A centrifugal compressor with built-in interstage flow channel device

Abstract

A centrifugal compressor with a built-in interstage flow channel device comprises a shell, a stator and a rotor with electromagnetic coils built in the shell, a primary gas compression device and a secondary gas compression device are respectively arranged at both ends of the shell, the gas compressed by the primary gas compression device is connected to the secondary gas compression device through the interstage flow channel built in the shell, the interstage flow channel and the shell are an integral structure, and valves and a fourth sensor are arranged on both sides, and the axial ends of the interstage flow channel are respectively used to install the primary gas compression device and the secondary gas compression device. This centrifugal compressor connects the primary gas compression device and the secondary gas compression device in series through the interstage flow channel built in the shell, and the gas is pressurized and heated by passing through the two-stage compression device inside the shell. The setting of the built-in interstage flow channel can effectively prevent the leakage of gas inside the centrifugal compressor, improve the energy efficiency of the whole machine, reduce the vibration of the whole machine and reduce the weight of the whole machine.

Description

Technical Field

[0001] The utility model relates to the field of centrifugal refrigeration compressors based on air floating bearing technology, in particular to a centrifugal compressor with a built-in interstage flow channel device. Background Art

[0002] Air-floating bearing technology has been widely promoted and applied in the centrifugal compressor industry, forming air-suspended centrifugal compressor products, which have the characteristics of high efficiency, low noise, low vibration, etc., and are widely used in aviation, rail transit, oxygen production and new energy vehicles. In the aviation field, air-suspended centrifugal compressors can provide air sources for the hydraulic, cooling, oxygen production and other systems of aircraft; in the rail transit field, air-suspended centrifugal compressors can provide air sources for brakes, drives, etc. of vehicles such as high-speed trains and subways; in the field of oxygen production, air-suspended centrifugal compressors can compress oxygen into a semi-liquid or liquid state for easy transportation and storage; in the field of new energy vehicles, air-suspended centrifugal compressors can provide hydrogen fuel cells with the oxygen required for electrochemical reactions, ensuring that the stack reaction can proceed smoothly. In recent years, air-suspended centrifugal compressors have also been widely used in the field of air conditioning and refrigeration. For example, South Korea's LG and Gree Group have successively launched air-suspended centrifugal refrigeration compressors based on gas dynamic bearing technology, and Qingdao Haier has launched an air-suspended centrifugal refrigeration compressor based on gas static bearing technology. The basic layout of the appearance structure of this type of product is that the high-speed motor is in the middle, and the first-stage centrifugal compressor and the second-stage centrifugal compressor are arranged back to back at both ends. The high-speed motor and the first-stage centrifugal compressor and the second-stage centrifugal compressor form a whole. An independent interstage pipeline is arranged outside the high-speed motor and its centrifugal compressor to connect the two-stage centrifugal compressor in series, usually connected and fastened by flanges or clamps, so as to achieve the purpose of pressurizing and heating the gas through the two-stage centrifugal compressor in sequence. The connection method of the external interstage pipeline of the two-stage centrifugal compressor may bring the following problems:

[0003] Problem 1: The external interstage pipeline increases the pipeline connection length between the two-stage centrifugal compressor, resulting in increased resistance loss along the airflow and local resistance loss, thus affecting the overall performance of the centrifugal compressor;

[0004] Problem 2: The external interstage pipeline with a certain weight affects the overall center of gravity distribution of the centrifugal compressor, and the center of gravity of the whole machine deviates from the center line of the rotor. Since the centrifugal compressor is a high-speed equipment, the deviation of the center of gravity may cause the vibration of the centrifugal compressor to increase, which may easily cause the bolts at the pipeline connection to loosen or the seals to age, and there is a risk of gas leakage at the connection;

[0005] Question 3: The economizer air supply pipeline of the chiller is usually connected to the external interstage pipeline. The external interstage pipeline will be impacted by the air flow from the air supply pipeline, which may cause resonance between the external interstage pipeline and the centrifugal compressor.

