Energy supply system and method utilizing LNG cold energy and solar energy

Abstract

The present invention relates to an energy supply system and method utilizing LNG cold energy and solar energy. It comprises an LNG cold side, a solar heat side, and a heat exchange portion. The LNG cold side is a cold medium pipeline A extending from an LNG storage tank, the solar heat side is a heat medium pipeline B extending from a solar heat storage tank, and the heat exchange portion is a heat exchange medium pipeline C. The cold medium pipeline A and the heat exchange medium pipeline C are connected via a phase-change cold storage device for heat exchange, and the solar side heat medium pipeline B and the heat exchange medium pipeline C are connected via a semiconductor temperature difference power generation device, and the temperature difference between the heat medium and the heat exchange medium is used to generate electrical energy. The present invention provides a multi-mode energy supply system and method with a phase-change heat storage / cold device that can simultaneously utilize solar energy to recover LNG cold energy, achieving good results in energy conservation, emission reduction, and low-carbon operation.

Description

Technical Field

[0001] The present invention relates to the technical field of LNG cold energy utilization, and in particular to an energy supply system and method utilizing LNG cold energy and solar energy. Background Art

[0002] Energy is essential for sustaining human activities. The progress of human society is closely linked to the development of energy technology. The efficient development and utilization of energy directly impacts the pace of social development. Today, with the continuous development of the global economy, people are placing greater emphasis on green and sustainable development paths. my country is also accelerating the implementation of environmental protection policies and promoting energy conservation and emission reduction. Natural gas, as a clean energy source, has garnered significant attention.

[0003] Currently, the most mature and economical method for transporting natural gas is through the use of liquefied natural gas (LNG), a material with low pressure, high density, and high safety. However, natural gas is typically consumed by end users in its gaseous form, which necessitates re-vaporization of LNG after long-distance transport. The natural gas liquefaction process is energy-intensive, requiring approximately 840 kilowatt-hours of energy to convert one ton of natural gas into LNG. Therefore, LNG contains a significant amount of cold energy.

[0004] It is of great significance to utilize the cold energy stored in LNG to avoid energy waste. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides an energy supply system that utilizes LNG cold energy and solar clean energy. The system can recover LNG cold energy while utilizing solar clean energy, and is an energy supply system with energy-saving, emission-reduction and carbon-reduction operation effects.

[0006] The present invention adopts the following technical solutions:

[0007] An energy supply system utilizing LNG cold energy and solar energy, comprising an LNG cold side, a solar heat side, and a heat exchange unit. The LNG cold side is a cold medium pipeline A extending from an LNG storage tank, the solar heat side is a heat medium pipeline B extending from a solar heat storage tank, and the heat exchange unit is a heat exchange medium pipeline C.

[0008] The end of the cooling medium pipeline A on the LNG side is connected to the natural gas user terminal, the end of the heat medium pipeline B on the solar energy side is connected to the hot water user terminal, and the heat exchange medium pipeline C is a circulation pipeline; wherein, the cooling medium pipeline A and the heat exchange medium pipeline C are connected through a phase change cold storage device for heat exchange, and the heat medium pipeline B and the heat exchange medium pipeline C on the solar energy side are connected through a semiconductor temperature difference power generation device, and the temperature difference between the heat carrier medium and the heat exchange medium is used to generate electricity.

[0009] Preferably, the phase change cold storage device is provided with two intertwined and independent medium channels, which are respectively connected to the cooling medium pipeline A and the heat exchange medium pipeline C; the semiconductor thermoelectric power generation device includes a hot end heat exchanger and a cold end heat exchanger, and generates electricity by utilizing the temperature difference between the hot end heat exchanger and the cold end heat exchanger, wherein the hot end heat exchanger is connected to the heat carrier pipeline B, and the cold end heat exchanger is connected to the heat exchange medium pipeline C.

[0010] Preferably, the cooling medium pipeline A is connected to the cold inlet of the phase change cold storage device, enters the medium channel of the phase change cold storage device, and passes through the cold outlet; between the cold outlet of the phase change cold storage device and the natural gas user terminal, a cold exchanger and a gas-phase natural gas storage tank are arranged in sequence along the flow direction of LGN, and the cold medium section of the cold exchanger is connected to the cooling medium pipeline A, and makes the LNG vaporize completely, and the vaporized natural gas is stored in the gas-phase natural gas storage tank.

[0011] Preferably, the heat medium end of the cold exchanger is connected to the cold supply terminal heat exchanger, which is a heat-generating device. An LNG gas supply temperature measuring point is also provided between the cold exchanger and the gas phase natural gas storage tank to detect whether the LNG is completely vaporized.

[0012] Preferably, a first switch valve is further provided on the pipeline between the gas-phase natural gas storage tank and the natural gas user terminal; an expander is further provided on the pipeline between the LNG gas supply temperature measuring point and the gas-phase natural gas storage tank. The LNG is completely vaporized in the cooler, and during this process, the gas expansion and pressure reduction are utilized to cause the expander to generate electricity.

