A centrifugal steam compressor wheel back axial combined sealing structure

Abstract

This utility model discloses an axial combined sealing structure for the impeller back of a centrifugal steam compressor, enhancing the sealing effect of the compressor impeller back. It includes a gearbox high-speed shaft and a gearbox connecting ring. A combined steam seal sleeve is provided between the gearbox high-speed shaft and the gearbox connecting ring. The combined steam seal sleeve includes a comb-tooth steam seal body, a T-shaped carbon ring sleeve, an inlet ring, an outlet ring, and a water return cover. The inlet ring, outlet ring, and water return cover are sequentially fixed to one side of the comb-tooth steam seal body. Adjacent parts of the comb-tooth steam seal body, T-shaped carbon ring sleeve, inlet ring, outlet ring, and water return cover are separated by carbon rings. The inlet ring has an inlet port, and the outlet ring has an outlet port. The inlet port is used to introduce steam, and the outlet port is used to discharge steam. The pressure of the introduced steam is greater than the internal pressure of the compressor. The water return cover includes a water return cover body with a leakage port at the bottom. A high-speed shaft sleeve is provided on the gearbox high-speed shaft, and water-throwing teeth are provided on the high-speed shaft sleeve corresponding to the water return cover body.

Description

Technical Field

[0001] This utility model relates to the field of compressor technology, and in particular to an axial combined sealing structure for the wheel back of a centrifugal steam compressor. Background Technology

[0002] MVR steam compressors are mainly used in processes such as water treatment. Through a motor-driven mechanical speed-increasing gearbox, a centrifugal compressor impeller rotates at high speed to perform work on the saturated steam working medium, achieving the recompression and recycling of secondary steam within the system. In MVR circulating process systems, negative pressure evaporation technology, operating below atmospheric pressure, is typically used to reduce scaling in the falling film evaporator.

[0003] The MVR cycle process system operates under negative pressure for extended periods, which requires the compressor to have reliable overall sealing performance and strong sealing capabilities to ensure that atmospheric air does not penetrate into the compressor and become a non-condensable gas in the MVR system, thereby reducing the efficiency of the entire system.

[0004] Sealing is the process of preventing liquids or gases inside a machine from leaking out between the mating surfaces of two parts, as well as preventing external impurities and dust from entering, thus maintaining the normal operation of mechanical parts.

[0005] In steam compressor equipment, the centrifugal compressor impeller is a key core working component. The compressor body uses mature gasket and O-ring seal technologies, achieving excellent sealing performance. However, the impeller back has a large cavity and needs to achieve dynamic and static fit and sealing with the high-speed rotating main shaft. Therefore, the impeller back seal is the most critical core technology issue in MVR compressor sealing.

[0006] The impeller back seal of MVR centrifugal impellers generally adopts several sealing methods such as floating ring, labyrinth, carbon ring, and air-filled seal to seal the impeller back.

[0007] Floating ring seals are a type of oil film seal. They have a complex structure, require high manufacturing precision, and the sealing oil is prone to emulsification. Furthermore, leakage of the sealing oil can cause contamination of the compressed gas. Labyrinth seals commonly include axial comb seals and radial comb seals. Labyrinth seals have a simple structure and low cost, but there is a phenomenon where condensate from the seal moves along the shaft into the gearbox, causing the lubricating oil to emulsify and affecting the reliability of the compressor.

[0008] Carbon ring seals are a type of throttling contact floating ring seal, a relatively precise type of seal. Their sealing principle relies on the formation of a gas film between the carbon graphite floating ring and the shaft, thereby throttling and reducing pressure to prevent high-pressure gas from flowing to the low-pressure side. Gas-filled seals require the MVR process system to provide a certain flow rate and pressure of sealing vapor, creating a positive pressure environment in the gas-sealing cavity that is higher than the compressor's internal pressure, preventing gas leakage from the compressor and atmospheric infiltration into the compressor. Summary of the Invention

[0009] The purpose of this invention is to overcome the shortcomings of the prior art and provide an axial combined sealing structure for the impeller back of a centrifugal steam compressor, thereby enhancing the sealing effect of the impeller back of the steam compressor.

