Novel LNG (Liquefied Natural Gas) medium-grade cold energy extraction and storage system

Abstract

The invention discloses a novel LNG medium-grade cold energy extraction and storage system, and belongs to the technical field of LNG cold energy utilization, the novel LNG medium-grade cold energy extraction and storage system comprises a cold energy extraction module and a cold energy storage module, the cold energy extraction module adopts a cascade circulating reducing coupling type heat exchange structure, and selects an adaptive circulating working medium to recover cold energy in LNG; the cold energy storage module is of a modularized cold energy storage structure, and cold energy in the cycle working medium is stored in a phase change energy storage material. By the adoption of the novel LNG medium-grade cold energy extraction and storage system, the problem that the cold energy extraction and storage efficiency is low can be solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of LNG cold energy utilization, in particular to a novel LNG medium-grade cold energy extraction and storage system. BACKGROUND

[0002] LNG cold energy utilization, as a new energy-saving technology, mainly refers to the use of low-temperature energy released during the conversion of liquefied natural gas into gaseous state for production and industrial application, and plays a key role in providing efficient and low-carbon cold source solutions for the energy industry. It has become one of the important supports for promoting green energy transformation and reducing carbon emissions. The efficient use of LNG cold energy not only can significantly improve energy utilization efficiency, but also can provide stable cold source for related industries and reduce dependence on traditional energy, thereby promoting the optimization and sustainable development of energy structure. Due to the important role of LNG cold energy in energy saving and emission reduction and green energy transformation, its utilization efficiency and technology development are directly related to the realization of energy security and environmental protection goals. At present, LNG cold energy extraction technology has been relatively mature, but there are still the following problems: 1. From the perspective of cold energy extraction, the current LNG high-grade cold energy (cold energy density > 120 kJ / (kg·℃)) and low-grade cold energy (cold energy density < 40 kJ / (kg·℃)) have formed a relatively perfect energy recovery application system, but the recovery of medium-grade cold energy, especially the part involving latent heat of phase change, has a significant technical gap, and the waste of cold energy is huge.

[0003] 2. From the perspective of cold energy storage, due to the thermal response lag of phase change energy storage materials, the actual cold energy storage efficiency is less than 45% of the design value.

[0004] 3. From the perspective of cold energy transportation, due to the fact that the existing transportation mode is mainly pipeline transportation, its inherent distance limitation and lack of networking result in that cold energy resources are difficult to realize efficient and flexible long-distance transportation and regional allocation, which objectively restricts the service coverage range and multi-scenario application potential of the cold energy network. SUMMARY

[0005] The purpose of the present application is to provide a novel LNG medium-grade cold energy extraction and storage system to solve the problem of low cold energy extraction and storage efficiency.

[0006] To achieve the above purpose, the present application provides a novel LNG medium-grade cold energy extraction and storage system, which comprises a cold energy extraction module and a cold energy storage module. The cold energy extraction module adopts a variable-diameter coupled heat exchange structure of cascade cycle, and selects a suitable circulating working medium to recover the cold energy in LNG. The cold energy storage module adopts a modular cold energy storage structure, and stores the cold energy in the circulating working medium into the phase change energy storage material.

[0007] Preferably, the variable-diameter coupled heat exchange structure comprises a shell one, the upper end of the shell one is sequentially provided with an LNG inlet and a circulating working medium outlet one, and the lower end is sequentially provided with a circulating working medium inlet one and an NG outlet.

[0008] Preferably, the inside of the shell one is provided with a chamber one and a gasification chamber on one side, and a chamber two and a chamber three on the other side; The chamber one and the gasification chamber are separated by a baffle plate, and the chamber one and the gasification chamber are provided with a left tube plate on one side, and the baffle plate is connected with the shell one and the left tube plate, and the left tube plate is connected with the shell one and the baffle plate. The chamber two and the chamber three are separated by a baffle plate, and the chamber two and the chamber three are provided with a right tube plate on one side, and the baffle plate is connected with the shell one and the right tube plate, and the right tube plate is connected with the shell one and the baffle plate.