[0006] Question 4: The existence of external interstage pipelines affects the appearance of the centrifugal compressor, occupies more space, increases the cost of the centrifugal compressor, and is inconvenient to assemble and transport. In response to the above-mentioned problems, technical personnel in this field have proposed a new technical idea, which is to arrange the two-stage gas compressor device in the shell, and connect the two-stage gas compressor device in series by building an interstage flow channel under the shell. Since the high-speed motor and the centrifugal compressor are integrated and compactly designed, the space inside the shell is small. The technical solution of independently arranging the interstage flow channel inside the shell has not been found in the centrifugal compressor industry. Utility Model Content

[0007] The purpose of the utility model is to address the defects and shortcomings of the prior art and propose a method for inserting an interstage flow channel below the inside of a shell, which completely solves the related problems caused by the external interstage pipeline connection of a two-stage centrifugal compressor.

[0008] In order to achieve the above-mentioned purpose, the utility model provides a centrifugal compressor with a built-in interstage flow channel device, including a shell, a stator and a rotor with electromagnetic coils built in the shell, a first-stage gas compression device and a second-stage gas compression device are respectively provided at both ends of the shell, the gas compressed by the first-stage gas compression device is connected to the second-stage gas compression device through the interstage flow channel built in the shell, the interstage flow channel and the shell are an integral structure, and valve components and a fourth sensor are respectively arranged on both sides, the valve components are connected with the interstage flow channel and are mainly used for filling or sucking the working fluid of the centrifugal compressor, the fourth sensor is used to detect the pressure and temperature of the gas in the interstage flow channel; the axial ends of the interstage flow channel are respectively used to install the first-stage gas compression device and the second-stage gas compression device, the interstage flow channel is provided with an exhaust port to cooperate with the second-stage gas compression device and the second gas shell to form a second air inlet cavity, the gas in the second air inlet cavity passes through the second-stage gas compression device to form high-pressure and high-temperature gas and is discharged through the exhaust port, the third sensor is arranged on the outside of the exhaust port and is connected to the condenser of the chiller. This type of centrifugal compressor with a built-in interstage flow channel device connects the first-stage gas compression device and the second-stage gas compression device in series through the interstage flow channel built into the shell, thereby improving the pressure ratio of the centrifugal compressor to adapt to a wider range of operating conditions of the chiller, shortening the flow channel connection distance between the first-stage gas compression device and the second-stage gas compression device, reducing the pressure loss of the gas flowing through the interstage flow channel, reducing the vibration of the centrifugal compressor, and improving the overall performance of the centrifugal compression stage. In addition, the built-in interstage flow channel not only has a strong pressure bearing capacity, but also does not require additional joint connectors, thereby avoiding the risk of gas leakage inside the centrifugal compressor. In addition, the gas in the built-in interstage flow channel is usually in an overheated state, which can be used to heat the refrigerant liquid in the shell to prevent liquid from accumulating in the shell before the centrifugal compressor is started. The first-stage gas compression device includes a first impeller connected to one end of the rotor, the first impeller cooperates with the first volute to form a first air inlet chamber, the first air inlet chamber is connected to the first exhaust channel, the first exhaust channel is composed of the first volute channel in the first volute and the first bearing seat channel in the first bearing seat matched therewith, the first exhaust channel is connected to the interstage channel, the first bearing seat cooperates to install the first bearing sleeved with the rotor; a first thrust plate sleeved with the rotor is provided between the first impeller and the first bearing, the first thrust plate is sleeved with the first sealing seat on the outer periphery. The first exhaust channel is a volute-type channel, and the connection between the first exhaust channel and the interstage channel is completed inside the shell, which avoids the possibility of gas leakage caused by the external interstage pipeline connection, and even if leakage occurs, it leaks inside the shell.

