A detection device for oil and gas recovery system and its application and detection method

Abstract

The present invention discloses a detection device for an oil and gas recovery system and its application and detection method. The detection device includes a nitrogen supply device, a pipeline for an oil and gas recovery system, an oil and gas separation tank, a liquid level meter, a liquid flow meter, a gas flow meter and an automatic control system; the oil and gas mixture inlet of the oil and gas separation tank is connected with a cyclone, and the oil and gas separation tank includes a lower tank for receiving liquid and an upper tank for receiving gas; the lower tank is connected to the liquid flow meter and the liquid level meter respectively, and the upper tank is connected to the gas flow meter. The device combines the original airtightness detector, liquid resistance detector and gas-liquid ratio detector into one, which reduces the system volume and mass while also reducing the cost. The detection method of the present invention can detect the airtightness, liquid resistance and gas-liquid ratio of the oil and gas recovery system, separate gas and liquid through the cyclone, and improve the accuracy of the gas-liquid ratio. The device can be used in the oil and gas recovery system of a gas station, the oil and gas recovery system of a tank truck and the oil and gas recovery system of an oil depot.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas recovery system detection, and in particular to an oil and gas recovery system detection device and an application and a detection method thereof. Background Art

[0002] Oil and gas recovery is an energy-saving and environmentally friendly high-tech in the field of petrochemicals. The application of oil and gas recovery technology can recover the oil and gas emitted during the storage, transportation and loading and unloading of oil products, prevent air pollution caused by oil and gas volatilization, eliminate safety hazards, improve energy utilization, reduce economic losses, and thus obtain considerable economic benefits.

[0003] The three limit indicators of tightness, liquid resistance and gas-liquid ratio are the key technologies and important evaluation data for controlling oil and gas emissions and identifying the oil and gas recovery effect of the oil and gas recovery system. However, whether it is the detection system of the European and American oil and gas recovery system or the ISD oil and gas online monitoring system, only some indicators can be detected, and only the oil tank pressure and the gas-liquid ratio of the refueling gun can be detected. The function is single. The flow measurement method used in the first two is the interception measurement method. During the measurement, the pressure loss is large and the error is relatively large. Although the online monitoring system can detect the corresponding indicators in real time, timely discover faults in the recovery system, and better improve the efficiency of oil and gas recovery, it is costly and expensive, and can only be used for monitoring gas stations that are already in operation. Summary of the invention

[0004] In order to overcome the shortcomings of the prior art, one of the objects of the present invention is to provide a detection device for an oil and gas recovery system, which can simultaneously detect the airtightness, liquid resistance and gas-liquid ratio of the oil and gas recovery system, and can also reduce the error of the gas-liquid ratio result; the second object of the present invention is to provide a detection method for an oil and gas recovery system, which can simultaneously detect the airtightness, liquid resistance and gas-liquid ratio, separate gas and liquid through a cyclone, and improve the accuracy of the gas-liquid ratio; the third object of the present invention is to provide an application of a detection device for an oil and gas recovery system.

[0005] One of the purposes of the present invention is achieved by the following technical solution:

[0006] A detection device for an oil and gas recovery system, comprising a nitrogen supply device, a pipeline for an oil and gas recovery system, an oil and gas separation tank, a liquid level meter, a liquid flow meter, a gas flow meter and an automatic control system; the oil and gas outlet of the pipeline is connected to the oil and gas inlet of the oil and gas separation tank, the gas outlet of the nitrogen supply device is connected to the gas inlet of the pipeline; the gas outlet of the pipeline is connected to a liquid resistance pressure gauge and a pressure sensor;

[0007] The oil-gas mixture inlet of the oil-gas separation tank is connected to a cyclone, and the oil-gas separation tank includes a lower tank for receiving liquid and an upper tank for receiving gas; the lower tank is connected to a liquid flow meter and a liquid level meter respectively, and the upper tank is connected to a gas flow meter; the automatic control system is electrically connected to the oil-gas analysis device, the oil-gas separation tank, the liquid level meter, the liquid flow meter and the gas flow meter respectively.

