CN112344574B - Refrigerating system, unit and method for adjusting lubricating oil quantity of refrigerating system - Google Patents
Refrigerating system, unit and method for adjusting lubricating oil quantity of refrigerating system Download PDFInfo
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- CN112344574B CN112344574B CN202011359551.9A CN202011359551A CN112344574B CN 112344574 B CN112344574 B CN 112344574B CN 202011359551 A CN202011359551 A CN 202011359551A CN 112344574 B CN112344574 B CN 112344574B
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- 239000010687 lubricating oil Substances 0.000 title claims abstract description 58
- 238000000034 method Methods 0.000 title claims abstract description 18
- 239000003921 oil Substances 0.000 claims abstract description 180
- 238000005057 refrigeration Methods 0.000 claims abstract description 30
- 238000002347 injection Methods 0.000 claims abstract description 18
- 239000007924 injection Substances 0.000 claims abstract description 18
- 230000001105 regulatory effect Effects 0.000 claims abstract description 4
- 239000003507 refrigerant Substances 0.000 claims description 39
- 239000007788 liquid Substances 0.000 claims description 37
- 238000001514 detection method Methods 0.000 claims description 9
- 239000000314 lubricant Substances 0.000 claims description 6
- 230000001276 controlling effect Effects 0.000 claims description 4
- 238000004891 communication Methods 0.000 abstract description 10
- 239000012530 fluid Substances 0.000 abstract description 2
- 230000000694 effects Effects 0.000 description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 7
- 239000000203 mixture Substances 0.000 description 5
- 239000000243 solution Substances 0.000 description 5
- 238000000926 separation method Methods 0.000 description 4
- 230000001050 lubricating effect Effects 0.000 description 3
- 238000005461 lubrication Methods 0.000 description 3
- 230000005856 abnormality Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 230000001502 supplementing effect Effects 0.000 description 1
Classifications
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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
- F25B1/00—Compression machines, plants or systems with non-reversible cycle
- F25B1/10—Compression machines, plants or systems with non-reversible cycle with multi-stage compression
-
- 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
-
- 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
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Mechanical Engineering (AREA)
- Thermal Sciences (AREA)
- General Engineering & Computer Science (AREA)
- Control Of Positive-Displacement Pumps (AREA)
- Compressor (AREA)
Abstract
The invention discloses a refrigerating system, a unit and a method for regulating the quantity of lubricating oil of the refrigerating system, which relate to the field of machinery and are used for optimizing the performance of the refrigerating system. The refrigeration system comprises an evaporator, a condenser, a first-stage compressor, a second-stage compressor, an injection loop and a bypass branch. The evaporator is in fluid communication with the condenser and is located between the condenser and the first stage compressor. The second-stage compressor is connected with both the first-stage compressor and the condenser, and the second-stage compressor is positioned between the first-stage compressor and the condenser. The injection loop is connected with the evaporator, the condenser and the first-stage compressor and is configured to inject lubricating oil in the evaporator to the first-stage compressor. The bypass branch is disposed between the oil tank of the first stage compressor and the oil tank of the second stage compressor, and is configured to switch between a connected state and an interrupted state. By adopting the technical scheme, each stage of compressor in the refrigerating system with the two stages of compressors can be effectively lubricated.
Description
Technical Field
The invention relates to the field of compressors, in particular to a refrigerating system, a refrigerating unit and a method for regulating the quantity of lubricating oil in the refrigerating system.
Background
In a cold water/heat pump unit in which dual compressors requiring oil lubrication are arranged in series, two compressors are divided into a low-pressure stage compressor and a high-pressure stage compressor according to a compressor arrangement. When two compressors are operated simultaneously, the refrigeration/heating cycle thereof is: the refrigerant in the evaporator is compressed by the low-pressure stage compressor and then exhausted to the air suction port of the high-pressure stage compressor, and then is compressed again by the high-pressure stage compressor to obtain the gaseous refrigerant with higher pressure and temperature. During system operation, the unit cannot completely isolate the lubricant and the refrigerant, so that the lubricant may inevitably mix with the refrigerant and eventually remain in the evaporator with the refrigeration cycle.
