A natural gas station integrated energy system with constant pressure compressed air energy storage

Abstract

The present invention discloses a natural gas station integrated energy system with constant pressure compressed air energy storage, which is applied to the upstream natural gas station, and the constant pressure pneumatic device is respectively connected to the air storage tank, the turbine of the fuel-driven compressor unit and the compressed air energy storage system, and the flue gas energy of the turbine of the fuel-driven compressor unit is recovered to maintain the compressed air energy storage system to always operate efficiently under the design conditions, and the turbine of the fuel-driven compressor unit is used as a driving heat source to achieve refrigeration or heating on the user side; it is applied to the downstream pressure regulating station, and the pressure potential energy of the natural gas in the upstream and downstream natural gas pipeline networks is recovered by the constant pressure pneumatic device, and the constant pressure energy storage and energy release operation of the compressed air energy storage system are maintained, and the heat exchange between the natural gas and the air occurs in the constant pressure pneumatic device, and the natural gas is maintained in an approximately constant temperature state during the throttling and pressure reduction process. The present invention improves the energy utilization efficiency and economic benefits of the natural gas station.

Description

Technical Field

[0001] The present invention belongs to the technical field of multi-energy recovery and utilization of natural gas stations, and specifically relates to a comprehensive energy system for natural gas stations integrating constant-pressure compressed air energy storage. Background Art

[0002] With the shortage of traditional fossil energy worldwide, as well as increasingly serious environmental pollution and ecological damage, vigorously developing renewable energy technology is considered an effective way to achieve the goal of "carbon peak and carbon neutrality". However, limited by the economic cost of existing renewable energy utilization technology, while promoting the development of renewable energy, it is necessary to improve the energy utilization rate of existing traditional fossil energy. Natural gas has become one of the ideal supplementary energy options at this stage due to its high calorific value and low pollution.

[0003] The natural gas source is usually far away from the user demand area, so it is necessary to transport natural gas through pipelines, which is mainly divided into two process flows: upstream natural gas pressurization and downstream natural gas decompression, that is, the transportation of natural gas is realized through high-pressure pipelines to increase the transportation volume of natural gas. However, in the actual operation of natural gas stations, both the upstream pressurization and downstream decompression processes of natural gas have insufficient energy utilization: in the upstream pressurization process, that is, in the operation of the upstream fuel-driven compressor unit, the flue gas waste heat generated by the fuel-driven compressor unit is not fully utilized and is directly discharged to the atmosphere, resulting in the technical problem that the natural gas station cannot fully utilize the surplus energy; in the downstream decompression process, that is, in the operation of the downstream pressure regulating station, the high-pressure natural gas needs to be decompressed on the end user side, usually using a throttle valve to regulate the pressure, resulting in irreversible dissipation of the pressure potential energy of the natural gas. In addition, in this process, as the natural gas pressure decreases, due to the Joule-Thomson effect, the temperature of the natural gas gradually decreases with the decrease in pressure, and there are even safety hazards such as ice blockage in the pipeline. Therefore, in the process of natural gas decompression, not only the pressure potential energy and thermal energy of the natural gas are lost, but also the natural gas transportation has safe operation process difficulties.

[0004] On the other hand, with the rapid development of renewable energy, its intermittent and undispatchy nature poses a huge challenge to the safe grid connection of renewable energy. In order to increase the proportion of renewable energy generation and solve the problem of grid connection fluctuation, energy storage technology has received widespread attention. Among the current energy storage technologies, compressed air energy storage is considered to be one of the most promising technologies due to its high reliability, long life and low cost. However, during the operation of the compressed air energy storage system, the pressure in the gas storage device in the system is constantly changing, causing the compressor unit to operate under variable back pressure. Although a throttling valve is set in front of the turbine unit to maintain a constant inlet pressure of the turbine unit, it causes a large throttling pressure loss, resulting in a low storage / release efficiency of the compressed air energy storage system, thereby limiting the energy efficiency of the overall system. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a natural gas station comprehensive energy system with integrated constant-pressure compressed air energy storage in response to the deficiencies in the above-mentioned prior art, which is used to solve the technical problem that the surplus energy of the natural gas station cannot be fully utilized, avoid the safe operation process difficulties caused by natural gas throttling and pressure reduction in the existing downstream pressure regulating station, improve the energy utilization efficiency and economic benefits of the natural gas station, and ensure the safe and stable operation of the natural gas station.

[0006] The present invention adopts the following technical solutions:

[0007] A natural gas station integrated energy system with constant pressure compressed air energy storage, including a constant pressure pneumatic device, corresponding to an upstream natural gas station, the constant pressure pneumatic device is respectively connected to a turbine of a fuel-driven compressor unit and an air storage tank, and the exhaust gas with waste heat of the turbine of the fuel-driven compressor unit is used as a driving heat source to realize cooling or heating on the user side;

[0008] Corresponding to the downstream pressure regulating station, the constant pressure pneumatic device is installed on the pipeline between the upstream high-pressure pipeline network and the downstream user pipeline network, and is respectively connected to the air storage tank and the compressed air energy storage system. The compressed air energy storage system converts the heat and pressure potential energy of natural gas and air through the constant pressure pneumatic device.

[0009] Specifically, the constant pressure pneumatic device includes a first pneumatic device, a second pneumatic device and a third pneumatic device which are arranged in parallel, and a floating piston is respectively arranged in the first pneumatic device, the second pneumatic device and the third pneumatic device; the input ends of the first pneumatic device, the second pneumatic device and the third pneumatic device are respectively connected to the upstream high-pressure pipeline network or the turbine of the fuel-driven compressor unit through corresponding gas valves; the output ends of the first pneumatic device, the second pneumatic device and the third pneumatic device are respectively connected to the downstream user pipeline network or the atmospheric environment through corresponding air valves; the air outlet ends of the first pneumatic device, the second pneumatic device and the third pneumatic device are respectively connected to the input end of the air storage tank through corresponding gas valves, and the output ends of the air storage tank are respectively connected to the air inlet ends of the first pneumatic device, the second pneumatic device and the third pneumatic device through corresponding air valves.

[0010] Furthermore, fins are arranged along the inner circumference of the floating piston.

[0011] Specifically, a natural gas pressure recovery system is provided between the upstream high-pressure pipeline network and the downstream user pipeline network, and the natural gas pressure recovery system is provided in parallel with the constant pressure pneumatic device.

[0012] Furthermore, the natural gas pressure recovery system includes a first valve, one end of which is connected to the upstream high-pressure pipeline network, and the other end is connected to the downstream user pipeline network via the second valve, the cold side of the first heat exchanger, the natural gas turbine and the hot side of the second heat exchanger in sequence. The first valve is connected to the natural gas inlet end of the natural gas turbine via the third valve, and is used to recover the natural gas pressure potential energy when the compressed air energy storage system and the constant pressure pneumatic device are in a static stage.

[0013] Specifically, the compressed air energy storage system includes an air compressor, which is connected to the air inlet of the air storage tank via the hot side of the third heat exchanger and the constant pressure pneumatic device in sequence, and the air outlet of the air storage tank is connected to the air inlet of the air turbine via the cold side of the fourth heat exchanger. The cold side of the third heat exchanger is divided into two paths through the thermal energy storage device, one path is connected to the cold energy storage device via the fourth heat exchanger, and the other path is connected to the cold energy storage device via the heat-driven energy supply device, and the outlet of the cold energy storage device is connected to the cold side of the third heat exchanger.

[0014] Specifically, the turbine of the fuel-driven compressor unit is coaxially connected to the compressor of the fuel-driven compressor unit and the natural gas compressor, and the compressor of the fuel-driven compressor unit is connected to the turbine of the fuel-driven compressor unit via the combustion chamber of the fuel-driven compressor unit.

[0015] Furthermore, the interstage exhaust outlet of the turbine of the fuel-driven compressor unit is connected to the gas inlet of the constant-pressure pneumatic device through the exhaust valve of the turbine of the fuel-driven compressor unit, and the gas outlet of the constant-pressure pneumatic device is connected to the atmospheric environment.

