Electric furnace waste heat recycling equipment

Abstract

The invention relates to the technical field of waste heat recovery, and discloses electric furnace waste heat recycling equipment which comprises a flue gas pipeline, one end of the flue gas pipeline is connected with an external electric furnace smoke outlet, and a heat exchange pipeline is arranged in the flue gas pipeline in a penetrating mode in the axial direction. The two ends of the heat exchange pipeline penetrate out of the smoke pipeline and then are connected with an external cooling medium circulation loop, a plurality of heat exchange parts are installed on the outer wall of the heat exchange pipeline, and each heat exchange part comprises a plurality of elastic heat exchange fins. Through cooperative action of the control assembly and the switching assembly, the elastic heat exchange fins are folded into a curved-surface sheath in the smelting stage, the curved-surface sheath is tightly attached to a heat exchange pipeline, a medium is made to be directly communicated at a high speed, heat insulation, dust accumulation prevention and oxidation prevention are achieved, and meanwhile rapid heat removal is achieved; in the heat preservation stage, the fins are unfolded into an umbrella shape, a medium flows through the branch pipelines around the fins, low-speed long-path sufficient heat exchange is achieved, the recovery efficiency is remarkably improved, and high-temperature protection and low-temperature high efficiency are both considered.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of waste heat recovery, in particular to a waste heat recovery and recycling equipment for electric furnace. BACKGROUND

[0002] Electric arc furnace, ladle refining furnace and other electric furnaces emit flue gas carrying a large amount of high-temperature sensible heat during smelting and refining process. If directly discharged into the atmosphere, it not only causes energy waste, but also aggravates the greenhouse effect and local thermal pollution. Therefore, the industry generally uses waste heat recovery devices to reuse this part of heat for preheating combustion-supporting air, heating process water or producing steam, which can significantly reduce electric furnace energy consumption, reduce fuel consumption and improve overall energy utilization efficiency, and is of great significance to achieving the goals of steel and non-ferrous industry.

[0003] However, the operating conditions of electric furnaces are not constant: for example, the operation of ferroalloy short hood electric furnace presents a two-state cycle of "smelting - holding", the flue gas temperature during smelting period is as high as 350-700℃, the flow rate is fast, and the dust content is high, while the flue gas temperature during holding period drops sharply to 300-450℃, the flow rate is slow, and the heat is thin, the existing fixed heat exchange channel cannot adjust the heat exchange area and flow channel structure in real time with the flue gas parameters, resulting in that the heat exchange is still efficient during smelting stage, but the heat exchange efficiency sharply decreases and the waste heat recovery amount sharply decreases during holding stage due to excessive area and low flow rate. SUMMARY

[0004] The present application aims to provide a waste heat recovery and recycling equipment for electric furnace to solve at least one technical problem existing in the prior art.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical scheme: a waste heat recovery and recycling equipment for electric furnace, comprising a flue gas pipeline, one end of the flue gas pipeline is connected with an external electric furnace smoke outlet, a heat exchange pipeline is arranged in the flue gas pipeline along the axial direction, and both ends of the heat exchange pipeline are connected with an external cooling medium circulation loop after penetrating out of the flue gas pipeline, a plurality of heat exchange parts are installed on the outer wall of the heat exchange pipeline, each heat exchange part comprises a plurality of elastic heat exchange fins, the elastic heat exchange fins are arranged in a ring array around the axis of the heat exchange pipeline and installed on the outer wall of the heat exchange pipeline, a plurality of branch pipelines are arranged on the outer wall of each elastic heat exchange fin, and both ends of each branch pipeline are connected with the inside of the heat exchange pipeline.

[0006] Further comprising a control assembly, the control assembly can control the expansion or contraction of the elastic heat exchange fins, and the elastic heat exchange fins are in a curved surface shape and wrapped around the outer periphery of the heat exchange pipeline when contracted;

[0007] Further comprising a switching assembly, the switching assembly can switch the flow path of the heat exchange medium in the heat exchange pipeline, so that the medium flows through the branch pipeline or directly flows through along the heat exchange pipeline.

