A cascade cold storage device for storing and delivering LNG cold energy by using multiple phase change materials

Abstract

The application discloses a step-by-step cold storage device for storing and conveying LNG cold energy by using multiple phase change materials, which comprises an LNG tank and a natural gas tank, and is provided with an ultralow-temperature phase change material energy storage system, a low-temperature phase change material energy storage system, a CO2 capture, liquefaction and energy storage system and a low-temperature power generation system which are connected with the LNG tank; the natural gas tank is connected with the low-temperature power generation system; the application divides the LNG cold energy utilization temperature into different zones, and uses phase change materials with different melting temperatures to store the cold energy of the LNG in different temperature zones, thereby improving the cold energy utilization rate and the temperature matching degree; different cold energy storage and conveying methods are formulated for the phase change materials in different temperature zones; the LNG cold energy can be utilized step by step, and is not affected by the adjustment or shutdown of a single series system; and the different temperature zone cold energy utilization systems can be independently operated.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of phase change cold storage, and particularly relates to a cascade cold storage device for storing and transporting LNG cold energy by using multiple phase change materials. BACKGROUND

[0002] With the transformation of global energy structure and the growth of demand for clean energy, liquefied natural gas (LNG) as a clean and efficient energy carrier is increasingly widely used. As a fuel, LNG generally undergoes a gasification process. The cold release of LNG is 830-860 kJ / kg, and the gasification temperature is about -162℃, which can be used as high-grade cold energy. At present, the LNG cold energy recycling methods mainly include direct utilization and indirect utilization. LNG cold energy utilization still needs to face several difficulties. First, the utilization method of cold energy is single, and most of the existing cold energy utilization projects are for recycling in a single temperature zone, and the cold energy outside the temperature zone has not been effectively recycled and utilized, resulting in low LNG cold energy utilization rate. Second, the demand for natural gas downstream fluctuates significantly with day and night and season, while cold energy users often need continuous and stable supply. Third, the planning of LNG cold energy utilization industry lags behind, and the design and construction of receiving stations and gasification stations ignore the surrounding cold energy users, resulting in insufficient space for subsequent planning and limiting the construction of large-scale utilization devices.

[0003] To solve the problem of single LNG cold energy utilization method, the cold energy in different temperature zones of LNG needs to be classified and recycled step by step, which can improve the utilization rate of LNG cold energy and match the LNG temperature zone with the use scenario. To solve the problem of significant fluctuation of natural gas downstream demand with day and night and season, LNG cold energy needs to be stored when there is surplus and released when there is shortage to meet the stable supply of cold energy users. To solve the problem of lagging behind in the planning of LNG cold energy utilization industry, a simple and fast cold energy transportation system needs to be strengthened to quickly transport LNG cold energy to the place where it is needed.

[0004] Phase change material is a material that stores and releases cold energy through phase change. Different phase change materials have different phase change temperatures and can store cold energy in different temperature ranges. At the same time, they can store a large amount of cold energy during the phase change process, greatly reducing the size of the LNG cold energy storage and release system. In addition, the phase change material after storing cold energy is generally in a solid or liquid state, which is convenient for the transmission of cold energy. Therefore, phase change material plays a very important role in the recycling of LNG cold energy, and the development of LNG cold energy cascade utilization system coupled with multiple phase change materials has important display significance.

[0005] The existing patent No. CN111102027B provides a LNG cold energy cascade utilization system and control method, which can ensure that other areas continue to produce without being affected when one of the refrigerant expansion sub-system, cold storage sub-system and data center sub-system appears abnormal working condition. The patent No. CN11757760A discloses a high-efficiency heat exchange phase change energy storage system based on low-temperature fluid. The high-efficiency heat exchange phase change energy storage system is a phase change energy storage cycle, which shares a set of system pipelines with the energy storage cycle and the energy release cycle through switching control, simplifying the system arrangement. The heat exchange plate group in the energy storage tank can perform energy storage heat exchange and energy release heat exchange, improving the heat exchange efficiency, increasing the effective heat exchange space in the energy storage tank, and reducing the volume of the energy storage tank by more than one-third.

[0006] The existing technology mainly focuses on single application in a certain field, such as air separation, low-temperature crushing, dry ice manufacturing, refrigeration cold storage and cold energy power generation technology, ignoring the utilization of LNG multi-temperature zone cold energy. Or a small amount of research only focuses on the utilization of multi-temperature zone LNG cold energy, ignoring the storage and transportation of LNG cold energy. SUMMARY

[0007] In view of the deficiencies of the prior art, the present application provides a cascade cold storage device for storing and transporting LNG cold energy by using multiple phase change materials. The device partitions the LNG cold energy utilization temperature and uses phase change materials with different melting temperatures to store the cold energy of LNG in different temperature zones, improving the cold energy utilization rate and temperature matching degree. Secondly, different cold energy storage and transportation methods are developed for different temperature zone phase change materials. Finally, through the design of the system control method, the LNG cold energy can be utilized step by step, and it is not affected by the adjustment or shutdown of a single series system; it can also realize independent operation of different temperature zone cold energy utilization systems.