[0016] Specifically, the downstream pressure regulating station works. When the renewable energy is sufficient or the grid has surplus electricity, the air compressor consumes the renewable energy electricity or surplus electricity to pressurize the air. The high-pressure air flows through the hot side of the third heat exchanger, is cooled by the heat storage medium, and enters the constant-pressure pneumatic device. The heat storage medium enters the thermal energy storage device. At the same time, the natural gas from the upstream high-pressure pipeline network enters the constant-pressure pneumatic device. The natural gas and air are converted into heat and pressure potential energy in the constant-pressure pneumatic device to ensure that the temperature of the natural gas remains constant during the throttling and pressure reduction process, and the back pressure of the air compressor is constant.

[0017] In the static state of the compressed air energy storage system, when the user side needs to provide heat load or cold load, the thermal fluid in the thermal energy storage device enters the heat-driven energy supply device, and provides external heating or cooling according to the load demand of the user side. The heat storage medium with reduced temperature enters the cold energy storage device for storage through the outlet of the heat-driven energy supply device;

[0018] When renewable energy is insufficient, the power grid is insufficient, or the power generation of the natural gas turbine is insufficient, the high-pressure air in the air storage tank flows through the constant-pressure pneumatic device and enters the cold side of the fourth heat exchanger to absorb heat and increase its temperature, and then enters the air turbine to expand and generate electricity. The heat storage medium in the thermal energy storage device flows through the hot side of the fourth heat exchanger, heats the air, and then flows into the cold energy storage device for storage; at the same time, the natural gas from the upstream high-pressure pipeline network enters the constant-pressure pneumatic device, and the natural gas and air convert heat and pressure potential energy in the constant-pressure pneumatic device to ensure that the temperature of the natural gas remains constant during the throttling and pressure reduction process, and the pressure of the high-pressure air entering the air turbine remains constant.

[0019] Specifically, the upstream fuel-driven compressor unit works. When the renewable energy is sufficient or the grid has surplus power, the air compressor consumes the renewable energy power or surplus power to pressurize the air. The high-pressure air flows through the hot side of the third heat exchanger, and enters the constant-pressure pneumatic device after being cooled by the heat storage medium. The heat storage medium enters the thermal energy storage device for storage. At the same time, the flue gas obtained by the interstage extraction of the turbine of the fuel-driven compressor unit enters the constant-pressure pneumatic device. The flue gas in the constant-pressure pneumatic device transfers the pressure potential energy with the high-pressure air, and the flue gas is discharged into the atmosphere. The flue gas flowing out of the turbine outlet of the fuel-driven compressor unit is used as a driving heat source to realize refrigeration or heating on the user side.

[0020] In the static state of the compressed air energy storage system, when the user side needs to provide heat load or cold load, the thermal fluid in the thermal energy storage device enters the heat-driven energy supply device, and provides external heating or cooling according to the load demand of the user side. The heat storage medium with reduced temperature enters the cold energy storage device for storage through the outlet of the heat-driven energy supply device;

[0021] When renewable energy is insufficient or the power grid is insufficient, the high-pressure air in the air storage tank flows through the constant-pressure pneumatic device and enters the cold side of the fourth heat exchanger to absorb heat and increase temperature, and then enters the air turbine to expand and generate power. The heat storage medium in the thermal energy storage device flows through the hot side of the fourth heat exchanger, heats the air and then flows into the cold energy storage device for storage; at the same time, the high-pressure flue gas extracted from the turbine of the fuel-driven compressor unit enters the constant-pressure pneumatic device, and the flue gas flowing out of the turbine outlet of the fuel-driven compressor unit is used as a driving heat source to achieve refrigeration or heating on the user side.

[0022] Compared with the prior art, the present invention has at least the following beneficial effects:

[0023] The present invention discloses a natural gas station integrated energy system with constant-pressure compressed air energy storage, comprising a natural gas station system, an advanced adiabatic compressed air system and a constant-pressure pneumatic device; corresponding to the upstream natural gas station, comprising a fuel-driven compressor unit system, a constant-pressure pneumatic device and a compressed air energy storage system, the constant-pressure pneumatic device being respectively connected to the turbine of the fuel-driven compressor unit and an air storage tank, the exhaust gas with waste heat from the turbine of the fuel-driven compressor unit being used as a driving heat source for realizing refrigeration or heating on the user side; corresponding to the downstream pressure regulating station, comprising an upstream high-pressure pipeline network, a downstream user pipeline network, a compressed air energy storage system and a constant-pressure pneumatic device, the constant-pressure pneumatic device being arranged on a pipeline between the upstream high-pressure pipeline network and the downstream user pipeline network, the constant-pressure pneumatic device being respectively connected to the air storage tank, a third heat exchanger and a fourth heat exchanger, thereby realizing comprehensive step-by-step utilization of natural gas thermal energy and pressure energy in the natural gas station, and realizing multiple functions of the system such as cooling, heating, electricity and storage on the basis of realizing mutual complementation and coordination of multiple energy sources.

[0024] Furthermore, the constant-pressure pneumatic device includes a first pneumatic device, a second pneumatic device and a third pneumatic device which are arranged in parallel, and floating pistons are respectively arranged in the first pneumatic device, the second pneumatic device and the third pneumatic device; the input ends of the first pneumatic device, the second pneumatic device and the third pneumatic device are respectively connected to the upstream high-pressure pipeline network or the turbine of the fuel-driven compressor unit through corresponding gas valves; the output ends of the first pneumatic device, the second pneumatic device and the third pneumatic device are respectively connected to the downstream user pipeline network or the atmosphere through corresponding air valves; the air outlet ends of the first pneumatic device, the second pneumatic device and the third pneumatic device are respectively connected to the input ends of the air storage tanks through corresponding air valves, and the output ends of the air storage tanks are respectively connected to the air inlet ends of the first pneumatic device, the second pneumatic device and the third pneumatic device through corresponding air valves. The structural design of the floating piston inside the constant-pressure pneumatic device can realize efficient heat exchange between the two working fluids inside the constant-pressure pneumatic device, thereby realizing safe and stable operation of the system.

[0025] Furthermore, circumferential fins are provided on both sides of the floating piston in the constant pressure pneumatic device. When used in upstream natural gas stations, heat exchange between compressed air and high-temperature flue gas can be achieved, thereby improving the working capacity of the compressed air energy storage system. When used in downstream pressure regulating stations, efficient heat exchange between compressed air and natural gas can be achieved, so that the temperature of natural gas can be maintained approximately constant during the throttling and pressure reduction process, thereby achieving safe operation of the natural gas pressure regulation process.

[0026] Furthermore, a natural gas pressure recovery system is installed between the upstream high-pressure pipeline network and the downstream user pipeline network. The natural gas pressure recovery system is installed in parallel with the constant pressure pneumatic device, which can recover the irreversible pressure loss generated by the throttling and pressure reduction process of natural gas and improve the energy utilization rate of the system.

[0027] Furthermore, the natural gas pressure recovery system includes a first valve, one end of which is connected to the upstream high-pressure pipeline network, and the other end is connected to the downstream user pipeline network via the second valve, the cold side of the first heat exchanger, the natural gas turbine and the hot side of the second heat exchanger in sequence. The first valve is connected to the natural gas inlet end of the natural gas turbine via the third valve, and is used for natural gas recovery when the constant pressure pneumatic device is in a static stage, which can avoid the discontinuous operation characteristics of the compressed air energy storage system and realize the continuous recovery of natural gas pressure energy.

[0028] Furthermore, the compressed air energy storage system includes an air compressor, which is connected to an air turbine via the hot side of a third heat exchanger, a constant pressure pneumatic device and a cold side of a fourth heat exchanger in sequence. The cold side of the third heat exchanger is divided into two paths via a thermal energy storage device, one path is connected to the cold side of the third heat exchanger via a heat-driven energy supply device and a cold energy storage device in sequence, and the other path is connected to the cold side of the third heat exchanger via the hot side of the fourth heat exchanger and the cold energy storage device. This not only recovers the compression heat generated by the compressed air energy storage system during the energy storage process, but also is used to preheat the high-pressure air from the air storage tank during the energy release process, thereby increasing the output power of the system. The use of fossil fuels is avoided. A sixth valve is provided between the air compressor and the third heat exchanger, a seventh valve is provided between the fourth heat exchanger and the air turbine, a first heat storage medium valve is provided between the thermal energy storage device and the heat-driven energy supply device, and a second heat storage medium valve is provided between the heat-driven energy supply device and the cold energy storage device. This ensures that during the static process of compressed air energy storage, the present invention can still realize flexible supply of heating and cooling to the user side according to the cold and hot energy loads on the user side. In addition, by providing a constant pressure pneumatic device, it is ensured that the compressed air energy storage system is always operating in the designed working condition.

