Four-stage energy-saving centrifugal air compressor system

Abstract

The invention relates to the technical field of air compressor equipment, and discloses a four-stage energy-saving centrifugal air compressor system which comprises an air-water cooling heat exchanger, a two-stage centrifugal air compressor A, a two-stage centrifugal air compressor B, a two-stage centrifugal air compressor C, an air-air intercooler and a strong heat exchange wind scooper. The four-stage energy-saving centrifugal air compressor system has the advantages that the efficiency is high, the structure is simple, the size is small, gas is not polluted by oil, operation is stable in the working condition state, and compressed airflow is free of pulsation; compared with an existing centrifugal air compressor system, the centrifugal air compressor system has the advantages of being small in flow loss, small in temperature rise, small in noise, small in size, high in integration degree, high in efficiency and capable of saving energy. Compared with a single-stage centrifugal air compressor, the two-stage centrifugal air compressor has the advantages that the high pressure ratio required by the system can be efficiently realized; the compression ratio of each stage can be reduced through two-stage pressurization, internal leakage of each stage is reduced, and the compression efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of air compressor equipment, in particular to a four-stage energy-saving centrifugal air compressor system. BACKGROUND

[0002] Compressed air is often referred to as the fourth type of public facilities, which is a kind of energy consumption in industrial production, and its consumption increases with the growth of industrial production. In China, the energy consumption of air compressor system accounts for about 9.4% of industrial power consumption. The air compressor is the core component of the air compressor system, and its power consumption accounts for more than 90% of the entire compression system, so a high-efficiency energy-saving air compressor system is urgently needed to reduce its energy consumption ratio to achieve the purpose of energy saving and consumption reduction.

[0003] The air compressor system is a kind of pressurization process system that converts the mechanical energy of the prime mover into gas energy. It consumes energy to transport gas working medium and participates in various different and important process flows; it is an important general machine in various departments of the national economy, and its use is very wide, almost covering all major industrial fields such as petroleum, chemical industry, metallurgy, power, national defense, refrigeration, pharmaceuticals, food, machinery, etc. In the chemical industry, the air compressor system is called the "heart" of the production process; in the metallurgical industry, compressed air and oxygen are needed to increase the pressure; in the national defense system, modern weapons also cannot do without compressed air; in the development of industrial automation instruments and biological engineering categories and food manufacturing industry, etc., clean compressed air is urgently needed to provide clean compressed air, etc.

[0004] The air compressor is usually divided into two types: volumetric air compressor and turbine air compressor. The volumetric air compressor system, especially the screw air compressor system, is most widely used, and the rotor of the air compressor is difficult to process and handle, easy to wear and tear, and needs to increase the wear-resistant coating; the internal auxiliary part of the system is large, and for the oil-injected screw air compressor, in order to separate the lubricating oil in the exhaust gas, a large-volume, complex-structure, high-efficiency oil separator and oil return device are needed; due to the reasons such as the periodic high-speed passing of the rotor tooth groove through the suction and exhaust port, and the leakage through the gap, the noise is large, the surrounding environment needs to be treated for sound insulation, and at the same time, it cannot be connected to the operation plant, otherwise it will interfere with the operation personnel. The centrifugal air compressor is a kind of turbine air compressor, which has the characteristics of large exhaust capacity, high efficiency, simple structure, small size, gas not being polluted by oil, and stable operation under various working conditions, and the compressed gas flow is not pulsating. It uses high-speed rotating impeller to do work on gas, so that the pressure of the gas is increased in the centrifugal force field, and the kinetic energy is also greatly increased, and then this part of kinetic energy is converted into static pressure energy when flowing in the expansion flow passage, so that the pressure of the gas is further increased.

[0005] The common centrifugal air compressor system has the advantages of low noise and high efficiency compared with the positive displacement compressor system, but in order to solve the problems of difficult adjustment of air volume, low pressure ratio, high temperature rise, reduce the gas flow loss and energy consumption, the application provides a four-stage energy-saving centrifugal air compressor system. SUMMARY

[0006] (I) Technical problems solved In view of the deficiencies of the prior art, the application provides a four-stage energy-saving centrifugal air compressor system, which has the advantages of small flow loss, small temperature rise, small noise, small volume, high integration, high efficiency and energy saving, and solves the problems of difficult adjustment of air volume, too low pressure ratio, too high temperature rise, large gas flow loss and high energy consumption of the common centrifugal air compressor system.

