High temperature fine powder counterflow quenching heat recovery method

Abstract

The present application relates to high temperature fine powder cooling and heat recovery technical field, aims at solving the problem that the existing fine powder cooling method cannot consider the rapid cooling effect, heat exchange efficiency, heat recovery value, device installation and wear of fine powder, and provides a high temperature fine powder convection type rapid cooling heat recovery method, which cools high temperature fine powder and recovers heat through a high temperature fine powder convection type rapid cooling heat recovery device; including that high temperature fine powder enters the bed from the feed port, cooling air enters the bed from the bottom, side and middle of the bed, due to the inclined arrangement of the bed, the airflow suspension dispersion effect of the air supply system and the effect of the conveying stirring device, the fine powder gradually forms a layer from the feed port and moves to the discharge port into the air pipe; the main hot air rises through the heat recovery air port to recover, part of the hot air enters the air pipe, and the balance wall isolates the heat recovery air and the discharge exhaust air; the present application can improve the rapid cooling and heat exchange rate, improve the product quality, improve the heat recovery efficiency, and the cooling device installation mode is simple and has small wear.

Description

Technical Field

[0001] This invention relates to the field of high-temperature fine powder cooling and heat recovery technology, and more specifically, to a convective rapid cooling and heat recovery method for high-temperature fine powder. Background Technology

[0002] In industries such as coal, chemical, and metallurgy, it is often necessary to cool high-temperature fine powders (particle size 1~1000μm) and maximize heat recovery. Currently, there are three main cooling methods for these fine powders: indirect cooling, semi-direct cooling, and suspension cooling, with cooling media including water cooling and air cooling.

[0003] Indirect cooling methods involve the fine powder not directly contacting the cooling medium. These indirect heat exchange methods include plate and rotary types. The advantage of this method is that the fine powder is unaffected by the cooling medium, but it also has significant drawbacks: First, the cooling 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 rates and poor rapid cooling, affecting product quality (rapid cooling is beneficial for improving product whiteness and reducing microcracks). Third, the cooling medium experiences limited temperature rise after heat exchange, resulting in low heat recovery value and difficulty in direct application to the firing system, leading to low heat recovery efficiency and high energy consumption. Fourth, the fine powder tends to agglomerate on the heat exchange surface, reducing long-term heat exchange stability. Fifth, direct contact and relative movement between the fine powder and the heat exchange surface cause equipment wear, affecting long-term stable system operation and increasing subsequent maintenance costs.

[0004] In semi-direct cooling methods, the fine powder material is in semi-direct contact with the cooling medium. That is, when using semi-direct heat exchange, the partially contacting cooling medium is air, while the non-contacting cooling medium is mostly water. The cooling water only acts on the equipment casing for cooling and indirect heat transfer. The main motion of this type of equipment is rotary, with the fine powder material rotating and reciprocating in an agglomerated manner. The contact between the cooling air and the fine powder material mainly occurs on the surface of the powder, with minimal heat exchange between the cooling air and the interior of the powder, and no convective heat exchange between the powder and the air. Furthermore, the amount of semi-direct contact cooling air is limited, relying mainly on heat dissipation and indirect water cooling. This rotary semi-direct cooling heat exchange method has the following disadvantages: the contact area between the fine powder material and the cooling air is small, resulting in relatively low heat exchange efficiency and a relatively slow rapid cooling rate; the cooling effect depends on indirect cooling water, leading to a still relatively low overall cooling rate; and due to the low heat recovery efficiency of the cooling water and cooling air, the temperature after heat exchange is low, resulting in low heat recovery value, leading most existing production lines to not even recover and utilize this portion of heat, thus causing high energy consumption.

[0005] In suspension cooling, fine powder is fully in contact with and suspended by the cooling medium, achieving both suspension and heat exchange. This results in thorough gas-solid mixing, a large heat exchange surface, and excellent rapid cooling. However, some drawbacks exist: First, in suspension cooling, the fine powder and cooling air exchange heat in a single, simultaneous process without a linear gradient, often requiring multiple stages of suspension cooling and separation to achieve complete cooling. Second, suspension cooling devices are relatively tall, making layout and installation difficult. Third, for fine powders, suspension separators are inefficient, dust separation is challenging, and internal circulation is severe. Fourth, cyclone separation involves extremely high wind speeds, which can lead to additional wear and impurities, affecting system lifespan and product purity and quality.

