Sealing structure for star wheel shaft of single-screw compressor

Abstract

A star wheel shaft sealing structure of a single-screw compressor comprises an upper bearing seat, a lower bearing seat and a bearing seat which are structurally symmetrical, bearings are mounted in the bearing seats, and two ends of a star wheel shaft are respectively mounted in the corresponding bearings, and is characterized in that a lip-shaped sealing ring is mounted at one end, close to the bearings, of the star wheel shaft; a mechanical sealing static ring and a mechanical sealing moving ring are mounted on the star wheel shaft, the mechanical sealing static ring is connected with a bearing seat through a static ring pin and is sealed with the bearing seat through a static ring O-shaped ring, and the mechanical sealing moving ring is fixed on the star wheel shaft through a moving ring fastening screw and is sealed with the star wheel shaft through a moving ring O-shaped ring; an isolation buffer chamber is formed between the lip-shaped sealing ring and the mechanical sealing static ring, and a sweeping gas inlet channel and a sweeping gas exhaust channel which are communicated with the isolation buffer chamber are arranged on the bearing seat. According to the utility model, the compression of mixed gas of nitrogen and tetrahydrofuran is realized, and no leakage is generated at the end of the star wheel shaft. The service life of the bearing is prolonged.

Description

Technical Field

[0001] The utility model relates to a sealing technology, in particular to a bearing sealing mechanism of a corrosion-resistant compressor, specifically a planetary gear shaft sealing structure of a single-screw compressor. Background Art

[0002] Nitrogen is required as a protective gas for tetrahydrofuran storage tanks or reactors. Nitrogen will be discharged together with tetrahydrofuran vapor during loading and unloading or reaction. In order to enhance the condensation effect, a compressor is used to pressurize the exhaust gas and then condense it. Tetrahydrofuran is a strong solvent. When its vapor comes into contact with the bearings, the bearing grease will absorb the tetrahydrofuran vapor, causing the grease to deteriorate and shorten the bearing life. Tetrahydrofuran is flammable and explosive, so its leakage to the air must be reduced. Utility Model Content

[0003] The utility model aims to design a single screw compressor planetary wheel shaft sealing structure to solve the problem that the planetary wheel shaft bearing of the single screw compressor for processing tetrahydrofuran is easily scrapped due to corrosion, which affects the service life of the compressor.

[0004] The technical solution of the utility model is:

[0005] A single-screw compressor planetary shaft sealing structure comprises symmetrical upper and lower bearing seats 1, mounted on a casing 2. Bearings 3 are mounted in the bearing seat 1, and both ends of a planetary shaft 4 are mounted in corresponding bearings 3. The structure is characterized in that a lip seal ring 8 is mounted on the end of the planetary shaft 4 closest to the bearing. The inner ring of the lip seal ring 8 forms a dynamic seal with the planetary shaft 4, while the outer ring forms a static seal with the bearing seat 1. A mechanical seal stationary ring 9 and a mechanical seal dynamic ring 10 are mounted on the planetary shaft 4. The mechanical seal stationary ring 9 is connected to the bearing seat 1 via a stationary ring pin 11 and is sealed to the bearing seat 1 via a stationary ring O-ring 12. The mechanical seal dynamic ring 10 is fixed to the planetary shaft 4 via a dynamic ring set screw 13 and is sealed to the planetary shaft via a dynamic ring O-ring 14. An isolation buffer chamber 15 is formed between the lip seal ring 8 and the mechanical seal stationary ring 9. The bearing seat 1 is provided with a purge gas inlet channel 16 and a purge gas exhaust channel 17, which communicate with the isolation buffer chamber 15.

[0006] A bearing chamber cover 5 is installed on the bearing seat 1 , and a bearing chamber 6 is formed between the bearing chamber cover 5 and the bearing 3 . A nitrogen inlet 7 is provided on the bearing chamber cover 5 to form a positive pressure in the bearing chamber 6 .

[0007] The nitrogen inlet pressure of the nitrogen inlet 7 is 20-100 kPa.

[0008] The surface of the segment of the star wheel shaft 4 in contact with the lip seal ring is sprayed with a wear-resistant and corrosion-resistant coating 19 such as tungsten carbide or chromium oxide ceramic.

[0009] The bearing 3 is a grease-lubricated rolling bearing.

[0010] A bearing seat O-ring 20 is installed between the bearing seat 1 and the housing 2.

[0011] The upper part of the mechanical seal dynamic ring 10 is inlaid with sealing graphite, and the upper and lower parts of the mechanical seal dynamic ring 10 are laser welded into a whole using a metal bellows to ensure sealing while providing sealing pre-tightening force for the graphite.

[0012] Beneficial effects of the utility model:

[0013] The utility model realizes the compression of nitrogen and tetrahydrofuran mixed gas without leakage at the star wheel shaft end, thereby extending the service life of the bearing.

