Continuous shaft scrap steel preheating device and electric furnace steelmaking equipment

Abstract

The present invention relates to a continuous vertical shaft scrap steel preheating device and electric furnace steelmaking equipment. The device comprises a vertical shaft, a chute section, and a control unit. The vertical shaft is configured as a straight pipe, and the chute section is configured as a curved pipe. The first end of the vertical shaft is connected to the first end of the chute section, and the vertical shaft and the chute section are configured with equal cross-sections. The second end of the vertical shaft is connected to the first end of a continuous feeding structure, and the first end of the continuous feeding structure is configured to be closable or openable, and the second end of the continuous feeding structure is configured to be closable or openable. The second end of the chute section is configured to connect to a discharge port, and a smoke extraction port is configured to connect to the side wall of the vertical shaft below the continuous feeding structure. The control unit can control the closure or opening of the continuous feeding structure. The present invention eliminates the need for a finger valve, and there is no risk of explosions caused by leakage of the finger valve. The vertical shaft and the chute section are configured with equal cross-sections, ensuring that there is no risk of scrap steel jamming throughout the entire process. The continuous feeding structure ensures sealed feeding throughout the entire process, making the process safe and reliable.

Description

Technical Field

[0001] The present invention relates to the technical field of electric furnace steelmaking, and in particular to a continuous vertical shaft scrap steel preheating device and electric furnace steelmaking equipment. Background Art

[0002] Electric furnace steelmaking is a steelmaking process that primarily uses scrap steel as raw material, eliminating the need for an ironmaking system. It's also known as short-process steelmaking technology. Currently, compared to the long blast furnace and converter process, the short-process EAF steelmaking process emits approximately 60% fewer pollutants, making it more environmentally friendly. However, the production costs of EAF steelmaking are higher than those of converters, weakening the competitiveness of EAF steelmaking technology and significantly hindering the rapid expansion of EAF steelmaking. Scrap preheating electric furnaces, however, directly utilize the high-temperature flue gases generated during the smelting process to preheat the scrap steel. This can reduce electricity consumption by 20 to 100 kWh per ton of steel, significantly reducing energy costs and making it a hot technology for the development of EAF steelmaking processes.

[0003] Currently, Consteel electric furnaces are widely used due to their relatively low heat load on the charging device, low equipment failure rate, and no risk of water leakage. However, this type of furnace charges scrap into the furnace via a horizontal vibrating device. The horizontal vibrating device consists of a charging section (uncovered) and a preheating section (covered). In the charging section, the scrap is attracted by the magnetic disk of the scrap overhead crane and loaded onto the vibrating device. Driven by the horizontal vibration, the scrap then enters the preheating section. In the preheating section, gravity forces the scrap to lie flat on the vibrating device (at the bottom of the preheating section), while the high-temperature flue gas passes through the top of the preheating section. This results in inefficient convective heat exchange between the high-temperature scrap and the scrap, resulting in poor preheating performance. With an average preheating temperature of 200°C, this saves 20 to 30 kWh / ton of electricity, a modest energy saving. For a 100% scrap feedstock, the electricity consumption is 350 kWh / ton.

[0004] In the prior art, there is an environmentally friendly device that uses exhaust gas from an electric arc furnace to preheat metal materials. The key is to set up a multi-layer hydraulic cylinder-driven finger valve structure inside the vertical shaft to hold multiple layers of scrap steel for vertical multi-layer preheating. By controlling the finger valves to open in layers, the preheated scrap steel is added in layers and batches to the horizontal vibrating feeding trough at the bottom of the vertical shaft. The horizontal vibrating feeding trough continuously adds small batches of preheated scrap steel in the vertical shaft to the electric furnace molten pool. At the same time, a receiving hopper is provided at the top of the vertical shaft, and a closed door is provided at the bottom of the receiving hopper. A second closed door is provided between the first closed door and the first layer of finger valve structure in the vertical shaft, and a dust removal port is provided on the side wall between the second closed door and the first layer of finger valve structure. The problems with this technology are:

[0005] 1) The existing technology uses a vertical shaft structure with multiple layers of finger valves. When feeding the horizontal feeding trough from the vertical shaft, the finger valves on the lower layer must be opened and then closed before the finger valves on the upper layer can be opened. This results in long opening and closing times, and the operational control logic is cumbersome and complex, which reduces production efficiency. Furthermore, the finger valves in this technology are driven by hydraulic cylinders to rotate downward around a rotating axis within the shaft. This requires that the highest point of the scrap after it falls cannot hinder the closing of the finger valves. This is difficult to control in actual operation, and there is a risk that the finger valves will not close after opening.

