A natural gas peaking system and method

Abstract

The application provides a natural gas peak shaving system and method. The natural gas peak shaving system comprises a high-pressure natural gas pipeline network, a first storage device, a phase change unit, a cold storage device and a heat storage device. The first storage device is connected with the high-pressure natural gas pipeline network and is used for storing liquid natural gas. The phase change unit is used for storing energy storage working medium, and the energy storage working medium can exchange heat with natural gas flowing from the high-pressure natural gas pipeline network to the first storage device, so as to realize gas-liquid phase change of the natural gas and gas-solid phase change of the energy storage working medium. The cold storage device can exchange heat with the natural gas, can absorb cold energy carried by the natural gas and can transfer cold energy to the natural gas. The heat storage device can exchange heat with the natural gas and / or the energy storage working medium, can absorb heat energy carried by the energy storage working medium and can transfer heat energy to the energy storage working medium, and can transfer heat energy to the natural gas. The natural gas peak shaving system can not only reduce energy consumption in the natural gas liquefaction process, but also reduce energy waste in the natural gas gasification process.

Description

Technical Field

[0001] This application relates to the field of energy transportation and storage technology, specifically to a natural gas peak-shaving system and method. Background Technology

[0002] Natural gas supply security is a crucial component of energy security. Natural gas storage and peak-shaving systems are effective means to address short- and medium-term natural gas supply shortages, ensure secure supply, and maintain stable market operations. Liquefied natural gas (LNG) is an important peak-shaving method; however, LNG liquefaction equipment is complex and requires significant investment. Furthermore, the liquefaction process consumes a large amount of energy, while the gasification process releases substantial amounts of cold energy, resulting in significant energy waste. Summary of the Invention

[0003] In view of this, this application provides a natural gas peak-shaving system that solves the problem of energy waste during the natural gas-liquid conversion process. This application also provides a natural gas peak-shaving method, implemented using the aforementioned natural gas peak-shaving system.

[0004] To achieve the above objectives, this application provides the following technical solution:

[0005] A natural gas peak-shaving system, comprising:

[0006] High-pressure natural gas pipeline network;

[0007] The first storage device is connected to the high-pressure natural gas pipeline network and is used to store liquefied natural gas;

[0008] A phase change unit is used to store an energy storage medium, and the energy storage medium can exchange heat with the natural gas moving from the high-pressure natural gas pipeline to the first storage device to realize the gas-liquid phase change of natural gas and the gas-solid phase change of the energy storage medium.

[0009] A cold storage device that can exchange heat with the natural gas, absorb the cold energy carried by the natural gas, and transfer cold energy to the natural gas;

[0010] The thermal storage device is capable of exchanging heat with the natural gas and / or the energy storage medium, absorbing the thermal energy carried by the energy storage medium and transferring thermal energy to the energy storage medium, and transferring thermal energy to the natural gas.

[0011] Optionally, the cold storage device includes a cold storage tank, a recooler, a hot storage tank, and a cold energy recovery unit connected in sequence; wherein, the cold storage tank is used to store the cold storage medium, the recooler is used to transfer the cold energy carried by the cold storage medium to the natural gas moving to the first storage tank via the high-pressure natural gas pipeline, the hot storage tank is used to store the hot storage medium, and the cold energy recovery unit is used to absorb the cold energy carried by the natural gas moving out of the first storage tank.

[0012] Optional, also includes:

[0013] The second memory is used to store the energy storage medium;

[0014] A compressor unit is disposed between the first memory and the second memory for compressing the energy storage medium;

[0015] A first expander unit is disposed between the first memory and the second memory for expanding the energy storage medium;

[0016] A second expander is installed between the first storage device and the low-pressure natural gas pipeline network for expanding the natural gas;

[0017] A generator is connected to the first expander unit and the second expander.

[0018] Optional,

[0019] The compressor unit includes a low-pressure compressor, a medium-pressure compressor, and a high-pressure compressor connected in sequence.

[0020] The first expander unit includes a high-pressure expander, a medium-pressure expander, and a low-pressure expander connected in sequence.

[0021] Optionally, the thermal storage device includes:

[0022] The first thermal storage unit is capable of exchanging heat with the natural gas and the energy storage medium, absorbing the heat energy carried by the energy storage medium as it moves from the low-pressure compressor to the medium-pressure compressor, and transferring heat energy to the natural gas as it moves from the first storage unit to the second expander.

[0023] The second thermal storage unit can exchange heat with the energy storage medium, absorb the heat energy carried by the energy storage medium moving from the medium-pressure compressor to the high-pressure compressor, and transfer heat energy to the energy storage medium moving from the high-pressure expander to the medium-pressure expander.