In the related art, the oil return mode of the unit is to adopt an ejector to eject the mixture of lubricating oil and refrigerant of the unit back to the oil tanks of the low-pressure stage compressor and the high-pressure stage compressor.
The inventors found that at least the following problems exist in the prior art: because the pressure of the low-pressure level compressor is different from that of the high-pressure level compressor, the oil return effect is also different, and the conditions that the pressure of the oil tank of the high-pressure level compressor is higher and the injection oil return effect is poor often exist.
Disclosure of Invention
The invention provides a refrigerating system, a unit and a method for adjusting the quantity of lubricating oil in the refrigerating system, which are used for optimizing the performance of the refrigerating system.
An embodiment of the present invention provides a refrigeration system, including:
an evaporator configured to evaporate a refrigerant;
a condenser configured to condense the refrigerant;
a first stage compressor, the evaporator being located between the condenser and the first stage compressor;
A second stage compressor, the gas pressure of the first stage compressor being lower than the gas pressure in the second stage compressor; the second-stage compressor is connected with the first-stage compressor and the condenser, and is positioned between the first-stage compressor and the condenser;
an injection loop connected to the evaporator, the condenser and the first stage compressor, the injection loop configured to inject lubricating oil in the evaporator to the first stage compressor; and
And a bypass branch provided between the oil tank of the first-stage compressor and the oil tank of the second-stage compressor, the bypass branch being configured to switch between a communication state and an intercepting state.
In some embodiments, the ejector circuit comprises:
The first ejector comprises a first jet port, a first introducing port and a first outlet, wherein the first jet port is communicated with a refrigerant outlet of the condenser, the first introducing port is communicated with the evaporator, and the first outlet is communicated with an oil tank of the first-stage compressor.
In some embodiments, the ejector circuit comprises:
The second ejector comprises a second jet port, a second introducing port and a second outlet, the second jet port is communicated with a refrigerant outlet of the condenser, the second introducing port is communicated with the evaporator, and the second outlet is communicated with an air suction port of the first-stage compressor; and
The third ejector comprises a third jet port, a third introducing port and a third outlet, wherein the third jet port is communicated with a refrigerant outlet of the first-stage compressor, the third introducing port is communicated with an air suction port of the first-stage compressor, and the third outlet is communicated with an oil tank of the first-stage compressor.
In some embodiments, the bypass branch is provided with a shut-off valve to control the conduction and interception of the bypass branch.
In some embodiments, the refrigeration system further comprises:
The first liquid level detection element is arranged in the oil tank of the first-stage compressor to detect the oil level in the oil tank of the first-stage compressor.
In some embodiments, the refrigeration system further comprises:
And the second liquid level detection element is arranged in the oil tank of the second-stage compressor so as to detect the oil level in the oil tank of the second-stage compressor.
The embodiment of the invention also provides a unit which comprises the refrigerating system provided by any technical scheme of the invention.
The embodiment of the invention also provides a method for regulating the quantity of lubricating oil of the refrigeration system, which comprises the following steps:
introducing all of the lubricant oil remaining in the evaporator of the refrigeration system to the first stage compressor;
And controlling the conduction and interception of a bypass branch between the oil tank of the first-stage compressor and the oil tank of the second-stage compressor according to the oil quantity in the oil tanks of the first-stage compressor and the second-stage compressor.
In some embodiments, the bypass branch is turned on when the amount of oil in the oil tank of the first stage compressor is greater than a first very low value and the amount of oil in the oil tank of the second stage compressor is less than a second very low value.
In some embodiments, the bypass branch is turned on when the amount of oil in the oil tank of the first stage compressor is greater than a first very high value and the amount of oil in the oil tank of the second stage compressor is less than a second very high value.
In some embodiments, the bypass branch is cut when the amount of oil in the oil tank of the first stage compressor is less than a first very low value and the amount of oil in the oil tank of the second stage compressor is greater than a second very low value.
In some embodiments, when the amount of oil in the oil tank of the first stage compressor is less than a first very low value and the amount of oil in the oil tank of the second stage compressor is less than a second very low value, the bypass branch is truncated and at least one of the following operations is performed: and sending out an alarm signal and stopping the machine.
