Super-long gravity assisted heat pipe direct-drive geothermal power generation system adopting suspension steam turbine

Abstract

The invention discloses a super-long gravity heat pipe direct-drive geothermal power generation system adopting a suspension type steam turbine. The super-long gravity heat pipe direct-drive geothermal power generation system comprises a super-long gravity heat pipe, the suspension type steam turbine, a power generator, a condenser and a booster pump. The super-long gravity heat pipe is buried in a selected geothermal well, the bottom of the super-long gravity heat pipe goes deep into an underground heat reservoir, a working medium outlet of the super-long gravity heat pipe is connected with a steam inlet of the suspension type steam turbine, and the suspension type steam turbine is connected with the generator through a mechanical transmission structure. A steam outlet of the suspension type steam turbine is connected with the condenser, and the condenser is connected with a working medium reinjection opening of the super-long gravity heat pipe through the booster pump. The steam turbine is vertically installed, the gravity of a steam turbine rotating part is counteracted through the pressure difference between an inlet and an outlet of the steam turbine, and therefore pneumatic suspension of the steam turbine rotating part is achieved; the rotating part of the steam turbine adopts the suspension design, the frictional resistance is extremely low, lubricating oil is not needed or only little lubricating oil is needed for lubrication, the situation that the lubricating oil is mixed into a working medium is avoided, and the working efficiency of the steam turbine is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of geothermal power generation, and particularly to an ultra-long gravity heat pipe direct-drive geothermal power generation system using a suspended steam turbine. Background Art

[0002] To achieve carbon peak and carbon neutrality and ensure national energy security, the best way is to develop green and renewable energy. Geothermal energy is widely distributed, has huge reserves, stable output, is not easily affected by the environment, and has the potential to become a base load. However, geothermal resources often have relatively low temperatures, and the traditional exploitation and utilization technologies have very low power generation efficiency and poor economic benefits, which limit their development; the efficiency of the existing ultra-long steam heat pipe direct-drive geothermal power generation system still needs to be further improved. Summary of the Invention

[0003] The purpose of the present invention is to overcome the deficiencies of the above-mentioned prior art and provide an ultra-long gravity heat pipe direct-drive geothermal power generation system using a suspended steam turbine.

[0004] The present invention is realized through the following technical solutions: an ultra-long gravity heat pipe direct-drive geothermal power generation system using a suspended steam turbine, comprising an ultra-long gravity heat pipe, a suspended steam turbine, a generator, a condenser, and a booster pump; the ultra-long gravity heat pipe is buried in a selected geothermal well, the bottom of the ultra-long gravity heat pipe penetrates into the underground heat reservoir, the working medium outlet of the ultra-long gravity heat pipe is connected to the steam inlet of the suspended steam turbine, and the suspended steam turbine is connected to the generator through a mechanical transmission structure; the steam outlet of the suspended steam turbine is connected to the condenser, and the condenser is connected to the working medium reinjection port of the ultra-long gravity heat pipe through the booster pump.

[0005] This system selects a geothermal well according to power demand and resource distribution and buries an ultra-long gravity heat pipe. The overall structure of the system is similar to the Rankine cycle, and the heat pipe plays the role of a boiler in it, which can be used for the development of hydrothermal geothermal sources and also for the development of hot dry rock geothermal resources.

[0006] The working medium in the ultra-long gravity heat pipe direct-drive geothermal power generation system is selected as ammonia or water, and the same batch of working medium is used for underground heat extraction and ground power generation in the system. In this system, the working medium is mainly screened according to thermodynamic adaptability, generally ammonia or water, and other suitable working media can also be used.

[0007] There are two cases for the suspended steam turbine. In the first case, the rotating components of the suspended steam turbine are arranged in a pneumatic suspension manner, and the suspended steam turbine is arranged vertically with respect to the ground. The suspension of the rotating components results in extremely low frictional resistance of the rotating components, and little or no lubricating oil or grease is required for lubrication. When it is arranged perpendicular to the ground, the pressure difference between the steam inlet and the steam outlet of the steam turbine can be utilized to offset the gravity of the rotating components of the steam turbine, thereby achieving the pneumatic suspension of the rotating components of the steam turbine.

