JPH01500152A - induction plasma furnace - Google Patents

Abstract

An induction plasma furnace comprises an inductor (1) housing a melting pot (2) the side wall of which consists of two vertically oriented sections (3) made of an electrically conductive material and electrically insulated from each other. At least one of the sections (3) of the pot (2) is connected in series with the electrical circuit of an electric arc plasmatron (7), said circuit being closed through the melt (4), so that the current direction of the arc (10) of the plasmatron (7) is the same or opposite to the current direction in the section (3) of the pot (2).

Description

[Detailed description of the invention] induction plasma furnace Technical field FIELD OF THE INVENTION The present invention relates to electrical engineering, and in particular to induction plasma furnaces.

Background technology The production output of various melting furnaces and the quality of the metal or alloy produced depend on the melting crucible. depends on the nature and intensity of the movement of the molten metal within the molten metal.

The melt of the entertainer's material falls off, reheating the entire molten metal, equalizing the temperature of the entire molten metal, and changing the molten metal composition. Each stage of the metal or alloy melting process, such as homogenization, and the melt itself, the melt/metal Diffusion processes at the slag interface and the atmosphere/molten metal interface are facilitated by active stirring. This results in a substantial increase in production through the entire process.

In the induction melting furnace widely known in the prior art, an internal It houses a melting crucible with a refractory lining on the side. In this furnace, Batch in the pot, ie non-contact to the entertainer material, molten metal, or charging material-molten metal mixture Energy is transferred. The entertainer material is stirred by the electromagnetic field of the induction heater. It will be done.

In an induction melting furnace that uses a commercial frequency (50-60Hz), the molten metal moves at high speed. , the melting of the solid entertainer material and the homogenization of the molten metal are effectively carried out. but This causes abnormal wear on the crucible lining and significant oxidation of the molten metal. As a result, metals become contaminated with various impurities. Furthermore, the eruption of metal from the crucible can occur. Therefore, the input power of such a furnace is 300 to 400 kw/ limited to the range of t.

For furnaces that use high frequencies (150 to 10.000Hz), it is not possible to increase the input power. It is possible, but the moving speed of the molten metal is quite slow.

As is known, natural circulation in induction melting furnaces induction heaters along two paths in the vertical plane at the top and bottom of the crucible. The molten metal circulates separately in these two paths and mixes slightly.

Because such circulation occurs in the induction furnace, the meniscus surface of the molten metal becomes convex, and its Therefore, a large amount of slag is required and the slag is descending towards the crucible wall. Destroys the vase lining and increases metal contamination.

Furthermore, since the slag is heated by heat transfer from the molten metal, the amount of slag increases. If added, the refining ability of the slag will decrease.

To improve the electrodynamic stirring of the molten metal, the entertainer material is simply moved by a moving electromagnetic field. The material is circulated through one path over the entire height of the pot, and the material is stirred and the meniscus is lowered. The induction melting furnace is equipped with a device for performing ky, V, S.

Nen+kov, N, 8, Pavlov, A, V, Bamune, Ustano vka induktisonnog.

nagreva, Energoisdat, Leningradskoe otdelenie+1981+246-247).

Heating and stirring of the entertainer's ingredients can be done simultaneously or alternately. heating and stirring If running at the same time, use separate induction heaters and While heating in a single phase, the other heater stirs in three phases. These heat The controller is equipped with an electrical filter that protects one high-frequency power source from high-frequency interference from the other. A tar is provided. When heating and stirring are performed alternately, separate power supplies are used alternately. The furnace is equipped with a split induction heater connected to the furnace. However, the induction melting furnace Even if the power supply circuit is made quite complex, there are only two modes of circulation. That is, induction When the heater is connected to a single-phase power supply, it becomes a two-path circulation, and the induction heater is connected to a three-phase power supply. When connected to a power source, there is a single path circulation.

Inside the induction heater is a melting crucible and an electric arc where the electrical circuit is completed through the molten metal. Induction plasma furnaces containing plasma generators are known. This furnace is induction melting Compared to furnaces, the production volume of metal or alloy melting processes is increased by two times, for example. For this purpose, the material is heated both locally and as a whole.