[0029] Furthermore, the turbine of the fuel-driven compressor unit is coaxially connected with the fuel-driven compressor unit compressor and the natural gas compressor. The compressor of the fuel-driven compressor unit is connected to the turbine of the fuel-driven compressor unit via the combustion chamber of the fuel-driven compressor unit, which can not only realize the continuous pressurization process of natural gas, but also realize the flexible supply of surplus energy (including pressure potential energy and thermal energy) of the turbine of the fuel-driven compressor unit according to actual production conditions.

[0030] Furthermore, the interstage exhaust outlet of the turbine of the fuel-driven compressor unit is connected to the gas inlet of the constant-pressure pneumatic device through the exhaust valve of the turbine of the fuel-driven compressor unit, and the gas outlet of the constant-pressure pneumatic device is connected to the atmospheric environment, so that the compressed air energy storage system can operate efficiently under the designed working conditions, that is, the back pressure of the air compressor unit and the inlet pressure of the air turbine unit are always in a constant state.

[0031] Furthermore, the downstream pressure regulating station works. When renewable energy is sufficient or the grid has surplus electricity, the air compressor consumes renewable energy electricity or surplus electricity to pressurize the air. The high-pressure air flows through the hot side of the third heat exchanger, is cooled by the heat storage medium, and then enters the constant-pressure pneumatic device. The heat storage medium enters the thermal energy storage device. At the same time, the natural gas from the upstream high-pressure pipeline network enters the constant-pressure pneumatic device. The natural gas and air exchange heat in the constant-pressure pneumatic device. When the user side needs to provide heat load or cold load, the hot fluid in the thermal energy storage device enters the heat-driven energy supply device, and supplies heat or cooling to the outside according to the load demand of the user side. After the temperature is lowered, The heat storage medium enters the cold energy storage device from the outlet of the heat-driven energy supply device for storage; when there is insufficient renewable energy, insufficient power in the grid, or insufficient power generation of the natural gas turbine, the high-pressure air in the air storage tank flows through the constant-pressure pneumatic device and enters the cold side of the fourth heat exchanger to absorb heat and heat up, and then enters the air turbine to expand and generate power, and the heat storage medium in the thermal energy storage device flows through the hot side of the fourth heat exchanger, heats the air, and then flows into the cold energy storage device for storage; at the same time, the natural gas from the upstream high-pressure pipeline network enters the constant-pressure pneumatic device, and the natural gas and air exchange heat in the constant-pressure pneumatic device to ensure that the temperature of the natural gas remains approximately constant during the throttling and pressure reduction process. Not only does it achieve the process goal of natural gas throttling and pressure reduction, but it also ensures that the temperature of the natural gas remains approximately constant during the throttling and pressure reduction process. In addition, it can also achieve important energy storage functions and flexible energy supply goals.

[0032] Furthermore, the upstream fuel-driven compressor unit is working. When renewable energy is sufficient or the power grid has surplus electricity, the air compressor consumes renewable energy electricity or surplus electricity to pressurize the air. The high-pressure air flows through the hot side of the third heat exchanger, is cooled by the heat storage medium, and enters the constant-pressure pneumatic device to further increase the pressure. The heat storage medium enters the thermal energy storage device for storage. At the same time, the interstage air extraction of the turbine of the fuel-driven compressor unit enters the constant-pressure pneumatic device. The air in the constant-pressure pneumatic device is divided into flue gas and air. The flue gas is extracted from the high-pressure air through the turbine of the fuel-driven compressor unit and discharged into the atmosphere. The flue gas flowing out of the turbine outlet of the fuel-driven compressor unit is used as a driving heat source to realize refrigeration or heating on the user side. When the user side needs to provide heat load or cold load, the hot fluid in the thermal energy storage device enters the heat-driven energy supply device, and supplies heat or cooling to the outside according to the load demand on the user side, and the temperature drops. The heat storage medium after cooling enters the cold energy storage device through the outlet of the heat-driven energy supply device for storage; when renewable energy is insufficient or the power grid is insufficient, the high-pressure air in the air storage tank flows through the constant-pressure pneumatic device and enters the cold side of the fourth heat exchanger to absorb heat and heat up, and then enters the air turbine to expand and generate power, and the heat storage medium in the heat energy storage device flows through the hot side of the fourth heat exchanger, heats the air and then flows into the cold energy storage device for storage; at the same time, the high-pressure air of the turbine of the fuel-driven compressor unit is extracted and enters the constant-pressure pneumatic device, and the flue gas flowing out of the turbine outlet of the fuel-driven compressor unit is used as the driving heat source to realize cooling or heating on the user side; when the user side needs to provide heat load or cold load, the hot fluid in the heat energy storage device enters the heat-driven energy supply device, and heat or cools the outside according to the load demand on the user side, and the heat storage medium after the temperature is reduced enters the cold energy storage device for storage from the outlet of the heat-driven energy supply device. It can not only realize the efficient cascade utilization of the waste heat of the turbine of the fuel-driven compressor unit, but also realize the flexible energy supply of the system, thereby improving the overall operation efficiency of the system.

[0033] In summary, the present invention, by making full use of the pressure potential energy of natural gas, can not only be used to solve the technical problem of frequent changes in operating conditions of compressor units and turbine units in compressed air energy storage technology, but also realizes efficient utilization and flexible energy supply of natural gas energy in natural gas stations, avoids the temperature drop problem caused by natural gas throttling and pressure reduction in existing downstream pressure regulating stations, improves the energy utilization efficiency and economic benefits of natural gas stations, and ensures the safe and stable operation of natural gas stations.

[0034] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A schematic diagram of a system integrating natural gas pipeline pressure energy recovery and compressed air energy storage according to the present invention;

[0036] Figure 2This is a schematic diagram of a system integrating waste heat recovery of a fuel-driven compressor unit and compressed air energy storage according to the present invention;

[0037] Figure 3 This is a working diagram of the constant pressure pneumatic device of the present invention;

[0038] Figure 4 A three-dimensional diagram of a floating piston in a constant pressure pneumatic device of the present invention;

[0039] Figure 5 It is a two-dimensional diagram of the floating piston in the constant pressure pneumatic device of the present invention.

[0040] Among them: 1. Upstream high-pressure pipeline network; 2. Downstream user pipeline network; 3. First heat exchanger; 4. Natural gas turbine; 5. Second heat exchanger; 6. Constant pressure pneumatic device; 7. Air compressor; 8. Third heat exchanger; 9. Air storage tank; 10. Fourth heat exchanger; 11. Air turbine; 12. Cold energy storage device; 13. Heat energy storage device; 14. First valve; 15. Second valve; 16. Third valve; 17. Fourth valve; 18. Fifth valve; 19. Sixth valve; 20. Seventh valve; 21. First gas valve; 22. Second gas valve; 23. Third gas valve; 24. Fourth gas valve; 25. Fifth gas valve; 26. Sixth gas valve; 28. first pneumatic device; 29. ​​second pneumatic device; 30. third pneumatic device; 31. first floating piston; 32. second floating piston; 33. third floating piston; 34. first air valve; 35. second air valve; 36. third air valve; 37. fourth air valve; 38. fifth air valve; 39. sixth air valve; 40. heat-driven energy supply device; 41. first heat storage medium valve; 42. second heat storage medium valve; 43. compressor of fuel-driven compressor unit; 44. combustion chamber of fuel-driven compressor unit; 45. turbine of fuel-driven compressor unit; 46. natural gas compressor; 47. exhaust valve of turbine of fuel-driven compressor unit. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions 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. 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.