[0024] The third thermal storage unit can exchange heat with the energy storage medium, absorb the heat energy carried by the energy storage medium moving from the high-pressure compressor to the second memory, and transfer heat energy to the energy storage medium moving from the second memory to the high-pressure expander.

[0025] Optionally, the first thermal storage unit includes a first thermal storage hot tank, a first reheater, a first thermal storage cold tank, and a first heat recovery unit connected in sequence; the second thermal storage unit includes a second thermal storage hot tank, a second reheater, a second thermal storage cold tank, and a second heat recovery unit connected in sequence; and the third thermal storage unit includes a third thermal storage hot tank, a third reheater, a third thermal storage cold tank, and a third heat recovery unit connected in sequence.

[0026] Optional, also includes:

[0027] A vaporizer is disposed between the second memory and the high-pressure expander;

[0028] The cold energy collector can transfer cold energy to the energy storage medium that moves from the high-pressure compressor to the second memory.

[0029] Optionally, it also includes a precooler, wherein the first inlet of the precooler is connected to the first memory, the first outlet of the precooler is connected to the inlet of the second expander, the second inlet of the precooler is connected to the outlet of the second expander, and the second outlet of the precooler is connected to the low-pressure natural gas pipeline network.

[0030] Optionally, it also includes a natural gas pressure regulating device disposed between the high-pressure natural gas pipeline network and the low-pressure natural gas pipeline network. The cold energy collector is capable of absorbing the cold energy of the natural gas moving from the natural gas pressure regulating device to the low-pressure natural gas pipeline network, and is also capable of absorbing the cold energy of the natural gas moving from the second expander to the low-pressure natural gas pipeline network.

[0031] A natural gas peak-shaving method, implemented using the aforementioned natural gas peak-shaving system, includes the following steps:

[0032] When natural gas is in a low-consumption period and also during a low-consumption period for electricity, the natural gas removed from the high-pressure natural gas pipeline is converted into liquefied natural gas by the phase change unit and stored in the first memory. During the phase change process, the energy storage medium in the phase change unit sublimates, and the gaseous energy storage medium is compressed by the compressor unit and condensed into liquefied energy storage medium, which is then stored in the second memory.

[0033] When natural gas consumption is at its peak and electricity consumption is also at its peak, the liquid natural gas in the first storage device is converted into gaseous natural gas by the phase change unit, and then expanded into low-pressure gaseous natural gas by the second expander. The low-pressure gaseous natural gas is transported to the low-pressure natural gas pipeline network to cope with the peak gas consumption period. The liquid energy storage medium in the second storage device is expanded into low-pressure gaseous energy storage medium by the gasifier and the first expander unit. The low-pressure gaseous energy storage medium is condensed and stored in the phase change unit by the phase change unit. The generator uses the energy generated by the expansion of the first expander unit and the second expander unit to generate electricity to cope with the peak electricity consumption period.

[0034] The natural gas peak-shaving system provided in this application converts high-pressure natural gas into liquefied natural gas and stores it in a first storage device when natural gas demand is low. When natural gas demand is high, the liquefied natural gas is converted into high-pressure gaseous gas and then expanded into gaseous natural gas by an expander. During the gas-liquid phase change of natural gas, the energy of the phase change process is recovered and reused through the phase change process of the energy storage medium by the phase change unit. This can reduce the energy consumed in the natural gas liquefaction process and reduce the energy waste in the natural gas gasification process. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of the natural gas peak-shaving system provided in this embodiment;

[0037] Figure 2 for Figure 1 Enlarged view of point A in the middle;

[0038] Figure 3 for Figure 1 Enlarged view at point B in the middle;

[0039] Figure 4 for Figure 1 Enlarged view of point C in the middle.

[0040] exist Figures 1-4 middle:

[0041] 1-High-pressure natural gas pipeline network; 2-First storage unit; 3-Phase change unit; 4-Cold storage device; 5-First thermal storage unit; 6-Second thermal storage unit; 7-Third thermal storage unit; 8-Compressor unit; 9-First expander unit; 10-Second expander; 11-Second storage unit; 12-Gasifier; 13-Cold energy collector; 14-Precooler; 15-Natural gas pressure regulating device; 16-Low-pressure natural gas pipeline network.

