A system and method for coupling a gas-based vertical furnace and a double-shell electric arc furnace

Abstract

The present invention relates to a system and method for coupling a gas-based vertical furnace and a double-shell electric arc furnace, and belongs to the field of ironmaking. The system includes a gas-based vertical furnace and a double-shell electric arc furnace; a sealed unloading device is correspondingly arranged below the discharge port at the bottom of the gas-based vertical furnace; the double-shell electric arc furnace includes two furnace bodies that can rotate relative to each other, and the two furnace bodies switch back and forth between the loading station and the smelting station; the two furnace bodies are provided with a protective gas device for introducing protective gas into the corresponding furnace bodies; when the furnace body rotates to the loading station, it is located below the sealed unloading device, and the furnace body and the sealed unloading device are connected through a sealed flexible connection device, and the sealed unloading device and the sealed flexible connection device form a sealed transmission channel for feeding to the furnace body; when the furnace body rotates to the smelting station, smelting operations are carried out. Sealed hot delivery of hot sponge iron is realized, heat loss is reduced, and oxidation is avoided; the two furnace bodies of the double-shell electric arc furnace cooperate with the production rhythm of the gas-based vertical furnace to improve production efficiency and save energy and reduce consumption.

Description

Technical Field

[0001] The invention belongs to the field of ironmaking, and relates to a system and method for coupling a gas-based vertical furnace and a double-shell electric arc furnace. Background Art

[0002] The gas-based vertical furnace ironmaking process refers to an industrial production process that uses reducing gases such as CH4 to reduce iron ore in a vertical furnace to produce solid sponge iron with a high metallization rate. At present, the gas-based vertical furnace process is a relatively mature technology. In 2019, the sponge iron produced by the gas-based vertical furnace process exceeded 100 million tons, forming a short-process steelmaking process (gas-based vertical furnace-electric furnace process) that is different from the typical blast furnace ironmaking process. However, due to the high metallization rate, low carbon content, and high porosity of hot sponge iron (HDRI), HDRI has a high reduction activity and is easily oxidized. Therefore, it needs to be cooled to below 50°C in a protective gas and transported to an electric furnace for smelting, or hot transported to an electric furnace for smelting under the protection of an inert gas. The former requires HDRI to be cooled in a reducing atmosphere and then discharged from the reactor, resulting in a large amount of sensible heat waste in HDRI, making the electric furnace smelting power consumption high, and the preparation of reducing cooling gas also increases the investment in gas production equipment. The latter requires the construction of a huge HDRI heat delivery device, which requires high equipment investment, and heat loss is inevitable during the HDRI transportation process. The HDRI temperature of the advanced HDRI heat delivery device sent to the steelmaking electric furnace is about 550℃, and the temperature drop is obvious. The current gas-based vertical furnace-electric furnace process not only wastes a lot of sensible heat of HDRI, resulting in high power consumption, but also lacks a coupling and coordinated production mechanism between the gas-based vertical furnace and the electric furnace (the annual operating time of the electric furnace is usually less than that of the gas-based vertical furnace). Part of the sponge iron has to be cooled in a protective atmosphere and then stacked, resulting in reduced production efficiency and increased power consumption of the electric furnace. Summary of the invention

[0003] In view of this, an object of the present invention is to provide a system and method for coupling a gas-based vertical furnace and a double-shell electric arc furnace to solve the shortcomings of the current gas-based vertical furnace-electric furnace process.

[0004] In order to achieve the above object, the present invention provides the following technical solutions:

[0005] A system in which a gas-based vertical furnace and a double-shell electric arc furnace are coupled comprises a gas-based vertical furnace and a double-shell electric arc furnace; a sealed unloading device is correspondingly arranged below a discharge port at the bottom of the gas-based vertical furnace; the double-shell electric arc furnace comprises two furnace bodies that can rotate relatively, and the two furnace bodies switch back and forth between a loading station and a smelting station; protective gas devices for introducing protective gas into the corresponding furnace bodies are arranged on the two furnace bodies; when the furnace body rotates to the loading station, it is located below the sealed unloading device, and the furnace body and the sealed unloading device are connected through a sealed flexible connection device, and the sealed unloading device and the sealed flexible connection device form a sealed transmission channel for feeding materials to the furnace body; when the furnace body rotates to the smelting station, smelting operations are performed.