[0008] Preferably, the control assembly comprises a fixed ring fixedly installed on the outer wall of the heat exchange pipeline, a plurality of rotating supports are rotatably installed on the outer wall of the fixed ring, an installation ring is fixedly installed on the outer wall of each rotating support, and the elastic heat exchange fins are hingedly connected between two adjacent installation rings at two ends thereof.

[0009] Preferably, the switching assembly comprises a first connecting pipeline with a tapered cavity inside, the heat exchange pipeline is sequentially and fixedly connected by a plurality of pipeline bodies through the first connecting pipeline, a slidable first sealing ball is arranged in the first connecting pipeline in a radial direction, and the first sealing ball is in sealing cooperation with the tapered cavity, when the first sealing ball moves to the small end of the tapered cavity, the heat exchange pipeline is cut off, and the two ends of the branch pipeline are in communication with the pipeline segments of the heat exchange pipeline on the two sides of the first sealing ball.

[0010] The switching assembly further comprises an opening and closing part capable of controlling the opening or closing of the branch pipeline.

[0011] Preferably, the opening and closing part comprises a second connecting pipeline, the branch pipeline is in communication with the inside of the heat exchange pipeline through the second connecting pipeline, the inner cavity of the second connecting pipeline is also arranged as a tapered cavity, a spring is fixedly installed on the inner wall of the side of the tapered cavity of the second connecting pipeline away from the heat exchange pipeline, and the other end of the spring is fixedly connected with a second sealing ball, when the second sealing ball moves to the small end of the spring tapered cavity, the branch pipeline is sealed.

[0012] Preferably, a screw rod is installed through the inside of the flue gas pipeline, the screw rod sequentially penetrates the outer walls of all the sliding rings and is threadedly connected with the penetration positions, an installation frame is fixedly installed on the outer wall of the flue gas pipeline, a driving gear is installed on the inner wall of the installation frame and can rotate, a driven gear is fixedly installed on the part of the screw rod penetrating out of the outer wall of the flue gas pipeline, and the driving gear is in meshing engagement with the driven gear.

[0013] Preferably, the thread pitches between the screw rod and each sliding ring are sequentially decreased.

[0014] Preferably, a first magnet is fixedly installed on the outer wall of the first sealing ball, a second magnet is fixedly installed inside the sliding ring, and the first magnet and the second magnet are opposite poles.

[0015] Preferably, metal corrugated pipes are adopted at the connection positions of the branch pipeline, the second connecting pipeline and the heat exchange pipeline.

[0016] Preferably, a heat insulation coating is arranged on the outer wall of the flue gas pipeline, and the heat insulation coating is a ceramic fiber composite coating.

[0017] Preferably, a temperature sensor is installed at the inlet of the flue gas pipeline.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] I. This invention, through the coordinated action of the control component and the switching component, enables the elastic heat exchange fins to retract into a curved sheath that tightly adheres to the heat exchange pipe during the melting stage, allowing the medium to flow through at high speed. This provides both heat insulation and prevents ash accumulation and oxidation, while simultaneously achieving rapid heat extraction. During the heat preservation stage, the fins expand into an umbrella shape, allowing the medium to flow through the branch pipes surrounding the fins. This low-speed, long-path heat exchange significantly improves the recovery efficiency, balancing high-temperature protection with low-temperature high efficiency.

[0020] II. This invention achieves a dynamic balance between heat transfer load and temperature difference along the flow path by gradually decreasing the screw pitch and sliding ring pitch along the flue gas direction: the pitch is large at the inlet end, and the fin angle is the largest, forming a high-enthalpy concentrated heat transfer zone at the front end, which quickly absorbs most of the heat; the pitch at the rear end gradually decreases, and the fins gradually retract, reducing the area to match the reduced flue gas enthalpy value. At the same time, the retracting channel induces secondary eddies to prolong the residence time and compensate for the temperature difference decrease. This results in a stable outlet flue gas temperature, avoids overheating at the front end and inefficiency at the rear end, and significantly improves the overall waste heat recovery rate and equipment energy efficiency. Attached Figure Description

