Steelmaking electric arc furnace and steelmaking method thereof

Abstract

The invention provides a steelmaking electric arc furnace and a steelmaking method thereof.The steelmaking electric arc furnace comprises an electric arc furnace body and a horizontal waste steel conveying and preheating device, and the electric arc furnace body is arranged at an outlet of the horizontal waste steel conveying and preheating device and used for receiving waste steel from the horizontal waste steel conveying and preheating device; the received scrap steel is smelted to obtain molten steel and slag; the horizontal waste steel conveying and preheating device is used for preheating the waste steel received from the waste steel feeding device and conveying the preheated waste steel to the electric arc furnace body; the horizontal steel scrap conveying and preheating device comprises a steel scrap conveying device, a horizontal connecting trolley, a horizontal connecting trolley smoke hood, a steel scrap preheating channel smoke hood, a dynamic sealing device, a gas collecting header pipe, a primary flue and a settling chamber. By means of the technical scheme, the double effects of reducing smelting energy consumption and improving the production rate can be achieved.

Description

Technical Field

[0001] The invention relates to the field of electric arc furnace steelmaking, in particular to a steelmaking electric arc furnace and a steelmaking method thereof. Background Art

[0002] In the modern steel industry, ultra-high power electric arc furnace (EAF) has become one of the main ways of steelmaking due to its high efficiency and environmental protection characteristics. However, electric arc furnaces produce a large amount of high-temperature flue gas during the steelmaking process. These flue gases will take away a large amount of heat during the emission process, accounting for about half of the input electrical energy. This waste of energy not only causes resource loss, but also increases production costs. In order to reduce energy loss and improve production efficiency, scrap steel preheating technology has emerged. This technology recovers the heat in the exhaust flue gas and preheats the scrap steel before entering the furnace to a certain temperature, thereby reducing energy consumption in the smelting process and shortening the melting time. The traditional practice is to use a horizontal scrap steel preheating electric furnace, in which the scrap steel and the high-temperature flue gas are heat exchanged in the preheating section. Although this design can preheat the scrap steel to 250-300°C, since the heat exchange mainly occurs between the top scrap steel and the flue gas, the preheating effect of the lower scrap steel is not ideal, resulting in the actual preheating temperature being far lower than the declared value.

[0003] In order to improve this problem, a shaft-type scrap steel preheating electric furnace was developed. In this design, high-temperature flue gas rises from the bottom of the shaft and conducts more sufficient heat exchange with cold scrap steel, which is expected to preheat the scrap steel to 600°C. However, actual operation data shows that the preheating temperature is usually between 500 and 540°C. Although the preheating effect has been improved, this high-temperature preheating also brings new problems, that is, a large amount of toxic gas may be generated during the preheating process, especially when cheap scrap steel containing chlorinated hydrocarbons such as paint, grease, and plastic is used. In order to meet environmental protection requirements, these toxic flue gases must be treated. The usual practice is to use a burner to heat the flue gas to more than 1000°C to decompose toxic substances, and then rapidly cool it by spraying water mist to prevent the secondary generation of toxic substances. Finally, the remaining toxic substances are adsorbed by spraying activated carbon powder into the flue gas. This process not only increases the complexity of the system, but also reduces the energy-saving effect of scrap steel preheating because of the need for additional fuel.

[0004] In summary, although scrap steel preheating technology has significant advantages in improving production efficiency and reducing energy consumption, its practical application still has problems such as unsatisfactory preheating effect and complicated toxic gas treatment. Therefore, developing a steelmaking electric arc furnace and steelmaking method that can effectively increase the scrap steel preheating temperature and simplify the toxic gas treatment process is a technical challenge that the current steel industry needs to solve urgently. Summary of the invention

[0005] The embodiment of the present invention provides a steelmaking electric arc furnace and a steelmaking method thereof, so as to achieve the dual effects of reducing smelting energy consumption and improving productivity.

[0006] In order to achieve the above object, on the one hand, a steelmaking electric arc furnace and a steelmaking method thereof are provided, wherein the steelmaking electric arc furnace comprises: an electric arc furnace body and a horizontal scrap steel conveying and preheating device, wherein:

[0007] The electric arc furnace body is arranged at the outlet of the horizontal scrap steel conveying and preheating device, and is used to receive scrap steel from the horizontal scrap steel conveying and preheating device, and smelt the received scrap steel to obtain molten steel and slag;

[0008] The horizontal scrap steel conveying and preheating device is used to preheat the scrap steel received from the scrap steel feeding device and convey the preheated scrap steel to the electric arc furnace body, wherein the horizontal scrap steel conveying and preheating device comprises: a scrap steel conveying device, a horizontal connecting trolley, a horizontal connecting trolley hood, a scrap steel preheating channel hood, a dynamic sealing device, a gas collecting main pipe, a primary flue and a settling chamber;

[0009] The scrap steel conveying device is used to receive the scrap steel from the scrap steel feeding device and transport the received scrap steel to the electric arc furnace body through the horizontal connecting trolley;

