Bellows single-end-face bidirectional pumping mechanical seal device

Abstract

The utility model relates to mechanical seal technical field discloses corrugated pipe single end face bidirectional pumping mechanical seal device, including welding metal corrugated pipe subassembly, gland, shaft sleeve and static ring, its characterized in that, the static ring end face design has bidirectional spiral groove. Welding metal corrugated pipe subassembly one end with the shaft sleeve fixed connection, welding metal corrugated pipe subassembly other end is static and the static ring close adhesion. The spiral groove in bidirectional spiral groove inner circle place spiral groove with the spiral groove at bidirectional spiral groove outer circle place rotation direction is opposite. Bidirectional spiral groove groove depth is 0.008mm. Bidirectional spiral groove circumferential distribution angle is alpha, alpha is 20~30 DEG. The utility model does not need to add sealing auxiliary system, directly utilizes the environment work in the sealing cavity of gas cabinet screw compressor, realizes self -lubricating and sealing through bidirectional pumping mechanism, has simplified the system structure, reduced the equipment initial investment and operating cost.

Description

Technical Field

[0001] This utility model relates to the field of mechanical seal technology, specifically a bellows single-end bidirectional pumping mechanical seal device. Background Technology

[0002] The gas holder screw compressor is a key piece of equipment in an oil refinery, supplying flare gas to the flare tower. Flare gas is a mixture of low-carbon hydrocarbons such as methane, ethylene, ethane, hydrogen, and propane, as well as hydrogen sulfide. The sealed chamber of the gas holder screw compressor (see...) Figure 1 The medium connected to the screw cavity on the medium side is gaseous flare gas, and the medium connected to the bearing housing on the atmospheric side is liquid turbine oil. In actual operation, the pressure of the flare gas is higher than that of the turbine oil.

[0003] The three sealing technologies are: single-end face sealing for the gas holder screw compressor, double-end face wet sealing for the gas holder screw compressor, and double-end face dry gas sealing for the gas holder screw compressor. For a gas-hold screw compressor with a single-end-face seal, the sealing structure can be a bellows or multi-spring seal. The outer circle of the sealing face operates in flare gas, while the inner circle operates in turbine oil. Because the pressure of the flare gas is higher than that of the turbine oil, the sealing face operates in a gas phase environment, preventing the formation of a lubricating film between the moving and stationary rings, resulting in dry operation and rapid seal failure. Alternatively, a double-end-face wet seal can be used, with a multi-spring or bellows seal and a backpressure prevention design on the medium side. The seal operation requires the PLAN54 system, which provides circulating sealing fluid to the sealing chamber between the double-end-face seals, preventing leakage of flare gas in the screw cavity, turbine oil in the bearing housing, and backflow between the two chambers. This technical solution presents challenges such as complex system installation and maintenance, and a large initial investment. The gas-hold screw compressor has four sealing chambers at both ends. The PLAN54 system requires inlet and outlet pipelines to each sealing chamber, making pipeline installation and maintenance complex, and requiring a larger system footprint. The PLAN54 system, which meets the standard requirements, is relatively expensive, resulting in a large initial investment. Using existing dry gas sealing technology, the gas holder screw compressor's sealing arrangement should be a double-end dry gas seal with a multi-spring sealing structure. Seal operation requires the support of the PLAN74 system. The PLAN74 system provides sealing gas to the sealing chamber between the double-end seals, sealing the flare gas in the screw chamber, preventing turbine oil leakage in the bearing housing, and preventing backflow between the two chambers. Using existing dry gas sealing technology presents problems such as large initial investment, complex system installation and maintenance, and high operating costs. According to the standard, a gas holder screw compressor with four sealing chambers at both ends should be equipped with four PLAN74 systems, leading to a substantial initial investment. The piping installation and maintenance of four PLAN74 systems are complex, and the system occupies a large area. Each pair of sealing faces in a dry gas seal consumes approximately 0.5 to 1 liter of nitrogen per hour; the nitrogen consumption for four sealing chambers and eight pairs of sealing faces is very high, resulting in high operating costs.

[0004] To address the aforementioned issues, we propose a bellows-type single-end-face bidirectional pumping mechanical seal device. Utility Model Content

[0005] The purpose of this invention is to provide a bellows single-end face bidirectional pumping mechanical seal device to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, this utility model provides the following technical solution: a bellows single-end face bidirectional pumping mechanical seal device, comprising a welded metal bellows assembly, a gland, a bushing, and a stationary ring, characterized in that the stationary ring end face is designed with a bidirectional spiral groove.