The technical scheme provides a refrigerating system, which comprises a first-stage compressor and a second-stage compressor, wherein the first-stage compressor is a low-pressure-stage compressor, and the second-stage compressor is a high-pressure-stage compressor. The refrigerant system has residual lubricating oil in the circulation process, the refrigerating system utilizes an injection loop to lead the residual lubricating oil in the evaporator back to the first-stage compressor, and a bypass branch is arranged between the first-stage compressor and the second-stage compressor. When the lubricating oil quantity in the second-stage compressor is insufficient, lubricating oil stored in the oil tank of the first-stage compressor is drained into the oil tank of the second-stage compressor through the bypass branch, so that the second-stage compressor is supplemented with lubricating oil. The mode of leading back lubricating oil enables the lubricating oil led back from the refrigerant circulation loop to be directly led to the low-pressure stage compressor, the internal pressure of the low-pressure stage compressor is small, and drainage is easier. Through the bypass branch, lubricating oil in the low-pressure stage compressor can flow to the high-pressure stage compressor, so that the aim of supplementing the lubricating oil for the high-pressure stage compressor is also fulfilled. By adopting the technical scheme, each stage of compressor in the refrigerating system with the two stages of compressors can be effectively lubricated.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the application and do not constitute a limitation on the application. In the drawings:
FIG. 1 is a schematic diagram of a refrigeration system according to some embodiments of the present invention;
FIG. 2 is a schematic cross-sectional view of a first ejector of a refrigeration system according to some embodiments of the present invention;
FIG. 3 is a schematic diagram of a refrigeration system according to further embodiments of the present invention;
fig. 4 is a schematic flow chart of a method for adjusting the amount of lubricating oil in a refrigeration system according to another embodiment of the invention.
Detailed Description
The technical scheme provided by the invention is described in more detail below with reference to fig. 1 to 4.
Referring to fig. 1 and 2, an embodiment of the present invention provides a refrigeration system comprising an evaporator 1, a condenser 2, a first stage compressor 3, a second stage compressor 4, an ejector circuit 5, and a bypass branch 6. The evaporator 1, the condenser 2, the first-stage compressor 3 and the second-stage compressor 4 form a refrigerant circulation circuit.
The evaporator 1 is configured to evaporate a refrigerant. The condenser 2 is configured to condense a refrigerant. The evaporator 1 is in fluid communication with the condenser 2 and the evaporator 1 is located between the condenser 2 and the first stage compressor 3, such that the gas pressure in the condenser 2 is higher, thereby making it possible to utilize the gas pressure in the condenser 2 to inject the lubricating oil remaining in the evaporator 1. The gas pressure of the first stage compressor 3 is lower than the gas pressure in the second stage compressor 4. The second stage compressor 4 is connected to both the first stage compressor 3 and the condenser 2, and the second stage compressor 4 is located between the first stage compressor 3 and the condenser 2. The injection circuit 5 is connected to the evaporator 1, the condenser 2 and the first stage compressor 3, and the injection circuit 5 is configured to inject lubricating oil in the evaporator 1 to the first stage compressor 3. The bypass branch 6 is provided between the first oil tank 31 of the first stage compressor 3 and the second oil tank 41 of the second stage compressor 4, and the bypass branch 6 is configured to be switched between a communication state and an intercepting state.
Referring to fig. 1, the first stage compressor 3 includes a motor 3a, a second stage impeller 3b, and a first stage impeller 3c, which are connected by a shaft. The second stage compressor 4 also includes a motor 4a, a second stage impeller 4b, and a first stage impeller 4c, which are also connected by a shaft.
The cold water/heat pump unit with the double compressors connected in series discharges the gas compressed by the first-stage compressor 3 to the second-stage compressor 4 for compression, so as to improve the pressure ratio and meet the requirement of high-water-temperature water outlet. When the two compressors are operated simultaneously, the refrigerant circulation is as follows: the first-stage compressor 3 compresses the low-temperature low-pressure gaseous refrigerant in the evaporator into a high-temperature high-pressure gaseous refrigerant, and then the high-temperature high-pressure gaseous refrigerant is discharged to the air suction port of the second-stage compressor 4 through the exhaust, and the second-stage compressor 4 further compresses the refrigerant and then discharges the compressed refrigerant to the condenser.
