A tertiary oil and gas recovery method and system for a gas station

Abstract

The present invention discloses a tertiary oil and gas recovery method and system for a gas station, the method comprising obtaining an oil temperature value and a liquid level height in a gas-liquid separation tank, and opening or closing a first solenoid valve between the gas-liquid separation tank and the oil storage area according to the oil temperature value and the liquid level height, so as to control the opening and closing of a return oil pipeline, that is, the return oil pipeline has nothing to do with the operation or stop of the system and is only related to the state of the gas-liquid separation tank, that is, the present invention can control the opening and closing of the return oil pipeline according to the temperature or the liquid level height in the gas-liquid separation tank, and avoid the impact of the condensed oil with a lower temperature on the crude oil in the oil storage tank, that is, it can not only improve the quality of the condensed oil return of the gas station, improve the efficiency of the condensed oil return, but also improve the service life of the gas station system.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil and gas recovery at gas stations, and in particular relates to a tertiary oil and gas recovery method and system for gas stations. Background Art

[0002] At present, most gas stations use tertiary oil and gas recovery systems to reduce the concentration of atmospheric pollutants, making gas stations more environmentally friendly. However, the current tertiary oil and gas recovery systems still have various shortcomings during use, and the key components are prone to malfunction or failure during long-term use, which not only affects the use of gas stations, but also causes the emission of pollutants to seriously exceed the standard. Summary of the Invention

[0003] The purpose of the present invention is to overcome the defects of the existing technology and provide a tertiary oil and gas recovery method and system for a gas station. The opening and closing of the return oil pipeline is controlled according to the temperature or liquid level in the gas-liquid separation tank to prevent the condensed oil with lower temperature from impacting the crude oil in the oil storage tank. That is, it can not only improve the quality of the condensed oil return from the gas station, improve the efficiency of the condensed oil return, but also increase the service life of the gas station system.

[0004] The object of the present invention is achieved through the following technical solutions:

[0005] A tertiary oil and gas recovery method for a gas station, comprising:

[0006] Obtaining the oil temperature value in the gas-liquid separation tank, comparing it with a preset temperature threshold, and outputting a first start signal if the oil temperature exceeds the preset temperature threshold; and outputting a first shut-down signal if the oil temperature is less than the preset temperature threshold;

[0007] Obtaining a liquid level height ratio value in the gas-liquid separation tank, comparing it with a preset height ratio threshold, and outputting a second start signal if the liquid level height ratio value exceeds the preset height ratio threshold; and outputting a second shut-down signal if the liquid level height ratio value is less than the preset height ratio threshold;

[0008] A first solenoid valve is provided, which is used to control the opening and closing of the return oil pipeline between the gas-liquid separation tank and the oil tank area. The first solenoid valve opens the return oil pipeline after receiving a first start signal or a second start signal, and closes the return oil pipeline when receiving a first closing signal and a second closing signal at the same time.

[0009] In one embodiment, it further includes:

[0010] At least two condensing units are installed at the gas outlet of the oil tank area;

[0011] Obtain the condensing oil temperature at the outlet of each condensing unit;

[0012] If the condensing oil temperature exceeds a preset condensing threshold, the valves between the multiple condensing units are switched so that the multiple condensing units operate in series;

[0013] If the condensing oil temperature is lower than a preset condensing threshold, the valves between the multiple condensing units are switched so that the condensing units operate individually;

[0014] Through this embodiment, at least two condensing units can be connected in parallel or in series with each other, that is, when the condensing oil temperature at the outlet end reaches the requirement, the oil circuit can be changed so that the outlet end directly discharges oil without having to operate in series with another condensing unit, which makes it convenient for the remaining non-working condensing units to be shut down for a rest, avoiding long-term operation affecting their lifespan. If the condensing oil temperature at its outlet end does not meet the requirement, the oil circuit is changed so that the oil and gas at the outlet end enter another condensing unit for continued condensation to meet the condensing oil temperature. That is, the multiple condensing units that can be connected in parallel and in series can not only meet the condensation requirements of the system, but also can replace each other to work, thereby increasing the service life of the system.

