Bottom electrode cooling method of direct-current submerged arc furnace and direct-current submerged arc furnace

Abstract

The invention relates to the technical field of submerged arc furnaces, in particular to a bottom electrode cooling method of a direct-current submerged arc furnace and the direct-current submerged arc furnace. The bottom electrode cooling method of the direct-current submerged arc furnace comprises the steps that a heat exchange cavity is formed in a bottom electrode of the direct-current submerged arc furnace; the first end of the water inlet pipe and the first end of the water outlet pipe are inserted into the heat exchange cavity, and the water inlet pipe and the water outlet pipe are relatively fixed and hermetically connected with the heat exchange cavity; the second end of the water inlet pipe is used for guiding heat exchange liquid conveyed by the first water suction pump to the water inlet pipe, the heat exchange liquid is discharged into the heat exchange cavity from the first end of the water inlet pipe, the heat exchange liquid is used for absorbing heat generated by the bottom electrode, and the heat exchange liquid conveyed by the first water suction pump is provided by a cooling device; and the heat exchange liquid which is gradually heated is guided into the water outlet pipe by utilizing the first end of the water outlet pipe and is discharged into the cooling device from the second end of the water outlet pipe. In this way, the cooling efficiency, safety and reliability of the electrode end part are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of submerged arc furnaces, and particularly to a method for cooling the bottom electrode of a DC submerged arc furnace and a DC submerged arc furnace. Background Art

[0002] A DC submerged arc furnace is an industrial device that uses a DC arc as a heat source for smelting and heating processes, and is widely used in fields such as metallurgy and chemical industry. Compared with traditional AC submerged arc furnaces, DC submerged arc furnaces have higher energy efficiency and more stable operation. The bottom electrode of a DC submerged arc furnace usually uses a graphite electrode. When the graphite electrode is used as the bottom electrode of a DC submerged arc furnace, it needs to extend outside the submerged arc furnace to lead the current out of the DC submerged arc furnace. However, the thermal conductivity of the graphite electrode is very high, resulting in easy oxidation of the graphite electrode. Therefore, it is necessary to cool the graphite electrode.

[0003] In some scenarios, the part of the graphite electrode exposed outside the DC submerged arc furnace is easily oxidized due to high temperature. Therefore, it is necessary to focus on cooling the electrode end of the graphite electrode exposed outside the DC submerged arc furnace. Simple air cooling or water cooling methods are often used to cool the electrode end of the graphite electrode, but the contact area between the heat exchange liquid and the graphite electrode is limited, and the heat exchange efficiency is not high. For example, in the air cooling method, the thermal conductivity coefficient of air is low, and it is difficult to quickly remove a large amount of heat generated at the electrode end of the graphite electrode, resulting in low cooling efficiency. And some water cooling methods are to nested multiple layers of water cooling pipes outside the electrode end of the graphite electrode, which increases the manufacturing difficulty and cost of the equipment. In addition, when water cooling pipes are arranged outside the graphite electrode, the molten iron passing through the DC submerged arc furnace will react with the water cooling pipes to generate gasification, and it is very easy to cause an explosion hazard, and the safety and reliability of cooling are low. Summary of the Invention

[0004] In order to solve the technical problems of low cooling efficiency, low cooling safety and reliability of the electrode end of the graphite electrode of a DC submerged arc furnace, the purpose of the present invention is to provide a method for cooling the bottom electrode of a DC submerged arc furnace and a DC submerged arc furnace, and the specific technical solutions adopted are as follows:

[0005] A method for cooling the bottom electrode of a DC submerged arc furnace, comprising: opening a heat exchange cavity inside the bottom electrode of the DC submerged arc furnace, and the part of the bottom electrode with the heat exchange cavity serves as the electrode end and is not inside the DC submerged arc furnace; inserting the first end of the water inlet pipe and the first end of the water outlet pipe into the heat exchange cavity, and the water inlet pipe and the water outlet pipe are relatively fixed and sealed to the heat exchange cavity, and the distance from the first end of the water inlet pipe to the furnace center of the DC submerged arc furnace is less than the distance from the first end of the water outlet pipe to the furnace center of the DC submerged arc furnace; using the second end of the water inlet pipe to guide the heat exchange liquid conveyed by the first water pump to the water inlet pipe, and discharging it into the heat exchange cavity from the first end of the water inlet pipe, so as to use the heat exchange liquid to absorb the heat generated by the bottom electrode, and the heat exchange liquid conveyed by the first water pump is provided by the cooling device; using the first end of the water outlet pipe to guide the gradually heated heat exchange liquid into the water outlet pipe, and discharging it from the second end of the water outlet pipe to the cooling device.

[0006] A DC submerged arc furnace, the DC submerged arc furnace includes a bottom electrode, a heat exchange cavity is opened inside the bottom electrode, and the part of the bottom electrode with the heat exchange cavity serves as the electrode end and is not inside the DC submerged arc furnace; the DC submerged arc furnace further includes a water inlet pipe, a water outlet pipe, a first water pump, and a cooling device; the first end of the water inlet pipe and the first end of the water outlet pipe are inserted into the heat exchange cavity, and the water inlet pipe and the water outlet pipe are relatively fixed and sealed to the heat exchange cavity, and the distance from the first end of the water inlet pipe to the furnace center of the DC submerged arc furnace is less than the distance from the first end of the water outlet pipe to the furnace center of the DC submerged arc furnace; the output port of the first water pump is connected to the second end of the water inlet pipe, and the water inlet pipe discharges the heat exchange liquid conveyed by the first water pump into the heat exchange cavity, so as to use the heat exchange liquid to absorb the heat generated by the bottom electrode, and the cooling device is used to provide the cooled heat exchange liquid for the first water pump; the second end of the water outlet pipe is connected to the cooling device, the first end of the water outlet pipe guides the gradually heated pressure heat exchange liquid into the water outlet pipe, and the water outlet pipe guides the heated pressure heat exchange liquid to the cooling device, and the cooling device cools the heated pressure heat exchange liquid.

[0007] In the above method for cooling the bottom electrode of a DC submerged arc furnace and the DC submerged arc furnace, a heat exchange cavity is opened inside the bottom electrode of the DC submerged arc furnace, and the part of the bottom electrode with the heat exchange cavity serves as the electrode end and is not inside the DC submerged arc furnace; then the first end of the water inlet pipe and the first end of the water outlet pipe are inserted into the heat exchange cavity, and the water inlet pipe and the water outlet pipe are relatively fixed and sealed to the heat exchange cavity, and the distance from the first end of the water inlet pipe to the furnace center of the DC submerged arc furnace is less than the distance from the first end of the water outlet pipe to the furnace center of the DC submerged arc furnace; secondly, use the second end of the water inlet pipe to guide the heat exchange liquid conveyed by the first water pump to the water inlet pipe, and discharge it into the heat exchange cavity from the first end of the water inlet pipe, so as to use the heat exchange liquid to absorb the heat generated by the bottom electrode, and the heat exchange liquid conveyed by the first water pump is provided by the cooling device; finally, use the first end of the water outlet pipe to guide the gradually heated heat exchange liquid into the water outlet pipe, and discharge it from the second end of the water outlet pipe to the cooling device.

[0008] Thus, in the embodiment of the present invention, a heat exchange cavity is opened inside the electrode end. Then, the heat exchange liquid provided by the cooling device is pressurized by a first water pump and introduced into the heat exchange cavity through a water inlet pipe to cool the electrode end. The heat exchange liquid can directly contact the inside of the electrode end, thereby quickly taking away the heat generated at the electrode end, with a better cooling effect, effectively improving the cooling efficiency, ensuring the stable operation of the bottom electrode in a high-temperature environment, and prolonging the service life of the electrode. Further, since the heat exchange cavity is opened inside the electrode end and is not in the DC submerged arc furnace, the problem of molten iron penetration in the DC submerged arc furnace is avoided, improving the safety and reliability of cooling the electrode end. In addition, the distance from the first end of the water inlet pipe to the furnace center of the DC submerged arc furnace is less than the distance from the first end of the water outlet pipe to the furnace center of the DC submerged arc furnace. The heat exchange liquid can gradually flow from the end face of the electrode end to the bottom of the electrode end, sequentially exchanging heat with the areas from the end face to the bottom of the electrode end, avoiding the direct contact between the heat exchange liquid and the bottom of the electrode end and vaporization, and further improving the cooling reliability and accuracy. Further, the water outlet pipe guides the gradually heated heat exchange liquid to the cooling device for recycling, improving the resource utilization rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is a schematic diagram of the composition structure of the DC submerged arc furnace disclosed in the embodiment of the present invention;

[0010] Figure 2 is a schematic diagram of a partial structure of the first DC submerged arc furnace disclosed in the embodiment of the present invention;

[0011] Figure 3 is a cross-sectional schematic diagram of a partial structure of the first DC submerged arc furnace disclosed in the embodiment of the present invention;

[0012] Figure 4 is an external structure schematic diagram of a partial structure of the first DC submerged arc furnace disclosed in the embodiment of the present invention;

[0013] Figure 5 is a schematic diagram of a partial structure of the second DC submerged arc furnace disclosed in the embodiment of the present invention;

[0014] Figure 6 is a cross-sectional schematic diagram of a partial structure of the second DC submerged arc furnace disclosed in the embodiment of the present invention;

[0015] Figure 7 is an external structure schematic diagram of a partial structure of the second DC submerged arc furnace disclosed in the embodiment of the present invention;

[0016] Figure 8 is a schematic flowchart of a method for cooling the bottom electrode of a DC submerged arc furnace disclosed in the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] To further elaborate on the technical means and effects adopted by the present invention to achieve the intended invention purpose, the following specifically describes, in conjunction with the accompanying drawings and preferred embodiments, a bottom electrode cooling method for a DC submerged arc furnace and the DC submerged arc furnace according to the present invention, including their specific implementation manners, structures, features, and effects. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. In addition, the specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0018] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs.

