Refrigeration Centrifugal Compressor Motor Cooling System and Cooling Method

Abstract

The present application discloses a motor cooling system and a cooling method for a refrigeration centrifugal compressor. The motor cooling system for the refrigeration centrifugal compressor includes: a condenser, a motor, an evaporator, and a flash tank; wherein, the refrigerant outlet of the condenser is connected to a flow channel inside the housing of the motor through a motor cooling liquid inlet pipeline for absorbing the heat of the stator inside the motor; the refrigerant outlet of the flow channel is connected to the flash tank, and the flash tank is used for gas-liquid separation of the incoming refrigerant; the gas outlet of the flash tank is connected to the left cavity of the motor through a motor cooling air supply pipeline, and the right cavity of the motor is connected to the evaporator through a motor cooling return air pipeline; the liquid outlet of the flash tank is connected to the evaporator. The present application solves the problems in the related art that there is too much liquid refrigerant in the motor cavity. When the liquid refrigerant enters the bearing, it is likely to cause instability of the bearing, and when the liquid level exceeds the lower edge of the motor rotor, it will cause unstable operation and large losses of the motor.

Description

Technical Field

[0001] The present application relates to the technical field of compressor cooling, and in particular, to a motor cooling system and a cooling method for a refrigeration centrifugal compressor. Background Technique

[0002] In the traditional motor cooling method of a centrifugal refrigeration compressor, the liquid refrigerant in the condenser is often throttled and directly introduced into the motor cavity. Since the current permanent magnet synchronous motor has high efficiency and requires less refrigerant, too much liquid refrigerant in the motor cavity cannot be vaporized, resulting in too much liquid refrigerant in the motor cavity. These liquid refrigerants entering the bearing are likely to cause bearing instability, and when the liquid level exceeds the lower edge of the motor rotor, it will cause unstable operation and large losses of the motor.

[0003] Regarding the problem that there is too much liquid refrigerant in the motor cavity in the related technology, the liquid refrigerant entering the bearing is likely to cause bearing instability, and the liquid level exceeding the lower edge of the motor rotor will cause unstable operation and large losses of the motor, no effective solution has been proposed yet. Summary of the Invention

[0004] The main purpose of the present application is to provide a motor cooling system and a cooling method for a refrigeration centrifugal compressor to solve the problems in the related technology that there is too much liquid refrigerant in the motor cavity, the liquid refrigerant entering the bearing is likely to cause bearing instability, and the liquid level exceeding the lower edge of the motor rotor will cause unstable operation and large losses of the motor.

[0005] To achieve the above purpose, the present application provides a motor cooling system for a refrigeration centrifugal compressor. The motor cooling system for a refrigeration centrifugal compressor includes: a condenser, a motor, an evaporator, and a flash tank; wherein, the refrigerant outlet of the condenser is connected to the flow channel in the outer shell of the motor through a motor cooling liquid inlet pipeline for absorbing the heat of the stator in the motor; the refrigerant outlet of the flow channel is connected to the flash tank, and the flash tank is used for gas-liquid separation of the incoming refrigerant; the gas outlet of the flash tank is connected to the left cavity of the motor through a motor cooling gas supply pipeline, and the right cavity of the motor is connected to the evaporator through a motor cooling gas return pipeline; the liquid outlet of the flash tank is connected to the evaporator.

[0006] Further, a motor cooling liquid inlet pipeline ball valve is arranged on the motor cooling liquid inlet pipeline; the liquid outlet of the flash tank is connected to the evaporator through a secondary throttle valve.

[0007] Further, a motor cooling gas return pipeline valve is arranged on the motor cooling gas return pipeline.

[0008] Further, the flash tank is connected to the condenser through a primary throttle valve.

[0009] Further, it further includes a make-up gas pipeline connected to the flash evaporator, and a front stage of a multi-stage compressor and a rear stage of a multi-stage compressor are connected in parallel on the make-up gas pipeline; the front stage of the multi-stage compressor is connected to the evaporator, and the rear stage of the multi-stage compressor is connected to the condenser.

[0010] Further, the motor includes a motor housing, a stator and a rotor provided in the motor housing, and the flow groove is opened in the motor housing and arranged around the motor housing.

[0011] Further, there is a gap between the stator and the rotor, and ventilation holes are provided on the outer side of the stator, and the gap and the ventilation holes communicate the left cavity and the right cavity of the motor.

