RU2793102C1 - Steam source for plasma separation of substances - Google Patents

Abstract

FIELD: melting devices.

SUBSTANCE: invention relates to melting devices using the cold crucible induction melting method for melting substances such as oxides and their alloys, and can be used to melt, vaporize and ionize radioactive waste for plasma separation. The source of steam for plasma separation of substances includes a container open from above with a heat-resistant bottom and side walls made of tubes with the possibility of filling with a coolant, and the bottom of the container is made with at least one technological hole, a high-frequency inductor placed around the walls of the container. One conductive refractory rod passes through the technological opening of the container bottom and is at least partially placed inside the container, the rod being installed with the possibility of longitudinal movement through the hole, and the electrode located above the container around its open part.

EFFECT: invention makes it possible to minimize the high-temperature effect on the walls and bottom of the container with the evaporated substance with simultaneous ionization of the evaporated substance, and also to expand the arsenal of steam sources for plasma separation of substances.

2 cl, 1 dwg

Description

The invention relates to melting devices using the cold crucible induction melting method (CIPCT) designed for melting substances, such as oxides and their alloys, and can be used for melting, vaporizing and ionizing radioactive waste for their plasma separation.

From the prior art, a means for melting oxide materials in an induction furnace is known, disclosed in patent RU 2737663, published on 12/02/2020, IPC G21F 9/16, F27B 14/06. This tool can be taken as the closest analogue. The melting of oxide materials, in particular, the vitrification of high-level waste, the authors of the patent propose to carry out in an induction furnace containing an inductor and a metal water-cooled sectional crucible with a hot-type induction downcomer. The bottom part of the crucible and the inductor are made in the form of a cone, and the coils of the inductor are located opposite the conical part of the crucible. In the lower part of the crucible cone there is a drain device with a drain flange and a drain tube, which is equipped with an additional inductor.

The disadvantages of the known tool from the point of view of the problem being solved can be identified as follows. The known means is aimed only at melting substances and its use does not imply the possibility of purposeful evaporation of the melted substance. In other words, the known tool is not designed for high temperatures, providing the evaporation of molten radioactive waste. The existing crucible under the proposed conditions will quickly become unusable and burn out. In addition, even if you try to use the known means as a source of vapor, it will not be able to provide ionization of the evaporated substances, since it does not provide integrated means of ionization.

The technical problem to be solved by the claimed invention is to create a steam source for plasma separation of substances, which is highly reliable and resistant to high temperature effects.

The technical result achieved by using the claimed invention is to minimize the high-temperature effect on the walls and bottom of the container with the evaporated substance while ensuring the ionization of the evaporated substance. The device also expands the arsenal of steam sources for plasma separation of substances.

The technical problem is solved, and the technical result is achieved due to the fact that the source of steam for plasma separation of substances includes a vessel open from above with a heat-resistant bottom and side walls made of tubes with the possibility of filling with a coolant, and the bottom of the vessel is made with at least one process hole, a high-frequency inductor placed around the walls of the container, at least one conductive refractory rod passing through the technological hole in the bottom of the container and at least partially located inside the container, the rod being mounted for longitudinal movement through the hole, and an electrode located above the container around it * open part.

The technical problem is solved, and the technical result is also achieved in the next particular embodiment of the device.

The conductive refractory rod of the steam source can be made of tungsten.

The use of a cooled container in combination with induction heating and a refractory rod installed with the possibility of longitudinal movement inside the container makes it possible to form a local zone of melting and evaporation of the substance loaded into the container. Cooling the walls of the container limits the spread of the melting of the substance, and, therefore, minimizes the high-temperature effect on the walls and bottom of the container and, thereby, increases its reliability and durability. The high frequency of the alternating current of the inductor, together with the heat transferred from the refractory rod, which functions as a cathode, makes it possible to maintain the evaporation temperature of the working substance. Tungsten has a high melting point, so its use as a rod material is preferable. The electrode above the container acts as an anode and, together with the cathode, provides ionization of the evaporated substance.

The steam source for the plasma separation of substances is illustrated in the drawing (Fig. 1), which schematically shows its design.