[0042] 401-Cold storage tank, 402-Recooler, 403-Hot storage tank, 404-Cold energy recovery unit, 501-First hot storage tank, 502-First reheater, 503-First cold storage tank, 504-First heat recovery unit, 601-Second hot storage tank, 602-Second reheater, 603-Second cold storage tank, 604-Second heat recovery unit, 701-Third hot storage tank, 702-Third reheater, 703-Third cold storage tank, 704-Third heat recovery unit, 801-Low-pressure compressor, 802-Medium-pressure compressor, 803-High-pressure compressor, 901-High-pressure expander, 902-Medium-pressure expander, 903-Low-pressure expander. Detailed Implementation

[0043] This application provides a natural gas peak-shaving system. This application also provides a natural gas peak-shaving method, implemented according to the aforementioned natural gas peak-shaving system.

[0044] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0045] like Figures 1 to 4 As shown in the embodiment of this application, a natural gas peak-shaving system is provided. The natural gas peak-shaving system includes a high-pressure natural gas pipeline network 1, a first storage unit 2, a phase change unit 3, a cold storage device 4, and a heat storage device. The first storage unit 2 is connected to the high-pressure natural gas pipeline network 1 and is used to store liquefied natural gas. The phase change unit 3 is used to store an energy storage medium, and the energy storage medium can exchange heat with the natural gas moving from the high-pressure natural gas pipeline network 1 to the first storage unit 2 to realize the gas-liquid phase change of natural gas and the gas-solid phase change of the energy storage medium. The cold storage device 4 can exchange heat with natural gas, absorb the cold energy carried by the natural gas, and transfer the cold energy to the natural gas. The heat storage device can exchange heat with natural gas and / or the energy storage medium, absorb the heat energy carried by the energy storage medium, transfer the heat energy to the energy storage medium, and transfer the heat energy to the natural gas.

[0046] Specifically, when natural gas consumption is at its lowest point, the high-pressure gaseous natural gas in the high-pressure natural gas pipeline 1 is transferred to the first storage unit 2. During the transfer to the first storage unit 2, the cold storage device 4 exchanges heat with the natural gas, transferring cold energy to the natural gas, causing the temperature of the natural gas to drop. Then, the natural gas passes through the phase change unit 3, where the solid energy storage medium sublimates into a gaseous energy storage medium. During the sublimation process, the energy storage medium continues to transfer cold energy to the gaseous natural gas, thereby turning the gaseous natural gas into liquefied natural gas. The liquefied natural gas is then stored in the first storage unit 2 to achieve natural gas storage. When natural gas is in peak demand, the liquefied natural gas stored in the first storage unit 2 is extracted and converted into gaseous natural gas through the phase change unit 3. When it flows through the cold storage device 4, it undergoes heat exchange with the cold storage device 4. The liquefied natural gas transfers the cold energy it carries to the cold storage device 4 for storage, thereby realizing the recovery of cold energy in the liquefied natural gas. Furthermore, the heat exchange device of the phase change unit 3 can recover the cold energy during the phase change of the liquefied natural gas. The heat exchange device can transfer the cold energy to the energy storage medium, thereby realizing the recovery of cold energy.

[0047] It should be noted that, in order to achieve the desired heat exchange rate between natural gas and the energy storage medium, a heat transfer medium can be selected within phase change unit 3. The energy storage medium is typically carbon dioxide, and the corresponding heat transfer medium is a liquid with excellent compatibility with carbon dioxide, such as ethanol, propane, or low-temperature lubricating oil. Here, carbon dioxide is chosen as the energy storage medium because it offers good safety and stability. Furthermore, in the event of a fire around the natural gas peak-shaving system, carbon dioxide can extinguish the fire, further enhancing the safety of the natural gas peak-shaving system.

[0048] In the natural gas peak-shaving system described above, when natural gas demand is low, the phase change unit 3 converts natural gas into liquefied natural gas and stores it in the first storage device 2. When natural gas demand is high, the liquefied natural gas is converted into gaseous natural gas through the phase change unit 3 and then expanded into low-pressure gaseous natural gas through an expander. During the gas-liquid phase change of natural gas, the energy of the phase change process of natural gas is recovered and reused through the phase change process of the energy storage medium via the phase change process of the phase change unit 3. This can reduce the energy consumed in the natural gas liquefaction process and reduce the energy waste in the natural gas gasification process.

