Bearing gas supply system and method

Abstract

The application provides a bearing gas supply system and a method thereof, wherein the bearing gas supply system comprises a condenser, a compressor and a refrigerant pump, the condenser is connected with the compressor through a first connecting pipeline, the condenser is connected with the compressor through a second connecting pipeline, the refrigerant pump is arranged on the second connecting pipeline, the first connecting pipeline forms a gas supply pipeline for supplying gas to the bearing of the compressor, and the second connecting pipeline forms a liquid supply pipeline for supplying liquid refrigerant to the bearing of the compressor. The bearing gas supply system and the gas supply method can take liquid from the condenser, pressurize the liquid by using the refrigerant pump, separate gas and liquid, supply gas and liquid to the bearing of the compressor uniformly, and adopt different gas supply schemes in the process of starting and stopping the system and in the process of normal operation. Stable bearing gas supply can be ensured in the process of starting and stopping the system, the operation efficiency of the compressor and the operation efficiency of the refrigeration system are improved, noise, vibration and operation stability are effectively improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of refrigeration compressor bearings, and particularly relates to a bearing gas supply system and a method thereof. BACKGROUND

[0002] Centrifugal water chiller units are commonly used in various building air conditioners. The centrifugal water chiller unit (or centrifugal chiller unit) for air conditioning is composed of a centrifugal refrigeration compressor, an evaporator, a condenser, a main motor, a suction recovery device, a lubrication system, a control cabinet, a starting cabinet, and the like. At present, the compressor bearings of the centrifugal unit generally adopt oil lubricated bearings and electromagnetic bearings (i.e. magnetic levitation bearings).

[0003] The use of oil lubricated bearings requires an additional lubricating oil supply system, which increases the complexity of the system. The lubricating oil will leak into the refrigeration system during the operation of the compressor and will be mixed with the refrigerant. Therefore, a lubricating oil return system is needed for periodic oil return. Oil lubricated bearings also have mechanical friction, which reduces mechanical efficiency, reduces the performance of the unit, and the like.

[0004] The centrifugal compressor using electromagnetic bearings relies on magnetic force to suspend the bearings. The electric control system of the magnetic levitation bearing is complex, large in size, and requires high consistency in bearing processing. The system has poor impact resistance, and in addition, an additional abnormal power-off protection measure is needed.

[0005] At present, gas bearings (gas levitation bearings) have begun to be applied to centrifugal compressors. The gas bearing uses gas force to support the shaft and has the following advantages: 1) compared with the compressor using oil lubricated bearings, there is no need for an oil supply system, an oil return system, a cold oil system, a filtration system, no risk of lubricating oil leakage, and lubricating oil maintenance work is saved; when the bearing is working, it is in a suspended state, there is no friction, mechanical loss is reduced, and the performance of the unit is improved; 2) compared with the compressor using magnetic levitation bearings, there is no need for a complex electric control system and an abnormal power-off protection system.

[0006] However, because the gas bearing needs external gas supply when working, the problem of unstable gas supply of the gas bearing often occurs in the prior art, and therefore, it is necessary to solve the problem of stable gas supply of the gas bearing in the field. SUMMARY

[0007] In view of the above technical problems, the technical scheme of the present application provides a bearing gas supply system and a method thereof to improve the stability of the gas supply of the compressor bearing and improve the operating efficiency of the compressor.

[0008] A bearing gas supply system, comprising a condenser, a compressor and a refrigerant pump, the condenser is connected with the compressor through a first connecting pipeline, the condenser is connected with the compressor through a second connecting pipeline, the refrigerant pump is arranged on the second connecting pipeline, the first connecting pipeline forms a gas supply pipeline for supplying gas to the bearing of the compressor, and the second connecting pipeline forms a liquid supply pipeline for supplying liquid refrigerant to the bearing of the compressor.

[0009] Further, a condensing pressure sensor is arranged in the condenser, a motor cavity pressure sensor is arranged in the compressor, and a first electromagnetic valve and a first filter are further arranged on the first connecting pipeline.

