WO2014079054A1

WO2014079054A1 - High temperature geothermal power generation device based on heat pipe

Info

Publication number: WO2014079054A1
Application number: PCT/CN2012/085249
Authority: WO
Inventors: 路明
Original assignee: Lu Ming
Priority date: 2012-11-26
Filing date: 2012-11-26
Publication date: 2014-05-30

Abstract

A high temperature geothermal power generation device based on a heat pipe relates to the field of heat transfer devices, is a device utilizing liquid-steam phase change to continuously supply high temperature geothermal energy to generate power, and comprises an evaporator (1), a condenser (2), a steam turbine power generation set (7), an electrically controlled air throttle (18), a steam pipe (19) having the electrically controlled air throttle, a steam flow connecting pipe (20), an exhaust valve (21), a main return pipe (22) having an electrically controlled flow throttle(23), an inner return pipe (24) capable of generating a swirling flow, a steam turbine rotor (27), a protective sleeve (28), and a cooling system (29).

Description

High-temperature geothermal power generation device based on heat pipe

Technical field

The present invention relates to the field of geothermal power generation equipment, and is a device for high-temperature geothermal power generation based on a heat pipe, and more particularly to a device for continuously transmitting high-temperature geothermal heat to the ground and generating electricity by utilizing a gas-liquid phase change in a heat pipe. Background technique

Geothermal power generation is a new type of power generation technology that uses underground hot water or steam as a power source. It involves geology, geophysics, chemistry, drilling, materials science, power generation engineering and many other modern science and technology. Its basic principle is similar to that of thermal power generation. According to the principle of energy conversion, the geothermal energy is first converted into mechanical energy, and then the mechanical energy is converted into electrical energy. Most of the current geothermal water or dry steam used for power generation is higher than 20CTC, which is high temperature geothermal. High-temperature geothermal power generation is a highly efficient form of thermoelectric conversion. For underground dry steam power generation, dry steam needs to be taken out of the ground and then steam is fed into the turbine for work. The steam entering the turbine first needs to pass through a purification device to separate the solid impurities therein. For underground hot water power generation, also known as dual-cycle geothermal power generation, it is necessary to use underground hot water to heat a certain low-boiling working fluid (such as ethyl chloride, Freon) to generate steam and then enter the steam turbine.

Figure 1 is a schematic diagram of a dual-cycle geothermal power generation system. The figure shows that the high temperature geothermal water (4) in the geothermal well (3) is extracted by the geothermal pump (5) and sent to the evaporator (1) to provide heat. At the other end, the low boiling point working fluid (6) is circulated to the evaporator (1) by the working fluid pump (8). In the evaporator (1), the working fluid is vaporized by heat, becomes high-pressure steam, and enters the steam turbine generator set (7) to perform work and power generation. After that, it passes through the condenser (1) and becomes a liquid working substance again. The high-temperature hot water (4) flows out of the evaporator (1) after heating the working medium, and is discharged into the ground through the recirculation system (9).

In the above geothermal power generation system, since the low-boiling working fluid has poor heat conductivity, a large metal heat exchange area is required, resulting in a large volume of the evaporator and the condenser, and high manufacturing cost. The low boiling point working fluid is unstable, flammable, toxic, prone to leakage and pollute the environment. On the other hand, in order to prevent groundwater level falling and land subsidence, while mining geothermal resources, it is necessary to establish a water source recharge system in places where geothermal water or dry steam is extracted, so that the current geothermal utilization cost has increased. In addition, underground hot water and steam often contain a large amount of corrosive substances and scale components. Such as hydrogen sulfide, carbon dioxide, etc., they are inside the pipes and ancillary equipment, causing them to be strongly corroded. The scale generated by silicon, calcium, magnesium and the like often occurs as a compound such as calcium carbonate or silica. These phenomena all have an adverse impact on geothermal power generation.

