RU2441353C1 - Electroarc plasmatron with steam-vortex arc stabilisation - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: electroarc plasmatron with steam-vortex arc stabilisation comprises the following coaxially and serially installed components - a water-cooled cathode unit with a screen and an insulator, an anode insert installed with an interelectrode gap and made as a hollow cylinder with helical cooling channels, and a jacket, and also a water-cooled anode unit with a solenoid. The anode insert serves as a steam generator and is equipped with a jacket and a helical cooling channel arranged between them, and also n-stage thread bores that communicate the helical cooling channel with the interelectrode gap and the inner channel of the anode insert. The anode insert and the jacket are made of metals with different coefficients of thermal expansion and are installed with a thermal gap relative to each other. The anode insert is cooled by a dosed amount of water depending on plasmatron capacity, and the cathode and anode units - with an unlimited amount of water, separately from the anode insert. Direction of current in a winding of a solenoid placed on the anode is set as equal to direction of n-stage bores on the anode insert, and to direction of plasma-generating gas swirling.

EFFECT: simplified design, increased reliability, capacity of plasmatron and plasma temperature at the outlet.

4 cl, 1 dwg

Description

The invention relates to electric arc plasmatrons operating on water vapor, and can be effectively used in plasma chemistry, metallurgy, in the destruction of rocks, metal cutting and spraying of heat-resistant coatings.

Known electric arc plasmatron (RF patent No. 21515130, IPC Н05В 7/18, 1999), according to which, for liquid stabilization, a plasma-forming gas flow swirls relative to the axis of the gas chamber is fed before the tangential fluid flow is supplied, by which it is ignited using an auxiliary discharge working arc. After the plasma-forming gas is supplied, the tangential flows of liquid are separately fed one after the other to the liquid stabilization chambers arranged in series along the axis. A gas chamber with a plasma-forming gas inlet pipe, a hollow electrode with a magnetic stabilization system and an additional electrode, which is the upper diaphragm tightly connected to it by the end face, a liquid stabilization chamber, are installed along the axis in the plasma torch case; the second liquid stabilization chamber, from the side of the lower diaphragm of which a removable anode nozzle with a magnetic arc stabilization system can be connected to the introduced catchment-divider.

The disadvantage of the plasma torch is: a complex constructive solution; the impossibility of accurate production of a given amount of steam-water plasma; unreliability of work after the gas supply from the hollow electrode is cut off; the presence of pulsations of the plasma jet due to explosive evaporation of water in the electric arc chamber and increased erosion of the electrodes as a result.

An electric arc plasmatron is also known (RF patent No. 1620032, 1989, IPC Н05В 7/22), selected for the prototype, in which dry superheated steam is generated from cooling water in the cooling channels of the cathode, anode nozzle and anode insert, and then fed to entrance to the vortex chamber. The plasma torch at startup is heated in air by feeding it into the vortex chamber. When working with steam in the design mode (t _steam = 250-350 ° С), the entire heat flux from the arc enters the cathode walls, the anode insert and the anode nozzle are returned to the plasma with the produced steam, and the thermal efficiency of the plasma torch is close to 100%. The presence of a capillary structure in the channels of the anode nozzle, made in the form of a copper displacer placed with a gap in the channel, ensures efficient evaporation of water and a pulsation-free mode of supply of dry superheated steam to the plasma torch.

The disadvantages of the prototype is that the cathode assembly and the anode with the initial section are sequentially cooled by the same water intended for steam generation. Its quantity is very limited, and the plasma torch will not be able to develop large power due to the apparent lack of water for cooling the electrode assemblies; as well as large erosion of the electrodes and arc pulsations during the transition from cold air to steam, during start-up, and the relatively low temperature of the generated plasma.

Design complexity - the prototype is equipped with two swirl chambers for air and water vapor.

The initial section of the plasma torch (anode insert) is made all-metal and, due to the large temperature difference between the internal and external surfaces, is subject to high thermal stresses, leading to structural failure.

The objective of the invention is to simplify the design, increase the reliability, power of the plasma torch and plasma temperature at the exit.

The technical result is achieved due to the fact that the arc plasma torch with steam-vortex stabilization of the arc contains a coaxially and sequentially mounted water-cooled cathode assembly with a screen and an insulator, an anode insert installed in the form of a hollow cylinder with screw cooling channels, and a jacket, as well as a water-cooled anode knot with a solenoid. According to the invention, the anode insert serves as a steam generator and is equipped with a jacket and a screw cooling channel located between them, as well as n-threaded grooves communicating with a screw cooling channel with an interelectrode gap and with an internal channel of the anode insert, wherein the anode insert and the jacket are made of metals with various coefficients of thermal expansion and are installed with a thermal gap relative to each other, while the anode insert is cooled with a dosed amount of water, depending on the plasma power throne, and the cathode and anode nodes - an unlimited amount of water, separately from the anode insert. The direction of the current in the winding of the solenoid placed on the anode is set to be the same with the direction of the n-entry grooves on the anode insert and the direction of twist of the plasma-forming gas.

The technical result in the proposed plasmatron is ensured by the fact that the heat-stressed structural parts of the plasma torch (cathode and anode) are cooled individually. Moreover, the cooling of the electrodes (cathode and anode) is not limited in the amount of water supplied and ensures the performance of the electrodes at high currents and powers. Steam-generating water is dosed only in the cooling jacket of the anode insert. It without pulsation turns with the help of a capillary structure into steam and through threaded grooves and then passes through the interelectrode gap into the plasmatron in the form of a vortex flow. Installing a solenoid on the anode body increases the life of the anode several times.

