Seawater desalination and electrolytic hydrogen production integrated system and method based on LNG (Liquefied Natural Gas) cold energy recovery and solar-assisted ORC (Organic Rankine Cycle) power generation

Abstract

The invention discloses a seawater desalination and electrolytic hydrogen production integrated system and method based on LNG (Liquefied Natural Gas) cold energy recovery and solar-assisted ORC (Organic Rankine Cycle) power generation. The solar heat collection subsystem is connected with the organic Rankine cycle power generation subsystem in a heat exchange mode, the organic Rankine cycle power generation subsystem is internally provided with a first-stage heat exchange mode and is connected with the LNG cold energy utilization subsystem in a heat exchange mode, and the LNG cold energy utilization subsystem is connected with the frozen sea water desalination subsystem through a heat exchanger. The LNG cold energy utilization subsystem is in transmission connection with the electrolytic hydrogen production unit through the heat exchanger; the method comprises two working processes of seawater desalination and hydrogen production. According to the invention, a multi-energy complementary comprehensive energy system capable of simultaneously realizing two modes of seawater desalination and hydrogen production is formed, the stability and reliability of the system are improved, a seawater desalination and hydrogen production system dependent on single energy is reduced, the energy utilization rate is high, the energy-saving effect is good, and'one water for two purposes' is realized.

Description

Technical Field

[0001] The present invention relates to the field of liquefied natural gas cold energy utilization, and in particular to an integrated system and method for seawater desalination and electrolytic hydrogen production based on LNG cold energy recovery and solar-assisted ORC power generation. Background Art

[0002] Liquefied natural gas (LNG) releases a significant amount of cold energy during its vaporization process (approximately 830–860 kJ / kg, corresponding to temperatures between -162°C and ambient temperature). Traditional LNG receiving terminals typically use seawater for vaporization, resulting in a waste of cold energy (efficiency is less than 20%).

[0003] In recent years, cold energy recovery technology has become a research hotspot. Its low-temperature characteristics can be coupled with high-energy-consuming industrial processes. For example, low-temperature cold energy (below -100°C) is suitable for air separation, carbon dioxide liquefaction, or deep-cold hydrogen liquefaction; medium- and low-temperature cold energy (-50°C to 0°C) can be used for seawater pre-cooling, desalination by freezing, or industrial refrigeration; low-grade cold energy (above 0°C) drives absorption refrigeration or power generation systems. Through graded utilization, the overall efficiency of LNG cold energy can be increased to over 60%, providing a key energy hub for polygeneration systems. In traditional seawater desalination processes, although freezing methods (such as vacuum refrigeration vapor compression, VFVC) have low energy consumption, they require a large amount of cold source. The introduction of LNG cold energy can break through technical bottlenecks. Summary of the Invention

[0004] In order to solve the problems existing in the background technology, the purpose of the present invention is to provide an integrated energy system and method that effectively combines solar energy, ORC power generation, and LNG cold energy to form a multi-energy complementary integrated energy system and method, improve the stability and reliability of the system, and reduce the dependence of seawater desalination and hydrogen production systems on a single energy source. It has the characteristics of using different modes to meet different needs, has high energy utilization rate, can obtain by-product hydrogen in hydrogen production mode, and can obtain by-product concentrated brine in seawater desalination mode, which is suitable for the comprehensive utilization of seawater in offshore LNG receiving stations.

[0005] In order to achieve the above-mentioned object of the invention, the technical solution of the present invention is:

[0006] 1. An integrated system for seawater desalination and electrolysis hydrogen production based on LNG cold energy recovery and solar-assisted ORC power generation:

[0007] It includes a solar heat collection subsystem, an organic Rankine cycle power generation subsystem, an LNG cold energy utilization subsystem, a frozen seawater desalination subsystem, and an electrolysis hydrogen production subsystem; the solar heat collection subsystem is connected to the organic Rankine cycle power generation subsystem for heat exchange, the organic Rankine cycle power generation subsystem is internally provided with a first-stage heat exchanger, the organic Rankine cycle power generation subsystem is connected to the LNG cold energy utilization subsystem for heat exchange, the LNG cold energy utilization subsystem is connected to the frozen seawater desalination subsystem through a heat exchanger, and the LNG cold energy utilization subsystem is connected to the electrolysis hydrogen production unit through a heat exchanger.

[0008] The innovation of the present invention lies in achieving the effects of efficient energy utilization and polygeneration through a structural design of multi-system integration and graded utilization of cold energy, combined with a processing method that complements solar energy and LNG cold energy.

[0009] The solar heat collection subsystem includes a solar heat collector, an oil pump and an ORC evaporator, which are mainly connected in a circular manner to form a solar heat collection circulation loop; the heated pipe of the ORC evaporator is connected to the organic Rankine cycle power generation subsystem;

[0010] The organic Rankine cycle power generation subsystem includes an ORC turbine I, a feed heater, an ORC pump I, an ORC pump II, an ORC heat exchanger, an ORC pump III, an ORC condenser, and an ORC turbine II. The first organic Rankine cycle power generation circuit is mainly formed by the ORC evaporator's heated pipe, the ORC turbine I, a heat exchange pipe of the ORC heat exchanger, the ORC pump II, the feed heater, and the ORC pump I being connected in a circular manner. At the same time, the ORC turbine I and the feed heater are directly connected. The second organic Rankine cycle power generation circuit is mainly formed by another heat exchange pipe of the ORC heat exchanger, the ORC turbine II, the condensing pipe of the ORC condenser, and the ORC pump III being connected in a circular manner. The heated pipe of the ORC condenser is connected to the LNG cold energy utilization subsystem.

[0011] The LNG cold energy utilization subsystem includes an LNG tank, an LNG pump, and an LNG turbine. The LNG tank is connected to the input end of the LNG turbine through the LNG pump and the heated pipeline of the ORC condenser in sequence. The output end of the LNG turbine is used to simultaneously connect to the refrigerated seawater desalination subsystem and the electrolysis hydrogen production subsystem.

[0012] The chilled seawater desalination subsystem includes a seawater filter, a heat exchanger with an ice crystal removal device, a solid-liquid separator, and a melting device. One end of a heat exchange pipe of the heat exchanger is connected to the output end of the LNG turbine, and seawater flows into the seawater filter. The output end of the seawater filter is connected to the input end of the solid-liquid separator through another heat exchange pipe of the heat exchanger. The solid output end of the solid-liquid separator is connected to the melting device.

[0013] The electrolysis hydrogen production subsystem includes a heater, a PEM electrolyzer and a hydrogen production liquefaction circulation loop; the heater is connected to the PEM electrolyzer, the hydrogen output end of the PEM electrolyzer is connected to the hydrogen production liquefaction circulation loop via a heat exchange pipeline of the heat exchanger, and another heat exchange pipeline of the heat exchanger is connected to the output end of the LNG cold energy utilization subsystem.

[0014] The heat exchangers I, III and IV are plate and shell type heat exchangers, and the heat exchanger II is a plate and fin type heat exchanger.