[0006] Fine powders exhibit different fluidization characteristics compared to ordinary granular powders. First, most fine powders belong to Geldart A and C categories, which are prone to agglomeration. Their strong van der Waals forces make fluidization extremely difficult, easily leading to channeling and stagnation, resulting in abnormal fluidization phenomena. This can cause localized overheating or caking of the material bed, affecting heat exchange efficiency. Second, once fine powders detach from agglomerates, they are easily carried away by cooling air, impacting the normal operation of subsequent heat recovery systems.

[0007] Existing methods for cooling fine powders mainly have the following problems: 1. In the existing indirect heat exchange technology, the cooling heat exchange efficiency is poor, the cooling requires a large contact surface, occupies a large space, and has a high investment.

[0008] 2. In the existing indirect heat exchange and semi-direct heat exchange technologies, indirect heat exchange results in slow cooling rate and poor rapid cooling effect of fine powder, which affects the product quality of fine powder.

[0009] 3. In the existing indirect heat exchange and semi-direct heat exchange technologies, the value of heat recovery is not great, especially since it is difficult to be directly recovered and utilized by the firing system. The heat recovery efficiency is low and the energy consumption is high.

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

[0011] 5. In existing indirect heat exchange technologies, the heat exchange surfaces experience wear, which affects long-term stable operation and increases subsequent maintenance costs.

[0012] 6. Existing suspension cooling heat exchange technologies are difficult to arrange and install, and are prone to additional wear and impurities, affecting the service life of the system and the purity and quality of the products.

[0013] Therefore, current technologies lack cooling methods that take into account the rapid cooling effect of fine powder, heat exchange efficiency, heat recovery value, simple installation of cooling devices, and reduced device wear. There are no devices or production lines in the existing technology that allow 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 convection rapid cooling heat recovery method to solve the problems of existing fine powder cooling methods that cannot simultaneously take into account the rapid cooling effect, heat exchange efficiency, heat recovery value, cooling device installation and device wear.

[0015] This invention is achieved using the following technical solution: This invention provides a method for convective rapid cooling and heat recovery of high-temperature fine powder, which involves cooling the high-temperature fine powder and recovering its heat using a convective rapid cooling and heat recovery device. The high-temperature fine powder convection rapid cooling heat recovery device includes a shell, inside which a material bed is provided. The material bed has an inlet and a outlet at both ends, and the material bed is arranged at an inclination toward the outlet. The high-temperature fine powder convection rapid cooling heat recovery device is equipped with an air supply system. The air supply system is used to provide bottom air supply, side air supply and middle air supply. Bottom air supply is used for convection rapid cooling and heat exchange with the material layer to form a strong direct convection rapid cooling and heat exchange process. Side air supply and middle air supply are used to reduce the temperature around the fine powder to form a temperature gradient, which helps to achieve heat exchange and cooling of the fine powder. The high-temperature fine powder convection rapid cooling heat recovery device is equipped with a porous settling plate. 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, so that it settles into the material layer. The material bed is equipped with a conveying and agitating device, which is used to homogenize and convey materials; A flow stabilizing bed is arranged below the conveying and agitating device. Cooling air from the bottom enters the material bed through the flow stabilizing bed, which is used to equalize and stabilize the airflow. A heat recovery air inlet is provided on the top of the casing for recovering hot air; The discharge port is connected to an air duct for exhaust ventilation during material discharge. A balance wall is arranged inside the shell, in front of the discharge port. The bottom of the balance wall is flush with the top surface of the material layer. The balance wall is used to isolate the heat recovery air and the discharge exhaust air, control the balance of hot air pressure on both sides, reduce the mutual air path influence, and enhance the stability and operability of the whole device. A reflective settling plate is installed in front of the discharge port. The reflective settling plate is used to reflect and slow down the highly fluid powder layer in front of the discharge port, reduce the impact on the downstream, and at the same time reduce the suspended dust caused by the impact, and promote the rebound and settling of the material. High-temperature fine powder convection quenching heat recovery methods include: High-temperature fine powder enters the feed bed through the inlet. Cooling air enters the feed bed from the bottom, sides, and middle. Based on the balance calculation of the fine powder's gravity and drag force, the critical fluidization velocity and bubbling velocity are determined. The bottom air supply volume and critical wind speed are then controlled accordingly. The cooling wind velocity per unit cross-section of the feed bed is less than 0.4 m / s, and the cooling load per unit area is less than 15 t / m². 2 This process brings the fine powder to a critical fluidization state, where the powder on the bed is in a near-fluidized state of dense-phase conveying and cooling, resulting in a stable fluidized material layer. Bottom air supply and material layer convect and rapidly cool each other; side air supply and middle air supply pass over the surface of the material layer for 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 airflow suspension and dispersion effect of the air supply system, and the action of the conveying and agitating device, the fine powder gradually forms a material layer from the feed inlet and moves to the discharge outlet to enter the air duct. Some of the fine powder separates from the agglomerates during fluidization and conveying. It is intercepted and agglomerated by the porous settling plate and settles into the material layer. Before the material layer enters the discharge outlet, the fine powder air collides and reflects with the reflective settling plate. The main hot air rises and is recovered through the heat recovery air inlet, and some hot air enters the air duct. The balance wall isolates the heat recovery air and the discharge exhaust air.