Since the slag is heated by the plasma arc of the electric arc plasma generator, The molten metal is intensively refined to eliminate non-metallic inclusions and harmful contaminants, resulting in high high quality metals or alloys are produced.

Through the use of plasma generators, both inert and active plasma-forming gases can process molten metal. Therefore, the charge in an induced plasma furnace The composition of the stirring method increases the production volume of the furnace and improves the quality of the metal or alloy produced. is especially important for

Another known induction plasma furnace houses a melting crucible with cylindrical side walls. An electric arc is used to complete the electric circuit through the molten metal in the crucible. Equipped with a plasma generator (S, Asada, Dvukhtonnaya plazmennoinduksion-naya pech nazav ode g, 5hibukava, “Denki 5eiko”t, 47 ゜NT, 1976, p, p, 60-63). The inner surface of the crucible is made of electrically insulating material It is made of synthetic material and is lined with magnesite. This electrically isolates the plasma generator circuit from the induction heater circuit. There is.

A bottom electrode is provided at the bottom of the crucible to complete the circuit of the plasma generator. It is being The induction heater is connected to a single phase power supply with an output frequency of 150.

A three-phase electrical system with three induction heaters is used to stir the molten metal throughout the crucible. A magnetic device is installed, and each induction heater is connected to each phase of a three-phase power supply with a frequency of 60Hz. It is connected. A three-phase electromagnetic system redirects the molten metal circulation from two paths to a single path. and vice versa. The direction of circulation in a single path is determined within the power circuit. It can be changed immediately by making the appropriate switch.

This kind of induction plasma furnace has a complicated furnace structure, and the overall size is large and the cost is low. It is also high in terms of power consumption, and the maximum power consumed during the melting period of entertainer materials is small.

This type of molten metal stirring method is similar to the circulation of molten metal in the melting of metals or alloys. Unable to adapt to process steps.

For example, for slag removal and formation, especially if the slag is formed multiple times. In this case, it is necessary to direct the movement of the molten metal on top of the metal toward the spout. Moreover, this In the eel furnace, the characteristics and intensity of the circulation can be changed, for example from a horizontal plane to a vertical plane. do not have.

Disclosure of invention The basic problem of the present invention is that the characteristics of the molten metal circulation are preset according to the stages of the melting process. A crucible structure that increases production in induced plasma reactors by providing Provided is an induction plasma furnace having a structure and a connection between a crucible and a plasma generator. That's true.

This task was solved according to the invention by housing a melting crucible with cylindrical side walls. An electric appliance in which an electric circuit is completed through an induction heater and the molten metal contained in the crucible. In an induction plasma furnace comprising a crucible plasma generator, the side wall of the crucible is formed by vertically arranged partial elements of conductive material, the partial elements being are electrically insulated from each other, and at least one of the subelements is electrically insulated from the plasma generator. The direction of the current of the arc of the raw equipment is the same as the direction of the current of the partial element of the crucible or is connected in series with the electric circuit of the plasma generator so that the direction is opposite to that of the plasma generator. This is achieved by an induction plasma furnace characterized by:

According to the crucible structure of such an induction plasma furnace, the current of the induction heater and the melting The electromagnetic phase between the magnetic field formed by the current in the vase element and the various currents in the molten metal. Preset according to the required stage of the melting process of metals or alloys by interaction molten metal circulation can be carried out. Therefore, the disclosed crucible structure This allows you to adapt to the stages of the metal or alloy melting process without complicating the furnace structure. Therefore, the molten metal can be circulated with the necessary characteristics in the induction plasma furnace.

Brief description of the drawing The invention will now be described with reference to specific embodiments in conjunction with the accompanying drawings.

