CN116222023A - Compressor oil return system and control method thereof - Google Patents

Compressor oil return system and control method thereof Download PDF

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Publication number
CN116222023A
CN116222023A CN202310377070.8A CN202310377070A CN116222023A CN 116222023 A CN116222023 A CN 116222023A CN 202310377070 A CN202310377070 A CN 202310377070A CN 116222023 A CN116222023 A CN 116222023A
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China
Prior art keywords
oil
compressor
oil return
storage tank
evaporator
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CN202310377070.8A
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Chinese (zh)
Inventor
孙玉香
吴迪
李敏
王璐
高理富
曹会彬
江曼
王大庆
吴旭东
姚睿
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Hefei Institutes of Physical Science of CAS
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Hefei Institutes of Physical Science of CAS
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Priority to CN202310377070.8A priority Critical patent/CN116222023A/en
Publication of CN116222023A publication Critical patent/CN116222023A/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B31/00—Compressor arrangements
    • F25B31/002—Lubrication
    • F25B31/004—Lubrication oil recirculating arrangements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B41/00—Fluid-circulation arrangements
    • F25B41/20—Disposition of valves, e.g. of on-off valves or flow control valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B41/00—Fluid-circulation arrangements
    • F25B41/40—Fluid line arrangements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B43/00—Arrangements for separating or purifying gases or liquids; Arrangements for vaporising the residuum of liquid refrigerant, e.g. by heat
    • F25B43/02—Arrangements for separating or purifying gases or liquids; Arrangements for vaporising the residuum of liquid refrigerant, e.g. by heat for separating lubricants from the refrigerant
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B43/00—Arrangements for separating or purifying gases or liquids; Arrangements for vaporising the residuum of liquid refrigerant, e.g. by heat
    • F25B43/04—Arrangements for separating or purifying gases or liquids; Arrangements for vaporising the residuum of liquid refrigerant, e.g. by heat for withdrawing non-condensible gases
    • F25B43/043—Arrangements for separating or purifying gases or liquids; Arrangements for vaporising the residuum of liquid refrigerant, e.g. by heat for withdrawing non-condensible gases for compression type systems
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B49/00—Arrangement or mounting of control or safety devices
    • F25B49/02—Arrangement or mounting of control or safety devices for compression type machines, plants or systems
    • F25B49/022—Compressor control arrangements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2500/00—Problems to be solved
    • F25B2500/16—Lubrication
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B30/00—Energy efficient heating, ventilation or air conditioning [HVAC]
    • Y02B30/70—Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating

Abstract

The invention relates to a compressor oil return system, which is characterized in that: the system comprises a main liquid path circulation system, a cold oil system, an oil return system, an oil supply system, a first auxiliary oil return system and a second auxiliary oil return system, wherein the main liquid path circulation system comprises a compressor, a condenser, a throttling electronic expansion valve and an evaporator; the cold oil system comprises a condenser, a cooling electronic expansion valve, a plate heat exchanger and an evaporator; the oil return system comprises a condenser, an oil return electromagnetic valve, a plate heat exchanger and an oil storage tank; the oil supply system comprises an oil storage tank and a compressor; the first auxiliary oil return system comprises an evaporator, a liquid taking pump and a compressor; the second auxiliary oil return system comprises an oil storage tank, an air taking electromagnetic valve, an air taking pump and a compressor. The invention also discloses a control method of the compressor oil return system. The invention improves the reliability of the oil return system, reduces the vibration and operation noise of the unit, avoids abnormal lubrication failure of the bearing caused by incapability of establishing pressure difference of the startup and shutdown, and improves the operation stability and the operation life of the unit of the system.

Description

Compressor oil return system and control method thereof
Technical Field
The invention relates to the technical field of compressor oil return systems, in particular to a compressor oil return system and a control method thereof.
