A comprehensive utilization system of cooling and electricity based on energy coupling

Abstract

The present invention relates to a cold-electricity integrated utilization system based on energy coupling, comprising: an LNG receiving station, wherein LNG is gasified into natural gas after being utilized for cold energy by a cold energy power generation and refrigeration system, a liquid air energy storage system, a cold energy air separation system, and a light hydrocarbon separation system. The natural gas then enters the natural gas pipeline network, the gas-fired power generation system, and the natural gas hydrogen production system; the cold energy power generation and refrigeration system utilizes cold energy to generate electricity for self-use within the plant area, with excess electricity transmitted to the power grid, while also producing refrigerated products; the liquid air energy storage system utilizes cold energy to generate electricity for self-use within the plant area, with excess electricity transmitted to the power grid; the cold energy air separation system utilizes cold energy to produce liquid oxygen, liquid nitrogen, and liquid helium; the light hydrocarbon separation system utilizes cold energy to produce ethane and LPG products; the gas-fired power generation system utilizes natural gas to generate electricity and transmits it directly to the power grid; and the natural gas hydrogen production system utilizes natural gas to produce hydrogen. The present invention can be widely applied to the field of LNG cold energy utilization technology.

Description

Technical Field

[0001] The present invention relates to the technical field of LNG (liquefied natural gas) cold energy utilization, in particular to a cold and electricity comprehensive utilization system based on energy coupling. Background Art

[0002] Natural gas can be converted into liquid by freezing it to approximately -162°C under normal pressure. Liquefied natural gas is produced by purifying natural gas and then using a process of compression, throttling, expansion, and refrigeration with an external cooling source.

[0003] LNG contains a large amount of cryogenic energy. Before it can be used as fuel or a chemical feedstock, it must undergo heat exchange to vaporize it into room-temperature gas. The cold energy released during the LNG vaporization process can be utilized directly or indirectly. Direct uses include power generation, cryogenic air separation, cold storage, liquefied carbon dioxide production, seawater desalination, air conditioning, and low-temperature aquaculture and cultivation. Indirect uses include cryogenic crushing using liquid nitrogen, liquid oxygen, and liquid argon after air separation, freeze drying, cryogenic drying, water and pollutant treatment, and frozen food.

[0004] During the LNG vaporization process, the total amount of cold energy that can be recovered in various application scenarios is constant, but the useful work generated varies at different recovery temperatures—that is, the exergy utilization efficiency of the cold energy contained in the LNG varies. Refrigeration principles indicate that the lower the required process temperature, the more energy conventional refrigeration methods consume. Within a certain low-temperature range, energy consumption increases by 10% for every 1K decrease in evaporation temperature. At this point, the energy savings from utilizing LNG cold energy become more significant, and the cold energy utilization rate is also higher. Therefore, cold energy should be utilized at the lowest possible temperature. When the temperature at the cold energy utilization site is higher, a significant amount of cold energy is lost in the heat transfer process. When LNG cold energy is used in air separation units, because the process temperature (90-100K) is lower than the LNG temperature (111K), it maximizes the utilization of LNG cold energy compared to applications such as refrigeration (253K), low-temperature power generation (233K), dry ice production (193K), and cryogenic pulverization (133K), making it the most technically feasible method. Summary of the Invention

[0005] In response to the above problems, the purpose of the present invention is to provide a cold-electricity comprehensive utilization system based on energy coupling, which is suitable for LNG receiving stations. By carrying out cascade utilization of LNG cold energy, the cold energy utilization rate of the LNG receiving station is improved, and at the same time, the natural gas resources of the LNG receiving station are fully utilized, thereby fully supplying electricity and producing other industrial products.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A cold electricity comprehensive utilization system based on energy coupling, comprising:

[0008] LNG receiving station, cold energy power generation and refrigeration system, liquid air energy storage system, cold energy air separation system, light hydrocarbon separation system, gas power generation system and natural gas hydrogen production system;

[0009] The LNG in the LNG receiving station is gasified into natural gas after being utilized for cold energy by the cold energy power generation and cold exchange system, the liquid air energy storage system, the cold energy air separation system and the light hydrocarbon separation system. The natural gas enters the natural gas pipeline network, the gas power generation system and the natural gas hydrogen production system respectively;