[0016] Among them, near-fluidization morphology refers to the morphology that a material exhibits when it reaches the critical fluidization state.

[0017] Based on the numerous advantages of direct convection linear gradient heat transfer, this invention improves the rapid cooling heat transfer rate, enhances product quality, increases heat recovery efficiency, and reduces energy consumption when applied to firing systems. It has significant strategic importance in environmental protection, energy conservation, and carbon reduction, and can also contribute to achieving the goal of sustainable green circular development. It has important scientific and technological breakthroughs and practical application value.

[0018] As a preferred technical solution: Calculate the critical fluidization rate using the Wen-Yu formula. :

[0019] in, Critical fluidization velocity, in m / s. The dynamic viscosity of the powder is expressed in Pa·s. Density of the gas, in kg / m³. The equivalent diameter of the powder particles, in meters (m). Density of powder particles, in kg / m³. This is the acceleration due to gravity, in meters per second (m / s). .

[0020] This formula is applicable to fine powders or granular systems with low Reynolds numbers (Re ≤ 20). Fluid type: Applicable to gas-solid fluidized beds, especially for high-viscosity fluids or fine particle scenarios. Limitations: The prediction error is relatively large for wide-sized particles (wide particle size distribution), requiring experimental correction. For high Reynolds numbers (Re > 1000), other formulas (such as the Ergun equation) must be used.

[0021] As a preferred technical solution: The entire high-temperature fine powder convection rapid cooling heat recovery device is long, thin, and tall, forming a narrow cooling channel that facilitates the formation of a stable material flow.

[0022] As a preferred technical solution: The height from the material bed to the heat recovery port is greater than 5m, which is conducive to the re-aggregation, growth and settling of suspended dust, thereby reducing the dust concentration in the heat recovery air.

[0023] As a preferred technical solution: High-temperature fine powder enters the material bed through the feed inlet via the feeding device. The feeding device is connected to the feed inlet and adopts a double V-bend type feeding device, which includes an upper V-shaped section, a middle straight section and a lower V-shaped groove. The larger opening end of the V-shaped section is used to collect the high-temperature fine powder coming from upstream, and the smaller opening end of the V-shaped section is connected and communicated with the straight section. The straight section bends relative to the V-shaped section and is arranged at an angle to form a feeding ramp. The cross-sectional area of ​​the straight section allows the maximum designed material flow to pass through. After the high-temperature fine powder is collected, it enters the feeding ramp to avoid the fine powder directly impacting the convection rapid cooling heat recovery device and reduce the dispersion of materials. The larger opening of the V-groove is connected to the feed inlet, and the smaller opening of the V-groove is connected to and communicates with the straight section. The V-groove is used to disperse and evenly distribute fine powder.

[0024] As a preferred technical solution: A gate-type airlock valve is installed at the straight section to control the cross-sectional area of ​​the straight section.

[0025] As a preferred technical solution: The air supply system includes cooling air inlet boxes and multi-faceted air inlet devices. Multiple cooling air inlet boxes are arranged at the bottom of the material bed. The cooling air inlet boxes are installed at the bottom of the stable flow bed. The multi-faceted air inlet devices are installed at the middle position on both sides of the tail of the shell. The cooling air inlet boxes adopt pulse air supply boxes.

[0026] The pulse air supply box supplies air from the bottom of the material bed, and the powder undergoes a stepped convection forced heat exchange; the pulse air supply box intermittently supplies air in zones, which can promote fluidization while reducing the dust carried away by suspension separation.

[0027] For special powders, the agglomeration force between Geldart C-type fine powders is extremely strong, far exceeding the gravity of the powder particles. Cold-state experiments show that, under controlled airflow velocity (less than 0.4 m / s), the fine powder exhibits localized bubbling fluidization and is lifted, but most of the powder re-agglomerates and returns to the bed, forming near-circular bubbling. Therefore, very little fine powder is suspended and carried away during small-scale bubbling fluidization. Controlling the cooling airflow velocity and using intermittent air supply increases the effect of sedimentation and re-agglomeration, ultimately forming a dense-phase fluidization and conveying pattern, creating a relatively stable flowing material layer, and reducing dust segregation and suspension at the source.