[0015] In one embodiment, it further includes:

[0016] A recovery branch connected to the condensing unit is provided at the adsorption membrane outlet at the rear end of the gas-liquid separation tank, and a solenoid valve is provided on the exhaust pipe at the adsorption membrane outlet. The solenoid valve is closed when the system stops working to recover the residual oil and gas in the pipeline when the working flow is alternated;

[0017] Through this embodiment, since the tertiary oil and gas recovery system of the gas station is not always in working condition, it is started as needed and enters standby state after the work is completed. The inventor found that after one workflow is completed, when the next workflow is just started, the residual oil and gas in the pipeline will be quickly discharged into the atmosphere at the time of startup. At this time, the pollutant concentration will be much greater than the emission requirements. That is, through the set solenoid valve and recovery branch, when the workflow alternates, the residual oil and gas in the pipeline will be recovered to the condensing unit for condensation recovery, which greatly improves the environmental protection performance of the gas station.

[0018] In one embodiment, it further includes:

[0019] Obtaining the outlet oil and gas concentration at the outlet end of the adsorption membrane;

[0020] If the oil and gas concentration at the outlet is continuously greater than the concentration threshold for more than a preset time, the adsorption membrane is determined to be invalid and a replacement signal is output;

[0021] Through this embodiment, the adsorption performance of the adsorption membrane is greatly reduced after working for a long time. When it fails to meet the filtration requirements, it needs to be replaced. Most of the current oil and gas recovery systems replace the adsorption membrane manually on a regular basis. However, due to the uncertainty of the working time of the recovery system, when it is replaced after it fails, the pollutants discharged during this period will inevitably fail to meet the emission requirements. If it is replaced before it fails, there will be waste. That is, by detecting the outlet oil and gas concentration at the outlet end of the adsorption membrane, when it continues to exceed the threshold concentration for a preset time, it is determined that the adsorption membrane has failed, and a replacement signal is output to remind the operator to replace the adsorption membrane in time.

[0022] In one embodiment, it further includes:

[0023] Obtaining the oil and gas pressure value of the oil return pipeline between the oil tank area and the condensing unit;

[0024] If the oil and gas pressure value exceeds 150Pa, the recovery system is started to enter the next work flow;

[0025] When the system is in working condition, if the oil and gas pressure value is lower than 50Pa, the recovery system is shut down;

[0026] Through this implementation, the oil and gas pressure value of the oil return pipeline is used as the start and stop standard of the recovery system, which meets the oil and gas recovery needs while reducing the energy consumption of the system.

[0027] The present invention also provides a tertiary oil and gas recovery system for a gas station, comprising a condensing device, wherein the inlet end of the condensing device is connected to the oil tank area via an air inlet pipeline, and the outlet end of the condensing device is connected to the oil tank area via an oil return pipeline to form a recovery pipeline, wherein the oil return pipeline is further provided with a gas-liquid separation tank;

[0028] Among them, a first solenoid valve is provided on the oil return pipeline between the gas-liquid separation tank and the oil tank area, and a liquid level and temperature integrated sensor is provided in the gas-liquid separation tank. The first solenoid valve is electrically connected to the liquid level and temperature integrated sensor, so that when the temperature or liquid level in the gas-liquid separation tank reaches a preset target, the first solenoid valve is connected to the recovery pipeline.

[0029] In one embodiment, the condensing device includes a plurality of condensing units connected in parallel, each condensing unit having an outlet end provided with a temperature sensor, each condensing unit having an outlet end provided with a first electronic switching valve connected to the oil return line, the first electronic switching valve being electrically connected to the temperature sensor;

[0030] Through this embodiment, multiple condensing units connected in parallel are switched for use to improve the service life of the condensing units. At the same time, a temperature sensor is provided to detect the temperature of the oil and gas after condensation. When it does not meet the requirements, the oil circuit is changed through the first electronic switching valve, so that the oil and gas are condensed again through another condensing unit, thereby ensuring the oil and gas condensation effect while improving the service life of the condensing unit.