[0014] The utility model has a simple structure and is easy to install. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a structural diagram of the present utility model. Among the figure, 21 is the bearing cover O-ring, and 22 is the bolt. DETAILED DESCRIPTION

[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0017] The structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in this specification for understanding and reading by those familiar with this technology. They are not used to limit the conditions for implementation of the utility model and therefore have no substantial technical significance. Any modification of the structure, change in the proportional relationship, or adjustment of the size should still fall within the scope of the technical content disclosed in this utility model without affecting the efficacy and purpose of the utility model. At the same time, terms such as "upper", "lower", "left", "right", and "middle" quoted in this specification are only for the convenience of description and are not used to limit the scope of implementation. Changes or adjustments in their relative relationships should also be considered as the scope of implementation of the utility model without substantially changing the technical content.

[0018] like Figure 1 shown.

[0019] A single-screw compressor planetary gear shaft sealing structure comprises symmetrical upper and lower bearing seats 1, mounted on a casing 2. A bearing seat O-ring 20 is installed between the bearing seat 1 and the casing 2. A bearing chamber cover 5 is mounted on the bearing seat 1, forming a bearing chamber 6 between the bearing chamber cover 5 and a bearing 3 (a grease-lubricated rolling bearing). A nitrogen inlet 7 is provided on the bearing chamber cover 5, with a nitrogen inlet pressure of 20 to 100 kPa to create a positive pressure in the bearing chamber 6. Bearings 3 are mounted in the bearing seat 1, and both ends of the planetary gear shaft 4 are mounted in corresponding bearings 3. The structure is characterized in that a lip seal ring 8 is installed on the end of the planetary gear shaft 4 closest to the bearing. The inner ring of the lip seal 8 forms a dynamic seal with the planet shaft 4, while the outer ring forms a static seal with the bearing seat 1. A mechanical seal stationary ring 9 and a mechanical seal dynamic ring 10 are mounted on the planet shaft 4. The mechanical seal stationary ring 9 is connected to the bearing seat 1 via a stationary ring pin 11 and is sealed to the bearing seat 1 via a stationary ring O-ring 12. The mechanical seal dynamic ring 10 is fixed to the planet shaft 4 via a dynamic ring set screw 13 and is sealed to the planet shaft via a dynamic ring O-ring 14. An isolation buffer chamber 15 is formed between the lip seal 8 and the mechanical seal stationary ring 9. The bearing seat 1 is provided with a purge gas inlet channel 16 and a purge gas exhaust channel 17, which communicate with the isolation buffer chamber 15. The surface of the planet shaft 4 section in contact with the lip seal is spray-coated with a wear-resistant and corrosion-resistant coating 19 made of tungsten carbide or chromium oxide ceramic.

[0020] The utility model's single-screw compressor planetary wheel shaft sealing structure achieves compression of a nitrogen and tetrahydrofuran mixture without leakage at the planetary wheel shaft end. Its features and principles are as follows:

[0021] 1. The star wheel shaft is a rotating shaft, and both ends are non-drive shafts. The upper and lower sealing structures are the same. The sealing principle is explained using the upper part as an example.

[0022] 2. A mechanical seal dynamic ring is installed on the star wheel shaft. The mechanical seal dynamic ring is connected to the star wheel shaft through the set screw at the bottom. There is an O-ring on the top of the set screw to seal between the dynamic ring and the star wheel shaft. The upper part of the dynamic ring is inlaid with sealing graphite. The upper and lower parts of the dynamic ring are laser welded as a whole using a metal bellows to ensure sealing while providing sealing pre-tightening force for the graphite.

[0023] 3 The upper part of the graphite moving ring is the mechanical seal static ring. There is an O-ring seal between the static ring and the bearing seat, and a pin is positioned to prevent it from rotating. The contact surface between the moving ring and the static ring is the dynamic sealing surface.

[0024] 4. A lip seal is installed inside the bearing seat. The material is self-lubricating and high-temperature resistant glass fiber reinforced polytetrafluoroethylene. The inner ring of the lip seal forms a dynamic seal with the shaft, and the outer ring forms a static seal with the bearing seat.

[0025] 5 The shaft section in contact with the lip seal is sprayed with wear-resistant and corrosion-resistant coatings such as tungsten carbide or chromium oxide ceramics.

[0026] 6. A grease-lubricated rolling bearing is installed on the upper part of the lip seal.

[0027] 7. The upper part of the bearing seat is the bearing chamber cover, which is sealed with an O-ring and has a nitrogen inlet on the bearing chamber cover.

[0028] 8. An O-ring is used to seal between the bearing seat and the casing. There are two vents on the bearing seat as the purge gas inlet and outlet.

[0029] 9 The bearing chamber cover, bearing cover O-ring, lip seal and bolts form a closed bearing chamber. When the star shaft rotates, the lip seal and the spray-coated shaft form a dynamic seal, and the O-ring is a static seal. At the same time, 20~100kPa nitrogen is introduced into the nitrogen purge port to maintain positive pressure in the bearing chamber.

