A method for regulating and controlling automatic balancing of axial force of centrifugal compressor

Abstract

The application provides a kind of centrifugal compressor axial force automatic balancing regulation and control method, comprising: step one, confirming control target;Step two, tracking the reading of shaft displacement monitoring probe;Step three, adjusting the pressure of balance disc high pressure adjusting chamber;Step four, the reading of shaft displacement monitoring probe returns to zero position.The application increases wheel disc seal between the last stage impeller and balance disc of centrifugal compressor, which can reduce the stress area of the last stage impeller on which the gas pressure at the outlet of the last stage impeller acts, and make the gas at the high pressure side of the balance disc form an independent chamber, and connect the balance disc high pressure adjusting chamber with the outlets of each stage impeller of the centrifugal compressor through a pressure pipeline.Electric regulating valve is arranged on each stage pressure pipeline, which can adjust the gas pressure in the chamber at the high pressure side of the balance disc.According to the monitoring of rotor shaft displacement, the gas pressure in the chamber at the high pressure side of the balance disc is adjusted, so as to realize the adjustment of rotor axial force, and ensure that the axial force borne by the thrust bearing is in the safe and efficient working range.

Description

Technical Field

[0001] This invention belongs to the field of centrifugal compressor technology, and relates to axial force, specifically to a method for automatically balancing the axial force of a centrifugal compressor. Background Technology

[0002] Centrifugal compressors, as core equipment, are widely used in various industries such as metallurgy, petrochemicals, air separation, video, and construction, occupying an extremely important position. Advances in gas dynamics research have continuously improved the efficiency of centrifugal compressors. Furthermore, the successful development of key technologies such as high-pressure sealing, the machining of small-flow, narrow-impeller systems, and multi-oil wedge bearings has solved a series of problems in the development of centrifugal compressors to higher pressure and wider flow ranges. This has greatly expanded the application range of centrifugal compressors, to the point that they can replace reciprocating compressors in many situations, thus significantly broadening their application scope.

[0003] In principle, in a centrifugal compressor, the high-speed rotating impeller exerts centrifugal force on the gas, and the diffusion effect in the diffusion channel increases the gas pressure. The impeller is fixed to the main shaft and rotates together. Gas enters the impeller axially, performs work on it, and is ejected radially, increasing its pressure in the process. In this structure, the force exerted on the impeller by the high-pressure gas at the outlet is greater than the force exerted by the low-pressure gas, thus generating an axial force on the rotor from the outlet to the inlet.

[0004] The high-speed rotor of a centrifugal compressor is constantly subjected to an axial force from the high-pressure end to the low-pressure end. Under the action of this axial force, the rotor will undergo axial displacement in the direction of the force. This axial displacement will cause relative movement between the journal and the bearing, potentially damaging the bearing or journal. More seriously, the rotor displacement can lead to friction and collision between the rotor and stator components, even causing machine damage. Because the rotor axial force can cause friction, wear, collision, and even machine damage, effective measures should be taken to balance and eliminate it.

[0005] The current common practice is to use a balance disc to balance part of the axial force, with the remaining axial force borne by the thrust bearing. Adding a balance disc after the final stage impeller of the centrifugal compressor, with one side connected to the outlet of the final stage impeller (for high-pressure gas) and the other side connected to the inlet of the first stage impeller (for low-pressure gas), creates a thrust opposite to the rotor's axial force, thus balancing part of the axial force.

[0006] However, in reality, centrifugal compressors can cause fluctuations in axial force under varying operating conditions. When the discharge pressure exceeds the rated value, the axial force becomes too large, exceeding the thrust bearing's load-bearing capacity, damaging the thrust bearing, and forcing the compressor to shut down, resulting in economic losses. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a method for automatically balancing the axial force of a centrifugal compressor, thereby solving the technical problem in the prior art where large pressure fluctuations on the high-pressure side of the balance disc easily damage the thrust bearing.

[0008] To solve the above-mentioned technical problems, the present invention adopts the following technical solution.