[0008] Furthermore, the detection device of the oil and gas recovery system also includes a differential pressure sensor and a temperature sensor. The pipeline, the temperature sensor and the differential pressure sensor are connected in sequence. The differential pressure sensor and the temperature sensor are both electrically connected to the automatic control system.

[0009] Furthermore, the detection device of the oil and gas recovery system also includes a droplet catcher, which is arranged inside the upper tank. The droplet catcher is used to separate the water mist component contained in the gas, improve the purity of the gas, and thus improve the accuracy of the gas-liquid ratio result.

[0010] Furthermore, the detection device of the oil and gas recovery system also includes a defoamer, which is arranged inside the lower tank. The defoamer uses centrifugal force to break the foam generated during the separation process to separate the gas and liquid. The shear force provided by the high-speed rotating module quickly breaks the bubbles. The liquid released by the bubbles is immediately thrown to the wall by the centrifugal force and compressed into a liquid flow to return to the lower tank, thereby reducing the loss of escaped liquid.

[0011] Furthermore, the detection device of the oil and gas recovery system also includes a nitrogen valve and an oil and gas inlet valve, the nitrogen valve is arranged between the nitrogen supply device and the pipeline, and the oil and gas valve is arranged between the pipeline and the oil and gas separation tank.

[0012] Furthermore, the detection device of the oil and gas recovery system also includes a pressure relief valve, which is arranged on the pipeline.

[0013] Furthermore, the detection device of the oil and gas recovery system also includes an alarm device, and the alarm device is connected to the automatic control system.

[0014] The second object of the present invention is achieved by adopting the following technical solution:

[0015] A detection method for an oil and gas recovery system, based on the above-mentioned detection device for an oil and gas recovery system, comprises the following steps:

[0016] 1) Check the tightness of the pipeline: The nitrogen supply device fills the pipeline with nitrogen, and the pressure sensor detects the pressure change value within the specified time, and transmits the result to the automatic control system in the form of an electrical signal. If the measured pressure change value is greater than the maximum residual pressure limit, it means that the tightness of the pipeline meets the standard; if the sealing of the pipeline does not meet the standard, the alarm device is turned on to notify the technicians to check for leakage;

[0017] 2) Detect the liquid resistance of the pipeline: the nitrogen supply device fills the pipeline with a specified amount of nitrogen, uses a liquid resistance pressure gauge to detect the liquid resistance of nitrogen passing through the pipeline, and transmits the result to the automatic control system in the form of an electrical signal. If the measured pressure value is less than the maximum pressure limit, it means that the liquid resistance does not affect the oil and gas recovery; if the liquid resistance of the pipeline does not meet the standard, it means that the pipeline is blocked and not smooth, then the alarm device is turned on to notify the technicians to dredge the pipeline; when testing the tightness and liquid resistance of the pipeline, stop passing the oil and gas mixture into the pipeline;

[0018] 3) The oil-gas mixture enters the oil-gas separation tank, where it is separated into gas and liquid through a cyclone. The gas enters the upper tank and the liquid enters the lower tank.

[0019] 4) The liquid entering the lower tank passes through the liquid flow meter and liquid level meter to obtain the liquid flow and liquid level parameters, and transmit the data to the automatic control system in the form of electrical signals;

[0020] 5) The gas entering the upper tank passes through the gas flow meter, which measures the gas flow and transmits the data to the automatic control system in the form of electrical signals;

[0021] 6) The automatic control system calculates the gas-liquid ratio based on the liquid flow obtained in step 4) and the gas flow obtained in step 5). If the gas-liquid ratio is within the specified range, it complies with the regulations.