[0006] 2) The existing equipment has a complex structure, high failure rate, high maintenance, high probability of water leakage from multi-layer fingers, and low safety;

[0007] 3) Once the finger valve fails in the shaft and cannot be closed, the finger valve cannot be withdrawn from the shaft, making it easier to repair.

[0008] There is also a type of steelmaking equipment in the prior art that includes a shaft preheater and an electric arc furnace. The shaft preheater contains a shaft and an electromagnetic brake. The electromagnetic brake can generate a magnetic field to keep steelmaking raw materials entering the shaft within the shaft; the lower end of the shaft is connected to the corresponding inlet of the steelmaking raw materials. This steelmaking equipment uses the electromagnetic brake to capture the steelmaking raw materials to form a suspended material column. The material column formed by the steelmaking raw materials captured by the electromagnetic brake supports the steelmaking raw materials falling from above. The problems with this technology are:

[0009] 1) It is not possible to continuously add scrap steel into the furnace in small batches. Scrap steel can only be added to the furnace in large quantities after preheating for a period of time. When adding scrap steel, it is necessary to cut off the power and lift the electrode to prevent the electrode from being damaged by the scrap steel, which prolongs the power off time and reduces the production efficiency of the electric furnace.

[0010] 2) It is impossible to overcome the impact of subsequent scrap steel added on the scrap steel adsorbed on the electromagnetic disk. The scrap steel adsorbed on the electromagnetic disk will fall into the furnace in a disorderly manner when impacted by the subsequent scrap steel added.

[0011] Therefore, the inventors, relying on their many years of experience and practice in related industries, have proposed a continuous shaft scrap steel preheating device and electric furnace steelmaking equipment to overcome the defects of the prior art. Summary of the Invention

[0012] The purpose of the present invention is to provide a continuous vertical shaft scrap steel preheating device and electric furnace steelmaking equipment, which solves the problems existing in the prior art. The present invention no longer requires a finger valve, and there is no safety accident such as explosion caused by water leakage of the finger valve; the vertical shaft and the chute section are arranged with equal cross-sections to ensure that there is no risk of scrap steel getting stuck throughout the entire process; the continuous feeding structure ensures sealed feeding throughout the entire process, and the use process is safe and reliable.

[0013] The object of the present invention is achieved in this way. A continuous vertical shaft scrap steel preheating device includes a vertical shaft, a chute section and a control unit, the vertical shaft is arranged as a straight pipe, and the chute section is arranged as a curved pipe; the first end of the vertical shaft is connected to the first end of the chute section, and the vertical shaft and the chute section are arranged with equal cross-sections; the second end of the vertical shaft is connected to the first end of a continuous feeding structure, the first end of the continuous feeding structure is arranged to be closable or openable, and the second end of the continuous feeding structure is arranged to be closable or openable; the second end of the chute section can be connected to a discharge port, and the vertical shaft is located on the side wall below the continuous feeding structure and is connected to a smoke suction port; the control unit can control the closing or opening of the continuous feeding structure.

[0014] In a preferred embodiment of the present invention, an electromagnetic brake is provided on the slide pipe section, and the electromagnetic brake is electrically connected to the control unit.

[0015] In a preferred embodiment of the present invention, the continuous feeding structure includes a silo, a first end of the silo is connected to the shaft via a first valve, and the first valve is electrically connected to the control unit.

[0016] In a preferred embodiment of the present invention, the second end of the silo is connected to the feeding hopper via a second valve, and the second end of the silo constitutes the second end of the continuous feeding structure; the second valve is electrically connected to the control unit.

