Solar distillation seawater desalination system with multi-heat-source partition heat supply

Abstract

The invention relates to the technical field of seawater desalination, and discloses a solar distillation seawater desalination system for multi-heat-source partition heat supply, which integrates a gas engine heat pump unit, a solar distillation unit and an optional salinity gradient energy utilization interface unit. The gas engine drives the compressor to operate and generates cylinder sleeve water and flue gas waste heat, and the cylinder sleeve water and the flue gas waste heat are introduced into the lower area of the solar distiller through the waste heat recovery unit to preheat seawater; the heat pump condenser exchanges heat with the upper middle area of the distiller to stably heat and evaporate interface water, so that different heat source partition heat supply modes are formed. And fresh water and concentrated solution generated by distillation are respectively collected. The salinity difference energy utilization interface unit is connected into the salinity difference energy utilization device when energy recovery is needed. The system realizes gradient utilization of multiple heat sources, improves the distillation efficiency and the operation stability, and can recycle salinity gradient energy as required.

Description

Technical Field

[0001] This invention relates to the field of seawater desalination technology, and in particular to a solar distillation seawater desalination system with multiple heat sources and zoned heating. Background Technology

[0002] Water resources are becoming increasingly scarce and unevenly distributed. Seawater desalination is one of the key technologies to solve this problem. Traditional distillation methods (such as multi-stage flash distillation and multi-effect distillation) have high energy consumption. Although reverse osmosis has improved efficiency, it faces problems such as membrane fouling and high pressure requirements. Solar distillation, as a low-carbon and environmentally friendly seawater desalination method, has advantages such as simple structure and low operation and maintenance costs. However, its water production efficiency is greatly affected by weather conditions, and the water production per unit area is limited, making it difficult to meet large-scale freshwater demand. To improve the efficiency of solar distillation, researchers often combine it with auxiliary heat sources, such as heat pump systems, to increase the evaporation temperature and accelerate the water vapor separation process. However, heat pump systems require secondary energy, namely electricity, and compared with primary energy, their energy storage and user energy costs are higher. At the same time, there is a significant salinity difference between the concentrated brine produced during seawater desalination and the desalinated freshwater, providing ideal conditions for reverse electrodialysis (RED) power generation. Coupled with the RED system and the seawater desalination process, energy can be used in a cascade manner, further improving the overall energy utilization efficiency of the system.

[0003] Against the backdrop of severe energy security and climate challenges, improving the overall efficiency of energy utilization and reducing fossil fuel consumption have become key issues in the energy transition of various countries. While traditional power systems, represented by gas engines, are widely used in industry and power generation, their energy utilization efficiency still has significant room for improvement. Research data shows that approximately 35-40% of the energy in a gas engine is converted into effective work output, while more than 50% is lost as waste heat from cylinder liner water and high-temperature flue gas, causing significant energy waste and thermal pollution. Effective recovery of this waste heat could provide a stable auxiliary heat source for seawater desalination, thereby improving the overall energy efficiency of the system. More importantly, existing gas engine systems are functionally singular, generally focusing on outputting mechanical work or electrical energy, lacking synergistic optimization of multiple energy forms such as fuel chemical energy, waste heat, and environmental energy. This makes it impossible to build a clean and efficient coupled system, and difficult to adapt to the technical requirements of future energy systems.

[0004] Therefore, there is an urgent need for a solar distillation seawater desalination system that can achieve multi-heat source zoned heating. Summary of the Invention

[0005] The purpose of this invention is to provide a solar distillation seawater desalination system with multiple heat sources and zoned heating. The system aims to achieve cascaded energy utilization during seawater desalination by applying different heat sources to different distillation zones of the still, and to recover electrical energy, thereby improving the system's energy utilization efficiency and operational stability, and further utilizing salinity gradient energy when needed.

[0006] This invention provides a solar distillation seawater desalination system with multi-heat source zoned heating, comprising: A gas engine heat pump unit includes a compressor, a condenser, an evaporator, and a gas engine, wherein the compressor, condenser, and evaporator are interconnected, and the gas engine is connected to the compressor; The solar distillation unit includes a solar distiller, freshwater pipelines, a freshwater storage tank, and a distillate storage tank. The waste heat recovery and lower heating unit is used to introduce the waste heat from the cylinder liner water and / or the waste heat from the flue gas generated during the operation of the gas engine into the lower distillation area of ​​the solar still to preheat the seawater entering the solar still 11. The upper heating unit of the condenser is configured to exchange heat with the middle or upper distillation area of ​​the solar still, and is used to stably heat the water near the evaporation interface. The salinity gradient energy utilization interface unit is connected to the distillate storage tank and the seawater supply unit, and is used to connect to the salinity gradient energy utilization device when energy recovery is required. The waste heat recovery and lower heating unit and the upper heating unit of the condenser respectively act on different distillation functional areas of the solar still. The lower distillation area is used for seawater preheating, and the upper distillation area is used for heating the evaporation interface.

