Cold electricity comprehensive utilization system based on energy coupling

Abstract

The utility model relates to a cold-electricity comprehensive utilization system based on energy coupling, which comprises an LNG (liquefied natural gas) receiving station, and LNG is gasified into natural gas after cold energy utilization by a cold energy power generation and cold exchange system, a liquid air energy storage system, a cold energy air separation system and a light hydrocarbon separation system. Natural gas respectively enters a natural gas pipe network, a gas power generation system and a natural gas hydrogen production system; the cold energy power generation and cold exchange system utilizes cold energy to generate electric energy for self-generation and self-use in a factory area, residual electricity is transmitted to a power grid, and meanwhile frozen products are generated. The liquid air energy storage system utilizes cold energy to generate electric energy for self-generation and self-use in a factory area, and residual electricity is transmitted to a power grid. The cold energy air separation system generates liquid oxygen, liquid nitrogen and liquid helium through cold energy. The light hydrocarbon separation system generates ethane and LPG (Liquefied Petroleum Gas) products by utilizing cold energy; the gas power generation system directly transmits electric energy generated by natural gas to a power grid; the natural gas hydrogen production system utilizes natural gas to produce hydrogen. The LNG cold energy utilization device can be widely applied to the technical field of LNG cold energy utilization.

Description

TECHNICAL FIELD

[0001] The utility model relates to LNG (liquefied natural gas) cold energy utilization technical field, especially is based on the cold electricity gas comprehensive utilization system of energy coupling. BACKGROUND

[0002] Natural gas can be changed into liquid under-162 DEG C or so by freezing under normal pressure. The liquefied natural gas is formed by the process of compression, throttling, expansion and external refrigeration after purifying natural gas.

[0003] LNG contains a large amount of low-temperature energy, which needs to be exchanged for heat before being used as fuel or chemical raw material to be gasified into normal-temperature gas. The cold energy released in the LNG gasification process can be utilized by direct or indirect methods. The direct utilization includes power generation, low-temperature air separation, refrigeration warehouse, liquefied carbon dioxide production, seawater desalination, air conditioning and low-temperature breeding and cultivation, etc. The indirect utilization includes low-temperature crushing, freeze drying, low-temperature drying, water and pollutant treatment and frozen food, etc. by using liquid nitrogen, liquid oxygen and liquid argon after air separation.

[0004] In the LNG gasification process, the total cold energy that can be recovered at various application sites is certain, but the useful work obtained at different recovery temperatures is different, that is, the utilization efficiency of the cold energy contained in LNG is different. According to the refrigeration principle, the lower the required process temperature, the more energy consumed by the conventional refrigeration mode. When reaching a certain low-temperature zone, the energy consumption increases by 10% for every 1K decrease in evaporation temperature. At this time, the energy-saving effect of utilizing LNG cold energy is more obvious, and the utilization rate of cold energy is high. Therefore, the cold energy should be utilized at the lowest possible temperature. When the temperature of the cold energy utilization site is high, a large amount of cold energy that cannot be utilized in the heat transfer process is wasted. When LNG cold energy is used in an air separation device, the process temperature (90-100K) is lower than the LNG temperature (111K). Compared with other applications such as refrigeration and freezing (253K), low-temperature power generation (233K), dry ice production (193K) and low-temperature crushing (133K), the cold energy of LNG is utilized to the greatest extent, which is the most reasonable way in the current technology. SUMMARY

[0005] In view of the above problems, the utility model aims at providing a cold electricity gas comprehensive utilization system based on energy coupling, which is suitable for LNG receiving station, improves the cold energy utilization rate of LNG receiving station by carrying out the cascade utilization of LNG cold energy, fully utilizes the natural gas resources of LNG receiving station, and additionally produces other industrial products while fully supplying power.

