WO2008038886A1

WO2008038886A1 - Plasma arc torch and scrubber using the same

Info

Publication number: WO2008038886A1
Application number: PCT/KR2007/002808
Authority: WO
Inventors: Sung Min Moon; Jae Kyu Kim; Dae Yong Kim; Hee Geun Oh
Original assignee: Korea Pionics Co., Ltd.
Priority date: 2006-09-28
Filing date: 2007-06-11
Publication date: 2008-04-03
Also published as: TW200820838A

Abstract

Provided are a plasma arc torch and a scrubber using the same. The plasma arc torch includes a cathode rod for discharging a thermal electron depending on an applied voltage, a first anode electrode spaced apart from the cathode rod by a predetermined distance and generating arc discharge when the voltage is applied, and a second anode electrode disposed under the first anode electrode, maintaining transfer arc discharge generated from the cathode rod and the first anode electrode to process waste gas, and having better thermal resistance than the first anode electrode. In addition, the scrubber using a plasma arc torch includes the plasma arc torch, a chamber for providing a closed space under the plasma arc torch to purify the waste gas and having a discharge port for discharging the purified waste gas, and a cooling part coupled with a lower side of the chamber and cooling the chamber.

Description

Description PLASMA ARC TORCH AND SCRUBBER USING THE SAME

Technical Field

[1] The present invention relates to a plasma arc torch and a scrubber using the same, and more particularly, to a plasma arc torch for generating a high temperature flame through arc discharge and a scrubber for processing waste gas using the flame generated from the plasma arc torch. Background Art

[2] In general, a plasma arc torch converts a plasma generating gas into a plasma state to generate a high temperature flame using arc discharge between a cathode electrode and an anode electrode. The plasma arc torch can also control a temperature of the flame.

[3] As described above, since the plasma arc torch generates flame caused by arc discharge between the two electrodes, a high temperature flame is inevitably generated from a portion in contact with one electrode, and the electrode is likely to be damaged by the flame and the arc discharge.

[4] Most conventional plasma arc torches use a copper anode electrode, and while there may be structural differences, these will be described in detail with reference to the accompanying drawings showing the conventional plasma arc torches.

[5] FIG. 1 is a schematic cross-sectional view of a conventional plasma arc torch.

[6] Referring to FIG. 1, the conventional plasma arc torch includes a cathode rod 1 having a sharp tip formed at its one end, a body 2 in which pipes such as a cooling water circulation pipe (not shown) and so on are disposed and supporting the cathode rod 1, a ring-shaped anode electrode 3 coupled with the other end of the body 2, and a plasma gas introduction pipe 4 for introducing a plasma gas between the anode electrode 3 and the cathode rod 1.

[7] The cathode rod 1 and the anode electrode 3 are spaced apart from each other by a predetermined distance. When a potential difference exists between the cathode rod 1 and the anode electrode 3, arc is generated between the sharp tip of the cathode rod 1 and the anode electrode 3.

[8] In contrast to another discharges, the above arc discharge is performed in such a way that thermal electrons are discharged from the cathode rod 1 to cause strong current to flow between the anode electrode 3 and the cathode rod 1 in a state that a potential di fference between the anode electrode 3 and the cathode rod 1 is low. At this time, a space between the cathode rod 1 and the anode electrode 3 is in a plasma state.

[9] The current flow is continuous, and a temperature of the plasma is within a range of

3000 to 6000⁰C. [10] Especially, a temperature adjacent to the anode electrode 3 is high, and an electrode material is partially sublimated. [11] The plasma gas supplied between the cathode rod 1 and the anode electrode 3 through the plasma gas introduction pipe 4 is converted into a plasma state to generate flame caused by a high temperature. [12] FIG. 2 is a view showing movement of arc in a conventional transfer- type plasma arc torch, enlarging portion I of FIG. 1. [13] Referring to FIG. 2, in the conventional transfer- type plasma torch, arc is generated by discharging electrons to a proximity point A of the anode electrode 3 most adjacent to the sharp tip of the cathode rod 1, and the arc vertically moves along an arc holding surface B of the anode electrode 3. [14] As described above, since a high temperature is generated adjacent to the anode electrode 3 of the plasma arc torch, the anode electrode 3 is likely to be damaged.

Therefore, the anode electrode 3 should be replaced with a new one after a short period of about fourteen hours. [15] Especially, the arc holding surface B along which the generated arc moves, except the proximity point A, is likely to be damaged such that the anode electrode 3 damaged to be replaced has a ring-shaped part, in which only a portion around the proximity point A exists. [16] As described above, since the conventional plasma arc torch uses the cathode rod 1 formed of tungsten and the anode electrode 3 formed of copper, lifespan of the anode electrode 3 may be reduced to increase maintenance cost. [17] In addition, a scrubber, to which the conventional plasma arc torch is adapted, should stop processing waste gas at every short exchange period of the anode electrode 3 of the plasma arc torch.

