JP2005209363A - Plasma torch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma torch which forms a plasma arc with a high voltage/current energized and melts a material to be melted, wherein a range of an arcing point is widened to extend service life by making a central part to be negative pressure in a wide range from an end portion of a hollow portion formed at a center of an electrode to a most recessed portion. <P>SOLUTION: The plasma torch (A) includes the cylindrical electrode 2 with the hollow portion 2a formed at its center, and a nozzle 3 which is disposed opposite to the electrode 2 and in which a jet 3a causing the plasma arc to pass through is formed. A taper portion 2b with a prefixed angle is formed at an outer peripheral portion of an end of the electrode 2, and a ring member 1 in which a three-stage slewing hole 5 through which a plasma gas passes is formed at a position opposite to the taper portion 2b is engaged with an outer periphery of the electrode 2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a plasma torch used when melting incineration ash or medical waste to detoxify it.

  By injecting a plasma arc toward the incineration ash of combustible garbage including raw garbage, the incineration ash is melted to reduce the volume, thereby improving the disposal efficiency, or by injecting the plasma arc on the mineral to melt it. In addition, a plasma arc is sprayed onto medical waste made of metal, glass, synthetic resin, etc., including stainless steel, to make it harmless by burning and melting.

  A plasma torch for generating a plasma arc used for such a purpose is composed of a hollow cylindrical copper electrode and a nozzle arranged to face the electrode, and is formed between the electrode and the nozzle. While supplying air as plasma gas to the chamber, the electrode is used as an anode and the cathode provided outside the plasma torch is energized to form a plasma arc that is ejected from the nozzle and incinerated by the heat of this plasma arc. Generally, it is configured to be able to heat and melt a material to be melted containing ash.

  In the plasma torch, when the plasma gas is supplied to the chamber formed between the electrode and the nozzle, the hollow portion formed at the center of the electrode has a negative pressure, and the plasma arc is formed at the hollow portion formed at the center of the electrode. From the surface. For this reason, the temperature of the arc generation point becomes high and partial melting damage occurs, and when this melting damage grows and reaches the limit, the life of the electrode is reached. Therefore, if the arc generation point is stagnated at one place, the life is shortened.

In order to extend the life of the electrode, the flow rate of the plasma gas is periodically changed to change the state of the negative pressure of the hollow portion formed in the electrode, and accordingly the arc generation point on the surface of the hollow portion There is a technique for moving the (see Patent Document 1, for example). However, this technique has a problem that it is difficult to periodically change the flow rate of the plasma gas while the plasma torch is operated.

  In order to solve the above problem, a plasma torch in which the ratio between the diameter of the nozzle (collimator) and the diameter of the hollow portion of the electrode is set within a certain range is proposed (for example, see Patent Document 2). This Patent Document 2 describes a plasma torch configured to be able to supply a swirl flow of plasma gas aiming at a gap formed between an electrode and a nozzle. In addition, the life of the electrode can be extended when the pressure difference between the plasma gas at the center of the electrode near the electrode outlet and the plasma gas on the wall surface is a certain value or more, and the pressure difference is between the electrode and the nozzle. It is described that it varies depending on the number of gas blowing holes for supplying a swirling flow of plasma gas.

US Pat. No. 3,673,375 Japanese Patent Application Laid-Open No. 07-17697.

  As described above, in the technique described in Patent Document 1, it is difficult to periodically change the flow rate of the plasma gas while injecting the plasma arc from the plasma torch, and the flow rate of the plasma gas is changed periodically. Even if it is changed, there is a problem that the arc generation point does not always move with this change.

  Further, in the plasma torch described in Patent Document 2, since the swirling flow of plasma gas is supplied between the tip surface of the electrode and the nozzle surface facing the tip surface, there is a limit to the amount of plasma gas supplied. There is a problem.

  The object of the present invention is to make negative pressure in the center part in the deep range from the tip of the hollow part where the center of the electrode is formed to the innermost part, thereby extending the range of the arc generation point and the service life. It is to provide a plasma torch capable of extending the length.