[0009] The first air inlet cavity is provided with a first air shell which is a sealed connection shell on the outside. A guide vane adjustment device for controlling the air intake is installed in the first air shell. The guide vane adjustment device is connected to the chiller control system through a terminal board installed outside the first air shell. The terminal board serves as a line connection and sealing function. The guide vane adjustment device is connected to the first air inlet in the first air shell. The rotation opening of the guide vane is comprehensively adjusted according to the working condition of the chiller and the performance of the centrifugal compressor. The first air inlet is connected to the evaporator of the chiller, and a first sensor is arranged on the outside. The first sensor is used to detect the suction temperature and pressure of the centrifugal compressor. The guide vane adjustment device is installed in the first air shell and is completely sealed. Compared with other types of guide vane adjustment devices, it has the characteristics of small space occupation and high adjustment accuracy, and at the same time avoids the gas leakage problem caused by the arrangement of the guide vane adjustment device.

[0010] The secondary gas compression device includes a second impeller connected to the other end of the rotor. The second impeller cooperates with the second volute to form a third air inlet chamber. The third air inlet chamber is connected to the second exhaust flow channel. The second exhaust flow channel is composed of the second volute flow channel in the second volute and the second bearing seat flow channel in the second bearing seat that cooperates with it. The third air inlet chamber is connected to the second air inlet chamber, and the second bearing seat cooperates to install the second bearing that is sleeved on the rotor; a second thrust plate that is sleeved on the rotor is provided between the second impeller and the second bearing, and the outer periphery of the second thrust plate is sleeved on the second sealing seat. The second exhaust flow channel is a volute-type flow channel that is connected to the exhaust port inside the shell to avoid gas leakage. The secondary gas compression device performs secondary compression on the gas compressed by the primary gas compression device, further increasing the pressure and temperature of the compressed gas, and discharges it from the exhaust port to the condenser of the chiller. A third sensor is arranged on one side of the exhaust port to detect the exhaust temperature and pressure of the centrifugal compressor.

[0011] The side of the second air shell is provided with a second air inlet connected to the second air inlet cavity, which is mainly used to inhale the flash gas from the economizer of the chiller through the second air inlet (which can be used for interstage extraction in special cases to meet specific working conditions) and further improve the COP performance of the chiller by using the jet enthalpy increase technology. The setting of the second air inlet cavity effectively reduces the gas velocity from the interstage flow channel and the second air inlet, so that the gas between the two is fully mixed. Even if the gas at the second air inlet contains a certain amount of droplets, the droplets are mixed with the superheated gas from the interstage flow channel and evaporated instantly, preventing the suction of the secondary gas compression device from carrying liquid, thereby improving the reliability of the operation of the centrifugal compressor.

[0012] The shell is provided with a junction box on the outside of the stator, and the junction box is installed with a second terminal for detecting the temperature of the stator and its electromagnetic coil. The first terminal is arranged on one side of the second terminal, and the second sensor is arranged on the other side. The first terminal is used to connect to the three-phase power supply of the stator, and the second sensor is used to detect the temperature and pressure in the first cooling cavity. The signals collected by the second terminal and the second sensor are used as signal sources for stator cooling control.

[0013] The side of the shell is connected to the air supply system of the first bearing and the second bearing through the first pipe joint. The air supply system includes a first air supply pipeline connected to the first pipe joint, the first air supply pipeline is respectively connected to the second air supply pipeline arranged on the second bearing seat and the third air supply pipeline of the first bearing seat, the second air supply pipeline is connected to the second bearing and the second air gap between the rotor and the second thrust plate, so that the rotor is suspended relative to the second bearing, and the third air supply pipeline is connected to the first bearing and the first air gap between the rotor and the first thrust plate, so that the rotor is suspended relative to the first bearing. The air supply system of the utility model adopts the first pipe joint to connect the condenser or evaporator of the chiller through the external air supply device. The main function of the air supply system is to provide lubricating gas of a certain pressure to the first bearing and the second bearing, ensure the formation of a stable air film in the first air gap and the second air gap, fully lubricate the air-floating bearing, so that the rotor is normally suspended on the bearing, thereby realizing the high-speed operation of the centrifugal compressor. The bearing uses refrigerant gas (also suitable for liquid or gas-liquid two-phase state) as a lubricant, so that the chiller can run without oil, which is beneficial to improve the COP energy efficiency of the chiller. It should be emphasized that the first bearing and the second bearing in the present invention are both static pressure air bearings (dynamic pressure air bearings and dynamic and static pressure air bearings are also applicable). In addition to being used in chillers, the bearings and their air supply systems can also be used in heat pump units, waste heat recovery units and ORC turbine expansion units, etc.