[0019] The following specifically describes, in conjunction with the accompanying drawings, the specific solutions of a bottom electrode cooling method for a DC submerged arc furnace and the DC submerged arc furnace provided by the present invention.

[0020] As Figure 1 shown, the DC submerged arc furnace 10 includes a bottom electrode 101. A heat exchange cavity 102 is formed inside the bottom electrode 101. The part of the bottom electrode 101 with the heat exchange cavity 102 serves as the electrode end and is not inside the DC submerged arc furnace 10. The DC submerged arc furnace 10 further includes a water inlet pipe 103, a water outlet pipe 104, a first water pump 105, and a cooling device 106. The first end of the water inlet pipe 103 and the first end of the water outlet pipe 104 are inserted into the heat exchange cavity 102. The water inlet pipe 103 and the water outlet pipe 104 are relatively fixed and sealed to the heat exchange cavity 102. The distance from the first end of the water inlet pipe 103 to the furnace center of the DC submerged arc furnace 10 is less than the distance from the first end of the water outlet pipe to the furnace center of the DC submerged arc furnace 10. The output port of the first water pump 105 is connected to the second end of the water inlet pipe 103. The water inlet pipe 103 discharges the heat exchange liquid conveyed by the first water pump 105 into the heat exchange cavity 102 to utilize the heat exchange liquid to absorb the heat generated by the bottom electrode 101. The cooling device 106 is used to provide cooled heat exchange liquid for the first water pump 105. The second end of the water outlet pipe 104 is connected to the cooling device 106. The first end of the water outlet pipe 104 guides the gradually heated heat exchange liquid into the water outlet pipe 104. The water outlet pipe 104 guides the heated and pressurized heat exchange liquid to the cooling device 106, and the cooling device 106 cools the heated and pressurized heat exchange liquid.

[0021] Specifically, in the embodiment of the present invention, the cavity of the heat exchange chamber 102 can be set as a spiral tubular shape, a honeycomb shape or a parallel flow channel structure. In the embodiment of the present invention, the heat exchange chamber 102 is opened axially inward along the bottom electrode 101 starting from the end face of the electrode end. In order to avoid corrosion of the interior of the electrode end by the heat exchange liquid, an insulating and heat-conducting coating is plated on the inner wall of the heat exchange chamber 102. This insulating and heat-conducting coating can be a coating with high thermal conductivity and insulation, such as a coating made of ceramic matrix composite materials, polymer coatings, graphene / boron nitride composite materials, coatings made of inorganic insulating and heat-conducting materials, etc. When plating the insulating and heat-conducting coating on the heat exchange chamber 102, the specific process is as follows: Before spraying, the inner wall of the heat exchange chamber needs to be strictly surface-treated, including removing impurities such as oil stains, rust, and dust, usually by methods such as sandblasting and pickling, to improve the bonding strength between the coating and the substrate. According to the working environment and performance requirements of the heat exchange chamber, a suitable insulating and heat-conducting coating material is selected. The embodiment of the present invention does not limit the coating material. Common materials include ceramic matrix composite materials, polymer coatings, etc. Different materials have differences in aspects such as thermal conductivity, insulation performance, and high-temperature resistance. During the spraying process, parameters such as the spraying temperature, pressure, and the moving speed of the spray gun need to be precisely controlled to ensure that the uniformity and thickness of the coating meet the requirements. For example, in plasma spraying technology, the temperature of the plasma usually needs to be controlled at several thousand degrees Celsius, and the moving speed of the spray gun is between several centimeters per second and dozens of centimeters per second. After spraying, post-treatment processes such as heat treatment and grinding are carried out to further improve the performance and quality of the insulating and heat-conducting coating. For example, through heat treatment, the internal stress of the coating can be eliminated, and the density and stability of the coating can be improved.

[0022] In this way, the insulating and heat-conducting coating can prevent the heat exchange liquid from directly contacting the bottom electrode through which direct current is passed, avoiding risks such as short circuit, electric leakage, or electric breakdown caused by the corrosion of the bottom electrode by the heat exchange liquid, extending the service life of the heat exchange chamber, reducing the maintenance cost of the equipment, improving the cooling safety and reliability of the bottom electrode, and ensuring the operation safety of the DC submerged arc furnace. In addition, the insulating and heat-conducting coating can quickly transfer the heat on the surface of the bottom electrode to the heat exchange liquid, reduce the thermal resistance, and improve the heat dissipation efficiency, thereby further improving the cooling efficiency of the bottom electrode. Further, the insulating and heat-conducting coating can effectively prevent the conduction of current on the inner wall of the heat exchange chamber, avoid safety accidents caused by problems such as electric leakage, and also prevent electrical short circuits between components with different potentials, improving the electrical safety and stability of the equipment.

[0023] The part of the bottom electrode 101 with the heat exchange chamber 102 serves as the electrode end and is outside the DC submerged arc furnace 10, that is, the electrode end is the part exposed outside the DC submerged arc furnace.

[0024] Further, the cooling device 106 includes a heat exchange liquid storage tank, a primary condensation tank, and a secondary condensation tank. Among them, the heat exchange liquid storage tank is used to store the heat exchange liquid, and the primary condensation tank and the secondary condensation tank are used to cool the heat exchange liquid in the heat exchange liquid storage tank. Specifically, the first water pump 105 pressurizes and extracts the heat exchange liquid in the heat exchange liquid storage tank, then passes it into the primary condensation tank and the secondary condensation tank for cooling, and then passes it into the heat exchange cavity. After the heat exchange liquid circulates in the heat exchange cavity, it is discharged from the water outlet pipe back to the cooling device 106 for recycling, improving the resource utilization rate.

[0025] Further, the temperature at the bottom of the electrode end is the highest, and the temperature gradually decreases from the bottom of the electrode end to the end face in sequence. If the heat exchange liquid contacts the bottom of the electrode end immediately, it may be vaporized, making it difficult to cool the bottom electrode, resulting in low cooling efficiency. In addition, the water vapor occupies the space of the heat exchange cavity, preventing the heat exchange liquid from completely filling the cavity, reducing the volume of the liquid actually participating in heat exchange, further weakening the overall cooling capacity, and possibly causing the electrode temperature to get out of control, triggering an overheating failure, and resulting in low cooling reliability and safety of the bottom electrode. Further, when the heat exchange liquid vaporizes, its volume will expand sharply. If the heat exchange cavity is a closed or semi-closed space, the gas generated by vaporization cannot be discharged in time, leading to a sudden increase in the pressure inside the cavity. When the pressure exceeds the design bearing limit of the heat exchange cavity, seals, or the cavity, it may cause seal failure, pipe rupture, or joint leakage, resulting in the leakage of the heat exchange liquid, and even triggering electric shock or equipment shutdown accidents, further leading to low cooling reliability and safety of the bottom electrode. Therefore, in order to avoid the problem that the heat exchange liquid contacts the bottom of the electrode end and vaporizes at the beginning, the embodiment of the present invention adopts a structure in which the distance from the first end of the water inlet pipe to the furnace center of the DC submerged arc furnace is less than the distance from the first end of the water outlet pipe to the furnace center of the DC submerged arc furnace, so that the heat exchange liquid flows into the heat exchange cavity from the first end of the water inlet pipe and gradually flows from the end face of the electrode end to the bottom of the electrode end. During the flowing process, the heat exchange liquid exchanges heat with the inner wall of the heat exchange cavity in sequence, gradually cools the electrode end until it flows to the bottom of the electrode end and is discharged from the water outlet pipe. In this way, adopting the structure in which the distance from the first end of the water inlet pipe to the furnace center of the DC submerged arc furnace is less than the distance from the first end of the water outlet pipe to the furnace center of the DC submerged arc furnace can avoid the heat exchange liquid that is introduced from first contacting the bottom of the electrode end and vaporizing, improving the cooling efficiency, cooling safety, and reliability.

