Self-circulation geothermal energy power generation system based on underground flash evaporation of U-shaped well

Abstract

The invention discloses a self-circulation geothermal energy power generation system based on underground flash evaporation of a U-shaped well, and relates to the field of geothermal exploitation and power generation. The system comprises a butt joint well, a flash evaporation cavity, a vertical production well and a power generation terminal. A high-thermal-conductivity cement layer is arranged outside the butt-joint well sleeve, a water injection inlet is formed in one end of the butt-joint well, a guide pipe is connected to the other end of the butt-joint well, and an atomization valve is arranged at the other end of the guide pipe and arranged in the flash evaporation cavity; the upper end of the flash evaporation cavity is connected with the lower end of the vertical production well, and a steam outlet in the upper end of the vertical production well is connected with the power generation terminal through a first pipeline; and the water injection inlet is connected with the power generation terminal through a second pipeline. Compared with a traditional closed-loop hydrothermal system, heat energy can automatically move upwards along with high-pressure steam, large equipment such as a high-pressure circulating pump, a turbine, a generator and a condenser is not needed, and investment and operation and maintenance cost are reduced. The system is high in safety, does not need long-term monitoring and maintenance, and has small influence on the environment.

Description

Technical Field

[0001] The present invention relates to the field of geothermal exploitation and power generation, and particularly to a self-circulating geothermal power generation system based on underground flashing of U-shaped wells. Background Art

[0002] The closed-loop geothermal system uses a sealed well as a heat exchanger, and the working fluid flows through it to extract heat, avoiding the operation of pumping or injecting water into the high-temperature formation, and reducing environmental and safety problems including induced earthquakes, groundwater pollution, etc. At present, the structural design of the closed-loop system mainly includes concentric tube configuration and U-shaped wells. The concentric tube structure consists of two pipes with different diameters that share a common central axis, and the structure is relatively complex; the internal structure of the U-shaped well is simpler. Only on the basis of a vertical well, a docking well including an injection section and a horizontal section needs to be constructed, which is easy to implement in engineering.

[0003] Traditional U-shaped well systems use water as the working fluid for extracting geothermal energy. These water-heat systems inject low-temperature water from the injection well, heat the water by using high-temperature rock masses, and then pump the hot water out from the vertical well, and generate electricity on the ground through flashing and other methods. Large equipment such as high-pressure circulation pumps, turbines, generators, and condensers are required during the operation of traditional systems, which not only requires more construction funds, but also significantly increases the system complexity and operation cost.

[0004] Some working fluids can cause corrosion to pipelines. Once the pipeline is damaged and leaks, it will not only cause harm to the environment, but also pose a risk of explosion, increasing the maintenance cost. The use of such working fluids is not conducive to the long-term safe operation of the system. For example, the organic working fluids commonly used in the organic Rankine cycle and ammonia used in the Kalina cycle.

[0005] Therefore, it is necessary to develop a pump-free closed-loop geothermal power generation system based on underground flashing of U-shaped wells to solve the above problems. Summary of the Invention

[0006] The object of the present invention patent is to provide a self-circulating geothermal power generation system based on underground flashing of U-shaped wells that can operate for a long time, save costs, and is safe.

[0007] To achieve the above object, the present invention patent provides the following technical solutions: A self - circulating geothermal power generation system based on underground flash evaporation in a U - shaped well. The power generation system includes a docking well, a flash evaporation cavity, a vertical production well, and a power generation terminal. The outside of the docking well is wrapped with a high - thermal - conductivity cement layer. One end of the docking well is a water injection inlet, and the other end is connected to a conduit. The other end of the conduit is provided with an atomizing valve and is arranged in the flash evaporation cavity. The upper end of the flash evaporation cavity is connected to the lower end of the vertical production well. The steam outlet at the upper end of the vertical production well is connected to the power generation terminal through a first pipeline. The water injection inlet is connected to the power generation terminal through a second pipeline.

[0008] Specifically, the docking well is divided into an injection section and a horizontal section.

[0009] Specifically, the outside of the casing of the vertical production well is an insulation layer.

[0010] Specifically, the power generation terminal can be equipped with a turbine or a thermoelectric generation module.

[0011] Specifically, the vertical production well can be connected to several docking wells.

[0012] Specifically, the docking well can be a multi - branch section.

