DE2501076A1 - DEVICE FOR GENERATING HIGH-TEMPERATURE PLASMA - Google Patents

Description

Patent Attorneys ₅₁ ^ _{den 11 # Jamar ig? 5}

DIPL.-1NG. BRUNO SCHMETZ Augustastraße 14-16 ■ Tel (024T) 508051

DIPL-ING. WERNER KÖNIG

LA SOUDURE ELECIRIQUE AUTOGEHE, PROCEDES ARCOS, S.A. in Brussels (Belgium)

Description of the patent application Yorrichtang for the generation of high temperature plasma

The invention relates to a device for generating high-temperature plasma with one or more plasma torches Plasma torches for superimposed arcs and means for supplying them with electrical current.

Devices for generating high-temperature plasma of this type are known. There are also already various means for Supply of the superimposed arc, i.e. the pilot arc and the power arc, of the burner (s) of such Electric current devices.

So it is known to feed the ignition arcs with direct current, in such a way that an uninterrupted ionization of the plasma-generating gas is guaranteed, and to cause the power arcs to be fed with alternating current, to achieve increased performance.

In the known devices, the alternating current 3'e can take a different path after its formation. So can in the case of a device with a plasma torch, they run between the latter and a workpiece to be treated by the same.

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Furthermore, it can be used in devices with plasma torches in opposite directions or in a star-shaped arrangement, which serve to generate very high temperatures, its way through those generated by the burners and encountering between them Take plasma flames.

There are also known plasma torches which are used individually, and in general for cutting purposes, and their Power supply either from two independent power sources (Belgian patent 623 218, USA patent 2 945 119 and German patent application P 18 07 960.2) or by a single direct current source (USA patents 2,862,099 and 3,612,807) will, in the latter case due to resistances and shunts different powers are supplied to the arcs.

It is also already known for the supply of plasma torches by means of a single direct current source, by means of a high-frequency oscillator, which is located in a bypass line inside the burner for a period of time during the ignition period, to feed an arc with alternating current (USA patent 3 450 926).

In devices with multiple plasma torches, there is usually a single single-phase or three-phase AC power source for the Supply of the power arcs provided, in the case of a three-phase alternating current source generally from each burner a phase is claimed. The ignition arcs are fed in devices of this type by means of mutually independent direct current sources, a current source being provided for each burner see Belgian patents 623 218 and 755 and French patent 1,469,629 such devices are very special.

So much for the known devices for supplying the ignition arcs and power arcs each have two or more power sources

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are needed, the disadvantage here is that it increases the cost and the space required for them can be increased. If alternating currents with increased voltage are used in the devices, this results in these the further disadvantage that a sufficient insulation of the two circuits, namely the direct current circuit and the AC circuit, must be provided.

The invention is based on these and other disadvantages to fix the known devices.

To this end, the invention provides for a device of the type mentioned at the beginning Kind before that to feed the superimposed arcs, i.e. the ignition arc and the power arc, the plasma torch or the plasma torch only use a single source of alternating current is provided and that this alternating current source also provides the direct current for the ignition arc of the plasma torch or the plasma torch supplies.

This design of the new device ensures that only a single power source, namely an alternating current source, for the supply of the superimposed arc of the plasma torch or the plasma torch of the same is required, and that but the ignition arc of every plasma torch with direct current can be fed while the power arc is fed by means of alternating current.

According to the invention it is also provided in the new device that in the presence of a plasma torch to feed the ignition arc with direct current a section of the secondary side of an alternating current transformer is provided with a bypass line is, in the two branches following the transformer there is a rectifier each and which is connected to the Rectifier is connected to an electrode of the plasma torch via another line, and that for this purpose continues from the center of the said section of the secondary side of the transformer from another line leads to the other electrode of the plasma torch.

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Looks similar as well as other features for the arc feed the invention for embodiments of the new gate direction before which these two plasma torches, which are arranged in opposite directions at the opposite ends of a furnace with arc plasma heating or have three plasma torches arranged in a star shape. ■

In all embodiments of the new door direction there is according to the invention the possibility of switching the rectifier according to the desired polarity of the plasma torch electrodes.

Also according to the invention in all embodiments of the new door direction it should be provided that the intensity of the currents used can be regulated independently of one another and that one Phase control takes place between the direct current or the direct currents and the alternating current.

In the drawing, the gate direction is for the generation of high temperature plasma according to the invention, for example and illustrated schematically, namely show:

Pig. 1 a gate direction with a plasma torch aimed at a workpiece

2 shows a gate direction with two plasma torches which are arranged in opposite directions at the ends a furnace with arc plasma heating and

3 shows a door direction with three arranged in a star shape Plasma torches.