[0006] Furthermore, the sealed unloading device includes a honeycomb wheel discharger for controlling the unloading and material speed.

[0007] Furthermore, the sealing flexible connection device is a bellows, which can withstand a temperature greater than 800°.

[0008] Furthermore, the protective gas device includes a high-temperature nozzle; there are multiple high-temperature nozzles on each furnace body of the double-shell electric arc furnace, which are evenly distributed on the upper part of the furnace body to spray high-temperature protective gas into the furnace body.

[0009] Furthermore, the double-shell electric arc furnace also includes a furnace body rotating device located at the furnace body rotation center for controlling the rotation of the furnace body, a furnace body clamping device respectively connected to the furnace body rotating device and clamping the furnace body, an electrode located at the smelting station for inserting the electrode into the furnace body, an electrode lifting device for controlling the lifting of the electrode, and an exhaust device respectively arranged on the upper part of the furnace body for balancing the internal and external air pressure of the furnace body during loading.

[0010] Furthermore, a charging port is provided at the top of the gas-based vertical furnace, a reducing gas inlet is provided at the side waist, and a reducing tail gas outlet is provided at the side upper part.

[0011] A method for coupling a gas-based vertical furnace and a double-shell electric arc furnace comprises the following steps:

[0012] S1. Open the protective gas device of one of the furnace bodies of the double-shell electric arc furnace, and introduce protective gas into the furnace body; rotate the furnace body to the loading station, and place it below the sealed unloading device, and connect the furnace body to the sealed unloading device through the sealed flexible connection device; open the sealed unloading device, and use the sealed unloading device and the sealed flexible connection device to load the hot sponge iron obtained by smelting in the gas-based vertical furnace into the furnace body; after being fully loaded, close the sealed unloading device, disconnect the sealed flexible connection device, and at this time, the sealed unloading device temporarily stores the hot sponge iron from the gas-based vertical furnace; the fully loaded furnace body leaves the loading station and turns to the smelting station;

[0013] S2. Perform the operation as in step S1 on another furnace;

[0014] S3. The fully loaded furnace body is rotated to the smelting station for smelting, and after smelting, the steel is tapped and the furnace is replenished, and then the smelting station is left and the charging station is turned;

[0015] S4. When the furnace body after smelting is close to the loading station, the furnace body at the loading station reaches full load, the sealing unloading device is closed, the sealing soft connection device is disconnected, and the fully loaded furnace body leaves the loading station and turns to the smelting station;

[0016] S5. Steps S1 to S4 are repeated so that the two furnace bodies are switched back and forth between the charging station and the smelting station, thereby realizing the coupling of the gas-based vertical furnace and the double-shell electric arc furnace.

[0017] Furthermore, before charging into the furnace body, the air in the furnace body and the sealed flexible connection device has been exhausted; the protective gas introduced into the furnace body is nitrogen, the nitrogen temperature is greater than 800° C., and the purity is greater than 99.99%.

[0018] Furthermore, the total smelting cycle of the double-shell electric arc furnace is greater than the smelting cycle of the gas-based vertical furnace, and the cycle difference is controlled within 1 minute; the closing time of the sealed unloading device is less than 30 seconds each time.

[0019] Furthermore, for the furnace body at the smelting position, before starting smelting, the electrode is lowered into the furnace body through the electrode lifting device, so that the temperature of the hot sponge iron in the furnace body is greater than 700°; during the smelting process, the hot sponge iron completes the melting period, oxidation period, and reduction period in the furnace body in sequence, and then the steel is discharged and the furnace is replenished. After the electrode penetrates the well, the protective gas device is turned off.

[0020] The beneficial effects of the present invention are:

[0021] (1) The present invention builds a sealed transfer channel formed by a sealed unloading device and a sealed flexible connection device, and realizes sealed heat transfer from the gas-based vertical furnace to the furnace body of the double-shell electric arc furnace through the sealed transfer channel, thereby reducing heat loss during the transfer process and preventing HDRI from being oxidized; at the same time, the two furnace bodies of the double-shell electric arc furnace switch back and forth between the loading station and the smelting station, coordinating with the production rhythm of the gas-based vertical furnace to form a coordinated production mechanism, thereby realizing continuous loading and smelting work, and HDRI does not need to be cooled and stacked in the middle, thereby improving production efficiency and saving energy and reducing consumption.

