Thermoelectric power generation system and method for near-island and reef islands

Abstract

This invention discloses a thermoelectric power generation system and method for near-island reefs, relating to the field of seawater power generation technology. It includes a hot water circulation pipe assembly, a cold water circulation pipe assembly, and a working fluid circulation pipe assembly. The working fluid circulation pipe assembly includes a hot-end heat exchanger, a storage tank, a cold-end heat exchanger, and a turbine. One end of the hot water circulation pipe assembly extends into the surface seawater, and its middle section connects to the hot-end heat exchanger, used to vaporize the working fluid transported from the storage tank to drive the turbine for power generation. The other end of the hot water circulation pipe assembly extends into the seawater. One end of the cold water circulation pipe assembly enters deep seawater through a borehole drilled on the near-island reef, and its middle section connects to the cold-end heat exchanger, used to liquefy the working fluid discharged from the turbine to flow back into the storage tank. The other end of the cold water circulation pipe assembly extends into the seawater. Compared to floating offshore thermoelectric power generation devices, this invention is easier to maintain and has lower costs, while also offering higher safety and stability.

Description

Technical Field

[0001] This invention relates to the field of seawater power generation technology, specifically to a thermoelectric power generation system and method for near-island and reef areas. Background Technology

[0002] Ocean thermal energy conversion (OTEC): A significant temperature difference exists between the surface and deep seawater. Surface seawater absorbs solar radiation, converting most of the solar energy into seawater heat energy, which is stored at a higher temperature. The average annual surface water temperature in the central South my country Sea reaches 25-26°C, while the temperature of seawater deeper than 700 meters is below 4°C, creating a vertical temperature difference of over 20°C throughout the year. This temperature difference between the surface and deep seawater leads to heat transfer, a process known as ocean thermal energy conversion (OTEC). It exists in the form of heat energy and is one form of ocean energy. Utilizing this temperature difference can enable a thermodynamic cycle and generate electricity, a process called ocean thermal energy conversion (OTEC).

[0003] There are two main types of existing ocean thermal energy conversion (OTEC) power generation methods: one is offshore platform and the other is island / reef shore-based. Existing technologies have the following drawbacks: (1) Offshore platforms are expensive and require mooring, making construction complex; (2) Island / reef shore-based OTEC power generation systems float on the sea to generate electricity. Various sensors, pumps, pipelines, and working fluids are immersed in the sea for a long time. Seawater is highly corrosive, resulting in high long-term system maintenance and power transmission costs. The power generation system is mainly used while floating at sea, making it difficult to handle emergencies such as working fluid leakage or motor malfunction; (3) Cold water pipes need to be lowered to a depth of 700m or more above the sea surface. The cold water pipes float in the sea for a long time, which greatly challenges their bending, tensile, and fatigue strength. Furthermore, as the power generation capacity increases, the diameter of the cold water pipes also increases, posing a severe challenge to the cold water pipes. Summary of the Invention

[0004] The purpose of this invention is to provide a thermoelectric power generation system and method for near-island and reef areas, in order to solve the problems existing in the prior art. Compared with floating thermoelectric power generation devices at sea, it is easier to maintain and has lower cost, while also being safer and more stable.

[0005] To achieve the above objectives, the present invention provides the following solution:

[0006] This invention provides a thermoelectric power generation system for near-island reefs, comprising a hot water circulation pipe assembly, a cold water circulation pipe assembly, and a working fluid circulation pipe assembly. The working fluid circulation pipe assembly includes a hot-end heat exchanger, a storage tank, a cold-end heat exchanger, and a turbine. One end of the hot water circulation pipe assembly extends into the surface seawater, and the middle part of the hot water circulation pipe assembly is connected to the hot-end heat exchanger and is used to vaporize the working fluid transported from the storage tank to drive the turbine to generate electricity. The other end of the hot water circulation pipe assembly extends into the seawater. One end of the cold water circulation pipe assembly enters the deep seawater through a borehole drilled on the near-island reef. The middle part of the cold water circulation pipe assembly is connected to the cold-end heat exchanger and is used to liquefy the working fluid discharged from the turbine to flow back into the storage tank. The other end of the cold water circulation pipe assembly extends into the seawater.