[0007] (II) Technical solutions In order to achieve the above-mentioned purpose, the application provides the following technical solutions: a four-stage energy-saving centrifugal air compressor, comprising an air-water cooling heat exchanger, a two-stage centrifugal air compressor A, a two-stage centrifugal air compressor B, a two-stage centrifugal air compressor C, an air-air intercooler, and a strong heat exchange wind shield.

[0008] Preferably, the two-stage centrifugal air compressor A comprises a primary air pump A, a permanent magnet motor A, a secondary air pump A, and a one-two connection pipe A, the primary air pump A comprises a gas pre-rotation compensation structure and a primary air compression structure, and the secondary air pump A comprises a gas pre-rotation compensation structure and a secondary air compression structure.

[0009] Preferably, the two-stage centrifugal air compressor B comprises a primary air pump B, a one-two connection pipe B, a secondary air pump, and a foil gas bearing system B.

[0010] Preferably, the two-stage centrifugal air compressor C comprises a primary air pump C, a one-two connection pipe C, a secondary air pump, and a foil gas bearing system C.

[0011] Preferably, the centrifugal air compressor A is provided with a pre-rotation compensation flow channel and a pre-rotation inlet flow channel.

[0012] Preferably, the one-two connection pipe A comprises an inter-stage connection pipe and a micro guide groove.

[0013] Preferably, the working process of the air compressor system is as follows: After the air passes through the filter, the clean air is divided into two branches, and the two branches are in parallel connection, and the two branches are connected in parallel to form a primary compression subsystem, that is, a first stage and a second stage of the four-stage energy-saving centrifugal air compressor system; Step one: the first branch enters the primary air pump A of the two-stage centrifugal air compressor A for compression, then passes through the one-two connection pipe A of the two-stage centrifugal air compressor A, and then enters the secondary air pump A of the two-stage centrifugal air compressor A; Step two: the second branch enters the first-stage compressor pump B of the two-stage centrifugal air compressor B for compression, then passes through the first-stage and second-stage connecting pipe B of the two-stage centrifugal air compressor B, and then enters the second-stage compressor pump B of the two-stage centrifugal air compressor B; Step three: the gas of the two branches is compressed by the two-stage centrifugal air compressor A and the two-stage centrifugal air compressor B respectively, and then is gathered into one branch and cooled by the air-air intercooler, Step four: the gas enters the final compression subsystem of the system, that is, the three-stage and four-stage compression part of the four-stage energy-saving centrifugal air compressor system, is compressed by the first-stage compressor pump C of the two-stage centrifugal air compressor C, then passes through the first-stage and second-stage connecting pipe C of the two-stage centrifugal air compressor C, then enters the second-stage compressor pump C of the two-stage centrifugal air compressor A, and finally is output.

[0014] Compared with the prior art, the four-stage energy-saving centrifugal air compressor system has the following beneficial effects: Compared with the volumetric air compressor system, the four-stage energy-saving centrifugal air compressor system has the advantages of high efficiency, simple structure, small size, no oil pollution of gas, stable operation under working conditions, and no pulsation of compressed gas flow; compared with the existing centrifugal air compressor system, the four-stage energy-saving centrifugal air compressor system has the advantages of small flow loss, small temperature rise, small noise, small size, high integration, high efficiency, and energy saving; compared with the single-stage centrifugal air compressor, the two-stage centrifugal air compressor can efficiently realize the high pressure ratio required by the system; if only single-stage compression is used, a higher single-stage pressure ratio is required, which will make the exhaust temperature too high, resulting in greater compression power consumption; meanwhile, two-stage supercharging can reduce the compression ratio of each stage, reduce the internal leakage of each stage, and improve the compression efficiency; the two stages are symmetrically and oppositely arranged, so that the axial forces are offset, the load of the bearing is greatly reduced, and the service life and reliability of the bearing and the whole machine are improved. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 Fig. 1 is a structural schematic diagram of the air compressor system of the present application; Figure 2 Fig. 2 is a related structural schematic diagram of the two-stage centrifugal air compressor A of the present application; Figure 3 Fig. 3 is a structural schematic diagram of the pre-rotation inlet flow channel of the present application; Figure 4 Fig. 4 is a schematic diagram of the petal-shaped circular arc surface of the present application; Figure 5 Fig. 5 is a schematic diagram of the petal-shaped structure of the volute inlet of the present application; Figure 6 Fig. 6 is a structural schematic diagram of the inter-stage connecting pipe of the present application; Figure 7 Fig. 7 is a sectional schematic diagram of the inter-stage connecting pipe structure of the present application; Figure 8This is a schematic diagram of the foil gas bearing system and related structures of the present invention.