[18] FIG. 3 is a schematic cross-sectional view of another conventional plasma arc torch.

[19] Referring to FIG. 3, another conventional plasma arc torch is similar to the conventional plasma arc torch, except that an exterior part of the anode electrode 3 is expanded outward. [20] When the above constitution is adapted to the plasma arc torch or a scrubber, flow rate of waste gas may be increased more than that of FIG. 1 to process a larger amount of gas. [21] However, in the above gas supply structure, non-direct exposure of the gas to the arc discharge may cause a decrease in efficiency. [22] FIG. 4 is a schematic cross-sectional view of a conventional scrubber using a plasma arc torch. [23] Referring to FIG. 4, the conventional scrubber includes a plasma arc torch 10 for heating waste gas to purify the waste gas, a discharge port 30 for providing a waste gas processing space by the plasma arc torch 10 and discharging the purified gas to the exterior, a chamber 20 having an opened bottom, and a cooling part 40 coupled with the opened bottom of the chamber 20, having a cooling water supply port through which a cooling water is supplied, heat exchanging the supplied cooling water, and discharging the cooling water to a lower center.

[24] Hereinafter, constitution and operation of the conventional scrubber using a plasma arc torch will be described in detail.

[25] The conventional scrubber using a plasma arc torch functions to purify waste gas using heat generated from the plasma arc torch shown in FIG. 1 or 3. The waste gas is supplied through the plasma gas introduction pipe 4 described in FIGS. 1 and 3, and the waste gas is processed by arc discharge generated due to a potential difference between the cathode rod 1 and the anode electrode 3.

[26] That is, the arc discharge increases an ambient temperature of the anode electrode 3 to a high temperature to convert the ambient air into a plasma state, and the waste gas supplied through the plasma gas supply pipe 4 as the waste gas supply pipe is purified by flame generated around and adjacent to the anode electrode 3.

[27] In order to maintain an environment in which the purification is performed, the plasma arc torch 10 is fixed to the chamber 20 to secure a purification space in the chamber 20. The purified waste gas is discharged to the exterior through the discharge port 30 of the chamber 20.

[28] In this process, the temperature in the chamber 20 is increased, and, in order to cool the chamber 20, the cooling part 40 is installed at a lower end of the chamber 20.

[29] The cooling part 40 includes a cooling water introduction pipe 41 through which cooling water is introduced, a circulation part 42 for circulating the cooling water introduced through the cooling water introduction pipe 41 along the lower end of the chamber 20, and a center discharge pipe 43 for discharging the cooling water supplied into the circulation part 42 and overflowed therefrom to the exterior.

[30] In the cooling part 40, a certain amount of cooling water is continuously supplied through the cooling water introduction pipe 41, the cooling water overflowed from the circulation part 42 is discharged to the exterior through the center discharge pipe 43, and the cooling chamber 20 is cooled by the cooling water newly and continuously supplied into the circulation part 42.

[31] Though the plasma arc torch 10 should also be cooled, since the plasma arc torch 10 has a self-cooling structure, there is no separate cooling apparatus.

[32] In the conventional scrubber using a plasma arc torch, dust generated during a waste gas treatment process may be deposited on the circulation part 42 to block discharge of the cooling water from the circulation part 42 to the center discharge pipe 43.

[33] In this case, the cooling water may be abnormally supplied and discharged to remarkably decrease cooling effect of the chamber 20.

[34] Therefore, after using for a certain time, the circulation part 42 should be cleaned to remove dust. At this time, since the waste gas treatment should be interrupted, its productivity may be decreased.

[35] In addition, the cooling water overflowed toward the center discharge port 43 from the circulation part 42 is splashed inside the chamber 20 to generate vapor, thereby contaminating the interior of the chamber 20. Disclosure of Invention Technical Problem

[36] In order to solve the problems, it is an object of the present invention to provide a plasma arc torch and a scrubber using the same capable of extending lifespan of an anode electrode, while generating arc discharge.

[37] It is another object of the present invention to provide a scrubber using a plasma arc torch capable of processing a large amount of gas, and increasing process efficiency.

