A quantitative recovery system for flare gas in an offshore oil and gas field

Abstract

The present invention provides a quantitative recovery system for flare-emitted fuel gas in an offshore oil and gas field, which includes a low-pressure gas pipeline network for collecting low-pressure fuel gas and a flare system. The low-pressure gas pipeline network is respectively connected with a skid-mounted compressor unit and a flare main pipeline network. The skid-mounted compressor unit includes a second emergency shutdown valve, a compressor inlet cooler, a gas-liquid separator, a compressor main unit, a compressor outlet cooler and a third emergency shutdown valve that are sequentially connected with the low-pressure gas pipeline network. A compressor local control panel is also arranged on the skid-mounted compressor unit, and the compressor local control panel is respectively connected with the second emergency shutdown valve and the third emergency shutdown valve. The third emergency shutdown valve is connected with the fuel gas system. The present invention can quantitatively recover part of the low-pressure fuel gas and burn and discharge the remaining non-recoverable low-pressure gas in the flare system.

Description

Technical Field

[0001] The present invention belongs to the technical field of waste low-pressure fuel gas emission and recovery in offshore oil and gas fields, and more specifically, relates to a quantitative recovery system for flare-emitted fuel gas in offshore oil and gas fields. Background Art

[0002] During the process of oil and gas field exploitation and refining of oil and natural gas, a part of low-pressure fuel gas is generated. This part of the gas is usually burned through a flare combustion system or cold vented, resulting in waste of resources and environmental pollution. For environmental protection considerations, onshore petrochemical enterprises install flare extinguishing devices on production units. However, compared with onshore petrochemical enterprises, due to their geographical location and relatively special operating environment, it is difficult for offshore oil and gas fields to install flare extinguishing devices on offshore platforms, and there are still problems of air pollution and waste of fuel gas. Therefore, there is an urgent need for a technical solution for recovering flare-emitted fuel gas in offshore oil and gas fields in the prior art. Summary of the Invention

[0003] In view of the above deficiencies in the prior art, the present invention provides a quantitative recovery system for flare-emitted fuel gas in offshore oil and gas fields, which quantitatively recovers the low-pressure gaseous fuel generated during the oil and gas exploitation process and burns and discharges the remaining low-pressure fuel gas in the flare system.

[0004] To achieve the above object, the present invention is realized through the following technical solutions:

[0005] A quantitative recovery system for flare-emitted fuel gas in offshore oil and gas fields includes a low-pressure gas pipeline network for collecting low-pressure fuel gas and a flare system.

[0006] The low-pressure gas pipeline network is respectively connected to a skid-mounted compressor unit and a flare main pipeline network. The skid-mounted compressor unit includes a second emergency shutdown valve, a compressor inlet cooler, a gas-liquid separator, a compressor main unit, a compressor outlet cooler, and a third emergency shutdown valve that are sequentially connected to the low-pressure gas pipeline network. A compressor local control panel is also provided on the skid-mounted compressor unit. The compressor local control panel is respectively connected to the second emergency shutdown valve and the third emergency shutdown valve. The third emergency shutdown valve is connected to the fuel gas system. The drainage pipeline of the compressor inlet cooler is communicated with seawater. A first regulating valve is provided on the drainage pipeline of the compressor inlet cooler. The first regulating valve is connected to a compressor inlet temperature transmitter provided on the exhaust pipeline of the compressor inlet cooler.

[0007] The gas-liquid separator is connected to the closed drainage system through the gas-liquid separator drainage pipeline. A second regulating valve is provided on the gas-liquid separator drainage pipeline. A gas-liquid separator pressure transmitter and a gas-liquid separator level transmitter are also provided on the gas-liquid separator. A compressor frequency converter is provided on the main compressor unit. The gas-liquid separator pressure transmitter is connected to the compressor frequency converter, and the gas-liquid separator level transmitter is connected to the second regulating valve.