In short, the high-temperature geothermal power generation equipment currently used has disadvantages such as high construction and maintenance costs, low thermal efficiency of working fluids, and poor reliability. In order to overcome the above drawbacks and utilize geothermal resources more efficiently, it is necessary to adopt a device and method that is simpler, more practical, cheap, efficient, reliable and durable. Summary of the invention

In order to achieve the above objectives, the conventional scheme of pumping high-temperature hot water to the ground is first excluded, but the evaporator is placed underground, the working medium is injected into the evaporator, and the evaporator is directly heated by high-temperature hot water or steam. The working fluid is directly vaporized into steam, which is sent to the steam turbine of the surface by the adiabatic pipeline for work, and then becomes a liquid working medium through the condenser, and then transported back to the underground evaporator to continue the cycle. The principle of using a gas-liquid continuous phase change process to transport high temperature geothermal energy is the working principle of a heat pipe. This heat transfer method has many advantages. First, its heat transfer efficiency is high, usually several times or even several times that of solid metal, so that heat can be transferred to a farther place with less heat loss. Further, the heat flux density can be changed by changing the heat transfer area. For example, heat is input with a smaller heating area, and heat is output with a larger cooling area, and vice versa. Engineering, using the working principle of the heat pipe, can be designed as a solution to extract high temperature geothermal, easy to use. Figure 2 shows a scheme for extracting high-temperature geothermal heat using the heat transfer principle of a heat pipe. As shown in the figure, the evaporator (1) is in the low-end, that is, the geothermal well (3), is the underground high-temperature geothermal area, the condenser (2) is at the high end, that is, on the ground, with an insulated steam pipe in the middle (12) ) is connected to the insulated liquid return pipe (15). When the heat source (11) is applied to the evaporator (1), the input heat heats, vaporizes, and evaporates the liquid working medium in the evaporator (1), and the working fluid becomes a high-temperature, high-pressure steam stream (13), and Move to the upper side of the low temperature and low pressure, that is, the direction of the condenser (2). The middle insulation line means that the heat output and input in this section are negligible. The condenser (2) releases heat on the ground (16), which causes the working fluid vapor to release latent heat and condense into a liquid. Since the condenser (2) forms a liquid head at the high end, the liquid medium becomes a liquid reflux (14), which is automatically returned to the evaporator (1) through the liquid return line (15). The heat transfer is realized by the phase change of the working medium at the cold and hot ends. If the added heat and the released heat remain constant, the phase change process will continue and reach a steady state. If the high-temperature geothermal heat is extracted by the working principle, method and corresponding device in Fig. 2, the traditional geothermal pump (5) and recharge system (9) in Fig. 1 are no longer needed, so that the overall scheme of high-temperature geothermal power generation is simple. At the same time, the geothermal water or steam is prevented from entering the pipeline and other equipment, preventing internal corrosion and scaling of the equipment, and reducing maintenance costs.

The use of such a device to extract high temperature geothermal resources faces an urgent problem to be solved. Still taking Figure 3 as an example, the evaporator (1) should be placed underground and the volume should be minimized. In order to ensure the amount of heat transfer, it is necessary to use a low-boiling working medium that excludes the use of conventional geothermal power, and a working fluid having a high heat transfer coefficient, such as water, methanol, or the like. Such a liquid working medium at normal temperature, in the case of a high temperature environment, forms a vapor film on the inner wall surface of the evaporator (1), and a large amount of vapor bubbles are generated on the wall surface, so that the liquid on the wall surface leaves the wall surface. Since the heat transfer coefficient of the steam bubbles is much lower than that of the liquid, the heat transfer amount of the wall surface is lowered. Therefore, when many heat pipes are used in a high temperature environment, the heat transfer efficiency is not high. Further, the upwardly moving vapor stream (13) in the evaporator (1) is opposite to the direction of movement of the liquid return (14) coming back from the condenser (2), and shear forces are generated from each other. Steam may take a portion of the liquid entrainment. The higher the working environment temperature, the greater the vapor pressure, and the greater the shearing force with the liquid, the easier it is to take away the liquid working fluid. If there is too much liquid entrained, there is not enough liquid in the evaporator (1) to return, evaporate The device α ) may be burned out, causing damage to components.