[0007] Through the above technical solution, different heat sources act on different areas of the still according to their temperature characteristics and stability, realizing zoned heating and synergistic effect, thereby improving distillation efficiency and enhancing system operation stability.

[0008] Preferably, the gas engine heat pump unit further includes a throttling valve; the condenser includes a condensing refrigerant pipe, and the evaporator includes an evaporating refrigerant pipe; The compressor outlet is connected to the condensing refrigerant pipeline inlet, the condensing refrigerant pipeline outlet is connected to the evaporating refrigerant pipeline inlet, the evaporating refrigerant pipeline outlet is connected to the compressor, and the throttle valve is located between the condensing refrigerant pipeline and the evaporating refrigerant pipeline.

[0009] Preferably, the waste heat recovery and lower heating unit includes a cylinder liner water heat exchanger and a flue gas heat exchanger. The heat exchange outlets of the cylinder liner water heat exchanger and the flue gas heat exchanger are connected to the lower distillation area of ​​the solar still. The cylinder liner water heat exchanger includes an inner cylinder liner and an outer cylinder liner. The flue gas heat exchanger includes a flue gas pipe and a flue gas heat exchange shell. The heat exchange outlet of the gas engine is connected to the inner cylinder liner inlet, the outer cylinder liner inlet is connected to the outlet of the heat exchange water storage tank, the outer cylinder liner outlet is connected to the flue gas heat exchange shell inlet, and the flue gas heat exchange shell outlet is connected to the heat exchanger. The exhaust gas outlet of the gas engine is connected to the exhaust gas duct inlet, and the exhaust gas duct outlet is connected to the outside.

[0010] Preferably, the evaporative refrigerant pipe is disposed inside the solar distiller and is located above the freshwater pipe; the condenser is configured to exchange heat with the upper water body region of the solar distiller, the upper water body region being located at the evaporation interface of the solar distiller.

[0011] Preferably, the solar still is connected to the evaporator, the freshwater pipe is located in the middle of the solar still, the freshwater storage tank is connected to the freshwater pipe, the heat exchanger is located at the bottom of the solar still and is used to heat and evaporate the seawater in the solar still, and the distillate storage tank is connected to the solar still.

[0012] Preferably, the solar distillation unit includes a heat exchanger storage tank and a cooling water pump. The heat exchanger outlet is connected to the heat exchanger storage tank inlet, the heat exchanger storage tank outlet is connected to the cooling water pump inlet, and the cooling water pump outlet is connected to the outer cylinder liner inlet.

[0013] Preferably, the concentrated solution outlet of the solar still is connected to the distillate storage tank, and the distillate storage tank is connected to the concentrated solution inlet of the salinity gradient energy utilization interface unit via a distillate pump.

[0014] Preferably, the salinity gradient energy utilization device connected to the salinity gradient energy utilization interface unit is a reverse electrodialysis power generation device. The salinity gradient energy utilization interface unit further includes a load, a waste liquid storage tank, and a waste liquid pump. The load is connected to the reverse electrodialysis power generation device. The inlet of the waste liquid storage tank is connected to the waste liquid outlet of the reverse electrodialysis power generation device. The outlet of the waste liquid storage tank is connected to the waste liquid pump. The waste liquid pump is connected to the inlet of the solar distiller.

[0015] Preferably, the seawater supply unit includes a seawater storage tank, the outlet of which is connected to the inlet of a seawater pump, the outlet of which is connected to the inlet of a solar distiller, and the outlet of which is also connected to the freshwater inlet of a reverse electrodialysis power generation device.

[0016] Compared with the prior art, the beneficial effect of the present invention is that it couples gas turbine heat pump, solar still seawater desalination and reverse electrodialysis power generation technology to achieve multi-heat source zoned heating operation.

[0017] By using a zoned heating method that combines waste heat from the gas turbine with heat pump condensers, the high-temperature fluctuating waste heat and stable, controllable heat sources are applied to different distillation zones respectively, avoiding the efficiency reduction caused by direct superposition of heat sources and improving the stability of the distillation process and the water production per unit area.

[0018] By fully recovering the waste heat from the flue gas and cylinder liner water of the gas turbine system, and combining it with the solar energy utilization of the solar distiller, the system energy consumption is reduced and the efficiency of primary energy utilization is improved.

[0019] It boasts high operational stability, with a gas turbine heat pump assisting the operation of the solar distiller, compensating for the limitations of solar energy due to weather conditions and ensuring the continuity of seawater desalination.