[0010] Further, a second filter and a liquid supply pressure sensor are arranged on the second connecting pipeline.

[0011] Further, a third connecting pipeline is further included, the condenser is connected with the compressor through the third connecting pipeline, and a check valve is arranged on the third connecting pipeline.

[0012] Further, an evaporator is further included, the condenser is connected with the evaporator through a fourth connecting pipeline, and the evaporator is connected with the compressor through a fourth connecting pipeline.

[0013] Further, a throttling electronic expansion valve and a second electromagnetic valve are arranged on the fourth connecting pipeline, and an evaporation pressure sensor is arranged on the evaporator.

[0014] Further, the fourth connecting pipeline comprises two fourth connecting pipeline branch pipelines, and the throttling electronic expansion valve and the second electromagnetic valve are arranged on the two fourth connecting pipeline branch pipelines respectively.

[0015] The method for supplying gas by using the bearing gas supply system, comprising the following steps: step one, during the operation of the bearing gas supply system, the condensing pressure sensor and the motor cavity pressure sensor detect the condensing pressure Pc of the condenser and the motor cavity pressure Pd of the compressor and transmit signals to the controller; step two, the controller calculates the pressure difference AP0 of the condensing pressure Pc and the motor cavity pressure Pd, when the pressure difference AP of the condensing pressure Pc and the motor cavity pressure Pd calculated by the controller is greater than or equal to the minimum bearing gas supply pressure difference AP0, the controller controls the refrigerant pump to be closed, and the bearing gas supply system supplies gas to the bearing of the compressor according to the gas supply pipeline formed on the first connecting pipeline; when the AP calculated by the controller is less than the minimum bearing gas supply pressure difference AP0, the controller controls the refrigerant pump to be opened, and liquid is supplied to the bearing of the compressor through the liquid supply pipeline formed on the second connecting pipeline, until the AP is greater than the minimum bearing gas supply pressure difference AP0, the controller controls the refrigerant pump to be closed, and the bearing gas supply system supplies gas to the bearing of the compressor according to the gas supply pipeline formed on the first connecting pipeline again.

[0016] Further, the bearing supply system in step one includes normal operation of the bearing supply system and normal start or normal stop of the bearing supply system.

[0017] Further, the bearing supply system in step one includes normal operation of the bearing supply system and normal start or normal stop of the bearing supply system.

[0018] The bearing supply system and the supply method can take liquid from the condenser, pressurize the liquid by using the refrigerant pump, supply unified gas and liquid to the compressor bearing, and separate the supply scheme during system start and stop from the normal operation. The stable bearing supply during system start and stop can improve the operation efficiency of the compressor and the operation efficiency of the refrigeration system, effectively improve the noise, vibration and operation stability, avoid mechanical contact and wear of the bearing, and avoid the damage to the gas suspension bearing caused by the insufficient supply pressure difference of the gas suspension bearing when the power supply of the bearing is suddenly cut off. BRIEF DESCRIPTION OF DRAWINGS

[0019] The application will be described in more detail below based on the embodiments and with reference to the accompanying drawings.

[0020] Figure 1 The figure is a schematic diagram of the connection structure of the bearing supply system of the application.

[0021] The figure is a schematic diagram of the connection structure of the bearing supply system of the application.

[0022] In the drawings, the same components are denoted by the same reference numerals. The drawings are not drawn according to the actual scale. DETAILED DESCRIPTION

[0023] The application will be described in more detail below based on the embodiments and with reference to the accompanying drawings.

[0024] As Figure 1As shown in the figure, the bearing gas supply system of the present application includes a condenser 1, a compressor 4 and a refrigerant pump 12. The condenser 1 is connected to the compressor 4 through a first connecting pipeline, and is also connected to the compressor 4 through a second connecting pipeline. The refrigerant pump 12 is arranged on the second connecting pipeline. Thus, the compressor 4 can be supplied with gas through the condenser 1 and the first connecting pipeline, and can be supplied with liquid through the condenser 1, the second connecting pipeline and the refrigerant pump 12. The gas condensed by the condenser 1 can form liquid refrigerant, which can be the liquid refrigerant commonly used in the prior art.