[0010] The horizontal connecting trolley smoke hood is arranged above the horizontal connecting trolley, and is used to provide a channel for the outflow of flue gas from the electric arc furnace body and the transportation of the scrap steel, and to provide a closed environment for the process of preheating the scrap steel with high-temperature flue gas;

[0011] The dynamic sealing device is connected to the fume hood of the scrap steel preheating channel, and is used to provide a channel for the transportation of the scrap steel, limit the amount of cold air entering the channel, and prevent the smoke in the channel from escaping;

[0012] The scrap steel preheating channel hood is respectively connected to the horizontal connecting trolley hood and the dynamic sealing device, and is located between the horizontal connecting trolley hood and the dynamic sealing device. The bottom is connected to the gas collecting main pipe through multiple exhaust bellows and multiple gas collecting branch pipes in a one-to-one correspondence;

[0013] The gas collecting main pipe is connected to the multiple gas collecting branch pipes and the primary flue respectively, and is used to collect and mix the flue gas from the multiple gas collecting branch pipes;

[0014] The primary flue is arranged between the gas collecting main pipe and the settling chamber, and is used to guide the flue gas collected and mixed in the gas collecting main pipe to the settling chamber; and

[0015] The settling chamber is connected to the primary flue and is used to separate and settle dust particles that meet predetermined size conditions in the collected and mixed flue gases.

[0016] Preferably, in the steelmaking electric arc furnace, the horizontal scrap steel conveying and preheating device further comprises:

[0017] The scrap steel feeding device is used to convey the scrap steel to the scrap steel conveying device to obtain a scrap steel material layer;

[0018] A plurality of scrap steel conveying device driving wheels, used for driving the scrap steel conveying device to convey the scrap steel to the horizontal connection trolley hood;

[0019] The plurality of exhaust bellows are located at the bottom of the fume hood of the scrap steel preheating channel and are used to suck the fume in the fume hood of the scrap steel preheating channel to penetrate the scrap steel material layer;

[0020] The multiple gas collecting branch pipes and the exhaust bellows are connected one by one and are connected to the gas collecting main pipe and are used to transport the flue gas to the gas collecting main pipe.

[0021] Preferably, in the steelmaking electric arc furnace, the horizontal connecting trolley adopts a slip-stick operation mode to horizontally deliver the scrap steel into the electric arc furnace body, and when the furnace body of the electric arc furnace body needs to be tilted for slag or steel, the trolley is completely withdrawn to the outer side of the upper furnace shell of the electric arc furnace body;

[0022] The horizontal connection trolley hood adopts a water-cooling structure;

[0023] The end of the horizontal connection trolley smoke hood near the furnace is provided with a hydraulic movable hood; and / or,

[0024] The horizontal connection trolley smoke hood is provided with a tilting hydraulic structure.

[0025] Preferably, in the steelmaking electric arc furnace, the scrap steel preheating channel hood adopts a refractory-lined structure, and a plurality of groups of burners are arranged on the scrap steel preheating channel hood.

[0026] Preferably, in the steel-making electric arc furnace, the dynamic sealing device is connected to the exhaust duct, and an exhaust fan is provided on the exhaust duct, the exhaust fan is linked with the main fan of the primary flue gas of the electric arc furnace body, and the end of the exhaust duct is merged into the secondary flue gas pipeline.

[0027] Preferably, in the steelmaking electric arc furnace, the scrap steel feeding device adopts a magnetic disk crane or a steel grabber structure;

[0028] The scrap steel conveying device is composed of a trough body and grate bars, wherein the trough body and the grate bars are both made of a predetermined high-temperature resistant metal material, and a plurality of trough bodies are connected in series front and back to form the scrap steel conveying device.

[0029] On the other hand, a steelmaking method of an electric arc furnace, wherein the steelmaking electric arc furnace is applicable to any one of the above steelmaking electric arc furnaces, the steelmaking method comprising:

[0030] Step S1, preheating the scrap steel through a horizontal scrap steel conveying and preheating device and conveying it to the electric arc furnace body:

[0031] Step S2, smelting the scrap steel through the electric arc furnace body to obtain molten steel and slag.

[0032] Preferably, the steelmaking method further comprises:

[0033] During the first furnace smelting, the furnace cover of the electric arc furnace body is opened, and the scrap steel is added into the electric arc furnace body through the furnace cover by using a crane and a basket loaded with scrap steel of a specified weight, and then the furnace cover is closed;

[0034] Among them, before smelting the first furnace, the hydraulic movable hood horizontally connected to the front end of the trolley smoke hood retreats to a position where the furnace cover can be opened; when closing the furnace cover, the hydraulic movable hood advances to a predetermined position; during the smelting process, the hydraulic movable hood adjusts the gap between it and the upper furnace shell of the electric arc furnace body according to the flue gas composition during the smelting process.