Figure 1 shows the direction of the arc current in the plasma generator and the direction of the current in the crucible element. One of the crucible partial elements is connected to the electrical circuit of the plasma generator so that the FIG. 2 is a cross-sectional view along the line nn of FIG. 1 according to the invention; Figure 3 shows the direction of the arc current in the plasma generator and the direction of the current in the crucible element. One of the crucible partial elements is connected to the electrical circuit of the plasma generator so that the FIG. Figure 4 shows the direction of the arc current in the plasma generator and the direction of the current in the crucible element. Six of the crucible partial elements are placed in the electric circuit of the plasma generator so that the FIG. 5 is a longitudinal sectional view schematically showing an induction plasma furnace according to the invention connected to 4 is a cross-sectional view along line V-V of FIG. 4 according to the invention; Figure 6 shows the direction of the arc current in the plasma generator and the direction of the current in the crucible element. All of the crucible partial elements are aligned in the same direction as the electric circuit of the plasma generator. FIG. FIG. 7 shows the electric current generated in the cross section of the induction plasma furnace of FIG. 1 according to the present invention. Acting on the molten metal on the side of the magnetic field (schematic diagram showing the action of force and the characteristics of the molten metal circulation caused by it, No. 8) Figures (a, b) show the longitudinal section of the induction plasma furnace of Figure 3 according to the present invention. , respectively the side of the crucible part element connected to the electric circuit of the plasma generator and it A schematic diagram showing the action of electromagnetic force acting on the molten metal on the side of the crucible partial element, FIG. 9 shows the molten metal circulation in a longitudinal section of the induction plasma furnace of FIG. 3 according to the present invention. FIG. 10 (a, b) is a schematic diagram showing the characteristics of the derivation of FIG. 4 according to the present invention. This graph shows the effect of the force exerted on the molten metal by the generated electromagnetic field in the longitudinal section of the plasma furnace. Schematic diagram, FIG. 11 shows the molten metal circulation in a longitudinal section of the induction plasma furnace of FIG. 4 according to the present invention. A schematic diagram showing the characteristics of the ring, FIG. 12 (a, b), shows the induction of FIG. In the longitudinal section of a plasma-induced plasma furnace, the force acting on the molten metal due to the generated electromagnetic field is Schematic diagram showing, and FIG. 13 shows the molten metal circulation in a longitudinal section of the induction plasma furnace of FIG. 6 according to the present invention. FIG. 3 is a schematic diagram showing the characteristics of a ring.

BEST MODE FOR CARRYING OUT THE INVENTION In FIG. 1, the induction plasma furnace has a melting crucible 2 housed inside it. Contains heater 1. The induction heater 1 is a crucible, similar to a known induction plasma furnace. A circular cross-section or a special cross-sectional shape arranged along a spiral line surrounding 2. It is made in the shape of a tube. The melting crucible 2 is cylindrical and its side walls are made of conductive material. For example, partial element 3 made of thermeft and arranged vertically (Figs. 1 and 2) Figure). The actual induction plasma reactor shown in Figures 1 and 2. In the embodiment, five sub-elements 3 are shown. 30 of these subelements and the material differs depending on the overall dimensions of the melting crucible 2. The number of subelements is In order to optimize the energy characteristics of induction plasma furnaces, such as efficiency and output, 5 It is desirable to select from a range of 35 to 35.

Partial element 3 can also be made of other electrically conductive materials, such as graphite or metal. . The partial elements 3 are electrically insulated from each other by electrical insulation N6 made of magnesite. The electrically insulating layer 6 is disposed between each of the partial elements 3 and covers the crucible 2. They are arranged on the surface of the sub-element 3 facing inward, on the bottom and also on the end face of the sub-element 3. There is. The thickness of N6 depends on the materials and methods used to provide electrical isolation. and For example, when performing electrical insulation with A140s, the spraying method will form an A1□03 layer. can be achieved.

This induction plasma furnace is an electric arc plasma generator 7 (Fig. 1) that operates with direct current. Also includes. The plasma generator 7 is disposed on the cover 8 of the crucible 2 and generates plasma. It is used by the marc 10 to heat and melt the charge material 9. cover 8 The inner surface of is coated with a lining layer 11. In this example, crucible 2 (Figure 1) The part 12 (FIG. 2) is located near the partial element 30 of the crucible 2 and has an arcuate shape, Electrical insulation is applied and a current is supplied through the molten metal 4 to the plasma generator 70 times. The road is completed.

