Cavitation-resistant mechanical sealing device for centrifugal pump

Abstract

The utility model relates to an anti-cavitation mechanical sealing device for a centrifugal pump, which comprises a shaft sleeve, a first sealing ring, a second sealing ring and a third sealing ring. The elastic compensation structure sleeves the end part, close to the third step surface, of the second step surface; the end, close to the second step surface, of the third step surface is sleeved with the graphite moving ring, one end of the graphite moving ring is connected with the elastic compensation structure in a sealed mode, the graphite moving ring is axially limited through the elastic compensation structure, and meanwhile the circumferential rotation capacity of the graphite moving ring is limited; the silicon carbide static ring is arranged on the third step surface in a sleeving mode and abuts against the graphite movable ring; the static ring flange plate is sleeved on the silicon carbide static ring and is provided with a cooling fluid inlet; the anti-cavitation protective sleeve is arranged on the first step surface, the elastic compensation structure and the graphite moving ring in a sleeving manner, is in interference fit with the first step surface and is locked through a set screw; and the locking metal ring is used for locking the position of each structure on the shaft sleeve. The elastic compensation structure can be prevented from being damaged by cavitation, and the service life of the mechanical seal is prolonged.

Description

Technical Field

[0001] The utility model relates to the technical field of centrifugal pump mechanical seal structures, in particular to an anti-cavitation mechanical seal device for a centrifugal pump. Background Art

[0002] In the air flotation system of an offshore oil platform, the gas-liquid fluid formed by the mixing of produced water and natural gas is pumped into the air flotation tank at a tangential velocity by means of an air flotation circulation pump, and oil-water separation is carried out under the action of high-speed swirling. The bubbles mixed with oil and grease are discharged from the top, and the produced water is discharged from the middle. In order to enable the fluid to reach a sufficient tangential velocity, a circulating centrifugal pump is used at the bottom inlet pipeline of the air flotation tank to continuously circulate the gas-liquid two-phase flow fluid. However, at present, the elastic compensation device of the mechanical seal used in the air flotation circulation pump of the offshore oil platform is directly impacted by the high-speed gas-liquid mixed fluid during the working process. The cavitation phenomenon that occurs damages the elastic compensation device, and finally leakage occurs. Summary of the Utility Model

[0003] The purpose of the utility model is to solve at least one technical problem in the background art, and provide an anti-cavitation mechanical seal device for a centrifugal pump.

[0004] To achieve the above purpose, the utility model provides an anti-cavitation mechanical seal device for a centrifugal pump, including:

[0005] A shaft sleeve, including a first step surface, a second step surface and a third step surface;

[0006] An elastic compensation structure, sleeved on the end of the second step surface close to the third step surface;

[0007] A graphite dynamic ring, sleeved on the end of the third step surface close to the second step surface, one end of which is hermetically connected to the elastic compensation structure, and the graphite dynamic ring is axially limited by the elastic compensation structure, and at the same time, the circumferential rotation of the graphite dynamic ring is restricted;

[0008] A silicon carbide static ring, sleeved on the third step surface and abutted against the graphite dynamic ring;

[0009] A static ring flange, sleeved on the silicon carbide static ring, and provided with a cooling fluid inlet and a cooling fluid outlet thereon;

[0010] An anti-cavitation protective sleeve, sleeved on the first step surface, the elastic compensation structure and the graphite dynamic ring, and in interference fit with the first step surface and locked by a set screw;

[0011] A locking metal ring, sleeved on the end of the third step surface far from the second step surface, to lock the positions of the structures on the shaft sleeve.

[0012] According to one aspect of the utility model, the elastic compensation structure includes: a coil spring seat, a plurality of coil springs and a dynamic ring metal seat;

[0013] The coil spring seat sleeve is placed on the second step surface, and is provided with a first groove facing the graphite moving ring, and one end of the coil spring seat sleeve facing away from the graphite moving ring abuts against the inner wall step of the anti-cavitation protective sleeve;

[0014] The movable ring metal seat sleeve is placed on the second step surface, and is arranged opposite to the coil spring seat, and is provided with a second groove facing the coil spring seat;

[0015] The coil springs are arranged at intervals, and one end of each coil spring is supported in the first groove, and the other end is supported in the second groove;

[0016] The coil spring seat is connected to the dynamic ring metal seat by bolts.

[0017] According to one aspect of the utility model, a limiting metal plate is provided at one end of the moving ring metal seat away from the coil spring seat, the end of the graphite moving ring is installed at the end of the moving ring metal seat away from the coil spring seat, and an installation groove is provided on the outer wall of the graphite moving ring, and the limiting metal plate is matched and connected with the installation groove.

[0018] According to one aspect of the utility model, an O-ring is provided between the graphite moving ring and the moving ring metal seat on a side close to the third step surface.