  In order to solve the above-described problems, a plasma torch according to the present invention has a cylindrical electrode having a hollow portion formed in the center thereof and a nozzle having a hole disposed so as to face the electrode and through which a plasma arc passes. In the plasma torch for supplying a plasma gas between the electrode and the nozzle to form a plasma arc, a tapered portion having a preset angle is formed on the outer peripheral portion of the tip of the electrode, and A ring member having a three-stage swirl hole through which plasma gas passes is fitted to the outer periphery of the electrode at a position facing the tapered portion formed at the tip of the electrode.

  In the above plasma torch, a tapered portion is formed at the tip of the electrode, and a three-stage swivel hole is formed in the ring member so as to face the tapered portion of the electrode and allow the plasma gas to pass therethrough. When the plasma gas is supplied, the swirled plasma gas flows to the tip side along the tapered portion of the electrode. This plasma gas forms a strong swirling flow at the tip of the electrode, and a strong negative pressure can be applied to the center of the hollow portion formed at the center of the electrode.

  That is, by making the swirl hole into a three-stage configuration, the plasma gas supplied from each stage toward the tapered portion of the electrode compensates for the attenuation of the flow velocity, thereby maintaining a high swirl action. For this reason, a strong swirling flow acts on the entrance portion of the hollow portion of the electrode, and the swirling flow velocity of the plasma gas in the hollow portion is improved so that a strong negative pressure can be exerted up to a deep portion.

  In particular, it is preferable that the swirl holes formed in the ring member in three stages are shifted from each other in plan view. By forming each swirl hole in this way, the plasma gas injected from each swirl hole can interact and maintain the flow velocity.

  The plasma torch according to the present invention is formed at the center of the electrode by fitting a ring member to the outer periphery of the tip of the electrode and injecting plasma gas from a swirl hole formed in three stages on the ring member. A strong negative pressure can be applied to the back side of the hollow portion, and thereby the range of the arc generation point on the surface of the hollow portion can be expanded. For this reason, the lifetime of an electrode can be extended.

  Hereinafter, a preferred embodiment of the plasma torch will be described with reference to the drawings. FIG. 1 is a diagram illustrating the overall configuration of the plasma torch. FIG. 2 is an enlarged view for explaining the configuration of the tip portion of the plasma torch. FIG. 3 is a cross-sectional view illustrating the configuration of the ring member. FIG. 4 is a diagram for explaining the configuration of the swivel hole, and is a cross-sectional view taken along a-c in FIG.

  The plasma torch A according to the present invention is used for melting a material to be melted of incinerated ash, metal, synthetic resin, etc. to reduce the volume to be disposed of or to detoxify medical waste. A gas selected from the gas such as argon gas, nitrogen gas, and air, for example, air is swirled from the ring member 1 and supplied to the chamber 4 constituted by the electrode 2 and the nozzle 3, and in this state By applying a high current to the electrode 2 and a cathode (not shown) at a high voltage, a plasma arc using air as a plasma gas is formed and ejected from the nozzle 3, and the melted material is melted by the heat of the plasma arc. is there.

  In particular, when the plasma gas is supplied from the ring member 1 to the chamber 4, the plasma gas in the chamber 4 is allowed to pass through the ring member 1 through a plurality of swirl holes 5 formed in three stages and for each stage. A strong swirling flow is applied, and thereby a strong negative pressure is applied to the back side along the central axis 6 (corresponding to the central axis of the plasma torch A) of the hollow portion 2a formed at the center of the electrode 2. It is possible.

  As described above, by applying a strong negative pressure to the back of the hollow portion 2a of the electrode 2, it is possible to expand the movement range of the arc generation point on the surface of the hollow portion 2a. It is possible to extend the lifetime by extending the range of the meltable portion of the steel.

  First, a schematic configuration of the plasma torch A according to the present invention will be briefly described. The plasma torch A has a main body 11 made of a cylindrical body, and an electrode base 12 made of a conductive pipe is provided at the center of the main body 11. The electrode base 12 is configured so that the electrode 2 can be detachably attached to the tip (left side in FIG. 1). Cooling water is supplied to the inside and the cooling water is placed around the electrode 2. The cooling water passage 13 is configured to be supplied. A cylindrical member 14 is provided on the outer periphery of the electrode table 12 so that the tip thereof reaches the vicinity of the tip of the electrode 2, and the cooling water passage 13 is defined by the cylindrical member 14.

