A lubricating oil recovery system for a refrigeration unit

Abstract

The utility model discloses a kind of lubricating oil recovery systems for refrigerating unit, it is related to refrigeration technical field, including column tube heat exchanger, column tube heat exchanger shell side entrance is connected with the compressor outlet end of refrigerating unit by pipeline one, column tube heat exchanger shell side export is connected with the compressor inlet end of refrigerating unit by pipeline two, still include oil collector, oil buffer tank, heating column tube, first remote liquid level meter, second remote liquid level meter, remote pressure gauge and remote cut-off valve, the utility model can remote operation under the condition of guaranteeing process system not to stop, after separating, recycling and using lubricating oil accumulated in column tube heat exchanger, guarantee the condensation effect of process medium, improve the stability and economic benefit of system.

Description

Technical Field

[0001] This utility model relates to the field of refrigeration technology, specifically to a lubricating oil recovery system for refrigeration units. Background Technology

[0002] In the field of refrigeration technology, during long-term operation of refrigeration units, the refrigerant gas discharged from the compressor often carries lubricating oil into the system circulation. If this lubricating oil accumulates in core heat exchange components such as shell-and-tube heat exchangers for a long time, it will form an oil film on the surface of the heat exchange tubes, significantly reducing the heat exchange efficiency between the refrigerant and the process medium. This leads to a decrease in cooling capacity, an increase in energy consumption, and may even cause compressor wear due to insufficient lubrication, seriously affecting the operational stability and service life of the refrigeration unit. Therefore, how to efficiently recover and recycle the lubricating oil in the refrigeration system, while avoiding interference with the normal operation of the system during the recovery process, has become a key problem that urgently needs to be solved in the industry.

[0003] In the prior art, relevant research has been carried out on the separation and recovery of refrigerant and lubricating oil. For example, a refrigerant purification and recovery device and refrigerant purification system with patent number CN114183951B achieves preliminary separation of refrigerant and lubricating oil through a filter screen in the purification device. It constructs a circulation loop with a two-stage heat exchanger, a throttling device and a compressor. It uses the principles of vapor compression refrigeration and distillation purification to perform multiple heat exchanges and purifications on the refrigerant. Finally, the separated lubricating oil is discharged through the oil drain port, realizing the purification and recovery of refrigerant. While this technology can effectively filter impurities such as lubricating oil from refrigerants and improve refrigerant purity, it still has certain limitations: its core design focuses on the purification and recovery of refrigerants, with lubricating oil only being separated and discharged as an impurity. There is no specific design for the recycling of lubricating oil, and the recovered lubricating oil cannot be directly returned to the compressor of the refrigeration unit for secondary use. Furthermore, the operation of this device relies on the collaboration of multiple devices, requiring multiple compression and heat exchange cycles of the refrigerant, making the process relatively complex. It also does not explicitly address how to complete the lubricating oil recovery operation without stopping the refrigeration unit. If applied to a continuous production refrigeration system, production may be interrupted due to device start-up, shutdown, or switching, affecting process continuity. Utility Model Content

[0004] The purpose of this invention is to provide a lubricating oil recovery system for refrigeration units, which aims to solve the problems in the background art where lubricating oil cannot be recycled and the shutdown of the unit will affect the continuity of the process.

[0005] To achieve the above objectives, this utility model adopts the following technical solution: a lubricating oil recovery system for a refrigeration unit, comprising a shell-and-tube heat exchanger, wherein the shell-side inlet of the shell-and-tube heat exchanger is connected to the compressor outlet of the refrigeration unit via a first pipeline, and the shell-side outlet of the shell-and-tube heat exchanger is connected to the compressor inlet of the refrigeration unit via a second pipeline. The system also includes an oil collector, an oil buffer tank, heated tubes, a first remote level gauge, a second remote level gauge, a remote pressure gauge, and a remote shut-off valve. The interface at two-thirds of the shell side of the shell-and-tube heat exchanger is connected to the oil collector via a third pipeline, and the top of the oil collector is connected to the tubes via a fourth pipeline. The shell-side top of the heat exchanger is connected, and the bottom of the oil receiver is connected to the oil buffer tank via pipe five. The oil buffer tank is connected to the compressor of the refrigeration unit via a lubricating oil circuit. The heating tubes are located inside the oil receiver. The first remote level gauge is located on the shell-and-tube heat exchanger, and the second remote level gauge and the remote pressure gauge are both located on the oil receiver. Remote shut-off valves are provided on pipes one, three, four, and five, the lubricating oil circuit, and the inlet and outlet ends of the heating tubes. The first remote level gauge, the second remote level gauge, the remote pressure gauge, and the remote shut-off valve are all electrically connected to the DCS automatic control system.

[0006] This utility model has the following beneficial effects: This invention provides a lubricating oil recovery system for refrigeration units, which can be operated remotely without stopping the process system. It separates and recovers the lubricating oil accumulated in the shell and tube heat exchanger, ensuring the condensation effect of the process medium and improving the stability and economic benefits of the system. Attached Figure Description

[0007] Figure 1 This is a schematic diagram of the overall structure of this utility model; In the diagram: 1. Shell and tube heat exchanger; 2. Pipeline 1; 3. Pipeline 2; 4. Oil collector; 5. Oil buffer tank; 6. Heating tubes; 7. First remote level gauge; 8. Second remote level gauge; 9. Remote pressure gauge; 10. Remote shut-off valve; 11. Pipeline 3; 12. Pipeline 4; 13. Pipeline 5; 14. Lubricating oil circuit. Detailed Implementation