[0008] The drainage pipeline of the compressor outlet cooler is connected to seawater. A third regulating valve is provided on the drainage pipeline of the compressor outlet cooler. A compressor outlet temperature transmitter is provided on the exhaust pipeline of the compressor outlet cooler. The compressor outlet temperature transmitter is connected to the third regulating valve. The exhaust pipeline of the compressor outlet cooler is also respectively connected to the intake pipeline of the gas-liquid separator and the flare main header. A reflux pipeline regulating valve is provided on the reflux pipeline where the exhaust pipeline of the compressor outlet cooler is connected to the intake pipeline of the gas-liquid separator. A BDV relief valve is provided on the pipeline where the exhaust pipeline of the compressor outlet cooler is connected to the flare main header.

[0009] The flare main header is connected to a flare knockout drum. A flare knockout drum pressure transmitter is provided on the flare knockout drum. The compressor local control panel is respectively connected to the gas-liquid separator pressure transmitter and the flare knockout drum pressure transmitter. The flare knockout drum is connected to a water seal tank through a water seal tank inlet pipeline. An ultrasonic flowmeter is provided on the water seal tank inlet pipeline. The water seal tank is connected to a flare system through a water seal tank outlet pipeline.

[0010] The water seal tank is separated into a water seal area and an oil skimming area by a weir plate. The water seal area and the oil skimming area are connected through a connecting pipeline. A pneumatic on-off valve is provided on the connecting pipeline. A water seal area level transmitter is provided in the water seal area. The water seal tank inlet pipeline is connected to the water seal area. The water seal area is connected to a makeup water system through a water seal area makeup water pipeline. A makeup water pipeline regulating valve and a first emergency shutdown valve are provided on the water seal area makeup water pipeline. The makeup water pipeline regulating valve is connected to the water seal area level transmitter. An oil skimming area level transmitter is provided in the oil skimming area. The oil skimming area is connected to an oil skimming pump through a water seal tank oil skimming pipeline. The oil skimming pump is connected to the closed drainage system through an oil skimming pump outlet pipeline. An oil skimming pipeline regulating valve is provided on the water seal tank oil skimming pipeline. The oil skimming pipeline regulating valve is connected to the oil skimming area level transmitter. A water seal tank level indicating transmitter is provided on the water seal tank. The water seal tank level indicating transmitter is connected to the first emergency shutdown valve and the oil skimming pump.

[0011] The flare system is an automatic ignition system.

[0012] The weir plate is penetrated by a hot oil coil pipe, and the inlet and outlet of the hot oil coil pipe are both connected to a hot oil circulation generating system.

[0013] An oil skimming tank is arranged at the end of the weir plate.

[0014] The beneficial effects of the present invention compared with the prior art are as follows: The compressor local control panel controls whether the second emergency shutdown valve is closed according to the pressures measured by the flare knockout drum pressure transmitter and the gas-liquid separator pressure transmitter, can quantitatively recover part of the low-pressure fuel gas, and burn and discharge the remaining non-recoverable low-pressure gas in the flare system. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a partial enlarged view of the skid-mounted compressor unit part.

[0016] Figure 2 It is a partial enlarged view of the water seal tank part.

[0017] Figure 3 It is a system diagram of the present invention.

[0018] Reference numerals: 1 - second emergency shutdown valve, 2 - compressor inlet cooler, 3 - first regulating valve, 4 - compressor inlet temperature transmitter, 5 - gas-liquid separator, 6 - second regulating valve, 7 - gas-liquid separator pressure transmitter, 8 - gas-liquid separator liquid level transmitter, 9 - compressor main unit, 10 - compressor frequency converter, 11 - compressor outlet cooler, 12 - third regulating valve, 13 - compressor outlet temperature transmitter, 14 - third emergency shutdown valve, 15 - return pipeline regulating valve, 16 - BDV relief valve, 17 - compressor local control panel, 18 - skid-mounted compressor unit, 19 - flare main pipe, 20 - weir plate, 21 - flare knockout drum, 22 - flare knockout drum pressure transmitter, 23 - ultrasonic flowmeter, 24 - water seal tank inlet pipeline, 25 - water seal tank, 26 - water seal area liquid level transmitter, 27 - water seal tank liquid level indicating transmitter, 28 - water seal tank outlet pipeline, 29 - flare system, 30 - oil skimming area liquid level transmitter, 31 - make-up water pipeline regulating valve, 32 - pneumatic switch valve, 33 - water seal tank oil skimming pipeline, 34 - hot oil coil pipe, 35 - oil skimming pump, 36 - oil skimming pump outlet pipeline, 37 - water seal area make-up water pipeline, 38 - gas-liquid separator drain pipeline, 39 - compressor outlet exhaust pipeline, 40 - first emergency shutdown valve, 41 - low-pressure gas header, 44 - return pipeline. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] As Figures 1-3 shown, a quantitative recovery system for flare emission fuel gas in an offshore oil and gas field includes a low-pressure gas header 41 for collecting low-pressure fuel gas and a flare system 29.