[0031] In one embodiment, the gas-liquid separation tank is further connected to an adsorption membrane, the outlet end of the adsorption membrane is connected to the outside atmosphere through an exhaust pipe to discharge residual oil and gas, a recovery branch connected to the condensing device is provided on the exhaust pipe, a second electronic switching valve is provided between the recovery branch and the exhaust pipe, an oil and gas concentration sensor is provided between the adsorption membrane and the second electronic valve, and the oil and gas concentration sensor is electrically connected to the second electronic switching valve;

[0032] Through this embodiment, the recovery branch provided can, on the one hand, send the oil and gas remaining in the pipeline to the condensing unit for continued condensation recovery when the work flow of the recovery system alternates, thereby preventing it from being quickly discharged to the outside when a new work flow is started, resulting in pollutant concentrations far exceeding the requirements and causing damage to the environment. On the other hand, it can also detect the oil and gas concentration at the outlet end by the oil and gas concentration sensor when key components malfunction or fail, such as when the adsorption membrane fails. That is, when it does not meet the requirements, the second electronic switching valve is used to change the path of the oil and gas and send it to the condensing device for further condensation recovery, thereby ensuring that the concentration of pollutants discharged when the system is in a work flow alternation or key component failure can still meet the requirements.

[0033] In one embodiment, a second solenoid valve is provided on the exhaust pipeline, a third solenoid valve is provided on the intake pipeline, a pressure sensor is further provided on the intake pipeline between the third solenoid valve and the oil tank area, and the second solenoid valve and the third solenoid valve are electrically connected to the pressure sensor;

[0034] Through this embodiment, the second solenoid valve and the third solenoid valve are opened and closed as the system is opened and closed. On the one hand, they protect the key components in the system, and on the other hand, they can prevent the residual oil and gas in the pipeline from being directly discharged to the outside without treatment, polluting the environment.

[0035] In one embodiment, the air intake pipeline between the oil tank area and the condensing device is connected to the recovery branch, and a one-way valve is provided on the air intake pipeline between the first solenoid valve and the recovery branch;

[0036] Through this embodiment, the air intake pipeline is connected to the recovery branch, so that the recovered oil and gas can be mixed with the oil and gas coming out of the oil storage area and then enter the condensing device for condensation recovery, avoiding the need for a new condensing device due to the separate recovery of the recovered oil and gas. At the same time, since the condensation efficiency of the recovered oil and gas is low when condensed alone, the energy consumption of the recovery system is reduced. At the same time, the one-way valve arranged on the air intake pipeline between the first solenoid valve and the recovery branch can prevent the recovered oil and gas and / or the oil and gas remaining in the pipeline when the working flow is alternated from returning to the oil storage area.

[0037] The beneficial effects of the present invention are:

[0038] The opening and closing of the return oil pipeline is controlled according to the temperature or liquid level in the gas-liquid separation tank to prevent the low-temperature condensed oil from impacting the crude oil in the oil storage tank. This not only improves the quality and efficiency of the condensed oil return from the gas station, but also increases the service life of the gas station system. The multiple condensing units that can be connected in parallel and series can not only meet the condensation requirements of the system, but also can replace each other to increase the service life of the system. The solenoid valve and the recovery branch are set so that when the working flow alternates, the oil and gas remaining in the pipeline will be recovered to the condensing unit for condensation recovery, which greatly improves the environmental protection performance of the gas station. The failure of the adsorption membrane can be judged in a timely and accurate manner, which does not affect the emission situation and does not waste the adsorption membrane. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The present invention will be described in more detail below based on embodiments and with reference to the accompanying drawings, wherein:

[0040] Figure 1 Shows a schematic structural diagram of the recovery system of the present invention;

[0041] Figure 2 Shown is a control flow chart of the recovery method of the present invention;

[0042] In the drawings, like reference numerals are used for like parts, but the drawings are not necessarily true to scale.

[0043] Reference numerals:

[0044] 11-pressure sensor, 101-first condensing unit, 102-second condensing unit, 31-first temperature sensor, 32-second temperature sensor, 33-liquid level temperature integrated sensor, 41-concentration sensor, 51-manual valve, 61-third solenoid valve, 62-second solenoid valve, 63-first solenoid valve, 71-second flow meter, 72-third flow meter, 73-first flow meter, 81-first one-way valve, 82-second one-way valve, 91-first flame arrester, 92-second flame arrester. DETAILED DESCRIPTION

[0045] The present invention will be further described below with reference to the accompanying drawings.