[0021] Figure 1 This is the front view of the present invention;

[0022] Figure 2 This is a front sectional view of the present invention;

[0023] Figure 3 This is a cross-sectional view of the heat exchange section in this invention;

[0024] Figure 4 For the present invention Figure 3 Enlarged view of point A in the image;

[0025] Figure 5 This is a perspective view of the present invention after the flue gas duct has been removed;

[0026] Figure 6 For the present invention Figure 5 Enlarged view of point B in the image;

[0027] Figure 7 This is a schematic diagram of the second embodiment of the present invention;

[0028] Figure 8 This is a cross-sectional schematic diagram of the transmission gear and the driven gear in this invention.

[0029] In the figure: 1, flue gas pipeline; 2, heat exchange pipeline; 3, rotating support; 4, branch pipeline; 5, first connecting pipeline; 6, screw; 7, first closed ball; 8, fixed ring; 9, elastic heat exchange fin; 10, connecting support; 11, sliding ring; 12, first magnet; 13, second magnet; 14, second connecting pipeline; 15, second closed ball; 16, spring; 17, mounting ring; 18, mounting frame; 19, driving gear; 20, driven gear. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0031] Please refer to Figures 1 to 8 The present application provides a technical solution: a waste heat recovery and recycling equipment for electric furnace, comprising a flue gas pipeline 1, one end of the flue gas pipeline 1 is connected with an external electric furnace smoke outlet, a heat exchange pipeline 2 is axially arranged in the flue gas pipeline 1, and both ends of the heat exchange pipeline 2 are connected with an external cooling medium circulation loop after penetrating out of the flue gas pipeline 1, a plurality of heat exchange units are mounted on the outer wall of the heat exchange pipeline 2, each heat exchange unit comprises a plurality of elastic heat exchange fins 9, the elastic heat exchange fins 9 are arranged in a ring array around the axis of the heat exchange pipeline 2 and are mounted on the outer wall of the heat exchange pipeline 2, and the outer wall of each elastic heat exchange fin 9 is provided with a plurality of branch pipelines 4, and both ends of each branch pipeline 4 are connected with the inside of the heat exchange pipeline 2.

[0032] Further comprising a control assembly, the control assembly can control the elastic heat exchange fins 9 to expand or contract, and when the elastic heat exchange fins 9 contract, the elastic heat exchange fins 9 are curved and wrapped around the outer periphery of the heat exchange pipeline 2.

[0033] Further comprising a switching assembly, the switching assembly can switch the flow path of the heat exchange medium in the heat exchange pipeline 2, so that the medium flows through the branch pipeline 4 or directly flows through the heat exchange pipeline 2.

[0034] Please refer to Figure 1, the left side of the flue gas pipeline 1 is the inlet of the flue gas pipeline 1, and in the smelting stage, the flue gas of the electric furnace enters the inside of the flue gas pipeline 1 from the smoke inlet of the flue gas pipeline 1, at this time, under the action of the control assembly, the elastic heat exchange fin 9 is folded to wrap the outer wall of the heat exchange pipeline 2, under the action of the switching assembly, the heat exchange medium flows along the inside of the heat exchange pipeline 2, the folding of the elastic heat exchange fin 9 forms a heat-resistant "sheath" closely attached to the pipe wall, directly blocking the high-temperature flue gas from contacting the heat exchange pipeline 2 in a large area, reducing the surface heat load, preventing the material from softening or oxidizing, and prolonging the service life, and the small amount of heat absorbed is immediately transferred to the heat exchange medium in the heat exchange pipeline 2 through the contact surface, realizing "heat insulation + auxiliary heat conduction", under the action of high-temperature flue gas, the heat exchange medium in the heat exchange pipeline 2 will rapidly absorb heat and be at the upper limit temperature, the heat exchange medium can quickly exit the inside of the flue gas pipeline 1 through the heat exchange pipeline 2, so that the medium heated to the upper limit temperature quickly enters the external cooling medium circulation system, and the heat absorbed is recovered and reused, at the same time, the curved "sheath" after the folding of the elastic heat exchange fin 9 can protect the outer wall of the heat exchange pipeline 2, prevent dust from adhering to the surface of the heat exchange pipeline 2 when the flue gas flows, and reduce the heat resistance of the heat exchange pipeline 2 due to dust accumulation;