Background
The commercial screw type water chilling unit refrigerating oil circulates synchronously along with a refrigerant system, the reliability of an oil return system directly influences noise, vibration, operation life and the like of the unit, and at present, the oil return system has the following problems:
1) The unit oil tank is arranged below the exhaust end of the compressor, and the temperature of the oil tank is influenced by the exhaust temperature, so that the lubrication effect of the unit is poor;
2) The unit adopts injection auxiliary oil return, and abnormal conditions such as injection dirty blockage, filter dirty blockage, welding concentricity and the like lead to failure of injection oil return;
3) The effective oil supply pressure difference cannot be quickly established under the conditions of machine set shutdown, low-ring temperature start and the like, so that the lubrication of the bearings is invalid, and the service life of the machine set is influenced;
4) The oil supply temperature of the unit is uncontrollable, the temperature of the lubricating oil cannot be ensured to be in an optimal range, the viscosity of the lubricating oil is influenced, and the oil is easy to oxidize and deteriorate;
5) Under the low temperature environment, the unit is started and needs to be heated, the phenomenon of oil leakage is very easy to occur when the unit is directly started, and a large amount of frozen oil enters the evaporator, so that the unit sucks air and brings liquid.
In summary, the existing oil return system and control method of the water-cooled screw unit compressor have certain defects, the oil leakage phenomenon of the unit under severe working conditions is easy to occur after sales, and risks such as lubrication failure and increase of vibration noise of the unit are caused.
Disclosure of Invention
The invention aims to overcome the defects of failure of auxiliary oil return, poor lubrication effect, low-temperature startup oil leakage and the like, and the primary aim of the invention is to provide a compressor oil return system which improves the reliability of an oil return system, reduces the vibration and noise of a unit and improves the running stability and the running life of the unit.
In order to achieve the above purpose, the present invention adopts the following technical scheme: an oil return system of a compressor comprises a main liquid path circulation system, an oil cooling system, an oil return system, an oil supply system, a first auxiliary oil return system and a second auxiliary oil return system; the main liquid path circulation system comprises a compressor, a condenser, a throttling electronic expansion valve and an evaporator, wherein an exhaust port at the upper end of the compressor is communicated with the upper end of the condenser through a pipeline, a liquid collecting bag at the bottom of the condenser is communicated with one end of the throttling electronic expansion valve through a pipeline, the other end of the throttling electronic expansion valve is communicated with a liquid collecting bag at the bottom of the evaporator through a pipeline, and an outlet at the top of the evaporator is communicated with an air suction port of the compressor through a pipeline; the oil cooling system comprises a condenser, a cooling electronic expansion valve, a plate heat exchanger and an evaporator, wherein a small liquid collecting bag of the condenser is communicated with one end of the cooling electronic expansion valve through a pipeline, the other end of the cooling electronic expansion valve is communicated with one end of the plate heat exchanger through a pipeline, and the other end of the plate heat exchanger is communicated with the middle part of a shell of the evaporator through a pipeline; the oil return system comprises a condenser, an oil return electromagnetic valve, a plate heat exchanger and an oil storage tank, wherein one end of the condenser is communicated with one end of the oil return electromagnetic valve through a pipeline, the other end of the oil return electromagnetic valve is communicated with one end of the plate heat exchanger through a pipeline, and the other end of the plate heat exchanger is communicated with the oil storage tank through a pipeline; the oil supply system comprises an oil storage tank and a compressor, wherein the oil storage tank is communicated with the compressor through a pipeline, and refrigerating oil is supplied to the compressor from the oil storage tank through a pressure difference; the first auxiliary oil return system comprises an evaporator, a liquid taking pump and a compressor, wherein the middle lower part of a shell of the evaporator is connected with one end of the liquid taking pump through a pipeline, and the other end of the liquid taking pump is connected with the air suction end of the compressor through a pipeline; the second auxiliary oil return system comprises an oil storage tank, an air taking electromagnetic valve, an air taking pump and a compressor, wherein the oil storage tank is communicated with one end of the air taking electromagnetic valve through a pipeline, the other end of the air taking electromagnetic valve is communicated with one end of the air taking pump through a pipeline, and the other end of the air taking pump is communicated with the air suction end of the compressor through a pipeline.