[0013] Preferably, the semiconductor thermoelectric power generation device and the expander are both connected to the same battery, and the generated electrical energy is stored in the battery; when the temperature difference between the heat carrier medium and the heat exchange medium in the semiconductor thermoelectric power generation device cannot meet the use requirements, the battery also serves as the power supply for the semiconductor thermoelectric power generation device.

[0014] Preferably, the heat carrier medium pipeline B is respectively connected to the heat inlet and heat outlet of the semiconductor thermoelectric power generation device; a second switch valve is provided between the heat outlet and the hot water user terminal, and a first three-way regulating valve is provided between the solar heat storage tank and the heat inlet; the solar heat storage tank is also connected to the second switch valve via a hot water branch, and a third switch valve is provided on the hot water branch, and a hot water bypass is provided between the third switch valve and the solar heat storage tank, connected to the first three-way regulating valve.

[0015] Preferably, the heat exchange medium pipeline C enters the phase change cold storage device from the hot inlet of the phase change cold storage device and passes through the hot outlet. The heat exchange medium pipeline C is also connected to the heat exchange inlet and heat exchange outlet of the semiconductor thermoelectric power generation device respectively to form a closed loop; a second three-way regulating valve is arranged between the hot outlet and the heat exchange inlet, and a heat exchange branch is also arranged on the pipeline between the hot inlet and the heat exchange outlet to connect to the second three-way regulating valve.

[0016] Preferably, a first temperature measuring point is set between the heat inlet of the semiconductor thermoelectric power generation device and the first three-way regulating valve, and a second temperature measuring point is set between the heat exchange inlet of the semiconductor thermoelectric power generation device and the second three-way regulating valve.

[0017] Preferably, a low-temperature LNG pump is provided between the LNG storage tank and the cold inlet of the phase change cold storage device, a high-temperature heat carrier pump is provided between the solar heat storage tank and the first three-way regulating valve, and a heat exchange medium pump is provided between the heat exchange outlet of the phase change cold storage device and the second three-way regulating valve.

[0018] The present invention also provides an energy supply method for the energy supply system utilizing LNG cold energy and solar energy, wherein the method comprises: selecting an operating mode by controlling the switch valves and pumps on the cooling medium pipeline A, the heating medium pipeline B, and the heat exchange medium pipeline C according to the natural gas and hot water usage and the degree of sunlight;

[0019] The usage mode of LNG is as follows:

[0020] Ⅰa. During peak natural gas usage: LNG enters the phase-change cold storage device from the LNG storage tank, transfers the cold energy to the heat exchange medium pipeline C, and at the same time, the LNG absorbs heat and vaporizes. After passing through the cooler, it is completely vaporized and enters the gas-phase natural gas storage tank, and finally reaches the natural gas user terminal;

[0021] Ⅰb. When natural gas usage is low: LNG is vaporized and stored in gas-phase natural gas storage tanks;

[0022] The hot water usage patterns are:

[0023] IIa. When hot water usage is at its peak and solar energy is sufficient:

[0024] If the heat provided by solar energy is equal to the heat required by the hot water user, the semiconductor thermoelectric power generation device has no power input and output;

[0025] If the heat provided by solar energy is greater than the hot water user's demand, the water in the heat medium pipe B absorbs the heat from the sunlight and transmits the hot water absorbed by the solar energy to the hot end heat exchanger of the semiconductor thermoelectric power generation device for heat exchange. The hot water after heat exchange is then delivered to the hot water user terminal.

[0026] The hot end heat exchanger of the semiconductor thermoelectric power generation device uses hot water for heat exchange, generating electricity which is stored in the battery.

[0027] If the amount of heat provided by solar energy is less than the demand of hot water users, the electric energy stored in the battery will be fed into the semiconductor thermoelectric power generation device. The cold-end heat exchanger of the semiconductor thermoelectric power generation device will continue to receive the cold energy provided by the heat exchange medium pipeline C, while the hot-end heat exchanger will output heat to heat the water in the heat medium pipeline B and send it to the hot water user terminal.

[0028] IIb. When hot water usage is at its peak and solar energy is insufficient, the electricity stored in the battery is passed through the semiconductor thermoelectric generator. The cold-end generator set of the semiconductor thermoelectric generator is still supplied with cooling energy by the heat exchange medium pipeline C, while the hot-end generator set outputs heat to heat the water in the heat medium pipeline B and deliver it to the hot water user terminal.

[0029] IIc. When hot water usage is low and solar energy is sufficient: the water in heat medium pipe B receives heat from the sun and transfers the hot water absorbed by the sun to the hot-end heat exchanger of the semiconductor thermoelectric generator.

[0030] IId. When hot water usage is low and solar energy is insufficient: the hot water stored in the solar thermal storage tank provides thermal energy for the hot end heat exchanger of the semiconductor thermoelectric power generation device.

