Combined mechanical seal structure for oil field

Abstract

A combined mechanical sealing structure for an oil field relates to the technical field of dynamic sealing. A threaded hole is formed in the upper portion of the stepped hole of the pump shell and connected with an oil storage barrel in a sealed mode, a gravity piston is installed in the oil storage barrel, the upper portion of the gravity piston is fixedly connected with a telescopic rod, an electromagnetic coil is installed on the upper portion of the oil storage barrel, and the space, below the gravity piston, of the oil storage barrel is filled with lithium-based grease lubricating oil. The utility model has the beneficial effects that a relatively independent space is formed at the joint sealing part of the moving ring and the static ring, and lithium-based grease lubricating oil is filled in the space, so that impurities can be prevented from entering the sealing surfaces of the moving ring and the static ring, and a pure sealing oil film is formed; the gravity piston keeps the pressure of the space where the sealing face is located to be the same as the pump operation pressure, liquid in the pump is prevented from entering the sealing portion, when the pump is stopped, the electromagnetic coil lifts the weight piston, the oil pressure in the space where the sealing face is located returns to normal, and lithium-based grease lubricating oil cannot flow out.

Description

Technical Field

[0001] The utility model relates to the technical field of dynamic sealing, in particular to a combined mechanical sealing structure for oil fields. Background Art

[0002] The mechanical seal of a centrifugal pump uses the liquid film formed between the dynamic ring and the static ring when the conveyed liquid enters, as well as the elastic force of the compensation mechanism for dynamic sealing. In the petroleum industry, the media often conveyed are mixtures containing oil, corrosive sewage and impurities. When impurities enter the contact surface of the dynamic ring and the static ring, the sealing surfaces of the static ring and the dynamic ring are damaged during the operation of the pump, thereby reducing the service life of the mechanical seal. Utility Model Content

[0003] In order to solve the problem of short service life of mechanical seal of centrifugal pump for oil field, the utility model provides a combined mechanical seal structure for oil field.

[0004] The technical solution provided by the utility model is: a combined mechanical seal structure for oil fields, comprising a stationary ring and a dynamic ring, wherein the stationary ring is inlaid on a pump casing through a sealing gasket, the dynamic ring is inlaid on a retaining sleeve, the dynamic ring and the stationary ring are fitted and sealed, the retaining sleeve is connected to the pump shaft through a sealing ring gap, the retaining sleeve is connected to a limit sleeve through a spring, and the limit sleeve is connected to the pump shaft through a locking screw;

[0005] The outer circle of the retaining sleeve is processed with a stepped shaft, and the pump casing is processed with a stepped hole at the stepped shaft position. The stepped hole is connected with the stepped shaft with clearance fit. A threaded hole is opened on the upper part of the step hole of the pump casing to seal and connect the oil storage cylinder. A gravity piston is installed in the oil storage cylinder. The gravity piston is connected with the oil storage cylinder through the clearance fit of the sealing ring. The upper part of the gravity piston is fixedly connected to the telescopic rod. The telescopic rod is made of carbon steel. An electromagnetic coil is installed on the upper part of the oil storage cylinder. The inner hole of the iron core of the electromagnetic coil is connected with the telescopic rod with clearance fit. The space below the gravity piston of the oil storage cylinder is filled with lithium-based grease lubricating oil.

[0006] When the centrifugal pump is powered on, the electromagnetic coil is de-energized. When the centrifugal pump stops running, the electromagnetic coil is energized to lift the telescopic rod.

[0007] The oil reservoir is connected with an oil filling nozzle beside the lower part of the gravity piston.

[0008] The weight of the gravity piston is such that the pressure of the hydraulic oil below the gravity piston is equal to the pressure inside the pump casing when the centrifugal pump is running.

[0009] The beneficial effects of the utility model are as follows: by means of the clearance fit connection between the stepped shaft of the retaining sleeve and the stepped hole of the pump housing, a relatively independent space is formed at the joint sealing position of the dynamic ring and the static ring, and lithium-based grease lubricating oil is filled in this space, which can ensure that impurities do not enter the sealing surfaces of the dynamic ring and the static ring, thereby forming a pure sealing oil film; at the same time, a gravity piston is arranged in the oil storage cylinder, and when the pump is running, the gravity piston keeps the pressure in the space where the sealing surface is located the same as the pump operating pressure, thereby preventing the liquid in the pump from entering the sealing position; when the pump is stopped, the electromagnetic coil lifts the weight piston, and the oil pressure in the space where the sealing surface is located returns to normal, and the lithium-based grease lubricating oil does not flow out. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Attached Figure 1 It is a structural schematic diagram of the utility model;

[0011] Attached Figure 2 Attached Figure 1 Enlarged view of point A.