[0028] As a preferred technical solution: The porous settling plate adopts a V-shaped porous settling plate, which has a V-shaped cross section and its opening faces the material layer. The V-shaped porous settling plate has multiple holes.

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

[0030] As a preferred technical solution: The steady flow bed includes, from bottom to top, a first layer of air supply plate, a second layer of air distribution ceramic balls, a third layer of porous air distribution plate, and a material box; The first layer of air supply plate has holes and a labyrinth seal is formed on it; the second layer of uniform air distribution ceramic balls has a variety of different particle sizes. The third layer of porous air distribution plate has multiple holes with inverted funnel-shaped openings. The diameter of the upper cylinder of the hole is smaller than the diameter of the funnel opening, which creates a Venturi effect, reduces the pressure in the contact area of ​​fine powder, promotes the formation of a stable material layer of fine powder, reduces suspension boiling and dispersion, and enhances 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 installed between the steady flow bed and the pulse air supply box.

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

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

[0033] As a preferred technical solution: Heat recovery air outlets include high-temperature heat recovery air outlets and low-temperature heat recovery air outlets.

[0034] As a preferred technical solution: The reflective settling plate is arranged at a 45-degree angle to the material layer.

[0035] As a 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. This invention achieves extremely fast cooling and heat exchange rates by directly convecting heat between cooling air and powder, resulting in high-quality products. At the same time, it maximizes heat recovery and utilization in the firing system, resulting in significant energy saving, consumption reduction, and emission reduction effects.

[0037] 2. This invention integrates the functions of material collection, airlocking, and material distribution, which can reduce dispersion and separation, stabilize airflow, 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 in the quenching device.

[0038] 3. To address the challenge of fluidizing fine powders, this invention designs multiple sets of conveying and agitating devices to enhance agitation, increase gas-solid porosity, break up powder agglomerates, and maximize the elimination of abnormal fluidization phenomena such as channeling and throttling. At the same time, the agitating devices can also convey the powder forward to complete cascade convective heat transfer.

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

[0040] 5. Due to the easily suspended nature of fine powder, this invention employs 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 air velocity. This controls the suspension and separation of the fine powder and reduces the impact on hot air recovery. Furthermore, in the remaining cooling areas unaffected by this, the cooling air velocity and volume are increased to enhance the cooling heat exchange effect and heat recovery efficiency.

[0041] 6. The reflective settling plate of the present invention reduces the velocity of the fine powder flow and causes refraction, while increasing the settling of the suspended fine powder, which is beneficial for further discharge.

[0042] 7. This invention employs multiple sets of V-shaped porous settling plates and a cleaning device. The V-shaped porous settling plates have a V-shaped cross-section, increasing the contact area with the surface fine powder. Simultaneously, the settling plates have pores approximately 3-10 times the diameter of the dust particles, allowing airflow to pass through. The suspended fine powder particles agglomerate under the obstruction of the porous settling plates, enhancing the agglomeration and settling effect of the dust and further reducing the concentration of suspended dust carried away. Furthermore, the cleaning device can automatically and periodically clean the blocked pores, supplement cooling airflow, lower the ambient temperature, create a temperature gradient, and enhance 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 sets of heat recovery ports, which promotes the formation of gradient heat exchange on the material layer, achieves a more efficient rapid cooling heat exchange effect with minimal cooling air volume, and promptly removes hot air and applies it to the heat recovery system to achieve energy saving, consumption reduction and emission reduction.

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

[0045] 10. Fine powder and some 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 rapid cooling heat recovery device of the present invention has a simple layout and installation method, does not involve extremely high wind speed, and avoids additional wear and impurities. Attached Figure Description

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

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

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

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

[0051] Figure 5 for Figure 1 A cross-sectional view along the AA direction.

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

[0053] Figure 7 This is an enlarged view of the vent hole described in this invention.

[0054] Figure 8 The image shows the simulation results of the high-temperature fine powder convection rapid cooling heat recovery device described in this invention.

