A differential pressure power generation system for a natural gas processing plant

Abstract

The application discloses a differential pressure power generation system of a natural gas treatment station and belongs to the technical field of natural gas transmission. The system comprises an inlet separation metering subsystem, a differential pressure power generation subsystem and a high-pressure venting subsystem, all of which are connected with a control system. The inlet separation metering subsystem comprises a separation unit and a metering unit. The separation unit comprises a first horizontal separator connected with a gas inlet port of an upstream single well or a gas gathering station. The liquid phase outlet of the first horizontal separator is connected with a port of a condensate oil stabilizing device. The metering unit comprises a vertical separator connected with the gas inlet port of the upstream single well or the gas gathering station. The gas phase outlet of the vertical separator is connected with the inlet of the first horizontal separator. Through the control of the control system and the interactive cooperation of the multiple subsystems, clean power can be generated by effectively utilizing pressure energy while ensuring the continuous and safe transmission of natural gas and meeting the process requirements of the treatment station.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of natural gas transportation, and relates to a differential pressure power generation system of a natural gas treatment station. BACKGROUND

[0002] Natural gas is a clean and high-quality energy and chemical raw material, but most of the gas fields producing natural gas are located in remote areas and far away from the main gas-consuming cities. Therefore, a continuous and sealed high-pressure long-distance pipeline is mostly used to transport natural gas from the gas field to the gas-consuming city in China. However, due to the limitations of pipeline materials, construction costs and other factors, the operating pressure of the high-pressure long-distance pipeline in China is mostly lower than 12 MPa, but the wellhead pressure of the natural gas produced by the ultra-deep gas field in China may be as high as 70 MPa. Therefore, the gathering pipeline between the wellhead of the natural gas and the long-distance pipeline generally needs to be regulated multiple times. Among them, in the natural gas gathering and treatment station, the existing pressure regulating process often uses a J-T valve to reduce the pressure, and the pressure potential energy of the natural gas is not fully utilized, and a large amount of energy is wasted. In recent years, in order to fully utilize the pressure potential energy in the natural gas transportation process, the expansion power generation technology has been gradually developed and applied. The existing expansion power generation technology mainly includes the following three kinds: turbine expander technology, double-rotor expander technology and screw expander technology. Among them, the efficiency of the turbine expander technology is generally greater than 80% when generating power, which is significantly higher than the other two technologies. Therefore, it is the preferred option to use the turbine expander technology to utilize the pressure potential energy of the natural gas in the natural gas treatment station.

[0003] However, the existing differential pressure power generation systems and devices in the energy field using turboexpander technology have some technical defects. For example, the Chinese invention patent with publication number CN114673566A discloses a differential pressure power generation device and system for natural gas pipeline pressure energy recovery, but the disadvantage of the system is that the temperature of the natural gas after power generation is low, and heating equipment needs to be additionally provided to heat the natural gas. The Chinese invention patent with authorization announcement number CN104234752B discloses an expander differential pressure power generation system and a control method thereof, but it mainly aims at the special situation of expander emergency shutdown. The Chinese invention patent with publication number CN103334891A discloses a natural gas pressure regulating type power generation device, but the device is a simple parallel structure and does not consider the maintenance of the device and the venting demand of natural gas during maintenance. The Chinese invention patent with publication number CN115681040A discloses an energy comprehensive utilization system and method for photovoltaic-photothermal coupled differential pressure power generation, which provides low-grade heat for differential pressure power generation through the waste heat after solar power generation, but it only simply combines the concepts of photovoltaic, photothermal and differential pressure power generation, mainly considers how to form the complement of several technologies, and cannot realize the benefit maximization of the differential pressure power generation system. The Chinese invention patent with publication number CN115434776A discloses a natural gas expansion differential pressure power generation system, which controls four power generation modes according to the principle of maximum economic benefit to produce electric power, compressed natural gas or liquefied natural gas, so as to realize the maximum utilization of natural gas pressure energy, but the scheme mainly aims at the situation that the gas transmission amount may have large fluctuations, and when it is applied to a treatment station with stable gas source, it will face the problems of excessive investment and equipment redundancy. SUMMARY

[0004] The purpose of the present application is to solve the technical problems of the differential pressure power generation system of the natural gas treatment station in the prior art, such as no natural gas heating equipment, unable to vent natural gas during maintenance, and unreasonable structure design with equipment redundancy, and to provide a differential pressure power generation system of a natural gas treatment station.

[0005] In order to achieve the above purpose, the present application adopts the following technical scheme:

[0006] The present application provides a differential pressure power generation system of a natural gas treatment station, comprising an inlet separation metering subsystem, a differential pressure power generation subsystem and a high-pressure venting subsystem, all of which are connected with a control system.