[0009] Preferably, the part between the left tube plate and the right tube plate is divided into an upper layer and a lower layer by a partition plate, and the partition plate is connected with the shell one and the right tube plate, and the upper layer comprises a plurality of small-diameter heat exchange tubes and a plurality of upper baffle plates, and the lower layer comprises a plurality of large-diameter heat exchange tubes and a plurality of lower baffle plates.

[0010] Preferably, a part of the upper baffle plate is connected with the shell one, and the other part is connected with the partition plate, and the upper baffle plate is alternately distributed in the upper layer. A part of the lower baffle plate is connected with the shell one, and the other part is connected with the partition plate, and the lower baffle plate is alternately distributed in the lower layer.

[0011] Preferably, the upper baffle plate is provided with through holes matched with the small-diameter heat exchange tubes, and the small-diameter heat exchange tubes pass through the upper baffle plate and are embedded on the left tube plate and the right tube plate; The lower baffle plate is provided with through holes matched with the large-diameter heat exchange tubes, and the large-diameter heat exchange tubes pass through the lower baffle plate and are embedded on the left tube plate and the right tube plate.

[0012] Preferably, the LNG flows from the LNG inlet, sequentially flows through the chamber one, a part of the small-diameter heat exchange tubes, the chamber two, another part of the small-diameter heat exchange tubes, the gasification chamber, the large-diameter heat exchange tubes, the chamber three, and finally flows out from the NG outlet; The circulating working medium flows from the circulating working medium inlet one, sequentially exchanges heat with the large-diameter heat exchange tubes and the small-diameter heat exchange tubes, and finally flows out from the circulating working medium outlet one.

[0013] Preferably, the cold energy storage structure comprises a plurality of storage units, and each storage unit comprises a shell two, and the inside of the shell two is provided with a plurality of phase change energy storage assemblies, and each phase change energy storage assembly comprises a phase change energy storage material and a heat preservation material arranged on the surface of the phase change energy storage material, and the phase change energy storage assemblies are orthogonally distributed with pipelines arranged around the phase change energy storage assemblies.

[0014] Preferably, the storage units are connected in sequence to form a cold energy storage structure, the first storage unit is provided with the second circulating working medium inlet and the energy medium outlet, and the last storage unit is provided with the second circulating working medium outlet and the energy medium inlet.

[0015] Preferably, the circulating working medium flowing out of the first circulating working medium outlet enters the pipeline from the second circulating working medium inlet to exchange heat with the phase change energy storage material, and finally flows out of the second circulating working medium outlet. The energy medium flows in from the energy medium inlet to exchange heat with the phase change energy storage material, and finally flows out of the energy medium outlet.

[0016] Therefore, the LNG medium-grade cold energy extraction and storage system has the following beneficial effects: The application innovatively designs a variable-diameter coupled heat exchange structure of cascade cycles, which can efficiently extract the medium-grade cold energy released in the LNG gasification process; in view of the problems of medium-grade cold energy storage and transportation, the modular cold energy storage structure is innovatively adopted, which can efficiently store cold energy, and the transportation of cold energy is more convenient and economical, thereby expanding the transportation radius and utilization mode of LNG cold energy.

[0017] The technical solutions of the application will be further described in detail below with reference to the drawings and embodiments. DESCRIPTION OF DRAWINGS

[0018] Figure 1 It is a perspective view of a cold energy extraction module of an embodiment of the application. Figure 2 It is a schematic view of an upper baffle of an embodiment of the application. Figure 3 It is a schematic view of a lower baffle of an embodiment of the application. Figure 4 It is a schematic view of a left tube plate of an embodiment of the application. Figure 5 It is a schematic view of a right tube plate of an embodiment of the application. Figure 6 It is a perspective view of a cold energy storage module of an embodiment of the application.

[0019] REFERENCE SIGNS 1, shell one; 2, LNG inlet; 3, NG outlet; 4, circulating working medium inlet one; 5, circulating working medium outlet one; 6, chamber one; 7, chamber two; 8, gasification chamber; 9, chamber three; 10, left tube plate; 11, right tube plate; 12, small-diameter heat exchange tube; 13, large-diameter heat exchange tube; 14, upper baffle; 15, lower baffle; 16, baffle; 17, baffle; 18, baffle; 19, shell two; 20, phase change energy storage material; 21, thermal insulation material; 22, pipeline; 23, circulating working medium inlet two; 24, circulating working medium outlet two; 25, energy using medium inlet; 26, energy using medium outlet; 27, phase change energy storage assembly. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the embodiments of the present application are further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the embodiments of the present application and not to limit the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present application. The examples of the embodiments are shown in the drawings, wherein the same or similar reference signs represent the same or similar elements or elements having the same or similar functions throughout.

