JP2942354B2 - Transfer type arc discharge type plasma torch cooled by liquid - Google Patents

Abstract

The invention relates to a fluid-cooled plasma burner with transferred arc in which the coolant, electric power and gas are taken via ignition and main electrode lances consisting of coaxial pipes to the ignition and main electrode. To improve the design of the burner, minimise heat losses from the burner jacket and improve the burner efficiency, it is proposed to provide a common coolant circuit (41, 35, 36, 43) for the ignition (16) and main electrode (27, 28) lances.

Description

Description: TECHNICAL FIELD The present invention relates to a liquid, in which coolant, current and gas are guided to an ignition electrode and a main electrode through an ignition electrode lance and a main electrode lance made of a coaxial tube. The invention relates to a cooled transfer arc discharge type plasma torch.

BACKGROUND OF THE INVENTION A plasma torch of this type is known, for example, from DE-A 2 909 330, and comprises a torch jacket with a nozzle, a main electrode spear with a main electrode, and an ignition electrode spear with an ignition electrode. Consists essentially of components.

In the prior art, all three of the above components are individually configured and electrically isolated units with their own water cooling. Both the ignition electrode spear and the main electrode spear are individually cooled by the liquid.
Each spear consists of tubes arranged coaxially with one another.
The outer tube of the ignition electrode lance closes endwise toward the ignition electrode and contains the ignition electrode. The inner tube of the ignition electrode lance has a gap leading to the outer tube or the end face of the electrode;
This gap provides a connection between the central bore of the inner tube and the ring channel between the inner and outer tubes for the coolant.
Current is conducted through the outer tube of the ignition electrode.

The outer tube of the ignition electrode is guided via an electrically insulating spacer or sleeve into the inner tube of the main electrode lance. Via a ring channel formed between the outer tube of the ignition electrode lance and the inner tube of the main electrode lance, the ignition plasma and the main nozzle, which surrounds the ignition electrode and is shaped like a nozzle, surround the ignition electrode. It is led to the central hole of the electrode.

In the prior art, a main electrode lance consisting of three coaxially arranged tubes is used to cool the main electrode. This forms an advancing and returning ring channel for the coolant which is diverted and guided on the inner end wall of the main electrode. Depending on the configuration of the connection between the electrode and the lance, power is supplied to the main electrode via the inner tube and / or the outer tube of the main electrode lance. The electrical insulation between the outer tube of the main electrode lance, the torch mantle and the inner tube of the nozzle is:
By means of the spacer, this electrical insulation is implemented in such a way that it is realized in the manner described above with respect to the end electrode lance. Correspondingly, the main plasma gas is also directed into the area between the main electrode and the nozzle.

Known plasma torches of the prior art have the disadvantage that they are very costly in construction and result in relatively large heat losses along the torch mantle surface.

As another prior art, from U.S. Pat. No. 3,356,966, a plasma torch cooled by a gas cutting liquid is known, in which the only electrode of the torch is the ignition electrode and main electrode, The channel is cooled by a cooling liquid which is diverted over and guided through the channel.

Technical Problem The object of the present invention is to provide a plasma torch according to the opening paragraph so that its structure is simplified, the heat loss generated in the prior art is reduced, and better efficiency is obtained. To develop.

The object is to provide a common cooling circuit for the ignition and main electrode lance consisting of three coaxially arranged tubes, the coolant being supplied between the outer tube and the intermediate tube and to the intermediate tube. It is solved by being guided in a ring channel connected to each other between the inner tube and the inner tube.

This has the advantage that not only the costs for the tube and the sealing member can be saved, but also the overall cooling water supply for the plasma torch is greatly simplified. In addition to this, the diameter of the shaft of the plasma torch can be greatly reduced, which directly reduces the torch mantle surface exposed to the external temperature, i.e. reduces the heat loss of the mantle and increases the efficiency of the torch. Is improved. The small diameter of the torch shaft increases versatility in terms of the possibility of using and incorporating the plasma torch in different types and sizes of vessels, such as blast furnaces, ladle, tundish or vacuum equipment.