[0007] Preferably, the hot water circulation pipe assembly includes a hot water intake pipe, a hot water filter, a buoyancy element, a hot water pump, and a hot water drain pipe. One end of the hot water intake pipe is fitted with the hot water filter and extends into the surface seawater. The other end of the hot water intake pipe is connected to the inlet of the hot water pump. The outlet of the hot water pump is connected to the inlet of the hot-end heat exchanger. The buoyancy element is located in the middle of the hot water intake pipe. One end of the hot water drain pipe is connected to the outlet of the hot-end heat exchanger, and the other end of the hot water drain pipe extends into the seawater.

[0008] Preferably, the buoyancy element includes a plurality of floats arranged along the length of the hot water intake pipe.

[0009] Preferably, the buoyancy element is bolted to the hot water suction pipe, the hot water filter is connected to one end of the hot water suction pipe via a flange, the other end of the hot water suction pipe is connected to the inlet of the hot water pump via a flange, the outlet flange of the hot water pump is connected to the inlet flange of the hot end heat exchanger via a stainless steel pipe, and the outlet flange of the hot end heat exchanger is connected to one end of the hot water drain pipe via a stainless steel pipe.

[0010] Preferably, the cold water circulation pipe assembly includes a cold water tank, a cold water drain pipe, a built-in cold water pump, and several cold water suction elements. One end of each cold water suction element extends into deep seawater, and the other end of each cold water suction element is connected to the inlet of the cold water tank. The outlet of the cold water tank is connected to the inlet of the built-in cold water pump, and the outlet of the built-in cold water pump is connected to one end of the cold water drain pipe, the other end of which extends into seawater.

[0011] Preferably, the cold water circulation pipe assembly further includes several shut-off valves and several external cold water pumps. The cold water suction element includes a cold water suction pipe and a cold water filter. One end of the cold water suction pipe is equipped with the cold water filter and extends into deep seawater. The other end of each cold water suction pipe is connected to one end of a main pipe. The other end of the main pipe is connected to the inlet of the external cold water pump. The outlet of the external cold water pump is connected to the inlet of the cold water tank. The shut-off valves are installed on each cold water suction pipe or the main pipe. The cold water suction pipe includes multiple sleeves that are connected sequentially in the length direction.

[0012] Preferably, adjacent sleeves are connected by threads. The lowermost sleeve is connected to the cold water filter by threads, and the uppermost sleeve is connected to the inlet flange of the shut-off valve by a flange and an elbow flange. The outlet flange of the shut-off valve is connected to the inlet flange of the external cold water pump. The outlet flange of the external cold water pump is connected to the inlet flange of the cold water tank. The outlet flange of the cold water tank is connected to the inlet flange of the cold end heat exchanger by a stainless steel pipe. The outlet flange of the cold end heat exchanger is connected to one end of the cold water drain pipe by a stainless steel pipe.

[0013] Preferably, the working fluid circulation pipeline further includes a working fluid pump and a gas-liquid separator. The working fluid outlet of the hot-end heat exchanger is connected to the working fluid inlet of the gas-liquid separator. The working fluid outlet of the gas-liquid separator is connected to the working fluid inlet of the turbine. The working fluid outlet of the turbine is connected to the working fluid inlet of the cold-end heat exchanger. The working fluid outlet of the cold-end heat exchanger is connected to the working fluid inlet of the liquid storage tank. The working fluid outlet of the liquid storage tank is connected to the working fluid inlet of the working fluid pump. The working fluid outlet of the working fluid pump is connected to the working fluid inlet of the hot-end heat exchanger.

[0014] Preferably, it also includes an equipment container, and the working fluid circulation pipe assembly is located inside the equipment container.

[0015] The present invention also provides a method for generating electricity from near-island reefs using thermoelectric energy conversion, and the near-island reef thermoelectric energy conversion system using any of the above technical solutions includes the following steps:

[0016] S1. Calculate the power generation capacity based on the total power generation and power generation efficiency, and then determine the parameters of the near-island and reef thermal energy power generation system based on the actual sea surface temperature.