[0049] In some embodiments, the cold storage device 4 includes a cold storage tank 401, a recooler 402, a hot storage tank 403, and a cold energy recovery device 404 connected in sequence; wherein, the cold storage tank 401 is used to store the cold storage medium, the recooler 402 is used to transfer the cold energy carried by the cold storage medium to the natural gas moving from the high-pressure natural gas pipeline 1 to the first storage 2, the hot storage tank 403 is used to store the hot storage medium, and the cold energy recovery device 404 is used to absorb the cold energy carried by the natural gas moving out of the first storage 2. Specifically, when natural gas consumption is low, during the process of natural gas flowing from the high-pressure natural gas pipeline 1 to the first storage tank 2, the cold storage medium in the cold storage tank 401 will flow to the hot storage tank 403 through the recooler 402. Gaseous natural gas will also flow through the recooler 402 and undergo heat conduction with the cold storage medium flowing through the recooler 402 to transfer the cold energy in the storage medium to the natural gas and reduce the temperature of the natural gas. When natural gas consumption is high, liquefied natural gas flows out of the first storage tank 2, and the hot storage medium in the hot storage tank 403 will flow to the cold storage tank 401 through the cold energy recovery device 404. The liquefied natural gas will also flow through the cold energy recovery device 404 and undergo heat conduction with the hot storage medium flowing through the cold energy recovery device 404 to transfer the cold energy in the natural gas to the storage medium.

[0050] Here, the cold storage device 4 includes a cold storage tank 401, a recooler 402, a hot storage tank 403, and a cold energy recovery device 404 connected in sequence. It can recover the remaining cold energy carried by the liquefied natural gas after gasification and use the recovered cold energy for pre-cooling and cooling before the gaseous natural gas is liquefied, so as to realize the recovery and utilization of cold energy and save energy.

[0051] In some embodiments, the natural gas peak-shaving system further includes a second storage unit 11, a compressor unit 8, a first expander unit 9, a second expander 10, and a generator. The second storage unit 11 is used to store the energy storage medium; the compressor unit 8 is disposed between the first storage unit 2 and the second storage unit 11 and is used to compress the energy storage medium; the first expander unit 9 is disposed between the first storage unit 2 and the second expander 11 and is used to expand the energy storage medium; the second expander 10 is disposed between the first storage unit 2 and the low-pressure natural gas pipeline network 16 and is used to expand natural gas; the generator is connected to the first expander unit 9 and the second expander 10. Specifically, when natural gas is at its peak, the liquid natural gas in the first storage unit 2 is converted into a gaseous state through the phase change unit 3, and then expanded into low-pressure gaseous natural gas by the second expander 10 to cope with the peak gas consumption period. At the same time, the residual pressure generated during the expansion of natural gas by the second expander 10 is recovered by the generator. The generator can generate electricity by recovering residual pressure, and at the same time, it can alleviate the pressure during peak electricity consumption and realize the power peak-shaving function. Meanwhile, during peak electricity demand, the energy storage medium in the second storage unit 11 flows to the first expander unit 9. While the first expander unit 9 is expanding the energy storage medium, the generator can also recover the residual pressure generated during the expansion of the energy storage medium to generate electricity, further alleviating the pressure during peak electricity demand.

[0052] In some embodiments, the compressor unit 8 includes a low-pressure compressor 801, a medium-pressure compressor 802, and a high-pressure compressor 803 connected in sequence; the first expander unit 9 includes a high-pressure expander 901, a medium-pressure expander 902, and a low-pressure expander 903 connected in sequence. Specifically, by configuring the compressor unit 8 as a low-pressure compressor 801, a medium-pressure compressor 802, and a high-pressure compressor 803, staged compression can save power consumption, improve volume utilization, and reduce exhaust temperature. Furthermore, by setting multiple heat storage units, the energy released during compression can be absorbed multiple times, increasing the total amount of energy recovered. By configuring the first expander unit 9 as a high-pressure expander 901, a medium-pressure expander 902, and a low-pressure expander 903, staged expansion can fully utilize the pressure generated during expansion, improving the generator's power generation efficiency. Moreover, the expansion process can absorb heat from the heat storage device multiple times, achieving thermal energy recovery and utilization.

[0053] In some embodiments, the thermal storage device includes a first thermal storage unit 5, a second thermal storage unit 6, and a third thermal storage unit 7. The first thermal storage unit 5 can exchange heat with natural gas and the energy storage medium, absorb the heat energy carried by the energy storage medium moving from the low-pressure compressor 801 to the medium-pressure compressor 802, and transfer heat energy to the natural gas moving from the first storage tank 2 to the second expander 10. The second thermal storage unit 6 can exchange heat with the energy storage medium, absorb the heat energy carried by the energy storage medium moving from the medium-pressure compressor 802 to the high-pressure compressor 803, and transfer heat energy to the energy storage medium moving from the high-pressure expander 901 to the medium-pressure expander 902. The third thermal storage unit 7 can exchange heat with the energy storage medium, absorb the heat energy carried by the energy storage medium moving from the high-pressure compressor 803 to the second storage tank 11, and transfer heat energy to the energy storage medium moving from the second storage tank 11 to the high-pressure expander 901.