SUMMARY OF THE INVENTION An object of the present invention is to provide a device and method which is simple, practical, inexpensive, efficient, reliable and durable, and utilizes the working principle of a heat pipe to extract high temperature geothermal heat (including high temperature geothermal water and high temperature geothermal dry steam) for power generation. Fig. 3 is a schematic view showing the operation of a high-temperature geothermal power generation apparatus based on a heat pipe according to the present invention. The figure shows: The device comprises an evaporator (1), a condenser (2), a turbine generator set (7), an electronically controlled throttle valve (18), a steam tube with an electrically controlled throttle valve (19) a steam flow connection pipe (20), an exhaust valve (21), a main return pipe (22) with an electrically controlled throttle valve, an electronically controlled throttle valve (23), an internal recirculation capable of generating a swirling flow Tube (24), a turbine rotor (27) and other components. In operation, the evaporator (1) is in the lowermost high temperature geothermal zone, the condenser (2) and the generator set (7) are above the ground, and the height difference is determined according to the application, and the two are connected by the insulated pipe. The evaporator (1) is cylindrical in appearance or a metal tube of inverted truncated cone shape.

The evaporator (1) has a steam outlet and a liquid inlet at the upper end;

The steam turbine unit (7) has a steam inlet and a steam outlet;

The condenser (2) has a steam inlet and a liquid outlet;

A steam pipe (19) with an electrically controlled throttle connects the steam outlet of the evaporator (1) to the steam inlet of the turbine (7), allowing steam to enter the turbine (7). Electronically controlled throttle valve (18), which regulates gas flow;

The steam outlet of the steam turbine unit (7) is connected to the steam inlet of the condenser (2) through a steam flow connecting pipe (20), and the steam enters the condenser after working in the steam turbine (2);

The upper exhaust valve (21) of the condenser (2) is designed to prevent gas blockage in the condenser (2);

A main return pipe (22) with an electrically controlled throttle valve is connected to the liquid outlet of the condenser (2), and the other end is connected to one end of an internal return pipe (24) capable of generating a swirl; electronically controlled throttling The valve (23) can control the flow of steam entering the condenser to control the amount of heat transfer;

The other end of the inner return pipe (24) penetrates from the liquid inlet of the evaporator (1) to the bottom of the inner chamber of the evaporator (1).

The evaporator (1) has a cylindrical shape or an inverted truncated cone shape;

The liquid working medium enters the evaporator (1) from the condenser (2) through the main return pipe (22) and the inner return pipe (24). Inserting the inner return pipe (24) directly into the lower end of the evaporator (1) means that the liquid working medium is directly guided into the evaporator (1), avoiding relative movement with a large amount of steam to generate shearing force, avoiding liquid The occurrence of entrainment occurs to prevent drying in the evaporator (1). The outer surfaces of all pipes are covered with insulation.

The inner surface of the inner return pipe (24) is engraved with a plurality of double lines (25), and the outer surface has a thread-shaped groove (26). Since the height of the condenser (2) is higher than that of the evaporator (1), there is a liquid head, and the liquid medium flows downward in the inner return pipe (24). Due to the guiding action of the inner surface of the double line (25), the liquid will rotate. The liquid having a certain moment of inertia flows out of the inner return pipe (24) and enters the evaporator to form the direction of rotation (27) of the two-phase flow in the evaporator shown in the drawing. at this time, The liquid working fluid is gradually vaporized in the evaporator (1) due to the evaporation caused by the high temperature of the outside, and becomes a gas-liquid two-phase flow. As the pressure in the evaporator (1) rises, the two-phase flow begins to move upwards, still maintaining the centrifugal force of rotation. The threaded groove (26) on the outer surface of the inner return pipe (24) coincides with the direction of the rifling (25), which directs the gas-liquid two-phase flow to move in a rotationally upward manner. Figure 4 is a partial detailed view showing the structural relationship between the inner return pipe and the evaporator, showing the detailed structure of the inner return pipe (24) and the bottom of the evaporator (1) in Figure 3. If it is in a high temperature environment at this time, a vapor film is generated on the inner wall of the evaporator (1), and a large amount of steam bubbles adhere to the wall surface of the evaporator (1), which reduces the heat transfer efficiency of the wall surface. However, in the gas-liquid two-phase flow, since the density of the liquid particles is large relative to the vapor, the liquid particles fly toward the wall surface of the evaporator (1) due to the centrifugal force of the rotation. The flying liquid particles will crush the vapor film, eliminate bubbles, and form a liquid film in the local area, so that the wall heat loss loss can be recovered.