[0035] When the electric furnace enters the holding state, the flue gas temperature decreases, at this time, if the high-speed straight-flow heat exchange mode in the heat exchange pipeline 2 is still continued, the heat exchange efficiency will be greatly reduced (according to effective test data, the heat exchange efficiency can be reduced to less than 30% of the smelting stage), a large amount of low-temperature waste heat is directly discharged, causing heat waste. Therefore, at this time, the elastic heat exchange fin 9 is unfolded to form an umbrella shape through the control assembly, and at the same time, the flow path of the heat exchange medium is switched to flow through the branch pipeline 4 through the switching assembly, when the elastic heat exchange fin 9 is unfolded to form an umbrella shape, on the one hand, it will form a ring-shaped barrier in the flue gas pipeline 1, forcing the flue gas to slow down and prolong the residence time, to ensure that the flue gas and the heat exchange medium have enough time to complete heat exchange; on the other hand, the unfolded elastic heat exchange fin 9 not only absorbs low-temperature flue gas waste heat as a heating surface, but also rapidly conducts heat to the root and the outer wall of the heat exchange pipeline 2, which is finally taken away by the heat exchange medium in the heat exchange pipeline 2, realizing high-efficiency waste heat recovery in the holding stage, at the same time, the heat exchange medium flows in the heat exchange pipeline 2 and is divided into multiple branch pipelines 4, forming multiple parallel, spiral, and long flow channels, the total heat exchange area is greatly increased, and the medium flow rate is reduced, which fully exchanges heat with the low-temperature flue gas, greatly improving the heat exchange efficiency and the overall energy efficiency.

[0036] Thus, by the cooperation of the control assembly and the switching assembly, the elastic heat exchange fins 9 are folded into a curved sheath to tightly adhere to the heat exchange pipeline 2 in the smelting stage, and the medium is made to pass through at high speed, which not only insulates heat but also prevents dust and oxidation, and at the same time realizes rapid heat extraction; in the heat preservation stage, the fins are unfolded into an umbrella shape and the medium is made to flow through the branch pipeline 4 around the fins, and the low-speed long-path heat exchange is sufficient, the recovery efficiency is significantly improved, and high-temperature protection and low-temperature high efficiency are taken into account.

[0037] Further, the control assembly comprises a fixed ring 8 fixedly installed on the outer wall of the heat exchange pipeline 2, a plurality of rotating supports 3 are rotatably installed on the outer wall of the fixed ring 8, an installation ring 17 is fixedly installed on the outer wall of each rotating support 3, and the two ends of the elastic heat exchange fin 9 are respectively hinged between two adjacent installation rings 17. A slidable sliding ring 11 is installed on the outer wall of the heat exchange pipeline 2, and a connecting support 10 is rotatably installed on the outer wall of each rotating support 3. The other end of each connecting support 10 is rotatably connected with the sliding ring 11.

[0038] Referring to Figure 3 When it is needed to convert the state of the elastic heat exchange fin 9 to the unfolded state, the sliding ring 11 is driven by the external driving assembly to slide towards the direction close to the rotating support 3, at this time, under the action of the connecting support 10, the rotating support 3 is rotated towards the direction away from the heat exchange pipeline 2, so that the rotating support 3 drives the installation ring 17 to synchronously unfold, the distance between the adjacent installation rings 17 gradually increases, the elastic heat exchange fin 9 is lifted and unfolded outward to form an umbrella shape, and the whole forms a ring-shaped expansion surface. During the unfolding process, the curvature radius of the elastic heat exchange fin 9 gradually increases, and the contact area with the flue gas increases at the same time. At the same time, the connecting support 10 is always in a tension state, which ensures that the unfolding angle is consistent and there is no shaking. When the sliding ring 11 reaches the predetermined position, the elastic heat exchange fin 9 reaches the maximum opening angle and is self-locked by the connecting rod mechanism, and no continuous external force is needed to maintain the unfolded posture, and the quick, synchronous and stable conversion from folding to unfolding is completed.

