A double-stirred fluidized bed

Abstract

The present application relates to a double-stirring fluidized bed, belonging to the field of particle synthesis or particle fluidization technology processing. The present application comprises a fluidized bed body device and a stirring device, wherein the stirring device is a stirring device with exhaust holes and / or a side feeding stirring device. The present application realizes the functions of side continuous feeding and preventing particle escape through two stirring systems, and also improves the fluidization quality in the bed. The stirring paddle is installed at a certain angle on the side of the fluidized bed, and the solid particles are sprayed into the fluidized bed bed layer from the internal passage of the hollow stirring shaft; the axial flow stirring paddle is installed on the upper part of the fluidized bed bed layer, which inhibits the fine solid particles uplifted by the bubble phase breaking and bed vibration, the outlet mode of the fluidizing gas is changed to be discharged from the stirring shaft, the gas carrying fine particles is forced to pass through the stirring shaft sleeve, the resistance of the particles to the wall surface is increased, and at the same time, under the action of the centrifugal force of the stirring paddle, the separation of the fine particles and the gas is realized, and the fine particles fall back into the fluidized bed.

Description

Technical Field

[0001] This invention belongs to the field of particle synthesis or particle fluidization technology, and specifically relates to a dual-stirred fluidized bed. Background Technology

[0002] Fluidized beds are widely used in petroleum, chemical, biological, pharmaceutical, and metallurgical industries due to their simple structure and good heat and mass transfer conditions. The main components of a fluidized bed include the bed body, inlet pipe, gas distribution plate, feed pipe, and exhaust pipe. During operation, fluidizing gas enters the bed body through a conical inlet at the bottom and forms a bubble phase through the gas distribution plate. The upward movement of these bubbles causes the particles within the bed to circulate. In actual operation, excessively large bubble sizes often cause severe pressure fluctuations, leading to undesirable phenomena such as channeling or surging. Furthermore, in high-temperature systems, particle surfaces become sticky, easily leading to particle adhesion. These particles with surface adhesion characteristics readily agglomerate during collisions, forming large particles that affect the stable operation of the material bed. However, the direct adhesion force between particles is difficult to break through non-contact external fields. Simultaneously, intense bed fluctuations cause collision friction between particles. To reduce bubble-induced bed fluctuations, a stirrer is often added to the fluidized bed to forcibly break up bubbles, reduce bubble size within the bed, and improve the quality of gas-solid fluidization. In actual industrial production, the size of solid particles cannot be uniform. This non-uniformity is caused by the particle characteristics of the raw materials or by the collision and friction between particles and the friction between particles and the fluidized bed wall, resulting in small particles in the system. These small particles are easily carried out of the fluidized bed by the gas, increasing the workload of subsequent cyclone separation and reducing fluidization efficiency.

[0003] Patent CN202223163568.4 discloses a fluidized bed reactor, including a reactor body with an inlet and an outlet. The inlet is located on both sides of the top of the reactor body, and the outlet is located on the reactor body. The reactor body also includes a reaction zone and a feeding zone. The feeding zone is located on both sides of the reaction zone and is connected to the inlet and the reaction zone. A stirring device is configured in the reaction zone. By setting the inlet and feeding zone on both sides of the reaction zone and setting the feeding baffle at the position where the reaction zone and the feeding zone are connected, feeding is convenient and the material can be fed evenly when entering the reaction zone, resulting in a more thorough reaction. The stirring device ensures that the material reacts thoroughly in the reaction zone and rises with the stirring airflow.