In the main liquid path circulation system, low-temperature low-pressure gaseous refrigerant is compressed by a compressor and then is discharged from an upper end exhaust port, enters a condenser, forms high-temperature high-pressure liquid refrigerant after heat exchange with cooling water, flows out of a bottom liquid collecting bag in the condenser, is throttled and depressurized by a throttle electronic expansion valve, then enters a liquid accumulating bag at the bottom of the evaporator, is evaporated in the evaporator and exchanges heat with chilled water, and the evaporated gaseous refrigerant enters an air suction port of the compressor from an outlet at the top of the evaporator.
In the oil cooling system, a high-temperature high-pressure liquid refrigerant is taken from a small liquid collecting bag in a condenser, throttled and depressurized by a cooling electronic expansion valve and enters a plate heat exchanger to cool refrigerating oil, and the gaseous refrigerant after heat exchange enters the middle part of a low-pressure evaporator shell and enters a compressor along with an air outlet of the evaporator to participate in circulation.
In the oil return system, high-temperature and high-pressure gas discharged by a compressor is impacted and separated in built-in oil in a condenser, and separated high-temperature and high-pressure frozen oil flows out from an upper outlet in a shell of the condenser, enters a plate heat exchanger for cooling, and then flows into an oil storage tank.
In the first auxiliary oil return system, an auxiliary oil return pipe is led from the middle lower part of the evaporator shell, power is provided by rotation of a liquid taking pump impeller, refrigerating oil in the evaporator is extracted, and the refrigerating oil enters a suction end of a compressor; in the second auxiliary oil return system, high-pressure gas in the oil storage tank enters the liquid taking pump from the top end after being separated by a gas-liquid separation net in the oil storage tank, power is provided for the liquid taking pump, and the gas finally flows into the air suction end of the compressor.
The bottom of oil storage tank sets up the magnet that is used for adsorbing impurity, sets up the oil return filter that is used for filtering the oil return impurity in the oil storage tank, sets up the gas-liquid separation net that is used for oil-gas separation in the oil storage tank.
Another object of the present invention is to provide a method for controlling an oil return system of a compressor, comprising the following sequential steps:
(1) Before the system is not started, the default opening degree of the throttling electronic expansion valve and the air taking electromagnetic valve is 0, when the system receives a starting command, the oil return electromagnetic valve is started, when the actual pressure difference value of the system is smaller than the set pressure difference value, the opening degree of the throttling electronic expansion valve and the air taking electromagnetic valve is kept unchanged by 0, at the moment, the condenser and the oil storage tank rapidly raise the pressure to lubricate a compressor bearing in time, and when the pressure difference value of the system is larger than or equal to the set pressure difference value, the throttling electronic expansion valve enters a pressure difference free regulation mode, and the system is started normally;
(2) When the system is normally shut down, the system is firstly unloaded to 50% of load, at the moment, the oil return electromagnetic valve and the gas taking electromagnetic valve are closed, the system is synchronously shut down, the inside of the oil storage tank is in a high-pressure state, and refrigerating oil is continuously supplied to the system for lubrication;
(3) And (3) when the emergency, the fault and the power failure occur, the oil return electromagnetic valve and the gas taking electromagnetic valve are immediately closed, the inside of the oil storage tank is still guaranteed to be in a high-pressure state, the oil is continuously supplied to the compressor bearings, and when the system is powered on and receives a starting command, the step (1) is executed.
According to the technical scheme, the beneficial effects of the invention are as follows: firstly, the invention ensures that the lubricating viscosity of the refrigeration oil is in an optimal state, improves the reliability of an oil return system, reduces the vibration and the operation noise of a unit, avoids abnormal lubrication failure of a bearing caused by incapability of establishing pressure difference of a switching machine, and improves the operation stability and the operation life of the unit of the system; secondly, the refrigerating oil is stored in the external oil storage tank, so that the influence of the exhaust temperature on the temperature of the oil tank is avoided, meanwhile, the refrigerating oil is not required to be preheated when a system unit is started, the phenomena of oil leakage and liquid entrainment during air suction are avoided, and the use satisfaction of users is improved; thirdly, the auxiliary oil return of the invention adopts the pump body extraction type, the high-pressure gas is used as a power source, the stability and reliability are realized, and the abnormal oil return failure caused by the system filth blockage can be avoided.
