A high shear nozzle and rotor for purifying molten aluminum by rotary injection

Abstract

The application belongs to the technical field of non-ferrous metal or alloy melt processing, and particularly relates to a high-shear jet head and a rotor for rotary blowing of aluminum liquid purification, which comprises an upper disc, an upper paddle, a lower disc and a lower paddle, the center of the upper disc and the lower disc is provided with a round hole, the edge is provided with semicircular grooves which are uniformly distributed in the circumferential direction, the semicircular grooves are used to apply shear force to the aluminum liquid during the rotation of the high-shear jet head for rotary blowing of aluminum liquid purification, the inclination directions of the upper paddle and the lower paddle are opposite, so that the upper paddle applies downward force to the aluminum liquid and the lower paddle applies upward force to the aluminum liquid when the jet head rotates; the aluminum liquid between the upper paddle and the lower paddle is extruded and sheared, the shear breaking capacity of the jet head is enhanced, the size of the refining gas bubbles blown into the aluminum liquid can be effectively refined, the adsorption and purification effect on the aluminum liquid is improved, and the disturbance degree of the rotation of the rotor to the surface of the aluminum liquid is reduced.

Description

Technical Field

[0001] This invention belongs to the field of non-ferrous metal or alloy melt processing technology, and particularly relates to the purification treatment of aluminum alloy melt, specifically to a high-shear force nozzle and rotor for rotary blowing aluminum liquid purification. Background Technology

[0002] Hydrogen and oxygen are the main impurity elements in aluminum alloys. If they are not sufficiently removed before casting, they will remain in the form of pores and oxide inclusions, negatively impacting product quality and performance. Currently, industrial production mainly uses rotary jetting technology to purify molten aluminum and remove gas and impurities. A high-speed rotating rotor injects refining gases (mainly nitrogen, argon, etc.) and refining agents (mainly chloride and fluoride salts of alkali metals and alkaline earth metals) into the molten aluminum, where they are sheared, crushed, and dispersed. Hydrogen and oxide inclusions are removed through the adsorption and purification effect of the refining agents.

[0003] A rotary jetting rotor typically consists of a rotor and a nozzle mounted at the bottom of the rotor. Both the rotor and the nozzle have hollow jetting channels through which the refining agent enters the molten aluminum from the bottom of the nozzle. The nozzle is a key component of the rotor, directly determining its effectiveness in breaking down and dispersing the refining medium. During the molten aluminum purification process, the refining agent can be added either by relying on surface vortices or directly by jetting from the rotor. Compared to relying on surface vortices, direct jetting from the rotor has the following advantages: firstly, it eliminates the need to form vortices on the surface of the molten aluminum, thus reducing secondary hydrogen and oxygen absorption and oxidation loss during the purification process; secondly, it ensures that the refining agent fully penetrates the molten aluminum to exert its effect, significantly improving the utilization efficiency of the refining agent.

[0004] Existing nozzle structures are designed for surface-entry addition processes in molten aluminum, requiring strong agitation capabilities to create vortices that entrain the refining agent. However, this vortex formation introduces secondary contamination and oxidation damage to the aluminum. For direct injection addition processes, vortex formation is unnecessary. Therefore, it's crucial to minimize the nozzle's agitation intensity while maintaining the rotor's shearing, crushing, and dispersing effects on the refining medium. Current nozzle designs fail to simultaneously reduce agitation intensity and enhance the shearing and crushing capabilities of the refining medium. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a high-shear force nozzle and rotor for rotary blowing aluminum molten purification, thereby improving the aluminum molten purification effect of the rotary blowing process and reducing aluminum molten loss during the purification process.

[0006] The complete technical solution of this invention includes:

[0007] A high-shear force nozzle for purifying molten aluminum by rotary spraying, the high-shear force nozzle for purifying molten aluminum by rotary spraying has a double-layer structure, including an upper disc, an upper blade, a lower disc, and a lower blade;

[0008] The upper and lower discs are provided with a circular hole at the center and semi-circular grooves are evenly distributed along the circumference at the edge. The semi-circular grooves are used to apply horizontal shear force to the aluminum liquid during the rotation of the high shear force nozzle for purifying aluminum liquid by rotary blowing.