[0004] Patent CN202310009811.7 discloses an iron ore fluidized bed melting reduction device and method utilizing the adhesion effect. Multiple sets of high-velocity differential stirring and jetting fluidized bed groups are arranged in parallel in the upper part of the oxygen-enriched high-temperature air or pure oxygen melting reduction furnace. High-temperature reformed hydrogen-rich coal gas is directly mixed with cold circulating coal gas as the reducing gas. Each group includes three or more fluidized beds connected in series. Each fluidized bed stage includes an upper expanding furnace body, a tube shaft family, multi-layer conical annular guide plates, a frame paddle, guide plate scrapers, an air inlet mechanism, and a discharge mechanism. The conical annular guide plates are equivalent to low-resistance distribution plates, increasing the number of sub-stages of the fluidized bed and making it more conducive to counter-current processes. The gas velocity in the middle and lower parts of this device is very high, allowing the adhered blocks to still be well fluidized and directly discharged into the melting reduction furnace. Utilizing the adhesion effect and adding hydrogen-rich or even pure hydrogen reducing agents improves the pre-reduction effect, avoids the problems of the blast furnace softening zone, and improves energy utilization and process stability.

[0005] Patent CN202310010710.1 discloses a hydrogen-rich reduction high-velocity differential stirred fluidized bed reactor, including a furnace body. The furnace body contains components such as guide plates, frame paddles, and scrapers. The airflow velocity at the lower part of the furnace body is 3 to 20 times that at the upper part, ensuring that fine mineral powder (at the top), agglomerated mineral powder, and large mineral powder particles (at the bottom) maintain a good fluidized reduction state. The rotating guide plates function as a stirring paddle, feeding paddle, and gas distribution paddle. The guide plates and frame paddles, along with the furnace wall and scrapers, all generate relative motion with the guide plates, effectively cleaning and breaking up the mineral powder adhering to the walls. The low pressure differential of the guide plates allows large mineral powder particles and agglomerated particles to be discharged downwards without clogging.

[0006] Patent CN202223324993.7 discloses a fluidized bed reactor with a stirring function, comprising a reaction vessel and a stirring mechanism. This patent uses a stirring element formed by multiple horizontal and vertical stirring sections fixed alternately. The staggered arrangement of the stirring elements creates a stirring passage, enabling thorough stirring of the material within the reaction chamber. This solves the problem of uneven stirring caused by the small contact area between the stirring element and the material in fluidized bed reactors, and also avoids the problem of the stirring blade size affecting uniformity.

[0007] Patent CN201310572519 discloses a fluidized bed reactor with a stirring system. Without the need to add auxiliary inert particles, it can prevent the agglomeration of high-viscosity polymer particles and the adhesion of polymer particles to the inner wall of the reactor. It can generate effective stirring and mixing and improve the fluidization stability of high-viscosity polymer particles.

[0008] Patent CN201410787543 discloses a dual-shaft stirred vertical fluidized bed reactor, characterized by two stirring shafts with equidistant, intersecting stirring blades that interlock with each other. The fluidized bed's straight section has inlet and outlet ports. This design prevents the formation of large agglomerates between polymer particles and also prevents polymer particles from adhering to the reactor's inner surface, resulting in effective mixing and improved fluidization stability.

[0009] Patent CN201720132506 discloses a novel side-spray fluidized bed feeding device. Through the impact of compressed air, the side-spray fluidized bed can feed powder or small solid particles and other materials evenly and smoothly, effectively preventing material blockage of the pipe and improving product yield.

[0010] Patent CN201721468458 discloses a fluidized bed side spray device, characterized in that a side spray base with a hollow cavity is provided on the side wall of the fluidized bed body, and the hollow cavity of the side spray base is interconnected with the hollow cavity of the fluidized bed body; a side spray gun is coaxially provided in the base, and the protective airflow carries solid particles through the air duct into the hollow cavity of the fluidized bed body.

[0011] The methods or devices used in the aforementioned patent documents are all vertical stirring fluidized beds, and the working area of ​​the stirrer is relatively narrow, resulting in unsatisfactory stirring performance; or multi-layer stirring paddles are used, which improves the fluidization quality but also increases the stirring power consumption; although the aforementioned patents improve the gas-solid fluidization quality inside the fluidized bed, they do not solve the problems of continuous feeding and escape of fine particles. Summary of the Invention

[0012] This invention provides a dual-stirred fluidized bed, which enables continuous feeding of solid particles within the fluidized bed, prevents agglomeration of highly viscous particles, eliminates channeling and surging phenomena within the bed, and prevents the escape of fine particles from the bed. It also reduces bed vibration caused by bubble breakage in the upper part of the material bed, breaks up bubbles in the upper part of the bed, and reduces bubble size. This invention can also enhance the gas-solid fluidization effect and improve the stability of the fluidization process.

