Geothermal energy-solar energy double-heat-source dynamic matching power generation system

Abstract

The invention relates to a geothermal energy-solar energy double-heat-source dynamic matching power generation system. A solar heat collection unit comprises a solar heat collector and a first check valve; the geothermal well heat extraction unit comprises a geothermal well, an inner-layer sleeve, an outer-layer sleeve, a geothermal water pump and a stratum; the heat storage regulation and control unit comprises a heat storage water tank, a water return tank, a heat source water pump, an evaporator, a water supplementing three-way valve, a water supplementing pump and a water supplementing and returning three-way valve. According to the invention, stable power output and grid connection can be realized, and frequent peak regulation of a power network is avoided; the service life of the geothermal well is effectively prolonged, and heat exhaustion is avoided; the system is simple in structure, high in reliability and wide in application range.

Description

Technical Field

[0001] The present invention belongs to the technical field of exploitation and utilization of geothermal and solar energy resources, and particularly relates to a geothermal-solar dual heat source dynamic matching power generation system. Background Art

[0002] Among many renewable energy technologies, geothermal energy and solar energy have become the focus of energy collaborative development and utilization due to their large reserves, wide distribution, high reliability, and small environmental impact. Geothermal energy can provide stable base load power, but solar energy resources are intermittent due to weather and day-night changes. For a long time, geothermal-solar hybrid power generation systems have always had problems such as large power output fluctuations and difficult grid connection.

[0003] In response to the above problems, the industry has proposed complementary power generation technologies using solar energy, geothermal energy, and energy storage. However, in existing research on the above new development technologies, larger area solar collectors are mostly used to absorb solar heat and store it in molten salt tanks for stable power output of the system when there is insufficient sunlight. However, larger scale collector fields and molten salt energy storage devices have large floor areas, high costs, and complex operation and regulation of the power generation system; geothermal energy, as the heat source of base load power, will cause geothermal resource depletion and reduced thermal output during long-term full load operation, further causing problems such as unstable power output and environmental damage. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a geothermal-solar dual heat source dynamic matching power generation system, which can achieve efficient collaborative development and utilization of geothermal energy and solar energy, solve problems such as unstable power output and difficult grid connection of existing geothermal-solar hybrid power generation systems, realize stable power output and grid connection, and avoid frequent peak shaving of the power grid; effectively extend the service life of geothermal wells and avoid thermal depletion; at the same time, it has a simple structure, high reliability, and a wide range of applications.

[0005] The present invention solves its technical problems through the following technical solutions:

[0006] A geothermal-solar dual heat source dynamic matching power generation system includes a solar heat collection unit, a geothermal well heat extraction unit, and a heat storage and regulation unit;

[0007] The solar heat collection unit includes a solar collector and a first check valve. The low-temperature return water after heat exchange in the heat storage and regulation unit flows into the inlet pipeline of the solar collector, and the outlet pipeline of the solar collector is connected to the heat storage and regulation unit through the first check valve;

[0008] The geothermal well heat extraction unit includes a geothermal well, an inner casing, an outer casing, a geothermal water pump and a formation. An outer casing and an inner casing are installed in the geothermal well, and the outer wall of the geothermal well is in close contact with the outer wall of the outer casing. The geothermal well is a dry well without water. The inner casing penetrates through the shallow low-temperature geothermal layer, the middle high-temperature geothermal layer and the deep high-temperature geothermal layer of the formation and connects the wellhead and the bottom of the well. A heat extraction water outlet channel is formed inside the inner casing, and an annular space between the inner casing and the outer casing forms a geothermal well water inlet channel. The heat extraction water outlet channel is connected to the heat storage and regulation unit through the geothermal water pump and a water supply three-way valve, and the geothermal water pump is arranged above the ground surface.

[0009] Moreover, the heat storage and regulation unit includes a hot water storage tank, a return water tank, a heat source water pump, an evaporator, a makeup water three-way valve, a makeup water pump and a makeup and return water three-way valve. The high-level end of the hot water storage tank is connected to the outlet pipeline of the solar heat collection unit through a water supply three-way valve. The low-level end of the hot water storage tank is connected to the hot water inlet of the evaporator through the heat source water pump. The hot water outlet of the evaporator is connected to the inlet pipeline of the solar heat collector through the first outlet of the return water three-way valve and the outlet of the makeup and return water three-way valve. The working medium outlet and the working medium inlet of the evaporator are jointly connected to the generator set. The second outlet of the return water three-way valve is connected to the high-level end of the return water tank. The low-level end of the return water tank is connected to the inlet of the makeup and return water three-way valve through the makeup water three-way valve and the makeup water pump. The outlet of the makeup water three-way valve is connected to the geothermal well water inlet channel.