[0015] In the organic Rankine cycle power generation subsystem, one end of the cooling pipe of the ORC evaporator is connected to the input end of the ORC turbine I, that is, the output end of the turbine I is connected to the input end of the ORC pump II in sequence through a heat exchange pipe of the ORC heat exchanger, the output end of the ORC pump II is connected to the first input end of the feed heater, the output end of the feed heater is connected to the input end of the ORC pump I, and the output end of the ORC pump I is connected to the other end of the cooling pipe of the ORC evaporator; at the same time, the output end of the turbine I is connected to the second input end of the feed heater; the working fluid at the turbine outlet is usually a gas-liquid two-phase flow. If the gaseous working fluid is not completely liquefied after heat exchange in the ORC heat exchanger 8, cavitation will occur when it enters the pump, so the gaseous working fluid is directly introduced into the feed heater, and the liquid working fluid is introduced into the ORC heat exchanger 8 for heat exchange.

[0016] One end of the other heat exchange pipe of the ORC heat exchanger is connected to the input end of the ORC turbine II, the output end of the ORC turbine II is connected to one end of the condensation pipe of the ORC condenser, the other end of the condensation pipe of the ORC condenser is connected to the input end of the ORC pump III, and the output end of the ORC pump III is connected to the other end of the other heat exchange pipe of the ORC heat exchanger.

[0017] In the first organic Rankine cycle power generation loop, the heated pipe of the ORC evaporator heats the medium flowing through it and raises its temperature. The heated medium flows into the ORC turbine I to generate electricity. The gaseous working fluid flowing out after power generation is directly input into the feed heater. The liquid working fluid is input into a heat exchange pipe of the ORC heat exchanger for cooling. After cooling, it is pumped into the feed heater through the ORC pump II to mix with the gaseous working fluid. The feed heater mixes the two fluids and heats them to a specific temperature. The output liquid working fluid is pumped back into the heated pipe of the ORC evaporator through the ORC pump I to continue heating and raising its temperature, thus repeating the cycle.

[0018] The feed heater mixes the gaseous working fluid directly flowing out of the ORC turbine I with the working fluid cooled by the ORC heat exchanger, recovering the waste heat of the gaseous working fluid and heating the working fluid to the set temperature, thereby increasing the temperature of the working fluid entering the ORC evaporator, reducing the heating load of the solar energy system, and preventing the temperature of the solar energy system heat transfer oil from being too low after heat exchange in the ORC evaporator. This reduces the temperature difference at both ends of the solar collector and helps extend the life of the equipment.

[0019] The gaseous working fluid flowing out after power generation is directly input into the feed heater, and the liquid working fluid is input into a heat exchange pipeline of the ORC heat exchanger for cooling. After cooling, it is pumped into the feed heater through the ORC pump II to mix with the gaseous working fluid. The feed heater mixes the two fluids and heats them to a specific temperature to output the liquid working fluid.

[0020] In the second organic Rankine cycle power generation loop, another heat exchange pipeline of the ORC heat exchanger heats the medium flowing through it. The heated medium flows into the ORC turbine II to generate electricity. The medium discharged from the generated electricity flows into the condensation pipeline of the ORC condenser to be cooled and exchange heat with liquefied natural gas (LNG). The cooled medium is pumped back into the heat exchange pipeline of the ORC heat exchanger through the ORC pump III to continue to be heated and heated, thus circulating back and forth.

[0021] The hydrogen production liquefaction circulation loop includes a compressor, heat exchanger I, heat exchanger III, an expander, heat exchanger IV, a throttle valve and a receiver; the input end of the compressor is connected to a heat exchange pipeline passing through the heat exchanger, and the output end of the compressor is connected to the receiver through a heat exchange pipeline of heat exchanger I, a heat exchange pipeline of heat exchanger III, and a heat exchange pipeline of heat exchanger IV in sequence, and then through the throttle valve. The receiver is also connected to the input end of the compressor through another heat exchange pipeline of heat exchanger IV, another heat exchange pipeline of heat exchanger III, and another heat exchange pipeline of heat exchanger I in sequence, and is connected to one end of the expander through a pipeline between heat exchanger I and one heat exchange pipeline of heat exchanger III, and the other heat exchange pipeline of heat exchanger IV and heat exchanger III is connected to the other end of the expander.

[0022] It also includes a cooling device and a low-temperature heat exchanger, and the LNG cold energy utilization subsystem and the electrolysis hydrogen production subsystem are connected in sequence through the cooling device and the low-temperature heat exchanger;

[0023] The LNG cold energy utilization subsystem is used to output the liquefied natural gas LNG to the electrolysis hydrogen production subsystem, which is pre-cooled by a cooling device and then input into a heat exchange pipeline of a low-temperature heat exchanger. The gasified natural gas NG is discharged after heat exchange with the hydrogen of the electrolysis hydrogen production subsystem in the low-temperature heat exchanger.

[0024] The electrical output ends of the ORC turbine I and ORC turbine II of the organic Rankine cycle power generation subsystem and the LNG turbine of the LNG cold energy utilization subsystem are connected together and connected to the energy storage device or the electrolysis hydrogen production subsystem.

[0025] The energy storage device adopts lithium ion battery, lead storage battery and the like.

[0026] An electrical switch for switching control is provided between the electrical output end of the LNG turbine of the LNG cold energy utilization subsystem and the energy storage device or the electrolysis hydrogen production subsystem. At the same time, a fluid valve for switching control is provided between the output end of the LNG turbine of the LNG cold energy utilization subsystem and the frozen seawater desalination subsystem and the electrolysis hydrogen production subsystem.

[0027] 2. A method for seawater desalination and electrolysis hydrogen production based on LNG cold energy recovery and solar-assisted ORC power generation, the method including two work processes of seawater desalination and hydrogen production.

[0028] When the electric switch is switched to connect the electrical output of the LNG turbine to the energy storage device, and the fluid valve is used to switch the output of the LNG turbine to connect to the heat exchanger of the refrigerated seawater desalination subsystem, the seawater desalination and electrolysis hydrogen production integrated system enters the seawater desalination working mode;

[0029] When the electrical switch is switched to connect the electrical output end of the LNG turbine to the PEM electrolyzer of the electrolysis hydrogen production subsystem, and the fluid valve is used to switch the output end of the LNG turbine to the electrolysis hydrogen production subsystem via the heat exchanger, the seawater desalination and electrolysis hydrogen production integrated system enters the electrolysis hydrogen production working mode.

[0030] In the desalination working mode, the working process is as follows:

[0031] S1. Solar energy enters the solar thermal collector, performs multi-stage heat transfer on the fluid medium in the solar thermal collection subsystem and the organic Rankine cycle power generation subsystem, and drives the ORC turbine I and ORC turbine II units of the organic Rankine cycle power generation subsystem to generate electricity;

[0032] S2. The liquefied natural gas (LNG) in the LNG cold energy utilization subsystem continues to absorb the waste heat from the power generation process of the organic Rankine cycle power generation subsystem and then enters the LNG turbine of the LNG cold energy utilization subsystem to further generate electricity. At the same time, the electricity generated by the organic Rankine cycle power generation subsystem and the LNG cold energy utilization subsystem is stored in the energy storage device. The remaining cold energy after the LNG cold energy utilization subsystem generates electricity is input into the chilled seawater desalination subsystem for seawater freezing, separation and desalination treatment.