[0014] The side of the shell is connected to the cooling system through the second pipe joint and the third pipe joint. The cooling system includes a first cooling channel connected by the second pipe joint. The first cooling channel is connected to the first cooling cavity and the second cooling cavity respectively. The first cooling cavity is formed by the shell, the stator, the rotor, the first bearing, and the first bearing seat surrounding each other. The first cooling cavity is connected to the first cooling channel through the second cooling channel and the spiral channel arranged on the outer periphery of the stator. The first cooling cavity is connected to the third pipe joint through the third cooling channel; the second cooling cavity is formed by the shell, the stator, the second bearing, and the second bearing seat surrounding each other. The first cooling cavity and the second cooling cavity are connected through the third air gap between the rotor and the stator, ensuring that the pressure and temperature of the gas in the two cooling cavities are equalized. The second pipe joint and the third pipe joint are connected to the condenser and the evaporator of the chiller respectively. The refrigerant liquid from the condenser is connected to the cooling system through the second pipe joint, and the cooling and temperature reduction treatment of the rotor and the stator is formed through the first cooling cavity and the second cooling cavity. The cooled refrigerant gas enters the evaporator through the third pipe joint to form a cycle.

[0015] The first cooling chamber is connected to the first exhaust channel via a first axial air hole provided in the first bearing seat; the second cooling chamber is connected to the second exhaust channel via a second axial air hole provided in the second bearing seat, and the gas in the exhaust channel enters the cooling chamber through the axial air hole after being throttled by the sealing seat, and the axial air hole also takes into account the exhaust function of the bearing.

[0016] The shell has a first mounting seat and a second mounting seat at both axial ends, respectively; the first mounting seat has an inner wall for mounting the first bearing seat and the first volute, and is provided with an air intake port for connecting the interstage flow channel of the first exhaust flow channel; the air intake port is located inside the shell as a whole and is connected to the first exhaust flow channel, and air leakage is usually not a concern.

[0017] The inner wall of the second mounting seat cooperates with the mounting of the second bearing seat and the second volute, and is provided with an exhaust port connected to the interstage flow channel of the second exhaust flow channel. The exhaust port is also located inside the shell and is connected to the second air inlet cavity. Usually, there is no need to consider the problem of air leakage. The second exhaust flow channel is connected to the exhaust port on the inner wall of the second mounting seat, and there is no need to consider the problem of air leakage at the connection part. The first-stage gas compression device and the second-stage gas compression device are completely wrapped in the shell, so that the inside of the shell can withstand higher gas pressure, while improving the centering of the assembly of parts and solving the problem of internal gas leakage.

[0018] By adopting the above-mentioned technical solution, the centrifugal compressor with a built-in interstage flow channel device connects the first-stage gas compression device and the second-stage gas compression device in series, thereby solving a series of problems caused by external connecting pipelines, avoiding gas leakage, and improving the overall performance of the centrifugal compressor. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0020] FIG1 is a cross-sectional structural schematic diagram of a centrifugal compressor with a built-in interstage flow channel device according to the present invention;

[0021] FIG2 is a schematic diagram of the three-dimensional structure of the centrifugal compressor in the utility model;

[0022] FIG3 is a schematic diagram of the three-dimensional structure of a centrifugal compressor from another angle in the present invention;

