Natural gas differential pressure power generation system

Abstract

The invention provides a natural gas differential pressure power generation system which comprises a pressure regulating pipeline, a gas inlet pipeline and a gas outlet pipeline. The power generation pipeline comprises a first heat exchanger, a turbo expander and a second heat exchanger which are sequentially connected, the first heat exchanger communicates with the air inlet pipeline, and the second heat exchanger communicates with the air outlet pipeline; the first heat exchange pipeline is connected with a first liquid inlet end of the first heat exchanger and a second liquid outlet end of the second heat exchanger, a liquid storage tank and a heater are arranged on the first heat exchange pipeline, the heater is communicated with the turbo expander, a heat exchange working medium in the liquid storage tank flows into the first heat exchanger after being heated by the heater, and natural gas flowing into the turbo expander is heated; the second heat exchange pipeline is connected with the first liquid outlet end of the first heat exchanger and the second liquid inlet end of the second heat exchanger, a third heat exchanger is arranged on the second heat exchange pipeline, and the heat exchange working medium is heated in the third heat exchanger and then flows into the second liquid inlet end to heat the natural gas flowing out of the turbo expander.

Description

Technical Field

[0001] This disclosure relates to the fields of gas transmission and power generation technology, and more specifically, to a natural gas differential pressure power generation system. Background Technology

[0002] Long-distance natural gas transportation typically uses high-pressure pipelines, with transmission pressures generally around 10 MPa. However, the pressure requirements on the user side vary, necessitating the installation of pressure regulating stations within the pipeline network. For residential gas consumption, the pressure is typically reduced from 10 MPa to 2.5-4.0 MPa at the city's pipeline network regulating stations, and then further adjusted to 0.1-0.4 MPa by the city gate stations before being delivered to end users. Currently, these regulating stations use pressure regulating valves for pressure regulation. The natural gas's pressure energy is entirely consumed in overcoming the flow resistance of these valves, resulting in significant pressure energy loss and potentially causing pipeline vibration and noise problems.

[0003] To fully utilize the pressure potential energy within natural gas pipelines, an increasing number of pressure regulating stations are adopting turbine expanders instead of pressure regulating valves for pressure regulation. This allows them to generate electricity using the pressure difference between upstream and downstream pipelines, improving overall energy efficiency. However, because the temperature of natural gas within the pipeline is close to room temperature and its composition is complex, potentially containing moisture, the temperature drops sharply after passing through the turbine expander, posing a risk of ice blockage at the turbine outlet and in the pipeline. Simultaneously, much of the leaking sealing gas from the expander shaft is introduced into the flare for combustion, resulting in significant energy waste. Summary of the Invention

[0004] In view of the above problems, this disclosure provides a natural gas differential pressure power generation system that can improve energy recovery and utilization and solve the problem of pipeline ice blockage.

[0005] According to one aspect of this disclosure, a natural gas differential pressure power generation system is provided, comprising:

[0006] A pressure regulating pipeline, wherein one end of the pressure regulating pipeline is an air inlet pipe and the other end is an air outlet pipe;

[0007] The power generation pipeline includes a first heat exchanger, a turbo expander, and a second heat exchanger connected in sequence, wherein the first air inlet of the first heat exchanger is connected to the air inlet pipe, and the second air outlet of the second heat exchanger is connected to the air outlet pipe.

[0008] The first heat exchange pipeline connects the first liquid inlet of the first heat exchanger and the second liquid outlet of the second heat exchanger. A storage tank and a heater are provided on the first heat exchange pipeline. The fourth gas inlet of the heater is connected to the turbine expander. The heat exchange working fluid in the storage tank flows into the first heat exchanger after being heated by the heater. The natural gas flowing into the turbine expander is heated in the first heat exchanger.

