An electric arc furnace

Abstract

The present invention relates to an electric arc furnace, comprising a furnace shell and a furnace cover, wherein the furnace shell and the furnace cover are both embedded with a water-cooling panel, and the water-cooling panel of the furnace shell and / or the water-cooling panel of the furnace cover are long-life panels, and the cooling water flow rate of the long-life panels is adjustable. The electric arc furnace provided by the present invention is designed to have an adjustable cooling water flow rate of the water-cooling panel, and can adjust the cooling water flow rate of the current water-cooling panel in real time as needed according to the smelting conditions of the steelmaking process, so that the adjusted cooling water flow rate just matches the heat load requirement of the current water-cooling panel, without causing excessive cooling water flow rate and corresponding power consumption loss, and at the same time, it will not significantly increase the average temperature of the cooling water outlet, thereby avoiding the situation where the heat transfer capacity is deteriorated due to underheated boiling at a local position of the water-cooling panel due to a low cooling water flow rate, and improving the service life of the water-cooling panel.

Description

Technical Field

[0001] The invention relates to an electric arc furnace. Background Art

[0002] In order to reduce the consumption of refractory materials during the smelting process, modern ultra-high power steelmaking electric arc furnaces generally use upper furnace shells and furnace covers in the form of embedded water-cooled panels. At present, the cooling water flow of these water-cooled panels has been determined at the beginning of the design and is no longer adjusted during the smelting process. At the beginning of the design, the cooling water flow of the current water-cooled panel is generally determined based on the maximum heat flux density that the current water-cooled panel may suffer during smelting to ensure the reliability of its cooling capacity under harsh working conditions; in this way, the cooling water flow used under normal smelting conditions is much larger than the actual need, which will significantly increase the cooling water volume and the corresponding circulation power consumption. By increasing the temperature difference between the cooling water inlet and outlet of the water-cooled panel, the cooling water design flow rate can be reduced to a certain extent, thereby partially offsetting the above-mentioned adverse effects; however, the disadvantage of this compromise approach is that the increase in the average temperature of the cooling water outlet cannot reliably reflect the fact that the temperature rise of some parts of the water-cooled panel is too large. Although the average outlet temperature is still far from the saturation value, some parts with lower cooling water flow rates may already be in a subcooled boiling state, making these places prone to scaling and increasing heat transfer resistance, increasing the risk of burning through the cooling water pipe wall, and the increase in the average cooling water outlet temperature will make this subcooled boiling easier. Summary of the invention

[0003] The present invention relates to an electric arc furnace, which can at least solve some of the defects of the prior art.

[0004] The present invention relates to an electric arc furnace, comprising a furnace shell and a furnace cover. The furnace shell and the furnace cover are both embedded with water cooling panels. The water cooling panel of the furnace shell and / or the water cooling panel of the furnace cover are long-life panels, and the cooling water flow of the long-life panels is adjustable.

[0005] As one of the embodiments, the long-life panel is equipped with a cooling water circulation pipeline, which includes an inlet pipeline connecting the panel water inlet and the cooling water supply main pipe and a return pipeline connecting the panel water outlet and the cooling water return main pipe, and a flow regulating unit is provided on the cooling water circulation pipeline.

[0006] As one of the embodiments, the flow regulating unit includes an adaptive flow regulating valve, which includes a valve shell, a hollow core shell and an adjusting mechanism. The core shell is fixedly installed in the valve shell and divides the inner cavity of the valve shell into a cold water circulation chamber and a hot water circulation chamber. An insulating piston is slidably arranged in the core shell and divides the inner cavity of the core shell into a cold cavity and a hot cavity. Both the cold cavity and the hot cavity are filled with thermal deformation medium. The cold cavity is at least partially located in the cold water circulation chamber, and the hot cavity is at least partially located in the hot water circulation chamber; the adjusting mechanism is connected to the insulating piston and the adjusting area is located in the cold water circulation chamber or the hot water circulation chamber;

[0007] The valve housing is provided with a cold water inlet and a cold water outlet connected to the cold water circulation chamber, and the water inlet pipeline includes a first water inlet pipe section connecting the cold water inlet and the cooling water supply main pipe and a second water inlet pipe section connecting the cold water outlet and the panel water inlet;

[0008] The valve housing is provided with a hot water inlet and a hot water outlet connected to the hot water circulation chamber, and the return water pipeline includes a first return water pipe section connecting the panel outlet and the hot water inlet and a second return water pipe section connecting the hot water outlet and the cooling water return water main.

