Variable cross-section paddle with tip baffle

Abstract

The invention discloses a variable cross-section paddle with a tip baffle. The stirring paddle is obtained by combining the variable cross-section paddle and the tip baffle. The variable cross-section paddle has good circulation capability, and can effectively shorten the mixing time. And the tip baffle plate has the effect of a stabilizing wing, so that the balance and the stability of the paddle during stirring are improved. The paddle can optimize the distribution condition of turbulent energy in the kettle, promote the turbulent energy of a liquid level and a kettle bottom area to be improved, remarkably reduce the area of a low-speed area of the area and remarkably enhance the axial flow pushing effect. The mechanical stirring paddle has obvious advantages in the aspects of improving the flow pattern, turbulence energy, speed and the like in the kettle.

Description

Technical Field

[0001] This invention belongs to the field of mixing equipment technology, specifically relating to a variable cross-section impeller with a pointed baffle. Background Technology

[0002] In diverse industrial sectors such as petroleum, chemical, metallurgy, food, and pharmaceuticals, mixing equipment, with its superior mass and heat transfer performance, has become an indispensable key piece of equipment in production processes. Among these, the performance of the mixing blades, as the core component of the mixing equipment, directly determines the mixing efficiency and energy consumption level. Therefore, exploring and developing new types of blades to significantly improve mixing efficiency while maintaining relatively stable energy consumption is of significant practical importance for promoting quality and efficiency improvements in industrial production. Summary of the Invention

[0003] To improve mixing efficiency, this invention provides a variable cross-section impeller with a pointed baffle, eliminating the need for additional components in the original mixing vessel. Instead, it optimizes and improves upon the existing variable cross-section impeller. Compared to traditional variable cross-section impellers, it has a wider axial influence range, effectively shortening the mixing time. Furthermore, by incorporating a baffle structure at the impeller tip, it effectively enhances the stability of the mixing process and the rigidity of the impeller blades.

[0004] To achieve this objective, the present invention adopts the following technical solution: A variable cross-section propeller with a tip baffle, the variable cross-section propeller includes a hub (1), a variable cross-section propeller (2) and a blade tip baffle (3); the variable cross-section propeller (2) has an angle of 40° to 50° with the horizontal plane.

[0005] The variable cross-section propeller (2) consists of a wide blade (2.1), a narrow blade (2.2) and an arc blade (2.3). The angle between the wide blade (2.1) and the narrow blade (2.2) is 10°. The length ratio between the wide blade (2.1) and the narrow blade (2.2) is 1:5 to 1:6. The arc blade (2.3) is a circular arc with a diameter of 0.1 to 0.11D, where D is the diameter of the propeller blade. The angle between the end of the arc blade (2.3) and the wide blade (2.1) is 30° to 40°.

[0006] The blade tip baffle (3) is an arc with the same diameter as the blade, welded to the center of the blade tip, with a length of 0.2D to 0.25D and a width of 0.27D, where D is the blade diameter.

[0007] The beneficial effects of this invention are: Compared to variable cross-section impellers without pointed baffles, variable cross-section impellers with pointed baffles exhibit several advantages. While the addition of the pointed baffles slightly restricts the radial flow of the fluid inside the vessel, it generates stronger axial flow during rotation, creating a large circulating flow field within the vessel and improving issues such as material accumulation at the bottom and insufficient mixing. Simultaneously, it significantly improves the velocity distribution within the vessel, greatly enhancing stirring efficiency. Attached Figure Description

[0008] Figure 1 This is a schematic diagram of the variable cross-section propeller with a pointed baffle of the present invention.

[0009] Figure 2 This is a schematic diagram of a three-bladed variable cross-section propeller without a tip baffle.

[0010] Figure 3 The diagrams shown in Example 2 illustrate the flow field. A is the flow field diagram inside a double-layered variable cross-section impeller with a pointed baffle, and b is the flow field diagram inside a double-layered variable cross-section impeller without a pointed baffle.

[0011] In the attached diagram, there is a hub (1), a variable cross-section propeller (2), a tip baffle (3), a wide blade (2.1), a narrow blade (2.2), and a circular arc blade (2.3). Detailed Implementation

[0012] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. Example 1

[0013] like Figure 1 The mechanical agitator shown is connected to the agitator shaft via a hub. The agitator blades consist of a wide blade 2.1, a narrow blade 2.2, an arc blade 2.3, and a tip baffle 3. The blade diameter D is 0.2–0.25T, where T is the diameter of the agitator. The angle between the blades and the horizontal plane is 40°–50°. The angle between the wide blade 2.1 and the narrow blade 2.2 is 5°–15°. The length ratio of the wide blade 2.1 to the narrow blade 2.2 is 1:5–1:6. The arc blade 2.3 is a circular arc with a diameter of 0.1–0.11D. The angle between the end of the arc blade 2.3 and the wide blade is 30°–40°. The tip baffle 3 is an arc with the same diameter as the blades, welded to the center of the blade tip, with a length of 0.2D–0.25D and a width of 0.27D. Example 2