[0046] The present invention provides a tertiary oil and gas recovery system for a gas station, comprising a condensing device, the inlet end of which is connected to the oil tank area via an air inlet pipeline, and the outlet end of which is connected to the oil tank area via an oil return pipeline to form a recovery pipeline, wherein a gas-liquid separation tank is also provided on the oil return pipeline;

[0047] A first solenoid valve 63 is provided on the oil return pipeline between the gas-liquid separation tank and the oil tank area. A liquid level and temperature integrated sensor is provided in the gas-liquid separation tank. The first solenoid valve 63 is electrically connected to the liquid level and temperature integrated sensor so that when the temperature or liquid level in the gas-liquid separation tank reaches a preset target, the first solenoid valve 63 is connected to the recovery pipeline.

[0048] It should be noted that, in this embodiment, the inventors found that the temperature of the oil after condensation recovery is relatively low. When it returns to the oil storage area after passing through the gas-liquid separation tank, it is easy to impact the crude oil and affect the crude oil. That is, a liquid level temperature sensor is set in the gas-liquid separation tank, and the gas-liquid separation tank is used as a temporary storage tank for the condensed oil. After its temperature is close to the crude oil temperature (5°C), it is discharged to the oil storage area. At the same time, in this embodiment, when the oil stored in the gas-liquid separation tank as a temporary storage tank exceeds half of its own liquid level, even if the oil temperature in the gas-liquid separation tank is not close to the crude oil temperature, it will still be discharged to the oil storage tank. On the one hand, when the condensed oil in the gas-liquid separation tank is When there is too much condensate, the temperature of the condensed oil in the tank is unlikely to change significantly. On the other hand, excessive condensate that is not close to the crude oil temperature is prevented from causing a greater impact on the crude oil in the oil storage area. That is, the opening and closing of the return oil pipeline is controlled according to the temperature or liquid level in the gas-liquid separation tank to prevent the low-temperature condensate from impacting the crude oil in the oil storage tank. This not only improves the quality and efficiency of the condensed oil return from the gas station, but also increases the service life of the gas station system. At the same time, the operation of the first solenoid valve 63 is only related to the output signal of the liquid level and temperature integrated sensor, and is not related to the opening and closing of the entire system, thereby ensuring the quality of the return oil and the safety of the system.

[0049] Specifically, if Figure 1 As shown, the condensing device includes a first condensing unit 101 and a second condensing unit 102. The outlet end of the first condensing unit 101 is provided with a first temperature sensor 31, and the outlet end of the second condensing unit 102 is provided with a second temperature sensor 32. The first temperature sensor 31 and the second temperature sensor 32 are used to detect the temperature of the oil after condensation by the condensing unit. The first condensing unit 101 and the second condensing unit 102 can be connected in parallel or in series. Figure 1 As shown, the connection relationship between the first condensing unit 101 and the second condensing unit 102 can be controlled by changing the connection state of the electronic three-way valve 21, 22, 23, 24, 25 or 26, as shown in FIG. Figure 1 The state of the first condensing unit 101 and the second condensing unit 102 being connected in series is shown. That is, when the first temperature sensor 31 detects that the outlet oil temperature does not reach -30°C, the first condensing unit 101 and the second condensing unit 102 are connected in series by changing the electronic three-way valve, so that the oil and gas that do not meet the standard enter the second condensing unit 102 for further condensation and then are sent to the gas-liquid separation tank. If the outlet oil temperature detected by the first temperature sensor 31 reaches -30°C, the oil and gas are directly sent to the gas-liquid separation tank without the second condensing unit 102 operating. Similarly, The second condensing unit 102 serves as the main unit. By changing the connection state of the electronic three-way valve, the outlet oil and gas enter the second condensing unit 102. According to the temperature of the outlet oil and gas detected by the second temperature sensor 32, the electronic three-way valve is changed to connect it to the first condensing unit 101 or the gas-liquid separator. This is also applicable to the case of multiple condensing units. That is, in this embodiment, the performance of multiple condensing units is fully utilized. Under the condition of ensuring the outlet oil temperature, it can not only save condensing energy consumption, but also extend the service life of the units and reduce maintenance frequency.