Drawings
FIG. 1 is a schematic diagram of a system of the present invention;
fig. 2 is a logic diagram of the oil supply control of the present invention.
Detailed Description
As shown in fig. 1, a compressor oil return system comprises a main liquid path circulation system, a cold oil system, an oil return system, an oil supply system, a first auxiliary oil return system and a second auxiliary oil return system; the main liquid path circulation system comprises a compressor 1, a condenser 2, a throttling electronic expansion valve 12 and an evaporator 13, wherein an exhaust port at the upper end of the compressor 1 is communicated with the upper end of the condenser 2 through a pipeline, a liquid collecting bag at the bottom of the condenser 2 is communicated with one end of the throttling electronic expansion valve 12 through a pipeline, the other end of the throttling electronic expansion valve 12 is communicated with a liquid collecting bag at the bottom of the evaporator 13 through a pipeline, and an outlet at the top of the evaporator 13 is communicated with an air suction port of the compressor 1 through a pipeline; the oil cooling system comprises a condenser 2, a cooling electronic expansion valve 3, a plate heat exchanger 5 and an evaporator 13, wherein a small liquid collecting bag of the condenser 2 is communicated with one end of the cooling electronic expansion valve 3 through a pipeline, the other end of the cooling electronic expansion valve 3 is communicated with one end of the plate heat exchanger 5 through a pipeline, and the other end of the plate heat exchanger 5 is communicated with the middle part of a shell of the evaporator 13 through a pipeline; the oil return system comprises a condenser 2, an oil return electromagnetic valve 4, a plate heat exchanger 5 and an oil storage tank 6, wherein one end of the condenser 2 is communicated with one end of the oil return electromagnetic valve 4 through a pipeline, the other end of the oil return electromagnetic valve 4 is communicated with one end of the plate heat exchanger 5 through a pipeline, and the other end of the plate heat exchanger 5 is communicated with the oil storage tank 6 through a pipeline; the oil supply system comprises an oil storage tank 6 and a compressor 1, wherein the oil storage tank 6 is communicated with the compressor 1 through a pipeline, and frozen oil is supplied to the compressor 1 from the oil storage tank 6 through a pressure difference; the first auxiliary oil return system comprises an evaporator 13, a liquid taking pump 9 and a compressor 1, wherein the middle lower part of a shell of the evaporator 13 is connected with one end of the liquid taking pump 9 through a pipeline, and the other end of the liquid taking pump 9 is connected with the air suction end of the compressor 1 through a pipeline; the second auxiliary oil return system comprises an oil storage tank 6, an air taking electromagnetic valve 8, an air taking pump 9 and a compressor 1, wherein the oil storage tank 6 is communicated with one end of the air taking electromagnetic valve 8 through a pipeline, the other end of the air taking electromagnetic valve 8 is communicated with one end of the air taking pump 9 through a pipeline, and the other end of the air taking pump 9 is communicated with the air suction end of the compressor 1 through a pipeline.
In the main liquid path circulation system, low-temperature low-pressure gaseous refrigerant is compressed by a compressor 1 and then discharged from an upper end exhaust port, enters a condenser 2, exchanges heat with cooling water to form high-temperature high-pressure liquid refrigerant, flows out of a bottom liquid collecting bag in the condenser 2, is throttled and depressurized by a throttle electronic expansion valve 12, then enters a liquid collecting bag at the bottom of an evaporator 13, is evaporated in the evaporator 13 and exchanges heat with chilled water, and the evaporated gaseous refrigerant enters an air suction port of the compressor 1 from an outlet at the top of the evaporator 13.
