Control method of compressor unit

Abstract

A control method of a compressor unit belongs to the technical field of compressors. Carbon dioxide is compressed by a compressor unit and then is reinjected into a well, the compressor unit comprises at least two stages of compressors which are connected in series, and an electric emptying valve is arranged at an air inlet of the compressor unit; the air inlet pressure of the compressor unit is controlled as follows: the lowest total air inlet pressure threshold P1 and the highest total air inlet pressure threshold P2 of the compressor unit are set, and when the air inlet pressure is lower than P1, the compressor unit is in a standby state; when the air inlet pressure is higher than P2, the outlet pressure is lower than P3, and the compressor is overloaded, the compressor keeps working at 100% speed, and when the compressor is overloaded, the electric emptying valve is opened, part of carbon dioxide is emptied, the air inlet pressure is kept between P1 and P2, the compressor unit is shut down when the exhaust pressure is higher than P3, and part of carbon dioxide is emptied through the electric emptying valve; damage of compressor parts caused by high-pressure gas is avoided, and normal and stable work of the compressor is guaranteed.

Description

Technical Field

[0001] The invention discloses a control method for a compressor unit, belonging to the technical field of compressors. Background Art

[0002] When carbon dioxide is used to drive oil in oil wells, liquid or high-pressure carbon dioxide squeezes out the oil or gas in the underground cracks. The carbon dioxide that completes the oil drive will be discharged together with the produced gas. This part of the carbon dioxide needs to be compressed and sent back into the well. Chinese invention patent CN117345177A discloses an oil field associated gas and carbon dioxide mixed state boosting system and its reinjection oil drive method. The gas source pipeline is connected to the gas source mixer, and the gas source mixer is connected to the synchronous rotary integrated boosting device through the air intake pipeline. The synchronous rotary integrated boosting device is connected to the gas injection well through the reinjection pipeline. The present invention can realize the cyclic reinjection of carbon dioxide-rich associated gas and pipeline gas at the wellhead, avoids the problems of handling the liquid precipitated by the separation and sedimentation of the intake air and the interstage cooling, eliminates the risk of liquid hammer, has no wearing parts, saves construction costs, and has the advantages of safety, reliability, low cost, flexibility and convenience; at the same time, it also avoids excessive reinjection gas pressure and takes into account the oil drive effect of the remote well group of the gas injection well.

[0003] However, in the process of compressing and reinjecting the separated carbon dioxide, the pressure of the carbon dioxide is not stable, which will cause the compressor to fail to work normally, affecting the normal carbon dioxide reinjection and reducing the life of the compressor. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a control method for a compressor unit, which can ensure the normal operation of the compressor, ensure the stable reinjection of carbon dioxide, and increase the service life of the compressor.

[0005] The technical solution adopted by the present invention to solve the technical problem is: the control method of the compressor unit, using the compressor unit to compress carbon dioxide and then inject it back into the well, characterized in that: the compressor unit includes at least two stages of compressors connected in series, and an electric vent valve is provided at the air inlet of the compressor unit; The electric vent valve is an electric ball valve.

[0006] Set the minimum total intake pressure threshold value P1, the maximum total intake pressure threshold value P2 and the maximum outlet pressure threshold value P3 of the compressor unit; When the intake pressure is lower than P1, the compressor unit is in standby mode; When the intake pressure is higher than P1 and lower than P2, the compressor unit works normally and adjusts the operating speed of the compressor between 0-100% according to the ratio of the intake pressure between P1 and P2; When the intake pressure is higher than P2 and the outlet pressure is lower than P3, and the compressor is not overloaded, the compressor maintains 100% speed operation. When the compressor is overloaded, the electric vent valve opens to vent part of the carbon dioxide and maintain the intake pressure between P1 and P2 or maintain the compressor in a non-overloaded operating state to ensure normal operation; When the exhaust pressure is higher than P3, the compressor stops and the electric vent valve is opened to vent part of the carbon dioxide and maintain the intake pressure between P1 and P2 to ensure the safety of the compressor unit; Pressure control between compressor stages: When the compressor is working, the exhaust volume of the compressor is adjusted according to the compressor inlet pressure. The greater the compressor inlet pressure, the greater the compressor exhaust volume.

[0007] Preferably, a standby time threshold S1 of the compressor is set, and when the standby time of the compressor exceeds S1, the compressor is forced to start for 1-2 minutes.