[0020] The low-pressure gas pipe manifold 41 is respectively connected to a skid-mounted compressor unit 18 and a flare main pipe manifold 19. The skid-mounted compressor unit 18 includes a second emergency shutdown valve 1, a compressor inlet cooler 2, a gas-liquid separator 5, a compressor main unit 9, a compressor outlet cooler 11, and a third emergency shutdown valve 14 that are sequentially connected to the low-pressure gas pipe manifold 41. A compressor local control panel 17 is also provided on the skid-mounted compressor unit 18. The compressor local control panel 17 is respectively connected to the second emergency shutdown valve 1 and the third emergency shutdown valve 14. The third emergency shutdown valve 14 is connected to the fuel gas system through a compressor outlet exhaust pipe 39. The drain pipe of the compressor inlet cooler 2 is connected to seawater. A first regulating valve 3 is provided on the drain pipe of the compressor inlet cooler 2. The first regulating valve 3 is connected to a compressor inlet temperature transmitter 4 provided on the exhaust pipe of the compressor inlet cooler 2.

[0021] The gas-liquid separator 5 is connected to a closed drainage system through a gas-liquid separator drain pipe 38. A second regulating valve 6 is provided on the gas-liquid separator drain pipe 38. A gas-liquid separator pressure transmitter 7 and a gas-liquid separator level transmitter 8 are also provided on the gas-liquid separator 5. A compressor frequency converter 10 is provided on the compressor main unit 9. The gas-liquid separator pressure transmitter 7 is connected to the compressor frequency converter 10. The gas-liquid separator level transmitter 8 is connected to the second regulating valve 6.

[0022] The drain pipe of the compressor outlet cooler 11 is connected to seawater. A third regulating valve 12 is provided on the drain pipe of the compressor outlet cooler 11. A compressor outlet temperature transmitter 13 is provided on the exhaust pipe of the compressor outlet cooler 11. The compressor outlet temperature transmitter 13 is connected to the third regulating valve 12. The exhaust pipe of the compressor outlet cooler 11 is also respectively connected to the inlet pipe of the gas-liquid separator 5 and the flare main pipe manifold 19. A return pipe regulating valve 15 is provided on the return pipe 44 where the exhaust pipe of the compressor outlet cooler 11 is connected to the inlet pipe of the gas-liquid separator 5. A BDV relief valve 16 is provided on the pipe where the exhaust pipe of the compressor outlet cooler 11 is connected to the flare main pipe manifold 19. The BDV (blow down valve) relief valve is related to the emergency shutdown system. Its purpose is to safely discharge the materials (mostly gas) in the system under emergency accidents (such as fire) to reduce the pressure in the system, rather than waiting for the safety valve to discharge when the design pressure is exceeded. It is in a normally closed state under normal operating conditions.

[0023] The main flare header 19 is connected to a flare knockout drum 21. A flare knockout drum pressure transmitter 22 is provided on the flare knockout drum 21. The compressor local control panel 17 is respectively connected to the gas-liquid separator pressure transmitter 7 and the flare knockout drum pressure transmitter 22. The flare knockout drum 21 is connected to a seal pot 25 through a seal pot inlet pipeline 24. An ultrasonic flowmeter 23 is provided on the seal pot inlet pipeline 24. The seal pot 25 is connected to a flare system 29 through a seal pot outlet pipeline 28.