[0025] The condenser 1 is provided with a condensing pressure sensor 2, and the compressor 4 is provided with a motor cavity pressure sensor 5. The first connecting pipeline is further provided with a first electromagnetic valve 9 and a first filter 14. The gas is supplied to the bearing of the compressor 4 through the condenser 1, the first connecting pipeline and the first filter 14 on the first connecting pipeline. The first electromagnetic valve 9 can open or close the first connecting pipeline.

[0026] The second connecting pipeline is further provided with a second filter 11 and a liquid supply pressure sensor 13. The liquid refrigerant is supplied to the bearing of the compressor 4 through the condenser 1, the second filter 11 on the second connecting pipeline and the refrigerant pump 12. The liquid supply pressure sensor 13 can detect the pressure of the liquid in the second connecting pipeline.

[0027] The first filter 14 can be a copper pipe filter. The first filter 14 can filter out impurities in the connecting pipeline to ensure the accuracy of the bearing. The second filter 11 can filter out fine impurities in the connecting pipeline to ensure that there are no impurities in the refrigerant pump. The first connecting pipeline and the second connecting pipeline partially overlap, that is, the first connecting pipeline and the second connecting pipeline overlap at a section connected to the compressor 4. The liquid refrigerant is supplied to the bearing of the compressor 4 through the condenser 1, the second filter 11 on the second connecting pipeline, the refrigerant pump 12 and the first filter 14.

[0028] The bearing gas supply system of the present application further includes a third connecting pipeline. The condenser 1 is connected to the compressor 4 through the third connecting pipeline. A check valve 3 is arranged on the third connecting pipeline to ensure that the gas flows in one direction to the compressor 4 on the third connecting pipeline.

[0029] The bearing gas supply system of the application further comprises an evaporator 6, the condenser 1 is connected with the evaporator 6 through a fourth connecting pipeline, the evaporator 6 is connected with the compressor 4 through the fourth connecting pipeline, the fourth connecting pipeline is further provided with a throttling electronic expansion valve 10 and a second electromagnetic valve 8, and the evaporator 6 is provided with an evaporating pressure sensor 7 to detect the pressure in the evaporator 6. The fourth connecting pipeline comprises two fourth connecting pipeline branch pipelines, and the throttling electronic expansion valve 10 and the second electromagnetic valve 8 are arranged on the two fourth connecting pipeline branch pipelines respectively.

[0030] The condensing pressure sensor 2, the evaporating pressure sensor 7, the motor cavity pressure sensor 5 and the liquid supply pressure sensor 13 can respectively detect the condensing pressure Pc of the unit, the evaporating pressure Pe, the motor cavity pressure Pd and the liquid supply pressure Pg. The motor cavity pressure sensor 5 and the liquid supply pressure sensor 13 are named according to the setting positions of the pressure sensors, that is, the motor cavity pressure sensor 5 is arranged in the motor cavity of the compressor 4, and the liquid supply pressure sensor 13 is arranged in the second connecting pipeline liquid-state refrigerant pipeline.

[0031] Therefore, for the gas supply pipeline, the gas supply pipeline formed on the first connecting pipeline is used, that is, the condenser 1-the first electromagnetic valve 9-the first filter 14-the compressor 4 bearing. For the liquid supply pipeline, the liquid supply pipeline formed on the second connecting pipeline is used to provide liquid-state refrigerant to the compressor 4 bearing, that is, the condenser 1-the second filter 11-the refrigerant pump 12-the first filter 14-the compressor 4 bearing.