The innovation of the invention: In the method, the evaporator is directly placed in the underground high-temperature geothermal area, and the working medium with high heat transfer coefficient is used, and the working principle of the heat pipe is used to directly extract high-temperature geothermal heat to the ground; A swirling inner return conduit is created to impart a rotational motion to the two-phase flow medium within the chamber of the evaporator and cooperate with the geometry of the evaporator to eliminate the vapor film. This inner return tube is inserted into the bottom of the evaporator chamber to avoid liquid entrainment. These features make geothermal power generation equipment work efficiently, safely and reliably at higher temperatures. DRAWINGS

Figure 1 is a schematic diagram of a dual-cycle geothermal power generation system. In the figure, 1 evaporator, 2 condenser, 3 geothermal well, 4 geothermal water, 5 geothermal pump, 6 low boiling point working fluid, 7 steam turbine unit, 8 working fluid pump, 9 recharge system, 10 electric power output.

Figure 2 is a plan diagram for extracting high temperature geothermal heat using the heat transfer principle of a heat pipe. In the figure, 1 evaporator, 2 condensers, 3 geothermal wells, 11 heat sources, 12 steam pipes, 13 steam streams, 14 liquid reflux, 15 liquid return pipes, 16 exotherms.

Figure 3 is a schematic diagram of the operation of a high temperature geothermal power generation device based on a heat pipe. In the figure, 1 evaporator, 2 condenser, 7 steam turbine unit, 10 power output, 13 steam flow, 14 liquid reflux, 17 two-phase flow rotation direction in evaporator, 18 electronically controlled throttle valve, 19 with electronically controlled throttle valve Steam pipe, 20 steam flow connection pipe, 21 exhaust valve, 22 main return pipe with electronically controlled throttle valve, 23 electronically controlled throttle valve, 24 internal swirling pipe capable of generating swirl, 25 inner return pipe inner wall Come to the double line, the thread on the outer wall of the return pipe in 26, 27 turbine rotor.

Figure 4 is a partial detailed view of the structure of the inner return pipe and the structural relationship with the evaporator. In the figure, 1 evaporator, 24 can generate a swirling inner return pipe, 25 a return line on the inner wall of the return pipe, and 26 a thread on the outer wall of the return pipe.

Figure 5 is a layout view of components of a heat pipe based high temperature geothermal power generation device in a specific embodiment. In the figure, 1 evaporator, 2 condenser, 7 steam turbine, 10 power output, 18 electronically controlled throttle, 19 steam tube with electric control throttle, 20 steam flow connection, 21 exhaust valve, 22 with electric control section The main return line of the flow valve, 23 electronically controlled throttle, 24 internal swirling tube capable of generating swirl, 27 turbine rotor, 28 protective sleeve, 29 cooling system. detailed description

The principles and structure of the invention are further illustrated in a specific embodiment. Figure 5 is a layout view of the components of a heat pipe based high temperature geothermal power generating apparatus in a specific embodiment.

A high-temperature geothermal power generation device based on a heat pipe, comprising an evaporator (1), a condenser (2), a steam turbine generator set (7), an electronically controlled throttle valve (18), and an electrically controlled throttle valve Steam pipe (19), a steam flow connection pipe (20), an exhaust valve (21), a main return pipe (22) with an electrically controlled throttle valve, an electronically controlled throttle valve (23), an energy An internal return pipe (24) that produces a swirl, a turbine rotor (27), a protective sleeve (28), and a cooling system (29).

