A natural gas differential pressure power generation system and operation method adapted to gas production and gas injection

Abstract

The application discloses a natural gas pressure difference power generation system and operation method suitable for gas production and gas injection, which comprises a former gas production period pressure regulating system, a former gas injection period pressure regulating system and a natural gas expander; the former gas production period pressure regulating system comprises a first inlet pipeline, a first valve group and a first outlet pipeline; the first inlet pipeline is provided with a first inlet branch; the first outlet pipeline is provided with a first outlet branch; the natural gas expander is connected with a third inlet pipeline at an inlet end and connected with a third outlet pipeline at an outlet end; the third inlet pipeline is connected with the first inlet branch at an inlet end; the third outlet pipeline is connected with the first outlet branch at an outlet end; the former gas injection period pressure regulating system comprises a second inlet pipeline, a second valve group and a second outlet pipeline; the second inlet pipeline is provided with a second inlet branch, and the other end of the second inlet branch is connected to the third inlet pipeline; the second outlet pipeline is provided with a second outlet branch, and the other end of the second outlet branch is connected to the third outlet pipeline. The application can reduce investment and improve annual utilization hours.

Description

Technical Field

[0001] This invention relates to the field of differential pressure power generation, specifically a natural gas differential pressure power generation system and its operation method adapted to gas extraction and injection. Background Technology

[0002] In the operation of a gas storage facility, natural gas needs to go through a periodic switching between gas injection and gas extraction periods.

[0003] Typically, the gas extraction period is from November to March of the following year, and the gas injection period is from April to October.

[0004] During the gas extraction period, the high-pressure natural gas extracted from the storage facility must pass through a pressure regulating valve group to reduce its pressure to the design pressure required by the external transmission network before it can be sent into the gas transmission pipeline. During the gas injection period, the high-pressure natural gas from the long-distance pipeline also needs to be reduced to the rated pressure at the inlet of the gas injection compressor by the pressure regulating valve group before it can be injected into the compressor for pressurization and stored in the storage.

[0005] It is evident that, regardless of the gas extraction or injection phase, there is always a usable natural gas pressure differential in the pipeline. This pressure difference is typically dissipated directly through the throttling and pressure regulating valve assembly, resulting in energy waste.

[0006] To recover this residual pressure energy, existing technologies have proposed technical solutions that use turbine expander generator sets to replace or partially replace traditional pressure regulating valve sets.

[0007] However, conventional practices have significant shortcomings for special application scenarios such as gas storage facilities, which have both gas extraction and injection periods, and where the working fluid parameters such as gas source direction, pressure, temperature, and flow rate differ significantly between the two periods. Since the operating parameters during the gas extraction and injection periods often differ greatly, in order to ensure that the expansion generator set can maintain acceptable power generation efficiency in both periods, it is usually necessary to select an independent differential pressure generator set for each of the gas extraction and injection periods, with each set supplying natural gas to its corresponding pipeline system and operating independently.

[0008] While this separate configuration solves the adaptability problem for different operating conditions, it also brings two obvious drawbacks: First, the overall investment increases significantly—both generator sets and their associated pipelines, valves, control systems, etc., need to be configured as a complete set, significantly increasing equipment purchase costs and engineering construction expenses; second, the unit utilization rate is low—only the gas extraction generator set operates during the gas extraction period, and only the gas injection generator set operates during the gas injection period. The annual utilization hours of a single unit are difficult to exceed approximately 4,000 hours, and the equipment is idle or semi-idle for a long time, seriously affecting the economics of the project.

[0009] Therefore, how to reduce the number of expansion generator units, lower overall investment, and effectively increase the annual utilization hours of the equipment while ensuring that the operating requirements of the two different working conditions during the gas extraction and injection periods are met has become an urgent technical problem to be solved in the field of differential pressure power generation in gas storage facilities. Summary of the Invention

[0010] The purpose of this invention is to address the shortcomings of existing technologies by providing a natural gas differential pressure power generation system and its operation method that effectively reduces the number of expansion generator sets, lowers overall investment, and effectively increases the annual utilization hours of the equipment, adapting to both gas extraction and injection.

