An oil and gas recovery protection system, working process and protection device

Abstract

The application discloses an oil gas recovery protection system, a working process and a protection device, relates to the technical field of oil gas recovery, and comprises an oil gas recovery pump, wherein the suction end of the oil gas recovery pump is connected with an air inlet pipeline, and the exhaust end is connected with an air outlet pipeline; the application further comprises a compensation loop, a protection device is connected in series on the compensation loop, the input end of the protection device is connected with the exhaust end of the oil gas recovery pump through the compensation loop, and the output end is connected with the suction end of the oil gas recovery pump through the compensation loop. The application automatically conducts and forms the gas circulation in the pump under the abnormal high pressure difference condition through the construction of the differential pressure driven self-compensation loop, avoids the dry grinding and blocking of the vacuum pump and the deformation of the oil tank negative pressure, simultaneously maintains the pipeline basic back pressure to prevent the oil gas backflow, integrates the fire blocking structure to realize the bidirectional flame blocking, and significantly improves the system operation stability and the essential safety level.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas recovery technology, and in particular relates to an oil and gas recovery protection system, its working process, and a protection device. Background Technology

[0002] Currently, with the implementation of the China VI emission standard, vehicles are generally equipped with onboard vapor recovery systems (ORVR). During refueling, when a vehicle equipped with an ORVR system uses a regular vapor recovery fuel dispenser, both the vehicle's vapor recovery system and the dispenser's vapor recovery system operate simultaneously. Because the onboard carbon canister in an ORVR vehicle absorbs most of the vapor during refueling, the vapor recovery pump on the dispenser lacks an air intake, causing a sharp increase in the pressure difference between the pump's inlet and outlet. This condition not only reduces vapor recovery efficiency but can also create excessively high negative pressure inside the fuel tank, potentially causing the tank to dent. More seriously, operating the vapor recovery pump under prolonged high-pressure differential stall conditions makes it highly susceptible to wear, overload, and even overheating and fire, posing significant safety hazards and equipment damage risks.

[0003] Moreover, most existing gas stations still use ordinary fuel dispensers. Due to their large number, direct replacement would be costly. Therefore, we designed an oil and gas recovery protection system, its working process, and protection devices to improve existing ordinary fuel dispensers. Summary of the Invention

[0004] To address the problem of existing oil and gas recovery pumps being prone to stalling and damage and posing safety risks during ORVR vehicle refueling, this invention provides an oil and gas recovery protection system, its working process, and a protection device to achieve automatic compensation circulation and safety protection based on pipeline pressure difference.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] An oil and gas recovery protection system includes an oil and gas recovery pump, the suction end of which is connected to an intake pipe and the exhaust end of which is connected to an outlet pipe. It also includes a compensation circuit, on which a protection device is connected in series. The input end of the protection device is connected to the exhaust end of the oil and gas recovery pump through the compensation circuit, and the output end is connected to the suction end of the oil and gas recovery pump through the compensation circuit.

[0007] The above solution establishes a differential pressure self-compensation channel by setting up a compensation circuit with a protection device connected in series between the exhaust and intake ends of the oil and gas recovery pump. When the system is in normal recovery operation, the protection device remains closed, without affecting the main pipeline oil and gas recovery; when the system is in abnormal high differential pressure conditions such as ORVR stall, the protection device responds to the differential pressure and opens the compensation circuit, allowing the gas to circulate within the pump, thereby preventing the pump from dry running and stalling, while maintaining the pipeline foundation back pressure to prevent oil and gas backflow from underground oil tanks.

[0008] Preferably, the free end of the air inlet pipe is connected to the refueling nozzle, and the free end of the air outlet pipe is connected to the underground oil tank.

[0009] This preferred solution clarifies the connection between the system and the refueling terminal and oil storage facilities, ensuring that the compensation circuit can play a role in the complete gas path of the refueling operation, and guaranteeing the gas phase balance and safety of the entire link from the refueling nozzle to the underground oil tank.

[0010] In addition, the present invention also provides a working process based on the above-mentioned oil and gas recovery protection system. When the oil and gas recovery pump is working, if the negative pressure in the intake pipe does not reach the set threshold of the protection device, the protection device will not be activated, and the oil and gas drawn in by the oil and gas recovery pump from the intake pipe will be discharged through the outlet pipe. If the negative pressure in the intake pipe reaches the set threshold, the protection device will be activated, the compensation circuit will be connected, and the oil and gas will enter the compensation circuit from the outlet pipe and then enter the intake pipe, where it will be drawn away by the oil and gas circulation pump and repeatedly circulated until the oil and gas circulation pump stops working.