[0026] Further, please refer to Figures 2 to Figure 4, As an alternative embodiment of the present invention, a first insertion hole 107 and a second insertion hole 108 are provided at the end of the electrode. Both the first insertion hole 107 and the second insertion hole 108 communicate with the heat exchange chamber 102. The first end of the water inlet pipe is inserted into the heat exchange chamber 102 through the first insertion hole 107, and the first end of the water outlet pipe is inserted into the heat exchange chamber 102 through the second insertion hole 108. The heat exchange chamber 102, the first insertion hole 107, and the second insertion hole 108 are close to the end face of the electrode end of the bottom electrode of the DC submerged arc furnace that is exposed outside the DC submerged arc furnace; an installation opening is provided on the end face of the electrode end, and the installation opening communicates with the heat exchange chamber 102; the part of the water inlet pipe 103 located in the heat exchange chamber 102 is perpendicular to the part of the water outlet pipe 104 located in the heat exchange chamber 102; the installation opening is sealed by a seal 109, and a tensioning hole 1010 is provided on the seal 109. One end of the tensioning member 1011 is fixedly connected to the part of the water inlet pipe 103 located in the heat exchange chamber 102 or the part of the water outlet pipe 104 located in the heat exchange chamber 102. The other end of the tensioning member 1011 passes through the tensioning hole 1010 and is fixed, so that the seal 109 is relatively fixed to the part of the water inlet pipe 103 located in the heat exchange chamber 102 or the part of the water outlet pipe 104 located in the heat exchange chamber 102, preventing the heat exchange liquid in the heat exchange chamber 102 from damaging the sealing connection between the seal 109 and the installation opening on the end face of the electrode end.

[0027] Specifically, the outer sidewall of the water inlet pipe is sealingly connected to the inner sidewall of the first insertion hole 107, and the outer sidewall of the water outlet pipe is sealingly connected to the inner sidewall of the second insertion hole 108. The first insertion hole 107 and the second insertion hole 108 can be provided on the sidewall of the electrode end or on the end face of the electrode end.

[0028] Further, as Figure 2 and Figure 3 shown, a support frame 1012 is provided in the heat exchange chamber. The part of the water outlet pipe 104 located in the heat exchange chamber 102 passes through the support frame 1012 to support the part of the water outlet pipe 104 located in the heat exchange chamber 102 by using the support frame 1012, preventing the part of the water outlet pipe 104 located in the heat exchange chamber 102 from bending and shaking. The part of the water outlet pipe 104 located in the heat exchange chamber 102 points to the furnace center; one end of the tensioning member 1011 is fixedly connected to the part of the water inlet pipe 103 located in the heat exchange chamber 102; a buffer hole is provided on the inner wall of the bottom electrode opposite to the water outlet of the part of the water inlet pipe 103 located in the heat exchange chamber 102. The diameter of the buffer hole is larger than the outer diameter of the water inlet pipe, and the first end of the part of the water inlet pipe located in the heat exchange chamber is located in the buffer hole to relieve the impact force of the heat exchange liquid by using the buffer hole, so that the heat exchange liquid entering the heat exchange chamber flows stably and directionally to the water drainage port of the water outlet pipe.

[0029] Specifically, in the embodiment of the present invention, an installation opening is provided on the end face of the electrode end, and the installation opening can be sealed by a seal 109. The seal 109 includes, but is not limited to, silicone rubber seals, ceramic matrix seals, metal matrix seals, and graphite matrix seals, etc. A tension hole for installing a tension member can be provided on the seal. One end of the tension member can pass through the tension hole and be fixedly connected to the part of the water inlet pipe or the water outlet pipe located in the heat exchange cavity. The other end of the tension member can be fixed on the other side of the tension hole of the seal, so as to cooperate and fix the seal with the water inlet pipe or the water outlet pipe. The reliability of the seal is improved.

[0030] Further, the water outlet pipe 104 includes a first sub-pipe and a second sub-pipe. The first sub-pipe is hermetically connected to the second insertion hole 108, and the second sub-pipe is hermetically connected to the first sub-pipe through a connecting member. The first sub-pipe extends along the radial direction of the heat exchange cavity 102, and the second sub-pipe extends along the axial direction of the heat exchange cavity 102; the first sub-pipe is arranged to extend along the radial direction of the heat exchange cavity 102, and the second end of the second sub-pipe is close to the bottom of the electrode end. The support frame 1012 is arranged on one side of the second end of the second sub-pipe, and the second sub-pipe passes through the support frame 1012 to support the second sub-pipe to prevent the second sub-pipe from bending and shaking; the part of the second sub-pipe located in the heat exchange cavity 102 points to the furnace center. A buffer hole is provided on the inner wall of the bottom electrode corresponding to the water outlet of the first end of the part of the water inlet pipe 103 located in the heat exchange cavity 102. The aperture of the buffer hole is larger than the outer diameter of the water inlet pipe 103, and the first end of the part of the water inlet pipe 103 located in the heat exchange cavity 102 is located in the buffer hole to utilize the buffer hole to exchange heat and the impact force of the heat exchange liquid, so that the heat exchange liquid entering the heat exchange cavity 102 flows stably and directionally to the drain port corresponding to the second end of the second sub-pipe.

[0031] More specifically, the support frame 1012 is made of high-strength titanium alloy material. This material not only has excellent strength and corrosion resistance, but also has a low density, and can provide reliable support for the second sub-pipe without adding too much weight. Its structural design is a cross-shaped frame, and the horizontal and vertical support beams intersect with each other to form a stable support network, further enhancing the overall rigidity of the support frame. The support frame 1012 is precisely positioned and installed inside the heat exchange cavity 102, and its installation position has been verified by mechanical calculation and simulation to ensure that it can provide the best support effect for the second sub-pipe.

[0032] The outlet pipe 104 is composed of a first sub-pipe and a second sub-pipe. This segmented design takes into account both the installation convenience and the heat exchange efficiency. The first sub-pipe is made of seamless stainless steel pipe, and its pipe diameter is precisely selected according to the flow rate and pressure requirements of the heat exchange fluid. The wall thickness of the pipe is calculated based on strength to ensure stable operation under high-pressure environments. The first sub-pipe is hermetically connected to the second insertion hole 108. The second sub-pipe is also made of high-quality stainless steel pipe, and it is hermetically connected to the first sub-pipe through a special flange connector. The surface of the flange connector is processed with high precision, and together with the sealing gasket and bolt fastening, a reliable sealing structure is formed to ensure the stable transportation of the heat exchange fluid in the pipe. The first sub-pipe extends radially along the heat exchange cavity 102, while the second sub-pipe extends axially along the heat exchange cavity 102. The layout where the two are perpendicular to each other enables the heat exchange fluid to form an efficient flow path in the cavity. The second end of the second sub-pipe is precisely close to the bottom of the electrode end. Such a design can fully take away the heat generated at the electrode end and improve the cooling efficiency.

[0033] The support frame 1012 is arranged on one side of the second end of the second sub-pipe. At the part where the second sub-pipe passes through the support frame 1012, a circular support hole adapted to the outer diameter of the pipe is provided. The inner wall of the support hole is polished and installed with a wear-resistant polytetrafluoroethylene bushing, which can not only reduce the friction between the pipe and the support frame, but also enhance the support effect, effectively preventing the second sub-pipe from bending and shaking due to factors such as vibration and fluid impact during long-term operation, and ensuring the stable transportation of the heat exchange fluid. The part of the second sub-pipe located in the heat exchange cavity 102 points towards the furnace center. Such a layout can guide the heat exchange fluid to concentrate on cooling the key parts in the furnace and optimize the heat exchange process.

[0034] The design of the part of the inlet pipe 103 located in the heat exchange cavity 102 and the buffer hole further improves the stability of the heat exchange fluid flow. The inlet pipe 103 is made of copper pipe with good thermal conductivity, and its pipe diameter is determined according to the flow rate requirements of the cooling system. A buffer hole is opened on the inner wall of the bottom electrode corresponding to the first end of the part of the inlet pipe 103 located in the heat exchange cavity 102. The aperture of the buffer hole is calculated by fluid mechanics and is 2 - 3 times larger than the outer diameter of the inlet pipe 103. Such a size design can not only ensure that the first end of the inlet pipe 103 can be smoothly placed in the buffer hole, but also provide enough buffer space for the heat exchange fluid. The inner wall of the buffer hole is designed with a circular arc transition. When the heat exchange fluid flows out of the inlet pipe 103, the circular arc inner wall can effectively disperse the impact force of the fluid, adjust the flow rate and flow direction of the heat exchange fluid, so that it can flow stably and directionally towards the drain port corresponding to the second end of the second sub-pipe, avoiding the turbulent flow phenomenon caused by fluid impact, and improving the overall efficiency and stability of the cooling system.

