Convection type quenching heat recovery method for high-temperature fine powder

Abstract

The invention relates to the technical field of high-temperature fine powder cooling and heat recovery, aims to solve the problem that an existing fine powder cooling method cannot give consideration to fine powder quenching effect, heat exchange efficiency, heat recovery value, device installation and abrasion, and provides a convection type quenching heat recovery method for high-temperature fine powder. The high-temperature fine powder is cooled and subjected to heat recovery through the high-temperature fine powder convection type quenching heat recovery device; comprising the steps that high-temperature fine powder enters a material bed from a feeding port, cooling air enters the material bed from the bottom, the side face and the middle of the material bed, and due to the inclined arrangement of the material bed, the airflow suspension dispersion effect of an air supply system and the effect of a conveying and stirring device, the fine powder gradually forms a material layer from the feeding port, moves to a discharging port and enters an air pipe; main hot air rises and is recovered through the heat recovery air opening, part of the hot air enters the air pipe, and the balance wall isolates heat recovery air from discharging air draft. The quenching heat exchange rate can be increased, the product quality is improved, the heat recovery efficiency is improved, and the cooling device is simple in installation mode and small in abrasion.

Description

Technical Field

[0001] The present invention relates to the technical field of high-temperature fine powder cooling and heat recovery, and in particular to a high-temperature fine powder convection-type rapid cooling and heat recovery method. Background Art

[0002] In industries such as coal, chemical, and metallurgy, high-temperature fine powders (particle size 1-1000μm) often need to be cooled to maximize heat recovery. Currently, the main cooling methods for these fine powders include indirect cooling, semi-direct cooling, and suspension cooling, using either water or air cooling.

[0003] In the indirect cooling method, the fine powder does not directly contact the cooling medium. This type of indirect heat exchange includes plate type and rotary type. The advantage of this indirect heat exchange method is that the fine powder is not affected by the cooling medium, but it also has obvious drawbacks: First, the cooling heat exchange efficiency is low, requiring a large contact surface, resulting in a large equipment footprint and high investment costs; second, indirect heat exchange leads to slow cooling of the fine powder and poor rapid cooling effect, affecting the product quality of the fine powder (rapid cooling is beneficial for improving the whiteness and micro-cracks of the product); third, the temperature rise of the cooling medium after heat exchange is limited, and the heat recovery value is low, making it difficult to directly apply to the firing system, resulting in low heat recovery efficiency and high energy consumption; fourth, the fine powder easily aggregates on the heat exchange surface, reducing the long-term heat exchange stability; fifth, the direct contact and relative movement of the fine powder with the heat exchange surface will cause equipment wear, affecting the long-term stable operation of the system and increasing subsequent operation and maintenance costs.

[0004] In semi-direct cooling, the fine powder comes into semi-direct contact with the cooling medium. In other words, in semi-direct heat exchange, the semi-contact cooling medium is air, while the non-contact cooling medium is typically water. The cooling water acts only on the equipment casing, providing cooling and indirectly transferring heat. The primary motion of this type of equipment is rotary, with the fine powder agglomerated and rotating back and forth. Contact between the cooling air and the fine powder occurs primarily on the surface of the powder, with minimal heat exchange between the cooling air and the interior, and no convective heat transfer between the powder and the air. Furthermore, the amount of semi-direct cooling air is limited, requiring cooling to rely primarily on heat dissipation and indirect water cooling. This rotary semi-direct cooling heat exchange method has the following disadvantages: the small contact surface between the fine powder and the cooling air results in relatively low heat transfer efficiency and a relatively slow quenching rate; the cooling effect relies on indirect cooling water, resulting in a relatively low overall cooling rate; and the low heat recovery efficiency of the cooling water and air, resulting in low temperatures after heat exchange and low heat recovery value. Consequently, most existing production lines do not even recycle this heat, resulting in high energy consumption.

[0005] The suspension cooling method allows the fine powder to be fully and thoroughly in contact with the cooling medium air and suspended, achieving suspension and heat exchange, sufficient gas-solid mixing, a large heat exchange surface, and excellent rapid cooling. However, there are some drawbacks. First, during suspension cooling, the fine powder and cooling air enter and exit the cooling medium simultaneously, undergoing a single heat exchange, lacking a linear gradient. Multiple stages of suspension cooling and separation are often required to achieve complete cooling. Second, the suspension cooling device is relatively tall, making layout and installation difficult. Third, for fine powders, the suspension separator is inefficient, making dust separation difficult and causing severe internal circulation. Fourth, the extremely high wind speed during cyclonic separation can easily introduce additional wear and impurities, impacting the system's service life and the purity and quality of the product.

[0006] Fine powders have different fluidization characteristics than ordinary granular powders. First, fine powders, mostly Geldart A and C materials, tend to agglomerate easily, resulting in strong van der Waals forces and difficult fluidization. During fluidization, channeling and sluicing are very likely to occur, leading to abnormal fluidization, localized overheating or compaction of the material layer, and thus affecting heat transfer efficiency. Second, once fine powders break away from agglomerates, they are easily carried away by the cooling air, affecting the normal operation of the subsequent heat recovery system.

[0007] The existing fine powder cooling method mainly has the following problems: 1. In the existing indirect heat exchange technology, the cooling heat exchange efficiency is poor, the contact surface required for cooling is large, the space occupied is large, and the investment is high.

[0008] 2. In the existing indirect heat exchange and semi-direct heat exchange technology routes, indirect heat exchange leads to slow cooling speed of fine powder and poor rapid cooling effect, which affects the product quality of fine powder.

