JPS61116799A - Axial supply type large output plasma jet 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 The present invention utilizes a (portex) gas tunnel discharge, uses a hollow cathode or an electrode cylinder, and supplies substances (solid, liquid, and gas) from a central axis to control the temperature and temperature of the plasma center. This invention relates to a plasma jet generator that attempts to utilize heat effectively.

Plasma jet is a high-temperature, high-speed energy beam that is easy to operate, and its industrialization is progressing by taking advantage of its characteristics. They are plasma processed.

It is widely used in plasma chemistry (high-temperature chemical reactions), plasma melting, etc.

For example, a plasma spraying apparatus using a plasma jet as a heat source can obtain particularly high-temperature molten particles, and is suitable for producing films of ceramics and inorganic materials having a high melting point.

However, with conventional plasma spraying equipment, there are various problems with the quality of the sprayed coating that uses particles with a high melting point such as ceramics, especially the weak interparticle bonding force of the sprayed coating itself and the reduction in airtightness due to porosity. At present, there are problems such as weak adhesion between the film and the substrate, and it is currently difficult to expect a significant improvement in its quality.

The reason for this is that the thermal spray powder is supplied from a direction perpendicular to the plasma jet, making it impossible to effectively utilize the high temperature heat of the plasma to melt the powder.

However, the industrial application of conventional plasma jet is not limited to such plasma spraying.
When supplying substances in various states such as flammable gases and liquids, this is done from outside or in the middle of the plasma jet torch. With conventional equipment, electrode wear (damage)
This is because it is difficult to supply the substance from the central axis due to the adhesion of oxides to the electrodes. As a result, the heat of the plasma cannot be used effectively, the temperature of the material cannot be increased, and the speed cannot be increased.The present invention solves the above problems by using high-voltage solid, liquid,
This problem is solved by supplying gas and effectively imparting heat and temperature at the center of the plasma jet to these substances.In addition, high-temperature plasma is achieved by increasing the output of the plasma jet using gas tunnel discharge of multi-stage electrodes, resulting in high efficiency of heat conversion. The purpose is to measure the

This device allows a large flow of gas to flow tangentially into a cylindrical container, and by the action of a gas diverter nozzle,
This is an application of principle 2), which states that when a high-speed vortex is generated, a low vacuum region (so-called (portex) gas tunnel) is formed on the axis of the container. Its configuration is as shown in FIG. 1. FIG. 2 shows the vortex generation system of the present invention.

The vortex generation nozzle (3) has a plurality of (40) small holes (3-1) drilled in the tangential direction from four symmetrical locations on the circumference, and the vortex is ejected from this vortex generation nozzle into the vortex chamber (5). The gas forms a vortex and flows out from the gas diverter nozzle. In this case, in order to obtain a vortex flow with good axis symmetry,
It is preferable that there are a sufficient number of small holes with respect to the area of the inner wall circumference of the swirl chamber.In this case, the gas diverter nozzle (4
), the flow velocity components radial velocity, tangential velocity ring, and cylindrical velocity all increase toward the center, and when ejected from the gas diverter nozzle, the vortex flow of the present invention reaches the sonic velocity %. It is characterized by a non-viscous flow at the outer periphery. Furthermore, the rotation is uniform at the center including the axis. Therefore, the pressure distribution inside the swirl chamber becomes as shown in FIG. At this time, a low pressure section (gas tunnel) is formed on the center axis of the swirl chamber. The gas tunnel formed on this axis depends on the gas flow rate as well as its properties (pressure, area, etc.) depending on the shape and size of the gas diverter nozzle (3).
is determined. Therefore, in the present invention, the shape and size of the gas diverter nozzle can be easily set by replacing the gas diverter nozzle, so that it can immediately correspond to all experimental conditions. Further, in addition to rare gases such as argon and helium, nitrogen, oxygen, air, etc. can be used as the working gas for generating the gas tunnel, and the atmosphere can be easily changed.

Figure 1 shows the generation of the shaft-fed high-power plasma jet of the present invention?
This is a one-stage application of the eddy current generator (gas tunnel discharge device) (B), and it shows the principle diagram of the eddy current generator (gas tunnel discharge device) (B). A conventional plasma jet torch (A), a torch nozzle (electrode), and a vortex generation nozzle (3)
), and a gas tunnel discharge device (B) consisting of a gas diverter nozzle (electrode) (4). here,
The cathode (1) of the plasma jet/torch section is.

It is a hollow cand, and various solids, liquids, and gases can be supplied from this central shaft. The arc generated between the anode torch nozzle (2) becomes a plasma jet (6) and ejects, but when it enters the low-vacuum gas tunnel, it is suddenly concentrated and its length increases greatly. Moreover, the strong thermal pinch effect of the high-speed vortex flow due to the effect of the gas diverter nozzle (4) constrains the plasma jet and reduces its diameter, contributing to the temperature increase. Furthermore, the stability of the plasma jet is greatly improved by the high-speed vortex flow.

Furthermore, by using the gas diverter nozzle as an electrode and performing gas tunnel discharge between it and the torch nozzle, the output of the plasma jet is significantly increased. For example, when gas tunnel discharge is performed using the gas diverter nozzle as the cathode, the output of the plasma jet torch is 15 to 30 k.
200 kW or more can be easily superimposed on W.

This high-power plasma jet is characterized by extremely high voltage and stability due to the strong thermal pinch effect of the eddy current. Moreover, its thermal efficiency is also very high compared to conventional plasma jets, at over 80%.

In this case, the gas diverter nozzle electrode was used as a cathode, but it can be used as an anode by changing the power supply wiring. Further, the voltage between the electrodes can be freely set depending on the length of the vortex chamber, the inner diameter of the diverter nozzle, the type and flow rate of the vortex working gas, the pressure, etc. Therefore, it is possible to easily increase the plasma jet output.