[0023] Figure 4 is a schematic cross-sectional view of the utility model gas supply system;

[0024] FIG5 is a schematic cross-sectional view of the cooling system in the present invention;

[0025] FIG6 is a schematic diagram of the three-dimensional structure of the housing in the present invention;

[0026] FIG7 is a schematic diagram of the three-dimensional structure of the housing of the present invention from another angle;

[0027] FIG8 is a schematic diagram of the installation structure of the first volute and the first bearing seat in the utility model;

[0028] FIG. 9 is a schematic diagram of the installation structure of the second volute and the second bearing seat in the utility model. DETAILED DESCRIPTION

[0029] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the protection scope of the present invention.

[0030] like Figure 1-9As shown, a centrifugal compressor with a built-in interstage flow channel device includes a shell 1, a stator 2 with an electromagnetic coil and a rotor 18 built in the shell 1, a primary gas compression device and a secondary gas compression device are respectively provided at both ends of the shell 1, the gas compressed by the primary gas compression device is connected to the secondary gas compression device through the interstage flow channel 101 built in the shell, the interstage flow channel 101 and the shell 1 are an integral structure, and valves 25 and a fourth sensor 34 are arranged on both sides, and the axial ends of the interstage flow channel 101 are respectively used to install the primary gas compression device and the secondary gas compression device, so that the exhaust of the primary gas compression device and the intake of the secondary gas compression device are respectively connected to the interstage flow channel 101 in the shell, avoiding the problem of interface leakage. The interstage flow channel 101 is provided with an exhaust port 109 to cooperate with the secondary gas compression device and the second gas shell 12 to form a second air intake chamber 122, and the gas in the second air intake chamber 122 passes through the secondary gas compression device to form high-pressure and high-temperature gas and is discharged through the exhaust port 112, and the third sensor 26 is arranged outside the exhaust port 112, and is connected to the condenser of the chiller. The gas passes through the first-stage gas compression device, the inter-stage flow channel 101, and the second-stage gas compression device, and finally realizes a centrifugal compressor with almost zero gas leakage.

[0031] As a preferred structure, the first-stage gas compression device includes a first impeller 15 connected to one end of the rotor 18. The first impeller 15 cooperates with the first volute 9 to form a first air inlet chamber 91. The first air inlet chamber 91 is connected to the first exhaust flow channel 7. The first exhaust flow channel 7 is composed of the first volute flow channel 92 in the first volute 9 and the first bearing seat flow channel 322 in the first bearing seat 3 matched therewith. The first exhaust flow channel 7 is connected to the interstage flow channel 101 to form an internal connection of the compressed gas. The first bearing seat 3 cooperates to install the first bearing 17 sleeved with the rotor. A first thrust plate 35 sleeved with the rotor 18 is provided between the first impeller 15 and the first bearing 17. The outer periphery of the first thrust plate 35 is sleeved with the first sealing seat 5. The first sealing seat 5 seals the gas of the first-stage gas compression device to reduce gas leakage into the first cooling chamber 33.

[0032] In order to control the air intake amount of the first air intake cavity 91, a first air shell 11 sealed and connected to the housing 1 is provided outside the first air intake cavity 91, and a guide vane adjustment device 14 for controlling the air intake amount is installed inside the first air shell 11. The guide vane adjustment device 14 is connected to the control system of the chiller through a terminal block 117 installed outside the first air shell 11. The guide vane adjustment device 14 is connected to the first air intake port 20 in the first air shell 11, and the guide vane rotation opening in the guide vane adjustment device 14 is comprehensively adjusted according to the working condition of the chiller and the performance of the centrifugal compressor. The first air intake port 20 is connected to the evaporator of the chiller, and a first sensor 13 is arranged outside.