[0031] The beneficial effects of the present invention are:

[0032] LNG contains a vast amount of cold energy. If this cold energy cannot be recovered during LNG vaporization, a significant amount of energy will be wasted, resulting in energy loss. However, if all of the cold energy stored in LNG is converted into electricity, it can release a significant amount of electricity. Solar energy, as one of the most promising renewable energy sources, offers excellent characteristics such as wide distribution, environmental friendliness, and inexhaustible supply. my country spans multiple temperature zones, with significant climate variations across regions, but all regions possess abundant solar energy resources.

[0033] The present invention utilizes the temperature difference power generation and reverse cooling and heating characteristics of semiconductor materials, combines solar clean energy with LNG cold energy, and realizes the simultaneous use of LNG cold energy and solar clean energy for users.

[0034] This invention takes into account periods of high and low solar power, high and low natural gas usage, and high and low hot water usage. The system sets different operating modes to implement different energy supply methods. By opening and closing pumps and valves in corresponding circuits and switching on and off, the system meets the user's different needs for cooling, heating, electricity, and natural gas.

[0035] The multifunctional energy supply system adopted for various usage scenarios, on the one hand, recovers the cold energy in LNG to provide the required cooling capacity for the system's power generation unit and cooling unit, and on the other hand realizes the utilization of solar clean energy to provide the required heat for the system's power generation unit. At the same time, the system is equipped with heat storage tanks in the high-temperature refrigerant circuit and cold storage tanks in the low-temperature LNG circuit, which can realize continuous, stable, all-weather output of cold energy, electricity and heat energy as needed.

[0036] A phase-change cold storage device is used to recover LNG cold energy, which is used to provide cold-end energy for semiconductor thermoelectric generators. A cold exchanger is also used to further recover cold energy from the LNG, allowing it to fully vaporize and enter the natural gas user terminal. The cold energy recovered by the cold exchanger is used to provide daily cooling. Natural gas cold energy serves as both a cooling source for semiconductor thermoelectric generators or reverse heating, and as a cooling source for user cooling, achieving different modes of supply for cooling, heating, and electricity. This system achieves cold energy recycling while comprehensively utilizing clean solar energy, resulting in energy conservation, environmental protection, and reduced cooling, heating, and electricity costs.

[0037] After the liquid LNG flows through the phase change cold storage device of the present invention, it is simultaneously connected to the cold exchanger, which is connected to the cooling system. The cooling system is provided with a three-way valve. The flow rate of the medium entering the cold exchanger is adjusted according to the residual cold capacity in the LNG to realize the recovery and utilization of different cold capacities, so as to realize the full recovery and utilization of the LNG cold energy, realize the complete conversion of the natural gas entering the user into gaseous state, and realize the recovery and utilization of 100% of the LNG cold energy.

[0038] The present invention sets three-way regulating valves on different circuits of the system to realize the change of system working medium flow under different heat exchange conditions of corresponding recovery of cold and heat, thereby ensuring the control of liquid supply temperature of different circuits.

[0039] The present invention utilizes an energy supply system that realizes different energy supply modes of cold, heat and electricity, which can realize the organic combination of solar clean energy and LNG cold energy. By constructing a new multifunctional energy supply system, combining the recycling of peak and valley energy and the efficient recovery of LNG low-temperature cold energy, the combined supply of cold energy, heat energy and electricity for industrial production or life can be realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a schematic diagram of the system partitioning of the present invention;

[0041] Figure 2 A schematic diagram of the system configuration of the present invention;

[0042] Figure 3 This is a schematic diagram of the inlet and outlet arrangements of the phase change cold storage device of the present invention;

[0043] Figure 4 It is a schematic structural diagram of the semiconductor thermoelectric power generation device of the present invention.

[0044] The meanings of the symbols in the figure are as follows:

[0045] 11-LNG storage tank 12-cooling exchanger 121-cooling terminal heat exchanger 122-cooling liquid storage tank 123-cooling liquid supply pump 124-third three-way regulating valve

[0046] 13-Gas phase natural gas storage tank 14-LNG gas supply temperature measurement point 15-Expansion valve

[0047] 21-Solar thermal storage tank 22-Solar concentrator

[0048] 30-Phase change cold storage device 31-LNG cold inlet 32-LNG hot inlet 33-Heat exchange inlet 34-Heat exchange outlet

[0049] 40-Semiconductor thermoelectric generator 41-Hot end heat exchanger 411-Hot outlet 412-Hot inlet 42-Cold end heat exchanger 421-Cold inlet 422-Cold inlet 43-Generator body

[0050] 50-Battery

[0051] 61-first switch valve 62-second switch valve 63-third switch valve

[0052] 71-first three-way regulating valve 72-second three-way regulating valve

[0053] 81-first temperature measurement point 82-second temperature measurement point

[0054] 91- Low temperature LNG pump 92- High temperature heat pump 93- Heat exchange medium pump

[0055] B1-hot water branch B2-hot water bypass C1-heat exchange branch DETAILED DESCRIPTION

[0056] The technical solution of the present invention is described in more detail below with reference to the accompanying drawings and embodiments:

[0057] Example 1

[0058] like Figure 1-4As shown, a power supply system utilizing LNG cold energy and solar energy includes an LNG cold side for transporting LNG, a solar heat side for transporting hot water, and a heat exchange portion for a heat exchange medium. The LNG cold side is a cold medium pipeline A extending from an LNG storage tank 11, the solar heat side is a heat medium pipeline B extending from a solar heat storage tank 21, and the heat exchange portion is a heat exchange medium pipeline C.