[0011] The above solution utilizes a negative pressure threshold as the trigger condition for the control logic, enabling automatic switching of the system's operating state. During regular refueling, it maintains the national standard gas-liquid ratio recovery; when refueling an ORVR vehicle causes excessively high negative pressure at the intake end, it automatically activates the compensation circuit to form an internal circulation, protecting the pump body from mechanical damage and avoiding the risk of tank deformation due to complete vacuum. The oil-gas circulation pump mentioned here is the pump component in the system that performs the gas delivery function.

[0012] Preferably, the activation threshold of the protection device is 17-20 kPa.

[0013] This preferred scheme sets the activation threshold above the normal recovery pressure (10-15 kPa) and below the ORVR stall danger pressure (25-60 kPa), ensuring that the valve only opens under abnormal operating conditions that truly require protection, avoiding malfunctions during normal refueling, and guaranteeing the accuracy of oil and gas recovery metering and the stability of system operation.

[0014] Furthermore, the present invention also provides a protective device for the aforementioned oil and gas recovery protection system, comprising a main body, wherein a valve seat, a valve core, and a plug are disposed within the main body, the valve core is located between the plug and the valve seat, and the valve core and the valve seat are sealed together, a spring is disposed between the valve core and the plug, a front base is disposed at one end of the main body, a rear base is disposed at the other end, and a flame arrester is also disposed between the front base and the rear base.

[0015] The above solution integrates mechanical differential pressure sensing with flame arrest and explosion-proof functions. The force balance mechanism composed of valve core and spring can sensitively respond to changes in pipeline differential pressure and realize automatic opening and closing of bypass channel; the flame arresters set at both ends form a double safety barrier, which can effectively block the flame from external backfire or internal friction sparks, thereby improving the inherent safety level of the system in flammable and explosive environments.

[0016] Preferably, the flame arrester is made of ultra-thin stainless steel strip pressed and wound into a columnar structure, the cross-section of which has a spiral structure, and the gap between adjacent layers is 0.4~0.6mm.

[0017] This preferred design utilizes the principle of flame quenching. By strictly controlling the corrugated gap to be smaller than the maximum safe quenching gap for gasoline vapors, the heat is rapidly absorbed by the metal wall as the flame passes through the narrow channel, causing the temperature to drop below the ignition point and extinguish. The vortex structure, while ensuring flame-retardant performance, provides a larger flow area and heat dissipation surface area, reducing airflow resistance and avoiding negative impacts on the pumping synchronization of the variable frequency pump.

[0018] Preferably, a limiting platform is fixedly provided on the valve core, the spring is sleeved on the valve core on one side of the limiting platform, and an inner sealing ring is sleeved on the valve core on the other side of the limiting platform. When the spring is in its natural state, the inner sealing ring is in contact with the valve seat and the limiting platform respectively.

[0019] This preferred design achieves the dual functions of spring positioning and sealing ring clamping through a limiting platform. When the valve is closed, the inner sealing ring fits tightly against the valve seat under the spring preload, ensuring zero leakage in the compensation circuit and maintaining the gas-liquid ratio accuracy under normal recovery conditions. The limiting platform also restricts the spring's compression stroke, preventing overpressure damage to the sealing structure.

[0020] Preferably, an overflow hole is also formed through the plug.

[0021] This preferred design ensures that gas can flow smoothly through the blockage area when the compensation circuit is open, avoiding local throttling or turbulence caused by structural dead angles, reducing pressure loss during internal circulation, and making the pump operate more smoothly.

[0022] Preferably, a connecting cavity is provided on both the front base and the rear base. The main base is connected to the front base and the rear base respectively through the connecting cavity. The flame arrester is located in the connecting cavity and is fixedly connected to the connecting cavity by a snap ring, and its axial direction is the same as the movement direction of the valve core.

[0023] This preferred design employs a modular assembly structure. The flame arrester is secured within the connecting cavity by a snap ring, facilitating subsequent disassembly, cleaning, or replacement and maintenance. The flame arrester's axis is coaxial with the valve core's movement direction, ensuring a straight and smooth airflow path and reducing pressure fluctuations and noise caused by abrupt changes in flow direction.

[0024] Preferably, an outer sealing ring is provided at the joint between the main substrate and the front and rear substrates, and both the inner and outer sealing rings are made of fluororubber FKM or PTFE.