[0050] In one embodiment, Figure 1 As shown, the gas-liquid separation tank is further connected to an adsorption membrane, the outlet end of the adsorption membrane is connected to the outside atmosphere through an exhaust pipe to discharge residual oil and gas, a recovery branch connected to the condensing device is provided on the exhaust pipe, a second electronic switching valve is provided between the recovery branch and the exhaust pipe, an oil and gas concentration sensor 41 is provided between the adsorption membrane and the second electronic valve, and the oil and gas concentration sensor 41 is electrically connected to the second electronic switching valve;

[0051] It should be noted that, on the one hand, the recovery branch can send the oil and gas remaining in the pipeline to the condensing unit for further condensation recovery when the work flow of the recovery system is alternated, so as to avoid it being quickly discharged to the outside when the new work flow is started, resulting in the pollutant concentration far exceeding the requirements and causing damage to the environment. On the other hand, it can also detect the oil and gas concentration at the outlet end by the oil and gas concentration sensor 41 when key components fail or fail, such as when the adsorption membrane fails. That is, when it does not meet the requirements, the path of the oil and gas is changed through the second electronic switching valve, and it is sent to the condensing device for further condensation recovery, ensuring that the concentration of pollutants discharged when the system is in the work flow alternation or key component failure can still meet the requirements.

[0052] In one embodiment, a second solenoid valve 62 is provided on the exhaust pipe, and a third solenoid valve 61 is provided on the intake pipe. A pressure sensor 11 is also provided on the intake pipe between the third solenoid valve 61 and the oil tank area. The second solenoid valve 62 and the third solenoid valve 61 are electrically connected to the pressure sensor 11. That is, in this embodiment, the opening and closing of the recovery system is controlled by detecting the pressure in the intake pipe, which ensures its safe operation while reducing the energy consumption of the system and improving the recovery efficiency. The second solenoid valve 62 and the third solenoid valve 61 are opened and closed as the system is opened and closed. On the one hand, they protect the key components of the system, and on the other hand, they can prevent the residual oil and gas in the pipeline from being directly discharged to the outside without treatment, thereby polluting the environment.

[0053] In one embodiment, the air intake pipeline between the oil tank area and the condensing device is connected to the recovery branch, and a one-way valve is provided on the air intake pipeline between the first solenoid valve 63 and the recovery branch. That is, in this embodiment, the air intake pipeline is connected to the recovery branch so that the recovered oil and gas can be mixed with the oil and gas coming out of the oil storage area and then enter the condensing device for condensation recovery, thereby avoiding the need for a new condensing device for recovering the recovered oil and gas separately. At the same time, since the condensation efficiency of the recovered oil and gas is low when condensed separately, the energy consumption of the recovery system is reduced. At the same time, the one-way valve provided on the air intake pipeline between the first solenoid valve 63 and the recovery branch can prevent the recovered oil and gas and / or the oil and gas remaining in the pipeline during the alternation of working flows from returning to the oil storage area.

[0054] Further, if Figure 1 As shown, a first flame arrester 91 is provided at the outlet end of the oil tank area, and a second flame arrester 92 is provided at the inlet end thereof to ensure the safety of the gas station;

[0055] Specifically, if Figure 1 As shown, a sampling port is also provided on the exhaust pipeline, and a manual valve 51 is provided between the sampling port and the exhaust pipeline. That is, when it is necessary to test or record and analyze the recovery performance of the system, the manual valve 51 can be opened to facilitate sampling of oil and gas samples at the outlet end of the exhaust pipeline for testing;

[0056] In one embodiment, Figure 1 As shown, a first flow meter 73 is provided on the air inlet pipeline between the oil tank area and the condensing device, a second flow meter 71 is provided on the air exhaust pipeline, and a third flow meter 72 is provided on the recovery pipeline between the gas-liquid separator and the oil tank area. This is to calculate the total oil and gas output, recovery volume, and emission volume in the recovery system, making it easier for staff to understand the working status of the system and to calculate the amount of carbon emissions reduced.

[0057] Specifically, the first condensing unit 101 and the second condensing unit 102 are both filled with HFO-1336mzz(Z), an environmentally friendly refrigerant. HFO-1336mzz(Z) can be used directly in its pure form in the refrigeration system, or it can form an azeotropic refrigerant with HFO-1234ze(Z) at a specific ratio and concentration at a certain temperature. The azeotropic refrigerant has a fixed boiling point at a given pressure within a range of -40 to 120°C and has stable physical properties.

