Solar energy-liquefied natural gas combined driven hydrogen production system and working method thereof

Abstract

The invention belongs to the technical field of medium and low temperature waste heat utilization, and particularly relates to a solar energy-liquefied natural gas combined driven hydrogen production system and a working method thereof. The solar energy-liquefied natural gas combined driving hydrogen production system is provided with a solar heat collector, a heat storage box, an auxiliary heater, a steam generator, a steam turbine, a power generator, a condenser, a pump, a refrigeration heat exchanger, an electrolytic tank and an alternating current-direct current converter. In the technical scheme disclosed by the invention, a solar heat collector and a heat storage tank form a solar energy collection subsystem, an auxiliary heater, a steam generator, a steam turbine, a generator, a condenser, a pump and a refrigeration heat exchanger form a power generation subsystem, and an electrolytic tank and an alternating current-direct current converter form a hydrogen production subsystem. The coupling effect can realize the utilization of medium and low temperature heat sources, and the influence of the parameter fluctuation of the heat sources is small.

Description

Technical Field

[0001] The present invention belongs to the technical field of medium and low temperature waste heat utilization, and in particular relates to a solar energy-liquefied natural gas (LNG) jointly driven hydrogen production system and a working method thereof. Background Art

[0002] With rapid economic development, the demand for fossil energy has increased dramatically. Furthermore, the burning of fossil fuels can cause significant damage to the natural environment. Energy crises and environmental pollution have become significant obstacles to economic development. To address these issues, scholars have proposed solutions such as waste heat recovery from existing energy-intensive industries and the development of green, renewable energy.

[0003] Currently, the heat source temperatures of renewable energy sources such as solar energy, geothermal energy, and industrial waste heat are typically less than 500°C, representing medium- and low-temperature heat sources. The traditional single-pressure water vapor Rankine cycle has low utilization efficiency for these sources. Consequently, scholars have proposed systems suitable for utilizing these sources, such as the organic working fluid Rankine cycle, the dual-pressure steam power cycle, the low-boiling-point working fluid supercritical cycle, and the Kalina cycle. All of these systems are currently operational in experimental benches or power plants. Compared to the stable heat source input of conventional fossil fuel thermal systems, the heat source parameters of medium- and low-temperature heat sources often fluctuate significantly, inevitably leading to deviations from design parameters and operation under variable operating conditions. Extensive operational experience has shown that medium- and low-temperature heat source utilization systems are affected by fluctuations in heat source parameters, resulting in frequent and significant changes in operating conditions. Furthermore, when the heat source fluctuates significantly, it is difficult for the system to maintain stable operating conditions, leading to frequent forced shutdowns. In order to ensure the safety and stability of the system during changes in operating conditions, it is necessary to conduct in-depth research on the dynamic characteristics of the system in order to develop a new type of efficient and stable integrated system to realize the utilization of medium and low temperature heat sources. Summary of the Invention

[0004] The present invention aims to provide a solar-liquefied natural gas (LNG)-powered hydrogen production system and its operating method to address one or more of the aforementioned technical problems. The disclosed technical solution comprises a solar energy collection subsystem, a power generation subsystem, and a hydrogen production subsystem. This system utilizes medium- and low-temperature heat sources and is minimally affected by fluctuations in heat source parameters.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: In a first aspect, the present invention provides a solar-liquefied natural gas combined drive hydrogen production system, comprising: a solar collector, a heat storage tank, an auxiliary heater, a steam generator, a steam turbine, a condenser, a pump, a refrigeration heat exchanger, an electrolytic cell and an AC-DC converter; wherein, The solar thermal collector is provided with a first heat exchange pipe, and the heat storage tank is provided with a first water inlet, a first water outlet, a second water inlet, and a second water outlet; the outlet of the first heat exchange pipe is connected to the first water inlet, and the first water outlet is connected to the inlet of the first heat exchange pipe; water is provided in the heat storage tank for use as a heat storage medium; The steam generator is provided with a second heat exchange pipe and a third heat exchange pipe, the condenser is provided with a fourth heat exchange pipe and a fifth heat exchange pipe, and the refrigeration heat exchanger is provided with a sixth heat exchange pipe and a seventh heat exchange pipe; the second water outlet is connected to the inlet of the second heat exchange pipe via the auxiliary heater, and the outlet of the second heat exchange pipe is connected to the second water inlet; the outlet of the third heat exchange pipe is connected to the inlet of the fourth heat exchange pipe via the steam turbine, and the outlet of the fourth heat exchange pipe is connected to the inlet of the third heat exchange pipe via a pump and the sixth heat exchange pipe of the refrigeration heat exchanger; the fifth heat exchange pipe is used to introduce liquefied natural gas; The generator is used to output electric energy under the drive of the steam turbine; The electrolytic cell is used to produce hydrogen by electrolyzing water using the electric energy output by the generator, and the AC-DC converter is provided between the electrolytic cell and the generator.

