Semi-closed high-temperature centrifugal compressor motor cooling system and cooling method

Abstract

The invention discloses a semi-closed high-temperature centrifugal compressor motor cooling system and a cooling method thereof. The semi-closed high-temperature centrifugal compressor motor cooling system comprises a semi-closed high-temperature centrifugal compressor, a subcooler, a condenser, a cooling medium container and a cold supply device, the flowing direction of the cooling medium in the heat exchange pipeline and the flowing direction of a refrigerant in the subcooler are arranged in a countercurrent manner; a refrigerant in the condenser enters the subcooler through a refrigerant liquid path pipeline, exchanges heat with a cooling medium and then is supplied to a compressor motor, so that the compressor motor dissipates heat; a cooling medium in the cooling medium container exchanges heat with a refrigerant in the subcooler through the heat exchange pipeline, enters the cold supply equipment, is cooled and then returns to the cooling medium container; the cooling effect of the compressor motor of the semi-closed high-temperature centrifugal compressor is improved, efficient heat dissipation is achieved, the operation stability and reliability of the compressor motor in the high-temperature, high-load and complex environment are remarkably improved, the operation load is reduced, and the use and maintenance cost is reduced.

Description

Technical Field

[0001] The invention relates to a semi-enclosed high-temperature centrifugal compressor motor cooling system and a cooling method, belonging to the technical field of centrifugal compressor cooling. Background Art

[0002] In the refrigeration (heating) system, the compressor acts as the "heart", sucking in the low-temperature, low-pressure gas from the evaporator and compressing it into high-temperature, high-pressure gas, which is then transported to the condenser; the temperature of the compressor motor will affect the operation of the entire system, so it is crucial to control the temperature of the compressor motor.

[0003] The temperature of the semi-hermetic centrifugal compressor motor is mainly affected by its cooling effect and motor power. The motor temperature is proportional to the condensing temperature and motor power. The suitable temperature range of the semi-hermetic centrifugal compressor motor is 45℃-70℃. When the temperature of the semi-hermetic centrifugal compressor motor is lower than 40℃, the viscous resistance of the lubricating oil surges, affecting the working efficiency of the semi-hermetic centrifugal compressor. When the temperature of the semi-hermetic centrifugal compressor motor is higher than 90℃, the thermal aging rate of the insulation material increases exponentially, and the risk of rupture of the lubricating film formed at the bearing increases, affecting the safety and service life of the semi-hermetic centrifugal compressor.

[0004] Currently, semi-hermetic centrifugal compressor motors are generally cooled using traditional working fluid cooling. This involves drawing refrigerant from the system condenser and directly entering the semi-hermetic centrifugal compressor motor through the refrigerant liquid line to cool the motor. For semi-hermetic centrifugal compressor motors, especially those with high-temperature operation, as the system condensing temperature increases, the refrigerant's cooling capacity deteriorates due to the refrigerant's characteristics, and the heat transfer temperature difference decreases. This significantly reduces the cooling effect of the semi-hermetic centrifugal compressor motor, and can even lead to the semi-hermetic centrifugal compressor motor shutting down due to the continued temperature increase. This reduces the safety, reliability, and service life of the compressor. Summary of the Invention

[0005] The object of the present invention is to overcome the deficiencies of the above-mentioned prior art and to provide a semi-enclosed high-temperature centrifugal compressor motor cooling system and cooling method.

[0006] The object of the present invention can be achieved through the following measures: a semi-enclosed high-temperature centrifugal compressor motor cooling system, which includes a semi-enclosed high-temperature centrifugal compressor and a condenser, characterized in that the refrigerant outlet of the condenser is connected to the refrigerant inlet of the subcooler through a refrigerant liquid pipeline, and the refrigerant outlet of the subcooler is connected to the refrigerant liquid channel inlet of the compressor motor of the semi-enclosed high-temperature centrifugal compressor through a pipeline; a heat exchange pipeline is inserted into the subcooler, and the heat exchange pipeline is arranged in the form of a spiral coil inside the subcooler; the inlet end of the heat exchange pipeline is connected to the cooling medium outlet of the cooling medium container, the outlet end of the heat exchange pipeline is connected to the reflux port of the cooling equipment, and the liquid supply port of the cooling equipment is connected to the cooling medium inlet of the cooling medium container by connecting the insulation pipeline; the flow direction of the cooling medium in the heat exchange pipeline is countercurrent to the flow direction of the refrigerant in the subcooler.