[0059] The end of the cooling medium pipeline A on the LNG side is connected to the natural gas user terminal, and the end of the heating medium pipeline B on the solar energy side is connected to the hot water user terminal. The heat exchange medium pipeline C is a circulation pipeline, and the circulation pipeline is filled with water, ethylene glycol aqueous solution or glacial refrigerant as a heat exchange medium.

[0060] The cooling medium pipeline A and the heat exchange medium pipeline C are connected through the phase-change cold storage device 30 for heat exchange. The cooling medium pipeline A connects to the LNG cold inlet 31 of the phase-change cold storage device 30, enters the medium channel of the phase-change cold storage device 30, and exits through the LNG cold outlet 32. The heat exchange medium pipeline C enters the phase-change cold storage device 30 through the heat exchange inlet 33 of the phase-change cold storage device 30 and exits through the heat exchange outlet 34.

[0061] The phase change cold storage device 30 is provided with two intertwined and independent medium channels. The LNG cold inlet 31 and the LNG cold outlet 32 ​​are the two ends of one of the medium channels, and the heat exchange inlet 33 and the heat exchange outlet 34 are the two ends of the other medium channel. Through the medium channels, sufficient heat exchange can be carried out between LNG and the heat exchange medium.

[0062] The heat carrier medium pipeline B and the heat exchange medium pipeline C on the solar side are connected via a semiconductor thermoelectric power generation device 40 , which generates electricity by using the temperature difference between the heat carrier medium, ie, hot water, and the heat exchange medium.

[0063] Specifically, the semiconductor thermoelectric power generation device 40 includes a hot-end heat exchanger 41, a cold-end heat exchanger 42, and a generator set body 43 sandwiched between the hot-end heat exchanger 41 and the cold-end heat exchanger 42, wherein the hot-end heat exchanger 41 is connected to the heat carrier pipeline B, and the cold-end heat exchanger 42 is connected to the heat exchange medium pipeline C. The generator set body 43 generates electricity by utilizing the temperature difference between the hot-end heat exchanger 41 and the cold-end heat exchanger 42.

[0064] Between the LNG cold outlet 32 ​​and the natural gas user terminal, along the LGN flow path, a gas-phase natural gas storage tank 13 is installed to temporarily store vaporized LNG. To ensure complete vaporization of the LNG, a cooler 12 is also installed to perform heat exchange on the partially vaporized LNG before it enters the gas-phase natural gas storage tank 13.

[0065] The cold medium end of the cooler 12 is connected to the cold medium pipeline A, and completely vaporizes the LNG. The vaporized natural gas is stored in the gas phase natural gas storage tank 13. The hot medium end of the cooler 12 is connected to the cooling terminal heat exchanger 121, which is a cooling system that provides the heat required for heat exchange of the equipment in the system.

[0066] Furthermore, a cold liquid storage tank 122 and a cold liquid supply pump 123 are provided between the cold exchanger 12 and the cold supply terminal heat exchanger 121. The cold liquid supply pump 123 is used to promote the flow of the medium used for heat exchange between the cold exchanger and the cold supply terminal heat exchanger 121, and to adjust the flow rate of the medium used for heat exchange.

[0067] For ease of use, an LNG supply temperature measurement point 14 is further provided between the cold exchanger 12 and the gas-phase natural gas storage tank 13 to detect complete vaporization of the LNG. If the LNG has completely vaporized in the phase-change cold storage device 30, the heat exchange medium entering the secondary cold storage tank 122 is regulated by a third three-way regulating valve 124, and the cold exchanger 12 is temporarily deactivated.

[0068] A first switch valve 61 is also provided on the pipeline between the gas-phase natural gas storage tank 13 and the natural gas user terminal; an expander 15 is also provided on the pipeline between the LNG supply temperature measuring point 14 and the gas-phase natural gas storage tank 13. The LNG is completely vaporized in the cooler, and during this process, the gas expansion and pressure reduction are utilized to cause the expander 15 to generate electricity.

[0069] The semiconductor thermoelectric power generation device 40 and the expander 15 are both connected to the same battery 50 and store the generated electrical energy in the battery 50; when the temperature difference between the two ends of the semiconductor thermoelectric power generation device 40 cannot meet the usage requirements, the battery 50 also serves as the power supply for the semiconductor thermoelectric power generation device 40.

[0070] In the present invention, the heat carrier pipeline B is respectively connected to the heat inlet 412 and the heat outlet 411 of the hot-end heat exchanger 41; a second switch valve 62 is provided between the heat outlet 411 and the hot water user terminal, and a first three-way regulating valve 71 is provided between the solar heat storage tank 21 and the heat inlet 412; the solar heat storage tank 21 is also connected to the second switch valve 62 via a hot water branch B1, and a third switch valve 63 is provided on the hot water branch B1. A hot water bypass B2 is provided between the third switch valve 63 and the solar heat storage tank 21 and connected to the first three-way regulating valve 71.