[0010] The purpose of this utility model is achieved as follows:

[0011] A combined axial sealing structure for a centrifugal steam compressor wheel back includes a gearbox high-speed shaft, a gearbox connecting ring, and a centrifugal compressor impeller. The centrifugal compressor impeller is mounted on the gearbox high-speed shaft. A combined steam seal sleeve is provided between the gearbox high-speed shaft and the gearbox connecting ring. The combined steam seal sleeve includes a comb-tooth steam seal body, a T-shaped carbon ring sleeve, an inlet ring, an outlet ring, and a return water cover. The inlet ring, outlet ring, and return water cover are sequentially fixed to one side of the comb-tooth steam seal body. The T-shaped carbon ring sleeve is located between the comb-tooth steam seal body and the inlet ring. Both ends of the T-shaped carbon ring sleeve are connected to the comb-tooth steam seal body and the inlet ring respectively through carbon rings. The steam inlet ring is used for isolation, and the steam outlet ring and the steam outlet ring are isolated by carbon rings. The steam outlet ring and the water return cover are also isolated by carbon rings. The steam inlet ring has a steam inlet, and the steam outlet ring has a steam outlet. The steam inlet is used to introduce steam, and the steam outlet is used to discharge steam. The pressure of the introduced steam is greater than the internal pressure of the compressor. The water return cover includes a water return cover body, and the lower part of the water return cover body has a leakage port. The high-speed shaft of the gearbox is equipped with a high-speed shaft sleeve, and the high-speed shaft sleeve is equipped with water-throwing teeth. The water-throwing teeth are used to throw the condensate out to the water return cover body, and the leakage port is used to discharge the collected condensate.

[0012] Preferably, the comb-tooth steam seal body, T-shaped carbon ring sleeve, steam inlet ring, steam outlet ring, and water return cover each include an upper half and a lower half, both of which are semi-circular, and the upper and lower halves are connected to each other as a ring-shaped whole by pins and screws.

[0013] Preferably, the comb-tooth steam seal body, T-shaped carbon ring sleeve, steam inlet ring, steam outlet ring, and water return cover are all provided with a labyrinth comb structure, and the labyrinth comb structure forms multiple throttling gaps between itself and the high-speed shaft of the gearbox.

[0014] Preferably, the carbon ring comprises three equally divided carbon ring segments, adjacent carbon ring segments are connected by a round hook tension spring, and the carbon ring is installed in the combined steam seal sleeve by a pin.

[0015] Preferably, the steam inlet and steam outlet are respectively equipped with hinged pipe joints, and the lower part of the steam inlet ring is provided with a drain pipe and a needle valve.

[0016] Preferably, the return water cover is provided with alternating high and low teeth, which cooperate with the water-throwing teeth on the high-speed shaft sleeve.

[0017] By adopting the above-mentioned technical solution, this utility model combines multiple sealing methods, including labyrinth seals, carbon ring seals, and gas-filled seals, to form a steam seal sleeve, thereby solving the sealing problem of the back of the compressor impeller of a steam compressor. Attached Figure Description

[0018] Figure 1 Schematic diagram of the compressor impeller back structure;

[0019] Figure 2 Schematic diagram of the combined steam seal sleeve;

[0020] Figure 3 : Schematic diagram of the carbon ring installation structure;

[0021] Figure 4 Schematic diagram of the combined steam seal sleeve connecting pipeline structure;

[0022] Figure 5 Schematic diagram of comb-tooth steam seal structure;

[0023] Figure 6 : Schematic diagram of the water return cover assembly structure.

[0024] Figure Labels

[0025] In the attached diagram: 1. Gearbox high-speed shaft; 2. Combined steam seal sleeve; 3. Gearbox connecting ring; 4. Centrifugal compressor impeller.