[0017] In a preferred embodiment of the present invention, the first valve is a gate valve.

[0018] In a preferred embodiment of the present invention, the second valve is a gate valve.

[0019] In a preferred embodiment of the present invention, the diameter of the feeding hopper is gradually reduced from top to bottom.

[0020] In a preferred embodiment of the present invention, the chute section is a 90° elbow.

[0021] In a preferred embodiment of the present invention, the second end of the chute section is connected to the discharge port through a straight pipe section of equal diameter.

[0022] The purpose of the present invention can also be achieved in this way. An electric furnace steelmaking equipment includes a charging device, a continuous vertical shaft scrap steel preheating device, an electric furnace charging and conveying structure and an electric furnace, wherein the continuous vertical shaft scrap steel preheating device is located above the electric furnace charging and conveying structure, the charging device is used to charge the continuous vertical shaft scrap steel preheating device, and the electric furnace charging and conveying structure is used to add the scrap steel preheated by the continuous vertical shaft scrap steel preheating device to the electric furnace.

[0023] As described above, the continuous shaft scrap steel preheating device and electric furnace steelmaking equipment of the present invention have the following beneficial effects:

[0024] In the present invention, a vertical shaft preheating method is adopted, which can maximize the use of flue gas waste heat and reduce power consumption during electric furnace production; finger valves are no longer provided in the continuous vertical shaft scrap steel preheating device, and there is no safety accident such as explosion caused by finger valve leakage; the vertical shaft and the chute section are arranged with equal cross-sections to ensure that there is no risk of scrap steel getting stuck throughout the process; the continuous feeding structure adopts a sealed bin + double-layer plug-in valve structure to ensure sealed feeding throughout the process, and the second end of the vertical shaft can be closed to ensure the effective sealing of the flue gas channel, avoiding the problem of flue gas overflow and mixing with wild wind during the preheating process; an electromagnetic brake is used on the chute section, and there is no directly force-bearing part, which improves the safety of system operation while ensuring that the addition of scrap steel is controllable. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The following drawings are intended only to illustrate and explain the present invention, and are not intended to limit the scope of the present invention.

[0026] Figure 1 : It is the front view of the continuous vertical shaft scrap steel preheating device of the present invention.

[0027] Figure 2 : It is a side view of the continuous vertical shaft scrap steel preheating device of the present invention.

[0028] Figure 3 : This is the state diagram after adding materials into the feeding hopper in step a.

[0029] Figure 4 : This is the state diagram after the feeding hopper adds materials to the silo in step a.

[0030] Figure 5 : This is the status diagram of the silo adding materials into the shaft in step b.

[0031] Figure 6 : Schematic diagram of the preheating working status in the shaft in step b.

[0032] Figure 7 : is the schematic diagram of electric furnace steelmaking equipment of the present invention.

[0033] In the picture:

[0034] 100. Continuous shaft scrap steel preheating device;

[0035] 1. Vertical shaft;

[0036] 2. Slide pipe section;

[0037] 3. Continuous feeding structure; 31. First valve; 32. Second valve; 33. Silo; 34. Feeding hopper;

[0038] 4. Feeding port;

[0039] 5. Smoke extraction port;

[0040] 6. Electromagnetic brake;

[0041] 7. Straight pipe sections of equal diameter;

[0042] 8. Scrap steel;

[0043] 200. Electric furnace steelmaking equipment; 201. Charging device; 202. Electric furnace charging and conveying structure; 203. Electric furnace. DETAILED DESCRIPTION

[0044] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described with reference to the accompanying drawings.