[0054] Furthermore, in some embodiments, the first heat storage unit 5 includes a first heat storage tank 501, a first reheater 502, a first heat storage cold tank 503, and a first heat recovery unit 504 connected in sequence; the second heat storage unit 6 includes a second heat storage tank 601, a second reheater 602, a second heat storage cold tank 603, and a second heat recovery unit 604 connected in sequence; and the third heat storage unit 7 includes a third heat storage tank 701, a third reheater 702, a third heat storage cold tank 703, and a third heat recovery unit 704 connected in sequence.

[0055] Specifically, when natural gas and electricity consumption are both at their lowest, phase change unit 3 converts gaseous natural gas into liquefied natural gas. The solid energy storage medium within phase change unit 3 sublimates into a gaseous energy storage medium. This gaseous energy storage medium is then compressed sequentially by low-pressure compressor 801, medium-pressure compressor 802, and high-pressure compressor 803 before flowing to the second storage unit 11. During this staged compression process, the temperature and pressure of the energy storage medium increase after each compression. After each compression, the energy storage medium undergoes heat transfer with the cold thermal storage medium in the three thermal storage units in the first heat recovery unit 504, the second heat recovery unit 604, and the third heat recovery unit 704, respectively. The energy storage medium will transfer heat... The energy is transferred to the cold thermal storage medium in the three thermal storage units, and the cold thermal storage medium becomes a hot thermal storage medium, which is then stored in the three thermal storage tanks. When natural gas and electricity are in peak demand, the medium in the second storage unit 11 passes through the high-pressure expander 901 and the medium-pressure expander 902 in sequence. Before each expansion, heat is required to heat the energy storage medium. Before each expansion, the energy storage medium undergoes heat conduction with the hot thermal storage medium in the two thermal storage units in the third reheater 702 and the second reheater 602, respectively. The hot thermal storage medium transfers heat to the energy storage medium, and the hot thermal storage medium becomes a cold thermal storage medium, which is then stored in the three thermal storage tanks. In this way, heat energy is recovered and utilized, achieving energy conservation and emission reduction.

[0056] Here, the thermal storage device includes three thermal storage units. This configuration allows for the recovery of the heat energy generated after the energy storage medium is compressed, and the recovered heat energy is used to heat the energy storage medium before it expands, thus realizing the recovery and utilization of thermal energy and saving energy.

[0057] In some embodiments, the natural gas peak-shaving system further includes a vaporizer 12 and a cold energy collector 13. The vaporizer 12 is disposed between the second storage unit 11 and the high-pressure expander 901. The cold energy collector 13 can transfer cold energy to the energy storage medium moving from the high-pressure compressor 803 to the second storage unit 11. Specifically, the solid energy storage medium in the phase change unit 3 is sublimated into a gaseous energy storage medium. The gaseous energy storage medium is compressed by the compressor unit 8. The compressed gaseous energy storage medium exchanges heat with the cold energy collector 13, converting the gaseous energy storage medium into a liquid energy storage medium. The liquid energy storage medium is stored in the second storage unit 11. This conversion of the gaseous energy storage medium into a liquid energy storage medium and its storage in the second storage unit 11 improves the convenience of storing liquid energy storage medium in the second storage unit 11 and increases the amount of energy storage medium that the second storage unit 11 can store. Since the second memory 11 stores liquid energy storage medium, when the first expander 9 is used to expand the energy storage medium, the vaporizer 12 is used to vaporize the liquid energy storage medium in the second memory 11, and then the first expander 9 is used to expand the gaseous energy storage medium. After the first expander 9 expands the gaseous energy storage medium in stages, the gaseous energy storage medium is transformed into a solid energy storage medium and stored in the phase change unit 3. At the same time, the generator is used to recover the residual pressure during the expansion process of the first expander 9 to generate electricity.