[0035] Further, please refer to Figure 5 and Figure 7, the heat exchange chamber 102, the first insertion hole 107, and the second insertion hole 108 are close to the end face of the electrode end of the bottom electrode of the DC submerged arc furnace that is exposed outside the DC submerged arc furnace; an installation opening is provided on the end face of the electrode end, and the installation opening communicates with the heat exchange chamber 102. The installation opening is sealed by a seal 109. The seal 109 is provided with a tensioning hole 1010, a first insertion hole 107, and a second insertion hole 108. One end of a tensioning member 1011 is fixedly connected to a part of a fixing member 1013 provided on the inner wall of the heat exchange chamber 102. The other end of the tensioning member 1011 passes through the tensioning hole 1010 and is fixed, so that the seal 109 and the fixing member 1013 are relatively fixed, preventing the heat exchange liquid in the heat exchange chamber 102 from damaging the sealed connection between the seal 109 and the installation opening on the end face of the electrode end. The water inlet pipe 103 enters the heat exchange chamber 102 through the first insertion hole 107, and the water outlet pipe 104 is inserted into the heat exchange chamber 102 through the second insertion hole 108.

[0036] Furthermore, as Figure 5 and Figure 7 shown, a support frame 1014 is provided in the heat exchange chamber. The part of the water outlet pipe 104 located in the heat exchange chamber 102 passes through the support frame 1014, so as to use the support frame 1014 to support the part of the water outlet pipe 104 located in the heat exchange chamber 102, preventing the part of the water outlet pipe 104 located in the heat exchange chamber 102 from bending and shaking.

[0037] Specifically, the support frame 1014 plays a key role in the structural stability in this embodiment of the present invention. The support frame 1014 is made of high-strength stainless steel material. Its unique truss structure design reduces its own weight as much as possible while ensuring sufficient support strength, so as to reduce the load impact on the overall equipment. The size of the support frame 1014 is accurately calculated according to the diameter of the installation opening provided on the end face and the diameter of the heat exchange chamber. The transverse span is adapted to the inner width of the heat exchange chamber 102, and the longitudinal height is determined according to the installation position of the water outlet pipe 104 in the heat exchange chamber 102, ensuring that stable and reliable support can be provided for the water outlet pipe 104.

[0038] Further, the embodiment of the present invention further includes a first heat conducting member (not shown in the figure) and a first heat insulating member (not shown in the figure). The support frame 1014 is disposed inside the heat exchange chamber 102 and fixedly connected to the inner side wall of the electrode end. The portion of the water outlet pipe 104 located inside the heat exchange chamber 102 passes through the support frame 1014 to utilize the support frame 1014 to support the portion of the water outlet pipe 104 located inside the heat exchange chamber 102, so as to prevent the portion of the water outlet pipe 104 located inside the heat exchange chamber 102 from bending or shaking. The support frame 1014 is disposed on one side of the second end of the water outlet pipe 104 for supporting the water outlet pipe 104; the first heat conducting member is disposed between the contact surfaces of the support frame 1014 and the inner side wall of the electrode end and is tightly connected to the support frame 1014 and the inner side wall of the electrode end to conduct the heat of the electrode end to the support frame 1014 and perform heat exchange with the heat exchange liquid; the first heat insulating member is disposed between the contact surfaces of the support frame 1014 and the outer side wall of the water outlet pipe 104 and is tightly connected to the support frame 1014 and the outer side wall of the water outlet pipe 104 to prevent the heat of the heat exchange liquid in the water outlet pipe 104 from being conducted to the inside of the heat exchange chamber 102.

[0039] Specifically, in the embodiment of the present invention, the support frame 1014, the first heat conducting member and the first heat insulating member play a key role in the heat management and structural stability of the heat exchange chamber 102. The portion of the water outlet pipe 104 located inside the heat exchange chamber 102 passes through a circular through hole reserved by the first support frame 1014. The diameter of the through hole is slightly larger than the outer diameter of the water outlet pipe 104. While ensuring the smooth passage of the pipeline, the limiting effect of the support frame 1014 can effectively prevent the water outlet pipe 104 from bending or shaking inside the heat exchange chamber 102 due to factors such as fluid pressure and vibration, thereby ensuring the stable transportation of the heat exchange liquid in the pipeline. The support frame 1014 is disposed on one side of the second end of the water outlet pipe 104. In the case of a long pipeline, like a stable anchor point, it provides reliable support to the water outlet pipe 104 from the side and maintains the accuracy of its spatial position.

[0040] The first heat conducting member is made of a graphite-based composite material with a high heat conduction coefficient. Its surface has been specially treated, having good flatness and conformability. The first heat conducting member is disposed between the contact surfaces of the support frame 1014 and the inner side wall of the electrode end. During installation, the tiny gaps are filled with thermal grease to make it tightly connected to the support frame 1014 and the inner side wall of the electrode end, forming an efficient heat conduction channel. During the operation of the device, a large amount of heat is generated at the electrode end due to the conversion of electrical energy. These heats are quickly conducted to the support frame 1014 through the first heat conducting member, and then heat exchange is performed with the heat exchange liquid flowing through the water outlet pipe 104 to take away the heat, realizing the effective cooling of the electrode end and ensuring the normal operation of the electrode.

[0041] The first heat insulator is made of an aerogel material with a low thermal conductivity. This material has a porous structure filled with a large number of tiny air chambers, which can greatly hinder heat transfer. The first heat insulator is arranged between the contact surface of the support frame 1014 and the outer side wall of the water outlet pipe 104. Its shape is customized according to the contour of the contact part of the two. During installation, it is firmly pasted with a heat-resistant insulating glue to ensure close fitting with the support frame 1014 and the outer side wall of the water outlet pipe 104, forming a tight heat insulation barrier. In this way, during the flow of the heat exchange liquid in the water outlet pipe 104, the low-temperature heat carried by it is effectively blocked and cannot be conducted to the inside of the heat exchange chamber 102, avoiding cold loss. At the same time, it also prevents the high-temperature environment in the heat exchange chamber from affecting the temperature of the heat exchange liquid, ensuring the efficient operation of the cooling system.

[0042] Further, a second heat conducting member is provided on the bottom surface of the heat exchange chamber opposite to the end face of the electrode end, and the heat at the bottom surface of the electrode end is quickly conducted to the heat exchange liquid through the second heat conducting member.

[0043] Specifically, a second heat conducting member is provided on the bottom surface of the heat exchange chamber 102 opposite to the end face of the electrode end. This measure significantly improves the heat conduction efficiency. The second heat conducting member can be a heat conducting member made of a metal matrix composite material. This material uses metals such as aluminum and copper as the matrix, and uniformly disperses reinforcing particles such as silicon carbide and alumina. It is formed by powder metallurgy or squeeze casting processes, combining the good toughness and high thermal conductivity of metals, as well as the high strength and wear resistance of the reinforcing particles; the graphite heat conducting member utilizes the layered crystal structure of natural flake graphite or artificial graphite, with extremely high thermal conductivity along the interlayer direction and strong chemical stability; the silicon carbide heat conducting member has a covalent bond crystal structure, with high hardness, high temperature resistance and excellent thermal conductivity. When installing the second heat conducting member, first precisely grind the bottom surface of the heat exchange chamber and the bottom surface of the electrode end to ensure that the surface roughness reaches below Ra0.8, and then apply a silver glue with a high thermal conductivity coefficient and perform hot pressing and curing under a pressure of 0.2 MPa to make the second heat conducting member closely fit with the two, forming an efficient heat conduction channel, which can quickly conduct the heat generated at the bottom surface of the electrode end to the heat exchange liquid, greatly improving the cooling efficiency.

[0044] Further, a second heat insulator is provided on the outer side wall of the part of the water outlet pipe located in the heat exchange chamber to prevent the heat exchange liquid in the water outlet pipe from exchanging heat with the heat exchange liquid near the end face of the electrode end inside the heat exchange chamber.

[0045] Specifically, a second heat insulation member is provided on the outer side wall of the part of the water outlet pipe located in the heat exchange cavity. The second heat insulation member can be a heat insulation coating, and the heat insulation coating can adopt a nano-composite heat insulation coating, with silicone resin as the base material, adding nano-scale heat insulation fillers such as silica aerogel and hollow ceramic microspheres, and forming a uniform and dense coating on the outer side wall of the water outlet pipe through a spraying process. The coating thickness is controlled within 0.3 - 0.5 mm, and the heat insulation coating is constructed by a high-pressure airless spraying device to ensure uniform coating thickness without sagging or missing spraying. In this way, the second heat insulation member can effectively prevent the heat exchange liquid in the water outlet pipe from exchanging heat with the heat exchange liquid near the end face of the electrode end in the heat exchange cavity, avoid the heat of the heat exchange liquid in the water outlet pipe from diffusing into the heat exchange cavity, prevent the temperature of the heat exchange liquid from rising, ensure the stable operation of the cooling system, and significantly improve the reliability and safety of cooling.