[0011] The technical objective of this invention is achieved through the following technical solution: A natural gas differential pressure power generation system adapted for gas extraction and injection includes a pressure regulating system for the original gas extraction period, a pressure regulating system for the original gas injection period, and a natural gas expander. The pressure regulating system for the original gas extraction period includes a first inlet pipe, a first valve group, and a first outlet pipe arranged sequentially along the flow direction. A first inlet pipe regulating valve is installed on the first inlet pipe, and a first inlet branch is led out from the first inlet pipe on the side of the first inlet pipe regulating valve away from the first valve group. A first outlet pipe regulating valve is installed on the first outlet pipe, and a first outlet branch is led out from the first outlet pipe on the side of the first outlet pipe regulating valve away from the first valve group. The inlet end of the natural gas expander is connected to a third inlet pipe, and its outlet end is connected to a third outlet pipe. The inlet end of the third inlet pipe is connected to the first inlet branch through a first inlet branch regulating valve. The outlet end of the third outlet pipe is connected to the first outlet branch via a first outlet branch regulating valve; the original gas injection period pressure regulating system includes a second inlet pipe, a second valve group, and a second outlet pipe arranged sequentially along the flow direction; a second inlet pipe regulating valve is provided on the second inlet pipe, and a second inlet branch is led out from the second inlet pipe on the side of the second inlet pipe regulating valve away from the second valve group, the other end of the second inlet branch is connected to the third inlet pipe, and a second inlet branch regulating valve is provided on the second inlet branch; a second outlet pipe regulating valve is provided on the second outlet pipe, and a second outlet branch is led out from the second outlet pipe on the side of the second outlet pipe regulating valve away from the second valve group, the other end of the second outlet branch is connected to the third outlet pipe, and a second outlet branch regulating valve is provided on the second outlet branch.

[0012] Preferably, the first inlet pipe regulating valve, the first outlet pipe regulating valve, the second inlet pipe regulating valve, the second outlet pipe regulating valve, the first inlet branch regulating valve, the first outlet branch regulating valve, the second inlet branch regulating valve, and the second outlet branch regulating valve are all electric regulating valves or pneumatic regulating valves.

[0013] Preferably, the first valve group and the second valve group are axial flow pressure regulating valves or cage sleeve pressure regulating valves.

[0014] Preferably, the natural gas expander is a centripetal turbine expander or an axial flow turbine expander, and is equipped with a generator.

[0015] An operating method for a natural gas differential pressure power generation system adapted to gas extraction and injection includes: During the gas extraction period, the first inlet branch control valve and the first outlet branch control valve are opened, while the second inlet branch control valve and the second outlet branch control valve are closed. At the same time, the first inlet pipeline control valve, the first valve group, the first outlet pipeline control valve, the second inlet pipeline control valve, the second valve group, and the second outlet pipeline control valve are closed. This allows the natural gas used for expansion power generation to enter the first inlet branch pipeline through the first inlet pipeline, then enter the third inlet pipeline through the first inlet branch control valve, and then enter the natural gas expander for power generation. After that, it enters the gas extraction period branch outlet pipeline through the third outlet pipeline and the first outlet branch control valve, and finally enters the subsequent process system pipeline through the first outlet pipeline. During the gas injection period, the second inlet branch regulating valve and the second outlet branch regulating valve are opened, while the first inlet branch regulating valve and the first outlet branch regulating valve are closed. At the same time, the first inlet pipeline regulating valve, the first valve group, the first outlet pipeline regulating valve, the second inlet pipeline regulating valve, the second valve group, and the second outlet pipeline regulating valve are closed. This allows the natural gas used for expansion power generation to enter the second inlet branch pipeline through the second inlet pipeline, then enter the third inlet pipeline through the second inlet branch regulating valve, and then enter the natural gas expander for power generation. After that, it enters the second outlet branch pipeline through the third outlet pipeline and the second outlet branch regulating valve, and finally enters the subsequent process system pipeline through the second outlet pipeline.

[0016] Furthermore, when the natural gas expander malfunctions and shuts down: If the current operation is during the gas production period, the first inlet branch regulating valve and the first outlet branch regulating valve will be interlocked and closed. By opening the first inlet pipeline regulating valve and the first outlet pipeline regulating valve, natural gas can enter the first outlet pipeline through the first inlet pipeline after being depressurized by the first valve group, and then enter the subsequent process system pipelines. If the current operation is during the gas injection period, the second inlet branch regulating valve and the second outlet branch regulating valve will be interlocked and closed, while the second inlet pipeline regulating valve and the second outlet pipeline regulating valve will be opened. Natural gas can enter the second outlet pipeline through the second inlet pipeline after being depressurized by the second valve group, and then enter the subsequent process system pipeline.