[0008] To achieve the above-mentioned application purposes, the specific technical solutions of the present application are as follows:

[0009] A cascade cold storage device for storing and transporting LNG cold energy by using multiple phase change materials, comprising an LNG tank and a natural gas tank, having an ultra-low temperature phase change material energy storage system connected with the LNG tank, a low-temperature phase change material energy storage system, a CO2 capture, liquefaction and energy storage system, and a low-temperature power generation system; the natural gas tank is connected with the low-temperature power generation system;

[0010] The ultra-low temperature phase change material energy storage system comprises an ultra-low temperature cold energy transport vehicle with a cold storage heat exchange pipe and a cold release heat exchange pipe inside, LNG output from the LNG tank enters the cold storage heat exchange pipe and is transferred to the liquid phase change material energy storage in the cold release heat exchange pipe; the LNG that has completed cold storage is used for output to the low-temperature phase change energy storage system and / or the low-temperature power generation system;

[0011] The low-temperature phase change energy storage system comprises a first low-temperature cold energy heat exchanger and a second low-temperature cold energy heat exchanger, the incoming LNG flows through the second low-temperature cold energy heat exchanger and the first low-temperature cold energy heat exchanger in sequence, exchanges heat with the low-temperature phase change material to store energy, and the LNG after heat exchange enters the CO2 capture, liquefaction and energy storage system and / or the low-temperature power generation system.

[0012] The CO2 capture, liquefaction and energy storage system comprises a first CO2 liquefaction heat exchanger, a second CO2 liquefaction heat exchanger and an air dehydrator, the incoming LNG flows through the second CO2 liquefaction heat exchanger, the first CO2 liquefaction heat exchanger and the air dehydrator in sequence, and the LNG after heat exchange enters the low-temperature power generation system.

[0013] The low-temperature power generation system comprises a LNG direct expander, the input LNG is directly expanded to generate power by the LNG direct expander, and the cold release becomes gaseous natural gas stored in a natural gas tank.

[0014] Preferably, the ultra-low-temperature cold energy transport vehicle has an energy storage stage and an energy release stage; in the energy storage stage, the LNG enters the cold storage heat exchange pipe and is transferred to the liquid phase change material, the phase change material gradually solidifies, and the energy storage is completed; in the energy release stage, the cold release heat exchange pipe is connected with the ultra-low-temperature cold energy heat exchange pipe, the heat exchange medium enters the cold release heat exchange pipe, the cold energy of the phase change material is gradually transferred to the heat exchange medium, and the phase change material gradually melts.

[0015] Preferably, the low-temperature phase change energy storage system is provided with a low-temperature phase change material storage tank, a low-temperature cold energy heat exchanger and a gaseous low-temperature phase change material compressor connected in sequence; the liquid phase change material gradually decreases in temperature after flowing through the first low-temperature cold energy heat exchanger and the second low-temperature cold energy heat exchanger in sequence and is stored in the first low-temperature phase change material storage tank, then flows through the low-temperature cold energy heat exchanger to release cold energy and changes in temperature to gaseous phase change material, and the gaseous phase change material is pressurized to liquid state by the gaseous low-temperature phase change material compressor and used for circulating heat exchange with the LNG.

[0016] Preferably, the LNG entering the low-temperature phase change energy storage system is derived from the ultra-low-temperature phase change material energy storage system and / or the LNG tank after energy storage is completed.

[0017] Preferably, the LNG entering the CO2 capture, liquefaction and energy storage system is derived from the low-temperature phase change material energy storage system and / or the LNG tank after energy storage is completed.

[0018] Preferably, the CO2 capture, liquefaction and energy storage system further comprises an air pump, an air-water separator, a first air-CO2 separator, a second air-CO2 separator and a first liquid CO2 storage tank; the pumped air enters the air dehydrator to freeze the water in the air by the cold energy of LNG; the air-water separator is used for removing the solid water in the air; the dehydrated air is liquefied through the first CO2 liquefaction heat exchanger and the second CO2 liquefaction heat exchanger; the first air-CO2 separator is used for separating the liquid CO2 in the first CO2 liquefaction heat exchanger; the second air-CO2 separator is used for separating the liquid CO2 in the second CO2 liquefaction heat exchanger; and the first liquid CO2 storage tank is used for storing the liquid CO2.

