Auxiliary electrode of direct-current electric arc furnace

Abstract

The utility model discloses an auxiliary electrode of a direct-current electric arc furnace, which belongs to the technical field of electric arc furnaces and is characterized in that an auxiliary anode is arranged, so that the cathode current of the electric arc furnace is increased under the condition that the anode current of the electric arc furnace is not changed, and the temperature of a cathode molten pool of the electric arc furnace is increased; the auxiliary anode does not need to be additionally provided with a direct-current power supply, the silicon controlled rectifier power supplies of the anode and the cathode of the electric arc furnace are directly utilized, the equipment investment is greatly reduced, the power supply structure is simplified, and the silicon controlled rectifier four-electrode without the bottom electrode is also suitable for the direct-current electric arc furnace with six or more electrodes. The two IGBTs can be combined into one IGBT.

Description

Technical Field

[0001] The utility model belongs to the technical field of electric arc furnaces, in particular to an auxiliary electrode for a direct current electric arc furnace. Background Art

[0002] At present, the temperature of the two anode molten pools of the thyristor rectifier four-electrode DC arc furnace without bottom electrode is obviously higher than the temperature of the two cathode molten pools, which leads to inconsistent temperature inside the electric furnace, especially the temperature of the furnace center and the temperature of the arc furnace cathode molten pool are relatively low, affecting the requirements of electric furnace smelting production, and has a great impact on product quality, output and unit energy consumption. This is a common problem of the thyristor rectifier four-electrode DC arc furnace without bottom electrode, and it is urgent to solve this problem. Utility Model Content

[0003] The technical solution of the utility model is as follows: an auxiliary electrode for a DC electric arc furnace, comprising: a first thyristor rectifier, a first electric arc furnace anode, a first electric arc furnace cathode, a second thyristor rectifier, a second electric arc furnace anode, a second electric arc furnace cathode, a first IGBT, a second IGBT and an auxiliary anode, wherein the first thyristor rectifier, the first electric arc furnace anode and the first electric arc furnace cathode form a power supply circuit; the second thyristor rectifier, the second electric arc furnace anode and the second electric arc furnace cathode form another power supply circuit; the first IGBT, the second IGBT, the auxiliary anode, the first electric arc furnace cathode and the second arc furnace cathode form an auxiliary power supply circuit.

[0004] Furthermore, the collector of the first IGBT is connected to the positive electrode of the first thyristor rectifier, the collector of the second IGBT is connected to the positive electrode of the second thyristor rectifier, and the emitters of the first IGBT and the second IGBT are connected and then connected to the auxiliary anode.

[0005] Furthermore, the thyristor rectifier is a 2000A / 50V thyristor rectifier power supply.

[0006] Furthermore, the current of the first electric arc furnace anode and the first electric arc furnace cathode is 1210A, and the current of the second electric arc furnace anode and the second electric arc furnace cathode is 1200A.

[0007] Furthermore, the voltage between the first arc furnace anode and the first arc furnace cathode is 43.5V, and the voltage between the second arc furnace anode and the second arc furnace cathode is 42.6V.

[0008] A method for controlling auxiliary electrodes of a direct current arc furnace is disclosed. When a control circuit turns on a first IGBT, the potential of the auxiliary anode is the same as the positive electrode of a first thyristor rectifier, and current flows between the auxiliary anode and the cathode of the first arc furnace. The control circuit adjusts the duty cycle of the first IGBT being turned on and off to control the magnitude of the auxiliary anode current. When the control circuit turns on a second IGBT, the potential of the auxiliary anode is the same as the positive electrode of the second thyristor rectifier, and current flows between the auxiliary anode and the cathode of the second arc furnace. The control circuit adjusts the duty cycle of the second IGBT being turned on and off to control the magnitude of the auxiliary anode current.

[0009] The beneficial effects of the utility model are:

[0010] The auxiliary anode increases the arc furnace cathode current while maintaining the same anode current, thereby raising the temperature of the arc furnace cathode molten pool. The auxiliary anode does not require an additional DC power supply, directly utilizing the thyristor rectifier power supply for the arc furnace's anode and cathode, significantly reducing equipment investment and simplifying the power supply structure. In addition to the four-electrode thyristor rectifier without a bottom electrode proposed in this utility model, it is also applicable to DC arc furnaces with six or more electrodes. IGBT1 and IGBT2 can also be combined into a single IGBT. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a circuit diagram of the utility model.

