Pellet shaft furnace hot exhaust waste heat recycling equipment

Abstract

This invention discloses a waste heat recovery and utilization device for hot exhaust gas from a pelletizing vertical shaft furnace, belonging to the field of waste heat recovery technology. It includes a furnace body assembly and a separation roller module. The separation roller module contains two sets of mirror-arranged roller assemblies. The built-in flow guiding assembly in the roller shell includes a fluid main pipe, a return pipe, and a flow guiding cylinder fitted around the outer diameter of the return pipe. One end of the fluid main pipe is fixed to the furnace bottom, and the other end is rotatably assembled in the roller shell. The flow guiding cylinder limits the flow path of the heat transfer medium inside the roller shell. The narrow cavity formed by the flow guiding cylinder and the inner wall of the roller shell increases the medium flow velocity, and the high-speed jet forcibly peels off the wall bubbles, effectively suppressing film boiling, reducing high thermal resistance and alternating thermal stress. The baffle and the flow hole form a serpentine flow channel, which can generate turbulent disturbance, promote uniform circumferential temperature of the roller body, and prevent hot bending deformation. The coaxial sleeve structure enables the incoming low-temperature medium to form a thermal barrier to the returning high-temperature medium, significantly reducing heat radiation dissipation.

Description

Technical Field

[0001] This invention belongs to the field of waste heat recovery technology, specifically relating to a waste heat recovery and utilization device for hot exhaust gas from a pelletizing vertical furnace. Background Technology

[0002] The pelletizing vertical shaft furnace heat recovery equipment is a special thermal energy equipment system installed on the pelletizing vertical shaft furnace to capture and reuse the high-temperature waste heat in the production process, converting waste heat into high-quality energy that can be used for production or power generation.

[0003] Conventional cooling rollers in traditional furnace bottom unloading structures often employ simple straight-through flow channels. The heat transfer medium has a short residence time and a single flow path within the roller, resulting in insufficient heat exchange. Under high-temperature heat flux density, film boiling easily occurs on the inner wall of the roller, forming a vapor film with extremely high thermal resistance. This not only deteriorates heat transfer efficiency but also causes rapid temperature fluctuations and localized overheating of the roller, generating enormous alternating thermal stress. Ultimately, this leads to thermal fatigue cracking of the roller material and hot bending deformation of the axis.

[0004] Roller deformation can further exacerbate bearing wear due to uneven load and cause failure of the rotary seal structure, leading to leakage of high-temperature gas inside the furnace to the outside, which in turn damages the stability of the furnace. This results in a significant reduction in the energy efficiency of the waste heat recovery system after the seal fails, increasing maintenance costs and downtime losses. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide a waste heat recovery and utilization device for pelletizing vertical shaft furnace hot exhaust gas, thereby solving the problems mentioned in the background technology.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A waste heat recovery and utilization device for hot exhaust gas from a pelletizing vertical furnace includes a separation roller module. Several separation roller modules are spaced apart on the bottom side of the furnace body assembly to support the material column inside the vertical furnace and to crush the material column on the contact surface. Each separation roller module includes two sets of roller body assemblies, which are arranged in a mirror image. The roller assembly includes a roller shell, concave surfaces, and crushing teeth. The roller shell is rotatably disposed in the furnace assembly, and the outer surface of the roller shell is provided with a plurality of concave surfaces and crushing teeth. The flow guiding assembly includes a fluid main pipe, a return pipe, and a flow guiding cylinder. One end of the fluid main pipe is fixedly installed in the furnace body assembly, and the other end of the fluid main pipe is rotatably assembled in the roller shell. The return pipe is connected to the fluid main pipe, and the outer diameter end of the return pipe is also fitted with a flow guiding cylinder. The flow guiding cylinder is used to limit the flow path of the heat transfer medium inside the roller shell.

[0007] As a further embodiment of the present invention, the furnace body assembly includes a furnace base, a material guiding chamber, a cooling chamber, a roasting chamber, a drying chamber, and a feeding chamber. The furnace base, the material guiding chamber, the cooling chamber, the roasting chamber, the drying chamber, and the feeding chamber have equal and interconnected inner cavities in the vertical direction. A shuttle-type stacking machine is also provided in the feeding chamber for stacking pellet columns.

