Electric furnace flue gas treatment system, environmentally friendly steelmaking arc furnace and electric furnace steelmaking production method

Abstract

The present invention relates to an electric furnace flue gas treatment system and an environmentally friendly steelmaking electric arc furnace equipped with the electric furnace flue gas treatment system. The electric furnace flue gas treatment system includes a flue gas mixing pipeline, a first flue gas outlet pipe connected to the electric furnace flue, and a scrap steel preheating device connected to the scrap steel inlet of the electric furnace. The scrap steel preheating device is equipped with a second flue gas outlet pipe, and the first flue gas outlet pipe and the second flue gas outlet pipe are both connected to the inlet end of the flue gas mixing pipeline. In addition, it also relates to an electric furnace steelmaking production method, a part of the electric furnace flue gas is directly drawn out as the first flue gas, and the remaining part is discharged after preheating the scrap steel to form the second flue gas, the first flue gas is mixed with the second flue gas, and the flow distribution of the first flue gas and the second flue gas makes the temperature of the mixed flue gas above 900°C. The present invention uses the heat of the electric furnace flue gas itself to simultaneously realize the preheating of the scrap steel and the treatment of dioxins generated during the preheating of the scrap steel, does not require additional consumption of energy such as natural gas, and has good environmental protection and economic performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of electric furnace steelmaking, and specifically relates to an electric furnace fume treatment system, an environmentally friendly steelmaking arc furnace equipped with the electric furnace fume treatment system, and an electric furnace steelmaking production method. Background Art

[0002] In the steelmaking process of modern ultra-high power electric arc furnaces, the heat carried away by the exhaust gas accounts for about half of the input electrical energy. Allowing such a large amount of heat to be dissipated in the exhaust pipe and the surrounding environment is a huge waste of resources and energy. For this reason, scrap steel preheating technology has been developed to use the heat contained in the exhaust gas to heat the scrap steel to a certain level before entering the furnace; this technology can partially recover the heat in the flue gas into the preheated scrap steel, which can reduce the waste of heat from the flue gas on the one hand, and reduce the energy and time required to melt the preheated scrap steel on the other hand, which can achieve the dual effects of reducing smelting energy consumption and improving productivity.

[0003] If the scrap steel used for electric arc furnace steelmaking is clean, then this type of technology can achieve partial recovery of heat in the flue gas relatively perfectly without causing negative impact on the surrounding environment; the so-called clean means that the scrap steel does not contain organic compounds such as grease, paint and plastic, especially chlorine-containing organic compounds. However, clean scrap steel usually means less sources and high prices, which is not conducive to steelmaking productivity and cost control. Scrap steel with a wide source and low price is usually social scrap steel. This type of scrap steel comes from waste products from all walks of life in society, and is mixed together during the recycling process, and is basically not clean. In the process of preheating such scrap steel using flue gas heat, the flue gas has a higher temperature in the upstream stage of its flow, which can decompose the mixed organic compounds in the scrap steel into a mixture of small organic molecules, carbon monoxide and carbon dioxide; during the flow process, as the heat of the flue gas is continuously transferred to the scrap steel with a lower temperature, the flue gas temperature continues to decrease; generally, when the temperature drops to the range of about 850 to 250°C, these mixtures contained in the flue gas begin to react and quickly generate highly carcinogenic dioxins. If there are no subsequent treatment measures for dioxins, they will enter the production and living environment with the dust and exhaust gas after dust removal, causing permanent harm to the health of humans and other organisms.

[0004] The effective treatment measures at present are: heating the flue gas rich in dioxins and at a low temperature to above 900℃ with a burner and maintaining it for a certain period of time, so that the dioxins can be fully decomposed at this high temperature; then, cooling it quickly to below about 250℃ by spraying water mist. Otherwise, the decomposition products of dioxins will react again and quickly generate dioxins when they are slowly cooled in the range of about 850-250℃. However, the combustion of the burner requires additional consumption of natural gas. For areas with sufficient natural gas supply and reasonable prices, this method is economically feasible. Otherwise, other alternatives are needed. Summary of the invention

[0005] The invention relates to an electric furnace fume treatment system, an environmentally friendly steelmaking arc furnace equipped with the electric furnace fume treatment system and an electric furnace steelmaking production method, which can at least solve some defects of the prior art.