[0039] Further, the switching assembly comprises a first connecting pipeline 5 with a tapered cavity inside, the heat exchange pipeline 2 is fixedly connected in sequence by a plurality of pipeline bodies through the first connecting pipeline 5, a slidable first sealing ball 7 is arranged in the first connecting pipeline 5 in the radial direction, and the first sealing ball 7 is in sealing cooperation with the tapered cavity. When the first sealing ball 7 slides to the small end of the tapered cavity, the heat exchange pipeline 2 is cut off, and the two ends of the branch pipeline 4 are respectively communicated with the pipeline segments of the heat exchange pipeline 2 on both sides of the first sealing ball 7.

[0040] The switching assembly further comprises an opening and closing part which can control the opening or closing of the branch pipeline 4.

[0041] Referring to Figure 3In the smelting stage, the first sealing ball 7 is located at the large end of the conical cavity of the first connecting pipe 5 by the external driving assembly, at this time, the maximum gap is kept between the first sealing ball 7 and the conical cavity wall of the first connecting pipe 5, the heat exchange pipe 2 keeps the full open state, the heat exchange medium flows along the heat exchange pipe 2 at high speed, quickly takes away the heat in the flue gas, realizes the rapid heat taking, and the opening and closing part ensures the closing of the branch pipe 4, cuts off the branch pipe 4, and prevents the medium short circuit;

[0042] In the holding stage, the first sealing ball 7 is located at the small end of the conical cavity of the first connecting pipe 5 by the external driving assembly, at this time, the first sealing ball 7 and the small end of the conical cavity of the first connecting pipe 5 form a metal-metal linear seal, cut off the inside of the heat exchange pipe 2, and make the branch pipe 4 open under the action of the opening and closing part, force the heat exchange medium to flow from the inside of the branch pipe 4, prolong the flow path of the heat exchange medium, and make the flue gas and the heat exchange medium have enough time to complete the heat exchange, as known from the above, at this time, the elastic heat exchange fin 9 is in the unfolded umbrella shape state, partially blocks the flow section of the flue gas pipe 1, forces the flue gas to slow down and prolong the residence time on the fin surface, and the fin quickly transfers the heat to the inside of the branch pipe 4 adjacent to it after absorbing the waste heat of the flue gas, realizes the high-efficiency heat exchange in the low-temperature stage.

[0043] Further, the opening and closing part includes a second connecting pipe 14, the branch pipe 4 is communicated with the inside of the heat exchange pipe 2 through the second connecting pipe 14, and the inner cavity of the second connecting pipe 14 is also provided as a conical cavity, a spring 16 is fixedly installed on the inner wall of the side of the conical cavity of the second connecting pipe 14 away from the heat exchange pipe 2, the other end of the spring 16 is fixedly connected with a second sealing ball 15, and when the second sealing ball 15 moves to the small end of the conical cavity of the spring 16, the branch pipe 4 is closed.

[0044] Referring to Figure 3 and Figure 4In the tapered cavity of the second connecting pipe 14, the spring 16 always exerts a pre-tightening force on the second sealing ball 15, which points to the small end, so that the ball keeps the closed state of the branch pipe 4 without external force. When the electric furnace switches to the holding stage, it is known from the above that the first sealing ball 7 is driven to move to the small end of the tapered cavity of the first connecting pipe 5, thereby gradually blocking the flowing medium in the heat exchange pipe 2. At this time, the medium in the heat exchange pipe 2 is subjected to the resistance of the first sealing ball 7, which gradually increases the force acting on the second sealing ball 15. When the force of the heat exchange medium acting on the second sealing ball 15 can overcome the elastic force of the spring 16, the second sealing ball 15 will be forced to move to the large end of the tapered cavity of the second connecting pipe 14, thereby unlocking the branch pipe 4 and making the branch pipe 4 communicate with the heat exchange pipe 2. When the first sealing ball 7 completely adheres to the inner wall of the small end of the first connecting pipe 5, the heat exchange medium in the heat exchange pipe 2 forces to flow from the branch pipe 4, thereby completing the switching of the flow path, and prolonging the flow path of the heat exchange medium, so that the flue gas and the heat exchange medium have enough time to complete the heat exchange.

