A wide working condition gas-liquid coupling differential pressure power generation system for complex wellhead gas

Abstract

The application discloses a wide-working-condition gas-liquid coupling type differential pressure power generation system for complex wellhead gas, which comprises a natural gas source pipeline, a natural gas gathering pipeline, an internal gas inlet distribution pipeline, an internal gas outlet gathering pipeline, an inlet and outlet gas control valve group, a first gas-liquid pressure conversion system, a second gas-liquid pressure conversion system, a hydraulic oil reversing valve and a power generation system. The inlet and outlet gas control valve group is connected with the internal gas inlet distribution pipeline, the internal gas outlet gathering pipeline, the first gas-liquid pressure conversion system and the second gas-liquid pressure conversion system. The hydraulic oil reversing valve is connected with the first gas-liquid pressure conversion system, the second gas-liquid pressure conversion system and the power generation system. The hydraulic oil output from the hydraulic oil reversing valve flows through the power generation system and then returns to the hydraulic oil reversing valve. The application is used to solve the problems that the wellhead differential pressure power generation system in the prior art is difficult to be applied to the complex gas quality conditions of the wellhead of a natural gas well and difficult to meet the long-period safe and stable operation requirements.

Description

Technical Field

[0001] This invention relates to the field of wellhead natural gas pressure differential energy recovery technology, specifically to a wide-condition gas-liquid coupling pressure differential power generation system for complex wellhead gas. Background Technology

[0002] Against the backdrop of the global energy structure's low-carbon transformation, natural gas's strategic position as a clean and efficient transitional energy source is becoming increasingly prominent. The entire production process of natural gas, from extraction to distribution, largely utilizes pressure transmission, requiring pressure regulation through throttling valves at multiple stages, thus containing a large amount of pressure energy resources that urgently need to be utilized. Traditional natural gas differential pressure power generation technology uses fluid machinery, primarily turbine expanders, to recover and utilize the pressure energy resources of natural gas. However, due to the stringent requirements of expander equipment on gas quality conditions, and to ensure efficient, safe, and stable system operation, traditional differential pressure power generation technology can only be applied in scenarios with clean gas quality, stable flow and pressure, medium to low pressure levels (<20MPa), and low differential pressure (<3~5MPa), such as natural gas pressure regulating stations and gas pipelines.

[0003] In natural gas production processes, wellhead gas from production wells contains abundant pressure energy resources due to its higher pressure rating (>25 MPa) and wider usable pressure differential range (>10 MPa). However, the gas quality conditions at the wellhead are exceptionally complex: it typically contains impurities such as formation water and formation sand, and may be rich in H2S, CO2, and chloride ions (Cl). - Corrosive media such as nitrogen oxides and sulfur dioxide are present at the wellhead. Furthermore, the pressure and flow rate of the wellhead gas fluctuate significantly due to factors such as production adjustments and formation pressure decay. These harsh operating conditions, characterized by complex composition and drastic pressure and flow fluctuations, constitute a technical barrier that traditional differential pressure power generation equipment struggles to overcome at the wellhead, preventing the effective development of the vast differential pressure energy resources of natural gas at the wellhead in the oil and gas industry for a long time.

[0004] Existing technologies for wellhead power generation for natural gas production wells have emerged, but they suffer from the following drawbacks and limitations:

[0005] (1) Some existing technologies applied in other fields also use the principle of gas driving liquid to generate electricity. However, the power generation process of such systems is limited by a fixed mass (volume) of gas / liquid, which makes it impossible for the system to operate continuously for a long time, thus exhibiting inherent intermittent power generation characteristics. However, in the actual demand scenario of wellhead gas pressure energy recovery and utilization, the wellhead gas after power generation still needs to maintain a certain high pressure (usually ≥10MPa) before it can enter the subsequent production process or gathering and transportation pipeline. Obviously, the design of such existing technologies cannot meet the high pressure back pressure conditions of natural gas wellheads.

[0006] (2) Although some existing technologies utilize the pressure difference of wellhead gas to generate electricity, their core technology is still based on the turbine expander as an energy conversion device. As mentioned above, such systems are extremely unsuitable for complex gas conditions and cannot meet the requirements of harsh operating conditions with drastic pressure and flow fluctuations. Furthermore, in order to meet the gas intake requirements of the turbine expander, these existing technologies are equipped with complex and redundant pretreatment systems to purify the source gas. However, these pretreatment systems inevitably lead to a large amount of pressure energy loss during the process of removing impurities from the wellhead gas.

[0007] (3) Some existing technologies require the source gas to have stable pressure and flow rate in order to ensure that the system has stable power generation output characteristics, which cannot effectively adapt to the inherent large pressure / flow rate fluctuations in wellhead gas production. Moreover, most of these existing technologies cannot ensure that the hydraulic oil maintains stable medium performance under long-term, high-pressure, and wide pressure difference operation conditions, which poses a risk of medium failure and thus threatens the overall reliability of the system.

[0008] (4) In order to prevent the gas temperature drop after expansion power generation from exceeding the standard, or even causing ice blockage, many existing technologies require the addition of heating equipment to reheat the natural gas before it enters the low-pressure gathering and transmission pipeline in order to meet the subsequent gas transmission temperature conditions. This not only increases the complexity of the process and equipment, but also has a serious dependence on external energy and introduces additional operating energy consumption.

[0009] (5) To achieve stable and continuous power generation and minimize pressure pulsation, some existing technologies rely on multiple sets (at least three or more sets) of equipment to achieve precise equal-angle phase difference drainage and flow superposition. This directly leads to extremely complex system processes and a significant increase in the number of high-voltage equipment. Furthermore, to ensure stable flow after superposition, these existing technologies inevitably increase the number of high-voltage equipment. Precise phase control (i.e., stroke control) between multiple units relies solely on the "soft" adjustment of the control system and lacks hardware support. As the number of units increases, the complexity of the control algorithm increases exponentially, making it extremely difficult to maintain stable system operation. Therefore, these existing technologies remain only in the theoretical stage and are difficult to apply in practice.

[0010] In summary, there is currently no pressure energy generation equipment specifically designed for the complex gas conditions at wellheads (such as complex composition, fluctuating flow and pressure, high pressure, and wide-band pressure differential utilization). While existing technologies have improved the pressure rating and operating pressure differential of the core equipment, the turbine expander, they still struggle to meet the requirements for safe and stable operation over long periods under the aforementioned complex and demanding gas conditions. Therefore, no wellhead pressure differential power generation system with practical field application capabilities has been publicly disclosed to date. Summary of the Invention

[0011] This invention provides a wide-condition gas-liquid coupling differential pressure power generation system for complex wellhead gas, in order to solve the problem that existing wellhead differential pressure power generation systems are still in the theoretical stage and are difficult to apply to the complex gas and gas conditions at the wellhead of natural gas wells, and are difficult to meet the requirements for safe and stable operation over long periods.

[0012] This invention is achieved through the following technical solution:

[0013] A wide-condition gas-liquid coupling differential pressure power generation system for complex wellhead gas includes a natural gas source pipeline, a natural gas gathering and transmission pipeline, an internal gas intake distribution pipeline connected to the natural gas source pipeline, an internal exhaust gathering and transmission pipeline connected to the natural gas gathering and transmission pipeline, an intake and exhaust control valve group, a first gas-liquid pressure conversion system, a second gas-liquid pressure conversion system, a hydraulic oil reversing valve, and a power generation system.

