JPH038812B2 - - 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 process, and the like.

Conventional technology Conventionally, a method using a palladium alloy membrane has been known as a method for producing high-purity hydrogen, and this method takes advantage of palladium's extremely high hydrogen permeability to separate impurities and hydrogen. It is.
In other words, a palladium-based alloy membrane is heated, and only the hydrogen in the hydrogen gas containing impurities permeates through the membrane to purify high-purity hydrogen. This method obtains the highest purity hydrogen 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 a main body made of stainless steel or the like, 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 to the inside of the tube and is drawn out to the secondary side.

However, in such conventional equipment, palladium alloy is extremely brittle, so when the Pd-Ag alloy membrane tube is welded directly to the main body made of stainless steel, etc., as mentioned above, cracks tend to form in the weld, which can cause leaks. , 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, fat, and dust. 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 make heating uniform, impurities may be generated therefrom, corroding the palladium alloy film and causing 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 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 However, in such conventional devices, when the device is stopped, for example, the inside is cleaned, and when the unpermeated gas (bleed gas) on the primary side is discharged through the exhaust system, the inside of the device becomes large. If the atmospheric pressure drops to or below the atmospheric pressure, there is a risk that fine particles may enter the Pd-Ag film, and if these particles adhere to the Pd-Ag film, they will become nuclei for microcrystal growth and cause pinholes. the result
The lifespan of the Pd-Ag film is shortened and must be replaced frequently.

Therefore, an object of the present invention is to prevent the intrusion of fine particles from the exhaust system when such an apparatus is stopped, and to protect the purification membrane from damage caused by them.

Means for solving the problem To achieve this objective, according to the invention:
One end of a palladium-based alloy tubular membrane is welded to a main body made of stainless steel, etc., a sealing member is attached to the other end of the tube, this tubular membrane is heated, and hydrogen gas containing impurities is passed through the tubular membrane. In high-purity hydrogen purification equipment, which allows only the hydrogen inside to permeate and refines high-purity hydrogen, and which can reduce the internal pressure to atmospheric pressure or below atmospheric pressure when it is not in operation, discharges hydrogen gas with concentrated impurity components to the primary side. The device is characterized in that the exhaust system is connected to an exhaust system, and this exhaust system is provided with a filter that prevents particulates from entering from the atmosphere when the inside of the device is brought to atmospheric pressure or below atmospheric pressure.

Effect With this configuration, in the device of the present invention, the filter for preventing the intrusion of fine particles from the atmosphere can be composed of, for example, a 0.02 μm filter, so that the filter that prevents the intrusion of fine particles from the atmosphere through the exhaust pipe system. The ingress of particulates into the primary side is substantially prevented, so that attack of the tubular membrane by particulates from the exhaust pipe system can ultimately be prevented. In addition, by configuring the bleed piping valve installed near the main body with a valve that does not generate particulates when operated,
It is possible to more reliably prevent fine particles from entering the primary side. This allows the purification membrane to operate stably for a long period of time.

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, in which 1 is a stainless steel main body, 2 is a Pd-Ag tubular membrane, and one open end 2a of this tubular membrane 2 is a nickel tubular member 3.
One end of the tubular member 3 is brazed 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 manner are shown in the drawings, the number can be designed arbitrarily. A spring-like body 6 made of stainless steel or tungsten whose surface is coated with titanium nitride is inserted inside each tubular membrane 2 along its entire length. This allows the tubular membrane 2
can withstand the pressure on the primary side. Arranged on the outer periphery of the tubular membrane assembly is an inner cylinder 7 made of oxygen-free copper that extends over its entire length and is fixed at one end to the end wall 8 of the main body 1.
A heater 9 is mounted on the outer peripheral surface of the cylindrical body 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 1 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
99,99999 in the seal portion between the end walls 4 and 8 assembled with b and between the end wall 4 and the lid member 12.
In order to purify hydrogen with a purity of over 100%, the inside of the device can be made into an ultra-high vacuum (i.e., in order to increase the purity of hydrogen to be purified, impurity gases attached to the parts inside the device that come in contact with hydrogen gas and those parts) Metal O-rings 15, 16, and 17 are used, respectively, in order to reduce the amount of gas released from the inside of the device as much as possible) and to withstand high temperatures of 200° C. or higher. These metal O-rings are made of, for example, stainless steel, Ni, or Al coated with titanium nitride, and preferably have 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.
Furthermore, 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.

The illustrated embodiments are merely for illustrative purposes, and the structure, shape, etc. of each part can be designed in various ways.
Naturally, the present invention can also be applied to prior art hydrogen purification apparatuses such as those described above.

Effects As explained above, according to the present invention, since the bleed gas exhaust system is provided with a filter that prevents the entry of fine particles, there is no fear that these fine particles will enter the primary side and corrode the purification membrane. The purification membrane can be used stably for a long period of time, and as a result, the operating cost of the device can be kept low.

[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, 20c: filter.

Claims (1)

[Claims] 1. One end of a palladium-based alloy tubular membrane is welded to a main body made of stainless steel, etc., a sealing member is attached to the other end of the tubular membrane, this tubular membrane is heated, and hydrogen containing impurities is passed through the tubular membrane. High-purity hydrogen purification equipment that allows only hydrogen in the gas to permeate and refines high-purity hydrogen, and that can reduce the internal pressure to atmospheric pressure or below atmospheric pressure when not in operation, discharges hydrogen gas with concentrated impurity components to the primary side. Connect the discharge system for
A high-purity hydrogen purification device characterized in that the exhaust system is provided with a filter that prevents particulates from entering from the atmosphere when the inside of the device is brought to atmospheric pressure or below atmospheric pressure.