Wellhead differential pressure power generation system of middle-high pressure natural gas well

Abstract

The invention discloses a wellhead differential pressure power generation system of a middle-high pressure natural gas well, and belongs to the technical field of natural gas transportation and power generation. Comprising a gas transmission system, a differential pressure power generation system, a pretreatment system and a hydrogen production system which are connected with a control system, the gas transmission system comprises a filter connected with a wellhead gas production tree, and an outlet of the filter is connected with a natural gas treatment station; a first pressure monitor, a first flow monitor, a first throttling valve, a gas production manifold reserved port, a first ball valve and a gas outlet manifold reserved port are sequentially arranged between the filter and the natural gas treatment station in the gas conveying direction; through control of the control system and cooperation of the gas transmission system and the differential pressure power generation system, the flow of natural gas entering the differential pressure power generator pry can be flexibly adjusted at a wellhead of a middle-high pressure natural gas well. When parameters such as gas production quantity, pressure and temperature of the medium-high pressure natural gas well fluctuate greatly, continuous and safe conveying of natural gas can be guaranteed.

Description

Technical Field

[0001] The invention belongs to the technical field of natural gas transportation and power generation, and relates to a wellhead pressure difference power generation system for a medium- and high-pressure natural gas well. Background Art

[0002] Natural gas is a clean, high-quality energy source and chemical raw material, but most of the gas fields that produce natural gas are located in remote areas, far away from major gas-consuming cities. Therefore, continuous, closed long-distance pipelines are often used to transport natural gas from gas fields to gas-consuming cities in my country. A gathering pipeline needs to be built from the wellhead of the natural gas well where the gas field is located to the first gas transmission station of the long-distance pipeline. However, due to the limitations of pipeline materials, construction costs and other factors, the operating pressure of most of my country's gathering pipelines is between 4 and 12 MPa. However, the wellhead pressure of medium-pressure natural gas wells in my country generally exceeds 35 MPa, and the wellhead pressure of high-pressure natural gas wells generally exceeds 70 MPa. Therefore, it is necessary to regulate the pressure between the natural gas wellhead and the gathering pipeline. In the previous pressure regulation process, a throttle valve was often used to reduce the pressure of natural gas, and the pressure potential energy between the wellhead of the medium- and high-pressure natural gas well and the gathering pipeline was wasted.

[0003] In recent years, in order to fully utilize the pressure potential energy from the natural gas wellhead to the gathering and transportation pipeline, the pressure difference power generation technology has been gradually developed and applied. The existing expansion power generation technologies mainly include the following three types: turbine expander technology, dual-rotor expander technology, and screw expander technology. Among them, because the turbine expander technology has the advantages of high power generation efficiency, high allowable pressure, and high output power, the turbine expander technology is given priority to utilize the pressure potential energy of the medium and high pressure natural gas wellhead.

[0004] In addition, due to the limitations of existing technology and equipment, domestic and foreign technicians have made many useful thoughts and attempts on how to carry out natural gas wellhead pressure differential power generation. For example, the Chinese invention patent with application number 201610130532.6 discloses a method and system for wellhead natural gas differential pressure power generation based on solar energy, which heats the natural gas before the expander to improve the efficiency of the expansion generator set, but the method and system described do not consider how to deal with impurities such as gravel and debris carried by the produced natural gas. The Chinese invention patent with application number 202110929299.9 proposes to convert the pressure potential energy of the natural gas at the wellhead into hydraulic energy by pushing the cylinder with natural gas, and the cylinder then pushes the hydraulic cylinder, so that the natural gas at the wellhead does not need to be depressurized; however, the wellhead pressure of medium and high pressure natural gas wells is higher than 35MPa, and even exceeds 70MPa, and the system does not provide a solution to the thorny problem of the sealing of the cylinder. The Chinese invention patent with application number 202211241271.7 proposes to achieve dehydration and dehydrocarbonization of produced natural gas through multi-stage separation and purification, thereby solving the ice blockage problem in the process of depressurization; the Chinese invention patent with application number 201821583923.4 proposes to adopt a multi-stage expansion power generation method to improve the utilization efficiency of pressure potential energy; however, both systems use a single gas transmission pipeline, and do not consider how to ensure the continuous and safe transportation of natural gas when the expander, separator and other equipment are overhauled or shut down. The Chinese invention patent with application number 201410311044.6 proposes to use the expansion generator set, air preheater and heat pump set together to improve the utilization rate of thermal energy and shut down the wellhead heating furnace; however, the system does not consider that the natural gas produced by most gas fields in my country contains a large amount of acidic gases such as CO2 and H2S. Directly sending the dehydrated, de-oiled and de-solidified natural gas into the expander will cause the expander unit to be severely corroded. The Chinese invention patent with application number 202122185824.9 discloses a natural gas wellhead pressure potential energy recovery system, which mainly includes a pressure control system, a flow control system, a pressure difference power generation device, a PEM water electrolysis hydrogen production device and a natural gas purification device; the power generation device of the system adopts an expander, and does not consider how to remove impurities such as gravel, water, SO2 contained in the natural gas, while the existing expander does not allow solid impurities to enter and only allows a small amount of liquid in the natural gas at most. The Chinese invention patent with application number 202210088823.9 discloses a natural gas wellhead integrated device based on pressure reduction and dehydration power generation, which integrates the three functions of gas-liquid-solid impurity separation, pressure reduction and power generation, thereby improving the energy efficiency utilization of the wellhead pressure potential energy; however, the device and system are only applicable to the situation where the operating parameters of the natural gas well such as gas production, pressure, temperature, etc. are relatively stable.

[0005] In summary, as the gas field is mined for more years, the gas production, pressure, temperature and other operating parameters of the natural gas wells will inevitably fluctuate greatly. However, the existing technologies and solutions are mostly single pressure difference power generation solutions, which do not systematically and comprehensively consider the following four issues: (1) How to reduce the pressure at the wellhead of medium and high pressure natural gas to the working pressure allowed by the gathering and transmission pipeline, and efficiently convert the excess pressure potential energy into electrical energy? (2) How to remove impurities such as gravel, CO2, H2S and water contained in the natural gas before it enters the pressure difference generator set? (3) How to ensure the continuous, closed and safe transportation of the produced natural gas while improving the operating efficiency of the pressure difference generator set? (4) The location of natural gas wells is often relatively remote. How to store and transport the electricity produced by the pressure difference generator set?