[0008] The gravity of the rotating components of the suspended steam turbine is equal to the magnitude of the steam force difference in and out of the suspended steam turbine. The gravity of the rotating components is equal to the magnitude of the steam force difference in and out of it, so as to achieve suspension during operation.

[0009] The second case of the suspended steam turbine is a magnetic levitation steam turbine, and the rotating components of the suspended steam turbine are arranged in a magnetic drive suspension manner. When the pneumatic suspension arrangement cannot meet the actual application requirements, a conventional arrangement can also be adopted. However, when a magnetic levitation steam turbine is required in the conventional arrangement, the rotating components of the suspended steam turbine are suspended by magnetic drive.

[0010] Compared with the prior art, the advantages of the present invention are as follows: The present system proposes a combination of a suspended steam turbine and an ultra-long gravity heat pipe steam direct drive power generation system. By utilizing the extremely low frictional resistance of the rotating components of the steam turbine in the suspended state, the efficiency of the steam turbine is improved, thereby increasing the power generation of the system and ultimately enhancing the market competitiveness of the technology. In the first case, the pressure difference between the inlet and outlet of the steam turbine is utilized to offset the gravity of the rotating components of the steam turbine, thereby achieving the pneumatic suspension of the rotating components of the steam turbine; no additional component support is required, and the operability is strong. Moreover, the situation of excessive axial force of the steam turbine caused by the pressure between the inlet and outlet of the steam turbine is avoided. In the case where the first case is not satisfied, magnetic drive can also be used to suspend the rotating components of the engine. In the present system, due to the suspended design of the rotating components of the steam turbine, the frictional resistance of the rotating components is extremely low, and little or no lubricating oil or grease is required for lubrication, which can greatly avoid the occurrence of adverse situations and the situation of lubricating oil mixing into the working medium. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a schematic structural diagram of an embodiment of the present invention.

[0012] The meanings of the reference numerals in the drawings: 1. Ultra-long gravity heat pipe; 2. Suspended steam turbine; 3. Generator; 4. Condenser; 5. Booster pump. DETAILED DESCRIPTION OF THE INVENTION

[0013] The following further elaborates on the content of the present invention in detail in conjunction with the drawings and specific embodiments.

[0014] Embodiment

[0015] The ultra-long gravity heat pipe technology is a new type of (medium)-deep geothermal energy single-well exploitation technology proposed and developed by Chinese scientific researchers. This technology only extracts heat without taking water, can be self-driven without pump power, and has a greater single-well heat extraction capacity compared to other traditional single-well heat extraction technologies without taking water. The ultra-long gravity heat pipe 1 produces steam, which can directly drive a steam turbine to generate electricity. It has a simpler structure and higher efficiency compared to other technologies and is very suitable for geothermal power generation. However, the current technology is still in the basic stage and urgently needs further research and development.

[0016] ① The ultra-long gravity heat pipe technology produces steam, which can directly drive a steam turbine without heat exchange or flashing. Therefore, under the same heat production conditions, the steam direct drive power generation system of the ultra-long gravity heat pipe 1 has higher power generation efficiency and thus better economic performance. However, the efficiency of the current steam direct drive power generation system of the ultra-long gravity heat pipe 1 still cannot meet the requirements and needs to be further improved.

[0017] ② As a low-enthalpy heat source heat extraction technology, the ultra-long gravity heat pipe produces a relatively small mass flow rate of steam. The steam turbine adapted to it has the remarkable characteristics of small volume and high speed. This characteristic causes a relatively large axial friction in the steam turbine, which not only reduces the power generation efficiency but also requires a lot of lubricating oil. However, some lubricating oil will mix into the heat pipe working medium and enter the entire system cycle. At this time, it will not only cause additional loss of lubricating oil but also cause the lubricating oil to deposit in the heat pipe without evaporation, thus affecting the heat extraction performance of the heat pipe.

