Centrifugal compressor with low compression ratio

Abstract

The utility model discloses a low-compression-ratio centrifugal compressor, and belongs to the technical field of refrigeration compressor equipment. The high-speed motor comprises a centrifugal volute body, a centrifugal impeller, a high-speed motor shell and a high-speed motor stator and rotor assembly. The two ends of the high-speed motor stator and rotor assembly are supported and installed in the high-speed motor shell through high-speed bearings respectively, one end of the high-speed motor shell is connected with one end of the centrifugal volute shell, a rotor shaft of the high-speed motor stator and rotor assembly extends into an inner cavity of the centrifugal volute shell, and the centrifugal impeller is installed on the extending portion of the rotor shaft. By adopting the low-compression-ratio design concept and utilizing the advantages of large air suction amount and high efficiency of the low-compression-ratio centrifugal compressor under low-temperature and low-pressure working conditions, the low-compression-ratio centrifugal compressor is mainly applied to a refrigerating system with double compressors connected in series and matched with a screw-type compressor, so that the efficiency of the whole refrigerating system is effectively improved; and meanwhile, the defects of poor air suction capacity and over-high exhaust temperature of the first-stage compressor caused by a double-compressor series-connection matching mode of other traditional compressors can be effectively avoided, and the conditions of overheating or overload of a motor of the second-stage compressor and non-ideal efficiency of the whole system are further avoided.

Description

TECHNICAL FIELD

[0001] The utility model belongs to refrigeration compressor equipment technical field, especially related to a low compression ratio centrifugal compressor. BACKGROUND

[0002] Traditional refrigeration compressor usually pursues high compression ratio, so as to improve the refrigeration or heating efficiency of the compressor, but this will inevitably cause the compatibility of the compressor in the low temperature or low pressure working section, thereby affecting the air suction capacity of the inlet of the compressor, and further affecting the working efficiency of the compressor under low temperature or low pressure working condition;The traditional refrigeration compressor has the disadvantages of poor stability and low efficiency in the double compressor series connection system due to high compression force. INVENTION CONTENTS

[0003] In view of the problems existing in the above background technology, the utility model provides a low compression ratio centrifugal compressor, which reduces the compression ratio of the compressor to improve the efficiency of the compressor under low temperature or low pressure working condition, and the low compression ratio centrifugal compressor is mainly used in the double compressor series connection system as a primary compressor to provide a stable medium pressure gas source for the secondary compressor, solve the stability and efficiency problems of the secondary compressor, and improve the overall efficiency.

[0004] Therefore, the utility model adopts the following technical scheme: a low compression ratio centrifugal compressor, comprising a centrifugal scroll body, a centrifugal impeller, a high-speed motor shell and a high-speed motor stator-rotor assembly;

[0005] The two ends of the high-speed motor stator-rotor assembly are respectively supported and installed in the interior of the high-speed motor shell through high-speed bearings, one end of the high-speed motor shell is connected with one end of the centrifugal scroll body, the rotor shaft of the high-speed motor stator-rotor assembly extends into the inner cavity of the centrifugal scroll body, and the centrifugal impeller is fixedly installed on the extension part of the rotor shaft.

[0006] The high-speed motor shell is provided with a motor wiring joint, a refrigerant inlet interface, a liquid collecting groove, a gas-liquid outlet interface and a refrigeration oil inlet interface, an external power supply line is connected to the high-speed motor through the motor wiring joint to provide power supply;The refrigerant inlet interface is opened in the upper part of the high-speed motor shell, and the medium pressure gaseous refrigerant is provided by the pressure difference in the medium pressure section of the refrigeration system to cool the motor, the liquid collecting groove is arranged at the bottom of the high-speed motor shell, and the refrigeration oil inlet interface is arranged on the high-speed motor shell and close to the high-speed bearing.

[0007] The low compression ratio centrifugal compressor includes a motor cooling system and a lubricating system, the motor cooling system is connected to a motor cooling return hole at a suction port of the centrifugal compressor through an external pipeline refrigerant from a high pressure section of a refrigeration system, the refrigerant enters a high speed motor shell to cool the motor and then is heated, the further refrigerant is discharged through a gas-liquid outlet interface at the bottom of a liquid collecting tank and connected to the low pressure section refrigerant before an inlet of the centrifugal scroll shell through an external pipeline, the heated refrigerant preheats the low temperature and low pressure refrigerant of the low pressure section, promotes the expansion and pressure increase of the low temperature and low pressure refrigerant, the process increases the suction capacity of the low compression ratio centrifugal compressor, and further improves the efficiency of the whole system.