[0019] Preferably, the CO2 capture, liquefaction and energy storage system further comprises a second liquid CO2 storage tank connected with the first liquid CO2 storage tank, and is provided with a liquid CO2 heat exchanger connected with the second liquid CO2 storage tank; and the liquid CO2 heat exchanger is used for releasing cold energy.

[0020] Preferably, the LNG sent into the low-temperature power generation system is derived from an ultralow-temperature phase change material energy storage system, a low-temperature phase change material energy storage system, a CO2 capture, liquefaction and energy storage system and / or an LNG tank.

[0021] Preferably, the low-temperature power generation system comprises an LNG-ORC working medium heat exchanger, through which the LNG transfers cold energy to the ORC working medium; an ORC working medium-seawater or low-temperature heat source heat exchanger and an ORC expander connected with the LNG-ORC working medium heat exchanger, for pumping the ORC working medium for ORC power generation into the ORC working medium-seawater or low-temperature heat source heat exchanger, and then into the ORC expander to generate power after being warmed up.

[0022] Preferably, the low-temperature power generation system comprises an LNG-ORC working medium heat exchanger, through which the LNG transfers cold energy to the ORC working medium; an ORC working medium-seawater or low-temperature heat source heat exchanger and an ORC expander connected with the LNG-ORC working medium heat exchanger, for pumping the ORC working medium for ORC power generation into the ORC working medium-seawater or low-temperature heat source heat exchanger, and then into the ORC expander to generate power after being warmed up.

[0023] Compared with the prior art, the application has the following innovations and beneficial effects:

[0024] (1) The application divides the LNG cold energy utilization temperature into zones, uses phase change materials with different melting temperatures to store the cold energy of the LNG in different temperature zones, and combines seawater or low-temperature heat sources to perform organic Rankine cycle and direct expansion power generation on the last cold energy, thereby improving the cold energy utilization rate and the matching degree of LNG utilization temperature.

[0025] (2) The application uses solid-liquid phase change materials with phase change temperature close to the LNG liquefaction temperature to store the ultra-low temperature cold energy of LNG through the heat storage exchanger, and uses the ultra-low temperature cold energy transport vehicle to transport the cold energy; the application uses phase change materials with phase change temperature between the LNG liquefaction temperature and the CO2 liquefaction temperature to store the low temperature cold energy of LNG, and transports the cold energy through the working fluid pipeline, thereby prolonging the use range of the LNG cold energy and increasing the convenience of the cold energy transportation.

[0026] (3) The application uses the cold energy close to the CO2 liquefaction temperature to capture and liquefy the CO2 in the air, and transports the liquid CO2 through the pipeline, thereby providing convenience for the users needing liquid CO2 around while decarbonizing by using the LNG cold energy.

[0027] (4) The four systems using the cold energy of the application have the cold energy temperature gradually decreasing from top to bottom, which can form a series of gradually using the cold energy of LNG, or can realize independent operation by adjusting the related valves when the demand of the part is high, thereby improving the system independence. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 It is a schematic diagram of the cascade cold storage device for storing and transporting the LNG cold energy by using various phase change materials.

[0029] Figure 2 It is a schematic diagram of the ultra-low temperature cold energy transport vehicle.

[0030] Figure 3 It is a schematic diagram of the cold storage and release heat exchange pipe.

[0031] Wherein: 1, LNG tank; 2, flow regulating valve 1; 3, LNG pump; 4, flow regulating valve 2; 5, flow regulating valve 3; 6, flow regulating valve 4; 7, flow regulating valve 5; 8, valve 1; 9, valve 2; 10, valve 3; 11, valve 4; 12, valve 5; 13, natural gas tank; 1-1, ultra-low temperature cold energy transport vehicle; 1-2, cold storage heat exchange pipe; 1-3, cold release heat exchange pipe; 1-4, ultra-low temperature cold energy heat exchanger; 1-5, ultra-low temperature phase change material energy storage system outlet temperature probe; 2-1, flow regulating valve 6; 2-2, low temperature phase change material energy storage system inlet temperature probe; 2-3, first low temperature cold energy heat exchanger; 2-4, second low temperature cold energy heat exchanger; 2-5, first low temperature phase change material storage tank; 2-6, first low temperature liquid phase change material pump; 2-7, second low temperature phase change material storage tank; 2-8, second low temperature liquid phase change material pump; 2-9, low temperature cold energy heat exchanger; 2-10, gaseous low temperature phase change material pump; 2-11, gaseous low temperature phase change material compressor; 2-12, low temperature phase change material energy storage system outlet temperature probe; 3-1, flow regulating valve 7; 3-2, CO2 capture, liquefaction and energy storage system inlet temperature probe; 3-3, air pump; 3-4, air dehydrator; 3-5, air-water separator; 3-6, first CO2 liquefaction heat exchanger; 3-7, first air-CO2 separator; 3-8, first liquid CO2 storage tank; 3-9, second CO2 liquefaction heat exchanger; 3-10, second air-CO2 separator; 3-11, first liquid CO2 pump; 3-12, second liquid CO2 storage tank; 3-13, second liquid CO2 pump; 3-14, liquid CO2 heat exchanger; 3-15, CO2 capture, liquefaction and energy storage system outlet temperature probe; 4-1, flow regulating valve 8; 4-2, flow regulating valve 9; 4-3, low temperature power generation system inlet temperature probe; 4-4, LNG-ORC working medium heat exchanger; 4-5, ORC working medium pump; 4-6, ORC working medium-seawater or low temperature heat source heat exchanger; 4-7, ORC expander; 4-8, first LNG-seawater or low temperature heat source heat exchanger; 4-9, LNG direct expander; 4-10, valve 3; 4-11, second LNG-seawater or low temperature heat source heat exchanger; 4-12, low temperature power generation system outlet temperature probe. DETAILED DESCRIPTION