[0012] In the figure, 1- pump housing, 2- pump shaft, 3- static ring, 4- dynamic ring, 5- retaining sleeve, 6- spring, 7- limit sleeve, 8- step hole, 9- step shaft, 10- oil storage cylinder, 11- gravity piston, 12- telescopic rod, 13- electromagnetic coil, 14- oil filling nozzle. DETAILED DESCRIPTION

[0013] like Figures 1-2 As shown, a combined mechanical seal structure for oil fields includes a stationary ring 3 and a dynamic ring 4. The stationary ring 3 is embedded in the pump housing 1 through a sealing gasket, and the dynamic ring 4 is embedded in a retaining sleeve 5. The dynamic ring 4 and the stationary ring 3 are tightly sealed and connected. The retaining sleeve 5 is connected to the pump shaft 2 through a sealing ring clearance fit. The retaining sleeve 5 is connected to the limiting sleeve 7 through a spring 6, and the limiting sleeve 7 is connected to the pump shaft 2 through a locking screw.

[0014] The outer circle of the retaining sleeve 5 is processed with a step shaft 9, and the pump housing 1 is processed with a step hole 8 at the position of the step shaft 9. The step hole 8 is connected with the step shaft 9 with a clearance fit. The pump housing 1 is opened with a threaded hole on the upper part of the step hole 8 to seal and connect the oil storage cylinder 10. A gravity piston 11 is installed in the oil storage cylinder 10. The gravity piston 11 is connected to the oil storage cylinder 10 through a sealing ring clearance fit. The upper part of the gravity piston 11 is fixedly connected to the telescopic rod 12, and the telescopic rod 12 is made of carbon steel. An electromagnetic coil 13 is installed on the upper part of the oil storage cylinder 10. The inner hole of the iron core of the electromagnetic coil 13 is connected with the telescopic rod 12 with a clearance fit, and the space below the gravity piston 11 of the oil storage cylinder 10 is filled with lithium-based grease lubricating oil.

[0015] When the centrifugal pump is powered on, the electromagnetic coil 13 is powered off. When the centrifugal pump stops running, the electromagnetic coil 13 is powered on to lift the telescopic rod 12.

[0016] By means of a clearance fit connection between the stepped shaft 9 of the retaining sleeve 5 and the stepped hole 8 of the pump housing 1, a relatively independent space is formed at the joint sealing position of the dynamic ring 4 and the static ring 3. The space is filled with lithium-based grease lubricating oil to ensure that the sealing surfaces of the dynamic ring 4 and the static ring 3 are not entered by impurities, thereby forming a pure sealing oil film. At the same time, a gravity piston 11 is arranged in the oil storage cylinder 10. When the pump is running, the gravity piston 11 keeps the pressure of the space where the sealing surface is located the same as the operating pressure of the pump to prevent the liquid in the pump from entering the sealing position. When the pump is stopped, the electromagnetic coil 13 lifts the weight piston 11, and the oil pressure in the space where the sealing surface is located returns to normal, and the lithium-based grease lubricating oil does not flow out.

[0017] The oil storage cylinder 10 is connected with an oiling nozzle 14 at the lower part of the gravity piston 11 for replenishing lithium-based grease lubricating oil.

[0018] The weight of the gravity piston 11 is such that the pressure of the hydraulic oil below the gravity piston 11 is equal to the pressure inside the pump housing 1 when the centrifugal pump is running.

Claims

1. A combined mechanical seal structure for oil fields, comprising a stationary ring (3) and a dynamic ring (4), characterized in that: The stationary ring (3) is embedded in the pump housing (1) through a sealing gasket, the dynamic ring (4) is embedded in the retaining sleeve (5), the dynamic ring (4) and the stationary ring (3) are closely connected and sealed, the retaining sleeve (5) is connected to the pump shaft (2) through a sealing ring clearance fit, the retaining sleeve (5) is connected to the limiting sleeve (7) through a spring (6), and the limiting sleeve (7) is connected to the pump shaft (2) through a locking screw; The outer circle of the retaining sleeve (5) is processed with a stepped shaft (9), and the pump housing (1) is processed with a stepped hole (8) at the stepped shaft (9). The stepped hole (8) and the stepped shaft (9) are connected by clearance fit. The pump housing (1) is provided with a threaded hole at the upper part of the stepped hole (8) to seal and connect the oil storage cylinder (10). A gravity piston (11) is installed in the oil storage cylinder (10). The gravity piston (11) is connected to the oil storage cylinder (10) by clearance fit through a sealing ring. The upper part of the gravity piston (11) is fixedly connected to a telescopic rod (12). The telescopic rod (12) is made of carbon steel. An electromagnetic coil (13) is installed at the upper part of the oil storage cylinder (10). The inner hole of the iron core of the electromagnetic coil (13) is connected by clearance fit with the telescopic rod (12). The space below the gravity piston (11) of the oil storage cylinder (10) is filled with lithium-based grease lubricating oil.

2. The combined mechanical seal structure for oil fields according to claim 1, characterized in that: When the centrifugal pump is powered on, the electromagnetic coil (13) is powered off; when the centrifugal pump stops running, the electromagnetic coil (13) is powered on to lift the telescopic rod (12).

3. The combined mechanical seal structure for oil fields according to claim 1, characterized in that: The oil storage cylinder (10) is connected with an oil injection nozzle (14) beside the lower part of the gravity piston (11).

4. The combined mechanical seal structure for oil fields according to claim 1, characterized in that: The weight of the gravity piston (11) is such that the pressure of the hydraulic oil below the gravity piston (11) is equal to the pressure inside the pump housing (1) when the centrifugal pump is in operation.

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