[0022] Furthermore, in step 3), the oil-gas mixture passes through a temperature sensor and a pressure difference sensor before entering the oil-gas separation tank, and transmits data to an automatic control system. In step 6), after calculating the gas-liquid ratio, the automatic control system combines the relationship between temperature, pressure and gas-liquid ratio to obtain a corrected gas-liquid ratio.

[0023] The third object of the present invention is achieved by adopting the following technical solution:

[0024] An application of a detection device for an oil and gas recovery system as described above, wherein the oil and gas recovery detection device is applied to an oil and gas recovery system of a gas station, an oil tanker recovery system, and an oil and gas recovery system of an oil depot.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) The detection device of the oil and gas recovery system of the present invention is used to detect the working condition of the oil and gas recovery system. It combines the original airtightness detector, liquid resistance detector and gas-liquid ratio detector into one, and adopts the same automatic control system for control. While reducing the volume and mass of the system, it also reduces the cost, and different positions can be selected for detection. The specific principle is: by detecting that the nitrogen supply device pumps nitrogen into the pipeline, the liquid resistance of the pipeline is measured by the liquid resistance pressure gauge, and it is determined whether the pipeline liquid resistance parameters meet the standards. Or after nitrogen is passed into nitrogen, the pressure value change value within the specified time is detected by the pressure sensor. If the change value is greater than the minimum residual pressure limit, it means that the airtightness is good. After it is determined that the liquid resistance and airtightness meet the standards, the oil-gas mixture is passed from the pipeline into the oil-gas separation tank, the cyclone separates the gas and liquid in the oil-gas mixture, the gas enters the upper tank, the liquid enters the lower tank, the gas in the upper tank passes through the gas flowmeter to obtain the gas flow; the liquid in the lower tank passes through the liquid flowmeter to obtain the liquid flow; then the automatic control system calculates the gas-liquid ratio according to the gas flow and the liquid flow, so as to obtain whether the gas-liquid ratio meets the standards; the detection device of the present invention can be used to test dynamic flow and critical flow, the cyclone can accelerate the flow of liquid, reduce the pressure loss caused by local resistance such as valve ports, elbows, flow section changes, etc., and can reduce liquid friction or avoid local energy loss caused by particle collision; then the gas and liquid are separated and their flow rates are measured respectively to reduce the error of the measured gas-liquid ratio.

[0027] (2) The detection device of the oil and gas recovery system of the present invention is also provided with an alarm device. If the automatic control system detects that the liquid resistance and / or the gas-liquid ratio do not meet the requirements, the alarm device is activated to indicate leakage of the detection pipeline.

[0028] (3) The detection device of the oil and gas recovery system of the present invention also includes a pressure difference sensor and a temperature sensor. When the oil and gas mixture enters the oil and gas separation tank, the pressure and temperature of the oil and gas mixture are detected and the data is transmitted to the automatic control system. The automatic control system corrects the value of the gas-liquid ratio according to the relationship between pressure, temperature and flow rate, reduces the error of the gas-liquid ratio caused by temperature and pressure, and improves the accuracy of the result.

[0029] (4) The detection method of the present invention is to pump nitrogen into the pipeline through a nitrogen supply device, and then calculate the real-time liquid resistance of the pipeline through a liquid resistance pressure gauge, or use a pressure sensor to detect the pressure change value within a specified time, so as to determine whether the pipeline of the oil and gas recovery system meets the standards of liquid resistance and sealing. After meeting the standards of liquid resistance and sealing, the oil and gas mixture is separated into gas and liquid through a cyclone, and their flow rates are measured respectively. The gas-liquid ratio is then measured by an automatic control system to determine whether it meets the standards. The detection method of the present invention can be used to detect dynamic flow and critical flow. While separating gas and liquid, the cyclone can also detect the flow of liquid in the lower tank and pipeline, thereby reducing pressure loss and reducing the error of liquid flow, thereby improving the accuracy of the gas-liquid ratio.