[0006] A further improvement of the technical solution of the present invention is that the seventh heat exchange pipe is used for letting in air.

[0007] A further improvement of the technical solution of the present invention is that the circulating working fluid flowing between the steam generator, the steam turbine, the condenser, the pump, and the refrigeration heat exchanger is supercritical carbon dioxide or propane.

[0008] A further improvement of the technical solution of the present invention lies in that, during the design process, the system is first modeled based on the effective heat absorbed by the solar collector, the energy balance of the heat storage tank, and the decomposition voltage of the high calorific value of water. Then, a selected optimization algorithm is used to optimize the system parameters with the maximum cycle thermal efficiency as the optimization goal to obtain the optimized system parameters.

[0009] A further improvement of the technical solution of the present invention is that the selected optimization algorithm is a particle swarm algorithm, a genetic algorithm, an ant colony algorithm or a neural network optimization algorithm.

[0010] A further improvement of the technical solution of the present invention is that the solar thermal collector is a flat-plate collector.

[0011] A further improvement of the technical solution of the present invention is that the effective heat absorbed by the solar collector is the difference between the instantaneous solar radiation heat absorbed by the collector and the heat loss of the collector. The calculation formula in steady state is: ; Where, Effectively absorb heat for the collector; The collector absorbs heat instantly; is the collector area; is the heat dissipation loss of the collector; ; Where, is the instantaneous direct solar radiation on the horizontal plane; is the calculation coefficient of direct solar radiation on the inclined surface; is the transmittance of the flat-plate collector glass; is the absorptivity of the flat-plate collector glass; is the transmittance absorption rate of direct solar radiation on the collector; is the instantaneous solar scattered radiation on the horizontal surface; is the calculation coefficient of solar scattered radiation on the inclined surface; is the calculation coefficient of solar reflected radiation on the inclined surface; is the transmittance absorptivity of the solar scattered radiation on the collector; ; Where, is the total heat dissipation coefficient; is the average surface temperature of the flat-plate collector; is the ambient temperature; ; Where, is the heat dissipation coefficient of the top of the flat-plate collector; is the side heat dissipation coefficient of the flat-plate collector; is the heat dissipation coefficient at the bottom of the flat-plate collector.

[0012] A further improvement of the technical solution of the present invention is that the energy balance formula of the heat storage tank is: ; Where, is the total heat capacity of the liquid in the thermal storage tank; is the total heat capacity of the thermal storage tank material; is the temperature of the heat storage tank; The heat transferred from the thermal storage tank to the load It is the product of the surface area of ​​the heat storage tank and the heat transfer system.

[0013] A further improvement of the technical solution of the present invention is that the calculation expression of the high calorific value decomposition voltage of water is: ; Where, It is the decomposition voltage of water high calorific value; is the higher calorific value of hydrogen; The number of electrons required to produce one molecule is 2 for hydrogen; is the Faraday constant.