[0009] The second heat exchange pipeline connects the first liquid outlet of the first heat exchanger and the second liquid inlet of the second heat exchanger. A third heat exchanger is provided on the second heat exchange pipeline. The heat exchange working fluid flows out from the first liquid outlet to the third heat exchanger, is heated in the third heat exchanger, and then flows into the second liquid inlet. The natural gas flowing out of the turbine expander is heated in the second heat exchanger.

[0010] According to an embodiment of this disclosure, the third inlet of the third heat exchanger is connected to the fourth outlet of the heater, and the waste heat generated by the heater flows into the third heat exchanger through the fourth outlet and the third inlet to heat the heat exchange medium in the third heat exchanger.

[0011] According to an embodiment of this disclosure, it further includes a gas supply branch, one end of which is connected to the air inlet pipe and the other end of which is connected to the fifth air inlet of the heater.

[0012] According to an embodiment of this disclosure, a first temperature monitor is provided on the power generation pipeline, and the first temperature monitor is located between the first outlet end of the first heat exchanger and the turbine expander.

[0013] According to an embodiment of this disclosure, a second temperature monitor is provided on the power generation pipeline, and the second temperature monitor is located between the second gas outlet and the gas outlet pipeline.

[0014] According to an embodiment of this disclosure, a circulation pump is provided on the first heat exchange pipeline. The circulation pump is located between the liquid storage tank and the heater and is used to pump the heat exchange working fluid into the heater.

[0015] According to embodiments of this disclosure, the pressure regulating pipeline is further provided with a first regulating valve, a first pressure reducing valve, and a first check valve.

[0016] According to an embodiment of this disclosure, the power generation pipeline is further provided with a shut-off valve, a second regulating valve, and a second check valve, wherein the shut-off valve and the second regulating valve are located between the air inlet pipe and the first air inlet end, and the second check valve is located between the second temperature monitor and the air outlet pipe.

[0017] According to an embodiment of this disclosure, a generator is also provided on the power generation pipeline, and the generator is connected to the turbine expander.

[0018] According to an embodiment of this disclosure, a third regulating valve and a second pressure reducing valve are also provided on the gas supply branch.

[0019] The above one or more embodiments have the following beneficial effects:

[0020] 1) The turbine expander is connected to the heater. The sealed natural gas leaking from the shaft end of the turbine expander can flow into the heater as fuel, thereby preventing energy waste caused by direct discharge of the sealed gas, realizing the effective recovery and utilization of this gas energy, and improving the overall system energy utilization efficiency.

[0021] 2) In the first heat exchanger, natural gas undergoes its first heat exchange with the heat exchange medium to increase the temperature of the natural gas flowing into the turbine expander, thereby increasing the natural gas's ability to expand and do work, and increasing the output power;

[0022] 3) In the second heat exchanger, natural gas undergoes a third heat exchange with the heat exchange medium to increase the temperature of the natural gas flowing out of the turbine expander, prevent natural gas from condensing in the pipeline, ensure smooth gas outlet pipeline and stable operation of downstream system, and improve the overall equipment's operational reliability and safety.

[0023] 4) The third heat exchanger is connected to the heater. In the third heat exchanger, the waste heat generated by the heater undergoes a second heat exchange with the heat exchange medium, allowing the heat exchange medium to absorb the waste heat and increase its temperature. This fully recovers and utilizes the waste heat of the heater, avoids energy waste, realizes the cascade utilization of system energy, further improves the overall energy utilization efficiency, and reduces energy consumption costs. Attached Figure Description

[0024] The foregoing contents, as well as other objects, features, and advantages of this disclosure, will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:

[0025] Figure 1 A schematic diagram of a natural gas differential pressure power generation system according to an embodiment of this application is shown.

[0026] It should be noted that, for clarity, the dimensions of the overall / partial structure or the overall / partial region in the drawings used to describe the embodiments of this disclosure may be enlarged or reduced, i.e., these drawings are not drawn to actual scale.