[0014] The intake and exhaust control valve group is connected to the intake distribution pipeline, the exhaust collection and transportation pipeline and the first gas-liquid pressure conversion system and the second gas-liquid pressure conversion system in the system, and is used to control the flow path of gas in the first gas-liquid pressure conversion system and the second gas-liquid pressure conversion system.

[0015] The hydraulic oil reversing valve is connected to the first gas-liquid pressure conversion system, the second gas-liquid pressure conversion system and the power generation system, and is used to control the flow path of hydraulic oil in the first gas-liquid pressure conversion system and the second gas-liquid pressure conversion system.

[0016] The hydraulic oil output from the hydraulic oil reversing valve flows through the power generation system and then flows back to the hydraulic oil reversing valve.

[0017] To address the problem that existing wellhead differential pressure power generation systems remain theoretical and are difficult to apply to the complex gas and gas conditions at natural gas wellheads, and cannot meet the requirements for safe and stable operation over long periods, this invention proposes a wide-condition gas-liquid coupling differential pressure power generation system for complex wellhead gas conditions. The natural gas source pipeline is the high-pressure gas pipeline from the natural gas production wellhead, while the natural gas gathering and transmission pipeline is the relatively low-pressure pipeline used to transport the collected natural gas downstream. The entire system of this application is positioned between the natural gas source pipeline and the natural gas gathering and transmission pipeline to achieve the purpose of generating electricity using wellhead pressure energy.

[0018] In this application, high-pressure gas from the wellhead enters the gas distribution pipeline within the system via the natural gas source pipeline. Its downstream flow path is then controlled by the intake and exhaust control valve group. The gas pressure energy is converted into hydraulic oil pressure energy by the first / second gas-hydraulic pressure conversion system. The hydraulic oil flow path is then controlled by the hydraulic oil reversing valve, allowing the high-pressure hydraulic oil to enter the power generation system for power generation. The hydraulic oil pressure decreases as it flows through the power generation system and returns to the hydraulic oil reversing valve, returning to the first / second gas-hydraulic pressure conversion system to replenish and circulate the hydraulic oil. Simultaneously, the gas within the first / second gas-hydraulic pressure conversion system is discharged and enters the exhaust and gathering pipeline within the system via the intake and exhaust control valve group, thus enabling the downstream transportation of natural gas.

[0019] This application sets up two gas-liquid pressure conversion systems. When one set is working, the other set can prepare for pressure regulation. The two sets of gas-liquid pressure conversion systems operate alternately to achieve continuous and uninterrupted power generation.

[0020] This application can be directly applied to special operating conditions with complex gas and gas quality, such as natural gas wellheads and oil and gas reservoirs. These scenarios are often affected by the characteristics of the original formation, resulting in irregular fluctuations in pressure and flow, complex composition, high pressure levels, and a large range of usable pressure differentials in the gas source. The wide-condition gas-liquid coupling differential pressure power generation system proposed in this application has strong adaptability to such complex operating conditions in terms of process flow, key equipment structure, and operation control scheme. It can achieve long-term, highly stable external power generation under complex gas and gas conditions, and only requires a relatively simple control strategy to meet the working requirements. It overcomes the shortcomings of existing technologies that rely on a large number of high-pressure equipment and have almost stringent requirements on control algorithms, and truly realizes the practical application of natural gas wellhead differential pressure power generation technology.

[0021] Furthermore, both the first gas-liquid pressure conversion system and the second gas-liquid pressure conversion system include N gas-liquid pressure conversion devices, where N is an even number;

[0022] N gas-liquid pressure conversion devices are grouped in pairs;

[0023] For two gas-liquid pressure conversion devices in the same group, when one converts gas pressure energy into hydraulic pressure energy, the other converts hydraulic pressure energy into gas pressure energy.

[0024] This scheme incorporates an even number of gas-liquid pressure conversion devices in the gas-liquid pressure conversion system to ensure that these devices can operate in pairs. For any pair of gas-liquid pressure conversion devices, during operation, the flow direction is controlled by the intake / exhaust control valve group and the hydraulic oil directional valve, achieving series connection with the power generation system. Specifically, high-pressure gas enters one of the gas-liquid pressure conversion devices via the intake / exhaust control valve group, converting gas pressure energy into hydraulic energy. This hydraulic energy drives the hydraulic oil to flow through the power generation system to generate electricity. Then, in the other gas-liquid pressure conversion device in the same group, the hydraulic energy is converted back into gas pressure energy, driving the natural gas remaining in that device into the intake / exhaust control valve group, and finally into the exhaust and gathering pipeline within the system. This application, through a special design of the gas-liquid pressure conversion system, achieves gas-liquid coupling operation, meeting the needs for wellhead gas pressure fluctuation and flow pulsation control under complex gas source conditions, and enabling the conversion and utilization of high-pressure, wide-pressure-difference wellhead gas pressure energy.

[0025] Furthermore, the gas-liquid pressure conversion device includes a cylinder, a partition located inside the cylinder, and an I-shaped piston that moves through the partition;

[0026] Both ends of the I-shaped piston are dynamically sealed to the inner wall of the cylinder; the piston rod of the I-shaped piston is dynamically sealed to the partition.

[0027] One end of the I-shaped piston faces away from the partition and forms a gas working chamber with the cylinder body; the other end of the I-shaped piston faces away from the partition and forms a hydraulic oil working chamber with the cylinder body.

[0028] It also includes an air inlet, an exhaust outlet, a fluid inlet / outlet, and a replenishment port formed on the surface of the cylinder block; the air inlet and exhaust outlet are both connected to the gas working chamber, and the fluid inlet / outlet and replenishment port are both connected to the hydraulic oil working chamber;

[0029] The hydraulic oil working chamber is connected to the hydraulic oil reversing valve; accumulators are installed on both the upstream and downstream pipelines of the hydraulic oil reversing valve.

[0030] This solution creatively employs an I-shaped piston as one of the core components of the gas-hydraulic pressure conversion device. Through the I-shaped piston and the partition, the cylinder body is divided into four chambers. The chambers at both ends serve as working chambers for gas and liquid, respectively, while the two middle chambers form two independent buffer chambers. This effectively prevents bidirectional contamination between high-pressure gas and hydraulic oil, ensuring stable system operation. Furthermore, the unique design of the gas-hydraulic pressure conversion device in this solution overcomes the limitation of existing technologies that can only reduce cylinder size to pursue operational stability. It can be modified from a large, high-pressure vessel, meaning that more hydraulic oil can be filled at once, significantly increasing the effective power generation water volume and piston stroke. This effectively extends the drainage time (i.e., continuous power generation time) of each gas-hydraulic pressure conversion system, thereby reducing the impact of frequent fluctuations in hydraulic oil flow and head caused by high-frequency switching between devices during long-term system operation on power generation. This substantially improves the system's operational stability and reliability. In addition, accumulators are installed above and below the hydraulic oil reversing valve to balance instantaneous flow fluctuations caused by valve switching during system scheduling, further enhancing the system's operational stability.

[0031] Furthermore, the air inlet and exhaust outlet are both connected to the air intake and exhaust control valve group, and the liquid inlet and outlet are connected to the hydraulic oil reversing valve; an electromagnetic control valve is provided between the liquid inlet and outlet and the hydraulic oil reversing valve.