[0008] As a further embodiment of the present invention, the roller assembly further includes a perforated plate, an internal shaft seal, an external shaft seal, a rotating shaft, and a transmission wheel. The perforated plate is locked and fixed in the inner cavity of the roller housing. The internal shaft seal is limited and locked at one end of the roller housing, and the external shaft seal is limited and locked at one side of the internal shaft seal. A rotating shaft is provided on the outer diameter side of the external shaft seal. The rotating shaft is rotatably mounted on the wall of the furnace base, and the transmission wheel is limited and locked at one side of the rotating shaft.

[0009] As a further embodiment of the present invention, the roller assembly further includes an inlet pipe and a guide hole. The inlet pipe is arranged at one end of the fluid main pipe and is independent of the return pipe. The fluid main pipe is coaxially rotatably installed in the external shaft seal and the transmission wheel. A guide hole is provided on the side of the fluid main pipe facing the inner cavity of the roller shell. The inlet pipe and the guide hole are connected to each other for inputting a heat-conducting medium into the inner cavity of the roller shell.

[0010] As a further embodiment of the present invention, the outer diameter of the guide tube is smaller than the inner diameter of the roller shell; the outer diameter of the guide tube is provided with a plurality of rings arranged in an array along the axial direction, and the rings and the roller shell are spaced apart.

[0011] As a further embodiment of the present invention, a plurality of baffles are arranged in an array along the axial direction inside the guide tube, and the baffles divide the inner cavity of the guide tube into a plurality of independent cavities; the ring body and the baffles are staggered along the axial direction of the guide tube.

[0012] As a further embodiment of the present invention, the flow guiding component further includes flow passages and spiral grooves. Several spiral grooves are respectively arranged in several cavities inside the flow guiding cylinder to divide the cavities into two interconnected curved cavities. The flow passages are arranged in a circumferential array at the outer diameter end of the flow guiding cylinder and are distributed on the sides of the two sets of curved cavities.

[0013] In summary, the embodiments of the present invention have the following beneficial effects compared with the prior art: This device significantly increases the flow rate of the heat transfer medium through the narrow cavity formed by the guide tube and the inner wall of the roller shell, based on Bernoulli's principle. The high-speed flowing fluid generates strong impact and shearing force on the steam bubbles attached to the high-temperature inner wall, forcing the bubbles to detach from the metal surface. This effectively blocks the formation of a continuous steam film, reduces the extremely high thermal resistance caused by film boiling, avoids the sudden rise in roller temperature and alternating thermal stress caused by heat accumulation, and ensures that the roller is maintained in the efficient nucleation boiling heat transfer range. Furthermore, the inner cavity of the guide tube is divided into multiple independent cavities by an array of baffles, and with the circumferentially arranged flow holes, it is configured as a serpentine flow path. When the heat transfer medium flows inside the roller, it needs to constantly change direction and pass through different areas, forming a strong turbulence and swirling effect. This causes the heat in the high-temperature area to be quickly carried away and dispersed to the low-temperature area, making the temperature of the roller uniform in the circumferential direction and effectively suppressing the thermal bending deformation caused by uneven circumferential heating. Furthermore, the fluid main pipe adopts a coaxial sleeve structure, with the inlet pipe surrounding the outside of the return pipe. This allows the incoming low-temperature medium to form a dynamic thermal barrier on the returning high-temperature medium that has completed heat exchange. By absorbing the radial heat radiation outward from the return pipe, the heat dissipation of the high-temperature medium during the return process is significantly reduced, thus realizing the cascade utilization of thermal energy. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of a vertical furnace in one embodiment of the present invention.

[0015] Figure 2 This is a partial cross-sectional view of a vertical furnace in one embodiment of the present invention.

[0016] Figure 3 This is a schematic diagram of the front structure of a vertical furnace in one embodiment of the present invention.

[0017] Figure 4 This is a schematic diagram of the structure of the roller assembly in one embodiment of the present invention.

[0018] Figure 5 This is a partial cross-sectional view of the roller assembly in one embodiment of the present invention.