[0033] In the electrolysis hydrogen production working mode, the working process is as follows:

[0034] S1. Solar energy enters the solar thermal collector, performs multi-stage heat transfer on the fluid medium in the solar thermal collection subsystem and the organic Rankine cycle power generation subsystem, and drives the ORC turbine I and ORC turbine II units of the organic Rankine cycle power generation subsystem to generate electricity;

[0035] S2. The liquefied natural gas (LNG) in the LNG cold energy utilization subsystem continues to absorb the waste heat from the power generation process of the organic Rankine cycle power generation subsystem and then enters the LNG turbine of the LNG cold energy utilization subsystem to further generate electricity. At the same time, the electric energy generated by the organic Rankine cycle power generation subsystem and the LNG cold energy utilization subsystem is transmitted to the electrolysis hydrogen production subsystem for electrolysis to prepare hydrogen. The remaining cold energy after the LNG cold energy utilization subsystem generates electricity is input into the electrolysis hydrogen production subsystem for pre-cooling the hydrogen generated by electrolysis.

[0036] Hydrogen liquefaction production consumes a lot of energy. This invention cleverly utilizes LNG to provide a large amount of cold source for the refrigeration-based seawater desalination process and pre-cooling of hydrogen liquefaction, significantly reducing energy consumption. Furthermore, solar energy is a clean energy source. The solar thermal collection subsystem uses solar energy to heat the working fluid, converting it into thermal energy. The system operates without producing greenhouse gases or pollutants, helping to reduce reliance on fossil energy. The Organic Rankine Cycle (ORC) system uses a low-boiling-point organic working fluid to convert thermal energy into electricity. The combination of these two technologies is suitable for powering off-grid areas.

[0037] In the present invention, LNG represents liquefied natural gas, and NG represents vaporized natural gas.

[0038] After adopting the above technical solution, the present invention has the following beneficial effects:

[0039] 1. The present invention provides a comprehensive energy system that effectively combines solar energy, ORC power generation, and LNG cooling energy to form a multi-energy complementary integrated energy system, thereby improving the stability and reliability of the system and reducing the dependence of the seawater desalination and hydrogen production system on a single energy source. It has the characteristics of using different modes to meet different needs, with high energy utilization and good energy-saving effects.

[0040] 2. The present invention utilizes the low temperature characteristics of liquefied natural gas (LNG) to achieve efficient utilization of cold energy. The natural gas formed by gasification of liquefied natural gas (LNG) after utilization can be incorporated into the pipeline network for further utilization.

[0041] 3. The present invention can realize both seawater desalination and hydrogen production modes according to different needs. The fresh water produced by seawater desalination can be used for civilian purposes or as a raw material for hydrogen production, realizing "one water, two uses".

[0042] The by-products oxygen and concentrated brine of the system of the present invention can be collected for further utilization, and are suitable for comprehensive utilization of seawater in offshore LNG receiving stations. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a system structure diagram of the present invention;

[0044] Figure 2 This is a working principle diagram of the seawater desalination mode of the present invention;

[0045] Figure 3 This is a working principle diagram of the hydrogen production mode of the present invention.

[0046] The markings in the figure are as follows: 1-solar collector; 2-oil pump; 3-ORC evaporator; 4-ORC turbine I; 5-feed heater; 6-ORC pump I; 7-ORC pump II; 8-ORC heat exchanger; 9-ORC pump III; 10-ORC condenser; 11-ORC turbine II; 12-LNG pump; 13-LNG turbine; 14-seawater filter; 15-heat exchanger with ice crystal removal device; 16-solid-liquid separator; 17-melting device; 18-cooling device; 19-low-temperature heat exchanger; 20-heater; 21-PEM electrolyzer; 22-compressor; 23-heat exchanger I; 24-heat exchanger II; 25-heat exchanger III; 26-expander; 27-heat exchanger IV; 28-throttle valve; 29-receiver. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0048] like Figure 1 As shown, the overall system includes a solar thermal collection subsystem, an organic Rankine cycle power generation subsystem, an LNG cold energy utilization subsystem, a chilled seawater desalination subsystem, and an electrolysis hydrogen production subsystem; the solar thermal collection subsystem is connected to the organic Rankine cycle power generation subsystem for heat exchange through an evaporator, and the organic Rankine cycle power generation subsystem has a first-stage heat exchange inside. The organic Rankine cycle power generation subsystem is connected to the LNG cold energy utilization subsystem for heat exchange through a condenser, so that there is a three-stage heat exchange from the solar thermal collection subsystem to the LNG cold energy utilization subsystem; the LNG cold energy utilization subsystem is connected to the chilled seawater desalination subsystem through a heat exchanger, and the LNG cold energy utilization subsystem is connected to the electrolysis hydrogen production unit through a heat exchanger.

[0049] The solar thermal collection subsystem includes a solar thermal collector 1, an oil pump 2 and an ORC evaporator 3, and is mainly composed of the solar thermal collector 1, the ORC evaporator 3 and the oil pump 2, which are connected in a circular sequence to form a solar thermal collection circulation loop, that is, the output end of the solar thermal collector 1 is connected to one end of the evaporation pipeline of the ORC evaporator 3, the cooling pipeline of the ORC evaporator 3 is connected to the input end of the oil pump 2, and the output end of the oil pump 2 is connected to the input end of the solar thermal collector 1; the heated pipeline of the ORC evaporator 3 is connected to the organic Rankine cycle power generation subsystem; the solar thermal collector 1 receives sunlight energy to heat the internal circulating fluid medium, and the oil pump 2 drives the fluid medium heated by the solar thermal collector 1 to flow out of the solar thermal collector 1 to the evaporation pipeline of the ORC evaporator 3 for evaporative cooling.

[0050] The organic Rankine cycle power generation subsystem includes an ORC turbine I4, a feed heater 5, an ORC pump I6, an ORC pump II7, an ORC heat exchanger 8, an ORC pump III9, an ORC condenser 10, and an ORC turbine II11. The first organic Rankine cycle power generation circuit is mainly formed by the heating pipe of the ORC evaporator 3, the ORC turbine I4, a heat exchange pipe of the ORC heat exchanger 8, the ORC pump II7, the feed heater 5, and the ORC pump I6, which are connected in a circular manner in sequence. At the same time, the ORC turbine I4 and the feed heater 5 are directly connected. The second organic Rankine cycle power generation circuit is mainly composed of another heat exchange pipeline of the ORC heat exchanger 8, the ORC turbine II 11, the condensation pipeline of the ORC condenser 10 and the ORC pump III 9, which are connected in a circular manner in sequence; the heat receiving pipeline of the ORC condenser 10 is connected to the LNG cold energy utilization subsystem; the first organic Rankine cycle power generation circuit and the solar thermal collection circuit are connected through the ORC evaporator 3 for heat exchange, and the first organic Rankine cycle power generation circuit and the second organic Rankine cycle power generation circuit are connected through the internal ORC heat exchanger 8 for heat exchange.