In the proposed technical solution, the anode insert moves freely in the shirt, which eliminates the occurrence of thermal stresses.

The drawing shows a longitudinal section of an electric arc plasmatron with vortex stabilization of the arc.

An electric arc plasma torch with vortex stabilization of the arc contains a coaxially and sequentially mounted water-cooled cathode assembly 1 with a screen 2, an insulator 3, an anode insert 4, which serves as a steam generator, made in the form of a hollow cylinder with a jacket 5, and a spiral cooling channel 6 with a displacer 7 is placed between them , annular receiver 8 and threaded n-entry groove 9 for swirling air and steam. The anode insert 4 and the jacket 5 are made of metals with different coefficients of thermal expansion and are cooled by a dosed amount of water based on the power of the plasma torch. A metal (wire) displacer 7 is placed in the screw cooling channel 6 of the anode insert 4 to create a capillary structure. The displacer is laid in the channel with a gap of 0.1-0.5 mm. A water-cooled anode assembly 10 is installed coaxially with the cathode assembly and the anode insert. The cathode assembly and the anode assembly are cooled separately by an unlimited amount of water. The anode insert 4 and the screen 2 of the cathode assembly 1 have sections 11 and 12 made of copper and forming an interelectrode gap 13 inclined, for example, at an angle of 30 ° <α <90 ° relative to the axis of the plasma torch. A solenoid 14 is installed on the anode casing, providing a several-fold increase in the life of the anode. The direction of the current in its winding should coincide with the direction of the threaded groove 9 and, accordingly, the direction of twist of the plasma-forming gas. The drawing shows the cathode 15 and the electric arc 16. The anode insert has a common air and water supply channel, but they are technologically separated by the supply time, which is necessary for starting the device. The magnitude of the interelectrode gap is regulated using the gaskets 17 of the insulator 3.

An electric arc plasma torch with vortex stabilization of the arc works as follows.

The start of the plasma torch begins with the air supply through the feed channel to the anode insert 4, where it, passing through the screw channel 6 with the displacer 7, warms up and then, passing through the annular receiver 8 and the n-threaded groove 9, acquires a twist and enters through the interelectrode the gap 13 in the arc chamber of the plasma torch. Then, the voltage of the power source is supplied to the cathode assembly 1 and the anode 10, and an electric breakdown of the interelectrode gap 13 is applied using an oscillator (not shown). A spark is generated along which the electric arc 16 develops. The magnetic field of the solenoid 14 substantially reduces the erosion of the anode. After a few minutes of operation of the plasma torch, when the air and the anode insert 4 are heated to 300-500 ° C, air is smoothly replaced by water, which enters the screw channel 6 with the displacer 7. Flowing through the capillary gaps of the displacer, the water effectively cools the anode insert 4, itself it heats up and evaporates smoothly without ripple. The resulting water vapor flows from the annular receiver 8 into the threaded groove 9, acquiring a twist, and through the interelectrode gap 13 enters the plasma torch in the form of a vortex stream, which stabilizes the axial position of the electric arc 16 in the electric arc chamber. Air consumption for 10-15 s is reduced to zero. Further, the plasmatron continues to operate on pure water vapor in the mode of autonomous steam generation. To protect the screen 2 and the anode insert 4 from increased wear during spark ignition of the arc, places on them where the gap is minimal are reinforced with copper inserts 11 and 12. The magnitude of the interelectrode gap is regulated by gaskets 17 on insulator 3.

The action of the anode solenoid will be positive if the direction of the current in its winding coincides with the direction of the n-threaded groove in the anode insert, as well as with the swirl direction, which it gives to the plasma-forming gas.

This technical solution allows to increase the power of the plasma torch with steam-water stabilization of the arc and the temperature of the steam-water plasma at the exit of the plasma torch.

Information sources

1. RF patent №2165130, IPC Н05В 7/18, 1999

2. RF patent No. 1620032, IPC Н05В 7/22, 1989 - prototype.

Claims (4)

1. An arc plasma torch with vortex stabilization of the arc, comprising a series-mounted water-cooled cathode assembly with a screen and an insulator, an anode insert installed with a gap, made in the form of a hollow cylinder with cooling channels, and a water-cooled anode assembly with a solenoid, characterized in that the anode insert serves a steam generator and is equipped with a jacket and a screw cooling channel, located between them, as well as n-threaded grooves communicating with a screw cooling channel with m electrode gap and with the internal channel of the anode insert, moreover, the anode insert and the jacket are made of metals with different coefficients of thermal expansion and are installed with a thermal gap relative to each other, while the anode insert is cooled by a dosed amount of water depending on the power of the plasma torch, and the cathode and anode nodes - an unlimited amount of water, separate from the anode insert. 2. An electric arc plasmatron with vortex stabilization of the arc according to claim 1, characterized in that the sections of the anode insert and the screen of the cathode assembly forming an interelectrode gap are made of copper. 3. An arc plasma torch with vortex stabilization of the arc according to claim 1, characterized in that the walls forming the interelectrode gap are made at an angle relative to the axis of the plasma torch. 4. An electric arc plasmatron with vortex stabilization of the arc according to claim 1, characterized in that the direction of the current in the winding of the solenoid placed on the anode is set equal to the direction of the n-entry ducts on the anode insert and the direction of swirl of the plasma gas.