[0025] This preferred solution uses fluororubber FKM or PTFE, which is resistant to gasoline, low temperatures and does not easily swell, as the sealing material. This fundamentally solves the problem that ordinary nitrile rubber is prone to aging and failure after long-term contact with gasoline vapors, leading to leakage. It ensures the sealing reliability and explosion-proof safety of the device throughout its entire life cycle.

[0026] Beneficial effects:

[0027] The oil and gas recovery protection system, its working process, and the protection device provided by this invention automatically sense changes in pipeline operating conditions by constructing a pressure differential-driven self-compensating loop and utilizing the mechanical force balance principle. When refueling of an ORVR vehicle causes an abnormal increase in the negative pressure at the intake end, the protection device automatically activates to form gas circulation within the pump, completely eliminating the mechanical root cause of dry running and stalling of the vacuum pump. Simultaneously, it maintains a slight positive back pressure in the pipeline, effectively preventing oil and gas backflow from underground oil tanks and deformation due to negative pressure in the tank. The integrated stainless steel corrugated flame arrester, based on the flame quenching effect, precisely controls the channel gap within a safe range of 0.4~0.6mm. Combined with high-temperature resistant and corrosion-resistant special sealing materials, it achieves bidirectional blocking of external backfire and internal sparks, significantly improving the operational stability and intrinsic safety level of the oil and gas recovery system under complex operating conditions. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the overall connection structure of the present invention;

[0030] Figure 2 This is a schematic diagram of the workflow of the present invention;

[0031] Figure 3 This is a schematic diagram of the oil and gas flow direction when the compensation circuit of the present invention is not connected;

[0032] Figure 4 This is a schematic diagram of the oil and gas flow direction when the compensation circuit of the present invention is connected;

[0033] Figure 5 This is an exploded view of the structure of each component of the protective device of the present invention;

[0034] Figure 6 This is a schematic diagram of the internal structure of the protective device of the present invention after assembly.

[0035] The annotations in the attached figures are explained as follows:

[0036] 1. Oil and gas recovery pump; 2. Inlet pipe; 3. Outlet pipe; 4. Compensation circuit; 5. Protection device; 501. Rear base; 502. Flame arrester; 503. Snap ring; 504. Main base; 505. Plug; 506. Valve core; 507. Spring; 508. Front base; 509. Valve seat; 510. Inner sealing ring; 511. Outer sealing ring; 512. Connecting cavity; 513. Limiting platform; 514. Flow hole; 6. Fuel nozzle; 7. Underground oil tank. Detailed Implementation

[0037] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0038] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0039] The present invention will be further described below with reference to the accompanying drawings:

[0040] Example 1: Refer to Figure 1 This embodiment provides an oil and gas recovery protection system, primarily designed to address the pump blockage and safety hazards caused by excessively high negative pressure at the intake end during refueling in vehicles equipped with an onboard oil and gas recovery system. The system includes an oil and gas recovery pump 1, whose intake end is connected to an intake pipe 2, and whose exhaust end is connected to an outlet pipe 3. Specifically, the oil and gas recovery pump 1, as the core power unit of the system, is responsible for generating negative pressure during refueling to extract oil and gas overflowing from the fuel tank. Its intake end forms the negative pressure inlet of the system, and its exhaust end forms the positive pressure outlet. In practical applications, the oil and gas recovery pump 1 can be a vane vacuum pump, a rotary vane pump, or other fluid machinery suitable for transporting flammable and explosive gases, as long as it can provide stable suction capacity.

[0041] The oil and gas recovery protection system in this embodiment also includes a compensation circuit 4, on which a protection device 5 is connected in series. The input end of the protection device 5 is connected to the exhaust end of the oil and gas recovery pump 1 through the compensation circuit 4, and the output end is connected to the intake end of the oil and gas recovery pump 1 through the compensation circuit 4. Specifically, the compensation circuit 4 physically forms a bypass channel bridging the exhaust end and intake end of the oil and gas recovery pump 1. The protection device 5, connected in series in this bypass channel, plays a dual role: firstly, as a controllable on / off element, it determines the opening or closing of the bypass channel according to the pipeline operating conditions; secondly, as a safety protection component, it performs flame-retardant and explosion-proof treatment on the gas flowing through the bypass. It should be understood that although Figure 1 The protective device 5 is illustrated as a standalone module. However, in other embodiments, the protective device 5 can also be integrated with other accessories on the compensation pipeline, such as check valves, filters, etc., or the compensation circuit 4 itself can be composed of multiple pipe sections spliced ​​together, as long as it ensures that the gas can flow from the exhaust end to the intake end through the protective device 5. This architectural design makes it physically possible for the system to form an internal pump self-circulation. That is, when the main intake is blocked, the gas can circulate internally between the pump's inlet and outlet through the compensation circuit 4, thereby preventing the pump body from being damaged by dry friction under no-load or high vacuum conditions.