[0013] The beneficial effects of this invention patent are as follows: 1. Compared with the open - loop hydrothermal system, this application has no water loss, can reuse water resources, protect the environment, does not require fracturing for reservoir construction, avoids induced earthquakes, and saves costs. 2. Compared with the traditional closed - loop hydrothermal system, this patent can realize the automatic migration of steam - carried heat energy, does not require large - scale equipment such as high - pressure pumps, turbines, generators, and condensers, and reduces investment and operation and maintenance costs. 3. Compared with the systems based on working fluids such as organic substances and ammonia, this patent has high safety, does not require long - term monitoring and maintenance, and has little impact on the environment. 4. The power generation terminal of this patent can choose a turbine or a thermoelectric generation module. The turbine can directly generate electricity using steam with higher efficiency. The thermoelectric generation module can be produced modularly, has low cost, can be built underground, and occupies a small area.

[0014] The above description is only an overview of the technical solution of this invention patent. In order to understand the technical means of this invention patent more clearly and be able to implement it according to the content of the specification, the following takes the preferred embodiments of this invention patent and coordinates with the attached drawings to explain in detail as follows. Brief Description of the Drawings

[0015] Figure 1 It is a schematic structural diagram of a self - circulating geothermal power generation system based on underground flash evaporation in a U - shaped well shown in an embodiment of the present invention; Figure 2 It is a schematic diagram showing the atomizing valve facing downward shown in an embodiment of the present invention; Figure 3 Schematic diagram showing the atomizing valve facing upward according to an embodiment of the present invention.

[0016] Reference numerals: 1, docking well; 2, flash evaporation cavity; 3, vertical production well; 4, power generation terminal; 5, steam pipeline; 6, condensation pipeline; 101, injection section; 102, horizontal section; 103, high thermal conductivity cement layer; 104, water injection inlet; 105, multi-branch section; 201, connecting pipeline; 202, atomizing valve; 203, top outlet; 301, heat insulation layer; 302, steam outlet. Detailed implementation manners

[0017] The technical solutions of the present invention patent will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention patent, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention patent without creative efforts belong to the scope of protection of the present invention patent.

[0018] In the description of the present invention patent, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention patent and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention patent. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0019] In the description of the present invention patent, it should be noted that unless otherwise clearly defined and limited, the terms "installation", "connection", "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention patent can be understood according to specific situations.

[0020] In addition, the technical features involved in different embodiments of the present invention patent described below can be combined with each other as long as they do not conflict with each other.

[0021] Please refer to Figure 1, the present invention discloses a pump - less closed - loop geothermal power generation system based on U - shaped well underground flash evaporation. The power generation system includes a docking well 1, a flash evaporation cavity 2, a vertical production well 3, and a power generation terminal 4. The outer side of the docking well 1 is wrapped with a high - thermal - conductivity cement layer 103. One end of the docking well 1 is a water injection inlet 104, and the other end is connected with a multi - branch section 105. The multi - branch section 105 is connected to the flash evaporation cavity 2. The upper end of the flash evaporation cavity 2 is connected to the lower end of the vertical production well 3. The steam outlet 302 at the upper end of the vertical production well 3 is connected to the power generation terminal 4 through a first pipeline 5. The water injection inlet 104 is connected to the power generation terminal 4 through a second pipeline 6.

[0022] Specifically, the docking well 1 is divided into an injection section 101 and a horizontal section 102.

[0023] Specifically, the outer side of the vertical production well 3 is wrapped with a heat insulation layer 301.

[0024] Specifically, the power generation terminal 4 can be equipped with a steam turbine or a thermoelectric generation module. Both of these power generation methods can directly use high - temperature steam for power generation. When using a steam turbine for power generation, it is necessary to adapt to the steam pressure at the outlet to ensure the power generation efficiency. Although the efficiency of using a thermoelectric generation module decreases, its modular production results in lower investment and operation and maintenance costs, and it can be built underground with a small footprint.

[0025] For the internal structure of the flash evaporation cavity, please refer to Figure 2 , whose spatial size and internal shape are determined by the specific flash evaporation scheme. This structure includes a connecting pipeline 201, an atomizing valve 202, and a top outlet 203. The connecting pipeline 201 can be connected to multiple groups of horizontal sections. The other end of the connecting pipeline 201 is connected to the atomizing valve 202.