[0010] The cold energy power generation and cooling system uses the cold energy of LNG to generate electricity for self-use within the plant, and transmits the surplus electricity to the power grid, while producing frozen products;

[0011] The liquid air energy storage system uses the cold energy of LNG to generate electricity for self-use within the factory, and transmits the surplus electricity to the power grid;

[0012] The cold energy air separation system utilizes the cold energy of LNG to produce liquid oxygen, liquid nitrogen and liquid helium;

[0013] The light hydrocarbon separation system utilizes the cold energy of LNG to produce ethane and LPG products;

[0014] The gas-fired power generation system utilizes natural gas to generate electricity which is directly transmitted to the power grid;

[0015] The natural gas hydrogen production system utilizes natural gas to produce hydrogen.

[0016] Furthermore, the cold energy power generation and cold exchange system includes a cold energy power generation device and a cold exchange station;

[0017] The cold energy power generation device includes an LNG-intermediate medium heat exchanger, an intermediate medium pump, a refrigerant-intermediate medium heat exchanger and an expansion power generation device;

[0018] The LNG-intermediate medium heat exchanger exchanges heat with the LNG at the LNG receiving station through the intermediate medium to release high-grade cold energy from the LNG. The LNG delivered by the LNG-intermediate medium heat exchanger then releases low-grade cold energy through the cold exchange station and is converted into natural gas, which is then returned to the LNG receiving station and transported to the natural gas pipeline network.

[0019] The intermediate medium pump is used to pressurize the intermediate medium, heat the refrigerant in the refrigerant-intermediate medium heat exchanger, and then gasify it, send it to the expansion power generation device to generate electricity, and finally return it to the LNG-intermediate medium heat exchanger;

[0020] The refrigerant in the cold exchange station is cooled by the refrigerant-intermediate medium heat exchanger, cooled by the LNG in the cold exchange station, and then supplied to downstream cold users.

[0021] Furthermore, the intermediate medium is propane or a mixed refrigerant.

[0022] Furthermore, the expander in the expansion power generation device is a single-stage or multi-stage expander.

[0023] Furthermore, the liquid air energy storage system uses liquid air energy storage or liquid carbon dioxide energy storage to realize the cold energy utilization of LNG.

[0024] Furthermore, when the liquid air energy storage system adopts liquid air energy storage, it includes a multi-stage compression unit, a liquefaction unit, a purification unit, a liquid air storage tank, a gasification unit, a multi-stage expansion unit, a heat storage tank and a cryogenic storage tank;

[0025] The purification unit is used to purify the air and send the purified air to the multi-stage compression unit; the multi-stage compression unit is used to perform multi-stage compression on the purified air and send the released heat energy to the thermal storage tank, and at the same time send the compressed air to the liquefaction unit; the liquefaction unit uses the LNG delivered by the LNG receiving station to pre-cool the air and then sends it to the liquid air storage tank for storage, completing the energy storage process;

[0026] The liquid air in the liquid air storage tank is pressurized by a cryogenic pump, flows through the vaporization unit for vaporization, and is then sent to the expansion unit. At the same time, the cold energy is sent to the cryogenic storage tank for storage. The vaporized low-temperature and high-pressure air is heated by the heat storage tank and then expanded in multiple stages by the expansion unit to generate high-pressure, room-temperature gas that drives the air turbine generator to generate electricity, completing the energy release process.

[0027] Furthermore, the cold energy air separation system includes a filtration system, a compression system, coolers at various stages of the air compressor, a purification system, an air separation cold box, an ethylene glycol system, an LNG cold box and a cryogenic liquid storage system;

[0028] The filtration system, compression system, air compressor coolers at various levels and purification system filter, compress, cool and purify the air in sequence;

[0029] The air separation cold box is used to distill the purified air and send the distilled liquid oxygen, liquid nitrogen and liquid argon products to the cryogenic liquid storage system for low-temperature storage;

[0030] The LNG cold box uses the LNG delivered by the LNG receiving station to exchange heat with the nitrogen cycle, and the nitrogen cycle provides cold energy to the air separation cold box. The remaining cold energy after the heat exchange between the LNG and nitrogen cycles is absorbed by the ethylene glycol system, and the ethylene glycol system is used to cool the coolers of each stage of the air compressor.