[0027] Component designation explanation

[0028] 1 intake pipe 2 air outlet pipe 3 Turbine expander 101 First regulating valve 102 Second regulating valve 103 Third regulating valve 201 First pressure reducing valve 202 Second pressure reducing valve 301 first check valve 302 Second check valve 41 First heat exchanger 411 First air intake end 412 First air outlet end 413 First liquid inlet end 414 First liquid outlet end 42 Second heat exchanger 421 Second air intake 422 Second air outlet 423 Second liquid inlet end 424 Second liquid outlet end 43 Third heat exchanger 431 Third air intake 432 Third liquid inlet end 433 Third liquid outlet end 5 gate valve 6 dynamo 7 Storage tank 8 heater 81 Fourth air intake 82 Fifth air intake end 83 Fourth air outlet 9 Circulating pump 11 First temperature monitor 12 Second temperature monitor Detailed Implementation

[0029] The embodiments of this application will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of this application. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of this application for ease of explanation. However, it will be apparent that one or more embodiments may be implemented without these specific details. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of this application.

[0030] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0031] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0032] When using expressions such as "at least one of A, B and C", they should generally be interpreted in accordance with the meaning that is commonly understood by those skilled in the art (e.g., "a system having at least one of A, B and C" should include, but is not limited to, a system having A alone, a system having B alone, a system having C alone, a system having A and B, a system having A and C, a system having B and C, and / or a system having A, B and C, etc.).

[0033] In related technologies, to fully recover the pressure potential energy within natural gas pipelines, an increasing number of pressure regulating stations are adopting turbine expanders instead of pressure regulating valves for pressure regulation. However, turbine expanders present two problems in practical applications: Firstly, because the natural gas in pipelines is typically near room temperature and has a complex composition, potentially containing moisture, its temperature drops sharply after it passes through the turbine expander. This makes the turbine outlet and subsequent connecting pipelines highly susceptible to ice blockage due to moisture condensation, affecting the normal transport of natural gas and potentially causing equipment damage. Secondly, the turbine expander shaft end is usually equipped with sealing gas to prevent natural gas leakage. Currently, most of this sealing gas is directly introduced into the flare for combustion, failing to be effectively utilized and resulting in significant energy waste.

[0034] An embodiment of this application provides a natural gas differential pressure power generation system, including: a pressure regulating pipeline, one end of which is an inlet pipe and the other end is an outlet pipe; a power generation pipeline, including a first heat exchanger, a turbine expander, and a second heat exchanger connected in sequence, wherein the first inlet end of the first heat exchanger is connected to the inlet pipe, and the second outlet end of the second heat exchanger is connected to the outlet pipe; a first heat exchange pipeline, connecting the first liquid inlet end of the first heat exchanger and the second liquid outlet end of the second heat exchanger, wherein a liquid storage tank and a heater are provided on the first heat exchange pipeline for heating. The fourth air inlet of the device is connected to the turbine expander. The heat exchange medium in the storage tank is heated by the heater and flows into the first heat exchanger, where it heats the natural gas flowing into the turbine expander. The second heat exchange pipeline connects the first liquid outlet of the first heat exchanger and the second liquid inlet of the second heat exchanger. A third heat exchanger is installed on the second heat exchange pipeline. The heat exchange medium flows out from the first liquid outlet to the third heat exchanger, is heated in the third heat exchanger, and then flows into the second liquid inlet, where it heats the natural gas flowing out of the turbine expander.

[0035] According to an embodiment of this application, the turbine expander is connected to a heater. The sealed natural gas leaking from the shaft end of the turbine expander can flow into the heater as fuel, thereby preventing energy waste caused by direct discharge of the sealed gas and realizing the effective recovery and utilization of this gas energy, thus improving the overall system's energy efficiency. In the first heat exchanger, the natural gas undergoes a first heat exchange with the heat exchange medium to increase the temperature of the natural gas flowing into the turbine expander, thereby increasing the natural gas's ability to expand and do work, and increasing the output power. In the second heat exchanger, the natural gas undergoes a third heat exchange with the heat exchange medium to increase the temperature of the natural gas flowing out of the turbine expander, preventing the natural gas from condensing in the pipeline, ensuring smooth gas outlet pipeline and stable operation of the downstream system, and improving the overall equipment's operational reliability and safety.