In some embodiments, each oil tank may be designed into the interior of the compressor casting, or a pressure vessel may be independently made as the oil tank.
According to the technical scheme, in the cold water/heat pump unit with the double compressors arranged in series, the current situation that oil return effect difference is large due to the fact that oil tanks of the two compressors are different in pressure is solved, the system for injecting oil return is changed, lubricating oil leaked into the system is completely injected into the first oil tank 31 of the first-stage compressor 3, the supply and distribution of the lubricating oil are realized according to respective lubricating requirements of the two compressors through the bypass branch 6, normal lubrication of bearings of the first-stage compressor 3 and the second-stage compressor 4 is guaranteed, and heat exchange effect, reliability and service life of the unit are improved.
Referring to fig. 1, in some embodiments, the first oil tank 31 is provided with a first oil pump 32, so that oil can be pumped from the first oil tank 31 to the to-be-lubricated part of the first stage compressor 3 normally, and oil in the first oil tank 31 can smoothly flow to the second oil tank 41 when needed.
In some embodiments, the bypass branch 6 comprises a pipe, one end of which communicates with the first tank 31 of the first stage compressor 3 and the other end of which communicates with the second tank 41 of the second stage compressor 4.
Referring to fig. 1 and2, in some embodiments, the ejector circuit 5 includes a first ejector 51. The first ejector 51 includes a first jet port 511, a first introduction port 512, and a first discharge port 513. The first jet port 511 communicates with the refrigerant outlet of the condenser 2, the first introduction port 512 communicates with the evaporator 1, and the first discharge port 513 communicates with the oil tank of the first stage compressor 3. In this technical solution, there is only one ejector, namely: a first ejector 51. The first ejector 51 uses the high-pressure refrigerant pressure at the outlet of the condenser 2 to drain the lubricating oil remaining in the evaporator 1 back into the first oil tank 31 of the first stage compressor 3.
The first jet port 511 is connected with high-pressure gas, and the gas taking port is at the condenser 2. The first inlet 512 is connected to the ejected location, in this system where the oil leaks into the system and eventually resides at the evaporator. The outlet pipe of the first outlet 513 is connected to the final destination of the injection system, i.e. the first tank 31. The first ejector 51 ejects the oil and refrigerant mixture at the low pressure to the medium pressure by using the high pressure gas. In some embodiments, the first eductor 51 is in a refrigeration system connected by a welded copper tube.
In the various embodiments described above, in some embodiments, the bypass branch 6 is provided with a shut-off valve 7 to control the conduction and interception of the bypass branch 6. The shut-off valve 7 is, for example, a solenoid valve, which facilitates the control of the opening and closing of the bypass branch 6.
Referring to fig. 1, in some embodiments, the refrigeration system further includes a first liquid level detection element 8, the first liquid level detection element 8 being disposed in the first tank 31 of the first stage compressor 3 to detect the oil level within the first tank 31 of the first stage compressor 3. The first liquid level detecting element 8 is, for example, a liquid level switch or other sensor, and the amount of oil in the first oil tank 31 of the first stage compressor 3 is determined by the first liquid level detecting element 8. The first liquid level detecting element 8 is a liquid level switch or a liquid level sensor. The liquid level switch can realize that the on-off operation of the relevant valve is carried out when a set value is reached. The liquid level sensor has longer measuring range and higher precision, can detect each liquid level value, can early warn before reaching a set value, and can control the on-off control of the bypass electromagnetic valve, the oil pressure early warning of two oil tanks, the oil pressure alarm, the forced shutdown protection and the like according to the liquid level signal fed back by the liquid level sensor.
Referring to fig. 1, in some embodiments, the refrigeration system further includes a second liquid level detection element 9, the second liquid level detection element 9 being disposed in the second tank 41 of the second stage compressor 4 to detect the oil level within the second tank 41 of the second stage compressor 4. The second liquid level detecting element 9 is, for example, a liquid level switch or other sensor, and the amount of oil in the second tank 41 of the second-stage compressor 4 is determined by the second liquid level detecting element 9. The second liquid level detecting element 9 is a liquid level switch or a liquid level sensor. The liquid level switch can only realize that the on-off operation of the relevant valve is carried out when a set value is reached. The liquid level sensor can detect each liquid level value, early warning can be carried out before the liquid level sensor reaches a set value, the on-off operation of the related valve is carried out after the liquid level sensor reaches the set value, and forced shutdown can be carried out after the liquid level sensor exceeds a certain value.