[0019] Figure 6 for Figure 5 Enlarged schematic diagram of reference numeral A in the attached figure.

[0020] Figure 7 This is a schematic diagram of the assembly of the roller assembly in one embodiment of the present invention.

[0021] Figure 8 This is a partial cross-sectional view of the flow guiding component in one embodiment of the present invention.

[0022] Figure 9 This is a front structural diagram of the flow guiding component in one embodiment of the present invention.

[0023] Figure 10 This is a schematic diagram showing the flow direction of the heat-conducting medium in one embodiment of the present invention.

[0024] Figure label: 1-Furnace body assembly, 101-Furnace base, 102-Feeding chamber, 103-Cooling chamber, 104-Roasting chamber, 105-Drying chamber, 106-Feeding chamber, 107-Shuttle-type feeder; Spray assembly, 201-Tower set, 202-Spray pipe, 203-Flue gas main pipe; Roller assembly, 301-roller shell, 302-concave surface, 303-crushing tooth, 304-perforated plate, 305-internal shaft seal, 306-external shaft seal, 307-rotating shaft, 308-transmission wheel, 309-limiting cylinder; Flow guiding assembly, 401-fluid main pipe, 402-return pipe, 403-inlet pipe, 404-flow guiding hole, 405-flow guiding cylinder, 406-ring body, 407-flow passage hole, 408-baffle, 409-spiral groove, 410-return groove hole; a1 - First cavity, a2 - Second cavity, a3 - Third cavity. Detailed Implementation

[0025] To more clearly illustrate the structural features and effects of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] Please see Figures 1-10 According to one embodiment of the present invention, a waste heat recovery and utilization device for pelletizing vertical shaft furnace includes a separation roller module. Several separation roller modules are spaced apart on the bottom side of the furnace body assembly 1 to support the material column inside the vertical shaft furnace and to crush the material column on the contact surface. Each separation roller module includes two sets of roller body assemblies 3, which are arranged in a mirror image. Each roller body assembly 3 includes a roller shell 301, a concave surface 302, and crushing teeth 303. The roller shell 301 is rotatably disposed within the furnace body assembly 1, and its outer surface is provided with… It has several concave surfaces 302 and breaking teeth 303; the flow guiding assembly 4 includes a fluid main pipe 401, a return pipe 402 and a flow guiding cylinder 405. One end of the fluid main pipe 401 is fixedly installed in the furnace body assembly 1, and the other end of the fluid main pipe 401 is rotatably assembled in the roller shell 301. The return pipe 402 is connected to the fluid main pipe 401, and the outer diameter end of the return pipe 402 is also fitted with a flow guiding cylinder 405. The flow guiding cylinder 405 is used to limit the flow path of the heat transfer medium inside the roller shell 301.

[0027] In practical application, the core waste heat recovery structure of the pellet vertical furnace waste gas recovery and utilization equipment adopts a separation roller module design. Multiple separation roller modules are arranged in a matrix with row and column spacing and installed in the bottom area of ​​the inner cavity of the furnace body component 1 to form the furnace bottom support and unloading platform. During the continuous operation of the vertical furnace, the pellets that have been roasted in the upper part continue to sink under the action of gravity, forming a material column with a certain accumulation height. The bottom of the material column is in direct contact with the surface of the rotating separation roller module.

[0028] The core execution unit of each separating roller module is the roller assembly 3. This assembly rotates in a directional manner under the drive of an external drive source. Considering the pressure of tens of tons exerted by the material column on the bottom roller surface, the external drive source preferably adopts a hydraulic transmission system, utilizing its low-speed, high-torque and overload protection characteristics to ensure the reliability of the rotation operation. The roller assembly 3 is mainly composed of a roller shell 301, whose outer circumferential surface is reinforced and has specific crushing teeth 303 distributed on it. When the roller rotates, these crushing teeth 303 first cut into and contact the bottom of the material column, applying force to the sintered pellets. The shearing and splitting action not only crushes the material but also continuously disrupts the arched support structure that may form at the bottom of the material column. This effectively intervenes in the arched structure, preventing material from being obstructed or suspended due to arching. It also promotes the formation of uniformly sized small pieces of pellets after crushing, which are then discharged in an orderly manner from the gap between adjacent separation roller modules. The surface of the roller shell 301 has a concave arc-shaped area between adjacent crushing teeth 303. This concave structure increases the instantaneous contact area with the crushed pellet fragments, which helps guide the fragments to move into the gap between the rollers and improves the discharge efficiency.