[0009] The upper blades are evenly distributed circumferentially below the upper disk, and the lower disk is located below the upper blades, with the lower blades evenly distributed circumferentially below the lower disk.

[0010] The upper and lower blades are inclined at a certain angle to the vertical direction, and the inclination directions of the two blades are opposite. When the high shear force nozzle for purifying aluminum liquid by rotating is rotating, the upper blade applies a downward force to the aluminum liquid, and the lower blade applies an upward force to the aluminum liquid. The aluminum liquid between the upper and lower blades is squeezed and sheared.

[0011] Furthermore, the diameter of the upper and lower discs is 180-220mm, and the height is 30-50mm.

[0012] Furthermore, the diameter of the circular holes at the center of the upper and lower disks is 90-110mm.

[0013] Furthermore, the semi-circular grooves have a diameter of 25-35mm and a quantity of 4-8.

[0014] Furthermore, both the upper and lower blades are parallelepiped structures, with each blade having a rectangular upper and lower plane and four parallelograms in the longitudinal direction, with a length of 20-30mm, a width of 20-30mm, and a height of 30-50mm.

[0015] Furthermore, both the upper and lower blades have 4-8 blades.

[0016] Furthermore, the upper blades are tilted at an angle of 15-45° to the vertically downward direction.

[0017] Furthermore, the tilt angle of the lower blades relative to the vertical downward direction is smaller than the tilt angle of the upper blades relative to the vertical downward direction.

[0018] Furthermore, the rotor with the high-shear force nozzle for purifying molten aluminum by rotary blowing includes a rotating rod, which is assembled and connected to the high-shear force nozzle for purifying molten aluminum by rotary blowing through a circular hole in the center of the upper disk.

[0019] Compared with the prior art, the advantages of the present invention are as follows:

[0020] (1) The nozzle is designed as a "disc + blade" structure with high shearing capacity. The number of disc and blade layers is increased from single layer to double layer. Combined with the disc groove structure and the blade cross layout with opposite tilting directions, a high-pressure, high-turbulence opposing extrusion zone is formed, which significantly enhances the shearing and crushing capacity of the nozzle. It can effectively refine the size of the refining gas bubbles sprayed into the aluminum liquid and improve the adsorption and purification effect of the refining medium on the aluminum liquid.

[0021] (2) The nozzle is set as a hollow structure, and the overall mass of the nozzle is significantly reduced compared with the traditional solid nozzle. Its stirring intensity on the aluminum liquid is reduced accordingly. The input power of the rotor is consumed more in the shearing action on the aluminum liquid near the nozzle. In addition, the height and tilt angle of the upper and lower blades are reasonably designed to generate a large downward axial force. The upward axial force of the lower blade is small, and only the upward lifting fluid is formed. The overall flow field shows a downward dominant flow direction, so that the refining medium is dispersed in the area below and around the nozzle, instead of impacting the aluminum liquid surface upward, thereby avoiding the liquid surface churning. Thus, while improving the breaking effect of the nozzle on the refining medium, the degree of disturbance of the rotor rotation on the aluminum liquid surface is reduced, and the oxidation loss of the aluminum liquid is reduced. Attached Figure Description

[0022] Figure 1 This is a perspective view of the nozzle proposed in this invention.

[0023] Figure 2 This is a front view of the nozzle proposed in this invention.

[0024] Figure 3 This is a bottom view of the nozzle proposed in this invention.

[0025] Figure 4 This is a perspective view of the nozzle and rotating rod after assembly according to the present invention.

[0026] In the diagram: 1 is the nozzle, 1-1 is the upper disc, 1-2 is the upper blade, 1-3 is the lower disc, 1-4 is the lower blade, and 2 is the rotating rod. Detailed Implementation

[0027] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. The described embodiments are merely examples and are not intended to limit this application.

[0028] See Figures 1 to 3 A high-shear force nozzle for purifying molten aluminum by rotary blowing, wherein the nozzle 1 has a double-layer structure, consisting of an upper disc 1-1, an upper blade 1-2, a lower disc 1-3, and a lower blade 1-4.