[0032] In this scheme, the intake and exhaust control valve group introduces high-pressure gas from the wellhead into the gas-liquid pressure conversion device through the intake port; the intake and exhaust control valve group introduces the gas discharged from the gas-liquid pressure conversion device into the exhaust collection pipeline in the system through the exhaust port; the hydraulic oil reversing valve is used to control whether the corresponding gas-liquid pressure conversion device is in the liquid inlet or liquid outlet state; and the electromagnetic control valve is used to completely shut off the pipeline between the gas-liquid pressure conversion device and the hydraulic oil reversing valve.

[0033] Furthermore, a gas buffer chamber and a hydraulic oil buffer chamber are respectively formed between the two ends of the I-shaped piston and the partition; the gas buffer chamber and the gas working chamber are located on the same side of the partition, and the hydraulic oil buffer chamber and the hydraulic oil working chamber are located on the same side of the partition;

[0034] The gas buffer chamber is provided with a sludge discharge valve on its side wall, and the hydraulic oil buffer chamber is provided with a sludge discharge port on its side wall; it also includes piston limiting devices installed at both ends of the I-shaped piston, the piston limiting devices being used to limit the stroke of the I-shaped piston.

[0035] The gas buffer chamber is used to prevent high-pressure gas from mixing into the hydraulic oil and causing contamination. If gas enters the gas buffer chamber, it can be discharged through the sludge discharge valve. The hydraulic oil buffer chamber is used to prevent hydraulic oil from mixing into the wellhead gas. If hydraulic oil enters the hydraulic oil buffer chamber, it can be discharged or recycled through the sludge discharge port.

[0036] Furthermore, this solution uses a piston limiting device to limit the movement of the I-shaped piston, preventing direct mechanical collision between the piston end face and the cylinder. This protects sensors and other equipment within the working chamber while allowing the residual high-pressure fluid in the clearance volume to act as a buffer at the moment the discharge process ends or the intake process begins. Specifically, this prevents both ends of the I-shaped piston from directly and tightly fitting into the partition, maintaining clearance in the gas and hydraulic oil buffer chambers. This ensures the exhaust valve and drain port remain open, guaranteeing stable exhaust and anti-fouling functions. Additionally, if one end of the I-shaped piston is tightly fitted into the partition, it could cause piston air or hydraulic lock, leading to malfunctions in the gas-hydraulic pressure conversion device. The piston limiting device in this solution maintains a gap between the end of the I-shaped piston and the partition, ensuring a constant pressure. This reduces the difficulty of switching the direction of movement of the I-shaped piston and prevents air or hydraulic lock from causing operational obstruction.

[0037] Furthermore, the intake and exhaust control valve group includes N two-position three-way valves, each corresponding to a gas-liquid pressure conversion device; the two-position three-way valves are connected to the intake distribution pipeline, the exhaust collection and transportation pipeline, and the gas working chamber within the system.

[0038] This solution uses a two-position three-way valve to achieve the required path switching and blocking, enabling individual control and rapid switching of the gas flow direction for each gas-liquid pressure conversion device. The two-position three-way valve can be implemented using existing finished products, and will not be elaborated here.

[0039] Furthermore, it also includes a temperature sensor for monitoring the temperature of the hydraulic oil flowing through the power generation system; an overflow control valve is installed on the path of the hydraulic oil returning from the power generation system to the hydraulic oil reversing valve, and the temperature sensor is signal-connected to the overflow control valve.

[0040] This also includes gas-liquid heat exchangers;

[0041] The overflow control valve is connected to the liquid input terminal of the gas-liquid heat exchanger, and the liquid output terminal of the gas-liquid heat exchanger is connected to the oil tank; the gas input terminal of the gas-liquid heat exchanger is connected to the exhaust gas gathering and transmission pipeline in the system, and the gas output terminal of the gas-liquid heat exchanger is connected to the natural gas gathering and transmission pipeline.

[0042] During further research, the inventors discovered that because the hydraulic oil in this application operates at high pressure for extended periods, it tends to reach high temperatures after flowing through the power generation system. Excessive hydraulic oil temperature can lead to denaturation and failure, hindering subsequent recycling. To overcome this problem, this solution uses a temperature sensor to monitor the temperature of the hydraulic oil flowing through the power generation system. The monitoring location can be upstream or downstream of the power generation system. Based on the real-time monitored hydraulic oil temperature, an overflow control valve proportionally replaces a portion of the high-temperature hydraulic oil in the gas-liquid heat exchanger. This oil exchanges heat with the low-temperature, low-pressure gas from the system's exhaust and distribution pipeline, allowing the cooled hydraulic oil to return to the tank for later use.

[0043] It should be noted that the opening ratio of the overflow control valve in this solution is positively correlated with the hydraulic oil temperature, that is, the higher the hydraulic oil temperature, the greater the opening degree of the overflow control valve. Of course, the specific opening relationship should be adaptively set by the operator according to the specific working conditions (such as the source air temperature, pressure and flow rate, system operating (design) pressure difference, hydraulic oil physical (temperature change) characteristics and ambient temperature, etc.), and no specific limitation is made here.

[0044] This solution not only enables effective control of hydraulic oil temperature and avoids overheating and subsequent degradation failure, but also utilizes high-temperature hydraulic oil to heat the low-temperature natural gas in the exhaust and transmission pipeline within the system. This overcomes the shortcomings of existing technologies that require the addition of numerous heating devices for reheating, thus reducing additional energy consumption.

[0045] Furthermore, the output end of the oil tank is sequentially connected to a filter, a hydraulic oil pump, a hydraulic oil pressure limiter, a hydraulic oil replenishment control valve, and a distribution control valve; the distribution control valve is used to replenish hydraulic oil to the first gas-hydraulic pressure conversion system and the second gas-hydraulic pressure conversion system.

[0046] To prevent the hydraulic oil from overheating, some hydraulic oil is replaced for heat exchange and cooling. This operation results in the volume of hydraulic oil flowing back into the corresponding gas-hydraulic pressure conversion system being smaller than the volume of hydraulic oil discharged. Consequently, the required working fluid level cannot be reached for the next power generation cycle, interfering with the working efficiency and power generation rate of the next cycle. To overcome these problems, this solution uses a hydraulic pump to draw cooled hydraulic oil from the tank and replenish it to the corresponding gas-hydraulic pressure conversion system. It also allows for the regulation of the initial gas pressure within the gas-hydraulic pressure conversion system. This ensures that while one gas-hydraulic pressure conversion system is operating, the other is in preparation, guaranteeing stable and continuous alternating operation of both systems. This, in turn, ensures a stable and continuous constant-frequency current output from the power generation system.

[0047] Furthermore, any leaked or contaminated hydraulic oil from the power generation system, hydraulic oil pressure limiter, and hydraulic oil replenishment control valve flows back to the oil tank.

[0048] For power generation systems, hydraulic oil pressure limiters, and hydraulic oil replenishment control valves, there is a possibility of passive oil leakage or active oil release during operation. This solution can recover as much of the leaked or contaminated hydraulic oil as possible into the oil tank for reuse, which helps reduce the frequency of external hydraulic oil replenishment. Those skilled in the art should understand that the collection of leaked hydraulic oil from equipment can be achieved using conventional methods, such as installing diversion pipelines on the equipment casing.