[0033] As a preferred structure, the two-stage gas compression device includes a second impeller 16 connected to the other end of the rotor 18, the second impeller 16 cooperates with the second volute 10 to form a third air inlet chamber 100, the third air inlet chamber 100 is connected to the second exhaust flow channel 8, the second exhaust flow channel 8 is composed of the second volute flow channel 110 in the second volute 10 and the second bearing seat flow channel 41 in the second bearing seat 4 cooperated therewith, the third air inlet chamber 100 is connected to the second air inlet chamber 122, the second bearing seat 4 cooperates to install the second bearing 19 sleeved with the rotor; a second thrust plate 38 sleeved with the rotor 18 is provided between the second impeller 16 and the second bearing 19, the outer periphery of the second thrust plate 38 is sleeved with the second sealing seat 6, and the second sealing seat 6 seals the gas of the two-stage gas compression device to reduce gas leakage into the second cooling chamber 30. A second air inlet 121 connected to the second air inlet chamber 122 is provided on the side of the second air shell 12, and the second air inlet 121 is connected to the economizer of the chiller.

[0034] The housing 1 is provided with a junction box 21 on the outside of the stator 2. The junction box 21 is installed with a second terminal 23 for detecting the temperature of the stator 2 and its electromagnetic coil. The second terminal 23 is provided with a first terminal 24 on one side and a second sensor 22 on the other side. The side of the housing 1 is connected to the air supply system of the first bearing 17 and the second bearing 19 through the first pipe joint 29. The air supply system includes a first air supply pipeline 36 connected with the first pipe joint 29. The first air supply pipeline 36 is respectively connected with a second air supply pipeline 43 provided on the second bearing seat 4 and a third air supply pipeline 37 of the first bearing seat 3. The second air supply pipeline 43 is connected with the second air gap 40 between the second bearing 19 and the rotor 18 and the second thrust plate 38, so that the rotor 18 is suspended relative to the second bearing 19. The third air supply pipeline 37 is connected with the first bearing 17 and the first air gap 39 between the rotor 18 and the first thrust plate 35, so that the rotor 18 is suspended relative to the first bearing 17.

[0035] In order to further improve the temperature control performance of the stator and rotor inside the shell, the side of the shell 1 is connected to the cooling system through the second pipe joint 27 and the third pipe joint 28. The cooling system includes a first cooling channel 105 connected to the second pipe joint 27. The first cooling channel 105 is connected to the first cooling cavity 33 and the second cooling cavity 30 respectively. The first cooling cavity 33 is formed by the shell 1, the stator 2, the rotor 18, the first bearing 17, and the first bearing seat 3 surrounding each other. The first cooling cavity 33 is connected to the first cooling channel 105 through the second cooling channel 107 and the spiral channel 106 arranged on the outer periphery of the stator. A certain number of second nozzles 130 are arranged circumferentially in the first cooling channel 105, and a certain number of first nozzles 131 are arranged circumferentially in the second cooling channel 107. The first cooling cavity 33 is connected to the first cooling channel 105 through the third cooling channel 108. The third pipe joint 28 is connected; the second cooling chamber 30 is formed by the housing 1, the stator 2, the rotor 18, the second bearing 19, and the second bearing seat 4 surrounding each other, and the first cooling chamber 33 is connected to the second cooling chamber 30 through the third air gap 32 between the rotor and the stator. The arrangement of the first nozzle 131 and the second nozzle 130 plays a spraying and atomizing role on the refrigerant liquid, so that the entire stator and rotor are cooled evenly without causing a large temperature gradient. The setting of the spiral flow channel 106 helps to enhance heat exchange and improve the cooling effect of the stator. The second pipe joint 27 and the third pipe joint 28 are respectively connected to the condenser and evaporator of the chiller.

[0036] As a preferred structure, the first cooling chamber 33 is connected to the first exhaust flow channel 7 through a first axial air hole 31 provided in the first bearing seat 3; the second cooling chamber 30 is connected to the second exhaust flow channel 8 through a second axial air hole 42 provided in the second bearing seat 4.