[0051] like Figure 2 and Figure 3 As shown, in the organic Rankine cycle power generation subsystem, specifically, in the first organic Rankine cycle power generation loop, one end of the cooling pipe of the ORC evaporator 3 is connected to the input end of the ORC turbine I 4, and the output end of the ORC turbine I 4 is connected to the other end of the cooling pipe of the ORC evaporator 3 after passing through the ORC heat exchanger 8, the ORC pump II 7, the feed heater 5 and the ORC pump I 6 in sequence. That is, the output end of the turbine I 4 is connected to the input end of the ORC pump II 7 in sequence through a heat exchange pipe of the ORC heat exchanger 8, the output end of the ORC pump II 7 is connected to the first input end of the feed heater 5, the output end of the feed heater 5 is connected to the input end of the ORC pump I 6, and the output end of the ORC pump I 6 is connected to the other end of the cooling pipe of the ORC evaporator 3; at the same time, the output end of the turbine I 4 is connected to the second input end of the feed heater 5.

[0052] The working fluid at the turbine outlet is usually a gas-liquid two-phase flow. If the gaseous working fluid is not completely liquefied after heat exchange in the ORC heat exchanger 8, cavitation will occur when it enters the pump. Therefore, the gaseous working fluid is directly introduced into the feed heater, and the liquid working fluid is introduced into the ORC heat exchanger 8 for heat exchange.

[0053] In the second organic Rankine cycle power generation loop, one end of the other heat exchange pipe of the ORC heat exchanger 8 is connected to the input end of the ORC turbine II 11, the output end of the ORC turbine II 11 is connected to one end of the condensation pipe of the ORC condenser 10, the other end of the condensation pipe of the ORC condenser 10 is connected to the input end of the ORC pump III 9, and the output end of the ORC pump III 9 is connected to the other end of the other heat exchange pipe of the ORC heat exchanger 8.

[0054] Organic heat transfer oil circulates in the first organic Rankine cycle power generation loop and the pipeline of the first organic Rankine cycle power generation loop.

[0055] like Figure 2 and Figure 3 As shown, in the first organic Rankine cycle power generation circuit, the heating pipeline of the ORC evaporator 3 heats the medium flowing through it and raises its temperature. The heated medium flows into the ORC turbine I 4 to generate electricity. The gaseous working fluid flowing out after power generation is directly input into the feed heater 5. The liquid working fluid is input into a heat exchange pipeline of the ORC heat exchanger 8 for cooling. After cooling, it is pumped into the feed heater 5 through the ORC pump II 7 to mix with the gaseous working fluid. The feed heater 5 mixes the two fluids and heats them to a specific temperature. The output liquid working fluid is pumped back into the heating pipeline of the ORC evaporator 3 through the ORC pump I 6 to continue to be heated and raised in temperature, thus circulating back and forth.

[0056] The feed heater 5 mixes the gaseous working fluid directly flowing out of the ORC turbine Ⅰ 4 with the working fluid cooled by the ORC heat exchanger 8, recovering the waste heat of the gaseous working fluid and heating the working fluid to a set temperature, thereby increasing the temperature of the working fluid entering the ORC evaporator 3, reducing the heating load of the solar energy system, and preventing the temperature of the solar energy system heat transfer oil from being too low after heat exchange in the ORC evaporator 3, thereby reducing the temperature difference at both ends of the solar collector, and helping to extend the life of the equipment.

[0057] The gaseous working fluid flowing out after power generation is directly input into the feed heater 5, and the liquid working fluid is input into a heat exchange pipeline of the ORC heat exchanger 8 for cooling. After cooling, it is pumped into the feed heater 5 through the ORC pump II 7 to mix with the gaseous working fluid. The feed heater 5 mixes the two fluids and heats them to a specific temperature to output the liquid working fluid.

[0058] In the second organic Rankine cycle power generation circuit, another heat exchange pipeline of the ORC heat exchanger 8 heats the medium flowing through it and raises its temperature. The heated medium flows into the ORC turbine II 11 to generate electricity. The medium discharged from the generated electricity flows into the condensation pipeline of the ORC condenser 10 to be cooled and exchange heat with the liquefied natural gas LNG, causing the liquefied natural gas LNG to be heated and raised in temperature. The cooled medium is pumped back into the heat exchange pipeline of the ORC heat exchanger 8 through the ORC pump III 9 to continue to be heated and raised in temperature, thus circulating back and forth.

[0059] The LNG cold energy utilization subsystem includes an LNG tank, an LNG pump 12 and an LNG turbine 13; the LNG tank is connected to the input end of the LNG turbine 13 through the LNG pump 12 and the heated pipeline of the ORC condenser 10 in sequence, and the output end of the LNG turbine 13 is used to simultaneously connect to the refrigerated seawater desalination subsystem and the electrolysis hydrogen production subsystem; specifically, the LNG tank is connected to the input end of the LNG pump 12, the output end of the LNG pump 12 is connected to one end of the heated pipeline of the ORC condenser 10, and the other end of the heated pipeline of the ORC condenser 10 is connected to the input end of the LNG turbine 13.

[0060] The chilled seawater desalination subsystem includes a seawater filter 14, a heat exchanger 15 with an ice crystal removal device, a solid-liquid separator 16 and a melting device 17; one end of a heat exchange pipeline of the heat exchanger 15 is connected to the output end of the LNG turbine 13, and the other end of a heat exchange pipeline of the heat exchanger 15 is used to output gasified natural gas NG; seawater flows into the seawater filter 14, and the output end of the seawater filter 14 is connected to the input end of the solid-liquid separator 16 through another heat exchange pipeline of the heat exchanger 15, and the solid output end of the solid-liquid separator 16 is connected to the melting device 17.

[0061] like Figure 2 As shown, the seawater is filtered by a seawater filter 14, and the heat exchanger 15 with an ice crystal removal device cools the seawater and heats the liquefied natural gas (LNG) output by the LNG turbine 13. After the heat exchange, a portion of the liquefied natural gas (LNG) is vaporized and discharged as natural gas (NG), while the remaining portion remains liquefied and is input into the electrolytic hydrogen production subsystem after pre-cooling and heat exchange. After the seawater is cooled, it is input into a solid-liquid separator 16 for solid-liquid separation, into ice crystals and concentrated brine. The concentrated brine is discharged from the liquid output end, and the ice crystals are input into a melting device 17 for heating and melting to become fresh water.

[0062] The LNG cold energy utilization subsystem is used to output the liquefied natural gas (LNG) to the refrigerated seawater desalination subsystem, which is input to the heat exchanger 15 , where the seawater is cooled and the liquefied natural gas (LNG) is heated to perform heat exchange.

[0063] The electrolysis hydrogen production subsystem includes a heater 20, a PEM electrolyzer 21 and a hydrogen production liquefaction circulation loop; the heater 20 and the PEM electrolyzer 21 are connected to heat the PEM electrolyzer 21, and water is stored in the PEM electrolyzer 21. The hydrogen output end of the PEM electrolyzer 21 is connected to the hydrogen production liquefaction circulation loop via a heat exchange pipeline of the low-temperature heat exchanger 19, and another heat exchange pipeline of the low-temperature heat exchanger 19 is connected to the output end of the LNG cold energy utilization subsystem.