[0042] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "one side", "one end", "one side" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying 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 limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0043] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" 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 communication 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.

[0044] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0045] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0046] It should be further understood that the term "and / or" used in the present description and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0047] Various structural schematic diagrams of the embodiments disclosed in the present invention are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0048] The present invention provides a natural gas station comprehensive energy system with integrated constant-pressure compressed air energy storage, which can be used in the upstream pressurization or downstream pressure reduction process of the natural gas station, and can be used for heat storage, power generation, refrigeration and heating by recovering the pressure energy and thermal energy of the natural gas station, thereby improving the energy utilization efficiency and economic benefits of the natural gas station; storing renewable energy and surplus power of the power grid during the energy storage process, and releasing electric energy during the energy release process, thereby improving the penetration rate of renewable energy in the power grid; in the operation process of the adiabatic compressed air energy storage technology, by setting a constant-pressure pneumatic device, not only the efficient utilization of the natural gas pressure in the natural gas pipeline is achieved, but also the natural gas is fully heat exchanged with the air, thereby avoiding the temperature reduction problem caused by the existing natural gas throttling and pressure reduction. In addition, by making full use of the pressure potential energy of natural gas, the compressor unit and turbine unit in the compressed air energy storage technology always operate efficiently under the designed conditions.

[0049] The present invention discloses a natural gas station integrated energy system with integrated constant-pressure compressed air energy storage, comprising a compressed air energy storage system, a natural gas pressure recovery system and a constant-pressure pneumatic device 6. The compressed air energy storage system is connected to the natural gas pressure recovery system via the constant-pressure pneumatic device 6, and the constant-pressure pneumatic device 6 and the natural gas pressure recovery system are respectively connected to an upstream high-pressure pipeline network 1 and a downstream user pipeline network 2; renewable energy and surplus power of the power grid are stored during the energy storage process, and electric energy is released during the energy release process; during the operation of the compressed air energy storage system, heat exchange between natural gas and air is performed through the constant-pressure pneumatic device.

[0050] The compressed air energy storage system includes an air compressor 7, an air storage tank 9, an air turbine 11 and a thermal energy storage device 13, the air compressor 7, the output end of the air compressor 7 is connected to the high-pressure air inlet end of the air turbine 11 through the sixth valve 19, the hot side of the third heat exchanger 8, the constant pressure pneumatic device 6, the cold side of the fourth heat exchanger 10 and the seventh valve 20 in sequence, the air outlet end of the constant pressure pneumatic device 6 is connected to the air inlet end of the air storage tank 9, and the air inlet end of the constant pressure pneumatic device 6 is connected to the air outlet end of the air storage tank 9; the heat storage outlet energy storage end of the thermal energy storage device 13 is connected to the heat storage inlet end of the thermal energy storage device 13 through the hot side of the fourth heat exchanger 10, the cold energy storage device 12 and the cold side of the third heat exchanger 8 in sequence; the heat storage outlet joint supply end of the thermal energy storage device 13 is connected to the cold storage inlet joint supply end of the cold energy storage device 12 through the first heat storage working medium valve 41, the heat-driven energy supply device 40 and the second heat storage working medium valve 42 in sequence.

[0051] See also Figure 1 When applied to a downstream pressure regulating station, the input end of the constant pressure pneumatic device 6 is connected to the upstream high pressure pipeline 1 through the fourth valve 17, and the output end of the constant pressure pneumatic device 6 is connected to the downstream user pipeline 2 through the fifth valve 18.

[0052] See also Figure 2 When applied to the upstream fuel-driven compressor unit, the input end of the constant pressure pneumatic device 6 is connected to the interstage exhaust outlet end of the turbine 45 of the fuel-driven compressor unit through the turbine exhaust valve 47 of the fuel-driven compressor unit, the turbine 45 of the fuel-driven compressor unit is coaxially connected with the compressor 43 of the fuel-driven compressor unit, the compressor 43 of the fuel-driven compressor unit is connected to the flue gas inlet end of the turbine 45 of the fuel-driven compressor unit through the combustion chamber 44 of the fuel-driven compressor unit, and the turbine 45 of the fuel-driven compressor unit is coaxially connected with the natural gas compressor 46.

[0053] The natural gas pressure recovery system includes a first valve 14, one end of which is connected to the upstream high-pressure pipeline 1, and the other end is connected to the downstream user pipeline 2 via the second valve 15, the cold side of the first heat exchanger 3, the natural gas turbine 4 and the hot side of the second heat exchanger 5 in sequence. The first valve 14 is connected to the natural gas inlet end of the natural gas turbine 4 via the third valve 16, and is used for natural gas recovery when the constant pressure pneumatic device 6 is in a static stage.

[0054] See also Figure 3The constant pressure pneumatic device 6 includes a first pneumatic device 28, a second pneumatic device 29 and a third pneumatic device 30 which are arranged in parallel. A first floating piston 31 is arranged in the first pneumatic device 28, a second floating piston 32 is arranged in the second pneumatic device 29, and a third floating piston 33 is arranged in the third pneumatic device 30; the input end of the first pneumatic device 28 is connected to the first gas valve 21, the input end of the second pneumatic device 29 is connected to the second gas valve 22, and the input end of the third pneumatic device 30 is connected to the third gas valve 23, and is connected to the upstream high-pressure pipeline 1 or the turbine 45 of the fuel-driven compressor unit through the first gas valve 21, the second gas valve 22 and the third gas valve 23; the output end of the first pneumatic device 28 is connected to the first air valve 34, the output end of the second pneumatic device 29 is connected to the second air valve 35, and the output end of the third pneumatic device 30 is connected to the third air valve 36, and is connected to the downstream user pipeline 2 or the atmosphere through the first air valve 34, the second air valve 35 and the third air valve 36.

[0055] The air outlet ends of the first pneumatic device 28, the second pneumatic device 29 and the third pneumatic device 30 are connected to the input end of the air storage tank 9 via the first air valve 34, the second air valve 35 and the third air valve 36 respectively, and the output end of the air storage tank 9 is connected to the air inlet ends of the first pneumatic device 28, the second pneumatic device 29 and the third pneumatic device 30 via the fourth air valve 37, the fifth air valve 38 and the sixth air valve 39 respectively.

[0056] Applied to upstream natural gas stations, the smoke inlet ends of the first pneumatic device 28, the second pneumatic device 29 and the third pneumatic device 30 are connected to the output end of the turbine exhaust valve 47 of the fuel-driven compressor unit through the first smoke valve 21, the second smoke valve 22 and the third smoke valve 33 respectively, and the smoke outlet ends of the first pneumatic device 28, the second pneumatic device 29 and the third pneumatic device 30 are connected to the atmospheric environment through the fourth smoke valve 24, the fifth smoke valve 25 and the sixth smoke valve 36 respectively.

[0057] Applied to the downstream pressure regulating station, the smoke inlet ends of the first pneumatic device 28, the second pneumatic device 29 and the third pneumatic device 30 are connected to the output end of the upstream high-pressure pipe network 1 through the first smoke gas valve 21, the second smoke gas valve 22 and the third smoke gas valve 33 respectively, and the smoke outlet ends of the first pneumatic device 28, the second pneumatic device 29 and the third pneumatic device 30 are connected to the input end of the downstream user pipe network 2 through the fourth smoke gas valve 24, the fifth smoke gas valve 25 and the sixth smoke gas valve 36 respectively.

[0058] See also Figure 4Compared with the existing flat piston structure, the floating piston structure can improve the heat exchange between air and flue gas (applied to upstream natural gas stations) or natural gas (applied to downstream pressure regulating stations) by adding circumferential fins. In the process of flue gas / natural gas / compressed air entering the constant pressure pneumatic device, gas swirl phenomenon will inevitably occur. By adding circumferential fins, the stable flow of gas in the cavity of the constant pressure pneumatic device can be achieved, the flow loss of gas can be reduced, and the energy utilization efficiency of the system can be improved. Please refer to Figure 5 The existing flat structure piston has two main purposes. One is for pressurization, and the other is for separating the two working media in the piston cavity. The floating piston structure in the present invention can realize the function of the existing piston structure on the one hand, and on the other hand, in the two application scenarios of upstream natural gas stations and downstream pressure regulating stations, it can realize the heat exchange between compressed air and flue gas / natural gas, thereby realizing stable and efficient operation of the system.