[0009] A method for automatically balancing the axial force of a centrifugal compressor is disclosed. The method employs an automatic axial force balancing device for the centrifugal compressor. The automatic axial force balancing device includes a main shaft, which is fitted with a housing. The front and rear ends of the main shaft extending out of the housing are respectively mounted on support bearings, and the rear part of the main shaft extending out of the housing is mounted on a thrust bearing. A final stage impeller and a balance disc are sequentially mounted on the main shaft from the inlet end to the outlet end along the axis.

[0010] The main shaft is coaxially fitted with a first sealing sleeve and a second sealing sleeve for the adjustment cavity, which are respectively fixedly installed inside the housing; the first sealing sleeve and the second sealing sleeve for the adjustment cavity are coaxially arranged, with the first sealing sleeve for the adjustment cavity located axially behind the second sealing sleeve for the adjustment cavity.

[0011] A balance disc seal is provided between the balance disc and the first sealing sleeve of the regulating chamber, and a wheel disc seal is provided between the wheel disc of the final stage impeller and the second sealing sleeve of the regulating chamber; the outer diameter of the wheel disc seal is smaller than the outer diameter of the balance disc.

[0012] The final stage impeller, the wheel seal, the second sealing sleeve of the regulating chamber, the housing, the first sealing sleeve of the regulating chamber, the balance disc seal, and the balance disc form a balance disc high-pressure regulating chamber.

[0013] The high-pressure regulating chamber of the balance plate is connected to one end of the main pressure pipe, and the other end of the main pressure pipe is connected to one or more branch pressure pipes. The other end of one or more branch pressure pipes is connected to the gas flow channel at the outlet of each stage impeller of the centrifugal compressor. The branch pressure pipe at the outlet of each stage impeller is independently controlled to regulate the gas pressure in the high-pressure regulating chamber of the balance plate, thereby achieving automatic axial force balance control.

[0014] The present invention also has the following technical features.

[0015] Furthermore, each of the support pressure pipes is equipped with an electric regulating valve; and an axial displacement monitoring probe is installed near the rear end face of the main shaft extending out of the housing.

[0016] Specifically, the method includes the following steps.

[0017] Step 1: Identify the control objective.

[0018] As the speed of the centrifugal compressor increases, the outlet exhaust pressure of the centrifugal compressor increases, the main shaft moves at the intake end, the thrust bearing bears the residual axial force, the lubricating oil film of the centrifugal compressor is established, and when the reading of the shaft displacement monitoring probe tends to stabilize, the current shaft displacement monitoring probe reading is confirmed to be zero as the control target.

[0019] Step two: Track the readings of the shaft displacement monitoring probe.

[0020] As the load on the centrifugal compressor increases, the axial force gradually increases, the thrust bearing carries more residual axial force, the lubricating oil film thins, the lubricating oil film bearing capacity increases, and the reading of the shaft displacement monitoring probe increases.

[0021] As the load on the centrifugal compressor decreases, the axial force gradually decreases, the thrust bearing carries less residual axial force, the lubricating oil film thickens, the lubricating oil film bearing capacity decreases, and the reading of the shaft displacement monitoring probe decreases.

[0022] Step 3: Adjust the pressure in the high-pressure regulating chamber of the balance disc.

[0023] When the axial force increases and the reading of the axial displacement monitoring probe is greater than zero, the valve opening of the electric regulating valve on the branch pressure pipeline is controlled to increase the pressure in the high-pressure regulating chamber of the balance disc, thereby increasing the force of the balance disc and reducing the axial force.

[0024] When the axial force decreases and the reading of the axial displacement monitoring probe is less than zero, the valve opening of the electric regulating valve on the pressure-reducing pipeline is controlled to reduce the pressure in the high-pressure regulating chamber of the balance disc, thereby reducing the force of the balance disc and increasing the axial force.

[0025] Step four: The reading of the shaft displacement monitoring probe returns to zero.

[0026] As the opening of the electric regulating valve changes, the balance disc gradually balances the increased axial force, reducing the residual axial force, thus reducing the axial force acting on the thrust bearing, decreasing the bearing capacity of the lubricating oil film, and decreasing the reading of the shaft displacement monitoring probe. The system gradually returns to zero, completing one control cycle. By repeating the control cycle multiple times, the automatic balancing of the axial force of the centrifugal compressor can be achieved.