[0007] A semi-enclosed high-temperature centrifugal compressor motor cooling method, characterized in that it includes a normal mode and a heat exchange mode; Normal mode: When the compressor motor of a semi-hermetic high-temperature centrifugal compressor operates at 45°C-70°C, the refrigerant outlet of the condenser is open, the refrigerant liquid channel inlet of the semi-hermetic high-temperature centrifugal compressor's compression motor is open, the cooling medium inlet and cooling medium outlet of the cooling medium container are closed, and the return port and liquid supply port of the cooling equipment are closed. The refrigerant in the condenser is supplied directly to the compression motor of the semi-hermetic high-temperature centrifugal compressor through the refrigerant liquid channel and the subcooler to dissipate heat. Heat exchange mode: When the compressor motor of the semi-hermetic high-temperature centrifugal compressor is operating at a temperature above 70°C, the refrigerant outlet of the condenser is opened, the refrigerant liquid channel inlet of the compression motor of the semi-hermetic high-temperature centrifugal compressor is opened, the cooling medium inlet and cooling medium outlet of the cooling medium container are both opened, the return port and the liquid supply port of the cooling equipment are both opened, and the refrigerant in the condenser enters the subcooler through the refrigerant liquid pipeline. At the same time, the cooling medium in the cooling medium container enters the heat exchange pipeline in the subcooler. After sufficient heat exchange with the cooling medium in the subcooler, the refrigerant is supplied to the compression motor of the semi-hermetic high-temperature centrifugal compressor to dissipate heat. After the heat exchange is completed, the cooling medium flows back to the cooling equipment through the heat exchange pipeline to be cooled again. After cooling is completed, it returns to the cooling medium container to complete the cycle.

[0008] Furthermore, when the compressor motor temperature of the semi-hermetic high-temperature centrifugal compressor is between 70°C and 90°C, the cooling medium is 25°C cold water, and the cooling medium flow rate is 5.6 kg / s; when the motor temperature of the semi-hermetic high-temperature centrifugal compressor is above 90°C, the cooling medium is 20°C cold water, and the cooling medium flow rate can be 9.4 kg / s.

[0009] Compared with existing technologies, the present invention can produce the following positive effects: the condenser, refrigerant liquid pipeline, semi-hermetic high-temperature centrifugal compressor compressor motor, cooling medium container, heat exchange pipeline, cooling equipment, and subcooler of the present invention constitute a semi-hermetic high-temperature centrifugal compressor motor cooling system. When the compressor motor operates at a low condensing temperature of 45°C to 70°C, it is in normal mode; when the compressor motor operates above the allowable safe condensing temperature, that is, above 70°C, it is in heat exchange mode. When the compressor motor temperature is between 70°C and 90°C, the cooling medium is 25°C cold water at a cooling medium flow rate of 5.6 kg / s; when the compressor motor temperature is above 90°C, the cooling medium can be 20°C cold water at a cooling medium flow rate of 9.4 kg / s. The present invention utilizes the refrigerant liquid from the condenser, which is further supercooled by a subcooler, to cool the compressor motor of the semi-hermetic high-temperature centrifugal compressor. Since the cooling capacity of the refrigerant supercooled by the subcooler is better than that of the traditional cooling method, the cooling effect of the compressor motor of the semi-hermetic high-temperature centrifugal compressor is improved. Even under extremely high temperature conditions of the semi-hermetic high-temperature centrifugal compressor system, the temperature of the compressor motor can still be kept between 45°C and 70°C, thereby improving the working conditions of the compressor motor of the semi-hermetic high-temperature centrifugal compressor, extending its service life, reducing the operating load, and reducing the use and maintenance costs. The overall efficiency of the compressor is improved by 2.3%-4.7%, thereby improving the stability and reliability of the system's operation under high temperature, high load and complex environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 Schematic diagram of the structure of the system of the present invention; In the figure, 1. Semi-hermetic high-temperature centrifugal compressor; 2. Compressor motor; 3. Heat exchange pipe; 4. Cooling medium container; 5. Subcooler; 6. Refrigerant liquid pipeline; 7. Condenser; 8. Cooling equipment; 9. Insulation pipeline. DETAILED DESCRIPTION