[38] It is still another object of the present invention to provide a scrubber using a plasma arc torch capable of preventing deposition of dust onto a cooling part and introduction of overflowed cooling water into a chamber. Technical Solution

[39] The foregoing and/or other aspects of the present invention may be achieved by providing a plasma arc torch including: a cathode rod for discharging a thermal electron depending on an applied voltage, a first anode electrode spaced apart from the cathode rod by a predetermined distance and generating arc discharge when the voltage is applied, a second anode electrode disposed under the first anode electrode, maintaining transfer arc discharge generated from the cathode rod and the first anode electrode, and having better thermal resistance than the first anode electrode, and a plasma gas supply pipe for supplying a plasma generating gas between the cathode rod and the first anode electrode.

[40] In addition, another aspect of the present invention may be achieved by providing a plasma arc torch including: a cathode rod for discharging a thermal electron depending on an applied voltage, a first anode electrode spaced apart from the cathode rod by a predetermined distance and generating arc discharge when the voltage is applied, and a plasma generating gas supply pipe disposed under the first anode electrode, maintaining arc discharge generated from the cathode rod and the first anode electrode, and supplying a plasma generating gas, wherein the plasma arc torch further includes a second anode electrode having better thermal resistance than the first anode electrode.

[41] Still another aspect of the present invention may be achieved by providing a scrubber using a plasma arc torch including: a plasma arc torch including a cathode rod for discharging a thermal electron depending on an applied voltage, a first anode electrode spaced apart from the cathode rod by a predetermined distance and generating arc discharge when the voltage is applied, a second anode electrode disposed under the first anode electrode, maintaining transfer arc discharge generated from the cathode rod and the first anode electrode, and having better thermal resistance than the first anode electrode, and a waste gas supply pipe for supplying a plasma generating gas between the cathode rod and the first anode electrode; a chamber for providing a closed space under the plasma arc torch to purify the waste gas and having a discharge port for discharging the purified waste gas; and a cooling part coupled with a lower side of the chamber and cooling the chamber.

[42] In addition, yet another aspect of the present invention may be achieved by providing a scrubber using a plasma arc torch including: a plasma arc torch including a cathode rod for discharging a thermal electron depending on an applied voltage, a first anode electrode spaced apart from the cathode rod by a predetermined distance and generating arc discharge when the voltage is applied, and a plasma generating gas supply pipe disposed under the first anode electrode, maintaining arc discharge generated from the cathode rod and the first anode electrode, and supplying a plasma generating gas, and further including a second anode electrode having better thermal resistance than the first anode electrode; a chamber for providing a closed space under the plasma arc torch to purify the waste gas and having a discharge port for discharging the purified waste gas; and a cooling part coupled with a lower side of the chamber and cooling the chamber.

[43] Further, the scrubber using a plasma arc torch may further include a blocking plate disposed between the chamber and the cooling part to prevent deposition of dust in the chamber onto the cooling part.

Advantageous Effects

[44] In a plasma arc torch in accordance with the present invention, an anode electrode, in which a high temperature is generated, is divided into a first anode electrode having good conductivity and a second anode electrode having good thermal resistance, thereby making it possible to prevent reduction in lifespan of the anode electrode, due to the high temperature, and to lengthen the lifespan.

[45] In addition, in the plasma arc torch in accordance with the present invention, since a plasma generating gas is directly supplied to the second anode electrode, it is possible to increase plasma generating efficiency.

[46] Further, in a scrubber using a plasma arc torch in accordance with the present invention, since a purification process time of waste gas can be extended, it is possible to extend interruption interval of a manufacturing process, thereby increasing pro- ductivity and yield.

[47] Furthermore, in the scrubber using a plasma arc torch in accordance with the present invention, it is possible to prevent interference with flow of cooling water in a cooling part due to dust generated from the chamber and effects of overflowed cooling water to the chamber. In addition, it is possible to prevent interruption of a purification process in the cooling part by means of the scrubber using a plasma arc torch, thereby improving productivity.

[48] Further, in the scrubber using a plasma arc torch in accordance with the present invention, since dust generated in the chamber is forcedly discharged with the cooling water and a self-purification means is installed to purify the cooling part and the blocking plate during a purification process of waste gas, it is possible to prevent interruption of the waste gas purification process for performing a separate purification process. Brief Description of the Drawings

[49] The above and other aspects and advantages of the present invention will become apparent and more readily appreciated from the following description of exemplary embodiments, taken in conjunction with the accompanying drawings, in which:

[50] FIG. 1 is a schematic cross-sectional view of a conventional plasma arc torch;

[51] FIG. 2 is a schematic view showing movement of arc in a conventional transfer- type plasma arc torch, enlarging portion I of FIG. 1 ;

[52] FIG. 3 is a schematic cross-sectional view of another conventional plasma arc torch;

[53] FIG. 4 is a schematic cross-sectional view of a conventional scrubber using a plasma arc torch;