[0045] The specific embodiments of the present invention described herein are intended only to illustrate the present invention and are not to be construed as limiting the present invention in any way. In light of the present invention, a skilled person may conceive of any possible variations based on the present invention, all of which should be considered to fall within the scope of the present invention. It should be noted that when an element is referred to as being "disposed on" another element, it may be directly on the other element or there may be an intermediate element. When an element is considered to be "connected" to another element, it may be directly connected to the other element or there may be an intermediate element at the same time. The terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to mechanical or electrical connections, or to internal communication between two elements, and may be directly connected or indirectly connected through an intermediate medium. A person of ordinary skill in the art can understand the specific meanings of the above terms based on the specific circumstances. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only implementation methods.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are intended only to describe specific embodiments and are not intended to limit this application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0047] like Figure 1 、 Figure 2As shown, the present invention provides a continuous vertical shaft scrap preheating device 100, comprising a vertical shaft 1, a chute section 2 and a control unit, wherein the vertical shaft 1 is arranged as a straight pipe, and the chute section 2 is arranged as a curved pipe; the first end of the vertical shaft 1 is connected to the first end of the chute section 2, and the vertical shaft 1 and the chute section 2 are arranged with equal cross-sections; the second end of the vertical shaft 1 is connected to the first end of a continuous feeding structure 3, and the first end of the continuous feeding structure 3 is arranged to be closable or openable; the second end of the continuous feeding structure 3 is arranged to be closable or openable; the second end of the chute section 2 can be connected to a discharge port 4, and a smoke suction port 5 is arranged on the side wall of the vertical shaft 1 below the continuous feeding structure; the control unit can control the closing or opening of the continuous feeding structure.

[0048] The present invention provides a continuous vertical shaft scrap steel preheating device, in which the vertical shaft 1 and the chute section 2 are connected to form a scrap steel channel, and the vertical shaft 1 and the chute section 2 are arranged with equal cross-sections to ensure that the scrap steel 8 has no risk of being stuck throughout the entire process; the discharge port 4, the chute section 2, the vertical shaft 1 and the flue gas suction port 5 are connected to form a flue gas channel, and the high-temperature flue gas of the electric furnace (existing technology) enters the flue gas channel through the discharge port 4 to preheat the scrap steel. The continuous feeding structure 3 connected to the second end of the vertical shaft 1 can be closed, ensuring the effective sealing of the flue gas channel and avoiding the problem of flue gas overflow and mixing with wild wind during the preheating work.

[0049] The present invention provides a continuous vertical shaft scrap steel preheating device, which adopts a vertical shaft preheating method, can maximize the use of flue gas waste heat and reduce power consumption during electric furnace production; finger valves are no longer provided in the device, and there are no safety accidents such as explosions caused by water leakage of finger valves; the vertical shaft and the chute section are arranged with equal cross-sections to ensure that there is no risk of scrap steel being stuck throughout the entire process; the continuous feeding structure connected to the second end of the vertical shaft can be closed, ensuring the effective sealing of the flue gas channel, and avoiding the problems of flue gas overflowing and mixing with wild wind during the preheating operation.

[0050] Further, if Figure 1 、 Figure 2 As shown, an electromagnetic brake 6 is installed on the chute section 2 and is electrically connected to the control unit. During the preheating process, the electromagnetic brake 6 is adjusted according to the falling speed of the scrap steel 8 in the shaft, ensuring that the scrap steel 8 enters the loading chute (the charging structure of the electric furnace, a prior art) at a uniform speed from the discharge port 4. The use of the electromagnetic brake 6 on the chute section 2, without any directly loaded parts, ensures controlled scrap steel feeding and improves system operation safety.

[0051] The electromagnetic brake 6 is always in the energized state, keeping the scrap steel 8 in the shaft 1 from falling slowly. The continuous feeding structure 3 is opened to allow the scrap steel to fall into the shaft 1. As the scrap steel surface increases, the scrap steel's own gravity causes the scrap steel in the chute section 2 and subsequent pipelines to overcome the maximum static friction and start moving until it enters the electric furnace or the scrap steel transport device from the discharge port. During the process, the electromagnetic brake 6 is adjusted according to the speed of the scrap steel falling, so that the scrap steel can enter the electric furnace or the scrap steel transport device from the discharge port 4 at a uniform speed.

[0052] Further, if Figure 1 、 Figure 2 As shown, the continuous feeding structure 3 includes a silo 33, a first end of which is connected to the shaft 1 via a first valve 31. The first valve 31 is electrically connected to a control unit, which controls the closing or opening of the first valve 31. In this embodiment, the first valve is a gate valve.