[0007] The inlet separation metering subsystem comprises a separation unit and a metering unit; the separation unit comprises a first horizontal separator connected with an upstream single well or gas gathering station gas inlet port, a gas phase outlet of the first horizontal separator is connected with a condensate stabilizer device port, a gas-liquid heat exchanger and a first gas-gas heat exchanger are connected with a second horizontal separator; the metering unit comprises a vertical separator connected with an upstream single well or gas gathering station gas inlet port, a gas phase outlet of the vertical separator is connected with an inlet of the first horizontal separator; a liquid phase outlet of the vertical separator is connected with the condensate stabilizer device port; a gas phase flow observer is arranged at the gas phase outlet of the vertical separator, and a liquid phase flow observer is arranged at the liquid phase outlet.

[0008] The pressure difference power generation subsystem comprises a pressure difference power generator pry connected with a gas phase outlet of the second horizontal separator, a gas phase outlet of the pressure difference power generator pry is connected with a third horizontal separator; a pressure difference power generation system front reserved port is arranged between the first gas-gas heat exchanger and the second horizontal separator, the pressure difference power generation system front reserved port is connected with the third horizontal separator, a pressure difference power generation system rear reserved port is arranged between the pressure difference power generation system front reserved port and the third horizontal separator, a J-T valve is arranged between the pressure difference power generation system front reserved port and the pressure difference power generation system rear reserved port; the third horizontal separator is connected with an external pipeline port in sequence through the first gas-gas heat exchanger and the second gas-gas heat exchanger; the pressure difference power generator pry is connected with a power grid connection system.

[0009] The high-pressure venting subsystem comprises a venting pipeline connecting a gas phase outlet of the pressure difference power generator pry with a high-pressure venting device port.

[0010] Further improvements of the present application are as follows:

[0011] The condensate recovery subsystem further comprises a condensate recovery device gas inlet port and a condensate recovery device port connected with a gas-liquid mixed outlet of the second horizontal separator; the condensate recovery device gas inlet port is connected with a gas phase inlet of the third horizontal separator through the second gas-gas heat exchanger, and the gas-liquid mixed outlet of the third horizontal separator is connected with the condensate recovery device port.

[0012] The antifreeze working subsystem further comprises an antifreeze adding port arranged between the first horizontal separator and the gas-liquid heat exchanger; after the antifreeze flows into the second horizontal separator and the third horizontal separator for separation, the antifreeze flows into a sewage treatment device port or an antifreeze recovery device port through a pipeline.

[0013] The antifreeze is methanol, ethylene glycol, ethanol or propylene glycol.

[0014] Further comprising a heating subsystem; the heating subsystem comprises a liquid end port of the heating system connected to the liquid phase inlet of the gas-liquid heat exchanger through a pipeline, and the heating water flows to the heating system port after heat exchange in the gas-liquid heat exchanger.

[0015] The gas phase outlet of the second horizontal separator is connected with the sealed bin of the differential pressure generator pry for sealing the differential pressure generator pry.

[0016] The devices are connected through pipelines, and valves are arranged on the pipelines.

[0017] The gas phase flow observer adopts an ultrasonic flow meter, a turbine flow meter, a vortex flow meter, a rotational flow meter, a differential pressure flow meter or an orifice flow meter; and the liquid phase flow observer adopts an electromagnetic flow meter, a differential pressure flow meter, a turbine flow meter, a volumetric flow meter or a contact flow meter.

[0018] The condensate stabilizing device is replaced by an oil-water mixture treatment device.

[0019] The control system is a DCS control system, which is used for monitoring the temperature, pressure and flow of the differential pressure power generation system of the natural gas treatment station, and adjusting the fluid flow in the differential pressure power generation system through valves.

[0020] Compared with the prior art, the application has the following beneficial effects:

[0021] The application discloses a differential pressure power generation system of a natural gas treatment station, which comprises an inlet separation and metering subsystem, a differential pressure power generation subsystem and a high-pressure venting subsystem, all of which are connected with a control system; through the control of the control system and the interaction and cooperation of the multiple subsystems, clean power can be effectively generated by utilizing pressure energy while ensuring the continuous and safe transportation of natural gas and meeting the process requirements of the treatment station; two sets of pipelines and devices for separation and metering are arranged at the inlet of the treatment station, which can effectively meet the two requirements of metering and treatment of the treatment station, and can preliminarily separate liquid phases contained in the natural gas, so that the requirements of the differential pressure power generation and the requirements of the external gas quality of the treatment station are met. The differential pressure power generation system can utilize the pressure potential energy of the natural gas by using the differential pressure generator pry, and can meet the bypass pressure reduction requirement in special conditions by using the J-T valve device, so that the continuous and safe operation requirement of the treatment station is met. The application is especially suitable for natural gas centralized treatment stations which are provided with J-T valves and gas quantity stabilizers. By arranging a horizontal separator before and after the differential pressure generator pry, liquid phases such as antifreeze and condensate contained in the natural gas can be fully separated, the separation and recovery capacity of the liquid phases such as antifreeze and condensate is improved, so that the operation and maintenance cost is reduced and the benefit is improved.