[0013] A dual-stirring fluidized bed includes a fluidized bed body and a stirring device, wherein the stirring device is a stirring device with vent holes and / or a stirring device with side feeding.

[0014] The fluidized bed device includes a fluidized bed body (1), a fluidized bed air inlet (9), a gas chamber (10), and a gas distribution plate (11); the fluidized bed body (1) is provided with a gas chamber (10) at the bottom, and the gas chamber (10) is connected to the fluidized bed air inlet (9); the gas distribution plate (11) is provided between the gas chamber (10) and the fluidized bed body (1).

[0015] Furthermore, the stirring device with vent holes includes an axial flow stirring paddle (2) and a hollow stirring shaft (4); the hollow stirring shaft (4) extends into the upper part of the fluidized bed body (1), the hollow stirring shaft is a hollow tube sleeve, the hollow stirring shaft (4) is perpendicularly inserted through the axial flow stirring paddle (2), the bottom of the hollow stirring shaft is provided with a bottom vent hole (3), and the upper side of the hollow stirring shaft is provided with a stirring shaft vent hole (7), allowing gas to enter the stirring shaft from the bottom and exit from the top.

[0016] Furthermore, the hollow stirring shaft has a circular vent hole (5), and the ratio of the diameter of the circular vent hole (5) to the diameter of the hollow stirring shaft is 0.25 to 0.4; the hollow stirring shaft (4) is connected to a motor (8) outside the fluidized bed body (1).

[0017] Furthermore, the stirring shaft plate (6) surrounding the hollow stirring shaft is bolted together, which can use the centrifugal force of the plate to separate fine particles back into the bed and prevent fine particles from escaping.

[0018] Preferably, three stirring shaft plates are installed at equal angles around the hollow stirring shaft.

[0019] Furthermore, if the stirring device is only a stirring device with an exhaust port, the fluidized bed also includes a stirring shaft (12) and a frame-type stirring paddle; the stirring shaft (12) extends from the outside of the fluidized bed body (1) through the conical gas chamber (10) and the gas distribution plate (11) into the inside of the fluidized bed body (1) and is connected to the frame-type stirring paddle (14); the stirring shaft (12) is connected to a motor (8) outside the fluidized bed body (1).

[0020] Furthermore, the lateral feeding stirring device includes a stirring paddle (17), a hollow stirring shaft (4), and a stirring shaft sleeve (15); the stirring shaft sleeve (15) is installed at an incline on the side wall of the fluidized bed, and the hollow stirring shaft (4) passes through the stirring shaft sleeve and is fixed; the stirring paddle (17) has a through hole at the bottom, is vertically installed at the bottom end of the hollow stirring shaft (4), and communicates with the hollow stirring shaft (4).

[0021] Furthermore, the stirring shaft sleeve is installed on the side wall of the fluidized bed at an angle of 30° to 60° to the horizontal plane, and the stirring blade rotates at a speed of 0 to 500 rpm, thereby expanding the influence area of ​​the stirring blade in the axial direction and improving the fluidization quality.