[0014] In a second aspect, the present invention provides a method for operating a solar-liquefied natural gas combined drive hydrogen production system, comprising the following steps: The solar thermal collector collects the heat from the sun and stores it in a heat storage tank using water as the medium. The heat storage tank uses water as the heat exchange medium to output heat, and the output heat is released in the steam generator. When the heat output of the heat storage tank is insufficient, the auxiliary heater is used to supplement the heat. The high-temperature, high-pressure working fluid output by the steam generator absorbs heat and drives the steam turbine to rotate. The steam turbine expands and produces work, driving the generator to generate electricity. The working fluid discharged from the steam turbine enters the condenser, exchanges heat with the low-temperature liquefied natural gas, and condenses into liquid. After being pressurized by the pump and heated by the refrigeration heat exchanger, it returns to the steam generator. In addition, when the power output by the generator is sufficient, the electrolytic cell uses the power output by the generator to electrolyze water to produce hydrogen for consumption.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The solar-liquefied natural gas (LNG) combined hydrogen production system disclosed in the present invention can be divided into three subsystems: a solar energy collection subsystem, a power generation subsystem, and a hydrogen production subsystem. These subsystems can utilize medium- and low-temperature heat sources and are less affected by fluctuations in heat source parameters. Specifically, the present invention uses solar thermal collectors to collect heat. Furthermore, a hot water-type heat storage tank is added to the system, which reduces the impact of changes in solar radiation intensity on the downstream power generation subsystem, thereby extending the operating time of the power generation subsystem and increasing power generation. Furthermore, the power generation subsystem is primarily composed of a steam generator, a steam turbine, a condenser, a water pump, and a refrigeration heat exchanger. The high-temperature, high-pressure working fluid from the steam generator drives the steam turbine to rotate and expand, producing work. The steam turbine drives the generator to generate electricity. The added refrigeration heat exchanger can first heat the circulating working fluid and simultaneously function as a refrigerator to output cooling capacity. Finally, the hydrogen production subsystem can produce hydrogen through water electrolysis in an electrolytic cell, absorbing excess electrical energy. In summary, the present invention realizes the utilization of medium and low-temperature heat sources through the coupled utilization of the solar energy collection subsystem, the power generation subsystem and the hydrogen production subsystem, and has good stability (that is, it realizes energy conversion based on solar energy and liquefied natural gas cold energy, improves the efficiency of the solar low-temperature thermal power generation system and realizes the recovery of cold energy in LNG).

[0016] In the preferred technical solution of the present invention, a static model of a solar-liquefied natural gas combined-driven hydrogen production system is constructed, a reasonable system form and circulating working fluid are selected, the influence of the main system parameters on the system performance is analyzed and the main parameters are optimized, further providing a theoretical analysis basis for the comprehensive utilization of low-temperature solar energy and LNG cold energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art; obviously, the drawings described below are some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 Schematic diagram of a solar-liquefied natural gas combined drive hydrogen production system according to an embodiment of the present invention; The explanations of the reference numerals in the figures are as follows: 1. Solar collector; 2. Heat storage tank; 3. Auxiliary heater; 4. Steam generator; 5. Steam turbine; 6. Condenser; 7. Pump; 8. Refrigeration heat exchanger; 9. Electrolytic cell; 10. AC / DC converter. DETAILED DESCRIPTION

[0019] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0020] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0021] The present invention is described in further detail below with reference to the accompanying drawings: See also Figure 1 The embodiment of the present invention provides a solar-liquefied natural gas combined drive hydrogen production system, comprising: a solar collector 1, a heat storage tank 2, an auxiliary heater 3, a steam generator 4, a steam turbine 5, a generator, a condenser 6, a pump 7, a refrigeration heat exchanger 8, an electrolytic cell 9 and an AC-DC converter 10; wherein, The solar thermal collector 1 is provided with a first heat exchange pipe; the heat storage tank 2 is provided with a first water inlet, a first water outlet, a second water inlet, and a second water outlet; wherein the outlet of the first heat exchange pipe is connected to the first water inlet, and the first water outlet is connected to the inlet of the first heat exchange pipe; water as a heat storage medium is provided in the heat storage tank 2; The steam generator 4 is provided with a second heat exchange pipe and a third heat exchange pipe; wherein the second water outlet is connected to the inlet of the second heat exchange pipe through the auxiliary heater 3, and the outlet of the second heat exchange pipe is connected to the second water inlet; The condenser 6 is provided with a fourth heat exchange pipe and a fifth heat exchange pipe; wherein, the outlet of the third heat exchange pipe is connected to the inlet of the fourth heat exchange pipe via the steam turbine 5, and the outlet of the fourth heat exchange pipe can be connected to the inlet of the third heat exchange pipe via the pump 7 and the refrigeration heat exchanger 8; the fifth heat exchange pipe is used to pass LNG; The generator is used to output electric energy under the drive of the steam turbine 5; The electrolytic cell 9 is used to utilize the electric energy output by the generator to electrolyze water to produce hydrogen; wherein, the AC-DC converter 10 is provided between the electrolytic cell 9 and the generator.