[0017] S2, Use a drilling rig to complete directional drilling, drill to the target depth, connect with seawater, and then lower a cold water suction pipe to complete the assembly of the near-island reef thermoelectric power generation system;

[0018] S3, Perform pressure and vacuum tests on the near-island reef thermoelectric power generation system to ensure that there are no leaks in the connection;

[0019] S4, put one end of the hot water circulation pipe assembly and one end of the cold water circulation pipe assembly into seawater;

[0020] S5, inject the working medium into the storage tank, and the liquid level of the working medium is located at 2 / 3 of the inside of the storage tank;

[0021] S6, deep seawater is extracted through the cold water circulation pipe group and circulated within the cold water circulation pipe group to reach the designed cold water temperature.

[0022] S7, draw surface seawater through the hot water circulation pipe group and circulate the surface seawater in the hot water circulation pipe group to reach the designed hot water temperature;

[0023] S8, the liquid working medium in the storage tank is injected into the hot end heat exchanger and exchanged with the surface seawater in the hot water circulation pipe group to vaporize the working medium and drive the turbine to rotate and generate electricity.

[0024] S9, the working gas after power generation enters the cold end heat exchanger and exchanges heat with the deep seawater in the cold water circulation pipe group, liquefying the working gas and flowing back into the storage tank.

[0025] The present invention achieves the following technical effects compared to the prior art:

[0026] The present invention provides a near-island reef-based ocean thermal energy conversion system and method. The working fluid circulation pipe assembly includes a hot-end heat exchanger, a storage tank, a cold-end heat exchanger, and a turbine. One end of the hot water circulation pipe assembly extends into the surface seawater, and the middle of the hot water circulation pipe assembly is connected to the hot-end heat exchanger, used to vaporize the working fluid transported from the storage tank to drive the turbine for power generation. The other end of the hot water circulation pipe assembly extends into the seawater. One end of the cold water circulation pipe assembly enters the deep seawater through a borehole drilled on the near-island reef, and the middle of the cold water circulation pipe assembly is connected to the cold-end heat exchanger, used to liquefy the working fluid discharged from the turbine to flow back into the storage tank. The other end of the cold water circulation pipe assembly extends into the seawater. Constructing the ocean thermal energy conversion system on near-island reefs avoids the high costs, high risks, and complex construction associated with offshore platform fixation, power transmission, and maintenance of various components. The hot water circulation pipe assembly is laid from the reef to the nearshore waters, while the cold water circulation pipe assembly is lowered through drilling on the reef, ensuring safety and stability. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the thermoelectric power generation system for near-island and reef applications provided in Embodiment 1;

[0029] Figure 2 This is a schematic diagram of the thermoelectric power generation system for near-island and reef applications provided in Embodiment 2;

[0030] Figure 3 This is a schematic diagram of the thermoelectric power generation system for near-island and reef applications provided in Embodiment 3;

[0031] Figure 4 These are schematic diagrams of the internal structure of the equipment container in Embodiments 1, 2, and 3;

[0032] In the diagram: 1-Seawater, 2-Hot water filter, 3-Hot water suction pipe, 4-Float, 5-Equipment container, 6-Cold water tank, 7-External cold water pump, 8-Stop valve, 9-Cold water suction pipe, 10-Near island / reef, 11-Casing, 12-Cold water filter, 13-Main pipe, 14-Built-in cold water pump, 15-Hot water pump, 16-Hot end heat exchanger, 17-Hot water drain pipe, 18-Cold water drain pipe, 19-Working fluid pump, 20-Storage tank, 21-Flange, 22-Cold end heat exchanger, 23-Gas-liquid separator, 24-Turbine. Detailed Implementation

[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] The purpose of this invention is to provide a near-island and reef-based ocean thermal energy conversion system and method to solve the technical problems of high construction cost, difficult maintenance, and poor safety and stability of existing ocean thermal energy conversion methods.