[0009] 3. In the existing indirect heat exchange and semi-direct heat exchange technology routes, the heat recovery value is not great, especially it is difficult to be directly recycled by the burning system, the heat recovery efficiency is low, and the energy consumption is high.

[0010] 4. In the existing indirect heat exchange and semi-direct heat exchange technology routes, fine powder materials tend to agglomerate on the heat exchange surface, further affecting the long-term stable heat exchange efficiency.

[0011] 5. In the existing indirect heat exchange technology route, there is a certain amount of wear on the heat exchange surface, which affects long-term stable operation and increases the subsequent operation and maintenance costs.

[0012] 6. The existing suspension cooling and heat exchange technology is difficult to arrange and install, and is prone to causing additional wear and impurities, affecting the service life of the system and the purity and quality of the product.

[0013] Therefore, the current existing technology lacks a cooling method that takes into account the rapid cooling effect of fine powder, heat exchange efficiency, heat recovery value, simple installation of cooling device and reduction of device wear. The existing technology does not have a device or operating production line for direct convection heat exchange between air and fine powder. Summary of the Invention

[0014] The present invention aims to provide a high-temperature fine powder material convection quenching heat recovery method to solve the problems that the existing fine powder material cooling method cannot take into account the fine powder material quenching effect, heat exchange efficiency, heat recovery value, cooling device installation and device wear.

[0015] The present invention is achieved by adopting the following technical solutions: The present invention provides a high-temperature fine powder material convection-type rapid cooling heat recovery method, which uses a high-temperature fine powder material convection-type rapid cooling heat recovery device to cool the high-temperature fine powder material and recover the heat; The high-temperature fine powder material convection quenching heat recovery device comprises a shell, a material bed is provided in the shell, a feed port and a discharge port are provided at both ends of the material bed, and the material bed is tilted toward one end of the discharge port; The high-temperature fine powder convection quenching heat recovery device is equipped with an air supply system, which is used to provide bottom air supply, side air supply and middle air supply. The bottom air supply is used for convection quenching and heat exchange with the material layer, forming a strong direct convection quenching and heat exchange process. The side air supply and middle air supply are used to reduce the temperature around the fine powder, forming a temperature gradient, and cooperate to achieve heat exchange cooling of the fine powder. A porous settling plate is installed inside the high-temperature fine powder convection quenching heat recovery device. The porous settling plate is located above the material layer and is used to intercept and agglomerate the fine powder in the suspended material gas and make it settle to the material layer. A conveying and stirring device is installed on the material bed, which is used to homogenize and convey the material; A flow stabilizing bed is arranged below the conveying and stirring device. The bottom cooling air enters the material bed through the flow stabilizing bed. The flow stabilizing bed is used to even out the air and stabilize the flow. A heat recovery vent is provided on the top of the shell to recover hot air; The discharge port is connected with an air duct to realize discharge and ventilation; A balancing wall is arranged inside the shell. The balancing wall is arranged in front of the discharge port. The bottom of the balancing wall is flush with the top surface of the material layer. The balancing wall is used to isolate the heat recovery air and the discharge exhaust air, control the balance of the hot air pressure on both sides, reduce the impact of the air paths on each other, and enhance the stability and operability of the entire device. A reflective sedimentation plate is installed in front of the discharge port. The reflective sedimentation plate is used to reflect and slow down the highly fluid powder layer in front of the discharge port, reducing the impact on the downstream, while reducing the suspended dust caused by the impact and promoting the rebound and sedimentation of the material; The heat recovery method of high-temperature fine powder convection quenching includes: High-temperature fine powder enters the material bed from the feed port, and cooling air enters the material bed from the bottom, side, and middle of the material bed. Based on the balance calculation of the fine powder gravity and drag force, the critical fluidization velocity and spraying velocity of the fine powder are obtained. Based on this, the bottom air supply volume and critical wind speed are controlled. The cooling wind speed per unit cross section of the material bed is less than 0.4m / s, and the cooling load per unit area is less than 15t / m 2 , so that the fine powder reaches the critical fluidization state, the powder on the material bed is in a near-fluidization state of dense phase transportation and cooling, and a stable fluidized material layer is obtained. The bottom air supply and the material layer are convectively cooled and heat exchanged; the side air supply and the middle air supply pass through the surface of the material layer for surface-to-surface heat exchange, forming a temperature gradient; After the fine powder enters the material bed, due to the inclined arrangement of the material bed, the air flow suspension and dispersion effect of the air supply system and the action of the conveying and stirring device, the fine powder gradually forms a material layer from the feed port and moves to the discharge port and enters the air duct. Part of the fine powder separates from the agglomerate during the fluidization and conveying process, and is intercepted and agglomerated by the porous sedimentation plate to settle to the material layer. Before the material layer enters the discharge port, the fine powder gas collides and reflects with the reflective sedimentation plate; the main hot air rises and is recovered through the heat recovery air port, and part of the hot air enters the air duct, and the balance wall isolates the heat recovery air from the discharge exhaust air.

[0016] Among them, the near-fluidization state refers to the state of the material when it reaches the critical fluidization state.

[0017] Based on the many advantages of direct convection linear gradient heat exchange, the present invention improves the rapid cooling heat exchange rate, improves product quality, and improves heat recovery efficiency. It is used in the firing system to reduce energy consumption. It has important strategic significance in environmental protection and energy conservation and carbon reduction. It can also contribute to the goal of achieving sustainable green circular development. It has important scientific and technological research and practical application value.