[54] FIG. 5 is a cross-sectional view of a plasma arc torch in accordance with a first exemplary embodiment of the present invention;

[55] FIG. 6 is a view showing movement of arc in the plasma arc torch, enlarging portion

I¹ of FIG. 5;

[56] FIG. 7 is a cross-sectional view of a scrubber in accordance with an exemplary embodiment of the present invention using the plasma arc torch shown in FIG. 5;

[57] FIG. 8 is a cross-sectional view of a plasma arc torch in accordance with a second exemplary embodiment of the present invention;

[58] FIG. 9 is a longitudinal cross-sectional view of a gas supply part of FIG. 8 in accordance with an exemplary embodiment of the present invention, and a side cross- sectional view of a waste gas supply pipe;

[59] FIG. 10 is a longitudinal cross-sectional view of a gas supply part in accordance with another exemplary embodiment of the present invention;

[60] FIG. 11 is a cross-sectional view of a scrubber in accordance with an exemplary embodiment of the present invention using the plasma arc torch shown in FIG. 8;

[61] FIG. 12 is a cross-sectional view of a scrubber using a plasma arc torch in accordance with another exemplary embodiment of the present invention; and

[62] FIG. 13 is a cross-sectional view of a scrubber using a plasma arc torch in accordance with still another exemplary embodiment of the present invention.

[63] * Description of Major Reference Numerals *

[64] 100: Plasma arc torch 110: Cathode rod

[65] 120: Body 130: First anode electrode

[66] 140: Second anode electrode 141: Gas supply part

[67] 142: Discharge holding part 150,160: Waste gas supply pipes

[68] 200: Chamber 300: Discharge port

[69] 400: Cooling part 410: Cooling water supply pipe

[70] 420: Circulation pipe 430: Center circulation pipe

[71] 500: Blocking plate 600: Injection nozzle

[72]

Best Mode for Carrying Out the Invention

[73] Reference will now be made in detail to exemplary embodiments of the present invention illustrated in the accompanying drawings.

[74] FIG. 5 is a cross-sectional view of a plasma arc torch in accordance with a first exemplary embodiment of the present invention.

[75] Referring to FIG. 5, the plasma arc torch in accordance with a first exemplary embodiment of the present invention includes a cathode rod 110 having a sharp tip formed at its one end to emit a thermal electron, a body 120 for supporting the cathode rod 110 and having a cooling water circulation pipe (not shown) and so on disposed therein, a first anode electrode 130 coupled with a portion of the body 120 adjacent to the sharp tip of the cathode rod 110 to perform initial arc discharge, a second anode electrode 140 coupled with the body 120 spaced apart from a lower surface of the first anode electrode 130 by a predetermined distance to continuously maintain arc discharge generated from the first anode electrode 130 and having good thermal resistance, and a plasma gas supply pipe 150 for supplying a plasma generating gas between the first anode electrode 130 and the cathode rod 110.

[76] Constitution and operation of the plasma arc torch in accordance with the present invention will be now described.

[77] First, the cathode rod 110 may be formed of tungsten, and the first anode electrode

130 may be formed of copper having resistivity of 1.724 x 10-2Ωmm2/m.

[78] This is because the thermal electron of the cathode rod 110 can be readily discharged to the first anode electrode 130 to flow strong current. [79] The first anode electrode 130 has a ring shape, and more preferably, a stepped shape having a small introduction area of a thermal electron. Especially, the ring-shaped first anode electrode 130 has a stepped part formed at its inner periphery such that a lower surface of the first anode electrode 130 adjacent to the second anode electrode 140 has a larger area than an upper surface of the first anode electrode 130 adjacent to the cathode rod 110.

[80] The reason for this is that the first arc discharge is performed at a lower side of the inner periphery of the first anode electrode 130 adjacent to the second anode electrode 140 such that the generated arc can readily move to the second anode electrode 140 to vertically and reciprocally move along the second anode electrode 140.

[81] In addition, the second anode electrode 140 may be formed of a material having strong thermal resistance, though its resistivity is higher than that of the first anode electrode 130.

[82] The second anode electrode 140 has a cylindrical shape with a flat inner periphery without any step.

[83] The second anode electrode 140 may be formed of graphite having good thermal resistance, or graphite coated with SiC.

[84] Using the second anode electrode 140 formed of graphite or graphite coated with

SiC, it is possible to reduce damage of the second anode electrode 140 in which current is substantially and continuously maintained.

[85] FIG. 6 is a view showing movement of arc in the plasma arc torch, enlarging portion

I¹ of FIG. 5.

