A kind of emulsion breaking prevention latex pump impeller structure

Abstract

The application provides a broken emulsion prevention latex pump impeller structure and belongs to the technical field of chemical production equipment. Current research shows that the main reason for the emulsion breaking phenomenon of latex during the latex conveying process by a latex pump is that the shear stress of the latex is too large, and the blade tip gap is the most severe position of the latex to the shear stress. The application adopts a semi-open centrifugal pump blade tip structure, the blade tip of the blade is provided with an inverted right triangle groove, the groove is provided in multiple sections, both ends of each section of the groove are blocked, and a certain distance interval is arranged between the parallel grooves. The blade tip structure of the centrifugal pump blade is used for reducing the shear stress of the fluid at the blade tip gap and preventing the emulsion breaking phenomenon during the latex conveying process.

Description

Technical Field

[0001] This invention belongs to the field of chemical production equipment technology. Background Technology

[0002] A centrifugal pump is a mechanical device that uses the centrifugal force generated by the rotation of an impeller to transport fluid media. It enables the fluid media to be transported from a low-pressure area to a high-pressure area through centrifugal force, achieving fluid transport and pressure increase. Centrifugal pumps are widely used in various production fields such as petroleum, chemical, power, metallurgy, and water treatment for pumping raw materials, products, and wastewater treatment processes. Among them, semi-open centrifugal pumps are widely used in the chemical production field due to their strong media adaptability, convenient maintenance, and compact structure.

[0003] ABS resin, or acrylonitrile-butadiene-styrene copolymer, has wide applications in electronics, electrical appliances, instruments, automobiles, building materials, and daily consumer goods. Industrial production mainly employs methods such as emulsion grafting and emulsion grafting blending. The colloidal emulsion (latex) used in these methods is a polymer aqueous dispersion with properties such as multiphase characteristics, high viscosity, and instability. As an important raw material in the production process, its quality determines the performance of the product. However, because latex itself is in a thermodynamically metastable state, changes in external conditions can cause it to transition from a stable to an unstable state. In chemical production, semi-open centrifugal pumps, collectively known as latex pumps, are commonly used to transport latex media. Therefore, demulsification and coagulation are highly susceptible to occur during latex pump transportation. Demulsification and coagulation affect the quality of the latex polymer product and cause blockages in the pump's flow channels and delivery pipelines, thus impacting production efficiency.

[0004] Current research indicates that latex demulsification during latex pump transport is primarily caused by excessive shear stress on the latex. This is attributed to an inadequate internal pump design, which results in excessive shear stress on the latex medium within the pump, leading to demulsification and coagulation. Therefore, adjusting the pump's internal structure to improve the shear stress distribution of the fluid within the pump is crucial to preventing demulsification. Summary of the Invention

[0005] To address the aforementioned problems, this invention proposes an anti-breakage latex pump impeller structure to reduce the shear stress distribution of the fluid at the impeller tip clearance of the centrifugal pump, thereby preventing the latex medium from being damaged during pump transport.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A latex pump impeller structure for preventing latex breakage includes a front cover plate 1, blades 2 and a rear cover plate 3; the blades 2 are disposed on the rear cover plate 3, and multiple blades 2 are evenly arranged circumferentially.

[0008] Furthermore, the top surface of the blade 2 is provided with two sets of inverted isosceles right-angled triangular grooves 4.

[0009] Furthermore, a gap 5 is provided between the two sets of inverted isosceles right-angled triangular grooves 4.

[0010] Furthermore, the inverted isosceles right-angled triangular groove 4 is configured as multiple segments, and each segment of the groove 4 has a sealing structure 6 at both ends.

[0011] Furthermore, the sealing structure 6 has a uniform thickness and its direction is perpendicular to the intersection of the blade tip surface and the blade pressure surface.

[0012] Furthermore, the sealing structure 6 is arranged sequentially towards the leading edge of the blade, with the trailing edge of the blade as the starting position. Let T be the arc length of the first sealing groove and L be the arc length of the adjacent second sealing groove. Both must satisfy: L = kT, where k is a coefficient, k = 1.1 to 1.5.

[0013] Furthermore, the ratio of the top width of the inverted isosceles right-angled triangular groove 4 to the width of the cross-section of the blade tip is 1:3.

[0014] Furthermore, the ratio of the interval 5 between the inverted isosceles right-angled triangular grooves 4 to the width of the cross-section of the blade tip is 1:10.