[0018] As the preferred technical solution: Calculate the critical fluidization velocity according to the Wen-Yu formula :

[0019] in, is the critical fluidization velocity, in m / s, is the dynamic viscosity of the powder, in Pa·s, is the density of the gas, in kg / m³, is the equivalent diameter of the powder particles, in m, Density of powder particles, unit: kg / m³, is the acceleration due to gravity, unit is m / .

[0020] This formula is suitable for fine powders or particle systems with low Reynolds numbers (Re ≤ 20). Fluid Type: Suitable for gas-solid fluidized beds, especially for high-viscosity fluids or fine particles. Limitations: Prediction errors are large for widely sized particles (wide particle size distributions) and require experimental correction. For high Reynolds numbers (Re > 1000), alternative formulas (such as the Ergun equation) are required.

[0021] As the preferred technical solution: The entire high-temperature fine powder convection rapid cooling heat recovery device is long, slender and tall, forming a narrow cooling channel, which is convenient for forming a stable material flow.

[0022] As the preferred technical solution: The height from the material bed to the heat recovery port is greater than 5m, which is conducive to the reagglomeration, growth and sedimentation of suspended dust, and reduces the dust concentration of the heat recovery air.

[0023] As the preferred technical solution: The high-temperature fine powder enters the material bed from the feed port through the feeding device, which is connected to the feed port. The feeding device adopts a double V-bend feeding device, which includes a V-shaped section at the top, a straight section in the middle, and a V-shaped groove at the bottom. The end with the larger opening of the V-shaped section is used to collect the high-temperature fine powder from upstream, and the end with the smaller opening of the V-shaped section is connected to and communicates with the straight section. The straight section is bent relative to the V-shaped section and arranged at an angle to form a material discharge slope. The cross-sectional area of ​​the straight section allows the maximum designed material flow to pass through. The high-temperature fine powder is collected and then enters the material discharge slope, which prevents the fine powder from directly impacting the convection quenching heat recovery device and reduces the dispersion of the material. The end with the larger opening of the V-shaped groove is connected to the feed port, and the end with the smaller opening of the V-shaped groove is connected and communicated with the straight section. The V-shaped groove is used to disperse and evenly distribute fine powder.

[0024] As the preferred technical solution: A plug-in air lock valve is installed at the straight section to control the cross-sectional area of ​​the straight section.

[0025] As the preferred technical solution: The air supply system includes a cooling air inlet box and a multi-sided air inlet device. Multiple cooling air inlet boxes are arranged at the bottom of the material bed. The cooling air inlet box is installed at the bottom of the steady flow bed. The multi-sided air inlet device is installed in the middle position on both sides of the tail of the shell. The cooling air inlet box adopts a pulse air supply box.

[0026] The pulse air supply box supplies air from the bottom of the material bed to force heat exchange with the powder in a stepped convection manner; the pulse air supply box intermittently supplies air in different zones, which can promote fluidization while reducing the dust carried away by suspended separation.

[0027] For special powders, the agglomeration forces between Geldart C fine powders are very strong, far exceeding the gravity of the powder particles. Cold-state experiments have shown that, when controlled at a certain air speed (less than 0.4 m / s), the fine powder undergoes localized bubbling and fluidization, lifting, but the majority of the powder reagglomerates and returns to the material bed, forming a near-circulating bubbling pattern. Consequently, very little fine powder is suspended and carried away during small-scale bubbling and fluidization. Controlling the cooling air flow rate and adopting intermittent air supply enhances the effect of sedimentation and reagglomeration, ultimately creating a dense phase fluidization and transport pattern, forming a relatively stable flowing material layer, and reducing dust segregation and suspension at the source.

[0028] As the preferred technical solution: The porous sedimentation plate adopts a V-shaped porous sedimentation plate, the cross section of which is V-shaped, and the opening thereof faces the material layer, and a plurality of holes are opened on the V-shaped porous sedimentation plate.

[0029] As the preferred technical solution: A cleaning and blowing device is installed on the V-shaped porous settling plate, and the V-shaped porous settling plate and the cleaning and blowing device are arranged above the material layer and the side air supply.

[0030] As the preferred technical solution: The flow stabilization bed includes, arranged from bottom to top, a first layer of air supply plates, a second layer of air-distributing ceramic balls, a third layer of porous air-distributing plates and a material box; The first layer of air supply plates has holes and a labyrinth seal formed on them; the second layer of air-distributing ceramic balls has a variety of particle sizes; The third layer of porous air distribution plate is formed with multiple holes in the shape of inverted bell mouths. The upper cylindrical diameter of the holes is smaller than the diameter of the bell mouth, forming a Venturi effect, reducing the pressure in the contact area of ​​the fine powder, promoting the formation of a stable material layer of the fine powder, reducing suspension boiling and dispersion, and enhancing the air supply and flow stabilization effect; The material box adopts a grid structure to form a dead material layer; A gravity-type automatic flow valve is provided between the steady flow bed and the pulse air supply box.

[0031] The gravity-type automatic flow valve can automatically adjust the air supply volume according to the resistance changes caused by material distribution, reasonably distribute the cooling air volume, prevent cooling air short circuit, and promote powder fluidization and heat exchange.

[0032] When a short circuit occurs in a local area of ​​powder, the automatic flow valve automatically closes, reducing the cooling air supply to that area. Similarly, when the cooling air supply to a local area is insufficient, the automatic flow valve opens, increasing the cooling air supply to that area. This automatic flow valve promotes fluidization and air supply balance throughout the powder bed, achieving better convective heat exchange.

[0033] As the preferred technical solution: The heat recovery vents include high-temperature heat recovery vents and low-temperature heat recovery vents.

