Long-pipe full-liquid refrigeration system oil return device

Abstract

The utility model relates to screw compressor refrigeration system technical field discloses a long pipeline flooded refrigeration system oil return device, including compressor, oil separator, oil cooler, condenser, liquid accumulator, economizer, oil collector, flooded evaporator, oil return device and gas -liquid separator etc. Compared with prior art, the utility model three times oil return is carried out to fluorine oil mixture in refrigeration system, realizes the process of long pipeline flooded refrigeration system oil return, thereby separates and removes the refrigeration oil taken away with refrigerant in system, and hot siphon returns compressor circulation use, solves the problem of quick oil level drop after refrigerating unit start, oil return difficulty, compressor oil pressure too low and shutdown.

Description

Technical Field

[0001] This utility model relates to the technical field of screw compressor refrigeration systems, and in particular to an oil return device for a long-pipeline flooded refrigeration system. Background Technology

[0002] Screw compressors require refrigerant oil to seal the rotor for high-efficiency compression and to lubricate the bearings, thus involving oil return and oil-refrigerant separation. In flooded screw compressor refrigeration units, even with an effective oil separator, a small amount of oil inevitably enters the evaporator along with the condenser. When the oil level in the evaporator exceeds that in the compressor, the unit will malfunction or even shut down after a period of operation due to the low oil level in the compressor. Therefore, safe and reliable oil return technology is essential to ensure the normal operation of the unit.

[0003] Currently, there are two main methods for oil return in refrigeration unit compressors: oil return via an oil separator and oil return via a return pipe. It's not uncommon for refrigeration systems with particularly long piping, flooded refrigeration systems, and freeze-drying equipment operating at very low temperatures to experience no oil return or very little oil return for tens of minutes after startup. Poor oil return in refrigeration unit compressors leads to a large amount of lubricating oil remaining in the evaporator pipes. When the oil film increases to a certain level, it directly affects system cooling. Furthermore, the machine cannot operate without oil, requiring continuous replenishment of lubricating oil, which causes lubricating oil to accumulate in the system, creating a vicious cycle, increasing operating costs, and reducing operational reliability. Utility Model Content

[0004] To solve the above-mentioned technical problems, this utility model provides an oil return device for a long-pipeline flooded refrigeration system, in which the fluorinated oil mixture undergoes three oil return cycles in the refrigeration system to ensure the normal operation of the system.

[0005] To achieve this technical objective, the present invention adopts the following solution: This utility model provides an oil return device for a long-pipeline flooded refrigeration system, including a compressor, an oil separator, and an oil cooler. The compressor is connected to the oil separator through the oil separator's inlet pipe, the oil separator is connected to the oil cooler through the oil separator's outlet pipe, and the oil cooler is connected to the compressor through the oil cooler's return pipe. The oil separator is connected to the condenser through the oil separator outlet pipe. The condenser is connected to the liquid receiver through the condenser bottom pipe. The liquid receiver is connected to the economizer through the economizer inlet pipe. The economizer is connected to the compressor through the economizer outlet pipe. The economizer is connected to an oil collector via the lower liquid pipe of the economizer. The oil collector is connected to a flooded evaporator via the liquid inlet pipe of the evaporator. The flooded evaporator is connected to a gas-liquid separator via the evaporator exhaust pipe. The gas-liquid separator is connected to the compressor via a return gas pipe. The gas-liquid separator is connected to an oil return device via an oil outlet pipe of the gas-liquid separator. The flooded evaporator is connected to the oil collector via the evaporator drain pipe. The oil collector is connected to the oil return device via a descending oil return pipe. The oil return device is connected to the gas return pipe via the oil return pipe.

[0006] Furthermore, both the oil cooler and the condenser are shell-and-tube heat exchangers.

[0007] Furthermore, a balance pipe is installed between the condenser and the receiver.

[0008] Furthermore, the economizer is a shell-and-tube heat exchanger, with a first connecting pipe between the tube side and the shell side.

[0009] Furthermore, a second connecting pipe is provided between the gas-liquid separator and the oil return device.

[0010] Furthermore, a pressure regulating pipe is installed between the gas-liquid separator and the condenser.

[0011] Furthermore, a pressure boosting pipe is installed between the condenser and the oil return device.