[0031] Furthermore, the light hydrocarbon separation system includes a primary heat exchanger, a secondary heat exchanger, a flash tower, a demethanizer, and a deethanizer;

[0032] The LNG from the LNG receiving station is subjected to heat exchange in the primary heat exchanger and the secondary heat exchanger, and then enters the flash tower for flash evaporation. The liquid phase separated from the flash tower is pressurized and enters the demethanizer.

[0033] The flash gas and methane gas separated from the flash tower and the demethanizer are respectively heat exchanged with the secondary heat exchanger and the primary heat exchanger without being compressed to condense the liquid methane product, and the cooling capacity of the LNG is used to liquefy the liquid methane product;

[0034] The liquid phase separated from the demethanizer is passed through a deethanizer to separate light hydrocarbons to obtain ethane products and propane products.

[0035] Furthermore, the gas-fired power generation system adopts a gas-steam combined cycle, with natural gas as the high-temperature working fluid and steam as the low-temperature working fluid, and uses the exhaust of the gas turbine as the heating source for the steam turbine device cycle to generate electricity and supply it to the power grid.

[0036] Furthermore, in the natural gas hydrogen production system, natural gas is sequentially subjected to natural gas desulfurization, natural gas steam reforming, CO2 water vapor shift and pressure swing adsorption processes to produce hydrogen.

[0037] The present invention has the following advantages due to the adoption of the above technical solution:

[0038] This invention utilizes cold energy at the LNG receiving station in multiple ways, significantly improving the station's cold energy utilization rate. This cascaded utilization of cold energy improves the exergy efficiency of LNG cold energy and reduces energy consumption in the station's seawater pumps. By utilizing natural gas in various ways, the station's locational advantages are fully utilized, creating a multi-layered product offering and expanding the station's industrial chain. Through multiple power supply methods, the LNG receiving station achieves self-generated power for its own use and also supplies power to the grid, enhancing regional power supply capacity.

[0039] In summary, the present invention has excellent use effect and high use and promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present invention. Throughout the drawings, the same reference numerals are used to denote the same components. In the drawings:

[0041] Figure 1This is a flow chart of a cold and electricity comprehensive utilization system based on energy coupling provided in an embodiment of the present invention;

[0042] Figure 2 Schematic diagram of a cold energy power generation and cold exchange station of a cold electricity comprehensive utilization system based on energy coupling provided in an embodiment of the present invention;

[0043] Figure 3 Schematic diagram of liquid air energy storage in a cold and electricity comprehensive utilization system based on energy coupling provided in an embodiment of the present invention;

[0044] Figure 4 Schematic diagram of cold energy and air separation of a cold electricity comprehensive utilization system based on energy coupling provided in an embodiment of the present invention;

[0045] Figure 5 It is a schematic diagram of light hydrocarbon separation in a cold electricity comprehensive utilization system based on energy coupling provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0046] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of the present invention.

[0047] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0048] In some embodiments of the present invention, a cold electricity comprehensive utilization system based on energy coupling is provided, including an LNG receiving station, a cold energy power generation and cold exchange station, liquid air energy storage, cold energy air separation, light hydrocarbon separation, gas power generation and natural gas hydrogen production, the cold energy power generation and cold exchange station includes an LNG-intermediate medium heat exchanger, an intermediate medium pump, a refrigerant-intermediate medium heat exchanger, an expansion power generation equipment and a cold exchange station, the liquid air energy storage includes multi-stage compression, liquefaction, purification, liquid air storage tank, gasification, multi-stage expansion, a heat storage tank and a cryogenic storage tank, the cold energy air separation includes a filtration system, a compressor system, air compressor coolers at various stages, a purification system, an air separation cold box, an ethylene glycol system, an LNG cold box, and a low-temperature liquid storage system, and the light hydrocarbon separation includes a heat exchanger, a flash tower, a demethanizer, and a deethanizer.