[0035] Preferably, in the steelmaking method, step S1 comprises:

[0036] The scrap steel layer and the scrap steel conveying device remain relatively stationary, and the moving speed of the scrap steel conveying device matches the melting process of the scrap steel pile in the furnace, wherein the scrap steel layer is arranged in layers according to the characteristics of the scrap steel, and the characteristics include: the shape of the scrap steel, the size of the scrap steel and / or the weight of the scrap steel;

[0037] When the scrap steel layer rolls and falls to the horizontal connecting trolley at the outlet of the scrap steel conveying device, the scrap steel with a relatively low temperature is turned to the surface, and then falls into the molten pool of the electric arc furnace body from the horizontal connecting trolley, and performs convection heat exchange with the molten steel with a relatively high temperature on the surface of the molten pool; during the smelting process, the distribution of the primary flue gas outflow flow rate of each exhaust bellows is adjusted, wherein the outflow flow rate allocated to the exhaust bellows near the furnace side is selected to be smaller than the outflow flow rate allocated to the exhaust bellows far from the furnace side, so that the temperature of the preheated flue gas is greater than or equal to the lower limit of the temperature for sufficient decomposition of dioxins.

[0038] Preferably, in the steelmaking method, step S2 comprises:

[0039] When the rising height of the molten pool in the electric arc furnace body reaches a predetermined value and the temperature of the molten pool meets the requirements of the smelting process, the horizontal connecting trolley continuously feeds the preheated scrap steel into the molten pool; the scrap steel continuously entering is further heated and melted in the molten pool, and the scrap steel melting rate matches the arc input power and the scrap steel feeding rate, wherein the foam slag covers the molten pool throughout the melting process;

[0040] When the weight of the molten steel in the molten pool reaches the predetermined steel retention and tapping requirements, the temperature and composition of the molten steel are measured. When the temperature and composition of the molten steel meet the tapping requirements, the tapping process begins. When the tapping weight reaches a predetermined target value, tapping is stopped, and a predetermined proportion of molten steel and slag are retained in the molten pool.

[0041] The above technical solution has the following technical effects:

[0042] The technical solution of this embodiment uses an improved horizontal scrap steel conveying and preheating device to preheat the scrap steel and transport the scrap steel to the electric arc furnace for smelting, thereby achieving efficient preheating of the scrap steel before entering the electric arc furnace and reducing the energy demand of the electric arc furnace itself. At the same time, through the closed preheating environment and flue gas management system of the horizontal scrap steel conveying and preheating device, heat loss and flue gas leakage during the preheating process are effectively controlled, energy utilization is improved, and the process layout is more optimized. The flue gas generated during the preheating process is further treated by the settling chamber, achieving the technical effects of energy saving, consumption reduction, environmental protection and emission reduction.

[0043] In a further embodiment, efficient heat exchange is achieved by allowing high-temperature flue gas to penetrate the scrap steel layer; the suction air volume of the wind box is controlled by zoning, so that when the average temperature of the scrap steel near the furnace side is high, the air volume is allocated smaller, while when the average temperature of the scrap steel far from the furnace side is lower, a larger air volume is allocated, thus ensuring a high level of overall preheating efficiency, and by reasonably zoning the suction air volume, making it close to the lower limit of the temperature for full decomposition of dioxins, avoiding additional consumption of fuel to heat the "overcooled" flue gas that has been preheated, thereby maximizing the use of the heat of the flue gas; when the scrap steel layer rolls and falls to the horizontal connecting trolley at the end of the conveying device, the scrap steel with a lower temperature flips to the surface, which is conducive to convective heat exchange with the steel liquid with a higher temperature on the surface of the molten pool, thereby improving the melting efficiency of the scrap steel; and, since the molten pool space occupied by the continuously added scrap steel is not too much, there is no need to specially design the furnace and molten pool of the electric arc furnace, which means that the traditional non-preheating ultra-high power electric arc furnace only needs a small amount of modification to achieve the preheating function.

[0044] In a further embodiment, by using a magnetic disk crane or a steel grabber, etc., scrap steel is continuously provided to the conveying device to ensure the continuous supply of the scrap steel layer, so that the scrap steel layer can always be maintained at an ideal thickness; and the feeding rate of the scrap steel feeding device needs to match the rate at which the scrap steel is fed into the electric arc furnace body, which helps to maintain the height of the scrap steel layer in the scrap steel conveying device within a predetermined range, wherein the bulk density of the incoming scrap steel determines the feeding frequency, which in turn affects the height of the scrap steel layer. This embodiment can effectively maintain the preset height of the scrap steel layer on the scrap steel conveying device, ensure that the scrap steel can be fully preheated before entering the electric arc furnace body, improve the melting efficiency of the scrap steel, and at the same time reduce energy consumption and improve production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 A schematic structural diagram of a steelmaking electric arc furnace according to an embodiment of the present invention;

[0046] Figure 2 It is a structural schematic diagram of a scrap steel conveying device in a steelmaking electric arc furnace according to an embodiment of the present invention;