[0036] Figure 1 A schematic diagram of a natural gas differential pressure power generation system according to an embodiment of this application is shown.

[0037] like Figure 1 As shown, the natural gas differential pressure power generation system includes a pressure regulating pipeline, a power generation pipeline, a first heat exchange pipeline, and a second heat exchange pipeline.

[0038] According to an embodiment of this application, one end of the pressure regulating pipeline is an inlet pipeline 1, and the other end is an outlet pipeline 2. The inlet pipeline 1 is a high-pressure natural gas pipeline, and the outlet pipeline 2 is a low-pressure natural gas pipeline. The pressure regulating pipeline is also equipped with a first regulating valve 101, a first pressure reducing valve 201, and a first check valve 301. The first regulating valve 101 is used to regulate the natural gas flow rate in the pipeline, the first pressure reducing valve 201 is used to reduce the pressure of the high-pressure natural gas to a set low pressure to stabilize the outlet pressure, and the first check valve 301 is used to prevent the natural gas from flowing backwards.

[0039] According to an embodiment of this application, the power generation pipeline includes a first heat exchanger 41, a turbine expander 3, and a second heat exchanger 42 connected in sequence. The first heat exchanger 41 has a first inlet end 411 and a first outlet end 412, as well as a first liquid inlet end 413 and a first liquid outlet end 414, wherein the first inlet end 411 and the first outlet end 412 are used for natural gas to enter and exit, and the first liquid inlet end 413 and the first liquid outlet end 414 are used for heat exchange working fluid to enter and exit. The second heat exchanger 42 has a second inlet end 421 and a second outlet end 422, as well as a second liquid inlet end 423 and a second liquid outlet end 424, wherein the second inlet end 421 and the second outlet end 422 are used for natural gas to enter and exit, and the second liquid inlet end 423 and the second liquid outlet end 424 are used for heat exchange working fluid to enter and exit. The first inlet end 411 is connected to an inlet pipe 1, and the second outlet end 422 is connected to an outlet pipe 2.

[0040] According to an embodiment of this application, the power generation pipeline is further equipped with a shut-off valve 5, a second regulating valve 102, a generator 6, and a second check valve 302. The shut-off valve 5 and the second regulating valve 102 are located between the gas inlet pipe 1 and the first gas inlet end 411. The shut-off valve 5 is used to control the opening / closing of the pipeline, and the second regulating valve 102 is used to regulate the natural gas flow rate in the pipeline. The generator 6 is connected to the turbine expander 3. During the natural gas decompression process, the turbine expander 3 drives the impeller to rotate through the pressure difference to generate mechanical energy. The generator 6 converts this mechanical energy into electrical energy to realize the recovery and utilization of the pressure potential energy of the natural gas pipeline. The second check valve 302 is located between the second temperature monitor 12 and the gas outlet pipe 2 to prevent the natural gas from flowing backward.

[0041] According to an embodiment of this application, a first temperature monitor 11 and a second temperature monitor 12 are also provided on the power generation pipeline. The first temperature monitor 11 is located between the first outlet end 412 of the first heat exchanger and the turbine expander 3, and is used to monitor the temperature of the natural gas flowing into the turbine expander 3. The second temperature monitor 12 is located between the second outlet end 422 and the outlet pipe 2, and is used to monitor the temperature of the natural gas flowing out of the turbine expander 3.