[0020] The system can be selectively configured with salinity gradient energy utilization units, which can be used for energy recovery when needed, and can still operate the seawater desalination process independently and stably when power generation is not required, thereby improving the system's operational flexibility.

[0021] The RED system achieves continuous power generation through a stable source of concentrated and distilled freshwater (seawater and distilled freshwater); it makes comprehensive use of resources, simultaneously realizing freshwater production and salinity gradient power generation, which has significant economic and environmental benefits and meets the dual needs of freshwater resource shortage and energy recovery and utilization. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of a solar distillation seawater desalination system with multi-heat source zoned heating according to the present invention.

[0024] In the diagram, 1. Compressor; 2. Condenser; 3. Throttling valve; 4. Evaporator; 5. Gas engine; 6. Cylinder liner water heat exchanger; 7. Flue gas heat exchanger; 8. Heat exchanger; 9. Hot water storage tank; 10. Cooling water pump; 11. Solar still; 12. Freshwater pipeline; 13. Freshwater storage tank; 14. Distillate storage tank; 15. Distillate pump; 16. Reverse electrodialysis unit; 17. Load; 18. Waste liquid storage tank; 19. Waste liquid pump; 20. Seawater storage tank; 21. Seawater pump. Detailed Implementation

[0025] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0026] In the description of this application, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0027] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0028] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0029] like Figure 1As shown, this invention provides a solar distillation seawater desalination system with multi-heat source zoned heating. This invention integrates gas turbine heat pump, solar still seawater desalination and reverse electrodialysis power generation technology to realize energy cascade utilization and electricity recovery during the seawater desalination process, improve the system's energy utilization efficiency and operational stability, and achieve synergistic benefits of freshwater production and salinity gradient power generation.

[0030] Specifically, the present invention includes: The gas engine heat pump unit includes a compressor 1, a condenser 2, an evaporator 4, and a gas engine 5. The compressor 1, condenser 2, and evaporator 4 are interconnected, and the gas engine 5 is connected to the compressor 1.

[0031] Specifically, the basic structure of the gas engine heat pump unit is constructed so that it can use the gas engine 5 to drive the compressor 1 and achieve heat transfer and recovery through the circulation of refrigerant between the compressor 1, condenser 2 and evaporator 4, thereby providing stable thermal energy support for the subsequent solar distillation process.

[0032] Specifically, the gas engine heat pump unit consists of a compressor 1, a condenser 2, an evaporator 4, and a gas engine 5. The compressor 1, condenser 2, and evaporator 4 are connected sequentially to form a closed refrigerant circulation loop. The gas engine 5 is mechanically connected to the compressor 1 to drive its operation. During operation, the gas engine 5 burns fuel to generate power, which drives the compressor 1 to compress the refrigerant. The high-temperature, high-pressure refrigerant then enters the condenser 2 to release heat, and after throttling and depressurization, it enters the evaporator 4 to absorb heat, completing one heat pump cycle. This unit not only efficiently recovers the waste heat generated during the operation of the gas engine 5 but also actively improves the heat energy grade, providing an auxiliary heat source for seawater heating in the solar distillation unit, thereby improving the overall system's energy utilization efficiency and freshwater production stability.

[0033] The solar distillation unit includes a solar still 11, a freshwater pipe 12, a freshwater storage tank 13, a distillate storage tank 14, and a heat exchanger 8. The solar still 11 is connected to the evaporator 4. The freshwater pipe 12 is located in the middle of the solar still 11. The freshwater storage tank 13 is connected to the freshwater pipe 12. The heat exchanger 8 is located at the bottom of the solar still 11 and is used to heat and evaporate the seawater in the solar still 11. The distillate storage tank 14 is connected to the solar still 11.

[0034] Understandably, the basic structure of the solar distillation unit enables it to use solar energy and external heat sources to evaporate and condense seawater, achieving the separation and collection of freshwater. At the same time, it effectively extracts the concentrated brine (distillate) after distillation, providing a high-concentration salt solution for subsequent salinity gradient power generation.

[0035] Specifically, the solar distillation unit includes a solar still 11, a freshwater pipeline 12, a freshwater storage tank 13, a distillate storage tank 14, and a heat exchanger 8. The solar still 11 serves as the core evaporation and condensation chamber, containing the seawater to be treated. The freshwater pipeline 12, located in the middle of the solar still 11, collects the condensed freshwater formed on the condensation surface of the still lid during distillation and directs it to the freshwater storage tank 13 for storage. The heat exchanger 8, installed at the bottom of the solar still 11, uses heat from a heat pump to supplement the heating of the seawater inside the still, promoting the evaporation process and ensuring stable system operation, especially when sunlight is insufficient. After distillation, the remaining high-concentration brine (i.e., distillate) is discharged from the solar still 11 and temporarily stored in the distillate storage tank 14 for subsequent transport to the reverse electrodialysis unit for salinity gradient power generation. This structure achieves synergistic utilization of solar energy and heat pump waste heat, improving desalination efficiency and the overall energy utilization level of the system.