[0006] To achieve the above-mentioned purpose, the utility model adopts the following technical scheme:

[0007] An energy coupling-based cold and electricity comprehensive utilization system, comprising:

[0008] 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 power generation system, and a natural gas hydrogen production system;

[0009] The LNG in the LNG receiving station is gasified into natural gas after cold energy utilization 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, and the natural gas enters a natural gas pipeline network, the gas power generation system, and the natural gas hydrogen production system, respectively;

[0010] The cold energy power generation and refrigeration system utilizes the cold energy of LNG to generate electricity for self-generation and self-use in the plant area, and the excess electricity is transmitted to the power grid, while refrigeration products are produced;

[0011] The liquid air energy storage system utilizes the cold energy of LNG to generate electricity for self-generation and self-use in the plant area, and the excess electricity is transmitted 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 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] Further, the cold energy power generation and refrigeration system comprises a cold energy power generation device and a refrigeration station;

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

[0018] The LNG-intermediate medium heat exchanger exchanges heat with LNG in the LNG receiving station through an intermediate medium to release the high-grade cold energy of LNG, and the LNG sent out by the LNG-intermediate medium heat exchanger releases low-grade cold energy through the refrigeration station and is converted into natural gas which is returned to the LNG receiving station and then output to the natural gas pipeline network;

[0019] The intermediate medium pump is used to pressurize the intermediate medium, which is gasified after being heated by the refrigerant in the refrigerant-intermediate medium heat exchanger, sent to the expansion power generation equipment to generate electricity, and finally returned to the LNG-intermediate medium heat exchanger;

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

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

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

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

[0024] Further, when the liquid air energy storage system uses 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 air and send the purified air to the multi-stage compression unit; the multi-stage compression unit is used to multi-stage compress the purified air and send the released heat energy to the heat 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.

[0026] The liquid air in the liquid air storage tank is pressurized by a cryogenic pump, flows through the gasification unit for gasification, and then is sent to the expansion unit, while sending the cold energy to the cryogenic storage tank for storage; the gasified low-temperature high-pressure air is heated by the heat storage tank and then multi-stage expanded by the expansion unit, producing high-pressure normal-temperature gas to drive an air turbine generator to generate electricity, completing the energy release process.

[0027] Further, the cold energy air separation system includes a filtration system, a compression system, air compressor various stage coolers, a purification system, an air separation cold box, a glycol system, an LNG cold box, and a low-temperature liquid storage system.

[0028] The filtration system, compression system, air compressor various stage coolers, and purification system sequentially filter, compress, cool, and purify air.

[0029] The air separation cold box is used to rectify the purified air and send the rectified liquid oxygen, liquid nitrogen, and liquid argon products to the low-temperature liquid storage system for low-temperature storage.

[0030] The LNG cold box uses LNG delivered by the LNG receiving station to exchange heat with a nitrogen cycle, the nitrogen cycle provides cold energy to the air separation cold box, and the remaining cold energy after the LNG and nitrogen cycle heat exchange is absorbed by the glycol system, which cools the air compressor various stage coolers.

[0031] Further, the light hydrocarbon separation system comprises a first heat exchanger, a second heat exchanger, a flash tower, a demethanizer and a deethanizer;

[0032] The LNG of the LNG receiving station is heated through the first heat exchanger and the second heat exchanger, and then enters the flash tower for flash evaporation, and the liquid phase separated from the flash tower is pressurized and enters the demethanizer;

[0033] The flash gas and the methane gas separated from the flash tower and the demethanizer are respectively condensed into liquid phase methane products through heat exchange with the second heat exchanger and the first heat exchanger without compression, and the cold energy of the LNG is used for liquefying the liquid phase methane products;

[0034] The liquid phase separated from the demethanizer is separated into light hydrocarbons through the deethanizer, and ethane products and propane products are obtained.

[0035] Further, the gas power generation system adopts a gas-steam combined cycle, uses natural gas as a high-temperature working medium and steam as a low-temperature working medium, uses the exhaust gas of the gas turbine as a heating source of the steam turbine device cycle, generates electric power and supplies the electric power to the power grid.

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

[0037] The utility model discloses a LNG receiving station and a natural gas power generation system, and the LNG receiving station and the natural gas power generation system are combined to form a LNG receiving station and natural gas power generation system.