[0042] According to an embodiment of this application, a first heat exchange pipeline connects a first inlet end 413 and a second outlet end 424. The first heat exchange pipeline is equipped with a storage tank 7, a heater 8, and a circulating pump 9. The storage tank 7 stores the heat exchange medium, which can be water, heat transfer oil, or other available liquid media. The circulating pump 9 is located between the storage tank 7 and the heater 8 and is used to pump the heat exchange medium into the heater 8.

[0043] According to an embodiment of this application, the heater 8 has a fourth inlet end 81, a fifth inlet end 82, and a fourth outlet end 83. The fourth inlet end 81 is connected to the turbine expander 3, and the sealing gas leaking from the shaft end of the turbine expander 3 enters the heater 8 through the fourth inlet end 81. The fifth inlet end 82 is connected to the inlet pipe 1, and natural gas enters the heater 8 through the fifth inlet end 82. The fourth outlet end 83 is connected to the third heat exchanger 43, and the waste heat generated in the heater 8 flows into the third heat exchanger 43 through the third inlet end 431.

[0044] According to an embodiment of this application, a second heat exchange pipeline connects a first liquid outlet 414 and a second liquid inlet 423, and a third heat exchanger 43 is provided on the second heat exchange pipeline. The third heat exchanger 43 has a third air inlet 431, a third liquid inlet 432, and a third liquid outlet 433, wherein the third air inlet 431 is connected to the fourth air outlet 83 of the heater, the third liquid inlet 432 is connected to the first liquid outlet 414 of the first heat exchanger, and the third liquid outlet 433 is connected to the second liquid inlet 423 of the second heat exchanger.

[0045] According to an embodiment of this application, the natural gas differential pressure power generation system further includes a gas supply branch, one end of which is connected to the gas inlet pipe 1, and the other end is connected to the fifth gas inlet end 82 of the heater. A third regulating valve 103 and a second pressure reducing valve 202 are installed on the gas supply branch. The third regulating valve 103 is used to regulate the natural gas flow rate in the pipeline, and the second pressure reducing valve 202 is used to reduce the pressure of the high-pressure natural gas to a set low pressure to stabilize the outlet pressure. When the fuel in the heater 8 is insufficient, natural gas is supplied to the heater 8 through the gas supply branch to solve the problem that the combustion of the sealed natural gas leaking from the turbine expander shaft end cannot meet the total heat exchange demand of the system during the initial startup or under special circumstances.

[0046] The working principle of the natural gas differential pressure power generation system provided in this application embodiment is as follows:

[0047] First, the circulating pump 9 is turned on to open the first heat exchange pipeline, and the heat exchange medium in the storage tank 7 flows into the heater 8. Next, the third regulating valve 103 is gradually opened to open the gas supply branch, and the natural gas in the inlet pipe 1 flows into the heater 8 through the fifth inlet end 82. In the heater 8, the natural gas is burned to heat the heat exchange medium, generating high-temperature flue gas, i.e., waste heat, which flows into the third heat exchanger 43 sequentially through the fourth outlet end 83 and the third inlet end 431. The heated heat exchange medium flows into the first heat exchanger 41 through the first liquid inlet end 413. Furthermore, the sealing gas leaking from the shaft end of the turbine expander 3 flows into the heater 8 through the fourth inlet end 81 and can also be burned in the heater 8, thus preventing energy waste caused by direct discharge of the sealing gas and achieving effective recovery and utilization of this gas energy, improving the overall system's energy efficiency.

[0048] Next, the power generation pipeline is opened by opening the shut-off valve 5, and the first regulating valve 101 is gradually closed to shut off the pressure regulating pipeline. At the same time, the second regulating valve 102 is gradually opened, allowing the natural gas in the intake pipeline 1 to flow into the first heat exchanger 41 through the first intake end 411. In the first heat exchanger 41, the heat exchange medium and the natural gas undergo the first heat exchange, that is, the heat exchange medium heats the natural gas that is about to flow into the turbine expander 3. At the same time, the first temperature monitor 11 monitors the temperature of the natural gas flowing into the turbine expander 3 in real time.