[0016] Among them: 1-Air-water cooled heat exchanger; 2-Two-stage centrifugal air compressor A; 21-First-stage compressor A; 211-Gas pre-swirl compensation structure; 212-First-stage compressor structure; 2111-Pre-swirl compensation flow channel; 2112-Pre-swirl inlet flow channel; 24-Permanent magnet motor A; 23-Second-stage compressor A; 231-Gas pre-swirl compensation structure; 232-Second-stage compressor structure; 22-First-second stage connecting pipe A; 221-Interstage connecting pipe; 222-Micro guide groove; 25-Foil gas bearing system; 3-Two-stage centrifugal air compressor B; 31-First-stage air compressor B; 32-First and second-stage connecting pipe B; 33-Second-stage air compressor B; 34-Permanent magnet motor B 4-Two-stage centrifugal air compressor C; 41-First-stage air compressor C; 42-First and second-stage connecting pipe C; 43-Second-stage air compressor C; 44-Permanent magnet motor C 5-Air-to-air intercooler; 6-High-efficiency heat exchange air guide shroud. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] Please see Figures 1-8 This invention introduces a four-stage energy-saving centrifugal air compressor system, including 1-air-water cooling heat exchanger, 2-two-stage centrifugal air compressor A, 3-two-stage centrifugal air compressor B, 4-two-stage centrifugal air compressor C, 5-air-intercooler, and 6-high-intensity heat exchange air duct.

[0019] Its main body consists of three two-stage centrifugal air compressor core units, namely 2-two-stage centrifugal air compressor A, 3-two-stage centrifugal air compressor B, and 4-two-stage centrifugal air compressor C.

[0020] The core of a two-stage centrifugal air compressor transfers mechanical energy to air through impeller rotation. Air enters the impeller axially, gaining static and kinetic energy, and leaves the impeller radially. It then passes through a diffuser chamber where the kinetic energy is further converted into pressure energy. The air pressure directly affects the output power of the entire system. Taking a two-stage centrifugal air compressor A as an example, the core consists of: 21-first-stage compressor A, 22-first-second-stage connecting pipe A, second-stage compressor A, 24-permanent magnet motor A, and other components as shown below. Figure 2As shown, the main consideration of the core machine using two-stage supercharging is that single-stage compression cannot achieve the high pressure required for efficient operation of the system, in addition, two-stage supercharging has the following advantages: if only single-stage compression is used, a higher single-stage pressure ratio is required, which will make the exhaust temperature too high, resulting in greater compression power consumption, two-stage compression can reduce the single-stage compression ratio, thereby saving compression power and reducing parasitic power consumption, two-stage compression can reduce internal leakage per stage, improve compression efficiency, and when two-stage compression is used, the two stages can be arranged symmetrically and reversely, so that the axial forces cancel each other out, greatly reducing the load on the bearings and improving the life and reliability of the bearings and the entire machine.

[0021] Adopt foil gas dynamic pressure bearing: It is a kind of sliding bearing which uses flexible foil structure, has self-adaptive adjustment function and uses gas dynamic pressure effect to suspend. When the external load changes, the foil bearing structure of the foil gas dynamic pressure bearing can adjust the gas film gap through its own deformation, so that the shaft journal is in a dynamic balance state during rotation to maintain stable operation.