[0055] Icons: 1-Feeding device, 101-V-shaped section, 102-Straight section, 103-V-shaped groove, 2-Airlock 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-Clean air device, 10-V-shaped perforated settling plate, 11-Balancing wall, 12-Reflective settling plate, 13-Discharge port, 14-Air duct, 15-Conveying and stirring device, 16-Stable flow bed, 16.1-First layer air supply plate, 16.2-Second layer air distribution ceramic balls, 16.3-Third layer perforated air distribution plate, 16.4-Material box, 16.5-Gravity automatic flow valve, 17-Shell, 18-Material bed. Detailed Implementation

[0056] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of 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 some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0057] Example 1 This embodiment proposes a high-temperature fine powder convection quenching and heat recovery method. The method utilizes a high-temperature fine powder convection quenching and heat recovery device to cool and recover the heat from the high-temperature fine powder. For example... Figures 1-7 As shown, the high-temperature fine powder convection rapid cooling heat recovery device includes a shell 17, inside which a material bed 18 is arranged. The entire high-temperature fine powder convection rapid cooling heat recovery device is long, thin, and tall, forming a narrow cooling channel. An inlet and a outlet 13 are respectively provided at both ends of the material bed 18. The inlet is connected to a feeding device 1, through which the high-temperature fine powder enters the material bed 18 to form a material layer. The fine powder is cooled in the material bed 18 and then discharged from the outlet 13. The outlet 13 is connected to an air duct 14 for material discharge and ventilation.

[0058] The feeding device 1 adopts a double V-bend type feeding device 1, which includes an upper V-shaped section 101, a middle straight section 102 and a lower V-shaped groove 103. The larger opening end of the upper V-shaped section 101 is used to collect the high-temperature fine powder material from upstream, and the smaller opening end of the upper V-shaped section 101 is connected to and communicates with the straight section 102. The straight section 102 bends relative to the upper V-shaped section 101 and is arranged at an inclination to form a feeding ramp. The cross-sectional area of ​​the straight section 102 allows the maximum designed material flow to pass through. After the high-temperature fine powder is collected, it enters the feeding ramp, avoiding the fine powder from directly impacting the convection rapid cooling heat recovery device, thereby reducing the dispersion of materials. The larger opening end of the lower V-shaped groove 103 connects to the feed inlet, while the smaller opening end connects to and communicates with the straight section 102. The height of the V-shaped groove 103 is less than the height of the V-shaped section 101. The V-shaped groove 103 is used to disperse and evenly distribute fine powder. The double-V-shaped feeding device 1 adopts a double-V design, which facilitates material collection and distribution. The V-shaped section 101 is used to receive the upstream rotary kiln equipment. A baffle plate airlock valve 2 is installed at the straight section 102 to control the cross-sectional area of ​​the straight section 102, thereby controlling the impact of fluctuations caused by air pressure on the upstream and downstream equipment. This achieves material sealing and minimizes the mutual influence between the upstream and downstream equipment. At the same time, due to the sealing effect of the airlock valve 2, the material can be dispersed and distributed into the convection-type rapid cooling heat recovery device.

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

[0060] The device is equipped with an air supply system that 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, multiple cooling air inlet boxes are arranged at the bottom of the material bed 18. In this 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 one 3, pulse air supply box two 4, and pulse air supply box three 5. The air supply at the bottom of the material bed 18 enables the fine powder to directly convect and exchange heat with the cooling air, forming a strong direct convection rapid cooling and heat exchange process, thereby obtaining a rapid-cooled 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 from the pulse air supply box 3, pulse air supply box 4, pulse air supply box 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 tail of the housing 17. The multi-faceted air inlet device 6 can directly supply air from both sides and the middle part of the material layer. This part of the cooling air sweeps across 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 and separation of fine powder can be avoided at the same time.

[0063] Preferably, the multi-faceted air intake 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 sets of air inlet boxes and directly convects and exchanges heat with the fine powder through the steady flow bed 16, causing the fine powder to be in a micro-fluidized boiling state, thereby reducing the suspension and separation of the fine powder from the source. Other side air supply is used to reduce the temperature around the fine powder, forming a temperature gradient, and working together to achieve heat exchange and cooling of the fine powder.

[0065] This invention employs a combined precise zoned air supply mode with multiple bottom air supply and multiple surface air supply to ensure sufficient cooling air volume and control different reasonable cooling air velocities per unit cross section.

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

[0067] The convection-type quench and quench heat recovery device is internally equipped with multiple V-shaped porous settling plates 10. The V-shaped porous settling plates 10 have a V-shaped cross-section, with their openings facing the material bed. Both ends of the V-shaped porous settling plates 10 are fixedly connected to the shells 17 on both sides of the material bed 18. The surface area of ​​the V-shaped porous settling plates 10 is much larger than the area of ​​the material bed 18. This design helps increase the contact area between the suspended material and the air, reduces the cross-sectional wind speed, and increases the interception and agglomeration settling capabilities. Under the influence of reflection and van der Waals forces, most of the suspended dust settles and agglomerates here, thus settling and re-entering the stable material bed.