[0036] The waste heat recovery and lower heating unit is used to introduce the waste heat from the cylinder liner water and / or flue gas generated during the operation of the gas engine 5 into the lower distillation area of ​​the solar still 11 to preheat the seawater entering the solar still 11. The upper heating unit of the condenser, the condenser 2 is configured to exchange heat with the middle or upper distillation area of ​​the solar distiller 11, and is used to stably heat the water near the evaporation interface. The salinity gradient energy utilization interface unit is connected to the distillate storage tank 14 and the seawater supply unit, and is used to connect to the salinity gradient energy utilization device when energy recovery is required. Among them, the waste heat recovery and lower heating unit and the upper heating unit of the condenser act on different distillation functional areas of the solar still. The lower distillation area is used for seawater preheating, and the upper distillation area is used for heating the evaporation interface.

[0037] Through the above technical solution, different heat sources act on different areas of the still according to their temperature characteristics and stability, realizing zoned heating and synergistic effect, thereby improving distillation efficiency and enhancing system operation stability.

[0038] In this embodiment, the condenser is arranged to exchange heat with the middle or upper water area of ​​the solar distiller, so that the heat released by the condenser directly acts on the vicinity of the evaporation interface, thereby maintaining the stability of the temperature in the evaporation zone.

[0039] In this embodiment, the above arrangement allows the waste heat at the bottom to generate natural convection driving force, while the heat from the upper condenser directly enhances the evaporation process. The synergistic effect of the two significantly improves distillation efficiency and reduces the risk of scaling.

[0040] In some embodiments of this application, the gas engine heat pump unit further includes a throttle valve 3; the condenser 2 includes a condensing refrigerant pipe, and the evaporator 4 includes an evaporating refrigerant pipe; the compressor 1 outlet is connected to the condensing refrigerant pipe inlet, the condensing refrigerant pipe outlet is connected to the evaporating refrigerant pipe inlet, the evaporating refrigerant pipe outlet is connected to the compressor 1, and the throttle valve 3 is disposed between the condensing refrigerant pipe and the evaporating refrigerant pipe.

[0041] It is understandable that by improving the refrigerant circulation loop structure of the gas engine heat pump unit, by setting the throttling valve 3, and by clarifying the internal structure and connection relationship of the condenser 2 and the evaporator 4, the refrigerant can efficiently complete the four processes of compression, condensation, throttling and evaporation in the system according to the heat pump working principle, thereby stably providing heat energy for seawater heating.

[0042] Specifically, the gas turbine heat pump unit adds a throttling valve 3 to the original design and refines the structure of the condenser 2 and evaporator 4. The condenser 2 consists of several condensing refrigerant pipes, and the evaporator 4 consists of several evaporating refrigerant pipes. The high-temperature, high-pressure gaseous refrigerant discharged from the compressor 1 outlet enters the condensing refrigerant pipe (located in the lower distillation area of ​​the solar still), where it condenses into a high-pressure liquid state through heat exchange with an external cooling medium (such as cooling water). Subsequently, this high-pressure liquid refrigerant is throttled and depressurized by the throttling valve 3, becoming a low-temperature, low-pressure gas-liquid two-phase state, and enters the evaporating refrigerant pipe (located in the upper distillation area of ​​the solar still). In the upper distillation area of ​​the solar still, the refrigerant absorbs heat from the solar still 11 or the environment and evaporates into a low-temperature, low-pressure gas, returning to the compressor 1 inlet to complete a full heat pump cycle. The throttling valve 3, located between the condensing refrigerant pipe outlet and the evaporating refrigerant pipe inlet, controls the refrigerant flow and achieves a rapid pressure drop, making it a key component for maintaining the normal operation of the heat pump cycle. This structure ensures that the heat pump system can continuously and controllably provide the required heat energy to the solar distillation unit.

[0043] In some embodiments of this application, the waste heat recovery and lower heating unit includes a cylinder liner water heat exchanger 6 and a flue gas heat exchanger 7. The cylinder liner water heat exchanger 6 includes an inner cylinder liner and an outer cylinder liner, and the flue gas heat exchanger 7 includes a flue gas duct and a flue gas heat exchange shell. The waste heat outlet of the gas engine 5 is connected to the inlet of the inner cylinder liner, the inlet of the outer cylinder liner is connected to the outlet of the heat exchange water storage tank 9, and the outlet of the outer cylinder liner is connected to the inlet of the flue gas heat exchange shell. The outlet of the flue gas heat exchange shell is connected to the heat exchanger 8. The flue gas outlet of the gas engine 5 is connected to the inlet of the flue gas duct, and the outlet of the flue gas duct is connected to the outside.