In some embodiments, in order to prevent the problem of the oil supply pipeline from the first oil tank 31 to the second oil tank 32, pressure sensors are respectively arranged at the high-order oil tanks of the first-stage compressor 3 and the second-stage compressor 4 to detect whether the oil supply pressure is normal. The control logic provided by the pressure value feedback signal has the highest priority, so that the function of timely shutdown protection is achieved.
For the cold water/heat pump unit with the conventional double compressors connected in series, when the cold water/heat pump unit with the conventional double compressors connected in series is operated simultaneously, whether a two-stage injection structure is arranged or not is determined according to the separation degree of oil and refrigerant, but is finally injected to the first oil tank 31 of the first-stage compressor 3. An embodiment of the two stage injection structure is described below.
Referring to fig. 3, this embodiment differs from the embodiment described above in that: the number and the setting positions of the ejectors are different. In other embodiments, the ejector circuit 5 includes a second ejector 52 and a third ejector 53. The second ejector 52 includes a second jet port 521, a second introduction port 522, and a second discharge port 523, the second jet port 521 being in communication with the refrigerant outlet of the condenser 2, the second introduction port 522 being in communication with the evaporator 1, the second discharge port 523 being in communication with the suction port of the first stage compressor 3. The third ejector 53 includes a third jet port 531, a third introduction port 532, and a third discharge port 533, the third jet port 531 being in communication with the refrigerant outlet of the first-stage compressor 3, the third introduction port 532 being in communication with the suction port of the first-stage compressor 3, and the third discharge port 533 being in communication with the oil tank of the first-stage compressor 3. In this technical scheme, there are two ejectors, namely: a second ejector 52 and a third ejector 53. The second ejector 52 uses the pressure of the high-pressure refrigerant at the outlet of the condenser 2 as power to guide the lubricating oil and refrigerant mixture remaining in the evaporator 1 back to the inlet of the first-stage compressor 3. At the inlet of the first stage compressor 3, the refrigerant in the mixed liquid of the lubricating oil and the refrigerant evaporates, thereby realizing the separation of the lubricating oil and the refrigerant. Subsequently, the third ejector 53 uses the high-pressure gas in the volute of the first-stage compressor 3 as power to drain the separated lubricating oil drained back from the second ejector 52 to the first oil tank 31 of the first-stage compressor 3.
Referring to fig. 3, the second jet port 521 of the second ejector 52 is connected with high-pressure gas, and the gas taking port is the gas outlet of the condenser; the second inlet 522 is connected to the ejected portion, specifically, the evaporator where the lubricating oil leaks into the system and finally remains; the second outlet 523 is connected to the destination of the second eductor 52, i.e., the suction port of the first stage compressor 3. The third jet port 531 of the third ejector 53 is connected with high-pressure gas, and the gas taking port is the volute of the first-stage compressor 3; the third inlet 532 is connected with the ejected part, and is the part of the air suction port of the compressor which is finally reserved after primary ejection and separation and purification in the system; the third outlet 533 is connected to the final destination of the third eductor 53, i.e., the first tank 31.
The lubricating oil circulation in the technical scheme is as follows: the first-stage injection injects the mixture of the refrigerant and the oil on the liquid surface of the evaporator to the vicinity of the air suction port of the first-stage compressor 3, the pressure at the position is smaller than that of the air suction port of the second-stage compressor 4, and the refrigerant is easier to evaporate into air to be absorbed by the air suction port, so that the separation effect is achieved. And the separated lubricating oil is ejected back to the first oil tank 31 of the first-stage compressor 3 by the second-stage ejection pipeline, so that the recovery of the lubricating oil leaked into the system is completed, the phenomenon that the high-pressure oil tank is too high in pressure, poor in ejection oil return effect and poor in heat exchange effect, and the heat exchange tube is covered by the lubricating oil due to the long-term retention of the lubricating oil in the evaporator is improved, and the performance of a unit is influenced. And the injection oil only flows to the first oil tank 31, so that the phenomenon that the high-pressure gas brought by the injection oil return of the second oil tank 41 of the second-stage compressor 4 makes the pressure higher, and the lubricating oil after lubricating the bearing is more difficult to flow back to the second oil tank 41 of the second-stage compressor 4 is improved.
