JPH0311598A - Plasma torch and its operating method - Google Patents

Abstract

PURPOSE:To improve the heat utilizing efficiency of plasma by leading in an electric conductive liquid to an inside electrode in the direction of the tangent, and generating a plasma arc in the condition that a thin liquid film is formed over the inner surface of the electrode. CONSTITUTION:A liquid for cooling with an electric conductibility is led into an inside electrode 1 from a liquid feeding port 11 at the rear end of the inside electrode 1 at a high speed. As the result of the rotation movement of a high speed, the liquid forms a thin liquid film over the inner surface of the electrode, realizing a whole surface covering condition. After the cooling of the inner surface of the inside electrode reaches to a normal condition, the plasma gas 8 is blown in through a gas leading-in hole 10 provided at a vortex generator 2 to form a vortex flow 5. A transfer type plasma arc 6 is generated by driving a plasma driving device while making the inside electrode 1 as the arc generating point and making an external electrode 7 provided at the outside of the torch as the arc reaching point. In this case, the arc generating point is at the surface of the liquid for cooling with the electric conductibility, and the electrode is cooled effectively.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a plasma torch used in metal smelting and energy-related fields and a method of operating the same.

[Conventional technology] Plasma technology is widely used in many industrial fields.

It is often used for scouring, welding, and cutting metals, and as a compact heat source. However, it cannot be denied that operation and maintenance requires a certain amount of work and cost.

For example, US Patent No. 3.673.37
The plasma torch disclosed in No. 5 is as shown in FIG. The principle of this plasma can be explained as follows according to this diagram.

The torch is composed of an internal electrode 1, a portex generator 2, an insulator 3 J3, and a collimator 4. The other electrode to the one-way electrode is an external electrode 7 placed in front of the torch. The gas introduction holes 8 provided in the portex generator 2 are perforated in a direction along the circumferential direction of the torch inner hole 9 shown by the broken line.

When gas is introduced through the gas introduction hole 8, the introduced gas forms a vortex flow along the torch inner hole and separates into two hands at the introduction position. One of the gases advances toward the front of the torch, passes through an insulator 3 and a collimator 4, and is discharged to the outside of the torch. The other gas returns inside the internal electrode to the rear of the torch, turns around at a position where the pressure is balanced, passes through the center of the vortex, advances to the front of the torch, and is discharged to the outside. The inner surface of the electrode at this folded position serves as an arc generation point, and the plasma arc rides the returning gas flow to the center of the vortex where the gas pressure is low, forming an arc that reaches the external electrode.

In this plasma torch, the blowing pressure of plasma gas is changed periodically between the upper and lower set values, the turning point of the gas is changed in the front and back direction of the internal electrode, and the gas forms a vortex, which causes the arc generation point to be changed. is rotated so that the arc generation point changes uniformly over the entire inner surface of the internal electrode.

Voltage changes in a plasma arc cause a significant electrode drop at the point of origin and arrival of the arc, resulting in large heat generation. Therefore, the heat causes melting damage at the arc generation point or arrival point.

Furthermore, the generated heat is removed from the system by the cooling water of the electrodes, which significantly reduces the heat utilization efficiency of the plasma.

Also in the plasma torch of the above US Patent No. 3.673.375, the wear and tear of the internal electrodes is large;
Inspecting for water leaks, replacing torches, and cooling loss of electrodes, etc.
There were problems in terms of utility, cost, and power consumption, which was a bottleneck to industrialization.

[Problem to be solved by the invention 1 The present inventors aim to improve the life of the electrode of a plasma torch, reduce the utility burden, and further reduce the electric power consumption.
We have developed a new plasma torch structure and operating method based on the basic principles of plasma.

The present invention aims to provide such a new technology.

fMeans for Solving the Problems] The present invention provides a technology that basically solves the above problems, and includes a gas blowing device that forms a vortex in the internal electrode of a torch, a metal cylinder that forms the internal electrode, and In a transition type plasma torch, which consists of a plasma torch main body consisting of a collimator located at the exit of the plasma arc, and an external electrode installed outside the torch main body, there are internal electrodes near the rear end and near the front end of the internal electrode, respectively. Features include a liquid supply port and a liquid drain port that open in the direction of the circumferential line, an insulating ring wall with a narrowed inner diameter at the front end of the internal electrode, and a sealed insulating material at the rear end of the internal electrode. It is a plasma torch with a

The method of operating this plasma torch is as follows. First, an electrically conductive liquid is introduced into the internal electrode from the v37pi port, and after forming a thin liquid film on the inner surface of the electrode to cover the entire inner surface, the liquid is discharged from the drain port to balance with the supplied liquid. to keep the entire surface of the electrode covered in a steady state, and after the steady state is established, 1--
A plasma arc is ignited by blowing gas into the chamber to form a vortex, and a plasma arc is generated between the internal electrode and the external electrode.

[Function] The device of the present invention has a simple structure, long life, and low power consumption. Using this device, operation with high plasma heat utilization efficiency can be easily performed.

[Embodiment 1] An embodiment of the present invention will be described in detail with reference to FIG. 1st
The figure is a longitudinal sectional view showing the configuration of a plasma torch in the present invention.