[0009] As one of the embodiments, the regulating mechanism includes a valve stem and a valve seat arranged in the hot water circulation chamber, the valve stem is connected to the insulating piston and passes from the hot chamber into the hot water circulation chamber, and the free end of the valve stem has an regulating portion adapted to the valve seat.

[0010] As one of the implementation modes, the regulating portion is a regulating plug formed at the free end of the valve stem, and the valve seat is disposed transversely in the hot water circulation chamber and is adaptively provided with a valve hole.

[0011] As one of the implementation modes, a sliding seal is performed at the penetration hole of the core shell through which the valve stem is penetrated.

[0012] As one of the implementation modes, the thermal deformation medium in the cold chamber and the thermal deformation medium in the hot chamber are both nitrogen.

[0013] As one of the implementation modes, the core shell is a copper component.

[0014] The present invention has at least the following beneficial effects:

[0015] The electric arc furnace provided by the present invention has an adjustable cooling water flow rate of the water-cooled panel by designing the cooling water flow rate of the water-cooled panel. The cooling water flow rate of the current water-cooled panel can be adjusted in real time as needed according to the smelting conditions of the steelmaking process, so that the adjusted cooling water flow rate just matches the thermal load requirement of the current water-cooled panel without causing excessive cooling water flow rate and corresponding power consumption loss, and at the same time, it will not significantly increase the average cooling water outlet temperature, thereby avoiding the situation where the heat transfer capacity is deteriorated due to underheated boiling caused by the low cooling water flow rate at a local position of the water-cooled panel, thereby improving the service life of the water-cooled panel. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 A schematic diagram of the installation structure of an adaptive flow control valve provided in an embodiment of the present invention;

[0018] Figure 2 A schematic diagram of the structure of an adaptive flow control valve provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] An embodiment of the present invention provides an electric arc furnace, including a furnace shell and a furnace cover, wherein the furnace shell and the furnace cover are both embedded with a water-cooling panel 2. The arrangement of the water-cooling panel 2 in the furnace shell and in the furnace cover are conventional techniques in the art and will not be described in detail herein.

[0021] Preferably, the water-cooling panel 2 of the furnace shell and / or the water-cooling panel 2 of the furnace cover are long-life panels, and the cooling water flow of the long-life panels is adjustable. Among them, preferably, the water-cooling panel 2 in the furnace shell and the water-cooling panel 2 in the furnace cover both adopt the long-life panel. The electric arc furnace provided in this embodiment is designed with an adjustable cooling water flow of the water-cooling panel 2. According to the smelting conditions of the steelmaking process, the cooling water flow of the current water-cooling panel 2 can be adjusted in real time as needed, so that the adjusted cooling water flow just matches the heat load requirement of the current water-cooling panel 2, without causing excessive cooling water flow and corresponding power consumption loss, and at the same time, it will not significantly increase the average temperature of the cooling water outlet, avoiding the situation where the heat transfer capacity is deteriorated due to underheating boiling caused by the low cooling water flow rate at the local position of the water-cooling panel 2, thereby improving the service life of the water-cooling panel 2.

[0022] Generally, the water-cooled panel 2 is equipped with a cooling water circulation pipeline, that is, the above-mentioned long-life panel is equipped with a cooling water circulation pipeline, wherein the cooling water circulation pipeline includes an inlet pipeline 31 connecting the panel water inlet and the cooling water supply main pipe 41 and a return pipeline 32 connecting the panel water outlet and the cooling water return main pipe 42.

[0023] Based on the above requirement of adjustable cooling water flow, in one embodiment, a flow regulating unit may be provided on the above cooling water circulation pipeline, for example, a flow control valve may be provided on the water inlet pipeline 31 and / or the water return pipeline 32, and a temperature sensor may be provided at the installation location of the water cooling panel 2. The temperature sensor is interlocked with the flow control valve to realize automatic adjustment of the cooling water flow of the water cooling panel 2. Of course, it is also a feasible solution to provide a flow regulating valve in the serpentine pipeline of the water cooling panel 2, but considering the harshness of the working environment of the water cooling panel 2, the flow regulating valve provided here needs to be a high temperature resistant valve.