[0007] Preferably, one end of the welded metal bellows assembly is fixedly connected to the bushing, and the other end of the welded metal bellows assembly is tightly fitted to the stationary ring when static.

[0008] Preferably, the spiral groove at the inner circle of the bidirectional spiral groove has the opposite spiral direction to the spiral groove at the outer circle of the bidirectional spiral groove.

[0009] Preferably, the depth of the bidirectional spiral groove is 0.008 mm.

[0010] Preferably, the circumferential distribution angle of the bidirectional spiral groove is α, where α is 20°~30°.

[0011] Compared with the prior art, the beneficial effects of this utility model are: Achieving self-lubrication and sealing: The bidirectional spiral grooves on the stationary ring end face enable bidirectional pumping of turbine oil. The spiral grooves on the inner circle transport turbine oil to the outer circle (upstream pumping), providing liquid lubrication to the sealing end face and forming the lubricating film required for sealing. The reverse spiral grooves on the outer circle transport turbine oil back to the inner circle (downstream pumping). This bidirectional pumping mechanism retains the advantages of upstream pumping while reducing leakage at the sealing end face.

[0012] Improving sealing reliability and service life: The bidirectional pumping mechanism optimizes the geometric parameters of the spiral grooves (groove depth, circumferential distribution angle) and the physical properties of the turbine oil, achieving efficient formation and stable maintenance of the lubricating film between the sealing end faces. The sealing end faces change from contact-type mixed friction to a non-contact state, significantly reducing sealing power consumption and improving service life and reliability.

[0013] This invention eliminates the need for an additional sealing auxiliary system, directly utilizing the environment within the sealing chamber of the gas holder screw compressor. It achieves self-lubrication and sealing through a bidirectional pumping mechanism, simplifying the system structure and reducing initial investment and operating costs. Attached Figure Description

[0014] Figure 1 This is a schematic cross-sectional view of the structure of this utility model; Figure 2 This is a right-side view of the structure of the stationary ring in this utility model.

[0015] In the figure: 1-Welded metal bellows assembly, 2-Glander cap, 3-Shaft sleeve, 4-Stationary ring, 41-Bidirectional spiral groove. Detailed Implementation

[0016] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0017] Please see Figure 1 , Figure 2 This utility model provides a technical solution: a bellows single-end face bidirectional pumping mechanical seal device, including a welded metal bellows assembly 1, a gland 2, a bushing 3 and a stationary ring 4, wherein the stationary ring 4 has a bidirectional spiral groove 41 designed on its end face.

[0018] Furthermore, one end of the welded metal bellows assembly 1 is fixedly connected to the bushing 3, and the other end of the welded metal bellows assembly 1 is tightly fitted with the stationary ring 4 when static. The other end of the welded metal bellows assembly 1 is in close contact with the stationary ring 4, forming a sealed end face. Because the welded metal bellows assembly 1 contains a moving ring, when the welded metal bellows assembly 1 moves, a gap is generated between the end face of the other end of the welded metal bellows assembly 1 and the contact surface of the stationary ring 4, avoiding direct contact friction. The outer circle of the end face of the stationary ring 4 contains gaseous flare gas, and the inner circle contains liquid turbine oil.

[0019] Furthermore, the spiral grooves on the inner circle of the bidirectional spiral groove 41 have opposite rotation directions to the spiral grooves on the outer circle of the bidirectional spiral groove 41. The groove depth of the bidirectional spiral groove 41 is 0.008 mm, and the circumferential distribution angle of the bidirectional spiral groove 41 is α, where α is 20°~30°, so as to realize bidirectional pumping of turbine oil.

[0020] During operation, one end of the welded metal bellows assembly 1 is fixedly connected to the bushing 3, and the other end of the welded metal bellows assembly 1 is in close contact with the stationary ring 4 to form a sealing end face.

[0021] Because the pressure of the flare gas is higher than that of the turbine oil, the outer circle of the sealing end face contains the gas phase of the flare gas, while the inner circle contains the liquid phase of the turbine oil.

[0022] The bidirectional spiral groove 41 on the end face of the stationary ring 4 is designed so that the spiral groove at the inner circle delivers turbine oil to the outer circle (upstream pumping), providing liquid lubrication for the sealing end face and forming the lubricating film required for normal sealing operation.