[0006] Therefore, proposing a systematic and comprehensive technical solution to solve the above four problems is a technical challenge that needs to be solved urgently in this field. Summary of the invention

[0007] The purpose of the present invention is to solve the technical problems in the prior art of how to reduce the pressure at the wellhead of medium and high pressure natural gas to the working pressure allowed by the gathering and transmission pipeline, and efficiently convert the surplus pressure potential energy into electrical energy, how to remove impurities and water such as gravel, CO2, H2S contained in the natural gas before it enters the pressure differential generator set, how to ensure the continuous, closed and safe transportation of the produced natural gas while improving the operating efficiency of the pressure differential generator set, and how to store and transport the electricity produced by the pressure differential generator set when the location of the natural gas well is often relatively remote, and to provide a wellhead pressure differential power generation system for medium and high pressure natural gas wells.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a wellhead differential pressure power generation system for a medium- and high-pressure natural gas well, comprising a gas transmission system, a differential pressure power generation system, a pretreatment system, and a hydrogen production system, all of which are connected to a control system;

[0010] The gas transmission system includes a filter connected to the wellhead gas tree, and the outlet of the filter is connected to the natural gas processing station; a first pressure monitor, a first flow monitor, a first throttle valve, a gas production manifold reserved port, a first ball valve and a gas outlet manifold reserved port are sequentially arranged between the filter and the natural gas processing station along the gas transmission direction;

[0011] The pretreatment system comprises a centrifugal separator; the inlet of the centrifugal separator is connected to the reserved port of the gas collection manifold; the liquid phase outlet of the centrifugal separator is connected to a liquid phase treatment skid; the gas phase outlet of the centrifugal separator is connected to a gas purification skid;

[0012] The pressure difference power generation system comprises a pressure difference power generation skid; the inlet of the pressure difference power generation skid is connected to the gas purification skid, and the outlet is connected to the photoelectric heating system; the outlet of the photoelectric heating system is connected to the reserved port of the gas outlet manifold; a third flow monitor and a seventh ball valve are sequentially arranged between the pressure difference power generation skid and the gas purification skid along the gas transmission direction;

[0013] The hydrogen production system comprises a water electrolysis hydrogen production device connected to the outlet of the liquid phase treatment skid, and the outlet of the water electrolysis hydrogen production device is connected to the reserved port of the gas outlet manifold.

[0014] The present invention is further improved in that:

[0015] It also includes a power regulation system; the power regulation system includes a power regulation device and a photovoltaic power generation device for solar power generation; the power regulation device is respectively connected to the pressure difference power generation skid, the photovoltaic heating system and the water electrolysis hydrogen production device.

[0016] The gas transmission system also includes a vent air recovery device connected in parallel with the natural gas processing station; the branch inlet where the vent air recovery device is located is arranged between the first ball valve and the reserved port of the gas outlet manifold; the branch is also provided with a vent air main reserved port; the outlet of the photoelectric heating system is also connected to the vent air main reserved port.

[0017] The branch line where the vent air recovery device is located is also provided with a second ball valve and a first throttling stop vent valve.

[0018] A liquid phase storage tank is also provided between the centrifugal separator and the liquid phase treatment skid; a tenth ball valve is provided between the liquid phase treatment skid and the water electrolysis hydrogen production device; a fifth ball valve is also provided between the reserved port of the gas collection manifold and the centrifugal separator; and a sixth ball valve is provided between the centrifugal separator and the gas purification skid.

[0019] A second pressure monitor and a first temperature monitor are also arranged between the first throttle valve and the reserved port of the gas production manifold; a third ball valve, a second throttle valve and a third pressure monitor are also arranged between the first ball valve and the reserved port of the gas outlet manifold; a fourth ball valve and a second flow monitor are arranged between the reserved port of the gas outlet manifold and the natural gas processing station.

[0020] A fourth pressure monitor and a second temperature monitor are arranged between the seventh ball valve and the pressure differential power generation skid; a fifth pressure monitor, a third temperature monitor and a check valve are arranged at the outlet of the photoelectric heating system; an eighth ball valve and a ninth ball valve are also arranged between the photoelectric heating system and the natural gas processing station; a second throttling cut-off vent valve is arranged between the check valve and the reserved port of the air vent main pipe.

[0021] The hydrogen production system further comprises a pressure regulating device arranged between the outlet of the water electrolysis hydrogen production device and the reserved port of the gas outlet manifold.

[0022] A sixth pressure monitor is arranged between the water electrolysis hydrogen production device and the pressure regulating device; the outlet of the pressure regulating device is connected between the eighth ball valve and the ninth ball valve; a seventh pressure monitor, a fourth temperature monitor, an eleventh ball valve and a fourth flow monitor are arranged in sequence between the pressure regulating device and the ninth ball valve along the gas flow direction.

[0023] The control system is a SCADA control system, which is used to monitor the temperature, pressure and flow of the wellhead differential pressure power generation system and adjust the fluid flow in the differential pressure power generation system through valves.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The present invention discloses a wellhead pressure differential power generation system for medium- and high-pressure natural gas wells, including a gas transmission system, a pressure differential power generation system, a pretreatment system and a hydrogen production system, all of which are connected to a control system; a pressure monitor, a flow monitor, a throttle valve and a ball valve are arranged in the gas transmission system, and through the control of the control system and the cooperation of the gas transmission system and the pressure differential power generation system, the natural gas flow entering the pressure differential generator skid at the wellhead of the medium- and high-pressure natural gas well can be flexibly adjusted. When the parameters such as the gas production volume, pressure, and temperature of the medium- and high-pressure natural gas wells fluctuate greatly, the continuous and safe transportation of natural gas can also be guaranteed. The pretreatment system realizes gas-liquid separation of the produced natural gas at the wellhead, removes acidic gases such as SO2, CO2, and H2S in the natural gas, and enhances the electrolysis degree of water, thereby meeting the use requirements of the pressure differential power generation skid and the water electrolysis hydrogen production device, reducing the corrosion of equipment and pipelines, and facilitating later maintenance. By setting a throttle valve on the production manifold to initially reduce the pressure of the produced natural gas from the medium and high pressure natural gas wells, the pressure that the equipment, pipelines and valves of the gas transmission system, pretreatment system and pressure difference power generation system need to bear is reduced, and the maximum intake pressure of the pressure difference power generation skid is met, and then the economic utilization of the wellhead pressure potential energy is realized through pressure difference power generation. Through the joint use of the pressure difference power generation system, the photovoltaic heating system and the off-grid photovoltaic power generation device, the power regulation system coordinates in the middle, and while meeting the power consumption of the wellhead equipment, valves and devices, the surplus power is used to produce hydrogen through the electrolysis water device with strong broadband tuning capability, and then the hydrogen is transported to the processing station together with the produced natural gas. In this way, the storage and transportation of the produced electricity can be realized without the need to set up additional transmission lines; and when the parameters such as the gas production volume, pressure and temperature of the medium and high pressure natural gas wells fluctuate greatly, the stable production of hydrogen can also be guaranteed. This system is particularly suitable for medium and high pressure natural gas wells in remote areas with strong sunlight in my country. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0027] Figure 1 It is a structural schematic diagram of a wellhead pressure difference power generation system for a medium- and high-pressure natural gas well in the present invention;