[0047] Among them, 1 is the electric arc furnace body, 2 is the horizontal connecting trolley, 3 is the smoke hood of the horizontal connecting trolley, 4 is the smoke hood of the scrap steel preheating channel, 5 is the dynamic sealing device, 6 is the scrap steel feeding device, 7 is the scrap steel material layer, 8 is the scrap steel conveying device, 9 is the driving wheel of the scrap steel conveying device, 10 is the exhaust bellows, 11 is the gas collecting branch pipe, 12 is the gas collecting main pipe, 13 is the primary flue, 14 is the settling chamber; a is the trough body, b is the grate bars, and c is the gap. DETAILED DESCRIPTION

[0048] To further illustrate the various embodiments, the present invention provides drawings. These drawings are part of the disclosure of the present invention, which are mainly used to illustrate the embodiments and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these contents, a person of ordinary skill in the art should be able to understand other possible implementations and advantages of the present invention. The components in the figures are not drawn to scale, and similar component symbols are generally used to represent similar components.

[0049] The present invention will now be further described with reference to the accompanying drawings and specific implementation methods.

[0050] Embodiment 1:

[0051] In order to achieve the dual effects of reducing smelting energy consumption and improving productivity, this embodiment provides a steelmaking electric arc furnace. Figure 1 FIG. 1 is a schematic diagram of the structure of a steelmaking electric arc furnace according to an embodiment of the present invention. Figure 1 As shown, the steelmaking electric arc furnace comprises: an electric arc furnace body 1 and a horizontal scrap steel conveying and preheating device, wherein:

[0052] The electric arc furnace body 1 is arranged at the outlet of the horizontal scrap steel conveying and preheating device, and is used to receive scrap steel from the horizontal scrap steel conveying and preheating device, and smelt the received scrap steel to obtain molten steel and slag;

[0053] The horizontal scrap steel conveying and preheating device is used to preheat the scrap steel received from the scrap steel feeding device and convey the preheated scrap steel to the electric arc furnace body 1, wherein the horizontal scrap steel conveying and preheating device comprises: a scrap steel conveying device 8, a horizontal connecting trolley 2, a horizontal connecting trolley hood 3, a scrap steel preheating channel hood 4, a dynamic sealing device 5, a gas collecting main pipe 12, a primary flue 13 and a settling chamber 14;

[0054] The scrap steel conveying device 8 is used to receive the scrap steel from the scrap steel feeding device 6 and transport the received scrap steel to the electric arc furnace body 1 through the horizontal connection trolley 2;

[0055] The horizontal connecting trolley smoke hood 3 is arranged above the horizontal connecting trolley 2, and is used to provide a channel for the outflow of flue gas and scrap steel from the electric arc furnace body 1, and to provide a closed environment for the process of preheating the scrap steel with high-temperature flue gas;

[0056] The dynamic sealing device 5 is connected to the fume hood 4 of the scrap preheating channel, and is used to provide a channel for the transportation of scrap steel, limit the amount of cold air entering the channel, and prevent the smoke in the channel from escaping;

[0057] The scrap steel preheating channel hood 4 is connected to the horizontal connecting trolley hood 3 and the dynamic sealing device 5 respectively, and is located between the horizontal connecting trolley hood 3 and the dynamic sealing device 5. The bottom is connected to the gas collecting main pipe 12 through multiple exhaust bellows 10 and multiple gas collecting branch pipes 11 in a one-to-one correspondence;

[0058] The gas collecting main pipe 12 is connected to the multiple gas collecting branch pipes 11 and the primary flue 13 respectively, and is used to collect and mix the flue gases from the multiple gas collecting branch pipes 11;

[0059] The primary flue 13 is disposed between the gas collecting main pipe 12 and the settling chamber 14 and is used to guide the flue gas collected and mixed in the gas collecting main pipe 13 to the settling chamber 14; and

[0060] The settling chamber 14 is connected to the primary flue 13 and is used to separate and settle dust particles that meet predetermined size conditions in the collected and mixed flue gases.

[0061] Preferably, the electric arc furnace body 1 includes: an electric arc furnace molten pool, which is composed of molten steel and slag and is the place where scrap steel is melted and steelmaking reactions are carried out; an electric arc furnace hearth, which is built of refractory materials and specifies the shape and size of the molten pool, such as the diameter and depth of the molten pool in the main melting zone; an upper shell of the electric arc furnace, which adopts a water-cooling structure to provide an opening channel for the high-temperature flue gas generated in the molten pool steelmaking reaction process to preheat the scrap steel and for the preheated scrap steel to enter the furnace, and also provides an opening channel for the installation of furnace wall oxygen guns and carbon guns; an electric arc furnace cover, which adopts a water-cooling structure to maintain the atmosphere and temperature in the furnace within a suitable range during the smelting process, and also provides a channel for the up and down movement of the electrode, the discharge of the flue gas in the furnace, and the loading of bulk materials, thereby meeting the needs of the smelting process and providing a good workshop production environment; a graphite electrode, which is used to introduce electrical energy into the electric arc furnace and convert it into arc heat of the arc to heat the molten pool and melt the scrap steel.