[0008] Preferably, each stage of the compressor is provided with a minimum intake pressure threshold and a maximum intake pressure threshold, wherein the minimum total intake pressure threshold P1 is the minimum intake pressure threshold of the first stage compressor, and the maximum total intake pressure threshold P2 is the maximum intake pressure threshold of the first stage compressor.

[0009] Preferably, the minimum total intake pressure threshold value P1 is 0.2 MPa, and the maximum total intake pressure threshold value P2 is 0.5 MPa. The minimum total intake pressure threshold value P1 and the maximum total intake pressure threshold value P2 are adjusted according to the actual working environment.

[0010] Preferably, it also includes automatic pressure ratio adjustment control; The compression ratio of each stage of compressor is adjustable. By controlling the compression ratio of each stage of compressor in linkage with the host, the outlet pressure of the last stage of compressor can meet the requirements.

[0011] Preferably, the compressor is a hydraulic piston pump, and a proportional valve is provided on the compressor, and the displacement of each stage of the compressor is adjusted by controlling the opening of the proportional valve.

[0012] Alternatively, the compressor is a swash plate type axial piston pump, and the displacement of each stage of the compressor is adjusted by controlling the swash plate angle of the swash plate type axial piston pump.

[0013] Preferably, it also includes outlet pressure control; The maximum outlet pressure threshold value P3 of the compressor unit is set, and the restart outlet pressure threshold value P4 of the compressor unit is set. When the outlet pressure of the compressor unit is higher than P3, the compressor unit is shut down. When the outlet pressure of the compressor unit is lower than P4, the compressor unit is started again. The restart outlet pressure threshold value P4 is 3-8MPa smaller than the maximum outlet pressure threshold value P3.

[0014] Preferably, the maximum outlet pressure threshold value P3 is 31-35 MPa, and the restart outlet pressure threshold value P4 is 26-30 MPa.

[0015] Preferably, outlet temperature control is also included: Set the maximum outlet temperature threshold T1 of the compressor unit, and the restart outlet temperature threshold T2 of the compressor unit. When the outlet temperature of the compressor unit is higher than T1, the compressor unit will shut down, and when the outlet temperature of the compressor unit is lower than T2, the compressor unit will start again. Too high a temperature will damage the seal, so the temperature control is set.

[0016] Preferably, the maximum temperature threshold T1 is 120°C, and the restart outlet temperature threshold T2 is 60-70°C.

[0017] The compressor unit further comprises a light oil recovery tank and a gas recovery tank, the light oil recovery tank and the gas recovery tank are arranged in sequence along the gas delivery direction in the compressor unit, and the light oil recovery tank and the gas recovery tank are respectively arranged between two adjacent compressors; The light oil recovery tank is connected with a condensation assembly. The gas pressure entering the light oil recovery tank reaches above 2.5MPa. After condensation by the condensation assembly, the hydrocarbon mixture in the gas is precipitated. A membrane separation component is provided in the gas recovery tank, and the gas entering the gas recovery tank passes through the membrane separation component to separate the C1-C4 components in the gas.

[0018] Compared with the prior art, the present invention has the following beneficial effects: By controlling the total intake pressure of the compressor unit and the pressure between each stage of the compressor, when the total intake pressure is lower than the set minimum total intake pressure threshold P1, the compressor starts but does not work and is in standby mode. When the total intake pressure is higher than the minimum total intake pressure threshold P1, the compressor starts working to avoid high-load operation of the compressor under low-pressure conditions. When the intake pressure reaches the maximum total intake pressure threshold P2, the compressor works at full speed and 100% displacement. If the intake pressure is higher than P2 and the compressor is not overloaded, the compressor continues to work. If it is overloaded, adjust the imported electric vent valve to discharge part of the carbon dioxide, and the compressor works within the rated load to avoid damage to compressor parts caused by high-pressure gas, thereby ensuring the normal and stable operation of the compressor.

[0019] According to the proportional relationship between the compressor inlet pressure P1 and P2, the proportional valve of the hydraulic system and the swash plate angle of the hydraulic oil pump are adjusted to realize the working speed of the compressor and change the exhaust volume of the compressor, so that the outlet pressure of the compressor meets the intake pressure of the next compressor, ensuring the normal operation of each level of compressor.