[0008] The utility model can achieve the following beneficial effects: 1, the utility model discloses a high speed motor stator rotor assembly, high speed bearing is installed in the motor shell, the high speed motor stator rotor assembly front end extension axle is connected with centrifugal impeller and provides high speed rotation power for centrifugal impeller, centrifugal impeller and centrifugal scroll shell form aerodynamic cooperation, utilize the advantage of low compression ratio centrifugal compressor under low temperature, low pressure working condition, effectively promote the efficiency of whole refrigeration system under the condition of screw compressor in double compressor series connection, can also effectively avoid the defects, such as poor suction capacity of primary compressor, too high exhaust temperature of other traditional compressor double machine, further cause the situation, such as overheating or overload of secondary compressor motor and the situation of unsatisfactory system efficiency.

[0009] 2, the utility model solves the problem of low efficiency of traditional single system compressor under low temperature or low pressure working condition, avoids the problem of low efficiency and low suction capacity of primary compressor of traditional double compressor refrigeration system and the problem of low running stability of secondary compressor caused by high outlet pressure and high temperature of primary compressor, and the oil circuit system of the compressor is directly supplied by secondary compressor, and the lubricated refrigerant returns to the refrigeration system, which also solves the lubrication problem of primary compressor and the difficulty of balancing the refrigeration oil level of double compressor. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 It is a three-dimensional structure schematic diagram of the utility model.

[0011] Figure 2 It is the front structure schematic view of the utility model.

[0012] Figure 3 It is the side structure schematic view of the utility model.

[0013] Figure 4 It is Figure 3 It is the section structure schematic view at A-A. DETAILED DESCRIPTION

[0014] The specific embodiments of the utility model are described in detail in combination with the drawings, and the described embodiments are only for the description and explanation of the utility model, and do not constitute the unique limitation of the utility model.

[0015] As Figures 1-4 Indicated, the utility model passes through centrifugal scroll casing 1 and centrifugal impeller 3 and forms low compression ratio centrifugal turbine pneumatic assembly;Pass through high-speed motor shell 2, high-speed motor stator rotor assembly 6, high-speed bearing 7 and motor wiring 8, refrigerant inlet interface 9, liquid collecting tank 10, gas-liquid outlet interface 11, frozen oil inlet interface 12 and form motor power assembly;Again by low compression ratio centrifugal turbine pneumatic assembly and motor power assembly combination is a kind of low compression ratio centrifugal compressor unit.

[0016] High-speed motor stator rotor assembly two ends each one high-speed bearing is installed in high-speed motor shell interior, and one end of high-speed motor shell is connected with one end of low compression ratio centrifugal scroll casing, and further installs low compression ratio centrifugal impeller on the top of the rotor shaft 8 of 6 high-speed motor stator rotor assembly extension;So as to form a kind of low compression ratio centrifugal compressor power system.

[0017] Refrigerant enters into centrifugal compressor turbine interior from low pressure end through centrifugal scroll casing air inlet 4, and further enters the low compression ratio turbine pneumatic cooperation by centrifugal scroll casing 1 and centrifugal impeller 3 and carries out compression;The medium-pressure gaseous refrigerant after compression is further transported out by centrifugal scroll casing exhaust port 5 and enters next link.The low compression ratio centrifugal compressor is mainly applied to double-compressor series refrigeration system, and the low compression ratio centrifugal compressor provides stable medium-temperature medium-pressure gaseous refrigerant for refrigeration system main compressor (or called secondary compressor) by above process after low pressure or low temperature is raised in temperature and pressure.

[0018] The high-speed motor shell is further provided with a motor junction, a refrigerant inlet interface, a liquid collecting groove, a gas-liquid outlet interface and a refrigeration oil inlet interface. The external power supply line is connected to the high-speed motor through the motor junction 8 to provide power supply for the high-speed motor; the refrigerant inlet interface is arranged at the upper portion of the high-speed motor shell 2, and the medium-pressure gaseous refrigerant is provided by the differential pressure of the medium-pressure section of the refrigeration system to cool the motor to form a lubrication system; the refrigerant is heated after cooling the motor in the high-speed motor shell 2; the further refrigerant is discharged through the gas-liquid outlet interface 11 at the bottom of the liquid collecting groove 10 and connected to the low-pressure section refrigerant in front of the centrifugal scroll shell gas inlet 4 through an external pipeline, and the heated refrigerant preheats the low-temperature and low-pressure refrigerant, promotes the expansion and pressurization of the low-temperature and low-pressure refrigerant, the process increases the suction capacity of the low-pressure ratio centrifugal compressor, and further improves the efficiency of the whole system, and the refrigeration oil inlet interface 12 is arranged at the high-speed bearing 7 of the high-speed motor shell 2, and the high-pressure refrigeration oil is provided by the oil circuit system of the main compressor (two-stage compressor) of the refrigeration system and connected to the refrigeration oil inlet interface 12 through an external pipeline, and then enters the high-speed motor shell 2 and sprays and lubricates the bearing, and then the refrigeration oil flows into the liquid collecting groove 10 arranged at the bottom of the high-speed motor shell 2, and returns to the low-pressure section of the refrigeration system through the gas-liquid outlet interface 11 together with the refrigerant.