[0021] It should be noted that the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or server comprising a series of steps or units does not have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0022] Similar reference signs and letters represent similar items in the following drawings, therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0023] In the description of the present application, it should be noted that the terms "upper", "lower", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the present application is usually placed, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, therefore, it cannot be understood as a limitation on the present application.

[0024] In the description of the present application, it is also necessary to explain that, unless otherwise explicitly specified and limited, the terms "arrangement", "installation", "connection" should be understood broadly, for example, can be fixedly connected, can also be detachably connected, or integrally connected; can be mechanically connected, can also be electrically connected; can be directly connected, can also be indirectly connected through an intermediate medium, can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0025] Embodiment As Figures 1-6 shown, the present embodiment provides a new LNG grade cold energy extraction and storage system, which comprises a cold energy extraction module and a cold energy storage module.

[0026] The cold energy extraction module adopts a cascaded, variable-diameter coupled heat exchange structure, selecting a suitable circulating working fluid to recover cold energy from LNG. The selected working fluid, compatible with the LNG's temperature range (-120℃ to -80℃), effectively extracts medium-grade cold energy from the LNG. The variable-diameter coupled heat exchange structure includes a shell 1. The upper end of the shell 1 has an LNG inlet 2 and a circulating working fluid outlet 5, while the lower end has a circulating working fluid inlet 4 and an LNG outlet 3. Inside the shell 1, one side has a chamber 6 and a vaporization chamber 8, and the other side has a chamber 7 and a chamber 9. Chamber 6 and vaporization chamber 8 are separated vertically by a baffle plate 16. A left tube sheet 10 is located on one side of chamber 6 and vaporization chamber 8. The baffle plate 16 is connected to both the shell 1 and the left tube sheet 10, and the left tube sheet 10 is connected to both the shell 1 and the baffle plate 16. Chambers 2 (7) and 3 (9) are separated vertically by baffles 17. A right tube sheet 11 is provided on one side of each chamber. Baffles 17 are connected to shell 1 and the right tube sheet 11, respectively. The right tube sheet 11 is connected to shell 1 and baffles 17. The portion between the left tube sheet 10 and the right tube sheet 11 is divided into upper and lower layers by a partition 18, which is connected to shell 1 and the right tube sheet 11. The upper layer includes several small-diameter heat exchange tubes 12 and several upper baffles 14, while the lower layer includes several large-diameter heat exchange tubes 13 and several lower baffles 15. Part of the upper baffles 14 is connected to shell 1, and the other part is connected to the partition 18. The upper baffles 14 are alternately distributed in the upper layer. Part of the lower baffles 15 is connected to shell 1, and the other part is connected to the partition 18. The lower baffles 15 are alternately distributed in the lower layer. The upper baffle plate 14 is provided with through holes adapted to the small-diameter heat exchange tubes 12. The small-diameter heat exchange tubes 12 pass through the upper baffle plate 14 and are embedded in the left tube sheet 10 and the right tube sheet 11. The lower baffle plate 15 is provided with through holes adapted to the large-diameter heat exchange tubes 13. The large-diameter heat exchange tubes 13 pass through the lower baffle plate 15 and are embedded in the left tube sheet 10 and the right tube sheet 11. LNG flows in from the LNG inlet 2, and flows sequentially through chamber 1 6, a portion of the small-diameter heat exchange tubes 12, chamber 2 7, another portion of the small-diameter heat exchange tubes 12, vaporization chamber 8, large-diameter heat exchange tubes 13, chamber 3 9, and finally flows out from the LNG outlet 3. The circulating working fluid flows in from the circulating working fluid inlet 4, and exchanges heat sequentially with the large-diameter heat exchange tubes 13 and the small-diameter heat exchange tubes 12, and finally flows out from the circulating working fluid outlet 5. LNG undergoes a liquid-to-gas conversion process in vaporization chamber 8. Based on the volume change law of LNG during the phase change process, the liquid phase tube side uses small-diameter heat exchange tubes 12, and the gas phase tube side uses large-diameter heat exchange tubes 13. Utilizing the different tube diameters provides a buffer for volume changes, controlling the phase change process within a variable-diameter coupled heat exchange structure. This utilizes the latent heat of phase change and achieves efficient and stable extraction of LNG cold energy. The upper baffle 14 and lower baffle 15 serve two purposes: firstly, they facilitate repeated convection heat exchange during the heat exchange process; secondly, they provide support for the small-diameter heat exchange tubes 12 and the large-diameter heat exchange tubes 13.