[0022] The lubricating medium of the bearing is air, which can be applied to ultra-high speed, up to tens of thousands of revolutions per minute or even hundreds of thousands of revolutions per minute; It has low friction power consumption, is not easy to wear, has long service life, high stability, can dissipate redundant energy through foil structure friction damping; It is completely oil-free lubrication, has high cleanliness and no pollution; Compact structure, saves space; It has good bearing misalignment adaptability; It can withstand high temperature environment and does not need to supply gas separately.

[0023] The working process of the air compressor system is as follows: After the air passes through the filter, the clean air is divided into two branches, which are in parallel relationship, and the two branches are connected in parallel to form the primary compression subsystem, that is, the first and second compression parts of the four-stage energy-saving centrifugal air compressor system; The first branch (system one, two compression A branch) enters 2-two-stage centrifugal air compressor A 21-first stage air pump A for compression, and then passes through 2-two-stage centrifugal air compressor A 22-one-two connection pipe A, and then enters 2-two-stage centrifugal air compressor A 23-second stage air pump A; The second branch (system one, two compression B branch) enters 3-two-stage centrifugal air compressor B 31-first stage air pump B for compression, and then passes through 3-two-stage centrifugal air compressor B 32-one-two connection pipe B, and then enters 3-two-stage centrifugal air compressor B 33-second stage air pump B; The gas of the two branches is compressed by 2-two-stage centrifugal air compressor A and 3-two-stage centrifugal air compressor B respectively, and then converges into one path, The terminal compression subsystem of the system, namely the three-fourth stage compression part of the fourth stage energy-saving centrifugal air compressor system, is compressed by the 41 -first stage air pump C of the 4-two stage centrifugal air compressor C, enters the 42-second stage connecting pipe C of the 4-two stage centrifugal air compressor C, and is finally output by the 43-second stage air pump C of the 4-two stage centrifugal air compressor A.

[0024] The air path compression part is optimized as follows: After the air passes through the filter, the clean air is divided into two branches. 1. The air in the first branch enters the 21 -first stage air pump A of the 2-two stage centrifugal air compressor A through the pre-rotation compensation flow channel 2111. In this process, the gas vortex area of the gas is controlled, the friction loss of the gas is reduced, and the energy loss of the impeller in the air compression process is reduced. 2. After the air in the first branch is speeded up and pressurized by the impeller, it enters the first compression cross-section flow channel. At this time, the flow channel cross-sectional area increases rapidly, the air is speeded up and pressurized in this process, and the volute itself will cause the gas to produce rotational flow loss. The gas will have a large temperature rise in this process. The 6-strong heat exchange air baffle using the strong heat exchange fins outside the first volute shell, the inter-stage connecting pipe and the second volute shell is used for forced air cooling, so that each stage of compressed gas is effectively cooled, the load of the next stage impeller and the internal power consumption consumed by the next stage of compressed gas are reduced, and the next stage is saved in the case of constant output pressure. The compression work is saved; 3. After the gas is compressed, it enters the 22-second stage connecting pipe A. At this time, the boundary thickness of the gas increases, the boundary layer appears longitudinal vortex and disturbance, especially at the position of the 180-degree bend.

[0025] The detangling flow channel is arranged in the inter-stage connecting pipe, the depth of the micro guide groove is 1.4~1.8 times the thickness of the gas laminar flow bottom layer, which can effectively remove the turbulence and increase the heat exchange area, and assist the strong heat exchange structure formed by the external fins of the connecting pipe.

[0026] 4. After the gas passes through the connecting pipe, it enters the 23-second stage air pump A of the 2-two stage centrifugal air compressor A. At this time, the improvement effect is the same as 1 and 2. After the second branch enters the 31 -first stage air pump B of the 3-two stage centrifugal air compressor B for compression, it passes through the 32-second stage connecting pipe B of the 3-two stage centrifugal air compressor B, and then enters the 33-second stage air pump B of the 3-two stage centrifugal air compressor B. At this time, the improvement effect is the same as 1~4. 5. The two branches of gas are compressed by 2-two-stage centrifugal air compressor A and 3-two-stage centrifugal air compressor B respectively, and then converged into one branch to pass through 5-air air cooler for cooling; 5-air air cooler is combined with 6-strong heat exchange air duct, and air introduced through the strong heat exchange air duct is used as cooling medium to cool the high-temperature air compressed by centrifugal air compressor A and B. 6-strong heat exchange air duct is installed at the edge of the four-stage centrifugal air compressor system frame, and multiple groups can be installed according to actual needs, and the heat source air emitted by 2-two-stage centrifugal air compressor A, 3-two-stage centrifugal air compressor B and 4-two-stage centrifugal air compressor C in the system frame is led out of the system.