[0028] Figure 2 It is a schematic diagram of a gas transmission system of a wellhead pressure difference power generation system of a medium- and high-pressure natural gas well in the present invention;

[0029] Figure 3 It is a schematic diagram of a pretreatment system of a wellhead pressure difference power generation system of a medium- and high-pressure natural gas well in the present invention;

[0030] Figure 4 A schematic diagram of a pressure differential power generation system of a wellhead pressure differential power generation system of a medium- and high-pressure natural gas well in the present invention;

[0031] Figure 5 It is a structural schematic diagram of a hydrogen production system of a wellhead pressure difference power generation system of a medium- and high-pressure natural gas well in the present invention;

[0032] Figure 6 It is a structural schematic diagram of a power regulation system of a wellhead pressure difference power generation system of a medium- and high-pressure natural gas well in the present invention;

[0033] Figure 7 The diagram is a schematic diagram of the operation of a wellhead pressure difference power generation system for a medium- and high-pressure natural gas well in the present invention.

[0034] Among them: 1-wellhead gas tree; 2-filter; 3-natural gas processing station; 4-venting air recovery device; 5-centrifugal separator; 6-gas purification skid; 7-pressure difference power generation skid; 8-photovoltaic heating system; 9-power regulation device; 10-photovoltaic power generation device; 11-water electrolysis hydrogen production device; 12-pressure regulating device; 13-liquid phase storage tank; 14-liquid phase processing skid; 15-gas collection manifold reserved port; 16-gas outlet manifold reserved port; 17-venting air main reserved port; 101-gas collection manifold; 102-first branch pipe; 103-raw gas inlet pipe; 104-second branch pipe; 105-third branch pipe; 106-gas outlet manifold; 107-dry gas inlet pipe; 108-dry gas outlet branch pipe; 109-gas outlet main pipe; 110-venting air branch pipe; 111-hydrogen outlet pipe; 112-hydrogen outlet branch pipe; 201-liquid phase transmission pipeline; 202-water inlet pipeline; 301-pressure difference power generation skid cable; 302-hydrogen production device cable; 303-photovoltaic heating system cable; 304-photovoltaic volt generator cable; 401-first throttle valve; 402-first ball valve; 403-second ball valve; 404-first throttle stop vent valve; 405-third ball valve; 406-second throttle valve; 407-fourth ball valve; 408-fifth ball valve; 409-sixth ball valve; 410-seventh ball valve; 411-check valve; 412-eighth ball valve; 413-second throttle stop vent valve; 414-ninth ball valve; 415-tenth ball valve; 416-eleventh ball valve; 501-first pressure Monitor; 502-second pressure monitor; 503-third pressure monitor; 504-fourth pressure monitor; 505-fifth pressure monitor; 506-sixth pressure monitor; 507-seventh pressure monitor; 601-first flow monitor; 602-second flow monitor; 603-third flow monitor; 604-fourth flow monitor; 701-first temperature monitor; 702-second temperature monitor; 703-third temperature monitor; 704-fourth temperature monitor. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0036] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0038] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0039] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0040] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0041] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0042] See also Figure 1 The embodiment of the present invention discloses a wellhead pressure difference power generation system for a medium- and high-pressure natural gas well, including a gas transmission system, a pretreatment system, a pressure difference power generation system, a hydrogen production system, and a power regulation system. Figure 2As shown, the gas transmission system includes a filter 2 connected to the wellhead gas tree 1, which is used to remove solid impurities such as gravel entering the gas manifold from the gas tree; the outlet of the filter 2 is connected to the natural gas processing station 3 through the gas manifold 101, the first branch pipe 102, the second branch pipe 104, the third branch pipe 105, and the gas outlet manifold 106; a gas manifold reserved port 15 is provided between the gas manifold 101 and the first branch pipe 102; the gas manifold 101 is provided with a first pressure monitor 501, a first flow monitor 601, a first throttle valve 401, a second pressure monitor 502 and a first temperature monitor 701 in sequence along the natural gas input direction; the first branch pipe 102 is provided with a first ball valve 402, the first branch pipe 104 is provided with a second ball valve 405, and the first branch pipe 106 is provided with a second ball valve 406. The outlet of 102 is divided into two branches, a second branch pipe 104 and a third branch pipe 105; the second branch pipe 104 is sequentially provided with a third ball valve 405, a second throttle valve 406, a third pressure monitor 503 and a reserved port 16 for the gas outlet manifold along the natural body input direction, the reserved port 16 for the gas outlet manifold is connected to the gas outlet manifold 106, the gas outlet manifold 106 is sequentially provided with a fourth ball valve 407 and a second flow monitor 602, and the outlet of the gas outlet manifold 106 is connected to the gathering and transportation pipeline of the natural gas processing station 3; the third branch pipe 105 is sequentially provided with a second ball valve 403, a first throttle stop vent valve 404 and a reserved port 17 for the vent air main pipe along the natural body input direction, and the outlet of the third branch pipe 105 is connected to the vent air recovery device 4.

[0043] The first throttle valve 401 is used to initially reduce the pressure of natural gas produced from medium- and high-pressure natural gas wells, thereby reducing the intake pressure of the gas transmission system, pretreatment system, and pressure difference power generation system to reduce the construction cost of equipment, pipelines, and valves.

[0044] The first ball valve 402 is used to adjust the flow rate of the wet natural gas entering the first branch pipe 102. The second ball valve 403 is used to adjust the flow rate of the wet natural gas entering the third branch pipe 105. The first throttle stop vent valve 404 is used to block the third branch pipe 105;

[0045] In addition, the first throttle stop vent valve 404 is also used to reduce the pressure of the natural gas entering the vent air recovery pipeline from the third branch pipe 105 when an emergency occurs in the gas transmission system. Optionally, the second ball valve 403 and the first throttle stop vent valve 404 should be as close as possible to the connection point between the third branch pipe 105 and the first branch pipe 102, so as to reduce the construction cost of the third branch pipe 105 and the vent air recovery pipeline. The third ball valve 405 is used to adjust the flow rate of wet natural gas entering the second branch pipe 104. The second throttle valve 406 is used to reduce the pressure of the natural gas in the second branch pipe 104, so as to meet the pressure requirements of the gathering and transportation pipeline from the wellhead to the natural gas processing station 3. The fourth ball valve 407 is used to adjust the flow rate of gas entering the gas outlet manifold 106.