[0006] The present invention relates to an electric furnace flue gas treatment system, comprising a flue gas mixing duct, a first flue gas outlet pipe connected to the electric furnace flue, and a scrap steel preheating device connected to the scrap steel inlet of the electric furnace, wherein the scrap steel preheating device is provided with a second flue gas outlet pipe, and the first flue gas outlet pipe and the second flue gas outlet pipe are both connected to the inlet end of the flue gas mixing duct.

[0007] As one of the implementation modes, a two-inlet-one-out three-way regulating valve is provided at the inlet end of the flue gas mixing duct, and the first flue gas outlet pipe and the second flue gas outlet pipe are respectively connected to the two inlet ends of the three-way regulating valve.

[0008] As one of the implementation modes, the three-way regulating valve is a water-cooled valve.

[0009] As one of the implementation modes, the scrap steel preheating device comprises a scrap steel preheating well, which is provided with a steel pusher and a charging port suitable for docking with the scrap steel inlet of the electric furnace, and the steel pusher is arranged opposite to the charging port.

[0010] As one of the implementation modes, the scrap steel preheating well is a vertical structure, and a scrap steel receiving hopper is provided on the top of the scrap steel preheating well.

[0011] As one of the implementation modes, a walking mechanism is provided at the bottom of the scrap steel preheating well.

[0012] The present invention also relates to an environmentally friendly steelmaking electric arc furnace, comprising an electric furnace body, wherein the electric furnace body has an electric furnace flue and an electric furnace scrap steel inlet, and also comprises the electric furnace flue gas treatment system as described above.

[0013] As one of the implementation modes, the scrap steel inlet of the electric furnace is opened on the side wall of the furnace shell of the electric furnace body.

[0014] The present invention also relates to an electric furnace steelmaking production method, comprising:

[0015] A portion of the electric furnace flue gas generated by electric furnace steelmaking is directly drawn out as the first flue gas, and the remaining portion is discharged after preheating the scrap steel to form the second flue gas. The first flue gas and the second flue gas are mixed, wherein the temperature of the mixed flue gas is above 900°C through flow distribution control of the first flue gas and the second flue gas.

[0016] As one of the embodiments, the production method further comprises: during the main melting period of the electric furnace, after a molten pool is formed in the furnace, opening the furnace wall oxygen lance and carbon lance to start blowing oxygen and spraying carbon into the molten pool to form foamed slag; when the scrap steel above the liquid level of the molten pool is nearly completely melted, the electric arc is well covered by the foamed slag;

[0017] When the molten pool liquid level rises to a certain value, the preheated scrap steel is added into the electric furnace molten pool in batches. The scrap steel melting rate matches the arc input power and the scrap steel adding rate to ensure that the foam slag covers the molten pool throughout the melting process, achieving good refining of the molten steel and automatic outflow of the slag.

[0018] When the weight of 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, tapping begins. When the tapping weight reaches the target value, tapping is stopped. A certain proportion of molten steel and slag is left in the molten pool to facilitate the start of the next smelting cycle.

[0019] The present invention has at least the following beneficial effects:

[0020] In the present invention, a part of the electric furnace flue gas is led out for preheating scrap steel to realize the preliminary utilization of the flue gas waste heat, and the other part of the electric furnace flue gas is directly led out and mixed with the flue gas after preheating the scrap steel. The dioxins that may be contained in the flue gas discharged from the scrap steel preheating device can be fully decomposed by the high-temperature electric furnace flue gas. Therefore, the heat of the electric furnace flue gas itself can be used to simultaneously realize the preheating of the scrap steel and the treatment of the dioxins generated during the preheating of the scrap steel, without the need to consume additional energy such as natural gas, and the environmental protection and economy are better. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] 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.

