Natural gas multi-energy coupling differential pressure power generation dehydration system

Abstract

The utility model relates to a natural gas multi-energy coupling differential pressure power generation dehydration system which comprises a hydrate inhibitor filling pump, a natural gas inlet and outlet heat exchanger, a natural gas refrigerator, an expansion machine, a power generator, a separator and a natural gas heater. The natural gas inlet and outlet heat exchanger is provided with a hot medium inlet, a hot medium outlet, a cold medium inlet and a cold medium outlet which are opposite, the hot medium inlet is used for communicating with a natural gas upstream pipeline, and the hydrate inhibitor filling pump communicates with the natural gas upstream pipeline before entering the hot medium inlet; the power generator is used for generating power under driving of the expansion machine. According to the natural gas multi-energy coupling differential pressure power generation dehydration system, the generator can be driven to generate power by using the differential pressure of natural gas, and before high-pressure wet natural gas is communicated and enters the expansion machine, the high-pressure natural gas inlet and outlet heat exchanger and the natural gas refrigerator are connected to prevent the high-pressure natural gas entering the expansion machine from being too high in temperature.

Description

Technical Field

[0001] The present application relates to natural gas exploitation thermal energy utilization technology, and in particular to a natural gas multi-energy coupling pressure difference power generation and dehydration system. Background Art

[0002] During natural gas extraction, gathering, and transportation, a series of pressure regulation processes are required to meet the pressure requirements of equipment and pipelines. Typically, throttling devices are used to reduce the high-pressure natural gas to a lower pressure. During this process, the pressure potential energy of the high-pressure natural gas is wasted and unused. Furthermore, during the pressure reduction process, the natural gas temperature drops. When the temperature drops to the hydrate formation temperature, hydrate blockage can occur, compromising safe and stable production. To prevent this, heating is required during the throttling and pressure reduction process, consuming additional energy.

[0003] Natural gas, when transported to downstream pipelines and users, requires dehydration to meet quality standards. Currently, the most widely used and mature process in the natural gas industry is triethylene glycol (TEG) dehydration. This process involves dehydration absorption, regeneration, and tail gas treatment, requiring extensive equipment. During the regeneration process, the reboiler burns natural gas for heating and regeneration. This entire process requires significant investment, high operating energy consumption, and a large footprint.

[0004] Patent document CN105201558A discloses a natural gas pipeline excess pressure power generation system based on a single-screw expander. This system is connected to the existing natural gas pipeline and replaces the existing pressure reducing valve assembly. High-pressure natural gas expands and generates work in the single-screw expander, which then drives a generator through a dynamic reducer to generate electricity. The expanded low-pressure natural gas then enters an oil-gas separator to separate the natural gas and lubricating oil. The separated natural gas then flows through an air heater and enters the existing natural gas pipeline for delivery to downstream users. The lubricating oil, after separation, is pressurized by a lubricating oil pump and then pumped back into the single-screw expander at the required lubrication point. This system utilizes the pressure energy of the natural gas pipeline to generate electricity, while the air heater simultaneously heats the low-temperature natural gas to the temperature required by downstream users. However, this power generation system suffers from the following issues: the natural gas temperature drops below the hydrate formation temperature during the decompression process in the expander, forming hydrates, which can easily cause equipment blockage. Furthermore, for some high-pressure wet natural gas, if it enters the expander directly at an excessively high temperature, it can cause excessive internal temperature in the expander, impacting its performance and lifespan. Utility Model Content

[0005] Based on this, it is necessary to provide a natural gas multi-energy coupled pressure difference power generation and dehydration system that can utilize natural gas pressure difference to generate electricity, solve the problem of equipment blockage caused by natural gas pressure reduction, and avoid excessive temperature inside the expander.

[0006] The present application provides a natural gas multi-energy coupled pressure differential power generation and dehydration system, comprising a hydrate inhibitor filling pump, a natural gas inlet and outlet heat exchanger, a natural gas refrigerator, an expander, a generator, a separator, and a natural gas heater, wherein the natural gas inlet and outlet heat exchanger has relative hot medium inlet, hot medium outlet, cold medium inlet, and cold medium outlet, the hot medium inlet is used to connect to the natural gas upstream pipeline, the hydrate inhibitor filling pump is connected to the natural gas upstream pipeline before entering the hot medium inlet; the hot medium outlet, the natural gas refrigerator, the expander, the separator, the cold medium inlet, the cold medium outlet, and the input port of the natural gas heater are connected in sequence, the generator is connected to the expander, the generator is used to generate electricity under the drive of the expander, and the output port of the natural gas heater is used to connect to the natural gas downstream pipeline. For example, the natural gas multi-energy coupled pressure differential power generation and dehydration system is a natural gas pressure differential power generation and dehydration system.