In the oil cooling system, a high-temperature high-pressure liquid refrigerant is taken from a small liquid collecting bag in a condenser 2, is throttled and depressurized by a cooling electronic expansion valve 3 and enters a plate heat exchanger 5 to cool refrigerating oil, and the gaseous refrigerant after heat exchange enters the middle part of a low-pressure evaporator 13 shell and enters the compressor 1 along with an air outlet of the evaporator 13 to participate in circulation.
In the oil return system, high-temperature and high-pressure gas discharged by the compressor 1 is impacted and separated in built-in oil in the condenser 2, and separated high-temperature and high-pressure frozen oil flows out from an upper outlet in the shell of the condenser 2, enters the plate heat exchanger 5 for cooling, and then flows into the oil storage tank 6.
In the first auxiliary oil return system, an auxiliary oil return pipe is led from the middle lower part of the shell of the evaporator 13, the rotation of the impeller of the liquid taking pump 9 is used for providing power, the frozen oil in the evaporator 13 is pumped, and the frozen oil enters the air suction end of the compressor 1; in the second auxiliary oil return system, high-pressure gas in the oil storage tank 6 enters the liquid taking pump 9 from the top end after being separated by a gas-liquid separation net in the oil storage tank 6, power is provided for the liquid taking pump 9, and the gas finally flows into the air suction end of the compressor 1.
The bottom of the oil storage tank 6 is provided with a magnet 10 for adsorbing impurities, an oil return filter 11 for filtering oil return impurities is arranged in the oil storage tank 6, and a gas-liquid separation net 7 for oil-gas separation is arranged in the oil storage tank 6.
As shown in fig. 2, the control method of the present invention includes the following sequential steps:
(1) Before the system is not started, the default opening degree of the throttle electronic expansion valve 12 and the air taking electromagnetic valve 8 is 0, when the system receives a starting command, the oil return electromagnetic valve 4 is opened, when the actual pressure difference value of the system is smaller than the pressure difference set value, the opening degree of the throttle electronic expansion valve 12 and the air taking electromagnetic valve 8 is kept unchanged, at the moment, the condenser 2 and the oil storage tank 6 rapidly raise the pressure to lubricate the bearings of the compressor 1 in time, and when the pressure difference value of the system is larger than or equal to the pressure difference set value, the throttle electronic expansion valve 12 enters a pressure difference free regulation mode, and the system is started normally;
(2) During normal shutdown, the system is firstly unloaded to 50% of load, at the moment, the oil return electromagnetic valve 4 and the air taking electromagnetic valve 8 are closed, the system is synchronously stopped, the inside of the oil storage tank 6 is in a high-pressure state, and refrigerating oil is continuously supplied to the system for lubrication;
(3) When the emergency, the fault and the power failure occur, the oil return electromagnetic valve 4 and the air taking electromagnetic valve 8 are immediately closed, the inside of the oil storage tank 6 is still guaranteed to be in a high-pressure state at the moment, the oil supply for the bearing of the compressor 1 is continued, and when the system is powered on and receives a starting command, the step (1) is executed.
The invention is further described below with reference to fig. 1 and 2.
According to the invention, the oil storage tank 6 is adopted, so that the frozen oil is separated from the exhaust gas, the oil heating is canceled, the low-temperature direct start is performed, the suction of air is avoided, the liquid carrying is avoided, the cold oil plate replacing structure is additionally arranged at the oil inlet, the oil supply temperature is accurately controlled in a throttling mode of taking liquid from the condenser 2 and cooling the electronic expansion valve 3, and the lubricating effect is ensured.
The pump body is adopted to extract auxiliary oil return, the high-pressure gas of the oil storage tank 6 is used as a power source to drive the impeller of the liquid taking pump 9 to rotate, and power is provided for the oil return flow path of the evaporator 13; the power source of the structure adopts high-pressure gas, can avoid the phenomenon of filth blockage, and the extracted liquid and the high-pressure gas of the power source run in independent cavities, thereby being stable and reliable.