[0029] While the separating roller module performs crushing and unloading functions, the internal flow guiding component 4 simultaneously recovers heat energy. The flow guiding component 4 is responsible for introducing a low-temperature heat transfer medium, such as cooling water, which is most commonly used in industrial applications, into the internal cavity of the roller shell 301. Since the temperature of the pellets sinking from the roasting area is usually as high as several hundred degrees Celsius, the outer wall of the roller shell 301 accumulates a large amount of heat energy in the process of directly contacting the high-temperature material. According to the principle of heat conduction, the heat is rapidly transferred inward through the metal wall and undergoes a violent heat exchange with the cooling water in the roller cavity. The cooling water absorbs the heat of the roller body, which not only reduces the overall working temperature of the roller assembly 3 and prevents it from becoming weak or damaged due to overheating, but also causes the cooling water itself to rise rapidly. After reaching the boiling point, some of it undergoes a phase change to produce steam, forming a steam-water mixture in the roller cavity.

[0030] Driven by pressure difference or circulation power, the steam-water mixture travels along a specific flow channel inside the guide tube 405 in the guide assembly 4. The inner flow channel of the guide tube 405 is designed in a serpentine and spiral shape, which forces the steam-water mixture to continuously change direction during the flow process, generating turbulence and churning effects. Through forced disturbance, it promotes uniform mixing of the liquid and gas phases, enhances the internal convective heat transfer coefficient, and suppresses the generation of local film boiling, thereby improving the overall heat transfer efficiency.

[0031] Due to the asymmetrical circumferential heating conditions of the separating roller module during operation, the upper arc surface of the roller body continuously contacts the high-temperature material column and absorbs heat, while the lower arc surface is exposed to the bottom of the furnace body and only contacts the air and falling cold material. During low-speed rotation, a large temperature gradient exists along the circumference of the roller body. The continuous circulation of the steam-water mixture guided by the guide tube 405 within the roller cavity can rapidly carry heat away from the high-temperature area and dissipate it to the low-temperature area, thus balancing the temperature field of the roller body. This significantly reduces the thermal stress caused by uneven circumferential heating, effectively preventing hot bending deformation of the roller body axis and avoiding shaft deformation. This, on the one hand, ensures... The rotational accuracy of the roller assembly 3 is crucial to prevent interference with adjacent modules or the furnace structure due to deformation deviations, ensuring unobstructed discharge channels. On the other hand, it avoids bearing overload caused by shaft deformation, thereby preventing abnormal wear, local overheating, or jamming failure of the bearings. Maintaining the straightness of the roller axis ensures the rotational sealing at the shaft penetration point. If the shaft deforms, it will directly damage the sealing state, leading to sealing structure failure. This will cause gas leakage between the precisely controlled high-temperature roasting atmosphere inside the vertical furnace and the external environment, ultimately affecting the stability of the thermal regime inside the vertical furnace and the roasting quality of the pellets.

[0032] Please see Figure 3 In a preferred embodiment of the present invention, the furnace body assembly 1 includes a furnace base 101, a material guiding chamber 102, a cooling chamber 103, a roasting chamber 104, a drying chamber 105, and a feeding chamber 106. The furnace base 101, the material guiding chamber 102, the cooling chamber 103, the roasting chamber 104, the drying chamber 105, and the feeding chamber 106 have equal and interconnected inner cavities in the vertical direction. A shuttle-type distribution machine 107 is also arranged in the feeding chamber 106 for stacking pellet columns. A spray assembly 2 is also assembled on the top of the feeding chamber 106. The spray assembly 2 includes a tower 201, a spray pipe 202, and a flue gas main duct 203.