[0071] In order to improve the efficiency of sunlight collection, devices such as solar concentrators 22 can be set around the solar heat storage tank 21 to help increase the amount of collected heat.

[0072] The heat exchange medium pipeline C is also respectively connected to the cold inlet 421 and the cold outlet 422 of the cold end heat exchanger 42 to form a closed loop; a second three-way regulating valve 72 is arranged between the heat exchange outlet 34 and the cold inlet 421, and a heat exchange branch C1 is also arranged on the pipeline between the heat exchange inlet 33 and the cold outlet 422 to connect to the second three-way regulating valve 72.

[0073] A first temperature measuring point 81 is set between the hot inlet 412 and the first three-way regulating valve 71, and a second temperature measuring point 82 is set between the cold inlet 412 and the second three-way regulating valve 72, which are used to assist in regulating the power input / output and heat exchange flow of the three-way valve in the system.

[0074] In order to ensure flow, a low-temperature LNG pump 91 is provided between the LNG storage tank 11 and the LNG cold inlet 31 of the phase change cold storage device 30, a high-temperature heat carrier pump 92 is provided between the solar heat storage tank 21 and the first three-way regulating valve 71, and a heat exchange medium pump 93 is provided between the heat exchange outlet 34 of the phase change cold storage device 30 and the second three-way regulating valve 72.

[0075] Example 2

[0076] In Example 1, the energy supply method for the energy supply system utilizing LNG cold energy and solar clean energy comprises: selecting an operating mode by controlling the opening or closing of the on-off valves and pumps on the cooling medium pipeline A, the heating medium pipeline B, and the heat exchange medium pipeline C according to the natural gas and hot water usage and the degree of sunlight;

[0077] The usage mode of LNG is as follows:

[0078] Ia. During peak natural gas usage: LNG enters the phase-change cold storage device 30 from the LNG storage tank 11, transfers cold energy to the heat exchange medium pipeline C, and simultaneously absorbs heat and vaporizes. After passing through the cold exchanger 12, it is completely vaporized and enters the gas-phase natural gas storage tank 13, and finally reaches the natural gas user terminal;

[0079] Ⅰb. When natural gas usage is low: LNG is vaporized and stored in the gas phase natural gas storage tank 13;

[0080] The hot water usage patterns are:

[0081] IIa. When hot water usage is at its peak and solar energy is sufficient:

[0082] If the heat provided by solar energy is equal to the heat required by the hot water user, the semiconductor thermoelectric power generation device 40 has no power input or output;

[0083] If the amount of heat provided by solar energy is greater than the demand for hot water by the user, the water in the heat medium pipe B absorbs the heat from the sunlight and transmits the hot water absorbed by the solar energy to the hot end heat exchanger 41 of the semiconductor thermoelectric power generation device 40 for heat exchange. The hot water after heat exchange is then delivered to the hot water user terminal.

[0084] The hot end heat exchanger 41 of the semiconductor thermoelectric power generation device 40 uses hot water to exchange heat, generating electrical energy which is stored in the battery 50;

[0085] If the amount of heat provided by solar energy is less than the amount required by hot water users, the electric energy stored in the battery 50 is fed into the semiconductor thermoelectric generator 40. The cold-end heat exchanger 42 of the semiconductor thermoelectric generator 40 continues to receive cold energy from the heat exchange medium pipeline C, while the hot-end heat exchanger 41 outputs heat to heat the water in the heat medium pipeline B and deliver it to the hot water user terminal.

[0086] IIb. When hot water usage is at its peak and solar energy is insufficient, the electric energy stored in the battery 50 is fed into the semiconductor thermoelectric generator 40. The cold-end heat exchanger 42 of the semiconductor thermoelectric generator 40 continues to receive cold energy from the heat exchange medium pipeline C, while the hot-end heat exchanger 41 outputs heat to heat the water in the heat medium pipeline B and deliver it to the hot water user terminal.

[0087] IIc. When hot water usage is low and solar energy is sufficient: the water in the heat medium pipeline B receives heat from the sun and then transfers the hot water absorbed from the sun to the hot end heat exchanger 41 of the semiconductor thermoelectric power generation device 40;

[0088] IId. When hot water usage is low and solar energy is insufficient: the hot water stored in the solar thermal storage tank 21 provides thermal energy to the hot end heat exchanger 41 of the semiconductor thermoelectric power generation device 40 .

[0089] After combining the above LNG usage mode and hot water usage mode, there are 8 situations in total, as shown in Table 1 below.