[0027] Preferably, the impellers at each stage include a first-stage impeller, an intermediate-stage impeller, and a final-stage impeller; the first-stage impeller, the intermediate-stage impeller, and the final-stage impeller are sequentially installed on the main shaft from the inlet end to the outlet end along the axis.

[0028] Preferably, shaft end seals are respectively provided between the front and rear ends of the main shaft and the housing; the first sealing sleeve of the adjustment chamber, the balance disk seal, the balance disk, the main shaft, the shaft end seal and the housing form a balance disk low-pressure chamber; the balance disk low-pressure chamber is connected to the gas flow channel at the air inlet of the first stage impeller through the low-pressure chamber air guide pipe.

[0029] Preferably, an air inlet is provided on the housing axially forward of the first-stage impeller, and an exhaust volute is provided in the housing axially rear of the last-stage impeller. An air outlet is connected to the exhaust volute. The air inlet, the flow channel of the first-stage impeller, the flow channel of the intermediate-stage impeller, the flow channel of the last-stage impeller, the exhaust volute, and the air outlet form a complete gas flow channel within the housing.

[0030] Preferably, wheel cover seals are provided between the outer side of the wheel cover and the housing of the first-stage impeller, intermediate-stage impeller, and final-stage impeller.

[0031] Preferably, baffles are provided on the casing between the first-stage impeller and the intermediate-stage impeller, and on the casing between the intermediate-stage impeller and the final-stage impeller, forming a diffuser channel between the baffles and the casing.

[0032] More preferably, there are three pressure-inducing pipes, and the other end of the three pressure-inducing pipes are connected in sequence to the diffuser channel between the first-stage impeller and the intermediate-stage impeller, the diffuser channel between the intermediate-stage impeller and the last-stage impeller, and the exhaust volute.

[0033] Preferably, a partition seal is provided between the radially inner side of the partition and the partition sealing sleeve installed on the main shaft.

[0034] Preferably, the balance disc seal is installed on the radial outer side of the balance disc, the wheel disc seal is installed on the radial outer side of the wheel disc of the final stage impeller, and the partition seal is installed on the radial inner side of the partition.

[0035] Compared with the prior art, the present invention has the following technical effects.

[0036] (I) This invention adds a disc seal between the final stage impeller and the balance disc of the centrifugal compressor. This reduces the area of ​​the disc subjected to the pressure of the outlet gas from the final stage impeller, and also creates an independent chamber for the high-pressure side gas of the balance disc. This high-pressure regulating chamber is connected to the outlet of each stage impeller of the centrifugal compressor via a pressure-sensing pipe. Electric regulating valves are installed on the pressure-sensing pipes at each stage to adjust the gas pressure within the high-pressure side chamber of the balance disc. By adjusting the gas pressure within the high-pressure side chamber of the balance disc based on rotor shaft displacement monitoring, the axial force of the rotor is adjusted, ensuring that the axial force borne by the thrust bearing is within a safe and efficient operating range.

[0037] (II) This invention solves the problem of axial force from the design source. The highest pressure of the high-pressure regulating chamber of the balance disc is the highest pressure that the centrifugal compressor outlet may reach under abnormal operating conditions. The calculation of the diameter of the balance disc needs to be based on the maximum axial force, rather than the rated operating condition. Under the rated operating condition, the high-pressure regulating chamber of the balance disc and the diffuser flow channel of the intermediate stage impeller are used to achieve the adjustment of axial force under various operating conditions. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the overall internal structure of the automatic axial force balancing device for a centrifugal compressor.

[0039] Figure 2 This is a schematic diagram of the high-pressure regulating chamber of the balance disc.