[0044] It is understandable that by recovering the waste heat from the cylinder liner cooling water and the waste heat from the high-temperature flue gas generated during the operation of the gas engine 5, and then systematically integrating these two waste heats and sending them to the heat exchanger 8 of the solar distillation unit for auxiliary heating of seawater, the overall energy utilization efficiency of the entire system can be improved.

[0045] Specifically, the gas engine heat pump unit is equipped with a cylinder liner water heat exchanger 6 and a flue gas heat exchanger 7. The cylinder liner water heat exchanger 6 consists of an inner cylinder liner and an outer cylinder liner. The inner cylinder liner circulates the cooling water from the gas engine 5, while the outer cylinder liner circulates the cooling water from the heat exchange water storage tank 9. The waste heat outlet of the gas engine 5 (i.e., the cylinder liner water outlet) is connected to the inlet of the inner cylinder liner, allowing the high-temperature cylinder liner water to enter the inner cylinder liner and release heat. This heat is transferred to the cooling water in the outer cylinder liner through the wall. This cooling water is drawn from the outlet of the heat exchange water storage tank 9, first entering the outer cylinder liner for preheating, and then flowing from the outer cylinder liner outlet into the flue gas heat exchange shell. The flue gas heat exchanger 7 consists of a flue gas duct and a flue gas heat exchange shell surrounding the duct. The high-temperature flue gas discharged from the gas engine 5 flows through the flue gas duct into the flue gas heat exchanger 7, transferring heat to the water flow within the flue gas heat exchange shell. The cooling water, preheated by the cylinder liner water heat exchanger 6, further absorbs waste heat from the flue gas in the flue gas heat exchange shell. The heated hot water is then transported from the outlet of the flue gas heat exchange shell to the heat exchanger 8 at the bottom of the solar distiller 11, where it is used to heat seawater and promote evaporation. After heat exchange, the flue gas is discharged to the outside through the flue gas duct outlet. This structure achieves the cascade recovery and synergistic utilization of the two main types of waste heat (cylinder liner water and flue gas) from the gas turbine engine 5, significantly improving the overall thermal efficiency of the system.

[0046] In some embodiments of this application, the evaporative refrigerant pipe is disposed within the solar distiller 11 and is located above the freshwater pipe 12.

[0047] In some embodiments of this application, the solar distillation unit further includes a hot water storage tank 9 and a cooling water pump 10. The outlet of the heat exchanger 8 is connected to the inlet of the hot water storage tank 9, the outlet of the hot water storage tank 9 is connected to the inlet of the cooling water pump 10, and the outlet of the cooling water pump 10 is connected to the inlet of the outer cylinder liner.

[0048] It is understandable that by optimizing the heat exchange layout inside the solar still 11 and establishing a cooling water circulation loop, the heat pump system and the distillation process can achieve efficient thermal coupling, while ensuring that the condenser 2 obtains a stable cooling water source to maintain the normal operation of the heat pump circulation.

[0049] Specifically, the evaporative refrigerant pipeline is located inside the solar distiller 11, above the freshwater pipeline 12. At this location, the low-temperature, low-pressure refrigerant absorbs heat and evaporates in the evaporative refrigerant pipeline, effectively condensing the rising water vapor inside the distiller and improving the freshwater condensation efficiency. Simultaneously, because it is located above the freshwater collection area, it prevents condensate dripping from interfering with the refrigerant pipeline and facilitates the smooth collection of freshwater into the central freshwater pipeline 12. Furthermore, the solar distillation unit is equipped with a hot water storage tank 9 and a cooling water pump 10, forming a cooling water circulation system: after the heat exchanger 8 heats seawater at the bottom of the distiller, the cooling water (i.e., the hot water that has released heat) flows out of the heat exchanger 8 outlet into the hot water storage tank 9 for temporary storage; subsequently, this water is pressurized and pumped by the cooling water pump 10, returning to the inlet of the outer cylinder liner to complete the cooling task before returning to the heat exchanger 8, forming a closed or semi-closed cycle. This design not only ensures the cooling needs of the condenser 2 but also achieves the orderly transfer and reuse of heat within the system, improving overall energy efficiency and operational stability.