[0022] Figure 1 A schematic diagram of the structure of an environmentally friendly steelmaking electric arc furnace provided in Embodiment 2 of the present invention;

[0023] Figure 2A schematic diagram of the installation structure of the adaptive flow control valve provided in the fourth embodiment of the present invention;

[0024] Figure 3 This is a schematic diagram of the structure of an adaptive flow control valve provided in Embodiment 4 of the present invention. DETAILED DESCRIPTION

[0025] 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.

[0026] Embodiment 1

[0027] like Figure 1 An embodiment of the present invention provides an electric furnace flue gas treatment system, comprising a flue gas mixing duct 33, a first flue gas outlet pipe 31 connected to the electric furnace flue, and a scrap steel preheating device connected to the scrap steel inlet of the electric furnace, wherein the scrap steel preheating device is provided with a second flue gas outlet pipe 32, and the first flue gas outlet pipe 31 and the second flue gas outlet pipe 32 are both connected to the inlet end of the flue gas mixing duct 33.

[0028] The above-mentioned electric furnace flue can be the fourth flue on the electric furnace cover, which can provide an exhaust channel for the high-temperature flue gas generated by the electric furnace molten pool steelmaking reaction process; the above-mentioned electric furnace scrap steel inlet can be located on the electric furnace cover or on the side wall of the electric furnace shell according to the design requirements of the electric furnace adding scrap steel. Part of the electric furnace flue gas can be discharged through the electric furnace scrap steel inlet and enter the scrap steel preheating device for scrap steel preheating operation, and part can be discharged through the above-mentioned electric furnace flue. In the absence of other flue gas exhaust channels, the electric furnace flue gas is divided into the above-mentioned two parts of flue gas airflow.

[0029] The electric furnace flue gas treatment system provided in this embodiment draws out a part of the electric furnace flue gas for preheating scrap steel to achieve preliminary utilization of the flue gas waste heat, and the other part of the electric furnace flue gas is directly drawn out and mixed with the flue gas after preheating the scrap steel. The dioxins that may be contained in the flue gas discharged from the scrap steel preheating device can be fully decomposed by the high-temperature electric furnace flue gas. Therefore, the heat of the electric furnace flue gas itself can be used to simultaneously achieve scrap steel preheating and the treatment of dioxins generated during the scrap steel preheating process, without the need to consume additional energy such as natural gas, and has better environmental protection and economy.

[0030] Preferably, a tee can be provided at the inlet end of the flue gas mixing duct 33 , the tee having two inlet ends and one outlet end, the two inlet ends being respectively connected to the first flue gas outlet pipe 31 and the second flue gas outlet pipe 32 , and the outlet end of the tee being connected to the flue gas mixing duct 33 .

[0031] Furthermore, in order to ensure the treatment effect of dioxins, it is preferred to ensure that the temperature of the mixed flue gas is above 900°C. The target temperature can be achieved by adjusting the flow rates of the first flue gas outlet pipe 31 and the second flue gas outlet pipe 32. Of course, factors such as the flue gas output of the electric furnace and the amount of scrap steel in the scrap steel preheating device need to be considered, and the dioxins can be fully decomposed while ensuring the scrap steel preheating effect. As the electric furnace smelting process continues, the electric furnace flue gas is continuously generated, and the scrap steel preheating effect in the scrap steel preheating device can generally be guaranteed.

[0032] In one embodiment, the flow distribution adjustment can be achieved by a three-way regulating valve, that is, the inlet end of the flue gas mixing pipe 33 is provided with a two-inlet and one-outlet three-way regulating valve, and the first flue gas outlet pipe 31 and the second flue gas outlet pipe 32 are respectively connected to the two inlet ends of the three-way regulating valve. The three-way regulating valve can obviously adjust the flue gas flow at its two inlet ends. The valve can be purchased from the market, and the specific structure is not described here. Preferably, the three-way regulating valve is a water-cooled valve, which has high working reliability and a long service life.