[0015] Furthermore, the distance between the top of the blade 2 and the front cover plate 1 is between 0.1 mm and 0.9 mm.

[0016] The beneficial effects of this invention are as follows:

[0017] (1) The present invention provides an inverted isosceles right-angled triangular groove at the tip of the blade. The groove is provided with multiple sealing sections. When the pump is running, liquid will be stored in the groove. The inverted triangular groove has a large top area, which allows the leakage flow to have a large contact range with the fluid in the groove. The leakage flow can interact with the fluid in the groove to generate energy dissipation and reduce the flow velocity, thereby reducing the shear stress of the leakage flow.

[0018] (2) The sidewall of the inverted isosceles right triangle groove can form a large obtuse angle with the blade tip surface, which can avoid generating an excessive velocity gradient when the fluid flows through, thus avoiding large shear stress.

[0019] (3) A certain distance is provided between the parallel grooves to avoid the contact of the side walls between the two grooves to form sharp corners, which would generate large shear stress on the fluid. Attached Figure Description

[0020] Figure 1 This is a structural diagram of the latex pump impeller in this invention;

[0021] Figure 2 This is a diagram of the blade structure in the latex pump of the present invention;

[0022] Figure 3 This is a cross-sectional view of the blade tip structure;

[0023] Figure 4 The diagrams show three blade tip structures: (a) is the original blade tip structure, (b) is the blade tip structure 1, (c) is the blade tip structure 2, (d) is the velocity vector diagram of the original blade tip structure, (e) is the velocity vector diagram of the blade tip structure 1, and (f) is the velocity vector diagram of the blade tip structure 2.

[0024] Figure 5 This is a cloud map showing the shear stress distribution within the impeller flow domain;

[0025] Figure 6 This is a bar chart showing the maximum shear stress generated in the impeller flow domain by the three blade tip structures mentioned above. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] like Figures 1-4 As shown, an anti-breakage latex pump impeller structure in this embodiment includes a front cover plate 1, blades 2, and a rear cover plate 3; the blades 2 are disposed on the rear cover plate 3, and multiple blades 2 are evenly arranged circumferentially.

[0028] The top surface of the blade 2 is provided with two sets of inverted isosceles right-angled triangular grooves 4.

[0029] A gap 5 is provided between the two sets of inverted isosceles right-angled triangular grooves 4.

[0030] The inverted isosceles right-angled triangular groove 4 is configured as multiple segments, and each segment of groove 4 has a sealing structure 6 at both ends.

[0031] The sealing structure 6 has a uniform thickness and its direction is perpendicular to the intersection of the blade tip surface and the blade pressure surface.

[0032] The sealing structure 6 is arranged sequentially from the trailing edge of the blade towards the leading edge. Let T be the arc length of the first sealing groove and L be the arc length of the adjacent second sealing groove. Both must satisfy: L = kT, where k is a coefficient, k = 1.1 to 1.5.

[0033] The ratio of the top width of the inverted isosceles right-angled triangular groove 4 to the width of the cross-section of the blade tip is 1:3.

[0034] The ratio of the interval 5 between the inverted isosceles right-angled triangular grooves 4 to the width of the cross-section of the blade tip is 1:10.

[0035] The distance between the top of the blade 2 and the front cover plate 1 is between 0.1 mm and 0.9 mm.

[0036] The working principle of this invention to achieve low shear stress is as follows: When the centrifugal pump is operating normally, due to the existence of the blade tip clearance, the leakage flow flows from the pressure surface of the blade through the blade tip to the suction surface. By arranging a novel blade tip structure, the leakage flow velocity is reduced, while avoiding the generation of large velocity gradients locally, thereby reducing the shear stress of the leakage flow at the blade tip. Because the inverted triangular groove at the blade tip is sealed in multiple sections, a large amount of liquid will be stored in the groove, and the inverted triangular groove has a large top area, allowing for a large contact range between the leakage flow and the fluid in the groove. The interaction between the fluids generates energy dissipation, reducing the flow velocity and thus reducing the shear stress of the leakage flow. Simultaneously, because the angle formed between the sidewall of the inverted isosceles right-angled triangular groove and the blade tip surface is large, excessive velocity gradients are avoided when the fluid flows through, thus preventing large shear stress. Since the linear velocity of the blade rotation is greater closer to the blade trailing edge, and the velocity of the leakage flow at the blade tip is greater, the distribution of the sealing structure is set to be denser closer to the blade trailing edge, resulting in a better sealing effect on the fluid in the groove and greater energy dissipation of the leakage flow. A certain distance is provided between the two parallel grooves to avoid the side walls of the two grooves contacting each other and forming sharp corners, which would generate large shear stress on the fluid.