[0035] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] Example 1

[0037] like Figure 1 and Figure 4As shown, this embodiment provides a thermoelectric power generation system for near-island reefs, including a hot water circulation pipe assembly, a cold water circulation pipe assembly, and a working fluid circulation pipe assembly, which are used to provide hot water, cold water, and working fluid for thermoelectric power generation, respectively. The working fluid circulation pipe assembly includes a hot-end heat exchanger 16, a storage tank 20, a cold-end heat exchanger 22, and a turbine 24. One end of the hot water circulation pipe assembly extends into the surface seawater, and the middle part of the hot water circulation pipe assembly is connected to the hot-end heat exchanger 16, which is used to vaporize the working fluid transported from the storage tank 20 to drive the turbine 24 to generate electricity. The other end of the hot water circulation pipe assembly extends into the seawater 1. One end of the cold water circulation pipe assembly enters the deep seawater through a borehole completed on the near-island reef 10. The middle part of the cold water circulation pipe assembly is connected to the cold-end heat exchanger 22, which is used to liquefy the working fluid discharged from the turbine 24 to flow back into the storage tank 20. The other end of the cold water circulation pipe assembly extends into the seawater 1. By constructing the ocean thermal energy conversion system on the near-shore island 10, the high costs, high risks, and complex construction associated with offshore platform fixation, power transmission, and maintenance of various components are avoided. The hot water circulation pipe assembly is laid from the near-shore island 10 to the near sea, while the cold water circulation pipe assembly is lowered by drilling on the near-shore island 10, ensuring safety and stability.

[0038] Specifically, the hot water circulation pipe assembly includes a hot water intake pipe 3, a hot water filter 2, a buoyancy element, a hot water pump 15, and a hot water drain pipe 17. One end of the hot water intake pipe 3 is equipped with the hot water filter 2 and extends into the surface seawater to exchange heat with the working fluid using the higher temperature of the surface seawater and to vaporize the working fluid. The vaporized working fluid is then used to drive the turbine 24 to generate electricity. The hot water filter 2 can prevent plankton and garbage from entering the hot water pipe and causing blockage. The other end of the hot water pipe is connected to the inlet of the hot water pump 15, and the outlet of the hot water pump 15 is connected to the inlet of the hot end heat exchanger 16. The buoyancy element is located in the middle of the hot water intake pipe 3 to ensure that the hot water intake pipe 3 can float on the surface seawater. One end of the hot water drain pipe 17 is connected to the outlet of the hot end heat exchanger 16, and the other end of the hot water drain pipe 17 extends into the seawater 1.

[0039] The hot water pump 15 continuously pumps surface seawater from the sea surface to the hot end heat exchanger 16, vaporizes the working fluid in the hot end heat exchanger 16, and drives the turbine 24 to generate electricity. The temperature of the hot water after heat exchange decreases and it is returned to the sea. The hot water intake and drainage are continuously circulated, thereby meeting the hot water temperature required for thermoelectric power generation.

[0040] The buoyancy element includes multiple floats 4 arranged along the length of the hot water intake pipe 3.

[0041] The buoyancy element is bolted to the hot water suction pipe 3. The hot water filter 2 is connected to one end of the hot water suction pipe 3 via flange 21. The other end of the hot water suction pipe 3 is connected to the inlet of the hot water pump 15 via flange 21. The outlet flange 21 of the hot water pump 15 is connected to the inlet flange 21 of the hot end heat exchanger 16 via a stainless steel pipe. The outlet flange 21 of the hot end heat exchanger 16 is connected to one end of the hot water drain pipe 17 via a stainless steel pipe. Using the above connection method, the installation and disassembly of the hot water circulation pipe assembly can be facilitated, and maintenance is convenient.

[0042] The cold water circulation pipe assembly includes a cold water tank 6, a cold water drain pipe 18, a built-in cold water pump 14, and several cold water suction elements. One end of each cold water suction element extends into deep seawater to exchange heat with the working fluid using the lower temperature of the deep seawater and liquefy the working fluid. The liquefied working fluid is then stored and re-circulated into the hot-end heat exchanger 16 for vaporization. The other end of each cold water suction element is connected to the inlet of the cold water tank 6. The outlet of the cold water tank 6 is connected to the inlet of the built-in cold water pump 14. The outlet of the built-in cold water pump 14 is connected to one end of the cold water drain pipe 18, and the other end of the cold water drain pipe 18 extends into the seawater 1.