[0064] The hydrogen production liquefaction circulation loop includes a compressor 22, a heat exchanger I 23, a heat exchanger II 24, a heat exchanger III 25, an expander 26, a heat exchanger IV 27, a throttle valve 28 and a receiver 29; the input end of the compressor 22 is connected to a heat exchange pipeline through the low-temperature heat exchanger 19, and the output end of the compressor 22 is connected to the receiver 29 through a heat exchange pipeline of the heat exchanger I 23, a heat exchanger II 24, a heat exchange pipeline of the heat exchanger III 25, and a heat exchange pipeline of the heat exchanger IV 27 in sequence through the throttle valve 28. The receiver 29 is used to receive and store liquid nitrogen and discharge unliquefied gas. The hydrogen receiver 29 is connected to the input end of the compressor 22 through another heat exchange pipeline of the heat exchanger IV 27, another heat exchange pipeline of the heat exchanger III 25, and another heat exchange pipeline of the heat exchanger I 23 in sequence, and is connected to one end of the expander 26 through the pipeline between the heat exchanger I 23 / heat exchanger II 24 and one heat exchange pipeline of the heat exchanger III 25. The heat exchanger IV 27 and another heat exchange pipeline of the heat exchanger III 25 are connected to the other end of the expander 26. The expander 26 is used to expand the hydrogen entering this branch to form low-temperature hydrogen, thereby providing cooling capacity for the heat exchanger I 23 and the heat exchanger III 25.

[0065] like Figure 3 As shown, the PEM electrolyzer 21 receives electrical energy from the ORC turbine I4 and ORC turbine II 11 of the organic Rankine cycle power generation subsystem and the LNG turbine 13 of the LNG cold energy utilization subsystem to perform electrolysis, decomposing water into hydrogen and oxygen. The hydrogen and the liquefied natural gas (LNG) filtered by the LNG cold energy utilization subsystem are heat-exchanged in the low-temperature heat exchanger 19. The hydrogen is cooled and the liquefied natural gas (LNG) is heat-exchanged. After being heated, the liquefied natural gas (LNG) is converted into gasified natural gas (NG) and discharged. The hydrogen is cooled and then enters the compressor 2 2 is compressed into high-pressure gas, then sequentially enters one of the heat exchange lines of heat exchanger I 23, heat exchanger II 24, heat exchanger III 25, and heat exchanger IV 27 for cooling and liquefaction into liquid hydrogen, which is then input into receiver 29. Receiver 29 still retains some unliquefied hydrogen. This unliquefied hydrogen is then heated through another heat exchange line of heat exchanger IV 27, heat exchanger III 25, heat exchanger II 24, and heat exchanger I 23, before returning to compressor 22 for further compression, repeating the cycle. This achieves efficient conversion to liquid hydrogen and improves efficiency. An expander 26 is provided between the two heat exchange lines of the heat exchanger to expand the hydrogen entering this branch, forming low-temperature hydrogen, which provides cooling for heat exchanger I 23 and heat exchanger III 25.

[0066] It also includes a cooling device 18 and a low-temperature heat exchanger 19, and the LNG cold energy utilization subsystem and the electrolysis hydrogen production subsystem are connected in sequence through the cooling device 18 and the low-temperature heat exchanger 19;

[0067] The LNG cold energy utilization subsystem is used to output the liquefied natural gas LNG to the electrolysis hydrogen production subsystem. After pre-cooling treatment by the cooling device 18, it is input into a heat exchange pipeline of the low-temperature heat exchanger 19. After heat exchange with the hydrogen of the electrolysis hydrogen production subsystem in the low-temperature heat exchanger 19, the gasified natural gas NG is discharged from the other end of the heat exchange pipeline. The hydrogen is cooled and the liquefied natural gas LNG is heated to perform heat exchange.

[0068] The electrical output ends of the ORC turbine I4 and ORC turbine II11 of the organic Rankine cycle power generation subsystem and the LNG turbine 13 of the LNG cold energy utilization subsystem are connected together and connected to the energy storage device or the PEM electrolyzer 21 of the electrolysis hydrogen production subsystem.

[0069] An electric switch for switching control is provided between the electrical output end of the LNG turbine 13 of the LNG cold energy utilization subsystem and the PEM electrolyzer 21 of the energy storage device or the electrolysis hydrogen production subsystem. The electric switch is used to switch the electrical energy output from the electrical output end of the LNG turbine 13 to the energy storage device or the PEM electrolyzer 21 of the electrolysis hydrogen production subsystem. At the same time, a fluid valve for switching control is provided between the liquefied natural gas output end of the LNG turbine 13 of the LNG cold energy utilization subsystem and the refrigerated seawater desalination subsystem and the electrolysis hydrogen production subsystem. The fluid valve is used to switch the liquefied natural gas output from the output end of the LNG turbine 13 to the heat exchanger 15 of the refrigerated seawater desalination subsystem or to the electrolysis hydrogen production subsystem via the low-temperature heat exchanger 19.

[0070] The system of the present invention includes two working methods and processes: seawater desalination and hydrogen production:

[0071] When the electric switch is switched to connect the electrical output end of the LNG turbine 13 to the energy storage device, and the fluid valve is used to switch the output end of the LNG turbine 13 to the heat exchanger 15 of the refrigerated seawater desalination subsystem, the seawater desalination and electrolysis hydrogen production integrated system enters the seawater desalination working mode.

[0072] When the electrical switch is switched to connect the electrical output end of the LNG turbine 13 to the PEM electrolyzer 21 of the electrolysis hydrogen production subsystem, and the fluid valve is used to switch the output end of the LNG turbine 13 to the electrolysis hydrogen production subsystem via the low-temperature heat exchanger 19, the seawater desalination and electrolysis hydrogen production integrated system enters the electrolysis hydrogen production working mode.

[0073] like Figure 2 As shown, in the seawater desalination working mode, the electrolysis hydrogen production subsystem does not work, and the working process is:

[0074] S1, solar energy enters the solar thermal collector 1, performs multi-stage heat transfer on the fluid medium in the solar thermal collection subsystem and the organic Rankine cycle power generation subsystem, and drives the ORC turbine Ⅰ4 and ORC turbine Ⅱ11 units of the organic Rankine cycle power generation subsystem to generate electricity;

[0075] S2. The liquefied natural gas (LNG) in the LNG cold energy utilization subsystem continues to absorb the waste heat from the power generation process of the organic Rankine cycle power generation subsystem and then enters the LNG turbine 13 of the LNG cold energy utilization subsystem to further generate electricity, thereby improving power generation efficiency and energy utilization rate. At the same time, the electric energy generated by the organic Rankine cycle power generation subsystem and the LNG cold energy utilization subsystem is stored in the energy storage device. The remaining cold energy after the LNG cold energy utilization subsystem generates electricity is input into the chilled seawater desalination subsystem for seawater freezing, separation and desalination treatment. Specifically, the chilled seawater desalination subsystem uses the remaining cold energy after the LNG cold energy utilization subsystem generates electricity to perform seawater freezing treatment, thereby separating fresh water and salt water, and then outputting fresh water for desalination.

[0076] like Figure 2 As shown, the implementation of seawater desalination mode is as follows:

[0077] Thermal oil is introduced into the solar thermal collector 1. By utilizing the concentrated energy from the solar collector 1, the thermal oil reaches the required temperature. Driven by the oil pump 2, the thermal oil, carrying a large amount of potential energy, is directed to the first organic Rankine cycle through the ORC evaporator 3. The ORC evaporator 3 outputs the heated and evaporated thermal oil, which then drives the ORC turbine 1 4 through the first organic Rankine cycle to generate electricity.

