Ocean platform low-temperature geothermal organic Rankine cycle power generation system and equipment

Abstract

The invention discloses an ocean platform low-temperature terrestrial heat organic Rankine cycle power generation system and device. A production reinjection system is used for outputting production water; the organic working medium circulating system can receive production water and comprises an evaporator, a turbine generator set, a condenser, a circulating pump and a preheater which are sequentially communicated through pipelines to form a closed loop; the natural gas output system comprises a return pipe which is coupled and communicated with the condenser; production water of the production reinjection system is in coupling communication with the working medium circulating system through an evaporator and a preheater, low-temperature terrestrial heat in the production water is recycled through an organic working medium, the organic working medium is vaporized after absorbing heat and enters the working medium circulating system in a gas state, and heat energy is converted into electric energy; a return pipe of the natural gas output system is in coupling communication with the working medium circulating system through a condenser, and the temperature of the organic working medium is reduced to be in a condensate state, so that the temperature lower than the temperature of production water is met, and low-temperature terrestrial heat is recycled.

Description

Technical Field

[0001] The present invention belongs to the field of low-temperature geothermal energy, and in particular relates to a low-temperature geothermal organic Rankine cycle power generation system and equipment for an ocean platform. Background Art

[0002] Geothermal energy is a huge energy source hidden in the earth, but its distribution is related to the depth of the stratum. The distribution of geothermal resources in my country is mainly medium and low temperature geothermal. Therefore, exploring medium and low temperature geothermal power generation technology is one of the key research directions in my country. Before the development of organic Rankine cycle ORC and other dual-cycle technologies, it was generally believed that low-temperature geothermal energy below 90°C was not economical for power generation. However, with the iterative screening of organic working fluids in organic Rankine cycle ORC, the value and economy of low-temperature geothermal energy have gradually emerged, especially for geothermal energy attached to fluids during marine oil and gas extraction. It does not require additional extraction costs, and the cost of electricity on marine platforms is extremely high. Therefore, the possibility and economy of power generation or heating are huge.

[0003] However, there are still certain application bottlenecks in how to realize the energy utilization of geothermal temperatures between 60℃ and 90℃. The main reason is that the cold sources of existing traditional organic Rankine geothermal power generation systems are mostly air-cooled or water-cooled. When utilizing low-temperature heat sources, there are fewer optional working fluids and the thermal utilization rate is low.

[0004] Therefore, it is urgent to design a low-temperature geothermal organic Rankine cycle power generation system for an ocean platform to solve the above-mentioned problems. Summary of the Invention

[0005] In order to solve the technical problems mentioned in the background technology that the cold sources of existing traditional organic Rankine geothermal power generation systems are mostly air-cooled or water-cooled, there are few optional working fluids when utilizing low-temperature heat sources, and the heat utilization rate is low, a low-temperature geothermal organic Rankine cycle power generation system and equipment for an ocean platform is provided.

[0006] To achieve the above objectives, the specific technical solutions of the present invention for a low-temperature geothermal organic Rankine cycle power generation system and equipment for an offshore platform are as follows: A low-temperature geothermal organic Rankine cycle power generation system for an ocean platform, comprising: Production reinjection system, which is used to output produced water; An organic working fluid circulation system, the organic working fluid circulation system is capable of receiving produced water, and the organic working fluid circulation system includes an evaporator, a turbine generator set, a condenser, a circulation pump, and a preheater connected in sequence through pipelines to form a closed loop; A natural gas transmission system, the natural gas transmission system includes a return pipe, the return pipe is coupled and connected to the condenser; The production water of the production reinjection system is coupled to the working fluid circulation system through an evaporator and a preheater, and the low-temperature geothermal energy in the production water is recovered using organic working fluid. After absorbing heat, the organic working fluid vaporizes and evaporates, entering the working fluid circulation system in a gaseous state, converting thermal energy into electrical energy. The return pipe of the natural gas transmission system is coupled to the working fluid circulation system through a condenser, reducing the temperature of the organic working fluid to a condensate state, thereby meeting a temperature lower than that of the production water and realizing the recovery of low-temperature geothermal energy.

[0007] Furthermore, the natural gas export system also includes a boosting device, the return pipe inlet of the natural gas export system is connected to the outlet of the boosting device, and the outlet is connected to the cold side inlet of the condenser; the cold side outlet of the condenser returns to the inlet of the boosting device through a pipeline, forming a natural gas reflux cooling loop.