[0058] In one embodiment, the oil tank area includes 98# oil tank, 95# oil tank and 92# oil tank, the air inlet pipeline is set at the outlet end of 98# oil tank, and the recovery pipeline between the gas-liquid separation tank and the oil tank area is connected to 92# oil tank;

[0059] In one embodiment, the present invention also provides a three-stage oil and gas recovery method for a gas station, such as Figure 2 As shown, the following steps are included:

[0060] S1. Obtain the pressure in the oil and gas outlet pipeline. If it is greater than 150 Pa, start the condensing device.

[0061] S2. Select any condensing unit to operate and obtain the oil and gas temperature at its outlet;

[0062] If the temperature is less than -30°C, the condensed oil and gas will be passed into the gas-liquid separation area;

[0063] If the temperature is not less than -30℃, the oil and gas at the outlet will continue to be fed into other condensing units for condensation until the oil and gas temperature at the outlet of the condensing unit is less than -30℃.

[0064] S3. Obtain the oil temperature value and the liquid level height ratio value in the gas-liquid separation area to open or close the recovery pipeline between the gas-liquid separation tank and the oil tank area;

[0065] Specifically, the oil temperature value in the gas-liquid separation tank is obtained and compared with a preset temperature threshold. If the oil temperature value exceeds the preset temperature threshold, a first start signal is output; if the oil temperature value is less than the preset temperature threshold, a first shut-down signal is output;

[0066] Obtaining a liquid level height ratio value in the gas-liquid separation tank, comparing it with a preset height ratio threshold, and outputting a second start signal if it exceeds the preset height ratio threshold; and outputting a second shut-down signal if it is less than the preset height ratio threshold;

[0067] A first solenoid valve is provided on the oil recovery pipeline, the first solenoid valve opens the oil return pipeline after receiving the first start signal or the second start signal, and closes the oil return pipeline when receiving the first closing signal and the second closing signal at the same time;

[0068] Specifically, when the temperature in the gas-liquid separation tank is less than 5°C, a first closing signal is output; when the liquid level in the gas-liquid separation tank is less than 1 / 2 of its own level, a second closing signal is output, that is, the return oil pipeline is closed at this time, and no recovered oil enters the oil storage area; and when the temperature in the gas-liquid separation tank is greater than 5°C or the liquid level exceeds 1 / 2 of its own level, the return oil pipeline is opened to discharge the recovered oil in the gas-liquid separation tank into the oil storage area;

[0069] S4. A recovery branch is set at the outlet of the oil and gas adsorption membrane and connected to the condensing unit to recover and process the oil and gas remaining in the pipeline when the system is in the working flow alternation to avoid environmental pollution. At the same time, when the failure or malfunction of important components in the system causes abnormal emission, the oil and gas emission can be suspended and recovered to the condensing device;

[0070] In the description of the present invention, it should be understood that the terms "upper", "lower", "bottom", "top", "front", "back", "inside", "outside", "left", "right", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention.

[0071] Although the present invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely illustrative of the principles and applications of the invention. It should be understood that many modifications may be made to the illustrative embodiments, and that other arrangements may be devised, without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in ways other than those described in the original claims. It should also be understood that features described in conjunction with individual embodiments may be employed in conjunction with other described embodiments.

Claims

1. A tertiary oil and gas recovery method for a gas station, characterized in that: include: Obtaining the oil temperature value in the gas-liquid separation tank, comparing it with a preset temperature threshold, and outputting a first start signal if the oil temperature exceeds the preset temperature threshold; and outputting a first shut-down signal if the oil temperature is less than the preset temperature threshold; Obtaining a liquid level height ratio value in the gas-liquid separation tank, comparing it with a preset height ratio threshold, and outputting a second start signal if the liquid level height ratio value exceeds the preset height ratio threshold; and outputting a second shut-down signal if the liquid level height ratio value is less than the preset height ratio threshold; A first solenoid valve is provided, which is used to control the opening and closing of the return oil pipeline between the gas-liquid separation tank and the oil tank area. The first solenoid valve opens the return oil pipeline after receiving a first start signal or a second start signal, and closes the return oil pipeline when receiving a first closing signal and a second closing signal at the same time.