[0045] Further, the screw rod 6 is installed through the inside of the flue gas pipe 1, the screw rod 6 successively penetrates the outer wall of all sliding rings 11 and is threadedly connected with the penetration, the flue gas pipe 1 is fixedly installed with a mounting frame 18 on the outer wall, a rotatable transmission gear 19 is installed on the inner wall of the mounting frame 18, and the part of the screw rod 6 that penetrates the outer wall of the flue gas pipe 1 is fixedly installed with a driven gear 20, and the transmission gear 19 is engaged with the driven gear 20.

[0046] Referring to Figure 2 , Figure 3 and Figure 8 , when it is necessary to move the sliding ring 11, the transmission gear 19 is driven to rotate by the motor fixed on the outer wall of the mounting frame 18, thereby driving the driven gear 20 to rotate, and further driving the screw rod 6 in the heat exchange pipe 2 to rotate, and further driving the sliding ring 11 to slide along the outside of the heat exchange pipe 2 through the threaded connection between the sliding ring 11 and the screw rod 6. When the sliding ring 11 slides axially, the corresponding rotating support 3 is synchronously pushed and pulled through the connecting support 10, thereby making the elastic heat exchange fins 9 complete the action of unfolding or folding. At the same time, the continuous rotation of the screw rod 6 keeps the sliding ring 11 precisely positioned at any position through the thread self-locking, without the need for additional braking. After the motor stops, the engagement angle of the transmission gear 19 and the driven gear 20 is less than five degrees, forming mechanical self-locking to prevent the sliding ring 11 from moving back due to the impact of flue gas. The entire drive chain is located outside the flue gas pipe 1, away from the high temperature area, and the service life and reliability of the motor are significantly improved.

[0047] Further, the thread pitch between the screw rod 6 and each sliding ring 11 decreases successively.

[0048] Referring to Figure 7In the heat preservation stage, if the temperature of the recovered flue gas is lower than the maximum recovery temperature of the recovery medium, such as the flue gas temperature is 200° and the upper limit of the heat exchange medium is 350°, when the flue gas flows from the inlet to the outlet, its temperature gradually decreases due to continuous heat release. If all the sliding rings 11 have the same pitch, the expansion angles of the elastic heat exchange fins 9 in each group are consistent, the heat exchange area of the front high-temperature zone is insufficient, and the area of the rear low-temperature zone is excessive, resulting in incomplete recovery of the front waste heat and the appearance of the "low-efficiency section" due to the reduction of temperature difference.

[0049] Therefore, on the basis of the above-mentioned embodiment, another embodiment is proposed, which is as follows:

[0050] By setting the pitch between the screw rod 6 and each sliding ring 11 to decrease in sequence along the flue gas flow direction, when the screw rod 6 rotates, the sliding ring 11 near the inlet will slide a farther distance, and thus the opening angle of the elastic heat exchange fin 9 will be larger, forming a front concentrated heat exchange zone. As the flue gas temperature decreases, the pitch decreases gradually, and the fin opening angle gradually closes. In this way, on the one hand, the largest heat exchange area is provided in the front high-enthalpy zone to rapidly absorb most of the heat, so that the flue gas temperature decreases to the medium-temperature zone as soon as possible; on the other hand, although the area of the rear end is reduced, the enthalpy value of the flue gas has been greatly reduced, and the required heat exchange amount is also reduced synchronously. At the same time, the closed fins form a tapered channel, inducing the flue gas to generate secondary vortex flow and prolonging the residence time, thereby compensating for the decrease in heat flux density caused by the reduction of temperature difference, realizing the dynamic matching of the heat exchange load and the available temperature difference along the way. Finally, the local heat exchange intensity of the entire heat exchange section tends to be balanced, the outlet flue gas temperature is stabilized at the set value, and the significant difference between "overheating at the front end and low efficiency at the rear end" is avoided, significantly improving the overall waste heat recovery rate and equipment energy efficiency.