[0078] The working fluid at the outlet of ORC turbine I 4 is in a gas-liquid two-phase state. The gaseous working fluid is directly introduced into the feed heater 5. Driven by ORC pump II 7, the liquid working fluid is cooled in the ORC heat exchanger 8 and then pumped into the feed heater 5. (The outlet of ORC turbine I 4 is in a gas-liquid two-phase state. The gaseous working fluid is directly introduced into the feed heater 5, while the liquid working fluid enters the ORC heat exchanger 8 for heat exchange.) The feed heater 5, integrated into the first organic Rankine cycle loop, mixes the working fluids introduced from the two branches and heats them to a specific temperature to avoid excessive temperature differences in the ORC evaporator 3 and maintain the high temperature of the thermal oil at the inlet of the solar collector 1. ORC pump I 6 drives the fluid at the outlet of the feed heater 5 for the next cycle.

[0079] The gaseous working fluid at the outlet of the ORC turbine Ⅰ 4 and the fluid after heat exchange in the ORC heat exchanger 8 are mixed in the feed heater and heated to a specific temperature. This can prevent the temperature of the solar system thermal oil from dropping too much after heat exchange with the fluid exiting the feed heater. That is, the high temperature of the thermal oil at the inlet of the solar collector 1 is increased, so that the temperature difference between the two ends of the solar collector is not too large. This can reduce damage to the equipment and help improve efficiency.

[0080] In the second organic Rankine cycle loop, driven by the ORC pump III 9, the second organic Rankine cycle absorbs heat and evaporates in the ORC heat exchanger 8, driving the ORC turbine II 11 to generate electricity, and then is condensed in the ORC condenser 10, so that it returns to liquid in the next cycle.

[0081] Driven by pump 12, the liquefied natural gas in the liquefied natural gas tank absorbs heat through the ORC condenser 10. The heated liquefied natural gas flow undergoes expansion in the LNG turbine 13 to generate electricity. The electricity generated in this mode is stored in an energy storage device for use at other times.

[0082] After passing through the seawater filter 14, the seawater enters the heat exchanger 15 equipped with an ice crystal removal device, where it is frozen by the liquefied natural gas stream output by the LNG turbine 13. After absorbing heat, the liquefied natural gas vaporizes and is discharged into the external natural gas pipeline. The frozen seawater enters the solid-liquid separator 16 for solid-liquid separation. The separated brine can be collected for further use, and the separated ice crystals continue to enter the melting device 17 to melt and obtain fresh water.

[0083] like Figure 3 As shown, in the electrolysis hydrogen production working mode, the chilled seawater desalination subsystem does not work, and the working process is:

[0084] S1, solar energy enters the solar thermal collector 1, performs multi-stage heat transfer on the fluid medium in the solar thermal collection subsystem and the organic Rankine cycle power generation subsystem, and drives the ORC turbine Ⅰ4 and ORC turbine Ⅱ11 units of the organic Rankine cycle power generation subsystem to generate electricity;

[0085] S2. The liquefied natural gas LNG of the LNG cold energy utilization subsystem continues to absorb the waste heat during the power generation process of the organic Rankine cycle generator subsystem and then enters the LNG turbine 13 of the LNG cold energy utilization subsystem to further generate electricity, thereby improving power generation efficiency and energy utilization rate;

[0086] At the same time, the electric energy generated by the organic Rankine cycle power generation subsystem and the LNG cold energy utilization subsystem is transmitted to the PEM electrolyzer 21 of the electrolysis hydrogen production subsystem for electrolysis, and is used to electrolyze water in the hydrogen production unit to produce hydrogen. The remaining cold energy after the LNG cold energy utilization subsystem generates electricity is input into the electrolysis hydrogen production subsystem for pre-cooling the hydrogen produced by electrolysis.

[0087] like Figure 3 As shown, the implementation of hydrogen production mode is as follows:

[0088] Thermal oil is introduced into the solar thermal collector 1. By utilizing the concentrated energy from the solar collector 1, the thermal oil reaches the required temperature. Driven by the oil pump 2, the thermal oil, carrying a large amount of potential energy, is directed to the first organic Rankine cycle through the ORC evaporator 3. The ORC evaporator 3 outputs a high-temperature working fluid, which then drives the ORC turbine I 4 through the first organic Rankine cycle to generate electricity.

[0089] The working fluid at the outlet of ORC turbine I 4 is in a gas-liquid two-phase state. The gaseous working fluid is directly introduced into the feed heater 5. Driven by ORC pump II 7, the liquid working fluid is cooled in the ORC heat exchanger 8 and then pumped into the feed heater 5. (The outlet of ORC turbine I 4 is in a gas-liquid two-phase state. The gaseous working fluid is directly introduced into the feed heater 5, while the liquid working fluid enters the ORC heat exchanger 8 for heat exchange.) The feed heater 5, integrated into the first organic Rankine cycle loop, mixes the working fluids introduced from the two branches and heats them to a specific temperature to avoid excessive temperature differences in the ORC evaporator 3 and maintain the high temperature of the thermal oil at the inlet of the solar collector 1. ORC pump I 6 drives the fluid at the outlet of the feed heater 5 for the next cycle.

[0090] The gaseous working fluid at the outlet of the ORC turbine Ⅰ 4 and the fluid after heat exchange in the ORC heat exchanger 8 are mixed in the feed heater and heated to a specific temperature. This can prevent the temperature of the solar system thermal oil from dropping too much after heat exchange with the fluid exiting the feed heater. That is, the high temperature of the thermal oil at the inlet of the solar collector 1 is increased, so that the temperature difference between the two ends of the solar collector is not too large. This can reduce damage to the equipment and help improve efficiency.

[0091] In the second organic Rankine cycle loop, driven by the ORC pump III 9, the second organic Rankine cycle absorbs heat and evaporates in the ORC heat exchanger 8, driving the ORC turbine II 11 to generate electricity, and then is condensed in the ORC condenser 10, so that it returns to liquid in the next cycle.

[0092] The liquefied natural gas in the liquefied natural gas tank is driven by the LNG pump 12 and absorbs heat through the ORC condenser 10. The heated liquefied natural gas flow undergoes expansion in the LNG turbine 13 to generate electricity, and then enters the cooling device 18 and then the low-temperature heat exchanger 19 for pre-cooling hydrogen. The gasified natural gas is then merged into the natural gas pipeline.

[0093] Water is introduced into the heater 20, and then the heated water enters the PEM electrolyzer 21 for electrolysis to produce hydrogen and oxygen. The electricity required for the heater 20 and the PEM electrolyzer comes from the self-generated energy of the system ORC turbine I4, ORC turbine II 11, LNG turbine 13, etc. The generated oxygen is collected separately, and the hydrogen enters the low-temperature heat exchanger 19 for pre-cooling, and then enters the hydrogen production liquefaction cycle.