[0022] Further, the differential pressure power generation system of the natural gas treatment station further comprises a condensate recovery subsystem, which fully utilizes the heat of the incoming natural gas to heat the water supply pipeline and the external natural gas, and exchanges heat between the condensate from the condensate recovery device and the external natural gas, so as to increase the temperature of the heating water and the temperature of the external natural gas, without the need of additionally adding heating equipment, greatly improving the heat utilization efficiency, and the process is relatively simple, the equipment stability is good, and the maintenance and repair are convenient.

[0023] Further, the gas phase outlet of the second horizontal separator is connected with the sealing bin of the differential pressure power generation machine, for sealing the differential pressure power generation machine, and the natural gas is used as raw material gas or instrument air system in the treatment station to provide sealing gas for the differential pressure power generation machine, so that the nitrogen sealing device and pipeline can be reduced, thereby reducing the investment cost. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced as follows, and it should be understood that the following drawings only show some embodiments of the present application, and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0025] Figure 1 FIG. 1 is a structural schematic diagram of a differential pressure power generation system of a natural gas treatment station according to the present application;

[0026] Figure 2 FIG. 2 is a schematic diagram of an inlet metering and separation subsystem of the differential pressure power generation system of the natural gas treatment station according to the present application;

[0027] Figure 3 FIG. 3 is a schematic diagram of a differential pressure power generation subsystem of the differential pressure power generation system of the natural gas treatment station according to the present application;

[0028] Figure 4 FIG. 4 is a schematic diagram of an anti-freezing agent recovery subsystem of the differential pressure power generation system of the natural gas treatment station according to the present application;

[0029] Figure 5 FIG. 5 is a schematic diagram of a condensate recovery subsystem of the differential pressure power generation system of the natural gas treatment station according to the present application;

[0030] Figure 6 FIG. 6 is a schematic diagram of a high-pressure venting subsystem of the differential pressure power generation system of the natural gas treatment station according to the present application;

[0031] Figure 7 FIG. 7 is a schematic diagram of a heating subsystem of the differential pressure power generation system of the natural gas treatment station according to the present application.

[0032] Wherein: 1 - upstream single well or gas station gas port; 2 - to the condensate stabilization device port; 3 - to the sewage treatment device port; 4 - to the antifreeze recovery device port; 5 - heating system liquid port; 6 - to the heating system port; 7 - to the export pipeline port; 8 - to the high-pressure venting device port; 9 - condensate recovery device gas port; 10 - to the condensate recovery device port; 11 - differential pressure generator pry; 12 - front reserved port of the differential pressure power generation system; 13 - rear reserved port of the differential pressure power generation system; 101 - inlet manifold; 102 - inlet gas metering branch pipe; 103 - inlet gas main pipe; 104 - liquid phase metering branch pipe; 105 - gas phase metering branch pipe; 106 - separated liquid phase main pipe; 107 - separated gas phase main pipe; 201 - raw gas inlet gas main pipe; 202 - dry gas sealing inlet gas branch pipe; 203 - raw gas outlet gas main pipe; 204 - dry gas outlet gas main pipe; 205 - condensate recovery gas pipeline; 206 - bypass pressure reduction branch pipe; 301 - antifreeze recovery branch pipe; 302 - antifreeze recovery main pipe; 303 - antifreeze recovery pipeline; 304 - blowdown pipeline; 401 - condensate recovery main pipe; 402 - condensate recovery branch pipe; 501 - leakage gas recovery branch pipe; 502 - venting gas recovery branch pipe; 503 - high-pressure venting main pipe; 601 - heating water pipeline; 1001 - first electric ball valve; 1002 - second electric ball valve; 1003 - first pneumatic ball valve; 1004 - first electric regulating valve; 1005 - first regulating valve; 1006 - vertical separator; 1007 - first horizontal separator; 1008 - second horizontal separator; 1009 - gas phase flow observer; 1010 - liquid phase flow observer; 2001 - second pneumatic ball valve; 2002 - second regulating valve; 2003 - J-T valve; 2004 - third pneumatic ball valve; 2005 - first ball valve; 2006 - third regulating valve; 2007 - first check valve; 2008 - fourth pneumatic ball valve; 2009 - third horizontal separator; 2010 - first pressure observer; 2011 - second pressure observer; 2012 - third pressure observer; 2013 - first temperature observer; 2014 - second temperature observer; 2015 - first gas-gas heat exchanger; 2016 - second gas-gas heat exchanger; 3001 - fourth regulating valve; 3002 - fifth regulating valve; 4001 - sixth regulating valve; 5001 - second electric regulating valve; 6001 - gas-liquid heat exchanger. DETAILED DESCRIPTION

[0033] In order to make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0034] The following detailed description of the embodiments of the application provided in the accompanying drawings is not intended to limit the scope of the application as claimed, but merely represents selected embodiments of the application. Based upon the embodiments of the application, all other embodiments that would be obvious to one of ordinary skill in the art and made without having exerted inventive faculty belong to the scope of the protection of the application.

[0035] It should be noted that similar reference numbers and letters in the following drawings represent similar items, and therefore, once an item is defined in one drawing, it need not be further defined and explained in subsequent drawings.