[0018] ③ If the rotating components of the steam turbine can be suspended, it will greatly avoid frictional resistance, thereby improving the power generation efficiency; and during this process, the use of lubricating oil can be reduced or even eliminated, avoiding the problem of lubricating oil mixing into the working medium of the ultra-long gravity heat pipe 1.

[0019] ④ The inlet pressure of the steam turbine is higher than its outlet pressure. Therefore, the steam will form an axial thrust between the inlet and outlet of the steam turbine. When the steam turbine is arranged perpendicular to the ground, under specific circumstances, its axial thrust will cancel out the gravity of the rotating components of the steam turbine, making it possible for the rotating components of the steam turbine to achieve suspension.

[0020] ⑤ Currently, the magnetic levitation steam turbine has been developed a lot. It uses magnetic force to suspend the rotating components of the steam turbine, thereby greatly reducing the friction of the axial contact parts.

[0021] Refer to Figure 1, it is a direct geothermal power generation system using a suspended steam turbine 2 and an ultra-long gravity heat pipe 1, including an ultra-long gravity heat pipe 1, a suspended steam turbine 2, a generator 3, a condenser 4 and a booster pump 5; the ultra-long gravity heat pipe 1 is buried in a selected geothermal well, the bottom of the ultra-long gravity heat pipe 1 extends deep into the underground heat reservoir, the working fluid outlet of the ultra-long gravity heat pipe 1 is connected to the steam inlet of the suspended steam turbine 2, and the suspended steam turbine 2 is connected to the generator 3 through a mechanical transmission structure; the steam outlet of the suspended steam turbine 2 is connected to the condenser 4, and the condenser 4 is connected to the working fluid reinjection port of the ultra-long gravity heat pipe 1 through the booster pump 5.

[0022] This system selects a geothermal well according to power demand and resource distribution and buries the ultra-long gravity heat pipe 1. The overall structure of the system is similar to the Rankine cycle. The heat pipe acts as a boiler in it and can be used for the development of hydrothermal geothermal sources as well as for the development of hot dry rock geothermal resources.

[0023] The working fluid selected in the direct geothermal power generation system of the ultra-long gravity heat pipe 1 is ammonia or water, and the same batch of working fluid is used for underground heat extraction and ground power generation in the system. In this system, the working fluid is mainly selected based on thermodynamic adaptability, generally ammonia or water, and other suitable working fluids can also be used.

[0024] The rotating components of the suspended steam turbine 2 are arranged in a pneumatic suspension manner, and the axis of the suspended steam turbine 2 is perpendicular to the ground. The suspension of the rotating components results in extremely low frictional resistance of the rotating components, requiring no or only very little lubricating oil or grease for lubrication, and with higher efficiency; when it is arranged perpendicular to the ground (vertically installed steam turbine), the pressure difference between the steam inlet and the steam outlet of the steam turbine can be used to offset the gravity of the rotating components of the steam turbine, thereby realizing the pneumatic suspension of the rotating components of the steam turbine.

[0025] The gravity of the rotating components of the suspended steam turbine 2 is equal to the difference in the steam forces entering and leaving the suspended steam turbine 2. The gravity of the rotating components is equal to the difference in the steam forces entering and leaving it, so as to achieve suspension during operation.

[0026] The suspended steam turbine 2 adopts a magnetic suspension steam turbine 2, and the rotating components of the suspended steam turbine 2 are arranged in a magnetic drive suspension manner. When the pneumatic suspension arrangement of the rotating components cannot meet the actual application requirements, a conventional arrangement can also be adopted. However, when a magnetic suspension steam turbine 2 is required in the conventional arrangement, the rotating components of the suspended steam turbine 2 are suspended by magnetic drive.