[0043] The cold water circulation pipe assembly also includes several shut-off valves 8 and several external cold water pumps 7. The cold water suction element includes a cold water suction pipe 9 and a cold water filter 12. One end of the cold water suction pipe 9 is equipped with a cold water filter 12 and extends into the deep seawater. The other end of each cold water suction pipe 9 is connected to one end of a main pipe 13. The other end of the main pipe 13 is connected to the inlet of the external cold water pump 7. The outlet of the external cold water pump 7 is connected to the inlet of the cold water tank 6. The shut-off valves 8 are installed on each cold water suction pipe 9 or the main pipe 13. In this embodiment, there is one cold water suction pipe 9, which includes multiple sleeves 11 connected sequentially in the length direction.

[0044] The most important part of the cold water circulation pipe assembly is the drilling process. A drilling rig is used to complete directional drilling in a certain location near the island reef 10, drilling to a water depth of more than 700m below the seabed. Then, the casing 11 is lowered into the well, and the drilling rig is withdrawn. The principle of communicating vessels is used to pressurize the deep seawater through the casing 11 to the wellhead. When generating electricity, the shut-off valve 8 is opened, and the external cold water pump 7 is used to pump the cold water in the casing 11 into the cold water tank 6. When there is a certain amount of cold water in the cold water tank 6, the internal external cold water pump 7 is turned on to pump the cold water in the cold water tank 6 into the cold end heat exchanger 22, liquefying the working fluid in the cold end heat exchanger 22, so that the working fluid returns to the liquid storage tank 20. The temperature of the cold water after heat exchange rises and returns to the sea. The cold water intake and drainage are continuously circulated, thereby meeting the cold water temperature required for thermoelectric power generation. In this process, deep seawater is pumped to the wellhead using the principle of communicating vessels, which facilitates the extraction of cold water, reduces the head required by the cold water pump, reduces the energy consumption of the system, and improves the power generation efficiency.

[0045] Adjacent sleeves 11 are connected by threads. The lowermost sleeve 11 is connected to the cold water filter 12 by threads. The uppermost sleeve 11 is connected to the inlet flange 21 of the shut-off valve 8 via flange 21 and elbow flange 21. The outlet flange 21 of the shut-off valve 8 is connected to the inlet flange 21 of the external cold water pump 7. The outlet flange 21 of the external cold water pump 7 is connected to the inlet flange 21 of the cold water tank 6. The outlet flange 21 of the cold water tank 6 is connected to the inlet flange 21 of the cold end heat exchanger 22 via a stainless steel pipe. The outlet flange 21 of the cold end heat exchanger 22 is connected to one end of the cold water drain pipe 18 via a stainless steel pipe. Using the above connection method facilitates the installation and disassembly of the cold water circulation pipe assembly and makes maintenance convenient.

[0046] The working fluid circulation pipeline also includes a working fluid pump 19 and a gas-liquid separator 23. The working fluid outlet of the hot-end heat exchanger 16 is connected to the working fluid inlet of the gas-liquid separator 23. The working fluid outlet of the gas-liquid separator 23 is connected to the working fluid inlet of the turbine 24. The working fluid outlet of the turbine 24 is connected to the working fluid inlet of the cold-end heat exchanger 22. The working fluid outlet of the cold-end heat exchanger 22 is connected to the working fluid inlet of the liquid storage tank 20. The working fluid outlet of the liquid storage tank 20 is connected to the working fluid inlet of the working fluid pump 19. The working fluid outlet of the working fluid pump 19 is connected to the working fluid inlet of the hot-end heat exchanger 16.

[0047] The storage tank 20 is mainly used to store the working fluid. The working fluid is pumped into the hot-end heat exchanger 16 by the working fluid pump 19. Under a specific pressure, the working fluid heats up by exchanging heat with hot water and vaporizes at a certain temperature. It then flows into the gas-liquid separator 23. The gas rises and enters the turbine 24, which is located at the highest point of the entire system. After entering, the gas drives the turbine 24 to rotate and generate electricity. The working fluid gas (exhaust gas) after power generation reaches the cold-end heat exchanger 22, where it cools down by exchanging heat with cold water and liquefies at a specific temperature under a specific pressure. It then returns to the storage tank 20. The power generated by the entire system can ultimately be connected to the grid via a grid-connected inverter.