[0032] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, it will be apparent to one skilled in the art that the present application can be practiced without the specific details presented herein. In other instances, well-known methods have not been described in detail in order to avoid unnecessarily complicating the present application.

[0033] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0034] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0035] Furthermore, in this invention, descriptions involving terms such as "first," "second," and "a" are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0036] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0037] like Figures 1-3 As shown, this embodiment utilizes a cascaded cold storage device for storing and transporting LNG cold energy using multiple phase change materials, including an LNG tank 1 and a natural gas tank 13. It has an ultra-low temperature phase change material energy storage system, a low temperature phase change material energy storage system, a CO2 capture, liquefaction and energy storage system, and a low temperature power generation system connected to the LNG tank 1; the natural gas tank 13 is connected to the low temperature power generation system.

[0038] The cryogenic phase change material energy storage system includes a cryogenic cold energy transport vehicle containing a cold storage heat exchange tube 1-2 and a cold release heat exchange tube 1-3. LNG output from LNG tank 1 enters the cold storage heat exchange tube 1-2 and is transferred to the liquid phase change material energy storage in the cold release heat exchange tube 1-3. The LNG that has completed cold storage is used to be output to the cryogenic phase change energy storage system and / or cryogenic power generation system.

[0039] The low-temperature phase change energy storage system comprises a first low-temperature cold energy exchanger 2-4 and a second low-temperature cold energy exchanger 2-3, the incoming LNG flows through the second low-temperature cold energy exchanger 2-4 and the first low-temperature cold energy exchanger 2-3 in sequence, exchanges heat with the low-temperature phase change material to store energy, and the LNG after heat exchange enters the CO2 capture, liquefaction and energy storage system and / or the low-temperature power generation system;

[0040] The CO2 capture, liquefaction and energy storage system comprises a first CO2 liquefaction exchanger 3-6, a second CO2 liquefaction exchanger 3-9 and an air dehydrator 3-4, the incoming LNG flows through the second CO2 liquefaction exchanger, the first CO2 liquefaction exchanger and the air dehydrator in sequence, and the LNG after heat exchange enters the low-temperature power generation system;

[0041] The low-temperature power generation system comprises a LNG direct expander 4-9, the input LNG is directly expanded to generate power through the LNG direct expander, and the cold release becomes gaseous natural gas which is stored in a natural gas tank.

[0042] In the embodiment, the cold energy temperature of the four systems using the cold energy of LNG gradually decreases from top to bottom, which can form a series of gradual utilization of the cold energy of LNG.

[0043] As shown in Figure 1 The LNG tank 1 is connected with the ultra-low-temperature phase change material energy storage system, the low-temperature phase change material energy storage system, the CO2 capture, liquefaction and energy storage system and the low-temperature power generation system through the flow regulating valve 2 and the LNG pump 3. The natural gas tank 13 is connected with the low-temperature power generation system. The opening degree of the flow regulating valve 2 can control the LNG flow pumped out of the LNG tank 1 and the LNG flow into different systems. In addition, the ultra-low-temperature phase change material energy storage system is connected with the low-temperature phase change material energy storage system through the valve 10 and the flow regulating valve 2-1, and is connected with the low-temperature power generation system through the valve 8 and the flow regulating valve 4-2. The low-temperature phase change material energy storage system is further connected with the CO2 capture, liquefaction and energy storage system through the valve 11 and the flow regulating valve 3-1, and is connected with the low-temperature power generation system through the valve 9 and the flow regulating valve 4-2. The CO2 capture, liquefaction and energy storage system is further connected with the low-temperature power generation system through the valve 12 and the flow regulating valve 4-1.