[0012] Compared with the prior art, the beneficial effects of this utility model are as follows: In this invention, the fluorinated oil mixture undergoes three oil return processes in the oil return device, resulting in a more thorough oil return and achieving efficient oil return for long-pipeline refrigeration units. The first oil return process utilizes an oil separator. The fluorinated oil mixture is separated by the oil separator, and the refrigerant oil is then cooled by an oil cooler before returning to the compressor. The oil separator can separate over 95% of the excess oil, ensuring excellent oil return and preventing large amounts of oil from entering the condenser and flooded evaporator, thus reducing the unit's heat exchange efficiency. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the oil return device of the long pipeline full-fill refrigeration system in this embodiment of the present invention.

[0014] The following are labeled in the diagram: 1. Compressor; 2. Oil separator inlet pipe; 3. Oil separator; 4. Oil separator outlet pipe; 5. Oil cooler; 6. Oil cooler return pipe; 7. Oil separator outlet pipe; 8. Condenser; 9. Condenser lower liquid pipe; 10. Balance pipe; 11. Liquid receiver; 12. Economizer inlet pipe; 13. Economizer; 14. Economizer lower liquid pipe; 15. Oil collector; 16. Evaporator inlet pipe; 17. Flooded evaporator; 18. Evaporator oil drain pipe; 19. Downward oil return pipe; 20. Oil return device; 21. Evaporator exhaust pipe; 22. Gas-liquid separator; 23. Gas-liquid separator outlet pipe; 24. Pressure regulating pipe; 25. Gas return pipe; 26. Oil return pipe; 27. Economizer outlet pipe; 28. First connecting pipe; 29. ​​Booster pipe; 30. Second connecting pipe. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solutions in the embodiments of this utility model will be clearly and completely described below in conjunction with the embodiments of this utility model. Obviously, the described embodiments are some embodiments of this utility model, but not all embodiments.

[0016] Please see Figure 1 This utility model provides an oil return device for a long pipeline flooded refrigeration system, including a compressor 1, an oil separator 3, an oil cooler 5, a condenser 8, a liquid receiver 11, an economizer 13, an oil collector 15, a flooded evaporator 17, an oil return device 20, and a gas-liquid separator 22.

[0017] Compressor 1 is connected to oil separator 3 through oil separator inlet pipe 2. Oil separator 3 is connected to oil cooler 5 through oil separator outlet pipe 4. Oil cooler 5 is connected to compressor 1 through oil cooler return pipe 6.

[0018] Oil separator 3 is connected to condenser 8 via oil separator outlet pipe 7. Condenser 8 is connected to liquid receiver 11 via condenser bottom liquid pipe 9. Liquid receiver 11 is connected to economizer 13 via economizer inlet pipe 12. Economizer 13 is connected to compressor 1 via economizer outlet pipe 27. Economizer 13 is connected to oil collector 15 via economizer bottom liquid pipe 14. Oil collector 15 is connected to flooded evaporator 17 via evaporator inlet pipe 16. Flooded evaporator 17 is connected to gas-liquid separator 22 via evaporator exhaust pipe 21. Gas-liquid separator 22 is connected to compressor 1 via return gas pipe 25. Gas-liquid separator 22 is connected to oil return device 20 via gas-liquid separator oil outlet pipe 23. Flooded evaporator 17 is connected to oil collector 15 via evaporator oil drain pipe 18. Oil collector 15 is connected to oil return device 20 via descending return oil pipe 19. Oil return device 20 is connected to return gas pipe 25 via return oil pipe 26.

[0019] Among them, the oil separator 3 is installed on the exhaust pipe of the compressor 1. The oil separator 3 uses a high-efficiency filter element, which can generally separate more than 95% of the oil (lubricating oil carried away by the refrigerant). It has a good oil return effect and fast speed, which greatly reduces the amount of oil entering the system pipeline, thereby effectively extending the oil-free operation time.

[0020] The oil cooler 5 is a shell-and-tube heat exchanger, and the heat exchange tubes are made of TP2 (copper). The refrigeration oil separated by the oil separator 3 needs to be cooled by the oil cooler 5 to reach the temperature required by the compressor 1 before it can be reused.

[0021] Condenser 8 is a shell-and-tube heat exchanger with TP2 heat exchange tubes, which condenses refrigerant gas containing a small amount of oil into liquid.

[0022] The receiver 11 is used to regulate and stabilize the refrigerant circulation rate in the refrigeration system when the operating conditions change. It prevents excessive condensate buildup in the condenser 8, which would reduce the heat transfer area and affect the heat transfer efficiency of the condenser 8. It adapts to the supply demand caused by load changes in the flooded evaporator 17. When the evaporation load increases, the supply also increases, replenished by the liquid stored in the receiver 11; when the load decreases, the required liquid volume also decreases, and excess liquid is stored in the receiver 11. It also provides some noise reduction and filtration, and prevents liquid slugging on the compressor 1.