[0033] In practical application, the furnace base 101 is sequentially equipped with a guiding chamber 102, a cooling chamber 103, a roasting chamber 104, a drying chamber 105, and a feeding chamber 106. The guiding chamber 102, cooling chamber 103, roasting chamber 104, drying chamber 105, and feeding chamber 106 all employ a composite layer structure. The outer layer is composed of a 6-8 mm thick metal plate to provide structural strength and airtightness. The inner layer uses an ablation-resistant material to withstand the thermal shock and chemical erosion of the high-temperature airflow and materials. The middle layer is filled with high-efficiency insulation material to reduce heat loss and improve thermal energy utilization efficiency. The guiding chamber 102 receives the pelletized material processed by the drying chamber 105 and guides the material orderly to the furnace base through its internal flow channel structure. The discharge port of 101 enables smooth unloading. The cooling chamber 103, located downstream of the roasting chamber, is used to force-cool the high-temperature pellets after roasting. By introducing ambient air or circulating cold air, the temperature of the pellets drops rapidly to meet the requirements of subsequent conveying and storage processes. The roasting chamber 104 is the core reaction zone of this process. An independent combustion chamber is installed outside it. The hot flue gas generated in the combustion chamber enters the roasting chamber through the distribution channel to exchange heat with the pellets, achieving high-temperature consolidation and roasting enhancement of the pellets. The drying chamber 105 is arranged adjacent to the roasting chamber. It uses the waste heat of the high-temperature flue gas discharged from the roasting section to preheat and dehydrate the green pellets entering the system, thereby reducing overall energy consumption and preventing the green pellets from cracking due to rapid temperature rise.

[0034] The feeding chamber 106 serves as the material inlet unit, and a shuttle cloth feeder 107 is installed inside it. This cloth feeder achieves uniform stacking and quantitative distribution of pellet raw materials in the cross section of the feeding section through reciprocating motion, ensuring the uniformity of the material layer structure in the subsequent process chambers.

[0035] Please see Figure 6 In a preferred embodiment of the present invention, the roller assembly 3 further includes a perforated plate 304, an internal shaft seal 305, an external shaft seal 306, a rotating shaft 307, and a transmission wheel 308. The perforated plate 304 is locked and fixed in the inner cavity of the roller housing 301. The internal shaft seal 305 is limited and locked at one end of the roller housing 301, and the external shaft seal 306 is limited and locked at one side of the internal shaft seal 305. A rotating shaft 307 is provided on the outer diameter side of the external shaft seal 306. The rotating shaft 307 is rotatably mounted on the wall of the furnace base 101, and the transmission wheel 308 is limited and locked at one side of the rotating shaft 307.

[0036] In practical application, the built-in shaft seal 305 is connected to one end of the roll housing 301 via its flange end face, and a high-strength bolt group is used to apply preload to achieve a rigid locking connection between the two. Simultaneously, a radial static seal is formed at the mating surface to ensure the sealing of the end of the roll housing 301. The external shaft seal 306 engages with the outer circular boss of one end of the built-in shaft seal 305 via its inner hole stop, and is secured with bolts to form a locking structure. The side of the external shaft seal 306 opposite to the built-in shaft seal 305 extends to form a support neck. A high-precision rolling bearing or sliding bearing is fitted between the inner hole of the support neck and the outer circular surface of the rotating shaft 307. The rotating shaft 307 is supported by this bearing and passes through the side wall plate of the furnace base 101. Its extended end is fixed to the wall plate by a bearing seat or end cover to realize the fixed-axis rotation function of the roller shell 301 relative to the furnace base 101. The drive wheel 308 is coaxially installed at one end of the rotating shaft body 307 outside the external shaft seal body 306. The drive wheel 308 preferably adopts a spline or flat key structure to realize torque transmission with the rotating shaft body 307 and is axially limited by a locking nut. The drive wheel 308 meshes with the output end of the external hydraulic drive unit. When the hydraulic drive unit is started, the rotational torque is transmitted to the rotating shaft body 307 through the drive wheel 308, thereby driving the built-in shaft seal body 305 and the roller shell 301 rigidly connected to it to perform directional reciprocating rotation or continuous rotation around its central axis to realize precise angle adjustment of the roller body.