[0007] In one embodiment, the natural gas multi-energy coupled pressure difference power generation and dehydration system further includes a first shut-off valve and a first pressure regulating valve, wherein the first shut-off valve and the first pressure regulating valve are connected in parallel between the natural gas refrigerator and the separator, and the natural gas refrigerator, the first shut-off valve, the first pressure regulating valve and the separator are connected in sequence.

[0008] In one embodiment, the natural gas multi-energy coupled pressure difference power generation and dehydration system further includes a second shutoff valve and a second pressure regulating valve, and the natural gas refrigerator is connected to the inlet of the expander through the second shutoff valve and the second pressure regulating valve in sequence.

[0009] In one embodiment, the natural gas multi-energy coupled pressure difference power generation and dehydration system further includes a third pressure regulating valve connected between the outlet of the expander and the separator.

[0010] In one embodiment, the natural gas multi-energy coupled pressure difference power generation and dehydration system further includes a controller, which is electrically connected to the expander, the generator, and the natural gas heater respectively.

[0011] In one embodiment, the controller is further electrically connected to the first shutoff valve, the first pressure regulating valve, the second shutoff valve, the second pressure regulating valve and the third pressure regulating valve.

[0012] In one embodiment, the controller is also electrically connected to the natural gas inlet and outlet heat exchangers, the separator, and the natural gas heater.

[0013] In one embodiment, the generator is a synchronous generator or an asynchronous generator.

[0014] In one embodiment, the expander is a turbine expander, a screw expander, a piston expander, a rotor expander, a magnetic levitation expander or a gear expander.

[0015] In one embodiment, the natural gas inlet and outlet heat exchangers are plate heat exchangers.

[0016] The above-mentioned natural gas multi-energy coupled pressure difference power generation and dehydration system includes a hydrate inhibitor filling pump, a natural gas inlet and outlet heat exchanger, a natural gas refrigerator, an expander, a generator, a separator and a natural gas heater. The generator of this application is used to generate electricity under the drive of the expander. The expander can use the pressure difference of natural gas to drive the generator to generate electricity, so that the natural gas multi-energy coupled pressure difference power generation and dehydration system can use the pressure difference of natural gas to generate electricity. Before the high-pressure wet natural gas is connected to the expander, this application connects the natural gas inlet and outlet heat exchanger and the natural gas refrigerator, so that the high-pressure wet natural gas first passes through the natural gas inlet and outlet heat exchange to reduce a part of its temperature, and then enters the natural gas refrigerator for further cooling before entering the expander. In this way, it can avoid the high-pressure natural gas temperature entering the expander being too high, which makes the internal temperature of the expander too high, affecting the performance and life of the expander.

[0017] The present application sets a hydrate inhibitor filling pump, and the hydrate inhibitor filling pump is connected to the upstream natural gas pipeline before entering the heat medium inlet. It can add hydrate inhibitors to the high-pressure wet natural gas before the natural gas inlet and outlet heat exchangers, which can prevent the natural gas from cooling and the temperature from dropping below the hydrate formation temperature during the pressure reduction process of the expander to produce hydrates and cause blockage. In addition, the present application separates the water in the natural gas through a separator, and heats the depressurized natural gas again through the natural gas inlet and outlet heat exchangers, which can effectively utilize the higher temperature in the high-pressure wet natural gas and further improve the utilization of thermal energy. It is then heated by a natural gas heater, and after meeting the needs of downstream users, it enters the original natural gas transmission pipeline system to be supplied to downstream users, thereby realizing the circulation of the entire natural gas transmission system.