[0034] As the preferred technical solution: The reflective sedimentation plate is arranged at an angle of 45 degrees to the material layer.

[0035] As the preferred technical solution: The inclination angle of the material bed is 1-5 degrees.

[0036] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. The present invention realizes extremely fast quenching and heat exchange rate through direct convection heat exchange between cooling air and powder, thereby obtaining high-quality products. At the same time, it realizes maximum heat recovery and utilizes it in the firing system, with significant effects of energy saving, consumption reduction and emission reduction.

[0037] 2. The present invention integrates the functions of collecting materials, locking air and distributing materials, which can reduce dispersion separation, lock air and stabilize flow, reduce the impact of negative pressure fluctuations on upstream and downstream equipment, and lay the foundation for the uniform dispersion and distribution of fine powder materials on the quenching device.

[0038] 3. To address the problem of fine powder being difficult to fluidize, the present invention designs multiple sets of conveying and stirring devices to enhance stirring, increase the gas-solid porosity, break up powder agglomerates, and maximize the elimination of abnormal fluidization phenomena such as channeling and slugging. At the same time, the stirring device can also convey the powder forward to complete cascade convection heat exchange.

[0039] 4. The stabilizing bed of the present invention has the functions of preventing material leakage, homogenizing and reducing wind speed, balancing the upper and lower pressure ratios of the material bed, and reducing the impact force on the powder, thus laying the foundation for stabilizing and fluidizing fine powder.

[0040] 5. Because fine powders tend to suspend easily, this invention utilizes a multi-group, multi-faceted, combined air supply system to increase the air supply area and reduce the cooling air velocity per unit cross-section to below the theoretical suspension velocity. This controls the suspension separation of fine powders and minimizes the impact on hot air recovery. Furthermore, in other cooling areas unaffected by this effect, the cooling air velocity and volume are increased to enhance cooling, heat exchange, and heat recovery efficiency.

[0041] 6. The reflective sedimentation plate of the present invention has the function of reducing the speed of the fine powder flow and causing refraction, while increasing the sedimentation of the suspended fine powder, which is beneficial to further discharge.

[0042] 7. The present invention utilizes multiple sets of V-shaped porous sedimentation plates and a purge device. The V-shaped porous sedimentation plates have a V-shaped cross-section, increasing the contact area with the surface fine powder. Furthermore, the plates contain holes approximately 3-10 times the diameter of the dust, allowing airflow to pass through. Suspended fine powder agglomerates under the obstruction of the porous sedimentation plates, enhancing dust agglomeration and sedimentation, further reducing the concentration of suspended dust carried away. Furthermore, the purge device automatically and regularly clears blocked holes and replenishes cooling airflow, lowering the ambient temperature, creating a temperature gradient, and enhancing the cooling and heat exchange effect.

[0043] 8. The top of the convection-type rapid cooling heat recovery device of the present invention is provided with multiple groups of heat recovery ports, which promote the formation of gradient heat exchange on the material layer, achieve a more efficient rapid cooling heat exchange effect with minimized cooling air volume, and promptly remove the hot air and apply it to the heat recovery system to achieve energy saving, consumption reduction and emission reduction.

[0044] 9. The pressure balance wall of the present invention can adjust the balance of air volume and pressure before and after the material bed, enhance the balance between the external discharge port and the heat recovery system, and improve the operability of the system.

[0045] 10. The fine powder and part of the cooling air enter the cooling air duct of the subsequent process to achieve heat exchange and separation between the main fine powder and the cooling air.

[0046] 11. The high-temperature fine powder convection quenching heat recovery device of the present invention is simple in layout and installation, does not involve extremely high wind speeds, and avoids causing additional wear and impurities. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 This is the main layout diagram of the high-temperature fine powder convection rapid cooling heat recovery device described in the present invention.

[0048] Figure 2 This is an isometric view of the high-temperature fine powder convection quenching heat recovery device described in the present invention.

[0049] Figure 3 This is a top view of the high-temperature fine powder convection rapid cooling heat recovery device described in the present invention.

[0050] Figure 4 It is a side view of the high-temperature fine powder convection rapid cooling heat recovery device described in the present invention.

[0051] Figure 5 for Figure 1 Cross-sectional view in the AA direction.

[0052] Figure 6 This is a partially enlarged view of the stabilized flow bed described in the present invention.

[0053] Figure 7 It is an enlarged view of the air vent described in the present invention.

[0054] Figure 8 This is a rendering of the simulation analysis of the high-temperature fine powder convection rapid cooling heat recovery device described in the present invention.

[0055] Icons: 1-feeding device, 101-V-shaped section, 102-straight section, 103-V-shaped groove, 2-air lock valve, 3-pulse air supply box one, 4-pulse air supply box two, 5-pulse air supply box three, 6-multi-faceted air inlet device, 7-high-temperature heat recovery air outlet, 8-low-temperature heat recovery air outlet, 9-blowing device, 10-V-shaped porous sedimentation plate, 11-balance wall, 12-reflective sedimentation plate, 13-discharge port, 14-air duct, 15-conveying and stirring device, 16-steady flow bed, 16.1-first layer air supply plate, 16.2-second layer air uniformity ceramic ball, 16.3-third layer porous air uniformity plate, 16.4-material box, 16.5-gravity automatic flow valve, 17-shell, 18-material bed. DETAILED DESCRIPTION

[0056] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0057] Example 1 This embodiment proposes a high-temperature fine powder material convection quenching heat recovery method, which uses a high-temperature fine powder material convection quenching heat recovery device to cool the high-temperature fine powder material and recover the heat, wherein, Figure 1-Figure 7 As shown, the high-temperature fine powder convection-type rapid cooling heat recovery device includes a housing 17, within which a material bed 18 is located. The entire device is long, slender, and tall, forming a narrow cooling channel. A feed inlet and a discharge port 13 are provided at each end of the material bed 18. The feed inlet is connected to a feed device 1. The high-temperature fine powder enters the material bed 18 from the feed device 1, forming a material layer. The fine powder is cooled in the material bed 18 and then discharged from the discharge port 13. The discharge port 13 is connected to an air duct 14 for exhaust ventilation.