In the above embodiment of the present invention, of the partial elements 3 of the crucible 2, the bottom 5 (the first The one adjacent to part 12 (Fig. 2) of Fig. It is connected to the.

The direction of the current flowing through the arc 10 of the plasma generating bag W7 is the current flowing through the partial element 3. (The direction of the current is indicated by an arrow in FIG. 1). plasma Current supply terminals 13 and 14 of the generator 7 are connected to a power source, that is, a DC power source in the above example. Connected.

An AC power source may be used as the power source, but when using a DC plasma generator, Must be connected to an AC power source via a rectifier. AC plasma generator is Receives power only from a current source. If necessary, power the induction heater to AC. It may also be used as a power source.

One of the terminals, for example 13, is connected to the bottom of the crucible 2, and the other terminal 14 is connected to the current lead 15 arranged at the top of the partial element 3, and connected to the bottom of the partial element 3. The other current lead section 16 disposed in the section is connected to the plasma generator 7. There is.

In the embodiment of the induced plasma furnace shown in FIG. 3 and the direction of the current flowing through the arc 10 are opposite to each other. It is connected in the circuit of the plasma generator 7. In this case, current lead part 1 5 is connected to the terminal 13, and the plasma generator 7 is connected to the terminal 14. Ru The bottom of the vase 2 is completely covered with an electrically insulating layer 6, and a plasma generator 7 is connected to the bottom. The inner surface portion 17 of the partial element 3 connected in the circuit is not electrically insulated. , transmits the current to the molten metal 4.

In the induction plasma furnace shown in FIG. 4, a melting crucible 18 is made by a known method. It is surrounded by an induction heater 19, and is different from a known induction furnace having a divided cooling crucible. It comprises twelve similarly made sub-elements 20 (FIG. 5). Partial element 20 Each is made of metal, such as copper, and has water, gas, or has a circulation passage 21 for cold liquid.

The partial elements 20 are located on the inwardly facing and mutually facing surfaces of the crucible 18. By means of layers 22 and 23 of an electrically insulating material, for example Aha, sprayed on each They are electrically isolated from each other. Inwardly facing partial elements 20 of the crucible 18 0 surface additionally coated with an electrically insulating layer of magnesite or alundum, for example. You may.

The cover 24 of the crucible 18 is made similarly to the cover 8.

In order to change the characteristics of the circulation of the hot water 4, the six partial elements 20 of the crucible 18 (FIG. 4) (Fig. 5) are connected in parallel to the plasma generator through each of the other subelements. The electric current flowing through the arc 10 of the plasma generator 7 is connected in series to the circuit of 7. The direction of the current and the direction of the current flowing through the partial element 20 are made to be opposite to each other. Ru. The current lead portions 25 disposed on the tops of these partial elements 20 are interconnected. The bottom of each partial element 20 is connected to the current lead 2. 6 to the bottom 27. The bottom part 27 has passages for circulation of the cooling medium. An electrical channel 28 is provided on the inwardly facing bottom 27 surface of the crucible 18. An insulating layer 29 is provided.

In order to supply the molten metal 4 with an electric current, the bottom is ring-shaped and connects the partial elements 20. Portion 30 (FIG. 5) of section 27 is not electrically insulated.

The induced plasma furnace shown in Figure 6 is similar to that shown in Figure 4.5, but All of the partial elements 20 of the pot 18 are connected to the circuit of the plasma generator 7. , so that the current in the arc 10 and the current in the partial element 20 flow in the same direction.

For this purpose, the current lead part 31 arranged on the top of the partial element 20 is connected to the terminal 14. The current lead portion 32 connected to the bottom of the partial element 20 is connected to a plasma generating device. 7 is connected.

The bottom part 27 has no electrical insulation and is connected to the terminal 13.

In Figures 7.8a, b, 10a, b, 12a, b, the electromagnetic field causes the molten metal 4 to The action F of the acting force is shown by an arrow. Induction plasma furnace of Figures 1, 2゜3.4, 5.6 The circulation characteristics of the molten metal inside are shown by the closed line rlJ in Figures 7.9 and 11.13. .