[0037] After the rheological properties of the latex are measured through rheological experiments, the data are input into CFD software for simulation experiments. Figure 4 (a) to (c) are schematic diagrams of three blade tip structures in the blade tip gap. Figure 4 (d) to (f) are velocity vector diagrams of the three blade tip structure sections in the blade tip gap. In this embodiment, the total blade length is 250 mm. For blade tip structure 2, the arc length of the first sealing groove is 40 mm, the coefficient k is 1.3, and the sealing length of the subsequent grooves is calculated as L = kT. Figure 4 (d) The fluid flows horizontally and directly along the blade tip gap. Figure 4 In (e), the fluid forms a distinct vortex, and the maximum flow velocity is greater than [missing value]. Figure 4 (d) and Figure 4 (f). Figure 4(f) shows a dense velocity vector at the top of the groove, indicating significant energy exchange, and the maximum velocity is the lowest among the three structures. Analysis suggests that when the tip clearance leakage flows through tip structure 1, the leakage flow can exit along the groove. The lack of fluid accumulation in the groove obstructs the leakage flow, causing vortices to form within the groove. This vortex effect increases the leakage flow velocity, leading to increased shear stress within the fluid layer and a higher risk of demulsification. When the tip clearance leakage flows through tip structure 2, the sealing structure allows fluid to accumulate in the groove. When the leakage flow passes through, the interaction between the leakage flow and the accumulated fluid in the groove dissipates energy, reducing the leakage flow velocity to below that of the original tip structure. This reduces shear stress within the fluid layer, preventing demulsification. Figure 5 The diagram shows the fluid shear stress distribution in the impeller flow domain of the original blade tip structure. It can be seen that the fluid shear stress is mainly distributed in the blade tip gap. Figure 6 The bar chart comparing the maximum shear stress in the impeller flow domain for the three blade tip structures shows that blade tip structure 2 generates the lowest maximum shear stress value in the impeller flow domain. The above simulation results demonstrate that the pump structure provided in this embodiment has a certain effect on reducing the shear stress in the pump blade tip clearance; therefore, the latex pump proposed in this invention can prevent demulsification.

Claims

1. A latex pump impeller structure designed to prevent latex breakage, characterized in that, The impeller structure includes a front cover plate (1), blades (2) and a rear cover plate (3); the blades (2) are set on the rear cover plate (3), and multiple blades (2) are evenly arranged in the circumferential direction; the top surface of the blades (2) is provided with an inverted right-angled triangular groove (4), the groove (4) is set into multiple segments, the two ends of each segment of the groove (4) are sealed, and a certain distance (5) is provided between the parallel grooves (4); the sealing structure (6) of the groove on the top surface of the blade (2) is arranged in sequence towards the leading edge of the blade, with the trailing edge of the blade as the starting position. The arc length of the first segment of the sealing groove (4) is denoted as T, and the arc length of the adjacent second segment of the sealing groove (4) is denoted as L. The two must satisfy: L=kT, k is a coefficient, k=1.1~1.

5.

2. The anti-breakage latex pump impeller structure according to claim 1, characterized in that, The top surface of the blade (2) is provided with two sets of inverted isosceles right triangle grooves (4).

3. The anti-breakage latex pump impeller structure according to claim 2, characterized in that, The groove (4) of the inverted isosceles right triangle on the top surface of the blade (2) has the same thickness as the sealing structure (6), and its direction is perpendicular to the intersection of the blade top surface and the blade pressure surface.

4. The anti-breakage latex pump impeller structure according to claim 2, characterized in that, The ratio of the top width of the groove (4) of the inverted isosceles right triangle on the top surface of the blade (2) to the width of the cross section at the top of the blade is 1:

3.

5. The anti-breakage latex pump impeller structure according to claim 2, characterized in that, The ratio of the interval (5) between the two sets of inverted isosceles right triangle grooves (4) to the width of the blade tip cross section is 1:

10.

6. The anti-breakage latex pump impeller according to claim 1, characterized in that, The distance between the top of the blade (2) and the front cover plate (1) is between 0.1 mm and 0.9 mm.

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