[0027] The cold energy storage module adopts a modular cold energy storage structure, storing the cold energy in the circulating working fluid into the phase change energy storage material 20. The cold energy storage structure includes several storage units, each including a housing 19. Inside the housing 19 are several phase change energy storage components 27. Each phase change energy storage component 27 includes the phase change energy storage material 20 and insulation material 21 disposed on the surface of the phase change energy storage material 20. The phase change energy storage components 27 are orthogonally distributed with the pipes 22 surrounding them. The storage units are connected sequentially to form the cold energy storage structure. The first storage unit has a circulating working fluid inlet 23 and an energy consumption medium outlet 26, and the last storage unit has a circulating working fluid outlet 24 and an energy consumption medium inlet 25. The circulating working fluid flowing out of the outlet 25 enters the pipes 22 through the inlet 23 to exchange heat with the phase change energy storage material 20, and finally flows out through the outlet 24. The energy-consuming medium flows into the energy-consuming medium inlet 25 to exchange heat with the phase change energy storage material 20, and finally flows out from the energy-consuming medium outlet 26. The phase change energy storage material 20 is temperature-matched to the grade of cold energy in LNG and is placed in a modular cold energy storage structure. After the low-temperature circulating working fluid enters the cold energy storage structure, it transfers cold energy to the phase change energy storage material 20 and then leaves the cold energy storage structure. When the temperature of the phase change energy storage material 20 drops to a threshold, the flow of circulating working fluid is stopped.

[0028] This invention is used in three stages: Cold energy extraction stage: LNG flows in from LNG inlet 2, sequentially through chamber 1 (6), a portion of small-diameter heat exchange tubes 12, chamber 2 (7), another portion of small-diameter heat exchange tubes 12, vaporization chamber 8, large-diameter heat exchange tubes 13, and chamber 3 (9), finally flowing out from LNG outlet 3. The circulating working fluid flows in from circulating working fluid inlet 4, sequentially exchanging heat with large-diameter heat exchange tubes 13 and small-diameter heat exchange tubes 12, finally flowing out from circulating working fluid outlet 5.

[0029] Cold energy storage stage: The circulating working fluid flowing out of the circulating working fluid outlet 5 enters the pipeline 22 through the circulating working fluid inlet 23 to exchange heat with the phase change energy storage material 20, and finally flows out from the circulating working fluid outlet 24. When the temperature of the phase change energy storage material 20 drops to the threshold, the flow of circulating working fluid is stopped.

[0030] Cold energy utilization stage: Based on the cold energy demand, select an appropriate number of storage units, transport them to the cooling unit, and the energy-consuming medium flows in from the energy-consuming medium inlet 25 to exchange heat with the phase change energy storage material 20, and finally flows out from the energy-consuming medium outlet 26. After the cold energy storage module is depleted, it is transported back for cold energy storage.

[0031] Therefore, the present invention employs the above-mentioned novel LNG medium-grade cold energy extraction and storage system, which can solve the problem of low efficiency in cold energy extraction and storage.

[0032] It should be pointed out finally that the above embodiments are only used to illustrate the technical solutions of the present application but not to limit it, and although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can still be modified or replaced equivalently, and these modifications or equivalent replacements should not make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. A novel LNG medium-grade cold energy extraction and storage system, characterized in that: It includes a cold energy extraction module and a cold energy storage module. The cold energy extraction module adopts a cascaded, variable-diameter coupled heat exchange structure to select a compatible circulating working fluid to recover cold energy from LNG. The cold energy storage module adopts a modular cold energy storage structure to store the cold energy in the circulating working fluid into a phase change energy storage material.

