RU2234973C2 - Apparatus for feeding of hydrogen isotopes into receptacle (versions) - Google Patents

Abstract

FIELD: nucleonics.

SUBSTANCE: apparatus has casing 1 incorporating part 2 from metal hydride, heater 3, electrodes 4, discharge branch pipe 5, enclosure 6, and branch pipe 7 with stopper 8. Part 2 is hydrogen isotopes carrier and is located in enclosure 6 made porous, from, for example, stainless steel. According to one version, apparatus is further equipped with membrane 9 having selective hydrogen isotope permeability. Heater 3 is positioned between membrane 9 and part 2. According to other version, heater 3 is made in the form of tube manufactured from material with selective hydrogen permeability and serves as selectively permeable membrane. One end of heater 3 is sealed and other end is hermetically connected with discharge branch pipe 5. Part 2 may be made in the form of hollow cylinder and positioned coaxially with respect to heater 3 or may be made flat, for example, in the form of pellet, and heater 3 is arranged above part 2. Hydrogen isotopes are desorbed from part 2 owing to heating thereof by current flowing through electrodes 4. Membrane 9 or heater 3 selectively transmits target hydrogen isotope, which is discharged through branch pipe 5. Apparatus of such construction allows purity of hydrogen isotope supplied into receptacle to be at least 99.99999%.

EFFECT: provision for producing of pure hydrogen isotope supplied into receptacle and fine regulation of flow.

5 cl, 3 dwg

Description

The invention relates to the field of producing high-purity hydrogen by diffusion cleaning and can be used to supply it to the receiver with the ability to fine-tune the values of the supplied flows.

In the field of supplying hydrogen isotopes to a receiver, a device is known for absorption and evolution of hydrogen [1]. It contains a housing in which a part of an alloy capable of absorbing hydrogen and a substance whose electrical resistance is higher than that of the alloy are installed. Electrodes are connected to the part, when a current is supplied through which it is heated, as a result of which the flow of hydrogen absorption and evolution reactions is regulated. This device can be used to supply hydrogen released during heating of the alloy to the receiver.

The known device has the following disadvantages. It does not provide purification of hydrogen from gas impurities. In the case of the release of the radioactive isotope of hydrogen - tritium, the yield of its decay product, He ^3, is also inevitable. In addition, as a result of the evolution of hydrogen from the alloy, its electrical resistance changes, because the reaction of converting the alloy hydride into alloy occurs. To obtain a constant rate of hydrogen evolution, the current flowing through the alloy must be constantly adjusted.

A device is known for separating hydrogen and / or its isotopes from liquid or gas flows [2], containing a hydrogen-permeable tubular substrate of porous ceramic material, the central outer part of which is coated with a film of a metal or alloy, characterized by catalytic activity and selective permeability to hydrogen. In this case, the outer surface of both ends of the tube is covered with a gas-tight material. The ends of the tube with seals are tightly attached to the reactor shell, and a cavity is formed in which an initial stream containing hydrogen isotopes enters. Through a film with selective permeability along hydrogen isotopes, they are released from the stream, enter the tube, and are removed through it.

This device allows you to select hydrogen isotopes from the flows of liquid and gases, and therefore the disadvantage of the device is its complexity due to the need for an external source of hydrogen isotopes with a variable parameter.

The closest in technical essence to the claimed device is a device for input and selection of hydrogen isotopes [3]. It contains an evacuated working chamber with an outlet pipe, a metal hydride part installed in it, and a unit with a heater made in the form of a wire spiral. The metal hydride part is located coaxially around the heater, while the equilibrium pressure of hydrogen above the metal hydride is: <0.1 mm Hg at 30 ° С and ≥1 atm at 350 ° С. A heat-shielding shell is placed in the working chamber, which divides the working chamber into two volumes, one of which contains a metal hydride component and a heater, and the other is connected to the outlet pipe. When voltage is applied, the wire spiral heats up and under the influence of heat, hydrogen isotopes are desorbed from the metal hydride. The pressure of hydrogen isotopes in the working chamber is equal to the equilibrium pressure above the hydride used at the heating temperature. The gas released into the working chamber is supplied through the pipe to the receiver.