[0046] The first pressure monitor 501 is used to monitor the pressure before the first throttle valve 401 on the gas production manifold 101 reduces the pressure, and the second pressure monitor 502 is used to monitor the pressure after the first throttle valve 401 on the gas production manifold 101 reduces the pressure. The third pressure monitor 503 is used to monitor the pressure after the second throttle valve 406 reduces the pressure. The first temperature monitor 701 is used to monitor the natural gas temperature at the end of the gas production manifold 101.

[0047] The first flow monitor 601 is used to monitor the flow of natural gas in the production manifold 101. The second flow monitor 602 is used to monitor the flow of the gathering pipeline entering the natural gas processing station 3 from the outlet manifold 106. Optionally, the first flow monitor 601 and the second flow monitor 602 are generally volume flow meters, but in order to facilitate the measurement of the amount of hydrogen produced by the hydrogen production system, the second flow monitor 602 can be a mass flow meter, and the first flow monitor 601 can also use a mass flow meter.

[0048] The gas transmission system is used to: complete the pressure regulation of natural gas produced from medium and high pressure natural gas wells through the adjustment of the SCADA control system, to ensure that the natural gas produced from the wellhead does not exceed the maximum pressure allowed by the gathering and transmission pipeline; in addition, it is also used for natural gas venting and recovery in emergency situations, thereby ensuring the safety of personnel, equipment and pipelines.

[0049] See also Figure 3 The pretreatment system includes a centrifugal separator 5, the inlet of the centrifugal separator 5 is connected to the reserved port 15 of the gas collection manifold through the raw gas inlet pipeline 103, and a fifth ball valve 408 is arranged on the raw gas inlet pipeline 103; the liquid phase outlet of the centrifugal separator 5 is connected to the liquid phase treatment skid 14 through the liquid phase delivery pipeline 201; a liquid phase storage tank 13 is arranged on the liquid phase delivery pipeline 201; the gas phase outlet of the centrifugal separator 5 is connected to the gas purification skid 6; a tenth ball valve 415 is arranged between the liquid phase treatment skid 14 and the water electrolysis hydrogen production device 11; a fifth ball valve 408 is also arranged between the reserved port 15 of the gas collection manifold and the centrifugal separator 5; a sixth ball valve 409 is arranged between the centrifugal separator 5 and the gas purification skid 6.

[0050] The fifth ball valve 408 is used to control the flow rate of wet natural gas entering the raw gas inlet pipeline from the gas production manifold 101 .

[0051] The sixth ball valve 409 is used to control the flow rate of natural gas dry gas entering the gas purification skid 6 from the centrifugal separator 5. (Generally, produced) The centrifugal separator 5 is used to separate the natural gas wet gas into gas-liquid two-phases, thereby removing the water contained in the produced natural gas. The separated gas phase enters the dry gas inlet pipeline 107 where the gas purification skid 6 is located, and leads to the gas purification skid 6 for the next step of processing. The separated water enters the liquid phase storage tank through the liquid phase transmission pipeline 201. The gas purification skid 6 is used to remove the acidic gases such as H2S, CO2, SO2 contained in the natural gas dry gas, thereby meeting the raw gas intake requirements of the pressure difference power generation system. Since the acidic gases such as CO2 and SO2 contained in the natural gas have a certain solubility in water, the water separated by the centrifugal separator 5 contains a certain acidity. The liquid phase storage tank 13 is used to store the water separated from the centrifugal separator 5, and according to the instructions of the SCADA control system, adjust the amount of water entering the liquid phase treatment skid 14 from the liquid phase storage tank 13. The liquid phase treatment skid 14 is used to neutralize or reduce the acid contained in the water, thereby obtaining water with a pH value of weak acidity or weak alkalinity to meet the use requirements of the water electrolysis hydrogen production device 11.

[0052] The pretreatment system is used to: complete the gas-liquid two-phase separation of medium and high pressure natural gas wellhead gas, and preliminarily complete the gas purification, remove the acid gases such as H2S and CO2 contained in the raw gas, so as to meet the safe use requirements of the pressure difference power generation system; preliminarily complete the liquid treatment, remove the oil contained in the liquid, neutralize or reduce the acid contained in the liquid, so that the treated liquid water can meet the use requirements of the water electrolysis hydrogen production device.

[0053] See also Figure 4 The pressure difference power generation system includes a pressure difference power generation skid 7; the inlet of the pressure difference power generation skid 7 is connected to the gas purification skid 6 through a dry gas inlet pipeline 107, and the outlet is connected to the photoelectric heating system 8; the dry gas inlet pipeline 107 is provided with a third flow monitor 603 and a seventh ball valve 410, a fourth pressure monitor 504 and a second temperature monitor 702 in sequence along the gas transmission direction; the outlet of the photoelectric heating system 8 is connected to a dry gas outlet branch pipe 108, and the outlet of the dry gas outlet branch pipe 108 is disposed There are two branches, namely, an air outlet main pipe 109 and a vent air branch pipe 110; the dry gas air outlet branch pipe 108 is provided with a fifth pressure monitor 505, a third temperature monitor 703 and a check valve 411; the outlet of the air outlet main pipe 109 is connected to the reserved port 16 of the air outlet manifold, and the air outlet main pipe 109 is provided with an eighth ball valve 412 and a ninth ball valve 414; the outlet of the vent air branch pipe 110 is connected to the reserved port 17 of the vent air main pipe; the vent air branch pipe 110 is provided with a second throttling cut-off vent valve 413.

[0054] The third flow monitor 603 is used to monitor the flow of natural gas dry gas from the gas purification skid 6 into the pressure difference generator skid 7. The seventh ball valve 410 is used to adjust the flow of natural gas dry gas from the dry gas inlet pipeline 107 into the pressure difference generator skid 7. The eighth ball valve 412 is used to adjust the flow of natural gas dry gas from the dry gas outlet branch pipe 108 into the outlet main pipe 109. The ninth ball valve 414 is used to adjust the flow of natural gas dry gas and hydrogen from the outlet main pipe 109 into the outlet manifold. The check valve 411 is used to prevent gas from flowing back into the pressure difference generator skid 7. The second throttling stop vent valve 413 is used to block the vent air branch pipe 110; in addition, the second throttling stop vent valve 413 is also used to reduce the natural gas pressure entering the vent air branch pipe 110 from the dry gas outlet branch pipe 108 when the pressure difference power generation system encounters an emergency or needs to be shut down for maintenance. The second throttling stop vent valve 413 should be as close as possible to the connection point between the vent branch pipe 110 and the dry gas outlet branch pipe 108, so as to reduce the construction cost of the vent branch pipe. The first pressure monitor 501 and the second pressure monitor 502 are used to monitor the pressure of the natural gas dry gas before and after the pressure difference power generation skid 7. The first temperature monitor 701 is used to monitor the temperature of the natural gas dry gas entering the pressure difference generator skid 7. The second temperature monitor 702 is used to monitor the temperature of the natural gas dry gas coming out of the pressure difference power generation skid 7 and reheated by the photovoltaic heating system. The pressure difference generator skid 7 is a complete set of modularly configured pressure difference power generation skid-mounted equipment, including a turbine expander, an asynchronous generator and an auxiliary control system, as well as supporting auxiliary equipment and skid-to-skid wiring. In the pressure difference generator skid 7, the turbine expander is coaxially connected to the asynchronous generator. After the natural gas dry gas enters the turbine expander, it drives the turbine expander to operate, and transmits the pressure potential energy contained in the natural gas to the asynchronous generator, thereby converting the pressure potential energy into electrical energy.