[0042] In a preferred embodiment, the free end of the intake pipe 2 is connected to the fuel nozzle, and the free end of the outlet pipe 3 is connected to the underground oil tank. Specifically, this connection defines the specific location of the oil and gas recovery protection system of the present invention within the overall process pipeline of the gas station. The intake pipe 2 transports the oil and gas collected at the fuel nozzle's vent hood to the oil and gas recovery pump 1, while the outlet pipe 3 transports the pressurized oil and gas back to the underground oil storage tank, thus forming a complete secondary oil and gas recovery gas path. Under this system-level connection, the compensation circuit 4 is actually connected in parallel on both sides of the main recovery path of "fuel nozzle-underground oil tank". When the fuel nozzle is normally recovering oil and gas, the compensation circuit 4 is in the closed state and does not affect the main flow metering; however, when encountering special operating conditions, such as ORVR vehicle refueling causing an abnormal increase in the vacuum at the intake end, the compensation circuit 4 is activated, allowing some or all of the gas to circulate within the pump body, maintaining the pump's minimum safe flow rate and preventing excessive negative pressure from being transmitted to the fuel nozzle, causing tank deformation or intake noise. Through the above system architecture, this embodiment provides a reliable hardware foundation for subsequent differential pressure sensing control and mechanical automatic switching.

[0043] Example 2

[0044] Reference Figures 2-4 This embodiment, based on the oil and gas recovery protection system provided in Embodiment 1, further elaborates on the dynamic working process of the system under different operating conditions and the basis for setting key control parameters. First, it should be noted that the oil and gas circulation pump mentioned in this embodiment and subsequent descriptions is essentially the same as the oil and gas recovery pump 1 in Embodiment 1. Both refer to the same physical entity; the term is used to describe the specific functional state of internal gas circulation to avoid confusion.

[0045] Specifically, the operation of the aforementioned vapor recovery protection system mainly includes two automatically switching operating states. When the vapor recovery pump 1 is working, if the negative pressure in the intake pipe 2 does not reach the set threshold of the protection device 5, the protection device 5 will not activate, and the vapors drawn in by the vapor recovery pump 1 from the intake pipe 2 will be discharged through the outlet pipe 3. In this state, the system is in the normal vapor recovery mode. For example, when refueling a regular vehicle without an onboard vapor recovery system, the amount of vapors overflowing from the fuel tank is sufficient, and the negative pressure in the intake pipe 2 is usually maintained within the normal range of 10 to 15 kPa. At this time, the valve core 506 inside the protection device 5 remains closed under the preload of the spring 507, the compensation circuit 4 is physically isolated, and all vapors are transported to the underground fuel tank via the main recovery path, thereby ensuring the gas-liquid ratio metering accuracy and normal recovery efficiency required by national standards.

[0046] Conversely, if the negative pressure in the intake pipe 2 reaches a set threshold, the protection device 5 is activated, the compensation circuit 4 is connected, and the oil and gas will enter the compensation circuit 4 from the exhaust pipe 3 and then enter the intake pipe 2, where they are repeatedly circulated by the oil and gas circulation pump until the pump stops working. This situation usually occurs when refueling a China VI vehicle equipped with an on-board oil and gas recovery system. Because the on-board carbon canister absorbs most of the oil and gas during refueling, the intake end of the refueling nozzle lacks an air source, and the vacuum at the intake end of the oil and gas recovery pump 1 will rise sharply. When this negative pressure value reaches the opening threshold of the protection device 5, the pressure difference overcomes the resistance of the spring 507 and opens the valve core 506, making the compensation circuit 4 conductive. At this time, the high-pressure oil and gas discharged from the exhaust end no longer enters the underground oil tank, but flows back directly to the intake end through the compensation circuit 4, forming a closed internal self-circulation within the pump body. This mechanism ensures that gas always flows through the pump body, completely avoiding the risk of dry running and overheating of the impeller under no-load conditions. On the other hand, the circulating airflow maintains a basic back pressure of about 3 to 4 kPa in the pipeline, effectively preventing the positive pressure oil and gas in the underground oil tank from flowing back to the filler port, and also avoiding the problem of the vehicle's fuel tank wall denting and deforming due to excessive vacuum at the suction end.