[0022] Preferably, the stirring shaft sleeve is installed on the side wall of the fluidized bed at an angle of 40° to 50° to the horizontal plane, and the stirring impeller is selected as a radial flow stirring impeller with a rotation speed of 120 to 300 rpm, which increases the radial shear force of the stirrer and weakens the adhesion effect between particles. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of the stirred fluidized bed with vent holes according to the present invention;

[0024] Figure 2 This is a top view of the hollow stirring shaft;

[0025] Figure 3 This is a schematic diagram of the side-feed fluidized bed structure of the present invention;

[0026] Figure 4 This is a schematic diagram of the structure of the dual-stirred fluidized bed of the present invention; in the figure:

[0027] 1. Fluidized bed body; 2. Axial flow impeller; 3. Bottom vent; 4. Hollow agitator shaft; 5. Round vent; 6. Agitator shaft plate; 7. Agitator shaft vent; 8. Motor; 9. Fluidized bed air inlet; 10. Gas chamber; 11. Gas distribution plate; 12. Agitator shaft; 13. Solid particles; 14. Frame agitator; 15. Agitator shaft sleeve; 16. Side agitator feed; 17. Agitator. Detailed Implementation

[0028] 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, and 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.

[0029] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

[0030] The axial-flow impeller described in this embodiment is an impeller capable of pressing solid particles downwards. It can be a CBY, a propeller, or a three-bladed impeller, but is not limited to these three types. The axial-flow impeller affects the movement of solid particles in the vertical direction, making it easier to press the solid particles downwards. At the same time, the shear force generated by the impeller can break up bubbles in the upper part of the material bed, reducing the bubble diameter and reducing pressure fluctuations in the bed, further reducing the escape of fine particles caused by bubble breakage.

[0031] Example 1

[0032] like Figure 1 As shown, a dual-stirring fluidized bed includes a fluidized bed body and a stirring device, wherein the stirring device is a stirring device with an exhaust port.

[0033] The fluidized bed device includes a fluidized bed body (1), a fluidized bed air inlet (9), a gas chamber (10), and a gas distribution plate (11); the fluidized bed body (1) has a gas chamber (10) at the bottom, and the gas chamber is a conical gas chamber; the side of the gas chamber (10) has a fluidized bed air inlet (9); the conical gas chamber (10) and the fluidized bed body (1) are provided with a gas distribution plate (11); the stirring shaft (12) extends from the outside of the fluidized bed body (1) through the conical gas chamber (10) and the gas distribution plate (11) into the inside of the fluidized bed body (1) and is connected to a frame-type stirring paddle (14); the stirring shaft (12) is connected to a motor (8) outside the fluidized bed body (1).

[0034] like Figure 2 As shown, the stirring device with vent holes includes an axial flow stirring paddle (2) and a hollow stirring shaft (4); the hollow stirring shaft (4) extends into the upper part of the fluidized bed body (1), the hollow stirring shaft is a hollow tube sleeve, the hollow stirring shaft (4) is perpendicularly inserted through the axial flow stirring paddle (2), the bottom of the hollow stirring shaft is provided with a bottom vent hole (3), and the upper side of the hollow stirring shaft is provided with a stirring shaft vent hole (7), allowing gas to enter the stirring shaft from the bottom and exit from the top.

[0035] The hollow stirring shaft has a circular vent hole (5). The ratio of the diameter of the circular vent hole (5) to the diameter of the hollow stirring shaft is 0.25 to 0.4. The selection of the vent hole diameter on the stirring shaft affects the velocity distribution of the fluidizing gas inside the stirring shaft and also affects the particle removal efficiency. The hollow stirring shaft (4) is connected to the motor (8) outside the fluidized bed body (1).

[0036] The hollow stirring shaft is equipped with stirring shaft plates (6). The three plates are installed at equal angles (120°) around the stirring shaft. The centrifugal force of the stirring shaft plates is used to separate fine particles back into the bed to prevent fine particles from escaping.