[0090] Table 1 Energy supply types in different operating modes

[0091] Serial number natural gas Hot water demand solar energy Energy supply type 1) peak low point adequate Cold and electricity 2) peak low point Insufficient Cold and electricity 3) low point low point adequate electricity 4) low point low point Insufficient Cold and electricity 5) peak peak Insufficient Cooling, heating, electricity 6) peak peak adequate Cooling, heating, electricity 7) low point peak Insufficient Cold, hot 8) low point peak adequate hot

[0092] The following are examples of various situations:

[0093] 1) When natural gas usage is at its peak and solar energy is good, and hot water is not needed

[0094] The low-temperature LNG pump 91, high-temperature heat pump 92, heat exchange medium pump 93, first on-off valve 61, and third on-off valve 63 in the system are turned on, while the second on-off valve 62 is closed. The cold energy in the LNG storage tank 11 is transferred by the heat exchange medium pump 93 to the cold-end heat exchanger 42 via the phase-change cold storage device 30. During periods of high solar radiation, the high-temperature heat pump 92 directly receives the heat medium, namely hot water, from the solar energy and delivers it to the hot-end heat exchanger 41, enabling continuous power generation by the semiconductor thermoelectric generator 40.

[0095] The liquid natural gas in the LNG storage tank 11 flows through the phase-change cold storage device 30, storing some of its cold energy in the heat exchange medium. However, some of the remaining cold energy in the LNG after passing through the phase-change cold storage device 30 remains unused. This energy continues to absorb heat from the refrigerant in the cooler 12, completely transforming into vaporized natural gas. This energy then drives the expander 13 to generate electricity, which is then delivered to the natural gas user terminal for use. The electricity generated by the expander 13 and the semiconductor thermoelectric generator 40 can be stored in the battery 50.

[0096] 2) When natural gas usage is at its peak and solar energy is insufficient, and hot water is not needed

[0097] The operation mode of natural gas is the same as 1), but for hot water, when the solar radiation is poor, the high-temperature heat pump 92 transports the heat medium stored in the solar heat storage tank 21, i.e., hot water, to the hot end heat exchanger 41, thereby realizing continuous power generation by the semiconductor thermoelectric power generation device 40.

[0098] 3) When natural gas usage is low and solar energy is sufficient, and hot water is not needed

[0099] Turn on the low-temperature LNG pump 91, high-temperature heat transfer pump 92, heat exchange medium pump 93, and third on-off valve 63 in the system, and close the first on-off valve 61 and second on-off valve 62. Hot water operation is similar to step 1), but once the natural gas is completely converted into gas, it enters the gas storage tank 13 for storage. When a natural gas user needs to use the gas, open the first on-off valve 61 to supply the user with the corresponding flow rate of natural gas.

[0100] 4) When natural gas usage is low, solar energy is insufficient, and hot water is not needed:

[0101] Turn on the low-temperature LNG pump 91, high-temperature heat pump 92, heat exchange medium pump 93, and third switch valve 63 in the system, and close the first switch valve 61 and second switch valve 62. In this mode, the natural gas operation mode is the same as 3), and the hot water operation mode is the same as 2).

[0102] In the above situations, the expander 13 and the semiconductor thermoelectric power generation device 40 can generate electrical energy to varying degrees, which belongs to the system power output mode.

[0103] 5) When natural gas usage is at its peak and solar energy is insufficient, and hot water is required:

[0104] Open the low-temperature LNG pump 91, the high-temperature heat transfer pump 92, the heat exchange medium pump 93, the first switch valve 61, the second switch valve 62 in the system, and close the third switch valve 63.

[0105] In this mode, natural gas is either delivered to the user terminal or stored in the gas tank 13 based on usage needs. The semiconductor thermoelectric generator 40 operates in reverse, with the electricity stored in the battery 50 flowing into it. Based on the performance of the generator chip itself, the cold-end heat exchanger 42 is continuously supplied with a cold source. When powered on, the hot-end heat exchanger 41 generates a relatively high-temperature heat output. This heat is then transferred to the hot water, a heat carrier medium delivered by the high-temperature heat pump 92, and finally delivered to the hot water user for use.

[0106] The thermoelectric power generation sheet in the semiconductor thermoelectric power generation device 40 used in the present invention can reversely cool and heat, which belongs to the existing technology and will not be further described here.

[0107] 6) When natural gas usage is at its peak and there is sufficient solar energy and hot water is available:

[0108] Open the low-temperature LNG pump 91, the high-temperature heat transfer pump 92, the heat exchange medium pump 93, the first switch valve 61, the second switch valve 62 in the system, and close the third switch valve 63.

[0109] In this mode, natural gas is selected to enter the user terminal or be stored in the gas storage tank 13 according to usage demand.

[0110] According to the relationship between the heat provided by solar energy and the heat required by hot water users, the power input or output mode of the semiconductor thermoelectric power generation device 40 is changed, specifically:

[0111] 6-1) If the heat provided by solar energy is equal to the heat required by the hot water user, the semiconductor thermoelectric power generation device 40 has no power input or output;

[0112] 6-2) If the amount of heat provided by solar energy exceeds the hot water demand, the water in heat carrier pipe B, after receiving the solar heat, transfers the excess heat to the hot-end heat exchanger 41 of the semiconductor thermoelectric generator 40. Since the cold-end heat exchanger 42 is continuously supplied with cold energy by natural gas, the semiconductor thermoelectric generator 40 still has power to output to the battery 50.