[0033] In order to prevent the mixed flue gas from reproducing dioxins during subsequent treatment, the mixed flue gas pipeline may be connected to a spray cooling device, such as an evaporative cooler, to quickly cool the mixed flue gas.

[0034] Following the above-mentioned electric furnace flue gas treatment system, such as Figure 1 The scrap steel preheating device comprises a scrap steel preheating well 2, wherein the scrap steel preheating well 2 is provided with a steel pusher 21 and a charging port suitable for docking with the scrap steel inlet of the electric furnace, and the steel pusher 21 is arranged opposite to the charging port. In one embodiment, the scrap steel preheating well 2 is a vertical structure, that is, the scrap steel preheating well 2 is a vertical shaft; further, a scrap steel receiving hopper 22 is provided at the top of the scrap steel preheating well 2, and a feeding valve is provided at the bottom of the scrap steel receiving hopper 22. When it is necessary to add scrap steel to the scrap steel preheating well 2, the valve is opened, and after the feeding is completed, the valve is closed, so as to provide a closed environment condition for the scrap steel preheating well 2. The scrap steel receiving hopper 22 is used to provide support and guidance when adding scrap steel to the scrap steel preheating well 2, and is also used to guide the rising flue gas flow when the feeding valve is opened.

[0035] like Figure 1 The scrap steel inlet of the electric furnace is opened on the side wall of the furnace shell of the electric furnace body 1, and the loading port of the scrap steel preheating well 2 is located on the well wall. The scrap steel preheating well 2 is arranged on the side of the electric furnace body 1, rather than directly above it. On the one hand, the height of the factory building can be reduced and the investment cost can be saved; on the other hand, even if the water-cooling element of the scrap steel preheating well 2 leaks, it will not enter the electric furnace molten pool, thereby avoiding the threat of steam flash explosion to equipment and personnel. However, there are many water-cooling elements in the scrap steel preheating well 2, and the probability of leakage during the smelting process is very high.

[0036] Alternatively, if Figure 1 At the bottom of the scrap preheating well 2, an impact-resistant and wear-resistant bottom plate 23 is provided to absorb the impact energy of the scrap falling into the well, and to withstand the wear caused by the scrap sliding on the bottom plate 23. The pusher 21 can be arranged on the bottom plate 23, and can push the preheated scrap stranded on the bottom plate 23 and enter the electric furnace through the charging port and the scrap steel inlet of the electric furnace; the pusher 21 can use a hydraulic cylinder as a power source.

[0037] More preferably, if Figure 1 A walking mechanism is provided at the bottom of the scrap steel preheating well 2, so that the scrap steel preheating well 2 can be moved with high flexibility, which is not only convenient for the control of electric furnace smelting production, but also suitable for different electric furnace smelting production, and convenient for the maintenance of the scrap steel preheating well 2 and the electric furnace.

[0038] Of course, scrap steel preheating devices with other structures in the art are also applicable to this embodiment, and they are not listed one by one here.

[0039] Embodiment 2

[0040] like Figure 1 An embodiment of the present invention provides an environmentally friendly steelmaking electric arc furnace, including an electric furnace body 1 and the electric furnace flue gas treatment system provided in the above-mentioned embodiment 1. The electric furnace body 1 has an electric furnace flue and an electric furnace scrap steel inlet. Obviously, the electric furnace flue is connected to the above-mentioned first flue gas outlet pipe 31, and the electric furnace scrap steel inlet is connected to the above-mentioned scrap steel preheating device.

[0041] The arrangement of the electric furnace flue and the electric furnace scrap steel inlet on the electric furnace body 1 has been described in the above-mentioned embodiment 1, and will not be described in detail here.