[0068] The V-shaped porous settling plate 10 has multiple holes, the diameter of which is 3-10 times the diameter of the fine powder D50, allowing heat recovery air to pass through.

[0069] Preferably, a cleaning device 9 is installed on the V-shaped porous settling plate 10. When the agglomerated dust particles block the holes on the V-shaped porous settling plate 10, the cleaning device 9 can be used to clean it automatically at regular intervals. In addition, the cleaning device 9 also serves to supplement cooling air, reduce the ambient temperature, form a temperature gradient, and enhance the cooling and heat exchange effect.

[0070] The structure of the cleaning device 9 is existing technology and will not be described in detail here. It is sufficient to achieve air supply and cleaning, and typically includes a compressed air nozzle and connecting pipeline.

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

[0072] Multiple sets of conveying and agitating devices 15 are installed on the material bed 18. The conveying and agitating 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 agitating devices 15 forcibly agitate the material layer to enhance the homogenization and conveying of the material in the material bed 18, and convey the fine powder from the feed end to the discharge end. The forced agitation eliminates channeling and slugging phenomena formed during the fluidization process of the fine powder, improves the fluidization performance of the fine powder, and promotes convective heat transfer.

[0073] The conveying and agitating 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 interaction force between fine powder is much greater than its gravity, the gaps between particles are very small, the air permeability is low, and uneven fluidization and short circuits are easy to occur. Therefore, the present invention designs multiple sets of conveying and agitating devices 15 to continuously agitate the material layer and promote the uniform fluidization and cooling of fine powder.

[0074] Among them, the conveying and stirring device 15 is existing technology, and its structure will not be described in detail here. For example, it can adopt the Chinese utility model patent "A mechanism for converting linear motion into multi-output oscillating sweeping motion" with publication number CN20441653U. It is not limited to adopting the above-mentioned mechanism. Other structures that can realize the conveying and homogenization of fine powder can also be used.

[0075] A stable flow bed 16 is arranged below the conveying and agitating device 15. The cooling air inlet box is installed at the bottom of the stable flow bed 16. The bottom cooling air enters the material bed 18 after passing through the stable flow bed 16.

[0076] Preferably, the steady flow bed 16 includes a first layer of air supply plate 16.1, a second layer of air distribution ceramic balls 16.2, a third layer of porous air distribution plate 16.3, and a material box 16.4 arranged sequentially from bottom to top; The first air supply plate 16.1 has a large opening ratio (20-40%) to reduce the air supply velocity and reduce the 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. That is, the first air supply plate 16.1 is used to ensure low-speed air supply and that the labyrinth seal does not leak material. The second layer of uniform airflow ceramic balls 16.2 has a variety of different particle sizes, making the cooling air supply more uniform and further optimizing the airflow distribution; The third layer of porous air distribution plate 16.3 has multiple inverted funnel-shaped vents. The upper cylindrical diameter Φ2 of the vent is smaller than the funnel diameter Φ1, which creates a Venturi effect, reduces the pressure in the contact area of ​​fine powder, promotes the formation of a stable material layer of fine powder, reduces suspension boiling and dispersion, and enhances the air supply and flow stabilization effect. The material box 16.4 is made of heat-resistant steel with a grid structure, which facilitates the formation of a relatively stable dead material layer to stabilize the powder layer; In addition to the above-mentioned effects of uniform airflow and stable flow, the steady flow bed 16 can also balance the resistance ratio of the upper and lower parts of the material layer, avoid top-heavy conditions, and facilitate the operation of cooling air.

[0077] Preferably, a gravity-type automatic flow valve 16.5 is installed 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 changes caused by the material distribution, reasonably distribute the cooling air volume, prevent the cooling air from short-circuiting, and promote the fluidization and heat exchange of the powder.

[0078] A reflective settling plate 12 is installed at the discharge port 13 where the material layer enters. The reflective settling plate 12 is fixedly installed on the shell 17. The reflective settling plate 12 is arranged at a 45-degree angle with the material layer. It reflects and slows down the highly fluid powder layer in front of the discharge port 13, reducing the impact on the downstream and reducing the suspended dust caused by the impact, thus promoting the rebound and settling of the material.