[0012] According to another aspect of the present application, there is provided a method for cooling a motor of a refrigeration centrifugal compressor, using a cooling system for a motor of a refrigeration centrifugal compressor, and the method includes the following steps:

[0013] (1) Introduce the liquid refrigerant in the condenser into the flow groove of the outer shell of the motor. After the liquid refrigerant absorbs the heat of the motor stator, part of it vaporizes to form gaseous refrigerant;

[0014] (2) The liquid refrigerant and the gaseous refrigerant enter the flash evaporator, and the liquid and the gas are separated through the flash evaporator;

[0015] (3) The separated gas enters the left cavity of the motor from the flash evaporator, then reaches the right cavity of the motor through the gap between the stator and the rotor of the motor and the ventilation holes on the outer side of the stator, and then returns to the evaporator; the separated liquid enters the evaporator from the flash evaporator.

[0016] Further, step (1) is specifically: throttle the liquid refrigerant in the condenser and introduce it into the flow groove of the outer shell of the motor. After the liquid refrigerant absorbs the heat of the motor stator, part of it vaporizes to form gaseous refrigerant.

[0017] Further, in step (3), the separated liquid enters the evaporator from the flash evaporator after throttling.

[0018] In the embodiment of the present application, a condenser, a motor, an evaporator and a flash evaporator are provided. Among them, the refrigerant outlet of the condenser is connected to the flow channel in the outer shell of the motor through the motor cooling liquid inlet pipeline, which is used to absorb the heat of the stator in the motor. The refrigerant outlet of the flow channel is connected to the flash evaporator, and the flash evaporator is used for gas-liquid separation of the incoming refrigerant. The gas outlet of the flash evaporator is connected to the left cavity of the motor through the motor cooling gas supply pipeline, and the right cavity of the motor is connected to the evaporator through the motor cooling return gas pipeline. The liquid outlet of the flash evaporator is connected to the evaporator. The purpose of separating the motor refrigerant into liquid and gas states and allowing the gaseous refrigerant to enter the motor cavity for cooling is achieved. Thus, the technical effect of avoiding the accumulation of a large amount of liquid refrigerant in the motor cavity, which may cause bearing or motor instability, is realized. Furthermore, the problem in the related art that there is too much liquid refrigerant in the motor cavity, and the liquid refrigerant entering the bearing is likely to cause bearing instability, and the liquid level exceeding the lower edge of the motor rotor will cause unstable motor operation and large losses is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings forming a part of this application are used to provide a further understanding of this application, making other features, objectives, and advantages of this application more obvious. The schematic embodiments and descriptions thereof of this application are used to explain this application and do not constitute an improper limitation of this application. In the drawings:

[0020] Figure 1 is a schematic structural diagram according to the embodiment of this application;

[0021] Among them, 1 is the condenser, 2 is the ventilation hole, 3 is the flow channel, 4 is the gap, 5 is the front stage of multi-stage compression, 6 is the supplementary gas pipeline, 7 is the motor cooling gas supply pipeline, 8 is the first throttle valve, 9 is the flash evaporator, 10 is the second throttle valve, 11 is the motor cooling liquid return pipeline, 12 is the evaporator, 13 is the motor cooling return gas pipeline valve, 14 is the rear stage of multi-stage compression, 15 is the motor cooling liquid inlet pipeline, 16 is the motor cooling liquid inlet pipeline ball valve, 17 is the motor, and 18 is the motor cooling return gas pipeline. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] In order to enable those skilled in the art to better understand the solution of this application, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of this application.

[0023] It should be noted that the terms "first", "second", etc. in the description, claims and the above-mentioned drawings of this application are used to distinguish similar objects, and do not necessarily describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so as to implement the embodiments of this application described herein.

[0024] In this application, the orientation or positional relationship indicated by the terms "upper", "lower", "inner", etc. is based on the orientation or positional relationship shown in the drawings. These terms are mainly used to better describe this application and its embodiments, and are not used to limit that the indicated devices, elements or components must have a specific orientation, or be constructed and operated in a specific orientation.

[0025] Moreover, in addition to being able to represent an orientation or positional relationship, some of the above terms may also be used to represent other meanings. For example, the term "upper" may also be used to represent a certain attachment relationship or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in this application can be understood according to specific circumstances.

[0026] In addition, terms such as "arranged", "provided with", "connected", "fixed", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or there is internal communication between two devices, elements or components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0027] In addition, the meaning of the term "plurality" should be two or more.

[0028] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The following will refer to the drawings and combine the embodiments to detail this application.

[0029] As Figure 1 shown, the embodiment of this application provides a cooling system for a refrigeration centrifugal compressor motor 17. The cooling system for the refrigeration centrifugal compressor motor 17 includes: a condenser 1, a motor 17, an evaporator 12, and a flash tank 9; wherein, the refrigerant outlet of the condenser 1 is connected to the flow channel 3 inside the housing of the motor 17 through a motor cooling liquid inlet pipeline 15 for absorbing the heat of the stator in the motor 17; the refrigerant outlet of the flow channel 3 is connected to the flash tank 9, and the flash tank 9 is used for gas-liquid separation of the incoming refrigerant; the gas outlet of the flash tank 9 is connected to the left cavity of the motor 17 through a motor cooling gas supply pipeline 7, and the right cavity of the motor 17 is connected to the evaporator 12 through a motor cooling gas return pipeline 18; the liquid outlet of the flash tank 9 is connected to the evaporator 12.