In accordance with the present invention, a steam source for plasma separation of substances (see Fig. 1) includes a container (1) open at the top with a heat-resistant bottom (2) and side walls (3) made of tubes that can be filled with coolant. A high-frequency inductor (4) is placed around the container (1) opposite its side walls (3). The bottom (2) of the container (1) is made with at least one technological hole (5). At least one conductive refractory rod (6), which is the first electrode, is installed in said hole (5) with the possibility of longitudinal movement. The rod (6) passes through the technological hole (5) and is at least partially placed inside the container (1). Preferably, the rod (6) is made of tungsten, which has a high melting point. The second electrode (7) is installed above the container (1) around its open part. The second electrode (7) can be made as a single or from several parts.

The execution of the electrical connection of the first and second electrodes, as well as the high-frequency inductor, can be performed by any method known to a person skilled in the art and is not the subject of the claimed invention.

The proposed steam source for plasma separation of substances works as follows.

The substance to be evaporated, for example an oxide, is placed in the form of a powder in a container (1). If necessary, the substance (powder) can be added to the container (1) from above, as it evaporates. The side walls (3) of the container (1) are tubes filled with coolant. The type of coolant and its means of supply may be any known to those skilled in the art. After that, power is supplied to the high-frequency inductor (4).

In the operating mode of the device, the container (1) constantly contains a substance both in a solid state (powder) and in a liquid, molten state, which is located on the surface of the solid in the central part of the container (1). Due to the presence of side walls (3) in the form of tubes with a coolant, the powder does not melt along the periphery of the container (1). In other words, the cooled container (1) in combination with the substance poured into it performs the functions of a crucible in which the process of melting and evaporation of the substance itself takes place. Thus, the durability of the device and its resistance to high temperatures is ensured.

Evaporation occurs from the upper surface of the liquid substance. Since the conductivity of oxide melts, as a rule, is much greater than the conductivity of oxides in the solid state, the melt of a substance can be heated inductively, by means of a high-frequency inductor (4). However, the conductivity of oxides is less than that of metals, and therefore a higher frequency is required to provide the desired skin thickness. Therefore, a high-frequency inductor is needed.

To start the evaporation process, it is possible, for example, to use a metal seed placed before starting the inductor (4) on the surface of the powdered substance in the container (1). After the inductor (4) is turned on, this seed is inductively heated and gradually destroyed, but at the same time it manages to create a layer of conductive straightened substance around itself.

A conductive rod (b) made of a refractory and chemically inert substance, preferably tungsten, is passed through the technological hole (5) in the bottom (2) of the container (1) through the thickness of the powdered substance (oxide). Due to the possibility of longitudinal movement of the rod (6), it is ensured that its upper part touches the liquid, molten substance. Thus, the molten substance, together with the rod (6), acts as a cathode for ignition of a vacuum arc discharge and ionization of the evaporated substance. The electrode (7), acting as an anode, is located above the container (1) around its open part.

In addition, it is important to note that the operation of the cathode is associated with high thermal radiation, which requires separate cooling. The proposed device ensures the removal of heat from the cathode and eliminates its local overheating due to the fact that the cathode is laid inside the container (1), and, consequently, through the thickness of the working substance. At the same time, the absorbed heat is not enough to melt the substance and subsequently damage the container (1), but it is sufficient to maintain, together with the inductor (4), the evaporation temperature of the substance. Also, since the rod (6) is made of refractory tungsten, it does not melt under induction action.

Thus, the claimed steam source for plasma separation of substances minimizes the high-temperature effect on the walls and bottom of the container with the evaporated substance with simultaneous ionization of the evaporated substance, which leads to high reliability and durability of the device.

The device also expands the arsenal of steam sources for plasma separation of substances.

Claims (6)

1. Steam source for plasma separation of substances, including - a container open from above with a heat-resistant bottom and side walls made of tubes with the possibility of filling with a coolant, and the bottom of the container is made with at least one technological hole, - a high-frequency inductor placed around the walls of the tank, - at least one conductive refractory rod passing through the technological hole in the bottom of the tank and at least partially placed inside the tank, and the rod is installed with the possibility of longitudinal movement through the hole, - an electrode located above the container around its open part. 2. Steam source according to claim. 1, in which the conductive refractory rod is made of tungsten.

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