[0024] This embodiment provides a preferred solution, which can achieve the purpose of adaptively adjusting the cooling water flow without consuming external energy or involving the sending and receiving of control signals. Specifically:

[0025] like Figure 1 and Figure 2The flow regulating unit includes an adaptive flow regulating valve 1, which includes a valve shell 11, a hollow core shell 12 and an adjusting mechanism. The core shell 12 is fixedly installed in the valve shell 11 and divides the inner cavity of the valve shell 11 into a cold water circulation chamber and a hot water circulation chamber. A heat-insulating piston 13 is slidably arranged in the core shell 12 and divides the inner cavity of the core shell 12 into a cold cavity and a hot cavity. The cold cavity and the hot cavity are both filled with a thermal deformation medium 15. The cold cavity is at least partially located in the cold water circulation chamber, and the hot cavity is at least partially located in the hot water circulation chamber; the adjusting mechanism is connected to the heat-insulating piston 13 and the adjusting area is located in the cold water circulation chamber or the The hot water circulation chamber; the valve housing 11 is provided with a cold water inlet 111 and a cold water outlet 112 which are connected to the cold water circulation chamber, the water inlet pipe 31 includes a first water inlet pipe section connecting the cold water inlet 111 and the cooling water supply main pipe 41, and a second water inlet pipe section connecting the cold water outlet 112 and the panel water inlet; the valve housing 11 is provided with a hot water inlet 113 and a hot water outlet 114 which are connected to the hot water circulation chamber, the return water pipe 32 includes a first return water pipe section connecting the panel water outlet and the hot water inlet 113, and a second return water pipe section connecting the hot water outlet 114 and the cooling water return water main pipe 42.

[0026] Flange connection can be adopted between the valve housing 11 and the first water inlet pipe section, between the valve housing 11 and the second water inlet pipe section, between the valve housing 11 and the first water return pipe section, and between the valve housing 11 and the second water return pipe section. The core housing 12 partially extends into the cold water circulation chamber so that its cold cavity is at least partially located in the cold water circulation chamber; similarly, the core housing 12 partially extends into the hot water circulation chamber so that its hot cavity is at least partially located in the hot water circulation chamber. The core housing 12 should obviously have a straight section to facilitate the linear motion of the heat-insulating piston 13. The straight section can be square or circular in cross section, depending on the shape of the heat-insulating piston 13; in one embodiment, the core housing 12 can be a long strip shell, and in another embodiment, spherical shell sections can be connected to both ends of the straight section, and the two spherical shell sections extend into the cold water circulation chamber and the hot water circulation chamber respectively.

[0027] like Figure 2 At the insertion point of the core shell 12, the valve shell 11 can be designed to be spherical / quasi-spherical to ensure that the inserted core shell 12 can be in contact with water flow on all sides. The water flow forms a vortex around the core shell 12, which has a better heat exchange effect and can improve the temperature sensing accuracy and response speed of the core shell 12.

[0028] Furthermore, the core shell 12 is preferably made of a material with good thermal conductivity, such as a metal with a large thermal conductivity coefficient and a low specific heat capacity, which can better transfer the water flow temperature to the thermal deformation medium 15; in this embodiment, a copper component is used. The thickness of the core shell 12 should be as thin as possible while meeting the requirements of structural strength and rigidity, so as to improve the response speed of the adaptive flow control valve 1.

[0029] The above-mentioned thermal deformation medium 15 can show a significant change in volume with the change of temperature. It is preferably selected to be a gas with low specific heat capacity and no corrosive effect on the core shell 12 and the piston 13. In this embodiment, nitrogen is selected as the thermal deformation medium 15 filled in the cold cavity and the hot cavity. The heat-insulating piston 13 isolates the thermal deformation medium 15 in the cold cavity from the thermal deformation medium 15 in the hot cavity, realizing independent sealing and heat exchange isolation between the two spaces; the thickness of the heat-insulating piston 13 is preferably selected so that when it moves, the thermal deformation medium 15 in the cold cavity and the hot cavity will not be excessively affected by the heat exchange of the cooling water flowing around the opposite side.

[0030] Due to the volume change of the thermally deformable medium 15 in the cold cavity and the hot cavity, the above-mentioned heat-insulating piston 13 can be pushed to slide, and the regulating mechanism can be driven to perform corresponding regulating actions, so as to control the flow area in the cold water circulation chamber / hot water circulation chamber, thereby achieving the purpose of regulating the cooling water flow in the water-cooled panel 2. It can be seen that in this embodiment, the cooling water flow of the water-cooled panel 2 is regulated by sensing the change in the cooling water temperature of the water-cooled panel 2 itself, which does not require consumption of external energy, does not involve the sending and receiving of control signals, and has high working reliability, so it is easy to install and serve for a long time in the complex working environment of the steelmaking arc furnace.