The invention increases the control logic of quick oil supply and continuous oil supply, and controls the on-off of a flow path through the air taking electromagnetic valve 8, the oil return electromagnetic valve 4 and the electronic expansion valve when the unit is started and shut down, so that the cavity of the oil storage tank 6 is kept in a high-pressure state, and continuous refrigeration oil lubrication is provided for the bearing of the compressor 1. In the present invention, the unit means the whole system as shown in fig. 1.
The unit adopts differential pressure to supply and return oil, the mixture of frozen oil and high-pressure gas is changed from the built-in oil condenser 2 to the oil storage tank 6 through the oil return electromagnetic valve 4 and the cold oil plate, the oil return filter 11 can filter impurities of an oil return system, when the pressure detection value P1-P2 of the condenser 2 is more than or equal to 100Pa (the set value of 100Pa is the pressure loss from the condenser 2 to the oil storage tank 6), the system prompts to change the oil return filter 11, the magnet 10 is uniformly distributed at the bottom of the oil storage tank 6 and is used for adsorbing impurities such as scrap iron and the like, and the dirty blockage of an oil supply pipeline is avoided; the top of the oil storage tank 6 is provided with a vapor-liquid separation net for separating lubricating oil from refrigerant gas, the top of the oil storage tank 6 is high-pressure gas after vapor-liquid separation, the bottom of the oil storage tank 6 is liquid frozen oil, a temperature sensing bag is used for detecting the temperature T of the frozen oil, an electronic expansion valve is matched with a cold oil plate to keep the temperature of the oil storage tank 6 in an optimal state, when the detected temperature T is between a set temperature T+/-2, the electronic expansion valve 3 is kept open, when the detected temperature T is greater than the set temperature T+2, the electronic expansion valve 3 is opened, when the detected temperature T is less than the set temperature T-2, the opening of the electronic expansion valve 3 is reduced, so that the aim of accurately controlling the oil temperature is fulfilled. The built-in oil tank structure of compressor 1, when starting the machine in winter, exhaust temperature receives the oil tank temperature to influence greatly, and a large amount of frozen oil can't in time separate, leads to the unit to bubble oily, and part unit is equipped with oil heating, and heating time in winter is about 5 hours, influences unit start-up time.
After the mixture of refrigerant and oil in the oil storage tank 6 is subjected to the vapor-liquid separation, the top is high-pressure gas, the high-pressure gas enters the liquid taking pump 9 through the gas taking electromagnetic valve 8, the high-pressure gas is used as a power source to drive the impeller of the liquid taking pump 9 to rotate, so that the pressure energy is converted into mechanical energy, the mechanical energy is returned to the air suction port of the compressor 1 through a connecting pipeline, the impeller on the other side synchronously rotates through a coaxial shaft, the mixed liquid of the frozen oil and the refrigerant on the liquid level surface of the evaporator 13 is pumped to the air suction port of the compressor 1, the gas taking electromagnetic valve 8 is opened every 1 hour when the unit normally operates, the opening time is one hour, the cold energy loss is reduced when the auxiliary oil return effect is achieved, compared with the abnormality that the injection oil return is easy to lose efficacy, the auxiliary oil return system high-pressure gas used as the power source can avoid auxiliary oil return failure caused by system impurities, the pumped liquid and the high-pressure gas of the power source operate in an independent cavity, and the auxiliary oil return effect is stable and reliable, and the oil return effect is good.
When the unit is started, the throttle electronic expansion valve 12 is closed to 0, the air taking electromagnetic valve 8 is closed, the unit exhaust is only connected with the condenser 2 and the oil storage tank 6, the pressure of the condenser 2 and the oil storage tank 6 is rapidly increased at the moment, the pressure difference can be rapidly established, the frozen oil in the oil storage tank 6 can be rapidly sent to the bearing lubrication of the compressor 1, when the system pressure difference delta P exceeds the pressure difference set value P, the throttle electronic expansion valve 12 enters a pressure difference adjusting mode, and the unit is normally started. When the unit is shut down, the male and female rotors continuously rotate under the action of inertia, when the unit is shut down normally and the load is reduced to 50%, the unit is shut down at the moment, the oil return electromagnetic valve 4 and the gas taking electromagnetic valve 8 are closed, the inside of the oil storage tank 6 is in a high-pressure state, and oil can be continuously supplied to the bearing of the compressor 1 after the unit is shut down; when the unit is in emergency, is stopped in fault or is suddenly powered off, the oil return electromagnetic valve 4 and the gas taking electromagnetic valve 8 are closed, the oil storage tank 6 serves as a high-pressure source to continuously supply oil for the bearing, and when a starting command is received after the fault of the standby group is cleared, the normal starting logic is executed; therefore, the problem of bearing lubrication failure of the unit in different on-off states is solved.
