An island geothermal power and fresh water ice combined supply system

Abstract

The present invention discloses an island geothermal power and fresh water ice co-generation system, which relates to the technical field of power generation using special working fluids. The system obtains supercritical carbon dioxide fluid through heat exchange between geothermal fluid and carbon dioxide, utilizes the supercritical carbon dioxide fluid to work in a first expander, and then drives a first generator to generate electricity. In a jet ice-making unit, the carbon dioxide undergoes a transcritical refrigeration cycle and provides recycled carbon dioxide to the first expander. The remaining heat of the geothermal fluid can also be used to heat the organic working fluid of another organic Rankine cycle unit. The superheated organic working fluid gas enters a second expander to work, and then drives a second generator to generate electricity and realize the desalination unit to produce fresh water, thereby realizing efficient cascade utilization of low-grade thermal energy, improving energy utilization efficiency, reducing costs, and being conducive to the recycling of low-grade thermal energy, thus contributing to my country's energy conservation and emission reduction.

Description

Technical Field

[0001] The present invention relates to the technical field of power generation using special working fluids, and in particular to an island geothermal power and fresh water ice cogeneration system. Background Art

[0002] To address the current challenges of high water production costs and concentrated seawater discharge in seawater desalination, developing renewable energy for desalination and implementing cogeneration of electricity and desalination is a key long-term solution. To this end, researchers both domestically and internationally have actively explored new energy sources for desalination, such as solar and wind power. However, solar desalination requires large solar collector areas, resulting in limited scale and high costs. Furthermore, the volatility of solar energy prevents continuous and stable system operation. Desalination using wind power also faces challenges with equipment stability and high construction and maintenance costs. Geothermal energy is a green, low-carbon, recyclable renewable energy source with large reserves, widespread distribution, clean and environmentally friendly, and reliable stability. It is a viable and competitive clean energy source. Research has shown that due to the influence of deep mantle uplift, geothermal heat flow values are greater in island regions than in continental regions, indicating greater geothermal resources. Furthermore, island regions have high demand for ice and electricity, and the electricity and ice produced can be consumed locally, eliminating the need for long-distance transportation. Ensuring energy supply is an indispensable and key link in my country's strategy of becoming a maritime power, and it has important national defense, economic and environmental significance. Summary of the Invention

[0003] In response to the deficiencies in the prior art, the present invention provides an island geothermal energy-electricity-fresh ice co-supply system, which obtains supercritical carbon dioxide fluid through contact and heat exchange between geothermal fluid and carbon dioxide, and utilizes the supercritical carbon dioxide fluid to work in a first expander to drive a first generator to generate electricity. In the jet ice-making unit, the carbon dioxide undergoes a transcritical refrigeration cycle and provides recycled carbon dioxide to the first expander. The remaining heat of the geothermal fluid can also be used to heat the organic working fluid of another organic Rankine cycle unit. The superheated organic working fluid gas enters a second expander to work and drive a second generator to generate electricity and realize the desalination unit to produce fresh water, thereby realizing efficient cascade utilization of low-grade thermal energy, improving energy utilization efficiency, reducing costs, and being conducive to the recycling of low-grade thermal energy, thus contributing to my country's energy conservation and emission reduction.

[0004] To achieve the above objectives, the present invention can be implemented through the following technical solutions:

[0005] An island geothermal energy-electricity-ice cogeneration system, characterized by comprising: a first organic Rankine cycle unit and a second organic Rankine cycle unit, wherein the first organic Rankine cycle unit comprises a spray ice making unit, a first expander and a first generator, and the second organic Rankine cycle unit comprises: a second expander, a desalination unit and a second generator, wherein:

[0006] The first organic Rankine cycle unit utilizes geothermal fluid to contact and exchange heat with carbon dioxide to obtain supercritical carbon dioxide fluid, and the supercritical carbon dioxide fluid enters the first expander to perform work, thereby driving the first generator to generate electricity, wherein the exhaust steam of the first expander draws the carbon dioxide in the spray ice-making unit to achieve ice making, and part of the carbon dioxide is used for heat exchange with the geothermal fluid;

[0007] The second organic Rankine cycle unit utilizes geothermal fluid to heat an organic working fluid to form an organic working fluid gas. The organic working fluid gas enters the second expander to perform work and thereby drives the second generator to generate electricity. The heat of the condenser of the first expander and the geothermal fluid is utilized to drive the desalination unit to produce fresh water.