[0019] According to the scheme of the utility model, in order to overcome the problem of cavitation of the mechanical seal elastic compensation device of the air flotation circulation pump during the transportation of gas-liquid fluids, the utility model proposes an anti-cavitation mechanical seal device for a centrifugal pump. The utility model can prevent the elastic compensation device (i.e., the elastic compensation structure) from being damaged by cavitation, thereby extending the service life of the mechanical seal.

[0020] According to the solution of the present utility model, the cooling water enters its interior from the stationary ring flange through the cooling fluid inlet, and is discharged from the cooling fluid outlet provided on its inner wall to cool the graphite rotating ring and the silicon carbide stationary ring. Since heat is generated by mutual friction between the graphite rotating ring and the silicon carbide stationary ring, cooling water is required to cool the joint surface between the graphite rotating ring and the silicon carbide stationary ring. In the present invention, when the cooling water flow in the mechanical seal cooling water channel cools the mechanical seal rotating ring and the stationary ring, the jet flow generated by the cooling water flow under high pressure will first impact the cavitation protection sleeve and will not directly damage the helical spring in the elastic compensation structure of the mechanical seal, ensuring the integrity and functionality of the mechanical seal elastic compensation device. That is, the fluid flowing through the cooling water channel of the mechanical seal directly impacts the cavitation protection sleeve, rather than directly impacting the elastic compensation structure composed of the rotating ring metal seat, the helical spring and the helical spring seat, so that the composed elastic compensation structure is not affected by cavitation, ensuring that the mechanical seal will not fail. Brief Description of the Drawings

[0021] Figure 1 Schematically showing a side cross-sectional view of an anti-cavitation mechanical seal device for a centrifugal pump according to an embodiment of the present utility model;

[0022] Figure 2 Schematically showing a top view of an anti-cavitation mechanical seal device for a centrifugal pump according to an embodiment of the present utility model. Detailed Description of the Embodiments

[0023] Now the content of the present utility model will be described with reference to exemplary embodiments. It should be understood that the described embodiments are only for enabling those of ordinary skill in the art to better understand and thus implement the content of the present utility model, rather than implying any limitation on the scope of the present utility model.

[0024] As used herein, the term "comprising" and its variants are to be construed as open-ended terms meaning "including but not limited to". The term "based on" is to be construed as "at least partially based on". The terms "one embodiment" and "an embodiment" are to be construed as "at least one embodiment".

[0025] Figure 1 Schematically showing a side cross-sectional view of an anti-cavitation mechanical seal device for a centrifugal pump according to an embodiment of the present utility model; Figure 2 Schematically showing a top view of an anti-cavitation mechanical seal device for a centrifugal pump according to an embodiment of the present utility model. As Figure 1 and Figure 2 shown, in the present embodiment, the anti-cavitation mechanical seal device for a centrifugal pump includes:

[0026] The shaft sleeve 1 includes a first step surface 2, a second step surface 3, and a third step surface 4;

[0027] The elastic compensation structure 5 is sleeved on the end of the second step surface close to the third step surface;

[0028] The graphite moving ring 6 is sleeved on the end of the third step surface close to the second step surface. One end is hermetically connected to the elastic compensation structure, and the graphite moving ring is axially limited by the elastic compensation structure, and at the same time, the circumferential rotation of the graphite moving ring is restricted;

[0029] The silicon carbide static ring 7 is sleeved on the third step surface and abuts against the graphite moving ring;

[0030] The static ring flange 8 is sleeved on the silicon carbide static ring, and is provided with a cooling fluid inlet 9 and a cooling fluid outlet 21 thereon;

[0031] The cavitation protection sleeve 10 is sleeved on the first step surface, the elastic compensation structure, and the graphite moving ring, and is in interference fit with the first step surface and locked by a set screw 11;

[0032] The locking metal ring 12 is sleeved on the end of the third step surface far from the second step surface to lock the positions of the structures on the shaft sleeve.

[0033] Further, according to an embodiment of the present invention, as Figure 1 shown, the elastic compensation structure 5 includes: a helical spring seat 13, a plurality of helical springs 14, and a moving ring metal seat 15;

[0034] The helical spring seat is sleeved on the second step surface, and is provided with a first groove 16 facing the graphite moving ring, and the end thereof facing away from the graphite moving ring abuts against the inner wall step 17 of the cavitation protection sleeve;

[0035] The moving ring metal seat is sleeved on the second step surface, is disposed opposite to the helical spring seat, and is provided with a second groove 18 facing the helical spring seat;

[0036] The helical springs are circumferentially arranged at intervals, and one end of each helical spring is supported in the first groove, and the other end is supported in the second groove;

[0037] The helical spring seat and the moving ring metal seat are connected by bolts.