[0049] Furthermore, the exhaust gas gathering and transmission pipeline within the system is connected to the natural gas gathering and transmission pipeline via a first bypass pipeline, on which a safety valve is installed. When the gas path of the gas-liquid heat exchanger is blocked or malfunctions, the gas opens the safety valve and enters the natural gas gathering and transmission pipeline through the safety valve to ensure the safe operation of the system and reduce the probability of accidents.

[0050] The overflow control valve is also connected to the oil tank via a second bypass pipeline, on which a heat exchanger bypass valve is installed. Similarly, when the oil circuit of the gas-liquid heat exchanger becomes blocked or malfunctions, the heat exchanger bypass valve is opened, and the oil flows through the heat exchanger bypass valve into the natural gas gathering and transmission pipeline to ensure the safe operation of the system and reduce the probability of accidents.

[0051] Compared with the prior art, the present invention has at least the following advantages and beneficial effects:

[0052] 1. This invention discloses a wide-condition gas-liquid coupling differential pressure power generation system for complex wellhead gas. It has strong adaptability to complex gas and gas conditions in terms of process flow, key equipment structure and operation control scheme. It can achieve long-term and highly stable external power generation under complex gas and gas conditions. At the same time, it only requires a relatively simple control strategy to meet the working requirements. It overcomes the defects of existing technologies that rely on a large number of high-pressure equipment and have almost stringent requirements on control algorithms. It truly realizes the practical application of natural gas wellhead differential pressure power generation technology.

[0053] 2. The present invention provides a wide-condition gas-liquid coupling differential pressure power generation system for complex wellhead gas. Through the special design of the gas-liquid pressure conversion system, gas-liquid coupling operation is realized. It can meet the needs of wellhead gas pressure fluctuation and flow pulsation control under complex gas source conditions, and can also realize the conversion and utilization of wellhead gas pressure energy with high pressure and wide pressure difference.

[0054] 3. The present invention provides a wide-condition gas-liquid coupling differential pressure power generation system for complex wellhead gas, which can effectively prevent bidirectional impurity contamination between high-pressure gas and hydraulic oil, ensure stable system operation, and substantially improve the system's operational stability and reliability.

[0055] 4. The present invention provides a wide-condition gas-liquid coupling differential pressure power generation system for complex wellhead gas, which can not only effectively regulate the temperature of hydraulic oil and avoid the degradation and failure caused by excessively high hydraulic oil temperature, but also use high-temperature hydraulic oil to heat up the low-temperature natural gas in the exhaust and gathering pipeline of the system. This overcomes the shortcomings of existing technologies that require the addition of a large number of heating devices for reheating, and reduces additional energy loss.

[0056] 5. This invention provides a wide-condition gas-liquid coupling differential pressure power generation system for complex wellhead gas. A hydraulic pump draws cooled hydraulic oil from the oil tank to compensate the corresponding gas-liquid pressure conversion system. This allows for regulation of the initial gas pressure within the gas-liquid pressure conversion system, enabling one system to operate while the other prepares, ensuring stable and continuous alternating operation of both systems. This, in turn, ensures the power generation system can stably and continuously output constant-frequency current. Attached Figure Description

[0057] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0058] Figure 1 This is a system schematic diagram of a specific embodiment of the present invention;

[0059] Figure 2 This is a cross-sectional view of the gas-liquid pressure conversion device in a specific embodiment of the present invention;

[0060] Figure 3 for Figure 2 A magnified view of a section at point A in the middle;

[0061] Figure 4 for Figure 2 A magnified view of a section at point B in the middle;

[0062] Figure 5 for Figure 2 A magnified view of a section at point C;

[0063] Figure 6 This is a schematic diagram of the fluid path in the first working process according to a specific embodiment of the present invention;

[0064] Figure 7 This is a schematic diagram of the fluid path in the second working process according to a specific embodiment of the present invention;

[0065] Figure 8 This is a schematic diagram of the fluid path in the third working process in a specific embodiment of the present invention;

[0066] Figure 9 This is a schematic diagram of the fluid path in the fourth working process of a specific embodiment of the present invention.

[0067] The attached diagram shows the markings and corresponding component names:

[0068] 1-Gas source pressure regulating device; 2-Inlet and outlet control valve assembly; 3-Mass flow regulating valve; 4-Mass flow sensor; 5-Check valve; 6-Gas-liquid pressure conversion device; 7-Gas pressure sensor; 8-Ultrasonic height sensor; 9-Oil pressure sensor; 10-Solenoid control valve; 11-Three-way control valve; 12-Accumulator; 13-Hydraulic oil directional valve; 14-Voltage flow meter; 15-Constant frequency AC power supply; 16-Variable frequency controller; 17-Asynchronous generator; 18-Flywheel energy storage and control system; 19-Gearbox; 20-One-way hydraulic motor; 21-Temperature sensor; 22-Overflow regulating valve. 23-Pressure regulating valve, 24-Heat exchanger bypass valve, 25-Gas-liquid heat exchanger, 26-Oil tank, 27-Filter, 28-Hydraulic oil pump, 29-Battery pack, 30-Power conversion device, 31-Motor, 32-Hydraulic oil pressure limiter, 33-Hydraulic oil replenishment control valve, 34-Distribution control valve, 35-Safety valve; 36-Piston support ring, 37-PTFE vinyl composite ring, 38-Spring energy storage sealing ring, 39-O-ring and retaining ring sealing assembly, 40-Reversible U-shaped sealing ring, 41-I-shaped piston, 42-Cylinder body, 43-Piston limiting device, 44-Separator;

[0069] 101 - Natural gas source pipeline; 102 - Natural gas gathering and transmission pipeline; 103 - Exhaust gas gathering and transmission pipeline within the system; 104 - Intake gas distribution pipeline within the system.

[0070] 201-Gas source flow regulating valve assembly; 202-Hybrid power supply subsystem;

[0071] 301-Air inlet, 302-Exhaust outlet, 303-Oil replenishment port, 304-Inlet / outlet of fluid, 305-Gas working chamber, 306-Hydraulic oil working chamber, 307-Gas buffer chamber, 308-Drain valve, 309-Drain oil outlet, 310-Hydraulic oil buffer chamber. Detailed Implementation

[0072] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments and accompanying drawings. The illustrative embodiments and descriptions of this invention are for explaining the invention only and are not intended to limit the invention. In the description of this application, it should be understood that terms such as "front," "rear," "left," "right," "upper," "lower," "vertical," "horizontal," "high," "low," "inner," and "outer," indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description. They 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 limiting the scope of protection of this application.

[0073] Example 1:

[0074] like Figures 1 to 5 This illustrates a wide-condition gas-liquid coupling differential pressure power generation system designed for complex wellhead gas conditions.

[0075] It includes a natural gas source pipeline 101, a natural gas gathering and transmission pipeline 102, an internal gas intake distribution pipeline 104 connected to the natural gas source pipeline 101, an internal exhaust gathering and transmission pipeline 103 connected to the natural gas gathering and transmission pipeline 102, an intake and exhaust control valve group 2, a first gas-liquid pressure conversion system, a second gas-liquid pressure conversion system, a hydraulic oil reversing valve 13, and a power generation system;

[0076] The intake and exhaust control valve group 2 is connected to the intake distribution pipeline 104, the exhaust collection and transportation pipeline 103, the first gas-liquid pressure conversion system, and the second gas-liquid pressure conversion system in the system, and is used to control the flow path of gas in the first gas-liquid pressure conversion system and the second gas-liquid pressure conversion system.