[0037] The specific working process of the dual-stirred fluidized bed described in this embodiment is as follows: the fluidizing gas enters the fluidized bed body (1) through the fluidized bed inlet (9) and gas chamber (10) at the bottom, and disperses the fluidizing gas into a bubble phase with size distribution through the gas distribution plate (11); the gas-solid two phases are fully contacted under the action of the frame-type stirring paddle (14), and the solid particles (13) undergo a variety of redox chemical reactions, accompanied by momentum and mass exchange; the bubbles continue to move to the upper part of the material bed and reach the position of the axial flow stirring paddle (2); the axial flow stirring paddle further breaks up the bubble phase and reduces the pressure fluctuation at the upper part of the bed; after the bubble phase detaches from the material bed, it carries small particles upward and enters the interior of the stirring shaft (4) through the exhaust hole (3) at the bottom of the hollow stirring shaft; due to the sudden contraction of the inlet area, the gas velocity increases, the movement speed of the particles increases, and the collision intensity and frequency with the inner wall of the hollow stirring shaft increases, so that the kinetic energy of the particles drops sharply after hitting the wall. Under the centrifugal force of the axial-flow impeller, the particles detach from the upper circular exhaust port (5) and fall back into the material bed. At the same time, the fine particles around the impeller plates (6) are deflected by the centrifugal force of the plates and fall back into the material bed after hitting the walls. The gas continues to move upward and is discharged from the axial-flow impeller exhaust port (7), and enters the cyclone separator through the pipe, completing one overall gas-solid motion.

[0038] Example 2

[0039] The fluidized bed described in Example 1 is used:

[0040] Iron ore powder particles were filled into a fluidized bed with a diameter of 100 mm and an initial height of 300 mm. The density of the iron ore powder was 2840 kg / m³. 3 The average particle diameter is 750 μm, with fine particles smaller than 50 μm accounting for 2.35%. The fluidized bed is aerated at the bottom, with the apparent gas velocity controlled within the range of 0.492–0.556 m / s. A frame-type agitator with a diameter of 80 mm is used for stirring, with a stirring speed controlled between 40 and 70 rpm. An axial-flow impeller with vent holes at the top, using a three-bladed design and a blade diameter of 80 mm, is used, with a stirring speed controlled between 120 and 200 rpm. The diameter of the circular vent holes on the agitator shaft is 0.25–0.4 times the diameter of the hollow agitator shaft. The mass and particle size distribution of the particles are measured at the gas outlet over a period of time using a laser particle size analyzer. In the stirred fluidized bed with vent holes described above, the escape rate of fine particles is only between 0.5% and 3.5%. The stirred fluidized bed with vent holes can effectively suppress the escape of fine particles, increase the residence time of particles in the bed, and ensure fluidization efficiency.

[0041] Example 3

[0042] like Figure 3As shown, a dual-stirring fluidized bed includes a fluidized bed body and a stirring device, wherein the stirring device is a side-feeding stirring device.

[0043] The fluidized bed device includes a fluidized bed body (1), a fluidized bed air inlet (9), a gas chamber (10), and a gas distribution plate (11); the fluidized bed body (1) is provided with a gas chamber (10) at the bottom, and the fluidized bed air inlet (9) is provided below the gas chamber (10); the gas distribution plate (11) is provided between the gas chamber (10) and the fluidized bed body (1).

[0044] The side-feed stirring device includes a stirring paddle (17), a hollow stirring shaft (4), and a stirring shaft sleeve (15); the stirring shaft sleeve (15) is installed at an angle on the side wall of the fluidized bed, and the hollow stirring shaft (4) passes through the stirring shaft sleeve and is fixed; the bottom of the stirring paddle (17) is provided with a through hole, and it is vertically installed at the bottom end of the hollow stirring shaft (4) and communicates with the hollow stirring shaft (4).

[0045] Furthermore, the stirring shaft sleeve is installed on the side wall of the fluidized bed at an angle of 30° to 60° to the horizontal plane, and the rotational speed of the stirring paddle is between 0 and 500 rpm. The installation angle within this range can expand the axial influence area of ​​the stirring paddle and improve the fluidization quality.

[0046] Preferably, the stirring shaft sleeve is installed on the side wall of the fluidized bed at an angle of 40° to 50° to the horizontal plane, and the stirring impeller can be a radial flow impeller with a rotational speed of 120 to 300 rpm. This ensures the radial shear force of the agitator and weakens the adhesion effect between particles.