[0017] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention involves connecting parallel inlet / outlet branches for the gas production and injection phases to the existing pressure regulating pipelines during the original gas production and injection phases, respectively. Corresponding regulating valves are then installed on each branch and the existing pipelines. This allows natural gas from both the production and injection phases to share the same natural gas expander for differential pressure power generation via their respective branches. This technical measure significantly reduces the number of expander generator units and their auxiliary equipment, substantially lowering overall investment. Simultaneously, it increases the annual utilization hours of a single unit from approximately 4000 hours to approximately 8000 hours, enabling continuous operation throughout the year and effectively improving equipment utilization and the overall economic efficiency of the project. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the present invention; Reference numerals: 11—First inlet pipeline; 111—First inlet pipeline control valve; 12—First valve group; 13—First outlet pipeline; 131—First outlet pipeline control valve; 14—First inlet branch; 141—First inlet branch control valve; 151—First outlet branch; 151—First outlet branch control valve; 21—Second inlet pipeline; 211—Second inlet pipeline control valve; 22—Second valve group; 23—Second outlet pipeline; 231—Second outlet pipeline control valve; 24—Second inlet branch; 241—Second inlet branch control valve; 25—Second outlet branch; 251—Second outlet branch control valve; 3—Natural gas expander; 31—Third inlet pipeline; 32—Third outlet pipeline; Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0020] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0021] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0022] like Figure 1 As shown, a natural gas differential pressure power generation system adapted for gas extraction and injection includes a pressure regulating system for the original gas extraction period, a pressure regulating system for the original gas injection period, and a natural gas expander 3. The pressure regulating system for the original gas extraction period includes a first inlet pipe 11, a first valve group 12, and a first outlet pipe 13 arranged sequentially along the flow direction. A first inlet pipe regulating valve 111 is installed on the first inlet pipe 11, and a first inlet branch 14 is led out from the first inlet pipe 11 on the side of the first inlet pipe regulating valve 111 away from the first valve group 12. A first outlet pipe regulating valve 131 is installed on the first outlet pipe 13, and a first outlet branch 15 is led out from the first outlet pipe 13 on the side of the first outlet pipe regulating valve 131 away from the first valve group 12. The inlet end of the natural gas expander 3 is connected to a third inlet pipe 31, and its outlet end is connected to a third outlet pipe 32. The inlet end of the third inlet pipe 31 is connected to the first inlet branch 14 through a first inlet branch regulating valve 141. The outlet end of the outlet pipe 32 is connected to the first outlet branch 15 via the first outlet branch regulating valve 151; the original gas injection period pressure regulating system includes a second inlet pipe 21, a second valve group 22, and a second outlet pipe 23 arranged sequentially along the flow direction; a second inlet pipe regulating valve 211 is provided on the second inlet pipe 21, and a second inlet branch 24 is led out from the second inlet pipe 21 on the side of the second inlet pipe regulating valve 211 away from the second valve group 22, and the other end of the second inlet branch 24 is connected to the third inlet pipe 31, and a second inlet branch regulating valve 241 is provided on the second inlet branch 24; a second outlet pipe regulating valve 231 is provided on the second outlet pipe 23, and a second outlet branch 25 is led out from the second outlet pipe 23 on the side of the second outlet pipe regulating valve 231 away from the second valve group 22, and the other end of the second outlet branch 25 is connected to the third outlet pipe 32, and a second outlet branch regulating valve 251 is provided on the second outlet branch 25.

[0023] By connecting inlet / outlet branches for the gas production period and the injection period in parallel to the existing pressure regulating pipelines for both the original gas production and injection periods, and by configuring corresponding regulating valves for each branch and the original pipelines, natural gas from both periods can share the same natural gas expander 3 for differential pressure power generation via their respective branches. This technical measure significantly reduces the number of expander generator units and their auxiliary equipment, substantially lowers the overall investment, and increases the annual utilization hours of a single unit from approximately 4,000 hours to approximately 8,000 hours, enabling the unit to operate continuously throughout the year, effectively improving equipment utilization and the overall economic efficiency of the project.

