RU2440701C1 - Combined plasmatron - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: combined plasmatron comprises a metal water-cooled chamber with longitudinal cuts, which is made from a metal pipe with wall thickness of 7-20 mm, where there are longitudinal water cooling channels, which are tightly closed at the outer side by metal pads. A quartz tube that serves as a jacket is placed onto the chamber and is installed onto detachable flanges as capable of detachment. An inducer covers a chamber and a quartz tube, besides, turns of the inducer are covered with electric insulation material. At the bottom an arched plasmatron is connected to the chamber via a gas generator, which is installed at the chamber's inlet.

EFFECT: simplified manufacturing of the plasmatron, improved conditions of its usage in the industry, higher reliability and increased resource of plasmatron operation.

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Description

The invention relates to a plasma technique, namely to the design of plasmatrons used for plasmachemical processes as a source of low-temperature plasma.

Known high-frequency induction (RFI) plasmatron containing a metal chamber formed by a set of water-cooled tubes located along the generatrix of the cylinder, in which the gaps between the tubes are covered by inserts of a dielectric heat-resistant material, an inductor covering the metal chamber and the dielectric sheath separating the metal chamber from the inductor. The dielectric sheath is made of three layers, the first of which is facing the metal chamber, is made of epoxy compound with heat-resistant dielectric hydrophilic filler, the second layer is made of organosilicon compound, and the third is made of heat-resistant dielectric hydrophilic fabric material [RF Patent No. 2142679]. The disadvantages of the plasma torch are the complexity of its assembly and low maintainability, a small resource of work. Therefore, the operation of such HF plasmatrons is unacceptable for industrial conditions.

Known HF plasmatron, selected for the prototype [Fundamentals of the theory and calculation of high-frequency plasmatrons. Dresvin S.V. Energoatomizdat. Leningra. Department, 1991, 312 p.]. The main elements of the plasma torch are: a metal chamber, consisting of water-cooled profiled tubes located along the generatrix of the cylinder, a quartz tube serving as a casing for the metal chamber, an inductor enclosing the metal chamber and the quartz tube and located concentrically with them, to which a high-frequency power source is connected. The disadvantage of this RFI plasmatron is the complexity of manufacture. The manufacture of the plasma torch chamber is carried out from individual profiled pipes welded together. In this case, the welds are located not only on the external, but also on the inner surface of the plasma torch chamber, which significantly complicates the welding. In addition, the assembly of the plasma torch chamber from individual pipes located along the generatrix of the cylinder inevitably leads to distortions of the cylindrical shape of the chamber. It should also be noted that due to the plasma ignition method used in the plasma torch (using a carbon electrode), there are difficulties in using such a plasma torch in an industrial environment. The disadvantages of the plasma torch also include the unreliable operation of the plasma torch and its low service life.

The objective is to simplify the manufacture of the plasma torch, improve the conditions for its use in industry, increase reliability and increase the life of the plasma torch.

To solve this problem, a combined plasma torch is proposed, containing a metal water-cooled chamber with longitudinal sections, which is made of a metal pipe with a wall thickness of 7-20 mm, in which longitudinal water cooling channels are made, hermetically closed on the outside with metal plates. A quartz tube is put on the camera, acting as a casing, mounted on removable flanges with the possibility of removal. The inductor covers the chamber and the quartz tube, and the turns of the inductor are covered with insulating material. Bottom to the chamber through a gas former, which is installed at the inlet of the chamber, an arc plasmatron is connected.

In the proposed design of the plasma torch, the cylindrical chamber is made immediately from a cylindrical pipe, directly into which water cooling channels are made, which are hermetically sealed on the outside by overlays. In this case, the cylindrical shape of the chamber is ensured by its manufacture from a cylindrical pipe, and the hermetic connection of the plates with the pipe is necessary only on the outside of the chamber, which simplifies the manufacture of the plasma torch chamber and improves the manufacturing accuracy.

The turns of the inductor are coated with an insulating material, such as fluoroplastic, which eliminates the occurrence of inter-turn breakdowns of the inductor during plasma ignition, which leads to increased reliability and an increased service life of the plasma torch.

The quartz tube is installed with the possibility of removal, which leads to an increase in the life of the plasma torch due to the possibility of replacing it with a new one without replacing the remaining elements of the plasma torch.

The connection of the arc plasma torch provides the creation of a laminar plasma flow designed to ignite the plasma in a metal water-cooled chamber, thereby improving the conditions for using the plasma torch in industry.

The wall thickness of the chamber pipe is made in the range of 7-20 mm. With thicknesses less than 7 mm, difficulties arise in supplying water through water cooling channels with a flow rate sufficient to remove the thermal power released in the chamber. With thicknesses exceeding 20 mm, the weight of the chamber increases excessively and the inductive coupling between the inductor and the plasma deteriorates.

The combined plasmatron (drawing) contains a metal chamber 1 made of a pipe with water cooling channels, a quartz tube 2, an inductor 3, a removable flange 4, a gas former with a fitting 5, and a transition flange 6 for connecting an arc plasmatron.

The split metal chamber 1 is made, for example, of a copper pipe with a thickness of 7 mm, 13 mm and 20 mm, in which water cooling channels are made, covered by copper plates, hermetically welded to the pipe. Quartz tube 2 is mounted on removable flanges 4. The turns of the inductor are placed inside, for example, a fluoroplastic tube. From below, a gas former with a nozzle 5 is connected to the flange of the split metal chamber, through which plasma-forming gas is supplied. From below, a transition flange 6 is attached to the gas former 5 for fastening the arc plasmatron, which creates a laminar plasma flow.

The plasma torch is used in a plasma installation to obtain a titanium dioxide nanopowder. A plasma jet with a plasma temperature in the range of 7-10 thousand K and a speed of up to 100 m / s, created by the PN-B1 arc plasma torch, with an increased diameter of the arc channel, flows into the inner part of the split metal chamber and provides ionization in it plasma forming gas. An electromagnetic field created by a 5.28 MHz current flowing through a four-turn inductor induces an annular current in the channel of the metal chamber, thereby forming an electrodeless plasma with a power of 30 kW. Water cooling of the split metal chamber removes the energy released when the induction current flows through the chamber, as well as the heat loss of the plasma transmitted to the chamber wall. After ignition of the plasma, the power supply to the DC arc plasma torch is turned off, and the jet of the arc plasma torch goes out. In this case, a jet of electrodeless plasma flows into a reactor connected to the output of the combined plasma torch. At the same time, an initial titanium dioxide powder is fed into the reactor, which evaporates in a plasma jet. After that, the resulting vapor-gas mixture at the outlet of the reactor is rapidly cooled, which leads to the formation of titanium dioxide nanoparticles.

The inventive design of a combined plasma torch is simpler to manufacture, provides improved conditions for the use of a plasma torch in industry, increased reliability and increased service life.

Claims (1)

A combined plasmatron containing a water-cooled metal chamber with longitudinal sections, a quartz tube serving as a casing for the chamber, an inductor covering the chamber and the quartz tube, a gas former installed at the inlet of the chamber, characterized in that the chamber is made of a pipe with a wall thickness of 7-20 mm, in which longitudinal water cooling channels are made, externally hermetically sealed with metal plates, inductor coils are covered with electrical insulation material, a quartz tube is installed with the possibility of w detachably to the bottom chamber through gazoformirovatel coupled arc plasma torch.