[0008] The island geothermal energy, electricity, and ice co-generation system as described above further includes a production well, a carbon dioxide heater, and a carbon dioxide separator. The jet ice-making unit includes an ice-making evaporator, an ejector, a pressure pump, a throttle valve, and a replenishing valve. The production well collects geothermal fluid and transports it to the carbon dioxide heater. In the carbon dioxide heater, the geothermal fluid heats the carbon dioxide transported from the jet ice-making unit into a supercritical state and transports it to the carbon dioxide separator. The carbon dioxide separated by the carbon dioxide separator enters the first expander to work, driving the first generator to generate electricity. The exhaust steam of the first expander ejects the carbon dioxide in the ice-making evaporator to achieve ice making. The ejected mixed carbon dioxide is divided into two paths through the throttle valve, one path entering the ice-making evaporator, and the other path entering the carbon dioxide heater through the pressure pump.

[0009] As described above, in the island geothermal energy combined electricity and ice supply system, further, during the mixing and heating process of carbon dioxide and geothermal fluid, part of the carbon dioxide dissolves in the geothermal fluid and is reinjected into the reinjection well along with the geothermal fluid.

[0010] The island geothermal energy, electricity, and ice co-production system as described above is further characterized in that the first inlet of the carbon dioxide heater is connected to the production well, the first outlet of the carbon dioxide heater is connected to the inlet end of the carbon dioxide separator, the first outlet of the carbon dioxide separator is connected to the inlet end of the first expander, the outlet end of the first expander is connected to the first inlet of the ejector, the outlet end of the ejector is connected to the inlet end of the ice-making evaporator via the throttle valve, the outlet end of the ejector is connected to the second inlet of the carbon dioxide heater via the throttle valve and the booster pump, the outlet end of the ice-making evaporator is connected to the second inlet of the ejector, and the replenishing valve is arranged on the pipeline with the booster pump.

[0011] The island geothermal energy electricity fresh water ice co-generation system as described above further includes a generator, a regenerator, a recharge well, a working fluid pump and a condenser. The desalination unit includes a spray chamber, a condensation chamber, a concentrated seawater storage tank, a concentrated seawater storage tank, a cold seawater tank and a fresh water storage tank. The geothermal fluid flowing out of the bottom of the carbon dioxide heater and the carbon dioxide separator is mixed and then enters the generator. The generator uses the heat of the geothermal fluid to heat the organic working fluid of the second organic Rankine cycle unit into an organic working fluid gas. The organic working fluid gas enters the second expander to work and then drives the The second generator generates electricity, and the seawater stored in the cold seawater tank enters the condensing chamber, condenses the water vapor flowing through the spray chamber into liquid water, and then enters the condenser. After the heat of the exhaust steam of the second expander is recovered in the condenser, it enters the regenerator, and the remaining heat of the geothermal fluid discharged from the generator is recovered in the regenerator. Finally, it enters the spray chamber for spraying. The evaporated water vapor is cooled into liquid water in the condensing chamber and enters the fresh water storage tank. The evaporated seawater enters the concentrated seawater storage tank, and the geothermal water discharged from the regenerator is reinjected into the recharge well.

[0012] The island geothermal energy, electricity, fresh water and ice co-generation system as described above, further, the first inlet of the generator is connected to the second outlet of the carbon dioxide separator, the first outlet of the generator is connected to the first inlet of the regenerator, the second expander, the condenser, the working fluid pump and the generator are connected in sequence, the outlet end of the regenerator is connected to the inlet end of the spray chamber, the first outlet of the spray chamber is connected to the first inlet of the condensing chamber, the outlet end of the cold seawater tank is connected to the second inlet of the condensing chamber, the first outlet of the condensing chamber is connected to the inlet end of the condenser, the outlet end of the condenser is connected to the inlet end of the regenerator, the second outlet of the spray chamber is connected to the concentrated seawater storage tank, and the second outlet of the condensing chamber is connected to the fresh water storage tank.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] (1) Direct contact mixed heating method is used to transfer the heat of geothermal fluid to carbon dioxide, which has the advantages of heat transfer effect, no heat transfer temperature difference, and low investment.

[0015] (2) Taking advantage of the fact that carbon dioxide is soluble in geothermal fluids, the underground physical storage of carbon dioxide can be achieved.