[0055] The auxiliary control system is only used to ensure the safe operation of the pressure difference generator set. A small part of the electric energy produced by the asynchronous generator is used by the generator itself, and most of it is transmitted to the power regulation system through cables. The photovoltaic heating system 8 is composed of auxiliary facilities such as photovoltaic arrays, electric heating furnaces, heat exchangers and cables. In the photovoltaic heating system 8, the photovoltaic array converts solar energy into electrical energy, which is then supplied to the electric heating furnace. In the electric heating furnace, the dry gas outlet branch pipe reheats the low-temperature natural gas dry gas through a heat exchanger. The reheating temperature requirement is to raise the temperature of the natural gas to above the water dew point of the natural gas. Most of the electricity produced by the photovoltaic heating system 8 is used for the power heating furnace, and the surplus electricity is transmitted to the power regulation system through cables. The pressure difference power generation system is used to introduce natural gas dry gas into the pressure difference generator skid 7, convert the large amount of pressure potential energy contained in the natural gas dry gas into electrical energy, and reheat the natural gas at the outlet of the pressure difference generator skid through the photovoltaic heating system, and then the reduced-pressure and reheated natural gas dry gas is transmitted to the outlet manifold.

[0056] Generally, power conditioning systems do not have energy storage devices.

[0057] Optionally, when the power generation of the photovoltaic power generation device obviously exceeds the regulation capacity of the power regulation system, an energy storage device can be configured to enhance the regulation capacity of the power regulation system, thereby maintaining continuous and stable operation of the hydrogen production system.

[0058] See also Figure 5 The hydrogen production system includes a water electrolysis hydrogen production device 11 connected to the outlet of the liquid phase treatment skid 14 through a water inlet pipeline 202, the outlet of the water electrolysis hydrogen production device 11 is connected to a pressure regulating device 12 through a hydrogen outlet pipeline 111, the pressure regulating device 12 is connected to a hydrogen outlet branch pipe 112, and the outlet of the hydrogen outlet branch pipe 112 is arranged between the eighth ball valve 412 and the ninth ball valve 414; a tenth ball valve 415 is arranged on the water inlet pipeline 202, a sixth pressure monitor 506 is arranged on the hydrogen outlet pipeline 111, and a seventh pressure monitor 507, a fourth temperature monitor 704, an eleventh ball valve 416 and a fourth flow monitor 604 are arranged on the hydrogen outlet branch pipe 112 in sequence. The tenth ball valve 415 is used to control the flow of the water inlet pipeline 202. The eleventh ball valve 416 is used to control the hydrogen flow rate of the hydrogen outlet branch pipe 112. The water electrolysis hydrogen production device 11 is an alkaline electrolyzer or a PEM electrolyzer. The PEM electrolyzer has a stronger frequency conversion capability and better adaptability at the wellhead.

[0059] The sixth pressure monitor 506 is used to monitor the pressure of the hydrogen coming out of the water electrolysis hydrogen production device 11 , and the seventh pressure monitor 507 is used to monitor the pressure of the hydrogen after being pressurized by the pressure regulating device 12 .

[0060] The fourth temperature monitor 704 is used to monitor the temperature of hydrogen after the pressure regulating device 12. The fourth flow monitor 604 is used to monitor the flow of hydrogen entering the outlet main pipe from the hydrogen outlet branch pipe 112. The electrolytic water device 11 has the following characteristics: the energy consumption of hydrogen production is lower than the industry average index, the system efficiency is higher than 70%, it has a strong broadband tuning capability, and the device has a high degree of integration and intelligence. The electricity required by the electrolytic water device 11 comes from the power regulation system, and the required water comes from the liquid phase treatment skid 14. In the electrolytic water device, water is electrolyzed into hydrogen and oxygen. Hydrogen is generated from the cathode of the electrolytic water device and introduced into the hydrogen outlet pipeline after collection; oxygen is generated at the anode of the electrolytic water device and can be directly introduced into the atmosphere or collected according to demand. Alkali solution can be used to increase the ionization degree of water. The pressure regulating device 12 is used to pressurize the hydrogen in the hydrogen outlet pipeline so that the hydrogen can be injected into the outlet main pipe from the hydrogen outlet branch pipe 112.

[0061] The hydrogen production system is used to produce hydrogen in a water electrolysis hydrogen production device by utilizing the electricity transmitted by the power regulation system and the liquid water obtained by the pretreatment system, thereby storing the surplus electric energy of the wellhead power generation. The output is pressurized by the pressure regulating device 12 and then transmitted to the dry gas outlet branch pipe 108, and then transported to the natural gas centralized processing plant through the gathering pipeline along with the natural gas.

[0062] See also Figure 6 The power regulation system includes a power regulation device 9 and a photovoltaic power generation device 10 for solar power generation; the power regulation device 9 is connected to the pressure difference power generation pry 7 through the pressure difference power generation pry cable 301, the power regulation device 9 is connected to the photovoltaic heating system 8 through the photovoltaic heating system cable 303, and the power regulation device 9 is connected to the water electrolysis hydrogen production device 11 through the hydrogen production device cable 302. The power regulation system rectifies the surplus power produced by the pressure difference power generation pry 7, the photovoltaic heating system 8, and the photovoltaic power generation device 10 through the cable, and then adjusts it by the automatic control system with the control cabinet. After ensuring the pressure monitor, flow monitor, temperature monitor, gas purification pry, liquid phase treatment pry 14, centrifugal separator 5 and other equipment required for wellhead pressure difference power generation, the surplus power is delivered to the water electrolysis hydrogen production device 11 to produce hydrogen. Since the photovoltaic heating system 8 adopts the form of solar power generation, the power regulation system also needs to supply power to the photovoltaic heating system 8 when the photovoltaic heating system cannot meet its own power consumption. In addition, since the photovoltaic power generation device 10 also adopts the form of photovoltaic power generation, it is limited by natural conditions, and the amount of electricity produced by the photovoltaic power generation device 10 will fluctuate with the intensity of light. However, the power regulation system provided in the present invention does not provide a power storage device, so the amount of electricity and frequency supplied by the power regulation system to the water electrolysis hydrogen production device 11 will fluctuate to a certain extent. The water electrolysis hydrogen production device 11 has a strong broadband tuning capability. With the assistance of the SCADA system, the power regulation system and the water electrolysis hydrogen production device 11 should meet the supply and demand balance.