[0050] In some embodiments of this application, the concentrated solution outlet of the solar distiller 11 is connected to the distillate storage tank 14, and the distillate storage tank 14 is connected to the concentrated solution inlet of the reverse electrodialysis assembly 16 via the distillate pump 15.

[0051] Understandably, by establishing a high-concentration brine transport path from the solar distiller 11 to the reverse electrodialysis unit 16, it is ensured that the concentrated brine (distillate) generated during the distillation process can be effectively collected and stably supplied to the reverse electrodialysis unit as a source of concentrated solution required for salinity gradient power generation.

[0052] Specifically, during the seawater evaporation and desalination process in the solar distiller 11, water is vaporized and condensed into fresh water, while the remaining salt gradually accumulates to form a high-concentration brine solution (i.e., a concentrated solution). This concentrated solution is discharged through a concentrated solution outlet located at the bottom or side of the solar distiller 11 and directly connected to a distillate storage tank 14 for temporary storage. The outlet of the distillate storage tank 14 is connected to the concentrated solution inlet of the reverse electrodialysis assembly 16 via a distillate pump 15. The distillate pump 15 provides the power to pressurize and pump the stored high-concentration brine into one side of the flow channel of the reverse electrodialysis assembly 16, forming a salinity gradient with the dilute solution (such as the original seawater or fresh water) on the other side, thereby driving ion selective migration and generating electricity. This structure realizes the resource utilization of desalination byproducts and concentrated brine, providing the necessary conditions for salinity gradient power generation, while avoiding the direct discharge of concentrated brine, thus improving the overall resource recycling efficiency and energy output capacity of the system.

[0053] In some embodiments of this application, the salinity gradient energy utilization interface unit is connected to a reverse electrodialysis power generation device 16. The salinity gradient energy utilization interface unit also includes a load 17, a waste liquid storage tank 18, and a waste liquid pump 19. The load 17 is connected to the reverse electrodialysis power generation device 16, the inlet of the waste liquid storage tank is connected to the waste liquid outlet of the reverse electrodialysis power generation device 16, the outlet of the waste liquid storage tank 18 is connected to the waste liquid pump 19, and the waste liquid pump 19 is connected to the inlet of the solar distiller 11.

[0054] In this embodiment, the system also includes a salinity gradient energy utilization unit, which is preferably a reverse electrodialysis power generation unit. The salinity gradient energy utilization unit is connected to the distillate storage tank and the seawater supply unit when electricity recovery is required, and can be disconnected from the system without affecting the continuous operation of the seawater desalination process when power generation is not required.

[0055] It is understandable that the reverse electrodialysis power generation device 16 can utilize the salinity difference between the high-concentration brine (distillate) generated during the solar distillation process and the diluted seawater to generate electricity, and collect the waste liquid after power generation, thereby realizing the effective recovery and utilization of salinity gradient energy.

[0056] Specifically, the salinity gradient energy utilization interface unit also includes a load 17, a waste liquid storage tank 18, and a waste liquid pump 19. The reverse electrodialysis power generation device 16 is an electrochemical device composed of alternating cation exchange membranes and anion exchange membranes. Its concentrated solution inlet is connected to the distillate storage tank 14, allowing the introduction of high-concentration brine concentrated by solar distillation. Simultaneously, the dilute solution inlet of the reverse electrodialysis power generation device 16 receives low-concentration seawater (or freshwater) from the seawater storage tank 20. The two components form a salt concentration gradient across the membrane stack, driving ion migration and generating current in the external circuit, which can be supplied to the load 17. After power generation, the waste liquid formed by the mixture of concentrated brine and diluted seawater is discharged from the reverse electrodialysis component 16 and introduced into the waste liquid storage tank 18 for temporary storage or further treatment. This structure realizes the energy utilization of desalination byproducts and high-concentration brine, improving the energy output efficiency and resource utilization level of the entire system.

[0057] It is understandable that by setting up waste liquid pump 19 to send the low-grade brine after power generation back to solar distiller 11 as part of the feed seawater, the comprehensive utilization efficiency of water resources and salt can be improved, and the system's dependence on external water sources and waste liquid discharge can be reduced.

[0058] Specifically, in the salinity gradient power generation process of the reverse electrodialysis unit, concentrated and dilute solutions are mixed after reaction in an ion exchange membrane stack to form waste liquid with a salt concentration between the two. This waste liquid is collected in waste liquid storage tank 18. To avoid resource waste caused by direct discharge, a waste liquid pump 19 is added to the system. Its inlet is connected to the outlet of the waste liquid storage tank 18, and its outlet is connected to the inlet of the solar still 11. During operation, the waste liquid pump 19 pressurizes and transports the waste liquid back to the solar still 11 as part of the feed liquid for the distillation process. Since the waste liquid still contains a certain amount of salt and residual heat, its reuse can reduce the consumption of fresh seawater and continue to participate in heat and mass transfer during the distillation process, improving the overall water, heat, and salt synergistic utilization level of the system. This design strengthens the internal material circulation of the system and enhances the sustainability and economy of operation.