[0047] As a preferred implementation, the activation threshold of the protection device 5 is set at 17–20 kPa. This range is not arbitrarily set but is a critical safety window determined based on extensive measured data. Specifically, the pipeline operating pressure under normal oil and gas recovery conditions generally fluctuates between 10 and 15 kPa, while the dangerous pressure differential under ORVR vehicle stall conditions can reach 25–60 kPa. Precisely limiting the activation threshold to 17–20 kPa, significantly higher than the upper limit of normal recovery pressure, effectively avoids malfunctions caused by instantaneous pipeline fluctuations or normal load changes, ensuring that the compensation circuit 4 is absolutely closed under non-ORVR conditions, thus guaranteeing metering accuracy. At the same time, this threshold is significantly lower than the lower limit of the dangerous pressure for equipment mechanical damage or tank deformation, providing sufficient safety margin for system response. When the negative pressure rises to this range, the protection device 5 can reliably and promptly open to release pressure, neither intervening too early to disrupt normal operations nor opening too late to damage equipment, achieving the best balance between protection sensitivity and operational stability. It should be understood that although this embodiment provides a preferred range of 17 to 20 kPa, in practical applications, this threshold can be adaptively fine-tuned based on factors such as the rated power of the oil and gas recovery pump 1, the stiffness of the spring 507, and the local altitude and air pressure, provided that the above-mentioned safety window logic is maintained, as long as it can distinguish between normal operating conditions and abnormal stall conditions.

[0048] Example 3

[0049] Reference Figure 5 and Figure 6To illustrate, this embodiment, based on the aforementioned oil and gas recovery protection system, further provides a specific mechanical structure for a protection device used in this system. The protection device 5 includes a main base 504, within which a valve seat 509, a valve core 506, and a plug 505 are disposed. The valve core 506 is located between the plug 505 and the valve seat 509, and the valve core 506 and valve seat 509 cooperate and seal. A spring 507 is disposed between the valve core 506 and the plug 505. A front base 508 is disposed at one end of the main base 504, and a rear base 501 is disposed at the other end. A flame arrester 502 is also disposed between the front base 508 and the rear base 501. Specifically, the main base 504 constitutes the central load-bearing frame of the protection device 5, and its interior forms an axially penetrating airflow channel. Valve seat 509 is fixed to the inner wall of main base 504 near the inlet side, serving as a sealing reference surface when the valve is closed. Plug 505 is installed on main base 504 near the exhaust side, acting as both a enclosure and a reverse support point for spring 507. Valve core 506 is constrained within the axial space between valve seat 509 and plug 505, allowing it to reciprocate axially under the combined action of spring 507 preload and airflow pressure difference, thus controlling the on / off state of compensation circuit 4. Front base 508 and rear base 501 are installed at both ends of main base 504 via threaded connections or flange bolts, achieving not only overall enclosure of the housing but also providing an independent mounting chamber for flame arrester 502. This modular, split-type architecture allows for independent assembly and maintenance of valve components and flame arrester components, improving production assembly efficiency and ease of later operation and maintenance. It should be understood that although the sealing fit between the valve core 506 and the valve seat 509 in this embodiment adopts a planar sealing form, in other embodiments, a conical sealing or spherical sealing structure can also be adopted, as long as airtight shut-off can be achieved under the compression state of the spring 507.

[0050] In a preferred embodiment, a limiting platform 513 is fixedly provided on the valve core 506. A spring 507 is sleeved on the valve core 506 on one side of the limiting platform 513, and an inner sealing ring 510 is sleeved on the valve core 506 on the other side of the limiting platform 513. When the spring 507 is in its natural state, the inner sealing ring 510 is in contact with the valve seat 509 and the limiting platform 513 respectively. Specifically, the limiting platform 513 is an annular protrusion structure integrally formed or interference-fitted on the valve core 506 body, which has a dual function: on the one hand, it provides a precise axial positioning reference for the spring 507, preventing the spring 507 from deflecting or slipping during compression, and ensuring the coaxiality and stability of the elastic force transmission; on the other hand, it acts as a pressing backing plate for the inner sealing ring 510. When the valve is closed, the preload of spring 507 is evenly transmitted to the inner sealing ring 510 through the limiting platform 513, causing it to press tightly against the end face of valve seat 509, thereby achieving zero-leakage sealing of compensation circuit 4. This design, which integrates the positioning and sealing clamping functions of spring 507 into a single limiting platform 513, significantly reduces the number of parts compared to the traditional separate structure using an independent retaining ring and sealing gasket, eliminates the risk of retaining ring loosening and falling off, and ensures a constant and controllable sealing specific pressure. In addition, the axial thickness of the limiting platform 513, precisely calculated, also limits the maximum compression stroke of spring 507, preventing permanent deformation and failure of the sealing ring due to overpressure.