[0063] The power regulation system is used to supply the power generated by the pressure difference power generation skid 7 and the photovoltaic power generation device 10 to the electrical equipment at the natural gas wellhead after regulation.

[0064] The working process of the present invention is as follows:

[0065] When the wellhead pressure difference power generation system of the medium- and high-pressure natural gas well in the present invention operates normally, the gas transmission system, the pretreatment system, the pressure difference power generation system, the hydrogen production system and the power regulation system are all in normal working conditions.

[0066] See also Figure 7The natural gas produced from the natural gas wellhead enters the gas production manifold 101 through the gas production tree 1. At this time, the produced natural gas carries gravel, debris, H2S, CO2, SO2, etc. Since the produced gas from medium and high pressure natural gas wells generally contains water, it can be called wet natural gas.

[0067] First, the process of processing and transporting wet natural gas produced by the gas transmission system will be described in detail below:

[0068] 1. Gas tree 1 to gas manifold reserved port 15

[0069] (1) Solid impurities such as debris and gravel carried by the produced natural gas are filtered out at filter 2 of the gas production manifold.

[0070] (2) Since the natural gas well targeted by the present invention is a medium-high pressure natural gas well, the pressure monitored by the first pressure monitor 501 on the gas manifold 101 should generally be higher than 35 MPa and not exceed 140 MPa at most.

[0071] (3) The first flow monitor 601 monitors the wet gas flow rate of the natural gas on the gas production manifold 101 .

[0072] (4) Then, the SCADA system issues a command to adjust the opening of the first throttle valve 401 based on the temperature and pressure of the natural gas collected and transmitted by the first pressure monitor 501 and the first flow monitor 601, and based on the maximum intake pressure that the differential pressure generator skid 7 in the system can withstand, so as to initially reduce the pressure of the wet natural gas, so that its pressure is reduced to within the maximum intake pressure that the differential pressure generator skid can withstand, and the temperature of the wet natural gas is reduced accordingly.

[0073] (5) The second pressure monitor 502 and the first temperature monitor 701 monitor the pressure and temperature of the wet natural gas after throttling and pressure reduction, and confirm again whether the pressure and temperature of the wet natural gas meet the requirements.

[0074] (6) After throttling and depressurization, the wet natural gas reaches the reserved port 15 of the gas manifold

[0075] 2. From the reserved port 15 of the gas collection manifold to the reserved port 16 of the gas outlet manifold

[0076] (1) When reaching the reserved port 15 of the gas manifold, due to the regulation of the SCADA system, the first throttle valve 401 and the third ball valve 405 are both opened. The degree of opening of the third ball valve 405 depends on the natural gas flow rate that the rated power of the pressure difference power generation system can handle. Therefore, the wet natural gas is divided into two streams at the reserved port 15 of the gas manifold, one stream enters the raw gas inlet pipeline 103, and the other stream enters the first branch pipe 102. And the principle of gas volume distribution is to give priority to the natural gas required by the pressure difference power generation system, and the remaining gas enters the first branch pipe 102.

[0077] (2) Under normal operating conditions, the second ball valve 403 and the first throttling stop vent valve 404 on the third branch pipe 105 are both in a fully closed state, so that the third branch pipe 105 is blocked, and the natural gas entering the first branch pipe 102 all enters the second branch pipe 104.

[0078] (3) The third ball valve 405 on the second branch pipe 104 is fully open by default. The opening degree of the second throttle valve 406 on the second branch pipe 104 depends on the working pressure of the gas outlet manifold 106 of the gathering and transportation pipeline. At the second throttle valve 406 on the third branch pipe 105, the pressure of the wet natural gas is reduced to the same as the working pressure of the gathering and transportation pipeline of the natural gas processing station.

[0079] (4) The wet natural gas after the secondary decompression reaches the reserved port 16 of the gas outlet manifold and mixes with the dry natural gas and hydrogen from the gas outlet main pipe 109. The connection point opening of the reserved port 16 of the gas outlet manifold is located at the bottom of the inlet of the gas outlet manifold 106 to promote the mixing of the dry natural gas, hydrogen and wet natural gas as soon as possible.

[0080] 3. Reserved port 16 to outlet manifold 106

[0081] (1) The mixed gas enters the gas outlet manifold 106, and the fourth ball valve 407 on the gas outlet manifold 106 is generally fully opened.

[0082] (2) The second flow monitor 602 on the gas outlet manifold 106 is generally a mass flow meter. The distance between the second flow monitor 602 and the reserved port of the gas outlet manifold 106 should be greater than 45 times the inner diameter of the gas outlet manifold 106, so as to ensure that the hydrogen, dry natural gas and wet natural gas are fully mixed and evenly mixed, thereby improving the metering accuracy of hydrogen and natural gas.

[0083] (3) The wet gas measured by the second flow monitor 602 enters the gas outlet manifold 106 and is transported to the natural gas processing station 3.

[0084] 4. Natural gas venting and recovery

[0085] (1) In an emergency, the natural gas in the gas transmission system needs to be released. At this time, the third ball valve 405 is completely closed, the second ball valve 403 and the first throttling stop vent valve 404 are opened, and the opening degree of the second ball valve 403 depends on the required flow rate of the released natural gas. The opening degree of the first throttling stop vent valve 404 depends on the pressure difference between the wet natural gas after the initial throttling and the vent air recovery pipeline.

[0086] (2) The wet natural gas after the pressure reduction by the first throttling stop vent valve 404 enters the vent air recovery pipeline and leads to the vent air recovery device 4.

[0087] Secondly, the process of treating wet natural gas in the pretreatment system will be described in detail below:

[0088] (1) The wet natural gas is diverted from the reserved port 15 of the gas production manifold and enters the raw gas inlet pipeline 103. The flow rate is controlled by the fifth ball valve 408, and then the wet natural gas enters the centrifugal separator 5.