[0044] The ultra-low-temperature cold energy transport vehicle 1-1 is provided with a cold storage heat exchange pipe 1-2 and a cold release heat exchange pipe 1-3, and the two groups of heat exchange pipes are arranged alternately. In the cold storage stage, the cold storage heat exchange pipe 1-2 is connected with the system pipeline through the flow regulating valve 4 and the valve 10. After long-distance transportation, the cold release heat exchange pipe 1-3 is connected with the ultra-low-temperature cold energy exchanger 1-4. The ultra-low-temperature phase change material energy storage system outlet temperature probe 1-5 is installed at the outlet position of the system.

[0045] The low-temperature phase change material energy storage system inlet temperature probe 2-2, the second low-temperature cold energy heat exchanger 2-4, the first low-temperature cold energy heat exchanger 2-3, and the low-temperature phase change material energy storage system outlet temperature probe 2-12 are sequentially connected. In addition, the first low-temperature cold energy heat exchanger 2-3, the second low-temperature cold energy heat exchanger 2-4, the first low-temperature phase change material storage tank 2-5, the first low-temperature liquid phase change material pump 2-6, the second low-temperature phase change material storage tank 2-7, the second low-temperature liquid phase change material pump 2-8, the low-temperature cold energy heat exchanger 2-9, the gaseous low-temperature phase change material pump 2-10, and the gaseous low-temperature phase change material compressor 2-11 are sequentially connected.

[0046] The CO2 capture, liquefaction and energy storage system inlet temperature probe 3-2, the second CO2 liquefaction heat exchanger 3-9, the first CO2 liquefaction heat exchanger 3-6, and the CO2 capture, liquefaction and energy storage system outlet temperature probe 3-14 are sequentially connected. The air pump 3-3, the air water separator 3-4, the air-water separator 3-5, the first CO2 liquefaction heat exchanger 3-6, the first air-CO2 separator 3-7, and the first liquid CO2 storage tank 3-8 are sequentially connected. In addition, the first air-CO2 separator 3-7 is also sequentially connected with the second CO2 liquefaction heat exchanger 3-9, the second air-CO2 separator 3-10, and the first liquid CO2 storage tank 3-8. The first liquid CO2 storage tank 3-8, the first liquid CO2 pump 3-11, the second liquid CO2 storage tank 3-12, the second liquid CO2 pump 3-13, and the liquid CO2 heat exchanger 3-14 are sequentially connected.

[0047] The low-temperature power generation system inlet temperature probe 4-3, the LNG-ORC working medium heat exchanger 4-4, the first LNG-seawater or low-temperature heat source heat exchanger 4-8, the LNG direct expansion generator 4-9, the second LNG-seawater or low-temperature heat source heat exchanger 4-11, and the low-temperature power generation system outlet temperature probe 4-12 are sequentially connected. In addition, the LNG-ORC working medium heat exchanger 4-4 is also sequentially connected with the ORC working medium pump 4-5, the ORC working medium-seawater or low-temperature heat source heat exchanger 4-6, and the ORC expander 4-7. In addition, the ORC working medium-seawater or low-temperature heat source heat exchanger 4-6, the first LNG-seawater or low-temperature heat source heat exchanger 4-8, and the second LNG-seawater or low-temperature heat source heat exchanger 4-11 are also connected with seawater or a low-temperature heat source.

[0048] In another preferred embodiment, the ultralow-temperature cold energy transport vehicle has an energy storage stage and an energy release stage; in the energy storage stage, LNG enters the cold storage heat exchange pipe 1-2 and is transferred to the liquid phase change material, the phase change material gradually solidifies, and the energy storage is completed; in the energy release stage, the cold release heat exchange pipe 1-3 is connected with the ultralow-temperature cold energy heat exchange pipe 1-4, the heat exchange medium enters the cold release heat exchange pipe, the cold energy of the phase change material is gradually transferred to the heat exchange medium, and the phase change material gradually melts.

[0049] The opening of flow regulating valve 2 is adjusted and LNG in LNG tank 1 is pumped out by LNG pump 3. The pumped LNG is regulated by flow regulating valve 4 and enters the cold storage heat exchange tube 1-2 in the ultra-low temperature cold energy transport vehicle 1-1 in the ultra-low temperature phase change energy storage system. At this time, the loaded phase change material (isopentane, 2-methylpentane, isoprene, etc.) in the ultra-low temperature cold energy transport vehicle 1-1 is in a liquid state. As the cold energy of the LNG is transferred to the liquid phase change material, the LNG gradually vaporizes and the temperature gradually rises (its temperature is monitored by the outlet temperature probe 1-5 of the ultra-low temperature phase change material energy storage system), and the phase change material gradually solidifies. After the energy storage is completed, the solid phase change material is transported by the ultra-low temperature cold energy transport vehicle 1-1 to a place where cold energy is needed, and the cold release heat exchange tube 1-3 of the ultra-low temperature cold energy transport vehicle 1-1 is connected with the ultra-low temperature cold energy heat exchange tube 1-4. The heat exchange medium enters the cold release heat exchange tube 1-3, the cold energy of the phase change material is gradually transferred to the heat exchange medium, the phase change material gradually melts, and the temperature of the heat exchange medium gradually decreases. The heat exchange medium then transfers the cold energy to other media in the ultra-low temperature cold energy heat exchanger 1-4. After the cold release is completed, the ultra-low temperature cold energy transport vehicle 1-1 returns to the cold storage place to continue the next cycle. The LNG that has completed the cold storage can enter the low-temperature phase change energy storage system through valve 10 and flow regulating valve 2-1, or can directly enter the low-temperature power generation system through valve 10, valve 8, and flow regulating valve 4-2.