[0018] In this application, the natural gas multi-energy coupled pressure difference power generation and dehydration integrated process technology can convert the pressure potential energy in the natural gas pressure reduction process into electrical energy for comprehensive utilization. At the same time, through the low-temperature condensation separation technology, the water carried in the natural gas can be fully separated, replacing the traditional triethylene glycol dehydration technology. In addition, the dehydration process requires less investment, occupies less space, and has lower operating costs than the traditional triethylene glycol dehydration process. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a structural schematic diagram of a natural gas multi-energy coupled pressure difference power generation and dehydration system according to one embodiment;

[0020] Illustration: 10-hydrate inhibitor filling pump; 20-natural gas inlet and outlet heat exchanger; 21-hot medium inlet; 22-hot medium outlet; 23-cold medium inlet, 24-cold medium outlet; 30-natural gas refrigerator; 40-expander; 50-generator; 60-separator; 70-natural gas heater; 81-first shut-off valve; 82-first pressure regulating valve; 83-second shut-off valve; 84-second pressure regulating valve; 85-third pressure regulating valve; 90-power grid cabinet. DETAILED DESCRIPTION

[0021] To facilitate understanding of this application and to make the above-mentioned objectives, features, and advantages of this application more readily apparent, the following detailed description of specific embodiments of this application is provided in conjunction with the accompanying drawings. The following description sets forth numerous specific details to facilitate a full understanding of this application, and the accompanying drawings illustrate preferred embodiments of this application. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the disclosure of this application. This application can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of this application. Therefore, this application is not limited to the specific embodiments disclosed below. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed to indicate or imply relative importance or to implicitly specify the number of technical features indicated. Therefore, features specified as "first" or "second" may explicitly or implicitly include at least one of such features. Throughout this description, "a plurality" means at least two, such as two or three, unless otherwise specifically defined. Throughout this description, "several" means at least one, such as one or two, unless otherwise specifically defined. An element is considered to be "connected" to another element, which may be directly connected to another element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only implementation method. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein are for the purpose of describing specific implementation methods only and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the relevant listed items.

[0022] This application provides a natural gas multi-energy coupled pressure difference power generation and dehydration system, please refer to Figure 1The natural gas multi-energy coupled pressure difference power generation and dehydration system includes a hydrate inhibitor charging pump 10, a natural gas inlet and outlet heat exchanger 20, a natural gas refrigerator 30, an expander 40, a generator 50, a separator 60, and a natural gas heater 70. The natural gas inlet and outlet heat exchanger 20 has a relative hot medium inlet 21, a hot medium outlet 22, a cold medium inlet 23, and a cold medium outlet 24. The hot medium inlet 21 is used to connect to the upstream natural gas pipeline, that is, the high-pressure natural gas pipeline before pressure reduction. The hydrate inhibitor charging pump 10 is connected to the upstream natural gas pipeline before entering the hot medium inlet 21. The hydrate inhibitor charging pump is used to add hydrate inhibitors to the natural gas. The hydrate inhibitors are added to the high-pressure wet natural gas before the natural gas inlet and outlet heat exchanger to prevent the temperature of the natural gas from dropping below the hydrate formation temperature during cooling and pressure reduction through the expander, thereby producing hydrates and causing blockage. The hot medium outlet 21 of the natural gas inlet and outlet heat exchanger 20, the natural gas refrigerator 30, the expander 40, the separator 60, the cold medium inlet 23, the cold medium outlet 24, and the input port of the natural gas heater 70 are connected in sequence. The generator 20 is connected to the expander 40. The generator 50 is used to generate electricity under the drive of the expander 40 and transmit electricity to the power grid cabinet 90. The output port of the natural gas heater 70 is used to be connected to the natural gas downstream pipeline. After being heated by the natural gas heater and meeting the needs of downstream users, it enters the original natural gas transmission pipeline system for supply to downstream users, thereby realizing the circulation of the entire natural gas transmission system.

[0023] In this application, high-pressure wet natural gas first passes through the natural gas inlet and outlet heat exchanger 20 for heat exchange, reducing its temperature. It then enters the natural gas cooler 30 for further cooling before entering the expander 40. The expander 40 drives the generator 50 to generate electricity, and the generated electricity is transmitted to the power equipment or the power grid via the power grid cabinet 90. After the high-pressure natural gas passes through the expander 40, its pressure and temperature are reduced. After the temperature is reduced, the water vapor in the natural gas condenses and precipitates, forming liquid water. The water is separated and discharged through the separator 60. The dehydrated natural gas then passes through the natural gas inlet and outlet heat exchanger 20 and the natural gas heater 70, raising the natural gas temperature to the target temperature before being transported downstream. To prevent the natural gas from cooling and reducing its pressure through the expander and causing hydrate formation and blockage, a hydrate inhibitor is injected into the high-pressure wet natural gas via a hydrate inhibitor injection pump 10 before the natural gas inlet and outlet heat exchanger.