[0022] (2) The system and method for coupling a gas-based vertical furnace and a double-shell electric arc furnace provided by the present invention have a HDRI metallization rate greater than 92%, a power consumption per ton of steel less than 400 kw·h / t, an operating cycle of the entire system less than 50 min, and a total smelting cycle of the double-shell electric arc furnace less than 45 min.

[0023] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0025] Figure 1 It is a schematic diagram of the arrangement of a system in which a gas-based vertical furnace and a double-shell electric arc furnace are coupled according to the present invention;

[0026] Figure 2 It is a top view of a double-shell electric arc furnace, with furnace body A at the charging station and furnace body B turning to the smelting station;

[0027] Figure 3 It is a top view of a double-shell electric arc furnace, with furnace body A at the charging position and furnace body B at the smelting position;

[0028] Figure 4 It is a top view of a double-shell electric arc furnace, in which furnace body A is at the charging station and furnace body B is turned to the charging station.

[0029] Figure numerals: iron ore 1, reducing gas 2, gas-based vertical furnace 3, sealed flexible connection device 4, protective gas device 5, furnace body A6, furnace body B7, sealed unloading device 8, exhaust device 9, furnace body rotating device 10, furnace body clamping device 11, electrode 12, electrode lifting device 13, reducing tail gas 14. DETAILED DESCRIPTION

[0030] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0031] Among them, the drawings are only used for illustrative explanations, and they only represent schematic diagrams rather than actual pictures, and should not be understood as limitations on the present invention. In order to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0032] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "front", "rear", etc. indicate the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0033] See also Figure 1 to Figure 4 , which is a system in which a gas-based vertical furnace and a double-shell electric arc furnace are coupled, comprising a gas-based vertical furnace 3 and a double-shell electric arc furnace.

[0034] The top of the gas-based vertical furnace 3 is provided with a charging port for charging iron ore 1, the side waist is provided with a reducing gas inlet for introducing reducing gas 2, the upper side is provided with a reducing tail gas outlet for discharging reducing tail gas 14, and the bottom is provided with a discharging port for unloading HDRI obtained by smelting.

[0035] The double shell electric arc furnace includes a furnace body A6 and a furnace body B7, and also includes a furnace body rotating device located at the rotation center of the furnace body A6 and the furnace body B7 for controlling the rotation of the furnace body A6 and the furnace body B7, a furnace body clamping device connected to the furnace body rotating device and clamping the furnace body A6 and the furnace body B7, an electrode 12 located at the smelting station to be inserted into the furnace body A6 or the furnace body B7, an electrode lifting device 13 for controlling the lifting of the electrode 12, and an exhaust device 9 respectively arranged on the upper part of the furnace body A6 and the furnace body B7 for balancing the internal and external air pressure of the corresponding furnace body during charging. The furnace body A6 and the furnace body B7 can rotate relative to each other and switch back and forth between the charging station and the smelting station.

[0036] The furnace body A6 and the furnace body B7 are provided with a protective gas device 5 for introducing protective gas into the corresponding furnace body; the protective gas device 5 includes a high-temperature nozzle; there are multiple high-temperature nozzles on the furnace body A6 and the furnace body B7, which are evenly distributed on the upper part of the corresponding furnace body to spray high-temperature protective gas into the corresponding furnace body. In this embodiment, the protective gas is nitrogen.

[0037] A sealed discharge device 8 is provided below the discharge port at the bottom of the gas-based vertical furnace 3. The sealed discharge device 8 includes a honeycomb wheel discharger for controlling the discharge and material speed. The sealed discharge device 8 can ensure that HDRI is not oxidized and can temporarily store a small amount of HDRI in the closed state.

[0038] The sealed discharge device 8 and the furnace body A6 or the furnace body B7 of the double-shell electric arc furnace are connected by a sealed flexible connection device 4. In this embodiment, the sealed flexible connection device 4 is a bellows, which can withstand a temperature greater than 800°.

[0039] When furnace body A6 or furnace body B7 rotates to the loading station, it is located below the sealed unloading device 8, and the corresponding furnace body and the sealed unloading device 8 are connected through the sealed flexible connection device 4. The sealed unloading device 8 and the sealed flexible connection device 4 form a sealed transmission channel for feeding materials to furnace body A6 or furnace body B7; when furnace body A6 or furnace body B7 rotates to the smelting station, smelting operations are carried out.

