filled with a large amount of powder of stainless steel or the like in order to ensure uniform heating, impurities may be generated therefrom, corroding the palladium alloy film and creating holes.

A high-purity hydrogen purification device that solves these various drawbacks has been proposed in Japanese Patent Application No. 198500/1983, and in this device, both ends of a palladium-based alloy tubular membrane are open ends, and one of the ends is open. The end is fixed to the main body via a tubular member made of high-purity metal such as nickel that can be easily welded or brazed, and the other end is fitted and fixed with a sealing member made of the same material as the tubular member. The heater for the membrane is supported by a support made of a material that generates few impurities, and an ultra-high vacuum flange is used at each sealing part.

Problems to be Solved by the Invention Although the various drawbacks mentioned above can be solved by such an improved device, mechanical strength is a problem because pressure is applied to the outside of the palladium-based alloy tubular membrane. Become.

The amount of hydrogen permeation depends on the area of the Pd-Ag membrane, heating temperature, and primary side pressure, and as these increase, the amount of hydrogen permeation also increases. Furthermore, the amount of hydrogen permeation is inversely proportional to the film thickness. Therefore, it is more economical to make the membrane thinner for the same area, but in the conventional structure as described above, the tubular membrane often collapses and leakage occurs. On the other hand, it is conceivable to make the membrane thicker in order to increase its mechanical strength, but as a result, the amount of permeation of hydrogen decreases, and as a result, the membrane area must be increased, which is uneconomical.

From this point of view, a conventional method of maintaining mechanical strength is to insert a spring made of stainless steel or other material inside a Pd-Ag pipe, but these materials emit a lot of gas and are located on the secondary side. This causes a significant decrease in the purity of purified hydrogen.

Therefore, an object of the present invention is to provide a high purity membrane that has a membrane thickness that can maintain a desired amount of hydrogen permeation, and that can ensure stable purification by guaranteeing the mechanical strength of the tubular membrane without reducing the purity of hydrogen to be purified. Our objective is to provide hydrogen purification equipment.

Means for Solving the Problems In order to achieve the above object, according to the present invention, one end of a palladium-based alloy tubular membrane is welded to a main body made of stainless steel, etc., and a sealing member is attached to the other end of the tubular membrane. In a high-purity hydrogen purification device that purifies high-purity hydrogen by heating this tubular membrane and permeating only the hydrogen in hydrogen gas containing impurities through the tubular membrane, palladium-based It is characterized in that a reinforcing member for maintaining mechanical strength, whose surface is coated with a gas release prevention layer, is attached along the entire tubular alloy membrane.

This reinforcing member is preferably a spring-like member made of stainless steel, tungsten, or the like whose surface is coated with titanium nitride, and can be inserted into the tubular membrane.

Effect In the device of the present invention configured as described above,
By providing a reinforcing member whose surface is coated with a gas release prevention layer made of titanium nitride, etc.
Even a thin Pd-Ag film can maintain sufficient strength, making it possible to purify hydrogen extremely efficiently and maintain the purity of purified hydrogen on the secondary side. Further, the reinforcing member may be provided on either the inside or outside of the tubular membrane, and can be designed in various shapes such as a fin shape, a net shape, etc. in addition to a spring shape.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 shows an embodiment of the present invention, where 1 is a main body made of stainless steel (preferably SUS316L), and 2 is a main body made of stainless steel (preferably SUS316L).
A Pd-Ag tubular membrane, one open end 2 of this tubular membrane 2.
A is brazed to one end of a nickel tubular member 3 using palladium brazing material, and the other end of the tubular member 3 is welded to the end wall 4 of the main body 1. On the other hand, a nickel sealing member 5 is fitted and brazed to the other open end 2b of the tubular membrane 2. Although only two tubular membrane assemblies constructed in this way are shown in the drawing,
The number can be arbitrarily designed. A spring-like body 6 made of stainless steel or tungsten, whose surface is coated with a gas release prevention layer made of titanium nitride, is inserted inwardly inside each tubular membrane 2 along its entire length. This allows the tubular membrane 2 to sufficiently withstand the pressure on the primary side. Arranged on the outer periphery of the tubular membrane assembly is a cylinder 7 made of oxygen-free copper extending over its entire length, which cylinder 7 is fixed at one end to the end wall 8 of the body 1; A heater 9 is mounted on the outer circumferential surface of 7. This heater 9 is connected to an external power source via a conductor (not shown). Reference numeral 10 denotes an inlet pipe for introducing hydrogen gas to be purified, and its tip is equipped with a pipe in order to avoid blowing hydrogen gas locally onto a portion of each tubular membrane 2 and to obtain a relatively uniform gas flow within the main body 1. As shown in FIG. 2, a drum-shaped introduction section 11 is provided with a large number of lateral air outlets 11a. This controls the blowing of hydrogen gas to the primary gas purification cylinder, that is, each tubular membrane 2, and as a result, the life of the tubular membrane 2 can be extended.

