TWI638128B - Method of highly efficient heat dissipation for plasma torch electrode by using integrated heat pipes - Google Patents

Abstract

An efficient integrated heat pipe heat dissipation method for a plasma torch electrode, wherein an inner portion of the torch electrode is arranged with an evaporation section of the heat pipe, and a rear end is connected in series with a condensation section of the heat pipe; and the high heat conductivity of the heat pipe is used to replace the low efficiency The traditional water-cooling electrode method, in particular, reduces the local high temperature of the arc root point of the torch electrode, improves the heat dissipation efficiency, and slows the electrode erosion to prolong the service life of the plasma torch. Moreover, the working fluid filled in the heat pipes is small and limited, and even if the pipe is broken, the torch electrode can be invaded by a large amount of cooling liquid, causing gas explosion or lithification solidification; and the other heat pipes are arranged by a plurality of arrays. Even if one of the heat pipes is eroded, the remaining heat pipes can still operate normally, although the overall heat dissipation performance will be slightly reduced, but the plasma torch can continue to operate, improve the overall operational flexibility, and give the operator appropriate strain time to make subsequent strains. Handling measures to prevent danger and work safety.

Description

Efficient integrated heat pipe heat dissipation method for plasma torch electrode

The invention relates to a high-efficiency integrated heat pipe heat dissipation method for a plasma torch electrode, wherein an inner portion of the torch electrode is arranged with an evaporation section of the heat pipe, and a rear end is connected with a condensation section of the heat pipe; the crucible is used to utilize the high heat conduction of the heat pipes. The coefficient replaces the low-efficiency traditional water-cooled electrode method, especially reducing the local high temperature of the arc root point of the torch electrode, improving the heat dissipation effect, slowing the electrode erosion, prolonging the service life of the plasma torch, extending the maintenance period and reducing the use cost.

The Plasma Torch is the local core technology independently developed by the Nuclear Energy Research Institute (hereinafter referred to as the Institute). Based on the power equipment and the thermal efficiency of the torch, the main development of the company is the economical DC plasma torch, which is currently the vast majority of the world's plasma. The melt processing system also uses a DC plasma torch. A direct current plasma torch is a form of gas discharge, that is, a self-sustaining arc discharge with a working pressure greater than atmospheric pressure. A DC plasma torch with an operating power of 10 to 8,000 kW can produce a flame with a temperature of approximately 5,000 to 20,000 ° C and an energy density of approximately 10 to 100 MJ/kg. Since the diameter of the arc root of the arcing point of the torch electrode increases with the operating power of the plasma torch, the size mainly falls between 1 and 6 mm. However, since the main power of the torch falls on the small circle, once the temperature of the torch is higher than the melting point of the electrode material, some of the electrode material will melt at a high temperature and be lost as the airflow is taken away, shortening the service life of the plasma torch. Is the limitation of the application of this technology. Many improvement techniques, such as the use of magnetic fields or varying working airflows, direct the movement of the arc roots to prevent the arc roots from being fixed at the same point of the electrode and severely eroding the electrodes. In addition, it is trying to enhance the heat transfer effect of the electrodes, such as pressurized water cooling and heat dissipation channels and heat sink fin design. In particular, the well-type plasma torch electrode developed by the Institute often uses metal copper with low conductivity and good thermal conductivity as the electrode material. The melting point of copper is 1083 ° C, and its boiling point is 2567 ° C. The minimum loss of copper electrodes in the literature is about 10 ^-7 g/Coulomb. In addition, the traditional cooling method is used to cool the copper electrode of the torch with high-pressure water. The traditional high-pressure water cooling channel is designed outside the copper electrode of the torch. However, in practical applications, such as plasma melting furnace, once the torch electrode is etched through, the cooling water of the traditional high-pressure cooling water channel will be sprayed into the plasma melting furnace in large quantities, because the plasma melting furnace is often maintained at a temperature above 1200 °C. The injected cooling water will instantly vaporize and suddenly increase in volume. At this time, there is a great chance of gas explosion. At the same time, the outflow of the cooling water also causes the existing molten soup in the electric furnace to be cooled and solidified in an instant, forming a major trouble in the subsequent operation and maintenance of the plasma furnace. Therefore, the general practitioners cannot meet the needs of the user in actual use.