[0038] The utility model discloses a LNG receiving station and a natural gas power generation system, and the LNG receiving station and the natural gas power generation system are combined to form a LNG receiving station and natural gas power generation system.

[0039] In summary, the utility model has excellent use effect, and has very high use and popularization value. BRIEF DESCRIPTION OF DRAWINGS

[0040] Various other advantages and benefits will become apparent to those of ordinary skill in the art, upon reading the following detailed description of the preferred embodiments. The accompanying drawings are included to provide a description of the preferred embodiments and are not intended to limit the scope of the application. Throughout the drawings, the same reference designations are used to represent the same elements. In the drawings:

[0041] Figure 1The utility model embodiment provides a cold electricity comprehensive utilization system process chart based on energy coupling.

[0042] Figure 2 The utility model embodiment provides a cold electricity comprehensive utilization system cold energy power generation and cold exchange station schematic view based on energy coupling.

[0043] Figure 3 The utility model embodiment provides a cold electricity comprehensive utilization system liquid air energy storage schematic view based on energy coupling.

[0044] Figure 4 The utility model embodiment provides a cold electricity comprehensive utilization system cold energy air separation schematic view based on energy coupling.

[0045] Figure 5 The utility model embodiment provides a cold electricity comprehensive utilization system light hydrocarbon separation schematic view based on energy coupling. DETAILED DESCRIPTION

[0046] To make the purpose, technical scheme and advantages of the utility model embodiment clearer, the technical scheme of the utility model embodiment will be described clearly and completely below in combination with the drawings of the utility model embodiment. Obviously, the described embodiment is a part of the embodiment of the utility model, not all the embodiment. Based on the described embodiment of the utility model, all other embodiments obtained by the person skilled in the art belong to the range of protection of the utility model.

[0047] It should be noted that the terms used here are only for describing the specific embodiment, and are not intended to limit the exemplary embodiment according to the utility model. As used herein, the singular form is intended to include the plural form unless the context clearly indicates otherwise, and furthermore, it should be understood that when the terms "comprise" and / or "include" are used in the specification, there is a feature, step, operation, device, component and / or their combination.

[0048] In some embodiments of the utility model, a cold electricity comprehensive utilization system based on energy coupling is provided, which comprises 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 comprises 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 liquid air energy storage comprises multistage compression, liquefaction, purification, liquid air storage tank, gasification, multistage expansion, heat storage tank and cryogenic storage tank. The cold energy air separation comprises a filter system, a compressor system, air compressor various coolers, a purification system, an air separation cold box, an ethylene glycol system, an LNG cold box and a low temperature liquid storage system. The light hydrocarbon separation comprises a heat exchanger, a flash tower, a demethanizer and a deethanizer.

[0049] The utility model discloses a cold electricity comprehensive utilization system based on energy coupling, which comprehensively utilizes cold energy and natural gas resources of an LNG receiving station and provides regional power supply, and fully utilizes the location advantage of the LNG receiving station.

[0050] Example 1

[0051] As Figure 1 shown, the utility model provides a cold electricity comprehensive utilization system based on energy coupling, which comprises an LNG receiving station, a cold energy power generation and cold exchange system, a liquid air energy storage system, a cold energy air separation system, a light hydrocarbon separation system, a gas power generation system and a natural gas hydrogen production system. In the LNG receiving station, LNG is gasified into natural gas after cold energy utilization 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, and 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 cold exchange system utilizes the cold energy of LNG to generate electric energy for self-generation and self-use in the factory area, and the excess electric energy is transmitted to the power grid, and refrigeration products are produced at the same time. The liquid air energy storage system utilizes the cold energy of LNG to generate electric energy for self-generation and self-use in the factory area, and the excess electric energy 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 power generation system utilizes natural gas to generate electric energy which is directly transmitted to the power grid, and the natural gas hydrogen production system utilizes natural gas to produce hydrogen.