[0089] (2) The principle of the wet natural gas entering the centrifugal separator 5 is the same as the dehydration process of a washing machine. The water carried in the natural gas is removed, and the dehydrated natural gas dry gas enters the dry gas inlet pipeline 107. The removed water is collected and enters the liquid phase storage tank 13 through the liquid phase delivery pipeline 201. The centrifugal separator 5 also adopts a miniaturized and integrated skid-mounted device. The removed water enters the liquid phase storage tank 13. The amount of water entering the liquid phase treatment skid 14 from the liquid phase storage tank 13 is determined by the amount of water required by the water electrolysis hydrogen production device 11. In the liquid phase treatment skid 14, the acid contained in the water is neutralized or reduced by adding alkali liquid or absorption method. The water treated by the liquid phase treatment skid 14 enters the water electrolysis hydrogen production device 11 through the liquid phase delivery pipeline 201, and its flow rate is controlled by the tenth ball valve 415. The opening of the tenth ball valve 415 is determined by the amount of water required by the water electrolysis hydrogen production device 11.

[0090] (3) The natural gas dry gas enters the gas purification skid through the dry gas inlet pipeline 107. The gas purification skid is a miniaturized, integrated natural gas purification skid-mounted equipment that can remove the acid gas contained in the natural gas by adsorption. The third flow monitor 603 monitors the flow of the natural gas dry gas after acid removal and transmits it to the SCADA control system, thereby determining the opening of the seventh ball valve 410.

[0091] Then, the process of using pressure potential energy by the pressure difference power generation system will be described in detail below:

[0092] (1) The natural gas dry gas enters the expander air inlet of the pressure difference generator skid 7 through the dry gas inlet pipeline 107. The fourth pressure monitor 504 and the second temperature monitor 702 collect the pressure and temperature of the natural gas dry gas before entering the pressure difference generator skid 7.

[0093] (2) In the pressure difference generator skid, the natural gas drives the turbine expander to do work. After expansion and refrigeration, the pressure and temperature of the natural gas are greatly reduced. The natural gas after pressure reduction and temperature reduction enters the dry gas outlet branch pipe 108.

[0094] (3) The turbo expander converts the pressure potential energy into mechanical energy, and then transmits the mechanical energy to the asynchronous generator, which then converts the mechanical energy into electrical energy to produce electricity. Part of the produced electricity is supplied to the pressure difference generator skid 7 for its own use, and most of it is transmitted to the power regulation system after voltage regulation. The working principle of the pressure difference generator skid 7 is to keep the turbo expander and the asynchronous generator at rated power as much as possible.

[0095] (4) After the pressure reduction and temperature reduction, the natural gas dry gas enters the dry gas outlet branch pipe 108, and first exchanges heat with the photovoltaic heating system 8, thereby heating the natural gas dry gas to prevent the natural gas temperature from being lower than the water dew point of the natural gas. The photovoltaic heating system 8 is a complete set of integrated equipment, which supplies power to the electric heating furnace through photovoltaic power generation. After the electric heating furnace heats the water, the natural gas dry gas is reheated through the heat exchanger. When the photovoltaic power generation of the photovoltaic heating system 8 is not enough to meet its own electricity demand, the power regulation system supplies power to the photovoltaic heating system. The water of the photovoltaic heating system comes from the liquid phase storage tank 13.

[0096] (5) The fifth pressure monitor 505 and the third temperature monitor 703 collect the pressure and temperature of the natural gas after decompression and reheating.

[0097] (6) The second throttling stop vent valve 413 on the vent air branch pipe 110 is generally in a fully closed state, and its principle is the same as that of the first throttling stop vent valve 404. It will only be opened when the pressure difference power generation system needs to release the natural gas in the system. The vent air of the pressure difference power generation system flows through the vent air branch pipe 110 into the vent air recovery pipeline at the reserved port 17 of the vent air main pipe, and then passes through the vent air recovery device 4.

[0098] (7) Therefore, the depressurized and reheated natural gas flowing out of the dry gas outlet branch pipe 108 enters the outlet main pipe 109. The eighth ball valve 412 regulates the flow of the natural gas dry gas entering the outlet main pipe 109. The outlet main pipe 109 also receives hydrogen from the hydrogen outlet branch pipe 112. The ninth ball valve 414 controls the flow of the mixed gas (natural gas dry gas and hydrogen) flowing out of the outlet main pipe 109.

[0099] Furthermore, the process of regulating the regular electricity demand of natural gas by the power regulation system is described in detail below:

[0100] (1) The power regulation system has two sources of power: one is the stable power produced by the pressure difference power generation skid 7; the other is the fluctuating power produced by the photovoltaic power generation device 10. The output load of the power regulation system includes the hydrogen production system, the gas purification skid 6, the liquid phase treatment skid 14, the centrifugal separator 5, valves (all valves are electric valves) and other electrical equipment.

[0101] (2) After rectifying and regulating the electricity from the two sources, the power regulation system gives priority to meeting the needs of wellhead power equipment other than the hydrogen production system. Since the wellhead power equipment cannot consume the surplus electricity, the surplus electricity is supplied to the hydrogen production system, thereby converting electrical energy into hydrogen energy and realizing the storage and transportation of surplus electrical energy.

[0102] Finally, the process of producing and transporting hydrogen by the hydrogen production system is described in detail below:

[0103] (1) The water electrolysis hydrogen production device 11 uses the water treated by the liquid phase treatment skid 14 and the surplus electricity delivered by the power regulation system to electrolyze water into hydrogen and oxygen, thereby converting electrical energy into hydrogen energy. Weakly alkaline or weakly acidic water can enhance the degree of electrolysis.

[0104] (2) The hydrogen produced by the water electrolysis hydrogen production device 11 enters the hydrogen outlet pipeline 111. Since the pressure of the hydrogen produced by the water electrolysis hydrogen production device 11 is often lower than the delivery pressure of the gathering pipeline of the natural gas processing station 3, in order to inject the hydrogen into the gathering pipeline of the natural gas, it is necessary to use a pressure regulating device 12 to pressurize the hydrogen.

[0105] (3) The sixth pressure monitor 506 collects the pressure of the hydrogen before pressure regulation. The seventh pressure monitor 507 and the fourth temperature monitor 704 collect the pressure and temperature of the hydrogen after pressure regulation.

[0106] (4) The eleventh ball valve 416 controls the flow of the pressure-regulated hydrogen. The fourth flow monitor 604 monitors the flow of hydrogen in the hydrogen outlet branch pipe 111. Generally, the fourth flow monitor 604 is a mass flow meter.

[0107] (5) The hydrogen after pressure regulation and metering is introduced into the gas outlet main pipe 109 through the hydrogen outlet branch pipe 111, and after being mixed with the natural gas, enters the gas outlet manifold 106 through the reserved port 16 of the gas outlet manifold. Research by Southwest Petroleum University shows that injecting no more than 15% hydrogen into natural gas for mixing and then transporting it together will not cause harm to existing natural gas transmission pipelines, equipment and valves.