[0024] like Figure 1As shown, the original gas production pressure regulating system includes a first inlet pipe 11, a first valve group 12, and a first outlet pipe 13 arranged sequentially along the flow direction. Specifically, the outlet end of the first inlet pipe 11 is connected to the inlet end of the first valve group 12, and the outlet end of the first valve group 12 is connected to the inlet end of the first outlet pipe 13.

[0025] like Figure 1 As shown, the original gas injection pressure regulating system includes a second inlet pipe 21, a second valve group 22, and a second outlet pipe 23 arranged sequentially along the flow direction. Specifically, the outlet of the second inlet pipe 21 is connected to the inlet of the second valve group 22, and the outlet of the second valve group 22 is connected to the inlet of the second outlet pipe 23.

[0026] In practical applications, the first inlet pipe regulating valve 111, the first outlet pipe regulating valve 131, the second inlet pipe regulating valve 211, the second outlet pipe regulating valve 231, the first inlet branch regulating valve 141, the first outlet branch regulating valve 151, the second inlet branch regulating valve 241, and the second outlet branch regulating valve 251 can all be electric or pneumatic regulating valves. Using uniformly configured electric or pneumatic regulating valves facilitates remote centralized control and interlocking protection of all valves in the system, improving the level of automation and operational reliability.

[0027] In practical applications, the first valve group 12 and the second valve group 22 can be axial flow pressure regulating valves or cage sleeve pressure regulating valves. Using axial flow or cage sleeve pressure regulating valves as valve groups can maintain stable pressure regulation accuracy and flow capacity over a wide operating range, ensuring stable and reliable downstream gas supply pressure when the power generation branch is switched off.

[0028] In practical use, the natural gas expander 3 is a radial turbine expander or an axial flow turbine expander, etc., and is equipped with a generator. By selecting a radial turbine or axial flow turbine expander as the core equipment for power generation, it can be compatible with the different chemical parameters during the gas extraction period and the gas injection period, so as to achieve efficient energy conversion and stable uninterrupted power generation throughout the year.

[0029] An operating method for a natural gas differential pressure power generation system adapted to gas extraction and injection includes: During the gas extraction period, the first inlet branch regulating valve 141 and the first outlet branch regulating valve 151 are opened, while the second inlet branch regulating valve 241 and the second outlet branch regulating valve 251 are closed. At the same time, the first inlet pipeline regulating valve 111, the first valve group 12, the first outlet pipeline regulating valve 131, the second inlet pipeline regulating valve 211, the second valve group 22, and the second outlet pipeline regulating valve 231 are closed. This allows the natural gas used for expansion power generation to enter the first inlet branch 14 pipeline through the original gas extraction period pressure regulating inlet pipeline (first inlet pipeline 11), then enter the natural gas expander inlet pipeline (third inlet pipeline 31) through the first inlet branch regulating valve 141, and then enter the natural gas expander 3 for power generation. After that, it enters the first outlet branch 15 through the natural gas expander outlet pipeline (third outlet pipeline 32) through the first outlet branch regulating valve 151, and finally enters the subsequent process system pipeline through the original gas extraction period pressure regulating outlet pipeline (first outlet pipeline 13).

[0030] During the gas injection period, the second inlet branch regulating valve 241 and the second outlet branch regulating valve 251 are opened, while the first inlet branch regulating valve 141 and the first outlet branch regulating valve 151 are closed. At the same time, the first inlet pipeline regulating valve 111, the first valve group 12, the first outlet pipeline regulating valve 131, the second inlet pipeline regulating valve 211, the second valve group 22, and the second outlet pipeline regulating valve 231 are closed. This allows the natural gas used for expansion power generation to enter the second inlet branch 24 pipeline through the original gas injection period pressure regulating inlet pipeline (second inlet pipeline 21), then enter the natural gas expander inlet pipeline (third inlet pipeline 31) through the second inlet branch regulating valve 241, and then enter the natural gas expander 3 for power generation. After that, it enters the second outlet branch 25 through the natural gas expander outlet pipeline (third outlet pipeline 32) and the second outlet branch regulating valve 251, and finally enters the subsequent process system pipeline through the original gas injection period pressure regulating outlet pipeline (second outlet pipeline 23).

[0031] By adopting this technical measure, the same natural gas expansion generator unit can adapt to the changes in natural gas flow direction and parameters under the two working conditions of gas extraction and gas injection in the gas storage facility. This achieves dual-purpose operation and avoids the need to set up two independent power generation systems. While saving equipment investment and land space, it significantly improves the annual utilization hours of the unit and the overall economic efficiency of the project.