[0048] In the working fluid circulation pipe assembly, the hot and cold end heat exchanger 16 has four flange 21 interfaces. Two of them are connected to the hot and cold water inlets and outlets, respectively. The other two flange 21 interfaces are the working fluid inlet and outlet, respectively. All flange 21 connecting pipes are made of stainless steel. The lower outlet flange 21 of the liquid storage tank 20 is connected to the inlet flange 21 of the working fluid pump 19. The outlet flange 21 of the working fluid pump 19 is connected to the working fluid inlet flange 21 of the hot end heat exchanger 16 through a pipeline. The working fluid outlet flange 21 of the hot end heat exchanger 16 is connected to the inlet flange 21 of the gas-liquid separator 23 through a pipeline. The outlet flange 21 of the gas-liquid separator 23 is connected to the inlet flange 21 of the turbine 24 through a pipeline. The outlet flange 21 of the turbine 24 is connected to the inlet flange 21 of the cold end heat exchanger 22 through a pipeline. The outlet flange 21 of the cold end heat exchanger 22 is connected to the upper inlet flange 21 of the liquid storage tank 20 through a pipeline.

[0049] This embodiment also includes an equipment container 5, in which the working fluid circulation pipe assembly is located, which can protect the components in the working fluid circulation pipe assembly and extend its service life.

[0050] Example 2

[0051] like Figure 2 As shown, the difference between this embodiment and embodiment one is that two horizontal directional wells are drilled and two sets of cold water suction pipes 9 are lowered to reduce the cold water temperature, increase the temperature difference and power generation. Each of the two cold water suction pipes 9 is equipped with a shut-off valve 8 and an external cold water pump 7.

[0052] Example 3

[0053] like Figure 3 As shown, the difference between this embodiment and embodiment one is that the casing window is opened in the main well to carry out deeper horizontal directional drilling. The upper part of the cold water suction pipe 9 does not need to be lowered, which saves construction costs, reduces the cold water temperature, increases the temperature difference and power generation, and a shut-off valve 8 and an external cold water pump 7 are installed on the main pipe 13.

[0054] Example 4

[0055] like Figures 1-4 As shown, this embodiment provides a method for generating electricity from near-island reefs using thermoelectric energy conversion, employing the thermoelectric energy conversion system for near-island reefs described in Embodiment 1, Embodiment 2, or Embodiment 3, and includes the following steps:

[0056] 1. First, determine the total power generation, then determine the power generation efficiency based on the circulation method and circulating working medium, thereby obtaining the power generation capacity. Then, determine the required cold water temperature, well depth, cold and hot water circulation flow rate, and working medium pump 19 circulation flow rate based on the actual seawater surface temperature.

[0057] 2. Determine the casing 11 size and drilling process based on the determined cold water temperature, well depth, and cold water circulation flow rate. Use a drilling rig to complete directional drilling, drill to the target depth, connect with seawater 1, and then run casing 11. Install a filter at the front end of casing 11, and finally connect elbow joint, shut-off valve 8, external cold water pump 7 and cold water tank 6.

[0058] 3. Connect the hot water suction pipe 3. The float 4 is fixed to the outside of the hot water suction pipe 3 with bolts and laid out towards the sea surface. The hot water suction pipe 3 has multiple sections. The front end of the hot water suction pipe 3 is connected to the hot water filter 2, and the rear end of the hot water suction pipe 3 is connected to the hot water pump 15.

[0059] 4. Connect the working fluid circulation pipe assembly. After connection, perform pressure and vacuum tests to ensure that there are no leaks in the connection.

[0060] 5. Connect the cold water drain pipe 18 and the hot water drain pipe 17, and extend one end of them into the seawater 1;

[0061] 6. Fill the storage tank 20 with working fluid to 2 / 3 of its height;

[0062] 7. Turn on the external cold water pump 7 to draw deep seawater with a lower temperature into the cold water tank 6. When the cold water tank 6 has a certain amount of cold water, turn on the cold water pump to lower the temperature of the entire cold water circulation pipe group and keep circulating until the designed cold water temperature is reached. At this time, the working fluid has been liquefied by cooling.

[0063] 8. Turn on hot water pump 15 to draw surface seawater, raise the temperature of the entire hot water circulation pipe group, maintain circulation until the designed hot water temperature is reached, which can vaporize the working fluid.