[0059] In some embodiments of this application, the seawater supply unit includes a seawater storage tank 20, the outlet of which is connected to the inlet of a seawater pump 21, the outlet of which is connected to the inlet of a solar distiller 11, and the outlet of which is also connected to the freshwater inlet of a reverse electrodialysis power generation device 16.

[0060] It is understandable that by establishing a unified seawater supply path, a single seawater pump 21 can simultaneously supply raw seawater to the solar distiller 11 and the reverse electrodialysis unit 16, thus satisfying the feed requirements of the distillation unit and providing the reverse electrodialysis unit with the dilute solution (i.e., low-concentration side fluid) required for salinity gradient power generation, thereby simplifying the system piping structure and improving seawater utilization efficiency.

[0061] Specifically, the seawater storage tank 20 stores the raw seawater to be treated, and its outlet is connected to the inlet of the seawater pump 21. During operation, the seawater pump 21 pressurizes and delivers the raw seawater, with its outlet divided into two paths: one path connects to the inlet of the solar distiller 11, serving as the raw material for distillation and desalination; the other path connects to the freshwater inlet (actually the dilute solution inlet) of the reverse electrodialysis unit 16, serving as the low-concentration side fluid that forms a salinity gradient with the high-concentration distillate during salinity gradient power generation. Since the salt concentration of the raw seawater is much lower than that of the distillation concentrate, it effectively drives ion migration during the reverse electrodialysis process, generating electricity. This design, by sharing the seawater pump 21 and the seawater source, avoids the need for an additional independent water supply system, reducing equipment complexity and energy consumption, while ensuring a stable and synchronized seawater supply for both functional units, enhancing system integration and operational coordination.

[0062] In this application, seawater is supplied by a seawater storage tank 20 and pumped in by a seawater pump 21, then split into two streams. One stream flows into the system via valve v7 as the raw water for seawater desalination, while the other stream flows into the reverse electrodialysis unit via valve v6. Water vapor generated by solar thermal and waste heat is partially cooled by a cover plate and flows into the freshwater pipe 12. The remaining portion is cooled by the heat exchange in the evaporator 4, thus cooling the surrounding environment and forming freshwater that flows into the freshwater pipe 12. Finally, the two pipes merge and flow naturally into the freshwater storage tank 13 under gravity. In the gas turbine heat pump unit, the refrigerant passes sequentially through the compressor 1, condenser 2, expansion valve 3, and evaporator 4.

[0063] In this system, a large amount of waste heat is released and absorbed sequentially by cooling water. The process is as follows: the cooling water first passes through condenser 2 to absorb the released heat, achieving a first temperature increase; then it passes through cylinder liner water heat exchanger 6 to absorb the waste heat generated by the combustion of gas engine 5, achieving a second temperature increase; then it passes through flue gas heat exchanger 7 to absorb the waste heat generated by the flue gas during combustion of gas engine 5, achieving a third temperature increase; finally, carrying a large amount of waste heat, it passes through heat exchanger 8 at the bottom of solar still 11 to release heat and raise the temperature of seawater, accelerating seawater evaporation and increasing freshwater yield. The water after heat exchange is fed into hot water storage tank 9 for the next cycle. The reverse electrodialysis power generation device 16 generates electricity using concentration difference as power. Its concentrated solution is the concentrate remaining after the solar still 11 evaporates seawater, supplied by distillate storage tank 14 and distillate pump 15, while the dilute solution is supplied by seawater storage tank 20 and seawater pump 21. The electrical energy generated by the concentration difference is stored or utilized by load 17. The waste liquid generated after power generation can be directly discharged, stored in a storage tank, or recycled back into the solar distiller 11. Furthermore, the system uses multiple valves (v1-v8) to control the flow and on / off status of each branch, ensuring coordinated operation of all system components. In this embodiment, the inlets of the multiple storage tanks are located in the upper half, and the outlets are located in the lower half. Both the freshwater storage tank and the distillate storage tank are lower than the solar distiller, better reflecting the liquid's gravity flow to the tanks.