[86] Referring to FIG. 6, in the plasma arc torch in accordance with the present invention, an electron of the cathode rod 110 is discharged to the first anode electrode 130 to generate arc, and the generated arc moves to the second anode electrode 140, thereby vertically reciprocating along the second anode electrode 140.

[87] That is, the first anode electrode 130 functions as a proximity point, and the second anode electrode 140 functions as an arc holding surface.

[88] As described above, while the second anode electrode 140 continuously maintains the arc discharge to increase a temperature therearound, since the second anode electrode 140 is formed of graphite or graphite coated with SiC, the second anode electrode 140 cannot be readily damaged due to its good thermal resistance.

[89] Therefore, the plasma arc torch in accordance with the present invention uses the first anode electrode 130 having good conductivity and the second anode electrode 140 having good thermal resistance to readily generate arc discharge and maintain the arc discharge and lengthen lifespan of the anode electrode in which the arc discharge is maintained.

[90] Generally, a melting point of copper is about 1083⁰C, and a melting point of graphite or SiC is 3000⁰C or more, however there can be a difference depending on its crystalline structure. Therefore, the second anode electrode cannot be readily damaged by the high temperature due to the arc discharge.

[91] As a result, even when the plasma arc torch in accordance with the present invention is continuously used, the second anode electrode can be used for several months to remarkably lengthen lifespan.

[92] FIG. 7 is a cross-sectional view of a scrubber in accordance with an exemplary embodiment of the present invention using the plasma arc torch shown in FIG. 5.

[93] Referring to FIG. 7, the scrubber using a plasma arc torch in accordance with the present invention includes a plasma arc torch 100 including a cathode rod 110 having a sharp tip formed at its one end to emit a thermal electron, a body 120 for supporting the cathode rod 110 and having a cooling water circulation pipe (not shown) and so on disposed therein, a first anode electrode 130 coupled with a portion of the body 120 adjacent to the sharp tip of the cathode rod 110 to perform initial arc discharge, a second anode electrode 140 coupled with the body 120 spaced apart from a lower surface of the first anode electrode 130 by a predetermined distance to continuously maintain arc discharge generated from the first anode electrode 130 and having good thermal resistance, and a waste gas supply pipe 150 for supplying a waste gas between the first anode electrode 130 and the cathode rod 110; a chamber for mounting the plasma arc torch 100 thereon and purifying the waste gas using flame generated from the plasma arc torch 100; a discharge port 300 for discharging the processed waste gas in the chamber 200; and a cooling part 400 coupled with a lower end of the chamber 100 to cooling the chamber 100.

[94] Hereinafter, structure and operation of the scrubber using a plasma arc torch in accordance with the present invention will be described in detail.

[95] First, as in the specifically described the structure of the plasma arc torch through the embodiment of FIG. 3, the anode electrode is divided into the first anode electrode 130 having good conductivity and the second anode electrode 140 having good thermal resistance.

[96] A waste gas is supplied through the waste gas supply pipe 150 disposed between the first anode electrode 130 and the cathode rod 110.

[97] The waste gas contains hazardous material and polluting induction material used to manufacture a semiconductor, a flat panel display, and so on. The waste gas is purified through the scrubber and exhausted therefrom before being discharged to the air.

[98] The waste gas supplied through the waste gas supply pipe 150 is phase converted into a plasma state by the arc discharge between the cathode rod 110 and the first anode electrode 130, or between the cathode rod 110 and the second anode electrode 140, and purified by flame caused by the arc discharge. [99] Substantially, the purification process is performed around the second anode electrode 140.

[100] In order to perform the purification process, a closed space under the second anode electrode 140 is provided in the chamber 200.

[101] The chamber 200 provides a space in which the waste gas is purified by the plasma arc torch 100, and has a discharge port formed at its one side to discharge the purified waste gas.

[102] Cooling water flows through the plasma arc torch 100 to cool the first and second anode electrodes 130 and 140 and the body 120, and the chamber 200 is cooled by the cooling part 400 formed at the lower part thereof.

[103] The scrubber using a plasma arc torch in accordance with the present invention should continuously perform the purification process during a process of generating waste gas, and should stop the waste gas generating process when the purification process needs to be interrupted.

[104] Such interruption of the process may cause decrease in productivity and yield. Using this constitution, it is possible to lengthen lifespan of the second anode electrode 140 of the plasma arc torch 100, thereby preventing frequent interruption of the process and improving productivity of a semiconductor or a flat panel display.

[105] FIG. 8 is a cross-sectional view of a plasma arc torch in accordance with a second exemplary embodiment of the present invention.

[106] Referring to FIG. 8, basic constitution of the plasma arc torch in accordance with a second exemplary embodiment of the present invention is similar to the plasma arc torch in accordance with a second exemplary embodiment of the present invention shown in FIG. 5.