[0022] To improve the efficiency of low-temperature solar thermal power generation systems and recover cold energy from LNG, an embodiment of the present invention specifically discloses a low-temperature solar-LNG-driven combined hydrogen production system. The system includes a solar energy collection subsystem (illustratively, primarily comprising a solar thermal collector 1 and a thermal storage tank 2), a power generation subsystem (illustratively, primarily comprising an auxiliary heater 3, a steam generator 4, a steam turbine 5, a generator, and a condenser 6), and a hydrogen production subsystem (illustratively, primarily comprising an electrolytic cell 9, etc.). The technical solution of this embodiment of the present invention incorporates a hot water thermal storage tank 2, which reduces the impact of variations in solar radiation intensity on the downstream power generation system, thereby extending the power generation system's operating time and increasing power generation. In the power generation subsystem, the high-temperature, high-pressure working fluid from steam generator 4 drives the rotation of steam turbine 5, expanding and producing work. This turbine 5 drives the generator to generate electricity. The addition of auxiliary heater 3 enhances the new system's ability to withstand parameter fluctuations. The hydrogen production subsystem of the present invention primarily includes an electrolytic cell 9 for water electrolysis to produce hydrogen. An AC / DC converter converts the electrical energy generated by the generator into DC power of an appropriate voltage level, which then drives electrolytic cell 9 to produce hydrogen through water electrolysis. In summary, the technical solutions disclosed in the embodiments of the present invention achieve energy conversion from solar energy and liquefied natural gas cold energy, enabling power generation and clean hydrogen production while enhancing resistance to parameter fluctuations.

[0023] In the embodiments of the present invention, the solar energy collection subsystem is further explained as follows: The solar thermal collector 1 can be a flat-plate collector. Because solar radiation intensity varies significantly throughout the day, a hot water heat storage tank 2 is incorporated into the system to ensure smoother system operation. This heat storage tank 2 stores some energy during periods of high solar radiation and releases the stored heat during periods of low or no solar radiation. The addition of the heat storage tank 2 not only reduces the impact of varying solar radiation intensity on the downstream power generation system but also extends the system's operating time and increases power generation. The solar thermal collector 1 absorbs solar energy and transfers heat to water. The heated hot water enters the heat storage tank 2, where it mixes with the water stored there, raising the temperature of the water. Some of the water in the heat storage tank 2 returns to the solar thermal collector 1 to continue absorbing heat. Other water flows out of the heat storage tank 2 and enters the steam generator 4, where it transfers heat to the working fluid before returning to the heat storage tank 2 after its temperature has been lowered.

[0024] In the embodiment of the present invention, the power generation subsystem is further explained as follows: The high-temperature, high-pressure working fluid exiting the steam generator 4 rotates the steam turbine 5, expanding and producing work, which in turn drives the generator to generate electricity. The working fluid discharged from the steam turbine 5 then enters the condenser 6, where it undergoes heat exchange with low-temperature liquefied natural gas (LNG) and condenses into a liquid state. In conventional low-temperature waste heat power generation systems, the working fluid is pressurized by a pump 7 and then directly enters the steam generator 4 to absorb heat. However, in this system, since the condensation temperature of the working fluid is very low, below the ambient temperature, if the pressurized working fluid is directly fed into the steam generator 4 to absorb heat, not only would the cold energy in the low-temperature working fluid not be utilized, but the heat energy provided by the steam generator 4's heat source would also be wasted. Therefore, the present invention incorporates a refrigeration heat exchanger 8 that initially heats the working fluid using air. The air's temperature drops after heat exchange with the working fluid, allowing the refrigeration heat exchanger 8 to function as a refrigerator, outputting cooling capacity. The temperature of the working fluid preheated by the refrigeration heat exchanger 8 rises to a temperature close to the ambient temperature, and then enters the steam generator 4 to further absorb heat and increase temperature, and the cycle continues.