[0058] The feeding device 1 adopts a double V-bend feeding device 1, which includes an upper V-shaped section 101, a middle straight section 102 and a lower V-shaped groove 103. The end with a larger opening of the upper V-shaped section 101 is used to collect high-temperature fine powder from upstream, and the end with a smaller opening of the upper V-shaped section 101 is connected to and communicates with the straight section 102; The straight section 102 is bent relative to the upper V-shaped section 101 and arranged at an angle to form a material discharge slope. The cross-sectional area of ​​the straight section 102 allows the maximum designed material flow to pass through. The high-temperature fine powder is collected and then enters the material discharge slope, preventing the fine powder from directly impacting the convection quenching heat recovery device, thereby reducing the dispersion of the material. The larger end of the lower V-groove 103 is connected to the feed port, and the smaller end of the V-groove 103 is connected and communicated with the straight section 102. The height of the V-groove 103 is less than that of the V-section 101. The V-groove 103 is used to disperse and evenly distribute fine powder. The double V-bend feeding device 1 adopts a double V-shaped design, which is convenient for gathering and distributing materials. The V-section 101 is used to receive the upstream equipment rotary kiln. The straight section 102 is equipped with a plug-in air lock valve 2 to control the cross-sectional area of ​​the straight section 102 and the impact of fluctuations caused by wind pressure on upstream and downstream equipment. This can achieve material sealing and minimize the mutual influence of upstream and downstream equipment. At the same time, due to the sealing effect of the air lock valve 2, the material can be dispersed and distributed into the convection-type rapid cooling heat recovery device.

[0059] The material bed 18 is tilted at a certain angle θ (1-5 degrees) according to the characteristics of the specific material, and the material bed 18 is tilted toward one end of the discharge port 13 .

[0060] An air supply system is installed on the device, which can provide bottom air supply, side air supply and middle air supply. The air supply system includes a cooling air inlet box and a multi-faceted air inlet device 6.

[0061] Specifically, a plurality of cooling air inlet boxes are arranged at the bottom of the material bed 18. In the present embodiment, three cooling air inlet boxes are installed at intervals at the bottom of the material bed 18. The cooling air inlet boxes adopt pulse air supply boxes. The three pulse air supply boxes are pulse air supply box 1 3, pulse air supply box 2 4, and pulse air supply box 3 5. The air supply at the bottom of the material bed 18 enables the fine powder to directly undergo convection heat exchange with the cooling air, forming a strong direct convection rapid cooling and heat exchange process, thereby obtaining a rapid cooling product with better quality.

[0062] The housing 17 is also equipped with a multi-faceted air inlet device 6. Cooling air enters the interior of the convection-type rapid cooling heat recovery device through pulse air supply box 1 3, pulse air supply box 2 4, pulse air supply box 3 5, and the multi-faceted air inlet device 6. Preferably, the multi-faceted air inlet device 6 is installed in the middle position on both sides of the rear end of the housing 17. The multi-faceted air inlet device 6 can directly supply air from both sides and the middle of the material layer. This cooling air passes over the surface of the material layer. With the assistance of the multi-faceted air inlet device 6, the cooling air volume can be increased, the cooling effect can be enhanced, and the suspension separation of fine powder can be avoided.

[0063] Preferably, the multi-faceted air inlet device 6 also adopts a pulse air supply box.

[0064] The air supply system of the present invention includes various forms such as bottom air supply, side air supply, and middle air supply. The bottom air supply passes through multiple groups of air inlet boxes and the steady flow bed 16 to directly exchange heat with the fine powder, causing the fine powder to be in a microfluidized boiling state, reducing the suspension and separation of the fine powder from the source; the other surface air supply is used to reduce the temperature around the fine powder, forming a temperature gradient, and cooperating to achieve heat exchange cooling of the fine powder.

[0065] The present invention adopts a combined precise partitioned air supply mode of multiple bottom air supply groups and multiple surface air supply groups to ensure sufficient cooling air volume and control different reasonable cooling air speeds per unit cross section.

[0066] The material bed 18 of the present invention has a large area and the cooling load per unit area is less than 15t / m 2 The cooling wind speed per unit area is less than 0.4 m / s, and the powder on the material bed 18 is in a near-fluidized state of dense phase transportation and cooling.

[0067] The convection-type rapid cooling heat recovery unit is internally equipped with multiple V-shaped porous settling plates 10. These plates have a V-shaped cross-section, with their openings facing the material bed. Their ends are fixedly connected to the housing 17 on either side of the material bed 18. The surface area of ​​these plates is much larger than that of the material bed 18. This design helps increase the contact area with the suspended material, reduces the wind speed across its cross section, and enhances interception, agglomeration, and sedimentation capabilities. Due to reflection and van der Waals forces, most of the suspended dust settles and aggregates here, eventually settling and re-entering the stable material bed.

[0068] The V-shaped porous settling plate 10 is provided with a plurality of holes, the diameter of the holes being 3-10 times the diameter of the fine powder D50, through which heat recovery air can pass.