[0027] 6. The compressed gas after cooling enters 41-one-stage air compressor C of 4-two-stage centrifugal air compressor C for re-compression, passes through 42-two-stage connecting pipe C of 4-two-stage centrifugal air compressor C, and then enters 43-two-stage air compressor C of 4-two-stage centrifugal air compressor C, and finally is output, at this time, the improvement effect is the same as 1~4.

[0028] 7. Water cooling channels are arranged on the two-stage centrifugal air compressor A, the two-stage centrifugal air compressor B and the two-stage centrifugal air compressor C which are core machines in the four-stage energy-saving centrifugal air compressor system, and cooling of the individual core machines is realized through 1-air water cooling heat exchanger in series.

[0029] After improvement, the whole system is optimized, and the temperature rise, noise and energy consumption in the air compression process are significantly reduced. Advantage 1: The application introduces a four-stage energy-saving centrifugal air compressor system, which has the advantages of high efficiency, simple structure, small size, non-oil pollution of gas, stable operation under working conditions, and non-pulsation of compressed gas flow compared with the volumetric air compressor system; and has the advantages of small flow loss, small temperature rise, small noise, small size, high integration, high efficiency and energy saving compared with the existing centrifugal air compressor system.

[0030] The four-stage energy-saving centrifugal air compressor system comprises a primary compression subsystem and a final compression subsystem, and the two compression subsystems are connected in series. The primary compression subsystem adopts two completely same one-two-stage compression branches in parallel, and the core of each branch is a two-stage centrifugal air compressor; the core of the final compression subsystem is also a two-stage centrifugal air compressor.

[0031] The centrifugal air compressor transmits mechanical energy to air by rotating impeller, air enters the impeller from the axial direction, obtains static pressure energy and kinetic energy, and then exits the impeller from the radial direction, and then the gas kinetic energy is further converted into pressure energy through the diffuser, and the size of air pressure directly affects the output power of the whole system.

[0032] The core machine of the present application adopts two-stage centrifugal air compressor. Taking two-stage centrifugal air compressor A as an example, the core machine is composed of 21-stage air compressor A, 22-two-stage connecting pipe A, 23-two-stage air compressor A, 24-permanent magnet motor A and 25-foil gas bearing system as shown in Figure 2 .

[0033] Compared with single-stage centrifugal air compressor, two-stage centrifugal air compressor can efficiently realize the high pressure ratio required by the system. If only single-stage compression is used, higher single-stage pressure ratio is required, which will make the exhaust temperature too high, resulting in greater compression power consumption. At the same time, two-stage supercharging can reduce the compression ratio of each stage, reduce the internal leakage of each stage, and improve the compression efficiency. The two stages are symmetrically and oppositely arranged, so that the axial forces are offset, greatly reducing the load of the bearing, and improving the life and reliability of the bearing and the whole machine.

[0034] The two-stage centrifugal air compressor of the present application adopts foil gas dynamic pressure bearing. The bearing adopts a flexible foil structure and has self-adaptive adjustment function. It uses gas dynamic pressure effect to make the rotating body suspended. When the external load changes, the foil support structure of the foil gas dynamic pressure bearing can adjust the gas film gap by deforming itself, so that the shaft journal is in a dynamic balance state during rotation to maintain stable operation.

[0035] The lubricating medium of the bearing is air, which can be applied to ultra-high speed, up to tens of thousands of revolutions per minute or even hundreds of thousands of revolutions per minute. It has low friction power consumption, is not easy to wear, has long service life and high stability, can dissipate redundant energy through foil structure friction damping, is completely oil-free lubrication, has high cleanliness and no pollution, has compact structure and saves space, has good bearing misalignment adaptability, is resistant to high temperature environment, and does not need to supply gas separately.