[0030] In this embodiment, the temperature of the liquid refrigerant in the condenser 1 decreases after throttling. The cooled liquid refrigerant enters the flow channel 3 inside the housing of the motor 17 to cool the stator in the motor 17. After absorbing the heat of the stator of the motor 17, part of the liquid refrigerant vaporizes. The vaporized refrigerant and the unvaporized liquid refrigerant enter the flash tank 9 together, and the flash tank 9 separates the gas from the liquid. The separated liquid refrigerant directly enters the evaporator 12 after throttling and cooling, while the gaseous refrigerant flows into the motor cooling gas supply pipeline 7 from the gas outlet of the flash tank 9, and from the left cavity of the motor 17 to the right cavity of the motor 17. The cavity of the motor 17 is cooled by the gaseous refrigerant, and the gaseous refrigerant discharged from the right cavity of the motor 17 returns to the evaporator 12. This embodiment achieves the purpose of separating the refrigerant of the motor 17 into liquid and gas states and enabling the gaseous refrigerant to enter the cavity of the motor 17 for cooling, thereby realizing the technical effect of avoiding the instability of the bearing or the motor 17 caused by the accumulation of a large amount of liquid refrigerant in the cavity of the motor 17. Furthermore, it solves the problems in the related art that there is too much liquid refrigerant in the cavity of the motor 17. When the liquid refrigerant enters the bearing, it is likely to cause the bearing to be unstable, and when the liquid level exceeds the lower edge of the rotor of the motor 17, it will cause the motor 17 to operate unstably and have large losses.

[0031] Moreover, in this embodiment, the refrigerant inlet of the flow channel 3 of the housing of the motor 17 is connected to the refrigerant outlet of the condenser 1 through the motor cooling liquid inlet pipeline 15, and the refrigerant outlet of the flow channel 3 is connected to the flash tank 9 through the motor cooling liquid return pipeline 11, and is not connected to the evaporator 12. After the liquid refrigerant exchanges heat with the stator of the motor 17 in the flow channel 3 of the housing of the motor 17, part of the liquid refrigerant absorbs heat and vaporizes and enters the flash tank 9 together with the unvaporized liquid refrigerant. At this time, the temperatures of the liquid refrigerant, the gaseous refrigerant, and the flow channel 3 are close. Then the gaseous refrigerant enters the cavity of the motor 17 to cool the cavity of the motor 17, that is, the cooling temperature of the flow channel 3 is close to the cooling temperature in the cavity of the motor 17. Therefore, it can also avoid too large a temperature difference between the cavity of the motor 17 and the flow channel 3, resulting in the condensation phenomenon on the housing of the motor 17.

[0032] As Figure 1 shown, a motor cooling liquid inlet pipeline ball valve 16 is provided on the motor cooling liquid inlet pipeline 15 to throttle and cool the liquid refrigerant coming out of the condenser 1; the liquid outlet of the flash tank 9 is connected to the evaporator 12 through a secondary throttle valve 10 to throttle and cool the liquid refrigerant separated by the flash tank 9. A motor cooling gas return pipeline valve 13 is provided on the motor cooling gas return pipeline 18, and the flash tank 9 is connected to the condenser 1 through a primary throttle valve 8.

[0033] As Figure 1As shown in the figure, it further includes a make-up gas pipeline 6 connected to the flash evaporator 9. A multi-stage compression front stage 5 and a multi-stage compression rear stage 14 are connected in parallel on the make-up gas pipeline 6. The multi-stage compression front stage 5 is connected to the evaporator 12, and the multi-stage compression rear stage 14 is connected to the condenser 1. The make-up gas for multi-stage compression is realized through the make-up gas pipeline 6, thereby improving the energy efficiency of the compressor.

[0034] As Figure 1 shown in the figure, the motor 17 includes a motor housing, a stator and a rotor disposed inside the motor housing. The flow groove 3 is opened inside the motor housing and arranged around the motor housing, thereby effectively increasing the heat exchange area and improving the heat exchange efficiency. There is a gap 4 between the stator and the rotor, and a ventilation hole 2 is provided outside the stator. The ventilation hole 2 is opened outside the stator silicon steel sheet of the motor 17, and the gap 4 and the ventilation hole 2 communicate the left cavity and the right cavity of the motor 17.