[0058] In some embodiments, the natural gas peak-shaving system further includes a precooler 14. The first inlet of the precooler 14 is connected to the first storage tank 2, the first outlet of the precooler 14 is connected to the inlet of the second expander 10, the second inlet of the precooler 14 is connected to the outlet of the second expander 10, and the second outlet of the precooler 14 is connected to the low-pressure natural gas pipeline network 16. Natural gas flowing out of the first storage tank 2 flows through the precooler 14 and is then expanded by the second expander 10 to become depressurized natural gas. The depressurized natural gas flows through the precooler 14 again, and heat exchange occurs between the natural gas flowing out of the first storage tank 2 and the depressurized natural gas within the precooler 14. The depressurized natural gas transfers its cooling energy to the natural gas flowing out of the first storage tank 2, thereby appropriately raising the temperature of the depressurized natural gas for subsequent output to the low-pressure natural gas pipeline network 16.

[0059] In some embodiments, the natural gas peak-shaving system further includes a natural gas pressure regulating device 15 disposed between the high-pressure natural gas pipeline network 1 and the low-pressure natural gas pipeline network 16. A cold energy collector 13 is capable of absorbing the cold energy of the natural gas moving from the pressure regulating device 15 to the low-pressure natural gas pipeline network 16, and also absorbs the cold energy of the natural gas moving from the second expander 10 to the low-pressure natural gas pipeline network 16. Specifically, the natural gas pressure regulating device 15 can reduce the pressure of the high-pressure natural gas in the high-pressure natural gas pipeline network 1 to low-pressure natural gas and deliver it to the low-pressure natural gas pipeline network 16 for user use. During the pressure regulating process of the pressure regulating device 15, the high-pressure natural gas is depressurized and cooled to become low-pressure, low-temperature natural gas. Before flowing to the low-pressure natural gas pipeline network 16, the low-pressure, low-temperature natural gas exchanges heat with the cold energy collector 13, transferring the cold energy to the cold energy collector 13. Furthermore, the natural gas expanded from the second expander 10 is also at a lower temperature, and it also exchanges heat with the cold energy collector 13, transferring the cold energy to the cold energy collector 13. On the other hand, the cold energy collector 13 can also exchange heat with the energy storage medium. The cold energy collector 13 can transfer the absorbed cold energy to the energy storage medium to cool it. The cold energy collector 13 can realize the recovery and utilization of cold energy, reduce energy waste, and save energy and reduce emissions.

[0060] A natural gas peak-shaving method is implemented using the aforementioned natural gas peak-shaving system. Since the natural gas peak-shaving method is implemented using the aforementioned natural gas peak-shaving system, the beneficial effects brought about by the natural gas peak-shaving system can be found above and will not be repeated here.

[0061] The method includes the following steps:

[0062] When natural gas is in a low-demand period and electricity demand is also low, the natural gas removed from the high-pressure natural gas pipeline 1 is converted into liquid natural gas through the phase change unit 3 and stored in the first storage device 2. During the phase change process, the energy storage medium in the phase change unit 3 sublimates. The gaseous energy storage medium is compressed by the compressor unit 8 and condensed into liquid energy storage medium, which is then stored in the second storage device 11.

[0063] When natural gas is in peak demand and electricity demand, the liquid natural gas in the first storage unit 2 is converted into gaseous natural gas through the phase change unit 3, and then expanded into low-pressure gaseous natural gas through the second expander 10. The low-pressure gaseous natural gas is transported to the low-pressure natural gas pipeline network 16 to cope with the peak demand. The liquid energy storage medium in the second storage unit 11 is expanded into low-pressure gaseous energy storage medium through the vaporizer 12 and the first expander unit 9. The low-pressure gaseous energy storage medium is condensed and stored in the phase change unit 3. The generator uses the energy generated by the expansion of the first expander unit 9 and the second expander 10 to generate electricity to cope with the peak demand.

[0064] When natural gas is in a low-consumption period, and when electricity consumption is also in a low-consumption period, the high-pressure natural gas in the high-pressure natural gas pipeline 1 flows through the recooler 402 and exchanges heat with it. The cold storage medium in the cold storage device 4 transfers cold energy to the natural gas to cool it down initially. After the initial cooling, the natural gas flows through the phase change unit 3 and exchanges heat with the energy storage medium in the phase change unit 3 to cool the natural gas again, so as to liquefy the gaseous natural gas into liquid natural gas and store it in the first memory 2. During the natural gas liquefaction process in phase change unit 3, the energy storage medium in phase change unit 3 is sublimated from solid to gas. The gaseous energy storage medium is compressed by low-pressure compressor 801, and then exchanges heat with the heat storage medium in first heat storage unit 5 in first heat recovery unit 504. After that, it is compressed by medium-pressure compressor 802, and then exchanges heat with the heat storage medium in second heat storage unit 6 in second heat recovery unit 604. After that, it is compressed by high-pressure compressor 803, and then exchanges heat with the heat storage medium in third heat storage unit 7 in third heat recovery unit 704. After that, it exchanges heat with cold energy collector 13. Cold energy collector 13 transfers cold energy to the energy storage medium to convert the energy storage medium from gaseous to liquid state. Finally, the liquid energy storage medium is stored in second memory 11.