In summary, the invention ensures that the lubricating viscosity of the refrigeration oil is in the optimal state, improves the reliability of an oil return system, reduces the vibration and the operation noise of the unit, avoids abnormal lubrication failure of the bearing caused by incapability of establishing pressure difference of a startup and shutdown machine, and improves the operation stability and the operation life of the unit of the system; according to the invention, the frozen oil is stored in the external oil storage tank 6, so that the influence of exhaust temperature on the oil temperature is avoided, meanwhile, the frozen oil is not required to be preheated when a system unit is started, the phenomena of oil leakage and liquid entrainment during air suction are avoided, and the use satisfaction of users is improved; the auxiliary oil return device adopts the pump body extraction type, the high-pressure gas is used as a power source, the stability and reliability are realized, and the abnormal oil return failure caused by the dirty blockage of the system can be avoided.

Claims (7)

1. An oil return system of a compressor, which is characterized in that: the system comprises a main liquid path circulation system, a cold oil system, an oil return system, an oil supply system, a first auxiliary oil return system and a second auxiliary oil return system; the main liquid path circulation system comprises a compressor, a condenser, a throttling electronic expansion valve and an evaporator, wherein an exhaust port at the upper end of the compressor is communicated with the upper end of the condenser through a pipeline, a liquid collecting bag at the bottom of the condenser is communicated with one end of the throttling electronic expansion valve through a pipeline, the other end of the throttling electronic expansion valve is communicated with a liquid collecting bag at the bottom of the evaporator through a pipeline, and an outlet at the top of the evaporator is communicated with an air suction port of the compressor through a pipeline; the oil cooling system comprises a condenser, a cooling electronic expansion valve, a plate heat exchanger and an evaporator, wherein a small liquid collecting bag of the condenser is communicated with one end of the cooling electronic expansion valve through a pipeline, the other end of the cooling electronic expansion valve is communicated with one end of the plate heat exchanger through a pipeline, and the other end of the plate heat exchanger is communicated with the middle part of a shell of the evaporator through a pipeline; the oil return system comprises a condenser, an oil return electromagnetic valve, a plate heat exchanger and an oil storage tank, wherein one end of the condenser is communicated with one end of the oil return electromagnetic valve through a pipeline, the other end of the oil return electromagnetic valve is communicated with one end of the plate heat exchanger through a pipeline, and the other end of the plate heat exchanger is communicated with the oil storage tank through a pipeline; the oil supply system comprises an oil storage tank and a compressor, wherein the oil storage tank is communicated with the compressor through a pipeline, and refrigerating oil is supplied to the compressor from the oil storage tank through a pressure difference; the first auxiliary oil return system comprises an evaporator, a liquid taking pump and a compressor, wherein the middle lower part of a shell of the evaporator is connected with one end of the liquid taking pump through a pipeline, and the other end of the liquid taking pump is connected with the air suction end of the compressor through a pipeline; the second auxiliary oil return system comprises an oil storage tank, an air taking electromagnetic valve, an air taking pump and a compressor, wherein the oil storage tank is communicated with one end of the air taking electromagnetic valve through a pipeline, the other end of the air taking electromagnetic valve is communicated with one end of the air taking pump through a pipeline, and the other end of the air taking pump is communicated with the air suction end of the compressor through a pipeline.