The induction plasma furnace operates as follows.

The solid entertainer material 9 (Fig. 1) is charged into the crucible 2, the cover 8 is closed, and plasma is generated. The device 7 is prepared for ignition of the arc 10. Next, induction heater 1 and plasma generator A voltage is applied to the generator 7 and the arc 10 is started.

The entertainer under the action of the arc 10 of the plasma generator 7 and the electromagnetic field of the induction heater 1 The material dissolution process begins. The arc 10 rapidly melts the layer of entertainer material and the molten metal 4 is formed between the surface of the plasma generator 7 and the plasma generating device 7, and the heat is further transferred to the surrounding entertainer materials. Give. As the melting of the entertainer material progresses and the amount of molten metal 4 increases, the arc 10 The length of the arc 10 decreases, and the conditions for heat transfer from the arc 10 to the molten metal 4 deteriorate. Same as that At times, the conditions for introducing energy from the induction heater 1 into the molten metal 4 are improved.

In the final melting of the entertainer material 9 and the reheating of the molten metal 4, the main energy source is Since the main part is introduced from induction heater 1, the circulation of melt @ 4 has a natural two-path characteristic. , and this property has a desirable effect on heat-mass exchange. After that, In order to remove harmful contaminants, a portion of the slag is passed through the cover 8 in a predetermined manner. It is supplied to the surface of the reheated molten metal 4 in Luppo 2 through another hole (not shown). Ru.

In order to uniformly distribute the slag over the entire surface of the molten metal 4 and to heat it uniformly, the molten metal 4 It is necessary to make the characteristics of the circulation as shown in the blockage line "2" in Fig. 7. For that purpose, Gradually reduce the voltage applied to conductive heater 1 or connect terminals 13 and 14. In the former case, by gradually increasing the applied voltage, the induction heater In the latter case, the current in the circuit of the plasma generator 7 is increased. Ru.

By making the direction of the current the same between the partial element 3 and the arc 10 (after all, the molten metal 4), Then, the molten metal 4 (Fig. 1 ), the molten metal 4 spreads over the entire crucible 2. and circulate in the horizontal plane. If the circulation characteristics are set like this, there will be a menu on the surface of the molten metal 4. No scum appears and the slag flows unhindered under the arc 10 of the plasma generator 7. The slag melts down and heats up faster, increasing furnace production. The homogeneity of the molten metal 4 is improved throughout the crucible 2. Implementation of such a crucible structure According to the embodiment, the current of the induction heater 1 or the arc 10 of the plasma generator 7 By gradually changing the current, the characteristics of the molten metal movement can be changed from circulation in the vertical plane to water flow. Can smoothly change to in-plane circulation.

During the melting process of high purity metals or alloys, slag is formed and removed multiple times.

By using the induction plasma furnace shown in Fig. 3, slag can be removed from the crucible 2. It can facilitate the process of leaving. Circulation of molten metal indicated by blockage line “E” (Fig. 9) The properties of the ring allow stirring of the molten metal 4 (FIG. 3) over the entire height of the crucible 2. P Electrical insulation on the side of the top of the partial element 3 connected in the circuit of the plasma generator 7 In the partial element coated with the molten metal layer 6, the force F acting on the molten metal 4 (Fig. 3) is In Figure 8a), the direction of the current is opposite between the partial element 3 and the arc 10, so the partial The force action F2 (FIG. 8b) on the side of the remainder of element 3 (FIG. 3) is greater.

To preset circulation characteristics that allow slag to accumulate near the location where it is to be removed , by gradually changing the current of the induction heater 1 and the current of the plasma generator 7 circuit. Change the relationship between F and T2.