[0037] Please see Figure 5 and Figure 6 In a preferred embodiment of this embodiment, the roller assembly 3 further includes an inlet pipe 403 and a guide hole 404. The inlet pipe 403 is disposed at one end of the fluid main pipe 401 and is independent of the return pipe 402. The fluid main pipe 401 is coaxially rotatably installed in the external shaft seal 306 and the transmission wheel 308, and the guide hole 404 is provided on the side of the fluid main pipe 401 facing the inner cavity of the roller housing 301. The inlet pipe 403 and the guide hole 404 are connected to each other for inputting heat transfer medium into the inner cavity of the roller housing 301.

[0038] In practical application, the fluid main pipe 401 contains two sets of fluid passages. The main pipe adopts a coaxial sleeve structure. The return pipe 402 forms a central flow channel for exporting the heat-conducting medium that has completed heat exchange from the roller shell 301. The inlet pipe 403 forms an annular flow channel for supplying the heat-conducting medium with regulated temperature to the roller shell 301. The fluid passage where the inlet pipe 403 is located adopts an annular flow channel structure and is arranged around the circumferential outer side of the return pipe 402. Through the nested arrangement of inner and outer pipes, the low-temperature medium in the inlet pipe 403 can form an effective thermal barrier for the high-temperature medium in the return pipe 402. By absorbing the radial heat radiation outward from the return pipe 402, the residual heat dissipation loss of the heat-conducting medium in the return pipe 402 during the return process is significantly reduced.

[0039] In one embodiment, a limiting cylinder 309 is coaxially mounted on the other end of the roller housing 301. The limiting cylinder 309 forms a precise positioning rotational fit with the return pipe 402 through its inner hole. The inner wall of the limiting cylinder 309 and the outer wall of the return pipe 402 are fitted with a clearance fit and form a rotational support structure in the circumferential direction, which effectively constrains the radial runout of the return pipe 402 and ensures that the return pipe 402 and the roller housing 301 maintain a high degree of coaxiality during dynamic rotation, thereby reducing load vibration caused by axial deviation.

[0040] Please see Figure 9 In a preferred embodiment of the present invention, the outer diameter of the guide tube 405 is smaller than the inner diameter of the roller shell 301, and a plurality of rings 406 are arranged in an array along the axial direction on the outer diameter of the guide tube 405, with the rings 406 and the roller shell 301 spaced apart.

[0041] In practical application, the outer diameter of the guide tube 405 is smaller than the inner diameter of the roller shell 301, forming an annular gap between them. Several annular flanges are distributed axially on the outer wall of the guide tube 405. The outer diameter of each ring 406 and the inner diameter of the roller shell 301 are connected by a clearance fit to form a sealing structure. This sealing structure can effectively prevent the heat transfer medium from flowing between the channels. There is a small assembly gap between the ring 406 and the inner wall of the roller shell 301. In actual operation, the flow rate of heat transfer medium leaking through this gap is extremely limited, and the effect of this magnitude on the overall heat exchange efficiency and temperature field distribution is negligible.

[0042] Furthermore, the guide tube 405 is internally arranged with several baffles 408 along the axial direction, which divide the inner cavity of the guide tube 405 into several independent cavities. The annular body 406 and the baffles 408 are staggered along the axial direction of the guide tube 405. The roller shell 301 is internally arranged with interconnected first cavities a1, second cavities a2, and third cavities a3 along the axial direction. The first cavity a1 is configured as a cavity structure adjacent to the orifice plate 304, used to receive the heat transfer medium introduced by the orifice plate 304. The second cavity a2 is configured as an annular gap channel formed between the outer wall of the guide tube 405 and the inner wall of the roller shell 301. This channel extends along the axial direction of the roller body and constitutes the flow path of the heat transfer medium. The third cavity a3 is configured as a cavity structure adjacent to the end of the return pipe 402, used to collect the heat transfer medium flowing through the heat exchange area. The guide tube 405 has a cylindrical structure. The heat transfer medium is axially arranged between the first cavity a1 and the third cavity a3. Its outer wall and the inner wall of the roller housing 301 form the second cavity a2. The guide tube 405 is used to separate and guide the heat transfer medium through multiple continuously arranged second cavity a2 sections, thereby extending the flow path of the heat transfer medium inside the roller body, so that it enters the third cavity a3 after flowing through multiple annular gap areas, achieving sufficient heat exchange. The return pipe 402 extends axially, with one end adjacent to the third cavity a3. A return groove hole 410 is opened on the pipe wall near the third cavity a3. The return groove hole 410 is a long strip-shaped groove structure, used to guide the heat transfer medium collected in the third cavity a3 into the interior of the return pipe 402. After completing the heat exchange, the heat transfer medium enters the return pipe 402 through the return groove hole 410 and is discharged outward through the inner cavity channel of the return pipe 402, forming a complete heat transfer medium circulation path.