2. The compressor oil return system of claim 1, wherein: in the main liquid path circulation system, low-temperature low-pressure gaseous refrigerant is compressed by a compressor and then is discharged from an upper end exhaust port, enters a condenser, forms high-temperature high-pressure liquid refrigerant after heat exchange with cooling water, flows out of a bottom liquid collecting bag in the condenser, is throttled and depressurized by a throttle electronic expansion valve, then enters a liquid accumulating bag at the bottom of the evaporator, is evaporated in the evaporator and exchanges heat with chilled water, and the evaporated gaseous refrigerant enters an air suction port of the compressor from an outlet at the top of the evaporator.
3. The compressor oil return system of claim 1, wherein: in the oil cooling system, a high-temperature high-pressure liquid refrigerant is taken from a small liquid collecting bag in a condenser, throttled and depressurized by a cooling electronic expansion valve and enters a plate heat exchanger to cool refrigerating oil, and the gaseous refrigerant after heat exchange enters the middle part of a low-pressure evaporator shell and enters a compressor along with an air outlet of the evaporator to participate in circulation.
4. The compressor oil return system of claim 1, wherein: in the oil return system, high-temperature and high-pressure gas discharged by a compressor is impacted and separated in built-in oil in a condenser, and separated high-temperature and high-pressure frozen oil flows out from an upper outlet in a shell of the condenser, enters a plate heat exchanger for cooling, and then flows into an oil storage tank.
5. The compressor oil return system of claim 1, wherein: in the first auxiliary oil return system, an auxiliary oil return pipe is led from the middle lower part of the evaporator shell, power is provided by rotation of a liquid taking pump impeller, refrigerating oil in the evaporator is extracted, and the refrigerating oil enters a suction end of a compressor; in the second auxiliary oil return system, high-pressure gas in the oil storage tank enters the liquid taking pump from the top end after being separated by a gas-liquid separation net in the oil storage tank, power is provided for the liquid taking pump, and the gas finally flows into the air suction end of the compressor.
6. The compressor oil return system of claim 1, wherein: the bottom of oil storage tank sets up the magnet that is used for adsorbing impurity, sets up the oil return filter that is used for filtering the oil return impurity in the oil storage tank, sets up the gas-liquid separation net that is used for oil-gas separation in the oil storage tank.
7. The control method of the compressor oil return system according to any one of claims 1 to 6, characterized in that: the method comprises the following steps in sequence:
(1) Before the system is not started, the default opening degree of the throttling electronic expansion valve and the air taking electromagnetic valve is 0, when the system receives a starting command, the oil return electromagnetic valve is started, when the actual pressure difference value of the system is smaller than the set pressure difference value, the opening degree of the throttling electronic expansion valve and the air taking electromagnetic valve is kept unchanged by 0, at the moment, the condenser and the oil storage tank rapidly raise the pressure to lubricate a compressor bearing in time, and when the pressure difference value of the system is larger than or equal to the set pressure difference value, the throttling electronic expansion valve enters a pressure difference free regulation mode, and the system is started normally;
(2) When the system is normally shut down, the system is firstly unloaded to 50% of load, at the moment, the oil return electromagnetic valve and the gas taking electromagnetic valve are closed, the system is synchronously shut down, the inside of the oil storage tank is in a high-pressure state, and refrigerating oil is continuously supplied to the system for lubrication;
(3) And (3) when the emergency, the fault and the power failure occur, the oil return electromagnetic valve and the gas taking electromagnetic valve are immediately closed, the inside of the oil storage tank is still guaranteed to be in a high-pressure state, the oil is continuously supplied to the compressor bearings, and when the system is powered on and receives a starting command, the step (1) is executed.
CN202310377070.8A 2023-04-11 2023-04-11 Compressor oil return system and control method thereof Pending CN116222023A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202310377070.8A CN116222023A (en) 2023-04-11 2023-04-11 Compressor oil return system and control method thereof

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202310377070.8A CN116222023A (en) 2023-04-11 2023-04-11 Compressor oil return system and control method thereof

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CN116222023A true CN116222023A (en) 2023-06-06

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