[0020] The control method also sets the compressor standby time threshold S1. When the compressor standby time exceeds S1, the compressor is forced to start for 1-2 minutes. This is because when the pressure is low for a long time, the particles in the well may block the bottom cracks, which will seriously reduce the oil recovery effect. After a certain period of time, by forcing the compressor to work and forcibly sucking the gas in the well for 1-2 minutes, the cracks can be unblocked to ensure the subsequent oil recovery effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the compressor unit embodiment 1.

[0022] Figure 2 This is a schematic diagram of the process of pressurizing the gas from the pipeline network by the compressor unit in Example 2.

[0023] Figure 3 Schematic diagram of the compressor in Example 3.

[0024] Among them: 1. Class A compressor 2. Class B compressor 3. Class C compressor 4. Electric vent valve 5. Swash plate 6. Adjustment servo motor 7. Class D compressor 8. Light oil recovery tank 9. Gas recovery tank 10. Radiator. DETAILED DESCRIPTION

[0025] Figure 1 This is the best embodiment of the control method of the compressor unit. Figures 1 to 3 The present invention is further described.

[0026] Example 1 Reference Figure 1 The control method of the compressor unit uses the compressor unit to compress carbon dioxide and then inject it back into the well. The compressor unit includes three stages of compressors connected in series, and an electric vent valve 4 is provided at the air inlet of the compressor unit. The electric vent valve 4 is an electric ball valve.

[0027] Set the minimum total intake pressure threshold value P1, the maximum total intake pressure threshold value P2 and the maximum outlet pressure threshold value P3 of the compressor unit; When the intake pressure is lower than P1, the compressor unit is in standby mode; When the intake pressure is higher than P1 and lower than P2, the compressor unit works normally and adjusts the operating speed of the compressor between 0-100% according to the ratio of the intake pressure between P1 and P2; When the inlet pressure is higher than P2 and the outlet pressure is lower than P3, and the compressor is not overloaded, the compressor maintains 100% speed operation. When the compressor is overloaded, the electric vent valve 4 opens to vent part of the carbon dioxide and maintain the inlet pressure between P1 and P2 to ensure normal operation; When the exhaust pressure is higher than P3, the compressor stops and the electric vent valve 4 is opened to vent part of the carbon dioxide and maintain the intake pressure between P1 and P2 to ensure the safety of the compressor unit.

[0028] In this embodiment, the minimum total intake pressure threshold value P1 is 0.2MPa, the maximum total intake pressure threshold value P2 is 0.5MPa, and the maximum outlet pressure threshold value P3 is 31-35MPa. When the exhaust pressure is higher than P3, part of the carbon dioxide is vented by adjusting the electric vent valve 4 to maintain the intake pressure below 0.5MPa, so as to avoid overload of the compressor and damage to the compressor parts caused by high-pressure gas.

[0029] This embodiment also sets a standby time threshold S1 for the compressor. When the standby time of the compressor exceeds S1, the compressor is forced to start for 1-2 minutes. This is because when the pressure is low for a long time, the particles in the well may block the bottom cracks, which will seriously reduce the oil recovery effect. After a certain period of time, the compressor is forced to work and the gas in the well is forced to be sucked for 1-2 minutes, which can unblock the cracks and ensure the subsequent oil recovery effect. The standby time threshold S1 is usually 30-80 minutes.

[0030] Pressure control between compressor stages: When the compressor is working, the exhaust volume of the compressor is adjusted according to the compressor inlet pressure. The greater the compressor inlet pressure, the greater the compressor exhaust volume.

[0031] Each stage of the compressor is set with a minimum intake pressure threshold and a maximum intake pressure threshold, wherein the minimum total intake pressure threshold P1 is the minimum intake pressure threshold of the first stage compressor, and the maximum total intake pressure threshold P2 is the maximum intake pressure threshold of the first stage compressor.

[0032] The compressor in this embodiment is a hydraulic piston pump, and a proportional valve is provided on the compressor, and the displacement of the compressor is adjusted by controlling the opening of the proportional valve. The three-stage compressor is defined as A, B, and C three-stage compressors, respectively, the A group proportional valve controls the A-stage compressor 1, the B group proportional valve controls the B-stage compressor 2, and the C group proportional valve controls the C-stage compressor 3.