[0036] In the description of the embodiments of the application, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship when the product of the application is usually placed, and are only for the convenience of describing the application and simplifying the description, and therefore cannot be understood as indicating or implying that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the application. In addition, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0037] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly inclined. For example, "horizontal" only means that its direction is relatively more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined.

[0038] In the description of the embodiments of the application, it should also be noted that unless otherwise explicitly specified and limited, if the terms "arrangement", "installation", "connection", "connection" appear, they should be understood in a broad sense, for example, they can be fixedly connected, or detachably connected, or integrally connected; can be mechanically connected, or electrically connected; can be directly connected, or indirectly connected through an intermediate medium; can be the communication inside two elements. For those of ordinary skill in the art, the specific meaning of the above terms in the application can be understood according to the specific circumstances.

[0039] The application will be described in further detail below in conjunction with the accompanying drawings:

[0040] Referring to Figure 1 The embodiment of the application discloses a differential pressure power generation system of a natural gas treatment station, comprising an inlet separation metering subsystem, a differential pressure power generation subsystem, a high-pressure venting subsystem, a condensate recovery subsystem, an antifreeze working subsystem and a heating subsystem, all of which are connected with a control system.

[0041] Referring to Figure 2The inlet separation metering sub-system comprises a separation unit and a metering unit; the separation unit comprises a first horizontal separator 1007 connected with the upstream single well or gas gathering station gas inlet port 1, a liquid phase outlet of the first horizontal separator 1007 is connected with a condensate stabilizer port 2, a gas phase outlet of the first horizontal separator 1007 is connected with a second horizontal separator 1008 through a gas-liquid heat exchanger 6001 and a first gas-gas heat exchanger 2015; the metering unit comprises a vertical separator 1006 connected with the upstream single well or gas gathering station gas inlet port 1, a gas phase outlet of the vertical separator 1006 is connected with an inlet of the first horizontal separator 1007; a liquid phase outlet of the vertical separator 1006 is connected with the condensate stabilizer port 2; a gas phase flow observer 1009 is arranged at the gas phase outlet of the vertical separator 1006, and a liquid phase flow observer 1010 is arranged at the liquid phase outlet.

[0042] The inlet separation device and pipeline refer to that the inlet natural gas is separated by a plurality of valves and gas-liquid separators, and then the natural gas with a large amount of liquid phase is sent to the condensate stabilizer, and the natural gas with a small amount of liquid phase is sent to the differential pressure compression system. The inlet separation device and pipeline are the main conveying channel of the inlet natural gas, and mainly comprise an inlet manifold 101, an inlet gas main pipe 103, a first horizontal separator 1007, a separated liquid phase main pipe 106, a separated gas phase main pipe 107 and valves on the pipeline.

[0043] The inlet metering device and pipeline refer to that the inlet natural gas enters the vertical separator 1006 through the inlet metering branch pipe 102, and then the gas phase and the liquid phase in the natural gas with a large amount of liquid phase are separated and metered by the gas phase flow observer 1009 and the liquid phase flow observer 1010 respectively, and then the gas phase is conveyed to the first horizontal separator 1007 through the gas phase metering branch pipe 105 for further separation, and the liquid phase is conveyed to the separated liquid phase main pipe 106 through the liquid phase metering branch pipe 104 and then sent to the condensate stabilizer. The inlet metering device and pipeline are the main metering channel of the inlet natural gas, and mainly comprise the inlet metering branch pipe 102, the vertical separator 1006, the liquid phase metering branch pipe 104, the gas phase metering branch pipe 105, the gas phase flow observer 1009, the liquid phase flow observer 1010 and valves on the pipeline.

[0044] Optionally, the vertical separator 1006 can also be a horizontal separator.

[0045] Optionally, the gas phase flow observer 1009 can be an ultrasonic flow meter, a turbine flow meter, a vortex flow meter, a rotary flow meter, a differential pressure flow meter, an orifice flow meter and the like. The liquid phase flow observer 1010 can be an electromagnetic flow meter, a differential pressure flow meter, a turbine flow meter, a volumetric flow meter, a contact flow meter and the like.

[0046] It is worth noting that the first electric ball valve 1001 and the second electric ball valve 1002 are not allowed to be opened at the same time in principle, that is, part of the inlet natural gas cannot enter the separation pipeline and part of the inlet natural gas cannot enter the metering pipeline.

[0047] The first electric ball valve 1001 and the second electric ball valve 1002 are used to adjust the opening and closing of the pipeline. The first pneumatic ball valve 1003 is used to adjust the flow. The first electric regulating valve 1004 and the first regulating valve 1005 are used to adjust the flow.

[0048] The separation liquid phase is generally condensate oil or oil-water mixture. Alternatively, the condensate oil stabilizer to which the condensate oil is sent can also be an oil-water mixture treatment device.

[0049] The DCS control system mainly concentrates on managing the equipment and valves in the gas transmission station and dispersively controls the equipment and valves in the gas transmission station. The DCS control system can realize the alarm function and the control function according to the monitored pressure, flow, temperature and other data. Intuitively, the DCS control system can control the valves.