[0077] The hydraulic oil reversing valve 13 is connected to the first gas-liquid pressure conversion system, the second gas-liquid pressure conversion system and the power generation system, and is used to control the flow path of hydraulic oil in the first gas-liquid pressure conversion system and the second gas-liquid pressure conversion system.

[0078] The hydraulic oil output from the hydraulic oil reversing valve 13 flows through the power generation system and then flows back to the hydraulic oil reversing valve 13.

[0079] In this embodiment, the power generation system includes a one-way hydraulic motor 20 connected to the hydraulic oil reversing valve 13. The output end of the one-way hydraulic motor 20 is sequentially connected to a transmission 19, a flywheel energy storage and control system 18, an asynchronous generator 17, and a frequency converter 16, for outputting constant frequency AC power 15 to achieve power generation. Furthermore, a gas source pressure regulating device 1 is installed between the natural gas source pipeline 101 and the system's intake distribution pipeline 104 to regulate the gas pressure entering the system's intake distribution pipeline 104. A volumetric flow meter 14 can also be installed upstream of the one-way hydraulic motor 20 to monitor the volumetric flow rate of the hydraulic oil entering the one-way hydraulic motor 20.

[0080] Both the first gas-liquid pressure conversion system and the second gas-liquid pressure conversion system include N gas-liquid pressure conversion devices 6, where N is an even number; the N gas-liquid pressure conversion devices 6 are grouped in pairs; for two gas-liquid pressure conversion devices 6 in the same group, when one converts gas pressure energy into hydraulic pressure energy, the other converts hydraulic pressure energy into gas pressure energy.

[0081] In this embodiment, as Figure 1 As shown, the first gas-liquid pressure conversion system consists of two gas-liquid pressure conversion devices 6, A1 and A2, and the second gas-liquid pressure conversion system consists of two gas-liquid pressure conversion devices 6, B1 and B2.

[0082] In this embodiment, the gas-liquid pressure conversion device 6 is as follows: Figures 2 to 5 As shown, the system includes a cylinder body 42, a partition 44 located inside the cylinder body 42, and an I-shaped piston 41 that moves through the partition 44. Both ends of the I-shaped piston 41 are dynamically sealed to the inner wall of the cylinder body 42. The piston rod of the I-shaped piston 41 is dynamically sealed to the partition 44. One end of the I-shaped piston 41 faces away from the partition 44 and forms a gas working chamber 305 with the cylinder body 42. The other end of the I-shaped piston 41 faces away from the partition 44 and forms a hydraulic oil working chamber 306 with the cylinder body 42. In this embodiment, the partition 44 is integrally formed with the cylinder body 42, that is, the partition 44 is a component belonging to the cylinder body 42.

[0083] It also includes an air inlet 301, an exhaust port 302, a fluid inlet / outlet 304, and a replenishment port 303 formed on the surface of the cylinder body 42; the air inlet 301 and the exhaust port 302 are both connected to the gas working chamber 305, and the fluid inlet / outlet 304 and the replenishment port 303 are both connected to the hydraulic oil working chamber 306; the hydraulic oil working chamber 306 is connected to the hydraulic oil reversing valve 13; accumulators 12 are installed on both the upstream and downstream pipelines of the hydraulic oil reversing valve 13. The accumulator 12 is preferably a piston-type accumulator.

[0084] The air inlet 301 and the exhaust outlet 302 are both connected to the air intake and exhaust control valve group 2, and the liquid inlet and outlet 304 are connected to the hydraulic oil reversing valve 13; an electromagnetic control valve 10 is provided between the liquid inlet and outlet 304 and the hydraulic oil reversing valve 13.

[0085] The two ends of the I-shaped piston 41 and the partition 44 respectively form a gas buffer chamber 307 and a hydraulic oil buffer chamber 310; the gas buffer chamber 307 and the gas working chamber 305 are located on the same side of the partition 44, and the hydraulic oil buffer chamber 310 and the hydraulic oil working chamber 306 are located on the same side of the partition 44.

[0086] The gas buffer chamber 307 is provided with a drain valve 308 on its side wall, and the hydraulic oil buffer chamber 310 is provided with a drain port 309 on its side wall; it also includes piston limiting devices 43 installed at both ends of the I-shaped piston 41, and the piston limiting devices 43 are used to limit the stroke of the I-shaped piston 41.

[0087] In this embodiment, in order to monitor and respond to the source gas pressure, hydraulic oil inlet volume, and position of the I-shaped piston 41, a gas pressure sensor 7 and a height sensor 8 are also installed in the gas working chamber 305, and an oil pressure sensor 9 is installed in the hydraulic oil working chamber 306. The gas pressure sensor 7 is used to monitor the gas pressure in the gas working chamber 305, the height sensor 8 is used to monitor the relative position of the I-shaped piston 41 in the cylinder, and the oil pressure sensor 9 is used to monitor the oil pressure in the hydraulic oil working chamber 306.

[0088] In this embodiment, the dynamic seal inside the gas-liquid pressure conversion device 6 is configured as follows: Figures 2 to 5 As shown, if the two ends of the I-shaped piston 41 are defined as the gas working condition end and the hydraulic oil working condition end, respectively, then:

[0089] Between the gas working end of the I-shaped piston 41 and the inner wall of the cylinder 42, a combined seal is achieved through the piston support ring 36, the polytetrafluoroethylene composite ring 37, and the spring energy storage sealing ring 38, wherein the polytetrafluoroethylene composite ring 37 serves as the main sealing element and the spring energy storage sealing ring 38 serves as the auxiliary sealing element.

[0090] A dynamic seal is achieved between the hydraulic oil working end of the I-shaped piston 41 and the inner wall of the cylinder 42 through the piston support ring 36 and the U-shaped sealing rings 40 installed in opposite directions; those skilled in the art should understand that the U-shaped sealing rings 40 installed in opposite directions are a pair of U-shaped sealing rings installed in opposite directions.

[0091] A dynamic seal is achieved between the piston rod of the I-shaped piston 41 and the partition 44 through the piston support ring 36, the O-ring seal and the retaining ring seal assembly 39.

[0092] In this embodiment, the intake and exhaust control valve group 2 includes four two-position three-way valves, which correspond one-to-one with four pressure conversion devices 6, namely A1, A2, B1, and B2. The two-position three-way valves are connected to the intake distribution pipeline 104, the exhaust collection and transportation pipeline 103, and the gas working chamber 305 in the system.

[0093] In a more preferred embodiment, a gas source flow regulating valve group 201 is provided between each two-position three-way valve and the corresponding pressure conversion device 6 to regulate the mass flow rate of the source gas. Specifically, the gas source flow regulating valve group 201 includes a mass flow regulating valve 3, a mass flow sensor 4, and a one-way valve 5 arranged sequentially.

[0094] In a more preferred embodiment, the piston limiting device 43 is an annular component, which is fixedly connected to the end of the I-shaped piston 41 by bolts; the annular component is coaxial with the I-shaped piston 41, and the outer diameter of the annular component is smaller than the diameter of the end face of the I-shaped piston 41.