[0035] According to another aspect of the present application, a method for cooling a refrigeration centrifugal compressor motor 17 is provided. Using a refrigeration centrifugal compressor motor 17 cooling system, the method includes the following steps:

[0036] (1) Introduce the liquid refrigerant in the condenser 1 into the flow groove 3 of the outer shell of the motor 17. After the liquid refrigerant absorbs the heat of the stator of the motor 17, part of it vaporizes to form a gaseous refrigerant;

[0037] (2) The liquid refrigerant and the gaseous refrigerant enter the flash evaporator 9, and the liquid refrigerant and the gaseous refrigerant are separated through the flash evaporator 9;

[0038] (3) The separated gaseous refrigerant enters the left cavity of the motor 17 from the flash evaporator 9, then reaches the right cavity of the motor 17 through the gap 4 between the stator and the rotor of the motor 17 and the ventilation hole 2 outside the stator, and then returns to the evaporator 12; the separated liquid refrigerant enters the evaporator 12 from the flash evaporator 9.

[0039] Further, step (1) is specifically: the liquid refrigerant in the condenser 1 is introduced into the flow groove 3 of the outer shell of the motor 17 after throttling. After the liquid refrigerant absorbs the heat of the stator of the motor 17, part of it vaporizes to form a gaseous refrigerant.

[0040] Further, in step (3), the separated liquid enters the evaporator 12 from the flash evaporator 9 after throttling.

[0041] The above are only the preferred embodiments of the present application and are not used to limit the present application. For those skilled in the art, the present application can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A motor cooling system for a refrigeration centrifugal compressor, characterized in that, it includes: a condenser, a motor, an evaporator and a flash tank; wherein, the refrigerant outlet of the condenser is connected to the flow channel inside the housing of the motor through a motor cooling liquid inlet pipeline, for absorbing the heat of the stator inside the motor; the refrigerant outlet of the flow channel is connected to the flash tank, and the flash tank is used for gas-liquid separation of the incoming refrigerant; the gas outlet of the flash tank is connected to the left cavity of the motor through a motor cooling gas supply pipeline, and the right cavity of the motor is connected to the evaporator through a motor cooling gas return pipeline; the liquid outlet of the flash tank is connected to the evaporator; the motor cooling system for the refrigeration centrifugal compressor further includes a gas supply pipeline connected to the flash tank, and multiple stages of the front stage of multi-stage compression and multiple stages of the rear stage of multi-stage compression are connected in parallel on the gas supply pipeline; the multiple stages of the front stage of multi-stage compression are connected to the evaporator, and the multiple stages of the rear stage of multi-stage compression are connected to the condenser; the motor includes a motor housing, a stator and a rotor arranged inside the motor housing, and the flow channel is arranged inside the motor housing and surrounds the motor housing.

2. The motor cooling system for the refrigeration centrifugal compressor according to claim 1, characterized in that, a motor cooling liquid inlet pipeline ball valve is arranged on the motor cooling liquid inlet pipeline; the liquid outlet of the flash tank is connected to the evaporator through a secondary throttle valve.

3. The motor cooling system for the refrigeration centrifugal compressor according to claim 2, characterized in that, a motor cooling gas return pipeline valve is arranged on the motor cooling gas return pipeline.

4. The motor cooling system for the refrigeration centrifugal compressor according to claim 3, characterized in that, the flash tank is connected to the condenser through a primary throttle valve.

5. The motor cooling system for the refrigeration centrifugal compressor according to claim 1, characterized in that, there is a gap between the stator and the rotor, and ventilation holes are arranged on the outside of the stator, and the gap and the ventilation holes communicate the left cavity and the right cavity of the motor.

6. A motor cooling method for a refrigeration centrifugal compressor, using the motor cooling system for the refrigeration centrifugal compressor according to any one of claims 1 to 5, characterized in that, it includes the following steps: (1) Introduce the liquid refrigerant in the condenser into the flow channel of the housing of the motor, and after the liquid refrigerant absorbs the heat of the motor stator, part of it vaporizes to form gaseous refrigerant; (2) The liquid refrigerant and the gaseous refrigerant enter the flash tank, and the liquid and the gas are separated through the flash tank; (3) The separated gas enters the left cavity of the motor from the flash tank, then reaches the right cavity of the motor through the gap between the motor stator and the rotor and the ventilation holes on the outside of the stator, and then returns to the evaporator; The separated liquid enters the evaporator from the flash tank.

7. The motor cooling method for the refrigeration centrifugal compressor according to claim 6, characterized in that, the specific step (1) is: throttle the liquid refrigerant in the condenser and then introduce it into the flow channel of the housing of the motor, and after the liquid refrigerant absorbs the heat of the motor stator, part of it vaporizes to form gaseous refrigerant.

8. The motor cooling method for the refrigeration centrifugal compressor according to claim 6, characterized in that, In the step (3), the separated liquid enters the evaporator from the flash tank after throttling.

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