[0049] According to an embodiment of this application, the heated natural gas flows out of the first heat exchanger 41 through the first outlet 412 and into the turbine expander 3. During the natural gas decompression process, the turbine expander 3 drives the impeller to rotate through the pressure difference to generate mechanical energy. The generator 6 converts this mechanical energy into electrical energy to realize the recovery and utilization of the pressure potential energy of the natural gas pipeline.

[0050] According to an embodiment of this application, the cooled heat exchange medium flows out of the first heat exchanger 41 through the first liquid outlet 414 and flows into the third heat exchanger 43 through the third liquid inlet 432.

[0051] Next, in the third heat exchanger, the waste heat undergoes a second heat exchange with the heat exchange medium, that is, the waste heat raises the temperature of the heat exchange medium. The heated heat exchange medium flows out of the third heat exchanger 43 through the third liquid outlet 433 and flows into the second heat exchanger 42 through the second liquid inlet 423. By allowing the heat exchange medium to absorb waste heat and raise its temperature, the waste heat of the heater is fully recovered and utilized, energy waste is avoided, energy is utilized in a cascade manner, the overall energy efficiency is further improved, and energy costs are reduced.

[0052] Next, the natural gas flowing out of the turbine expander 3 flows into the second heat exchanger 42, where it undergoes a third heat exchange with the heat exchange medium, that is, the natural gas is heated. At the same time, the second temperature monitor 12 monitors the temperature of the natural gas flowing out of the turbine expander 3 in real time.

[0053] Finally, once the temperature of the natural gas meets the preset value, it flows into the outlet pipeline 2. This ensures that the temperature of the natural gas entering the outlet pipeline 2 is within a safe range, preventing condensation inside the pipeline due to excessively low temperatures. This effectively prevents ice blockage or liquid accumulation that could clog the pipeline, ensuring smooth flow of the outlet pipeline and stable operation of the downstream system, thus improving the overall reliability and safety of the equipment. In this embodiment, the preset value is higher than the dew point temperature, and the difference between the two is at least 5°C. The dew point temperature refers to the temperature at which water or hydrocarbons in natural gas begin to condense into liquid under a certain pressure.

[0054] According to an embodiment of this application, in the above process, the temperature of the natural gas flowing into and out of the turbine expander 3 is monitored by a first temperature monitor 11 and a second temperature monitor 12, and the flow rate of the heat exchange medium and natural gas in the system is dynamically adjusted so that the temperature of the natural gas finally flowing out of the turbine expander meets the requirements.

[0055] According to an embodiment of this application, when the heat generated by the combustion of the sealing gas leaking from the shaft end of the turbine expander can meet the heat exchange requirements of the system, the gas supply branch can be gradually shut off.

[0056] According to an embodiment of this application, the steps for shutting down the natural gas differential pressure power generation system are as follows: The second regulating valve 102 is gradually closed to shut down the power generation pipeline. Simultaneously, the first regulating valve 101 is opened to gradually reduce the flow rate of natural gas entering the turbine expander 3 and increase the flow rate of natural gas in the pressure regulating pipeline to maintain stable downstream gas supply. Next, based on the first temperature monitor 11 and the second temperature monitor 12, the flow rate of the heat exchange medium in the first and second heat exchange pipelines is dynamically adjusted. Based on the change in the flow rate of the sealing gas leaking from the shaft end of the turbine expander 3, the third regulating valve 103 is gradually opened in a timely manner to open the gas supply branch, ensuring sufficient natural gas in the heater 8 for combustion to heat the heat exchange medium. Through multiple heat exchanges, the temperature of the natural gas flowing out of the turbine expander meets a preset value. After the second regulating valve 102 is completely closed, the heater 8 and the circulating pump 9 are shut down sequentially.