Water is used as the working medium, the heat transfer coefficient is large, the resources are abundant, the cost is low, and no toxic substances are produced. Because the high temperature resistant stainless steel material does not react chemically with water, does not oxidize, deforms, and has a high heat transfer coefficient, therefore, the condenser (1), the evaporator (2) and various connecting lines (19, 20, 22) They are made of high temperature resistant stainless steel.

In operation, the evaporator (1) is in the lowermost high temperature geothermal zone, where the high temperature geothermal resource is at a temperature of 200. C exists in the form of high temperature hot water and dry steam, and the height difference from the ground is about 2000m to 3000m. The evaporator (1) has a steam outlet and a liquid inlet at the upper end. The turbine (7) and condenser (2) are on the ground. ;

The steam turbine unit (7) has a steam inlet and a steam outlet; the condenser (2) has a steam inlet and a liquid outlet; a steam tube with an electrically controlled throttle valve (19) exports the steam outlet of the evaporator (1) It is connected to the steam inlet of the steam turbine unit (7) so that steam enters the steam turbine unit (7) to push the turbine rotor (27) to work. An electric control throttle (18) is installed on the steam pipe (19) to regulate the gas flow; the steam outlet of the steam turbine (7) is connected to the steam inlet of the condenser (2), and the steam enters the condenser after working in the turbine (7). (2); The upper exhaust valve (21) of the condenser (2) is designed to prevent gas blockage in the condenser (2); a main return pipe (22) with an electrically controlled throttle valve is connected to the end The liquid outlet of the condenser (2) is connected to one end of an internal return pipe (24) capable of generating a swirl; an electronically controlled throttle valve (23) is mounted on the main return pipe (22), and the condenser can be controlled to enter the condenser. (2) The flow of steam to control the amount of heat transfer; the other end of the inner return pipe (24) penetrates from the liquid inlet of the evaporator (1) to the bottom of the inner cavity of the evaporator (1). The liquid working fluid enters the evaporator (1) from the condenser (2) through the main return pipe (19) and the inner return pipe (24). The outer surfaces of all tubing (19, 20, 22) are covered with a thermal insulation material and placed in a corrosion-resistant, rigid protective sleeve (28).

Inserting the inner return pipe (24) directly into the lower end of the evaporator (1) means directing the water back into the evaporator (1), avoiding shear forces when moving against a large amount of steam, avoiding water being steamed The phenomenon of entrainment occurs to prevent drying in the evaporator (1). The inner return pipe (24) has an outer diameter of 0.3 m and an inner diameter of 0.2 m. The inner wall is engraved with six lines (25) with a depth of 0.01 m and a depth of 0.01 m on the outer wall and a thread groove of 0.01 m (26). The thread is twisted in the same direction as the double line. Since the height of the condenser (2) is much higher than that of the evaporator (1), there is a hydraulic head of 2000 m to 3000 m, and the water flows downward in the inner return pipe (24). Due to the guiding action of the inner double line (25), the water will rotate. Strong The inertia of water flows out of the inner return pipe (24) and enters the evaporator (1) to become a vapor-water two-phase flow. Due to the evaporation, the pressure in the evaporator increases and the two-phase flow begins to move upward. Since the viscosity of water and water vapor is small, the friction loss with the wall surface is small, and the moment of inertia loss is small, the two-phase flow still maintains a strong centrifugal force of rotation. The inner surface of the inner return pipe has a thread-shaped groove

(26) The gas-water two-phase flow will be guided to move in a rotationally upward manner. The structure of the inner return pipe (24) and the mode of fluid flow inside them are the same as those shown in Figs. 3 and 4.

In the vapor-water two-phase flow, since the density of the water droplet particles is larger than that of the steam, the liquid particles fly toward the inner wall surface of the evaporator due to the centrifugal force of rotation. At this time, if the evaporator is in a high temperature environment, a vapor film is generated on the inner wall of the evaporator to reduce the amount of heat transfer on the wall. The flying liquid particles will crush the vapor film and form a water film in the local area, so that the loss of wall heat transfer is restored. The inner chamber of the evaporator (1) has a cylindrical shape with an outer diameter of lm and a height of L 5m.