[0065] When natural gas is in peak gas consumption and electricity consumption, the liquefied natural gas in the first storage unit 2 flows out and passes through the cold energy recovery unit 404, where it exchanges heat with the cold storage medium in the energy storage device. The cold energy in the liquefied natural gas is transferred to the cold storage medium. Then, the natural gas flows sequentially through the precooler 14 and the first reheater 502. In the precooler 14, it exchanges heat with the natural gas that has been expanded by the second expander 10, and in the first reheater 502, it exchanges heat with the heat storage medium in the first heat storage unit 5. Then, it flows to the second expander 10 to expand the natural gas, cooling and depressurizing it. After that, the cooled and depressurized natural gas exchanges heat with the natural gas flowing out of the first storage unit 2 in the precooler 14. Then, the natural gas flows through the cold energy collector 13 and exchanges heat with it, transferring the cold energy to the cold energy collector 13. Finally, the natural gas flows to the low-pressure natural gas pipeline 16 for users. Meanwhile, the liquid energy storage medium in the second storage unit 11 flows to the vaporizer 12 and becomes a gaseous energy storage medium. It then exchanges heat with the heat storage medium in the third heat storage unit 7 in the third reheater 702. Afterward, the gaseous energy storage medium expands through the high-pressure expander 901, and then exchanges heat with the heat storage medium in the second heat storage unit 6 in the second reheater 602. Next, the gaseous energy storage medium expands through the medium-pressure expander 902, and then expands again through the low-pressure expander 903 into a low-pressure gaseous energy storage medium, which then condenses into a solid state in the phase change unit 3 and is stored. Simultaneously, the generator utilizes the residual pressure from the expansion of the high-pressure expander 901, medium-pressure expander 902, low-pressure expander 903, and the second expander 10 to generate electricity to cope with peak electricity demand periods, thereby alleviating electricity pressure.

[0066] The basic principles of this application have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this application are merely examples and not limitations, and should not be considered as essential features of each embodiment of this application. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the application to the necessity of employing the aforementioned specific details for implementation.

[0067] The block diagrams of devices, apparatuses, devices, and systems involved in this application are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, apparatuses, devices, and systems can be connected, arranged, and configured in any manner. Words such as “comprising,” “including,” “having,” etc., are open-ended terms meaning “including but not limited to,” and are used interchangeably with them. The terms “or” and “and” as used herein refer to the terms “and / or,” and are used interchangeably with them unless the context clearly indicates otherwise. The term “such as” as used herein refers to the phrase “such as but not limited to,” and is used interchangeably with it.

[0068] It should also be noted that in the apparatus, equipment, and methods of this application, the components or steps can be disassembled and / or recombined. These disassemblies and / or recombinations should be considered as equivalent solutions of this application.

[0069] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use this application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of this application. Therefore, this application is not intended to be limited to the aspects shown herein, but rather to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0070] It should be understood that the qualifiers “first,” “second,” “third,” “fourth,” “fifth,” and “sixth” used in the description of the embodiments of this application are only used to more clearly illustrate the technical solutions and are not intended to limit the scope of protection of this application.

[0071] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of this application to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

Claims

1. A natural gas peak-shaving system, characterized in that, include: High-pressure natural gas pipeline network; The first storage device is connected to the high-pressure natural gas pipeline network and is used to store liquefied natural gas; A phase change unit is used to store an energy storage medium, and the energy storage medium can exchange heat with the natural gas moving from the high-pressure natural gas pipeline to the first storage device to realize the gas-liquid phase change of natural gas and the gas-solid phase change of the energy storage medium. A cold storage device that can exchange heat with the natural gas, absorb the cold energy carried by the natural gas, and transfer cold energy to the natural gas; A thermal storage device is capable of exchanging heat with the natural gas and / or the energy storage medium, absorbing the thermal energy carried by the energy storage medium and transferring thermal energy to the energy storage medium, and transferring thermal energy to the natural gas. The second memory is used to store the energy storage medium; A second expander is installed between the first storage device and the low-pressure natural gas pipeline network for expanding the natural gas; A compressor unit is disposed between the first memory and the second memory for compressing the energy storage medium; the compressor unit includes a low-pressure compressor and a medium-pressure compressor connected in sequence. Precooler; The thermal storage device includes a first thermal storage unit, which can exchange heat with the natural gas and the energy storage medium, absorb the heat energy carried by the energy storage medium moving from the low-pressure compressor to the medium-pressure compressor, and transfer heat energy to the natural gas moving from the first storage tank to the second expander. The first thermal storage unit includes a first thermal storage hot tank, a first reheater, a first thermal storage cold tank, and a first heat recovery unit connected in sequence. The first inlet of the precooler is connected to the first storage tank, the first outlet of the precooler is connected to the inlet of the second expander, the second inlet of the precooler is connected to the outlet of the second expander, and the second outlet of the precooler is connected to the low-pressure natural gas pipeline network.