[0030] (5) The detection device of the oil and gas recovery system of the present invention can be applied to different locations of the oil and gas recovery system, such as the oil and gas recovery system of a gas station, the oil and gas recovery system of a tank truck, and the oil and gas recovery system of an oil depot. For the oil and gas recovery systems at different locations, the liquid resistance, airtightness, and gas-liquid ratio standards all need to be adaptively adjusted. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a connection schematic diagram of the detection device of the present invention;

[0032] Figure 2 This is a connection diagram of the detection device of Example 1;

[0033] Figure 3 This is a flow chart of testing airtightness of Example 1;

[0034] Figure 4 This is a flow chart of testing liquid resistance in Example 1. DETAILED DESCRIPTION

[0035] The present invention is further described below in conjunction with the accompanying drawings and specific implementation methods. It should be noted that, under the premise of no conflict, the various embodiments or technical features described below can be arbitrarily combined to form a new embodiment.

[0036] like Figure 1 As shown, the present invention provides a detection device for an oil and gas recovery system, comprising a nitrogen supply device, a pipeline for an oil and gas recovery system, an oil and gas separation tank, a liquid level meter, a liquid flow meter, a gas flow meter and an automatic control system; the oil and gas outlet of the pipeline is connected to the oil and gas inlet of the oil and gas separation tank, the gas outlet of the nitrogen supply device is connected to the gas inlet of the pipeline; the gas outlet of the pipeline is connected to a liquid resistance pressure gauge and a pressure sensor;

[0037] The oil-gas mixture inlet of the oil-gas separation tank is connected to a cyclone, and the oil-gas separation tank includes a lower tank for receiving liquid and an upper tank for receiving gas; the lower tank is connected to a liquid flow meter and a liquid level meter respectively, and the upper tank is connected to a gas flow meter; the automatic control system is electrically connected to the oil-gas analysis device, the oil-gas separation tank, the liquid level meter, the liquid flow meter and the gas flow meter respectively.

[0038] The detection device of the present invention is set based on the existing oil and gas recovery system, and can be divided into: gas station oil and gas recovery system, oil tanker oil and gas recovery system and oil depot oil and gas recovery system according to the different oil and gas recovery locations. Using the oil and gas recovery system to recycle oil and gas is one of the important measures to solve environmental problems, safety problems and energy waste, and the airtightness of the oil and gas recovery system is the key technology for the successful recovery and reuse of oil and gas, so it is necessary to set up a nitrogen supply device to pump in nitrogen, and then use a pressure sensor to check the airtightness of the oil and gas recovery system pipeline. The present invention separates the oil and gas mixture and calculates the gas flow, liquid flow and liquid level respectively. The gas-liquid ratio of the oil and gas recovery system is monitored in real time by the automatic control system, and it can be judged in real time whether the return gas volume, airtightness and liquid resistance of the oil and gas recovery system are qualified. Specifically, the automatic control system includes a pressure sensor module, a display module, a control system module and an alarm system module, which can complete the automation, intelligentization and digital detection of the oil and gas recovery system.

[0039] Furthermore, the detection device of the oil and gas recovery system also includes a differential pressure sensor and a temperature sensor. The pipeline, the temperature sensor and the differential pressure sensor are connected in sequence, and the differential pressure sensor and the temperature sensor are both electrically connected to the automatic control system. It is known that when the temperature is constant, as the pressure increases, the gas state will transform into the liquid state; when the pressure decreases, the liquid state will transform into the gas state. Adding temperature and pressure can obtain a more accurate gas-liquid ratio.

[0040] Furthermore, the detection device of the oil and gas recovery system also includes a droplet catcher, which is arranged inside the upper tank. The droplet catcher is used to separate the water mist component contained in the gas, improve the purity of the gas, and thus improve the accuracy of the gas-liquid ratio result.