[0040] The labels in the diagram represent the following: 1-Main shaft, 2-Housing shell, 3-Support bearing, 4-Thrust bearing, 5-Final stage impeller, 6-Balance disc, 7-First sealing sleeve of regulating chamber, 8-Balance disc seal, 9-Wheel disc seal, 10-Balance disc high-pressure regulating chamber, 11-Main pressure pipe, 12-Branch pressure pipe, 13-Electric regulating valve, 14-Shaft displacement monitoring probe, 15-First stage impeller, 16-Intermediate stage impeller, 17-Shaft end seal, 18-Balance disc low-pressure chamber, 19-Low-pressure chamber air guide pipe, 20-Gas flow channel, 21-Inlet, 22-Exhaust volute, 23-Outlet, 24-Wheel cover seal, 25-Baffle plate, 26-Diffuser flow channel, 27-Baffle plate sealing sleeve, 28-Baffle plate seal, 29-Second sealing sleeve of regulating chamber.

[0041] The specific content of the present invention will be further explained in detail below with reference to the embodiments. Detailed Implementation

[0042] It should be noted that, unless otherwise specified, all devices and components in this invention are devices and components known in the prior art.

[0043] The following are specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments. All equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0044] Example 1:

[0045] This embodiment provides an automatic axial force balancing device for a centrifugal compressor, such as... Figure 1 As shown, it includes a main shaft 1, which is fitted with a housing 2. The front and rear ends of the main shaft 1 extending out of the housing 2 are respectively mounted on support bearings 3, and the rear part of the main shaft 1 extending out of the housing is mounted on a thrust bearing 4. A final stage impeller 5 and a balance disc 6 are sequentially mounted on the main shaft 1 from the air inlet end to the air outlet end along the axis.

[0046] like Figure 1 As shown, the main shaft 1 is coaxially fitted with a first sealing sleeve 7 and a second sealing sleeve 29 for the adjustment cavity, which are fixedly installed inside the housing 2. The first sealing sleeve 7 and the second sealing sleeve 29 for the adjustment cavity are coaxially arranged, with the first sealing sleeve 7 located axially behind the second sealing sleeve 29. like Figure 2 As shown, a balance disc seal 8 is provided between the balance disc 6 and the first sealing sleeve 7 of the regulating chamber, and a wheel disc seal 9 is provided between the wheel disc of the final stage impeller 5 and the second sealing sleeve 29 of the regulating chamber; the outer diameter of the wheel disc seal 9 is smaller than the outer diameter of the balance disc 6 to ensure the regulating function of the high-pressure regulating chamber 10 of the balance disc.

[0047] like Figure 2 As shown, a high-pressure regulating chamber 10 is formed between the final stage impeller 5, the impeller seal 9, the second sealing sleeve 29 of the regulating chamber, the housing 2, the first sealing sleeve 7 of the regulating chamber, the balance disc seal 8, and the balance disc 6.

[0048] like Figure 1 As shown, the high-pressure regulating chamber 10 of the balance plate is connected to one end of the main pressure pipe 11, and the other end of the main pressure pipe 11 is connected to one or more branch pressure pipes 12. The other end of one or more branch pressure pipes 12 is connected to the gas flow channel 20 at the outlet of each stage impeller of the centrifugal compressor.

[0049] As a further embodiment, an electric regulating valve 13 is provided on the support pressure pipe 12; and an axial displacement monitoring probe 14 is provided near the rear end face of the main shaft 1 extending out of the housing 2.

[0050] As a preferred embodiment, the impellers at each stage include a first-stage impeller 15, an intermediate-stage impeller 16, and a final-stage impeller 5; the first-stage impeller 15, the intermediate-stage impeller 16, and the final-stage impeller 5 are sequentially installed on the main shaft 1 along the axis from the inlet end to the outlet end.

[0051] As a preferred embodiment, shaft end seals 17 are respectively provided between the front and rear ends of the main shaft 1 and the housing 2; a balance disk low-pressure chamber 18 is formed between the first sealing sleeve 7 of the adjustment chamber, the balance disk seal 8, the balance disk 6, the main shaft 1, the shaft end seal 17 and the housing 2; the balance disk low-pressure chamber 18 is connected to the gas flow channel 20 at the air inlet of the first stage impeller 15 through the low-pressure chamber air guide pipe 19.