[0062] Preferably, the horizontal connecting trolley 2 adopts a slip-stick operation mode to transport the scrap steel into the electric arc furnace through horizontal displacement. At the same time, when the electric arc furnace body needs to be tilted to discharge slag / steel, it can be completely withdrawn to the outside of the upper furnace shell to avoid collision with the tilted upper furnace shell.

[0063] Preferably, the horizontal connecting trolley smoke hood 3 adopts a water-cooling structure to provide a channel for the outflow of flue gas and scrap steel from the arc furnace body, and also provide a closed environment for the high-temperature flue gas preheating scrap steel process. In a specific embodiment, the end of the horizontal connecting trolley smoke hood 3 near the furnace is provided with a hydraulic movable hood to make room for the rotation of the arc furnace cover. At the same time, the horizontal connecting trolley smoke hood 3 is also provided with a tilting hydraulic mechanism, which can tilt the horizontal connecting trolley smoke hood 3 as a whole, so as to facilitate the maintenance of the inner side of the horizontal connecting trolley smoke hood 3 and the horizontal connecting trolley 2.

[0064] Preferably, the scrap steel preheating channel hood 4 adopts a refractory-lined structure to provide a channel for the outflow of flue gas from the arc furnace body and the transportation of scrap steel, and also provide a closed environment for the high-temperature flue gas preheating scrap steel process. In a specific implementation, a plurality of groups of burners are arranged on the scrap steel preheating channel hood 4 to enhance the scrap steel preheating effect.

[0065] Preferably, the dynamic sealing device 5 is located in the combined area of ​​scrap steel feeding and preheating, providing a channel for scrap steel to enter the preheating area. When the pressure in the scrap steel preheating channel 4 fluctuates, on the one hand, it prevents excessive cold air from entering the preheating area, thereby weakening the preheating effect, and on the other hand, it prevents the high-temperature and high-dust flue gas in the preheating channel from escaping into the factory space, thereby deteriorating the operation and external environment. In a specific implementation, the dynamic sealing device 5 is connected to an exhaust duct, and an exhaust fan is provided on the exhaust duct. The exhaust fan is linked to the main fan of the primary flue gas of the electric arc furnace, and the end of the exhaust duct is merged into the secondary flue gas pipeline of the factory.

[0066] Preferably, the scrap steel feeding device 6 adopts a structure such as a magnetic disk crane or a steel grabber to continuously provide scrap steel to the scrap steel conveying device 8 for conveying scrap steel.

[0067] Preferably, the scrap steel layer 6 composed of scrap steel loaded onto the scrap steel conveying device 8 through the scrap steel feeding device 6 can be optimally arranged in layers according to the characteristics of the incoming scrap steel (such as shape, size, weight, etc.) to achieve optimization of the preheating effect and the smelting process.

[0068] Preferably, the scrap steel conveying device 8 receives the scrap steel provided by the scrap steel feeding device 6, carries the scrap steel to move horizontally, and continuously conveys the scrap steel to the horizontal connecting trolley 2. Its structure is as follows: Figure 2 As shown, it is composed of a trough body a, grate bars b and gaps c. The trough body a and the grate bars b are both made of high-temperature resistant metal materials. Several trough bodies a are connected in series to form a scrap steel conveying device 8. The gaps c between the grate bars b facilitate the passage of smoke that penetrates the scrap steel layer 6 without causing the scrap steel to fall.

[0069] Preferably, the scrap steel conveying device 8 is provided with a plurality of scrap steel conveying device driving wheels 9, which are used to drive the scrap steel conveying device 8 to continuously supply scrap steel to the horizontal connecting trolley 2, and at the same time circulate the conveying trough body a after unloading the scrap steel back to the loading area.

[0070] Preferably, the scrap steel conveying device 8 can adopt a trolley type or a chain plate type structure. The horizontal travel speed of the scrap steel is faster than that of the traditional horizontal feeding conveyor, so a thinner material layer thickness can be used, thereby significantly improving the preheating effect; and the horizontal conveying form can be compatible with the optimized horizontal feeding workshop process layout to the greatest extent;

[0071] Preferably, a plurality of exhaust bellows 10 are arranged below the scrap steel preheating channel hood 4, and the plurality of exhaust bellows 10 are used to draw the smoke in the scrap steel preheating channel hood 4 to penetrate the scrap steel material layer 6, thereby improving the heat exchange effect between the two.

[0072] Preferably, a plurality of gas collecting branch pipes 11 are used to connect the exhaust bellows 10 with the gas collecting main pipe 12 , and to transport the flue gas from each exhaust bellows 10 branch that has penetrated the scrap steel layer 6 and has been cooled to the gas collecting main pipe 12 .