[0037] As a preferred mounting structure, the housing 1 is provided with a first mounting seat 115 and a second mounting seat 116 at both axial ends respectively. The inner wall of the first mounting seat 115 cooperates with the mounting of the first bearing seat 3 and the first volute 9, and is provided with an air inlet port 114 of the interstage flow channel 101 connected to the first exhaust flow channel 7; the inner wall of the second mounting seat 116 cooperates with the mounting of the second bearing seat 4 and the second volute 10, and is provided with an exhaust port 109 and an exhaust port 112 of the interstage flow channel 101 connected to the second exhaust flow channel 8, thereby realizing the leakage-free function of gas entering and exiting the interstage flow channel 101.

[0038] Although the embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and cannot be understood as limiting the present invention. Those skilled in the art can change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and purpose of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A centrifugal compressor with a built-in interstage flow channel device, comprising a housing (1), a stator (2) with an electromagnetic coil wound thereon and a rotor (18) built therein, a first-stage gas compression device and a second-stage gas compression device being respectively provided at two ends of the housing (1), characterized in that: The gas compressed by the first-stage gas compression device is connected to the second-stage gas compression device through an interstage flow channel (101) built into the shell. The interstage flow channel (101) and the shell (1) are an integral structure. A valve component (25) and a fourth sensor (34) are arranged on both sides of the interstage flow channel (101). The axial ends of the interstage flow channel (101) are used to install the first-stage gas compression device and the second-stage gas compression device respectively. The interstage flow channel (101) is provided with an exhaust port (109) to cooperate with the second-stage gas compression device and the second gas shell (12) to form a second air inlet chamber (122).

2. A centrifugal compressor with a built-in interstage flow channel device according to claim 1, characterized in that: The first-stage gas compression device comprises a first impeller (15) connected to one end of a rotor (18), the first impeller (15) cooperates with a first volute (9) to form a first air inlet chamber (91), the first air inlet chamber (91) is connected to a first exhaust flow channel (7), the first exhaust flow channel (7) is composed of a first volute flow channel (92) in the first volute (9) and a first bearing seat flow channel (322) in a first bearing seat (3) cooperated therewith, the first exhaust flow channel (7) is connected to an inter-stage flow channel (101), and the first bearing seat (3) cooperates to install a first bearing (17) sleeved with the rotor; a first thrust plate (35) sleeved with the rotor (18) is provided between the first impeller (15) and the first bearing (17), the outer periphery of the first thrust plate (35) sleeved with the first sealing seat (5).

3. A centrifugal compressor with a built-in interstage flow channel device according to claim 2, characterized in that: A first air shell (11) sealed and connected to the housing (1) is provided outside the first air intake cavity (91); a guide vane adjustment device (14) for controlling the air intake amount is installed inside the first air shell (11); the guide vane adjustment device (14) is connected to the control system of the chiller via a terminal block (117) installed outside the first air shell (11); the guide vane adjustment device (14) is connected to a first air intake port (20) inside the first air shell (11); the rotational opening of the guide vane adjustment device (14) is comprehensively adjusted according to the operating conditions of the chiller and the performance of the centrifugal compressor; the first air intake port (20) is connected to an evaporator of the chiller, and a first sensor (13) is arranged outside.

4. A centrifugal compressor with a built-in interstage flow channel device according to claim 1, characterized in that: The two-stage gas compression device comprises a second impeller (16) connected to the other end of the rotor (18); the second impeller (16) cooperates with the second volute (10) to form a third air inlet chamber (100); the third air inlet chamber (100) is connected to a second exhaust flow channel (8); the second exhaust flow channel (8) is composed of a second volute flow channel (110) in the second volute (10) and a second bearing seat flow channel (41) in a second bearing seat (4) cooperated therewith; the third air inlet chamber (100) is connected to the second air inlet chamber (122); the second bearing seat (4) cooperates with a second bearing (19) sleeved on the rotor; a second thrust plate (38) sleeved on the rotor (18) is provided between the second impeller (16) and the second bearing (19); the outer periphery of the second thrust plate (38) is sleeved on the second sealing seat (6).