[0042] Embodiment 3

[0043] The embodiment of the present invention provides an electric furnace steelmaking production method, comprising:

[0044] A portion of the electric furnace flue gas generated by electric furnace steelmaking is directly drawn out as the first flue gas, and the remaining portion is discharged after preheating the scrap steel to form the second flue gas. The first flue gas and the second flue gas are mixed, wherein the temperature of the mixed flue gas is above 900°C through flow distribution control of the first flue gas and the second flue gas.

[0045] The electric furnace steelmaking production method can be implemented based on the electric furnace flue gas treatment system provided in the first embodiment or the environmentally friendly steelmaking arc furnace provided in the second embodiment.

[0046] Furthermore, the production method further comprises: during the main melting period of the electric furnace, after a molten pool is formed in the furnace, opening the furnace wall oxygen lance and carbon lance to start blowing oxygen and carbon into the molten pool to form foamed slag; when the scrap steel above the liquid level of the molten pool is nearly completely melted, the electric arc is well covered by the foamed slag;

[0047] When the molten pool liquid level rises to a certain value, the preheated scrap steel is added into the electric furnace molten pool in batches. The scrap steel melting rate matches the arc input power and the scrap steel adding rate to ensure that the foam slag covers the molten pool throughout the melting process, achieving good refining of the molten steel and automatic outflow of the slag.

[0048] When the weight of 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, tapping begins. When the tapping weight reaches the target value, tapping is stopped. A certain proportion of molten steel and slag is left in the molten pool to facilitate the start of the next smelting cycle.

[0049] Before the first furnace is smelted, the scrap steel preheating well 2 can be moved away from the electric furnace body 1 to make room for the furnace cover to be opened. Then, the furnace cover is opened, and a basket with a specified weight of scrap steel is moved to the top of the electric furnace body 1 by a crane. After the basket is lowered to a certain height, the bottom of the basket is opened to drop the scrap steel into the electric furnace body 1. After the basket is lifted and removed, the furnace cover is closed. Then, the scrap steel preheating well 2 is moved to be connected to the electric furnace body 1, and a certain weight of scrap steel is added to the scrap steel preheating well 2 before the charging valve is closed. The scrap steel preheating well 2 can be charged by a basket, a conveyor belt, or a trolley on a slope. When charging, a smoke hood can be set on the scrap steel receiving hopper 22 to better capture the smoke and dust that escapes from the well during the opening of the charging valve.

[0050] In the following smelting cycle, it is no longer necessary to add scrap steel into the electric furnace body 1 by opening the furnace cover. All scrap steel is preheated in the scrap preheating well 2 before entering the electric furnace body 1. When the weight of the existing scrap steel in the scrap preheating well 2 is reduced to a certain level, it can be replenished in time to achieve appropriate resistance to the flow of flue gas in the scrap preheating well 2 and a good scrap preheating effect. Generally, the number of scrap steel additions to the scrap preheating well 2 corresponding to the weight of steel produced in one furnace is 2 to 4 times, depending on the bulk density of the scrap steel in the well.

[0051] Since the small batches of scrap steel preheated in the scrap steel preheating well 2 are almost continuously added to the electric furnace, the small batch added each time is nearly preheated to the highest temperature, which can maximize the recovery of flue gas heat. In addition, since the molten pool space occupied by each small batch of scrap steel added is not too much, there is no need to design a special arc furnace hearth and molten pool. The traditional non-preheating ultra-high power arc furnace can be slightly modified to become the above-mentioned environmentally friendly arc furnace, which can realize the reuse and transformation of existing equipment.

[0052] Embodiment 4

[0053] The embodiment of the present invention provides an electric arc furnace, which can be used as a further optimization of the environmentally friendly steelmaking electric arc furnace provided in the above-mentioned embodiment 2.

[0054] The electric arc furnace comprises a furnace shell and a furnace cover, wherein the furnace shell and the furnace cover are both embedded with water cooling panels 11. The arrangement of the water cooling panels 11 in the furnace shell and in the furnace cover is conventional technology in the art and will not be described in detail herein.