[0073] Preferably, the gas collecting main pipe 12 is used to connect the gas collecting branch pipe 11 with the primary flue 13 to collect and mix the branch flue gases of the gas collecting branch pipe 11.

[0074] Preferably, the primary flue 13 is used to connect the gas collecting main pipe 12 with the settling chamber 14 , and guide the primary flue gas in the gas collecting main pipe 12 to the settling chamber 14 .

[0075] Preferably, the front end of the settling chamber 14 is connected to the primary flue 13, and the rear end is connected to the dust collector pipeline, which is used to separate and settle the coarse dust particles in the flue gas, reduce the burden on the rear pipeline and the dust collector, and burn the unburned components in the flue gas here.

[0076] Preferably, the steelmaking electric arc furnace is also provided with a transformer room, a high voltage room and a hydraulic room.

[0077] Embodiment 2:

[0078] The present invention also provides a steelmaking method using the steelmaking electric arc furnace as described above. The method of this embodiment comprises:

[0079] Step S1, preheating the scrap steel through a horizontal scrap steel conveying and preheating device and conveying it to the electric arc furnace body:

[0080] Step S2, smelting the scrap steel through an electric arc furnace body to obtain molten steel and slag.

[0081] In a specific implementation, before the first furnace is smelted, the hydraulic movable hood horizontally connected to the front end of the trolley hood retreats to the furnace cover opening position to make room for the arc furnace body to open the furnace cover; then the furnace cover of the arc furnace body is opened, and a basket containing scrap steel of a specified weight is moved to the top of the arc furnace body by a crane; after the basket is lowered to a certain height, the bottom of the basket is opened to allow the scrap steel to fall into the arc furnace; after the basket is lifted and removed, the furnace cover is closed, and the hydraulic movable hood horizontally connected to the front end of the trolley hood advances to the smelting position, and the gap between the hydraulic movable hood and the upper furnace shell is adjusted according to the smoke components in the smelting process, so as to control the intake of sufficient air for the secondary combustion of the combustible components in the smoke, without inhaling excessive air, thereby weakening the preheating effect;

[0082] Subsequently, the scrap steel feeding device supplies scrap steel to the scrap steel conveying device located in the loading area, and the scrap steel conveying device carries the scrap steel layer added thereto and continuously moves horizontally toward the electric arc furnace body, the scrap steel layer and the scrap steel conveying device remain relatively still, and the moving speed of the scrap steel conveying device matches the melting process of the scrap steel pile in the furnace to achieve an optimized scrap steel preheating effect; preferably, before the preheated scrap steel falls into the molten pool, the depth and temperature of the molten pool in the furnace have reached the expected level required by the smelting process;

[0083] At the same time, power is supplied to the graphite electrode of the electric arc furnace body, and after the graphite electrode drops to a certain height, it contacts the scrap steel pile in the electric arc furnace. After the arc is started, the graphite electrode continuously moves downward to penetrate the well. After penetrating the well to a certain depth, the power supply is increased to start the main melting period. Preferably, during the smelting process, the distribution of the outflow flow of the primary flue gas of each exhaust bellows is adjusted to achieve the purpose of controlling the temperature of the mixed flue gas to above 900°C, so as to fully decompose the dioxins in the subsequent primary flue gas.

[0084] During the main melting period, when a clear molten pool appears in the furnace, the oxygen lance and carbon lance of the furnace wall are opened, and an appropriate amount of slag-making flux is added according to the melting process, and oxygen and carbon are sprayed into the molten pool to form foamed slag; preferably, when the scrap steel above the molten pool liquid level is nearly completely melted, the arc is well covered by the foamed slag, thereby maximizing the recovery of arc heat and protecting the refractory materials and water-cooling components of the furnace wall and the water-cooling components of the furnace cover from thermal erosion by the arc;

[0085] As the scrap steel is melted, the liquid level of the molten pool in the furnace rises continuously. When the rising height reaches a certain value and the temperature of the molten pool meets the requirements of the smelting process, the horizontal connecting trolley continuously feeds the preheated scrap steel into the molten pool of the electric arc furnace. The scrap steel continuously entering is further heated and melted in the molten pool. The melting rate of the scrap steel matches the input power of the arc and the feeding rate of the scrap steel. The foam slag covers the molten pool throughout the melting process, achieving good refining of the molten steel and automatic outflow of the molten slag.

[0086] When the weight of the molten steel in the molten pool reaches the requirements for steel retention and tapping, the temperature and composition of the molten steel are measured; when the temperature and composition meet the tapping requirements, the tapping process begins; when the tapping weight reaches the target value, tapping is stopped, and a certain proportion of molten steel and slag are left in the molten pool to facilitate the start of the next smelting cycle;

[0087] In the subsequent smelting cycle, there is no need to add scrap steel into the electric arc furnace by opening the furnace cover. All scrap steel is preheated by the scrap steel conveying device before entering the electric arc furnace. Preferably, the loading rate of the scrap steel feeding device matches the scrap steel feeding rate, and the scrap steel layer is maintained at a certain preset height to achieve appropriate resistance for flue gas in the conveying device to penetrate the scrap steel layer and a good scrap preheating effect. The loading frequency of the scrap steel feeding device depends on the bulk density of the incoming scrap steel.