[0016] (3) Fully recovering the heat from the organic Rankine cycle condenser and geothermal tail water for seawater desalination can achieve deep cascade utilization of geothermal resources.

[0017] (4) The demand for electricity, fresh water and ice is high in island areas, and this system has good adaptability. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 This is a structural diagram of an island geothermal power and fresh ice combined supply system according to an embodiment of the present invention.

[0020] Explanation of the accompanying symbols: 1. generator; 2. carbon dioxide expander; 3. ice making evaporator; 4. ejector; 5. carbon dioxide separator; 6. carbon dioxide heater; 7. pressure pump; 8. throttle valve; 9. replenishing valve; 10. production well; 11. low-pressure stage expander; 12. generator; 13. regenerator; 14. reinjection well; 15. working fluid pump; 16. condenser; 17. spray chamber; 18. condensing chamber; 19. concentrated seawater storage tank; 20. cold seawater tank; 21. fresh water storage tank. DETAILED DESCRIPTION

[0021] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0022] Example:

[0023] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof in the embodiments of the present invention are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0024] In the description of the present invention, "plurality" means at least two, such as two or three, unless otherwise specifically defined. Furthermore, unless otherwise specified or defined, the terms "mounted," "connected," and "connected" should be understood broadly, meaning, for example, fixed, removable, or integral; mechanical or electrical; direct or indirect through an intermediary; and internal communication between two components. Those skilled in the art will understand the specific meanings of these terms in the present invention.

[0025] See also Figure 1 , Figure 1 The figure is a schematic diagram of the structure of an island geothermal power-fresh ice cogeneration system according to an embodiment of the present invention. The present invention provides an island geothermal power-fresh ice cogeneration system. This system, targeted at applications such as solar energy, geothermal energy, and ocean temperature difference energy, utilizes heat exchange between geothermal fluid and carbon dioxide to produce supercritical carbon dioxide fluid. This supercritical carbon dioxide fluid is then used to generate power in a first expander, thereby driving a first generator to generate electricity. In the jet ice-making unit, the carbon dioxide undergoes a transcritical refrigeration cycle and provides recycled carbon dioxide to the first expander. The remaining heat from the geothermal fluid is then used to heat the organic working fluid in another organic Rankine cycle unit. The superheated organic working fluid enters a second expander to generate power, driving the second generator to generate electricity and enabling the desalination unit to produce fresh water. This system achieves efficient, cascaded utilization of low-grade thermal energy, improves energy efficiency, reduces costs, and facilitates the recycling of low-grade thermal energy, contributing to my country's energy conservation and emission reduction efforts.

[0026] A geothermal energy-to-electricity-to-ice cogeneration system for an island, characterized by comprising: a first organic Rankine cycle (ORC) unit and a second ORC unit, wherein the first ORC unit comprises a jet ice-making unit, a first expander, and a first generator, and the second ORC unit comprises a second expander, a desalination unit, and a second generator, wherein the first ORC unit utilizes geothermal fluid to contact and exchange heat with carbon dioxide to obtain supercritical carbon dioxide fluid, which enters the first expander to perform work and thereby drive the first generator to generate electricity, wherein exhaust steam from the first expander ejects carbon dioxide from the jet ice-making unit to achieve ice production, and part of the carbon dioxide is used for heat exchange with the geothermal fluid, wherein the second ORC unit utilizes geothermal fluid to heat an organic working fluid to form an organic working fluid gas, which enters the second expander to perform work and thereby drive the second generator to generate electricity, wherein the heat from the condenser 16 of the first expander and the geothermal fluid is used to drive the desalination unit to produce fresh water.

[0027] The above embodiment further includes a production well 10, a carbon dioxide heater 6, and a carbon dioxide separator 5. The jet ice-making unit includes an ice-making evaporator 3, an ejector 4, a pressure pump 7, a throttle valve 8, and a replenishing valve 9. The first inlet of the carbon dioxide heater 6 is connected to the production well 10, the first outlet of the carbon dioxide heater 6 is connected to the inlet of the carbon dioxide separator 5, the first outlet of the carbon dioxide separator 5 is connected to the inlet of the first expander, the outlet of the first expander is connected to the first inlet of the ejector 4, the outlet of the ejector 4 is connected to the inlet of the ice-making evaporator 3 via the throttle valve 8, the outlet of the ejector 4 is connected to the second inlet of the carbon dioxide heater 6 via the throttle valve 8 and the pressure pump 7, and the outlet of the ice-making evaporator 3 is connected to the second inlet of the ejector 4. During the mixing and heating process of carbon dioxide and geothermal fluid, a certain proportion of carbon dioxide will dissolve in the geothermal fluid and be reinjected into the reinjection well along with the geothermal fluid, achieving a certain degree of physical sequestration of carbon dioxide. The replenishing valve 9 is provided on the pipeline with the pressure pump 7.