[0050] Referring to Figure 3 , the differential pressure power generation system includes a differential pressure power generation sled 11 connected with a gas phase outlet of the second horizontal separator 1008, a gas phase outlet of the differential pressure power generation sled 11 is connected with a third horizontal separator 2009; a differential pressure power generation system front reserved port 12 is arranged between the first gas-gas heat exchanger 2015 and the second horizontal separator 1008, the differential pressure power generation system front reserved port 12 is connected with the third horizontal separator 2009, a differential pressure power generation system rear reserved port 13 is arranged between the differential pressure power generation system front reserved port 12 and the third horizontal separator 2009, a J-T valve 2003 is arranged between the differential pressure power generation system front reserved port 12 and the differential pressure power generation system rear reserved port 13; the third horizontal separator 2009 is connected with a pipeline to the export pipeline port 7 in sequence after passing through the first gas-gas heat exchanger 2015 and the second gas-gas heat exchanger 2016; the differential pressure power generation sled 11 is connected with a power grid connection system;

[0051] The differential pressure power generation system includes a differential pressure power generation sled, a power grid connection system, a gas phase conveying pipeline, a J-T valve, a horizontal separator, a heat exchanger and connected pipelines and valves.

[0052] The differential pressure power generation sled is a complete set of modularly configured differential pressure power generation sled equipment, including a turbo expander, an asynchronous generator, a lubricating oil system, a cooling system, a control system, a thermal resistance, a pressure transmitter and other supporting auxiliary equipment and inter-sled wiring.

[0053] The turbine expander of the differential pressure generator pry is designed according to the pressure drop and temperature drop of the J-T valve and the flow of the treated natural gas in the station; the asynchronous generator needs to be combined with the environment of the gas transmission station and the requirement of low maintenance, and the generator set widely used in the market at present is adopted, which is mature in technology and simple in structure, high in reliability and not limited by the use place; the lubricating oil system adopts a three-oil-pump oil supply mode of a main oil pump MOP, an auxiliary oil pump AOP and an emergency oil pump EOP, and does not set a high oil tank; the cooling system adopts an air cooling mode; the control system is a complete turbine expansion generator control system, including system design, hardware manufacturing, cabinet integration, system configuration and testing; the control system can be isolated when the turbine expander has an accident (such as overspeed, lack of lubricating oil, abnormal pressure rise, etc.), so as to ensure the safety of the pry generator set.

[0054] The sealing of the differential pressure generator pry is mainly completed by means of the instrument air system in the natural gas treatment station, and nitrogen is generally used as the sealing gas. Dry gas separated by the second horizontal separator 1008 can also be used to enter the sealing chamber through the dry gas sealing inlet branch pipe 202.

[0055] Due to the limitations of materials and processes, the differential pressure generator pry cannot achieve absolute sealing, and a small amount of leakage gas still passes through the secondary seal and enters the leakage gas recovery branch pipe 501 through the gas outlet.

[0056] The power grid connection system refers to the power generated by the differential pressure generator pry, which is transmitted to the high-voltage distribution room of the natural gas treatment station through high-voltage cables, and automatically adjusts and controls the energy relationship between the grid power and the differential pressure power to realize the power supply mode of grid power and differential pressure power combination, and preferentially uses differential pressure power to supply power to the power equipment in the treatment station, and grid power as a beneficial supplement.

[0057] The grid connection system should have the functions of complementary self-regulation with grid power, anti-island protection and emergency fault power-off.

[0058] The complementary self-regulation function of grid power: the phase sequence of the generated power should be the same as that of the grid power return; the voltage effective value of the generated power should be close to or equal to that of the grid power, and the waveforms should be the same; the frequency of the generated power should be basically equal to that of the power system; the voltage phase of the generated power should be equal to that of the power system power supply; according to the amount of generated power, the complementary self-regulation with grid power is realized to supply power to the natural gas treatment station.

[0059] Grid-connected anti-islanding protection function: when overvoltage, low voltage, frequency is too high, frequency is too low, frequency mutation, reverse power, external tie jump, system power failure, frequency mutation lockout low frequency, voltage automatic closing, analog tripping and other conditions occur, the grid-connected system can be automatically controlled to realize the separation and protection of grid power and pressure difference power generation.

[0060] Emergency fault power-off function: in order to ensure the safety and reliability of power supply, in order to make the pressure difference generator set run reliably and stably after being connected to the grid, the set should have safety protection device, once the set occurs overload fault, overspeed fault, pressure fault, temperature fault, power direction fault, emergency stop device and other faults, it should be automatically tripped, separated from the grid power, and automatically stopped.

[0061] The high-voltage cable of the grid-connected system is directly buried and laid, is protected by being laid through power tubes, is protected by being laid with sand and covered with protection plates. The connection between the cable and the pressure difference generator set adopts an explosion-proof cable sealing head with a double-sealing structure.

[0062] The gas phase conveying pipeline mainly comprises a raw gas inlet main pipe 201, a raw gas outlet main pipe 203 and a dry gas outlet main pipe 204.