[0046] Further, as Figure 8 shown, the present invention also provides a bottom electrode cooling method for a DC submerged arc furnace, including the following steps:

[0047] Step S801, a heat exchange cavity is opened inside the bottom electrode of the DC submerged arc furnace, and the part of the bottom electrode with the heat exchange cavity serves as the electrode end and is not inside the DC submerged arc furnace.

[0048] Specifically, an insulating and heat-conducting coating is plated on the inner wall of the heat exchange cavity.

[0049] Step S802, the first end of the water inlet pipe and the first end of the water outlet pipe are inserted into the heat exchange cavity, and the water inlet pipe and the water outlet pipe are relatively fixed and sealed to the heat exchange cavity. The distance from the first end of the water inlet pipe to the furnace center of the DC submerged arc furnace is less than the distance from the first end of the water outlet pipe to the furnace center of the DC submerged arc furnace.

[0050] Among them, as an optional embodiment of the present invention, a first insertion hole and a second insertion hole are opened on the electrode end of the bottom electrode exposed outside the DC submerged arc furnace. Both the first insertion hole and the second insertion hole communicate with the heat exchange cavity. The first end of the water inlet pipe is inserted into the heat exchange cavity from the first insertion hole, and the first end of the water outlet pipe is inserted into the heat exchange cavity from the second insertion hole. The heat exchange cavity, the first insertion hole, and the second insertion hole are close to the end face of the electrode end of the bottom electrode of the DC submerged arc furnace exposed outside the DC submerged arc furnace; an installation opening is opened on the end face of the electrode end, and the installation opening communicates with the heat exchange cavity; the part of the water inlet pipe located in the heat exchange cavity is perpendicular to the part of the water outlet pipe located in the heat exchange cavity; the installation opening is sealed by a seal, and a tension hole is provided on the seal. One end of a tension member is fixedly connected to the part of the water inlet pipe located in the heat exchange cavity or the part of the water outlet pipe located in the heat exchange cavity, and the other end of the tension member passes through the tension hole and is fixed, so that the seal is relatively fixed to the part of the water inlet pipe located in the heat exchange cavity or the part of the water outlet pipe located in the heat exchange cavity, avoiding the heat exchange liquid in the heat exchange cavity from damaging the sealed connection between the seal and the installation opening on the end face of the electrode end.

[0051] A support frame is arranged in the heat exchange cavity. The part of the water outlet pipe located in the heat exchange cavity passes through the support frame, so as to use the support frame to support the part of the water outlet pipe located in the heat exchange cavity, and prevent the part of the water outlet pipe located in the heat exchange cavity from bending and shaking. The part of the water outlet pipe located in the heat exchange cavity points to the furnace center; one end of the tensioning member is fixedly connected to the part of the water inlet pipe located in the heat exchange cavity; a buffer hole is formed in the inner wall of the bottom electrode opposite to the water outlet of the part of the water inlet pipe located in the heat exchange cavity. The aperture of the buffer hole is larger than the outer diameter of the water inlet pipe, and the first end of the part of the water inlet pipe located in the heat exchange cavity is located in the buffer hole, so as to use the buffer hole to relieve the impact force of the heat exchange liquid, and make the heat exchange liquid entering the heat exchange cavity flow stably and directionally to the water drainage port of the water outlet pipe.

[0052] Step S803: Use the second end of the water inlet pipe to guide the heat exchange liquid conveyed by the first water pump to the water inlet pipe, and discharge it from the first end of the water inlet pipe into the heat exchange cavity, so as to use the heat exchange liquid to absorb the heat generated by the bottom electrode. The heat exchange liquid conveyed by the first water pump is provided by the cooling device.

[0053] Step S804: Use the first end of the water outlet pipe to guide the gradually heated heat exchange liquid into the water outlet pipe, and discharge it from the second end of the water outlet pipe to the cooling device.

[0054] In the embodiment of the present invention, a heat exchange cavity is opened inside the end of the electrode, and then the heat exchange liquid provided by the cooling device is pressurized by the first water pump and introduced into the heat exchange cavity through the water inlet pipe to cool the end of the electrode. The heat exchange liquid can directly contact the inside of the end of the electrode, so as to quickly take away the heat generated at the end of the electrode, with good cooling effect, effectively improving the cooling efficiency, ensuring the stable operation of the bottom electrode in a high-temperature environment, and prolonging the service life of the electrode. Further, since the heat exchange cavity is opened inside the end of the electrode and is not in the DC submerged arc furnace, the problem of molten iron penetration in the DC submerged arc furnace is avoided, and the safety and reliability of cooling the end of the electrode are improved. In addition, the distance from the first end of the water inlet pipe to the furnace center of the DC submerged arc furnace is less than the distance from the first end of the water outlet pipe to the furnace center of the DC submerged arc furnace. The heat exchange liquid can gradually flow from the end face of the electrode end to the bottom of the electrode end, sequentially exchanging heat with the area from the end face to the bottom of the electrode end, avoiding the direct contact between the heat exchange liquid and the bottom of the electrode end and vaporization, and further improving the cooling reliability and accuracy. Further, the water outlet pipe guides the gradually heated heat exchange liquid to the cooling device for recycling, improving the resource utilization rate.

[0055] It should be noted that the method for cooling the bottom electrode of the DC submerged arc furnace in the embodiment of the present invention and the DC submerged arc furnace in the above embodiment belong to the same inventive concept, and the same or similar parts can be referred to each other. The embodiment of the present invention will not be described in detail here.

[0056] Further, as an optional embodiment of the present invention, the cooling device includes a heat exchange liquid storage tank, a primary condensation tank, and a secondary condensation tank. Guiding the heat exchange liquid conveyed by the first water pump to the water inlet pipe through the second end of the water inlet pipe and discharging it from the first end of the water inlet pipe into the heat exchange cavity includes: obtaining the electrode temperature and the target electrode temperature at the electrode end of the bottom electrode of the DC submerged arc furnace, and determining the power of the first water pump, the first refrigeration intensity of the primary condensation tank, and the second refrigeration intensity of the secondary condensation tank according to the electrode temperature and the target electrode temperature. The target electrode temperature is the expected value of the electrode end; after pressurizing and pumping the coolant in the heat exchange liquid storage tank by the first water pump based on the power of the first water pump, it passes through the primary condensation tank and the secondary condensation tank in sequence, is cooled with the first refrigeration intensity and the second refrigeration intensity, and then is introduced into the heat exchange cavity through the water inlet pipe.

[0057] Specifically, in the embodiment of the present invention, the electrode temperature at the electrode end refers to the real-time temperature of the electrode end, and the target electrode temperature refers to the expected temperature of the electrode end, which can be determined according to the actual scenario and is not limited in the embodiment of the present invention. Among them, a temperature sensor is arranged at the electrode end in the embodiment of the present invention to monitor the real-time temperature of the electrode end in real time.

[0058] Further, the first water pump refers to the water pump located in the heat exchange liquid storage tank, which is used to pressurize the coolant in the heat exchange liquid storage tank and send it into the primary condensation tank and the secondary condensation tank. Among them, the first water pump has an adjustment coefficient, and under the action of the adjustment coefficient, the power of the first water pump can be adjusted in real time. Further, the primary condensation tank adopts a combination of air cooling and water cooling. First, the temperature of the coolant is initially reduced by air cooling to reduce the load of subsequent water cooling. The air-cooled part uses efficient heat sinks and fans, which can quickly take away part of the heat in the coolant. Then, the coolant enters the water-cooled part and exchanges heat with the circulating water to further reduce the temperature. The secondary condensation tank adopts a more refined refrigeration technology, such as compressor refrigeration, to accurately control the temperature of the coolant within the set range. The coolant cooled by two-stage condensation is introduced into the heat exchange cavity, circulates in the cavity, and fully absorbs the heat generated at the electrode end.

[0059] Further, as an optional embodiment of the present invention, determining the power of the first water pump, the first refrigeration intensity of the primary condensation box, and the second refrigeration intensity of the secondary condensation box according to the electrode temperature and the target electrode temperature includes: calculating the temperature difference between the electrode temperature and the target electrode temperature; obtaining the power coefficient and the basic power of the first water pump, the first refrigeration intensity coefficient and the first basic refrigeration intensity of the primary condensation box, and the second refrigeration intensity coefficient and the second basic refrigeration intensity of the secondary condensation box; calculating the first product between the power coefficient and the temperature difference, and determining the first sum value between the first product and the basic power as the power of the first water pump; calculating the second product between the first refrigeration intensity coefficient and the temperature difference, and determining the second sum value between the second product and the first basic refrigeration intensity as the first refrigeration intensity; calculating the third product between the second refrigeration intensity coefficient and the temperature difference, and determining the third sum value between the third product and the second basic refrigeration intensity as the second refrigeration intensity.