[0052] As a preferred embodiment, an air inlet 21 is provided on the housing 2 axially forward of the first-stage impeller, and an exhaust volute 22 is provided in the housing 2 axially rearward of the last-stage impeller 5. An air outlet 23 is connected to the exhaust volute 22. The air inlet 21, the flow channel of the first-stage impeller 15, the flow channel of the intermediate-stage impeller 16, the flow channel of the last-stage impeller 5, the exhaust volute 22, and the air outlet 23 form a complete gas flow channel 20 in the housing 2.

[0053] In a further preferred embodiment, wheel cover seals 24 are respectively provided between the outer side of the wheel cover of the first-stage impeller 15, the intermediate-stage impeller 16, and the final-stage impeller 5 and the housing 2.

[0054] As a preferred embodiment, baffles 25 are respectively provided on the housing 2 between the first-stage impeller 15 and the intermediate-stage impeller 16 and on the housing 2 between the intermediate-stage impeller 16 and the final-stage impeller 5, and a diffuser channel 26 is formed between the baffles 25 and the housing 2.

[0055] More preferably, there are three branch pressure pipes 12, and the other end of the three branch pressure pipes 12 are connected in sequence to the diffuser channel 26 between the first stage impeller 15 and the intermediate stage impeller 16, the diffuser channel 26 between the intermediate stage impeller 16 and the last stage impeller 5, and the exhaust volute 22.

[0056] More preferably, a partition seal 28 is provided between the radial inner side of the partition 25 and the partition seal sleeve 27 installed on the main shaft 1.

[0057] As a preferred embodiment, the balance disc seal 8 is installed on the radial outer side of the balance disc 6, the wheel disc seal 9 is installed on the radial outer side of the wheel disc of the final stage impeller 5, and the partition seal 28 is installed on the radial inner side of the partition 25.

[0058] Example 2: This embodiment provides a method for automatically balancing the axial force of a centrifugal compressor, which is implemented using the automatic axial force balancing device for centrifugal compressors described in Embodiment 1. The pressure-guiding pipes 12 corresponding to the outlet of each impeller stage are independently controlled, achieving matching of similar pressures, reducing throttling losses, and regulating the gas pressure within the high-pressure regulating chamber 10 of the balance disc, thereby achieving automatic axial force balancing.

[0059] Specifically, the method includes the following steps.

[0060] Step 1: Identify the control objective.

[0061] As the speed of the centrifugal compressor increases, the outlet exhaust pressure of the centrifugal compressor increases, the main shaft 1 moves towards the intake end, the thrust bearing 4 bears the residual axial force, the lubricating oil film of the centrifugal compressor is established, and when the reading of the shaft displacement monitoring probe 14 tends to stabilize, the current reading of the shaft displacement monitoring probe 14 is confirmed to be zero as the control target.

[0062] Step two: Track the readings of the shaft displacement monitoring probe.

[0063] As the load on the centrifugal compressor increases, the axial force gradually increases, the thrust bearing 4 bears more residual axial force, the lubricating oil film thins, the lubricating oil film bearing capacity increases, and the reading of the shaft displacement monitoring probe 14 increases.

[0064] As the load on the centrifugal compressor decreases, the axial force gradually decreases, the thrust bearing 4 bears less residual axial force, the lubricating oil film thickens, the lubricating oil film bearing capacity decreases, and the reading of the shaft displacement monitoring probe 14 decreases.

[0065] Step 3: Adjust the pressure in the high-pressure regulating chamber of the balance disc.

[0066] When the axial force increases and the reading of the axial displacement monitoring probe 14 is greater than zero, the valve opening of the electric regulating valve 13 on the support pressure pipeline 12 is controlled to increase the pressure in the high pressure regulating chamber 10 of the balance disc, thereby increasing the force of the balance disc 6 and reducing the axial force.

[0067] When the axial force decreases and the reading of the axial displacement monitoring probe 14 is less than zero, the valve opening of the electric regulating valve 13 on the support pressure pipeline 12 is controlled to reduce the pressure in the high pressure regulating chamber 10 of the balance disc, thereby reducing the force of the balance disc 6 and increasing the axial force.

[0068] This step can stabilize the force on the thrust bearing 4 by adjusting the pressure in the high-pressure regulating chamber 10 of the balance disc, thus ensuring the stability of the force on the thrust bearing 4.