[0033] The opening of the A group proportional valve is controlled by the inlet pressure. The inlet pressure setting value is 0.2MPa-0.5MPa, and the corresponding opening of the A group proportional valve is 0%-100%. When the intake pressure is 0.2MPa, the opening of the A group proportional valve is 0%. As the intake pressure gradually increases, the opening of the A group proportional valve gradually increases, and the corresponding piston movement speed gradually increases. When the intake pressure reaches 0.5MPa, the opening of the A group proportional valve is 100%. At this time, the compressor displacement is the maximum. The corresponding relationship here is that the intake pressure of 0.2-0.5MPA corresponds to the proportional valve opening of 0%-100%.

[0034] The same B group proportional valve corresponds to the inlet pressure of Class B compressor 2 (also the outlet pressure of Class A compressor 1). The inlet set pressure of Class B compressor 2 is 1MPa-2.5MPa, and the opening of Class B proportional valve is 0%-100% The C group proportional valve corresponds to the inlet pressure of the C class compressor 3 (also the outlet pressure of the B class compressor 2). The inlet pressure setting value of the C class compressor 3 is 5MPa-12.5MPa, and the opening of the C class proportional valve is 0%-100%.

[0035] On the basis of pressure control between compressors at various stages, it also includes automatic adjustment control of compression ratio; the specific method is: setting variable compression ratio for compressors at various stages, and linking the compression ratio of compressors at various stages through controlling the host machine, so that the outlet pressure of the last compressor stage meets the requirements.

[0036] The control method also sets a standby time threshold S1 of the compressor. When the standby time of the compressor exceeds S1, the compressor is forced to start for 1-2 minutes.

[0037] The control method of the compressor group of the present embodiment also includes outlet pressure control, and the specific method is: setting the maximum outlet pressure threshold value P3 of the compressor group, and setting the restart outlet pressure threshold value P4 for restarting the compressor group. When the outlet pressure of the compressor group is higher than P3, the compressor group shuts down. When the outlet pressure of the compressor group is lower than P4, the compressor group starts again. The restart outlet pressure threshold value P4 is 3-8MPa less than the maximum outlet pressure threshold value P3.

[0038] The restart outlet pressure threshold P4 is 26-30MPa.

[0039] The control method of the compressor unit of this embodiment also includes outlet temperature control: setting the maximum outlet temperature threshold value T1 of the compressor unit, setting the restart outlet temperature threshold value T2 of the compressor unit, when the outlet temperature of the compressor unit is higher than T1, the compressor unit is shut down, and when the outlet temperature of the compressor unit is lower than T2, the compressor unit is restarted. Specifically, the maximum temperature threshold value T1 is 120°C, and the restart outlet temperature threshold value T2 is 60-70°C.

[0040] By controlling the total intake pressure of the compressor unit and the pressure between each stage of the compressor, when the total intake pressure is lower than the set minimum total intake pressure threshold P1, the compressor starts but does not work and is in standby mode. When the total intake pressure is higher than the minimum total intake pressure threshold P1, the compressor starts to work to avoid high-load operation of the compressor under low-pressure conditions. When the intake pressure is higher than the maximum total intake pressure threshold P2, part of the carbon dioxide is discharged through the electric vent valve 4 to avoid damage to compressor parts caused by high-pressure gas.

[0041] In other embodiments, the initial ratio of the proportional valve opening of each stage of the compressor can be adjusted according to the working conditions, for example, it can be selected to be 30%-60%.

[0042] Example 2 Reference Figure 2 The compressor unit of this embodiment further includes a light oil recovery tank and a gas recovery tank, the light oil recovery tank and the gas recovery tank are sequentially arranged along the gas delivery direction in the compressor unit, and the light oil recovery tank and the gas recovery tank are respectively arranged between two adjacent compressors; A radiator 10 is also provided at the outlet of each compressor, and the discharged gas is cooled by the radiator 10. The compressor unit in this embodiment includes a class A compressor 1, a class B compressor 2, a class C compressor 3 and a class D compressor 7 arranged in sequence, wherein the light oil recovery tank is arranged between the class B compressor 2 and the class C compressor 3, and the gas recovery tank is arranged between the class C compressor 3 and the class D compressor 7.