[0031] The above-mentioned regulating mechanism can adopt a displacement regulating method or an angle regulating method. Different structures can be adopted according to different regulating methods. This is a conventional technology in the valve field. It is correspondingly connected with the heat-insulating piston 13 and should meet the following requirements: when the return water temperature of the water-cooled panel 2 increases, the cooling water flow of the water-cooled panel 2 increases; when the return water temperature of the water-cooled panel 2 decreases, the cooling water flow of the water-cooled panel 2 decreases until the pressure on both sides of the heat-insulating piston 13 reaches equilibrium. In this embodiment, the above-mentioned regulating mechanism adopts a displacement regulating method, which can simplify the structure of the adaptive flow regulating valve 1 and ensure high working reliability in the complex working environment of the steelmaking arc furnace. In one of the embodiments, Figure 2The regulating mechanism includes a valve stem 14 and a valve seat 16 disposed in the hot water circulation chamber. The valve stem 14 is connected to the heat-insulating piston 13 and passes through the hot chamber into the hot water circulation chamber. The free end of the valve stem 14 has a regulating portion adapted to the valve seat 16. The valve stem 14 is driven to move linearly by the linear displacement of the heat-insulating piston 13, thereby driving the regulating portion to move closer to or away from the valve seat 16, thereby achieving the purpose of flow regulation. The regulating portion may be a valve plate or other components. In an optional embodiment, such as Figure 2 The regulating part is a regulating plug 141 formed at the free end of the valve stem 14, and the valve seat 16 is separated from the hot water circulation chamber and has a valve hole adapted thereto. Figure 2 The hot water circulation chamber may be a right-angle chamber, including a straight segment inlet chamber, a straight segment outlet chamber, and a transition chamber connecting the straight segment inlet chamber and the straight segment outlet chamber. One end of the core shell 12 may extend into the transition chamber. The valve seat 16 may be a partition across the connection between the transition chamber and the straight segment outlet chamber. The valve stem 14 is preferably coaxial with the straight segment outlet chamber. The gap between the valve hole and the regulating plug 141 can be adjusted by the displacement of the valve stem 14. Different regulating characteristics of the cooling water flow rate can be achieved by designing the shape of the regulating plug 141. Preferably, a conical or parabolic regulating plug 141 is used.

[0032] Furthermore, a sliding seal is performed at the hole of the core shell 12 through which the valve stem 14 is penetrated, so as to prevent the thermal deformation medium 15 and the cooling water from penetrating into each other.

[0033] Taking the furnace shell water cooling panel 2 as an example, the working process of the above-mentioned adaptive flow control valve 1 is roughly described:

[0034] (1) When the steelmaking process has not yet started and the electric arc furnace is still in a cold state, an initial distance is maintained between the regulating plug 141 and the valve hole, so that the adaptive flow regulating valve 1 and the cooling water circulation pipeline maintain a certain initial flow rate. The average flow rate of cooling water in the water-cooled panel 2 corresponding to this initial flow rate is usually between 0.5 and 1.5 m / s; this initial flow rate ensures the smooth start of the adaptive adjustment function of the adaptive flow regulating valve 1, and on the other hand, it is conducive to flushing away the bubbles in the water-cooled panel 2 to avoid deterioration of the cooling capacity of the water-cooled panel 2. At this time, in the cold water circulation chamber and the hot water circulation chamber, the temperature of the cooling water flowing around the core shell 12 is consistent, and accordingly, the volume of the thermal deformation medium 15 in the cold cavity and the hot cavity remains unchanged, so that the distance between the regulating plug 141 and the valve hole remains unchanged.

[0035] (2) After the steelmaking process is started, the water-cooled panel 2 receives heat radiation and heat convection from the furnace, causing the temperature of the cooling water flowing through the water-cooled panel 2 to rise. The magnitude of the rise depends on the heat flux density acting on it and the instantaneous relative size of the cooling water flow rate. Subsequently, the cooling water with the increased temperature transfers heat to the heat-deformed medium 15 in the hot cavity, causing the latter to expand in volume and increase in pressure. If the cooling water temperature in the cold water circulation chamber remains unchanged, the volume and pressure of the heat-deformed medium 15 in the cold cavity remain at the previous level, resulting in different pressures on both sides of the insulation piston 13. Under the action of the pressure difference, the insulation piston 13 moves toward the cold cavity side; driven by the insulation piston 13, the valve stem 14 also moves upward, increasing the distance between the regulating plug 141 and the valve hole, increasing the outflow area of ​​the valve hole and reducing the local resistance coefficient, thereby increasing the cooling water flow inside the water-cooled panel 2.

[0036] When the pressures on the upper and lower sides of the piston 13 are equal, the movement of the heat-insulating piston 13 stops.