The main electrode lance and the ignition electrode lance consist of a total of only three coaxially arranged tubes, in which the coolant is
By being guided in the interconnected ring channels between the outer tube and the intermediate tube and between the intermediate tube and the inner tube, the main electrode is the component that needs the most cooling. Measures have been taken. In this case, the main electrode current is conducted via the outer tube and the ignition electrode current is conducted via the inner tube.

Advantageous embodiments of the invention are set out in the dependent claims. Since the ignition electrode lance is sealed to the coolant channel and electrically insulated from the main electrode lance or main electrode, the ignition gas is guided directly into the ignition electrode lance. At the same time, the ignition electrode lance is externally cooled.

A correspondingly thin but preferably highly elastic and high temperature resistant insulating tube is selected so that the cooling of the inner tube is sufficient despite the surrounding insulating tube. One or more sleeves are used to center the firing electrode lance.

The intermediate tube is continued by a substantially ring-shaped diverter in the area of the main electrode, the diverter being on the end face side so that the coolant ring channels located on both sides of the diverter are connected. Is leaving. In this case, the intermediate pipe,
The diverter and the sleeve for centering the ignition electrode lance are made of a non-conductive material, preferably a synthetic resin.

This prevents the cooling medium from lowering the resistance of the transition between the ignition electrode and the main electrode. On the other hand, the ignition electrode and the gas nozzle with which the cylindrical chamber of the ignition electrode lance communicates are electrically conductive. The nozzle efficiency of the gas nozzle is increased in that the corresponding ignition gas guide channel is guided conically outwardly, preferably in the form of a number of single holes that rejoin in the region of the main electrode or outlet.

The gas nozzle and the main electrode are connected to each other via a ring-shaped insulating sleeve. These sleeves may be made of high temperature resistant synthetic resin, pressurized liquid tight ceramic, or a composite of synthetic resin and metal ceramic. The insulating tube overlaps and seals over the gas nozzle and over a portion of the insulating sleeve to improve liquid insulation. An O-ring sealing member provided between the outer surface of the gas nozzle and the inner surface of the insulating sleeve and located in a groove provided in the gas nozzle optimizes sealing. The main electrode itself is formed in a pot shape and is conductively connected to the outer tube.
These parts are provided with an O-ring sealing member for sealing. Another O-ring closure is located in the overlap region between the insulating sleeve and the main electrode.

Advantageously, the inner tube and / or the gas nozzle are manufactured from copper. Advantageously, the ignition electrode is made of tungsten, for manufacturing technical reasons the upper conical part of the ignition electrode is cast around with copper and the casting block forms a gas nozzle.

In order to achieve as laminar a flow as possible in the flow channel for the ignition gas, the inner tube is conically widened in the lower subregion and tapered with a subsequent hole.

Next, the present invention will be described in detail with reference to the drawings based on embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view of a plasma torch of the present invention, and FIG. 2 is an enlarged longitudinal sectional view of a fixing portion of an ignition electrode.

BEST MODE FOR CARRYING OUT THE INVENTION A plasma torch has an ignition or auxiliary electrode as a main component.
11, a main or nozzle electrode 12 and a nozzle 13, each of which is electrically insulated from each other.