[0026] 21. Comb-tooth steam seal body; 22. T-type carbon ring sleeve; 23. Steam inlet ring; 24. O-ring seal; 25. Steam outlet ring; 26. Spring washer; 27. Socket head cap screw; 28. Water return cover; 29. ​​Spring washer; 210. Socket head cap screw; 211. Spring washer; 212. Socket head cap screw;

[0027] 31. Cylindrical pin; 32. Carbon ring; 33. Hook-shaped tension spring; 34. Steam inlet; 35. Steam outlet; 36. Liquid drain port;

[0028] 41. Needle valve; 42. Drainage pipeline; 43. Inlet hinged pipe joint; 44. Outlet hinged pipe joint.

[0029] 51. Socket head cap screw; 52. Spring washer; 53. Upper half of comb-tooth steam seal body; 54. Cylindrical pin; 55. Lower half of comb-tooth steam seal body;

[0030] 61. High-speed shaft sleeve, 62. Water return cover, 63. Water ejector gear, 64. Leakage port. Detailed Implementation

[0031] See Figures 1-6A combined axial sealing structure for the impeller back of a centrifugal steam compressor includes a gearbox high-speed shaft 1, a gearbox connecting ring 3, and a centrifugal compressor impeller 4. The centrifugal compressor impeller 4 is mounted on the gearbox high-speed shaft 1. A combined steam seal sleeve 2 is provided between the gearbox high-speed shaft 1 and the gearbox connecting ring 3. The combined steam seal sleeve 2 is located on the impeller back side of the centrifugal compressor impeller 4. The combined steam seal sleeve 2 includes a comb-tooth steam seal body 21, a T-shaped carbon ring sleeve 22, an inlet ring 23, an outlet ring 25, and a return water cover 28. The inlet ring 23, outlet ring 25, and return water cover 28 are sequentially fixed to one side of the comb-tooth steam seal body 21. The T-shaped carbon ring sleeve 22 is located between the comb-tooth steam seal body 21 and the inlet ring 23. The two ends of the T-shaped carbon ring sleeve 22 are respectively connected to carbon rings. The comb-tooth steam seal body 21 and the steam inlet ring 23 are isolated from each other. The steam inlet ring 23 and the steam outlet ring 25 are isolated from each other by a carbon ring. The steam outlet ring 25 and the return water cover 28 are isolated from each other by a carbon ring. The steam inlet ring 23 is provided with a steam inlet 34, and the steam outlet ring 25 is provided with a steam outlet 35. The steam inlet 34 is used to introduce steam, and the steam outlet 35 is used to discharge steam. The pressure of the introduced steam is greater than the pressure inside the compressor. The return water cover 28 includes a return water cover body 62. The lower part of the return water cover body 62 is provided with a leakage port 64. The high-speed shaft 1 of the gearbox is provided with a high-speed shaft sleeve 61. The high-speed shaft sleeve 61 is provided with water-throwing teeth 63. The water-throwing teeth 63 are used to throw the condensate out to the return water cover body 62. The leakage port 64 is used to discharge the collected condensate.

[0032] The comb-tooth steam seal body 21, T-shaped carbon ring sleeve 22, steam inlet ring 23, steam outlet ring 25, and water return cover 28 each consist of an upper and a lower half, both of which are semi-annular. The upper and lower halves are connected as a single annular unit by pins and screws. The comb-tooth steam seal body 21, T-shaped carbon ring sleeve 22, steam inlet ring 23, steam outlet ring 25, and water return cover 28 are all equipped with a labyrinthine comb structure, forming multiple throttling gaps between the labyrinthine comb structure and the high-speed shaft 1 of the gearbox. The carbon ring consists of three evenly divided carbon ring segments, adjacent carbon ring segments are connected by a round hook tension spring 33, and the carbon ring is installed inside the combined steam seal sleeve 2 by pins.

[0033] Hinged pipe joints are installed on the steam inlet 34 and steam outlet 35 respectively. A drain pipe 42 and a needle valve 41 are located at the lower part of the steam inlet ring 23. The return water cover 62 has alternating high and low teeth, which engage with the water-throwing teeth 63 on the high-speed shaft sleeve 61. The lower teeth give way to the water-throwing teeth 63, while the higher teeth prevent condensate from leaking out of the return water cover 62.