[0024] The above-mentioned natural gas multi-energy coupled pressure difference power generation and dehydration system includes a hydrate inhibitor filling pump, a natural gas inlet and outlet heat exchanger, a natural gas refrigerator, an expander, a generator, a separator and a natural gas heater. The generator of this application is used to generate electricity under the drive of the expander. The expander can use the pressure difference of natural gas to drive the generator to generate electricity, so that the natural gas multi-energy coupled pressure difference power generation and dehydration system can use the pressure difference of natural gas to generate electricity. Before the high-pressure wet natural gas is connected to the expander, this application connects the natural gas inlet and outlet heat exchanger and the natural gas refrigerator, so that the high-pressure wet natural gas first passes through the natural gas inlet and outlet heat exchange to reduce a part of its temperature, and then enters the natural gas refrigerator for further cooling before entering the expander. In this way, it can avoid the high-pressure natural gas temperature entering the expander being too high, which makes the internal temperature of the expander too high, affecting the performance and life of the expander.

[0025] The present application sets a hydrate inhibitor filling pump, and the hydrate inhibitor filling pump is connected to the upstream natural gas pipeline before entering the heat medium inlet. It can add hydrate inhibitors to the high-pressure wet natural gas before the natural gas inlet and outlet heat exchangers, which can prevent the natural gas from cooling and the temperature from dropping below the hydrate formation temperature during the pressure reduction process of the expander to produce hydrates and cause blockage. In addition, the present application separates the water in the natural gas through a separator, and heats the depressurized natural gas again through the natural gas inlet and outlet heat exchangers, which can effectively utilize the higher temperature in the high-pressure wet natural gas and further improve the utilization of thermal energy. It is then heated by a natural gas heater, and after meeting the needs of downstream users, it enters the original natural gas transmission pipeline system to be supplied to downstream users, thereby realizing the circulation of the entire natural gas transmission system.

[0026] In this application, the natural gas multi-energy coupled pressure difference power generation and dehydration integrated process technology can convert the pressure potential energy in the natural gas pressure reduction process into electrical energy for comprehensive utilization. At the same time, through the low-temperature condensation separation technology, the water carried in the natural gas can be fully separated, replacing the traditional triethylene glycol dehydration technology. In addition, the dehydration process requires less investment, occupies less space, and has lower operating costs than the traditional triethylene glycol dehydration process.

[0027] In one embodiment, see Figure 1The natural gas multi-energy coupled pressure differential power generation and dehydration system further includes a first shutoff valve 81 and a first pressure regulating valve 82. The first shutoff valve 81 and the first pressure regulating valve 82 are connected in parallel between the natural gas refrigerator 30 and the separator 60, and the natural gas refrigerator 30, the first shutoff valve 81, the first pressure regulating valve 82, and the separator 60 are sequentially connected. For example, the natural gas multi-energy coupled pressure differential power generation and dehydration system further includes a second shutoff valve 83 and a second pressure regulating valve 84. The natural gas refrigerator is sequentially connected to the inlet of the expander 40 through the second shutoff valve 83 and the second pressure regulating valve 84. For example, the natural gas multi-energy coupled pressure differential power generation and dehydration system further includes a third pressure regulating valve 85, which is connected between the outlet of the expander 40 and the separator 60. In this application, by setting up the aforementioned multiple valves, the first shutoff valve 81 and the first pressure regulating valve 82 are closed; the second shutoff valve 83, the second pressure regulating valve 84, and the third pressure regulating valve 85 are opened, and the openings of the second and third pressure regulating valves 84 and 85 are adjusted according to pressure requirements. When the expander 40 malfunctions or requires shutdown for maintenance, an automatic interlocking program automatically closes the second shutoff valve 83, the second pressure regulating valve 84, and the third pressure regulating valve 85, while simultaneously opening the first shutoff valve 81 and the first pressure regulating valve 82, and adjusting the opening of the first pressure regulating valve 85 according to pressure requirements. By adjusting the operating load of the natural gas chiller, the temperature of the natural gas entering the separator is lowered to an appropriate temperature for separation, which is the water dew point. For example, a controller is provided to connect the first shutoff valve, the first pressure regulating valve, the second shutoff valve, the second pressure regulating valve, the second pressure regulating valve, and the third pressure regulating valve, respectively, so that the first shutoff valve, the first pressure regulating valve, the second shutoff valve, the second pressure regulating valve, the second pressure regulating valve, and the third pressure regulating valve are controlled by the controller. For example, the controller is electrically connected to the expander, the generator, and the natural gas heater, and the expander, the generator, and the natural gas heater are also controlled by the controller. For example, the controller is also electrically connected to the natural gas inlet and outlet heat exchangers, the separator, and the natural gas heater, and the natural gas inlet and outlet heat exchangers, the separator, and the natural gas heater are also controlled by the controller.