[0008] like Figure 1As shown, a lubricating oil recovery system for a refrigeration unit includes a shell-and-tube heat exchanger 1. The shell-side inlet of the shell-and-tube heat exchanger 1 is connected to the compressor outlet of the refrigeration unit via a DN80 pipe 2, and the shell-side outlet of the shell-and-tube heat exchanger 1 is connected to the compressor inlet of the refrigeration unit via a DN80 pipe 3. The system also includes an oil collector 4, an oil buffer tank 5, heated tubes 6, a first remote level gauge 7, a second remote level gauge 8, a remote pressure gauge 9, and a remote shut-off valve 10. The interface at two-thirds of the shell side of the shell-and-tube heat exchanger 1 is connected via a DN40 pipe. Pipeline 3.11 connects to the oil collector 4. The top of the oil collector 4 is connected to the top of the shell side of the shell-and-tube heat exchanger 1 via DN40 pipe 4. The bottom of the oil collector 4 is connected to the oil buffer tank 5 via DN40 pipe 5. The oil buffer tank 5 is connected to the compressor of the refrigeration unit via DN32 lubricating oil circuit 14. The heating tubes 6 are located inside the oil collector 4, and their inlet and outlet ends are connected to the steam condensate system via DN25 pipes. The pressure is stable at 0.4 MPa and the temperature is 150℃, providing continuous steam supply. The first remote level gauge 7 is installed on the shell-and-tube heat exchanger 1, and the second remote level gauge 8 and the remote pressure gauge 9 are both installed on the oil receiver 4. The remote pressure gauge 9 monitors the gas phase pressure inside the oil receiver 4 in real time to prevent overpressure risks. Remote shut-off valves 10 are installed on pipeline 1 2, pipeline 3 11, pipeline 4 12, pipeline 5 13, lubricating oil circuit 14, and the inlet and outlet ends of the heating tube 6.

[0009] The first remote level gauge 7, the second remote level gauge 8, the remote pressure gauge 9, and the remote shut-off valve 10 are respectively connected to the DCS automatic control system via telecommunications.

[0010] The specific operation process of this utility model is as follows: When the process system operates continuously for 240 hours, the DCS system increases the opening of the remote shut-off valve 10 on pipeline 1-2, thereby increasing the flow rate of refrigerant gas R507. This ensures an increase in the flow velocity of the gas-liquid mixture in the shell side of the tubular heat exchanger 1, driving the accumulated lubricating oil to flow. Simultaneously, the remote shut-off valves 10 on pipelines 3-11 and 4-12 are opened, establishing a gas-liquid flow channel between the tubular heat exchanger 1 and the oil collector 4. The DCS system remotely monitors the liquid level in the shell side of the tubular heat exchanger 1 in real time through the first remote level gauge 7, stabilizing the liquid level at two-thirds of the full capacity for 10 minutes. During this period, the lubricating oil in the shell side of the tubular heat exchanger 1... The lubricating oil enters the oil collector 4 along with the refrigerant. After 10 minutes, the remote shut-off valve 10 on pipe 311 is closed, and the remote shut-off valve 10 on the inlet and outlet of the heating tube 6 is opened. Steam condensate enters the oil collector 4 and begins to heat the interior of the oil collector 4. During this process, the liquid refrigerant R507 evaporates into a gaseous phase. The gaseous R507 flows back to the gas phase space at the top of the shell side of the tube heat exchanger 1 through pipe 412 and rejoins the refrigeration cycle. The lubricating oil, because its boiling point is much higher than that of R507, remains at the bottom of the oil collector 4. When the DCS system detects that the liquid level of the second remote level gauge 8 does not change, it determines that the liquid R507 in the oil collector 4 is present. The refrigerant R507 in the oil collector 4 has completely evaporated. The remote shut-off valve 10 on the inlet and outlet of the heating tube 6 is closed to stop the supply of steam condensate for heating. The remote shut-off valve 10 on pipeline 5 13 and lubricating oil circuit 14 is opened, and the lubricating oil enters the oil buffer tank 5. When the DCS remotely detects that the level of the second remote level gauge 8 does not change, the remote shut-off valve 10 on pipeline 4 12 and pipeline 5 13 is closed, and the remote shut-off valve 10 on lubricating oil circuit 14 is opened, and the lubricating oil returns to the refrigeration unit for reuse.

Claims

1. A lubricating oil recovery system for a refrigeration unit, comprising a shell-and-tube heat exchanger (1), wherein the shell-side inlet of the shell-and-tube heat exchanger (1) is connected to the compressor outlet of the refrigeration unit via a first pipe (2), and the shell-side outlet of the shell-and-tube heat exchanger (1) is connected to the compressor inlet of the refrigeration unit via a second pipe (3), characterized in that: It also includes an oil collector (4), an oil buffer tank (5), heated tubes (6), a first remote level gauge (7), a second remote level gauge (8), a remote pressure gauge (9), and a remote shut-off valve (10). The interface at two-thirds of the shell side of the tube heat exchanger (1) is connected to the oil collector (4) via pipe three (11). The top of the oil collector (4) is connected to the top of the shell side of the tube heat exchanger (1) via pipe four (12). The bottom of the oil collector (4) is connected to the oil buffer tank (5) via pipe five (13). The oil buffer tank (5) is connected to the compressor of the refrigeration unit via a lubricating oil circuit (14). The heating tube (6) is located inside the oil receiver (4). The first remote level gauge (7) is located on the tube heat exchanger (1). The second remote level gauge (8) and the remote pressure gauge (9) are both located on the oil receiver (4). The first pipeline (2), the third pipeline (11), the fourth pipeline (12), the fifth pipeline (13), the lubricating oil circuit (14), and the inlet and outlet of the heating tube (6) are all equipped with remote shut-off valves (10). The first remote level gauge (7), the second remote level gauge (8), the remote pressure gauge (9), and the remote shut-off valve (10) are respectively connected to the DCS automatic control system.

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