[0011] The best embodiment of the present invention is described in detail below with reference to the accompanying drawings: like Figure 1As shown, a semi-hermetic high-temperature centrifugal compressor motor cooling system includes a semi-hermetic high-temperature centrifugal compressor 1, a subcooler 5, a condenser 7, a cooling medium container 4, and a cooling device 8. A heat exchange pipe 3 is inserted into the subcooler 5, and the heat exchange pipe 3 is arranged inside the subcooler 5 in the form of a spiral coil. The refrigerant outlet of the condenser 7 is connected to the refrigerant inlet of the subcooler 5 through a refrigerant liquid pipe 6, and the refrigerant outlet of the subcooler 5 is connected to the refrigerant liquid channel inlet of the compressor motor 2 of the semi-hermetic high-temperature centrifugal compressor 1 through a pipe; the cooling medium outlet of the cooling medium container 4 is connected to the inlet end of the heat exchange pipe 3, and the outlet end of the heat exchange pipe 3 is connected to the reflux port of the cooling device 8. The liquid supply port of the cooling device 8 is connected to the cooling medium inlet of the cooling medium container 4 through a connecting insulation pipe 9. When the cooling medium flows through heat exchange pipe 3, its flow direction is countercurrent to the flow direction of the refrigerant in subcooler 5. After the refrigerant, supercooled by the cooling medium, cools the compressor motor 2 of the semi-hermetic high-temperature centrifugal compressor 1 to below 70°C, the compressor motor 2 drives the impeller to rotate via the drive shaft. After the gas is accelerated by centrifugal force, the kinetic energy is converted into pressure energy in the diffuser, ultimately achieving gas compression and continuously driving the semi-hermetic high-temperature centrifugal compressor 1. The cooling medium in the cooling medium container 4 exchanges heat in the subcooler 5 through heat exchange pipe 3, then enters the cooling device 8 for cooling. After cooling is completed, it returns to the cooling medium container 4 through the insulation pipe 9. The condenser 7, refrigerant liquid pipeline 6, the semi-hermetic high-temperature centrifugal compressor's compressor motor 2, the cooling medium container 4, the heat exchange pipe 3, the cooling device 8, the insulation pipe 9, and the subcooler 5 constitute the semi-hermetic high-temperature centrifugal compressor motor cooling system.

[0012] A semi-enclosed high-temperature centrifugal compressor motor cooling method includes two modes: a conventional mode and a heat exchange mode.

[0013] When the compressor motor 2 of the semi-hermetic high-temperature centrifugal compressor 1 operates at a low condensing temperature of 45°C-70°C, normal mode is enabled. At this time, the refrigerant outlet of the condenser 7 is open, the refrigerant liquid channel inlet of the semi-hermetic high-temperature centrifugal compressor's compressor motor 2 is open, the cooling medium inlet and cooling medium outlet of the cooling medium container 4 are closed, and the return port and liquid supply port of the cooling device 8 are closed. In other words, no cooling medium is supplied, and heat is not exchanged in the subcooler 5. The refrigerant in the condenser 7 passes through the refrigerant liquid channel 6 and the subcooler 5 without heat exchange. Instead, it is directly supplied to the semi-hermetic high-temperature centrifugal compressor's compressor motor 2, dissipating heat.

[0014] When the compressor motor 2 of the semi-hermetic high-temperature centrifugal compressor 1 operates above the permitted safe condensing temperature (i.e., above 70°C), the heat exchange mode is activated. At this point, the refrigerant outlet of the condenser 7 is opened, the refrigerant fluid channel inlet of the semi-hermetic high-temperature centrifugal compressor's compressor motor 2 is opened, the refrigerant inlet and outlet of the refrigerant container 4 are both opened, and the return and supply ports of the cooling device 8 are both opened. This indicates that refrigerant is supplied and heat is exchanged in the subcooler 5. The refrigerant in the condenser 7 enters the subcooler 5 through the refrigerant fluid channel 6. Simultaneously, the refrigerant in the refrigerant container 4 enters the heat exchange pipe 3 within the subcooler 5. After sufficient heat exchange with the refrigerant in the subcooler 5, the refrigerant is supplied to the compressor motor 2 of the semi-hermetic high-temperature centrifugal compressor, where it dissipates heat. After the heat exchange is complete, the refrigerant flows back through the heat exchange pipe 3 to the cooling device 4 for further cooling. After cooling, it returns to the refrigerant container 4, completing the cycle.