The main object of the present invention is to overcome the above problems encountered in the prior art and to provide an advantage of utilizing the ultra-high thermal conductivity of the heat pipe, instead of improving the heat dissipation efficiency of the existing water-cooled electrode method and reducing the temperature at the arc root point of the torch electrode. An efficient integrated heat pipe cooling method for the electrode of a plasma torch that slows electrode erosion, increases the service life of the torch electrode, and extends maintenance cycles and costs.

The secondary object of the present invention is to provide a plasma torch copper integrated structure with a heat pipe, which has better heat dissipation effect, can be directly fabricated by using 3D metal printing, and can also be used for direct deep drilling of electrodes or electrode drilling. The method of embedding the heat pipe after the hole is made into a highly efficient integrated heat pipe heat dissipation method for the plasma torch electrode.

Another object of the present invention is to provide an efficient integrated heat pipe heat dissipation method for a plasma torch electrode which can avoid and solve the gas storm and lithification solidification phenomenon caused by the torch electrode being etched and the cooling liquid is ejected.

A further object of the present invention is to provide a method for dissipating a high-efficiency heat pipe of a torch electrode arranged in a plurality of arrays. When one of the heat pipes is etched through, the heat dissipation function of the entire heat pipe is deteriorated, but the operation can still be continued. Appropriate strain time to do the subsequent strain treatment measures to prevent the dangerous and beneficial work of the high-efficiency integrated heat pipe cooling method for the plasma torch electrode.

For the purpose of the above, the present invention is a highly efficient integrated heat pipe heat dissipation method for a plasma torch electrode, which is fabricated by a metal working method or a 3D metal printing method, and is directly printed for a plasma torch electrode. The root heat pipe is arranged in a circular shape and has no integrated interface structure. The inner end of the torch electrode is an evaporation section of the heat pipe, and the rear end is a condensation section of the heat pipe, and the length of the condensation section is smaller than the length of the evaporation section; The thermal conductivity of some heat pipes is 5,000~50,000W/(mK) instead of water-cooled electrodes to reduce the temperature at the arc root point of the torch electrode, slow down the electrode erosion, and thus improve the heat dissipation efficiency, and the amount of working fluid filled in the heat pipes Less and limited, it can avoid and solve the gas explosion and lithification solidification caused by the blasting of the torch electrode and the cooling liquid. Even if one of the heat pipes is eroded, the heat dissipation function of the whole heat pipe can continue to operate and operate. There is sufficient strain time for subsequent processing.

In the above embodiment of the present invention, the torch electrode with a plurality of heat pipes arranged in a circular pattern is directly printed and produced by a 3D metal printing method, and a working fluid is added to the tail end to be vacuum-sealed, or a deep deep hole can be taken. The road is further filled with a working fluid at the end end, and then vacuum-sealed, or a method in which the electrode is dug and the long hole is buried in the heat pipe.

In the above embodiment of the invention, the plasma torch electrode is a post-horse DC plasma hollow torch rear electrode.

In the above embodiment of the invention, the center position of the evaporation section is located at the center of the plasma arc root, and the length of the condensation section is less than the length of the evaporation section.

In the above embodiment of the present invention, the working system filled in the heat pipes accounts for 10 to 50% of the volume in the tube.

In the above embodiments of the present invention, a wick structure may be added to the heat pipes, and the work of the torch includes, but is not limited to, vertical and horizontal directions.

10‧‧‧ torch electrode

11‧‧‧ Heat pipe

111‧‧‧Evaporation section

112‧‧‧Condensation section

Figure 1 is a diagram showing the thermal conductivity ratio of a general substance.

Fig. 2 is a schematic view showing a well type torch electrode in which a plurality of heat pipes are arranged in a circular shape.

Figure 3 is a graph showing the temperature distribution of the evaporation section of the axial torch electrode surface of the present invention.

Figure 4 is a schematic diagram showing the 3D temperature distribution of the flare electrode simulated without a heat pipe.

Fig. 5 is a schematic view showing the 3D temperature distribution of the flare electrode simulated by the heat pipe of the present invention at a heat conductivity of 5,000 W/(m.K).

Figure 6 is a schematic diagram showing the simulated 3D temperature distribution of the torch electrode under the thermal conductivity of the heat pipe of the present invention of 50,000 W/(m.K).