[0052] Preferably, as Figure 2 shown, the cold energy power generation and cold exchange system comprises a cold energy power generation device and a cold exchange station. The cold energy power generation device is based on an intermediate medium vaporizer (IFV) split device, adopts a low-temperature Rankine cycle system, takes the cold exchange station refrigerant as a heat source, and takes the intermediate medium as a working medium to form a closed low-temperature vapor power cycle. The cold energy power generation and cold exchange system utilizes the high-quality low-temperature cold energy of LNG and the low-grade energy of the cold exchange station refrigerant to generate electric energy.

[0053] Specifically, the cold energy power generation device comprises 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 the LNG of the LNG receiving station through the intermediate medium to release the high-grade cold energy of the LNG. The LNG sent out by the LNG-intermediate medium heat exchanger releases low-grade cold energy through the cold exchange station to be converted into natural gas and returned to the receiving station for external output to the natural gas pipeline network. The intermediate medium in the LNG-intermediate medium heat exchanger is pressurized by the intermediate medium pump, gasified by the refrigerant in the refrigerant-intermediate medium heat exchanger after heating, sent to the expansion power generation device for power generation to produce electric power, and finally returned to the LNG-intermediate medium heat exchanger. At the same time, the refrigerant of the cold exchange station is cooled by the refrigerant-intermediate medium heat exchanger, cooled by the LNG of the cold exchange station and supplied to downstream cold users.

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

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

[0056] Preferably, the cold exchange station utilizes the low-temperature cold energy of NG. The NG is gasified in the cold energy power generation device into NG, and the NG still has a large amount of low-temperature (such as below-50 DEG C) cold energy, which is taken away by the refrigerant of the cold exchange station for use in low-temperature cold storage, frozen seafood, freeze-dried fruits and vegetables, and data center cooling. The refrigerant can be ammonia, carbon dioxide, or environmentally friendly Freon.

[0057] Preferably, as shown in Figure 3 The liquid air energy storage system 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 liquid air energy storage system can be divided into an energy storage process and an energy release process.

[0058] In the energy storage process, the purification unit is used to purify air and send the purified air to the multi-stage compression unit; the multi-stage compression unit is used to compress the purified air in multiple stages and send the released heat energy to the heat storage tank, and send the compressed high-pressure air to the liquefaction unit; the liquefaction unit is used to pre-cool the high-pressure air by using LNG delivered by an LNG receiving station, and then store the air in the liquid air storage tank.

[0059] In the energy release process, the liquid air in the liquid air storage tank is pressurized by a cryogenic pump, flows through the gasification unit for gasification, and is sent to the expansion unit, while the cold energy is sent to the cryogenic storage tank for storage; the gasified low-temperature high-pressure air is heated by the heat storage tank and then expanded by the expansion unit in multiple stages to produce high-pressure normal-temperature gas to drive 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 closed cycle of the super-service-life tank of the LNG receiving station or the traditional closed cycle, which is not limited by the utility model.

[0061] Preferably, as shown in Figure 4 The cold energy air separation system combines the LNG gasification system and the air separation system, fully utilizes the huge cold energy 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, various stages of coolers in 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. The filtration system, compression system, various stages of coolers in the air compressor, 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 cryogenic storage. The LNG cold box utilizes the LNG supplied from the LNG receiving terminal and nitrogen circulation for heat exchange. The nitrogen circulation provides cooling energy to the air separation cold box, and the remaining cooling energy after the LNG and nitrogen circulation is absorbed by the ethylene glycol system, which then cools the various stages of coolers in the air compressor.

[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 liquefaction heat exchanger. Air cooling is achieved by fully utilizing the low-temperature LNG cooled after passing through the refrigeration and liquefaction system via an ethylene glycol cooling system. The cold energy air separation system utilizes cold energy in a cascade manner; the low-temperature LNG from the LNG receiving terminal first releases high-grade cold energy through a nitrogen circulation system, and then releases low-grade cold energy through the ethylene glycol system. Compared to conventional air separation processes, this replaces the expander refrigeration mechanism, eliminates the air-cooled tower, and significantly reduces power and water consumption.