[0029] The upper disk 1-1 and the lower disk 1-3 both have a diameter of 180-220mm and a height of 30-50mm. The center of each disk has a circular hole with a diameter of 90-110mm, and the edge of each disk is machined with 4-8 semi-circular grooves with a diameter of 25-35mm.

[0030] Both the upper blade 1-2 and the lower blade 1-4 are parallelepiped structures, evenly distributed circumferentially below the upper disk 1-1 and the lower disk 1-3, respectively. Each layer contains 4-8 blades. The top and bottom planes of each blade are rectangular, and the four longitudinal planes are parallelograms. The length... All are 20-30mm wide. All are 20-30mm, height All blades are 30-50mm in diameter. The upper blades are tilted at an angle of 15-45° to the vertically downward direction (nose axis), while the lower blades are tilted at a smaller angle to the vertically downward direction than the upper blades. The upper blades 1-2 and the lower blades 1-4 are tilted in opposite directions, with the specific tilt direction determined by the nozzle's rotation direction.

[0031] Viewed from above, when the nozzle rotates clockwise, the upper blades tilt downwards to the right and the lower blades tilt downwards to the left in the frontal view; conversely, when the nozzle rotates counterclockwise, the upper blades tilt downwards to the left and the lower blades tilt downwards to the right. Figures 1-4 The image shows the tilted arrangement of the two blades when the nozzle rotates counterclockwise. When the nozzle rotates clockwise, the tilting direction of the two blades can be reversed.

[0032] The nozzle proposed in this invention has a basic structural feature of "disc + blade". During rotation, the abrupt changes in cross-section between the grooves on the disc and the edges of the blades can apply a high shear force to the molten aluminum, thereby effectively breaking down the refining medium flowing through this area into smaller particles. By improving the nozzle from a traditional single-layer structure to a double-layer structure, the number of grooves on the disc and the number of blades are significantly increased, and the shear strength of the nozzle on the molten aluminum is correspondingly significantly improved.

[0033] Existing single-layer blades or multi-layer blades tilted in the same direction, regardless of the blade inclination angle, generate a dominant thrust flow in one direction (such as simply downward or upward) in the axial direction. The interior of the molten aluminum lacks a strong, directional counter-extrusion effect. Bubbles are mainly broken up by eddy shear at the blade trailing edge and friction with the surrounding relatively stationary melt, which has limited efficiency and makes it difficult to achieve bubble homogenization.

[0034] Furthermore, while existing bladed nozzles can generate shear force, this shear force is highly concentrated within the narrow gap between the rotor and stator, and decreases rapidly in areas far from the gap, resulting in an uneven overall flow field. Moreover, the shear distribution of a single blade within its disk surface is difficult to control.

[0035] Based on the above technical problems, the nozzle disclosed in this invention employs a key design feature of a special two-layer blade layout. Unlike traditional nozzles where all blades are tilted in the same direction, in this invention, the upper and lower layers of the nozzle are distributed in opposite directions. During nozzle rotation, the upper blades generate a downward axial force, while the lower blades generate an upward axial force. Under the action of these opposing axial forces, the nozzle's extrusion and shearing forces on the molten aluminum are significantly enhanced, thereby achieving a better refining medium crushing effect.

[0036] As the nozzle rotates in the molten aluminum, its upper and lower blades, with their opposite tilt directions, generate distinctly different force fields, working together to form a dynamic "compression-shear" zone. The upper blades, rotating like a downward-propelling helix, exert continuous downward pressure on the molten aluminum, while the lower blades, tilted in the opposite direction, exert continuous upward thrust. The two opposing flows of molten aluminum strongly converge and collide within the annular space between the upper and lower blades, creating a high-pressure, high-turbulence opposing compression zone where the molten aluminum is repeatedly compressed and stretched.