[0088] Preferably, the suction air volume of the exhaust bellows is controlled in zones. If the average temperature of the scrap steel near the furnace is high, the suction air volume allocation is relatively small, while if the average temperature of the scrap steel far from the furnace is low, the suction air volume allocation is relatively large, so that the overall preheating efficiency is maintained at a high level. By controlling the suction air volume of the exhaust bellows in zones, the temperature of the flue gas after preheating is just near the lower limit value for the full decomposition of dioxins, so that there is no need to consume additional fuel for heating the supercooled flue gas after the scrap steel is preheated, thereby achieving the ultimate utilization of the flue gas heat.

[0089] The above-mentioned steelmaking method of this embodiment penetrates the scrap steel layer through high-temperature flue gas, and the heat exchange is sufficient and the preheating temperature is high. According to the calculated average temperature, it is expected to reach 300-500°C, and the expected temperature varies depending on the scrap steel incoming conditions; and, when the scrap steel layer rolls and falls to the horizontal connecting trolley at the outlet of the scrap steel conveying device, the scrap steel with a relatively low temperature is turned to the surface, and then falls into the molten pool of the electric arc furnace body from the horizontal connecting trolley, and performs convection heat exchange with the relatively high temperature of the molten steel on the surface of the molten pool, thereby improving the scrap steel melting efficiency; further, since the molten pool space occupied by the continuously added scrap steel is not too much, there is no need to design a special electric arc furnace furnace and molten pool. The traditional non-preheating ultra-high power electric arc furnace can be transformed into the electric arc furnace with a slight modification, which can realize the reuse and transformation of existing equipment.

[0090] Although the present invention has been specifically shown and described in conjunction with the preferred embodiments, it should be understood by those skilled in the art that various changes may be made to the present invention in form and details without departing from the spirit and scope of the present invention as defined by the appended claims, all of which are within the scope of protection of the present invention.

Claims

1. A steelmaking electric arc furnace, characterized in that: include: Electric arc furnace body and horizontal scrap conveying and preheating device, including: The electric arc furnace body is arranged at the outlet of the horizontal scrap steel conveying and preheating device, and is used to receive scrap steel from the horizontal scrap steel conveying and preheating device, and smelt the received scrap steel to obtain molten steel and slag; The horizontal scrap steel conveying and preheating device is used to preheat the scrap steel received from the scrap steel feeding device and convey the preheated scrap steel to the electric arc furnace body, wherein the horizontal scrap steel conveying and preheating device comprises: a scrap steel conveying device, a horizontal connecting trolley, a horizontal connecting trolley hood, a scrap steel preheating channel hood, a dynamic sealing device, a gas collecting main pipe, a primary flue and a settling chamber; The scrap steel conveying device is used to receive the scrap steel from the scrap steel feeding device and transport the received scrap steel to the electric arc furnace body through the horizontal connecting trolley; The horizontal connecting trolley smoke hood is arranged above the horizontal connecting trolley, and is used to provide a channel for the outflow of flue gas from the electric arc furnace body and the transportation of the scrap steel, and to provide a closed environment for the process of preheating the scrap steel with high-temperature flue gas; The dynamic sealing device is connected to the fume hood of the scrap steel preheating channel, and is used to provide a channel for the transportation of the scrap steel, limit the amount of cold air entering the channel, and prevent the smoke in the channel from escaping; The scrap steel preheating channel hood is respectively connected to the horizontal connecting trolley hood and the dynamic sealing device, and is located between the horizontal connecting trolley hood and the dynamic sealing device. The bottom is connected to the gas collecting main pipe through multiple exhaust bellows and multiple gas collecting branch pipes in a one-to-one correspondence; The gas collecting main pipe is connected to the multiple gas collecting branch pipes and the primary flue respectively, and is used to collect and mix the flue gas from the multiple gas collecting branch pipes; The primary flue is arranged between the gas collecting main pipe and the settling chamber, and is used to guide the flue gas collected and mixed in the gas collecting main pipe to the settling chamber; and The settling chamber is connected to the primary flue and is used to separate and settle dust particles that meet predetermined size conditions in the collected and mixed flue gases.

2. The steelmaking electric arc furnace according to claim 1, characterized in that: The horizontal scrap steel conveying and preheating device also includes: The scrap steel feeding device is used to convey the scrap steel to the scrap steel conveying device to obtain a scrap steel material layer; A plurality of scrap steel conveying device driving wheels, used for driving the scrap steel conveying device to convey the scrap steel to the horizontal connection trolley hood; The plurality of exhaust bellows are located at the bottom of the fume hood of the scrap steel preheating channel and are used to suck the fume in the fume hood of the scrap steel preheating channel to penetrate the scrap steel material layer; The multiple gas collecting branch pipes and the exhaust bellows are connected one by one and are connected to the gas collecting main pipe and are used to transport the flue gas to the gas collecting main pipe.