[0032] When natural gas expander 3 malfunctions and shuts down: If the current operation is during the gas production period, the first inlet branch regulating valve 141 and the first outlet branch regulating valve 151 are interlocked and closed. In actual use, during the gas production period, the gas production period pressure regulating system remains closed and will not activate due to a fault shutdown. That is, during the gas production period, the second inlet pipeline regulating valve 211, the second valve group 22, the second outlet pipeline regulating valve 231, the second inlet branch regulating valve 241, and the second outlet branch regulating valve 251 remain closed and will not activate due to a fault shutdown. Opening the gas production period pressure regulating inlet pipeline regulating valve (first inlet pipeline regulating valve 111) and the gas production period pressure regulating outlet pipeline regulating valve (first outlet pipeline regulating valve 131) allows natural gas to enter the original gas production period pressure regulating outlet pipeline (first outlet pipeline 13) after being depressurized through the original gas production period pressure regulating inlet pipeline (first inlet pipeline 11) via the original gas production period pressure regulating valve group (first valve group 12), and then enter the subsequent process system pipelines.

[0033] If the current operation is during the gas injection period, the second inlet branch regulating valve 241 and the second outlet branch regulating valve 251 are interlocked and closed. In actual use, during the gas injection period, the gas extraction period pressure regulating system remains closed and will not activate due to a fault shutdown. During the gas injection period, the first inlet pipeline regulating valve 111, the first valve group 12, the first outlet pipeline regulating valve 131, the first inlet branch regulating valve 141, and the first outlet branch regulating valve 151 remain closed and will not activate due to a fault shutdown. Opening the gas injection period pressure regulating inlet pipeline regulating valve (second inlet pipeline regulating valve 211) and the gas injection period pressure regulating outlet pipeline regulating valve (second outlet pipeline regulating valve 231) allows natural gas to enter the original gas injection period pressure regulating outlet pipeline (second outlet pipeline 23) after being depressurized via the original gas injection period pressure regulating inlet pipeline (second inlet pipeline 21) and the original gas injection period pressure regulating valve group (second valve group 22), and then enter the subsequent process system pipelines.

[0034] By automatically interlocking and switching to the original pressure regulating pipeline when the expander stops, the natural gas pressure regulating path can be switched without interruption in the event of a power generation equipment failure. This ensures that the downstream gas supply is not affected by the expander's status, and balances the economic efficiency of residual pressure power generation with the process safety of continuous and stable gas supply from the gas storage facility.

[0035] Implementation examples of the present invention: Taking a gas storage facility as an example, with a daily gas extraction volume of 4 million standard cubic meters (Nm3 / h), its hourly natural gas transmission rate is approximately 166,700 Nm3 / h. The extracted natural gas, after filtration, has parameters of 8 MPa and 25°C, while the required transmission parameters are 6 MPa and 5°C. For an injection volume of 3 million standard cubic meters (Nm3 / h), its hourly natural gas transmission rate is approximately 125,000 Nm3 / h. The pipeline-sourced natural gas has parameters of 6 MPa and 35°C, while the required transmission parameters are 4 MPa and 5°C. The present invention employs a natural gas pressure differential power generation system and operating method adapted to both gas extraction and injection. This system recovers this pressure energy by installing a 1MW-class turbine expander. Specific parameters are shown in Table 1. Annual power generation revenue is approximately 2.88 million yuan.