[0008] Furthermore, the cold side outlet of the condenser is communicated with the inlet pipe of the boosting device, the hot side inlet of the condenser is communicated with the outlet of the turbine generator set, and the hot side outlet of the condenser is communicated with the inlet of the circulation pump.

[0009] Furthermore, the production reinjection system includes a production well, a separator, a production water treatment system, a production water booster pump, and a reinjection well, which are connected in sequence through pipelines.

[0010] Furthermore, the gas phase outlet of the separator is connected to the inlet of the boosting equipment of the natural gas transmission system, and the liquid phase outlet is connected to the production water treatment system.

[0011] Furthermore, the evaporator includes a hot side and a cold side, the hot side inlet of the evaporator is connected to the production water treatment system for receiving production water, the hot side outlet of the evaporator is connected to the preheater, the cold side inlet of the evaporator is connected to the cold side outlet of the preheater, and the cold side outlet of the evaporator is connected to the inlet of the turbine generator set.

[0012] Furthermore, the cold side inlet of the preheater is connected to the outlet of the circulation pump, and the hot side outlet is connected to the production water booster pump. The hot side fluid of the preheater is production water, and the cold side fluid is organic working fluid.

[0013] Furthermore, the produced water after heat recovery is pressurized by a produced water boosting pump and then reinjected into the reinjection well.

[0014] Furthermore, the natural gas transmission system further includes a throttle valve, which is located on the return pipe before the cold side inlet of the condenser.

[0015] A low-temperature geothermal organic Rankine cycle power generation device for an ocean platform uses the above-mentioned low-temperature geothermal organic Rankine cycle power generation system for an ocean platform.

[0016] The marine platform low-temperature geothermal organic Rankine cycle power generation system of the present invention has the following advantages: the marine platform low-temperature geothermal organic Rankine cycle power generation system effectively improves the heat extraction efficiency of the organic Rankine geothermal power generation system, and organically combines the marine oil and gas production process with the organic Rankine cycle process, which not only recovers the process waste heat of the marine oil and gas production process and realizes the cascade utilization of energy, but also meets the power generation needs. It has high practical value and promotion and application value, and is particularly suitable for low-temperature geothermal reinjection sites in the marine oil and gas production process.

[0017] The low-temperature geothermal organic Rankine cycle power generation equipment for an offshore platform of the present invention has the following advantages: by coupling a production reinjection system, an organic working fluid circulation system, and a natural gas transmission system, the low-temperature geothermal organic Rankine cycle power generation equipment for an offshore platform achieves dual recovery of geothermal energy and natural gas cold sources, thereby improving energy utilization efficiency. The equipment is applicable to low-temperature geothermal resources at temperatures between 60°C and 90°C, thereby resolving the low efficiency problem of traditional ORC systems in low-temperature scenarios. Furthermore, the equipment directly utilizes produced water and natural gas from the oil and gas extraction process, eliminating the need for additional cold source equipment and reducing platform space occupancy and investment costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic structural diagram of the marine platform low-temperature geothermal organic Rankine cycle power generation system of the present invention.

[0019] Description of the marks in the figure: 1. Production well; 2. Separator; 3. Production water treatment system; 4. Production water booster pump; 5. Recharge well; 6. Evaporator; 7. Turbine generator set; 8. Condenser; 9. Circulation pump; 10. Preheater; 11. Booster equipment; 12. Return pipe; 13. Throttle valve. DETAILED DESCRIPTION

[0020] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making any creative efforts shall fall within the scope of protection of the present invention.

[0021] Those skilled in the art will appreciate that although some embodiments herein include certain features included in other embodiments but not other features, the combination of features from different embodiments is intended to be within the scope of the present invention and to form different embodiments. For example, in the claims, any one of the claimed embodiments may be used in any combination.

[0022] Please refer to the attached Figure 1 The present invention describes a low-temperature geothermal organic Rankine cycle power generation system and equipment for an ocean platform.