[0028] In the above embodiment, a generator 12, a regenerator 13, a recharge well 14, a working fluid pump 15 and a condenser 16 are further included. The desalination unit includes a spray chamber 17, a condensation chamber 18, a concentrated seawater storage tank 19, a concentrated seawater storage tank 19, a cold seawater tank 20 and a fresh water storage tank 21. The first inlet of the generator 12 is connected to the second outlet of the carbon dioxide separator 5, the first outlet of the generator 12 is connected to the first inlet of the regenerator 13, the second expander, the condenser 16, the working fluid pump 15 and the generator 12 are connected in sequence. The outlet end of the regenerator 13 is connected to the inlet end of the spray chamber 17, the first outlet of the spray chamber 17 is connected to the first inlet of the condensing chamber 18, the outlet end of the cold seawater tank 20 is connected to the second inlet of the condensing chamber 18, the first outlet of the condensing chamber 18 is connected to the inlet end of the condenser 16, the outlet end of the condenser 16 is connected to the inlet end of the regenerator 13, the second outlet of the spray chamber 17 is connected to the concentrated seawater storage tank 19, and the second outlet of the condensing chamber 18 is connected to the fresh water storage tank 21.

[0029] A complete workflow of the present invention may include:

[0030] The carbon dioxide pressurized by the CO2 booster pump 7 is directly mixed and heated with geothermal fluid extracted from a production well 10 in a contact CO2 heater 6, where it is heated to a supercritical state. The supercritical CO2 then enters the CO2 separator 5. The separated CO2 enters the CO2 expander 2, producing power and driving the generator 1 to output electricity. Exhaust steam from the CO2 expander 2 of the supercritical CO2 power generation system is used to inject CO2 from the ice-making evaporator 3, achieving ice production. The injected mixed CO2 is split into two paths by a throttle valve 8: one path enters the ice-making evaporator 3, and the other path enters the contact CO2 heater 6 via the CO2 booster pump 7. During the mixing and heating process, the CO2 dissolves in a certain proportion of the geothermal fluid's CO2. This is then reinjected into the re-injection well along with the geothermal fluid, achieving a certain degree of physical sequestration of the CO2. A CO2 replenishment valve 9 is located before the CO2 booster pump 7.

[0031] The geothermal fluid flowing from the bottom of the contact CO2 heater 6 and the CO2 separator 5 mix and then enter the generator 12, heating the organic working fluid to a superheated state. The organic working fluid then enters the low-pressure expander 11 to perform work, driving the generator 1 to generate electricity. The cold seawater in the cold seawater tank 20 enters the condensing chamber 18, condensing the water vapor flowing through the spray chamber 17 into liquid water. The water then enters the condenser 16 to recover the heat of the exhaust steam from the low-pressure expander 11. The water then enters the regenerator 13 to recover the heat of the geothermal tail water discharged from the generator 12. Finally, the water enters the spray chamber 17 for spraying. The evaporated water vapor is cooled to liquid water in the condensing chamber and enters the fresh water storage tank 21. The evaporated seawater enters the concentrated seawater storage tank 19. The geothermal water discharged from the regenerator 13 is reinjected into the recharge well 14.

[0032] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0033] The above embodiments are intended only to illustrate the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made based on the essence of the present invention are intended to be covered by the scope of protection of the present invention.

