Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
  • H05H1/00—Generating plasma; Handling plasma
  • H05H1/24—Generating plasma
  • H05H1/26—Plasma torches
  • H05H1/32—Plasma torches using an arc
  • H05H1/34—Details, e.g. electrodes, nozzles
  • H05H1/3421—Transferred arc or pilot arc mode
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
  • B05B7/00—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas
  • B05B7/16—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas incorporating means for heating or cooling the material to be sprayed
  • B05B7/22—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas incorporating means for heating or cooling the material to be sprayed electrically, magnetically or electromagnetically, e.g. by arc
  • B05B7/222—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas incorporating means for heating or cooling the material to be sprayed electrically, magnetically or electromagnetically, e.g. by arc using an arc
  • B05B7/224—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas incorporating means for heating or cooling the material to be sprayed electrically, magnetically or electromagnetically, e.g. by arc using an arc the material having originally the shape of a wire, rod or the like
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
  • H05H1/00—Generating plasma; Handling plasma
  • H05H1/24—Generating plasma
  • H05H1/26—Plasma torches
  • H05H1/32—Plasma torches using an arc
  • H05H1/34—Details, e.g. electrodes, nozzles
  • H05H1/3425—Melting or consuming electrodes

Definitions

• the present invention relates to the field of plasma torches and more particularly plasma torches transferred arc.
• Plasma torches are used for the treatment of matter (solid, liquid or gas) at a very high temperature in an atmosphere of controlled reactivity. Plasma torches are typically used in welding, marking, thermal spraying and waste treatment.
• Plasma is a gas in the ionized state, classically considered as a fourth state of matter.
• plasma torches are used. These provide the necessary energy for the ionization of the gas by means of an electromagnetic wave (radio frequency or microwave) or an electric arc.
• electromagnetic wave radio frequency or microwave
• electric arc we will consider here only the arc torches which constitute the only technology allowing to reach important operating powers.
• Arc torches are classified into two categories: blown arc torches and transferred arc torches.
• the two electrodes for the establishment of the arc are contained in the torch and the arc is therefore confined inside thereof.
• Plasma plume created by the passage of a gas in the arc is ejected outside the torch.
• the torch comprises only one electrode and the arc is established between the torch and another material acting as a counterelectrode. Examples of arc flash and arc flash torches are described in EP-A-706308.
• Two transferred arc torches can be used in a paired fashion to maintain an arc between them, one serving as a cathode and the other anode.
• This device is known as bipolar twin torches or "twin torches”.
• twin torches is described in application EP-A-1281296. Regardless of the arc torch technology implemented, the main problem remains the short life of the electrodes.
• the object of the present invention is to have a transferred arc plasma torch having the same utilization properties as cooled electrode plasma torches but without presenting the disadvantages thereof, in particular in terms of size and complexity. mounting and maintenance.
• the present invention is defined as a transferred arc plasma torch comprising a sleeve cooled by means of a cooling fluid and an electrode inserted in said sleeve, said electrode being made of a consumable material and the torch comprising means for feeding the electrode in this material so as to compensate for its erosion.
• the means for supplying the material electrode comprise means for automatically feeding the electrode towards the distal end of the torch.
• the means for supplying the material electrode comprise means for automatically feeding the electrode towards the distal end of the torch.
• the torch comprises gaseous cladding means ensuring the cladding of said electrode by a neutral gas and plasmagene inside said sheath.
• the gaseous cladding means ensure the scanning of the electrode by said gas and its diffusion at the distal end of the electrode.
• the sheath may comprise conduits for supplying a secondary gas at its distal end, the torch comprising injection means connected to said supply ducts for injecting a gas secondary downstream of the electrode.
• the plasma torch comprises a fixed torch body supporting all of the gas connections, the cooling fluid and the power supply.
• the sheath has a tubular portion secured to a torch head and passes therethrough, the torch head resting on said torch body and cooperating with it to ensure the continuity of the gas, cooling fluid and gas flow circuits. power supply between said connectors and said sleeve.
• the tubular portion of the sheath comprises two concentric shells delimiting a cavity connected to the cooling circuit.
• a guiding and holding device may be provided so as to position the torch head on said body in a predetermined position and fix it to said body in this position.
• the assembly and disassembly will be facilitated and in particular one will avoid sealing problems resulting from a misalignment between the body and the torch head.
• the power supply of the electrode is ensured by means of at least one metal broom mounted on the head of the torch and pressing on the surface of the electrode by the action of a spring. Again, the assembly and disassembly of the electrode will be facilitated.
• Fig. 1 schematically shows a transferred arc plasma torch according to the invention