[0050] In a preferred embodiment, the LNG entering the low-temperature phase change energy storage system is derived from the ultra-low temperature phase change material energy storage system or the LNG tank that has completed energy storage, or a mixture of the two.

[0051] The temperature of LNG entering the low temperature phase change material energy storage system can be monitored by the low temperature phase change material energy storage system inlet temperature probe 2-2. The LNG is sourced from the ultra-low temperature phase change material energy storage system or LNG tank 1 that has completed energy storage and can be adjusted in flow rate or temperature by the flow regulating valve 2-1 and the flow regulating valve 5. After mixing, the LNG flows through the second low temperature cold energy heat exchanger 2-4 and the first low temperature cold energy heat exchanger 2-3 in sequence, in the opposite direction to the flow direction of the low temperature phase change material, and the cold energy of the LNG can be utilized step by step. The LNG that has completed heat exchange can enter the CO2 capture, liquefaction and energy storage system through the valve 11 and the flow regulating valve 3-1, or can directly enter the low temperature power generation system through the valve 11, the valve 9 and the flow regulating valve 4-2. In addition, the high temperature liquid phase change material (nitrogen trifluoride, etc.) gradually decreases in temperature after flowing through the first low temperature cold energy heat exchanger 2-3 and the second low temperature cold energy heat exchanger 2-4 in sequence and can then be stored in the first low temperature phase change material storage tank 2-5. Subsequently, it can be transported to the second low temperature phase change material storage tank 2-7 that requires cold energy through the first low temperature phase change material pump 2-6 and the pipeline, and can be released through the second low temperature phase change material pump 2-8 and the low temperature cold energy heat exchanger 2-9, gradually increasing in temperature and becoming gaseous phase change material. Finally, it can be transported to the cold storage site through the gaseous low temperature phase change material pump 2-10 and the pipeline and the gaseous low temperature phase change material compressor 2-11 to pressurize the gaseous phase change material into a liquid state, continuing the next cycle.

[0052] In this embodiment, the LNG entering the CO2 capture, liquefaction and energy storage system is sourced from the low temperature phase change material energy storage system or LNG tank that has completed energy storage, or can be a mixture of the two.

[0053] The LNG temperature entering the CO2 capture, liquefaction and energy storage system can be monitored by the CO2 capture, liquefaction and energy storage system inlet temperature probe 3-2, which is sourced from the low temperature phase change material energy storage system or the LNG tank 1 after energy storage and can be regulated by the flow regulating valve 3-1 and the flow regulating valve 6. The mixed LNG flows through the second CO2 liquefaction heat exchanger 3-9, the first CO2 liquefaction heat exchanger 3-6 and the air water separator 3-4 in sequence, in the opposite direction of the air flow, which can utilize the cold energy of the LNG in stages. The LNG after heat exchange enters the low temperature power generation system through the valve 12, the flow regulating valve 4-1 and the flow regulating valve 4-2. The air is first pumped into the air water separator 3-4 by the air pump 3-3, using the cold energy of the LNG to condense the water in the air, and then passes through the air-water separator 3-5 to remove the solid water. The air after water removal passes through the first CO2 liquefaction heat exchanger 3-6 to liquefy part of the CO2, and in the subsequent first air-CO2 separator 3-7, the liquid CO2 is separated and stored in the first liquid CO2 tank 3-8. The remaining gas enters the second CO2 liquefaction heat exchanger 3-9 to liquefy most of the CO2, and in the subsequent second air-CO2 separator 3-10, the liquid CO2 is separated and stored in the first liquid CO2 tank 3-8. The liquid CO2 in the first liquid CO2 tank 3-8 is transported by the first liquid CO2 pump 3-11 and the pipeline to the location where liquid CO2 and cold energy are needed and stored in the second liquid CO2 tank 3-12. Then the liquid CO2 can be directly used or transported to the liquid CO2 heat exchanger 3-14 to release cold energy.