[0023] Meanwhile, the reverse spiral groove at the outer circle transports the turbine oil back to the inner circle (downstream pumping). The bidirectional pumping effect combining upstream and downstream pumping reduces leakage at the sealing end face while retaining the advantages of upstream pumping.

[0024] The sealing device provided by this utility model eliminates the need for an additional sealing auxiliary system. It directly utilizes the environment within the sealing chamber of the gas holder screw compressor, achieving self-lubrication and sealing through a bidirectional pumping mechanism. This significantly simplifies the system structure and reduces initial investment and operating costs. The bidirectional pumping mechanism includes a spiral groove at the inner circumference that transports turbine oil to the outer circumference (upstream pumping), forming a liquid lubricating film; and a reverse spiral groove at the outer circumference that transports turbine oil back to the inner circumference (downstream pumping). Together, these mechanisms maintain a non-contact state at the sealing end faces, significantly reducing leakage and sealing power consumption. Meanwhile, because the sealing end face forms a non-contact seal, the sealing power consumption is significantly reduced, and the service life and reliability are improved.

[0025] in, Figure 1 In the diagram, a is the drain outlet, b is the medium end, and c is the atmospheric end.

[0026] This invention is applicable to screw compressors, with flare gas or mixed gas as the working medium, working temperature not exceeding 260℃, working pressure not exceeding 2MPa, and speed not exceeding 3000RPM, demonstrating wide applicability and stability.

[0027] The bidirectional pumping mechanism optimizes the geometric parameters of the spiral groove (groove depth, circumferential distribution angle) and the physical properties of the turbine oil, thereby achieving efficient formation and stable maintenance of the lubricating film between the sealing end faces, significantly improving the reliability and service life of the seal.

[0028] Working principle: During sealed operation, the outer circle of the end face of the welded metal bellows assembly 1 contains gaseous flare gas, while the inner circle of the welded metal bellows assembly 1 contains liquid turbine oil. The working pressure of the flare gas is higher than that of the turbine oil.

[0029] This invention does not require additional sealing support; instead, it utilizes the environment within the sealed cavity of the gas holder screw compressor to operate.

[0030] During sealing operation, the spiral groove at the inner circle forcefully pumps the turbine oil from the inner circle of the end face to the outer circle, a process known as upstream pumping. Upstream pumping provides liquid lubrication to the sealing end face and forms the lubricating film required for normal sealing operation. The liquid turbine oil is mechanically compressed within the spiral groove to form a lubricating film with a certain rigidity, generating lifting force that pushes a 3-5 micrometer gap between one end face of the welded metal bellows assembly 1 and the end face of the stationary ring 4, changing the sealing end face from contact-type mixed friction to non-contact. Upstream pumping achieves non-contact sealing, significantly improving power consumption, service life, and reliability. However, the leakage rate is relatively high, 10-20 times that of contact seals, resulting in poor economic efficiency. The reverse spiral groove designed and machined at the outer circle reverses the flow of turbine oil pumped upstream, from the outer circle to the inner circle, a process known as downstream pumping. This bidirectional pumping, combining upstream and downstream pumping, retains the advantages of upstream pumping while reducing the leakage rate of the sealing end face to only 1-2 times that of contact seals, fully meeting the user's economic requirements.

[0031] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0032] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A bellows single-end-face bidirectional pumping mechanical seal device, comprising a welded metal bellows assembly (1), a gland (2), a shaft sleeve (3) and a static ring (4), characterized in that, The end face of the stationary ring (4) is designed with a bidirectional spiral groove (41). The spiral groove at the inner circle of the bidirectional spiral groove (41) has the opposite spiral direction to the spiral groove at the outer circle of the bidirectional spiral groove (41).

2. The bellows single-end-face bidirectional pumping mechanical seal apparatus according to claim 1, characterized by, One end of the welded metal bellows assembly (1) is fixedly connected to the bushing (3), and the other end of the welded metal bellows assembly (1) is tightly fitted to the stationary ring (4) when static.

3. The bellows single-end-face bi-directional pumping mechanical seal apparatus according to claim 1, wherein, The depth of the bidirectional spiral groove (41) is 0.008 mm.

4. The bellows single-end-face bi-directional pumping mechanical seal apparatus according to claim 1, wherein, The circumferential distribution angle of the bidirectional spiral groove (41) is α; α is 20°~30°.

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