  A cylindrical member 15 is disposed between the main body 11 and the cylindrical member 14, a plasma gas passage 16 is formed between the cylindrical member 15 and the cylindrical member 14, and the cylindrical member 15 and the main body 11 are A cooling water passage 13 serving as a cooling water return passage is formed therebetween. That is, the cooling water passage 13 is formed along the outer periphery of the electrode 2, is formed along the inner surface of the nozzle 3 after returning from the front end portion of the electrode 2, and further on the inner surface of the main body 11. A path is formed so as to be discharged from the rear of the plasma torch A along.

  A cylindrical guide member 17 is detachably fitted to the distal end portion of the cylindrical member 14, and the ring member 1 and a cup-shaped insulating member 18 are fitted to the guide member 17 on the inner periphery. A plurality of plasma gas through holes 17a are formed in the guide member 17, and the plasma gas supplied through the plasma gas passage 16 passes through the plasma lath through holes 17a, so that the ring member 1 and the insulating member 18 Is supplied to the chamber 19 formed between the two.

  A nozzle 3 is detachably attached to the tip of the main body 11. The nozzle 3 has an injection hole 3a for injecting a plasma arc at the center, and a tapered portion 3b is formed on the outer periphery, and a screw portion 3c that is attached to and detached from the main body 11 is formed. The injection hole 3 a is formed in a protrusion 3 d that is formed so as to protrude from the tip portion of the nozzle 3 toward the electrode 2.

  When the nozzle 3 is attached to the main body 11, the protrusion 3 d fits into the insulating member 18 and approaches the tip surface of the electrode 2, so that the ring member 1, the electrode 2, the nozzle 3, and the insulating member 18 form a chamber. 4 is configured.

  Next, a specific configuration of the plasma torch according to the present invention will be described. The electrode 2 is an electrode when a large voltage and a large current are energized with a cathode (not shown). By energizing the chamber 4 while supplying a plasma gas, the plasma gas is converted into a plasma arc. It has a function to inject from the injection hole 3a of the nozzle 3. The electrode 2 is made of copper or a copper alloy, and a hollow portion 2a is formed at the center.

  Although the length of the electrode 2 is not limited, in the plasma torch for melting the material to be melted, the electrode 2 is formed with a length of about 300 mm, and the hollow portion 2a is also about 280 mm. The diameter of the nozzle 3 formed on the side facing the injection hole 3a (opening side) and the diameter on the opposite side (back side) are different from each other. That is, the hollow part 2a is formed as a two-stage hollow part having a large diameter on the opening side and a small diameter on the back side.

  A tapered portion 2b is formed on the outer periphery of the tip of the electrode 2, and a stepped portion 2c, which is a portion where the ring member 1 is fitted, is formed at the base of the tapered portion 2b. The taper angle of the taper portion 2b is set to an angle such that the plasma gas injected from the ring member 1 smoothly flows to the tip surface side of the electrode 2. Such an angle is preferably in the range of about 40 to 50 degrees. For example, in the present embodiment, the taper angle of the taper portion 2b is set to 45 degrees.

  The length of the tapered portion 2b is set in a range in which the swivel holes 5 formed in three stages on the ring member 1 can face each other, and all the plasma gas injected from the plurality of swivel holes 5 is in the tapered portion 2a. It is comprised so that it may collide with either.

  The ring member 1 is formed in a cylindrical shape that can be fitted to the outer periphery of the electrode 2, a flange 1 a is formed at the tip, and a swivel hole 5 is formed over three stages from the flange 1 a to the rear side. Further, a flange-like projection 1b that engages with a step 2c formed on the outer periphery of the electrode 2 when fitted to the electrode 2 at a position spaced apart from the step at the rear end of the swivel hole 5 by a predetermined distance. Is formed. Grooves 1c for accommodating O-rings are formed at predetermined positions on the inner and outer peripheral surfaces.