The ignition electrode 11 having a circular cross section has its upper conical end 1
1 'embedded in the gas nozzle 14 by the gas nozzle 14
The lance is fixed to a lance which, unlike known plasma torches, consists of only one tube 16. The hollow chamber 17, which is the cylindrical inside of the tube 16, transitions into a conical extension 14 having a taper angle γ in its lower region bordering the gas nozzle 14. The gas nozzle 14 has a large number, for example, ten holes 19 uniformly distributed around the periphery. The axis of the hole 19 is on the (virtual) conical surface 19 ′,
At the end facing the tube 16 it is more closely adjacent to each other (compared to its end facing the ignition electrode 11) and these ends are within the hollow cross section of the conical extension 18. It is arranged to be located at. The taper angle of the (virtual) conical surface 19 'is designated by β in FIG. The tube 16 is preferably made of copper, whereas the ignition electrode 11 is made of tungsten. In this case, it is recommended to manufacture the ignition electrode 11 in advance in a semi-finished product as follows. That is, the ignition electrode 11 is changed to a cone 11 'having a certain taper angle.
Beforehand to have copper, then copper by casting,
It is cast around the ignition electrode 11 with the dimensions necessary to form the gas nozzle 14. The semi-finished product manufactured in this manner is finished by processing the hole 19,
Connected to 16. The inclination angle of the hole 19 in the gas nozzle 14 (1/2 of the taper angle β) determines the position of the region cooled by the gas flow and the cooling strength. Due to the small spacing between the holes 19, the area of the gas nozzle 14 facing the tube 16 is cooled more strongly than the area facing the ignition electrode 11. Accordingly, the taper angle α of the upper conical portion 11 ′ of the ignition electrode 11 is selected such that the entire length of the connection between the gas nozzle 14 and the ignition electrode 11 is uniformly used for the current supply and heat transfer. I do.

The outside of the gas nozzle 14 is surrounded by one end of an electrically insulating sleeve 20. The other end of the insulating sleeve 20 surrounds the cylindrical flange 21 of the main electrode 12. With the gas nozzle 14 by the ring-shaped protrusion 22 inside the sleeve 20,
The main electrode 12 having the flange 21 is held at a distance from each other. Therefore, the insulating sleeve 20 is
And serves as a mechanical joining member between the main electrode 12 and the ignition electrode 11 with respect to the main electrode 12. The insulating sleeve 20 is preferably made of a high temperature resistant plastic and / or a ceramic that is dense against pressurized liquid or a combination of plastic, metal and ceramic.

The main electrode 12 has a central through hole 23, which over a partial length, in particular in the region of the cylindrical flange 21, cooperates with the outer surface of the ignition electrode 11 to form a ring channel 24. The inner diameter of the ring-shaped protrusion 22 is
And is equal to the inner diameter of the flange 21 or the through hole 23 of the main electrode 12. The entire outlet of the hole 19 lies in the plane given by this diameter.

The outside of the tube 16 is covered with a thin, high temperature resistant, highly elastic insulating sleeve 25 that can be easily attached and detached,
The insulating sleeve 25 further covers the gas nozzle 14 and a part of the insulating sleeve 20 in a ring shape. An electrically insulating coating may be provided instead of the insulating sleeve 25.

The outer cylindrical portion 26 of the main electrode 12 is capable of conducting current and is connected to the tube 28 tightly against pressurized liquid. tube
Another tube 27 is provided between 28 and the tube 16, and the lower end of the tube 27 carries a direction change portion 29.

The tubes 16, 27, 28 are hereinafter referred to as the inner tube 16, the intermediate tube 27 and the outer tube 28 because they are arranged concentrically. In this case, the inner tube 16 together with the gas nozzle 14 forms an ignition electrode lance, and the inner tube 16 and the gas nozzle 14 together with the sleeve 20 and the intermediate tube 27 and the outer tube 28 form a main electrode lance.

In order to center the inner tube 16 coaxially, a sleeve 31 made of an electrically insulating member having a through hole parallel to the axis.
The sleeve 31 is in contact with the insulating sleeve 25 on the one hand and on the inside of the intermediate tube 27 on the other hand.

The intermediate tube 27, the diverter 29 connected thereto and the centering sleeve 31 are preferably made of synthetic resin, which saves weight in addition to electrical insulation.

The gas flow for the ignition electrode 11 is provided by an ignition gas supply pipe 32,
This takes place via the cavity 17, the hole 19 and the ring channel 24. The interior of the ignition electrode lance formed by the holes 16 is cooled by the low temperature ignition plasma gas. Ignition electrode
When an ignition arc is ignited between 11 and main electrode 12, ignition plasma is ejected as a plasma jet from a central hole of main electrode 12, that is, through hole 23.

The gas flow for the main or output arc igniting the main electrode 12 and another electrode, such as molten metal, is provided by a plasma tube 33.
Via a ring channel 34 formed between the outer surface of the outer tube 28 and the main electrode 12 and the inner surface of the torch mantle and nozzle 13.