[0060] Specifically, the greater the difference between the electrode temperature and the target electrode temperature, the stronger the cooling capacity required, that is, the power of the first water pump, the first refrigeration intensity of the primary condensation box, and the second refrigeration intensity of the secondary condensation box are all greater. Therefore, there is a linear relationship among the above parameters. Based on this, the embodiments of the present invention specifically use the following formula to calculate the power of the first water pump, the first refrigeration intensity of the primary condensation box, and the second refrigeration intensity of the secondary condensation box:

[0061] P = P0 + k p ×ΔT

[0062] In the above formula, P represents the power of the first water pump. P0 represents the basic power of the first water pump. The basic power refers to the power of the first water pump when ΔT is equal to 0, and it can be determined according to empirical values. k p represents the power coefficient of the first water pump (unit: kW / °C), which represents the value that the power of the first water pump needs to increase for every 1°C increase in temperature, and it can be determined according to the actual scenario. The embodiments of the present invention do not limit it here. ΔT represents the temperature difference (unit: °C) between the electrode temperature and the target electrode temperature. Among them, ΔT = T - Ttarget, T is the electrode temperature (unit: °C), and Ttarget is the target electrode temperature (unit: °C).

[0063] C1 = C 10 + k C1 ×ΔT

[0064] In the above formula, C1 represents the first refrigeration intensity of the primary condensation box. C 10 represents the first basic refrigeration intensity (unit: kW). The first basic refrigeration intensity refers to the refrigeration intensity of the primary condensation box when ΔT is equal to 0, and it can be determined according to empirical values. k C1It represents the first refrigeration intensity coefficient (unit: kW / ℃). ΔT represents the temperature difference between the electrode temperature and the target electrode temperature.

[0065] C2 = C 20 + k C2 ×ΔT

[0066] In the above formula, C2 represents the second refrigeration intensity of the secondary condensation box. C 20 represents the second basic refrigeration intensity (unit: kW). The second basic refrigeration intensity refers to the refrigeration intensity of the secondary condensation box when ΔT is equal to 0, and it can be determined according to empirical values. k C2 represents the second refrigeration intensity coefficient (unit: kW / ℃). ΔT represents the temperature difference between the electrode temperature and the target electrode temperature.

[0067] It should be noted that k p 、k C1 and k C2 need to be determined according to the actual equipment performance and experimental data. These coefficients reflect the influence degree of temperature change on each equipment parameter. P0, C 10 and C 20 are the basic operating parameters when the temperature of the electrode end reaches the target electrode temperature, and they also need to be determined according to the actual situation. The specific values of the above parameters in the embodiments of the present invention are not limited.

[0068] In this way, the power of the first water pump, the first refrigeration intensity of the primary condensation box, and the second refrigeration intensity of the secondary condensation box are determined according to the electrode temperature and the target electrode temperature, so that the temperature and flow rate of the coolant entering the heat exchange chamber are more suitable for the real-time temperature scenario of the electrode end, accurately controlling the cooling temperature of the electrode end, ensuring that the electrode end is always in the optimal working temperature range, and further improving the cooling efficiency, reliability, and accuracy.

[0069] Further, as an optional embodiment of the present invention, after the coolant in the heat exchange liquid storage tank is pressurized and extracted by the first water pump based on the power of the first water pump, and then passes through the primary condensation box and the secondary condensation box in sequence for cooling with the first refrigeration intensity and the second refrigeration intensity and then enters the heat exchange chamber through the water inlet pipe, the method further includes: judging the change rate of the difference between the real-time electrode temperature and the target electrode temperature at the electrode end; if the change rate of the difference is less than the threshold value and the real-time electrode temperature at the electrode end has not reached the target electrode temperature, increasing the power of the first water pump and the power of the second water pump in the heat exchange chamber to accelerate the speed of the coolant entering the heat exchange chamber and the speed of the coolant discharging from the water outlet pipe until the real-time electrode temperature at the electrode end reaches the target electrode temperature, and the power of the second water pump is greater than the power of the first water pump.

[0070] Specifically, in the embodiments of the present invention, the rate of change of the difference between the electrode temperature and the target electrode temperature can be calculated in the following manner. Let the current time be t and the previous time be t - Δt. At time t, the electrode temperature is T(t), and the target electrode temperature is Target. Then the difference between the electrode temperature and the target electrode temperature is ΔT(t) = T(t) - Ttarget. At time t - Δt, the electrode temperature is T(t - Δt), and the difference is ΔT(t - Δt) = T(t - Δt) - Ttarget. The calculation formula for the rate of change v of the difference is:

[0071]

[0072] If the rate of change of the difference is less than the threshold and the real-time electrode temperature at the electrode end does not reach the target electrode temperature, it indicates that the current coolant cools the electrode end at a relatively slow speed. Therefore, in the embodiments of the present invention, the power of the first water pump and the second water pump can be adjusted to accelerate the flow rate of the coolant and quickly remove the temperature generated at the electrode end, improving the cooling efficiency. Accurately controlling the cooling temperature at the electrode end ensures that the electrode end is always within the optimal operating temperature range, further improving the cooling efficiency, reliability, and accuracy. Among them, the threshold can be determined according to the actual situation, and the embodiments of the present invention do not make any limitations in this regard.

[0073] Further, in order to accurately control the power of the first water pump and the second water pump in the heat exchange chamber, thereby improving the cooling accuracy and efficiency. As an optional embodiment of the present invention, if the rate of change of the difference is less than the threshold and the real-time electrode temperature at the electrode end does not reach the target electrode temperature, increasing the power of the first water pump and the second water pump in the heat exchange chamber includes: calculating the absolute value of the rate difference between the threshold and the rate of change; calculating the fourth product of the adjustment coefficient of the first water pump, the absolute value of the first difference, and the power of the first water pump; determining the sum value between the fourth product and the power of the first water pump as the power of the first water pump after the increase; determining the fifth product of the adjustment coefficient of the second water pump, the absolute value of the first difference, and the power of the second water pump; determining the sum value between the fifth product and the power of the second water pump as the power of the second water pump after the increase.

[0074] Specifically, the embodiments of the present invention specifically use the following formula to calculate the power of the first water pump after the increase:

[0075] P 1new (t) = P1(t) + k1 × |v0 - v| × P1(t)

[0076] In the above formula, P 1new(t) is the adjusted power of the first water pump. P1(t) is the current power of the first water pump. k1 is the adjustment coefficient of the first water pump. v0 is the threshold value. v is the change rate.

[0077] Furthermore, in the embodiments of the present invention, the following formula is specifically used to calculate the adjusted power of the second water pump:

[0078] P 2new (t) = P2(t) + k2 × |v0 - v| × P2(t)

[0079] In the above formula, P 2new (t) is the adjusted power of the second water pump. P2(t) is the current power of the second water pump. k2 is the adjustment coefficient of the second water pump. v0 is the threshold value. v is the change rate.

[0080] It should be noted that k1 and k2 are the adjustment coefficients of the first water pump and the second water pump respectively, which are used to control the amplitude of power increase. These coefficients can be determined according to the actual characteristics of the cooling system and experimental data, and are not limited in the embodiments of the present invention.

[0081] In this way, the embodiments of the present invention can accurately adjust the powers of the first water pump and the second water pump, thereby accelerating the flow rate of the coolant and quickly taking away the temperature generated at the electrode end, improving the cooling efficiency. And accurately control the cooling temperature at the electrode end to ensure that the electrode end is always in the optimal working temperature range, further improving the cooling efficiency, reliability and accuracy.

[0082] Furthermore, an exchange heat cavity is axially extended and opened inside the electrode end. The electrode end is a part of the bottom electrode of the DC submerged arc furnace that is exposed outside the DC submerged arc furnace. The open end of the exchange heat cavity is opened on the end face of the electrode end, which can enable the coolant to directly exchange heat with the inside of the electrode, effectively improving the cooling efficiency. The inner wall of the exchange heat cavity can be made of a material with high thermal conductivity, such as copper alloy, etc., to enhance the heat conduction performance. At the same time, the shape of the exchange heat cavity can be optimized according to the structure and heat distribution characteristics of the electrode. For example, a spiral or multi-channel structure can be adopted to make the coolant form a more uniform flow path in the cavity to ensure that all parts of the electrode end can be fully cooled.