[107] In contrast to the first embodiment, there is no separate waste gas supply pipe 150, and a waste gas supply pipe 160 is disposed in the second anode electrode 140 to supply waste gas. The second anode electrode 140 includes: a gas supply pipe 141 having the waste gas supply pipe 160 and a relatively small inner diameter, and disposed adjacent to the cathode rod 110; and a discharge holding part 142 for holding arc generated between the first anode electrode 130 and the cathode rod 110 and having a larger inner diameter than the gas supply part 141.

[108] The gas supply part 141 may be integrally formed with the discharge holding part 142.

[109] The first anode electrode 130 functions as a proximity point, and the discharge holding part 142 of the second anode electrode 140 functions as an arc holding surface.

[110] As described above, while the second anode electrode 140 continuously maintains the arc discharge to increase a temperature therearound, since the second anode electrode 140 is formed of graphite or graphite coated with SiC, the second anode electrode 140 cannot be readily damaged due to its good thermal resistance.

[I l l] Therefore, the plasma arc torch in accordance with the present invention uses the first anode electrode 130 having good conductivity and the second anode electrode 140 having good thermal resistance to readily generate arc discharge and maintain the arc discharge and lengthen lifespan of the anode electrode in which the arc discharge is maintained.

[112] FIG. 9 is a longitudinal cross-sectional view of the gas supply part 141 of FIG. 8 in accordance with an exemplary embodiment of the present invention, and a side cross- sectional view of the waste gas supply pipe 160.

[113] Referring to FIG. 9, the gas supply part 141 has the waste gas supply pipe 160 from an outer periphery to an inner periphery of the gas supply part 141. The waste gas supply pipe 160 may be sloped downward toward the inner periphery.

[114] This is because the gas is directed to the discharge holding part 142 to prevent flame being ejected upward.

[115] FIG. 10 is a longitudinal cross-sectional view of a gas supply part 141 in accordance with another exemplary embodiment of the present invention.

[116] Referring to FIG. 10, the gas supply partl41 has a waste gas supply pipe 160 passing through from an outer periphery to an inner periphery thereof. The gas supply pipe 160 is formed in a tangential direction of the inner periphery thereof such that a gas supplied through the waste gas supply pipe 160 is rotated along the inner periphery of the second anode electrode 140 to generate a vortex.

[117] As described above, the structure of the gas supply part 141 generates the vortex in the plasma generating gas supplied therefrom, thereby preventing back flow.

[118] FIG. 11 is a cross-sectional view of a scrubber in accordance with an exemplary embodiment of the present invention using the plasma arc torch shown in FIG. 8.

[119] Referring to FIG. 11, the scrubber using a plasma arc torch in accordance with the present invention includes: a plasma arc torch 100 including a cathode rod 110 having a sharp tip formed at its one end to emit a thermal electron, a body 120 for supporting the cathode rod 110 and having a cooling water circulation pipe (not shown) and so on disposed therein, a first anode electrode 130 coupled with a portion of the body 120 adjacent to the sharp tip of the cathode rod 110 to perform initial arc discharge and having good electrical conductivity, a second anode electrode 140 coupled with the body 120 spaced apart from a lower surface of the first anode electrode 130 by a predetermined distance to continuously maintain arc discharge generated from the first anode electrode 130, and having a larger inner diameter of an upper part than a lower part thereof and good thermal resistance, and a plurality of waste gas supply pipes 160 formed to pass through an upper part of the second anode electrode 140 and supplying a waste gas into an inner space of the second anode electrode 140; a chamber for mounting the plasma arc torch 100 thereon and purifying the waste gas using flame generated from the plasma arc torch 100; a discharge port 300 for discharging the processed waste gas in the chamber 200; and a cooling part 400 coupled with a lower end of the chamber 100 to cooling the chamber 100.

[120] Hereinafter, structure and operation of the scrubber using a plasma arc torch in accordance with the present invention will be described in detail.

[121] First, as in the specifically described structure of the plasma arc torch through the embodiment of FIG. 8, the anode electrode is divided into the first anode electrode 130 having good conductivity and the second anode electrode 140 having good thermal resistance.

[122] The second anode electrode 140 has a stepped shape in which an inner diameter of an upper part is larger than that of a lower part, and the plurality of waste gas supply pipes 160 disposed over the second anode electrode 140 to supply waste gas inside the second anode electrode 140.

[123] The waste gas contains hazardous material and polluting induction material used to manufacture a semiconductor, a flat panel display, and so on. The waste gas is purified through the scrubber and exhausted therefrom before discharged to the air.