[0113] 6-3) If the amount of heat provided by solar energy is less than the hot water user's demand, external electricity is required to heat the water. In this case, the electricity stored in the battery 50 is fed into the semiconductor thermoelectric generator 40, driving the semiconductor thermoelectric generator 40 to operate in reverse. Since the cold-end heat exchanger 42 receives cold energy, the hot-end heat exchanger 41 outputs heat, heating the water in the heat medium pipeline B, thereby meeting the hot water user's demand.

[0114] 7) When natural gas usage is low and solar energy is insufficient, and hot water is used:

[0115] Open the low-temperature LNG pump 91 , the high-temperature heat transfer pump 92 , the heat exchange medium pump 93 , the second on-off valve 62 , and the third on-off valve 63 , and close the first on-off valve 61 .

[0116] At this time, the natural gas operation mode is the same as 3), and the hot water operation mode is the same as 6-3).

[0117] 8) When natural gas usage is low and solar energy is sufficient and hot water is available:

[0118] Open the low-temperature LNG pump 91 , the high-temperature heat transfer pump 92 , the heat exchange medium pump 93 , the second on-off valve 62 , and the third on-off valve 63 , and close the first on-off valve 61 .

[0119] At this time, the natural gas operation mode is the same as 3), and the hot water operation mode is the same as 6).

[0120] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An energy supply system utilizing LNG cold energy and solar energy, characterized in that: It comprises an LNG cold side, a solar thermal side and a heat exchange part, wherein the LNG cold side is a cold medium pipeline A extending from an LNG storage tank (11), the solar thermal side is a heat medium pipeline B extending from a solar thermal storage tank (21), and the heat exchange part is a heat exchange medium pipeline C; The end of the cooling medium pipeline A on the LNG side is connected to a natural gas user terminal, the end of the heat medium pipeline B on the solar side is connected to a hot water user terminal, and the heat exchange medium pipeline C is a circulation pipeline; wherein, the cooling medium pipeline A and the heat exchange medium pipeline C are connected via a phase change cold storage device (30) for heat exchange, and the heat medium pipeline B and the heat exchange medium pipeline C on the solar side are connected via a semiconductor temperature difference power generation device (40), and the temperature difference between the heat medium and the heat exchange medium is used to generate electrical energy; The phase change cold storage device (30) is provided with two intertwined and mutually independent medium channels, which are respectively connected to the cooling medium pipeline A and the heat exchange medium pipeline C; the semiconductor temperature difference power generation device (40) includes a hot end heat exchanger (41), a cold end heat exchanger (42) and a generator set body (43) sandwiched between the hot end heat exchanger (41) and the cold end heat exchanger (42); the generator set body (43) generates electricity by utilizing the temperature difference between the hot end heat exchanger (41) and the cold end heat exchanger (42), wherein the hot end heat exchanger (41) is connected to the heat medium pipeline B, and the cold end heat exchanger (42) is connected to the heat exchange medium pipeline C; The heat medium pipeline B is respectively connected to the heat inlet (412) and the heat outlet (411) of the hot end heat exchanger (41); a second switch valve (62) is provided between the heat outlet (411) and the hot water user terminal, and a first three-way regulating valve (71) is provided between the solar heat storage tank (21) and the heat inlet (412); the solar heat storage tank (21) is also connected to the second switch valve (62) via a hot water branch (B1), and a third switch valve (63) is provided on the hot water branch (B1); and a hot water bypass (B2) is provided between the third switch valve (63) and the solar heat storage tank (21) and connected to the first three-way regulating valve (71).

2. The energy supply system using LNG cold energy and solar energy according to claim 1, characterized in that: The cooling medium pipeline A is connected to the LNG cold inlet (31) of the phase-change cold storage device (30), enters the medium channel of the phase-change cold storage device (30), and passes through the LNG cold outlet (32); between the LNG cold outlet (32) and the natural gas user terminal, along the flow direction of the LGN, a cold exchanger (12) and a gas-phase natural gas storage tank (13) are also arranged in sequence, the cold medium section of the cold exchanger (12) is connected to the cooling medium pipeline A, and the LNG is completely vaporized, and the vaporized natural gas is stored in the gas-phase natural gas storage tank (13).

3. The energy supply system using LNG cold energy and solar energy as claimed in claim 2, characterized in that: The heat medium end of the cold exchanger (12) is connected to the cold supply terminal heat exchanger (121), and the cold supply terminal heat exchanger (121) is a heat generating device. An LNG supply temperature measuring point (14) is also provided between the cold exchanger (12) and the gas phase natural gas storage tank (13) for detecting whether the LNG is completely vaporized.