[0024] The seal pot 25 is separated into a water seal area and an oil skimming area by a weir plate 20. An oil skimming trough (not shown in the figure) is provided at the end of the weir plate 20. Floating oil will be generated on the upper surface of the water in the water seal area. The floating oil flows from the water seal area into the oil skimming area through the oil skimming trough. The water seal area and the oil skimming area are connected through a connecting pipeline. A pneumatic switch valve 32 is provided on the connecting pipeline. In this embodiment, the pneumatic switch valve 32 is a butterfly valve. A water seal area liquid level transmitter 26 is provided in the water seal area. The seal pot inlet pipeline 24 is connected to the water seal area. The water seal area is connected to a water supply system through a water seal area make-up water pipeline 37. A make-up water pipeline regulating valve 31 and a first emergency shutdown valve 40 are provided on the water seal area make-up water pipeline 37. The make-up water pipeline regulating valve 31 is connected to the water seal area liquid level transmitter 26. An oil skimming area liquid level transmitter 30 is provided in the oil skimming area. The oil skimming area is connected to an oil skimming pump 35 through a seal pot oil skimming pipeline 33. The oil skimming pump 35 is connected to a closed drainage system through an oil skimming pump outlet pipeline 36. An oil skimming pipeline regulating valve is provided on the seal pot oil skimming pipeline 33. The oil skimming pipeline regulating valve is connected to the oil skimming area liquid level transmitter 30. A seal pot liquid level indicating transmitter 27 is provided on the seal pot 25. The seal pot liquid level indicating transmitter 27 is connected to the first emergency shutdown valve 40 and the oil skimming pump 35.

[0025] The flare system 29 is an automatic ignition system. The high-voltage wire and the arc generation device in the automatic ignition system directly ignite the pilot burner through an electric ignition device. The electric ignition device can achieve automatic operation, on-site manual operation, and remote control operation in the central control room. The automatic ignition system uses the thermocouple signal to judge the combustion state of the pilot burner. When the pilot burner goes out, the control system automatically starts the electric ignition device to re-ignite the pilot burner. To ensure the safety of the platform in the abnormal shutdown state, the flare pilot burner remains lit for a long time to ensure that the flare can be ignited at any time when the main flare header discharges fuel gases such as natural gas.

[0026] The weir plate 20 is penetrated by a hot oil coil pipe 34. Both the oil inlet and the oil outlet of the hot oil coil pipe 34 are connected to a hot oil circulation generating system. The offshore platform is equipped with a hot oil circulation generating system which heats the oil and transports it through the oil inlet to the hot oil coil pipe 34, where it flows through the water seal area and the oil skimming area and finally returns to the hot oil circulation generating system for recycling. The hot oil coil pipe 34 has good heat conduction performance, and is sealed at the places where it enters and exits the water seal tank 25 and passes through the weir plate 20, ensuring that the hot oil will not leak into the water seal tank 25 to contaminate the water and fuel gas in the water seal tank 25. The hot oil heats the water in the water seal tank 25 to prevent the water seal tank 25 from freezing due to too low temperature.

[0027] The working mode of the present invention is as follows:

[0028] The low-pressure fuel gas generated in the offshore oil and gas field is collected and divided into two paths. One path enters the skid-mounted compressor unit 18, and the other part enters the flare main manifold 19. The gas entering the skid-mounted compressor unit 18 first passes through the second emergency shutdown valve 1 and enters the compressor inlet cooler 2. Seawater is used as the cooling water and enters the compressor inlet cooler 2. When the exhaust temperature measured by the compressor inlet temperature transmitter 4 exceeds the set temperature value, the first regulating valve 3 signal-connected to the compressor inlet temperature transmitter 4 automatically opens, and discharges the water into the sea through the drain pipe of the compressor inlet cooler 2.

[0029] The cooled low-pressure gas enters the gas-liquid separator 5, where the gas is separated and enters the compressor main body 9. The liquid precipitates below the gas-liquid separator 5. When the liquid level indication of the liquid level transmitter 8 on the gas-liquid separator 5 is higher than the set value, the second regulating valve 6 signal-connected to it automatically opens, and discharges the liquid from the bottom of the gas-liquid separator 5 through the drain pipe 38 of the gas-liquid separator into the closed drainage system. The closed drainage system is used to discharge the water containing oil into the sea after treatment. The frequency converter 10 on the compressor main body 9 is signal-connected to the gas-liquid separator pressure transmitter 7 on the gas-liquid separator 5. The gas-liquid separator pressure transmitter 7 measures the pressure of the low-pressure gas separated above the gas-liquid separator 5. The frequency converter 10, that is, the variable frequency motor, can adjust the frequency of the compressor according to the pressure of the low-pressure gas, so as to compress the gas to the target air pressure value and realize the quantitative control of the recovery of the low-pressure fuel gas.