Such a device provides a gas supply to the receiver with a purity realized by heating the metal hydride. In particular, for metal tritide, this means the presence of impurities of radiogenic helium and other impurities of organic and inorganic origin adsorbed on the surface of tritide and released into the gas phase upon heating, which is not always acceptable for the operating conditions of the receiver. As impurities, gases that are initially found in the structural materials of the device can be released. In addition, with such a design of the device it is difficult to provide fine adjustment of the gas flow in a wide range of flow values (when they differ in extreme values by 3-4 orders of magnitude). The pressure of hydrogen isotopes in the chamber will be equal to the equilibrium pressure above the hydride used at the heating temperature, and without any adjustment, this flow of hydrogen isotopes will pass through the nozzle to the receiver.

The present invention is to provide a device that provides fine adjustment of the gas flows supplied to the receiver in a wide range of flows (up to 3-4 orders of magnitude) while ensuring the diffusion purity of the isotopes of hydrogen supplied to the receiver.

When using the present invention, the following technical results are achieved:

- the purity of the gas supplied to the receiver increases by at least 2 orders of magnitude and is at least 99.99999%;

- expanding the range of flows by summing the temperature effects of the equilibrium pressure P (T) over the hydride and the coefficient of selective membrane permeability K _p (T), which can be controlled by changing the temperature of the working surfaces of the device. In this case, the flow is calculated as follows:

J (mol / s) = K _p (T) · S / (L · N _A ) · √P (T),

where S is the area of the selective membrane, L is the thickness of the membrane, N _A is the Avogadro number. When the temperature of the 0.2 mm thick membrane from nickel changes from 400 to 1000 K and at an equilibrium hydrogen pressure of 1 atm, the penetrating flow will change by 4 orders of magnitude;

- the established flow of gas coming from the device is maintained with an accuracy of ± 0.5% in the range of flow changes up to 4 orders of magnitude.

This problem is solved by the fact that the known device for supplying hydrogen isotopes containing an evacuated working chamber with an outlet pipe, a metal hydride part installed in it, a heater and an element dividing the working chamber into two volumes, one of which contains a metal hydride part, and the other is connected to the outlet pipe, according to the invention, said element is made in the form of a membrane with selective permeability along hydrogen isotopes. A heater is installed between the metal hydride part and the membrane. The metal hydride part is housed in a shell, wherein at least one of the walls of the shell is made porous.

An option is a device for supplying hydrogen isotopes to a receiver, comprising a working chamber with an outlet pipe, a metal hydride component installed in it, and a heater, characterized in that the heater is made in the form of a tube made of a material with selective permeability along hydrogen isotopes, with one end of the tube it is tightly closed, and the second is hermetically connected to the outlet pipe with the possibility of separating the tube cavity from the volume of the working chamber. The metal hydride part can be made flat, for example, in the form of a tablet, and the tubular heater in the form of a flat spiral mounted above its surface. The metal hydride part is housed in a shell, wherein at least one of the walls of the shell is made porous.

A comparative analysis of the proposed solution with the prototype shows that the claimed device differs from the prototype in that the element dividing the working chamber into two volumes, one of which is a metal hydride part, and the other is connected to the outlet pipe, is made in the form of a membrane with selective permeability according to hydrogen isotopes, while the heater is installed between the metal hydride part and the membrane. In another embodiment, the claimed device differs from the prototype in that the heater is made in the form of a tube made of a material with selective permeability along hydrogen isotopes, while one end of the tube is tightly closed and the other is hermetically connected to the outlet pipe with the possibility of separating the cavity of the tube from the volume of the working chamber . Thus, the claimed device meets the criteria of the invention of "novelty."

When analyzing the known technical solutions, no devices were found that have features that match the distinguishing features of the claimed devices, which allows us to conclude that it meets the criterion of "inventive step".

