JPS63198299A - Radio frequency induction plasma generator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a high frequency induced plasma generation device, and particularly to a high frequency induced plasma suitable for producing ultrafine particles and high temperature chemical reactions.

[Conventional technology]

Since high-frequency induced plasma is electrodeless, electrode materials do not mix into the plasma as impurities, and an extremely high temperature region of around 10,000°C can be easily obtained, and various reactive gases can be used. Therefore, in recent years, ultrafine metal particles, oxides, nitrides, etc. have been produced using this ultra-high temperature heat source.

A typical method is to supply powder raw material directly to the plasma center and then cool it (Japanese Patent Publication No. 53-197-
40583, JP-A-58-207938). In addition to this method, in consideration of the fact that the plasma tends to become unstable when raw materials are supplied into the plasma, a plasma reactor in which a plasma jet torch is installed above the plasma torch has been developed (Japanese Unexamined Patent Application Publication No. 1983-55). -32
(See Publication No. 317).

[Problem that the invention seeks to solve]

The above conventional technology supplies raw materials to the plasma center and utilizes high-temperature chemical reactions within the ultra-high temperature plasma, so even if the raw materials are supplied to the plasma center, the flow of the plasma is reversed due to the influence of magnetic pressure. I wake up. For this reason, the raw material does not pass through the plasma center and scatters to the plasma outer flame or to the outside of the plasma. Furthermore, when the supply amount of the raw material is increased, since the plasma is an electrodeless discharge, it becomes easily disturbed, and in some cases, there is a problem that the plasma itself disappears. On the other hand, a hybrid plasma reactor with a plasma jet torch installed above the plasma torch is equipped with a plasma jet torch that consumes the electrodes, so the advantage of high-frequency induction plasma is that no impurities are mixed in. However, there are problems in that it goes against the grain, unavoidable contamination with impurities, and is considered to be very expensive.

The purpose of the present invention is to widen the high-temperature region of the plasma using a nozzle, increase the uniformity of the product by keeping the temperature history of the product constant, and ensure the stability of the plasma, thereby achieving high quality. The purpose of the present invention is to provide an apparatus for producing ultrafine metal particles, nitrides, oxides, etc.

[Means for solving problems]

The above purpose is to install a nozzle at the bottom of the plasma torch that generates high-frequency induced plasma, expand the ultra-high temperature area over a wide range, and supply powder raw material to the ultra-high temperature area, passing through the cooling section installed at the bottom of the nozzle. This is achieved by letting Furthermore, in order to further improve the effect of constricting this high-temperature plasma, by adding a mechanism that generates a magnetic field, such as a magnet, around the nozzle, the plasma is constricted and the ultra-high temperature region expands over a wide range.

That is, the high frequency induction plasma generation device of the present invention is as follows.

A double pipe part consisting of an inner pipe and an outer pipe and having a structure in which a cooling fluid (for example, cooling water) flows through the gap between the two pipes, and an ignition rod arranged in the space inside the inner pipe of this double pipe part. .

A high frequency induction coil is provided around the outer tube of the double tube section. Furthermore, the present invention is characterized in that a nozzle configured to narrow the diameter of the inner tube space is attached to the exhaust side of the double pipe portion.

The nozzle may be formed as an extension of the inner and outer tubes, or as part of a double tube section, so that the cooling fluid may flow through the nozzle.

It is preferable to install a cooling section on the exhaust side of the nozzle.
It is preferable to adopt a structure in which a cooling fluid flows in the cooling section. In this case, the cooling fluid flow path may be an extension of the double pipe.

In order to supply the powder material into the torch, it is desirable to form a supply port in the squeezing nozzle. 1 for supply
It can be in one place or several places.

Furthermore, it is preferable to install a magnet (especially preferably an electromagnet) or an ultrasonic oscillation element in a coaxial circle of the nozzle (around the outer tube).

[Effect]

If the powder raw material is supplied into the high-frequency induced plasma from the top or side, it is predicted that the high-temperature plasma will be disturbed for the above-mentioned reasons. For this reason, when powder raw material is supplied to the tail flame of high-temperature plasma to cause a high-temperature chemical reaction, the flow of the high-temperature plasma is disturbed, the plasma diameter increases, and the powder raw material is scattered toward the outer circumference of the pragma, resulting in insufficient heat. Favorable high-temperature chemical reactions cannot occur. As a result, high-quality ultrafine metal particles cannot be obtained. According to the present invention, by installing a nozzle for the high-temperature plasma output from the plasma torch, the high-temperature plasma is compressed, so that a good ultra-high temperature region can be obtained even when a powder raw material is supplied. Therefore, it is possible to easily cause a high temperature chemical reaction and obtain metal vapor.

By rapidly cooling this metal vapor in a cooling section, high-quality ultrafine metal particles and nitrides with uniform particle sizes are produced.

Oxides etc. are obtained. Furthermore, by applying a magnetic field using a magnet or the like around the nozzle in the center and axial direction, the high-temperature plasma is rapidly constricted and the ultra-high temperature region expands.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

In this embodiment, the main portion of the torch 22 is formed from an inner tube 3 and an outer tube 4. The gap between the inner tube 3 and the outer tube 4 serves as a flow path for cooling water]7.