[0030] The compressed fuel gas enters the compressor outlet cooler 11, and the cooling water enters the compressor outlet cooler 11 to further cool the fuel gas. When the temperature value measured by the compressor outlet temperature transmitter 13 is higher than a certain set value, the third regulating valve 12 is automatically opened to discharge the used cooling water back into the sea water. The further cooled gas is divided into three paths. One path passes through the compressor outlet exhaust pipeline 39 and enters the fuel gas system. This part of the gas is recovered and continues to be used as fuel gas. For a natural gas field, this part of the natural gas can be directly sold. When the temperature indication of the compressor outlet temperature transmitter 13 exceeds the allowed maximum threshold, the third emergency shutdown valve 14 is shut off to prevent the compressed fuel gas from having too high a temperature and causing danger when entering the fuel gas system. The second path of the further cooled gas enters the reflux pipeline 44 and returns to the inlet pipeline of the gas-liquid separator 5. When the pressure value measured by the gas-liquid separator pressure transmitter 7 is higher than the preset value of the gas pressure in the gas-liquid separator 5, the reflux pipeline regulating valve 15 is started to make part of the compressed fuel gas reflux to the gas-liquid separator 5. The third path of the further cooled gas flows into the pipeline leading to the flare main header 19. The BDV relief valve 16 on this pipeline will open automatically when the pressure exceeds its own threshold, thereby reducing the pressure in the pipeline. This part of the fuel gas that has not been recovered into the fuel gas system then enters the flare main header 19 and then enters the flare knockout drum 21.

[0031] In the flare knockout drum 21, the water vapor carried in the fuel gas is further condensed and separated. The dry fuel gas enters the water seal tank 25 through the water seal tank inlet pipeline 24. The flare knockout drum pressure transmitter 22 and the gas-liquid separator pressure transmitter 7 are both connected to the compressor local control panel 17 by signals. When the pressure in the flare knockout drum or the gas pressure in the gas-liquid separator is greater than their respective maximum thresholds, the second emergency shutdown valve 1 needs to be closed and the compressor main unit 9 needs to be shut down to prevent danger such as explosion due to too high pressure; when the pressure in the flare knockout drum or the gas pressure in the gas-liquid separator is lower than their respective minimum thresholds, the second emergency shutdown valve 1 should also be closed and the compressor main unit 9 should be shut down to avoid the skid-mounted compressor unit 18 compressing the fuel gas meaninglessly and causing unnecessary waste.

[0032] The fuel gas enters the water seal tank 25. The weir plate 20 divides the water seal tank 25 into a water seal area and an oil skimming area. The height of the weir plate 20 is adjustable and can be set to different heights according to the amount of recovered fuel gas on site to establish water seals and back pressures of different heights. The fuel gas first enters the water seal area. When it reaches a certain pressure, it will break through the water seal and enter the water seal tank outlet pipeline 28, and then enter the flare system 29 for combustion. The combustion products are discharged into the atmosphere.

[0033] When the pressure of the flare network measured by the flare knockout drum pressure transmitter 22 is higher than the set value, and the water seal height measured by the water seal area level transmitter 26 is higher than the highest set value of the liquid level, the pneumatic switch valve 32 opens to perform the "remove water seal" action. Part of the water flows into the oil skimming area until the water seal liquid level reaches the highest set value, and then the pneumatic switch valve 32 is closed. When the operator gives the "build water seal" signal and the liquid level is lower than the lowest liquid level set value, the water seal area level transmitter 26 controls the opening of the make-up water pipeline regulating valve 31 on the make-up water pipeline 37 of the water seal area to perform automatic water make-up.