[0023] Economizer 13 is a shell-and-tube heat exchanger with carbon steel heat exchange tubes. A first connecting pipe 28 is installed between the tube side and the shell side of economizer 13. The low-temperature, high-pressure liquid from receiver 11 is divided into two paths. One path is throttled to become a low-temperature, low-pressure liquid and enters the tube side, where it exchanges heat with the high-pressure liquid entering the shell side. The gas evaporated in the tube side enters the gas inlet, while the other high-pressure liquid in the shell side is cooled, increasing the subcooling of the liquid entering the evaporator throttling valve, thereby greatly improving the unit's cooling capacity and coefficient of performance (COP).

[0024] The flooded evaporator 17 is a shell-and-tube heat exchanger with carbon steel heat exchange tubes. In the entire system, the flooded evaporator 17 is generally the area with relatively low pressure and temperature, where the refrigerant oil viscosity is highest, leading to difficulties in oil return. If too much refrigerant oil remains in the flooded evaporator 17 and other areas, it will severely hinder heat exchange and significantly affect the normal operation of the equipment, potentially even burning out the compressor 1. The oil and liquid refrigerant mixture forms an oil-rich layer on the surface of the flooded evaporator 17. By finding suitable locations and using three oil return holes at different liquid levels, the oil is drawn from this rich oil layer, improving the oil return efficiency in the flooded evaporator 17.

[0025] The oil collector 15 is positioned lower than the flooded evaporator 17. The oil-rich liquid refrigerant is drawn from the flooded evaporator 17 and flows into the oil collector 15, where it exchanges heat with the high-temperature liquid refrigerant in the economizer 13. This helps to increase the cooling capacity of the chiller unit and also helps the liquid refrigerant evaporate into a gaseous state before entering the compressor 1. This step is a thermosiphon oil return method.

[0026] The descending oil return pipe 19 connects the oil collector 15 to the oil return device 20 near the compressor 1, and uses the gravity of the refrigeration oil and the principle of thermosiphon to solve the problem of difficult oil return in long pipelines.

[0027] The gas-liquid separator 22 is one of the most critical components affecting oil return, located between the return port of the flooded evaporator 17 and the compressor 1. When liquid refrigerant enters the gas-liquid separator 22, its expansion velocity decreases, causing the liquid to separate or hit a baffle, thus separating the liquid. During the separation of liquid refrigerant, refrigeration oil is also separated and accumulates at the bottom of the gas-liquid separator 22. There is an oil hole at the outlet pipe and bottom of the gas-liquid separator 22 to ensure that the refrigeration oil can return to the compressor 1, thereby preventing the compressor 1 from running out of oil. At the same time, it can temporarily store excess liquid refrigerant to prevent excess refrigerant from flowing into the compressor 1 and diluting the lubricating oil.

[0028] The oil return device 20 uses capillary tubes, communicating vessels, and nozzles to draw refrigerant oil from the low-pressure side of the compressor 1 and return it to the high-pressure side, thus realizing the recycling and reuse of refrigerant oil. The oil return volume is controlled according to the vibration and noise conditions of the compressor 1, so as to increase the oil supply in time when abnormal vibration or noise occurs, thereby maintaining the stable operation of the compressor 1 and preventing damage.

[0029] Furthermore, a balance pipe 10 is installed between the condenser 8 and the liquid receiver 11 to regulate and stabilize the refrigerant circulation volume in the system when the refrigeration system operating conditions change. A second connecting pipe 30 is installed between the gas-liquid separator 22 and the oil return device 20, a pressure regulating pipe 24 is installed between the gas-liquid separator 22 and the condenser 8, and a pressure boosting pipe 29 is installed between the condenser 8 and the oil return device 20 to ensure stable system operation.

[0030] The working process of the oil return device in the long-pipeline flooded refrigeration system of this utility model is as follows: The refrigerant-oil mixture in compressor 1 enters oil separator 3 through oil separator inlet pipe 2 for separation. It has a built-in gas-liquid filter and a pleated microporous filter element, which can generally separate more than 95% of the refrigerant. The refrigerant oil at the bottom of oil separator 3 enters oil cooler 5 through oil separator outlet pipe 4 for cooling, and then returns to compressor 1 through oil cooler return pipe 6, completing one oil return cycle.