The shut-off valve 7, the first liquid level detecting element 8 and the second liquid level detecting element 9 described in the above embodiments are equally applicable to this embodiment, and the same contents are not repeated here.
The embodiment of the invention also provides a unit which comprises the refrigerating system provided by any technical scheme of the invention.
Referring to fig. 3, an embodiment of the present invention further provides a method for adjusting the lubricant amount of a refrigeration system, which may be implemented by using the refrigeration system provided in any of the foregoing embodiments. The method comprises the following steps:
step S100, leading all the residual lubricating oil in the evaporator 1 of the refrigeration system to the first-stage compressor 3;
Step S200, controlling the conduction and interception of the bypass branch 6 between the first oil tank 31 of the first stage compressor 3 and the second oil tank 41 of the second stage compressor 4 according to the oil amount in the first oil tank 31 of the first stage compressor 3 and the second oil tank 41 of the second stage compressor 4.
In some embodiments, the bypass branch 6 is turned on when the amount of oil in the first oil tank 31 of the first stage compressor 3 is greater than a first very low value and the amount of oil in the second oil tank 41 of the second stage compressor 4 is less than a second very low value.
In some embodiments, the bypass branch 6 is conducted when the amount of oil in the first tank 31 of the first stage compressor 3 is greater than a first very high value and the amount of oil in the second tank 41 of the second stage compressor 4 is less than a second very high value.
In some embodiments, the bypass branch 6 is cut when the amount of oil in the first tank 31 of the first stage compressor 3 is less than a first very low value and the amount of oil in the second tank 41 of the second stage compressor 4 is greater than a second very low value.
In some embodiments, when the quantity of oil in the first tank 31 of the first stage compressor 3 is less than a first very low value and the quantity of oil in the second tank 41 of the second stage compressor 4 is less than a second very low value, the bypass branch 6 is truncated and at least one of the following operations is performed: and sending out an alarm signal and stopping the machine.
How the amount of oil in the first tank 31 and the second tank 32 is controlled by controlling the opening and closing of the bypass branch will be described below in connection with a specific embodiment. The total requirement of the lubricating oil of the cold water/heat pump unit with the double compressors arranged in series is set as M, and the total filling amount of the lubricating oil is M, the content of the lubricating oil leaked into the system and the content of the lubricating oil remained in the pipeline and the bearings in the running process of the unit is considered. The lubrication oil requirements of the first stage compressor 3 and the second stage compressor 4 are M1, M2, respectively, where m=m1+m2. It should be noted that the small-sized unit may not consider the content of the lubricating oil leaked into the system and the content of the lubricating oil remained in the pipelines and the bearings; the large-cooling-capacity unit pipeline is large in leakage quantity and low in injection efficiency, and the content of lubricating oil leaked into the system and the content of lubricating oil remained in the pipeline and the bearings need to be considered.
The standard value set by the first oil tank 31 of the first-stage compressor 3 is M1, and the first extremely low value of the first-stage compressor 3 is M1 which is 0.8 times, namely 0.8M1; the first very high value of the first stage compressor 3 is M1, 1.2M1 times 1.2.
The standard value set in the second oil tank 41 of the second-stage compressor 4 is M2. The second stage compressor 4 has a second stage low value of 0.8 times M2, 0.8M2; the second extreme high value of the second stage compressor 4 is 1.2 times M2, 1.2M2.
1. When the oil content a1 of the first oil tank 31 of the first-stage compressor 3 is detected to be equal to or greater than M1 by 0.8 and the oil content a2 of the second oil tank 41 of the second-stage compressor 4 is detected to be equal to or less than M2 by 0.8, the cut-off valve 7 is opened, and lubricating oil at the oil tank of the first-stage compressor 3 is bypassed to the second oil tank 41 of the second-stage compressor 4.