[0037] The increase in cooling water flow increases the cooling strength of the water-cooled panel 2. If the heat flux density received by the water-cooled panel 2 no longer increases at this time, the increased cooling water flow will reduce the temperature of the cooling water return water; at this time, the volume of the thermally deformable medium 15 in the hot cavity is reduced and the pressure is reduced. Under the action of the pressure difference, the heat-insulating piston 13 drives the valve stem 14 to move toward the hot cavity side, so that the distance between the regulating plug 141 and the valve hole becomes smaller, reducing the outflow area of ​​the valve hole and increasing the local resistance coefficient, thereby reducing the cooling water flow inside the water-cooled panel 2. Under a certain heat flux density, the above process will eventually be in a balanced state, at which time the increased cooling water flow and temperature just match the current heat flux density, so that the cooling water temperature will not rise too high. Under normal smelting conditions, the average temperature of the cooling water return outlet is in the range of 7 to 15°C; under extreme smelting conditions, such as when the arc is exposed for too long, the average temperature of the cooling water return outlet does not exceed 28°C.

[0038] (3) When the water-cooled panel 2 no longer receives heat from the furnace, such as during the shutdown cooling process, the cooling water temperature in the hot water circulation chamber will continue to decrease, and the volume and pressure of the thermally deformable medium 15 in the heat cavity will continue to decrease. Under the action of the pressure difference, the heat-insulating piston 13 drives the valve stem 14 to move toward the heat cavity, so that the distance between the regulating plug 141 and the valve hole continues to decrease, gradually reducing the outflow area of ​​the valve hole while increasing the local resistance coefficient, thereby continuously reducing the cooling water flow inside the water-cooled panel 2. Finally, when the cooling water temperatures in the cold water circulation chamber and the hot water circulation chamber are the same, the distance between the regulating plug 141 and the valve hole returns to the initial value.

[0039] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An electric arc furnace, comprising a furnace shell and a furnace cover, wherein the furnace shell and the furnace cover are both embedded with water-cooled panels, characterized in that: The water-cooling panel of the furnace shell and / or the water-cooling panel of the furnace cover is a long-life panel, and the cooling water flow rate of the long-life panel is adjustable; The long-life panel is equipped with a cooling water circulation pipeline, which includes a water inlet pipeline connecting the panel water inlet and the cooling water supply pipe and a water return pipeline connecting the panel water outlet and the cooling water return pipe, and a flow regulating unit is provided on the cooling water circulation pipeline; The flow regulating unit comprises an adaptive flow regulating valve, which comprises a valve shell, a hollow core shell and an adjusting mechanism. The core shell is fixedly installed in the valve shell and divides the inner cavity of the valve shell into a cold water circulation chamber and a hot water circulation chamber. A heat-insulating piston is slidably arranged in the core shell and divides the inner cavity of the core shell into a cold cavity and a hot cavity. Both the cold cavity and the hot cavity are filled with a thermal deformation medium. The cold cavity is at least partially located in the cold water circulation chamber, and the hot cavity is at least partially located in the hot water circulation chamber. The adjusting mechanism is connected to the heat-insulating piston and the adjusting area is located in the cold water circulation chamber or the hot water circulation chamber. The valve housing is provided with a cold water inlet and a cold water outlet connected to the cold water circulation chamber, and the water inlet pipeline includes a first water inlet pipe section connecting the cold water inlet and the cooling water supply main pipe and a second water inlet pipe section connecting the cold water outlet and the panel water inlet; The valve housing is provided with a hot water inlet and a hot water outlet communicating with the hot water circulation chamber, and the return water pipeline comprises a first return water pipe section connecting the panel water outlet and the hot water inlet and a second return water pipe section connecting the hot water outlet and the cooling water return water main pipe; Flange connections are adopted between the valve housing and the first water inlet pipe section, between the valve housing and the second water inlet pipe section, between the valve housing and the first water return pipe section, and between the valve housing and the second water return pipe section.

2. The electric arc furnace according to claim 1, characterized in that: The regulating mechanism includes a valve stem and a valve seat arranged in the hot water circulation chamber. The valve stem is connected to the heat-insulating piston and passes from the heat cavity into the hot water circulation chamber. The free end of the valve stem has an regulating portion adapted to the valve seat.

3. The electric arc furnace according to claim 2, characterized in that: The regulating part is a regulating plug formed at the free end of the valve stem, and the valve seat is separated from the hot water circulation chamber and is adaptively provided with a valve hole.

4. The electric arc furnace according to claim 2, characterized in that: The core shell is provided with a sliding seal at a penetration hole through which the valve stem is penetrated.

5. The electric arc furnace according to claim 1, characterized in that: The heat deformation medium in the cold cavity and the heat deformation medium in the hot cavity are both nitrogen.

6. The electric arc furnace according to claim 1, characterized in that: The core shell is a copper component.

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