[0049] The present invention designs a cold-electricity comprehensive utilization system based on energy coupling, comprehensively utilizes the cold energy and natural gas resources of the LNG receiving station and provides regional electricity supply, thus giving full play to the location advantage of the LNG receiving station.

[0050] Example 1

[0051] like Figure 1 As shown, the present invention provides a cold electricity comprehensive utilization system based on energy coupling, comprising: an LNG receiving station, a cold energy power generation and refrigeration system, a liquid air energy storage system, a cold energy air separation system, a light hydrocarbon separation system, a gas-fired power generation system, and a natural gas hydrogen production system. The LNG in the LNG receiving station is gasified into natural gas after being utilized for cold energy by the cold energy power generation and refrigeration system, the liquid air energy storage system, the cold energy air separation system, and the light hydrocarbon separation system. The natural gas enters the natural gas pipeline network, the gas-fired power generation system, and the natural gas hydrogen production system respectively; the cold energy power generation and refrigeration system utilizes the cold energy of LNG to generate electricity for self-generation and self-use within the plant area, and the surplus electricity is transmitted to the power grid, while producing refrigerated products; the liquid air energy storage system utilizes the cold energy of LNG to generate electricity for self-generation and self-use within the plant area, and the surplus electricity is transmitted to the power grid; the cold energy air separation system utilizes the cold energy of LNG to produce liquid oxygen, liquid nitrogen, and liquid helium; the light hydrocarbon separation system utilizes the cold energy of LNG to produce ethane and LPG; the gas-fired power generation system utilizes natural gas to generate electricity and transmits it directly to the power grid, and the natural gas hydrogen production system utilizes natural gas to produce hydrogen.

[0052] Preferably, Figure 2 As shown, the cold energy power generation and cooling system includes a cold energy power generation device and a cooling station. The cold energy power generation device is based on an intermediate medium vaporizer (IFV) split device, adopts a low-temperature Rankine cycle system, uses the cooling station refrigerant as the heat source, and the intermediate medium as the working medium to form a closed low-temperature steam power cycle, which uses the high-quality low-temperature cold energy of LNG and the low-grade energy of the cooling station refrigerant to generate electricity.

[0053] Specifically, the cold energy power generation device includes an LNG-intermediate medium heat exchanger, an intermediate medium pump, a refrigerant-intermediate medium heat exchanger, an expansion power generation device, and a cold exchange station. The LNG-intermediate medium heat exchanger exchanges heat with LNG from the LNG receiving station using an intermediate medium to release high-grade cold energy from the LNG. The LNG delivered from the LNG-intermediate medium heat exchanger then releases low-grade cold energy through the cold exchange station, converts it into natural gas, and returns it to the receiving station for transmission to the natural gas pipeline network. The intermediate medium in the LNG-intermediate medium heat exchanger is pressurized by the intermediate medium pump, heated by the refrigerant in the refrigerant-intermediate medium heat exchanger, and then vaporized. The gas is then delivered to the expansion power generation device to generate electricity and finally returned to the LNG-intermediate medium heat exchanger. Meanwhile, the refrigerant in the cold exchange station is cooled by the refrigerant-intermediate medium heat exchanger, cooled by the LNG in the cold exchange station, and then supplied to downstream cold users.

[0054] Preferably, the cold energy power generation device may also adopt a direct expansion method.

[0055] Preferably, the intermediate medium of the Rankine cycle system can be propane or a mixed refrigerant, and the expander in the expansion power generation equipment can be a single-stage or multi-stage expander.

[0056] Optimally, the cold exchange station utilizes the low-temperature cold energy of NG. LNG is vaporized in the cold energy power generation device and converted into NG. The NG still contains a large amount of low-temperature cold energy (e.g., below -50°C). This energy is then transported away via the cold exchange station's refrigerant for use in low-temperature cold storage, frozen seafood, freeze-dried fruits and vegetables, and cooling large data centers. Refrigerants can include ammonia, carbon dioxide, or environmentally friendly Freon.