2. When the oil content a1 of the first oil tank 31 of the first stage compressor 3 is detected to be equal to or greater than m1×1.2, and the oil content a2 of the second oil tank 41 of the second stage compressor 4 is detected to be equal to or less than m2×1.2, the cut-off valve 7 is opened, and the lubricating oil at the first oil tank 31 of the first stage compressor 3 is bypassed to the second oil tank 41 side of the second stage compressor 4.
3. When the oil content A1 of the first oil tank 31 of the first-stage compressor 3 is less than or equal to M1 and equal to 0.8, or the oil content of the second oil tank 41 of the second-stage compressor 4 is higher than or equal to A2 and equal to M2 and equal to 0.8, the cut-off valve 7 is closed, and the oil tank lubricating oil of the second-stage compressor 4 is supplemented.
4. If the oil content a2 of the second oil tank 41 of the second stage compressor 4 is detected to be less than or equal to m2×0.8, and the oil content a1 of the first oil tank 31 of the first stage compressor 3 is detected to be less than or equal to m1×0.8, the shut-off valve 7 is not opened, and a corresponding warning or shutdown protection is provided according to the oil pressure low abnormality.
Of course, only one liquid level detecting element may be provided, where the liquid level detecting element is disposed at the second oil tank 41 of the second stage compressor 4, and when the oil content a2.ltoreq.m2×0.8 in the second oil tank 41 of the second stage compressor 4 is detected, the unit itself is disposed at the high-level oil tank pressure sensor of the first stage compressor 3 to detect whether the oil supply pressure detecting signal is normal, if so, the shut-off valve 7 is opened, and the lubricating oil at the first oil tank 31 of the first stage compressor 3 is bypassed to the second oil tank 41 of the second stage compressor 4. When the oil content A2 of the second oil tank 41 of the second stage compressor 4 is equal to or greater than M2 x 1.2, the shut-off valve 7 is closed, and the replenishment of the lubricating oil in the second oil tank 41 of the second stage compressor 4 is completed. As described above, in the opening process of the shut-off valve 7, the oil supply pressure detection signal of the first-stage compressor 3 reports that the oil supply pressure is low, and the corresponding warning or shutdown protection is also reported according to the abnormality of the oil pressure.
According to the above technical solution, according to the relationship between the set oil amount of the first oil tank 31 of the first stage compressor 3 and the set oil amount of the second oil tank 41 of the second stage compressor 4, and the set maximum oil amount and minimum oil amount, it is determined whether to open the shut-off valve 7 in the first oil tank 31 of the first stage compressor 3, so that a part of lubricating oil bypasses the second oil tank 41 of the second stage compressor 4, and the functions of oil level monitoring and oil path bypass control are realized, so that the oil return effect of the oil return system is improved, and the second oil tank 41 of the second stage compressor 4 is ensured to have enough lubricating oil. According to the technical scheme, the problems that the second oil tank 41 of the second-stage compressor 4 is high in pressure and poor in injection oil return effect are solved, and in the running process of equipment, the lubricating oil in the lubricating system of the second-stage compressor 4 can always be ensured to be sufficient, so that the second-stage compressor 4 is sufficiently lubricated and a bearing is not easy to damage; in addition, the lubricating oil quantity is enough, so that the unit can stably and reliably operate.