[0041] Furthermore, the detection device of the oil and gas recovery system also includes a defoamer, which is arranged inside the lower tank. The defoamer uses centrifugal force to break the foam generated during the separation process to separate the gas and liquid. The shear force provided by the high-speed rotating module quickly breaks the bubbles. The liquid released by the bubbles is immediately thrown to the wall by the centrifugal force and compressed into a liquid flow to return to the lower tank, thereby reducing the loss of escaped liquid.

[0042] Furthermore, the detection device of the oil and gas recovery system also includes a nitrogen valve and an oil and gas inlet valve, the nitrogen valve is arranged between the nitrogen supply device and the pipeline, and the oil and gas valve is arranged between the pipeline and the oil and gas separation tank.

[0043] Furthermore, the detection device of the oil and gas recovery system further comprises a pressure relief valve, which is arranged in the pipeline and used to discharge the nitrogen filled in so as to maintain the gas pressure in the pipeline at normal pressure.

[0044] Furthermore, the detection device of the oil and gas recovery system also includes an alarm device, which is connected to the automatic control system. The alarm device is used to remind the technicians that the airtightness, liquid resistance and gas-liquid ratio do not meet the requirements, so that the technicians can deal with the adverse conditions such as leakage and blockage of the oil and gas recovery system in time.

[0045] Example 1

[0046] A detection device for an oil and gas recovery system, such as Figure 2 As shown, it includes a pipeline for a nitrogen supply device and an oil and gas recovery system, an oil and gas separation tank, a liquid level meter, a liquid flow meter, a gas flow meter, an automatic control system and an alarm device; the oil and gas outlet of the pipeline is connected to the oil and gas inlet of the oil and gas separation tank, and the oil and gas outlet of the pipeline is also connected to a temperature sensor and a pressure difference sensor respectively, and the gas outlet of the nitrogen supply device is connected to the gas inlet of the pipeline; the gas outlet of the pipeline is connected to a liquid resistance pressure gauge and a pressure sensor;

[0047] The oil-gas mixture inlet of the oil-gas separation tank is connected to a cyclone, and the oil-gas separation tank includes a lower tank for receiving liquid and an upper tank for receiving gas; the lower tank is connected to a liquid flow meter and a liquid level meter respectively, and the upper tank is connected to a gas flow meter; the automatic control system is respectively connected to the oil-gas analysis device, the oil-gas separation tank, the liquid level meter, the liquid flow meter, the gas flow meter signal and the alarm device.

[0048] A detection method for an oil and gas recovery system, based on the above-mentioned detection device for an oil and gas recovery system, comprises the following steps:

[0049] 1) Check the tightness of the pipeline: Figure 3 As shown, the nitrogen supply device fills the pipeline with nitrogen to make the pressure in the pipeline reach 500Pa, the automatic control system closes the solenoid valve of the pipeline, and clamps the air inlet pipeline with a pipe clamp. After 5 minutes, the remaining pressure value is detected by the pressure sensor and compared with the minimum remaining pressure limit in Table 2 of GB20952-2007. If it is lower than the limit, it means that the leakage degree of the oil and gas recovery system exceeds the allowable range, and the alarm device is turned on to notify the technicians to check the leakage; otherwise, it means that the leakage meets the standard;

[0050] 2) Detect the liquid resistance of the pipeline: Figure 4As shown, the nitrogen supply device fills the pipeline with a specified amount of nitrogen, uses a liquid resistance pressure gauge to detect the liquid resistance of nitrogen passing through the pipeline, and transmits the result to the automatic control system in the form of an electrical signal. If the measured pressure value is less than the maximum pressure limit, it means that the liquid resistance does not affect the oil and gas recovery; if the liquid resistance of the pipeline does not meet the standard, it means that the pipeline is blocked and unobstructed, then the alarm device is turned on to notify the technicians to dredge the pipeline; wherein, when testing the tightness and liquid resistance of the pipeline, stop passing the oil and gas mixture into the pipeline;

[0051] 3) The oil-gas mixture passes through the temperature sensor and the pressure sensor, and detects the temperature and pressure parameters of the oil-gas mixture, and transmits them to the automatic control system in the form of electrical signals;

[0052] 4) The oil-gas mixture enters the oil-gas separation tank, where it is separated into gas and liquid by a cyclone. The gas enters the upper tank, where it passes through a dropper to remove moisture from the gas. The liquid enters the lower tank, where it passes through a defoamer to reduce the loss of liquid caused by the generation of foam.