[0027] The working principle of this embodiment:

[0028] The ultra-long gravity heat pipe 1 is used to extract (medium) deep geothermal energy. During the operation of the system, the working fluid absorbs heat and evaporates into saturated steam at the bottom of the ultra-long gravity heat pipe 1, and then floats upward by itself under the action of the saturated pressure difference and is output from the working fluid outlet of the ultra-long gravity heat pipe 1; the produced saturated steam enters the suspended steam turbine 2 to expand and do work, and the steam turbine drives the generator 3 to produce electric energy; then the working fluid flows out of the steam turbine and condenses into a liquid state in the condenser 4, and after being boosted to a pressure equal to or higher than the pressure at the working fluid outlet of the ultra-long gravity heat pipe 1 under the action of the booster pump 5, it is reinjected into the ultra-long gravity heat pipe 1 to start the next cycle. The whole system has a simple structure and strong operability.

[0029] Since the steam turbine used in the steam direct-driven geothermal power generation system of the ultra-long gravity heat pipe 1 has the characteristic of high rotational speed, the frictional influence caused by rotation is more significant; and because this steam turbine also has the characteristic of small volume, in this embodiment, it is considered to be installed in a way that its axis is perpendicular to the ground, so as to utilize the force difference between the working fluid inlet and outlet of the steam turbine to offset the gravity of the rotating components of the steam turbine, so as to achieve suspension and reduce friction. In order to increase the scope of adaptation, in the case where the above situation is not met, this embodiment also proposes an alternative solution of using a magnetic levitation steam turbine 2 to increase the efficiency of the steam turbine. In this solution, the conventional layout plus the magnetic levitation steam turbine 2 are used to reduce the frictional resistance.

[0030] In a general solution, when the system starts, the pressure at the inlet of the steam turbine is higher than the pressure at the outlet, so under the action of the pressure difference of the working fluid, an axial force will be generated on the rotating components of the steam turbine. Under suitable circumstances, the magnitude of this force is equal to the gravity of the rotating components of the steam turbine. At this time, if the steam turbine is arranged as Figure 1 shown, the rotating components of the steam turbine will achieve pneumatic suspension. And when the layout is not met, a magnetic levitation steam turbine 2 is used. At this time, the rotating components of the steam turbine are suspended under the action of magnetic force and still meet the design requirements.

[0031] The above detailed description is a specific description of the feasible embodiments of the present invention. This embodiment is not intended to limit the patent scope of the present invention. Any equivalent implementation or modification without departing from the present invention should be included in the patent scope of this case.

Claims

1. An ultra-long gravity heat pipe direct-driven geothermal power generation system using a suspended steam turbine, characterized in that: it includes an ultra-long gravity heat pipe, a suspended steam turbine, a generator, a condenser and a booster pump; the ultra-long gravity heat pipe is buried in a selected geothermal well, the bottom of the ultra-long gravity heat pipe extends deep into the underground heat reservoir, the working fluid outlet of the ultra-long gravity heat pipe is connected to the steam inlet of the suspended steam turbine, and the suspended steam turbine is connected to the generator through a mechanical transmission structure; the steam outlet of the suspended steam turbine is connected to the condenser, and the condenser is connected to the working fluid reinjection port of the ultra-long gravity heat pipe through the booster pump.

2. The ultra-long gravity heat pipe direct-driven geothermal power generation system using a suspended steam turbine according to claim 1, characterized in that: the working fluid in the ultra-long gravity heat pipe direct-driven geothermal power generation system is selected from ammonia or water, and the same batch of working fluid is used for underground heat extraction and ground power generation in the system.

3. The ultra-long gravity heat pipe direct-driven geothermal power generation system using a suspended steam turbine according to claim 1, characterized in that: the rotating components of the suspended steam turbine are arranged in a pneumatic suspension manner, the axis of the suspended steam turbine is perpendicular to the ground, and the suspended steam turbine is located above the ultra-long gravity heat pipe.

4. The ultra-long gravity heat pipe direct-driven geothermal power generation system using a suspended steam turbine according to claim 1, characterized in that: the gravity of the rotating components of the suspended steam turbine is equal to the difference in steam force at the inlet and outlet in the suspended steam turbine.

5. The ultra-long gravity heat pipe direct-driven geothermal power generation system using a suspended steam turbine according to claim 1, characterized in that: the suspended steam turbine adopts a magnetic levitation steam turbine, and the rotating components of the suspended steam turbine are arranged in a magnetic force-driven suspension manner.

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