[0055] Preferably, the water-cooling panel 11 of the furnace shell and / or the water-cooling panel 11 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 11 in the furnace shell and the water-cooling panel 11 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 11. According to the smelting conditions of the steelmaking process, the cooling water flow of the current water-cooling panel 11 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 11, 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, thereby 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 11, thereby improving the service life of the water-cooling panel 11.

[0056] Generally, the water-cooled panel 11 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 131 connecting the panel water inlet and the cooling water supply main 141 and a return pipeline 132 connecting the panel water outlet and the cooling water return main 142.

[0057] 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 131 and / or the water return pipeline 132, and a temperature sensor may be provided at the installation location of the water cooling panel 11. The temperature sensor is interlocked with the flow control valve to realize automatic adjustment of the cooling water flow of the water cooling panel 11. Of course, it is also a feasible solution to provide a flow regulating valve in the serpentine pipeline of the water cooling panel 11, but considering the harshness of the working environment of the water cooling panel 11, the flow regulating valve provided here needs to be a high temperature resistant valve.

[0058] 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:

[0059] like Figure 2 and Figure 3The flow regulating unit includes an adaptive flow regulating valve 12, which includes a valve shell 121, a hollow core shell 122 and an adjusting mechanism. The core shell 122 is fixedly installed in the valve shell 121 and divides the inner cavity of the valve shell 121 into a cold water circulation chamber and a hot water circulation chamber. An insulating piston 123 is slidably arranged in the core shell 122 and divides the inner cavity of the core shell 122 into a cold cavity and a hot cavity. Both the cold cavity and the hot cavity are filled with a thermal deformation medium 125. 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 123 and the adjusting area is located in the cold water circulation chamber or the hot The valve housing 121 is provided with a cold water inlet 1211 and a cold water outlet 1212 which are connected to the cold water circulation chamber, and the water inlet pipe 131 includes a first water inlet pipe section connecting the cold water inlet 1211 and the cooling water supply main 141, and a second water inlet pipe section connecting the cold water outlet 1212 and the panel water inlet; the valve housing 121 is provided with a hot water inlet 1213 and a hot water outlet 1214 which are connected to the hot water circulation chamber, and the return water pipe 132 includes a first return water pipe section connecting the panel water outlet and the hot water inlet 1213, and a second return water pipe section connecting the hot water outlet 1214 and the cooling water return water main 142.

[0060] Flange connection can be adopted between the valve housing 121 and the first water inlet pipe section, between the valve housing 121 and the second water inlet pipe section, between the valve housing 121 and the first water return pipe section, and between the valve housing 121 and the fourth water return pipe section. The core housing 122 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 122 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 122 should obviously have a straight section to facilitate the linear motion of the heat-insulating piston 123. The straight section can be square or circular in cross section, depending on the shape of the heat-insulating piston 123; in one embodiment, the core housing 122 can be a long strip housing, and in another embodiment, spherical housing sections can be connected to both ends of the straight section, and the two spherical housing sections extend into the cold water circulation chamber and the hot water circulation chamber respectively.

[0061] like Figure 3 At the insertion point of the core shell 122, the valve shell 121 can be designed to be spherical / quasi-spherical to ensure that the inserted core shell 122 can be in contact with water flow on all sides. The water flow forms a vortex around the core shell 122, which has a better heat exchange effect and can improve the temperature sensing accuracy and response speed of the core shell 122.

[0062] Furthermore, the core shell 122 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 125; in this embodiment, a copper component is used. The thickness of the core shell 122 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 12.

[0063] The above-mentioned thermal deformation medium 125 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 122 and the piston 123. In this embodiment, nitrogen is selected as the thermal deformation medium 125 filled in the cold cavity and the hot cavity. The heat-insulating piston 123 isolates the thermal deformation medium 125 in the cold cavity from the thermal deformation medium 125 in the hot cavity, realizing independent sealing and heat exchange isolation between the two spaces; the thickness of the heat-insulating piston 123 is preferably selected so that when it moves, the thermal deformation medium 125 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.