[0051] Further, the first closed ball 7 is fixedly installed with a first magnet 12, and the sliding ring 11 is fixedly installed with a second magnet 13, and the first magnet 12 and the second magnet 13 are opposite poles.

[0052] Referring to Figure 3 , the second magnet 13 is embedded in the sliding ring 11, when the sliding ring 11 slides towards the first closed ball 7, the distance between the second magnet 13 and the first magnet 12 decreases, thereby increasing the magnetic force, so that the first magnet 12 drives the first closed ball 7 to move away from the small end of the first connecting pipeline 5, to complete the function of cutting off the heat exchange pipeline 2.

[0053] Among them, it is worth noting that because the second magnet 13 and the first magnet 12 are long-term exposed to high-temperature flue gas environment, the above-mentioned magnet is preferably a high-temperature resistant magnet, such as an aluminum-nickel-cobalt magnet, which can work at a temperature of 500-525 DEG C, and the Curie temperature is 860-900 DEG C, and the two magnets do not need to work during the smelting stage, and during the holding stage, the two magnets can return to the working temperature as the flue gas temperature drops, ensuring stability and being suitable for long-term exposure in high-temperature flue gas.

[0054] Further, the connection between the branch pipeline 4 and the second connecting pipeline 14 and the heat exchange pipeline 2 is made of a metal bellows.

[0055] Referring to Figure 4 When the rotating support 3 rotates, the branch pipeline 4 will be rotated, and the metal bellows can ensure the deformation of the branch pipeline 4 to a certain extent and ensure the sealing property.

[0056] Further, the outer wall of the flue gas pipeline 1 is provided with a heat insulation coating, which is a ceramic fiber composite coating.

[0057] The ceramic fiber composite heat insulation coating reduces the surface temperature of the outer wall of the flue gas pipeline 1 by more than 100 DEG C, significantly reduces heat loss and workshop heat radiation, reduces energy consumption and improves the working environment; at the same time, the coating is resistant to high temperature and thermal shock, can prevent oxidation and corrosion of the outer wall of the pipeline, prolong the service life and reduce the maintenance cost.

[0058] Further, a temperature sensor is installed at the inlet of the flue gas pipeline 1.

[0059] The temperature sensor arranged at the inlet of the flue gas pipeline 1 can monitor the temperature of the flue gas in real time, so as to transmit the signal to the motor, directly trigger the linkage of the control assembly and the switching assembly, realize the folding and unfolding of the elastic heat exchange fins 9 and the switching of the medium path, and avoid manual intervention.

[0060] The standard parts used in the embodiment can be directly purchased from the market, and the non-standard structural parts according to the description and the drawings can also be directly processed according to the existing technical knowledge without doubt, and the connection mode of each part adopts the mature conventional means in the existing technology, and the machinery, parts and equipment adopt the conventional type in the existing technology, so the specific description is not made here.

[0061] Although the embodiments of the present application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to the embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A waste heat recovery and reuse device for electric furnaces, comprising a flue gas duct (1), characterized in that: One end of the flue gas pipe (1) is connected to the flue gas outlet of the external electric furnace. A heat exchange pipe (2) is axially inserted inside the flue gas pipe (1). Both ends of the heat exchange pipe (2) are connected to the external cooling medium circulation loop after exiting the flue gas pipe (1). Multiple sets of heat exchange sections are installed on the outer wall of the heat exchange pipe (2). Each set of heat exchange sections includes several elastic heat exchange fins (9). The elastic heat exchange fins (9) are installed in a ring array on the outer wall of the heat exchange pipe (2) with the axis of the heat exchange pipe (2) as the center. Several branch pipes (4) are arranged around the outer wall of each elastic heat exchange fin (9). Both ends of each branch pipe (4) are connected to the inside of the heat exchange pipe (2). It also includes a control component, which can control the expansion or contraction of the elastic heat exchange fins (9). When contracted, the elastic heat exchange fins (9) are curved and cover the outer periphery of the heat exchange pipe (2). It also includes a switching component that can switch the flow path of the heat exchange medium in the heat exchange pipe (2) so that the medium flows through the branch pipe (4) or flows directly along the heat exchange pipe (2).