[0040] The method for coupling the gas-based vertical furnace 3 and the double-shell electric arc furnace using the system comprises the following steps:

[0041] S1. Open the protective gas device 5 of the furnace body B7 of the double-shell electric arc furnace, and introduce nitrogen into the furnace body B7; rotate the furnace body B7 to the loading station, and place it below the sealed unloading device 8, and connect the furnace body B7 with the sealed unloading device 8 through the sealed flexible connection device 4; open the sealed unloading device 8, and use the sealed unloading device 8 and the sealed flexible connection device 4 to load the hot sponge iron smelted in the gas-based vertical furnace 3 into the furnace body B7; after being fully loaded, close the sealed unloading device 8, disconnect the sealed flexible connection device 4, and at this time, the sealed unloading device 8 temporarily stores the hot sponge iron from the gas-based vertical furnace 3; the fully loaded furnace body B7 leaves the loading station and turns to the smelting station;

[0042] S2. Perform the operation as in step S1 on the furnace body A6;

[0043] S3. The fully loaded furnace body B7 is rotated to the smelting station. Before starting smelting, the electrode 12 is lowered into the furnace body B7 by the electrode lifting device 13, so that the temperature of the hot sponge iron in the furnace body B7 is greater than 700°; during the smelting process, the hot sponge iron in the furnace body B7 completes the melting period, oxidation period, and reduction period in sequence, and then the steel is tapped and the furnace is replenished. After the electrode 12 penetrates the well, the protective gas device 5 is turned off; then leave the smelting station and turn to the loading station;

[0044] S4. When the furnace body B7 after smelting is adjacent to the loading station, the furnace body A6 at the loading station reaches full load, the sealing unloading device 8 is closed, the sealing soft connection device 4 is disconnected, and the fully loaded furnace body A6 leaves the loading station and turns to the smelting station;

[0045] S5. Steps S1 to S4 are repeated so that the furnace body A6 and the furnace body B7 are switched back and forth between the charging station and the smelting station, thereby achieving coupling between the gas-based vertical furnace 3 and the double-shell electric arc furnace.

[0046] In this embodiment, the temperature of the nitrogen used as the protective gas is greater than 800°C and the purity is greater than 99.99%. The nitrogen flow rate of each high-temperature nozzle is given by the formula q=V 炉 / 4t 转 (m 3 / s) is determined by, where V 炉 is the volume of the double shell electric arc furnace (m 3 ), t 转 It is the time (s) for the furnace to transfer from the smelting station to the charging station.

[0047] The material discharge speed of the sealed discharge device 8 is given by the formula u = 1000M D / (3600-t 闭 )(kg / s) is determined by, where M D (t / h) is the output of HDRI per hour, t 闭 (s) is the closing time of the sealing discharge device 8, t 闭 Should be less than 30s.

[0048] During the charging period, when the furnace body A6 or the furnace body B7 is transferred from the charging station to the smelting station and when the HDRI is heated and melted, the protective gas device 5 is in the open state, and the gas pressure inside and outside the furnace body can be balanced through the exhaust device 9. Before HDRI unloading, it should be ensured that the air in the furnace body A6 or the furnace body B7 and the sealing flexible connection device 4 has been exhausted.