[0043] The light oil recovery tank is connected with a condensation component. The gas pressure entering the light oil recovery tank reaches above 2.5MPa. After condensation by the condensation component, the hydrocarbon mixture in the gas is precipitated, and the C5 hydrocarbon mixture is recovered. The gas recovery tank is equipped with a membrane separation component. The gas entering the gas recovery tank passes through the membrane separation component to separate the C1-C4 components in the gas, and the C1-C4 components are recovered. While recycling carbon dioxide, the C1-C4 gas components and the C5 hydrocarbon mixture are recovered.

[0044] Example 3 See also Figure 3 The compressor in this embodiment is a swash plate 5 type axial piston pump, and the displacement of the compressor is adjusted by controlling the swash plate 5 angle of the swash plate 5 type axial piston pump. The three-stage compressor is defined as A, B, and C three-stage compressors, respectively. The swash plate 5 angle of the A-stage compressor 1 controls the A-stage compressor 1, the swash plate 5 angle of the B-stage compressor 2 controls the B-stage compressor 2, and the swash plate 5 angle of the C-stage compressor 3 controls the C-stage compressor 3.

[0045] The adjustment range of the angle of the swash plate 5 of the Class A compressor 1 is controlled by the inlet pressure. The normal working angle of the swash plate 5 is 100%. The inlet pressure setting value is 0.2MPa-0.5MPa, and the corresponding adjustment range of the swash plate 5 angle of the Class A compressor 1 is 0-100%. When the intake pressure is 0.2MPa, the proportion of the adjustment range corresponding to the angle of the swash plate 5 of the Class A compressor 1 is 0%. As the intake pressure gradually increases, the opening of the angle of the swash plate 5 of the Class A compressor 1 gradually increases, and the corresponding piston movement speed gradually increases. When the intake pressure reaches 0.5MPa, the proportion of the adjustment range corresponding to the opening of the angle of the swash plate 5 of the Class A compressor 1 is 100%. At this time, the compressor displacement is the largest. The corresponding relationship here is that the intake pressure of 0.2-0.5MPA corresponds to the oil pump swash plate 5 angle opening of 0-100%.

[0046] Similarly, the angle of the swash plate 5 of the B-class compressor 2 corresponds to the inlet pressure of the B-class compressor 2 (also the outlet pressure of the A-class compressor 1). The inlet set pressure of the B-class compressor 2 is 1MPa-2.5MPa, and the opening angle of the swash plate 5 of the B-class compressor 2 is 0%-100% The angle of the swash plate 5 of the C-class compressor 3 corresponds to the inlet pressure of the C-class compressor 3 (also the outlet pressure of the B-class compressor 2). The inlet pressure setting value of the C-class compressor 3 is 5MPa-12.5MPa, and the opening angle of the swash plate 5 of the C-class compressor 3 is 0%-100%.

[0047] Example 4 In this embodiment, the three-stage compressors are defined as A, B, and C compressors respectively. The A group of proportional valves controls the A class compressor 1 , the B group of proportional valves controls the B class compressor 2 , and the C group of proportional valves controls the C class compressor 3 .

[0048] The opening of the A group proportional valve is controlled by the inlet pressure. The inlet pressure setting value is 0.2MPa-0.5MPa, and the corresponding opening of the A group proportional valve is 0%-100%. When the intake pressure is 0.2MPa, the opening of the A group proportional valve is 0%. As the intake pressure gradually increases, the opening of the A group proportional valve gradually increases, and the corresponding piston movement speed gradually increases. When the intake pressure reaches 0.5MPa, the opening of the A group proportional valve is 100%. At this time, the compressor displacement is the maximum. The corresponding relationship here is that the intake pressure of 0.2-0.5MPA corresponds to the proportional valve opening of 0%-100%.

[0049] The same B group proportional valve corresponds to the inlet pressure of Class B compressor 2 (also the outlet pressure of Class A compressor 1). The inlet set pressure of Class B compressor 2 is 1MPa-2.5MPa, and the opening of Class B proportional valve is 0%-100% The C group proportional valve corresponds to the inlet pressure of the C class compressor 3 (also the outlet pressure of the B class compressor 2). The inlet pressure setting value of the C class compressor 3 is 5MPa-12.5MPa, and the opening of the C class proportional valve is 0%-100%.