[0053] Further, if Figure 1 、 Figure 2 As shown, the second end of the silo 33 is connected to the feeding hopper 34 via the second valve 32, and the second end of the silo 33 constitutes the second end of the continuous feeding structure; the second valve 32 is electrically connected to the control unit, and the control unit controls the closing or opening of the second valve 32. In this embodiment, the second valve is a gate valve.

[0054] When adding material to the silo 33, the first valve 31 is closed and the second valve 32 is opened. The scrap steel enters the silo 33 through the feeding hopper 34. The amount of scrap steel added each time cannot exceed the volume of the silo 33, and the second valve 32 must be effectively closed. Wait until the scrap steel has completely entered the silo 33 and close the second valve 32.

[0055] When adding material to the shaft 1 , the first valve 31 is opened, so that the scrap steel falls from the silo 33 into the shaft 1 of uniform cross-section.

[0056] After adding the material, the first valve 31 and the second valve 32 are closed, the silo 33 is in a closed state, the discharge port 4, the chute section 2, the vertical shaft 1 and the smoke suction port 5 are connected to form a smoke channel, and the smoke enters the smoke channel through the discharge port 4. The preheated smoke can only be extracted by the fan (existing technology) through the smoke suction port 5.

[0057] Through the aforementioned feeding operation, the continuous vertical shaft scrap steel preheating device 100 continuously transports scrap steel into the electric furnace or the scrap steel transport device (existing technology) and ensures that the added scrap steel is effectively preheated.

[0058] The continuous feeding structure 3 adopts the structure of sealed chamber + double-layer plug-in valve, which can effectively seal the smoke channel and basically prevent the smoke from overflowing and mixing with wild wind during the feeding process.

[0059] Furthermore, the diameter of the feeding hopper 34 is gradually reduced from top to bottom.

[0060] Further, if Figure 1 、 Figure 2 As shown, the chute section 2 is a 90° bend, which can effectively control the falling speed of the preheated scrap steel.

[0061] Further, if Figure 1 、 Figure 2 As shown, the second end of the chute section 2 is connected to the discharge port 4 via a straight pipe section 7 of uniform diameter. By adjusting the length of the straight pipe section 7, the weight of the scrap at a given scrap pile height is balanced with the frictional resistance of the scrap in the horizontal section. Ideally, the electromagnetic brake 6 can be omitted, and the purpose of downward discharge can be achieved by increasing the pile height with each addition of scrap.

[0062] like Figure 7 As shown, the present invention also provides an electric furnace steelmaking equipment 200, including a feeding device 201, a continuous vertical shaft scrap steel preheating device 100, an electric furnace feeding and conveying structure 202 (feeding chute) and an electric furnace 203. The continuous vertical shaft scrap steel preheating device 100 is located above the electric furnace feeding and conveying structure 202. The feeding device 201 is used to feed the continuous vertical shaft scrap steel preheating device 100. The electric furnace feeding and conveying structure 202 is used to add the scrap steel preheated by the continuous vertical shaft scrap steel preheating device 100 into the electric furnace 203.

[0063] The working process of the continuous shaft scrap preheating device 100 of the present invention is as follows:

[0064] Step a: Figure 3 As shown, the first valve 31 and the second valve 32 are closed, and the feeding device 201 transports the scrap steel 8 to the feeding hopper 34 and adds the scrap steel 8 to the feeding hopper 34; Figure 4 As shown, the second valve 32 is opened, and the scrap steel in the feeding hopper 34 is added to the silo 33. The amount of scrap steel added each time cannot exceed the volume of the silo 33, and the second valve 32 must be effectively closed. When the scrap steel is completely in the silo 33, the second valve 32 is closed.