[0054] In this embodiment, the LNG sent into the low temperature power generation system is sourced from the ultra-low temperature phase change material energy storage system, the low temperature phase change material energy storage system, the CO2 capture, liquefaction and energy storage system and / or the LNG tank, and can also be a mixture of at least two of the above LNGs.

[0055] The temperature of LNG entering the low temperature power generation system can be monitored by the low temperature power generation system inlet temperature probe 4-3, and the LNG is sourced from the above three systems or the LNG tank 1 and can be regulated in flow or temperature by the flow regulating valve 4-1, the flow regulating valve 7 and the flow regulating valve 4-2. After mixing, the LNG first passes through the LNG-ORC working medium heat exchanger 4-4, and the cold energy of the LNG is transferred to the ORC working medium, and the temperature of the LNG gradually rises, and the temperature of the ORC working medium gradually drops. Subsequently, the LNG flows through the first LNG-seawater or low temperature heat source heat exchanger 4-8, and the temperature of the LNG rises and the pressure increases, and the LNG directly expands in the LNG direct expander 4-9 to generate power. Finally, the LNG passes through the second LNG-seawater or low temperature heat source heat exchanger 4-11, and after releasing cold, becomes gaseous natural gas and is stored in the natural gas tank 13. The ORC working medium for ORC power generation is pumped into the ORC working medium-seawater or low temperature heat source heat exchanger 4-5, the temperature of the ORC rises, and enters the ORC expander 4-7 to generate power, and the high temperature ORC working medium flows into the LNG-ORC working medium heat exchanger 4-4, and the temperature drops, and continues the next cycle. In addition, the LNG from the above three systems or the LNG tank 1 can also be directly introduced into the second LNG-seawater or low temperature heat source heat exchanger 4-11 through the valve 4-10 to quickly supply natural gas or reduce the shortage of natural gas supply caused by failure of the above four systems.

[0056] In addition, the four energy storage or power generation systems in the present application can also be independently operated by adjusting the valves or flow regulating valves, increasing the flexibility of the use of LNG cold energy. For example, to realize the operation of the single CO2 capture, liquefaction and energy storage system, close the remaining systems, then open the regulating valve 2, the regulating valve 6, the valve 12, the regulating valve 4-1 and the valve 4-10, and close the remaining valves, to realize the independent operation of the system without affecting other systems. If only the low temperature phase change material energy storage system and the low temperature power generation system are to be operated, the regulating valve 2, the regulating valve 5, the valve 11, the valve 9 and the regulating valve 4-2 need to be opened, and the remaining valves need to be closed, to realize the operation of only the low temperature phase change material energy storage system and the low temperature power generation system.

[0057] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A cascade cold storage device for storing and delivering LNG cold energy using a plurality of phase change materials, comprising an LNG tank and a natural gas tank, characterized in that, The system comprises an ultra-low temperature phase change material energy storage system, a low temperature phase change material energy storage system, a CO2 capture, liquefaction and energy storage system, and a low temperature power generation system, wherein the LNG tank is connected with the ultra-low temperature phase change material energy storage system, the low temperature phase change material energy storage system, the CO2 capture, liquefaction and energy storage system, and the low temperature power generation system. The ultra-low temperature phase change material energy storage system comprises an ultra-low temperature cold energy transport vehicle with a cold storage heat exchange pipe and a cold release heat exchange pipe, wherein the LNG output from the LNG tank enters the cold storage heat exchange pipe and is transferred to the liquid phase change material energy storage in the cold release heat exchange pipe. The low temperature phase change material energy storage system comprises a first low temperature cold energy heat exchanger and a second low temperature cold energy heat exchanger, wherein the incoming LNG flows through the second low temperature cold energy heat exchanger and the first low temperature cold energy heat exchanger in sequence, exchanges heat with the low temperature phase change material, and the LNG after heat exchange enters the CO2 capture, liquefaction and energy storage system and / or the low temperature power generation system. The CO2 capture, liquefaction and energy storage system comprises a first CO2 liquefaction heat exchanger, a second CO2 liquefaction heat exchanger and an air dehydrator, wherein the incoming LNG flows through the second CO2 liquefaction heat exchanger, the first CO2 liquefaction heat exchanger and the air dehydrator in sequence, and the LNG after heat exchange enters the low temperature power generation system. The low temperature power generation system comprises a LNG direct expander, wherein the input LNG is directly expanded by the LNG direct expander to generate power, and the cold release gasified natural gas is stored in the natural gas tank.