[0034] The floating oil on the upper surface of the water seal side is introduced into the oil skimming area on the other side of the weir plate 20 by the oil skimming tank arranged at the end of the weir plate 20. The oil skimming area level transmitter 30 controls the start and stop of the oil skimming pump 35 through the LIC (Level Indicator Controller). As the floating oil continuously enters the oil skimming area from the oil skimming tank, when the liquid level signal of the oil skimming area level transmitter 30 exceeds its set value, the oil skimming pump 35 is started to pump away the floating oil on the liquid surface, and after the water make-up and oil skimming are completed, the drain pipeline of the water seal area is manually opened to lower the water seal to the required height.

[0035] The LIC controller, that is, the level indicator controller, installs the ultrasonic probe directly below (at the bottom) the outer wall of the measured container. There is no need to open holes, the installation is simple, and it does not affect the on-site production. It can achieve accurate measurement of various toxic substances and various pure liquids in high-temperature and high-pressure sealed containers. The instrument adopts an explosion-proof design to meet the explosion-proof requirements. Structure of the level indicator: When the liquid level changes, the float floats up and down following the change of the liquid level. The toothed conveyor belt drives the mechanical indicator to change its up and down position, and the simple scale indicates the height of the liquid level. At the same time, the conveyor belt drives the gear of the gearbox to rotate. The gearbox converts the displacement of the float from the lowest position to the highest position into a 360° rotation change and sends it to the photoelectric encoder. The photoelectric encoder converts this position into an 8-bit binary number and sends it to the liquid level measuring device. The liquid level measuring device receives the data output by the photoelectric encoder, processes this data, and then obtains the liquid level value at that time. This liquid level value can be sent to the management computer in the control room through the communication bus, and at the same time, this liquid level value is displayed locally by the LED. This device can also accumulate the liquid flow rate into and out of the tank. The gearbox and the photoelectric encoder are encapsulated by an aluminum casting shell to meet the requirements of anti-corrosion and explosion-proof.

[0036] The water seal tank level indicating transmitter 27 is respectively signal-connected to the first emergency shutdown valve 40 and the oil skimming pump 35. When the liquid level in the oil skimming area reaches the set value of the water seal tank level indicating transmitter 27, the water seal tank level indicating transmitter 27 will start the oil skimming pump 35 and close the first emergency shutdown valve 40 through the ESD (Electro-Static discharge) system, stopping the water supply system from supplying water to the water seal tank 25.

[0037] ESD is the abbreviation of the English term "Emergence Shutdown", and is called the Emergency Shutdown System in Chinese. It consists of three major parts: input, control, and output. The input part of the ESD system generally consists of pressure switches, temperature switches, level switches, intelligent transmitters, and some manual switches, buttons, etc.; the control part can be composed of wired relay logic circuits, pneumatic logic circuits, electric logic control circuits, PLC programmable controllers, FSC fault-safe controllers, etc.; the output part consists of pneumatic or electric shutdown valves, vent valves, and some shutdown switches, which are used to shut down and bypass the process flow and shut down the corresponding equipment.

[0038] When the time that the fuel gas flow rate measured by the ultrasonic flowmeter 23 is lower than the preset value exceeds the preset duration, the system will issue an alarm signal and close the flare system 29, and the fuel is directly discharged into the sea water through the closed drainage system; when the measured flow rate is higher than the preset value, the flare system 29 is opened, and after the fuel gas is burned, the carbon dioxide, water vapor and other combustion products are discharged into the atmosphere.

[0039] The above are only the preferred embodiments of the present invention, but the present invention is not limited to the above specific embodiments. For those of ordinary skill in the art, without departing from the inventive concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention.