[0069] Preferably, a blowing device 9 is installed on the V-shaped porous sedimentation plate 10. When the agglomerated dust particles block the holes on the V-shaped porous sedimentation plate 10, the blowing device 9 can be used to automatically clean them regularly. In addition, the blowing device 9 also has the function of supplementing cooling air, reducing the ambient temperature, forming a temperature gradient, and enhancing the cooling and heat exchange effect.

[0070] The structure of the cleaning and blowing device 9 is prior art and will not be described in detail here. It only needs to be able to achieve air supply and cleaning, and usually includes a compressed air nozzle and connecting pipes.

[0071] Preferably, multiple groups of V-shaped porous settling plates 10 and blowing devices 9 are arranged above the material layer and the side air supply.

[0072] A plurality of conveying and stirring devices 15 are installed on the material bed 18. The conveying and stirring devices 15 control the flow rate of the fine powder through rotational motion to form a stable material layer. At the same time, the conveying and stirring devices 15 force stirring in the material layer to enhance the homogenization and transportation of the material in the material bed 18, and transport the fine powder from the feed end to the discharge end. Forced stirring is used to eliminate the channeling and throttling phenomena formed during the fluidization process of the fine powder, thereby improving the fluidization performance of the fine powder and promoting convective heat exchange.

[0073] The conveying and stirring device 15 of the present invention can not only convey fine powder, but also homogenize the fine powder layer. Since fine powder is extremely difficult to fluidize, the force between fine powders is much greater than its gravity, the gaps between particles are extremely small, and the air permeability is low, which easily leads to uneven fluidization and short-circuiting. Therefore, the present invention designs multiple groups of conveying and stirring devices 15 to continuously stir the material layer and promote uniform fluidization and cooling of the fine powder.

[0074] Among them, the conveying and stirring device 15 is a prior art, and its structure is not described in detail here. For example, the Chinese utility model patent with publication number CN20441653U "A swinging motion mechanism for converting linear motion into multiple outputs" can be adopted. It is not limited to the above-mentioned mechanism, and other structures that can realize the conveying and homogenization of fine powder materials can also be used.

[0075] A flow stabilizing bed 16 is arranged below the conveying and stirring device 15 , and a cooling air inlet box is installed at the bottom of the flow stabilizing bed 16 . The bottom cooling air passes through the flow stabilizing bed 16 and enters the material bed 18 .

[0076] Preferably, the flow stabilizing bed 16 comprises a first layer of air supply plates 16.1, a second layer of air-distributing ceramic balls 16.2, a third layer of porous air-distributing plates 16.3 and a material box 16.4, which are arranged in sequence from bottom to top; The first air supply plate 16.1 has a relatively large opening ratio (20-40%) to reduce air velocity and minimize impact and suspension separation of fine powder. The first air supply plate 16.1 also forms a labyrinth seal to prevent powder from leaking into the air inlet box. In other words, the first air supply plate 16.1 ensures low-speed air supply and a leak-proof labyrinth seal. The second layer of air-distributing ceramic balls 16.2 has a variety of particle sizes, which makes the cooling air supply more uniform and further optimizes the air flow distribution; The third layer of porous air distribution plate 16.3 is formed with a plurality of air holes in the shape of inverted bell mouths. The upper cylindrical diameter Φ2 of the air holes is smaller than the diameter Φ1 of the bell mouths, creating a Venturi effect, reducing the pressure in the contact area of ​​the fine powder, promoting the formation of a stable material layer of the fine powder, reducing suspension boiling and dispersion, and enhancing the air supply and flow stabilization effect. The material box 16.4 is made of heat-resistant steel with a grid structure, which is convenient for forming a relatively stable dead material layer to stably form a powder material layer; In addition to the above-mentioned wind and flow stabilization effects, the flow stabilization bed 16 can also balance the resistance ratio of the upper and lower layers of the material layer to avoid top-heavyness, which is beneficial to the operation of cooling air.

[0077] Preferably, a gravity-type automatic flow valve 16.5 is provided between the steady flow bed 16 and the pulse air supply box. The gravity-type automatic flow valve 16.5 can automatically adjust the air supply volume according to the resistance change caused by the material distribution, reasonably distribute the cooling air volume, prevent the cooling air short circuit, and promote the fluidization heat exchange of the powder.

[0078] A reflection sedimentation plate 12 is provided at the place where the material layer enters the discharge port 13. The reflection sedimentation plate 12 is fixedly mounted on the shell 17. The reflection sedimentation plate 12 is arranged at an angle of 45 degrees to the material layer, so as to reflect and decelerate the highly fluid powder layer in front of the discharge port 13, thereby reducing the impact on the downstream and the suspended dust caused by the impact, and promoting the rebound and sedimentation of the material.

[0079] The present invention promotes the sedimentation of part of the suspended powder by using the reflective sedimentation plate 12 and the V-shaped porous sedimentation plate 10, thereby significantly reducing the dust concentration of the heat recovery air.

[0080] The top of the shell 17 is provided with a high-temperature heat recovery vent 7 and a low-temperature heat recovery vent 8. Multiple sets of heat recovery vents are used to recycle the air after heat exchange to the firing system and control the dust concentration within a reasonable range. The present invention achieves efficient cooling through direct convection heat exchange between the cooling air and the fine powder, and recovers the hot air after heat exchange and reintroduces it into the firing system for utilization, achieving efficient cascade heat exchange and heat recovery. The height from the material bed 18 to the heat recovery vent is greater than 5m, which is conducive to the reagglomeration, growth and sedimentation of suspended dust, thereby reducing the dust concentration of the heat recovery air.