[0053] 5) The liquid entering the lower tank passes through the liquid flow meter and liquid level meter to obtain the liquid flow and liquid level parameters, and transmit the data to the automatic control system in the form of electrical signals;

[0054] 6) The gas entering the upper tank passes through the gas flow meter, which measures the gas flow and transmits the data to the automatic control system in the form of electrical signals;

[0055] 7) The automatic control system calculates the gas-liquid ratio based on the liquid flow rate obtained in step 5) and the gas flow rate obtained in step 6), and then combines the temperature and pressure of the oil-gas mixture obtained in step 3) to calculate the gas-liquid ratio through the ideal gas state equation PV=nRT (p is pressure (Pa), V is gas volume (m 3 ), T is the temperature (K), n is the amount of gas (mol), R is the molar gas constant (also called the universal gas constant) (J / (mol.K))) and the Bernoulli equation: p+1 / 2pv 2 +pgh=C (where p is the pressure at a point in the fluid, v is the flow velocity at that point, ρ is the fluid density, g is the acceleration due to gravity, h is the height of the point, and C is a constant.) The above two equations are used to verify the difference between the measured liquid flow and gas flow and the calculated liquid flow and gas flow. If the error is greater than 0.2, repeat step 6). If the gas-liquid ratio obtained by the test is within the range of 1.0 to 1.2, it meets the requirements.

[0056] Specifically, liquid resistance refers to the resistance to gas passing through the pipeline caused by condensate liquid retained in the oil and gas pipeline or other reasons. Under specified conditions, it is expressed by the pressure loss value when nitrogen passes through the oil and gas recovery pipeline, and its value should be less than the maximum pressure limit specified in Table 1.

[0057] Table 1 Maximum pressure limit of liquid resistance of gas recovery pipeline in gas station

[0058] Nitrogen flow rate (L / min) Maximum pressure limit / Pa 1818 40 20 90 38 155

[0059] Airtightness refers to the degree of airtightness of the oil and gas recovery system under a certain pressure state, which is expressed by the residual pressure value of the oil tank and oil and gas recovery pipeline under specified conditions. For details, see Table 2 in GB20952-2007.

[0060] The gas-liquid ratio refers to the ratio of the volume of oil and gas collected during refueling to the volume of gasoline added to the tank at the same time. The gas-liquid ratio of various oil and gas recovery systems should be greater than or equal to 1.0 and less than or equal to 1.2, but the test value of the gas-liquid ratio should be within the range given in the technical evaluation report.

[0061] The detection device and method of this embodiment can be applied to the oil and gas recovery system of a gas station, the oil tanker recovery system and the oil and gas recovery system of an oil depot.

[0062] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A detection device for an oil and gas recovery system, characterized in that: It includes a nitrogen supply device, a pipeline, an oil-gas separation tank, a liquid level meter, a liquid flow meter, a gas flow meter and an automatic control system; the oil-gas outlet of the pipeline is connected to the oil-gas inlet of the oil-gas separation tank, the gas outlet of the nitrogen supply device is connected to the gas inlet of the pipeline; the gas outlet of the pipeline is connected to a liquid resistance pressure gauge and a pressure sensor; The oil and gas inlet of the oil and gas separation tank is connected with a cyclone, and the oil and gas separation tank includes a lower tank for receiving liquid and an upper tank for receiving gas; the lower tank is connected with a liquid flow meter and a liquid level meter respectively, and the upper tank is connected with a gas flow meter; the automatic control system is electrically connected with the oil and gas separation tank, the liquid level meter, the liquid flow meter and the gas flow meter respectively; Among them, the detection device of the oil and gas recovery system also includes a pressure difference sensor and a temperature sensor, the pipeline, the temperature sensor and the pressure difference sensor are connected in sequence, and the pressure difference sensor and the temperature sensor are both electrically connected to the automatic control system.