[0034] Specifically:

[0035] Appendix Figure 1As shown: Compressor impeller back seal structure. A certain clearance must be maintained between the rotating components of the centrifugal compressor, such as the high-speed shaft 1 of the gearbox and the centrifugal compressor impeller 4, and stationary components, such as the gearbox connecting ring 3. To reduce leakage through this clearance and prevent internal gas from leaking into the atmosphere, a sealing structure, such as a combined steam seal sleeve 2, must be installed on the impeller back.

[0036] Appendix Figure 2 As shown: The combined steam seal assembly structure. The combined steam seal assembly consists of five independent parts, such as the comb-tooth steam seal body 21, the T-shaped carbon ring sleeve 22, the inlet ring 23, the outlet ring 25, and the return water cover 28. The combined steam seal body can be axially mounted on the high-speed shaft of the gearbox, achieving integrated installation of the rotor assembly and ensuring the operational stability of the compressor's core rotor.

[0037] The five independent parts of the gas seal sleeve are all of a two-part structure, as shown in the attached diagram. Figure 5 As shown, the upper half 53 and lower half 55 of the comb-tooth steam seal body are connected as a whole by cylindrical pins and hexagonal head screws. The two-part structural design principle of the steam seal body, such as the T-type carbon ring sleeve 22, inlet ring 23, outlet ring 25, and return water cover 28, is the same as that of the comb-tooth steam seal body. The two-part structural design of the combined steam seal assembly allows the steam seal sleeve to be disassembled and installed separately on the compressor, greatly improving the maintenance efficiency of the steam seal assembly and making on-site maintenance simple and convenient.

[0038] As attached Figure 2 As shown, the comb-tooth steam seal body 21, T-type carbon ring sleeve 22, steam inlet ring 23, steam outlet ring 25, and water return cover 28 are all designed with a labyrinthine comb-tooth structure, forming a series of throttling gaps between the comb teeth and the high-speed shaft of the gearbox. When the compressor steam flows through the throttling gaps, the flow velocity increases, and the pressure and temperature decrease, with pressure being converted into velocity. The steam then enters the expansion cavity, forming a gas vortex, which leads to a decrease in velocity.

[0039] When steam flows through a series of throttling gaps in the combined steam seal, a pressure gradient is formed within the labyrinth seal, and the pressure inside the compressor tends to balance with the external atmospheric environment, thereby reducing compressor leakage and achieving the sealing effect of the present invention.

[0040] Appendix Figure 3 The diagram shows the carbon ring seal structure. The combined steam seal assembly includes four carbon rings made of M254D graphite. The carbon rings employ a three-lobed design, with each lobe featuring a dovetail-shaped outer groove. A hook-shaped tension spring 33 is fitted around the outside of the dovetail groove to form the carbon ring assembly into a ring shape, which is then mounted on the high-speed shaft. The carbon rings are fixed within the cavity between the steam seal assembly bodies by cylindrical pins 31.

[0041] Because the circular hook tension spring 33 has tension properties, it achieves self-compensation of the carbon ring structure, solving the defect of poor sealing effect after wear of the inner circle of the traditional sealing carbon ring. It is suitable for shaft end sealing of rotating machinery for a long time, and achieves the near-zero leakage sealing effect of the present invention.

[0042] Appendix Figure 3 As shown: a combined steam seal sleeve structure. High-pressure steam is introduced into the inlet ring for blocking. The high-pressure steam creates a pressure higher than that inside the compressor within the cavity of the inlet ring, completely isolating the compressor interior from the atmospheric environment. To achieve a better sealing effect, the inlet and outlet chambers of the sealing steam are divided into two independent chambers, such as the inlet ring and the outlet ring, separated by a set of carbon rings. Two independent layers of high-pressure sealing steam are formed in the inlet ring cavity and the outlet ring cavity, ensuring the sealing effect of this invention.

[0043] Appendix Figure 4 The diagram shows the piping structure of the combined steam seal assembly. Hinged pipe fittings 43 and 44 are installed at the reserved steam inlet and outlet ports; a drain pipe 42 and a needle valve 41 are installed at the reserved drain port. When liquid accumulates in the intake ring cavity, the needle valve 1 can be opened to drain the liquid, ensuring that the interior of the combined steam seal assembly is not corroded by the accumulated liquid.