[0094] The hydrogen enters the compressor 22 and is compressed into a high-temperature and high-pressure gas. It first enters the heat exchanger I (23) for cooling, so that the temperature of the hydrogen drops to the temperature before compression, achieving isothermal compression. It is then cooled by liquid nitrogen in the heat exchanger II 24. The gas is then divided into two parts. One part continues to pass through the heat exchanger III 25 and the heat exchanger IV 27 to be cooled, and then passes through the throttle valve 28. At this time, part of this part of the gas is converted into liquid and discharged from the receiver 29. The part that has not been converted into liquid is heat exchanged through the heat exchanger IV 27; the other part is expanded by the expander and mixed with the part of the gas that has not been converted into liquid before. It passes through the heat exchanger III 25 and the heat exchanger I 23 for heat exchange, and then returns to the front of the compressor 22, thus forming a liquefaction cycle and completing the liquid hydrogen production process.

[0095] In summary, the present invention provides a comprehensive energy system that effectively combines solar energy, ORC power generation, and LNG cold energy to form a multi-energy complementary integrated energy system, improves the stability and reliability of the system, and reduces the dependence of the seawater desalination and hydrogen production system on a single energy source. It has the characteristics of using different modes to meet different needs, high energy utilization rate, and good energy-saving effect. It uses the low-temperature characteristics of liquefied natural gas (LNG) to achieve efficient utilization of cold energy. The natural gas formed by the gasification of liquefied natural gas (LNG) after utilization can be incorporated into the pipeline network for further utilization. According to different needs, it can be used in two modes: seawater desalination and hydrogen production. The fresh water produced by seawater desalination can be used for civilian purposes or as a raw material for hydrogen production, realizing "one water, two uses". The by-products of the system, oxygen and concentrated brine, can be collected for further utilization, which is suitable for the comprehensive utilization of seawater at offshore LNG receiving stations.

[0096] The above specific embodiments are used to illustrate the present invention rather than to limit the present invention. Any modifications and changes made to the present invention within the spirit of the present invention and the protection scope of the claims shall fall within the protection scope of the present invention.

[0097] The above description is only a preferred embodiment of the present invention. Therefore, any equivalent changes or modifications made according to the structure, characteristics and principles described in the scope of the patent application of the present invention are included in the scope of the patent application of the present invention.

Claims

1. An integrated system for seawater desalination and electrolysis hydrogen production based on LNG cold energy recovery and solar-assisted ORC power generation, characterized by: It includes a solar heat collection subsystem, an organic Rankine cycle power generation subsystem, an LNG cold energy utilization subsystem, a frozen seawater desalination subsystem, and an electrolysis hydrogen production subsystem; the solar heat collection subsystem is connected to the organic Rankine cycle power generation subsystem for heat exchange, the organic Rankine cycle power generation subsystem is internally provided with a first-stage heat exchanger, the organic Rankine cycle power generation subsystem is connected to the LNG cold energy utilization subsystem for heat exchange, the LNG cold energy utilization subsystem is connected to the frozen seawater desalination subsystem through a heat exchanger, and the LNG cold energy utilization subsystem is connected to the electrolysis hydrogen production unit through a heat exchanger.

2. The integrated system of seawater desalination and electrolysis hydrogen production based on LNG cold energy recovery and solar-assisted ORC power generation according to claim 1 is characterized in that: The solar heat collection subsystem comprises a solar heat collector (1), an oil pump (2) and an ORC evaporator (3), and is mainly composed of the solar heat collector (1), the ORC evaporator (3) and the oil pump (2) being connected in a circular manner to form a solar heat collection circulation loop; the heat receiving pipe of the ORC evaporator (3) is connected to the organic Rankine cycle power generation subsystem; The organic Rankine cycle power generation subsystem includes an ORC turbine I (4), a feed heater (5), an ORC pump I (6), an ORC pump II (7), an ORC heat exchanger (8), an ORC pump III (9), an ORC condenser (10) and an ORC turbine II (11); the first organic Rankine cycle power generation circuit is mainly formed by the heat receiving pipe of the ORC evaporator (3), the ORC turbine I (4), a heat exchange pipe of the ORC heat exchanger (8), the ORC pump II (7), the feed heater (5) and the ORC pump I (6) being connected in a circular manner, while the ORC turbine I (4) and the feed heater (5) are directly connected, and the second organic Rankine cycle power generation circuit is mainly formed by the other heat exchange pipe of the ORC heat exchanger (8), the ORC turbine II (11), the condensation pipe of the ORC condenser (10) and the ORC pump III (9) being connected in a circular manner; the heat receiving pipe of the ORC condenser (10) is connected to the LNG cold energy utilization subsystem; The LNG cold energy utilization subsystem comprises an LNG tank, an LNG pump (12) and an LNG turbine (13); the LNG tank is connected to the input end of the LNG turbine (13) through the LNG pump (12) and the heated pipeline of the ORC condenser (10) in sequence, and the output end of the LNG turbine (13) is used to simultaneously connect to the refrigerated seawater desalination subsystem and the electrolytic hydrogen production subsystem; The chilled seawater desalination subsystem comprises a seawater filter (14), a heat exchanger (15) with an ice crystal discharge device, a solid-liquid separator (16) and a melting device (17); one end of a heat exchange pipeline of the heat exchanger (15) is connected to the output end of the LNG turbine (13), seawater flows into the seawater filter (14), the output end of the seawater filter (14) is connected to the input end of the solid-liquid separator (16) via another heat exchange pipeline of the heat exchanger (15), and the solid output end of the solid-liquid separator (16) is connected to the melting device (17); The electrolytic hydrogen production subsystem comprises a heater (20), a PEM electrolyzer (21) and a hydrogen production liquefaction circulation loop; the heater (20) is connected to the PEM electrolyzer (21), the hydrogen output end of the PEM electrolyzer (21) is connected to the hydrogen production liquefaction circulation loop via a heat exchange pipeline of a heat exchanger, and another heat exchange pipeline of the heat exchanger is connected to the output end of the LNG cold energy utilization subsystem.

3. The integrated system of seawater desalination and electrolysis hydrogen production based on LNG cold energy recovery and solar-assisted ORC power generation according to claim 1 is characterized in that: In the organic Rankine cycle power generation subsystem, one end of the cooling pipe of the ORC evaporator (3) is connected to the input end of the ORC turbine I (4), that is, the output end of the turbine I (4) is connected to the input end of the ORC pump II (7) via a heat exchange pipe of the ORC heat exchanger (8), the output end of the ORC pump II (7) is connected to the first input end of the feed heater (5), the output end of the feed heater (5) is connected to the input end of the ORC pump I (6), and the output end of the ORC pump I (6) is connected to the other end of the cooling pipe of the ORC evaporator (3); at the same time, the output end of the turbine I (4) is connected to the second input end of the feed heater (5); One end of the other heat exchange pipe of the ORC heat exchanger (8) is connected to the input end of the ORC turbine II (11), the output end of the ORC turbine II (11) is connected to one end of the condensation pipe of the ORC condenser (10), the other end of the condensation pipe of the ORC condenser (10) is connected to the input end of the ORC pump III (9), and the output end of the ORC pump III (9) is connected to the other end of the other heat exchange pipe of the ORC heat exchanger (8).