In the claimed device, under the action of heat from the heater, hydrogen isotopes are desorbed from the metal hydride. Under the action of heat from the same heater, the membrane heats up. The membrane is made of a material with selective permeability to hydrogen, for example, Pd or Ni. When heated, the membrane becomes permeable to hydrogen isotopes. Due to the heating of a metal hydride and membrane from a single heater, not only the design is simplified, but the flow control conditions are also improved. In this case, the summation of the results of two physical phenomena occurs. It is known that the equilibrium pressure of hydrogen isotopes over metal hydrides is proportional to their temperature. It is also known that the permeability of metals with hydrogen isotopes is a function of temperature and pressure. Increasing the temperature of the heater by increasing the current passing through it, in order to increase the flow of hydrogen, leads to an increase in the pressure of hydrogen in the working chamber and an increase in the permeability of the membrane. Those. the flow will increase due to the summation of effects. In the same way, with a decrease in the current passing through the heater, the pressure of hydrogen isotopes in the working chamber and the membrane permeability decrease. This leads to a decrease in the flow of hydrogen from the device.

In the embodiment of the device, when the heater is made in the form of a tubular spiral made of a material with selective permeability along hydrogen isotopes (it also acts as a membrane), the same summation of two effects is observed - with an increase in the current passing through the heater, its permeability increases and the isotope pressure hydrogen in the working chamber by increasing the temperature of the hydride. Hydrogen isotopes diffuse into the internal cavity of the tube through its wall. The sealing of the tubular membrane on one side and the tight connection of its other end with the outlet pipe allows you to separate the inner cavity of the tubular membrane from the cavity of the working chamber. Thus, the hydrogen isotopes entering the cavity of the tubular membrane are completely isolated from the gas medium in the working chamber. Because Since the cavity of the tubular membrane is hermetically connected to the outlet pipe, diffusion-pure hydrogen isotopes enter the receiver.

To reduce the overall characteristics of the device, the metal hydride part can be made in the form of a tablet, and a tubular heater acting as a membrane is installed above the surface of the tablet.

Placing a metal hydride part in a shell, at least one of the walls of which is made porous, allows us to solve the technological problem of holding the powder of the hydride-forming material in one geometric place, to prevent its migration through the device’s volume, and, accordingly, to the membrane’s material, which can lead to its failure due to dissolution of the metal hydride in the metal of the membrane. At the same time, the porous wall allows one to solve the problem of the escape of hydrogen isotopes from the shell, and when gas is completely removed from the carrier metal through the porous wall, it is again filled with hydrogen isotopes.

Figure 1 shows a device for supplying hydrogen isotopes - a variant according to claim 1 of the claims (with a cylindrical gas carrier, a membrane and a heater).

Figure 2 presents a device for supplying hydrogen isotopes - an option according to claim 3 of the claims (with a combined heater and membrane and a cylindrical gas carrier).

Figure 3 presents a special case of a device for supplying isotopes of hydrogen - an option according to claim 4 of the claims (with a combined heater and membrane and a flat gas carrier) and a top view in section.

The device in figure 1 contains a housing 1, in which a part 2 is installed, made of a metal hydride, which is a carrier of gas - a hydrogen isotope (or mixtures of hydrogen isotopes), a heater 3 in the form of a spiral, electrodes 4, an outlet pipe 5. Detail 2 is enclosed in the shell 6, which, at least on one side is made porous, for example, of porous stainless steel. In the case of complete removal of gas from the part 2, a nozzle 7 with a plug 8 is provided in the housing for filling the carrier. The housing 1 also contains a membrane 9 with selective hydrogen permeability separating the metal hydride volume from the volume in which the outlet nozzle is installed. The heater 3 is located between the membrane 9 and the metal hydride part 2.

The device of FIG. 2 and FIG. 3 comprises a housing 1 in which a part 2 is mounted made of a metal hydride that is a carrier of a gas — a hydrogen isotope (or mixtures of hydrogen isotopes), a heater 3 in the form of a tube made of a material with selective hydrogen permeability, performing the function of a diffusion membrane. One end of the tube is hermetically connected to the electrode 4, and the other end is hermetically installed in the outlet 5. The metal hydride part 2 can be made in the form of a hollow cylinder and mounted coaxially with respect to the heater membrane 3 (as shown in FIG. 2). Another option is also possible when the metal hydride part 2 is made flat, for example, in the form of a tablet, and the tubular heater - membrane 3 is made in the form of a flat spiral and is located above the surface of the tablet (as shown in Fig. 3). Part 2 is enclosed in a shell 6, which, at least on one side, is made porous, for example, of porous stainless steel. In the case of complete removal of gas from the part 2, a nozzle 7 with a plug 8 is provided in the housing to fill the carrier.