[0043] Because the temperature of the inner wall of the roller exceeds the saturation temperature of water under the corresponding pressure, the liquid water in close contact with the heated wall vaporizes, forming discrete vaporization nuclei and generating tiny bubbles. As the heat flux density continues to increase, the superheat of the wall increases, and the bubble generation rate increases sharply. When the nucleation and growth rate of the bubbles exceeds the critical rate at which they detach from the wall, the bubbles remain on the wall in large numbers and merge and grow, eventually forming a continuous gaseous isolation layer. Furthermore, when the bubbles completely converge to form a stable continuous vapor film covering the heating surface, the heat transfer mechanism transitions from nucleation boiling to film boiling. At this time, the inner wall surface of the roller is completely covered by a stable vapor film. Since the thermal conductivity of vapor (approximately 0.06 W / m·K at normal pressure saturation temperature) is an order of magnitude lower than that of liquid water (approximately 0.6 W / m·K), its thermal resistance increases significantly. After the heat is conducted from the high-temperature pellets to the metal wall of the roller, it must pass through this low thermal conductivity vapor film before it can be absorbed by the external cooling water. Due to the strong insulating effect of the vapor film, heat rapidly accumulates inside the metal wall of the roller and cannot be effectively transferred to the cooling medium, causing the roller temperature to rise sharply. Under efficient forced convection heat transfer conditions, the inner wall temperature of the roller is usually maintained at 200-300℃. Once film boiling occurs, the inner wall temperature can instantly jump to 500-600℃ or even higher, and the roller turns dark red to bright red. This vapor film has dynamic instability and will periodically form, thicken, rupture locally or regenerate, causing violent fluctuations in the roller temperature, thereby generating alternating thermal stress inside the metal, which greatly increases the risk of thermal fatigue cracking of the roller material.

[0044] In this invention, the guide tube 405 is arranged at a distance from the inner wall of the roller shell 301, thereby defining a second cavity a2 with a significantly reduced cross-sectional area between them. According to Bernoulli's principle, under the condition that the water supply pressure is kept constant, the flow velocity of the heat transfer fluid will be significantly increased when it flows through the second cavity a2, thereby realizing high-speed impact and shearing action on the bubbles attached to the inner wall of the roller shell 301, causing the bubbles to be forcibly peeled off from the metal surface, and thus effectively weakening the adverse effects of the vapor film on the heat transfer process.

[0045] Please see Figure 8 In a preferred embodiment of the present invention, the flow guiding component 4 further includes flow passage holes 407 and spiral grooves 409. A plurality of spiral grooves 409 are respectively arranged in a plurality of cavities inside the flow guiding cylinder 405 so that the cavities are divided into two interconnected curved cavities. The flow passage holes 407 are arranged in a circumferential array at the outer diameter end of the flow guiding cylinder 405 and are respectively arranged on the two sets of curved cavity sides.

[0046] In practical application, baffles 408 are arranged between two sets of rings 406. The two adjacent sets of baffles 408 are used to connect the curved cavities on both sides of the spiral groove 409, so that the heat transfer medium flows in a serpentine manner inside the roller shell 301. During this flow, the heat transfer medium will generate swirling disturbance when passing through the limiting cylinder 309, which further enhances the mixing uniformity of the heat transfer medium in the circumferential direction of the roller. Through the guidance of the flow path by the baffles 408 and the rotational disturbance of the medium by the limiting cylinder 309, the heat transfer medium forms multiple alternating radial and circumferential mixing during the flow process, thereby effectively improving the overall temperature field uniformity of the roller and improving the thermal stability and heat conduction uniformity of the roller during operation.