[0012] In the picture:

[0013] 1. First thyristor rectifier, 2. First arc furnace anode, 3. First arc furnace cathode, 4. Second thyristor rectifier, 5. Second arc furnace anode, 6. Second arc furnace cathode, 7. First IGBT, 8. Second IGBT, 9. Auxiliary anode, 10. Arc furnace wall. DETAILED DESCRIPTION

[0014] It should be noted that in the description of the present invention, the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", "clockwise", "counterclockwise", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction.

[0015] In this utility model, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, "fixed" can refer to a fixed connection, a detachable connection, or an integral connection; connection can refer to a mechanical connection or an electrical connection; connection can refer to a direct connection or an indirect connection through an intermediate medium, and can refer to internal communication between two components or an interaction between two components. Those skilled in the art will be able to understand the specific meanings of the above terms in this utility model based on specific circumstances.

[0016] A DC arc furnace auxiliary electrode includes a first thyristor rectifier 1, a first arc furnace anode 2, a first arc furnace cathode 3, a second thyristor rectifier 4, a second arc furnace anode 5, a second arc furnace cathode 6, a first IGBT 7, a second IGBT 8 and an auxiliary anode 9.

[0017] The first thyristor rectifier 1, first arc furnace anode 2, and first arc furnace cathode 3 form one power supply circuit of a previous thyristor rectifier four-electrode DC arc furnace. The second thyristor rectifier 4, second arc furnace anode 5, and second arc furnace cathode 6 form another power supply circuit of the previous thyristor rectifier four-electrode DC arc furnace. The first IGBT 7, second IGBT 8, auxiliary anode 9, first arc furnace cathode 3, and second arc furnace cathode 6 form the auxiliary power supply circuit of this utility model.

[0018] Previously, when the current of the arc furnace anode and the arc furnace cathode was the same, the temperature of the arc furnace anode molten pool was significantly higher than the temperature of the arc furnace cathode molten pool, which created a low-temperature zone near the arc furnace cathode, affecting metal smelting.

[0019] The method is to add an electric arc furnace auxiliary anode 9, which is connected to the positive electrode of the first thyristor rectifier 1 through the collector of the first IGBT 7, the collector of the second IGBT 8 and the positive electrode of the second thyristor rectifier 4, the emitters of the first IGBT 7 and the second IGBT 8, and then connected to the auxiliary anode 9; when the control circuit turns on the first IGBT 7, the potential of the auxiliary anode 9 is the same as the positive electrode of the first thyristor rectifier 1 (ignoring the conduction voltage drop of the first IGBT 7), and current flows between the auxiliary anode 9 and the cathode 3 of the first electric arc furnace. The magnitude of the current of the auxiliary anode 9 can be controlled by adjusting the duty cycle of the conduction and shutdown of the first IGBT 7 through the control circuit; when the control circuit turns on the second IGBT 8, the potential of the auxiliary anode 9 is the same as the positive electrode of the second thyristor rectifier 4 (ignoring the conduction voltage drop of the second IGBT 8), and the auxiliary anode 9 is connected to the positive electrode of the second thyristor rectifier 4. Current flows between the anode 9 and the cathode 6 of the second arc furnace. The current of the auxiliary anode 9 can be controlled by adjusting the duty cycle of the second IGBT8 on and off through the control circuit; the current of the auxiliary anode 9 does not affect the current of the arc furnace anode and the arc furnace cathode, so that the current of the arc furnace cathode can be appropriately increased while the anode current of the arc furnace remains unchanged, thereby ensuring that the temperature of the arc furnace electrode pool is basically the same. As long as the position of the arc furnace electrode is reasonably arranged, the temperature of the smelting area inside the entire DC furnace can be guaranteed to fully meet the production requirements, thereby completely solving the problems of low furnace center temperature and low arc furnace cathode molten pool temperature that were common in the previous thyristor rectifier four-electrode DC arc furnace without bottom electrode, which has a significant effect on improving product quality, output and reducing unit energy consumption, and at the same time provides technical feasibility for the future development of ultra-high power DC arc furnaces.