[0059] The working process of the integrated energy system of a natural gas station with integrated constant pressure compressed air energy storage in the present invention applied to a downstream pressure regulating station is as follows:

[0060] See also Figure 1 , when the compressed air energy storage system is specifically divided into energy storage stage, energy release stage and static stage, a total of three stages, as follows:

[0061] A. Energy storage stage

[0062] When renewable energy is sufficient or there is surplus electricity in the power grid or there is surplus power generated by the natural gas turbine 4, the compressed air energy storage system is in the energy storage stage, and the air compressor 7 consumes renewable energy electricity or surplus electricity to pressurize the air. The high-pressure air flows through the hot side of the third heat exchanger 8, and enters the constant-pressure pneumatic device 6 after being cooled by the heat storage medium. The heat storage medium enters the thermal energy storage device 13 for storage. At the same time, another natural gas from the upstream high-pressure pipeline 1 enters the constant-pressure pneumatic device 6 after passing through the valve 17.

[0063] During the energy storage process, the working process of the constant pressure pneumatic device when it is started is as follows:

[0064] 1. The air flowing out of the third heat exchanger 8 enters the first pneumatic device 28 through the air valve 37 until the air pressure is equal to the device pressure; during this process, all other valves in the constant pressure pneumatic device 6 are closed.

[0065] 2. High-pressure natural gas from the upstream high-pressure pipeline 1 enters the first pneumatic device 28 through the valve 21, and the air in the first pneumatic device 28 is pushed into the air storage tank 9 through the air valve 34 by the floating piston 31; at the same time, the air flowing out of the third heat exchanger 8 enters the second pneumatic device 29 through the air valve 38 until the air pressure is equal to the device pressure; during this process, all other valves in the constant pressure pneumatic device 6 are closed.

[0066] 3. The natural gas in the first pneumatic device 28 enters the downstream user pipeline through the natural valve 24; at the same time, the high-pressure natural gas from the upstream high-pressure pipeline network 1 enters the second pneumatic device 29 through the valve 22, and the air in the second pneumatic device 29 is pushed to the air storage tank 9 through the air valve 35 by the floating piston 32; at the same time, the air flowing out of the third heat exchanger 8 enters the third pneumatic device 28 through the air valve 39 until the air pressure is equal to the device pressure; in this process, all other valves in the constant pressure pneumatic device 6 are closed.

[0067] 4. The air flowing out of the third heat exchanger 8 enters the first pneumatic device 28 through the air valve 37, and the remaining natural gas in the first pneumatic device 28 is further pushed to the downstream user pipeline 2 through the gas valve 24 by the floating piston 31; at the same time, the natural gas in the second pneumatic device 29 enters the downstream user pipeline through the natural valve 25; at the same time, the high-pressure natural gas from the upstream high-pressure pipeline 1 enters the third pneumatic device 30 through the valve 23, and the air in the third pneumatic device 30 is pushed to the air storage tank 9 through the air valve 36 by the floating piston 33; in this process, all other valves in the constant pressure pneumatic device 6 are closed.

[0068] 5. The high-pressure natural gas from the upstream high-pressure pipeline network 1 enters the first pneumatic device 28 through the valve 21, and the air in the first pneumatic device 28 is pushed to the air storage tank 9 through the air valve 34 by the floating piston 31; at the same time, the air flowing out of the third heat exchanger 8 enters the second pneumatic device 29 through the air valve 38, and the remaining natural gas in the second pneumatic device 29 is further pushed to the downstream user pipeline network 2 through the gas valve 25 by the floating piston 32; at the same time, the natural gas in the third pneumatic device 30 enters the downstream user pipeline through the natural valve 26; in this process, all other valves in the constant pressure pneumatic device 6 are closed.

[0069] 6. The natural gas in the first pneumatic device 28 enters the downstream user pipeline through the natural valve 24; at the same time, the high-pressure natural gas from the upstream high-pressure pipeline network 1 enters the second pneumatic device 29 through the valve 22, and the air in the second pneumatic device 29 is pushed to the air storage tank 9 through the air valve 35 by the floating piston 32; at the same time, the air flowing out of the third heat exchanger 8 enters the third pneumatic device 30 through the air valve 39, and the remaining natural gas in the third pneumatic device 30 is further pushed to the downstream user pipeline network 2 through the gas valve 26 by the floating piston 33; in this process, all other valves in the constant pressure pneumatic device 6 are closed.

[0070] Afterwards, the constant pressure pneumatic device 6 in the energy storage process works repeatedly according to the above process.

[0071] If the user side needs to provide heat load or cold load, the hot fluid in the thermal energy storage device 13 enters the heat-driven energy supply device 40 through the heat storage medium valve 41, and supplies heat or cooling to the outside according to the load demand of the user side. The heat storage medium with reduced temperature enters the cold energy storage device 12 for storage from the outlet of the heat-driven energy supply device 40 through the heat storage medium valve 42.

[0072] B. Energy release stage

[0073] When renewable energy is insufficient, the power grid is insufficient, or the power generation of the natural gas turbine 4 is insufficient, the high-pressure air in the air storage tank 9 flows through the constant-pressure pneumatic device 6 and enters the cold side of the fourth heat exchanger 10 to absorb heat and increase the temperature, and then enters the turbine to expand and generate electricity. At this time, the heat storage medium in the thermal energy storage device 13 flows through the hot side of the fourth heat exchanger 10, heats the air, and then flows into the cold energy storage device 12 for storage; at the same time, another natural gas from the upstream high-pressure pipeline 1 enters the constant-pressure pneumatic device 6 after passing through the valve 17.

[0074] During the energy release process, the working process of the constant pressure pneumatic device when it is started is as follows:

[0075] 1. The air flowing out of the air storage tank 9 enters the first pneumatic device 28 through the air valve 37 until the air pressure is equal to the device pressure; during this process, all other valves in the constant pressure pneumatic device 6 are closed.

[0076] 2. High-pressure natural gas from the upstream high-pressure pipeline network 1 enters the first pneumatic device 28 through the valve 21, and the air in the first pneumatic device 28 is pushed to the fourth heat exchanger 10 through the air valve 34 by the floating piston 31; at the same time, the air flowing out of the air storage tank 9 enters the second pneumatic device 29 through the air valve 38 until the air pressure is equal to the device pressure; during this process, all other valves in the constant pressure pneumatic device 6 are closed.

[0077] 3. The natural gas in the first pneumatic device 28 enters the downstream user pipeline through the natural valve 24; at the same time, the high-pressure natural gas from the upstream high-pressure pipeline network 1 enters the second pneumatic device 29 through the valve 22, and the air in the second pneumatic device 29 is pushed to the fourth heat exchanger 10 through the air valve 35 by the floating piston 32; at the same time, the air flowing out of the air storage tank 9 enters the third pneumatic device 28 through the air valve 39 until the air pressure is equal to the device pressure; in this process, all other valves in the constant pressure pneumatic device 6 are closed.

[0078] 4. The air flowing out of the air storage tank 9 enters the first pneumatic device 28 through the air valve 37, and the remaining natural gas in the first pneumatic device 28 is further pushed to the downstream user pipeline 2 through the gas valve 24 by the floating piston 31; at the same time, the natural gas in the second pneumatic device 29 enters the downstream user pipeline through the natural valve 25; at the same time, the high-pressure natural gas from the upstream high-pressure pipeline 1 enters the third pneumatic device 30 through the valve 23, and the air in the third pneumatic device 30 is pushed to the fourth heat exchanger 10 through the air valve 36 by the floating piston 33; in this process, all other valves in the constant pressure pneumatic device 6 are closed.