[0064] Due to the volume change of the thermally deformable medium 125 in the cold cavity and the hot cavity, the above-mentioned heat-insulating piston 123 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 11. It can be seen that in this embodiment, the cooling water flow of the water-cooled panel 11 is regulated by sensing the change in the cooling water temperature of the water-cooled panel 11 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.

[0065] The above-mentioned regulating mechanism may adopt a displacement regulating method or an angle regulating method, and different structures may be adopted according to different regulating methods. This is a conventional technology in the valve field, and it is correspondingly connected with the heat-insulating piston 123, and should meet the following conditions: when the return water temperature of the water-cooled panel 11 increases, the cooling water flow rate of the water-cooled panel 11 increases; when the return water temperature of the water-cooled panel 11 decreases, the cooling water flow rate of the water-cooled panel 11 decreases, until the pressure on both sides of the heat-insulating piston 123 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 12 and ensure high working reliability in the complex working environment of the steelmaking arc furnace. In one of the embodiments, Figure 3The regulating mechanism includes a valve stem 124 and a valve seat 126 disposed in the hot water circulation chamber. The valve stem 124 is connected to the heat-insulating piston 123 and passes through the hot chamber into the hot water circulation chamber. The free end of the valve stem 124 has a regulating portion adapted to the valve seat 126. The valve stem 124 is driven to move linearly by the linear displacement of the heat-insulating piston 123, thereby driving the regulating portion to move closer to or away from the valve seat 126, 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 3 The regulating part is a regulating plug 1241 formed at the free end of the valve stem 124, and the valve seat 126 is separated from the hot water circulation chamber and has a valve hole adapted thereto. Figure 3 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 122 may extend into the transition chamber. The valve seat 126 may be a partition across the connection between the transition chamber and the straight segment outlet chamber. The valve stem 124 is preferably coaxial with the straight segment outlet chamber. The gap between the valve hole and the regulating plug 1241 can be adjusted by the displacement of the valve stem 124. Different regulating characteristics of the cooling water flow rate can be achieved by designing the shape of the regulating plug 1241. Preferably, a conical or parabolic regulating plug 1241 is used.

[0066] Furthermore, a sliding seal is performed at the hole of the core shell 122 through which the valve stem 124 is penetrated, so as to prevent the thermal deformation medium 125 and the cooling water from penetrating into each other.

[0067] Taking the furnace shell water cooling panel 11 as an example, the working process of the above-mentioned adaptive flow control valve 12 is roughly described:

[0068] (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 1241 and the valve hole, so that the adaptive flow regulating valve 12 and the cooling water circulation pipeline maintain a certain initial flow rate. The average flow rate of cooling water in the water-cooled panel 11 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 12 on the one hand, and is conducive to flushing away the bubbles in the water-cooled panel 11 on the other hand, so as to avoid deterioration of the cooling capacity of the water-cooled panel 11. 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 122 is consistent, and accordingly, the volume of the thermal deformation medium 125 in the cold cavity and the hot cavity remains unchanged, so that the distance between the regulating plug 1241 and the valve hole remains unchanged.

[0069] (2) After the steelmaking process is started, the water-cooled panel 11 receives heat radiation and heat convection from the furnace, causing the temperature of the cooling water flowing through the water-cooled panel 11 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-deformable medium 125 in the hot cavity, causing the latter to expand in volume and increase in pressure. The cooling water temperature in the cold water circulation chamber remains unchanged, and the volume and pressure of the heat-deformable medium 125 in the cold cavity remain at the previous level, resulting in different pressures on both sides of the insulation piston 123. Under the action of the pressure difference, the insulation piston 123 moves toward the cold cavity side; driven by the insulation piston 123, the valve stem 124 also moves upward, increasing the distance between the regulating plug 1241 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 11.

[0070] When the pressures on the upper and lower sides of the piston 123 are equal, the movement of the heat-insulating piston 123 stops.