2. A tertiary oil and gas recovery method for a gas station according to claim 1, characterized in that: Also includes: At least two condensing units are installed at the gas outlet of the oil tank area; Obtain the condensing oil temperature at the outlet of each condensing unit; If the condensing oil temperature exceeds a preset condensing threshold, the valves between the multiple condensing units are switched so that the multiple condensing units operate in series; If the condensing oil temperature is lower than a preset condensing threshold, valves between the multiple condensing units are switched so that the condensing units operate individually.

3. The tertiary oil and gas recovery method for a gas station according to claim 2, characterized in that: Also includes: A recovery branch connected to the condensing unit is set at the adsorption membrane outlet end at the rear end of the gas-liquid separation tank, and a solenoid valve is set on the exhaust pipe at the adsorption membrane outlet end. The solenoid valve is closed when the system stops working to recover the residual oil and gas in the pipeline when the working flow is alternated.

4. The tertiary oil and gas recovery method for a gas station according to claim 3, characterized in that: Also includes: Obtaining the outlet oil and gas concentration at the outlet end of the adsorption membrane; If the outlet oil and gas concentration continues to be greater than the concentration threshold for more than a preset time, it is determined that the adsorption membrane has failed and a replacement signal is output.

5. The tertiary oil and gas recovery method for a gas station according to claim 3, characterized in that: Also includes: Obtaining the oil and gas pressure value of the oil return pipeline between the oil tank area and the condensing unit; If the oil and gas pressure value exceeds 150Pa, the recovery system is started to enter the next work flow; When the system is in working condition, if the oil and gas pressure value is lower than 50Pa, the recovery system is shut down.

6. A tertiary oil and gas recovery system for a gas station, applied to the tertiary oil and gas recovery method for a gas station as claimed in claim 1, characterized in that: It includes a condensing device, the inlet end of the condensing device is connected to the oil tank area through an air inlet pipeline, and the outlet end is connected to the oil tank area through an oil return pipeline to form a recovery pipeline. The oil return pipeline is also provided with a gas-liquid separation tank; Among them, a first solenoid valve is provided on the oil return pipeline between the gas-liquid separation tank and the oil tank area, and a liquid level and temperature integrated sensor is provided in the gas-liquid separation tank. The first solenoid valve is electrically connected to the liquid level and temperature integrated sensor, so that when the temperature or liquid level in the gas-liquid separation tank reaches a preset target, the first solenoid valve is connected to the recovery pipeline.

7. A tertiary oil and gas recovery system for a gas station according to claim 6, characterized in that: The condensing device includes a plurality of condensing units connected in parallel, and a temperature sensor is provided at the outlet end of each condensing unit. The outlet end of each condensing unit is provided with a first electronic switching valve connected to the return oil pipeline, and the first electronic switching valve is electrically connected to the temperature sensor.

8. A tertiary oil and gas recovery system for a gas station according to claim 6 or 7, characterized in that: The gas-liquid separation tank is also connected to an adsorption membrane, and the outlet end of the adsorption membrane is connected to the outside atmosphere through an exhaust pipe to discharge residual oil and gas. A recovery branch connected to the condensing device is provided on the exhaust pipe, and a second electronic switching valve is provided between the recovery branch and the exhaust pipe. An oil and gas concentration sensor is provided between the adsorption membrane and the second electronic switching valve, and the oil and gas concentration sensor is electrically connected to the second electronic switching valve.

9. The tertiary oil and gas recovery system for a gas station according to claim 8, characterized in that: A second solenoid valve is provided on the exhaust pipeline, a third solenoid valve is provided on the intake pipeline, and a pressure sensor is also provided on the intake pipeline between the third solenoid valve and the oil tank area. The second solenoid valve and the third solenoid valve are both electrically connected to the pressure sensor.

10. The tertiary oil and gas recovery system for a gas station according to claim 8, characterized in that: The air intake pipeline between the oil tank area and the condensing device is connected to the recovery branch, and a one-way valve is provided on the air intake pipeline between the first solenoid valve and the recovery branch.

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