In the door direction according to FIG. 1, the plasma torch P .. a cathode 1, which is formed by a solid electrode, and an anode 2, which is a nozzle electrode. The plasma jet 3 generated by the plasma torch P .. is on Workpiece 4 directed, which serves as a further electrode.

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Burns in between the solid electrode 1 and the nozzle electrode 2 Ignition arc while moving from the nozzle electrode 2 to the workpiece 4 extends a lexstungslxchfbogen. Through these arcs and one through the nozzle electrode 2 in the direction of the workpiece 4 The plasma flame 3 is generated by the gas flow passing through.

An alternating current transformer, of which only its secondary side 5 is shown, is used to feed the ignition arc and the power arc of the plasma torch P _{1 with electrical current.} The section located between points A and B at one end of the secondary side 5 of the transformer is provided with a shunt line 6. This shunt line has two branches 6a and 6b following the transformer, in each of which a rectifier 7, 8 is located. Following the rectifiers 7, 8, the two branches 6a and 6b of the shunt line 6 are connected via a further line 9 to the solid electrode 1 of the plasma torch P ₁ . A further line 11 extends from the middle 10 of the secondary side section AB of the transformer to the nozzle electrode 2 of the plasma torch P ..

With this circuit, the ignition arc of the plasma torch P. is supplied with direct current, whereby due to the design and arrangement of the rectifiers 7, 8 on the solid electrode 1 always the negative pole and on the nozzle electrode 2 always the positive pole is, making the solid electrode 1 the cathode and the nozzle electrode 2 is the anode of the plasma torch P. Apart from this, the circuit causes the rectifiers to have a double rectifying effect, i.e. one rectification of the alternating current takes place over the entire length or duration of its periods.

From point C at the other end of the secondary side 5 of the transformer, another line 12 extends to the workpiece 4. The power arc of the plasma torch P _{1 is generated via this line 12 and the line 11 leading to the nozzle electrode}

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fed with alternating current from the secondary side 5 of the transformer.

In the device according to Pig. 2 are two plasma torches P " intended. These two plasma torches Pp, P, are located in opposing arrangement at the opposite ends of a rotary melting furnace 13 with arc plasma heating according to the Belgian U.S. Patent 779,116 and U.S. Patent 3,578,943.

According to the apparatus of FIG. 1, each has a plasma torch Ρ «, P- a cathode 1, which is from a solid electrode is formed, and an anode 2, which is a nozzle electrode. The nozzle electrodes 2 are at the ends of the furnace 13, while the massive electrodes 1 with Distance from and axially to this. The plasma flames 3 generated by the plasma torches Pp, P- extend into the Furnace chamber 14 and meet in the middle.

As with the device according to FIG. 1, the plasma torches burn Pp, P- between the solid electrodes 1 and the nozzle electrodes a pilot arc. Furthermore, in the device, a power arc extends inside the furnace chamber 14 through the plasma flames 3 from the nozzle electrode 2 of one burner to the nozzle electrode 2 of the other burner.

An alternating current transformer 15 is used to feed the ignition arcs and the power arcs of the plasma torches Pp, P- * with a primary side 16 and a secondary side 17.

For the supply of the ignition arcs the burners P ", P, are connected to the both ends of the secondary side 17 of the transformer 15 in a symmetrical arrangement with respect to the secondary side center for each burner Pp, P, corresponding switching elements as at the device of FIG. 1 is provided. These switching elements therefore also have a corresponding effect as in the case of the device according to FIG. 1 achieved.

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The power arc is supplied with alternating current at of the device in question from the secondary side 17 of the Transformer 15 from across the from the center 10 of the secondary side sections A-B from lines 11 leading to the nozzle electrodes 2.

In the door direction according to FIG. 3, three are arranged in a star shape Plasma torches P., P ^ - and Pg provided in one of the devices of the Belgian PaiHites 735 091 and the USA patent 3 578 943 corresponding to Art.

In this device, as in the devices of Fig. and 2, each burner P., Pj- and Pg a cathode 1, which of a solid electrode is formed, as well as an anode 2, which is a nozzle electrode. The solid electrodes 1 are each arranged on the outside and the nozzle electrodes 2 on the inside of the device. Also, the arrangement is of electrodes 1 and 2 in such a way that the plasma flames 3 generated by the plasma torches are directed at a central intersection are where they meet.

As with the devices already described, there is a fire between the solid electrode 1 and the nozzle electrode 2 of each plasma torch P., Pj-, Pg an ignition arc. Furthermore, each extends from the nozzle electrode 2 of a torch to the nozzle electrode 2 of a another torch a power arc.