[0079] 5. The high-pressure natural gas from the upstream high-pressure pipeline network 1 enters the first pneumatic device 28 through the valve 21, and the air in the first pneumatic device 28 is pushed to the fourth heat exchanger 10 through the air valve 34 by the floating piston 31; at the same time, the air flowing out of the air storage tank 9 enters the second pneumatic device 29 through the air valve 38, and the remaining natural gas in the second pneumatic device 29 is further pushed to the downstream user pipeline network 2 through the gas valve 25 by the floating piston 32; at the same time, the natural gas in the third pneumatic device 30 enters the downstream user pipeline through the natural valve 26; in this process, all other valves in the constant pressure pneumatic device 6 are closed.

[0080] 6. The natural gas in the first pneumatic device 28 enters the downstream user pipeline through the natural valve 24; at the same time, the high-pressure natural gas from the upstream high-pressure pipeline network 1 enters the second pneumatic device 29 through the valve 22, and the air in the second pneumatic device 29 is pushed to the fourth heat exchanger 10 through the air valve 35 by the floating piston 32; at the same time, the air flowing out of the air storage tank 9 enters the third pneumatic device 30 through the air valve 39, and the remaining natural gas in the third pneumatic device 30 is further pushed to the downstream user pipeline network 2 through the gas valve 26 by the floating piston 33; in this process, all other valves in the constant pressure pneumatic device 6 are closed.

[0081] Afterwards, the constant pressure pneumatic device 6 in the energy release process works repeatedly according to the above process.

[0082] If the user side needs to provide heat load or cold load, the hot fluid in the thermal energy storage device 13 enters the heat-driven energy supply device 40 through the heat storage medium valve 41, and provides external heating or cooling according to the load demand on the user side. The heat storage medium with reduced temperature enters the cold energy storage device 12 for storage from the outlet of the heat-driven energy supply device 40 through the heat storage medium valve 42.

[0083] C. Static stage

[0084] When the compressed air energy storage system is in the static stage, when the natural gas pressure regulating station needs to supply heat to the outside, the natural gas from the upstream high-pressure pipeline 1 flows through valves 14 and valves 15, enters the first heat exchanger 3 to absorb heat from the heat source, and then enters the natural gas turbine 4 to expand and generate electricity. The reduced-pressure natural gas flows through the second heat exchanger 5 to heat the outside, and finally enters the downstream user pipeline 2 for users to use; when the natural gas pressure regulating station needs to cool the outside, the natural gas from the upstream high-pressure pipeline 1 flows through valves 14 and valves 16, and directly enters the natural gas turbine 4 to expand and generate electricity. The reduced-pressure and cooled natural gas flows through the second heat exchanger 5 to cool the outside, and finally enters the downstream user pipeline 2 for users to use.

[0085] The working process of the integrated energy system of a natural gas station with integrated constant pressure compressed air energy storage in the present invention applied to an upstream fuel-driven compressor unit is as follows:

[0086] See also Figure 2 The compressed air energy storage system is specifically divided into three stages: energy storage stage, energy release stage and static stage, as follows:

[0087] A. Energy storage stage

[0088] When there is sufficient renewable energy or the grid has surplus electricity or the power generation of the natural gas turbine 4 is surplus, the compressed air energy storage system is in the energy storage stage, and the air compressor 7 consumes renewable energy electricity or surplus electricity to pressurize the air, and the high-pressure air flows through the hot side of the third heat exchanger 8, and enters the constant pressure pneumatic device 6 after being cooled by the heat storage medium, and the heat storage medium enters the thermal energy storage device 13 for storage. At the same time, another natural gas from the upstream high-pressure pipeline 1 enters the constant pressure pneumatic device 6 after passing through the valve 17. The air in the constant pressure pneumatic device 6 is divided into flue gas and air, where flue gas is defined as being extracted from high-pressure air through the turbine 45 of the fuel-driven compressor unit and discharged into the atmosphere, and the working medium in the compressed air energy storage system is defined as air. The flue gas flowing out of the outlet of the turbine 45 of the fuel-driven compressor unit can be used as a driving heat source according to the needs of the user side to achieve refrigeration or heating on the user side.

[0089] During the energy storage process, the working process of the constant pressure pneumatic device when it is started is as follows:

[0090] 1. The high-pressure air flowing out of the turbine 45 of the fuel-driven compressor unit enters the first pneumatic device 28 through the turbine 45 of the fuel-driven compressor unit until the air pressure is equal to the device pressure; during this process, all other valves in the constant pressure pneumatic device 6 are closed.

[0091] 2. The high-pressure flue gas from the turbine 45 of the fuel-driven compressor unit enters the first pneumatic device 28 through the valve 21, and the air in the first pneumatic device 28 is pushed to the air storage tank 9 through the air valve 34 by the floating piston 31; at the same time, the air flowing out of the third heat exchanger 8 enters the second pneumatic device 29 through the air valve 38 until the air pressure is equal to the device pressure; in this process, all other valves in the constant pressure pneumatic device 6 are closed.

[0092] 3. The flue gas in the first pneumatic device 28 enters the atmospheric environment through the gas valve 24; at the same time, the high-pressure flue gas from the stages of the turbine 45 of the fuel-driven compressor unit enters the second pneumatic device 29 through the second gas valve 22, and the air in the second pneumatic device 29 is pushed to the air storage tank 9 through the air valve 35 by the floating piston 32; at the same time, the high-pressure flue gas extracted from the turbine 45 of the fuel-driven compressor unit enters the third pneumatic device 28 through the first gas valve 21 until the air pressure is equal to the device pressure; during this process, all other valves in the constant pressure pneumatic device 6 are closed.

[0093] 4. The high-pressure air extracted from the turbine 45 of the fuel-driven compressor unit enters the first pneumatic device 28 through the air valve 37, and the flue gas in the first pneumatic device 28 is further pushed to the atmosphere through the gas valve 24 by the floating piston 31; at the same time, the flue gas in the second pneumatic device 29 enters the atmosphere through the gas valve 25; at the same time, the high-pressure air from the turbine 45 of the fuel-driven compressor unit enters the third pneumatic device 30 through the valve 23, and the air in the third pneumatic device 30 is pushed to the air storage tank 9 through the air valve 36 by the floating piston 33; during this process, all other valves in the constant pressure pneumatic device 6 are closed.

[0094] 5. The high-pressure air from the turbine 45 of the fuel-driven compressor unit enters the first pneumatic device 28 through the valve 21, and the air in the first pneumatic device 28 is pushed to the air storage tank 9 through the air valve 34 by the floating piston 31; at the same time, the air extracted from the turbine 45 of the fuel-driven compressor unit enters the second pneumatic device 29 through the air valve 38, and the flue gas in the second pneumatic device 29 is further pushed to the atmosphere through the gas valve 25 by the floating piston 32; at the same time, the air in the third pneumatic device 30 enters the downstream user pipeline through the gas valve 26; in this process, all other valves in the constant pressure pneumatic device 6 are closed.

[0095] 6. The air in the first pneumatic device 28 enters the downstream user pipeline through the gas valve 24; at the same time, the high-pressure air from the turbine 45 of the fuel-driven compressor unit enters the second pneumatic device 29 through the valve 22, and the air in the second pneumatic device 29 is pushed to the air storage tank 9 through the air valve 35 by the floating piston 32; at the same time, the air flowing out of the third heat exchanger 8 enters the third pneumatic device 30 through the air valve 39, and the flue gas in the third pneumatic device 30 is further pushed to the atmospheric environment through the gas valve 26 by the floating piston 33; in this process, all other valves in the constant pressure pneumatic device 6 are closed.

[0096] Afterwards, the constant pressure pneumatic device 6 in the energy storage process works repeatedly according to the above process.

[0097] If the user side needs to provide heat load or cold load, the hot fluid in the thermal energy storage device 13 enters the heat-driven energy supply device 40 through the heat storage medium valve 41, and provides external heating or cooling according to the load demand on the user side. The heat storage medium with reduced temperature enters the cold energy storage device 12 for storage from the outlet of the heat-driven energy supply device 40 through the heat storage medium valve 42.