Claims

1. An island geothermal energy electricity and ice combined supply system, characterized in that: include: A first organic Rankine cycle unit and a second organic Rankine cycle unit, wherein the first organic Rankine cycle unit includes a spray ice making unit, a first expander and a first generator, and the second organic Rankine cycle unit includes a second expander, a desalination unit and a second generator, wherein: The first organic Rankine cycle unit utilizes geothermal fluid to contact and exchange heat with carbon dioxide to obtain supercritical carbon dioxide fluid, and the supercritical carbon dioxide fluid enters the first expander to perform work, thereby driving the first generator to generate electricity, wherein the exhaust steam of the first expander draws the carbon dioxide in the spray ice-making unit to achieve ice making, and part of the carbon dioxide is used for heat exchange with the geothermal fluid; The second organic Rankine cycle unit utilizes geothermal fluid to heat an organic working fluid to form an organic working fluid gas. The organic working fluid gas enters the second expander to perform work and thereby drive the second generator to generate electricity. The heat of the condenser of the first expander and the geothermal fluid is utilized to drive the desalination unit to produce fresh water. It also includes a production well, a carbon dioxide heater and a carbon dioxide separator, a generator, a regenerator, a recharge well, a working fluid pump and a condenser. The desalination unit includes a spray chamber, a condensation chamber, a concentrated seawater storage tank, a concentrated seawater storage tank, a cold seawater tank and a fresh water storage tank. The geothermal fluid flowing out of the bottom of the carbon dioxide heater and the carbon dioxide separator is mixed and then enters the generator. The generator uses the heat of the geothermal fluid to heat the organic working fluid of the second organic Rankine cycle unit into an organic working fluid gas. The organic working fluid gas enters the second expander to work and then drives the second The generator generates electricity, and the seawater stored in the cold seawater tank enters the condensing chamber, condensing the water vapor flowing through the spray chamber into liquid water. The seawater then enters the condenser, recovers the heat of the exhaust steam of the second expander in the condenser, and then enters the regenerator. The remaining heat of the geothermal fluid discharged from the generator is recovered in the regenerator, and finally enters the spray chamber for spraying. The evaporated water vapor is cooled into liquid water in the condensing chamber and enters the fresh water storage tank. The evaporated seawater enters the concentrated seawater storage tank, and the geothermal water discharged from the regenerator is reinjected into the recharge well.

2. The island geothermal energy electricity and ice cogeneration system according to claim 1, characterized in that: The jet ice-making unit includes an ice-making evaporator, an ejector, a pressure pump, a throttle valve, and a replenishing valve. The production well collects geothermal fluid and transports it to the carbon dioxide heater. In the carbon dioxide heater, the geothermal fluid heats the carbon dioxide transported from the jet ice-making unit into a supercritical state and transports it to the carbon dioxide separator. The carbon dioxide separated by the carbon dioxide separator enters the first expander to perform work, driving the first generator to generate electricity. The exhaust steam of the first expander ejects the carbon dioxide in the ice-making evaporator to achieve ice making. The ejected mixed carbon dioxide is divided into two paths by the throttle valve, one path entering the ice-making evaporator and the other path entering the carbon dioxide heater through the pressure pump.

3. The island geothermal energy electricity and ice cogeneration system according to claim 2, characterized in that: During the mixing and heating process of carbon dioxide and geothermal fluid, part of the carbon dioxide dissolves in the geothermal fluid and is reinjected into the reinjection well along with the geothermal fluid.

4. The island geothermal energy electricity and ice cogeneration system according to claim 2, characterized in that: The first inlet of the carbon dioxide heater is connected to the production well, the first outlet of the carbon dioxide heater is connected to the inlet of the carbon dioxide separator, the first outlet of the carbon dioxide separator is connected to the inlet of the first expander, the outlet of the first expander is connected to the first inlet of the ejector, the outlet of the ejector is connected to the inlet of the ice-making evaporator via the throttle valve, the outlet of the ejector is connected to the second inlet of the carbon dioxide heater via the throttle valve and the boosting pump, the outlet of the ice-making evaporator is connected to the second inlet of the ejector, and the replenishing valve is arranged on the pipeline with the boosting pump.

5. The island geothermal energy electricity and ice co-generation system according to claim 1, characterized in that: The first inlet of the generator is connected to the second outlet of the carbon dioxide separator, the first outlet of the generator is connected to the first inlet of the regenerator, the second expander, the condenser, the working fluid pump and the generator are connected in sequence, the outlet end of the regenerator is connected to the inlet end of the spray chamber, the first outlet of the spray chamber is connected to the first inlet of the condensing chamber, the outlet end of the cold seawater tank is connected to the second inlet of the condensing chamber, the first outlet of the condensing chamber is connected to the inlet end of the condenser, the outlet end of the condenser is connected to the inlet end of the regenerator, the second outlet of the spray chamber is connected to the concentrated seawater storage tank, and the second outlet of the condensing chamber is connected to the fresh water storage tank.

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