[0030] 10 Mechanical seal dynamic ring, mechanical seal static ring, dynamic ring O-ring, static ring O-ring, bearing seat, casing, bearing seat O-ring, and bolts form the internal seal of the casing. The mechanical seal dynamic ring and the mechanical seal static ring are dynamic seals, and the O-ring is a static seal.

[0031] 11 The mechanical seal dynamic ring and the mechanical seal static ring form the first pair of dynamic seals, the lip seal and the shaft form the second pair of dynamic seals, and there is an annular isolation buffer chamber between the two pairs of dynamic seals. The isolation buffer chamber is connected to the purge gas inlet and purge gas exhaust of the bearing seat.

[0032] 12 The rotary seal between the dynamic and static rings of the mechanical seal is a liquid film seal. A small amount of tetrahydrofuran liquid will seep out from the dynamic seal surface and evaporate into the isolation buffer chamber. Purge nitrogen is introduced from the purge air inlet and discharged from the purge exhaust port and connected to the factory waste gas treatment system, forming organized emissions. The purge gas pressure is 1~10kPa.

[0033] 13 In this structure, all O-rings are used only as static seals, eliminating the impact of O-ring swelling on the sealing system.

[0034] 14 forms three independent sealed chambers, namely the bearing chamber, the isolation buffer chamber, and the internal sealing chamber of the casing. The nitrogen pressure entering the bearing chamber is the highest. If there is a leak, it will enter the isolation buffer chamber. The leak in the internal sealing chamber of the casing will also enter the isolation buffer chamber. The purge gas in the isolation buffer chamber will quickly take it away into the factory exhaust gas treatment system, ensuring the service life of the bearing. At the same time, no unorganized leakage will occur, ensuring safe use.

[0035] The above embodiments are only preferred implementation methods of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and equivalent substitutions can be made without departing from the principles of the present invention. These technical solutions after improvements and equivalent substitutions to the claims of the present invention all fall within the scope of protection of the present invention.

[0036] The parts not involved in the present invention are the same as the existing technology or can be implemented by using the existing technology.

Claims

1. A single-screw compressor planetary gear shaft sealing structure, comprising upper and lower bearing seats (1) of symmetrical structure, wherein the bearing seat (1) is mounted on a casing (2), a bearing (3) is mounted in the bearing seat (1), and both ends of the planetary gear shaft (4) are respectively mounted in corresponding bearings (3), wherein the structure is characterized by: A lip seal ring (8) is installed on one end of the star wheel shaft (4) close to the bearing, and a dynamic seal is formed between the inner ring of the lip seal ring (8) and the star wheel shaft (4), and a static seal is formed between the outer ring and the bearing seat (1); a mechanical seal static ring (9) and a mechanical seal dynamic ring (10) are installed on the star wheel shaft (4), the mechanical seal static ring (9) is connected to the bearing seat (1) through a static ring pin (11), and is sealed with the bearing seat (1) through a static ring O-ring (12); the mechanical seal dynamic ring (10) is fixed to the star wheel shaft (4) through a dynamic ring set screw (13), and is sealed with the star wheel shaft through a dynamic ring O-ring (14); an isolation buffer chamber (15) is formed between the lip seal ring (8) and the mechanical seal static ring (9), and a purge gas inlet channel (16) and a purge gas exhaust channel (17) communicating with the isolation buffer chamber (15) are provided on the bearing seat (1).

2. The single-screw compressor planetary gear shaft sealing structure according to claim 1, characterized in that: A bearing chamber cover (5) is installed on the bearing seat (1), and a bearing chamber (6) is formed between the bearing chamber cover (5) and the bearing (3). A nitrogen inlet (7) is provided on the bearing chamber cover (5) to form a positive pressure in the bearing chamber (6).

3. The single-screw compressor planetary gear shaft sealing structure according to claim 2, characterized in that: The nitrogen inlet pressure of the nitrogen inlet (7) is 20-100 kPa.

4. The single-screw compressor planetary gear shaft sealing structure according to claim 1, characterized in that: The surface of the axis section of the star wheel shaft (4) in contact with the lip seal ring is sprayed with a tungsten carbide or chromium oxide ceramic coating (19).

5. The single-screw compressor planetary gear shaft sealing structure according to claim 1, characterized in that: The bearing (3) is a grease-lubricated rolling bearing.

6. The single-screw compressor planetary gear shaft sealing structure according to claim 1, characterized in that: A bearing seat O-ring (20) is installed between the bearing seat (1) and the housing (2).

7. The single-screw compressor planetary gear shaft sealing structure according to claim 1, characterized in that: The upper part of the mechanical seal dynamic ring (10) is inlaid with sealing graphite, and the upper and lower parts of the mechanical seal dynamic ring (10) are laser-welded into a whole using a metal bellows, thereby ensuring sealing while providing sealing pre-tightening force for the graphite.

Images