The inside of each tubular membrane assembly communicates via a cavity 14 to a purified hydrogen take-off pipe 13 provided in the lid member 12. Also, the flanges 1a, 1 at both ends of the main body 1
In order to purify hydrogen with a high purity of 99.99999% or more, the inside of the device can be made into an ultra-high vacuum at the sealing parts between the end walls 4 and 8 combined with b and between the end wall 4 and the lid member 12. Moreover, in order to withstand high temperatures of over 200℃, each metal O-ring 1
5, 16, 17 are used. These metal O
The ring is made of, for example, stainless steel, Ni, or Al coated with titanium nitride, and preferably has a spring inside to prevent crushing.

In addition, as shown in the figure, the inner wall of the main body 1 in the portion that comes into contact with the hydrogen gas and the inner wall of the secondary side cavity 14 is coated with a conductive material that can withstand high temperatures, is stable, and emits less gas, such as titanium nitride coating 18.
19 is applied, thereby reducing the amount of released gas to prevent corrosion of the tubular membrane 2 and a decrease in the purity of purified hydrogen. In addition to the above-mentioned titanium nitride, materials for this coating include materials that emit less gas, such as
Examples include CrN, AlN, BN, etc.

Furthermore, in FIG. 1, reference numeral 20 denotes an exhaust system for discharging hydrogen gas enriched with impurity components on the primary side, and this exhaust system 20 is equipped with two valves 20a, 20b and a filter 20c as shown. There is. The filter 20c functions to prevent fine particles from the atmosphere from entering the primary side and adhering to the tubular membrane 2, and may be made of, for example, a 0.02 μm filter.
Further, a valve that does not generate particulates during operation, such as a bellows valve or a diaphragm valve, may be used as the valve 20a. When fine particles adhere to the tubular membrane 2, they become nuclei for microcrystal growth and cause pinholes, so preventing the intrusion of fine particles is also important from the viewpoint of stable operation.

3 and 4 show a modified embodiment, which is shown in FIG. 1 except that the hydrogen gas introduction part 21 has a donut shape and is provided with a large number of outlets 21a toward the end wall 8. The structure is the same.

In the illustrated embodiment, a spring-like body 6 is inserted into each tubular membrane 2, but instead of this spring-like body 6, a fin-like reinforcing member may be provided on the outside of the tubular membrane 2 as described above, or A net-like or annular reinforcing member may be provided inside.

Further, the present invention is not limited to the illustrated embodiment, but may be applied to a conventional device such as that described in the above-mentioned Japanese Patent Application No. 1985-1983.

Effects As explained above, according to the present invention, by providing the reinforcing member to the tubular membrane, the mechanical strength of the tubular membrane can be maintained sufficiently, and the hydrogen gas pressure on the primary side can be reduced to 10 kg/cm ² For example, if the thickness of the tubular membrane is set to about 50 to 75 μm, it can be used at a pressure of about 20 kg/cm ² and the purified gas flow rate can be sufficiently increased. can. In addition, the reinforcing member used for the tubular membrane is coated with a gas release prevention layer.
The released gas is lower than before, and the purity of purified hydrogen can be maintained at 99.99999% or higher without any substantial decrease in purity. As a result, the device according to the invention can guarantee stable purification operation over a long period of time.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing an embodiment of the present invention;
2 is an enlarged perspective view of a part of the device shown in FIG. 1, FIG. 3 is a schematic sectional view showing a modified embodiment of the present invention, and FIG. 4 is an enlarged part of the device shown in FIG. 3. FIG. In the figure, 1: main body, 2: tubular membrane, 6: reinforcing member.

Claims (1)

[Claims] 1. One end of a palladium-based alloy tubular membrane is welded to a main body made of stainless steel or the like, a sealing member is attached to the other end of the tubular membrane, this tubular membrane is heated, and a In a high-purity hydrogen purification device that purifies high-purity hydrogen by passing only hydrogen in hydrogen gas containing impurities, a gas release prevention layer is applied to the surface along the entire tubular membrane of palladium alloy. A high-purity hydrogen purification device characterized by being equipped with a reinforcing member for maintaining mechanical strength that is coated with. 2. The device according to claim 1, wherein the reinforcing member is a spring-like body made of stainless steel, tungsten, etc. whose surface is coated with titanium nitride, and is inserted into the tubular membrane.