[0025] In the technical solution of the embodiment of the present invention, since the heating capacity of the solar subsystem is affected by changes in solar radiation, and the LNG flow rate is also limited by user demand, in order to alleviate the changes in the output power of the power generation subsystem, the present invention adds a hydrogen production subsystem. In the research on new energy hydrogen production, water electrolysis is one of the most basic and widely used hydrogen production methods. Since water electrolysis requires direct current, and the electric energy generated by the generator is alternating current, an AC-DC converter 10 is required to convert the electric energy into direct current with a suitable voltage level, and then drive the electrolytic cell 9 to produce hydrogen by water electrolysis.

[0026] To illustrate, solar energy is one of the most promising renewable energy sources. One of the main ways to improve the efficiency of low-temperature solar thermal power generation systems is to combine solar energy with other energy sources. Liquefied natural gas (LNG) is a liquid at -162°C under atmospheric pressure. Before being supplied to downstream users, it must be vaporized and heated to above 0°C. LNG releases a large amount of cold energy during vaporization, approximately 830-860 kJ / kg. Therefore, to improve the efficiency of low-temperature solar thermal power generation systems and recover the cold energy from LNG, the present invention proposes a low-temperature solar-LNG combined hydrogen production system. In this further improved technical solution, based on the system described in the preceding embodiment, a static model of the low-temperature solar-LNG combined hydrogen production system is constructed. A suitable system configuration and circulating working fluid are selected, and the impact of key system parameters on system performance is analyzed and optimized. This provides a theoretical basis for the comprehensive utilization of low-temperature solar energy and LNG cold energy.

[0027] As a preferred embodiment of the technical solution of the present invention, the effective heat absorbed by the solar collector is the difference between the instantaneous solar radiation heat absorbed by the collector and the heat loss of the collector. The calculation formula in steady state is: ; Where, The effective heat absorption of the collector / W; is the instantaneous heat absorption of the collector / W·m -2 ; is the collector area / m 2 ; is the heat loss of the collector / W.

[0028] The calculation formula for the instantaneous heat absorption of the collector is: ; Where, is the instantaneous direct solar radiation on the horizontal surface / W·m -2 ; is the calculation coefficient of direct solar radiation on the inclined surface; is the transmittance of the flat-plate collector glass; is the absorptivity of the flat-plate collector glass; is the transmittance absorption rate of direct solar radiation on the collector; is the instantaneous solar scattered radiation on the horizontal surface / W·m 2 ; is the calculation coefficient of solar scattered radiation on the inclined surface; is the calculation coefficient of solar reflected radiation on the inclined surface; is the transmittance absorptivity of the solar scattered radiation on the collector.

[0029] The calculation formula for the heat dissipation loss of the collector is: ; Where, is the total heat dissipation coefficient / W·m -2 ·K -1 ; is the average surface temperature of the flat-plate collector / K; is the ambient temperature / K.

[0030] ; Where: is the heat dissipation coefficient of the top of the flat-plate collector / W·m -2 ·K -1 ; is the side heat dissipation coefficient of the flat-plate collector / W·m -2 ·K -1 ; is the heat dissipation coefficient of the flat plate collector bottom / W·m -2 ·K -1 .

[0031] In this embodiment of the present invention, the heat storage tank is calculated using a uniform mixing model, meaning that the temperature of the liquid in the tank is uniform everywhere. The energy source for the heat storage tank is hot water generated by a flat-plate solar collector. Part of this energy is provided to the downstream power generation cycle, while the remaining energy is lost to the environment. Therefore, the energy balance equation for the heat storage tank is: ; Where, is the total heat capacity of the liquid in the heat storage tank / J·K -1 ; is the total heat capacity of the heat storage tank material / J·K -1 ; is the temperature of the heat storage tank / K; The heat transferred from the heat storage tank to the load / W; The product of the surface area of ​​the heat storage tank and the heat transfer system / W·K -1 Explanatory note: when the capacity of the thermal storage tank is large, the heat capacity of the thermal storage tank material is small compared to the heat capacity of the liquid in the tank. This item can be ignored.