Please refer to the "1st to 6th" diagrams, which are respectively the thermal conductivity ratio diagram of general materials, the schematic diagram of the well type torch electrode in which the plurality of heat pipes are arranged in a circular shape, and the present invention simulates an axial torch electrode. The temperature distribution curve of the surface evaporation section, the 3D temperature distribution diagram of the torch electrode simulation without the heat pipe, the thermal conductivity of the heat pipe of the invention is 5,000 W/(mK) The schematic diagram of the 3D temperature distribution of the lower torch electrode and the 3D temperature distribution of the flare electrode simulated by the thermal conductivity coefficient of the heat pipe of the present invention is 50,000 W/(m.K). As shown in the figure: a highly efficient integrated heat pipe heat dissipation method suitable for a plasma torch electrode disclosed in the present invention, the main purpose of which is to replace and upgrade the existing water cooling by utilizing the advantages of the ultra-high thermal conductivity of the heat pipe of 5,000-50,000 W/(mK). The heat dissipation efficiency of the electrode method reduces the temperature of the arc root point of the torch electrode, slows down the electrode erosion, and increases the service life of the torch electrode, thereby prolonging the maintenance cycle and reducing the cost, and facilitating the promotion of technology. The heat dissipation of a hot object is good or bad, or it is difficult to conduct heat. It is related to the thermal conductivity of the material. Figure 1 shows the thermal conductivity of common materials. In principle, the solid state, liquid state, gas state and vacuum, the thermal conductivity value Reduced. As shown in Figure 1, the thermal conductivity of air is 0.024W/(mK), the thermal conductivity of water at 4°C is 0.58W/(mK), and the thermal conductivity of carbon steel is 43.2W/(mK). The coefficient is 400W/(mK), and the thermal conductivity of the heat pipe is between 5,000 and 100,000 W/(mK), depending on other factors such as the heat pipe material, working fluid and use environment.

In a specific embodiment, a Well-type DC plasma hollow torch electrode structure developed by the present invention is taken as an example, and FIG. 2 is a 3D back electrode suitable for an integrated type heat pipe of a well type DC plasma hollow torch. The embodiment refers to a copper cathode of a negative polarity electrical connection), using a 3D metal printing method, and directly printing a well-type DC plasma hollow torch electrode 10 to produce a circular arrangement with multiple heat pipes 11 and no interface integration. The inner structure of the torch electrode 10 has a long section of 30 cm long and is an evaporation section 111 of the heat pipe 11. The center of the evaporation section 111 is located at the center of the plasma arc root, and the inner end of the torch electrode 10 is the condensation section 112 of the heat pipe 11 and The evaporation section 111 is short and about 10 cm long. Computational Fluid Dynamics (CFD) simulation was performed using this 3D electrode geometry model, in which the thermal conductivity of the heat pipe was changed to 400 W/(mK), 5,000 W/(mK), and 50,000 W/(mK). ) and other three values, of which 400W / (mK) thermal conductivity is The thermal conductivity of copper, 5,000 W / (m. K) and 50,000 W / (m. K) is the upper and lower limits of the thermal conductivity of the heat pipe, as a comparison reference. Here, the plasma operating power was 500 kW, and the arc root was simulated in the middle around the inner diameter of the hollow tube and the length was 1.5 cm. Figure 3 is a graph showing the temperature distribution of the evaporation section of the surface of the axial torch (copper) electrode. For the central arc root high temperature zone, the highest temperature is 2500 °C when there is no heat pipe (ie, the thermal conductivity is 400 W/(mK)). The highest temperature is nearly 1500 ° C when the thermal conductivity is 5,000 W / (mK), and the highest temperature is nearly 700 ° C when the thermal conductivity is 50,000 W / (mK).

Since copper has a melting point of 1083 ° C and a boiling point of 2567 ° C, in the absence of a heat pipe and a thermal conductivity of 400 W / (mK), that is, copper, although lower than the boiling point, the corrosion of the (copper) electrode is still difficult to avoid. It is also actually observed. When comparing a heat pipe with a thermal conductivity of 50,000 W/(m.K), the highest temperature of the electrode surface is lower than 700 ° C, lower than the melting point, and there is no problem of electrode erosion. If the thermal conductivity is 5,000 W/(mK), this is more in line with the thermal conductivity value of the actual heat pipe. The highest temperature is near 1500 ° C. The arc root high temperature zone is lower than the boiling point but higher than the melting point, compared with the thermal conductivity. 400W / (mK), can greatly reduce the temperature to slow down the melting phenomenon, slow down the electrode erosion, and increase the service life of the torch electrode. Figures 4, 5 and 6 represent the CFD heat transfer simulations obtained by three heat transfer coefficients (TCHP) of 400 W/(mK), 5,000 W/(mK), and 50,000 W/(mK), respectively. The 3D temperature profile of the torch electrode, which contains the evaporation section and the condensation section.