[124] The waste gas supplied through the waste gas supply pipes 160 is phase converted into a plasma state at a lower part inside the second anode electrode 140 in which the arc discharge generated between the cathode rod 110 and the first anode electrode 130 is maintained, and purified by flame caused by the arc discharge.

[125] In order to perform the purification process, a closed space under the second anode electrode 140 is provided in the chamber 200.

[126] The chamber 200 provides a space in which the waste gas is purified by the plasma arc torch 100, and has a discharge port formed at its one side to discharge the purified waste gas.

[127] Cooling water flows through the plasma arc torch 100 to cool the first and second anode electrodes 130 and 140 and the body 120, and the chamber 200 is cooled by the cooling part 400 formed at the lower part thereof.

[128] The scrubber using a plasma arc torch in accordance with the present invention should continuously perform the purification process during a process of generating waste gas, and should stop the waste gas generating process when the purification process needs to be interrupted.

[129] Such interruption of the process may cause decrease in productivity and yield. Using this constitution, it is possible to lengthen lifespan of the second anode electrode 140 of the plasma arc torch 100, thereby preventing frequent interruption of the process and improving productivity of a semiconductor or a flat panel display.

[130] In addition, since the waste gas is directly supplied through the second anode electrode 140, it is possible to increase gas process efficiency and enable manufacturing of a large capacity scrubber.

[131] FIG. 12 is a cross-sectional view of a scrubber using a plasma arc torch in accordance with another exemplary embodiment of the present invention.

[132] Referring to FIG. 12, the scrubber using a plasma arc torch in accordance with another exemplary embodiment of the present invention includes a plasma arc torch 100 for heating waste gas to a high temperature to purify the waste gas, a chamber 200 for fixing the plasma arc torch 100 and providing a waste gas purification space, and having a discharge port 130 for exhausting the purified waste gas, a cooling part 400 disposed at a lower part of the chamber 200 to cool the chamber 200 using cooling water, and an annular blocking plate 500 disposed between the cooling part 400 and the chamber 200 to prevent deposition of dust generated in the chamber 200 onto the cooling part 400.

[133] Hereinafter, constitution and operation of the scrubber using a plasma arc torch in accordance with another exemplary embodiment of the present invention will be described in detail.

[134] First, any constitution of the plasma arc torch 100 capable of generating a high temperature heat to purify waste gas can be used in the present invention, and preferably, the plasma arc torch in accordance with a first or second embodiment of the present invention shown in FIG. 5 or 8 is used.

[135] The plasma arc torch 100 is fixed to an upper part of the chamber 200 to enable purification by flame injected inside the chamber 200.

[136] The waste gas purified in the plasma arc torch 100 and the chamber 200 is discharged to the exterior through the discharge port 300. At this time, a temperature in the chamber 200 is increased by the plasma and the flame.

[137] In order to cool the chamber 200, the cooling part 400 using cooling water is disposed at a lower end of the chamber 200.

[138] The cooling part 400 includes a cooling water supply pipe 410 through which cooling water is supplied, a circulation part 420 for circulating the cooling water supplied through the cooling water supply pipe 410 along the lower end of the chamber 200, and a center discharge pipe 430 for discharging the cooling water overflowed from the circulation part 420 to the exterior.

[139] While foreign substances contained in the waste gas during a process of treating waste gas by the plasma arc torch may be combusted and then dropped toward the circulation part 420, the blocking plate 500 may be disposed over the circulation part 420 to prevent deposition of dust onto the circulation part 420 and interference with flow of the cooling water.

[140] In addition, the blocking plate 500 can prevent the overflowed cooling water from being splashed toward inside the chamber 200. [141] The blocking plate 500 has an annular shape, which is sloped downward toward a center of the chamber 200. [142] Installation of the blocking plate 500 enables smooth supply of the cooling water into the scrubber using a plasma arc torch in accordance with the present invention, and prevents interruption of operation of the scrubber using a plasma arc torch due to abnormal supply of the cooling water. [143] FIG. 13 is a cross-sectional view of a scrubber using a plasma arc torch in accordance with still another exemplary embodiment of the present invention. [144] Referring to FIG. 13, the scrubber using a plasma arc torch in accordance with still another exemplary embodiment of the present invention further includes an injection nozzle 600 for forcedly discharging dust in the chamber 200 to the center discharge pipe 430 and purging the cooling part 400, in addition to the structure of FIG. 12. [145] Hereinafter, constitution and operation of the scrubber using a plasma arc torch in accordance with still another exemplary embodiment of the present invention will be described in detail. [146] First, the injection nozzle 600 is disposed over the blocking plate 500 to inject an inert gas. [147] The inert gas may be nitrogen gas, or any gas showing inert properties under a high temperature atmosphere. [148] The blocking plate 500 may be an annular plate downwardly sloped toward its center or having a downwardly bent center part. [149] As a result, the dust generated in the chamber 200 is not deposited on the cooling part 400 by the injection nozzle 600 for injecting the inert gas, and therefore, is discharged with the overflowed cooling water to the exterior through the center discharge pipe 430 of the cooling part 400. [150] As described above, interference with flow of the cooling water is prevented and the inside of the cooling part 400 is continuously and periodically purged, thereby making it possible to prevent interruption of the waste gas purification process due to purge of the cooling part 400. [151] While this invention has been described with reference to exemplary embodiments thereof, it will be clear to those of ordinary skill in the art to which the invention pertains that various modifications may be made to the described embodiments without departing from the spirit and scope of the invention as defined in the appended claims and their equivalents.