5. The centrifugal compressor with a built-in interstage flow channel device according to claim 1, characterized in that: A second air inlet (121) communicating with the second air inlet cavity (122) is provided on the side of the second air shell (12), and the second air inlet (121) is connected to the economizer of the chiller.

6. A centrifugal compressor with a built-in interstage flow channel device according to claim 1, characterized in that: The housing (1) is provided with a junction box (21) outside the stator (2); the junction box (21) is installed with a second junction head (23) for detecting the temperature of the stator (2) and its electromagnetic coil, and the second junction head (23) is provided with a first junction head (24) on one side and a second sensor (22) on the other side.

7. The centrifugal compressor with a built-in interstage flow channel device according to claim 1, characterized in that: The side surface of the housing (1) is connected to an air supply system of the first bearing (17) and the second bearing (19) via a first pipe joint (29), the air supply system comprising a first air supply pipeline (36) connected to the first pipe joint (29), the first air supply pipeline (36) respectively connected to a second air supply pipeline (43) provided on the second bearing seat (4) and a third air supply pipeline (37) of the first bearing seat (3), the second air supply pipeline (43) connected to the second bearing (19) and a second air gap (40) between the rotor (18) and the second thrust plate (38), so that the rotor (18) is suspended relative to the second bearing (19), the third air supply pipeline (37) connected to the first bearing (17) and a first air gap (39) between the rotor (18) and the first thrust plate (35), so that the rotor (18) is suspended relative to the first bearing (17), and the first pipe joint (29) is connected to a condenser or an evaporator of the chiller via an external air supply device.

8. The centrifugal compressor with a built-in interstage flow channel device according to claim 1, characterized in that: The side of the housing (1) is connected to a cooling system via a second pipe joint (27) and a third pipe joint (28), the cooling system comprising a first cooling channel (105) connected to the second pipe joint (27), the first cooling channel (105) respectively communicating with a first cooling cavity (33) and a second cooling cavity (30), the first cooling cavity (33) being formed by the housing (1), the stator (2), the rotor (18), the first bearing (17), and the first bearing seat (3), the first cooling cavity (33) being surrounded by the second cooling channel (105) disposed on the outer periphery of the stator. 07), the spiral flow channel (106) is connected to the first cooling flow channel (105), and the first cooling chamber (33) is connected to the third pipe joint (28) through the third cooling flow channel (108); the second cooling chamber (30) is formed by the housing (1), the stator (2), the rotor (18), the second bearing (19), and the second bearing seat (4) surrounding each other, and the first cooling chamber (33) and the second cooling chamber (30) are connected through the third air gap (32) between the rotor and the stator; the second pipe joint and the third pipe joint are respectively connected to the condenser and the evaporator of the chiller.

9. A centrifugal compressor with a built-in interstage flow channel device according to claim 8, characterized in that: The first cooling chamber (33) is connected to the first exhaust flow channel (7) via a first axial air hole (31) provided in the first bearing seat (3); and the second cooling chamber (30) is connected to the second exhaust flow channel (8) via a second axial air hole (42) provided in the second bearing seat (4).

10. The centrifugal compressor with a built-in interstage flow channel device according to claim 1, characterized in that: The housing (1) is provided with a first mounting seat (115) and a second mounting seat (116) at two axial ends thereof, respectively; the inner wall of the first mounting seat (115) cooperates with the mounting of the first bearing seat (3) and the first volute (9), and is provided with an air inlet port (114) of the interstage flow passage (101) connected to the first exhaust flow passage (7); the inner wall of the second mounting seat (116) cooperates with the mounting of the second bearing seat (4) and the second volute (10), and is provided with an exhaust port (109) and an exhaust port (112) of the interstage flow passage (101) connected to the second exhaust flow passage (8).

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