[0015] When the temperature of the compressor motor 2 of the semi-hermetic high-temperature centrifugal compressor 1 is higher than 70°C, the semi-hermetic high-temperature centrifugal compressor motor cooling system is turned on; when the temperature of the compressor motor 2 of the semi-hermetic high-temperature centrifugal compressor 1 is between 70°C and 90°C, the cooling medium can be 25°C cold water, and the cooling medium flow rate can be 5.6 kg / s; when the temperature of the semi-hermetic high-temperature centrifugal compressor motor 2 is above 90°C, the cooling medium can be 20°C cold water, and the cooling medium flow rate can be 9.4 kg / s; the temperature of the compressor motor 2 of the semi-hermetic high-temperature centrifugal compressor 1 can be reduced to 45°C-70°C.

[0016] The temperature drop of the compressor motor 2 of the semi-hermetic high-temperature centrifugal compressor 1 of the present invention can be increased by 50°C or even higher; the temperature inside the compressor motor 2 of the semi-hermetic high-temperature centrifugal compressor 1 is reduced to below 70°C, so that the structure can improve the overall efficiency of the compressor by 2.3%-4.7%, and the continuous operation time at an ambient temperature of 45°C and full load conditions is extended to 1.8 times that of the traditional structure, and ensure that the compressor motor 2 of the semi-hermetic high-temperature centrifugal compressor 1 can operate safely and reliably under high temperature conditions.

[0017] It should be understood that any portion not elaborated in detail in this specification belongs to the prior art. The above embodiments are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made by ordinary engineers and technicians in this field to the technical solution of the present invention should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A semi-hermetic high-temperature centrifugal compressor motor cooling system, comprising a semi-hermetic high-temperature centrifugal compressor and a condenser, characterized in that: The refrigerant outlet of the condenser is connected to the refrigerant inlet of the subcooler through a refrigerant liquid pipeline, and the refrigerant outlet of the subcooler is connected to the refrigerant liquid channel inlet of the compressor motor of the semi-enclosed high-temperature centrifugal compressor through a pipeline; a heat exchange pipeline is inserted into the subcooler, and the heat exchange pipeline is arranged inside the subcooler in the form of a spiral coil; the inlet end of the heat exchange pipeline is connected to the cooling medium outlet of the cooling medium container, and the outlet end of the heat exchange pipeline is connected to the reflux port of the cooling equipment, and the liquid supply port of the cooling equipment is connected to the cooling medium inlet of the cooling medium container through a connecting insulation pipeline; the flow direction of the cooling medium in the heat exchange pipeline is countercurrent to the flow direction of the refrigerant in the subcooler.

2. A semi-enclosed high-temperature centrifugal compressor motor cooling method, characterized in that: It includes normal mode and heat exchange mode; Normal mode: When the compressor motor of a semi-hermetic high-temperature centrifugal compressor operates at 45°C-70°C, the refrigerant outlet of the condenser is open, the refrigerant liquid channel inlet of the semi-hermetic high-temperature centrifugal compressor's compression motor is open, the cooling medium inlet and cooling medium outlet of the cooling medium container are closed, and the return port and liquid supply port of the cooling equipment are closed. The refrigerant in the condenser is supplied directly to the compression motor of the semi-hermetic high-temperature centrifugal compressor through the refrigerant liquid channel and the subcooler to dissipate heat. Heat exchange mode: When the compressor motor of the semi-hermetic high-temperature centrifugal compressor is operating at a temperature above 70°C, the refrigerant outlet of the condenser is opened, the refrigerant liquid channel inlet of the compression motor of the semi-hermetic high-temperature centrifugal compressor is opened, the cooling medium inlet and cooling medium outlet of the cooling medium container are both opened, the return port and the liquid supply port of the cooling equipment are both opened, and the refrigerant in the condenser enters the subcooler through the refrigerant liquid pipeline. At the same time, the cooling medium in the cooling medium container enters the heat exchange pipeline in the subcooler. After sufficient heat exchange with the cooling medium in the subcooler, the refrigerant is supplied to the compression motor of the semi-hermetic high-temperature centrifugal compressor to dissipate heat. After the heat exchange is completed, the cooling medium flows back to the cooling equipment through the heat exchange pipeline to be cooled again. After cooling is completed, it returns to the cooling medium container to complete the cycle.

3. A semi-hermetic high-temperature centrifugal compressor motor cooling method according to claim 2, characterized in that: When the compressor motor temperature of the semi-hermetic high-temperature centrifugal compressor is between 70°C and 90°C, the cooling medium is 25°C cold water, and the cooling medium flow rate is 5.6 kg / s; when the motor temperature of the semi-hermetic high-temperature centrifugal compressor is above 90°C, the cooling medium is 20°C cold water, and the cooling medium flow rate can be 9.4 kg / s.

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