[0028] The generator of the present application is driven by the expander, and the generator can be a synchronous generator or an asynchronous generator.

[0029] It should be noted that how the expander of the present application utilizes the pressure difference to drive the generator to generate electricity, please refer to the existing technology, and this application will not go into details here.

[0030] The expander described herein can be a turbine expander, screw expander, piston expander, rotor expander, magnetic levitation expander, or gear expander. It should be noted that a turbine expander utilizes the adiabatic expansion of gas within the turbine expander to generate external work, consuming the gas's internal energy, thereby intensely cooling the gas itself and achieving refrigeration. It is a key component essential for generating cooling in air separation equipment, natural gas (LPG) liquefaction and separation equipment, and cryogenic pulverization equipment, and is the heart of the entire equipment, ensuring stable operation. A screw expander is a positive displacement expander that changes the volume of the working chamber through the rotation of the screw, thereby expanding the gas and generating work. Screw expanders are suitable for medium- and low-pressure applications with high flow rates and offer advantages such as smooth operation and easy maintenance. A piston expander primarily utilizes gas expansion within the cylinder chamber to generate external work, which is then transmitted to the crankshaft via a crank-connecting rod mechanism. The crankshaft is then coupled to a gearbox and generator, driving electricity generation. It is primarily suitable for small and medium-sized high- and medium-pressure cryogenic equipment with high pressure ratios and low flow rates. A rotor expander usually includes one or more rotors that rotate in a cylinder to change the volume of the working chamber, thereby achieving expansion of the gas and work. A dual-rotor expander may have two rotors that mesh with each other to further improve the expansion efficiency. Rotor expanders have the characteristics of compact structure and high efficiency. A magnetic levitation expander is an expander that uses magnetic levitation technology to support the rotor and drive it to rotate. Magnetic levitation technology reduces mechanical friction and wear, and improves the efficiency and stability of the expander. Magnetic levitation expanders usually have the advantages of high efficiency, low noise, and low maintenance costs. A gear expander can use the meshing and rotation of gears to change the volume of the working chamber, thereby achieving expansion of the gas and work. For the specific structure and principle of the expander, please refer to the prior art, and this application will not go into details here.

[0031] In one embodiment, the natural gas inlet and outlet heat exchanger is a plate heat exchanger. For example, the natural gas inlet and outlet heat exchanger may also be referred to as a high-pressure natural gas heat exchanger or a natural gas heat exchanger.

[0032] The above-mentioned natural gas multi-energy coupled pressure difference power generation and dehydration system includes a hydrate inhibitor filling pump, a natural gas inlet and outlet heat exchanger, a natural gas refrigerator, an expander, a generator, a separator and a natural gas heater. The generator of this application is used to generate electricity under the drive of the expander. The expander can use the pressure difference of natural gas to drive the generator to generate electricity, so that the natural gas multi-energy coupled pressure difference power generation and dehydration system can use the pressure difference of natural gas to generate electricity. Before the high-pressure wet natural gas is connected to the expander, this application connects the natural gas inlet and outlet heat exchanger and the natural gas refrigerator, so that the high-pressure wet natural gas first passes through the natural gas inlet and outlet heat exchange to reduce a part of its temperature, and then enters the natural gas refrigerator for further cooling before entering the expander. In this way, it can avoid the high-pressure natural gas temperature entering the expander being too high, which makes the internal temperature of the expander too high, affecting the performance and life of the expander.