[0037] Simultaneously, axial and radial synergistic shearing forces are generated within the compression zone. The encounter of upward and downward fluids results in severe radial splitting and velocity differences, triggering intense turbulent shearing. This internal shear force generated by the opposing flow fields is far greater than the shear force generated by traditional impellers solely through the velocity difference between the rotating and stationary melt. Furthermore, the semi-circular grooves along the edges of the upper and lower disks exert horizontal circumferential shear forces on the surrounding melt during high-speed rotation. This extends the main shear zone between the impeller blades to the periphery of the disks, ensuring that the shearing effect permeates the entire flow field.

[0038] Through the above synergistic effect, the refining gas and refining agent introduced from the central hole of the rotor are first initially dispersed by the upper blades. Then, under the upward action of the lower blades, they are immediately drawn into the compression-shear zone between the blades. Here, they are subjected to the dual action of compression and shearing, and are rapidly broken into a group of dispersed bubbles with extremely small size and uniform distribution, which greatly increases the gas-liquid contact area.

[0039] Furthermore, the aforementioned extrusion-shearing action is limited to the annular space between the upper and lower blades. First, the refining gas and refining agent ejected from the nozzle are fully mixed, broken, and dispersed, but without causing significant disturbance to the entire molten aluminum, thus reducing the overall stirring intensity and minimizing oxidation and burn-off.

[0040] Furthermore, unlike traditional nozzles which have a solid internal structure, the nozzle proposed in this invention has a hollow frame structure. The power input through the rotor is consumed more in the local shearing action of the blades and the grooves on the edge of the disc on the molten aluminum. The overall stirring intensity of the nozzle on the molten aluminum is reduced, thereby reducing the degree of disturbance of the nozzle on the surface of the molten aluminum during the refining process.

[0041] Furthermore, the angles of the upper and lower blades are further designed. By differentiating the tilt angles of the upper and lower blades, the upper blade generates a larger downward axial force, forcefully pressing the molten aluminum and refining medium into the extrusion zone. Meanwhile, the lower blade generates a smaller upward axial force, only lifting the fluid upward, which encounters the downward mainstream and generates opposing extrusion and shearing. This creates a high-pressure, high-turbulence opposing extrusion zone between the upper and lower blades, effectively breaking up bubbles. Moreover, the overall flow field exhibits a downward dominant flow direction, allowing the refining medium to disperse below and around the nozzle without impacting the surface of the molten aluminum upward, thus preventing surface turbulence and reducing oxidation and burn-off of the molten aluminum.

[0042] Analysis revealed that the axial force generated by a single blade is related to... Proportional relationship The angle between the blade and the vertically downward direction (nozzle axis) is defined by the following constraint relationship:

[0043]

[0044]

[0045] in, The angle between the upper blade and the vertically downward direction. It is the angle between the lower blade and the vertically downward direction.

[0046] and,

[0047]

[0048] In the formula, The outer diameter of the disk. The diameter of the central circular hole, The blade height, This represents the height of the disk.

[0049] Through the above design, highly efficient bubble breakage is achieved. Asymmetrical but opposing axial forces create a high-pressure, high-turbulence flow field within the extrusion zone, subjecting the bubbles to multiple effects of stretching, compression, and shearing, resulting in improved breakage efficiency compared to traditional nozzles. Bubble size is homogenized; the repeated extrusion within the extrusion zone leads to a more concentrated bubble size distribution and a reduced average bubble diameter. Simultaneously, the overall flow field is predominantly downward, transporting the refined bubbles / refining agent deep into the melt, preventing upward impact on the liquid surface, reducing surface ripple amplitude, and significantly lowering the oxidation loss rate. After the bubbles are broken into dispersed microbubbles, the total gas-liquid contact area increases significantly by 2-4 times, further improving refining efficiency.

[0050] By controlling the aspect ratio of the extrusion zone within a certain range, the extrusion zone simultaneously achieves efficient axial compression and radial shearing, maximizing bubble breakage efficiency. Combined with the condition that the axial force of the upper blade is greater than that of the lower blade, the pressure center within the extrusion zone is not at the geometric center but rather offset downwards, with the offset being no less than 1 / 4 of the extrusion zone height. After breakage, the bubbles are carried downwards by the mainstream flow to the depths of the melt, avoiding backmixing to the liquid surface and achieving directional bubble transport. The residence time of bubbles within the extrusion zone can be controlled to be no less than 0.3 s. The geometric dimensions of the extrusion zone are matched with the fluid dynamics parameters, avoiding "dead zones" and "short-circuit flows" in the flow field, ensuring uniform breakage of the refining gas throughout the entire extrusion zone and improving flow field uniformity.