Between the inner tube 16 and the intermediate tube 27, and between the intermediate tube 27 and the outer tube 28, there are respectively provided one ring channel 35 or 36 through which the liquid coolant flows. The two ring channels 35 and 36 are connected to each other between the direction changing unit 29 and the end face of the main electrode 12. The ignition electrode lance formed by the inner tube 16 is also cooled by the cooling flow.

The ignition electrode 11 includes a gas nozzle 14, an inner tube 16, and an inner tube 16.
And electrically connected to electrodes of a current source (not shown) or a voltage source via an electric terminal 37. The main electrode 12 is connected to another electrode of a current source or a voltage source via an outer tube 28 and an electric terminal 39 arranged on the outer tube 28.

Liquid coolant for cooling both the ignition electrode 11 and the main electrode 12 is supplied to the ring channel 35 via a coolant supply pipe or inlet 41 indicated by a downward triangle, and the direction change section 29 is provided. Through the ring channel 36 and into the coolant outlet or outlet 43 indicated by the upward triangle. In this case, the inside of the outer tube 28 that guides the flow from the main electrode 12 is cooled by guiding the coolant, that is, water. In addition to this, the outer tube 28 has a ring channel facing the main electrode 12.
It is cooled by the low-temperature main plasma gas flowing through it.

A sealing member in the form of an O-ring is provided between the sleeve 20 and the gas nozzle 14 (O-ring 45), the cylindrical inner flange 21 and the main electrode 12 to seal the coolant circulation passage through the ring channels 35, 36, respectively. (O-ring 46) and between the outer flange 26 of the main electrode 12 and the outer tube 28 (O-ring 47) (O-ring 47). The O-rings 45-47 are held in ring grooves, of which, in FIG. 2, a ring groove 48 in the gas nozzle 14 for the O-ring 45,
A ring groove 49 in the sleeve 20 for the O-ring 46 is shown by way of example.

Besides the liquid coolant, the inner tube 16 is a hollow chamber of the inner tube 16
It is also cooled by the plasma gas flowing through 17.

The aforementioned plasma torch preferably operates as a three-phase AC plasma torch. Alternatively, the plasma torch can be operated with direct and / or alternating current as described in EP-A-0134961.

Reference number list 11 Auxiliary electrode (ignition electrode) 11 'Conical end 12 Main electrode (nozzle electrode) 13 Nozzle 14 Gas nozzle 16 Inner tube 17 Cavity 18 Expansion 20 Insulation sleeve 22 Projection 23 Through hole 24 Ring channel 25 Insulation tube 26 Outer flange 27 Intermediate pipe 28 Outer pipe 29 Direction conversion section 31 Sleeve 32 Ignition gas supply pipe 33 Plasma gas supply pipe 34 Ring channel 36 Ring channel 37 Electrical terminal 39 Electrical terminal 41 Coolant supply pipe 43 Coolant outlet pipe 45 O-ring 46 O-ring 47 O-ring 49 O-ring

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Tomara, Gebhard Germany 4300 Essen 1, Voltberglaude 13 (56) References JP-A-63-154273 (JP, A) JP-A-61- 88500 (JP, A) Actually open 63-57506 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) H05H 1/28 H05H 1/34 H05H 1/38

Claims (17)