[0051] To ensure smooth airflow when compensation circuit 4 is in operation, a flow passage 514 is also provided through the plug 505. Specifically, there can be one or more flow passages 514, the diameter and distribution of which are optimized through fluid simulation to eliminate any dead zones that may form in the plug 505 area. When the valve core 506 opens and high-pressure oil and gas return from the exhaust end, the gas can pass through the plug 505 evenly through the flow passage 514 and enter the valve chamber, avoiding turbulent noise and pressure loss caused by local throttling effects. This design is crucial for maintaining the stability of the pump's internal self-circulation, especially under high-frequency start-stop conditions, effectively reducing the impact load of airflow pulsation on the valve core 506 and extending the valve's service life.

[0052] In terms of safety protection, the flame arrester 502 is made of ultra-thin stainless steel strips pressed and wound into a columnar structure with a vortex-shaped cross-section and a gap of 0.4~0.6mm between adjacent layers. Specifically, the flame arrester 502 works based on the principle of flame quenching. The maximum safe quenching gap for gasoline vapor is approximately 0.7mm. In this embodiment, the gap between the corrugated strip layers is strictly controlled within the range of 0.4~0.6mm to ensure that any flame front attempting to pass through the flame arrester 502 will be divided into countless tiny fireballs. The huge heat exchange surface area of ​​the ultra-thin stainless steel strip can instantly absorb the heat of the flame, causing the gas temperature to drop sharply below the ignition point of gasoline, thereby interrupting the combustion chain reaction. The vortex structure, while ensuring sufficient quenching depth, provides a larger effective flow area than a straight channel, reducing resistance loss during normal ventilation and avoiding negative impacts on the pumping synchronization of the vapor recovery pump 1. It should be understood that although 304 stainless steel corrugated strip is preferred in this embodiment, 316L stainless steel or other equivalent metal materials can also be selected in some scenarios with higher requirements for corrosion resistance; the structure of the flame arrestor core is not limited to vortex lines, but can also be parallel plate corrugations or sintered metal porous media, as long as its pore size meets the above-mentioned quenching gap requirements.

[0053] To facilitate maintenance and cleaning, connecting cavities 512 are provided on both the front base 508 and the rear base 501. The main base 504 is connected to the front base 508 and the rear base 501 respectively through the connecting cavities 512. The flame arrester 502 is located inside the connecting cavity 512 and is fixedly connected to the connecting cavity 512 by a retaining spring 503, with its axis direction being the same as the movement direction of the valve core 506. Specifically, the connecting cavity 512 provides a standardized installation interface for the flame arrester 502. After the flame arrester 502 core is pushed into the connecting cavity 512, it is axially limited by the elastic retaining spring 503 embedded in the pre-set annular groove in the cavity wall, and can be fixed without screw tightening. This quick-release connection method allows on-site personnel to remove the flame arrester core separately for cleaning or replacement without disassembling the entire protective device 5 body, greatly simplifying the operation and maintenance process. The flame arrester 502 axis is coaxial with the valve core 506 in the direction of movement, so that the inlet and outlet airflow paths are straight and unobstructed, avoiding additional pressure drop and eddy noise caused by sudden changes in flow direction, and further optimizing the system's fluid dynamics performance.