[0098] B. Energy release stage

[0099] When renewable energy is insufficient, the power grid is insufficient, or the power generation of the natural gas turbine 4 is insufficient, the high-pressure air in the air storage tank 9 flows through the constant-pressure pneumatic device 6 and enters the cold side of the fourth heat exchanger 10 to absorb heat and heat up, and then enters the turbine to expand and generate power. At this time, the heat storage medium in the thermal energy storage device 13 flows through the hot side of the fourth heat exchanger 10, heats the air, and then flows into the cold energy storage device 12 for storage; at the same time, the high-pressure air drawn from the turbine 45 of the fuel-driven compressor unit enters the constant-pressure pneumatic device 6 through the valve 17. The flue gas flowing out of the outlet of the turbine 45 of the fuel-driven compressor unit can be used as a driving heat source according to the needs of the user side to achieve refrigeration or heating on the user side.

[0100] During the energy release process, the working process of the constant pressure pneumatic device when it is started is as follows:

[0101] 1. The air flowing out of the air storage tank 9 enters the first pneumatic device 28 through the air valve 37 until the air pressure is equal to the device pressure; during this process, all other valves in the constant pressure pneumatic device 6 are closed.

[0102] 2. The high-pressure air from the turbine 45 of the fuel-driven compressor unit enters the first pneumatic device 28 through the valve 21, and the air in the first pneumatic device 28 is pushed to the fourth heat exchanger 10 through the air valve 34 by the floating piston 31; at the same time, the air flowing out of the air storage tank 9 enters the second pneumatic device 29 through the air valve 38 until the air pressure is equal to the device pressure; during this process, all other valves in the constant pressure pneumatic device 6 are closed.

[0103] 3. The flue gas in the first pneumatic device 28 enters the atmosphere through the gas valve 24; at the same time, the high-pressure air from the turbine 45 of the fuel-driven compressor unit enters the second pneumatic device 29 through the valve 22, and the air in the second pneumatic device 29 is pushed to the fourth heat exchanger 10 through the air valve 35 by the floating piston 32; at the same time, the air flowing out of the air storage tank 9 enters the third pneumatic device 28 through the air valve 39 until the air pressure is equal to the device pressure; during this process, all other valves in the constant pressure pneumatic device 6 are closed.

[0104] 4. The air flowing out of the air storage tank 9 enters the first pneumatic device 28 through the air valve 37, and the flue gas in the first pneumatic device 28 is further pushed into the atmosphere through the gas valve 24 by the floating piston 31; at the same time, the flue gas in the second pneumatic device 29 enters the atmosphere through the gas valve 25; at the same time, the high-pressure air from the turbine 45 of the fuel-driven compressor unit enters the third pneumatic device 30 through the valve 23, and the air in the third pneumatic device 30 is pushed into the fourth heat exchanger 10 through the air valve 36 by the floating piston 33; during this process, all other valves in the constant pressure pneumatic device 6 are closed.

[0105] 5. The high-pressure air from the turbine 45 of the fuel-driven compressor unit enters the first pneumatic device 28 through the valve 21, and the air in the first pneumatic device 28 is pushed to the fourth heat exchanger 10 through the air valve 34 by the floating piston 31; at the same time, the air flowing out of the air storage tank 9 enters the second pneumatic device 29 through the air valve 38, and the flue gas in the second pneumatic device 29 is further pushed to the atmosphere through the gas valve 25 by the floating piston 32; at the same time, the flue gas in the third pneumatic device 30 enters the atmosphere through the gas valve 26; in this process, all other valves in the constant pressure pneumatic device 6 are closed.

[0106] 6. The flue gas in the first pneumatic device 28 enters the atmosphere through the gas valve 24; at the same time, the high-pressure air from the turbine 45 of the fuel-driven compressor unit enters the second pneumatic device 29 through the valve 22, and the air in the second pneumatic device 29 is pushed to the fourth heat exchanger 10 through the air valve 35 by the floating piston 32; at the same time, the air flowing out of the air storage tank 9 enters the third pneumatic device 30 through the air valve 39, and the remaining flue gas in the third pneumatic device 30 is further pushed to the atmosphere through the gas valve 26 by the floating piston 33; during this process, all other valves in the constant pressure pneumatic device 6 are closed.

[0107] Afterwards, the constant pressure pneumatic device 6 in the energy release process works repeatedly according to the above process.

[0108] If the user side needs to provide heat load or cold load, the hot fluid in the thermal energy storage device 13 enters the heat-driven energy supply device 40 through the heat storage medium valve 41, and provides external heating or cooling according to the load demand on the user side. The heat storage medium with reduced temperature enters the cold energy storage device 12 for storage from the outlet of the heat-driven energy supply device 40 through the heat storage medium valve 42.

[0109] The heat source in the thermal energy storage device 13 can be composed of two parts. One part comes from the compression heat generated in the energy storage process, that is, the high-pressure air flowing out of the air compressor 7 enters the hot side of the third heat exchanger 8, and the heat in the high-pressure air is stored in the thermal energy storage device 13; the other part comes from the outlet of the turbine of the fuel-driven compressor unit, enters the thermal energy storage device for storage, and is used to increase the temperature of the air entering the inlet of the air turbine 11.

[0110] C. Static stage

[0111] When the compressed air energy storage system is in a static stage, the flue gas flowing out of the outlet of the turbine 45 of the fuel-driven compressor unit can be used as a driving heat source according to the needs of the user side to achieve cooling or heating on the user side.

[0112] Taking the operation process of traditional compressed air energy storage as an example, the pressure drop caused by the change of compressor back pressure during energy storage and throttling during energy release is Losses account for the compressed air energy storage system The loss is 18.85%. It can be seen that the present invention can greatly improve the operating efficiency of the compressed air energy storage system by setting a constant pressure pneumatic device and coupling the recovery of the pressure potential energy of the natural gas station.

[0113] The present invention is applied to the upstream natural gas station, the constant pressure pneumatic device is respectively connected to the air storage tank, the fuel-driven compressor unit turbine and the compressed air energy storage system, the constant pressure pneumatic device recovers the flue gas energy of the fuel-driven compressor unit turbine, and maintains the compressed air energy storage system to always operate efficiently under the designed working conditions, and the fuel-driven compressor unit turbine is used as a driving heat source to realize refrigeration or heating on the user side; applied to the downstream pressure regulating station, a constant pressure pneumatic device is set between the upstream high-pressure pipeline network and the downstream user pipeline network, and the pressure potential energy of the natural gas in the upstream and downstream natural gas pipeline networks is recovered by the constant pressure pneumatic device to maintain the constant pressure energy storage and energy release operation of the compressed air energy storage system, and the heat exchange between the natural gas and the air occurs in the constant pressure pneumatic device, which can maintain the natural gas in the throttling and pressure reduction process. The present invention can be used to solve the technical problem of the frequent change of working conditions of the compressor unit and the turbine unit in the compressed air energy storage technology by making full use of the natural gas energy (including pressure potential energy and thermal energy) in the natural gas station, and realize the efficient utilization and flexible energy supply of the natural gas energy in the natural gas station.

[0114] To sum up, the comprehensive energy system of a natural gas station with integrated constant-pressure compressed air energy storage of the present invention can be used to solve the technical problem of frequent changes in operating conditions of compressor units and turbine units in compressed air energy storage technology by making full use of the pressure potential energy of natural gas, and realizes efficient utilization and flexible energy supply of natural gas energy (including pressure potential energy and thermal energy) in the natural gas station, avoids the temperature reduction problem caused by throttling and pressure reduction of natural gas in the existing downstream pressure regulating station, improves the energy utilization efficiency and economic benefits of the natural gas station, and ensures the safe and stable operation of the natural gas station.