• Fig. 2 represents a detail of a transferred arc plasma torch according to the invention.
• a first idea underlying the invention is to provide a consumable electrode fed continuously material.
• a second idea underlying the invention is to protect this electrode by a sheath of neutral gas in the sheath.
• Fig. 1 shows a transferred arc plasma torch according to the invention. It comprises a support 10 referred to as a torch body, a sheath 25, preferably metal, having a tubular portion integral at its upper part with a torch head 20, a consumable electrode 30, for example a graphite electrode, a guiding device and 40, a diffuser 50, a device for advancing the electrode 60, means for electrical connection to the brush electrode 70.
• the torch body 10 constitutes the fixed part of the torch which is never disassembled and supports all the connection with the fluid circuits, gas and power supply.
• the connections are the arrival and departure of cooling water from the head and sheath, the arrival of plasma gas, the secondary gas supply and the power supply.
• the torch body comprises in its upper part a plate 11 which open the gas circuits, cooling fluid and electrical connections.
• the torch head 20 is mounted on the plate 11 of the torch body by means of a guiding and holding device 40.
• This device ensures guiding and fixing of the torch head on the torch body in a predetermined position. Guiding is provided by a guiding pin or a centering device on the support body or a combination of these means. The maintenance is for example achieved by means of a quick fastening mechanism.
• the continuity of the fluid and gas circuits between the support body 10 and the torch head 20 is provided by systems suitable seals, for example by means of seals, in particular O-rings, or by means of special connections at the plate 11.
• the graphite cylindrical electrode 30 passes right through the torch head and extends into the sheath. Its power supply is performed by a metal brush contact 70 pushed on the electrode by a spring 71. Means are provided to allow the supply of the electrode consumable material, for example by means of automatic advance placed at the level of the torch head. These means of advance are for example motorized rollers 60 with adjustable speed, coming to rest on the electrode, in diametrically opposite positions and advancing the electrode by friction towards the distal end of the torch.
• Fig. 2 more precisely describes the end of the torch head according to the invention.
• the electrode 30 is protected by the sheath 25 and the torch head 20.
• the distal end 31 of the electrode is advantageously set back from the nose 26 of the torch.
• the sheath is cooled by internal circulation of a cooling fluid 21, for example water.
• the sleeve has a tubular shape with two concentric envelopes, the cooling fluid circulating in the cavity defined by these two envelopes.
• conduits 22 disposed inside the cavity allow the supply of the secondary gas 23 to the distal end of the torch.
• the plasma torch comprises gaseous cladding means adapted to maintain a neutral and protective gas sheath around the electrode.
• This neutral gas is also used to generate the plasma.
• the gaseous cladding means ensure not only the scanning of the electrode by the neutral gas but also the diffusion of this gas at its distal or active end. Thus the electrode is protected from the external environment, especially if it is oxidizing.
• the gas cladding means comprise the gas supply circuit and the diffuser 50.
• the latter fulfills several functions: in addition to the circulation of the plasmagenic neutral gas 80 between the electrode 30 and the sheath 25 and its diffusion to the active end of the electrode, it ensures the coaxial centering of the electrode 30 relative to the sheath 25 and their mutual electrical insulation.
• the diffuser 50 may be in the form of an insulating ring provided with a flange 51 at its lower part.
• the insulating ring is held in the sleeve 25 by a metal stop ring or equivalent clipping system.
• the inner diameter of the ring is chosen so as to maintain the sheath slightly overpressure and to ensure the scanning of the electrode 30 by the neutral gas and plasmagen.
• the flange is traversed by nozzles 52 fed by the supply pipe or pipes 22 of the secondary gas so that the secondary gas is injected into the plasma zone downstream of the electrode.
• the plasma gas allows the creation of a plasma with a stable arc while the secondary gas makes it possible to obtain a plasma having the desired chemical composition or physical properties.
• argagene and oxygen secondary gas will be used as plasmagenic neutral gas.
• Such a system can be used in all applications requiring the generation of a plasma and in particular in the field of waste treatment.

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• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Plasma & Fusion (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Electromagnetism (AREA)
• Plasma Technology (AREA)
• Arc Welding In General (AREA)

Applications Claiming Priority (2)

Publications (2)

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• 2006
  • 2006-02-23 FR FR0650625A patent/FR2897747B1/fr not_active Expired - Fee Related
• 2007
  • 2007-02-20 JP JP2008555778A patent/JP5226536B2/ja active Active
  • 2007-02-20 RU RU2008137802/07A patent/RU2456780C2/ru not_active IP Right Cessation
  • 2007-02-20 WO PCT/EP2007/051618 patent/WO2007096357A1/fr not_active Ceased
  • 2007-02-20 CN CN200780006389.9A patent/CN101390454B/zh active Active
  • 2007-02-20 US US12/280,337 patent/US9686850B2/en active Active
  • 2007-02-20 EP EP07726439.8A patent/EP1994808B1/de active Active
• 2008
  • 2008-08-21 KR KR1020087020500A patent/KR101376626B1/ko active Active

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