[0071] The increase in cooling water flow increases the cooling strength of the water-cooled panel 11. If the heat flux density received by the water-cooled panel 11 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 125 in the hot cavity is reduced and the pressure is reduced. Under the action of the pressure difference, the heat-insulating piston 123 drives the valve stem 124 to move toward the hot cavity side, so that the distance between the regulating plug 1241 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 11. 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.

[0072] (3) When the water-cooled panel 11 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 125 in the heat cavity will continue to decrease. Under the action of the pressure difference, the heat-insulating piston 123 drives the valve stem 124 to move toward the heat cavity side, so that the distance between the regulating plug 1241 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 rate inside the water-cooled panel 11. 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 1241 and the valve hole returns to the initial value.

[0073] 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 environmentally friendly steelmaking electric arc furnace, comprising an electric furnace body, wherein the electric furnace body has an electric furnace flue and an electric furnace scrap steel inlet, characterized in that: It also includes an electric furnace fume treatment system, the electric furnace fume treatment system includes a fume mixing pipeline, a first fume outlet pipe connected to the electric furnace flue, and a scrap steel preheating device connected to the scrap steel inlet of the electric furnace, the scrap steel preheating device is equipped with a second fume outlet pipe, the first fume outlet pipe and the second fume outlet pipe are both connected to the inlet end of the fume mixing pipeline; The electric furnace body comprises 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; 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 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.

2. The environmentally friendly steelmaking electric arc furnace according to claim 1, characterized in that: A two-inlet-one-out three-way regulating valve is provided at the inlet end of the smoke mixing pipeline, and the first smoke outlet pipe and the second smoke outlet pipe are respectively connected to the two inlet ends of the three-way regulating valve.

3. The environmentally friendly steelmaking electric arc furnace according to claim 2, characterized in that: The three-way regulating valve is a water-cooled valve.

4. The environmentally friendly steelmaking electric arc furnace according to claim 1, characterized in that: The scrap steel preheating device comprises a scrap steel preheating well, which is provided with a steel pusher and a charging port suitable for docking with the scrap steel inlet of the electric furnace, and the steel pusher is arranged opposite to the charging port.

5. The environmentally friendly steelmaking electric arc furnace according to claim 4, characterized in that: The scrap steel preheating well is a vertical structure, and a scrap steel receiving hopper is provided on the top of the scrap steel preheating well.

6. The environmentally friendly steelmaking electric arc furnace according to claim 4, characterized in that: A walking mechanism is arranged at the bottom of the scrap steel preheating well.

7. The environmentally friendly steelmaking electric arc furnace according to claim 1, characterized in that: The scrap steel inlet of the electric furnace is opened on the side wall of the furnace shell of the electric furnace body.

8. The production method of the environmentally friendly steelmaking electric arc furnace according to any one of claims 1 to 7, characterized in that: include: A portion of the electric furnace flue gas generated by electric furnace steelmaking is directly drawn out as the first flue gas, and the remaining portion is discharged after preheating the scrap steel to form the second flue gas. The first flue gas and the second flue gas are mixed, wherein the temperature of the mixed flue gas is above 900°C through flow distribution control of the first flue gas and the second flue gas.

9. The production method according to claim 8, characterized in that: During the main melting period of the electric furnace, after a molten pool is formed in the furnace, the oxygen lance and carbon lance on the furnace wall are opened to start blowing oxygen and spraying carbon into the molten pool to form foamy slag; when the scrap steel above the molten pool surface is almost completely melted, the arc is well covered by the foamy slag; When the molten pool liquid level rises to a certain value, the preheated scrap steel is added into the electric furnace molten pool in batches. The scrap steel melting rate matches the arc input power and the scrap steel adding rate to ensure that the foam slag covers the molten pool throughout the melting process, achieving good refining of the molten steel and automatic outflow of the slag. When the weight of 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, tapping begins. When the tapping weight reaches the target value, tapping is stopped. A certain proportion of molten steel and slag is left in the molten pool to facilitate the start of the next smelting cycle.

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