[0050] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

Claims

1. A method for controlling a compressor unit, which uses a compressor unit to compress carbon dioxide and then inject it back into the well, characterized in that: The compressor unit comprises at least two stages of compressors connected in series, and an electric vent valve is provided at the air inlet of the compressor unit; The inlet pressure of the compressor unit is controlled as follows: Set the minimum total intake pressure threshold value P1, the maximum total intake pressure threshold value P2 and the maximum outlet pressure threshold value P3 of the compressor unit; When the intake pressure is lower than P1, the compressor unit is in standby mode; When the intake pressure is higher than P1 and lower than P2, the compressor unit works normally and adjusts the operating speed of the compressor between 0-100% according to the ratio of the intake pressure between P1 and P2; When the inlet pressure is higher than P2 and the outlet pressure is lower than P3, and the compressor is not overloaded, the compressor maintains 100% speed operation. When the compressor is overloaded, the electric vent valve opens to vent part of the carbon dioxide and maintain the inlet pressure between P1 and P2. When the exhaust pressure is higher than P3, the compressor stops and the electric vent valve is opened to vent part of the carbon dioxide and maintain the intake pressure between P1 and P2 or maintain the compressor in a non-overloaded operating state; Pressure control between compressor stages: When the compressor is working, the exhaust volume of the compressor is adjusted according to the compressor inlet pressure. The greater the compressor inlet pressure, the greater the compressor exhaust volume.

2. The control method of the compressor unit according to claim 1, characterized in that: Set the compressor standby time threshold S1. When the compressor standby time exceeds S1, the compressor is forced to start for 1-2 minutes.

3. The control method of the compressor unit according to claim 1, characterized in that: Each stage of the compressor is set with a minimum intake pressure threshold and a maximum intake pressure threshold, wherein the minimum total intake pressure threshold P1 is the minimum intake pressure threshold of the first stage compressor, and the maximum total intake pressure threshold P2 is the maximum intake pressure threshold of the first stage compressor.

4. The control method of the compressor unit according to claim 1 or 3, characterized in that: The minimum total intake pressure threshold value P1 is 0.2 MPa, and the maximum total intake pressure threshold value P2 is 0.5 MPa.

5. The control method of the compressor unit according to claim 1, characterized in that: It also includes automatic pressure ratio adjustment control; The compression ratio of each stage of compressor is adjustable. By controlling the compression ratio of each stage of compressor in linkage with the host, the outlet pressure of the last stage of compressor can meet the requirements.

6. The control method of the compressor unit according to claim 1, characterized in that: The compressor is a hydraulic piston pump, and a proportional valve is provided on the compressor, and the displacement of each level of the compressor is adjusted by controlling the opening of the proportional valve; Alternatively, the compressor is a swash plate type axial piston pump, and the displacement of each stage of the compressor is adjusted by controlling the swash plate angle of the swash plate type axial piston pump.

7. The control method of the compressor unit according to claim 1, characterized in that: Also includes outlet pressure control; The restart outlet pressure threshold value P4 of the compressor unit is set. When the outlet pressure of the compressor unit is higher than P3, the compressor unit shuts down. When the outlet pressure of the compressor unit is lower than P4, the compressor unit starts again. The restart outlet pressure threshold value P4 is 3-8MPa less than the maximum outlet pressure threshold value P3.

8. The control method of the compressor unit according to claim 7, characterized in that: The maximum outlet pressure threshold value P3 is 31-35 MPa, and the restart outlet pressure threshold value P4 is 26-30 MPa.

9. The control method of a compressor unit according to claim 1, characterized in that: Also includes outlet temperature control: The maximum outlet temperature threshold T1 of the compressor unit is set, and the restart outlet temperature threshold T2 of the compressor unit is set. When the outlet temperature of the compressor unit is higher than T1, the compressor unit is shut down. When the outlet temperature of the compressor unit is lower than T2, the compressor unit is started again.

10. The control method of a compressor unit according to claim 1, characterized in that: The compressor unit further comprises a light oil recovery tank and a gas recovery tank, the light oil recovery tank and the gas recovery tank are arranged in sequence along the gas delivery direction in the compressor unit, and the light oil recovery tank and the gas recovery tank are respectively arranged between two adjacent compressors; The light oil recovery tank is connected with a condensation assembly. The gas pressure entering the light oil recovery tank reaches above 2.5MPa. After condensation by the condensation assembly, the hydrocarbon mixture in the gas is precipitated. A membrane separation component is provided in the gas recovery tank, and the gas entering the gas recovery tank passes through the membrane separation component to separate the C1-C4 components in the gas.

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