[0047] The specific working process of the dual-stirred fluidized bed described in this embodiment is as follows: the fluidizing gas enters the fluidized bed body (1) in the form of bubbles through the gas distribution plate (11) at the bottom; the solid particles (3) move along the gas channel inside the hollow stirring shaft (4) by pneumatic conveying and enter the fluidized bed body (1) through the through hole at the bottom of the stirring paddle (17); the particles and bubbles are broken by the shear force generated by the stirring paddle in the stirring area, which can reduce the bubble diameter and greatly weaken the adhesion effect between particles. The inclined stirring paddle, under high-speed rotation, not only ensures its radial shear strength, but also enhances the axial movement speed of the particles, promoting the full circulation and internal circulation of particles in the material bed.

[0048] Example 4

[0049] The fluidized bed described in Example 3 is used:

[0050] In a fluidized bed with a diameter of 100 mm, iron ore powder (density 2840 kg / m³) was used.3 The solid iron ore powder (with an average particle size of 750 μm) is used as the fluidizing gas. Air is used as the fluidizing gas. The gas enters the fluidized bed through the bottom gas distribution plate at an apparent velocity of 0.5 m / s. The solid iron ore powder particles are pneumatically conveyed within a hollow stirring shaft (15–25 mm inner diameter) at a speed of 1.5–2.5 m / s along the internal gas channels of the stirring shaft, and then enter the fluidized bed reactor through the through-holes at the bottom of the stirring paddle. The particles and gas bubbles are broken up by the shear force generated by the stirring paddle in the stirring zone, which reduces pressure fluctuations within the fluidized bed and also facilitates the addition of iron ore powder.

[0051] Example 5

[0052] like Figure 4 As shown, a dual-stirring fluidized bed includes a fluidized bed body and a stirring device, wherein the stirring device is a stirring device with an exhaust port and a stirring device with side feeding.

[0053] The fluidized bed device includes a fluidized bed body (1), a fluidized bed air inlet (9), a gas chamber (10), and a gas distribution plate (11); the fluidized bed body (1) has a gas chamber (10) at its lower part, and the gas chamber is a conical gas chamber; the gas chamber (10) is connected to the fluidized bed air inlet (9); the gas distribution plate (11) is provided between the gas chamber (10) and the fluidized bed body (1).

[0054] The stirring device with vent holes includes an axial flow stirring paddle (2) and a hollow stirring shaft (4); the hollow stirring shaft (4) extends into the fluidized bed body (1) from above. The hollow stirring shaft is a hollow tube sleeve. The hollow stirring shaft (4) passes vertically through the axial flow stirring paddle (2). The bottom of the hollow stirring shaft is provided with a bottom vent hole (3). The upper side of the hollow stirring shaft is provided with a stirring shaft vent hole (7), which allows gas to enter the stirring shaft from the bottom and exit from the top.

[0055] Furthermore, the hollow stirring shaft has a circular vent hole (5), and the ratio of the diameter of the circular vent hole (5) to the diameter of the hollow stirring shaft is 0.25 to 0.4; the hollow stirring shaft (4) is connected to a motor (8) outside the fluidized bed body (1).

[0056] Furthermore, the hollow stirring shaft is equipped with stirring shaft plates (6), which can use the centrifugal force of the plates to separate fine particles back into the bed and prevent fine particles from escaping.

[0057] Preferably, three stirring shaft plates are installed at equal angles around the hollow stirring shaft.

[0058] Furthermore, if the stirring device is only a stirring device with an exhaust port, the fluidized bed also includes a stirring shaft (12) and a frame-type stirring paddle; the stirring shaft (12) extends from the outside of the fluidized bed body (1) through the conical gas chamber (10) and the gas distribution plate (11) into the inside of the fluidized bed body (1) and is connected to the frame-type stirring paddle (14); the stirring shaft (12) is connected to a motor (8) outside the fluidized bed body (1).