[0044] Appendix Figure 6 The diagram shows the assembly structure of the return water cover. The return water cover body 62 is designed with staggered teeth of varying heights, which cooperate with the water-throwing teeth designed on the high-speed shaft sleeve 61. After a small amount of condensate enters the return water cover, the high-speed rotating water-throwing teeth throw the condensate out, hitting the return water cover. Under the action of gravity, the condensate is discharged from the combined steam seal sleeve through the leakage port at the bottom of the return water cover.

[0045] The design of the water return cover's water-throwing teeth and leakage port ensures that, based on the axial design, the steam seal sleeve of this invention can still prevent the condensate from flowing along the shaft into the gearbox, thus avoiding the problem of lubricating oil emulsification and significantly improving the reliability of the compressor.

[0046] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solution of this utility model and are not intended to limit it. Although the 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 to it in form and detail without departing from the scope defined by the claims of this utility model.

Claims

1. A centrifugal vapor compressor wheel back axial combined seal structure, comprising a gear box high speed shaft, a gear box connecting ring, a centrifugal compressor impeller, the centrifugal compressor impeller is installed on the gear box high speed shaft, a combined seal part sleeve is arranged between the gear box high speed shaft and the gear box connecting ring, characterized in that: The combined steam seal assembly includes a comb-tooth steam seal body, a T-shaped carbon ring sleeve, an inlet ring, an outlet ring, and a water return cover. The inlet ring, outlet ring, and water return cover are sequentially fixed to one side of the comb-tooth steam seal body. The T-shaped carbon ring sleeve is located between the comb-tooth steam seal body and the inlet ring. The two ends of the T-shaped carbon ring sleeve are isolated from the comb-tooth steam seal body and the inlet ring respectively by carbon rings. The inlet ring and outlet ring are isolated by carbon rings, and the outlet ring and water return cover are isolated by carbon rings. The inlet ring has an inlet port, and the outlet ring has an outlet port. The inlet port is used to introduce steam, and the outlet port is used to discharge steam. The pressure of the introduced steam is greater than the internal pressure of the compressor. The water return cover includes a water return cover body, and the lower part of the water return cover body has a leakage port. The high-speed shaft of the gearbox is equipped with a high-speed shaft sleeve, and the high-speed shaft sleeve is equipped with water-throwing teeth. The water-throwing teeth are used to throw condensate out to the water return cover body, and the leakage port is used to discharge the collected condensate. ​ 2. A centrifugal vapor compressor wheel back-to-shaft combination seal structure according to claim 1, characterized in that: The comb-tooth steam seal body, T-shaped carbon ring sleeve, steam inlet ring, steam outlet ring, and water return cover each include an upper half and a lower half, both of which are semi-circular. The upper and lower halves are connected to each other by pins and screws to form a ring-shaped whole.

3. A centrifugal vapor compressor wheel back-to-axle combination seal structure according to claim 1, wherein: The comb-tooth steam seal body, T-shaped carbon ring sleeve, steam inlet ring, steam outlet ring, and water return cover are all equipped with a labyrinth comb structure, which forms multiple throttling gaps between the labyrinth comb structure and the high-speed shaft of the gearbox.

4. A centrifugal vapor compressor wheel back-to-shaft combination seal structure according to claim 1, characterized in that: The carbon ring comprises three equally divided carbon ring segments, adjacent carbon ring segments are connected by a round hook tension spring, and the carbon ring is installed in the combined steam seal sleeve by a pin.

5. A centrifugal vapor compressor wheel back-to-shaft combination seal structure according to claim 1, characterized in that: The steam inlet and steam outlet are respectively equipped with hinged pipe joints, and the lower part of the steam inlet ring is provided with a drain pipe and a needle valve.

6. A centrifugal vapor compressor wheel back-to-axle combination seal structure according to claim 1, wherein: The return water cover is equipped with high and low staggered teeth, which cooperate with the water-throwing teeth on the high-speed shaft sleeve.

Images