[0095] Example 2:

[0096] A wide-condition gas-liquid coupling differential pressure power generation system for complex wellhead gas, based on Example 1, such as... Figures 1 to 5 As shown,

[0097] It also includes a temperature sensor 21, which is used to monitor the temperature of the hydraulic oil flowing through the power generation system; an overflow control valve 22 is provided on the path of the hydraulic oil flowing back from the power generation system to the hydraulic oil reversing valve 13, and the temperature sensor 21 is signal-connected to the overflow control valve 22.

[0098] It also includes a gas-liquid heat exchanger 25;

[0099] The overflow control valve 22 is connected to the liquid input terminal of the gas-liquid heat exchanger 25, and the liquid output terminal of the gas-liquid heat exchanger 25 is connected to the oil tank 26; the gas input terminal of the gas-liquid heat exchanger 25 is connected to the exhaust gas collection and transportation pipeline 103 in the system, and the gas output terminal of the gas-liquid heat exchanger 25 is connected to the natural gas collection and transportation pipeline 102.

[0100] In this embodiment, a pressure regulating valve 23 is provided between the overflow regulating valve 22 and the gas-liquid heat exchanger 25 to control the hydraulic oil pressure entering the gas-liquid heat exchanger 25.

[0101] The output end of the oil tank 26 is connected in sequence to the filter 27, the hydraulic oil pump 28, the hydraulic oil pressure limiter 32, the hydraulic oil replenishment control valve 33, and the distribution control valve 34; the distribution control valve 34 is used to replenish hydraulic oil to the first gas-hydraulic pressure conversion system and the second gas-hydraulic pressure conversion system.

[0102] In this embodiment, the distribution control valve 34 is used to control four oil circuits, which are respectively connected to the oil replenishment port 303 of the four pressure conversion devices 6, namely A1, A2, B1, and B2, and can pump hydraulic oil into the hydraulic oil working chamber 306 of the corresponding pressure conversion device 6 as needed.

[0103] In addition, any leaked or contaminated hydraulic oil from the power generation system, hydraulic oil pressure limiter 32, and hydraulic oil replenishment control valve 33 flows back to the oil tank 26.

[0104] In this embodiment, the exhaust gas gathering and transmission pipeline 103 and the natural gas gathering and transmission pipeline 102 are also connected by a first bypass pipeline, and a safety valve 35 is installed on the first bypass pipeline; the overflow control valve 22 and the oil tank 26 are also connected by a second bypass pipeline, and a heat exchanger bypass valve 24 is installed on the second bypass pipeline.

[0105] In a more preferred embodiment, the hydraulic pump 28 is driven by an electric motor 31.

[0106] In a more preferred embodiment, a power supply system 202 is also included for supplying power to the hydraulic pump 28 or the electric motor 31. The power supply system 202 includes a battery pack 29 and a power conversion device 30. In the initial stage of starting up this application, power is supplied by the battery pack 29; once the application is running stably and the power generation system stably outputs constant frequency AC power 15, the constant frequency AC power 15 generated by this application can be used directly for power supply.

[0107] In a more preferred embodiment, the natural gas source pipeline 101 and the natural gas gathering and transmission pipeline 102 can be connected by a third bypass pipeline, and a safety valve is correspondingly installed on the third bypass pipeline.

[0108] Example 3:

[0109] A wide-condition gas-liquid coupled differential pressure power generation system for complex wellhead gas, based on Embodiment 1 or 2, such as... Figures 1 to 9 As shown, the power generation methods include:

[0110] First working process:

[0111] The first gas-liquid pressure conversion system is set to "constant differential pressure power generation" state, with the hydraulic oil flowing from gas-liquid pressure conversion device A1 to gas-liquid pressure conversion device A2; the second gas-liquid pressure conversion system is set to "pressure regulating pre-power generation" state; for details, please refer to... Figure 6 :

[0112] Control the intake and exhaust control valve group 2 to connect the intake distribution pipeline 104 in the system with the gas working chamber 305 of the gas-liquid pressure conversion devices A1 and A2, and the gas flow direction is: gas flows unidirectionally from the intake distribution pipeline 104 in the system to the gas-liquid pressure conversion device A1, and from the gas-liquid pressure conversion device A2 to the intake distribution pipeline 104 in the system; open V A-1 V A-2 Turn off V B-1 V B-2 Three-way control valve V1 is connected to the A1 passage of device, and three-way control valve V2 is connected to the A2 passage of device.

[0113] Gas from the wellhead enters the gas distribution pipeline 104 within the system via the natural gas source pipeline 101, and then enters the gas working chamber 305 of the gas-liquid pressure conversion device A1 via the intake and exhaust control valve group 2. The hydraulic oil discharged from the gas-liquid pressure conversion device A1 enters the power generation system via the hydraulic oil reversing valve 13. After flowing through the power generation system, part of the hydraulic oil flows back to the hydraulic oil reversing valve 13 and enters the hydraulic oil working chamber 306 of the gas-liquid pressure conversion device A2. The gas discharged from the gas-liquid pressure conversion device A2 passes through the intake and exhaust control valve group 2, enters the gas path of the gas-liquid heat exchanger 25 via the exhaust gathering and transmission pipeline 103 within the system, and then enters the natural gas gathering and transmission pipeline 102 after flowing through the gas-liquid heat exchanger 25.

[0114] Meanwhile, some of the hydraulic oil flowing through the power generation system enters the oil circuit of the gas-liquid heat exchanger 25 through the overflow control valve 22, and then enters the oil tank 26 after flowing through the gas-liquid heat exchanger 25.

[0115] At the same time, hydraulic oil is drawn from the oil tank 26 by the hydraulic oil pump 28, and the distribution control valve 34 is switched to conduct to the gas-hydraulic pressure conversion device B1, so as to replenish the gas-hydraulic pressure conversion device B1 and make its internal oil pressure reach the set state.

[0116] When the I-shaped piston in the gas-liquid pressure conversion device A1 moves to the end of its stroke, the first working process ends and the second working process begins.

[0117] Second working process:

[0118] The second gas-liquid pressure conversion system is set to "constant differential pressure power generation" state, with the hydraulic oil flowing from gas-liquid pressure conversion device B1 to gas-liquid pressure conversion device B2; the first gas-liquid pressure conversion system is set to "pressure regulating pre-power generation" state; for details, please refer to... Figure 7 :

[0119] Switch the intake and exhaust control valve group 2 to connect the intake distribution pipe 104 in the system with the gas working chamber 305 of the gas-liquid pressure conversion devices B1 and B2, and make the gas flow direction: the gas flows unidirectionally from the intake distribution pipe 104 in the system to the gas-liquid pressure conversion device B1, and from the gas-liquid pressure conversion device B2 to the intake distribution pipe 104 in the system; open V B-1 V B-2 Turn off V A-1 V A-2 Three-way control valve V1 is connected to the B1 passage, and three-way control valve V2 is connected to the B2 passage.