[0059] Furthermore, the lateral feeding stirring device includes a stirring paddle (17), a hollow stirring shaft (4), and a stirring shaft sleeve (15); the stirring shaft sleeve (15) is installed at an incline on the side wall of the fluidized bed, and the hollow stirring shaft (4) passes through the stirring shaft sleeve and is fixed; the stirring paddle (17) has a through hole at the bottom, is vertically installed at the bottom end of the hollow stirring shaft (4), and communicates with the hollow stirring shaft (4).

[0060] Furthermore, the stirring shaft sleeve is installed on the side wall of the fluidized bed at an angle of 30° to 60° to the horizontal plane, and the rotational speed of the stirring paddle is between 0 and 500 rpm. The installation angle within this range can expand the axial influence area of ​​the stirring paddle and improve the fluidization quality.

[0061] Preferably, the stirring shaft sleeve is installed on the side wall of the fluidized bed at an angle of 40° to 50° to the horizontal plane, and the stirring impeller can be a radial flow impeller with a rotational speed of 120 to 300 rpm. This ensures the radial shear force of the agitator and weakens the adhesion effect between particles.

[0062] The specific working process of the dual-stirred fluidized bed described in this embodiment is as follows:

[0063] Fluidized gas enters the fluidized bed body (1) through the fluidized bed inlet (9) and conical inlet chamber (10) at the bottom, and is dispersed by the gas distribution plate (11) to form a bubble phase with a size distribution. Solid particles (13) move along the inside of the stirring paddle (17) in the hollow stirring shaft (4) by pneumatic conveying, and enter the interior of the fluidized bed body (1) through the through hole at the bottom of the stirring paddle (17). The solid particles and the bubble phase are broken by the shear force generated by the stirring paddle (17) in the stirring zone, which can reduce the bubble diameter and greatly weaken the adhesion effect between particles. The bubbles continue to move to the upper part of the material bed and reach the position of the axial flow stirring paddle (2). At this point, the bubble phase is further broken, reducing the pressure fluctuation at the top of the material bed. After the gas phase detaches from the material bed, it carries small particles upward. It enters the interior of the hollow stirring shaft (4) through the exhaust hole (3) at the bottom of the hollow stirring shaft. The sudden contraction of the inlet area causes an increase in gas velocity, which in turn increases the velocity of the particles, increasing the intensity and frequency of collisions with the inner wall of the stirring shaft. This results in a sharp decrease in the kinetic energy of the particles after they hit the wall. Under the centrifugal force of the axial flow stirring paddle (2), the particles detach from the upper circular exhaust hole (5) and fall back into the material bed. At the same time, the fine particles around the stirring shaft plates (6) are deflected by the centrifugal force of the plates and fall back into the material bed after hitting the wall. The gas continues to move upward and is discharged from the exhaust hole (7) of the stirring shaft. It then enters the cyclone separator through the pipeline, completing one overall gas-solid motion. The dual-stirring fluidized bed utilizes two stirring systems to simultaneously achieve continuous side feeding and prevent particle escape, while also improving the fluidization quality within the bed.

[0064] Example 6

[0065] The fluidized bed described in Example 5 is used:

[0066] Air, as the fluidizing gas, enters the fluidized bed body (1) through the fluidized bed inlet (9) and the conical inlet chamber (10) at the bottom. The fluidized bed body has a bottom diameter of 100 mm and a height of 1200 mm, and the gas is dispersed by the gas distribution plate (11). Iron ore powder (density 2840 kg / m³) 3The particles (with an average particle size of 750 μm) move along the inside of the hollow stirring shaft (4) at a pneumatic conveying speed of 1.2–2.5 m / s, and enter the fluidized bed (1) through the through-hole at the bottom of the stirring paddle (17). The particles and bubbles are broken up by the shear force generated by the stirring paddle (17) in the stirring zone, which can reduce the pressure fluctuation of the material bed, and the pressure pulsation variance is as low as 50 Pa. The bubbles continue to move upward to the material bed, reaching the position of the three-bladed stirring paddle (2) (diameter 80 mm). Here the bubbles are further broken up, reducing the pressure fluctuation of the upper part of the material bed. After the gas phase detaches from the material bed, it carries the small particles upward. It enters the inside of the hollow stirring shaft (4) through the exhaust hole (3) at the bottom of the hollow stirring shaft. Under the action of the centrifugal force of the three-bladed stirring paddle (2), the particles detach from the upper round exhaust hole (5) and fall back into the material bed. Meanwhile, the fine particles around the stirring shaft plates (6) are deflected by the centrifugal force of the plates and fall back into the material bed after hitting the wall. The gas continues to move upward and is discharged from the exhaust port (7) of the stirring shaft, and enters the cyclone separator through the pipeline, completing one overall gas-solid motion. The dual-stirring fluidized bed utilizes two stirring systems to simultaneously achieve continuous feeding of iron ore powder particles from the side, and achieves an escape rate of less than 5% for fine particles (below 50μm), and also improves the fluidization quality in the bed.