An induction coil 2 is wound around the outer tube 4, and both ends thereof are connected to a high frequency power source 1 via wiring 11. The inner tube 3 and the outer tube 4 are made of heat-resistant material. A nozzle 5 is formed at the lower end of this double tube portion, and the space formed by the inner tube 3 is gradually narrowed down as shown in the figure. An electromagnet 12 is arranged around the nozzle 5, and the nozzle 5 is designed so that the influence of this electromagnetic force extends to the space. Furthermore, several raw material supply pipes 14 are opened in the nozzle 5 . Furthermore, a cooling section 13 is provided below.

An ignition rod 7 is disposed inside and above the torch 22 so as to be movable in the vertical direction. Note that 10 is a holding portion for the ignition rod 7. On the other hand, on the opposite side, that is, on the exhaust side, a conduit 21 is formed as an extension of the space, and a filter 8 and an exhaust pump 9 are arranged on the conduit 21. 15 is an inflow gas, for example argon.

Inert gases such as nitrogen are preferred, but the type is not limited thereto. Reference numeral 16 indicates a swirling flow formed above the torch 22 by the inflowing gas 15. Reference numeral 18 denotes high frequency induced plasma generated by the above configuration.

An electric field is generated by passing a high frequency current from a high frequency power supply 1 to an induction coil 2, and this electric field is used to cause dielectric breakdown using an ignition rod 7 (by lowering the ignition rod 7) to start a high frequency induction plasma 18. Here, this high frequency induced plasma 18
Various gases and mixed gases, such as argon gas, can be used as the gas composition for holding the . These gases 15 and 16 flow spirally through the wall of the heat-resistant inner tube 3 to stabilize the high-frequency induced plasma 18.

Cooling water 17 is provided between the heat-resistant inner tube 3 and outer tube 4.
is applied to protect the induction coil 2 from radiant heat from the plasma.

By installing the high-frequency induced plasma 18 obtained above with the nozzle 5 in this embodiment, it is possible to expand the high temperature region of the plasma over a wide range, and to this high temperature region, powder materials etc. are delivered from the nozzle 5 together with reactive gas. By supplying it, there is an effect that high-temperature chemical reactions can be carried out easily. It is desirable to use metal as the material of the nozzle 5, and in this case, it is necessary to cool it with cooling water or the like. In addition, it is also possible to use heat-resistant materials such as ceramics.

In addition, as a method of supplying the powder material, a method of providing a powder material supply section between the plasma torch 22 and the nozzle 5 and continuously supplying it from one or several locations, and a method of supplying the powder material from one or several locations;
There is a method of supplying powdered raw material by providing one or several powder raw material supply ports 14 inside.

The powder raw material supplied to the high-temperature plasma from the nozzle 5 is vaporized in the high-temperature region, is quenched by the cooling section 13 in the flow of gas, and is collected by a filter installed in the collection section 8. The gas and high-quality ultrafine particles are separated in this collection section 8, and the gas is exhausted by an exhaust pump 9, and in some cases, connected to a circulation pump, and returned to the plasma torch 22, where the same process can be performed. It is. It is preferable that the cooling unit 8 has a structure in which the cooling unit 8 is cooled with cooling water, but there is also a method in which the cooling unit 8 is rapidly cooled with liquid nitrogen. Further, it is desirable that the cooling section has a structure that allows temperature control, mainly because it is highly effective in film production and the like.

By providing a mechanism for generating a magnetic field, such as an electromagnet 12, around the nozzle 5 and applying a magnetic field in the axial direction with respect to the central axis, the high temperature plasma narrowed by the nozzle 5 is further narrowed by the effect of the magnetic field, It is possible to create ultra-high temperature conditions. This makes it possible to obtain extremely clean high-temperature plasma. According to experiments, it was possible to stably generate high-temperature plasma at a temperature of about 6,000 ℃. In addition, it has been confirmed that providing an ultrasonic mechanism around the nozzle 5 or the cooling section 13 enhances the dispersion effect of the powder raw material and is effective for high-temperature chemical reactions.

〔Effect of the invention〕

According to the present invention, by providing a nozzle at the bottom of a plasma torch that generates high-frequency induced plasma, the high-frequency induced plasma is rapidly narrowed down, making it easy to carry out various high-temperature chemical reactions, melting, and manufacturing single crystals within the nozzle. In addition, it supplies a large amount of powder raw material to a stable ultra-high temperature region without disturbing the supply of powder raw material with high-frequency induction plasma as in the past, and generates high-quality ultrafine particles, nitrides, oxides, etc. The effect is that it is possible.

[Brief explanation of the drawing]

The figure is a sectional view of a main part of a high-frequency induced plasma generation device according to an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... High frequency power supply, 2... Induction coil, 3... Inner tube, 4... Outer tube, 5... Nozzle, 7... Ignition rod,
8... Collection section, 9... Exhaust pump, 12... Electromagnet, 13... Cooling section, 14... Powder supply port, 17.
...Cooling water, 18...High frequency induced plasma, 19...
・Tail flame section, 22...Torch.

Claims (1)

[Scope of Claims] 1. A double pipe section consisting of an inner pipe and an outer pipe and having a structure in which a cooling fluid flows through the gap between the two pipes, and a double pipe section disposed in a space inside the inner pipe of the double pipe section. A high-frequency induction plasma generator comprising an ignition rod and a high-frequency induction coil disposed around an outer tube of the double-pipe section, and a nozzle configured to narrow the diameter of the space on the exhaust side of the double-pipe section. A high frequency induction plasma generation device characterized by being attached with. 2. The high-frequency induced plasma generation device according to claim 1, further comprising a cooling section attached to the exhaust side of the nozzle. 3. The high frequency induced plasma generation device according to claim 1, wherein the nozzle is provided with a powder material supply port.