[0054] Finally, to ensure the long-term sealing reliability of the device in flammable and explosive environments, external sealing rings 511 are provided at the joints between the main substrate 504 and the front substrate 508 and the rear substrate 501. Both the inner sealing ring 510 and the outer sealing ring 511 are made of fluororubber FKM or polytetrafluoroethylene (PTFE). Specifically, the oil and gas recovery system is in long-term contact with gasoline vapor and liquid fuel. Ordinary nitrile rubber is prone to swelling, softening, or even dissolving and failing under gasoline immersion, leading to oil and gas leakage and safety accidents. Fluororubber FKM has excellent resistance to hydrocarbon solvents and wide temperature range adaptability, while polytetrafluoroethylene (PTFE) has an extremely low coefficient of friction and excellent chemical inertness. Using these two special materials to manufacture key sealing components fundamentally eliminates the risk of leakage due to seal aging, ensuring the inherent safety of the protection device 5 throughout its entire life cycle. It should be understood that although this embodiment lists FKM and PTFE as two preferred materials, in practical applications, other equivalent oil-resistant and high-temperature resistant elastomers such as perfluoroether rubber FFKM can also be selected according to the specific medium composition and operating temperature, as long as their medium resistance and mechanical strength meet the requirements of the oil and gas recovery industry standards.

[0055] Example 4

[0056] This embodiment, based on the oil and gas recovery protection system, working process, and protection device 5 provided in Embodiments 1 to 3 above, further verifies the effectiveness and reliability of the technical solution in solving practical technical problems through specific application scenarios. It should be noted that this embodiment is merely an illustrative application example and not a limitation on the scope of protection of this invention. Any equivalent application scenario that conforms to the core technical concept of this invention should be covered within the scope of protection of this invention.

[0057] Specifically, let's consider a typical conflict scenario: A vehicle meeting China VI emission standards and equipped with an onboard vapor recovery system pulls into a gas station and uses a standard secondary vapor recovery fuel dispenser for refueling. In this scenario, both the vehicle's vapor recovery system and the fuel dispenser's vapor recovery system activate simultaneously. Because the vehicle's carbon canister actively absorbs most of the vapors overflowing from the fuel tank during refueling, almost no vapors are available for extraction at the fuel nozzle's vapor collection hood. At this point, the vapor recovery pump 1 inside the fuel dispenser experiences an extremely high vacuum due to the lack of air intake, causing the negative pressure in the pipeline to rapidly rise from the normal 10-15 kPa to a dangerous range of 25-60 kPa.

[0058] During this abnormal operating condition evolution, the oil and gas recovery protection system provided by this invention exhibits the expected automatic protection function. When the negative pressure in the intake pipe 2 rises and reaches the preset activation threshold of 17 to 20 kPa for the protection device 5, the pressure difference force acting on the valve core 506 overcomes the preload force of the spring 507, driving the valve core 506 to move axially and leave the valve seat 509, thereby automatically opening the protection device 5 connected in series with the compensation circuit 4. Subsequently, the high-pressure oil and gas that should have been discharged to the underground oil tank is diverted and flows directly back to the suction end of the oil and gas recovery pump 1 through the compensation circuit 4, forming a closed self-circulating airflow channel inside the pump body. This process is completely completed automatically by the mechanical structure without the need for external electrical control signals, ensuring real-time response and inherent safety.

[0059] Through the aforementioned differential pressure self-compensation mechanism, the system has verified its technical effectiveness in multiple dimensions. First, at the mechanical protection level, the internal circulating airflow ensures that the oil and gas recovery pump 1 is always in a loaded operating state, completely eliminating the risk of impeller dry running and stalling in the absence of media, effectively delaying the performance degradation of the pump body, and avoiding equipment damage or even fire accidents caused by overheating. Second, at the process safety level, the circulating airflow maintains a basic back pressure of approximately 3 to 4 kPa in the pipeline. This slightly positive pressure environment effectively prevents the backflow of positive pressure oil and gas that may exist in the underground oil tank to the refueling port, and also avoids negative pressure indentation and deformation of the vehicle's fuel tank wall due to excessive vacuum at the suction end. Secondly, regarding explosion-proof safety, the oil and gas flowing through the compensation circuit 4 must pass through the flame arresters 502 at both ends of the protection device 5. The vortex gap of 0.4 to 0.6 mm is strictly smaller than the maximum safe quenching gap of gasoline and oil. Even if sparks are generated inside the pump due to friction or backfire occurs outside, the flame will be quenched by the heat absorbed instantly by the metal corrugated belt. At the same time, the sealing ring made of fluororubber or polytetrafluoroethylene maintains stable sealing performance in the long-term contact environment with gasoline and oil, eliminating the risk of leakage.