[0064] 9. Turn on the working fluid pump 19 to draw the liquid working fluid from the storage tank 20 and inject it into the hot end heat exchanger 16, where it exchanges heat with the hot water in the hot water circulation pipe group and vaporizes the working fluid.

[0065] 10. The gasified working fluid enters the gas-liquid separator 23, and then rises into the turbine 24, which drives it to rotate and generate electricity;

[0066] 11. After power generation, the working gas becomes exhaust gas and enters the cold end heat exchanger 22, where it exchanges heat with the cold water in the cold water circulation pipe group, liquefying the working gas.

[0067] 12. The liquefied working fluid flows back to the storage tank 20, and is then pumped back into the hot end heat exchanger 16 by the working fluid pump 19. The fluid is repeatedly circulated to generate electricity from the temperature difference. The hot and cold water after heat exchange are respectively drained from the cold water drain pipe 18 and the hot water drain pipe 17 and then re-enter the seawater 1.

[0068] The power generation parameters of the entire system can be viewed and operated in real time inside the container.

[0069] like Figure 2 As shown, when it is necessary to increase the power generation, a drilling rig can be used to drill a new directional well not far from the original wellbore, drilling to a deeper position below the seabed, running casing 11, installing a shut-off valve 8 and an external cold water pump 7. The external cold water pump 7 is connected to the three-way flange 21 of the cold water tank 6 used in the first wellbore to increase the cold water volume and reduce the temperature of the cold seawater 1, thereby increasing the power generation.

[0070] like Figure 3 As shown, under the condition of saving costs, the casing windowing process can also be used in the original wellbore to drill branch wells to a deeper position below the seabed. The upper casing 11 of the casing window can continue to be used, and the temperature of the cold seawater 1 is reduced, the temperature difference is increased, and the power generation capacity is increased.

[0071] This embodiment connects deep seawater to the wellhead through directional well drilling, and runs the casing 11 into the formation. The structure is stable and reliable, and avoids the cold water intake pipe 9 from being easily broken or fatigued due to floating in seawater 1 for a long time. Furthermore, multiple directional wells can be connected in parallel or a single directional well can be opened and re-drilled to increase the amount of cold water obtained and increase the power generation.

[0072] This specification uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A thermoelectric power generation system for use near islands and reefs, characterized in that: The system includes a hot water circulation pipe assembly, a cold water circulation pipe assembly, and a working fluid circulation pipe assembly. The working fluid circulation pipe assembly includes a hot-end heat exchanger, a storage tank, a cold-end heat exchanger, and a turbine. One end of the hot water circulation pipe assembly extends into the surface seawater, and the middle part of the hot water circulation pipe assembly is connected to the hot-end heat exchanger and is used to vaporize the working fluid transported from the storage tank to drive the turbine to generate electricity. The other end of the hot water circulation pipe assembly extends into the seawater. One end of the cold water circulation pipe assembly enters the deep seawater through a borehole completed near the island reef. The middle part of the cold water circulation pipe assembly is connected to the cold-end heat exchanger and is used to liquefy the working fluid discharged from the turbine so that it flows back into the storage tank. The other end of the cold water circulation pipe assembly extends into the seawater. The hot water circulation pipe assembly includes a hot water intake pipe, a hot water filter, a buoyancy element, a hot water pump, and a hot water drain pipe. One end of the hot water intake pipe is equipped with the hot water filter and extends into the surface seawater. The other end of the hot water intake pipe is connected to the inlet of the hot water pump. The outlet of the hot water pump is connected to the inlet of the hot end heat exchanger. The buoyancy element is located in the middle of the hot water intake pipe. One end of the hot water drain pipe is connected to the outlet of the hot end heat exchanger, and the other end of the hot water drain pipe extends into the seawater. The cold water circulation pipe assembly includes a cold water tank, a cold water drain pipe, a built-in cold water pump, and several cold water suction elements. One end of each cold water suction element extends into deep seawater, and the other end of each cold water suction element is connected to the inlet of the cold water tank. The outlet of the cold water tank is connected to the inlet of the built-in cold water pump, and the outlet of the built-in cold water pump is connected to one end of the cold water drain pipe. The other end of the cold water drain pipe extends into seawater. The cold water circulation pipe assembly also includes several shut-off valves and several external cold water pumps. The cold water suction element includes a cold water suction pipe and a cold water filter. One end of the cold water suction pipe is equipped with the cold water filter and extends into deep seawater. The other end of each cold water suction pipe is connected to one end of a main pipe. The other end of the main pipe is connected to the inlet of the external cold water pump. The outlet of the external cold water pump is connected to the inlet of the cold water tank. The shut-off valve is installed on each cold water suction pipe or the main pipe. The cold water suction pipe includes multiple sleeves that are connected sequentially in the length direction. The working fluid circulation pipe assembly also includes a working fluid pump and a gas-liquid separator. The working fluid outlet of the hot-end heat exchanger is connected to the working fluid inlet of the gas-liquid separator. The working fluid outlet of the gas-liquid separator is connected to the working fluid inlet of the turbine. The working fluid outlet of the turbine is connected to the working fluid inlet of the cold-end heat exchanger. The working fluid outlet of the cold-end heat exchanger is connected to the working fluid inlet of the liquid storage tank. The working fluid outlet of the liquid storage tank is connected to the working fluid inlet of the working fluid pump. The working fluid outlet of the working fluid pump is connected to the working fluid inlet of the hot-end heat exchanger.