[0033] The present application sets a hydrate inhibitor filling pump, and the hydrate inhibitor filling pump is connected to the upstream natural gas pipeline before entering the heat medium inlet. It can add hydrate inhibitors to the high-pressure wet natural gas before the natural gas inlet and outlet heat exchangers, which can prevent the natural gas from cooling and the temperature from dropping below the hydrate formation temperature during the pressure reduction process of the expander to produce hydrates and cause blockage. In addition, the present application separates the water in the natural gas through a separator, and heats the depressurized natural gas again through the natural gas inlet and outlet heat exchangers, which can effectively utilize the higher temperature in the high-pressure wet natural gas and further improve the utilization of thermal energy. It is then heated by a natural gas heater, and after meeting the needs of downstream users, it enters the original natural gas transmission pipeline system to be supplied to downstream users, thereby realizing the circulation of the entire natural gas transmission system.

[0034] In this application, the natural gas multi-energy coupled pressure difference power generation and dehydration integrated process technology can convert the pressure potential energy in the natural gas pressure reduction process into electrical energy for comprehensive utilization. At the same time, through the low-temperature condensation separation technology, the water carried in the natural gas can be fully separated, replacing the traditional triethylene glycol dehydration technology. In addition, the dehydration process requires less investment, occupies less space, and has lower operating costs than the traditional triethylene glycol dehydration process.

[0035] The various technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the various technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification. It should be noted that "in one embodiment", "for example", "for example", etc. in this application are intended to illustrate this application, rather than to limit this application. The above-mentioned embodiments only express several implementation methods of this application, and their descriptions are relatively specific and detailed, but they cannot be understood as limiting the scope of the patent application. It should be pointed out that for ordinary technicians in this field, without departing from the concept of this application, several variations and improvements can be made, which all fall within the scope of protection of this application. Therefore, the scope of protection of the patent application of this application shall be based on the attached claims.

Claims

1. A natural gas multi-energy coupled pressure difference power generation and dehydration system, characterized in that: The system comprises a hydrate inhibitor charging pump, a natural gas inlet and outlet heat exchanger, a natural gas refrigerator, an expander, a generator, a separator and a natural gas heater, wherein the natural gas inlet and outlet heat exchanger has relative hot medium inlet, hot medium outlet, cold medium inlet and cold medium outlet, the hot medium inlet is used to connect to the natural gas upstream pipeline, the hydrate inhibitor charging pump is connected to the natural gas upstream pipeline before entering the hot medium inlet; the hot medium outlet, the natural gas refrigerator, the expander, the separator, the cold medium inlet, the cold medium outlet and the input port of the natural gas heater are connected in sequence, the generator is connected to the expander, the generator is used to generate electricity under the drive of the expander, and the output port of the natural gas heater is used to connect to the natural gas downstream pipeline.

2. The system according to claim 1, wherein: The natural gas multi-energy coupled pressure difference power generation and dehydration system also includes a first shut-off valve and a first pressure regulating valve. The first shut-off valve and the first pressure regulating valve are connected in parallel between the natural gas refrigerator and the separator, and the natural gas refrigerator, the first shut-off valve, the first pressure regulating valve and the separator are connected in sequence.

3. The system according to claim 2, characterized in that The natural gas multi-energy coupled pressure difference power generation and dehydration system further includes a second shutoff valve and a second pressure regulating valve, and the natural gas refrigerator is connected to the inlet of the expander through the second shutoff valve and the second pressure regulating valve in sequence.

4. The system according to claim 3, characterized in that The natural gas multi-energy coupling pressure difference power generation and dehydration system further includes a third pressure regulating valve connected between the outlet of the expander and the separator.

5. The system according to claim 4, characterized in that The natural gas multi-energy coupling pressure difference power generation and dehydration system further includes a controller, which is electrically connected to the expander, the generator and the natural gas heater respectively.

6. The system according to claim 5, characterized in that The controller is also electrically connected to the first shutoff valve, the first pressure regulating valve, the second shutoff valve, the second pressure regulating valve and the third pressure regulating valve respectively.

7. The system according to claim 6, wherein: The controller is also electrically connected to the natural gas inlet and outlet heat exchangers, the separator and the natural gas heater respectively.

8. The system according to claim 1, wherein: The generator is a synchronous generator or an asynchronous generator.

9. The system according to claim 1, wherein: The expander is a turbine expander, a screw expander, a piston expander, a rotor expander, a magnetic levitation expander or a gear expander.

10. The system according to claim 9, characterized in that The natural gas inlet and outlet heat exchangers are plate-type heat exchangers.

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