In the description of the present invention, it should be understood that the terms "center," "longitudinal," "lateral," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, merely to facilitate description of the present invention and simplify the description, and do not indicate or imply that the device or element being referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the protection of the present invention.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may be modified or some technical features may be replaced with others, which may not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims (12)
1. A refrigeration system, comprising:
An evaporator (1) configured to evaporate a refrigerant;
a condenser (2) configured to condense the refrigerant;
-a first stage compressor (3), the evaporator (1) being located between the condenser (2) and the first stage compressor (3);
-a second stage compressor (4), the gas pressure of the first stage compressor (3) being lower than the gas pressure inside the second stage compressor (4); the second-stage compressor (4) is connected with the first-stage compressor (3) and the condenser (2), and the second-stage compressor (4) is positioned between the first-stage compressor (3) and the condenser (2);
an injection loop (5) connected to the evaporator (1), the condenser (2) and the first stage compressor (3), the injection loop (5) being configured to inject lubricating oil in the evaporator (1) to the first stage compressor (3); and
A bypass branch (6) disposed between a first oil tank (31) of the first stage compressor (3) and a second oil tank (41) of the second stage compressor (4), the bypass branch (6) being configured to switch between a connected state and an interrupted state;
Wherein the first-stage compressor (3) is a low-pressure-stage compressor, and the second-stage compressor (4) is a high-pressure-stage compressor; when the amount of lubricating oil in the second-stage compressor (4) is insufficient, lubricating oil stored in a first oil tank (31) of the first-stage compressor (3) is drained into a second oil tank (41) of the second-stage compressor (4) through the bypass branch (6), so that the second-stage compressor (4) is supplemented with lubricating oil.
2. A refrigeration system according to claim 1, wherein the ejector circuit (5) comprises:
The first ejector (51) comprises a first jet port (511), a first introducing port (512) and a first outlet (513), wherein the first jet port (511) is communicated with a refrigerant outlet of the condenser (2), the first introducing port (512) is communicated with the evaporator (1), and the first outlet (513) is communicated with an oil tank of the first-stage compressor (3).
3. A refrigeration system according to claim 1, wherein the ejector circuit (5) comprises:
A second ejector (52) including a second jet port (521), a second introduction port (522), and a second discharge port (523), wherein the second jet port (521) communicates with a refrigerant outlet of the condenser (2), the second introduction port (522) communicates with the evaporator (1), and the second discharge port (523) communicates with an intake port of the first-stage compressor (3); and
The third ejector (53) comprises a third jet port (531), a third introducing port (532) and a third outlet (533), wherein the third jet port (531) is communicated with a refrigerant outlet of the first-stage compressor (3), the third introducing port (532) is communicated with an air suction port of the first-stage compressor (3), and the third outlet (533) is communicated with an oil tank of the first-stage compressor (3).
4. A refrigeration system according to any one of claims 1 to 3, wherein the bypass branch (6) is provided with a shut-off valve (7) to control the conduction and interception of the bypass branch (6).
5. A refrigeration system according to any one of claims 1 to 3 further comprising:
The first liquid level detection element (8) is arranged in the oil tank of the first-stage compressor (3) so as to detect the oil level in the oil tank of the first-stage compressor (3).
6. A refrigeration system according to any one of claims 1 to 3 further comprising:
And a second liquid level detection element (9) which is arranged in the oil tank of the second-stage compressor (4) so as to detect the oil level in the oil tank of the second-stage compressor (4).
7. A unit comprising a refrigeration system according to any one of claims 1 to 6.
8. The method for regulating the quantity of lubricating oil of the refrigerating system is characterized by comprising the following steps of:
introducing all of the lubricant oil remaining in the evaporator of the refrigeration system to the first stage compressor; wherein the refrigeration system is the refrigeration system of any one of claims 1 to 6;
And controlling the conduction and interception of a bypass branch between the first oil tank of the first-stage compressor and the second oil tank of the second-stage compressor according to the oil quantity in the oil tanks of the first-stage compressor and the second-stage compressor.
9. The method of adjusting a lubricant level of a refrigeration system according to claim 8, wherein said bypass branch is conducted when a first amount of oil in a first tank of said first stage compressor is greater than a first very low value and a second amount of oil in a second tank of said second stage compressor is less than a second very low value.
10. The method of claim 9, wherein the bypass branch is conducted when the amount of oil in the first tank of the first stage compressor is greater than a first very high value and the amount of oil in the second tank of the second stage compressor is less than a second very high value.
11. The method of claim 9, wherein the bypass branch is cut when the amount of oil in the first tank of the first stage compressor is less than a first very low value and the amount of oil in the second tank of the second stage compressor is greater than a second very low value.
12. The method of claim 9, wherein when the amount of oil in the first tank of the first stage compressor is less than a first very low value and the amount of oil in the second tank of the second stage compressor is less than a second very low value, the bypass branch is cut and at least one of the following operations is performed: and sending out an alarm signal and stopping the machine.
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