[0014] Depend on Figures 1-2 The stirring paddles are composed of two layers of stirring paddles, with the upper and lower layers of paddles having the same size and being parallel to each other. The specific size of the paddles is the same as in Example 1. The distance from the bottom paddle to the bottom of the stirring vessel is 0.29h, and the distance between the two layers of paddles is 0.27h, where h is the liquid level height.

[0015] In this embodiment, the flow field of the impeller in the vessel was tested on a dedicated stirring test platform (patent number: ZL201110148263.3). The platform includes a transparent stirring vessel with an inner diameter T=430mm, a wall thickness δ=10mm, and a vessel height H=675mm. The flow field diagrams of the double-layered three-bladed variable cross-section impeller with a pointed baffle and the three-bladed variable cross-section impeller without a pointed baffle were observed under the same test conditions.

[0016] PIV technology is a transient and non-contact method for measuring flow fields. Tracer particles with tracking and reflective properties are added to the flow field to be measured. A laser sheet light source is used to irradiate the cross-sectional area of the flow field to be measured, and then the tracer particle trajectories within the cutting plane are captured through two consecutive exposures by means of photographic imaging technology. Finally, image processing technology is used to analyze the captured PIV images to obtain the average displacement of the particle images in each small area, thereby determining the two-dimensional fluid velocity distribution of the entire area on the flow field cross-section. By replacing the impeller blades, the flow fields of a double-layer novel three-arc blade agitator and a double-layer traditional three-arc blade agitator in the same area are measured experimentally.

[0017] Comparing the measured flow fields, for the internal flow field a of the three-blade variable cross-section agitator with double-layer tip baffles of the present invention and the internal flow field diagram b of the three-blade variable cross-section agitator with double-layer without tip baffles, the vortices in the middle area between the two impeller blades approach the upper impeller blade, making the connecting flow between the two impeller blades better, forming a large circulating flow field at the bottom of the kettle, making the materials at the bottom of the kettle mix more fully, and improving the problem of material accumulation at the bottom of the kettle. Example 3

[0018] The structure and dimensions of the mixing tank and impeller blades in this example are the same as those in Example 2. The test device mainly consists of a kettle body, a stirring drive device, a hydraulic lifting bracket for the stirring shaft, and a computer control cabinet, etc. The special software supporting the computer control system can monitor in real time the performance indicators and parameter performances such as the mixing time and stirring power of the stirrer. The mixing time is measured by the temperature difference method.

[0019] Table 1 shows the measured values of the parameters inside the kettle for the three-blade variable cross-section agitator with double-layer tip baffles and the three-blade variable cross-section agitator with double-layer without tip baffles. It can be seen that under the same operating conditions, compared with the impeller blade without tip baffles, the power of the impeller blade with tip baffles increases by 14.5%, and the mixing time decreases by 19.2%. Although the power consumption of the present invention increases slightly, the reduction in the mixing time is more obvious, enabling the materials to reach a uniform state faster.

[0020] Table 1 stirring paddle Power / W Mixing time / s Double-layer variable cross-section propeller with tip baffle 1.2946 10.371 Double-layer variable cross-section propeller without tip baffle 1.1306 12.835 rate of change -14.5% 19.2%

Claims

1. A variable cross-section propeller with a pointed baffle, characterized in that: The variable cross-section propeller includes a hub (1), a variable cross-section propeller (2), and a blade tip baffle (3); the variable cross-section propeller (2) has an angle of 40° to 50° with the horizontal plane.

2. The variable cross-section propeller with a pointed baffle according to claim 1, characterized in that: The variable cross-section propeller (2) consists of a wide blade (2.1), a narrow blade (2.2) and an arc blade (2.3). The angle between the wide blade (2.1) and the narrow blade (2.2) is 10°. The length ratio between the wide blade (2.1) and the narrow blade (2.2) is 1:5 to 1:

6. The arc blade (2.3) is a circular arc with a diameter of 0.1 to 0.11D, where D is the diameter of the propeller blade. The angle between the end of the arc blade (2.3) and the wide blade (2.1) is 30° to 40°.

3. The variable cross-section propeller with a pointed baffle according to claim 1, characterized in that: The blade tip baffle (3) is an arc with the same diameter as the blade, welded to the center of the blade tip, with a length of 0.2D to 0.25D and a width of 0.27D, where D is the blade diameter.

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