[0063] The J-T valve 2003 is a Joule-Thomson throttling expansion valve, which is designed according to the Joule-Thomson throttling expansion principle and is located on the 1020 bypass pressure reduction branch pipe.

[0064] Alternatively, the J-T valve 2003 can also be replaced by other components with the same throttling pressure reduction and temperature reduction effect, and such components should have the same Joule-Thomson throttling expansion principle.

[0065] The horizontal separators comprise a second horizontal separator 1008 and a third horizontal separator 2009, which have the same effect of separating liquid-phase media such as antifreeze, oil and water from natural gas, so that the natural gas containing a small amount of liquid droplets is converted into dry gas that can be externally transported.

[0066] The heat exchangers comprise a first gas-gas heat exchanger 2015 and a second gas-gas heat exchanger 2016, which are used for exchanging heat between high-temperature gas and low-temperature gas, so that the heat of the high-temperature gas is transferred to the low-temperature gas, thereby improving the heat utilization efficiency.

[0067] The first gas-gas heat exchanger 2015 is used for exchanging heat between natural gas containing a small amount of liquid and dry gas that is externally transported after being throttled, pressure-reduced and temperature-reduced, so as to increase the temperature of the externally transported natural gas. The second gas-gas heat exchanger 2016 is used for exchanging heat between natural gas containing a small amount of liquid droplets and externally transported natural gas, so as to further increase the temperature of the externally transported natural gas.

[0068] It is worth noting that the third regulating valve 2006 and the first ball valve 2005 can be opened at the same time, that is, the raw gas can act as the sealing gas of the differential pressure generator.

[0069] The second pneumatic ball valve 2001, the third pneumatic ball valve 2004, and the fourth pneumatic ball valve 2008 are used to regulate the opening and closing of the pipeline. The first ball valve 2005 is used to regulate the flow. The J-T valve 2003 and the third regulating valve 2006 are used to regulate the pressure. The first check valve 2007 is used to prevent the backflow of natural gas into the differential pressure generator.

[0070] The first pressure observer 2010 and the second pressure observer 2011 are used to observe the pressure before and after the third regulating valve 2006, and the third pressure observer 2012 is used to observe the pressure at the outlet of the differential pressure generator.

[0071] The first temperature observer 2013 and the second temperature observer 2014 are used to observe the temperature at the inlet and outlet of the differential pressure generator, respectively.

[0072] Referring to Figure 4 , the antifreeze working subsystem includes an antifreeze adding port between the first horizontal separator 1007 and the gas-liquid heat exchanger 6001. After the antifreeze flows into the second horizontal separator 1008 and the third horizontal separator 2009 for separation, it flows into the sewage treatment device port 3 or the antifreeze recovery device port 4 through the pipeline.

[0073] The antifreeze working subsystem includes the addition, separation, and recovery of antifreeze, as well as the connected pipelines and valves.

[0074] Optionally, the antifreeze can be methanol, ethylene glycol, ethanol, propylene glycol, etc.

[0075] The antifreeze adding port is generally located on the separation gas phase main pipe 107, between the gas-liquid heat exchanger 6001 and the first horizontal separator 1007.

[0076] The separation of antifreeze mainly relies on the second horizontal separator 1008 and the third horizontal separator 2009. A large amount of antifreeze separated from the second horizontal separator 1008 flows through the antifreeze recovery main pipe 302, generally flows into the antifreeze recovery pipeline 303, and goes to the antifreeze recovery device. In special cases, it can also flow into the sewage pipeline 304 and go to the sewage treatment device. A small amount of antifreeze separated from the third horizontal separator 2009 flows through the antifreeze recovery branch pipe 301 and flows into the antifreeze recovery main pipe 302.

[0077] The fourth regulating valve 3001 is used for the flow of the antifreeze recovery main pipe 302.

[0078] Referring to Figure 5The condensate recovery subsystem includes a condensate recovery device, a condensate recovery device gas port 9, and a condensate recovery device port 10 connected to the gas-liquid mixed outlet of the second horizontal separator 1008; the condensate recovery device gas port 9 is connected to the gas phase inlet of the third horizontal separator 2009 through the second gas-gas heat exchanger 2016, and the gas-liquid mixed outlet of the third horizontal separator 2009 is connected to the condensate recovery device port 10.

[0079] The condensate recovery subsystem includes equipment, pipelines and valves for sending the condensate separated from the natural gas to the condensate recovery device, and equipment, pipelines and valves for sending the higher-temperature natural gas separated from the condensate recovery device to the third horizontal separator 2009.

[0080] Condensate refers to a liquid hydrocarbon mixture recovered from natural gas and not subjected to stabilization treatment, generally including ethane, propane, butane and part of the stable light hydrocarbon components.

[0081] The condensate separated by the second horizontal separator 1008 is sent to the condensate recovery device through the condensate recovery main pipe 401. The condensate separated from the natural gas by the third horizontal separator 2009 is sent to the condensate recovery main pipe 401 through the condensate recovery branch pipe 402.