[0032] The bearing gas supply system of the application further comprises a controller, and the bearing gas supply system of the application is controlled and operated by the controller. The specific gas supply system working process is as follows:

[0033] When the bearing gas supply system or unit of the present application is started or normally stopped, the bearing gas supply system or unit is controlled by the controller to operate in the following manner or flow: during the starting and stopping process of the bearing gas supply system or unit, the condenser pressure sensor 2 and the motor cavity pressure sensor 5 keep detecting the condenser pressure Pc of the condenser 1 and the motor cavity pressure Pd of the compressor 4 and transmitting signals to the controller, and the mainboard controller always calculates the pressure difference ΔP of the condenser pressure Pc and the motor cavity pressure Pd; when ΔP is less than the minimum bearing gas supply pressure difference ΔP0, the controller controls to open the refrigerant pump 12, and liquid supply is performed through the liquid supply pipeline formed on the second connecting pipeline, that is, the condenser 1-second filter 11-refrigerant pump 12-first filter 14-compressor 4 bearing, until ΔP is greater than the minimum bearing gas supply pressure difference ΔP0, the controller controls the refrigerant pump 12 to be closed. The above-mentioned ΔP0 is a preset pressure difference comparison basic parameter value, which is usually a set value of the pressure difference ΔP0 of the condenser pressure Pc and the motor cavity pressure Pd obtained according to experimental results, and when it is greater than the minimum pressure difference value ΔP0, the gas in the condenser 1 will supply gas to the compressor 4 bearing under the influence of the pressure difference. The parameter value of the preset pressure difference ΔP0 is different for different compressors 4.

[0034] When the bearing gas supply system or unit of the present application is in normal operation, the bearing gas supply system or unit is controlled to operate in the following flow: during the operation of the bearing gas supply system or unit, according to the real-time working condition, the condenser pressure sensor 2 and the motor cavity pressure sensor 5 keep detecting the condenser pressure Pc of the condenser 1 and the motor cavity pressure Pd of the compressor 4 and transmitting signals to the controller, and the mainboard controller always calculates the pressure difference ΔP0 of the condenser pressure Pc and the motor cavity pressure Pd; when ΔP is less than the minimum bearing gas supply pressure difference ΔP0, the controller controls to open the refrigerant pump 12, and liquid supply is performed through the liquid supply pipeline formed on the second connecting pipeline, that is, the condenser 1-second filter 11-refrigerant pump 12-first filter 14-compressor 4 bearing, until ΔP is greater than the minimum bearing gas supply pressure difference ΔP0, the controller controls the refrigerant pump 12 to be closed. When the controller calculates that the pressure difference ΔP of the condenser pressure Pc and the motor cavity pressure Pd is large, and ΔP is greater than or equal to the minimum bearing gas supply pressure difference ΔP0, the controller controls the refrigerant pump 12 to be closed, and the bearing gas supply system supplies gas according to the gas supply pipeline formed on the first connecting pipeline, that is, according to the condenser 1-first electromagnetic valve 9-filter-compressor 4 bearing, to meet the gas supply amount of the entire bearing gas supply system.

[0035] When the bearing gas supply system or unit of the application fails to stop and the refrigerant pump 12 fails to start, the controller controls the bearing gas supply system to work according to the following steps: when the main board controller of the unit detects a fault signal (for example, whether the condensing pressure Pc, the evaporating pressure Pe, the motor cavity pressure Pd, the liquid supply pressure Pg and other parameters are normal) and a refrigerant pump 12 fault signal, the controller controls the first electromagnetic valve 9 and the second electromagnetic valve 8 to change from the current state to closed, and the throttling electronic expansion valve 10 is directly closed to 0 from the current opening D0. Then, the corresponding connection pipes connected with the first electromagnetic valve 9, the second electromagnetic valve 8 and the throttling electronic expansion valve 10 are all closed, only the third connection pipe connecting the condenser 1 and the compressor 4 is kept to supply gas to the bearing of the compressor 4, and the high-pressure gas of the condenser 1 during shutdown is used to supply gas to the bearing of the compressor 4 in emergency, so as to avoid the bearing from being damaged due to the grinding of the shaft in the case that the bearing is still in the state of inertia rotation during shutdown.

[0036] The bearing gas supply system or method of the application takes liquid from the condenser 1, pressurizes the refrigerant pump 12, separates the gas supply and the liquid supply, unifies the gas supply and the liquid supply, and supplies gas according to different schemes during start and stop of the centrifugal refrigeration unit and normal operation, so as to ensure the safety and stability of the gas supply and protect the bearing of the compressor 4.