[0064] Preferred, such as Figure 5 As shown, the light hydrocarbon separation system includes a primary heat exchanger, a secondary heat exchanger, a flash distillation tower, a demethanizer, and a deethaner. LNG from the LNG receiving terminal undergoes heat exchange in the primary and secondary heat exchangers before entering the flash distillation tower for flash evaporation. The liquid phase separated from the flash distillation tower is then pressurized and enters the demethanizer. The flash vapor and methane gas separated from the flash distillation tower and demethanizer are exchanged with the secondary and primary heat exchangers respectively without compression to condense liquid methane product. The cooling capacity of the LNG is used for the liquefaction of the liquid methane product. The liquid phase separated from the demethanizer is then subjected to light hydrocarbon separation in the deethaner to obtain ethane and propane products.

[0065] In particular, the preheating of raw materials in light hydrocarbon separation can also adopt LNG multi-stage pressurization flash evaporation process, LNG single-stage pressurization flash evaporation full compression process, LNG two-stage pressurization one-stage flash evaporation partial compression process, and LNG two-stage pressurization one-stage flash evaporation no compression process; the light hydrocarbon separation process can adopt single tower and double tower process or high, medium and low pressure process.

[0066] Preferably, the gas-fired 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 gas from the gas turbine serves as the heating source for the steam turbine unit's cycle, and the generated electricity is supplied to the power grid.

[0067] Preferably, the natural gas hydrogen production system includes several main processes such as natural gas desulfurization, natural gas steam reforming, CO 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 to supply natural gas reforming.

[0068] The specific workflow of this utility model embodiment is described below:

[0069] like Figure 1 The diagram shows a flow chart of a combined cold and electricity system based on energy coupling. During the day, LNG from the LNG receiving terminal passes through a cold energy power generation and cooling station, as well as a cold energy air separation system. At night, it passes through a liquid air storage system and another cold energy air separation system. When there are a high concentration of light hydrocarbons in the LNG receiving terminal, it passes through a light hydrocarbon separation system. After passing through these facilities, the LNG's cold energy is released and converted into natural gas. This natural gas is then simultaneously transported to the natural gas pipeline network, gas-fired power generation, and a natural gas-to-hydrogen system for utilization. The cold energy generation and cooling station utilize cold energy in a cascade manner: the cryogenic LNG first passes through the cold energy power generation system to release high-grade cold energy, and then passes through the cooling station to release low-grade cold energy. During the day, electricity generated by the cold energy power generation and liquid air storage system is transmitted to the power grid, while the gas-fired power generation system supplies peak-shaving power to the power grid throughout the day.

[0070] like Figure 2 The diagram shows a flow chart of a cold energy power generation and cooling station integrated utilization system based on energy coupling. LNG from the LNG receiving terminal undergoes heat exchange with the intermediate medium in an LNG-intermediate medium heat exchanger, releasing high-grade LNG cooling capacity. This high-grade cooling capacity is then released at the cooling station, converting the LNG into natural gas, which returns to the receiving terminal for export. The intermediate medium absorbs cooling capacity in the LNG-intermediate medium heat exchanger and undergoes a Rankine cycle. It is pressurized by an intermediate medium pump, heated by the refrigerant in the refrigerant-intermediate medium heat exchanger, vaporized, and expanded to generate electricity using power generation equipment. Finally, it returns to the LNG-intermediate medium heat exchanger. The refrigerant at the cooling station is cooled by the refrigerant-intermediate medium heat exchanger and then cooled by the LNG at the cooling station before being supplied to downstream cooling users.

[0071] like Figure 3 The diagram shows a flow chart of a liquid air energy storage system based on energy coupling for integrated cold and electricity utilization. In the liquid air energy storage stage, purified air undergoes multi-stage compression followed by LNG pre-cooling and liquefaction. The liquefied air is then stored in a liquid air storage tank. In the energy release stage, the liquid air is vaporized and then subjected to multi-stage expansion for power generation, which is then transmitted to the grid. The heat of compression generated by the multi-stage compression is stored in a thermal storage tank and then released to the expander stages. The cold energy of the liquid air is stored in a cryogenic storage tank and then released to the liquefaction cold box.