[0049] The total smelting cycle of the double-shell electric arc furnace (including the furnace body rotation time and the furnace filling time) is longer than the smelting cycle of the gas-based vertical furnace, and the cycle difference is controlled within 1 minute. In general, the metallization rate of HDRI is greater than 92%, the power consumption per ton of steel is less than 400kw·h / t, the operation cycle of the entire system is less than 50min, and the total smelting cycle of the double-shell electric arc furnace is less than 45min.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A system of coupling a gas-based vertical furnace and a double-shell electric arc furnace, characterized in that: It comprises a gas-based vertical furnace and a double-shell electric arc furnace; a sealed unloading device is correspondingly arranged below the discharge port at the bottom of the gas-based vertical furnace; the double-shell electric arc furnace comprises two furnace bodies that can rotate relative to each other, and the two furnace bodies switch back and forth between the loading station and the smelting station; a protective gas device for introducing protective gas into the corresponding furnace body is arranged on the two furnace bodies; when the furnace body rotates to the loading station, it is located below the sealed unloading device, and the furnace body and the sealed unloading device are connected through a sealed flexible connection device, and the sealed unloading device and the sealed flexible connection device form a sealed transmission channel for feeding materials to the furnace body; When the furnace body rotates to the smelting station, smelting operation is carried out; The protective gas device includes a high-temperature nozzle; each furnace body of the double-shell electric arc furnace has a plurality of high-temperature nozzles, which are evenly distributed on the upper part of the furnace body to spray high-temperature protective gas into the furnace body; The double-shell electric arc furnace further comprises a furnace body rotating device located at the furnace body rotating center for controlling the furnace body rotation, a furnace body clamping device respectively connected to the furnace body rotating device and clamping the furnace body, an electrode located at the smelting station for inserting the electrode into the furnace body, an electrode lifting device for controlling the lifting of the electrode, and an exhaust device respectively arranged at the upper part of the furnace body for balancing the internal and external air pressure of the furnace body during charging; The total smelting cycle of the double-shell electric arc furnace is greater than that of the gas-based vertical furnace, and the cycle difference is controlled within 1 minute; the closing time of the sealed unloading device is less than 30 seconds each time.

2. The system of coupling a gas-based vertical furnace and a double-shell electric arc furnace according to claim 1, characterized in that: The sealed unloading device comprises a honeycomb wheel discharger for controlling the unloading and material speed.

3. The system of coupling a gas-based vertical furnace and a double-shell electric arc furnace according to claim 1, characterized in that: The sealing flexible connection device is a bellows, which can withstand a temperature greater than 800°C.

4. The system of coupling a gas-based vertical furnace and a double-shell electric arc furnace according to claim 1, characterized in that: The top of the gas-based vertical furnace is provided with a charging port, the side waist is provided with a reducing gas inlet, and the upper side is provided with a reducing tail gas outlet.

5. A method for a system of coupling a gas-based vertical furnace and a double-shell electric arc furnace according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1. Open the protective gas device of one of the furnace bodies of the double-shell electric arc furnace, and introduce protective gas into the furnace body; rotate the furnace body to the loading station, and place it below the sealed unloading device, and connect the furnace body to the sealed unloading device through the sealed flexible connection device; open the sealed unloading device, and use the sealed unloading device and the sealed flexible connection device to load the hot sponge iron obtained by smelting in the gas-based vertical furnace into the furnace body; after being fully loaded, close the sealed unloading device, disconnect the sealed flexible connection device, and at this time, the sealed unloading device temporarily stores the hot sponge iron from the gas-based vertical furnace; the fully loaded furnace body leaves the loading station and turns to the smelting station; S2. Perform the operation as in step S1 on another furnace; S3. The fully loaded furnace body is rotated to the smelting station for smelting, and after smelting, the steel is tapped and the furnace is replenished, and then the smelting station is left and the charging station is turned; S4. When the furnace body after smelting is close to the loading station, the furnace body at the loading station reaches full load, the sealing unloading device is closed, the sealing soft connection device is disconnected, and the fully loaded furnace body leaves the loading station and turns to the smelting station; S5. Cycle steps S1 to S4, so that the two furnace bodies switch back and forth between the charging station and the smelting station to achieve the coupling of the gas-based vertical furnace and the double-shell electric arc furnace; Before charging into the furnace, the air in the furnace and the sealed flexible connection device has been exhausted; the protective gas introduced into the furnace is nitrogen, the nitrogen temperature is greater than 800°C, and the purity is greater than 99.99%; The total smelting cycle of the double-shell electric arc furnace is greater than that of the gas-based vertical furnace, and the cycle difference is controlled within 1 minute; the closing time of the sealed unloading device is less than 30 seconds each time.

6. The method of the system of coupling a gas-based vertical furnace and a double shell electric arc furnace according to claim 5, characterized in that: For the furnace body at the smelting position, before starting smelting, the electrode is lowered into the furnace body through the electrode lifting device to make the temperature of the hot sponge iron in the furnace body greater than 700°C; during the smelting process, the hot sponge iron completes the melting period, oxidation period, and reduction period in the furnace body in sequence, and then the steel is tapped and the furnace is replenished. After the electrode penetrates the well, the protective gas device is turned off.

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