[0019] The above process forms a pneumatic system, a power system, a motor cooling and high-speed bearing lubrication system, and realizes a complete low-compression-ratio centrifugal compressor.

[0020] The utility model adopts single-stage low compression ratio working condition design, and the compression ratio of the compressor group is generally between 1:1.2 and 1:1.8 according to different working condition requirements, and the highest compression ratio is not more than 1:2.5; the traditional centrifugal compressor usually reaches more than 1:3; taking R22 refrigerant as an example, the low compression ratio centrifugal compressor outlet absolute pressure is generally controlled at 2Bar to 4Bar, and the highest will not exceed 5Bar, which is much lower than the traditional centrifugal compressor; the above technical scheme expands the compressor performance of the low compression ratio centrifugal compressor under low pressure or low temperature working condition, so that higher efficiency is realized under low pressure or low temperature working condition, and the defects of low displacement caused by poor suction capacity of the primary compressor, double high outlet temperature and pressure causing unstable secondary work and the like in the traditional double compressor series matching mode are solved. The low compression ratio centrifugal compressor can be better used in the low-temperature or low-pressure refrigeration system of the double-compressor matching mode.

[0021] Compared with the traditional centrifugal compressor, the low compression ratio centrifugal compressor gives up the pursuit of high compression ratio to improve performance, and reverses it by reducing the aerodynamic compression ratio of the centrifugal compressor, controlling the compression ratio at a lower level, thereby specializing in the supercharging work of the main compressor (or secondary compressor); and improving the efficiency of the main compressor (or secondary compressor) to improve the overall efficiency. Secondly, in the low compression ratio centrifugal compressor system, the lubricating oil of the high-speed bearing 7 is provided by the main compressor (or secondary compressor) and recycled together with the motor cooling refrigerant, which is also an innovation of the technology.

[0022] The utility model mainly applies to the patent name: supercharged refrigerating unit (disclosed / authorized number: CN222257081U, application number CN202420396203.6) supercharged refrigerating unit in the main compressor (or secondary compressor) is provided with the supercharging device as the alternative supercharging device The role of providing supercharging; It can also be applied to other types of low compression ratio gas compression fields.

[0023] The above shows and describes the basic principles and main features of the utility model and the advantages of the utility model. Those skilled in the art should understand that the utility model is not limited by the above examples, and the above examples and descriptions in the specification are only to illustrate the principles of the utility model. Without departing from the spirit and scope of the utility model, the utility model can also have various changes and improvements, and these changes and improvements all fall within the scope of the claimed utility model. The scope of protection of the utility model is defined by the appended claims and their equivalents.

Claims

1. A low compression ratio centrifugal compressor characterized by: The low compression ratio centrifugal compressor comprises a centrifugal vortex shell (1), a centrifugal impeller (3), a high-speed motor shell (2) and a high-speed motor stator-rotor assembly (6); The high-speed motor stator-rotor assembly (6) is supported and installed at the inside of the high-speed motor shell (2) through high-speed bearings (7) at both ends, one end of the high-speed motor shell (2) is connected with one end of the centrifugal vortex shell (1), a rotor shaft (13) of the high-speed motor stator-rotor assembly (6) is extended into the inner cavity of the centrifugal vortex shell, and the centrifugal impeller (3) is fixedly installed on the extended part of the rotor shaft (13).

2. A low compression ratio centrifugal compressor according to claim 1, characterized in that: The high-speed motor shell (2) is provided with a motor wiring joint (8), a refrigerant inlet interface (9), a liquid collecting groove (10), a gas-liquid outlet interface (11) and a refrigeration oil inlet interface (12), an external power supply line is connected to the high-speed motor through the motor wiring joint to provide power supply; the refrigerant inlet interface (9) is arranged on the upper part of the high-speed motor shell (2), the liquid collecting groove (10) is arranged on the bottom of the high-speed motor shell (2), and the refrigeration oil inlet interface (12) is arranged on the high-speed motor shell (2) and close to the high-speed bearing (7).

3. A low compression ratio centrifugal compressor according to claim 2, characterized in that: The low compression ratio centrifugal compressor comprises a motor cooling system and a lubricating system, the gas-liquid outlet interface is connected to the motor cooling return hole at the suction pipe port of the centrifugal compressor through an external pipeline, the motor cooling refrigerant returns to the inside of the low-pressure section of the refrigeration system to form the cooling system; The refrigeration oil lubricates the high-speed bearing through the refrigeration oil inlet hole at the high-speed bearing of the motor shell, and enters the inside of the low-pressure section of the refrigeration system to form the lubricating system through the motor cooling refrigerant outlet together with the refrigerant entering the motor cooling return hole at the suction pipe port of the centrifugal compressor.

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