Industrial Applicability [152] As can be seen from the foregoing, a plasma arc torch in accordance with the present invention includes an anode electrode constituted of a first anode electrode having good conductivity and a second anode electrode having good thermal resistance, thereby enabling an increase in lifespan and a reduction in maintenance cost. [153] In addition, the plasma arc torch in accordance with the present invention is configured to directly supply waste gas through the second anode electrode to enable an increase in process efficiency of the waste gas. [154] Further, a scrubber using a plasma arc torch in accordance with the present invention can lengthen an exchange period of the plasma arc torch to extend interruption interval of the purification process. [155] Furthermore, a blocking plate is installed between a chamber and a cooling part of t he scrubber to block dust to enable lengthening of a purification period of the scrubber.

Claims

[1] A plasma arc torch comprising: a cathode rod for discharging a thermal electron depending on an applied voltage; a first anode electrode spaced apart from the cathode rod by a predetermined distance and generating arc discharge when the voltage is applied; and a second anode electrode disposed under the first anode electrode, maintaining transfer arc discharge generated from the cathode rod and the first anode electrode to process waste gas, and having better thermal resistance than the first anode electrode.

[2] The plasma arc torch according to Claim 1, wherein the first anode electrode is a ring-shaped electrode having a lower inner diameter smaller than an upper inner diameter in an installation state.

[3] The plasma arc torch according to Claim 1 or 2, wherein the first anode electrode is formed of copper, and the second anode electrode is formed of graphite or graphite coated with SiC.

[4] The plasma arc torch according to Claim 3, wherein the waste gas is supplied between the cathode rod and the first anode electrode.

[5] The plasma arc torch according to Claim 3, wherein the second anode electrode has a stepped cylindrical shape having an upper inner end smaller than a lower inner diameter, and a plurality of waste gas supply pipes are disposed at the upper part having the small inner diameter to directly supply the waste gas through the second anode electrode.

[6] The plasma arc torch according to Claim 5, wherein the waste gas supply pipe is configured to pass through from an upper outer periphery to an inner periphery of the second anode electrode.

[7] The plasma arc torch according to Claim 5, wherein the waste gas supply pipe is configured to pass through from an upper outer periphery to an inner periphery of the second anode electrode, and disposed in a tangential direction of the inner periphery of the second anode electrode to rotate the supplied plasma generating gas along the inner periphery.

[8] A scrubber using a plasma arc torch comprising: a plasma arc torch comprising a cathode rod for discharging a thermal electron depending on an applied voltage, a first anode electrode spaced apart from the cathode rod by a predetermined distance and generating arc discharge when the voltage is applied, and a second anode electrode disposed under the first anode electrode, maintaining transfer arc discharge generated from the cathode rod and the first anode electrode to process waste gas, and having better thermal resistance than the first anode electrode; a chamber for providing a closed space under the plasma arc torch to purify the waste gas and having a discharge port for discharging the purified waste gas; and a cooling part coupled with a lower side of the chamber and cooling the chamber. [9] The scrubber according to Claim 8, further comprising a blocking plate disposed between the chamber and the cooling part to prevent deposition of dust in the chamber onto the cooling part. [10] The scrubber according to Claim 8 or 9, wherein the blocking plate is an annular plate downwardly sloped toward its center or having a downwardly bent center part. [11] The scrubber according to Claim 8 or 9, further comprising an injection nozzle disposed between the chamber and the cooling part and injecting an inert gas toward the cooling part. [12] The scrubber according to Claim 8 or 9, wherein the first anode electrode is formed of copper, and the second anode electrode is formed of graphite or graphite coated with SiC. [13] The scrubber according to Claim 12, wherein the second anode electrode has a waste gas supply pipe for supplying waste gas.