[0037] Although the application has been described with reference to the preferred embodiments, various modifications can be made to it without departing from the scope of the application, and equivalent substitutions can be made to the components thereof. In particular, the technical features mentioned in each embodiment can be combined in any manner as long as there is no structural conflict. The application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A bearing air supply system, characterized in that, The system includes a condenser, a compressor, and a refrigerant pump. The condenser is connected to the compressor via a first connecting pipe and a second connecting pipe. The refrigerant pump is located on the second connecting pipe. The first connecting pipe forms a gas supply line to the compressor bearings, and the second connecting pipe forms a liquid supply line to the compressor bearings. A condensing pressure sensor is installed in the condenser, and a motor cavity pressure sensor is installed in the compressor. The condensing pressure sensor detects the condensing pressure Pc of the unit, and the motor cavity pressure sensor detects the motor cavity pressure Pd. Based on the real-time pressure difference ΔP between the condensing pressure (Pc) and the compressor motor cavity pressure (Pd), the gas supply line or the liquid supply line is dynamically switched. The system also includes a third connecting pipe, through which the condenser is connected to the compressor. A check valve is installed on the third connecting pipe. The system also includes an evaporator, through which the condenser is connected to the evaporator, and through which the evaporator is connected to the compressor.

2. The bearing air supply system according to claim 1, characterized in that, The first connecting pipeline is also equipped with a first solenoid valve and a first filter.

3. The bearing air supply system according to claim 1, characterized in that, The second connecting pipe is equipped with a second filter and a liquid supply pressure sensor.

4. The bearing air supply system according to claim 3, characterized in that, The fourth connecting pipe is equipped with a throttling electronic expansion valve and a second solenoid valve, and the evaporator is equipped with an evaporation pressure sensor.

5. The bearing air supply system according to claim 4, characterized in that, The fourth connecting pipeline includes two fourth connecting pipeline branches, and the throttling electronic expansion valve and the second solenoid valve are respectively installed on the two fourth connecting pipeline branches.

6. A method for supplying air using the bearing air supply system according to any one of claims 1-5, characterized in that, Includes the following steps: Step 1: During the operation of the bearing air supply system, the condensing pressure sensor and the motor cavity pressure sensor continuously detect the condensing pressure Pc of the condenser and the motor cavity pressure Pd of the compressor and transmit the signals to the controller. Step 2: The controller calculates the pressure difference ΔP0 between the condenser condensing pressure Pc and the motor cavity pressure Pd. When the controller calculates that the pressure difference ΔP between the condenser condensing pressure Pc and the motor cavity pressure Pd is greater than or equal to the minimum bearing gas supply pressure difference ΔP0, the controller controls the refrigerant pump to shut down, and the bearing gas supply system supplies gas to the compressor bearing according to the gas supply pipeline formed on the first connecting pipeline. When the controller calculates that ΔP is less than the minimum supply pressure difference of the bearing ΔP0, the controller controls the refrigerant pump to start and supply liquid to the compressor bearing through the liquid supply pipeline formed on the second connecting pipeline. When ΔP is greater than the minimum supply pressure difference of the bearing ΔP0, the controller controls the refrigerant pump to shut down, and the bearing supply system supplies air to the compressor bearing again through the supply pipeline formed on the first connecting pipeline.

7. The gas supply method according to claim 6, characterized in that, The operation of the bearing air supply system in step one includes the normal operation of the bearing air supply system as well as the normal start-up or normal shutdown of the bearing air supply system.

8. The gas supply method according to claim 7, characterized in that, The system also includes the following steps: when the controller detects a fault in the bearing gas supply system or a fault signal in the refrigerant pump, the controller controls the shutdown of the gas supply line and liquid supply line formed on the first and second connecting lines, respectively. The condenser is directly connected to the compressor through the third connecting line. The controller controls the condenser to supply gas to the compressor bearing through the third connecting line and using the high-pressure gas from the condenser when the compressor is stopped.

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