[0032] As a preferred embodiment of the technical solution of the present invention, there are many options for the system form of the power generation subsystem. However, the single-pressure or dual-pressure cycle using water as the working fluid is limited by the freezing temperature of water and cannot make good use of the cold energy of LNG. At the same time, for low-temperature solar energy with a temperature below 100°C, the advantages of the Kalina cycle are not prominent. Therefore, the embodiment of the present invention adopts the Rankine cycle as the basic cycle form of the power generation system. There are many optional working fluids for the Rankine cycle. In the recovery of low-temperature heat sources, supercritical carbon dioxide has received widespread attention due to its low price, non-toxicity, non-flammability and non-explosion, and high low-temperature heat source utilization rate. In addition, in the recovery of LNG cold energy, propane is a widely used circulating working fluid.

[0033] When the conversion efficiency of water electrolysis is 100%, the thermal equilibrium decomposition voltage of water into hydrogen and oxygen is 1.48V. This voltage corresponds to the higher heating value (HHV) of hydrogen and is calculated by the following formula: ; Where, The decomposition voltage of water high calorific value / V; is the higher heating value of hydrogen, which is 285,840 J·mol -1 ; The number of electrons required to produce one molecule is 2 for hydrogen; is the Faraday constant, which is 96,485 coulombs·mol -1 .

[0034] The water decomposition voltage corresponding to the lower heating value (LHV) of hydrogen is 1.23 V. Since the higher heating value represents the total energy of the fuel, including the latent heat of vaporization of water, it better reflects the energy required for water electrolysis than the lower heating value. Therefore, in the technical solutions of the embodiments of the present invention, all calculations are based on the parameters corresponding to the higher heating value.

[0035] In the embodiment of the present invention, the main purpose of modeling and analyzing the medium and low temperature heat source utilization system is to obtain an optimal set of design parameters, and it is usually necessary to use a certain optimization algorithm to obtain this set of parameters. Since traditional optimization algorithms are difficult to solve the optimization problems of complex systems, many scholars have proposed modern optimization algorithms, such as particle swarm algorithms, genetic algorithms, ant colony algorithms, neural network optimization algorithms, etc. The particle swarm algorithm has a simple structure and a clear physical meaning of the optimization process. It is one of the most widely used intelligent optimization algorithms. Specifically, for example, the present invention uses a particle swarm algorithm to optimize the parameters of the system. The process of finding the optimal point is an iterative process. The termination condition of the iteration is generally set to reach the maximum number of cycles or meet the minimum error. The optimization goal is to maximize the thermal efficiency of the cycle.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A solar-liquefied natural gas combined drive hydrogen production system, characterized in that: include: Solar thermal collector (1), heat storage tank (2), auxiliary heater (3), steam generator (4), steam turbine (5), generator, condenser (6), pump (7), refrigeration heat exchanger (8), electrolytic cell (9) and AC-DC converter (10); wherein, The solar thermal collector (1) is provided with a first heat exchange pipe, and the heat storage tank (2) is provided with a first water inlet, a first water outlet, a second water inlet, and a second water outlet; the outlet of the first heat exchange pipe is connected to the first water inlet, and the first water outlet is connected to the inlet of the first heat exchange pipe; water used as a heat storage medium is provided in the heat storage tank (2); The steam generator (4) is provided with a second heat exchange pipe and a third heat exchange pipe, the condenser (6) is provided with a fourth heat exchange pipe and a fifth heat exchange pipe, and the refrigeration heat exchanger (8) is provided with a sixth heat exchange pipe and a seventh heat exchange pipe; the second water outlet is connected to the inlet of the second heat exchange pipe via the auxiliary heater (3), and the outlet of the second heat exchange pipe is connected to the second water inlet; the outlet of the third heat exchange pipe is connected to the inlet of the fourth heat exchange pipe via the steam turbine (5), and the outlet of the fourth heat exchange pipe is connected to the inlet of the third heat exchange pipe via the pump (7) and the sixth heat exchange pipe of the refrigeration heat exchanger (8); the fifth heat exchange pipe is used for introducing liquefied natural gas; The generator is used to output electric energy under the drive of the steam turbine (5); The electrolytic cell (9) is used to produce hydrogen by electrolyzing water using the electric energy output by the generator, and the AC-DC converter (10) is provided between the electrolytic cell (9) and the generator.

2. The solar-liquefied natural gas combined drive hydrogen production system according to claim 1, characterized in that: The seventh heat exchange pipe is used for letting in air.