Furthermore, the present invention includes a plasma jet generator in which eddy current generators are installed in two or three stages and a voltage is applied between each diverter nozzle and electrode. can also be measured. Therefore, a high-voltage, large-output plasma jet generator with a current of 2 kA, a voltage of 1500 V, and an output of 3 MW is also possible. In this case, the diameter of the gas diverter nozzle for the electrode needs to be gradually increased from the second stage to the third stage, taking into consideration the flow rate of the working gas.

Therefore, when materials are supplied to this device, it is possible to obtain molten material and gas particles at extremely high temperatures and high speeds compared to conventional plasma jet generators. Therefore, if this high-output plasma jet is used, the effect is very large not only when the material is supplied from the shaft, but also when the material is supplied from the middle of the plasma jet torch or gas tunnel device.

Furthermore, since the plasma jet generating device according to the present invention basically consists of a conventional plasma jet torch and a gas tunnel discharge device, the portex gas tunnel generating section is different from that of a wide variety of conventional plasma jet devices. It can be installed very easily. In this case, after plasma ignition, it is also possible to automatically replace the shaft supply device that supplies various solids, powders, flammable materials, gases, etc. to the electrode (cathode) portion of the plasma jet. In this case as well, the high-speed vortex flow reduces the diameter of the plasma jet and contributes to increasing its stability, and the length of the plasma jet increases as the particles are accelerated in the portex gas tunnel. Therefore, it is possible to obtain molten particles and gas particles at extremely high temperatures and high speeds.

The invention will be explained in detail by means of the illustrated embodiment (FIG. 4). This is a gas tunnel discharge device for a conventional plasma jet torch! (B) is the type that can be installed. A plasma jet (6) generated by a gas tunnel discharge ignited in an on-axis gas tunnel using a plasma jet ejected from a torch (11) as a seed is accelerated and at the same time strongly constrained by a high-speed eddy current. As a result, the diameter of the plasma jet decreases and its length increases significantly. After that, the plasma jet torch is connected to the shaft feeding device (11
) for thermal spraying powder (various ceramics) (10)
When the sprayed particles (13a) are supplied from the central axis direction, the sprayed particles (13a) in the plasma jet become very high-speed, and the time taken to be heated by the plasma increases, resulting in a high temperature. On the other hand, unmelted spray particles (13b
) is removed by the centrifugal force of the vortex. Therefore, compared to conventional plasma spraying equipment, the width of the sprayed coating (14) on the material (15) under the same spraying conditions decreases by several tens of percent or more, but the thickness of the sprayed coating increases by 100%. It is being In addition, regarding the quality of the sprayed coating, the number of pores is significantly reduced, the adhesion and airtightness at the interface are improved, and the hardness is also significantly increased. As a result, the quality of the thermal spray coating can be significantly improved.

As described above, in the present invention, for example, when used in thermal spraying, the quality of the thermal sprayed coating can be formed by effectively utilizing the molten particles at high temperature and high speed, so that the quality of the thermal sprayed coating can be significantly improved. This makes it possible to spray high melting point ceramics, which is difficult to do with conventional plasma spray equipment.

In addition, various objects such as rod-shaped solids, fine powders, liquids, and gases can be used as the shaft supply material, and instead of using a follower cathode, a conventional plasma jet can be used as an ignition torch, which can be replaced with the shaft supply device. In addition, it is a very effective means to supply substances in various states in the middle of the gas tunnel discharge device or from the outlet.

Furthermore, the high-output plasma jet according to the present invention has a thermal efficiency of 80% or more, compared to 60% or less in conventional equipment, and can reduce the cost of generating heat, and has good operability, so it can be used industrially. The advantages are enormous.

Literature l) Arata, Kobayashi; Patent pending, 1983-132783
High output plasma jet generator” 2) Y, ARATA; J, Ph7s, Sac
, Japan, 43. No. 31977, “
Concept of Gas Tunnel and
Appli-to High Temperature
e-Production"

[Brief explanation of the drawing]

Embodiments of the present invention are shown in the drawings. FIG. 1 is a cross-sectional view of a shaft-fed high-power plasma jet of the present invention. FIG. 2 is a cross-sectional view of a vortex generator of the present invention. FIG. 3, which shows the axial direction, shows the pressure distribution in the vortex chamber and the central gas tunnel. Further, FIG. 4 is a sectional view of an embodiment in which the present invention is applied to ceramic thermal spraying. 1. Torch center electrode (tungsten)? , Torch nozzle (water-cooled copper electrode) 3. Eddy current generating nozzle (insulating material) 3-1. Eddy current generating nozzle hole 4, gas diverter nozzle (water-cooled copper electrode) 4-1.
Gas diverter nozzle hole 5, swirl chamber 6, plasma jet 7, working gas 8, cooling water 9, insulating material 10, substances in various states (ceramic powder in FIG. 4) 11, plasma jet torch or axial feeding device 12, Cylindrical electrode 13a6 Thermal spray particles 13b heated and accelerated, Thermal spray particles 14 deviated from the central axis, Thermal spray coating 15, Material: vortex chamber diameter r'n, Gas diverter nozzle diameter: r = positive pressure) , ;)” = pressure at θ,

Claims (1)

[Claims] (a) Various states (solid, liquid, or gas) on the central axis
A shaft-supplied high-output plasma that connects a normal plasma jet device that can supply the following substances with a single-stage and multi-stage gas tunnel discharge device that utilizes a special vortex flow using various working gases, including chemically reactive gases. In addition to the functions of the jet generator (b) and (b), this is a high-output plasma jet generator that supplies materials in various states from the middle of the gas tunnel discharge device or from the exit.