[0072] like Figure 4The diagram shows the flow chart of a cold energy air separation system based on energy coupling and integrated cold and electrical utilization. After filtration, air enters the compression system and then the purification system for further purification. After purification, it enters the air separation cold box for distillation, producing liquid oxygen, liquid nitrogen, and liquid argon products, which are then stored in a cryogenic liquid state. LNG is introduced from the LNG receiving terminal into the LNG cold box for heat exchange with the nitrogen circulation system. The nitrogen circulation system provides cooling energy to the air separation cold box. After heat exchange between the LNG and nitrogen circulation systems, the remaining cooling energy is absorbed by the ethylene glycol system, which then cools the various stages of the air compressor's coolers. The cold energy air separation system utilizes cold energy in a cascade manner. The cryogenic LNG first releases high-grade cold energy through the nitrogen circulation system, and then releases low-grade cold energy through the ethylene glycol system.

[0073] like Figure 5 The diagram shows a flowchart of a cold and electricity integrated utilization system based on energy coupling for light hydrocarbon separation. LNG undergoes two stages of heat exchange, followed by flash evaporation in a flash tower, then methane removal in a demethanizer, and finally ethane and propane removal in a deethaner. The natural gas produced in the demethanizer and flash towers is liquefied after being cooled by LNG cold energy and 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 terminal. In the cold energy power generation and cooling exchange station, LNG first releases high-grade cold energy through cold energy power generation, and then releases low-grade cold energy through the cooling exchange station. In the cold energy air separation, LNG first releases high-grade cold energy through nitrogen circulation, and then releases low-grade cold energy through ethylene glycol circulation, thereby improving the utilization rate of LNG cold energy and reducing overall energy loss. By leveraging the locational advantages of the LNG receiving terminal, the system comprehensively utilizes the cold energy and natural gas resources of the LNG receiving terminal and provides a stable power supply to the region.

[0075] The above-described embodiments are preferred embodiments of the present utility model and are only used to facilitate the illustration of the present utility model. They are not intended to limit the present utility model in any way. Any person skilled in the art who makes partial modifications or alterations to the technical content disclosed in the present utility model without departing from the scope of the technical features of the present utility model shall still fall within the scope of the technical features of the present utility model.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of this utility model and not to limit it. Although the utility model has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of this utility model. Any modifications or equivalent substitutions that do not depart from the spirit and scope of this utility model should be covered within the protection scope of the claims of this utility model.

Claims

1. A cold electricity integrated utilization system based on energy coupling, characterized in that, The system comprises an LNG receiving station, a cold energy power generation and cold exchange system, a liquid air energy storage system, a cold energy air separation system, a light hydrocarbon separation system, a gas power generation system and a natural gas hydrogen production system. The LNG in the LNG receiving station is gasified into natural gas after cold energy utilization 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, and the natural gas enters a natural gas pipeline network, the gas power generation system and the natural gas hydrogen production system respectively. The cold energy power generation and cold exchange system utilizes the cold energy of LNG to generate power for self-use in the plant, and the excess power is transmitted to the power grid, and refrigeration products are produced at the same time. The liquid air energy storage system utilizes the cold energy of LNG to generate power for self-use in the plant, and the excess power 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 products. The gas power generation system utilizes natural gas to generate power which is directly transmitted to the power grid. The natural gas hydrogen production system utilizes natural gas to produce hydrogen. The cold energy power generation and cold exchange system comprises a cold energy power generation device and a cold exchange station.

2. The energy source coupling-based cold electric comprehensive utilization system according to claim 1, characterized in that, The cold energy power generation device comprises an LNG-intermediate medium heat exchanger, an intermediate medium pump, a refrigerant-intermediate medium heat exchanger and an expansion power generation equipment. The LNG-intermediate medium heat exchanger exchanges heat with LNG in the LNG receiving station by an intermediate medium to release the high-grade cold energy of LNG, and the LNG sent out by the LNG-intermediate medium heat exchanger releases low-grade cold energy by the cold exchange station and is converted into natural gas which is returned to the LNG receiving station and then is exported to the natural gas pipeline network. The intermediate medium pump is used to pressurize the intermediate medium, which is gasified after being heated by the refrigerant in the refrigerant-intermediate medium heat exchanger, is sent to the expansion power generation equipment to generate power, and finally returns to the LNG-intermediate medium heat exchanger. The refrigerant of the cold exchange station is cooled by the refrigerant-intermediate medium heat exchanger, is cooled by LNG in the cold exchange station, and is supplied to downstream cold users. The intermediate medium is propane or a mixed refrigerant.