[0031] The gas separated by the oil separator 3 enters the condenser 8 through the oil separator outlet pipe 7 and is condensed. The low-temperature liquid refrigerant enters the liquid receiver 11 through the condenser bottom liquid pipe 9. A balance pipe 10 is provided between the condenser 8 and the liquid receiver 11 to adjust and stabilize the circulation of refrigerant in the system when the operating conditions of the refrigeration system change. The liquid outlet of the receiver 11 is connected to the inlet pipe 12 of the economizer, allowing liquid refrigerant to enter the economizer 13. Gaseous refrigerant returns to the compressor 1 via the economizer outlet pipe 27. Liquid refrigerant then enters the oil collector 15 via the lower liquid pipe 14 of the economizer, cooling the refrigerant-oil mixture within. It then enters the flooded evaporator 17 via the evaporator inlet pipe 16. After flashing within the flooded evaporator 17, the gaseous refrigerant enters the gas-liquid separator 22 via the evaporator exhaust pipe 21. Residual refrigerant oil in the refrigerant enters the oil collector 15 via the evaporator oil drain pipe 18. The flooded evaporator 17 uses three oil return holes at three liquid levels to ensure sufficient oil return. The refrigerant oil stored in the oil collector 15 then enters the oil return unit 20 via the descending oil return pipe 19. The oil return unit 20 is connected to the gas return pipe 25 via the oil return pipe 26, which in turn connects to the compressor 1. Secondary oil return is achieved through a siphon effect.

[0032] The gaseous refrigerant separated from the flooded evaporator 17 enters the gas-liquid separator 22 for further separation. The separated refrigeration oil enters the oil return unit 20 through the oil outlet pipe 23 of the gas-liquid separator, and then returns to the compressor 1 through the oil return pipe 26 and the gas return pipe 25 in sequence, completing three oil returns.

[0033] After the implementation of this utility model oil return device for long-pipeline flooded refrigeration systems, the problem of difficult oil return in long-pipeline flooded refrigeration systems is effectively solved, and the annual profit can reach 230,000 yuan.

[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features. If these modifications and variations fall within the scope of the claims of this utility model and their equivalents, they should be considered to be within the protection scope of this utility model.

Claims

1. An oil return device for a long-pipeline flooded refrigeration system, comprising a compressor (1), an oil separator (3), and an oil cooler (5), characterized in that, The compressor (1) is connected to the oil separator (3) through the oil separator inlet pipe (2), the oil separator (3) is connected to the oil cooler (5) through the oil separator outlet pipe (4), and the oil cooler (5) is connected to the compressor (1) through the oil cooler return pipe (6). The oil separator (3) is connected to the condenser (8) through the oil separator outlet pipe (7). The condenser (8) is connected to the liquid receiver (11) through the liquid receiver outlet pipe (9). The liquid receiver (11) is connected to the economizer (13) through the economizer inlet pipe (12). The economizer (13) is connected to the compressor (1) through the economizer outlet pipe (27). The economizer (13) is connected to the oil collector (15) through the lower liquid pipe (14) of the economizer. The oil collector (15) is connected to the flooded evaporator (17) through the liquid inlet pipe (16) of the evaporator. The flooded evaporator (17) is connected to the gas-liquid separator (22) through the evaporator exhaust pipe (21). The gas-liquid separator (22) is connected to the compressor (1) through the return gas pipe (25). The gas-liquid separator (22) is connected to the return oil device (20) through the oil outlet pipe (23) of the gas-liquid separator. The flooded evaporator (17) is connected to the oil collector (15) through the evaporator drain pipe (18). The oil collector (15) is connected to the oil return device (20) through the descending oil return pipe (19). The oil return device (20) is connected to the gas return pipe (25) through the oil return pipe (26).

2. The oil return device for a long-pipeline flooded refrigeration system according to claim 1, characterized in that, Both the oil cooler (5) and the condenser (8) are shell-and-tube heat exchangers.

3. The oil return device for a long-pipeline flooded refrigeration system according to claim 1, characterized in that, A balance pipe (10) is provided between the condenser (8) and the liquid receiver (11).

4. The oil return device for a long-pipeline flooded refrigeration system according to claim 1, characterized in that, The economizer (13) is a shell-and-tube heat exchanger with a first connecting pipe (28) between the tube side and the shell side.

5. The oil return device for a long-pipeline flooded refrigeration system according to claim 1, characterized in that, A second connecting pipe (30) is provided between the gas-liquid separator (22) and the oil return device (20).

6. The oil return device for a long-pipeline flooded refrigeration system according to claim 1, characterized in that, A pressure regulating pipe (24) is provided between the gas-liquid separator (22) and the condenser (8).

7. The oil return device for a long-pipeline flooded refrigeration system according to claim 1, characterized in that, A booster pipe (29) is provided between the condenser (8) and the oil return device (20).

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