2. The novel LNG medium-grade cold energy extraction and storage system according to claim 1, characterized in that: The variable diameter coupled heat exchange structure includes a shell, with an LNG inlet and a circulating working fluid outlet at the upper end of the shell, and a circulating working fluid inlet and an NG outlet at the lower end.

3. A novel LNG medium-grade cold energy extraction and storage system according to claim 2, characterized in that: The shell has a chamber 1 and a vaporization chamber on one side, and a chamber 2 and a chamber 3 on the other side; The first chamber and the vaporization chamber are separated by baffles. A left tube sheet is provided on one side of the first chamber and the vaporization chamber. The baffles are connected to the first shell and the left tube sheet respectively. The left tube sheet is connected to the first shell and the baffles respectively. Chamber 2 and Chamber 3 are separated by baffles. A right tube sheet is provided on one side of Chamber 2 and Chamber 3. The baffles are connected to the shell 1 and the right tube sheet respectively. The right tube sheet is connected to the shell 1 and the baffle respectively.

4. A novel LNG medium-grade cold energy extraction and storage system according to claim 3, characterized in that: The section between the left tube sheet and the right tube sheet is divided into an upper layer and a lower layer by a partition. The partition is connected to the shell and the right tube sheet respectively. The upper layer includes several small-diameter heat exchange tubes and several upper baffles, and the lower layer includes several large-diameter heat exchange tubes and several lower baffles.

5. A novel LNG medium-grade cold energy extraction and storage system according to claim 4, characterized in that: One part of the upper baffle is connected to the shell, and the other part is connected to the partition. The upper baffles are alternately distributed in the upper layer. One part of the lower baffle is connected to the shell, and the other part is connected to the partition. The lower baffles are alternately distributed in the lower layer.

6. A novel LNG medium-grade cold energy extraction and storage system according to claim 5, characterized in that: The upper baffle plate is provided with through holes that are compatible with small-diameter heat exchange tubes. The small-diameter heat exchange tubes pass through the upper baffle plate and are embedded in the left tube sheet and the right tube sheet. The lower baffle plate is provided with through holes that are compatible with large-diameter heat exchange tubes. The large-diameter heat exchange tubes pass through the lower baffle plate and are embedded in the left tube sheet and the right tube sheet.

7. A novel LNG medium-grade cold energy extraction and storage system according to claim 6, characterized in that: LNG flows in from the LNG inlet, and flows sequentially through chamber one, a portion of small-diameter heat exchange tubes, chamber two, another portion of small-diameter heat exchange tubes, the vaporization chamber, the large-diameter heat exchange tubes, chamber three, and finally flows out from the LNG outlet; The circulating working fluid flows in from the circulating working fluid inlet, exchanges heat with the large-diameter heat exchange tubes and the small-diameter heat exchange tubes in sequence, and finally flows out from the circulating working fluid outlet.

8. A novel LNG medium-grade cold energy extraction and storage system according to claim 7, characterized in that: The cold energy storage structure includes several storage units. Each storage unit includes a housing, and the interior of the housing contains several phase change energy storage components. Each phase change energy storage component includes a phase change energy storage material and an insulation material disposed on the surface of the phase change energy storage material. The phase change energy storage components and the pipelines disposed around the phase change energy storage components are orthogonally distributed.

9. A novel LNG medium-grade cold energy extraction and storage system according to claim 8, characterized in that: The storage units are connected in sequence to form a cold energy storage structure. The first storage unit is equipped with a second circulating working fluid inlet and an energy consumption medium outlet, and the last storage unit is equipped with a second circulating working fluid outlet and an energy consumption medium inlet.

10. A novel LNG medium-grade cold energy extraction and storage system according to claim 9, characterized in that: The circulating working fluid flowing out of the first outlet enters the pipeline through the second inlet to exchange heat with the phase change energy storage material, and finally flows out from the second outlet. The energy-consuming medium flows in from the energy-consuming medium inlet to exchange heat with the phase change energy storage material, and finally flows out from the energy-consuming medium outlet.

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