[0081] A balance wall 11 is arranged inside the shell 17. The top of the balance wall 11 is fixedly connected to the shell 17. The balance wall 11 is arranged in front of the discharge port 13. The bottom of the balance wall 11 is flush with the top surface of the material layer, forcibly isolating and disconnecting the heat recovery air and the discharge exhaust air, which is used to control the balance of hot air pressure on both sides, reduce the impact of the wind paths on each other, and enhance the stability and operability of the entire device.

[0082] After the fine powder enters the material bed 18, under the dual effects of the cooling air suspension fluidization (multi-faceted air supply) and the conveying and stirring device 15, most of the fine powder flows along the material bed 18 into the discharge port 13 and completes gradient heat exchange with the cooling air. The cooled fine powder and part of the cooling air enter the air duct 14 through the discharge port 13 to continue running the subsequent processes, completing the entire material-air cooling and heat exchange process. Very little powder is suspended and enters the heat recovery system, realizing material-air heat exchange and separation.

[0083] The high-temperature fine powder convection quenching heat recovery method comprises the following steps: The high-temperature fine powder enters the material bed 18 from the double V-bend feeding device 1. At the same time, the cooling air enters the material bed 18 from the pulse air supply box 1 3, the pulse air supply box 2 4, the pulse air supply box 3 5, the multi-faceted air inlet device 6, etc. The critical fluidization velocity and the spraying velocity of different fine powders are calculated based on the balance between the gravity and the drag force of the fine powder, so that different cooling air volumes are supplied to different air inlet boxes in a targeted manner, and the critical wind speed is controlled. The critical fluidization state of the fine powder is obtained through the controllable critical wind speed, and the fine powder is prevented from completely entering the boiling suspension and separation state, thereby obtaining a stable fluidized material layer; the multi-faceted air inlet device 6 directly supplies air from both sides and the middle part of the material layer. This part of the cooling air passes over the surface of the material layer, exchanges heat with the surface of the material layer, and forms a strong temperature gradient. According to Newton's cooling law, a larger temperature gradient is conducive to achieving cooling heat exchange. The auxiliary role of the multi-faceted air inlet device 6 can increase the cooling air volume, enhance the cooling effect, and at the same time avoid the suspension and separation of the fine powder; After the fine powder enters the material bed 18, due to the material bed 18 being arranged at a certain angle θ (1-5 degrees), coupled with the air flow suspension and dispersion effect, and under the action of the conveying and stirring device 15, the fine powder gradually forms a material layer from the feed port and moves to the discharge port 13, and finally enters the air duct 14, completing the transmission of the main fine powder; Since the particle size (PSD) of fine powders is often normally distributed, there are many ultrafine powders with extremely small particle sizes. This part of fine powders is easy to break away from agglomerates and separate during the fluidization and transportation process. This small amount of separated fine powders moves upward under the action of hot air and collides with the V-shaped porous settling plate 10, achieving momentum conversion, deceleration, and agglomeration and growth with other powders, and finally settles back to the material layer. The V-shaped porous settling plate 10 intercepts and agglomerates the suspended material gas. When the agglomerated dust particles block the holes on the V-shaped porous settling plate 10, they are regularly and automatically cleaned by the cleaning device 9, which also serves as a cooling air supply. Before the material layer enters the discharge port 13, the fine powder gas collides and reflects with the reflective settling plate 12. After the gas is reflected, the energy is reduced, and the fine powder and part of the hot gas enter the air duct 14. The main hot air rises and enters the high-temperature heat recovery air outlet 7 and the low-temperature heat recovery air outlet 8. After direct convection heat exchange, the cooling air rises directly and promptly into the heat recovery system, forming a linear gradient heat exchange, which is conducive to the formation of a larger temperature gradient in the subsequent material layer, enhancing the heat exchange effect (the heat exchange effect is significantly stronger than the one-time mixed heat exchange, and the cooling air volume can be greatly reduced), and can also realize temperature recovery and utilization at different levels.

[0084] In the entire convection-type rapid cooling heat recovery device, a pressure balance wall 11 is provided, the bottom of which is flush with the top surface of the material layer, and is used to control the balance of hot air pressure on both sides, thereby enhancing the stability and operability of the entire device.

[0085] Figure 8 This is a rendering of the simulation analysis of the present invention. By coupling the flow field and temperature field of high-temperature fine powder, the present invention clearly demonstrates the dynamic flow characteristics and heat exchange behavior of the material layer within the convection quenching device. Experimental verification shows that the proposed method and device for convection quenching heat recovery of high-temperature fine powder solves the problem of fine powder being difficult to fluidize at low air volumes and prone to suspension at high air volumes by optimizing the air supply form of multiple groups and multiple facets, enhancing agitation to enhance the fluidization effect, and configuring various sedimentation devices. This provides key technical support for direct convection heat exchange recovery of fine powder, and has significant engineering application value and industrialization prospects.