2. The electric furnace waste heat recovery and reuse equipment according to claim 1, characterized in that: The control assembly includes a fixed ring (8) fixedly installed on the outer wall of the heat exchange pipe (2). Several rotating brackets (3) are rotatably installed on the outer wall of the fixed ring (8). Each rotating bracket (3) is fixedly installed with an installation ring (17) on its outer wall. The two ends of the elastic heat exchange fins (9) are respectively hinged between two adjacent installation rings (17). A sliding ring (11) is installed on the outer wall of the heat exchange pipe (2). A connecting bracket (10) is rotatably installed on the outer wall of each rotating bracket (3). The other end of each connecting bracket (10) is rotatably connected to the sliding ring (11).

3. The electric furnace waste heat recovery and reuse equipment according to claim 2, characterized in that: The switching assembly includes a first connecting pipe (5) with an internal conical cavity. The heat exchange pipe (2) is formed by connecting multiple pipe sections end to end in sequence through the first connecting pipe (5). A first slidable sealing ball (7) is arranged radially inside the first connecting pipe (5), and the first sealing ball (7) is sealed to the conical cavity. When the first sealing ball (7) slides to the small end of the conical cavity, the heat exchange pipe (2) is cut off. The two ends of the branch pipe (4) are respectively connected to the heat exchange pipe (2) sections on both sides of the first sealing ball (7). The switching component also includes an opening and closing part, which can control the opening or closing of the branch pipe (4).

4. The electric furnace waste heat recovery and reuse equipment according to claim 3, characterized in that: The opening and closing part includes a second connecting pipe (14). The branch pipe (4) is connected to the heat exchange pipe (2) through the second connecting pipe (14). The inner cavity of the second connecting pipe (14) is also set as a conical cavity. A spring (16) is fixedly installed on the inner wall of the conical cavity of the second connecting pipe (14) away from the heat exchange pipe (2). The other end of the spring (16) is fixedly connected to a second closing ball (15). When the second closing ball (15) moves to the small end of the conical cavity of the spring (16), the branch pipe (4) is closed.

5. The electric furnace waste heat recovery and reuse equipment according to claim 4, characterized in that: A screw (6) is installed inside the flue gas duct (1). The screw (6) passes through the outer wall of all sliding rings (11) in sequence and is threaded to the penetration point. An installation frame (18) is fixedly installed on the outer wall of the flue gas duct (1). A rotatable transmission gear (19) is installed on the inner wall of the installation frame (18). A driven gear (20) is fixedly installed on the part of the screw (6) that passes through the outer wall of the flue gas duct (1). The transmission gear (19) meshes with the driven gear (20).

6. The electric furnace waste heat recovery and reuse equipment according to claim 5, characterized in that: The thread pitch between the screw (6) and each sliding ring (11) decreases sequentially.

7. The electric furnace waste heat recovery and reuse equipment according to claim 3, characterized in that: A first magnet (12) is fixedly installed on the outer wall of the first closed ball (7), and a second magnet (13) is fixedly installed inside the sliding ring (11), with the first magnet (12) and the second magnet (13) having the same pole facing each other.

8. The electric furnace waste heat recovery and reuse equipment according to claim 6, characterized in that: The connection points between the branch pipe (4) and the second connecting pipe (14) and the heat exchange pipe (2) are all made of metal corrugated pipe.

9. The electric furnace waste heat recovery and reuse equipment according to any one of claims 1-8, characterized in that: The outer wall of the flue gas duct (1) is provided with a heat insulation coating, which is a ceramic fiber composite coating.

10. The electric furnace waste heat recovery and reuse equipment according to any one of claims 1-8, characterized in that: A temperature sensor is installed at the inlet of the flue gas duct (1).

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