[0036] Advantage 2: The gas pre-rotation compensation flow channel composed of 6-12 petal-shaped curved surfaces is arranged at the inlet of the volute. The gas inlet of the traditional centrifugal compressor is a cylindrical inlet without special design, and the gas changes from axial motion to radial motion. The gas is disturbed before encountering the impeller blades and changes its velocity field, and at the same time is affected by the rotation effect of the impeller. The change of the velocity field is the pre-rotation of the gas, and the direction of the pre-rotation is the direction of the rotation of the impeller. At this time, the gas will no longer enter the impeller in a vertical direction, so that the airflow impacts the blade working surface and forms a vortex zone, both of which will cause energy loss and consume part of the power of the impeller.

[0037] The gas pre-rotation compensation flow channel 2111 composed of 6-12 petal-shaped circular arc curved surfaces is arranged at the inlet of the volute. Taking the first circular arc curved surface as an example, the width dimension L of the center position Q1 of the first circular arc curved surface relative to the center of the volute (the position of the central axis of the air compressor) Q is 0.03-0.1mm, and the height dimension L is 0.005-0.03mm.

[0038] The pre-rotation compensation flow channel 2111 makes the gas pre-rotation compensation optimization processing before encountering the impeller blades, compensates the angle of the gas entering the impeller, reduces the viscous stress caused by the velocity difference on both sides of the pressure and suction sides of the blades, effectively alleviates the impact of the gas flow on the working surface of the blades when the gas flow contacts the impeller, greatly improves the vortex area, reduces the energy loss of the impeller in the compression process, and improves the effective power of the impeller.

[0039] Advantage 3: 45-60 micro-guiding grooves distributed on the circumference are arranged in the inter-stage connecting pipe to form a turbulence-removing flow channel together with the main flow channel of the connecting pipe. The inner cross section of the inter-stage connecting pipe of a common back-to-back two-stage compression centrifugal air compressor is a smooth cylinder, and the inner cross-sectional area is not always constant. The cross-sectional area gradually decreases when it transitions to the next stage, and a 180° turn occurs before connecting the second-stage volute. This results in poor coordination of the velocity field and temperature field at the wall surface, energy loss caused by flow separation during gas flow, and secondary flow loss at the elbow.

[0040] The patent has 45-60 micro-guiding grooves distributed on the circumference arranged in the inter-stage connecting pipe to form a turbulence-removing flow channel together with the main flow channel of the connecting pipe. The groove depth D is 0.1-0.3 mm, which is 1.4-1.8 times the thickness of the gas laminar bottom layer (the fluid boundary layer thickness is an important factor affecting convective heat transfer, and the boundary layer thickness refers to the height along the normal direction of the wall surface from the solid inner wall surface to the position where the tangential velocity of the gas along the wall surface reaches 99% of the incoming flow velocity). The fillet R1 is 0.05-0.15 mm, and the fillet R2 is 0.05-0.15 mm. The path is a conical spiral in the straight pipe part and a spatially curved conical spiral in the elbow part. The pitch is 150-300 mm, the initial spiral angle α is 10-30°, and the initial groove spacing is 0.3-0.8 mm.

[0041] The turbulence-removing flow channel can effectively improve the poor coordination of the velocity field and temperature field at the wall surface. The groove depth D of 0.1-0.3 mm (1.4-1.8 times the thickness of the gas laminar bottom layer) improves the flow resistance. At the same time, the heat transfer area is increased to assist the formation of a strong heat transfer structure by the external fins of the connecting pipe for heat dissipation enhancement. Compared with the smooth inner wall of the elbow, the coordination of the velocity field and temperature field at the wall surface is improved, thereby effectively improving the efficiency of the super-high-speed electric air compressor.

[0042] Advantage 4: The first volute shell exterior, inter-stage connecting pipe exterior and second volute shell exterior are provided with strong heat exchange fins, and are placed in front of the 5-air-to-air intercooler through the 6-strong heat exchange air guide cover which is closely fitted with the volute and strong heat exchange fins, to form a special airflow channel for strong heat exchange of the volute shell, inter-stage connecting pipe and secondary heat exchange of the motor shell, and then input to the two-stage output gas cooling intercooler, to cool the two-stage output gas while forcibly air cooling the shell assemblies on the three sets of air compressor shells; The strong heat exchange of the volute shell exterior fins in cooperation with the 6-strong heat exchange air guide cover can effectively reduce the temperature rise caused by gas compression, and at the same time reduce the backflow process in the impeller outlet blade tip clearance area, so that the impeller efficiency can be further improved.