[0065] Step b, the electromagnetic brake 6 is energized to generate braking resistance for scrap steel above the control range; Figure 5 As shown, the first valve 31 is opened, and the scrap steel in the silo 33 falls into the shaft 1; Figure 6 As shown, the first valve 31 is closed, and the scrap steel enters the preheating process. As the scrap steel surface rises, the scrap steel's own gravity causes the scrap steel in the chute section 2 to overcome the maximum static friction and begin to move. At the same time, the high-temperature flue gas enters the equal-diameter straight pipe section 7, the chute section 2, and the vertical shaft 1 through the discharge port 4, preheating the scrap steel before being discharged through the flue gas suction port 5.

[0066] Step c: During the preheating process, the electromagnetic brake 6 is adjusted according to the falling speed of the scrap steel, so that the preheated scrap steel can enter the electric furnace or the scrap steel transport device from the discharge port 4 at a uniform speed;

[0067] Step d: repeat steps a, b and c to continuously preheat the scrap steel in the shaft.

[0068] As described above, the continuous shaft scrap steel preheating device and electric furnace steelmaking equipment of the present invention have the following beneficial effects:

[0069] In the present invention, a vertical shaft preheating method is adopted, which can maximize the use of flue gas waste heat and reduce power consumption during electric furnace production; finger valves are no longer provided in the continuous vertical shaft scrap steel preheating device, and there is no safety accident such as explosion caused by finger valve leakage; the vertical shaft and the chute section are arranged with equal cross-sections to ensure that there is no risk of scrap steel getting stuck throughout the process; the continuous feeding structure adopts a sealed bin + double-layer plug-in valve structure to ensure sealed feeding throughout the process, and the second end of the vertical shaft can be closed to ensure the effective sealing of the flue gas channel, avoiding the problem of flue gas overflow and mixing with wild wind during the preheating process; an electromagnetic brake is used on the chute section, and there is no directly force-bearing part, which improves the safety of system operation while ensuring that the addition of scrap steel is controllable.

[0070] The above description is only an illustrative embodiment of the present invention and is not intended to limit the scope of the present invention. Any equivalent changes and modifications made by those skilled in the art without departing from the concept and principle of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A continuous shaft scrap steel preheating device, characterized in that: The invention comprises a vertical shaft, a chute section and a control unit, wherein the vertical shaft is arranged as a straight pipe, and the chute section is arranged as a curved pipe; the first end of the vertical shaft is connected to the first end of the chute section, and the vertical shaft and the chute section are arranged with equal cross-sections; the second end of the vertical shaft is connected to the first end of a continuous feeding structure, the first end of the continuous feeding structure is arranged to be closable or openable, and the second end of the continuous feeding structure is arranged to be closable or openable; the second end of the chute section can be connected to a discharge port, and the side wall of the vertical shaft below the continuous feeding structure is connected to a smoke suction port; the control unit can control the closing or opening of the continuous feeding structure; The slide pipe section is provided with an electromagnetic brake, and the electromagnetic brake is electrically connected to the control unit; The continuous feeding structure includes a silo, a first end of which is connected to the shaft via a first valve, and the first valve is electrically connected to the control unit; The second end of the silo is connected to the feeding hopper via a second valve, and the second end of the silo constitutes the second end of the continuous feeding structure; the second valve is electrically connected to the control unit; The slide pipe section is a 90° elbow; The second end of the chute section is connected to the discharge port through a straight pipe section of equal diameter.

2. The continuous shaft scrap preheating device according to claim 1, characterized in that: The first valve is a gate valve.

3. The continuous shaft scrap preheating device according to claim 1, characterized in that: The second valve is a gate valve.

4. The continuous shaft scrap steel preheating device according to claim 1, characterized in that: The diameter of the feeding hopper is gradually reduced from top to bottom.

5. An electric furnace steelmaking equipment, characterized in that: It comprises a feeding device, the continuous vertical shaft scrap steel preheating device according to any one of claims 1 to 4, an electric furnace feeding and conveying structure, and an electric furnace, wherein the continuous vertical shaft scrap steel preheating device is located above the electric furnace feeding and conveying structure, the feeding device is used to feed the continuous vertical shaft scrap steel preheating device, and the electric furnace feeding and conveying structure is used to add the scrap steel preheated by the continuous vertical shaft scrap steel preheating device into the electric furnace.

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