2. The cascade cold storage device for storing and delivering LNG cold energy using multiple phase change materials according to claim 1, characterized in that, The ultra-low temperature cold energy transport vehicle has an energy storage stage and an energy release stage, wherein in the energy storage stage, the LNG enters the cold storage heat exchange pipe and is transferred to the liquid phase change material, the phase change material gradually solidifies, and the energy storage is completed; in the energy release stage, the cold release heat exchange pipe is connected with the ultra-low temperature cold energy heat exchange pipe, the heat exchange medium enters the cold release heat exchange pipe, the cold energy of the phase change material is gradually transferred to the heat exchange medium, and the phase change material gradually melts. 3.The cascade cold storage device for storing and delivering LNG cold energy by using multiple phase change materials according to claim 1, characterized in that, The low temperature phase change material energy storage system is provided with a low temperature phase change material storage tank, a low temperature cold energy heat exchanger and a gaseous low temperature phase change material compressor connected in sequence, wherein the liquid phase change material flows through the first low temperature cold energy heat exchanger and the second low temperature cold energy heat exchanger in sequence, the temperature gradually decreases, and the liquid phase change material is stored in the first low temperature phase change material storage tank; the liquid phase change material flows through the low temperature cold energy heat exchanger to release cold energy, the temperature changes to a gaseous phase change material, and the gaseous phase change material is pressurized into a liquid state by the gaseous low temperature phase change material compressor, which is used for circulating heat exchange with the LNG.

4. The cascade cold storage device for storing and delivering LNG cold energy using multiple phase change materials according to claim 3, characterized in that, The LNG entering the low temperature phase change material energy storage system is derived from the ultra-low temperature phase change material energy storage system and / or the LNG tank after energy storage.

5. The cascade cold storage device for storing and delivering LNG cold energy using multiple phase change materials according to claim 1, wherein, The LNG entering the CO2 capture, liquefaction and energy storage system is derived from the low temperature phase change material energy storage system and / or the LNG tank after energy storage.

6. The cascade cold storage device for storing and delivering LNG cold energy using multiple phase change materials according to claim 5, characterized in that, The CO2 capture, liquefaction and energy storage system further comprises an air pump, an air-water separator, a first air-CO2 separator, a second air-CO2 separator and a first liquid CO2 storage tank; the pumped air enters the air-water separator to freeze water in the air by cold energy of LNG; the air-water separator is used for removing solid water in the air; the dehydrated air is liquefied through the first CO2 liquefaction heat exchanger and the second CO2 liquefaction heat exchanger; the first air-CO2 separator is used for separating liquid CO2 in the first CO2 liquefaction heat exchanger; the second air-CO2 separator is used for separating liquid CO2 in the second CO2 liquefaction heat exchanger; and the first liquid CO2 storage tank is used for storing liquid CO2.

7. The cascade cold storage device for storing and delivering LNG cold energy using multiple phase change materials according to claim 6, characterized in that, The CO2 capture, liquefaction and energy storage system further comprises a second liquid CO2 storage tank connected with the first liquid CO2 storage tank, and is provided with a liquid CO2 heat exchanger connected with the second liquid CO2 storage tank; and the liquid CO2 heat exchanger is used for releasing cold energy. 8.The cascade cold storage device for storing and delivering LNG cold energy by using multiple phase change materials according to claim 1, characterized in that, The LNG sent into the low-temperature power generation system is derived from an ultralow-temperature phase change material energy storage system, a low-temperature phase change material energy storage system, a CO2 capture, liquefaction and energy storage system and / or an LNG tank. 9.The cascade cold storage device for storing and delivering LNG cold energy by using multiple phase change materials according to claim 8, characterized in that, The low-temperature power generation system comprises an LNG-ORC working medium heat exchanger, through which LNG transfers cold energy to ORC working medium; an ORC working medium-seawater or low-temperature heat source heat exchanger and an ORC expander connected with the LNG-ORC working medium heat exchanger, and ORC working medium pumped into the ORC working medium-seawater or low-temperature heat source heat exchanger is warmed and then enters the ORC expander to generate power.

10. The cascade cold storage device for storing and delivering LNG cold energy using multiple phase change materials according to claim 9, wherein, The low-temperature power generation system comprises an LNG-ORC working medium heat exchanger, through which LNG transfers cold energy to ORC working medium; an ORC working medium-seawater or low-temperature heat source heat exchanger and an ORC expander connected with the LNG-ORC working medium heat exchanger, and ORC working medium pumped into the ORC working medium-seawater or low-temperature heat source heat exchanger is warmed and then enters the ORC expander to generate power. The low-temperature power generation system comprises an LNG-ORC working medium heat exchanger, through which LNG transfers cold energy to ORC working medium; an ORC working medium-seawater or low-temperature heat source heat exchanger and an ORC expander connected with the LNG-ORC working medium heat exchanger, and ORC working medium pumped into the ORC working medium-seawater or low-temperature heat source heat exchanger is warmed and then enters the ORC expander to generate power.

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