[0120] Gas from the wellhead enters the gas distribution pipeline 104 within the system via the natural gas source pipeline 101, and then enters the gas working chamber 305 of the gas-liquid pressure conversion device B1 via the intake and exhaust control valve group 2. The hydraulic oil discharged from the gas-liquid pressure conversion device B1 enters the power generation system via the hydraulic oil reversing valve 13. After flowing through the power generation system, part of the hydraulic oil flows back to the hydraulic oil reversing valve 13 and enters the hydraulic oil working chamber 306 of the gas-liquid pressure conversion device B2. The gas discharged from the gas-liquid pressure conversion device B2 passes through the intake and exhaust control valve group 2, enters the gas path of the gas-liquid heat exchanger 25 via the exhaust gathering and transmission pipeline 103 within the system, and then enters the natural gas gathering and transmission pipeline 102 after flowing through the gas-liquid heat exchanger 25.

[0121] Meanwhile, some of the hydraulic oil flowing through the power generation system enters the oil circuit of the gas-liquid heat exchanger 25 through the overflow control valve 22, and then enters the oil tank 26 after flowing through the gas-liquid heat exchanger 25.

[0122] At the same time, hydraulic oil is drawn from the oil tank 26 by the hydraulic oil pump 28, and the distribution control valve 34 is switched to conduct to the gas-hydraulic pressure conversion device A2, so as to replenish the gas-hydraulic pressure conversion device A2 and make its internal oil pressure reach the set state.

[0123] When the I-shaped piston in the gas-liquid pressure conversion device B1 moves to the end of its stroke, the second working process ends and the third working process begins.

[0124] Third working process:

[0125] The first gas-liquid pressure conversion system is set to "constant differential pressure power generation" state, with the hydraulic oil flowing from gas-liquid pressure conversion device A2 to gas-liquid pressure conversion device A1; the second gas-liquid pressure conversion system is set to "pressure regulating pre-power generation" state; for details, please refer to... Figure 8 :

[0126] Switch the intake and exhaust control valve group 2 to connect the intake distribution pipe 104 in the system with the gas working chamber 305 of the gas-liquid pressure conversion devices A1 and A2, and make the gas flow direction: the gas flows unidirectionally from the intake distribution pipe 104 in the system to the gas-liquid pressure conversion device A2, and unidirectionally from the gas-liquid pressure conversion device A1 to the intake distribution pipe 104 in the system; open V A-1 V A-2 Turn off V B-1 V B-2 Three-way control valve V1 is connected to the A1 passage of device, and three-way control valve V2 is connected to the A2 passage of device.

[0127] Gas from the wellhead enters the gas distribution pipeline 104 within the system via the natural gas source pipeline 101, and then enters the gas working chamber 305 of the gas-liquid pressure conversion device A2 via the intake and exhaust control valve group 2. The hydraulic oil discharged from the gas-liquid pressure conversion device A2 enters the power generation system via the hydraulic oil reversing valve 13. After flowing through the power generation system, part of the hydraulic oil flows back to the hydraulic oil reversing valve 13 and enters the hydraulic oil working chamber 306 of the gas-liquid pressure conversion device A1. The gas discharged from the gas-liquid pressure conversion device A1 passes through the intake and exhaust control valve group 2, enters the gas path of the gas-liquid heat exchanger 25 via the exhaust gathering and transmission pipeline 103 within the system, and then enters the natural gas gathering and transmission pipeline 102 after flowing through the gas-liquid heat exchanger 25.

[0128] Meanwhile, some of the hydraulic oil flowing through the power generation system enters the oil circuit of the gas-liquid heat exchanger 25 through the overflow control valve 22, and then enters the oil tank 26 after flowing through the gas-liquid heat exchanger 25.

[0129] At the same time, hydraulic oil is drawn from the oil tank 26 by the hydraulic oil pump 28, and the distribution control valve 34 is switched to conduct to the gas-hydraulic pressure conversion device B2, so as to replenish the hydraulic oil in the gas-hydraulic pressure conversion device B2 and keep its internal oil pressure at the set state.

[0130] When the I-shaped piston in the gas-liquid pressure conversion device A2 moves to the end of its stroke, the third working process ends and the fourth working process begins.

[0131] Fourth working process:

[0132] The second gas-liquid pressure conversion system is set to "constant differential pressure power generation" state, with the hydraulic oil flowing from gas-liquid pressure conversion device B2 to gas-liquid pressure conversion device B1; the first gas-liquid pressure conversion system is set to "pressure regulating pre-power generation" state; for details, please refer to... Figure 9 :

[0133] Switch the intake and exhaust control valve group 2 to connect the intake distribution pipe 104 in the system with the gas working chamber 305 of the gas-liquid pressure conversion devices B1 and B2, and make the gas flow direction: the gas flows unidirectionally from the intake distribution pipe 104 in the system to the gas-liquid pressure conversion device B2, and from the gas-liquid pressure conversion device B1 to the intake distribution pipe 104 in the system; open V B-1 V B-2 Turn off V A-1 V A-2 Three-way control valve V1 is connected to the B1 passage, and three-way control valve V2 is connected to the B2 passage.

[0134] Gas from the wellhead enters the gas distribution pipeline 104 within the system via the natural gas source pipeline 101, and then enters the gas working chamber 305 of the gas-liquid pressure conversion device B2 via the intake and exhaust control valve group 2. The hydraulic oil discharged from the gas-liquid pressure conversion device B2 enters the power generation system via the hydraulic oil reversing valve 13. After flowing through the power generation system, part of the hydraulic oil flows back to the hydraulic oil reversing valve 13 and enters the hydraulic oil working chamber 306 of the gas-liquid pressure conversion device B1. The gas discharged from the gas-liquid pressure conversion device B1 passes through the intake and exhaust control valve group 2, enters the gas path of the gas-liquid heat exchanger 25 via the exhaust gathering and transmission pipeline 103 within the system, and then enters the natural gas gathering and transmission pipeline 102 after flowing through the gas-liquid heat exchanger 25.

[0135] Meanwhile, some of the hydraulic oil flowing through the power generation system enters the oil circuit of the gas-liquid heat exchanger 25 through the overflow control valve 22, and then enters the oil tank 26 after flowing through the gas-liquid heat exchanger 25.

[0136] At the same time, hydraulic oil is drawn from the oil tank 26 by the hydraulic oil pump 28, and the distribution control valve 34 is switched to conduct to the gas-hydraulic pressure conversion device A1, so as to replenish the gas-hydraulic pressure conversion device A1 and make its internal oil pressure reach the set state.

[0137] When the I-shaped piston in the gas-liquid pressure conversion device B2 moves to the end of its stroke, the fourth working process ends and the first working process is repeated.

[0138] It should be noted that, in Figures 6 to 9 In the diagram, the bold lines represent the main flow paths of the gas and liquid phases in the system of this application; the dashed lines represent the return and replenishment paths of the hydraulic oil.

[0139] As can be seen, the power generation method adopted in this application achieves alternating power generation and pressure adjustment through coordinated control and scheduling between two sets of gas-liquid pressure conversion systems. This overcomes the problem of existing technologies requiring more than three sets of equipment and precise control of the discharge volume and phase between each set to ensure the stability of fluid mechanical output, effectively reducing the number of core equipment and the control system's regulatory burden. Furthermore, the system in this application employs a "coordinated scheduling and control + dynamic compensation + combined stepped sealing" scheme, which allows the system to maintain a stable power generation operation state while avoiding cross-contamination of media.