(57) [Claims] An ignition electrode lance (14, 16) having a gas nozzle (14) and an inner tube (16) is formed, and the ignition electrode lance (1) is formed.
The intermediate tube (27) and the outer tube (28) are arranged coaxially outside the ring channels (35) and (36) outside of the 4, 16), and the ignition electrode is attached to the lance (14, 16). Attach (11),
Connect the ring-shaped direction changing part (29) to the intermediate tube (27), attach the main electrode (12) to the outer tube (28), and extend the ring-shaped direction changing part (29) into the main electrode (12). And main electrode (12)
And the ignition electrode spears (14) and (16) are insulated and connected by an insulating sleeve (20), thereby cooling the ignition electrode spears (14, 16) and the ignition electrode (11) from outside. To form a common cooling circuit (41, 35, 36, 43) for the igniter, and interpose a sleeve (31) between the ignition electrode lance (14, 16) and the intermediate pipe (27) to connect them. A transfer type arc discharge type plasma torch characterized by being coaxially installed. 2. An electric terminal (39) for the main electrode current is connected to the outer tube (28), and an electric terminal (37) for the ignition electrode current is connected to the inner tube (16). The transfer arc discharge type plasma torch according to claim 1, characterized in that: 3. An ignition tube for guiding an ignition gas into an inner chamber (17) of the inner tube (16) of the ignition electrode lance, wherein the inner tube (16) is a thin, highly elastic and high temperature resistant insulating tube. The transfer-type arc discharge type plasma torch according to claim 1 or 2, which is coated with (25). 4. The method according to claim 1, wherein the intermediate tube, the ring-shaped direction change portion and / or the sleeve are made of a non-conductive material. The transfer type arc discharge type plasma torch as described in the above. 5. An inner chamber (17) of the inner tube (16) of the ignition electrode lance communicates with a nozzle (14), and the gas nozzle (14) is conductively connected to the ignition electrode (11). The transfer type arc discharge type plasma torch according to any one of claims 1 to 4, characterized in that: 6. A conical upper part (1) of said ignition electrode (11).
1 ′) protrudes into the gas nozzle (14) and the gas nozzle (1
6. The transferable arc discharge plasma torch according to claim 5, wherein 4) is formed by an ignition gas guide channel (19) which is guided obliquely outward in the radial direction. 7. The inner chamber (17) of said inner tube (16) has a plurality of single holes (19) arranged symmetrically with respect to the axis of the inner tube (16) and the ignition electrode (11). 6. The method according to claim 5, wherein the single hole is guided in the area of the main electrode toward the outlet of the single hole and merges.
Or a transfer type arc discharge type plasma torch according to item 6. 8. The gas nozzle according to claim 1, wherein the gas nozzle and the main electrode are detachably connected to each other via a ring-shaped insulating sleeve. 3. The transfer-type arc discharge type plasma torch according to 1.). 9. The insulating sleeve (20) is made of a synthetic resin having high temperature resistance, a ceramic which is dense against a pressurized liquid, or a synthetic resin.
The transfer-type arc torch according to claim 8, wherein the torch is made of a united material made of metal and ceramic. 10. The method according to claim 8, wherein the insulating tube overlaps the gas nozzle and a part of the insulating sleeve and covers the gas nozzle in a sealed manner. Transfer type arc discharge type plasma torch. 11. An O-ring sealing member (45) is disposed between an outer surface of the gas nozzle (14) and an inner surface of the insulating sleeve (20), and the O-ring sealing member (45) is connected to the gas nozzle (14). ) In a corresponding groove (48) of the transfer arc discharge type plasma torch according to any one of claims 9 to 10. 12. The device according to claim 1, wherein the main electrode is formed in a pot-like shape and is conductively connected to an outer tube. Transfer type arc discharge type plasma torch. 13. At least one O-ring sealing member (47 or 46) between the main electrode (12) and the outer tube (28) and between the main electrode (12) and the insulating sleeve (20). 13. The transfer type arc discharge plasma torch according to claim 1, wherein a torch is provided. 14. A transferable arc discharge type plasma torch according to claim 1, wherein said inner tube (16) and / or gas nozzle (14) are made of copper. 15. A transferable arc discharge type plasma torch according to claim 1, wherein said ignition electrode is made of tungsten. 16. An upper conical portion (1) of said ignition electrode (11).
1 ′) is cast into a copper block forming a gas nozzle (14), in which a hole (19) converging with a conical arrangement into an inner chamber (17) is formed. The transfer arc discharge type plasma torch according to any one of claims 1 to 15, wherein the transfer type arc torch is provided. 17. A transferable arc discharge type plasma torch according to claim 7, wherein said inner tube (16) extends conically in a lower region (18).