[0057] Preferably, Figure 3 As shown in Figure 1, the liquid air energy storage system includes a multi-stage compression unit, a liquefaction unit, a purification unit, a liquid air storage tank, a vaporization unit, a multi-stage expansion unit, a thermal storage tank, and a cryogenic storage tank. The liquid air energy storage system can be divided into an energy storage process and an energy release process.

[0058] During the energy storage process: the purification unit is used to purify the air and send the purified air to the multi-stage compression unit; the multi-stage compression unit is used to perform multi-stage compression on the purified air and send the released heat energy to the heat storage tank, while sending the compressed high-pressure air to the liquefaction unit; the liquefaction unit is used to pre-cool the high-pressure air using LNG delivered by the LNG receiving station and then send it to the liquid air storage tank for storage.

[0059] During the energy release process: the liquid air in the liquid air storage tank is pressurized by a cryogenic pump, flows through the vaporization unit for vaporization, and is then sent to the expansion unit. At the same time, the cold energy is sent to a cryogenic storage tank for storage; the vaporized low-temperature and high-pressure air is heated by a heat storage tank and then expanded in multiple stages by an expansion unit to generate high-pressure, room-temperature gas that drives an air turbine generator to generate electricity.

[0060] Preferably, the liquid air energy storage system can use liquid air energy storage or liquid carbon dioxide energy storage, and can use the over-service life storage tanks of the LNG receiving station to adopt a closed cycle or use a traditional closed cycle. The present invention does not impose any restrictions on this.

[0061] Preferably, Figure 4 As shown in the figure, the cold energy air separation system is a process that combines the LNG gasification system with the air separation system, and fully utilizes the huge amount of cold released during LNG gasification to produce air separation liquid products such as liquid nitrogen and liquid oxygen.

[0062] Specifically, the cold energy air separation system includes a filtration system, a compression system, air compressor coolers at various stages, a purification system, an air separation cold box, an ethylene glycol system, an LNG cold box, and a cryogenic liquid storage system. The filtration system, compression system, air compressor coolers at various stages, and purification system sequentially filter, compress, cool, and purify the air; the air separation cold box is used to distill the purified air and deliver the distilled liquid oxygen, liquid nitrogen, and liquid argon products to the cryogenic liquid storage system for low-temperature storage; the LNG cold box utilizes LNG delivered from the LNG receiving station to circulate with nitrogen for heat exchange, with the nitrogen cycle providing cold energy to the air separation cold box. The remaining cold energy after the heat exchange between the LNG and nitrogen cycles is absorbed by the ethylene glycol system, which then cools the air compressor coolers at various stages.

[0063] In this embodiment, the refrigeration and liquefaction system in the cold energy air separation process directly utilizes the cold energy of LNG for refrigeration and liquefaction through a nitrogen liquefier heat exchanger. Air cooling utilizes the ethylene glycol cooling system to fully utilize the low-temperature LNG after passing through the refrigeration and liquefaction system. This cold energy air separation system utilizes cold energy in a cascaded manner. Low-temperature LNG from the LNG receiving station first circulates through nitrogen to release high-quality cold energy, and then passes through the ethylene glycol system to release low-quality cold energy. Compared to conventional air separation processes, this system replaces the expansion mechanism for refrigeration and eliminates the air cooling tower, significantly reducing power and water consumption.

[0064] Preferably, Figure 5 As shown in the figure, the light hydrocarbon separation system includes a primary heat exchanger, a secondary heat exchanger, a flash tower, a demethanizer, and a deethanizer. LNG from the LNG receiving station undergoes heat exchange in the primary and secondary heat exchangers before entering the flash tower for flash evaporation. The liquid phase separated from the flash tower is then pressurized and enters the demethanizer. The flash gas and methane gas separated from the flash tower and demethanizer are uncompressed and exchanged with the secondary and primary heat exchangers, respectively, to condense into liquid methane products. The refrigeration of the LNG is used to liquefy the liquid methane products. The liquid phase separated from the demethanizer passes through the deethanizer for light hydrocarbon separation, resulting in ethane and propane products.