[0108] In summary, the wellhead pressure difference power generation system of a medium- and high-pressure natural gas well provided by the present invention includes a gas transmission system and a pressure difference power generation system. Through the control of the SCADA system, the cooperation of the gas transmission system and the pressure difference power generation system can ensure the continuous and safe transportation of natural gas and the efficient use of pressure potential energy when the parameters such as the gas production volume, pressure, and temperature of the medium- and high-pressure natural gas wells fluctuate greatly. By separating and treating the natural gas moisture by gas-liquid separation through the pretreatment system, the natural gas quality requirements required by the pressure difference power generation skid can be met, and the water quality requirements required by the water electrolysis hydrogen production device can be met. Through the combined use of the pressure difference power generation system, the photovoltaic heating system and the off-grid photovoltaic power generation device, the power regulation system is coordinated in the middle, and the water electrolysis hydrogen production device produces hydrogen, which can meet the electricity demand of the wellhead equipment, and the surplus electric energy can be converted into hydrogen energy, and then transported by the natural gas gathering and transmission pipeline. This system is particularly suitable for medium- and high-pressure natural gas wells in remote areas of my country with strong sunlight.

[0109] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A wellhead pressure difference power generation system for a medium- and high-pressure natural gas well, characterized in that: It includes a gas transmission system, a pressure difference power generation system, a pretreatment system and a hydrogen production system, all of which are connected to the control system; The gas transmission system comprises a filter (2) connected to a wellhead gas tree (1), wherein the outlet of the filter (2) is connected to a natural gas processing station (3); a first pressure monitor (501), a first flow monitor (601), a first throttle valve (401), a gas production manifold reserved port (15), a first ball valve (402) and a gas outlet manifold reserved port (16) are sequentially arranged between the filter (2) and the natural gas processing station (3) along the gas transmission direction; The pretreatment system comprises a centrifugal separator (5); the inlet of the centrifugal separator (5) is connected to a reserved port (15) of a gas collection manifold; the liquid phase outlet of the centrifugal separator (5) is connected to a liquid phase treatment skid (14); the gas phase outlet of the centrifugal separator (5) is connected to a gas purification skid (6); The pressure difference power generation system comprises a pressure difference power generation skid (7); the inlet of the pressure difference power generation skid (7) is connected to the gas purification skid (6), and the outlet is connected to the photoelectric heating system (8); the outlet of the photoelectric heating system (8) is connected to the reserved port (16) of the gas outlet manifold; a third flow monitor (603) and a seventh ball valve (410) are sequentially arranged between the pressure difference power generation skid (7) and the gas purification skid (6) along the gas transmission direction; The hydrogen production system comprises a water electrolysis hydrogen production device (11) connected to the outlet of the liquid phase treatment skid (14), and the outlet of the water electrolysis hydrogen production device (11) is connected to a reserved port (16) of a gas outlet manifold.

2. The wellhead pressure difference power generation system for medium and high pressure natural gas wells according to claim 1 is characterized in that: It also includes a power regulation system; the power regulation system includes a power regulation device (9) and a photovoltaic power generation device (10) for solar power generation; the power regulation device (9) is respectively connected to the pressure difference power generation skid (7), the photovoltaic heating system (8) and the water electrolysis hydrogen production device (11).

3. The wellhead pressure difference power generation system for medium and high pressure natural gas wells according to claim 2 is characterized in that: The gas transmission system also includes a vent air recovery device (4) connected in parallel with the natural gas processing station (3); the branch inlet where the vent air recovery device (4) is located is arranged between the first ball valve (402) and the reserved port (16) of the gas outlet manifold; the branch is also provided with a vent air main reserved port (17); the outlet of the photoelectric heating system (8) is also connected to the vent air main reserved port (17).

4. The wellhead pressure difference power generation system for medium- and high-pressure natural gas wells according to claim 3 is characterized in that: The branch line where the vent air recovery device (4) is located is also provided with a second ball valve (403) and a first throttling stop vent valve (404).

5. The wellhead pressure difference power generation system for medium- and high-pressure natural gas wells according to claim 1, characterized in that: A liquid phase storage tank (13) is also provided between the centrifugal separator (5) and the liquid phase treatment skid (14); a tenth ball valve (415) is provided between the liquid phase treatment skid (14) and the water electrolysis hydrogen production device (11); a fifth ball valve (408) is also provided between the gas collection manifold reserved port (15) and the centrifugal separator (5); and a sixth ball valve (409) is provided between the centrifugal separator (5) and the gas purification skid (6).

6. The wellhead pressure difference power generation system for medium- and high-pressure natural gas wells according to claim 1, characterized in that: A second pressure monitor (502) and a first temperature monitor (701) are also provided between the first throttle valve (401) and the reserved port (15) of the gas collection manifold; a third ball valve (405), a second throttle valve (406) and a third pressure monitor (503) are also provided between the first ball valve (402) and the reserved port (16) of the gas outlet manifold; and a fourth ball valve (407) and a second flow monitor (602) are provided between the reserved port (16) of the gas outlet manifold and the natural gas processing station (3).

7. The wellhead pressure difference power generation system for medium- and high-pressure natural gas wells according to claim 1, characterized in that: A fourth pressure monitor (504) and a second temperature monitor (702) are arranged between the seventh ball valve (410) and the pressure difference power generation skid (7); a fifth pressure monitor (505), a third temperature monitor (703), and a check valve (411) are arranged at the outlet of the photovoltaic heating system (8); an eighth ball valve (412) and a ninth ball valve (414) are also arranged between the photovoltaic heating system (8) and the natural gas processing station (3); and a second throttling stop vent valve (413) is arranged between the check valve (411) and the reserved port (17) of the air vent main pipe.

8. The wellhead pressure difference power generation system for medium- and high-pressure natural gas wells according to claim 7, characterized in that: The hydrogen production system further comprises a pressure regulating device (12) arranged between the outlet of the water electrolysis hydrogen production device (11) and a reserved port (16) of the gas outlet manifold.

9. The wellhead pressure difference power generation system for medium- and high-pressure natural gas wells according to claim 8, characterized in that: A sixth pressure monitor (506) is arranged between the water electrolysis hydrogen production device (11) and the pressure regulating device (12); the outlet of the pressure regulating device (12) is connected between the eighth ball valve (412) and the ninth ball valve (414); a seventh pressure monitor (507), a fourth temperature monitor (704), an eleventh ball valve (416) and a fourth flow monitor (604) are arranged in sequence between the pressure regulating device (12) and the ninth ball valve (414) along the gas flow direction.

10. The wellhead pressure difference power generation system for a medium- and high-pressure natural gas well according to any one of claims 1 to 9, characterized in that: The control system is a SCADA control system, which is used to monitor the temperature, pressure and flow of the wellhead differential pressure power generation system and adjust the fluid flow in the differential pressure power generation system through valves.

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