[0086] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A high-temperature fine powder convection cooling heat recovery method, characterized by: Cooling the high-temperature fine powder and recovering the heat through a high-temperature fine powder convection quenching heat recovery device; The device includes a shell, a material bed is provided in the shell, a feed port and a discharge port are provided at both ends of the material bed, and the material bed is arranged tilted toward the discharge port; The device is equipped with an air supply system, which is used to provide air supply at the bottom, sides and middle; A porous sedimentation plate is installed inside the device, and the porous sedimentation plate is located above the material layer; A conveying and stirring device is installed on the material bed; A steady flow bed is arranged below the conveying and stirring device, and the bottom cooling air enters the material bed through the steady flow bed; There is a heat recovery vent on the top of the shell; The discharge port is connected with an air duct; A balance wall is arranged inside the shell. The balance wall is arranged in front of the discharge port, and the bottom of the balance wall is flush with the top surface of the material layer; A reflective sedimentation plate is installed in front of the discharge port; Methods include: High-temperature fine powder enters the material bed from the feed port, and cooling air enters the material bed from the bottom, side, and middle of the material bed. Based on the balance calculation of the fine powder gravity and drag force, the critical fluidization velocity and spraying velocity of the fine powder are obtained. Based on this, the bottom air supply volume and critical wind speed are controlled. The cooling wind speed per unit cross section of the material bed is less than 0.4m / s, and the cooling load per unit area is less than 15t / m 2 , so that the fine powder reaches the critical fluidization state, the powder on the material bed is in a near-fluidization state of dense phase transportation and cooling, and a stable fluidized material layer is obtained. The bottom air supply and the material layer are convectively cooled and heat exchanged; the side air supply and the middle air supply pass through the surface of the material layer for surface-to-surface heat exchange, forming a temperature gradient; After the fine powder enters the material bed, due to the inclined arrangement of the material bed, the air flow suspension and dispersion effect of the air supply system and the action of the conveying and stirring device, the fine powder gradually forms a material layer from the feed port and moves to the discharge port and enters the air duct. Part of the fine powder separates from the agglomerate during the fluidization and conveying process, and is intercepted and agglomerated by the porous sedimentation plate to settle to the material layer. Before the material layer enters the discharge port, the fine powder gas collides and reflects with the reflective sedimentation plate; the main hot air rises and is recovered through the heat recovery air port, and part of the hot air enters the air duct, and the balance wall isolates the heat recovery air from the discharge exhaust air.

2. The high-temperature fine powder convection cooling heat recovery method according to claim 1, characterized in that: The high-temperature fine powder enters the material bed from the feed port through the feeding device, which is connected to the feed port. The feeding device adopts a double V-bend feeding device, which includes a V-shaped section at the top, a straight section in the middle, and a V-shaped groove at the bottom. The end with the larger opening of the V-shaped section is used to collect the high-temperature fine powder from upstream, and the end with the smaller opening of the V-shaped section is connected to and communicates with the straight section. The straight section is bent relative to the V-shaped section and arranged at an angle to form a material discharge slope. The cross-sectional area of ​​the straight section allows the maximum designed material flow to pass through. The high-temperature fine powder is collected and then enters the material discharge slope, which prevents the fine powder from directly impacting the convection quenching heat recovery device and reduces the dispersion of the material. The end with the larger opening of the V-shaped groove is connected to the feed port, and the end with the smaller opening of the V-shaped groove is connected and communicated with the straight section. The V-shaped groove is used to disperse and evenly distribute fine powder.

3. The high-temperature fine powder convection cooling heat recovery method according to claim 2, characterized in that: A plug-in air lock valve is installed at the straight section to control the cross-sectional area of ​​the straight section.

4. The high-temperature fine powder convection cooling heat recovery method according to claim 1, characterized in that: The air supply system includes a cooling air inlet box and a multi-sided air inlet device. Multiple cooling air inlet boxes are arranged at the bottom of the material bed. The cooling air inlet box is installed at the bottom of the steady flow bed. The multi-sided air inlet device is installed in the middle position on both sides of the tail of the shell. The cooling air inlet box adopts a pulse air supply box.

5. The high-temperature fine powder convection cooling heat recovery method according to claim 1, characterized in that: The porous sedimentation plate adopts a V-shaped porous sedimentation plate, the cross section of which is V-shaped, and the opening thereof faces the material layer, and a plurality of holes are opened on the V-shaped porous sedimentation plate.

6. The high-temperature fine powder convection cooling heat recovery method according to claim 5, characterized in that: A cleaning and blowing device is installed on the V-shaped porous settling plate, and the V-shaped porous settling plate and the cleaning and blowing device are arranged above the material layer and the side air supply.

7. The high-temperature fine powder convection cooling heat recovery method according to claim 4, characterized in that: The flow stabilization bed includes, arranged from bottom to top, a first layer of air supply plates, a second layer of air-distributing ceramic balls, a third layer of porous air-distributing plates and a material box; The first layer of air supply plates has holes and a labyrinth seal formed on them; the second layer of air-distributing ceramic balls has a variety of particle sizes; The third layer of porous air distribution plate is formed with multiple holes in the shape of inverted bell mouths. The upper cylindrical diameter of the holes is smaller than the diameter of the bell mouth, forming a Venturi effect, reducing the pressure in the contact area of ​​the fine powder, promoting the formation of a stable material layer of the fine powder, reducing suspension boiling and dispersion, and enhancing the air supply and flow stabilization effect; The material box adopts a grid structure to form a dead material layer; A gravity-type automatic flow valve is provided between the steady flow bed and the pulse air supply box.

8. The high-temperature fine powder convection cooling heat recovery method according to claim 1, characterized in that: The heat recovery vents include high-temperature heat recovery vents and low-temperature heat recovery vents.

9. The high-temperature fine powder convection cooling heat recovery method according to claim 1, characterized in that: The reflective sedimentation plate is arranged at an angle of 45 degrees to the material layer.

10. The high-temperature fine powder convection cooling heat recovery method according to claim 1, characterized in that: The inclination angle of the material bed is 1-5 degrees.

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