[0083] Furthermore, during the installation of the bottom electrode of the DC submerged arc furnace, the exchange heat cavity is accurately opened at the electrode end according to the design requirements, and it is ensured that the inner wall of the exchange heat cavity is smooth and there is no leakage. The open end of the exchange heat cavity is hermetically connected to the inlet and outlet pipes of the coolant to prevent coolant leakage. Install equipment such as water pumps, primary condensation boxes, and secondary condensation boxes, and perform electrical connection and debugging. During the debugging process, check whether the circulation of the coolant is smooth and whether the operating parameters of each device are normal to ensure that the entire cooling system can operate stably.

[0084] Furthermore, the inner wall of the heat exchange chamber is made of a material with high thermal conductivity, and the shape of the heat exchange chamber is spiral or multi-channel structure, thereby accelerating the cooling efficiency of the electrode end.

[0085] Furthermore, as an optional embodiment of the present invention, based on the power of the first water pump, the coolant in the heat exchange liquid storage tank is pressurized and extracted by the first water pump and then passes through the primary condenser and the secondary condenser in sequence to be cooled at the first refrigeration intensity and the second refrigeration intensity and then introduced into the heat exchange chamber, including: based on the power of the first water pump, the coolant in the heat exchange liquid storage tank is pressurized and extracted by the first water pump and then enters the primary condenser for air cooling and water cooling at the first refrigeration intensity; controlling the coolant passing through the primary condenser to enter the secondary condenser for compression refrigeration at the second refrigeration intensity and then introduced into the heat exchange chamber.

[0086] Furthermore, as an optional embodiment of the present invention, the method further includes: controlling the coolant discharged from the heat exchange chamber through the outlet pipe to enter the heat recovery device, and the heat recovery device is used to recover part of the heat carried when the coolant is discharged; sending the heat recovered by the heat recovery device into the raw material preheating device of the DC submerged arc furnace for recycling; and sequentially introducing the coolant passing through the heat recovery device into the heat exchange liquid storage tank, the primary condenser and the secondary condenser for cooling circulation.

[0087] Specifically, in the embodiment of the present invention, the coolant discharged from the heat exchange chamber through the outlet pipe enters the heat recovery device. After the heat recovery device recovers part of the heat carried when the coolant is discharged, the collected heat is sent to the raw material preheating device for recycling. And the coolant passing through the heat recovery device is sequentially introduced into the heat exchange liquid storage tank, the primary condenser and the secondary condenser for cooling circulation, thereby realizing the efficient utilization of resources.

[0088] Furthermore, the material of the heat recovery device is made of heat-resistant and corrosion-resistant copper-nickel alloy or stainless steel (such as 316L stainless steel), with a thermal conductivity ≥ 15 W / (m·K) and a temperature resistance ≥ 500 °C. It includes a heat exchange main body and a hot and cold fluid channel. The heat exchange main body includes: a spiral coil heat exchanger: multiple layers of spiral coils are arranged inside the spiral coil heat exchanger, and fins are wrapped on the outer layer to increase the heat exchange area (fin pitch 5-10 mm, height 15-30 mm). A plate heat exchanger: composed of corrugated metal plates stacked together, the channel width between the plates is 3-5 mm, forming turbulent flow to enhance heat exchange. A heat pipe array: using gravity heat pipes, the length ratio of the evaporation section to the condensation section is 1:2, and the working medium is deionized water or heat-conducting oil. The hot and cold fluid channel includes a high-temperature side: connecting the outlet pipe of the heat exchange chamber, and the high-temperature coolant (60-90 °C) flows through the inside of the heat exchange main body. A low-temperature side: connecting the raw material preheating device, and the low-temperature fluid (20-40 °C) flows reversely outside the heat exchange main body and exchanges heat through the tube wall.

[0089] In addition, it further includes an electric control valve: installed at the low-temperature side inlet, it adjusts the flow rate of the low-temperature fluid according to the real-time temperature difference (adjustment range: 0 - 100%). Temperature sensors: arranged at the high-temperature side inlet, high-temperature side outlet, low-temperature side inlet, and low-temperature side outlet, with an accuracy of ±0.5°C.

[0090] The specific process of the energy recovery device is as follows: After the high-temperature coolant is discharged from the heat exchange chamber, it enters the high-temperature side channel of the heat recovery device. The low-temperature fluid flows reversely through the low-temperature side channel and exchanges heat with the high-temperature coolant. After the temperature of the high-temperature coolant decreases, it enters the heat exchange liquid storage tank, and the low-temperature fluid is heated and then output to the raw material preheating device, thereby realizing the repeated and efficient utilization of resources.

[0091] In the embodiment of the present invention, a heat exchange chamber is axially extended and opened inside the electrode end along the axial direction of the electrode end, and then the coolant cooled by the primary condensation tank and the secondary condensation tank is introduced into the heat exchange chamber to cool the electrode end. The coolant can directly contact the inside of the electrode end, thereby quickly taking away the heat generated by the electrode end, with a better cooling effect, effectively improving the cooling efficiency, ensuring the stable operation of the bottom electrode in a high-temperature environment, and prolonging the service life of the electrode. In addition, the power of the first water pump, the first refrigeration intensity of the primary condensation tank, and the second refrigeration intensity of the secondary condensation tank are determined according to the electrode temperature and the target electrode temperature, so that the temperature and flow rate of the coolant entering the heat exchange chamber are more suitable for the real-time temperature scenario of the electrode end, accurately controlling the cooling temperature of the electrode end, ensuring that the electrode end is always in the optimal working temperature range, and further improving the cooling efficiency, reliability, and accuracy. In addition, since the heat exchange chamber is opened inside the electrode end, the problem of the molten iron of the DC submerged arc furnace penetrating downward is avoided, further improving the safety and reliability of the cooling of the electrode end.

[0092] It should be noted that the DC submerged arc furnace provided by the embodiment of the present invention and the bottom electrode cooling method of the DC submerged arc furnace provided by the embodiment of the present invention are based on the same application concept. Therefore, the specific implementation of this embodiment can refer to the implementation of the aforementioned bottom electrode cooling method of the DC submerged arc furnace and has the same or similar beneficial effects. The repeated parts will not be elaborated.

[0093] It should be noted that: the above-mentioned sequence of the embodiments of the present invention is only for description and does not represent the superiority or inferiority of the embodiments. The processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be beneficial.

[0094] Each embodiment in this specification is described in a progressive manner. The same or similar parts between each embodiment can be referred to each other, and the key points of each embodiment are the differences from other embodiments.

Claims

1. A cooling method for the bottom electrode of a DC submerged arc furnace, characterized in that, Including: A heat exchange cavity is opened inside the bottom electrode of the DC submerged arc furnace, and the part of the bottom electrode with the heat exchange cavity serves as the electrode end and is not inside the DC submerged arc furnace; The first end of the water inlet pipe and the first end of the water outlet pipe are inserted into the heat exchange cavity, and the water inlet pipe and the water outlet pipe are relatively fixed and sealed to the heat exchange cavity. The distance from the first end of the water inlet pipe to the furnace center of the DC submerged arc furnace is less than the distance from the first end of the water outlet pipe to the furnace center of the DC submerged arc furnace; The heat exchange liquid conveyed by the first water pump is guided to the water inlet pipe through the second end of the water inlet pipe and discharged into the heat exchange cavity from the first end of the water inlet pipe, so as to use the heat exchange liquid to absorb the heat generated by the bottom electrode. The heat exchange liquid conveyed by the first water pump is provided by the cooling device; The gradually heated heat exchange liquid is guided into the water outlet pipe through the first end of the water outlet pipe and discharged to the cooling device from the second end of the water outlet pipe.

2. The bottom electrode cooling method of the DC submerged arc furnace according to claim 1, characterized in that A first insertion hole and a second insertion hole are opened on the electrode end of the bottom electrode exposed outside the DC submerged arc furnace. Both the first insertion hole and the second insertion hole communicate with the heat exchange cavity. The first end of the water inlet pipe is inserted into the heat exchange cavity through the first insertion hole, and the first end of the water outlet pipe is inserted into the heat exchange cavity through the second insertion hole.