3. The steelmaking electric arc furnace according to claim 1, characterized in that: The horizontal connecting trolley adopts a sliding and sticking operation mode to horizontally deliver the scrap steel into the electric arc furnace body, and when the furnace body of the electric arc furnace body needs to be tilted to discharge slag or steel, it is completely withdrawn to the outer side of the upper furnace shell of the electric arc furnace body; The horizontal connection trolley hood adopts a water-cooling structure; The end of the horizontal connection trolley smoke hood near the furnace is provided with a hydraulic movable hood; and / or, The horizontal connection trolley smoke hood is provided with a tilting hydraulic structure.

4. The steelmaking electric arc furnace according to claim 1, characterized in that: The scrap steel preheating channel smoke hood adopts a refractory material lined structure, and a plurality of groups of burners are arranged on the scrap steel preheating channel smoke hood.

5. The steelmaking electric arc furnace according to claim 1, characterized in that: The dynamic sealing device is connected to the exhaust duct, and an exhaust fan is arranged on the exhaust duct. The exhaust fan is linked with the main fan of the primary flue gas of the electric arc furnace body, and the end of the exhaust duct is merged into the secondary flue gas pipeline.

6. The steelmaking electric arc furnace according to claim 2, characterized in that: The scrap steel feeding device adopts the structural form of a magnetic disk crane or a steel grabber; The scrap steel conveying device is composed of a trough body and grate bars, wherein the trough body and the grate bars are both made of a predetermined high-temperature resistant metal material, and a plurality of trough bodies are connected in series front and back to form the scrap steel conveying device.

7. A steelmaking method using an electric arc furnace, characterized in that: Applicable to the steelmaking electric arc furnace described in any one of claims 1 to 6, the steelmaking method comprising: Step S1, preheating the scrap steel through a horizontal scrap steel conveying and preheating device and conveying it to the electric arc furnace body: Step S2, smelting the scrap steel through the electric arc furnace body to obtain molten steel and slag.

8. The steelmaking method according to claim 7, characterized in that Also includes: During the first furnace smelting, the furnace cover of the electric arc furnace body is opened, and the scrap steel is added into the electric arc furnace body through the furnace cover by using a crane and a basket loaded with scrap steel of a specified weight, and then the furnace cover is closed; Among them, before smelting the first furnace, the hydraulic movable hood horizontally connected to the front end of the trolley smoke hood retreats to a position where the furnace cover can be opened; when closing the furnace cover, the hydraulic movable hood advances to a predetermined position; during the smelting process, the hydraulic movable hood adjusts the gap between it and the upper furnace shell of the electric arc furnace body according to the flue gas composition during the smelting process.

9. The steelmaking method according to claim 7, characterized in that: Step S1 includes: The scrap steel layer and the scrap steel conveying device remain relatively stationary, and the moving speed of the scrap steel conveying device matches the melting process of the scrap steel pile in the furnace, wherein the scrap steel layer is arranged in layers according to the characteristics of the scrap steel, and the characteristics include: the shape of the scrap steel, the size of the scrap steel and / or the weight of the scrap steel; When the scrap steel layer rolls and falls to the horizontal connecting trolley at the outlet of the scrap steel conveying device, the scrap steel with a relatively low temperature is turned to the surface, and then falls into the molten pool of the electric arc furnace body from the horizontal connecting trolley, and performs convection heat exchange with the molten steel with a relatively high temperature on the surface of the molten pool; during the smelting process, the distribution of the primary flue gas outflow flow rate of each exhaust bellows is adjusted, wherein the outflow flow rate allocated to the exhaust bellows near the furnace side is selected to be smaller than the outflow flow rate allocated to the exhaust bellows far from the furnace side, so that the temperature of the preheated flue gas is greater than or equal to the lower limit of the temperature for sufficient decomposition of dioxins.

10. The steelmaking method according to claim 7, characterized in that Step S2 includes: When the rising height of the molten pool in the electric arc furnace body reaches a predetermined value and the temperature of the molten pool meets the requirements of the smelting process, the horizontal connecting trolley continuously feeds the preheated scrap steel into the molten pool; the scrap steel continuously entering is further heated and melted in the molten pool, and the scrap steel melting rate matches the arc input power and the scrap steel feeding rate, wherein the foam slag covers the molten pool throughout the melting process; When the weight of the molten steel in the molten pool reaches the predetermined steel retention and tapping requirements, the temperature and composition of the molten steel are measured. When the temperature and composition of the molten steel meet the tapping requirements, the tapping process begins. When the tapping weight reaches a predetermined target value, tapping is stopped, and a predetermined proportion of molten steel and slag are retained in the molten pool.

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