[0064] 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, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A solar-powered seawater desalination system with multi-heat source zoned heating, characterized in that, include: A gas engine heat pump unit includes a compressor, a condenser, an evaporator, and a gas engine, wherein the compressor, condenser, and evaporator are interconnected, and the gas engine is connected to the compressor; The solar distillation unit includes a solar distiller, freshwater pipelines, a freshwater storage tank, and a distillate storage tank. The waste heat recovery and lower heating unit is used to introduce the waste heat from the cylinder liner water and / or the waste heat from the flue gas generated during the operation of the gas engine into the lower distillation area of ​​the solar still to preheat the seawater entering the solar still. The upper heating unit of the condenser is configured to exchange heat with the middle or upper distillation area of ​​the solar still, and is used to stably heat the water near the evaporation interface. The salinity gradient energy utilization interface unit is connected to the distillate storage tank and the seawater supply unit, and is used to connect to the salinity gradient energy utilization device when energy recovery is required. The waste heat recovery and lower heating unit and the upper heating unit of the condenser respectively act on different distillation zones of the solar still. The lower distillation zone is used for seawater preheating, and the upper distillation zone is used for heating the evaporation interface.

2. The solar distillation seawater desalination system with multi-heat source zoned heating according to claim 1, characterized in that, The gas engine heat pump unit also includes a throttling valve; the condenser includes a condenser refrigerant pipe, and the evaporator includes an evaporator refrigerant pipe. The compressor outlet is connected to the condensing refrigerant pipeline inlet, the condensing refrigerant pipeline outlet is connected to the evaporating refrigerant pipeline inlet, the evaporating refrigerant pipeline outlet is connected to the compressor, and the throttle valve is located between the condensing refrigerant pipeline and the evaporating refrigerant pipeline.

3. The solar distillation seawater desalination system with multi-heat source zoned heating according to claim 2, characterized in that, The waste heat recovery and lower heating unit includes a cylinder liner water heat exchanger and a flue gas heat exchanger. The heat exchange outlets of the cylinder liner water heat exchanger and the flue gas heat exchanger are connected to the lower distillation area of ​​the solar still. The cylinder liner water heat exchanger includes an inner cylinder liner and an outer cylinder liner. The flue gas heat exchanger includes a flue gas pipe and a flue gas heat exchange shell. The heat exchange outlet of the gas engine is connected to the inner cylinder liner inlet, the outer cylinder liner inlet is connected to the outlet of the heat exchange water storage tank, the outer cylinder liner outlet is connected to the flue gas heat exchange shell inlet, and the flue gas heat exchange shell outlet is connected to the heat exchanger. The exhaust gas outlet of the gas engine is connected to the exhaust gas duct inlet, and the exhaust gas duct outlet is connected to the outside.

4. The solar distillation seawater desalination system with multi-heat source zoned heating according to claim 3, characterized in that, The evaporative refrigerant pipe is located inside the solar distiller and above the freshwater pipe; the condenser is configured to exchange heat with the upper water body region of the solar distiller, which is located at the evaporation interface of the solar distiller.

5. The solar distillation seawater desalination system with multi-heat source zoned heating according to claim 4, characterized in that, The solar still is connected to the evaporator. The freshwater pipe is located in the middle of the solar still. The freshwater storage tank is connected to the freshwater pipe. The heat exchanger is located at the bottom of the solar still and is used to heat and evaporate the seawater in the solar still. The distillate storage tank is connected to the solar still.

6. The solar distillation seawater desalination system with multi-heat source zoned heating according to claim 5, characterized in that, The solar distillation unit includes a heat exchanger storage tank and a cooling water pump. The heat exchanger outlet is connected to the heat exchanger storage tank inlet, the heat exchanger storage tank outlet is connected to the cooling water pump inlet, and the cooling water pump outlet is connected to the outer cylinder liner inlet.

7. The solar distillation seawater desalination system with multi-heat source zoned heating according to claim 6, characterized in that, The concentrated solution outlet of the solar still is connected to the distillate storage tank, and the distillate storage tank is connected to the concentrated solution inlet of the salinity gradient energy utilization interface unit via a distillate pump.

8. The solar distillation seawater desalination system with multi-heat source zoned heating according to claim 7, characterized in that, The salinity gradient energy utilization interface unit is connected to a reverse electrodialysis power generation device. The salinity gradient energy utilization interface unit also includes a load, a waste liquid storage tank, and a waste liquid pump. The load is connected to the reverse electrodialysis power generation device. The inlet of the waste liquid storage tank is connected to the waste liquid outlet of the reverse electrodialysis power generation device. The outlet of the waste liquid storage tank is connected to the waste liquid pump. The waste liquid pump is connected to the inlet of the solar distiller.

9. The solar distillation seawater desalination system with multi-heat source zoned heating according to claim 8, characterized in that, The seawater supply unit includes a seawater storage tank, the outlet of which is connected to the inlet of a seawater pump, the outlet of which is connected to the inlet of a solar distiller, and the outlet of which is also connected to the freshwater inlet of a reverse electrodialysis power generation device.

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