[0115] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A natural gas station integrated energy system with integrated constant pressure compressed air energy storage, characterized in that: It comprises a constant pressure pneumatic device (6), corresponding to an upstream natural gas station, the constant pressure pneumatic device (6) is respectively connected to a turbine (45) of a fuel-driven compressor unit, an air storage tank (9) and a compressed air energy storage system, and the exhaust gas with waste heat of the turbine (45) of the fuel-driven compressor unit is used as a driving heat source to realize cooling or heating on the user side; Corresponding to the downstream pressure regulating station, a constant pressure pneumatic device (6) is arranged on the pipeline between the upstream high-pressure pipeline network (1) and the downstream user pipeline network (2), and is respectively connected to the air storage tank (9) and the compressed air energy storage system; The compressed air energy storage system converts the heat and pressure potential energy of natural gas and air through a constant pressure pneumatic device (6). The compressed air energy storage system comprises an air compressor (7). The air compressor (7) is connected to the air inlet of an air storage tank (9) via the hot side of a third heat exchanger (8) and the constant pressure pneumatic device (6) in sequence. The air outlet of the air storage tank (9) is connected to the air inlet of an air turbine (11) via the cold side of a fourth heat exchanger (10). The cold side of the third heat exchanger (8) is divided into two paths via the heat energy storage device (13). One path is connected to the cold energy storage device (12) via the fourth heat exchanger (10), and the other path is connected to the cold energy storage device (12) via the heat driven energy supply device (40). The outlet of the cold energy storage device (12) is connected to the cold side of the third heat exchanger (8). The constant pressure pneumatic device (6) comprises a first pneumatic device (28), a second pneumatic device (29) and a third pneumatic device (30) which are arranged in parallel, and a floating piston is arranged in each of the first pneumatic device (28), the second pneumatic device (29) and the third pneumatic device (30); the input ends of the first pneumatic device (28), the second pneumatic device (29) and the third pneumatic device (30) are connected to an upstream high pressure pipeline network (1) or a turbine (45) of a fuel driven compressor unit via corresponding gas valves; the first pneumatic device (28) The output ends of the first pneumatic device (28), the second pneumatic device (29) and the third pneumatic device (30) are connected to the downstream user pipe network (2) or the atmospheric environment via corresponding air valves; the air outlet ends of the first pneumatic device (28), the second pneumatic device (29) and the third pneumatic device (30) are connected to the input end of the air storage tank (9) via corresponding air valves, and the output end of the air storage tank (9) is connected to the air inlet ends of the first pneumatic device (28), the second pneumatic device (29) and the third pneumatic device (30) via corresponding air valves.

2. The natural gas station integrated energy system with integrated constant pressure compressed air energy storage according to claim 1 is characterized in that: Fins are arranged along the inner circumference of the floating piston.

3. The natural gas station integrated energy system with integrated constant pressure compressed air energy storage according to claim 1 is characterized in that: A natural gas pressure recovery system is also provided between the upstream high-pressure pipeline network (1) and the downstream user pipeline network (2), and the natural gas pressure recovery system is provided in parallel with the constant pressure pneumatic device (6).

4. The natural gas station integrated energy system with integrated constant pressure compressed air energy storage according to claim 3 is characterized in that: The natural gas pressure recovery system comprises a first valve (14), one end of the first valve (14) is connected to an upstream high-pressure pipeline network (1), and the other end is connected to a downstream user pipeline network (2) via a second valve (15), a cold side of a first heat exchanger (3), a natural gas turbine (4) and a hot side of a second heat exchanger (5) in sequence. The first valve (14) is connected to a natural gas inlet end of the natural gas turbine (4) via a third valve (16) and is used to recover natural gas pressure potential energy when the compressed air energy storage system and the constant pressure pneumatic device (6) are in a static stage.

5. The natural gas station integrated energy system with integrated constant pressure compressed air energy storage according to claim 1 is characterized in that: The fuel-driven compressor unit turbine (45) is coaxially connected to the fuel-driven compressor unit compressor (43) and the natural gas compressor (46), and the fuel-driven compressor unit compressor (43) is connected to the fuel-driven compressor unit turbine (45) via the fuel-driven compressor unit combustion chamber (44).

6. The natural gas station integrated energy system with integrated constant pressure compressed air energy storage according to claim 5 is characterized in that: The interstage exhaust outlet of the turbine (45) of the fuel-driven compressor unit is connected to the gas inlet of the constant pressure pneumatic device (6) through the exhaust valve (47) of the turbine of the fuel-driven compressor unit, and the gas outlet of the constant pressure pneumatic device (6) is connected to the atmospheric environment.

7. The natural gas station integrated energy system with integrated constant pressure compressed air energy storage according to any one of claims 1 to 6, characterized in that: The downstream pressure regulating station is in operation. When the renewable energy is sufficient or the grid has surplus power, the air compressor (7) consumes the renewable energy power or surplus power to pressurize the air. The high-pressure air flows through the hot side of the third heat exchanger (8), is cooled by the heat storage medium, and enters the constant-pressure pneumatic device (6). The heat storage medium enters the thermal energy storage device (13). At the same time, the natural gas from the upstream high-pressure pipeline (1) enters the constant-pressure pneumatic device (6). The natural gas and air are converted into heat and pressure potential energy in the constant-pressure pneumatic device (6), thereby ensuring that the temperature of the natural gas is kept constant during the throttling and pressure reduction process, and that the back pressure of the air compressor (7) is kept constant. In the static state of the compressed air energy storage system, when the user side needs to provide a heat load or a cold load, the thermal fluid in the thermal energy storage device (13) enters the heat-driven energy supply device (40) to provide external heating or cooling according to the load demand of the user side, and the heat storage medium after the temperature is reduced enters the cold energy storage device (12) for storage through the outlet of the heat-driven energy supply device (40); When renewable energy is insufficient, the power grid is insufficient, or the power generation of the natural gas turbine (4) is insufficient, the high-pressure air in the air storage tank (9) flows through the constant-pressure pneumatic device (6) and enters the cold side of the fourth heat exchanger (10) to absorb heat and increase its temperature, and then enters the air turbine (11) to expand and generate power, and the heat storage medium in the thermal energy storage device (13) flows through the hot side of the fourth heat exchanger (10), heats the air, and then flows into the cold energy storage device (12) for storage; at the same time, the natural gas from the upstream high-pressure pipeline (1) enters the constant-pressure pneumatic device (6), and the natural gas and air are converted into heat and pressure potential energy in the constant-pressure pneumatic device (6), thereby ensuring that the temperature of the natural gas is kept constant during the throttling and pressure reduction process, and that the pressure of the high-pressure air entering the air turbine (11) is kept constant.

8. The natural gas station integrated energy system with integrated constant pressure compressed air energy storage according to any one of claims 1 to 6, characterized in that: The upstream fuel-driven compressor unit is working. When the renewable energy is sufficient or the grid has surplus power, the air compressor (7) consumes the renewable energy power or surplus power to pressurize the air. The high-pressure air flows through the hot side of the third heat exchanger (8), is cooled by the heat storage medium, and enters the constant-pressure pneumatic device (6). The heat storage medium enters the thermal energy storage device (13) for storage. At the same time, the flue gas obtained by the interstage extraction of the turbine (45) of the fuel-driven compressor unit enters the constant-pressure pneumatic device (6). The flue gas in the constant-pressure pneumatic device (6) transfers pressure potential energy with the high-pressure air. The flue gas is discharged into the atmosphere. The flue gas flowing out of the outlet of the turbine (45) of the fuel-driven compressor unit is used as a driving heat source to realize cooling or heating on the user side. In the static state of the compressed air energy storage system, when the user side needs to provide a heat load or a cold load, the thermal fluid in the thermal energy storage device (13) enters the heat-driven energy supply device (40), and provides external heating or cooling according to the load demand of the user side, and the heat storage medium after the temperature is reduced enters the cold energy storage device (12) for storage through the outlet of the heat-driven energy supply device (40); When renewable energy is insufficient or the power grid is insufficient, the high-pressure air in the air storage tank (9) flows through the constant-pressure pneumatic device (6) and enters the cold side of the fourth heat exchanger (10) to absorb heat and increase its temperature, and then enters the air turbine (11) to expand and generate power, and the heat storage medium in the thermal energy storage device (13) flows through the hot side of the fourth heat exchanger (10), heats the air, and then flows into the cold energy storage device (12) for storage; at the same time, the high-pressure flue gas extracted from the turbine (45) of the fuel-driven compressor unit enters the constant-pressure pneumatic device (6), and the flue gas flowing out of the outlet of the turbine (45) of the fuel-driven compressor unit is used as a driving heat source to achieve refrigeration or heating on the user side.

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