The invention can utilize the existing 3D metal printing method to directly print the heat pipe for the well type DC plasma hollow torch electrode and vacuum-seal after adding the working fluid to the tail end, and the integrated structure containing the heat pipe has no interface. Better heat dissipation. It can also be made by directly drilling the deep drilling channel and then adding the working fluid to the tail end, vacuum sealing, or by the method of embedding the long hole in the cathode to fill the heat pipe, but the thermal conductivity will decrease slightly due to the difficulty of tight joint. In addition, a wick structure may be added to the heat pipes of the present invention, and the work of the torch includes, but is not limited to, vertical and horizontal directions.

Another advantage of the present invention is that the working fluid filled in the heat pipe generally accounts for about 10 to 50% of the volume inside the pipe, and the amount thereof is small and limited, and the torch electrode is not eroded and the cooling liquid of the conventional high-pressure water cooling pipe is large. The molten smelting and solidification in the furnace of the plasma furnace caused by the blasting and the gas explosion in the furnace. In addition, the high-efficiency heat pipe heat dissipation method applied to the torch electrode adopts multiple arrays, which are usually etched through the so-called torch electrode, and also refers to one of the heat pipes being eroded, and the working fluid filled in the heat pipe is discharged, but the rest The heat pipe is still built, although the heat dissipation function of the overall heat pipe is deteriorated, but it can maintain its function to continue to operate, giving the operator appropriate time to do the subsequent strain treatment measures to prevent danger and safety.

In summary, the present invention is an efficient integrated heat pipe heat dissipation method for a plasma torch electrode, which can effectively improve various disadvantages of the conventional use. The plasma torch technology is the core technology of the high temperature plasma furnace, and the electrode heat dissipation design is improved by Extending the life of the torch can help improve the utilization rate and life cycle of the plasma furnace, effectively extend the maintenance cycle and reduce the use cost, and improve the return on investment of the manufacturer, thereby making the invention more progressive, practical and more suitable. The person must have met the requirements of the invention patent application and filed a patent application according to law.

However, the above is only the preferred embodiment of the present invention, and the scope of the present invention is not limited thereto; therefore, the simple equivalent changes and modifications made in accordance with the scope of the present invention and the contents of the invention are modified. All should remain within the scope of the invention patent.

Claims (6)

The invention relates to a high-efficiency integrated heat pipe heat dissipation method for a plasma torch electrode, which comprises a plurality of heat pipe circular arrangement and an interfaceless integrated structure, wherein an inner front end of the torch electrode is an evaporation section of the heat pipe, and a rear end is a condensation section of the heat pipe, and The length of the condensation section is less than the length of the evaporation section; 俾using the heat conductivity of the heat pipes of 5,000~50,000 W/(mK) instead of water to cool the electrode, the temperature of the arc root of the torch electrode can be lowered, and the electrode erosion is slowed down. In addition, the heat dissipation efficiency is improved, and the amount of the working fluid filled in the heat pipes is limited and limited, and the gas explosion and lithification solidification caused by the blasting of the torch electrode and the cooling liquid ejection can be avoided and solved, even if one of the heat pipes After being etched through, the overall heat pipe cooling function can continue to operate, so that it has sufficient strain time for subsequent treatment. The high-efficiency integrated heat pipe heat dissipation method for a plasma torch electrode according to the first aspect of the patent application, wherein the plurality of heat pipe round-arranged torch electrodes directly print the heat pipe by a 3D metal printing method. After the working fluid is added to the tail end, the vacuum sealing is performed, and the direct deep drilling channel can be adopted, and then the working fluid is added to the tail end to be vacuum-sealed, or the electrode is dug and the long hole is buried in the heat pipe. The high-efficiency integrated heat pipe heat dissipation method for a plasma torch electrode according to the first aspect of the patent application, wherein the plasma torch electrode is a well-type DC plasma hollow torch rear electrode. An efficient integrated heat pipe heat dissipation method for a plasma torch electrode according to claim 1, wherein a center position of the evaporation section is at a center of the plasma arc root. The high-efficiency integrated heat pipe heat dissipation method for the plasma torch electrode according to the first aspect of the patent application, wherein the heat pipe filled with the working flow system accounts for 10 to 50% of the volume inside the pipe. Efficient integrated heat for plasma torch electrodes as described in item 1 of the patent application The heat dissipation method of the tube, wherein a wick structure may be added to the heat pipe, and the work of the torch includes, but is not limited to, vertical and horizontal directions.