Generally, melting of high melting point metals or alloys, such as tungsten, is done by cooling. The process is carried out in an induced plasma furnace with a crucible 18 (FIG. 4.5). induction heat Before applying voltage to the generator 19 and the plasma generator 7, the passage of the partial element 20 is 21 and the passages 28 in the bottom 27 should deliver the cooling medium, which will carry out the entire melting process. Circulation of the cooling medium should be maintained throughout. Induction heater 19 and plasma generator After applying voltage to the generator 7, the arc 1.0 is ignited. In this case, Plasz The direction of the current flowing through the sub-elements 20 connected in the circuit of the plasma generator 7 is This direction is opposite to the direction of the current flowing through the arc 10 of the arc generator 7. The amount of molten metal 4 increases As the temperature increases, the molten metal 4 is strongly stirred under the action of the electromagnetic field of the induction heater 19. The surface of the molten metal 4 thus has a convex shape. In this case, the current of the arc 10 flowing through the molten metal 4 is , electrically insulated sub-elements 20 connected in the circuit of the plasma generator. Nearby, there is a tendency to flow along the surface of the molten metal 4.

Therefore, as a component of the force action of the electromagnetic field of the partial element 20, the bottom of the crucible 18 27, which acts on the current flowing through the arc 10 and the molten metal 4. Components generated at the top of the molten metal 4. Along with this operation, the electric current of the partial element 20 causes The component due to the similar cooperative action between the electromagnetic field formed by the electric current flowing through the molten metal 4 is arise. This component moves from the periphery of the molten metal 4 to the center, thereby The force that moves the molten metal 4 away from the partial element 20 of the crucible 18 is increased. Firstly, this This reduces heat losses, protects the electrically insulating layer of the partial element 20 from destruction and Secondly, this increases the height of the molten metal as a columnar body, so the molten metal 4 and the entertainer material The contact zone with the molten metal 4 is expanded, and the effect of absorbing and dissolving the entertainer material by the molten metal 4 is improved. Ru. As a result, the force T acting on the molten metal 4 (Figure 4) (Figures 10a and 10b) Accordingly, the circulation of the single path characteristic "l" (Fig. 11) moves the molten metal 4 (Fig. 4) into the molten metal. In order to carry it upward along the axis directly below the arc 10 together with the entertainer material absorbed in 4. , melting of the material for comedians is possible by shortening the falling time and by stirring over the entire height of the crucible 18. By the end of the period, the homogeneity of the molten metal 4 has improved.

According to the induction plasma furnace shown in Figure 6, during the final melting and reheating of the molten metal, In between, a current flows in the same direction as the current direction of the arc 10 of the plasma generator 7. In connecting the partial element 20 of the crucible 18 to be connected to the circuit of the plasma generator 7. Therefore, the action T (first 2a, b) to increase the power introduced from the induction heater 19. can be set. Circulation characteristic "!" under the action of T (Fig. 12a, b) (Fig. 12a, b) Fig. 3) is similar to the circulation characteristic of the induction heater 19 under the action of the electromagnetic field, and only Only the circulation speed of the molten metal 4 differs. During this period, the induction heater 19 turns the molten metal into By increasing the electrical power introduced, the production of the furnace is significantly increased.

Industrial applicability The induction plasma furnace of the present invention can be used in metallurgical technology to process various, preferably high temperature, metals. Metals or alloys, such as tungsten, are used in large amounts to I can do it.

recognition international search report III+-Internal Rumors-IA Marshal i Awesome 1^-PCT/SU 86100070

Claims (1)

[Claims] Induction heaters (1, 1) containing melting crucibles (2, 18) with cylindrical side walls 9) and the molten metal (4) contained in the crucible (2, 18) to complete an electric circuit. In an induction plasma furnace comprising an electric arc plasma generator (7) , the side walls of the crucible (2, 18) are vertically arranged partial elements (3, 2) of conductive material. 0), the partial elements are electrically insulated from each other, and the partial elements are electrically insulated from each other. At least one of the sub-elements is configured to control the electric current of the arc (10) of the plasma generator (7). The direction of the flow is the same as the direction of the current in the partial element (3, 20) of the crucible (2, 18). connected in series with the electrical circuit of the plasma generator (7) so that the An induction plasma furnace characterized by being connected to an induction plasma furnace.