[0065] In particular, the preheating of raw materials in light hydrocarbon separation can also adopt the LNG multi-stage pressure-boosting flash process, the LNG single-stage pressure-boosting flash process with full compression, the LNG two-stage pressure-boosting and one-stage flash process with partial compression, and the LNG two-stage pressure-boosting and one-stage flash process without compression; the light hydrocarbon separation process can adopt single-tower and double-tower processes or high, medium and low pressure processes.

[0066] Preferably, the gas power generation system adopts a gas-steam combined cycle, with gas as the high-temperature working fluid and steam as the low-temperature working fluid. The exhaust of the gas turbine is used as the heating source for the steam turbine device cycle, and the generated electricity is supplied to the power grid.

[0067] Preferably, the natural gas hydrogen production system includes several main processes: natural gas desulfurization, natural gas steam reforming, CO2 steam shift and pressure swing adsorption (PSA). Hydrogen is mainly produced by natural gas reforming, and the steam generation system recovers heat from high-temperature flue gas for natural gas reforming.

[0068] The specific workflow of the embodiment of the present invention is introduced below:

[0069] like Figure 1 The figure shows a flow chart of the integrated cold and electricity utilization system based on energy coupling. During the day, LNG from the LNG receiving terminal passes through the cold energy generation and refrigeration exchange station, as well as the cold energy air separation system. At night, it passes through the liquid air energy storage system and the cold energy air separation system. When the LNG receiving terminal has a high concentration of light hydrocarbons, it passes through the light hydrocarbon separation system. After passing through these facilities, the LNG cold energy is released and converted into natural gas. The natural gas is then transported to the natural gas pipeline network, gas-fired power generation, and natural gas hydrogen production systems for utilization. The cold energy generation and refrigeration exchange station utilize cold energy in a cascaded manner, with low-temperature LNG first passing through the cold energy generation to release high-quality cold energy, and then passing through the refrigeration exchange station to release low-quality cold energy. During the day, electricity generated by the cold energy generation and liquid air energy storage is transmitted to the grid, while gas-fired power generation provides peak-shaving power throughout the day and is also transmitted to the grid.

[0070] like Figure 2 The figure shows a flow chart for the cold energy power generation and cold exchange station in a cold-electricity integrated utilization system based on energy coupling. LNG from the LNG receiving station passes through the LNG-intermediate medium heat exchanger, where it exchanges heat with the intermediate medium, releasing high-grade cold from the LNG. This cold is then released through the cold exchange station, where it is converted into natural gas and returned to the receiving station for export. The intermediate medium absorbs cold through the LNG-intermediate medium heat exchanger, undergoes a Rankine cycle, is pressurized by an intermediate medium pump, and then heated by the refrigerant in the refrigerant-intermediate medium heat exchanger, where it vaporizes and expands to generate electricity. The refrigerant finally returns to the LNG-intermediate medium heat exchanger. The refrigerant at the cold exchange station is cooled by the refrigerant-intermediate medium heat exchanger, cooled by the LNG in the cold exchange station, and then supplied to downstream cold users.

[0071] like Figure 3 The figure shows the liquid air energy storage flow chart for a cold-electricity integrated utilization system based on energy coupling. During the storage phase, air is purified, then compressed by a multi-stage compressor for LNG pre-cooling and liquefaction. The liquefied air is then stored in liquid air tanks. During the energy release phase, the liquefied air is vaporized and expanded in multiple stages to generate electricity and transmit it to the grid. The heat of compression generated by the multi-stage compression is stored in a thermal storage tank and then released between the expander stages. The cooling capacity of the liquid air is stored in a cryogenic tank and then released to the liquefied cold box.

[0072] like Figure 4The figure shows the cold energy air separation flow chart for a cold and electricity integrated utilization system based on energy coupling. After filtration, air enters the compression system and then the purification system for purification. After purification, it enters the air separation cold box for distillation into liquid oxygen, liquid nitrogen, and liquid argon products, which are then stored in cryogenic liquid form. LNG is introduced from the LNG receiving station into the LNG cold box for heat exchange with the nitrogen cycle, which provides cold energy to the air separation cold box. After the heat exchange between the LNG and nitrogen cycles, the remaining cold energy is absorbed by the ethylene glycol system, which then cools the various coolers of the air compressor. The cold energy air separation system utilizes cold energy in a cascaded manner, with the low-temperature LNG first passing through the nitrogen cycle to release high-grade cold energy, and then passing through the ethylene glycol system to release low-grade cold energy.