3. The energy source coupling-based cold electric comprehensive utilization system according to claim 2, characterized in that, The expander in the expansion power generation equipment is a single-stage or multi-stage expander.

4. The energy source coupling-based cold electric comprehensive utilization system according to claim 2, characterized in that, The liquid air energy storage system utilizes the cold energy of LNG by liquid air energy storage or liquid carbon dioxide energy storage.

5. The energy source coupling-based cold electric comprehensive utilization system according to claim 1, characterized in that, When the liquid air energy storage system utilizes liquid air energy storage, it comprises 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.

6. The energy-source-coupling-based cold electric comprehensive utilization system according to claim 5, characterized in that, The purification unit is used to purify air and send the purified air to the multi-stage compression unit. The multi-stage compression unit is used to compress the purified air in multiple stages, and the released heat energy is sent to the heat storage tank, while the compressed air is sent to the liquefaction unit; the liquefaction unit utilizes LNG delivered by the LNG receiving station to pre-cool the air, and then the air is stored in the liquid air storage tank to complete the energy storage process. ​ The liquid air in the liquid air tank is pressurized by a cryogenic pump, flows through the gasification unit for gasification, and is sent to the expansion unit, while the cold energy is sent to the cryogenic storage tank for storage; the gasified low-temperature high-pressure air is heated by the heat storage tank, and then multi-stage expanded by the expansion unit to generate high-pressure normal-temperature gas to drive the air turbine generator to generate electricity, thus completing the energy release process.

7. The energy-source-coupling-based cold electric comprehensive utilization system according to claim 1, characterized by, The cold energy air separation system comprises a filtering system, a compression system, air compressor coolers at different levels, a purification system, an air separation cold box, an ethylene glycol system, an LNG cold box and a low-temperature liquid storage system; The filtering system, the compression system, the air compressor coolers at different levels and the purification system sequentially filter, compress, cool and purify the air; The air separation cold box is used for rectifying the purified air, and the rectified liquid oxygen, liquid nitrogen and liquid argon products are sent to the low-temperature liquid storage system for low-temperature storage; The LNG cold box uses LNG delivered by an LNG receiving station to exchange heat with a nitrogen cycle, the nitrogen cycle provides cold energy to the air separation cold box, and the remaining cold energy after the LNG and the nitrogen cycle exchange heat is absorbed by the ethylene glycol system, and the ethylene glycol system cools the air compressor coolers at different levels.

8. The energy-source-coupling-based cold electric comprehensive utilization system according to claim 1, characterized in that, The light hydrocarbon separation system comprises a first heat exchanger, a second heat exchanger, a flash tower, a demethanizer and a deethanizer; The LNG from the LNG receiving station is exchanged heat by the first heat exchanger and the second 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 the methane gas separated from the flash tower and the demethanizer are not compressed and are exchanged heat with the second heat exchanger and the first heat exchanger respectively to condense liquid phase methane products, and the cold energy of the LNG is used for liquefying the liquid phase methane products; The liquid phase separated from the demethanizer is separated into ethane products and propane products by the deethanizer.

9. The energy-source-coupling-based cold electric comprehensive utilization system according to claim 1, characterized by, The gas power generation system adopts a gas-steam combined cycle, uses natural gas as a high-temperature working medium and steam as a low-temperature working medium, uses the exhaust gas of the gas turbine as a heating source for the steam turbine device cycle, generates electricity and supplies the power grid.

10. The energy-source-coupling-based cold electric comprehensive utilization system 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, CO steam shift and pressure swing adsorption processes to produce hydrogen.

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