[0140] This application enables the system to maintain the real-time pressure head, volumetric flow rate, and total fluid inflow of the hydraulic oil input to the unidirectional hydraulic motor 20 within the rated operating range during scheduling at different operating stages. This reduces fluctuations in system operating parameters caused by the coordinated control process, thereby avoiding interference with the system's external constant-frequency power generation stability. Furthermore, it addresses the hydraulic oil leakage and overheating issues caused by high pressure head and operating differential pressure on the unidirectional hydraulic motor 20, preventing high-temperature degradation and failure of the hydraulic oil while eliminating the need for frequent external hydraulic oil replenishment.

[0141] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0142] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Additionally, the term "connection" as used herein, unless otherwise specified, can refer to a direct connection or an indirect connection via other components.

Claims

1. A wide working condition gas-liquid coupled differential pressure power generation system for complex wellhead gas, comprising a natural gas source pipeline (101), a natural gas gathering pipeline (102), characterized in that, Further comprising a system internal gas inlet distribution pipeline (104) connected with the natural gas source pipeline (101), a system internal gas outlet gathering pipeline (103) connected with the natural gas gathering pipeline (102), an inlet and outlet gas control valve group (2), a first gas-liquid pressure conversion system, a second gas-liquid pressure conversion system, a hydraulic oil reversing valve (13), and a power generation system; The inlet and outlet gas control valve group (2) is connected with the system internal gas inlet distribution pipeline (104), the system internal gas outlet gathering pipeline (103), and the first gas-liquid pressure conversion system and the second gas-liquid pressure conversion system, and is used for controlling the flow path of the gas in the first gas-liquid pressure conversion system and the second gas-liquid pressure conversion system; The hydraulic oil reversing valve (13) is connected with the first gas-liquid pressure conversion system, the second gas-liquid pressure conversion system, and the power generation system, and is used for controlling the flow path of the hydraulic oil in the first gas-liquid pressure conversion system and the second gas-liquid pressure conversion system; The hydraulic oil output from the hydraulic oil reversing valve (13) flows through the power generation system and then returns to the hydraulic oil reversing valve (13); The first gas-liquid pressure conversion system and the second gas-liquid pressure conversion system each comprise N gas-liquid pressure conversion devices (6), wherein N is an even number; The N gas-liquid pressure conversion devices (6) are grouped into pairs; For the two gas-liquid pressure conversion devices (6) in the same group, one converts gas pressure energy into hydraulic energy, and the other converts hydraulic energy into gas pressure energy; Further comprising a temperature sensor (21) used for monitoring the oil temperature of the hydraulic oil flowing through the power generation system; an overflow control valve (22) is arranged on the path of the hydraulic oil returning to the hydraulic oil reversing valve (13) through the power generation system, and the temperature sensor (21) is signal connected with the overflow control valve (22); Further comprising a gas-liquid heat exchanger (25); The overflow control valve (22) is connected to the liquid input end of the gas-liquid heat exchanger (25), the liquid output end of the gas-liquid heat exchanger (25) is communicated to an oil tank (26), the gas input end of the gas-liquid heat exchanger (25) is connected with the system internal gas outlet gathering pipeline (103), and the gas output end of the gas-liquid heat exchanger (25) is connected with the natural gas gathering pipeline (102).

2. The wide operating condition gas-liquid coupled differential pressure power generation system for complex wellhead gas according to claim 1, characterized in that, The gas-liquid pressure conversion device (6) comprises a cylinder body (42), a partition (44) located inside the cylinder body (42), and an I-shaped piston (41) movably penetrating through the partition (44); Both ends of the I-shaped piston (41) are in dynamic sealing cooperation with the inner wall of the cylinder body (42), and the piston rod of the I-shaped piston (41) is in dynamic sealing cooperation with the partition (44); One end of the I-shaped piston (41) is away from one side of the partition (44), and forms a gas working chamber (305) with the cylinder body (42); the other end of the I-shaped piston (41) is away from one side of the partition (44), and forms a hydraulic oil working chamber (306) with the cylinder body (42); Further comprising an air inlet (301), an exhaust port (302), an inlet and outlet liquid port (304) and an oil supplement port (303) opened on the surface of the cylinder (42); the air inlet (301) and the exhaust port (302) are communicated with the gas working chamber (305), and the inlet and outlet liquid port (304) and the oil supplement port (303) are communicated with the hydraulic oil working chamber (306); The hydraulic oil working chamber (306) is communicated to the hydraulic oil reversing valve (13); the upstream and downstream pipelines of the hydraulic oil reversing valve (13) are both provided with an accumulator (12).

3. The wide operating condition gas-liquid coupled differential pressure power generation system for complex wellhead gas according to claim 2, characterized in that, The air inlet (301) and the exhaust port (302) are connected with the inlet and outlet gas control valve group (2), and the inlet and outlet liquid port (304) is connected with the hydraulic oil reversing valve (13); an electromagnetic control valve (10) is arranged between the inlet and outlet liquid port (304) and the hydraulic oil reversing valve (13).

4. The wide operating condition gas-liquid coupled differential pressure power generation system for complex wellhead gas according to claim 2, characterized in that, The two ends of the I-shaped piston (41) and the separation part (44) form a gas buffer chamber (307) and a hydraulic oil buffer chamber (310) respectively; the gas buffer chamber (307) and the gas working chamber (305) are located on the same side of the separation part (44), and the hydraulic oil buffer chamber (310) and the hydraulic oil working chamber (306) are located on the same side of the separation part (44); A blow-off gas valve (308) is arranged on the side wall of the gas buffer chamber (307), and a blow-off oil port (309) is arranged on the side wall of the hydraulic oil buffer chamber (310); further comprising a piston limiting device (43) mounted on the two ends of the I-shaped piston (41), and the piston limiting device (43) is used for limiting the stroke of the I-shaped piston (41).

5. The wide operating condition gas-liquid coupled pressure difference power generation system for complex wellhead gas according to claim 2, characterized in that, The inlet and outlet gas control valve group (2) comprises N two-position three-way valves, and the two-position three-way valves correspond to the gas-liquid pressure conversion device (6) one by one; The two-position three-way valves are connected with the system internal inlet gas distribution pipeline (104), the system internal exhaust gas gathering pipeline (103) and the gas working chamber (305).

6. The wide operating condition gas-liquid coupled pressure difference power generation system for complex wellhead gas according to claim 1, characterized in that, The output end of the oil tank (26) is connected with a filter (27), a hydraulic oil pump (28), a hydraulic oil pressure limiter (32), a hydraulic oil supplement control valve (33) and a distribution control valve (34) in sequence; the distribution control valve (34) is used for supplementing hydraulic oil to the first gas-liquid pressure conversion system and the second gas-liquid pressure conversion system.

7. The wide operating condition gas-liquid coupled pressure difference power generation system for complex wellhead gas according to claim 6, characterized in that, The leaked and / or blow-off hydraulic oil of the power generation system, the hydraulic oil pressure limiter (32) and the hydraulic oil supplement control valve (33) is all returned to the oil tank (26).

8. The wide operating condition gas-liquid coupled pressure difference power generation system for complex wellhead gas according to claim 1, characterized in that, The system internal exhaust gas gathering pipeline (103) and the natural gas gathering pipeline (102) are further connected through a first bypass pipeline, and a safety valve (35) is arranged on the first bypass pipeline; The overflow control valve (22) and the oil tank (26) are further connected through a second bypass pipeline, and a heat exchanger bypass valve (24) is arranged on the second bypass pipeline.

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