[0082] Optionally, due to the pressure reduction and temperature reduction effect of the pressure differential generator pry, the temperature and pressure at the outlet of the pressure differential generator pry are significantly lower than those at the inlet, so the pressure and temperature of the third horizontal separator 2009 are significantly lower than those of the second horizontal separator 1008, and the amount of condensate separated from the third horizontal separator 2009 is generally greater than that separated from the second horizontal separator 1008. Therefore, the main and branch of the condensate recovery main pipe 401 and the condensate recovery branch pipe 402 are only used to distinguish the connection mode of the pipelines, and are not used to distinguish the flow rate, i.e., the condensate recovery main pipe and the condensate recovery branch pipe are only names and can be interchangeable.

[0083] The higher-temperature natural gas separated from the condensate recovery device is sent to the third horizontal separator 2009 through the condensate recovery gas pipe 205 and the second gas-gas heat exchanger 2016 after heat exchange with the external natural gas.

[0084] The fifth regulating valve 3002 and the sixth regulating valve 4001 are used to regulate the flow rate.

[0085] Referring to Figure 6 The high-pressure venting subsystem includes a venting pipe connecting the gas phase outlet of the pressure differential generator pry 11 to the high-pressure venting device port 8.

[0086] The high-pressure venting subsystem includes a leakage gas recovery branch pipe 501, a venting gas recovery branch pipe 502, a high-pressure venting main pipe 503 and valves thereof.

[0087] The function of the vent gas recovery branch pipe 502 is to release the flammable and explosive natural gas in the system when the pressure difference power generation system is in emergency shutdown or maintenance, so as to ensure the safety of the pressure difference power generation system; the released natural gas enters the vent gas recovery branch pipe and goes to the high-pressure vent main pipe.

[0088] The function of the leakage gas recovery branch pipe 501 is that although a strict sealing system has been adopted, due to the limitation of the process level, a small amount of natural gas working medium still leaks from the pressure difference generator pry, and the leakage of the small amount of gas is guided into the vent gas recovery branch pipe by the leakage gas recovery branch pipe, and then goes to the high-pressure vent main pipe.

[0089] The high-pressure vent main pipe 503 mainly guides the leaked or released high-pressure natural gas to the high-pressure vent device, so as to meet the requirement of removing the combustible natural gas in the device.

[0090] Optionally, the high-pressure vent device can also be a vent gas recovery device, so as to recover the leaked or released natural gas. The specific selection should be comprehensively considered according to factors such as economy and environmental protection requirements.

[0091] Referring to Figure 7 The heating subsystem comprises a heating system liquid end port 5 connected to the liquid phase inlet of the gas-liquid heat exchanger 6001, and heating water flows to a heating system port 6 after heat exchange in the gas-liquid heat exchanger 6001.

[0092] The heating subsystem refers to pipelines, heat exchangers and valves for heat exchange between heating water in the living area and natural gas with a higher temperature entering the station.

[0093] Heat exchange between the heating water pipeline and the natural gas with a higher temperature entering the station is beneficial to saving the gas consumption of the living area.

[0094] Optionally, the heating water pipeline can be provided with energy supplement in the form of photovoltaic power generation, photothermal heating or air source heat pump, water source heat pump and the like, but economic efficiency needs to be considered.

[0095] The working principle of the application is as follows:

[0096] The inlet separation metering subsystem is used for metering and preliminarily separating the natural gas containing a large amount of liquid phase entering the treatment station under the control of the DCS control system. The separated natural gas containing a small amount of liquid phase enters the pressure difference power generation subsystem; and the large amount of liquid phase after separation goes to the condensate oil stabilization device.

[0097] The differential pressure power generation system is used for providing a stable, reliable, economical and practical process, fully utilizing the pressure potential energy of the natural gas to generate electric energy, and fully utilizing the heat in the station to provide heat for the natural gas after pressure reduction, so as to meet the requirements of temperature and pressure of the natural gas for external transmission.

[0098] The antifreeze working subsystem is used for adding the antifreeze into the natural gas in the station to reduce the freezing point and improve the antifreeze capacity, so as to prevent the hydrate formation and pipe or equipment freezing in the cooling process. The separated antifreeze is recovered by the separator, so as to realize the recycling of the antifreeze and save the cost.

[0099] The condensate recovery subsystem is used for separating the condensate with high economic value from the natural gas and sending the condensate to the condensate recovery device for centralized treatment. The natural gas with low pressure and relatively high temperature separated from the condensate recovery device is sent to the differential pressure power generation system and externally transmitted after being separated again.

[0100] The high-pressure venting subsystem is used for sending the natural gas in the system to the venting device through the high-pressure venting pipeline when the differential pressure power generation system of the natural gas treatment station needs to be overhauled or the leakage of the sealing gas needs to be released.

[0101] The heating subsystem is used for exchanging heat between the low-temperature heating water in the living area of the treatment station and the high-temperature natural gas entering the station, so as to reduce the temperature of the natural gas and increase the temperature of the heating water, thereby saving the heating cost.