2. The detection device of the oil and gas recovery system according to claim 1, characterized in that: The detection device of the oil and gas recovery system also includes a droplet catcher, which is arranged inside the upper tank.

3. The detection device of the oil and gas recovery system according to claim 1, characterized in that: The detection device of the oil and gas recovery system also includes a defoamer, which is arranged inside the lower tank.

4. The detection device of the oil and gas recovery system according to claim 1, characterized in that: The detection device of the oil and gas recovery system also includes a nitrogen valve and an oil and gas inlet valve. The nitrogen valve is arranged between the nitrogen supply device and the pipeline, and the oil and gas valve is arranged between the pipeline and the oil and gas separation tank.

5. The detection device of the oil and gas recovery system according to claim 1, characterized in that: The detection device of the oil and gas recovery system also includes a pressure relief valve, which is arranged on the pipeline.

6. The detection device of the oil and gas recovery system according to claim 1, characterized in that: The detection device of the oil and gas recovery system also includes an alarm device, and the alarm device is connected to the automatic control system.

7. A method for detecting an oil and gas recovery system, characterized in that: The detection device of the oil and gas recovery system according to any one of claims 1 to 6 comprises the following steps: 1) Check the tightness of the pipeline: the nitrogen supply device fills the pipeline with nitrogen, and the pressure sensor detects the pressure change value within the specified time, and transmits the result to the automatic control system in the form of an electrical signal. If the measured pressure change value is greater than the maximum residual pressure limit, it means that the pipeline tightness meets the standard; 2) Detect the liquid resistance of the pipeline: the nitrogen supply device fills the pipeline with a specified amount of nitrogen, uses a liquid resistance pressure gauge to detect the liquid resistance of nitrogen passing through the pipeline, and transmits the result to the automatic control system in the form of an electrical signal. If the measured pressure value is less than the maximum pressure limit, it means that the liquid resistance does not affect the oil and gas recovery; wherein, when testing the tightness and liquid resistance of the pipeline, stop passing the oil and gas mixture into the pipeline; 3) The oil-gas mixture enters the oil-gas separation tank, and the gas and liquid are separated by the cyclone. The gas enters the upper tank and the liquid enters the lower tank; 4) The liquid entering the lower tank passes through the liquid flow meter and liquid level meter to obtain the liquid flow and liquid level parameters, and transmit the data to the automatic control system in the form of electrical signals; 5) The gas entering the upper tank passes through the gas flow meter, which measures the gas flow and transmits the data to the automatic control system in the form of electrical signals; 6) The automatic control system calculates the gas-liquid ratio based on the liquid flow obtained in step 4) and the gas flow obtained in step 5). If the gas-liquid ratio is within the specified range, it complies with the regulations.

8. The oil vapor recovery system detection method according to claim 7, characterized in that: In step 3), the oil-gas mixture passes through a temperature sensor and a pressure difference sensor before entering the oil-gas separation tank, and transmits data to an automatic control system. In step 6), after calculating the gas-liquid ratio, the automatic control system combines the relationship between temperature, pressure and gas-liquid ratio to obtain a corrected gas-liquid ratio.

9. An application of the detection device of the oil vapor recovery system according to any one of claims 1 to 6, characterized in that: The oil and gas recovery detection device is applied to the oil and gas recovery system of a gas station, a tanker truck recovery system and an oil and gas recovery system of an oil depot.

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