[0057] According to an embodiment of this application, the steps for emergency shutdown of the natural gas differential pressure power generation system are as follows: the power generation pipeline is quickly shut off by closing the shut-off valve 5, and the first regulating valve 101 is quickly opened to open the pressure regulating pipeline, thereby ensuring the safety and stability of the system.

[0058] The embodiments of this disclosure have been described above. However, these embodiments are for illustrative purposes only and are not intended to limit the scope of this disclosure. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. The scope of this disclosure is defined by the appended claims and their equivalents. Various substitutions and modifications can be made by those skilled in the art without departing from the scope of this disclosure, and all such substitutions and modifications should fall within the scope of this disclosure.

Claims

1. A natural gas differential pressure power generation system, characterized in that, include: A pressure regulating pipeline, wherein one end of the pressure regulating pipeline is an air inlet pipe and the other end is an air outlet pipe; The power generation pipeline includes a first heat exchanger, a turbo expander, and a second heat exchanger connected in sequence, wherein the first air inlet of the first heat exchanger is connected to the air inlet pipe, and the second air outlet of the second heat exchanger is connected to the air outlet pipe. The first heat exchange pipeline connects the first liquid inlet of the first heat exchanger and the second liquid outlet of the second heat exchanger. A storage tank and a heater are provided on the first heat exchange pipeline. The fourth gas inlet of the heater is connected to the turbine expander. The heat exchange working fluid in the storage tank flows into the first heat exchanger after being heated by the heater. The natural gas flowing into the turbine expander is heated in the first heat exchanger. The second heat exchange pipeline connects the first liquid outlet of the first heat exchanger and the second liquid inlet of the second heat exchanger. A third heat exchanger is provided on the second heat exchange pipeline. The heat exchange working fluid flows out from the first liquid outlet to the third heat exchanger, is heated in the third heat exchanger, and then flows into the second liquid inlet. The natural gas flowing out of the turbine expander is heated in the second heat exchanger.

2. The natural gas differential pressure power generation system according to claim 1, characterized in that, The third inlet of the third heat exchanger is connected to the fourth outlet of the heater. The waste heat generated by the heater flows into the third heat exchanger through the fourth outlet and the third inlet to raise the temperature of the heat exchange medium in the third heat exchanger.

3. The natural gas differential pressure power generation system according to claim 1, characterized in that, It also includes a gas supply branch, one end of which is connected to the air inlet pipe and the other end of which is connected to the fifth air inlet of the heater.

4. The natural gas differential pressure power generation system according to claim 1, characterized in that, A first temperature monitor is installed on the power generation pipeline, and the first temperature monitor is located between the first outlet end of the first heat exchanger and the turbine expander.

5. The natural gas differential pressure power generation system according to claim 1, characterized in that, A second temperature monitor is installed on the power generation pipeline, and the second temperature monitor is located between the second gas outlet and the gas outlet pipeline.

6. The natural gas differential pressure power generation system according to claim 1, characterized in that, A circulation pump is installed on the first heat exchange pipeline. The circulation pump is located between the liquid storage tank and the heater and is used to pump the heat exchange working fluid into the heater.

7. The natural gas differential pressure power generation system according to claim 1, characterized in that, The pressure regulating pipeline is also equipped with a first regulating valve, a first pressure reducing valve, and a first check valve.

8. The natural gas differential pressure power generation system according to claim 5, characterized in that, The power generation pipeline is also equipped with a shut-off valve, a second regulating valve, and a second check valve. The shut-off valve and the second regulating valve are located between the air inlet pipe and the first air inlet end, and the second check valve is located between the second temperature monitor and the air outlet pipe.

9. The natural gas differential pressure power generation system according to claim 1, characterized in that, A generator is also installed on the power generation pipeline, and the generator is connected to the turbine expander.

10. The natural gas differential pressure power generation system according to claim 3, characterized in that, The gas supply branch is also equipped with a third regulating valve and a second pressure reducing valve.

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