[0073] like Figure 5 The figure shows a flow chart for light hydrocarbon separation in a cold and electricity integrated utilization system based on energy coupling. After two stages of heat exchange, the LNG is flashed in a flash tower, then in a demethanizer to remove methane. The LNG then enters a deethanizer to remove ethane and propane products. The natural gas produced in the demethanizer and flash tower is cooled by LNG cold energy and liquefied before being returned to the LNG receiving terminal.

[0074] The innovation of this system lies in the cascaded utilization of LNG cold energy at the LNG receiving station. In the cold energy power generation and cold exchange station, LNG first releases high-grade cold energy through the cold energy power generation process, and then releases low-grade cold energy through the cold exchange station. In the cold energy air separation process, LNG first releases high-grade cold energy through the nitrogen cycle, and then releases low-grade cold energy through the ethylene glycol cycle. This improves the utilization rate of LNG cold energy and reduces overall energy exergy losses. By leveraging the LNG receiving station's locational advantages, the station's cold energy and natural gas resources are comprehensively utilized, providing a stable power supply to the region.

[0075] The above embodiments are preferred implementation modes of the present invention and are only used to facilitate the explanation of the present invention. They are not intended to limit the present invention in any form. Any person with ordinary knowledge in the technical field can, without departing from the scope of the technical features of the present invention, make partial changes or modifications to the technical contents disclosed in the present invention and make equivalent embodiments without departing from the technical features of the present invention. Such modifications still fall within the scope of the technical features of the present invention.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A cold electricity comprehensive utilization system based on energy coupling, characterized in that: include: LNG receiving station, cold energy power generation and refrigeration system, liquid air energy storage system, cold energy air separation system, light hydrocarbon separation system, gas power generation system and natural gas hydrogen production system; The LNG in the LNG receiving station is gasified into natural gas after being utilized for cold energy by the cold energy power generation and cold exchange system, the liquid air energy storage system, the cold energy air separation system and the light hydrocarbon separation system. The natural gas enters the natural gas pipeline network, the gas power generation system and the natural gas hydrogen production system respectively; The cold energy power generation and cooling system uses the cold energy of LNG to generate electricity for self-use within the plant, and transmits the surplus electricity to the power grid, while producing frozen products; The liquid air energy storage system uses the cold energy of LNG to generate electricity for self-use within the factory, and transmits the surplus electricity to the power grid; The cold energy air separation system utilizes the cold energy of LNG to produce liquid oxygen, liquid nitrogen and liquid helium; The light hydrocarbon separation system utilizes the cold energy of LNG to produce ethane and LPG products; The gas-fired power generation system utilizes natural gas to generate electricity which is directly transmitted to the power grid; The natural gas hydrogen production system utilizes natural gas to produce hydrogen; When the liquid air energy storage system adopts liquid air energy storage, it includes a multi-stage compression unit, a liquefaction unit, a purification unit, a liquid air storage tank, a gasification unit, a multi-stage expansion unit, a heat storage tank and a cryogenic storage tank; The purification unit is used to purify the air and send the purified air to the multi-stage compression unit; The multi-stage compression unit is used to perform multi-stage compression on the purified air and send the released heat energy to the thermal storage tank, while sending the compressed air to the liquefaction unit; the liquefaction unit uses the LNG delivered by the LNG receiving station to pre-cool the air and then sends it to the liquid air storage tank for storage, completing the energy storage process; The liquid air in the liquid air storage tank is pressurized by a cryogenic pump, flows through the vaporization unit for vaporization, and is then sent to the expansion unit, while the cold energy is sent to the cryogenic storage tank for storage; the vaporized low-temperature and high-pressure air is heated by the thermal storage tank and then expanded in multiple stages by the expansion unit, generating high-pressure and room-temperature gas that drives an air turbine generator to generate electricity, completing the energy release process; The cold energy air separation system includes a filtration system, a compression system, air compressor coolers at various stages, a purification system, an air separation cold box, an ethylene glycol system, an LNG cold box and a cryogenic liquid storage system; The filtration system, compression system, air compressor coolers at various levels and purification system filter, compress, cool and purify the air in sequence; The air separation cold box is used to distill the purified air and send the distilled liquid oxygen, liquid nitrogen and liquid argon products to the cryogenic liquid storage system for low-temperature storage; The LNG cold box uses the LNG delivered by the LNG receiving station to exchange heat with the nitrogen cycle, and the nitrogen cycle provides cold energy to the air separation cold box. The remaining cold energy after the heat exchange between the LNG and nitrogen cycles is absorbed by the ethylene glycol system, and the ethylene glycol system is used to cool the coolers of each stage of the air compressor.