4. The energy supply system using LNG cold energy and solar energy as claimed in claim 3, characterized in that: A first switch valve (61) is also provided on the pipeline between the gas-phase natural gas storage tank (13) and the natural gas user terminal; an expander (15) is also provided on the pipeline between the LNG gas supply temperature measurement point (14) and the gas-phase natural gas storage tank (13). The LNG is completely vaporized in the cooler, and during this process, the gas expansion and pressure reduction are utilized to cause the expander (15) to generate electricity.

5. The energy supply system using LNG cold energy and solar energy as claimed in claim 4, characterized in that: The semiconductor thermoelectric power generation device (40) and the expander (15) are both connected to the same storage battery (50), and the generated electric energy is stored in the storage battery (50); when the temperature difference between the two ends of the semiconductor thermoelectric power generation device (40) cannot meet the use requirements, the storage battery (50) also serves as the power supply of the semiconductor thermoelectric power generation device (40).

6. The energy supply system using LNG cold energy and solar energy as claimed in claim 5, characterized in that: The heat exchange medium pipeline C enters the phase change cold storage device (30) from the heat exchange inlet (33) of the phase change cold storage device (30) and passes through the heat exchange outlet (34). The heat exchange medium pipeline C is also connected to the cold inlet (421) and the cold outlet (422) of the cold end heat exchanger (42) respectively to form a closed loop. A second three-way regulating valve (72) is provided between the heat exchange outlet (34) and the cold inlet (421). A heat exchange branch (C1) connected to the second three-way regulating valve (72) is also provided on the pipeline between the heat exchange inlet (33) and the cold outlet (422).

7. The energy supply system using LNG cold energy and solar energy as claimed in claim 6, characterized in that: A low-temperature LNG pump (91) is provided between the LNG storage tank (11) and the LNG cold inlet (31) of the phase-change cold storage device (30); a high-temperature heat transfer pump (92) is provided between the solar heat storage tank (21) and the first three-way regulating valve (71); and a heat exchange medium pump (93) is provided between the heat exchange outlet (34) of the phase-change cold storage device (30) and the second three-way regulating valve (72); A first temperature measuring point (81) is provided between the hot inlet (412) and the first three-way regulating valve (71), and a second temperature measuring point (82) is provided between the cold inlet (421) and the second three-way regulating valve (72).

8. A method for supplying energy using LNG cold energy and solar energy as claimed in claim 7, characterized in that: The method is as follows: according to the natural gas and hot water usage and the degree of sunlight, the operation mode is selected by controlling the switch valves and pumps on the cooling medium pipeline A, the heating medium pipeline B and the heat exchange medium pipeline C; The usage mode of LNG is as follows: Ⅰa. When natural gas usage is at its peak: LNG enters the phase-change cold storage device (30) from the LNG storage tank (11), transfers the cold energy to the heat exchange medium pipeline C, and at the same time, the LNG absorbs heat and vaporizes. After passing through the cold exchanger (12), it is completely vaporized and enters the gas phase natural gas storage tank (13), and finally enters the natural gas user terminal; Ⅰb. When natural gas usage is low: LNG is vaporized and stored in the gas phase natural gas storage tank (13); The hot water usage pattern is: IIa. When hot water usage is at its peak and solar energy is sufficient: If the heat provided by the solar energy is equal to the heat required by the hot water user, the semiconductor thermoelectric power generation device (40) has no power input and output; If the heat provided by solar energy is greater than the demand of hot water users, the water in the heat medium pipeline B receives the heat from the sunlight and then transports the hot water absorbed by the solar energy to the hot end heat exchanger (41) of the semiconductor thermoelectric power generation device (40) for heat exchange. The hot water after heat exchange is then transported to the hot water user terminal. The hot end heat exchanger (41) of the semiconductor thermoelectric power generation device (40) uses hot water for heat exchange, generating electrical energy which is stored in the storage battery (50); If the amount of heat provided by solar energy is less than the demand of the hot water user, the electric energy stored in the storage battery (50) is fed into the semiconductor thermoelectric power generation device (40), the cold end heat exchanger (42) of the semiconductor thermoelectric power generation device (40) still receives the cold energy provided by the heat exchange medium pipeline C, and the hot end heat exchanger (41) outputs heat to heat the water in the heat medium pipeline B and deliver it to the hot water user terminal; IIb. When the hot water usage is at its peak and solar energy is insufficient: the electric energy stored in the storage battery (50) is fed into the semiconductor thermoelectric power generation device (40), the cold end heat exchanger (42) of the semiconductor thermoelectric power generation device (40) still receives the cold energy provided by the heat exchange medium pipeline C, and the hot end heat exchanger (41) outputs heat to heat the water in the heat medium pipeline B and deliver it to the hot water user terminal; IIc. When hot water usage is low and solar energy is sufficient: after the water in the heat medium pipeline B receives the heat from the sun, the hot water absorbed by the sun is transported to the hot end heat exchanger (41) of the semiconductor thermoelectric power generation device (40); IId. When hot water usage is low and solar energy is insufficient: the hot water stored in the solar thermal storage tank (21) provides thermal energy for the hot end heat exchanger (41) of the semiconductor thermoelectric power generation device (40).

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