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

[0080] The top of the shell 17 is equipped with a high-temperature heat recovery air inlet 7 and a low-temperature heat recovery air inlet 8. Multiple sets of heat recovery air inlets are used to recover and reuse the heat-exchanged air in the firing system, while controlling the dust concentration within a reasonable range. This invention achieves efficient cooling through direct convection heat exchange between cooling air and fine powder, and recovers the heat-exchanged air, reintroducing it into the firing system for reuse, thus achieving efficient cascade heat exchange and heat recovery. The height from the material bed 18 to the heat recovery inlet is greater than 5m, which is conducive to the re-agglomeration and settling of suspended dust, reducing the dust concentration in the heat recovery air.

[0081] A balance wall 11 is arranged inside the housing 17. The top of the balance wall 11 is fixedly connected to the housing 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. It forcibly isolates and disconnects 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 mutual air path influence, and enhance the stability and operability of the entire device.

[0082] After the fine powder enters the material bed 18, under the dual action of cooling air suspension fluidization (multi-face air supply) and 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 the subsequent process, completing the entire material-gas cooling and heat exchange process. A very small amount of powder is suspended and enters the heat recovery system to realize material-gas heat exchange and separation.

[0083] The high-temperature fine powder convection rapid cooling heat recovery method includes the following steps: High-temperature fine powder enters the material bed 18 through the double V-bend type feeding device 1. Simultaneously, cooling air enters the material bed 18 from pulse air supply box 1 3, pulse air supply box 2 4, pulse air supply box 3 5, and multi-face air inlet device 6. Based on the balance calculation of gravity and drag force of the fine powder, the critical fluidization velocity and jetting velocity of different fine powders are obtained. Different cooling air volumes are supplied to different air inlets to control the critical air velocity. The critical fluidization state of the fine powder is obtained through controllable critical air velocity, avoiding the fine powder from completely entering the boiling suspension and separation state, thereby obtaining a stable fluidized material layer. The multi-face air inlet device 6 directly supplies air from both sides and the middle part of the material layer. This part of the cooling air sweeps across the surface of the material layer, exchanging heat on the surface of the material layer and forming a strong temperature gradient. According to Newton's law of cooling, a large temperature gradient helps to achieve cooling heat exchange. The auxiliary role of the multi-face 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 effect of airflow suspension and dispersion, and under the action of the conveying and stirring device 15, the fine powder gradually forms a material layer from the feed inlet and moves to the discharge outlet 13, and finally enters the air duct 14 to complete the transmission of the main fine powder. Since the particle size distribution (PSD) of fine powder is often normally distributed, there are many ultrafine powders with extremely small particle sizes. These fine powders are prone to detach from agglomerates and separate during fluidization and conveying. This small portion of separated fine powder moves upward under the action of hot air and collides with the V-shaped porous settling plate 10, realizing momentum conversion, deceleration, and agglomeration with other powders, eventually settling back onto the material layer. The suspended material air is intercepted and agglomerated by the V-shaped porous settling plate 10. When the agglomerated dust particles block the holes on the V-shaped porous settling plate 10, they are automatically cleaned periodically by the cleaning device 9. The cleaning device 9 also serves as a supplementary cooling air. 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 some hot gas enter the air duct 14. The main hot air rises into the high-temperature heat recovery air inlet 7 and the low-temperature heat recovery air inlet 8. After direct convection heat exchange, the cooling air rises directly into the heat recovery system in a timely manner, forming a linear gradient heat exchange. This is beneficial for the subsequent material layer to form a large temperature gradient, which enhances the heat exchange effect (the heat exchange effect is significantly stronger than one-time mixing heat exchange, and the cooling air volume can be greatly reduced). It can also realize the recovery and utilization of different levels of temperature.

[0084] In the entire convection quenching and heat recovery device, a pressure balancing wall 11 is installed, with its bottom flush with the top surface of the material layer. This wall 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 The diagram shows the simulation results of this invention. Through coupled simulation of the flow field and temperature field of high-temperature fine powder, this invention clearly presents the dynamic flow characteristics and heat exchange behavior of the material layer within the convection quenching device. Experimental verification shows that the high-temperature fine powder convection quenching heat recovery method and device proposed in this invention, by optimizing the multi-group, multi-faceted air supply configuration, enhancing agitation to improve fluidization, and configuring various settling devices, solves the problems of poor fluidization of fine powder at low airflow rates and easy suspension at high airflow rates. This provides key technical support for direct convection heat transfer and heat recovery of fine powder, and has significant engineering application value and industrialization prospects.