[0023] This embodiment provides a low-temperature geothermal organic Rankine cycle power generation system for an ocean platform, such as Figure 1 As shown, the low-temperature geothermal organic Rankine cycle power generation system of the marine platform includes a production reinjection system, an organic working fluid circulation system and a natural gas export system. The production reinjection system is used to output produced water; the organic working fluid circulation system can receive produced water, and the organic working fluid circulation system includes an evaporator 6, a turbine generator set 7, a condenser 8, a circulation pump 9, and a preheater 10 connected in sequence by pipelines to form a closed loop; the natural gas export system includes a return pipe 12, which is coupled and connected to the condenser 8; the produced water of the production reinjection system is coupled and connected to the working fluid circulation system through the evaporator 6 and the preheater 10, and the low-temperature geothermal energy in the produced water is recovered by using the organic working fluid. After absorbing heat, the organic working fluid vaporizes and evaporates, enters the working fluid circulation system in a gaseous state, and converts the heat energy into electrical energy. The return pipe 12 of the natural gas export system is coupled and connected to the working fluid circulation system through the condenser 8, and the temperature of the organic working fluid is reduced to a condensate state, thereby meeting a temperature lower than that of the produced water, thereby realizing the recovery of low-temperature geothermal energy.

[0024] The natural gas export system further includes a booster 11. The inlet of the natural gas export system's return pipe 12 is connected to the outlet of the booster 11, and the outlet is connected to the cold-side inlet of the condenser 8. The cold-side outlet of the condenser 8 is returned to the inlet of the booster 11 via a pipeline, forming a natural gas return cooling loop. Throttled, low-temperature natural gas is used as the cooling source for the condenser 8, replacing traditional seawater cooling to prevent marine biofouling and equipment corrosion. The reduced-pressure natural gas reaches a lower temperature (e.g., -20°C), significantly improving the condensation efficiency of the working fluid and ensuring stable operation of the system under low-temperature geothermal conditions.

[0025] Furthermore, the production reinjection system includes a production well 1, a separator 2, a production water treatment system 3, a production water booster pump 4, and a reinjection well 5, which are sequentially connected through pipelines.

[0026] Furthermore, the gas phase outlet of the separator 2 is connected to the inlet of the boosting equipment 11 of the natural gas export system, and the liquid phase outlet is connected to the produced water treatment system 3. The gas phase outlet of the separator 2 is connected to the boosting equipment 11, realizing a seamless connection between the natural gas export and the power generation system, avoiding energy waste.

[0027] Furthermore, the evaporator 6 includes a hot side and a cold side. The hot side inlet of the evaporator 6 is connected to the produced water treatment system 3 for receiving produced water. The hot side outlet of the evaporator 6 is connected to the preheater 10. The cold side inlet of the evaporator 6 is connected to the cold side outlet of the preheater 10. The cold side outlet of the evaporator 6 is connected to the inlet of the turbine generator set 7. The produced water releases heat through the hot side of the evaporator 6, and the working fluid absorbs heat and vaporizes on the cold side, realizing direct conversion of geothermal energy. The waste heat after the produced water is treated is fully utilized, reducing heat energy waste. Furthermore, the cold side outlet of the condenser 8 is connected to the inlet pipe of the boosting device 11, the hot side inlet of the condenser 8 is connected to the outlet of the turbine generator set 7, and the hot side outlet of the condenser 8 is connected to the inlet of the circulation pump 9.

[0028] Furthermore, the cold-side inlet of preheater 10 is connected to the outlet of circulation pump 9, and the hot-side outlet is connected to produced water booster pump 4. The hot-side fluid of preheater 10 is produced water, and the cold-side fluid is an organic working fluid. Preheater 10 is connected in series with evaporator 6, preheating the working fluid before evaporation, reducing irreversible thermodynamic losses and improving power generation efficiency. The produced water at the hot-side outlet enters preheater 10 for a second heat release, further reducing the recharge water temperature and increasing geothermal heat extraction efficiency.

[0029] Furthermore, the produced water after heat recovery is pressurized by a produced water boosting pump and then reinjected into the reinjection well 5.

[0030] Furthermore, the natural gas transmission system further includes a throttle valve 13, which is located on the return pipe 12 before the cold side inlet of the condenser 8. The throttle valve 13 controls the pressure and flow of the return natural gas to meet the cooling requirements under different working conditions.

[0031] It is understandable that the system ensures the continuity and thermodynamic balance of the working medium circulation through the pipeline layout and component linkage design (such as the circulation pump 9 and the condenser 8 outlet connection).