The plasma torch main body is composed of an internal electrode 1, a portex generator 2, an insulator 3, and a co-J meter 4 - and the function of the internal electrode is different from that in FIG.

In the present invention, a cooling liquid supply port 11 and a liquid drain port 2 are provided at two locations near the rear end and near the 111-side end of the internal electrode, which are perforated along the inner circumferential direction of the electrode. Further, the front end of the internal electrode is provided with an insulating ring 13 having a small inner diameter.

On the other hand, the rear end of the internal electrode is sealed with an insulator 9.

In the apparatus of the present invention, when an electrically conductive cooling liquid such as water is used, it is water to which salts or organic substances are added to increase ionic conductivity. Such a liquid is introduced into the internal electrode at high speed through the liquid supply port 11 at the rear end of the internal electrode. As a result of the high-speed circular motion, the liquid forms a thin liquid film on the inner surface of the electrode, achieving full coverage. On the other hand, a ring wall 13 is provided at the front end of the internal electrode to prevent the liquid from flowing out to the outside of the electrode. The liquid introduced from the liquid supply port 11 is discharged from the liquid drain port I2 while maintaining balance.

After the inner surface of the internal electrode has cooled to a steady state, plasma gas (for example, air) 8 is blown through the gas introduction hole 10 provided in the portex generator 2 to form a vortex flow as in the case of FIG. A transition type plasma actuator (not shown in FIG. 1) is activated to generate plasma, with the internal electrode as the arc generation point and the external electrode 7 provided outside the torch as the arc arrival point.
5 to J[≧.

In this case, the arc generation point is on the surface of the electrically conductive cooling liquid, and the high temperature and large amount of heat generated by the electrode fall is directly cooled by the liquid and becomes the latent heat of evaporation of the liquid, which further causes dissociation and ionization of the liquid. It is used to promote That is, the evaporated liquid forms part of the plasma gas, and the energy corresponding to the electrode fall is included in the plasma arc and output to the outside of the torch.

As a result, only a small portion of the amount of heat required for cooling the electrode is removed from the system as a rising vortex of the cooling liquid, and the thermal efficiency of the plasma torch is significantly improved.

Furthermore, with conventional torches, the life of the torch was significantly reduced due to melting of the arc generation point, and the electrode consumption rate increased, but in the plasma torch of the present invention, the arc generation point is protected by being coated with a cooling liquid. Therefore, the electrode itself hardly suffers from melting and damage, and the electrode can be used almost semi-permanently.

In the present invention, as in the prior art, the blowing pressure of the plasma gas is changed periodically between the set value of 1 and lower, and the turning point of the gas is changed in the front and back direction of the internal electrode, and the arc generation point is set on the entire inner surface of the internal electrode. It is necessary to vary uniformly across the range. This is because when the scum concentrates in one place, the liquid film breaks,
This is because the effects of the present invention described above will be impaired.

When air is used as a plasma gas, a large amount of NOx is usually generated, which must be dealt with separately using other means. However, in the present invention, if water is used as the cooling liquid, the water will dissociate into N2 and 02, and the ionized I]+ will reduce the generated NOx and return it to N2 and 02, so if air is used as the plasma gas, However, a plasma arc that does not contain NOx can be obtained.

〔Effect of the invention〕

Since the plasma torch according to the present invention has the above-mentioned configuration, it can be suitably used in the method of the present invention, and a) heat utilization efficiency of plasma is improved.

Mouth) The plasma torch has a long lifespan.

c) Air can be used as the plasma gas, and in this case, the generation of NOX is suppressed.

It has excellent effects such as

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention, and FIG. 2 is a perspective view of a conventional example. ■--Internal electrode 2--Portex generator 3--Insulator 4--Collimator 5--
Eddy current 6...-Plasma arc 7...-External electrode 8...Plasma gas 9...Insulator 10...Gas introduction hole 0 l 1...-Liquid supply port 2...Drain port 13...- Agent for Ring Applicant Saki Steel Co., Ltd.

Claims (1)

[Claims] 1. A gas blowing device that forms a vortex in the internal electrode of the torch;
In a transitional plasma torch, which consists of a plasma torch body consisting of a metal cylinder forming an internal electrode and a collimator located at the exit of the plasma arc, and an external electrode installed outside the torch body, the rear end of the internal electrode A liquid supply port and a liquid drain port are provided in the vicinity and near the front end, respectively, which open in the transverse direction of the inner circumference of the electrode, and an insulating ring wall with a narrowed inner diameter is provided at the front end of the internal electrode, and the rear end of the internal electrode is insulated. A plasma torch characterized by being sealed with an object. 2 Using the plasma torch according to claim 1, an electrically conductive liquid is introduced into the internal electrode from the liquid supply port, a thin liquid film is formed on the inner surface of the electrode to cover the entire inner surface, and the supplied liquid is introduced from the liquid drain port. The liquid is discharged to maintain a constant state of full coverage of the inner surface of the electrode, and then gas is blown into the torch from the gas blowing device to form a vortex, igniting the plasma arc, and discharging the inner and outer electrodes. A method of operating a plasma torch characterized by generating a plasma arc between the torch and the plasma torch.