[0069] Step four: The reading of the shaft displacement monitoring probe returns to zero.

[0070] As the opening degree of the electric regulating valve 13 changes, the balance disc 6 gradually balances the increased axial force, the residual axial force decreases, the axial force acting on the thrust bearing 4 decreases, the bearing capacity of the lubricating oil film decreases, the reading of the shaft displacement monitoring probe 14 decreases, and it gradually returns to zero, completing one control cycle; repeating the control cycle multiple times, the automatic balancing of the axial force of the centrifugal compressor is achieved.

Claims

1. A method for automatically balancing the axial force of a centrifugal compressor, wherein the method is implemented using an automatic axial force balancing device for the centrifugal compressor, the automatic axial force balancing device for the centrifugal compressor includes a main shaft (1), a housing (2) is fitted over the main shaft (1), the front and rear ends of the main shaft (1) extending out of the housing (2) are respectively mounted on support bearings (3), and the rear part of the main shaft (1) extending out of the housing is mounted on a thrust bearing (4); a final stage impeller (5) and a balance disc (6) are sequentially mounted on the main shaft (1) along the axis from the inlet end to the outlet end; characterized in that: The main shaft (1) is coaxially fitted with a first sealing sleeve (7) and a second sealing sleeve (29) for the adjustment cavity. The first sealing sleeve (7) and the second sealing sleeve (29) for the adjustment cavity are respectively fixedly installed inside the housing (2). The first sealing sleeve (7) and the second sealing sleeve (29) for the adjustment cavity are coaxially arranged, and the first sealing sleeve (7) for the adjustment cavity is located axially behind the second sealing sleeve (29). A balance disc seal (8) is provided between the balance disc (6) and the first sealing sleeve (7) of the regulating cavity, and a wheel disc seal (9) is provided between the wheel disc of the final stage impeller (5) and the second sealing sleeve (29) of the regulating cavity; the outer diameter of the wheel disc seal (9) is smaller than the outer diameter of the balance disc (6); The final stage impeller (5), the impeller seal (9), the second sealing sleeve of the regulating chamber (29), the housing (2), the first sealing sleeve of the regulating chamber (7), the balance disc seal (8) and the balance disc (6) form a balance disc high-pressure regulating chamber (10). The high-pressure regulating chamber (10) of the balance plate is connected to one end of the main pressure pipe (11), and the other end of the main pressure pipe (11) is connected to one or more branch pressure pipes (12). The other end of one or more branch pressure pipes (12) is connected to the gas flow channel (20) at the outlet of each stage impeller of the centrifugal compressor. The branch pressure pipe (12) at the outlet of each stage impeller is independently controlled to regulate the gas pressure in the high-pressure regulating chamber (10) of the balance plate, thereby realizing the automatic axial force balance control. Electric regulating valves (13) are respectively installed on the branch pressure pipes (12); a shaft displacement monitoring probe (14) is installed near the rear end face of the main shaft (1) extending out of the housing (2). The method includes the following steps: Step 1, confirm the control objective: As the speed of the centrifugal compressor increases, the outlet exhaust pressure of the centrifugal compressor increases, the main shaft (1) moves towards the inlet end, the thrust bearing (4) bears the residual axial force, the lubricating oil film of the centrifugal compressor is established, and when the reading of the shaft displacement monitoring probe (14) tends to be stable, the current shaft displacement monitoring probe (14) reading is confirmed to be zero as the control target. Step 2: Track the readings of the shaft displacement monitoring probe: As the load on the centrifugal compressor increases, the axial force gradually increases, the thrust bearing (4) bears more residual axial force, the lubricating oil film thins, the lubricating oil film bearing capacity increases, and the reading of the shaft displacement monitoring probe (14) increases. As the load on the centrifugal compressor decreases, the axial force gradually decreases, the thrust bearing (4) bears less residual axial force, the lubricating oil film thickens, the lubricating oil film bearing capacity decreases, and the reading of the shaft displacement monitoring probe (14) decreases. Step 3: Adjust the pressure in the high-pressure regulating chamber of the balance disc: When the axial force increases and the reading of the axial displacement monitoring probe (14) is greater than zero, the valve opening of the electric regulating valve (13) on the branch pressure pipeline (12) is controlled to increase the pressure in the high pressure regulating chamber (10) of the balance disc, thereby increasing the force of the balance disc (6) and reducing the axial force. When the axial force decreases and the reading of the axial displacement monitoring probe (14) is less than zero, the valve opening of the electric regulating valve (13) on the branch pressure pipe (12) is controlled to reduce the pressure in the high pressure regulating chamber (10) of the balance plate, thereby reducing the force of the balance plate (6) and increasing the axial force. Step four: Return the readings of the shaft displacement monitoring probe to zero. As the valve opening of the electric regulating valve (13) changes, the balance disc (6) gradually balances the increased axial force, the residual axial force decreases, the axial force acting on the thrust bearing (4) decreases, the bearing capacity of the lubricating oil film decreases, the reading of the shaft displacement monitoring probe (14) decreases, and it gradually returns to zero, completing one control cycle; repeating the control cycle multiple times, the automatic balancing of the axial force of the centrifugal compressor is achieved.