3. The solar-liquefied natural gas combined drive hydrogen production system according to claim 1, characterized in that: The circulating working fluid circulating between the steam generator (4), the steam turbine (5), the condenser (6), the pump (7), and the refrigeration heat exchanger (8) is supercritical carbon dioxide or propane.

4. The solar-liquefied natural gas combined drive hydrogen production system according to claim 1, characterized in that: During the design process, the system is first modeled based on the effective heat absorbed by the solar collector, the energy balance of the heat storage tank, and the decomposition voltage of the high calorific value of water. Then, the selected optimization algorithm is used to optimize the system parameters with the maximum cycle thermal efficiency as the optimization goal to obtain the optimized system parameters.

5. The solar-liquefied natural gas combined drive hydrogen production system according to claim 4, characterized in that: The optimization algorithms selected are particle swarm optimization, genetic algorithm, ant colony algorithm or neural network optimization algorithm.

6. The solar-liquefied natural gas combined drive hydrogen production system according to claim 4, characterized in that: The solar thermal collector (1) is a flat-plate thermal collector.

7. The solar-liquefied natural gas combined drive hydrogen production system according to claim 6, characterized in that: The effective heat absorbed by the solar collector is the difference between the instantaneous solar radiation heat absorbed by the collector and the heat loss of the collector. The calculation formula in steady state is: ； Where, Effectively absorb heat for the collector; The collector absorbs heat instantly; is the collector area; is the heat dissipation loss of the collector; ； Where, is the instantaneous direct solar radiation on the horizontal plane; is the calculation coefficient of direct solar radiation on the inclined surface; is the transmittance of the flat-plate collector glass; is the absorptivity of the flat-plate collector glass; is the transmittance absorption rate of direct solar radiation on the collector; is the instantaneous solar scattered radiation on the horizontal surface; is the calculation coefficient of solar scattered radiation on the inclined surface; is the calculation coefficient of solar reflected radiation on the inclined surface; is the transmittance absorptivity of the solar scattered radiation on the collector; ； Where, is the total heat dissipation coefficient; is the average surface temperature of the flat-plate collector; is the ambient temperature; ； Where, is the heat dissipation coefficient of the top of the flat-plate collector; is the side heat dissipation coefficient of the flat-plate collector; is the heat dissipation coefficient at the bottom of the flat-plate collector.

8. The solar-liquefied natural gas combined drive hydrogen production system according to claim 4, characterized in that: The energy balance formula of the heat storage tank is: ； Where, is the total heat capacity of the liquid in the thermal storage tank; is the total heat capacity of the thermal storage tank material; is the temperature of the heat storage tank; The heat transferred from the thermal storage tank to the load It is the product of the surface area of ​​the heat storage tank and the heat transfer system.

9. The solar-liquefied natural gas combined drive hydrogen production system according to claim 4, characterized in that: The calculation expression of the decomposition voltage of water high calorific value is: ； Where, It is the decomposition voltage of water high calorific value; is the higher calorific value of hydrogen; The number of electrons required to produce one molecule is 2 for hydrogen; is the Faraday constant.

10. An operating method of the solar-liquefied natural gas combined driven hydrogen production system according to claim 1, characterized in that: The following steps are involved: The solar heat is collected by a solar collector (1) and stored in a heat storage tank (2) using water as a medium; The heat storage tank (2) outputs heat using water as a heat exchange medium, and the output heat is released in the steam generator (4); wherein, when the heat output by the heat storage tank (2) is insufficient, heat is supplemented by the auxiliary heater (3); The high-temperature and high-pressure working fluid output by the steam generator (4) absorbs heat and drives the steam turbine (5) to rotate. The steam turbine (5) performs expansion work and drives the generator to generate electricity and output electrical energy. The working fluid discharged from the steam turbine (5) enters the condenser (6) and exchanges heat with the low-temperature liquefied natural gas, condenses into liquid, is pressurized by the pump (7), and is heated by the refrigeration heat exchanger (8), and then returns to the steam generator (4). In addition, when the electric energy output by the generator is sufficient, the electrolytic cell (9) uses the electric energy output by the generator to electrolyze water to produce hydrogen for consumption.

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