[0020] In a practical demonstration, two 2000A / 50V thyristor rectifier power supplies, five graphite electrodes, and silicon-manganese raw material were used for the experiment. Constant current control was used, with the current flowing through arc furnace anode 1 and cathode 1 being 1210A, and the current flowing through anode 2 and cathode 2 being 1200A. The voltage between anode 1 and cathode 1 was 43.5V, and the voltage between anode 2 and cathode 2 was 42.6V. After 60 minutes, the temperatures near the four electrodes, measured using an infrared thermometer, were: arc furnace anode 1: 1060°C, arc furnace anode 2: 1052°C, arc furnace cathode 1: 908°C, and arc furnace cathode 2: 905°C. Inserting the auxiliary anode resulted in virtually no change in the current and voltage at the anode and cathode of the arc furnace. IGBT1 and IGBT2 also use constant current control when working. When IGBT1 and IGBT2 are both working at 60A (auxiliary anode current is 120A), the voltage between arc furnace anode 1 and arc furnace cathode 1 is 44.5V, and the voltage between arc furnace anode 2 and arc furnace cathode 2 is 43.6V. After 30 minutes, the temperatures near the five electrodes are measured as follows: arc furnace anode 1 temperature: 1080°C, arc furnace anode 2 temperature: 1076°C, arc furnace cathode 1 temperature: 1035°C, arc furnace cathode 2 temperature: 1030°C, auxiliary anode temperature: 10 63℃; when IGBT1 and IGBT2 are working at the same time with the current of 150A (auxiliary anode current is 300A), the voltage between arc furnace anode 1 and arc furnace cathode 1 is 46.1V, and the voltage between arc furnace anode 2 and arc furnace cathode 2 is 45.6V. After 30 minutes, the temperatures near the five electrodes are measured as follows: arc furnace anode 1 temperature: 1087℃, arc furnace anode 2 temperature: 1081℃, arc furnace cathode 1 temperature: 1083℃, arc furnace cathode 2 temperature: 1080℃, auxiliary anode temperature: 1089℃; the temperature in the whole furnace is relatively uniform, and the effect is very good.

[0021] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by any person skilled in the art within the technical scope disclosed herein and within the spirit and principles of the present invention shall be covered by the scope of protection of the present invention. Furthermore, any matters not described in detail in this specification constitute prior art known to those skilled in the art.

[0022] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting; it is not intended to be used to limit the scope of the present application. Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art to which this application belongs. The singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

Claims

1. A DC arc furnace auxiliary electrode, characterized in that: include: The first thyristor rectifier, the first arc furnace anode, the first arc furnace cathode, the second thyristor rectifier, the second arc furnace anode, the second arc furnace cathode, the first IGBT, the second IGBT and the auxiliary anode, wherein the first thyristor rectifier, the first arc furnace anode and the first arc furnace cathode form a power supply circuit; the second thyristor rectifier, the second arc furnace anode and the second arc furnace cathode form another power supply circuit; the first IGBT, the second IGBT, the auxiliary anode, the first arc furnace cathode and the second arc furnace cathode form an auxiliary power supply circuit.

2. The DC arc furnace auxiliary electrode according to claim 1, characterized in that: The collector of the first IGBT is connected to the positive electrode of the first thyristor rectifier, the collector of the second IGBT is connected to the positive electrode of the second thyristor rectifier, and the emitters of the first IGBT and the second IGBT are connected and then connected to the auxiliary anode.

3. The DC arc furnace auxiliary electrode according to claim 1, characterized in that: The thyristor rectifier is a 2000A / 50V thyristor rectifier power supply.

4. The auxiliary electrode for a DC arc furnace according to claim 1, characterized in that: The current of the first arc furnace anode and the first arc furnace cathode is 1210A, and the current of the second arc furnace anode and the second arc furnace cathode is 1200A.

5. The DC arc furnace auxiliary electrode according to claim 1, characterized in that: The voltage between the first arc furnace anode and the first arc furnace cathode is 43.5V, and the voltage between the second arc furnace anode and the second arc furnace cathode is 42.6V.

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