2. The thermoelectric power generation system for near-island reefs according to claim 1, characterized in that: The buoyancy element includes a plurality of floats arranged along the length of the hot water intake pipe.

3. The thermoelectric power generation system for near-island reefs according to claim 1, characterized in that: The buoyancy element is bolted to the hot water suction pipe. The hot water filter is connected to one end of the hot water suction pipe via a flange. The other end of the hot water suction pipe is connected to the inlet of the hot water pump via a flange. The outlet flange of the hot water pump is connected to the inlet flange of the hot end heat exchanger via a stainless steel pipe. The outlet flange of the hot end heat exchanger is connected to one end of the hot water drain pipe via a stainless steel pipe.

4. The thermoelectric power generation system for near-island reefs according to claim 1, characterized in that: The adjacent sleeves are connected by threads. The lowermost sleeve is connected to the cold water filter by threads. The uppermost sleeve is connected to the inlet flange of the shut-off valve by a flange and an elbow flange. The outlet flange of the shut-off valve is connected to the inlet flange of the external cold water pump. The outlet flange of the external cold water pump is connected to the inlet flange of the cold water tank. The outlet flange of the cold water tank is connected to the inlet flange of the cold end heat exchanger by a stainless steel pipe. The outlet flange of the cold end heat exchanger is connected to one end of the cold water drain pipe by a stainless steel pipe.

5. The thermoelectric power generation system for near-island reefs according to claim 1, characterized in that: It also includes an equipment container, inside which the working fluid circulation pipe assembly is located.

6. A method for generating electricity using thermoelectric energy conversion near islands and reefs, characterized in that: Using the near-island / reef thermoelectric power generation system according to any one of claims 1-5 includes the following steps: S1. Calculate the power generation capacity based on the total power generation and power generation efficiency, and then determine the parameters of the near-island and reef thermal energy power generation system based on the actual sea surface temperature. S2, use a drilling rig to complete directional drilling, drill to the target depth, connect with seawater, and then lower a cold water suction pipe to complete the assembly of the near-island reef thermoelectric power generation system. S3, Perform pressure and vacuum tests on the near-island and reef thermoelectric power generation system to ensure that there are no leaks in the connection; S4, put one end of the hot water circulation pipe assembly and one end of the cold water circulation pipe assembly into seawater; S5, inject the working medium into the storage tank, and the liquid level of the working medium is located at 2 / 3 of the inside of the storage tank; S6, deep seawater is extracted through the cold water circulation pipe group and circulated within the cold water circulation pipe group to reach the designed cold water temperature. S7, draw surface seawater through the hot water circulation pipe group and circulate the surface seawater in the hot water circulation pipe group to reach the designed hot water temperature; S8, the liquid working medium in the storage tank is injected into the hot end heat exchanger and exchanged with the surface seawater in the hot water circulation pipe group to vaporize the working medium and drive the turbine to rotate and generate electricity. S9, the working gas after power generation enters the cold end heat exchanger and exchanges heat with the deep seawater in the cold water circulation pipe group, liquefying the working gas and flowing back into the storage tank.

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