[0026] Specifically, the generated steam will enter the lower end of the vertical production well 3 through the top outlet 203.

[0027] Specifically, the atomizing valve 202 can face downward (as shown in Figure 2 ) or upward (as shown in Figure 3 ).

[0028] Specifically, around the flash evaporation cavity, supercritical carbon dioxide can be used to create a heat storage layer to enhance the heat exchange capacity and improve the flash evaporation efficiency.

[0029] In use, low-temperature water enters through the water injection inlet 104. As the depth gradually increases to the kilometer level, the thermal energy of the deep geothermal energy is conducted through the high thermal conductivity cement layer into the injection section 101 to heat the water therein. The hot water is continuously heated in the horizontal section 102. The hot water enters the atomizing valve 202 through the connecting pipe 201 and is then sprayed by the atomizing valve 202 in the form of small liquid particles into the flash chamber 2. When the liquid droplets enter the high-temperature chamber or contact the high-temperature chamber wall of the flash chamber 2, they will instantly vaporize to form steam, and the low-pressure environment inside the chamber will ensure the efficiency of the vaporization phase change. The outlet 203 at the top of the chamber is connected to the vertical production well 3. The well wall above the vertical production well 3 is an insulating layer 301 with low thermal conductivity to ensure that the transported steam is in a high-temperature state. Since the pressure at the bottom of the vertical well is higher than that at the top, the high-temperature steam will automatically migrate to the top steam outlet 302. The steam at the outlet is transported by the steam pipe 5 to the power generation terminal 4. After power generation, the steam is condensed to form low-temperature water and returns to the water injection inlet 104 through the condensate pipe 6 to form a cycle.

[0030] In summary, compared with the open-loop hydrothermal system, this application has no water loss, can reuse water resources, protect the environment, does not require fracturing for reservoir construction, avoids inducing earthquakes, and saves costs. Compared with the traditional closed-loop hydrothermal system, this patent can achieve the automatic migration of steam carrying thermal energy, does not require large equipment such as high-pressure pumps, turbines, generators, and condensers, and reduces investment and operation and maintenance costs. Compared with the systems based on working fluids such as organic substances and ammonia, this patent has high safety, does not require long-term monitoring and maintenance, and has little impact on the environment. The power generation terminal of this patent can select a steam turbine or a thermoelectric generation module. The steam turbine can directly use steam for power generation with higher efficiency; the thermoelectric generation module can be produced modularly, has low costs, can be built underground, and occupies a small area.

[0031] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0032] The above-described embodiments only represent several implementation manners of this invention patent. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of this invention patent, several modifications and improvements can still be made, and these all belong to the protection scope of this invention patent. Therefore, the protection scope of this invention patent should be subject to the appended claims.

Claims

1. A self-circulating geothermal power generation system based on U-shaped well underground flash evaporation, characterized in that: The power generation system includes a docking well, a flash chamber, a vertical production well, and a power generation terminal; the outside of the docking well casing is a high thermal conductivity cement layer, one end of the docking well is a water injection inlet, and the other end is connected to a conduit, the other end of the conduit is provided with an atomizing valve and is arranged in the flash chamber; the upper end of the flash chamber is connected to the lower end of the vertical production well, and the upper end steam outlet of the vertical production well is connected to the power generation terminal through a first pipeline; the water injection inlet is connected to the power generation terminal through a second pipeline.

2. A self-circulating geothermal power generation system based on U-shaped well underground flash evaporation as claimed in claim 1, characterized in that: The docking well is divided into an injection section and a horizontal section.

3. A self-circulating geothermal power generation system based on U-shaped well underground flash evaporation as claimed in claim 1, characterized in that: There is a heat insulation layer between the vertical production well casing and the formation.

4. A self-circulating geothermal power generation system based on U-shaped well underground flash evaporation as claimed in claim 1, characterized in that: The power generation terminal may be equipped with a turbine or a temperature difference power generation module.

5. A self-circulating geothermal power generation system based on U-shaped well underground flash evaporation as claimed in claim 1, characterized in that: The vertical production well can be connected to several docking wells. Water heated by the formation in the docking well can enter the flash chamber at the bottom of the vertical well through a valve. The horizontal section of the docking well can be designed as a multi-branch section.

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