[0060] As a comparative verification, when the same system was used to refuel a regular vehicle without an onboard vapor recovery system, the negative pressure in the intake pipe 2 remained stable within the normal range of 10 to 15 kPa due to sufficient fuel vapor in the tank, far below the opening threshold of 17 to 20 kPa. At this time, the spring 507 inside the protection device 5 firmly pressed the valve core 506, the compensation circuit 4 remained absolutely closed, and all fuel vapor was normally transported through the main recovery path. The system's gas-liquid ratio metering accuracy and recovery efficiency were completely unaffected. This comparative result conversely confirms the necessity and rationality of the threshold parameter settings in the aforementioned embodiments, proving that the system can accurately distinguish between normal and abnormal operating conditions. While ensuring that daily operations are not interfered with, it automatically intervenes only in critical moments when protection is truly needed, achieving the best balance between protection sensitivity and operational stability.

[0061] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. An oil and gas recovery protection system, comprising an oil and gas recovery pump (1), wherein the suction end of the oil and gas recovery pump (1) is connected to an inlet pipe (2), and the exhaust end of the oil and gas recovery pump (1) is connected to an outlet pipe (3), characterized in that: It also includes a compensation circuit (4), on which a protection device (5) is connected in series. The input end of the protection device (5) is connected to the exhaust end of the oil and gas recovery pump (1) through the compensation circuit (4), and the output end is connected to the suction end of the oil and gas recovery pump (1) through the compensation circuit (4).

2. The oil and gas recovery and protection system according to claim 1, characterized in that: The free end of the air inlet pipe (2) is connected to the refueling nozzle, and the free end of the air outlet pipe (3) is connected to the underground oil tank.

3. The working process of an oil and gas recovery protection system according to claims 1-2, characterized in that: When the oil and gas recovery pump (1) is working, if the negative pressure in the intake pipe (2) does not reach the set threshold of the protection device (5), the protection device (5) will not start, and the oil and gas sucked in by the oil and gas recovery pump (1) from the intake pipe (2) will be discharged through the outlet pipe (3); if the negative pressure in the intake pipe (2) reaches the set threshold, the protection device (5) will start, the compensation circuit (4) will be connected, and the oil and gas will enter the compensation circuit (4) from the outlet pipe (3) and then enter the intake pipe (2), and be drawn away by the oil and gas circulation pump and circulated repeatedly until the oil and gas circulation pump stops working.

4. The working process of the oil and gas recovery protection system according to claim 3, characterized in that: The activation threshold of the protection device (5) is 17-20 kPa.

5. A protection device for an oil and gas recovery protection system according to any one of claims 1-2, characterized in that: The system includes a main body (504), within which a valve seat (509), a valve core (506), and a plug (505) are disposed. The valve core (506) is located between the plug (505) and the valve seat (509), and the valve core (506) and the valve seat (509) are fitted together to seal. A spring (507) is disposed between the valve core (506) and the plug (505). A front base (508) is disposed at one end of the main body (504), and a rear base (501) is disposed at the other end. A flame arrester (502) is also disposed between the front base (508) and the rear base (501).

6. The protection device for an oil and gas recovery protection system according to claim 5, characterized in that: The flame arrester (502) is made of ultra-thin stainless steel strip pressed and wound into a columnar structure, with a cross-section of a spiral structure and a gap of 0.4~0.6mm between adjacent layers.

7. The protection device for an oil and gas recovery protection system according to claim 5, characterized in that: A limiting platform (513) is fixedly provided on the valve core (506). The spring (507) is sleeved on the valve core (506) on one side of the limiting platform (513). An inner sealing ring (510) is sleeved on the valve core (506) on the other side of the limiting platform (513). When the spring (507) is in its natural state, the inner sealing ring (510) is in contact with the valve seat (509) and the limiting platform (513) respectively.

8. The protection device for an oil and gas recovery protection system according to claim 5, characterized in that: An overflow hole (514) is also provided through the plug (505).

9. The protection device for an oil and gas recovery protection system according to claim 6, characterized in that: A connecting cavity (512) is provided on both the front base (508) and the rear base (501). The main base (504) is connected to the front base (508) and the rear base (501) respectively through the connecting cavity (512). The flame arrester (502) is located in the connecting cavity (512) and is fixedly connected to the connecting cavity (512) by a snap ring (503). Its axial direction is the same as the moving direction of the valve core (506).

10. The protection device for an oil and gas recovery protection system according to claim 7, characterized in that: An outer sealing ring (511) is provided at the joint between the main substrate (504) and the front substrate (508) and the rear substrate (501), and the inner sealing ring (510) and the outer sealing ring (511) are both made of fluororubber FKM or tetrafluoroethylene PTFE.

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