[0086] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for convective rapid cooling and heat recovery of high-temperature fine powder, characterized in that: The high-temperature fine powder is cooled and its heat is recovered by a high-temperature fine powder convection rapid cooling heat recovery device. The device includes a housing, inside which is a material bed. The material bed has an inlet and a outlet at both ends, and the material bed is arranged at an inclination toward the outlet. The device is equipped with an air supply system that provides air supply from the bottom, sides, and center. The device is equipped with a porous settling plate located above the material layer. The material bed is equipped with a conveying and agitating device; A stabilizing bed is arranged below the conveying and agitating device, and the bottom cooling air enters the material bed through the stabilizing bed; The steady flow bed includes, from bottom to top, a first layer of air supply plate, a second layer of air distribution ceramic balls, a third layer of porous air distribution plate, and a material box; The first layer of air supply plate has holes and a labyrinth seal is formed on it; the second layer of uniform air distribution ceramic balls has a variety of different particle sizes. The third layer of porous air distribution plate has multiple holes with inverted funnel-shaped openings. The diameter of the upper cylinder of the hole is smaller than the diameter of the funnel opening, which creates a Venturi effect, reduces the pressure in the contact area of ​​fine powder, promotes the formation of a stable material layer of fine powder, reduces suspension boiling and dispersion, and enhances 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 installed between the steady flow bed and the bottom air supply; A heat recovery air vent is located at the top of the casing; The discharge port is connected to an air duct; A balancing wall is arranged inside the shell, and the balancing wall is located in front of the discharge port. The bottom of the balancing wall is flush with the top surface of the material layer. A reflective settling plate is installed in front of the discharge port; The methods include: High-temperature fine powder enters the feed bed through the inlet. Cooling air enters the feed bed from the bottom, sides, and middle. Based on the balance calculation of the fine powder's gravity and drag force, the critical fluidization velocity and bubbling velocity are determined. The bottom air supply volume and critical wind speed are then controlled accordingly. The cooling wind velocity per unit cross-section of the feed bed is less than 0.4 m / s, and the cooling load per unit area is less than 15 t / m². 2 This process brings the fine powder to a critical fluidization state, where the powder on the bed is in a near-fluidized state of dense-phase conveying and cooling, resulting in a stable fluidized material layer. Bottom air supply and material layer convect and rapidly cool each other; side air supply and middle air supply pass over the surface of the material layer for 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 airflow suspension and dispersion effect of the air supply system, and the action of the conveying and agitating device, the fine powder gradually forms a material layer from the feed inlet and moves to the discharge outlet to enter the air duct. Some of the fine powder separates from the agglomerates during fluidization and conveying. It is intercepted and agglomerated by the porous settling plate and settles into the material layer. Before the material layer enters the discharge outlet, the fine powder air collides and reflects with the reflective settling plate. The main hot air rises and is recovered through the heat recovery air inlet, and some hot air enters the air duct. The balance wall isolates the heat recovery air and the discharge exhaust air.

2. The high-temperature fine powder convection rapid cooling heat recovery method according to claim 1, characterized in that: High-temperature fine powder enters the material bed through the feed inlet via the feeding device. The feeding device is connected to the feed inlet and adopts a double V-bend type feeding device, which includes an upper V-shaped section, a middle straight section and a lower V-shaped groove. The larger opening end of the V-shaped section is used to collect the high-temperature fine powder coming from upstream, and the smaller opening end of the V-shaped section is connected and communicated with the straight section. The straight section bends relative to the V-shaped section and is arranged at an angle to form a feeding ramp. The cross-sectional area of ​​the straight section allows the maximum designed material flow to pass through. After the high-temperature fine powder is collected, it enters the feeding ramp to avoid the fine powder directly impacting the convection rapid cooling heat recovery device and reduce the dispersion of materials. The larger opening of the V-groove is connected to the feed inlet, and the smaller opening of the V-groove is connected to and communicates with the straight section. The V-groove is used to disperse and evenly distribute fine powder.

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

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

5. The high-temperature fine powder convection quenching and heat recovery method according to claim 1, characterized in that: The porous settling plate adopts a V-shaped porous settling plate, which has a V-shaped cross section and its opening faces the material layer. The V-shaped porous settling plate has multiple holes.

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

7. The high-temperature fine powder convection rapid cooling heat recovery method according to claim 1, characterized in that: Heat recovery air outlets include high-temperature heat recovery air outlets and low-temperature heat recovery air outlets.

8. The high-temperature fine powder convection quenching and heat recovery method according to claim 1, characterized in that: The reflective settling plate is arranged at a 45-degree angle to the material layer.

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

Images