[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A waste heat recovery and utilization device for pelletizing vertical shaft furnace hot exhaust gas, comprising furnace body components, characterized in that, The waste heat recovery and utilization equipment for the pelletizing vertical furnace includes: Separating roller module: Several separating roller modules are arranged at intervals on the bottom side of the furnace body assembly to support the material column inside the vertical furnace and to crush the material column on the contact surface. Each separating roller module includes two sets of roller body assemblies, which are arranged in a mirror image. The roller assembly includes a roller shell, concave surfaces, and crushing teeth. The roller shell is rotatably disposed in the furnace assembly, and the outer surface of the roller shell is provided with a plurality of concave surfaces and crushing teeth. The flow guiding assembly includes a fluid main pipe, a return pipe, and a flow guiding cylinder. One end of the fluid main pipe is fixedly installed in the furnace body assembly, and the other end of the fluid main pipe is rotatably assembled in the roller shell. The return pipe is connected to the fluid main pipe, and the outer diameter end of the return pipe is also fitted with a flow guiding cylinder. The flow guiding cylinder is used to limit the flow path of the heat transfer medium inside the roller shell.

2. The waste heat recovery and utilization equipment for pelletizing vertical shaft furnace hot exhaust gas according to claim 1, characterized in that, The furnace body assembly includes a furnace base, a material guiding chamber, a cooling chamber, a roasting chamber, a drying chamber, and a feeding chamber. The furnace base, material guiding chamber, cooling chamber, roasting chamber, drying chamber, and feeding chamber have equal and interconnected inner cavities in the vertical direction. A shuttle-type stacking machine is also installed in the feeding chamber for stacking pellet columns.

3. The waste heat recovery and utilization equipment for pelletizing vertical shaft furnace hot exhaust gas according to claim 2, characterized in that, The roller assembly also includes a perforated plate, an internal shaft seal, an external shaft seal, a rotating shaft, and a drive wheel. The perforated plate is locked and fixed in the inner cavity of the roller shell. The internal shaft seal is limited and locked at one end of the roller shell, and the external shaft seal is limited and locked at one side of the internal shaft seal. A rotating shaft is provided on the outer diameter side of the external shaft seal. The rotating shaft is rotatably mounted on the wall of the furnace base, and the drive wheel is limited and locked at one side of the rotating shaft.

4. The waste heat recovery and utilization equipment for pelletizing vertical shaft furnace hot exhaust gas according to claim 3, characterized in that, The roller assembly also includes an inlet pipe and a guide hole. The inlet pipe is located at one end of the fluid main pipe and is independent of the return pipe. The fluid main pipe is coaxially rotatably installed in the external shaft seal and the transmission wheel. The guide hole is provided on the side of the fluid main pipe facing the inner cavity of the roller shell. The inlet pipe and the guide hole are connected to each other for inputting heat transfer medium into the inner cavity of the roller shell.

5. The waste heat recovery and utilization equipment for pelletizing vertical shaft furnace hot exhaust gas according to claim 1, characterized in that, The outer diameter of the guide tube is smaller than the inner diameter of the roller shell; The outer diameter of the guide tube is arranged with several rings along the axial direction, and the rings and the roller shell are spaced apart.

6. The waste heat recovery and utilization equipment for pelletizing vertical shaft furnace hot exhaust gas according to claim 5, characterized in that, The guide tube has several baffles arranged in an array along the axial direction inside, which divide the inner cavity of the guide tube into several independent cavities. The ring and the baffle are offset along the axis of the guide tube.

7. The waste heat recovery and utilization equipment for pelletizing vertical shaft furnace hot exhaust gas according to claim 6, characterized in that, The flow guiding assembly also includes flow passages and spiral grooves. Several spiral grooves are respectively arranged in several cavities inside the flow guiding cylinder to divide the cavities into two interconnected curved cavities. The flow passages are arranged in a circumferential array at the outer diameter end of the flow guiding cylinder and are distributed on the sides of the two sets of curved cavities.

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