The high temperature and high pressure steam enters the steam turbine unit (7) for mechanical work, causing the turbine rotor (27) to rotate and the thermal energy to be converted into an electrical output. The principle of converting mechanical work in a steam turbine unit (7) into electrical energy is well known and will not be described here. The function of the condenser (2) is to convert steam into water by exotherm. Inside the condenser (2) is a cooling system with circulating water as the medium.

(29). The circulating water absorbs the heat of the steam, and the steam is cooled to become liquid water. Through the main return pipe (19) and the internal return pipe (24), the evaporator (1) is re-entered.

The invention provides a high-temperature geothermal power generation device based on a heat pipe, directly placing the evaporator into an underground high-temperature geothermal region, using water as a working medium, and improving the structural design of the component, and utilizing the continuous phase change of the working medium to heat the high-temperature geothermal Transfer to the ground for power generation. This method has high thermal efficiency due to the method of drawing geothermal heat by the heat pipe, and the overall heat engine efficiency of the power generating device is high, and the structure is simple and practical, inexpensive, efficient, reliable, and low in maintenance cost.

Instruction manual number list

1 evaporator

2 condenser

3 geothermal wells

4 geothermal water

5 geothermal pump

6 low boiling point working fluid

7 steam turbine unit

8 working fluid pump

9 recharge system

10 power output Heat source

steam pipes

Steam flow

Liquid reflux

Liquid pipeline

Heat release

Direction of rotation of two-phase flow in the evaporator Electronically controlled throttle

Steam pipe with electrically controlled throttle valve

Vent

Main return pipe with electrically controlled throttle valve Electronically controlled throttle valve

An internal return pipe capable of generating a swirling flow. The inner wire on the inner wall of the return pipe is threaded on the outer wall of the inner return pipe.

Protective sleeve

cooling system

Claims

WO 2014/079054 Claim PCT/CN2012/085249

A heat pipe based high temperature geothermal power generation device comprising an evaporator (1), a condenser (2), a turbine generator set (7), an electronically controlled throttle valve (18), a belt The steam tube (19) of the electronically controlled throttle valve, a steam flow connection tube (20), an exhaust valve (21), a main return line (22) with an electrically controlled throttle valve, and an electronically controlled throttle valve (23) An internal return pipe (24) capable of generating a swirl, a turbine rotor (27), a protective sleeve (28), and a cooling system (29);

The evaporator (1) has a steam outlet and a liquid inlet at the upper end;

The condenser (2) has a steam inlet and a liquid outlet;

The steam turbine unit (7) has a steam inlet and a steam outlet;

The evaporator (1) is located below the condenser (2);

The steam pipe (19) with an electrically controlled throttle valve connects the steam outlet of the evaporator (1) to the steam inlet of the steam turbine unit (7);

The steam flow connecting pipe (20) is connected to the steam outlet of the steam turbine unit (7) and the steam inlet of the condenser (2); the main return pipe (22) with the electrically controlled throttle valve is connected to the condensation The liquid outlet of the (2), the other end is connected to one end of an internal return pipe (24) capable of generating a swirl;

One end of the inner return pipe (24) capable of generating a swirling flow is connected to the main return pipe (22), and the other end penetrates to the bottom of the inner cavity of the evaporator (1);

The turbine rotor (27) is located inside the turbine generator set (7).

2. A device for high temperature geothermal power generation based on heat pipes according to claim 1, characterized in that: said evaporator (1) is located in an underground high temperature geothermal zone during operation.

3. A device for high temperature geothermal power generation based on heat pipes according to claim 1, wherein: the inner chamber of the evaporator (1) is cylindrical.

4. The apparatus for high temperature geothermal power generation based on heat pipes according to claim 1, wherein: the inner cavity of the evaporator (1) is inverted truncated cone shaped.

5. The apparatus for high temperature geothermal power generation based on heat pipe according to claim 1, wherein: the inner surface of the inner return pipe (24) is engraved with a plurality of lines (25), and the outer surface is threaded. The shape of the groove (26), the direction of the double line (25) is the same as the direction of the thread (26).