[0051] This invention also discloses a rotor equipped with the aforementioned high-shear force nozzle for purifying molten aluminum using rotary blowing, comprising a rotating rod 2. The rotating rod is assembled and connected to the high-shear force nozzle for purifying molten aluminum using rotary blowing. A refining agent adding device is connected above the rotating rod, through which refining agents are added, thus forming a complete rotary blowing aluminum alloy melt purification device. The rotating rod and the refining agent adding device can adopt a common structure in the prior art, using refining gas to blow the refining agent into the molten aluminum for refining. The density of the refined molten aluminum (measured by vacuum solidification method) is greater than 2.66 g / cm³. 3 The aluminum liquid loss rate ((weight of aluminum liquid before refining - weight of aluminum liquid after refining) / weight of aluminum liquid before refining × 100) is less than 2%, the purity meets the production quality requirements, and the aluminum liquid loss rate is significantly reduced compared to the 3-5% of the traditional rotary blowing process.

[0052] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Any simple modifications, alterations, or equivalent structural changes made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A high-shear force nozzle for purifying molten aluminum by rotary spraying, characterized in that, The high-shear nozzle for purifying molten aluminum by rotary blowing has a double-layer structure, including an upper disc, an upper blade, a lower disc, and a lower blade. The upper and lower discs are provided with a circular hole at the center and semi-circular grooves are evenly distributed along the circumference at the edge. The semi-circular grooves are used to apply horizontal shear force to the aluminum liquid during the rotation of the high shear force nozzle for purifying aluminum liquid by rotary blowing. The upper blades are evenly distributed circumferentially below the upper disk, and the lower disk is located below the upper blades, with the lower blades evenly distributed circumferentially below the lower disk. The upper and lower blades are inclined at a certain angle to the vertical direction, and the inclination directions of the two blades are opposite. When the high shear force nozzle for purifying aluminum liquid by rotating is rotating, the upper blade applies a downward force to the aluminum liquid, and the lower blade applies an upward force to the aluminum liquid. The aluminum liquid between the upper and lower blades is squeezed and sheared.

2. The high-shear force nozzle for purifying molten aluminum by rotary blowing according to claim 1, characterized in that, The diameter of the upper and lower discs is 180-220mm, and the height is 30-50mm.

3. The high-shear force nozzle for purifying molten aluminum by rotary blowing according to claim 2, characterized in that, The diameter of the circular hole at the center of the upper and lower discs is 90-110mm.

4. The high-shear force nozzle for purifying molten aluminum by rotary blowing according to claim 3, characterized in that, The semi-circular grooves have a diameter of 25-35mm and a quantity of 4-8.

5. A high-shear force nozzle for purifying molten aluminum by rotary blowing according to claim 4, characterized in that, Both the upper and lower blades are parallelepiped structures. The upper and lower planes of each blade are rectangular, and the four longitudinal planes are parallelograms. The length is 20-30mm, the width is 20-30mm, and the height is 30-50mm.

6. A high-shear force nozzle for purifying molten aluminum by rotary blowing according to claim 5, characterized in that, The number of upper and lower blades is 4-8 each.

7. A high-shear force nozzle for purifying molten aluminum by rotary blowing according to claim 6, characterized in that, The upper blades are tilted at an angle of 15-45° to the vertical downward direction.

8. A high-shear force nozzle for purifying molten aluminum by rotary blowing according to claim 6, characterized in that, The tilt angle of the lower blades relative to the vertical downward direction is smaller than the tilt angle of the upper blades relative to the vertical downward direction.

9. A rotor equipped with a high-shear force nozzle for purifying molten aluminum as described in claim 7, characterized in that, It includes a rotating rod, which is assembled and connected to the high-shear force nozzle for purifying molten aluminum by rotating and blowing through a circular hole in the center of the upper disk.

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