2. The cold electricity comprehensive utilization system based on energy coupling according to claim 1, characterized in that: The cold energy power generation and cooling system includes a cold energy power generation device and a cooling station; The cold energy power generation device includes an LNG-intermediate medium heat exchanger, an intermediate medium pump, a refrigerant-intermediate medium heat exchanger and an expansion power generation device; The LNG-intermediate medium heat exchanger exchanges heat with the LNG at the LNG receiving station through the intermediate medium to release high-grade cold energy from the LNG. The LNG delivered by the LNG-intermediate medium heat exchanger then releases low-grade cold energy through the cold exchange station and is converted into natural gas, which is then returned to the LNG receiving station and transported to the natural gas pipeline network. The intermediate medium pump is used to pressurize the intermediate medium, heat the refrigerant in the refrigerant-intermediate medium heat exchanger, and then gasify it, send it to the expansion power generation device to generate electricity, and finally return it to the LNG-intermediate medium heat exchanger; The refrigerant in the cold exchange station is cooled by the refrigerant-intermediate medium heat exchanger, cooled by the LNG in the cold exchange station, and then supplied to downstream cold users.

3. The cold electricity comprehensive utilization system based on energy coupling according to claim 2, characterized in that: The intermediate medium is propane or mixed refrigerant.

4. The cold electricity comprehensive utilization system based on energy coupling according to claim 2, characterized in that: The expander in the expansion power generation device is a single-stage or multi-stage expander.

5. The cold and electricity comprehensive utilization system based on energy coupling according to claim 1, characterized in that: The liquid air energy storage system uses liquid air energy storage or liquid carbon dioxide energy storage to achieve cold energy utilization of LNG.

6. The cold electricity comprehensive utilization system based on energy coupling according to claim 1, characterized in that: The light hydrocarbon separation system includes a primary heat exchanger, a secondary heat exchanger, a flash tower, a demethanizer and a deethanizer; The LNG from the LNG receiving station is subjected to heat exchange in the primary heat exchanger and the secondary heat exchanger, and then enters the flash tower for flash evaporation. The liquid phase separated from the flash tower is pressurized and enters the demethanizer. The flash gas and methane gas separated by the flash tower and the demethanizer are respectively heat exchanged with the secondary heat exchanger and the primary heat exchanger without being compressed and condensed into liquid methane products. The cold energy of LNG is used to liquefy the liquid methane products. The liquid phase separated from the demethanizer is passed through a deethanizer to separate light hydrocarbons to obtain ethane products and propane products.

7. The cold electricity comprehensive utilization system based on energy coupling according to claim 1, characterized in that: The gas-fired power generation system adopts a gas-steam combined cycle, with natural gas as the high-temperature working fluid and steam as the low-temperature working fluid, and uses the exhaust gas of the gas turbine as the heating source for the steam turbine device cycle to generate electricity and supply it to the power grid.

8. The cold and electricity comprehensive utilization system based on energy coupling according to claim 1, characterized in that: In the natural gas hydrogen production system, natural gas is sequentially subjected to natural gas desulfurization, natural gas steam reforming, CO2 water vapor shift and pressure swing adsorption processes to produce hydrogen.

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