Claims

1. A quantitative recovery system for flare-emitted fuel gas in an offshore oil and gas field, comprising a low-pressure gas pipeline network (41) for collecting low-pressure fuel gas and a flare system (29), characterized in that, The low-pressure gas pipeline manifold (41) is respectively connected to a skid-mounted compressor unit (18) and a flare main pipeline manifold (19). The skid-mounted compressor unit (18) includes a second emergency shutdown valve (1), a compressor inlet cooler (2), a gas-liquid separator (5), a compressor main unit (9), a compressor outlet cooler (11), and a third emergency shutdown valve (14) that are sequentially connected to the low-pressure gas pipeline manifold (41). A compressor local control panel (17) is further provided on the skid-mounted compressor unit (18). The compressor local control panel (17) is respectively connected to the second emergency shutdown valve (1) and the third emergency shutdown valve (14). The third emergency shutdown valve (14) is connected to the fuel gas system through a compressor outlet exhaust pipeline (39). The drain pipeline of the compressor inlet cooler (2) is connected to seawater. A first regulating valve (3) is provided on the drain pipeline of the compressor inlet cooler (2). The first regulating valve (3) is connected to a compressor inlet temperature transmitter (4) provided on the exhaust pipeline of the compressor inlet cooler (2); The gas-liquid separator (5) is connected to a closed drainage system through a gas-liquid separator drain pipeline (38). A second regulating valve (6) is provided on the gas-liquid separator drain pipeline (38). A gas-liquid separator pressure transmitter (7) and a gas-liquid separator level transmitter (8) are further provided on the gas-liquid separator (5). A compressor frequency converter (10) is provided on the compressor main unit (9). The gas-liquid separator pressure transmitter (7) is connected to the compressor frequency converter (10). The gas-liquid separator level transmitter (8) is connected to the second regulating valve (6); The drain pipeline of the compressor outlet cooler (11) is connected to seawater. A third regulating valve (12) is provided on the drain pipeline of the compressor outlet cooler (11). A compressor outlet temperature transmitter (13) is provided on the exhaust pipeline of the compressor outlet cooler (11). The compressor outlet temperature transmitter (13) is connected to the third regulating valve (12). The exhaust pipeline of the compressor outlet cooler (11) is further respectively connected to the inlet pipeline of the gas-liquid separator (5) and the flare main pipeline manifold (19). A return pipeline regulating valve (15) is provided on a return pipeline (44) where the exhaust pipeline of the compressor outlet cooler (11) is connected to the inlet pipeline of the gas-liquid separator (5). A BDV relief valve (16) is provided on the pipeline where the exhaust pipeline of the compressor outlet cooler (11) is connected to the flare main pipeline manifold (19); The flare main header (19) is connected to a flare knockout drum (21). A flare knockout drum pressure transmitter (22) is provided on the flare knockout drum (21). The compressor local control panel (17) is respectively connected to the gas-liquid separator pressure transmitter (7) and the flare knockout drum pressure transmitter (22). The flare knockout drum (21) is connected to a water seal tank (25) through a water seal tank inlet pipeline (24). An ultrasonic flowmeter (23) is provided on the water seal tank inlet pipeline (24). The water seal tank (25) is connected to a flare system (29) through a water seal tank outlet pipeline (28); The water seal tank (25) is separated into a water seal area and an oil skimming area by a weir plate (20). The water seal area and the oil skimming area are connected through a communication pipeline (43). A pneumatic on-off valve (32) is provided on the communication pipeline (43). A water seal area liquid level transmitter (26) is provided in the water seal area. The water seal tank inlet pipeline (24) is connected to the water seal area. The water seal area is connected to a water supply system through a water seal area make-up water pipeline (37). A make-up water pipeline regulating valve (31) and a first emergency shutdown valve (40) are provided on the water seal area make-up water pipeline (37). The make-up water pipeline regulating valve (31) is connected to the water seal area liquid level transmitter (26). An oil skimming area liquid level transmitter (30) is provided in the oil skimming area. The oil skimming area is connected to an oil skimming pump (35) through a water seal tank oil skimming pipeline (33). The oil skimming pump (35) is connected to a closed drainage system through an oil skimming pump outlet pipeline (36). An oil skimming pipeline regulating valve (42) is provided on the water seal tank oil skimming pipeline (33). The oil skimming pipeline regulating valve (42) is connected to the oil skimming area liquid level transmitter (30); A water seal tank liquid level indicating transmitter (27) is provided on the water seal tank (25). The water seal tank liquid level indicating transmitter (27) is connected to the first emergency shutdown valve (40) and the oil skimming pump (35); The flare system (29) is an automatic ignition system; A hot oil coil (34) passes through the weir plate (20). The inlet and outlet of the hot oil coil (34) are both connected to a hot oil circulation generating system.

2. The quantitative recovery system for flare-emitted fuel gas in an offshore oil and gas field according to claim 1, characterized in that, An oil skimming trough is provided at the end of the weir plate (20).

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