[0102] The above only describes the preferred embodiments of the present application and is not used to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A differential pressure power generation system for a natural gas processing station, characterized in that, This includes an inlet separation metering subsystem, a differential pressure generator system, and a high-pressure venting subsystem, all of which are connected to the control system. The inlet separation and metering subsystem includes a separation unit and a metering unit; the separation unit includes a first horizontal separator (1007) connected to the upstream single well or gas gathering station gas inlet port (1), the liquid phase outlet of the first horizontal separator (1007) is connected to the port (2) leading to the condensate stabilization device, and the gas phase outlet of the first horizontal separator (1007) is connected to a second horizontal separator (1008) via a gas-liquid heat exchanger (6001) and a first gas-gas heat exchanger (2015); the metering The unit includes a vertical separator (1006) connected to the gas inlet port (1) of an upstream single well or gas gathering station. The gas phase outlet of the vertical separator (1006) is connected to the inlet of the first horizontal separator (1007). The liquid phase outlet of the vertical separator (1006) is connected to the port (2) leading to the condensate stabilization device. A gas phase flow meter (1009) is installed at the gas phase outlet of the vertical separator (1006), and a liquid phase flow meter (1010) is installed at the liquid phase outlet. The differential pressure power generation system includes a differential pressure generator skid (11) connected to the gas phase outlet of a second horizontal separator (1008), and the gas phase outlet of the differential pressure generator skid (11) is connected to a third horizontal separator (2009); a pre-reserved port (12) for the differential pressure power generation system is provided between the first gas-to-gas heat exchanger (2015) and the second horizontal separator (1008), and the pre-reserved port (12) for the differential pressure power generation system is connected to the third horizontal separator (2009). A reserved port (13) for a differential pressure power generation system is provided between port (12) and the third horizontal separator (2009). A JT valve (2003) is provided between the reserved port (12) for the differential pressure power generation system and the reserved port (13) for the differential pressure power generation system. The third horizontal separator (2009) is connected to an external transmission pipeline port (7) after passing through the first gas-to-gas heat exchanger (2015) and the second gas-to-gas heat exchanger (2016). The differential pressure generator skid (11) is connected to a power grid connection system. The high-pressure venting subsystem includes a venting pipe that connects the gas phase outlet of the differential pressure generator skid (11) to the port (8) leading to the high-pressure venting device.

2. The differential pressure power generation system of the natural gas processing station according to claim 1, characterized in that, It also includes a condensate recovery subsystem; the condensate recovery subsystem includes a condensate recovery device inlet port (9) and a condensate recovery device outlet (10) connected to the gas-liquid mixing outlet of the second horizontal separator (1008); the condensate recovery device inlet port (9) is connected to the gas phase inlet of the third horizontal separator (2009) via the second gas-to-gas heat exchanger (2016), and the gas-liquid mixing outlet of the third horizontal separator (2009) is connected to the condensate recovery device outlet (10).

3. The differential pressure power generation system of the natural gas processing station according to claim 1, characterized in that, It also includes an antifreeze working subsystem; the antifreeze working subsystem includes an antifreeze inlet provided between the first horizontal separator (1007) and the gas-liquid heat exchanger (601), and the antifreeze flows through the pipeline into the second horizontal separator (1008) and the third horizontal separator (2009) for separation, and then flows through the pipeline to the sewage treatment device port (3) or to the antifreeze recovery device port (4).

4. The differential pressure power generation system for a natural gas processing station according to claim 3, characterized in that, The antifreeze is methanol, ethylene glycol, ethanol or propylene glycol.

5. The differential pressure power generation system for a natural gas processing station according to claim 1, characterized in that, It also includes a heating subsystem; the heating subsystem includes the heating system liquid inlet (5) of the gas-liquid heat exchanger (6001) connected by a pipeline, and the heating water flows to the heating system port (6) after heat exchange in the gas-liquid heat exchanger (6001).

6. The differential pressure power generation system for a natural gas processing station according to claim 1, characterized in that, The gas phase outlet of the second horizontal separator (1008) is connected to the sealing chamber of the differential pressure generator skid (11) for sealing the differential pressure generator skid (11).

7. The differential pressure power generation system for a natural gas processing station according to any one of claims 1-6, characterized in that, The various devices are connected by pipes, and valves are installed on the pipes.

8. The differential pressure power generation system for a natural gas processing station according to claim 7, characterized in that, The gas phase flow observer (1009) is an ultrasonic flow meter, turbine flow meter, vortex flow meter, swirl flow meter, differential pressure flow meter or orifice plate flow meter; the liquid phase flow observer (1010) is an electromagnetic flow meter, differential pressure flow meter, turbine flow meter, volumetric flow meter or contact flow meter.

9. The differential pressure power generation system for a natural gas processing station according to claim 7, characterized in that, The condensate oil stabilization unit was replaced by an oil-water mixture treatment unit.

10. The differential pressure power generation system for a natural gas processing station according to claim 7, characterized in that, The control system is a DCS control system, which is used to monitor the temperature, pressure and flow rate of the differential pressure power generation system in the natural gas processing station, and to regulate the fluid flow rate in the differential pressure power generation system through valves.

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