  As shown in FIGS. 4A to 4C, the swivel hole 5 formed in the ring member 1 is located at a position where three pieces are divided at equal angles (120 degrees) for each step, and the tangential direction of the inner circumference. Furthermore, it is formed at a position shifted by 30 degrees for each adjacent stage. Therefore, when the turning holes 5 formed in the ring member 1 are viewed from the direction of the central axis 6, the nine turning holes 5 are formed so as to be shifted by 30 degrees.

  As described above, in this embodiment, three swirl holes 5 are formed for each stage, and nine swirl holes 5 are formed as a whole. However, in the present invention, the number of swirling holes 5 is not limited to this embodiment, and four swirling holes 5 may be formed in each stage, and a total of twelve swirling holes 5 may be formed. More may be formed.

  The electrode 2 is screwed onto and attached to the tip of the electrode base 12, and then the ring member 1 is fitted to the electrode 12, and the protrusion 1 b of the ring member 1 is engaged with the step 2 c formed on the electrode 2. Further, the plasma torch A can be assembled by fitting the insulating member 18 to the ring member 1, fitting the nozzle 3, and screwing the nozzle 3 to the main body 11.

  At this time, the swivel hole 5 formed in the ring member 1 faces the tapered portion 2 b of the electrode 2. Accordingly, when a plasma gas composed of air is supplied to the plasma gas passage 16 from a supply port (not shown) provided on the rear end side of the plasma torch A, the supplied plasma gas is swirled from the swirl hole 5 toward the chamber 4. It sprays and flows along the outer peripheral surface of the taper part 2b. For this reason, the plasma gas flows to the tip end side of the electrode 2 while maintaining strong swirling, and further flows into the gap between the tip end surface of the electrode 2 and the nozzle 3 and is strongly negative over the inner side of the hollow portion 2a of the electrode 2 It is possible to apply pressure.

  When the inventor measured the pressure at the position along the central axis 6 in the hollow portion 2a of the electrode 2 and the pressure at the wall surface of the hollow portion 2a in the above state, the pressure along the central axis 6 was The water column was about -30 mm at the innermost part of the hollow portion 2a, and the water column was about -100 mm at the tip of the hollow portion 2a. The wall pressure was about 400 mm at the innermost part of the hollow portion 2a and about 550 mm at the tip of the hollow portion 2a. These measurement results are sufficiently satisfactory compared with the performance of the conventional plasma torch.

  Further, an anode of a power source (not shown) is connected to the electrode 2, a cathode of a power source is connected to a portion having a function as an electrode (not shown) facing the plasma torch A, and a plasma gas is supplied to the plasma torch A while By energizing 2 and the cathode, it is possible to discharge between the two electrodes to turn the plasma gas into plasma and to inject a plasma arc from the injection hole 3a of the nozzle 3.

  Then, it is possible to melt the material to be melted by the plasma arc ejected from the ejection holes 3a of the nozzle 3.

  When the plasma torch A according to the present invention is used when melting incinerated ash, metal or nonmetal, it is possible to extend the life, which is advantageous.

It is a figure explaining the whole structure of a plasma torch. It is an enlarged view explaining the structure of the front-end | tip part of a plasma torch. It is sectional drawing explaining the structure of a ring member. It is a figure explaining the structure of a turning hole, and is a sectional view-c sectional view of FIG.

Explanation of symbols

A plasma torch 1 ring member 1a flange 1b projection 1c groove 2 electrode 2a hollow 2b taper 2c step 3 nozzle 3a injection hole 3b taper 3c screw 3d protrusion 4 chamber 5 swivel hole 6 central axis
11 Body
12 Electrode table
13 Cooling water passage
14, 15 Tube member
16 Plasma gas passage
17 Guide member
17a Plasma gas passage
18 Insulating material
19 rooms

Claims (1)

A cylindrical electrode having a hollow portion formed in the center thereof and a nozzle having a hole disposed so as to face the electrode and allowing a plasma arc to pass therethrough; a plasma gas is supplied between the electrode and the nozzle; In the plasma torch for forming a plasma arc, a tapered portion having a preset angle is formed on the outer peripheral portion of the tip of the electrode, and the tapered portion formed on the tip of the electrode is formed on the outer periphery of the electrode. A plasma torch characterized in that a ring member having a three-stage swirl hole through which plasma gas passes is fitted at an opposing position.

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