4. The integrated system of seawater desalination and electrolysis hydrogen production based on LNG cold energy recovery and solar-assisted ORC power generation according to claim 3 is characterized in that: In the first organic Rankine cycle power generation circuit, the heating pipe of the ORC evaporator (3) heats the medium flowing through it and raises its temperature. The heated medium flows into the ORC turbine I (4) to generate electricity. The gaseous working fluid flowing out after power generation is directly input into the feed heater (5). The liquid working fluid is input into a heat exchange pipe of the ORC heat exchanger (8) for cooling. After cooling, it is pumped into the feed heater (5) through the ORC pump II (7) to mix with the gaseous working fluid. The feed heater (5) mixes the two fluids and heats them to a specific temperature. The output liquid working fluid is pumped back into the heating pipe of the ORC evaporator (3) through the ORC pump I (6) to continue to be heated and raised in temperature, thus circulating back and forth. In the second organic Rankine cycle power generation circuit, another heat exchange pipeline of the ORC heat exchanger (8) heats the medium flowing through it and raises its temperature. The heated medium flows into the ORC turbine II (11) to generate electricity. The medium discharged from the generated electricity flows into the condensation pipeline of the ORC condenser (10) to be cooled and to exchange heat with liquefied natural gas (LNG). The cooled medium is pumped back into the heat exchange pipeline of the ORC heat exchanger (8) through the ORC pump III (9) to continue to be heated and raised in temperature, thus circulating back and forth.

5. The integrated system of seawater desalination and electrolysis hydrogen production based on LNG cold energy recovery and solar-assisted ORC power generation according to claim 1 is characterized in that: The hydrogen production liquefaction circulation loop comprises a compressor (22), a heat exchanger I (23), a heat exchanger III (25), an expander (26), a heat exchanger IV (27), a throttle valve (28) and a receiver (29); the input end of the compressor (22) is connected to a heat exchange pipeline through the heat exchanger, and the output end of the compressor (22) is connected to the throttle valve (28) after passing through a heat exchange pipeline of the heat exchanger I (23), a heat exchange pipeline of the heat exchanger III (25), a heat exchange pipeline of the heat exchanger IV (27) in sequence. The receiver (29) is connected to the input end of the compressor (22) through another heat exchange pipeline of the heat exchanger IV (27), another heat exchange pipeline of the heat exchanger III (25), and another heat exchange pipeline of the heat exchanger I (23). The pipeline between the heat exchanger I (23) and one heat exchange pipeline of the heat exchanger III (25) is connected to one end of the expander (26). The other heat exchange pipeline between the heat exchanger IV (27) and the heat exchanger III (25) is connected to the other end of the expander (26).

6. The integrated system of seawater desalination and electrolysis hydrogen production based on LNG cold energy recovery and solar-assisted ORC power generation according to claim 1 is characterized in that: It also includes a cooling device (18) and a low-temperature heat exchanger (19), wherein the LNG cold energy utilization subsystem and the electrolysis hydrogen production subsystem are sequentially connected via the cooling device (18) and the low-temperature heat exchanger (19); The LNG cold energy utilization subsystem is used to output the liquefied natural gas LNG to the electrolysis hydrogen production subsystem, which is pre-cooled by a cooling device (18) and then input into a heat exchange pipeline of a low-temperature heat exchanger (19), and then the gasified natural gas NG is discharged after heat exchange with the hydrogen of the electrolysis hydrogen production subsystem in the low-temperature heat exchanger (19).

7. The integrated system of seawater desalination and electrolysis hydrogen production based on LNG cold energy recovery and solar-assisted ORC power generation according to claim 1 is characterized in that: The electrical output ends of the ORC turbine I (4) and ORC turbine II (11) of the organic Rankine cycle power generation subsystem and the LNG turbine (13) of the LNG cold energy utilization subsystem are connected together and connected to an energy storage device or an electrolytic hydrogen production subsystem.

8. The integrated system of seawater desalination and electrolysis hydrogen production based on LNG cold energy recovery and solar-assisted ORC power generation according to claim 1 is characterized in that: An electric switch for switching control is provided between the electrical output end of the LNG turbine (13) of the LNG cold energy utilization subsystem and the energy storage device or the electrolysis hydrogen production subsystem. At the same time, a fluid valve for switching control is provided between the output end of the LNG turbine (13) of the LNG cold energy utilization subsystem and the frozen seawater desalination subsystem and the electrolysis hydrogen production subsystem.

9. A method for seawater desalination and electrolysis hydrogen production based on LNG cold energy recovery and solar-assisted ORC power generation, applied to the seawater desalination and electrolysis hydrogen production integrated system of claims 1-8, characterized in that: The method includes two working processes of seawater desalination and hydrogen production. When the electric switch is switched to connect the electric output end of the LNG turbine (13) to the energy storage device, and the fluid valve is used to switch the output end of the LNG turbine (13) to connect to the heat exchanger (15) of the refrigerated seawater desalination subsystem, the seawater desalination and electrolytic hydrogen production integrated system performs the seawater desalination working mode; When the electric switch is switched to connect the electric output end of the LNG turbine (13) to the PEM electrolyzer (21) of the electrolytic hydrogen production subsystem, and the fluid valve is used to switch the output end of the LNG turbine (13) to the electrolytic hydrogen production subsystem via the heat exchanger, the seawater desalination and electrolytic hydrogen production integrated system enters the electrolytic hydrogen production working mode.

10. The method for seawater desalination and electrolysis hydrogen production based on LNG cold energy recovery and solar-assisted ORC power generation according to claim 9, characterized in that: In the desalination working mode, the working process is as follows: S1, solar energy enters the solar thermal collector (1), performs cyclic multi-stage heating transfer on the fluid medium in the solar thermal collector subsystem and the organic Rankine cycle power generation subsystem, and drives the ORC turbine I (4) and ORC turbine II (11) units of the organic Rankine cycle power generation subsystem to generate electricity; S2. The liquefied natural gas (LNG) in the LNG cold energy utilization subsystem continues to absorb the waste heat in the power generation process of the organic Rankine cycle power generation subsystem and then enters the LNG turbine (13) of the LNG cold energy utilization subsystem to further generate electricity. At the same time, the electric energy generated by the organic Rankine cycle power generation subsystem and the LNG cold energy utilization subsystem is stored in the energy storage device, and the remaining cold energy after the LNG cold energy utilization subsystem generates electricity is input into the refrigerated seawater desalination subsystem for seawater freezing, separation and desalination treatment. In the electrolysis hydrogen production working mode, the working process is as follows: S1, solar energy enters the solar thermal collector (1), performs cyclic multi-stage heating transfer on the fluid medium in the solar thermal collector subsystem and the organic Rankine cycle power generation subsystem, and drives the ORC turbine I (4) and ORC turbine II (11) units of the organic Rankine cycle power generation subsystem to generate electricity; S2. The liquefied natural gas (LNG) in the LNG cold energy utilization subsystem continues to absorb the waste heat in the power generation process of the organic Rankine cycle power generation subsystem and then enters the LNG turbine (13) of the LNG cold energy utilization subsystem to further generate electricity; at the same time, the electric energy generated by the organic Rankine cycle power generation subsystem and the LNG cold energy utilization subsystem is transmitted to the electrolysis hydrogen production subsystem for electrolysis to prepare hydrogen, and the remaining cold energy after the LNG cold energy utilization subsystem generates electricity is input into the electrolysis hydrogen production subsystem for pre-cooling the hydrogen generated by electrolysis.

Images