The device of figure 1 for supplying isotopes of hydrogen to the receiver operates as follows.

When voltage is applied to the electrodes 4 and the housing of the working chamber 1, the heater 3 is heated, under the action of heat from which the part 2 of the metal hydride and the membrane 9 are heated. This leads to hydrogen desorption from the part 2 and the membrane permeability 9. The released hydrogen fills the working chamber 1 and is directed to the membrane 9, which separates part of the working chamber with metal hydride from its other part, in which the outlet pipe 5 is located. Gas passes through the membrane and enters the outlet pipe. Thus, the hydrogen leaving the device is cleaned.

By changing the magnitude of the applied voltage between the housing 1 and the electrode 4, it is possible to vary the flow of hydrogen isotopes directed to the receiver over a wide range of parameters.

The device according to figure 2 and 3 for supplying isotopes of hydrogen to the receiver operates as follows.

When voltage is applied to the electrode 4 and the housing of the working chamber 1, the heater tube 3 is heated, under the action of heat from which the part 2 of the metal hydride is heated and hydrogen is desorbed. The released hydrogen diffuses through the wall of the tube 3, which simultaneously performs the function of the membrane, into the internal cavity of the tube. Because one end of the tube is sealed, and the other is hermetically installed in the outlet pipe 5 of the working chamber 1, then the hydrogen isotopes located in the tube are isolated from the cavity of the working chamber and pure hydrogen isotopes enter the receiver.

By changing the magnitude of the applied voltage between the housing 1 and the electrode 4, it is possible to vary the flow of hydrogen isotopes directed to the receiver over a wide range of parameters.

The proposed device for supplying hydrogen isotopes to the receiver is implemented as a variant according to claim 3 of the claims with ZrCO ₂ hydride and a selective nickel tube. After the metal hydride was saturated with hydrogen at a pressure of 1 atm, a current from 0 to 5 A was applied to the electrodes of the device, while the leakage flux changed from ~ 0.1 cm ³ bar / h to 2500 cm ³ bar / h.

Sources of information

1. Device for the absorption and evolution of hydrogen using an alloy that absorbs hydrogen. Japan patent No. 6092241 B4 (application No. 61-230375 with priority of 09/29/86), publ. 11.16.94, IPC ⁶ C 01 B 3/00, ISM Magazine, Issue 37, No. 4, 1998, p. 9.

2. Ceramic catalytic membrane reactor for separating hydrogen and / or its isotopes from the feed streams. US patent No. 5366712, publ. 11.22.94, IPC ⁶ C 01 B 3/00.

3. Device for input and selection of hydrogen isotope of ultrahigh purity. Japanese Application No. 59137301, publ. 08/07/84, IPC ⁶ C 01 B 4/00.

Claims (5)

1. A device for feeding hydrogen isotopes to a receiver containing a vacuum chamber with an outlet pipe, a metal hydride part installed in it, a heater and an element dividing the working chamber into two volumes, one of which contains a metal hydride part, and the other is connected with an outlet pipe, characterized in that said element is made in the form of a membrane with selective permeability along hydrogen isotopes, wherein the heater is installed between the metal hydride part and the membrane. 2. The device according to claim 1, characterized in that the part of the metal hydride is placed in the shell, and at least one of its walls is made porous. 3. A device for supplying hydrogen isotopes to a receiver containing a working chamber with an outlet pipe, a metal hydride part installed in it and a heater, characterized in that the heater is made in the form of a tube made of a material with selective permeability along hydrogen isotopes, with one end of the tube it is sealed, and the second is hermetically connected to the outlet pipe with the possibility of separating the tube cavity from the volume of the working chamber. 4. The device according to claim 3, characterized in that the metal hydride part is made flat, for example, in the form of a tablet, and the tubular heater is made in the form of a flat spiral and is installed on one side of it. 5. The device according to claim 3 or 4, characterized in that the part of the metal hydride is placed in the shell, and at least one of its walls is made porous.

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