[0043] Although embodiments of the present application have been shown and described, it is to be understood that various modifications, substitutions, replacements and changes can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A four-stage energy-saving centrifugal air compressor, comprising an air-water cooling heat exchanger (1), a two-stage centrifugal air compressor A (2), a two-stage centrifugal air compressor B (3), a two-stage centrifugal air compressor C (4), an air-air intercooler (5), and a strong heat exchange guide cover (6).

2. A four-stage energy-efficient centrifugal air compressor as claimed in claim 1, wherein: The two-stage centrifugal air compressor A (2) comprises a first-stage air pump A (21), a two-stage connecting pipe A (22), a second-stage air pump A (23), a permanent magnet motor A (24), and a foil gas bearing system A (25), wherein the first-stage air pump A (21) comprises a gas pre-rotation compensation structure (211) and a first-stage air compression structure (212), and the second-stage air pump A (23) comprises a gas pre-rotation compensation structure (231) and a second-stage air compression structure (232).

3. A four-stage energy-efficient centrifugal air compressor as claimed in claim 1, wherein: The two-stage centrifugal air compressor B (3) comprises a first-stage air pump B (31), a two-stage connecting pipe B (32), a second-stage air pump B (33), a permanent magnet motor B (34), and a foil gas bearing system B.

4. A four-stage energy-efficient centrifugal air compressor as claimed in claim 1, wherein: The two-stage centrifugal air compressor C (4) comprises a first-stage air pump C (41), a two-stage connecting pipe C (42), a second-stage air pump C (43), a permanent magnet motor C (44), and a foil gas bearing system C.

5. A four-stage energy-efficient centrifugal air compressor as claimed in claim 1, wherein: The centrifugal air compressor A (2) is provided with a pre-rotation compensation flow channel (2111) and a pre-rotation inlet flow channel (2112), and the centrifugal air compressor B (3) and the centrifugal air compressor C (4) are provided with pre-rotation compensation flow channels and pre-rotation inlet flow channels.

6. A four-stage energy-efficient centrifugal air compressor as claimed in claims 2 and 4, wherein: The two-stage connecting pipe A (22) comprises an inter-stage connecting pipe (221) and a micro guide groove (222), and the two-stage connecting pipe B (32) and the two-stage connecting pipe C (42) also comprise inter-stage connecting pipes and micro guide grooves.

7. A system applied to the four-stage energy-saving centrifugal air compressor of claims 1-6, characterized in that: The working process of the air compressor system is as follows: After passing through the filter, the clean air is divided into two branches, which are in parallel relationship, and the two branches are connected in parallel to form an initial compression subsystem, which is the first-stage and second-stage compression part of the four-stage energy-saving centrifugal air compressor system. Step one: the first branch enters the first-stage air pump A (21) of the two-stage centrifugal air compressor A (2) for compression, then passes through the two-stage connecting pipe A (22) of the two-stage centrifugal air compressor A (2), and then enters the second-stage air pump A (23) of the two-stage centrifugal air compressor A (2). Step two: the second branch enters the first-stage air pump B (31) of the two-stage centrifugal air compressor B (3) for compression, then passes through the two-stage connecting pipe B (32) of the two-stage centrifugal air compressor B (3), and then enters the second-stage air pump B (33) of the two-stage centrifugal air compressor B (3). Step three: the gas of the two branches is respectively compressed by the two-stage centrifugal air compressor A (2) and the two-stage centrifugal air compressor B (3), and then converges into one branch, which is cooled by the air-air intercooler (5), and then Step four: into the final compression subsystem of the system, that is, the three-fourth stage compression part of the four-stage energy-saving centrifugal air compressor system, after compression by the first-stage air compressor C (41) of the two-stage centrifugal air compressor C (4), through the one-two stage connecting pipe C (42) of the two-stage centrifugal air compressor C (4), and then into the second-stage air compressor C (43) of the two-stage centrifugal air compressor A (4), and finally output.

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