Claims

1. A dual-stirred fluidized bed, characterized in that, It includes a fluidized bed body device and a stirring device, wherein the stirring device is a stirring device with vent holes and a side-feeding stirring device; The fluidized bed device includes a fluidized bed body (1), a fluidized bed air inlet (9), a gas chamber (10), and a gas distribution plate (11); the fluidized bed body (1) has a gas chamber (10) at its lower part, and the gas chamber (10) is connected to the fluidized bed air inlet (9); the gas distribution plate (11) is provided between the gas chamber (10) and the fluidized bed body (1). The stirring device with vent holes includes an axial flow stirring paddle (2) and a hollow stirring shaft (4); the hollow stirring shaft (4) extends into the upper part of the fluidized bed body (1), the hollow stirring shaft is a hollow tube sleeve, the hollow stirring shaft (4) is vertically inserted through the axial flow stirring paddle (2), the bottom of the hollow stirring shaft is provided with a bottom vent hole (3), and the upper side of the hollow stirring shaft is provided with a stirring shaft vent hole (7), allowing gas to enter the stirring shaft from the bottom and exit from the top; The side-feed stirring device includes a stirring paddle (17), a hollow stirring shaft (4), and a stirring shaft sleeve (15); the stirring shaft sleeve (15) is installed at an angle on the side wall of the fluidized bed, and the hollow stirring shaft (4) passes through the stirring shaft sleeve and is fixed; the bottom of the stirring paddle (17) is provided with a through hole, and it is installed vertically at the bottom end of the hollow stirring shaft (4) and communicates with the hollow stirring shaft (4).

2. The dual-stirred fluidized bed according to claim 1, characterized in that, The hollow stirring shaft has a circular vent hole (5), and the ratio of the diameter of the circular vent hole (5) to the diameter of the hollow stirring shaft is 0.25~0.4; the hollow stirring shaft (4) is connected to the motor (8) outside the fluidized bed body (1).

3. The dual-stirred fluidized bed according to claim 1, characterized in that, The stirring shaft plate (6) is installed around the hollow stirring shaft by bolt connection. The centrifugal force of the stirring shaft plate can be used to separate fine particles back into the bed and prevent fine particles from escaping.

4. The dual-stirred fluidized bed according to claim 3, characterized in that, Three stirring shaft plates (6) are installed at equal angles around the hollow stirring shaft.

5. The dual-stirred fluidized bed according to claim 1, characterized in that, The stirring shaft sleeve is installed on the side wall of the fluidized bed at an angle of 30° to 60° to the horizontal plane. The rotation speed of the stirring paddle is 0 to 500 rpm, which expands the influence area of ​​the stirring paddle in the axial direction and improves the fluidization quality.

6. The dual-stirred fluidized bed according to claim 5, characterized in that, The stirring shaft sleeve is installed on the side wall of the fluidized bed at an angle of 40° to 50° to the horizontal plane. The stirring impeller is a radial flow stirring impeller with a rotation speed of 120 to 300 rpm, which increases the radial shear force of the stirrer and weakens the adhesion effect between particles.

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