To supply the ignition and power arcs, the The device in question is a three-phase AC power source with three primary sides 18, 19, 20 and three secondary sides 21, 22,

To feed the ignition arcs of the burners P., Pp- and Pg, respectively at one end of each of the three secondary sides 21, 22, 23 of the current source corresponding switching elements as in the device according to Pig. 1 provided. These switching elements therefore also provide a corresponding power supply for the ignition arcs Effect as achieved with the device according to FIG. 1.

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For the supply of the power arcs with alternating current extends From the other end of each of the three secondary sides 21, 22, 23 of the power source, a line 24 extends to the nozzle electrode 2 of the counterclockwise direction neighboring burner Pg, P ^ or P ..

Via the burners P>, Pg or Pg, P ^ or P ^, P. leading from the secondary side 21, 22, 23 to the nozzle electrodes 2
Lines 11 and 24 as well as those emanating from these burners
Plasma flames 3 are therefore also closed the circuits for the power arcs.

In the device of FIG. 1, starting from a
AC mains with 220 V, an alternating current of 2.4 A and 215 "V for the power arc and a direct current of 1 A and 80 V for the pilot arc.

Is one of the devices shown independent of each other If it is desired to regulate the intensity of the currents used, this can be done in one of the shunt lines an amplifier is installed.

In order to provide phase regulation between the direct current or the direct currents and the alternating current, the circuit
a phase shift device can be installed. This makes it possible to achieve a maximum of the ionization of the gas flows caused by the ignition arcs when the voltage
of the alternating current for the power arcs has a zero crossing.

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Claims (1)

_ 9 - Claims J Device for generating high-temperature plasma with a Plasma torches or several plasma torches for superimposed arcs and means for supplying them with electrical current, characterized in that for feeding the superimposed arcs, i.e. the ignition arc and the power arc, the plasma torch or the plasma torch is only a single alternating current source is provided and that this alternating current source also provides the direct current for the ignition arc of the plasma torch or the plasma torch supplies. 2. Apparatus according to claim 1, characterized in that in the presence of a plasma torch (P ₁ ) for feeding the ignition arc with direct current, a section (AB) of the secondary side (5) of an alternating current transformer is provided with a shunt line (6), in both of which branches (6a, 6b) following the transformer are each a rectifier (7, 8) and which is connected to the rectifier (7, 8) via another line (9) with an electrode (1) of the plasma torch (P ₁ ) is in connection, and that for this purpose a further line (II) leads to the other electrode (2) of the plasma torch (P ₁ ) from the middle (10) of said section (AB) of the secondary side (5) of the transformer. 5. Apparatus according to claim 1, characterized in that in the presence of two plasma torches (Pp, P,) which are in arranged in opposite directions at the opposite ends of a furnace (13) with arc plasma heating, for supply the ignition arcs of the same with direct current at the two ends of the secondary side (17) of an alternating current transformer (15) in symmetrical arrangement with respect to the secondary side center for each plasma torch (Pp, P,) according to claim 2, one each Shunt line (6), two rectifiers (7, 8) and lines (9, 11) leading to the burner electrodes (1, 2) are provided 509836/0266 2 5 Q1 0 7 6 and that the alternating current circuit for feeding the power arcs over that of the center (10) of the secondary side sections (A-B) to the burner electrodes (2) filling lines (11) and the plasma flames (3) that meet in the furnace chamber (14) are closed is. 4. Apparatus according to claim 1, characterized in that in the presence of three star-shaped plasma torches (P., P ₁ -, Pg) and a three-phase alternating current source for supplying the ignition arcs with direct current, each of the three secondary sides (21, 22, 23) of these AC power source for each plasma torch (P., P (-, Pg) according to claim 2 has a loom line (6), two rectifiers (7, 8) and connecting lines (9, 11) to the burner electrodes (1, 2) and that for the supply of the power arcs with alternating current each of the three secondary sides (21, 22, 23) of the alternating current source is connected to an electrode (2) of two adjacent plasma torches (P., Pg or Pg, P ^ or P ^, P.) is. 5. Device according to one of claims 1 to 4 »characterized in that that the rectifiers (7, 8) of the desired polarity of the plasma torch electrodes (l, 2) are connected accordingly. 6. Device according to one of claims 1 to 5> characterized in that that the intensity of the currents used can be regulated independently of one another. 7. Device according to one of claims 1 to 6, characterized in that that a phase control is provided between the direct current or the direct currents and the alternating current. 50 9 8 36/0266 Blank page