2. The method for automatically balancing the axial force of a centrifugal compressor as described in claim 1, characterized in that, The impellers at each stage include a first-stage impeller (15), an intermediate-stage impeller (16), and a final-stage impeller (5); the first-stage impeller (15), the intermediate-stage impeller (16), and the final-stage impeller (5) are installed sequentially along the axis from the inlet end to the outlet end on the main shaft (1).

3. The method for automatically balancing the axial force of a centrifugal compressor as described in claim 2, characterized in that, Shaft end seals (17) are respectively provided between the front and rear ends of the main shaft (1) and the housing (2); a balance disk low-pressure chamber (18) is formed between the first sealing sleeve (7) of the adjustment chamber, the balance disk seal (8), the balance disk (6), the main shaft (1), the shaft end seal (17) and the housing (2); the balance disk low-pressure chamber (18) is connected to the gas flow channel (20) at the air inlet of the first stage impeller (15) through the low-pressure chamber air guide pipe (19).

4. The method for automatically balancing the axial force of a centrifugal compressor as described in claim 2, characterized in that, An air inlet (21) is provided on the housing (2) axially in front of the first-stage impeller, and an exhaust volute (22) is provided in the housing (2) axially behind the last-stage impeller (5). An air outlet (23) is connected to the exhaust volute (22). The air inlet (21), the flow channel of the first-stage impeller (15), the flow channel of the intermediate-stage impeller (16), the flow channel of the last-stage impeller (5), the exhaust volute (22), and the air outlet (23) form a complete gas flow channel (20) in the housing (2).

5. The method for automatically balancing the axial force of a centrifugal compressor as described in claim 2, characterized in that, The first-stage impeller (15), the intermediate-stage impeller (16) and the final-stage impeller (5) are respectively provided with wheel cover seals (24) between the outer side of the wheel cover and the housing (2).

6. The method for automatically balancing the axial force of a centrifugal compressor as described in claim 4, characterized in that, A baffle (25) is provided on the housing (2) between the first stage impeller (15) and the intermediate stage impeller (16) and on the housing (2) between the intermediate stage impeller (16) and the last stage impeller (5), respectively. A diffuser channel (26) is formed between the baffle (25) and the housing (2). The three branch pressure pipes (12) are connected in sequence to the diffuser flow channel (26) between the first stage impeller (15) and the intermediate stage impeller (16), the diffuser flow channel (26) between the intermediate stage impeller (16) and the last stage impeller (5), and the exhaust volute (22).

7. The method for automatically balancing the axial force of a centrifugal compressor as described in claim 6, characterized in that, A partition seal (28) is provided between the radial inner side of the partition (25) and the partition seal sleeve (27) installed on the main shaft (1).

8. The method for automatically balancing the axial force of a centrifugal compressor as described in claim 7, characterized in that, The balance disc seal (8) is installed on the radial outer side of the balance disc (6), the wheel disc seal (9) is installed on the radial outer side of the wheel disc of the final stage impeller (5), and the partition seal (28) is installed on the radial inner side of the partition (25).

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