3. The method for cooling the bottom electrode of a DC submerged arc furnace according to claim 2, characterized in that, The heat exchange cavity, the first insertion hole, and the second insertion hole are close to the end face of the electrode end of the bottom electrode of the DC submerged arc furnace exposed outside the DC submerged arc furnace; an installation opening is opened on the end face of the electrode end, and the installation opening communicates with the heat exchange cavity; The part of the water inlet pipe located in the heat exchange cavity is perpendicular to the part of the water outlet pipe located in the heat exchange cavity; the installation opening is sealed by a seal. The seal is provided with a tensioning hole. One end of the tensioning member is fixedly connected to the part of the water inlet pipe or the part of the water outlet pipe located in the heat exchange cavity. The other end of the tensioning member passes through the tensioning hole and is fixed, so that the seal is relatively fixed to the part of the water inlet pipe or the part of the water outlet pipe located in the heat exchange cavity, and to prevent the heat exchange liquid in the heat exchange cavity from damaging the sealed connection between the seal and the installation opening on the end face of the electrode end; A support frame is arranged in the heat exchange cavity. The part of the water outlet pipe located in the heat exchange cavity passes through the support frame to support the part of the water outlet pipe located in the heat exchange cavity by using the support frame, so as to prevent the part of the water outlet pipe located in the heat exchange cavity from bending and shaking; the part of the water outlet pipe located in the heat exchange cavity points to the furnace center; one end of the tensioning member is fixedly connected to the part of the water inlet pipe located in the heat exchange cavity; a buffer hole is opened on the inner wall of the bottom electrode opposite to the water outlet of the part of the water inlet pipe located in the heat exchange cavity. The diameter of the buffer hole is larger than the outer diameter of the water inlet pipe, and the first end of the part of the water inlet pipe located in the heat exchange cavity is located in the buffer hole, so as to use the buffer hole to relieve the impact force of the heat exchange liquid and make the heat exchange liquid entering the heat exchange cavity flow stably and directionally to the water drainage port of the water outlet pipe.

4. The method for cooling the bottom electrode of a DC submerged arc furnace according to claim 1, characterized in that, An insulating and heat-conducting coating is plated on the inner wall of the heat exchange cavity.

5. The bottom electrode cooling method of the DC submerged arc furnace according to claim 1, characterized in that, The cooling device includes a heat exchange liquid storage tank, a primary condensation tank, and a secondary condensation tank. The process of guiding the heat exchange liquid conveyed by the first water pump to the water inlet pipe through the second end of the water inlet pipe and discharging it from the first end of the water inlet pipe into the heat exchange cavity includes: Obtain the electrode temperature and the target electrode temperature at the end of the electrode, and determine the power of the first water pump, the first refrigeration intensity of the primary condensation tank, and the second refrigeration intensity of the secondary condensation tank based on the electrode temperature and the target electrode temperature. The target electrode temperature is the expected value at the end of the electrode. Based on the power of the first water pump, the coolant in the heat exchange liquid storage tank is pressurized and pumped by the first water pump, and then passes through the primary condensation tank and the secondary condensation tank in sequence, and is cooled with the first refrigeration intensity and the second refrigeration intensity, and then enters the heat exchange cavity through the water inlet pipe.

6. The method for cooling the bottom electrode of a DC submerged arc furnace according to claim 5, characterized in that, The process of determining the power of the first water pump, the first refrigeration intensity of the primary condensation tank, and the second refrigeration intensity of the secondary condensation tank based on the electrode temperature and the target electrode temperature includes: Calculate the temperature difference between the electrode temperature and the target electrode temperature. Obtain the power coefficient and the basic power of the first water pump, the first refrigeration intensity coefficient and the first basic refrigeration intensity of the primary condensation tank, the second refrigeration intensity coefficient and the second basic refrigeration intensity of the secondary condensation tank. Calculate the first product between the power coefficient and the temperature difference, and determine the first sum value between the first product and the basic power as the power of the first water pump. Calculate the second product between the first refrigeration intensity coefficient and the temperature difference, and determine the second sum value between the second product and the first basic refrigeration intensity as the first refrigeration intensity. Calculate the third product between the second refrigeration intensity coefficient and the temperature difference, and determine the third sum value between the third product and the second basic refrigeration intensity as the second refrigeration intensity.

7. The bottom electrode cooling method of the DC submerged arc furnace according to claim 5, characterized in that, After the coolant in the heat exchange liquid storage tank is pressurized and pumped by the first water pump based on the power of the first water pump, and then passes through the primary condensation tank and the secondary condensation tank in sequence, and is cooled with the first refrigeration intensity and the second refrigeration intensity, and then enters the heat exchange cavity through the water inlet pipe, the method further includes: Judge the change rate of the difference between the real-time electrode temperature at the end of the electrode and the target electrode temperature. If the change rate of the difference is less than the threshold value and the real-time electrode temperature at the end of the electrode has not reached the target electrode temperature, increase the power of the first water pump and the power of the second water pump in the heat exchange cavity to accelerate the speed of the coolant entering the heat exchange cavity and the speed of the coolant discharging from the water outlet pipe until the real-time electrode temperature at the end of the electrode reaches the target electrode temperature. The power of the second water pump is greater than the power of the first water pump. The process of increasing the power of the first water pump and the power of the second water pump in the heat exchange cavity if the change rate of the difference is less than the threshold value and the real-time electrode temperature at the end of the electrode has not reached the target electrode temperature includes: Calculate the absolute value of the rate difference between the threshold value and the change rate. Calculate a fourth product among the adjustment coefficient of the first water pump, the absolute value of the difference, and the power of the first water pump; Determine that the sum value between the fourth product and the power of the first water pump is the increased power of the first water pump; Calculate a fifth product among the adjustment coefficient of the second water pump, the absolute value of the difference, and the power of the second water pump; Determine that the sum value between the fifth product and the power of the second water pump is the increased power of the second water pump.

8. A DC submerged arc furnace, the DC submerged arc furnace comprising a bottom electrode, characterized in that: A heat exchange cavity is provided inside the bottom electrode, and the part of the bottom electrode with the heat exchange cavity serves as the electrode end and is not inside the DC submerged arc furnace; the DC submerged arc furnace further includes a water inlet pipe, a water outlet pipe, a first water pump, and a cooling device; The first end of the water inlet pipe and the first end of the water outlet pipe are inserted into the heat exchange cavity, and the water inlet pipe and the water outlet pipe are relatively fixed and sealed to the heat exchange cavity. The distance from the first end of the water inlet pipe to the furnace center of the DC submerged arc furnace is less than the distance from the first end of the water outlet pipe to the furnace center of the DC submerged arc furnace; The output port of the first water pump is connected to the second end of the water inlet pipe. The water inlet pipe discharges the heat exchange liquid conveyed by the first water pump into the heat exchange cavity to utilize the heat exchange liquid to absorb the heat generated by the bottom electrode. The cooling device is used to provide the first water pump with the cooled heat exchange liquid; The second end of the water outlet pipe is connected to the cooling device. The first end of the water outlet pipe guides the gradually heated pressure heat exchange liquid into the water outlet pipe, and the water outlet pipe guides the heated pressure heat exchange liquid to the cooling device, and the cooling device cools the heated pressure heat exchange liquid.

9. The DC submerged arc furnace according to claim 8, wherein: A first insertion hole and a second insertion hole are provided on the electrode end. Both the first insertion hole and the second insertion hole communicate with the heat exchange cavity. The first end of the water inlet pipe is inserted into the heat exchange cavity from the first insertion hole, and the first end of the water outlet pipe is inserted into the heat exchange cavity from the second insertion hole; the heat exchange cavity, the first insertion hole, and the second insertion hole are close to the end face of the electrode end of the bottom electrode of the DC submerged arc furnace exposed outside the DC submerged arc furnace; an installation opening is provided on the end face of the electrode end, and the installation opening communicates with the heat exchange cavity; The part of the water inlet pipe inside the heat exchange cavity is perpendicular to the part of the water outlet pipe inside the heat exchange cavity; the installation opening is sealed by a sealing member. The sealing member is provided with a tension hole. One end of a tension member is fixedly connected to the part of the water inlet pipe inside the heat exchange cavity or the part of the water outlet pipe inside the heat exchange cavity. The other end of the tension member passes through the tension hole and is fixed, so that the sealing member is relatively fixed to the part of the water inlet pipe inside the heat exchange cavity or the part of the water outlet pipe inside the heat exchange cavity, preventing the heat exchange liquid in the heat exchange cavity from damaging the sealed connection between the sealing member and the installation opening on the end face of the electrode end.

10. The DC submerged arc furnace according to claim 9, characterized in that, A support frame is arranged in the heat exchange cavity. The part of the water outlet pipe located in the heat exchange cavity passes through the support frame, so as to use the support frame to support the part of the water outlet pipe located in the heat exchange cavity, preventing the part of the water outlet pipe located in the heat exchange cavity from bending and shaking; the part of the water outlet pipe located in the heat exchange cavity points to the furnace center; one end of the tensioning member is fixedly connected to the part of the water inlet pipe located in the heat exchange cavity; a buffer hole is opened on the inner wall of the bottom electrode opposite to the water outlet of the part of the water inlet pipe located in the heat exchange cavity. The diameter of the buffer hole is larger than the outer diameter of the water inlet pipe, and the first end of the part of the water inlet pipe located in the heat exchange cavity is located in the buffer hole, so as to use the buffer hole to relieve the impact force of the heat exchange liquid, making the heat exchange liquid entering the heat exchange cavity flow stably and directionally to the water drainage port of the water outlet pipe.

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