[0036] Table 1 Turbine Generator Set Parameter Table The technical solutions provided by the embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the embodiments of the present invention. The descriptions of the embodiments above are only for helping to understand the principles of the embodiments of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the embodiments of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A natural gas differential pressure power generation system adapted for gas extraction and injection, characterized in that, This includes the original gas extraction period pressure regulating system, the original gas injection period pressure regulating system, and the natural gas expander; The original gas production period pressure regulating system includes a first inlet pipe, a first valve group, and a first outlet pipe arranged sequentially along the flow direction; A first inlet pipe regulating valve is provided on the first inlet pipe, and a first inlet branch is led out from the first inlet pipe on the side of the first inlet pipe away from the first valve group. A first outlet pipe regulating valve is provided on the first outlet pipe, and a first outlet branch is led out from the first outlet pipe on the side of the first outlet pipe away from the first valve group. The inlet end of the natural gas expander is connected to a third inlet pipe, and its outlet end is connected to a third outlet pipe. The inlet end of the third inlet pipe is connected to the first inlet branch through the first inlet branch regulating valve; The outlet end of the third outlet pipeline is connected to the first outlet branch through the first outlet branch regulating valve; The original gas injection period pressure regulating system includes a second inlet pipe, a second valve group, and a second outlet pipe arranged sequentially along the flow direction. A second inlet pipe regulating valve is installed on the second inlet pipe. A second inlet branch is led out from the second inlet pipe on the side of the second inlet pipe away from the second valve group. The other end of the second inlet branch is connected to the third inlet pipe. A second inlet branch regulating valve is installed on the second inlet branch. A second outlet pipe regulating valve is installed on the second outlet pipe. A second outlet branch is led out from the second outlet pipe on the side of the second outlet pipe regulating valve away from the second valve group. The other end of the second outlet branch is connected to the third outlet pipe. A second outlet branch regulating valve is installed on the second outlet branch.

2. The natural gas differential pressure power generation system adapted to gas extraction and injection according to claim 1, characterized in that: The first inlet pipeline regulating valve, the first outlet pipeline regulating valve, the second inlet pipeline regulating valve, the second outlet pipeline regulating valve, the first inlet branch regulating valve, the first outlet branch regulating valve, the second inlet branch regulating valve, and the second outlet branch regulating valve are all electric regulating valves or pneumatic regulating valves.

3. The natural gas differential pressure power generation system adapted for gas extraction and injection according to claim 1, characterized in that: The first valve group and the second valve group are axial flow pressure regulating valves or cage sleeve pressure regulating valves.

4. The natural gas differential pressure power generation system adapted to gas extraction and injection according to claim 1, characterized in that: The natural gas expander is a radial turbine expander or an axial flow turbine expander, and is equipped with a generator.

5. An operation method for a natural gas differential pressure power generation system adapted to gas extraction and injection, characterized in that, include: During the gas extraction period, the first inlet branch control valve and the first outlet branch control valve are opened, while the second inlet branch control valve and the second outlet branch control valve are closed. At the same time, the first inlet pipeline control valve, the first valve group, the first outlet pipeline control valve, the second inlet pipeline control valve, the second valve group, and the second outlet pipeline control valve are closed. This allows the natural gas used for expansion power generation to enter the first inlet branch pipeline through the first inlet pipeline, then enter the third inlet pipeline through the first inlet branch control valve, and then enter the natural gas expander for power generation. After that, it enters the gas extraction period branch outlet pipeline through the third outlet pipeline and the first outlet branch control valve, and finally enters the subsequent process system pipeline through the first outlet pipeline. During the gas injection period, the second inlet branch regulating valve and the second outlet branch regulating valve are opened, while the first inlet branch regulating valve and the first outlet branch regulating valve are closed. At the same time, the first inlet pipeline regulating valve, the first valve group, the first outlet pipeline regulating valve, the second inlet pipeline regulating valve, the second valve group, and the second outlet pipeline regulating valve are closed. This allows the natural gas used for expansion power generation to enter the second inlet branch pipeline through the second inlet pipeline, then enter the third inlet pipeline through the second inlet branch regulating valve, and then enter the natural gas expander for power generation. After that, it enters the second outlet branch pipeline through the third outlet pipeline and the second outlet branch regulating valve, and finally enters the subsequent process system pipeline through the second outlet pipeline.

6. The operation method of the natural gas differential pressure power generation system adapted to gas extraction and injection according to claim 5, characterized in that: When the natural gas expander malfunctions and shuts down: If the current operation is during the gas production period, the first inlet branch regulating valve and the first outlet branch regulating valve will be closed by interlock, and the first inlet pipeline regulating valve and the first outlet pipeline regulating valve will be opened. Natural gas can enter the first outlet pipeline through the first inlet pipeline after being depressurized by the first valve group, and then enter the subsequent process system pipeline. If the current operation is during the gas injection period, the second inlet branch regulating valve and the second outlet branch regulating valve will be interlocked and closed, while the second inlet pipeline regulating valve and the second outlet pipeline regulating valve will be opened. Natural gas can enter the second outlet pipeline through the second inlet pipeline after being depressurized by the second valve group, and then enter the subsequent process system pipeline.

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