2. The natural gas peak-shaving system according to claim 1, characterized in that, The cold storage device includes a cold storage tank, a recooler, a hot storage tank, and a cold energy recovery unit connected in sequence; wherein, the cold storage tank is used to store the cold storage medium, the recooler is used to transfer the cold energy carried by the cold storage medium to the natural gas moving to the first storage tank via the high-pressure natural gas pipeline, the hot storage tank is used to store the hot storage medium, and the cold energy recovery unit is used to absorb the cold energy carried by the natural gas moving out of the first storage tank.

3. The natural gas peak-shaving system according to claim 1, characterized in that, Also includes: A first expander unit is disposed between the first memory and the second memory for expanding the energy storage medium; A generator is connected to the first expander unit and the second expander.

4. The natural gas peak-shaving system according to claim 3, characterized in that, The compressor unit includes a high-pressure compressor connected to the medium-pressure compressor; The first expander unit includes a high-pressure expander, a medium-pressure expander, and a low-pressure expander connected in sequence.

5. The natural gas peak-shaving system according to claim 4, characterized in that, The thermal storage device includes: The second thermal storage unit can exchange heat with the energy storage medium, absorb the heat energy carried by the energy storage medium moving from the medium-pressure compressor to the high-pressure compressor, and transfer heat energy to the energy storage medium moving from the high-pressure expander to the medium-pressure expander. The third thermal storage unit can exchange heat with the energy storage medium, absorb the heat energy carried by the energy storage medium moving from the high-pressure compressor to the second memory, and transfer heat energy to the energy storage medium moving from the second memory to the high-pressure expander.

6. The natural gas peak-shaving system according to claim 5, characterized in that, The second thermal storage unit includes a second thermal storage hot tank, a second reheater, a second thermal storage cold tank, and a second heat recovery unit connected in sequence; the third thermal storage unit includes a third thermal storage hot tank, a third reheater, a third thermal storage cold tank, and a third heat recovery unit connected in sequence.

7. The natural gas peak-shaving system according to claim 5, characterized in that, Also includes: A vaporizer is disposed between the second memory and the high-pressure expander; The cold energy collector can transfer cold energy to the energy storage medium that moves from the high-pressure compressor to the second memory.

8. The natural gas peak-shaving system according to claim 1, characterized in that, It also includes a natural gas pressure regulating device installed between the high-pressure natural gas pipeline network and the low-pressure natural gas pipeline network. The cold energy collector is capable of absorbing the cold energy of the natural gas moving from the natural gas pressure regulating device to the low-pressure natural gas pipeline network, and is also capable of absorbing the cold energy of the natural gas moving from the second expander to the low-pressure natural gas pipeline network.

9. A natural gas peak-shaving method, characterized in that, The natural gas peak-shaving system according to any one of claims 1-8 is completed, and the method includes the following steps: When natural gas is in a low-consumption period and also during a low-consumption period for electricity, the natural gas removed from the high-pressure natural gas pipeline is converted into liquefied natural gas by the phase change unit and stored in the first memory. During the phase change process, the energy storage medium in the phase change unit sublimates, and the gaseous energy storage medium is compressed by the compressor unit and condensed into liquefied energy storage medium, which is then stored in the second memory. When natural gas consumption is at its peak and electricity consumption is also at its peak, the liquid natural gas in the first storage device is converted into gaseous natural gas by the phase change unit, and then expanded into low-pressure gaseous natural gas by the second expander. The low-pressure gaseous natural gas is transported to the low-pressure natural gas pipeline network to cope with the peak gas consumption period. The liquid energy storage medium in the second storage device is expanded into low-pressure gaseous energy storage medium by the gasifier and the first expander unit. The low-pressure gaseous energy storage medium is condensed and stored in the phase change unit by the phase change unit. The generator uses the energy generated by the expansion of the first expander unit and the second expander unit to generate electricity to cope with the peak electricity consumption period.

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