[0038] Further, as Figure 1 shown, in this embodiment, a limiting metal plate 19 is provided at the end of the moving ring metal seat facing away from the helical spring seat. The end of the graphite moving ring is installed at the end of the moving ring metal seat facing away from the helical spring seat, and an installation groove (not shown in the figure) is provided on the outer wall of the graphite moving ring. The limiting metal plate is connected with the installation groove, so as to restrict the circumferential rotation of the graphite moving ring through the limiting metal plate.

[0039] Further, as Figure 1 shown, in this embodiment, an O-ring seal 20 is provided on one side of the graphite rotating ring close to the third step surface between the graphite rotating ring and the rotating ring metal seat.

[0040] According to the above solution of the present utility model, the present utility model aims to overcome the problem that the mechanical seal elastic compensation device of the air-lift circulation pump is cavitated during the transportation of gas-liquid fluid, and thus proposes an anti-cavitation mechanical seal device for a centrifugal pump. The present utility model can prevent the elastic compensation device (i.e., the elastic compensation structure) from being damaged by cavitation and extend the service life of the mechanical seal.

[0041] According to the above solution of the present utility model, cooling water enters the inside of the stationary ring flange 8 through the cooling fluid inlet 9 and is discharged from the cooling fluid outlet 21 provided on its inner wall to cool the graphite rotating ring 6 and the silicon carbide stationary ring 7. Since mutual friction generates heat between the graphite rotating ring 6 and the silicon carbide stationary ring 7, cooling water is required to cool the joint surface between the graphite rotating ring 6 and the silicon carbide stationary ring 7. In the present invention, when the cooling water flow in the mechanical seal cooling water channel cools the rotating ring and the stationary ring of the mechanical seal, the jet flow generated by the cooling water flow under high pressure will first impact the anti-cavitation protection sleeve and will not directly damage the helical spring in the elastic compensation structure of the mechanical seal, ensuring the integrity and functionality of the mechanical seal elastic compensation device. That is, the fluid flowing through the cooling water channel of the mechanical seal directly impacts the anti-cavitation protection sleeve, rather than directly impacting the elastic compensation structure composed of the rotating ring metal seat, the helical spring and the helical spring seat. In this way, the composed elastic compensation structure is not affected by cavitation, ensuring that the mechanical seal does not fail.

[0042] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present utility model and not to limit them. Although the present utility model has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present utility model.

Claims

1. An anti-cavitation mechanical seal device for a centrifugal pump, characterized in that: include: The shaft sleeve comprises a first step surface, a second step surface and a third step surface; An elastic compensation structure is sleeved on an end of the second step surface close to the third step surface; A graphite moving ring is sleeved on the end of the third step surface close to the second step surface, one end of which is sealed and connected to the elastic compensation structure, and the elastic compensation structure is used to axially limit the graphite moving ring and limit the circumferential rotation of the graphite moving ring; A silicon carbide stationary ring is sleeved on the third step surface and abuts against the graphite moving ring; A stationary ring flange is sleeved on the silicon carbide stationary ring and is provided with a cooling fluid inlet and a cooling fluid outlet; An anti-cavitation protective sleeve is sleeved on the first step surface, the elastic compensation structure and the graphite dynamic ring, and is interference-fitted with the first step surface and locked by a set screw; A locking metal ring is sleeved on the end of the third step surface away from the second step surface to lock the positions of various structures on the shaft sleeve.

2. The anti-cavitation mechanical seal device for a centrifugal pump according to claim 1, characterized in that: The elastic compensation structure comprises: a coil spring seat, a plurality of coil springs and a dynamic ring metal seat; The coil spring seat sleeve is placed on the second step surface, and is provided with a first groove facing the graphite moving ring, and one end of the coil spring seat sleeve facing away from the graphite moving ring abuts against the inner wall step of the anti-cavitation protective sleeve; The movable ring metal seat sleeve is placed on the second step surface, and is arranged opposite to the coil spring seat, and is provided with a second groove facing the coil spring seat; The coil springs are arranged at intervals, and one end of each coil spring is supported in the first groove, and the other end is supported in the second groove; The coil spring seat is connected to the dynamic ring metal seat by bolts.

3. The anti-cavitation mechanical seal device for a centrifugal pump according to claim 2, characterized in that: A limiting metal plate is provided at one end of the moving ring metal seat away from the coil spring seat, the end of the graphite moving ring is installed at the end of the moving ring metal seat away from the coil spring seat, and an installation groove is provided on the outer wall of the graphite moving ring, and the limiting metal plate is matched and connected with the installation groove.

4. The anti-cavitation mechanical seal device for a centrifugal pump according to claim 2, characterized in that: An O-type sealing ring is provided between the graphite moving ring and the moving ring metal seat on one side close to the third step surface.

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