[0032] This embodiment also provides a low-temperature geothermal organic Rankine cycle power generation device for an offshore platform, utilizing the aforementioned offshore platform low-temperature geothermal organic Rankine cycle power generation system. By coupling a production reinjection system, an organic working fluid circulation system, and a natural gas transmission system, this offshore platform low-temperature geothermal organic Rankine cycle power generation device achieves dual recovery of geothermal energy and natural gas cooling, improving energy utilization. This device is suitable for low-temperature geothermal resources between 60°C and 90°C, addressing the low efficiency of traditional ORC systems in low-temperature scenarios. Furthermore, it directly utilizes produced water and natural gas from the oil and gas production process, eliminating the need for additional cooling equipment and reducing platform space usage and investment costs.

[0033] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A low-temperature geothermal organic Rankine cycle power generation system for an ocean platform, characterized in that: include: Production reinjection system, which is used to output produced water; An organic working fluid circulation system, the organic working fluid circulation system is capable of receiving produced water, and the organic working fluid circulation system includes an evaporator, a turbine generator set, a condenser, a circulation pump, and a preheater connected in sequence through pipelines to form a closed loop; A natural gas transmission system, the natural gas transmission system includes a return pipe, the return pipe is coupled and connected to the condenser; The production water of the production reinjection system is coupled to the working fluid circulation system through an evaporator and a preheater. The low-temperature geothermal energy in the production water is recovered using organic working fluid. After absorbing heat, the organic working fluid vaporizes and evaporates, entering the working fluid circulation system in a gaseous state, converting thermal energy into electrical energy. The return pipe of the natural gas transmission system is coupled to the working fluid circulation system through a condenser, reducing the temperature of the organic working fluid to a condensate state, thereby meeting a temperature lower than that of the production water and realizing the recovery of low-temperature geothermal energy.

2. The marine platform low-temperature geothermal organic Rankine cycle power generation system according to claim 1, characterized in that: The natural gas export system also includes a boosting device. The return pipe inlet of the natural gas export system is connected to the outlet of the boosting device, and the outlet is connected to the cold side inlet of the condenser; the cold side outlet of the condenser returns to the inlet of the boosting device through a pipeline, forming a natural gas reflux cooling loop.

3. The marine platform low-temperature geothermal organic Rankine cycle power generation system according to claim 2, characterized in that: The cold side outlet of the condenser is communicated with the inlet pipe of the boosting equipment, the hot side inlet of the condenser is communicated with the outlet of the turbine generator set, and the hot side outlet of the condenser is communicated with the inlet of the circulating pump.

4. The marine platform low-temperature geothermal organic Rankine cycle power generation system according to claim 2, characterized in that: The production reinjection system includes a production well, a separator, a production water treatment system, a production water booster pump, and a reinjection well, which are connected in sequence through pipelines.

5. The marine platform low-temperature geothermal organic Rankine cycle power generation system according to claim 4, characterized in that: The gas phase outlet of the separator is connected to the inlet of the booster equipment of the natural gas transmission system, and the liquid phase outlet is connected to the production water treatment system.

6. The marine platform low-temperature geothermal organic Rankine cycle power generation system according to claim 4, characterized in that: The evaporator includes a hot side and a cold side. The hot side inlet of the evaporator is connected to the production water treatment system for receiving production water. The hot side outlet of the evaporator is connected to the preheater. The cold side inlet of the evaporator is connected to the cold side outlet of the preheater. The cold side outlet of the evaporator is connected to the inlet of the turbine generator set.

7. The marine platform low-temperature geothermal organic Rankine cycle power generation system according to claim 6, characterized in that: The cold side inlet of the preheater is connected to the outlet of the circulation pump, and the hot side outlet is connected to the production water booster pump. The hot side fluid of the preheater is production water, and the cold side fluid is organic working fluid.

8. The marine platform low-temperature geothermal organic Rankine cycle power generation system according to claim 7, characterized in that: The produced water after heat recovery is pressurized by the produced water boosting pump and then reinjected into the reinjection well.

9. The marine platform low-temperature geothermal organic Rankine cycle power generation system according to claim 1, characterized in that: The natural gas transmission system also includes a throttle valve, which is located on the return pipe before the cold side inlet of the condenser.

10. A low-temperature geothermal organic Rankine cycle power generation device for an ocean platform, characterized in that: The marine platform low-temperature geothermal organic Rankine cycle power generation system according to any one of claims 1 to 9 is used.

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