[0010] Moreover, a second check valve is installed on the outlet pipeline of the geothermal water pump.

[0011] Moreover, the solar heat collector is a concentrating parabolic trough collector, and a temperature control valve is arranged at the front end of the first check valve on the outlet pipeline of the solar heat collector. The temperature control valve controls the outlet temperature of the heat transfer working medium in the solar heat collector to be constant according to the change of the irradiation intensity.

[0012] Moreover, the generator set is an organic Rankine cycle generator set, and the working medium of the generator set is Rfa or Ra.

[0013] Moreover, the inner casing and the outer casing are concentric casings. The flow direction of the circulating water in the concentric casings is "outward injection and inward discharge". The circulating water has no direct contact with the formation. In the geothermal well heat extraction unit, the circulating water reaches the bottom of the geothermal well through the geothermal well water inlet channel, flows out of the ground through the heat extraction water outlet channel after heat exchange with the formation, and is sent to the hot water storage tank by the geothermal water pump.

[0014] Moreover, the return water tank is installed near the geothermal wellhead.

[0015] Moreover, the volume of the hot water storage tank is larger than that of the return water tank.

[0016] The positive effects that the present invention can produce are as follows:

[0017] 1. The geothermal energy-solar energy dual heat source dynamic matching power generation system provided by the present invention breaks the limitation of unstable power output of the existing geothermal-solar energy coupled power generation system, can achieve all-weather stable output and high-quality grid connection, and avoids frequent peak regulation of the power grid.

[0018] 2. While the geothermal energy-solar energy dynamic matching power generation system provided by the present invention stably outputs power, it can achieve intermittent operation of the geothermal well, avoid thermal depletion of the hot dry rock geothermal resources, and effectively extend the service life of the geothermal well.

[0019] 3. The geothermal energy-solar energy dynamic matching power generation system provided by the present invention is provided with a hot water storage tank and a return water tank. Compared with the existing geothermal-solar energy-molten salt energy storage coupled power generation system, the system structure is simple, the heat storage working medium is water, which can greatly reduce the investment, construction and operation costs of the heat storage system, and improve the economy of the system.

[0020] 4. For the geothermal energy-solar energy dynamic matching power generation system provided by the present invention, the area of the solar collector is determined by the maximum output of the geothermal well. Compared with the existing geothermal-solar energy-molten salt energy storage coupled power generation system, it can greatly reduce the area of the collector, the floor area and the volume of the heat storage tank, and improve the overall economy. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic structural diagram of the present invention;

[0022] Figure 2 is a schematic diagram of the water flow direction of the heat source loop under the low-irradiance power generation condition of the present invention;

[0023] Figure 3 is a schematic diagram of the water flow direction of the heat source loop under the strong-irradiance power generation condition of the present invention;

[0024] Figure 4 is a schematic diagram of the water flow direction of the heat source loop under the geothermal energy power generation condition without irradiation of the present invention;

[0025] Figure 5 is a schematic diagram of the water flow direction of the heat source loop under the hot water storage tank power generation condition without irradiation of the present invention.

[0026] Description of the reference numerals:

[0027] 1. Heat source water pump; 2. Evaporator; 3. Evaporator hot water inlet; 4. Evaporator hot water outlet; 5. Evaporator working medium inlet; 6. Evaporator working medium outlet; 7. Return water three-way valve; 8. Return water three-way valve inlet; 9. Return water three-way valve second outlet; 10. Return water three-way valve first outlet; 11. Return water tank; 12. Make-up water three-way valve; 13. Make-up water three-way valve inlet; 14. Make-up water three-way valve first outlet; 15. Make-up water three-way valve second outlet; 16. Make-up water pump; 17. Make-up and return water three-way valve; 18. Make-up and return water three-way valve first inlet; 19. Make-up and return water three-way valve second inlet; 20. Make-up and return water three-way valve outlet; 21. Inner sleeve; 22. Outer sleeve; 23. Geothermal well; 24. Stratum; 25. Solar collector; 26. Temperature control valve; 27. First check valve; 28. Geothermal water pump; 29. Second check valve; 30. Feed water three-way valve; 31. Feed water three-way valve first inlet; 32. Feed water three-way valve second inlet; 33. Feed water three-way valve outlet; 34. Hot water storage tank; 35. Generator set. Detailed implementation mode

[0028] The present invention will be further described in detail below through specific embodiments. The following embodiments are only descriptive and not restrictive, and the protection scope of the present invention cannot be limited thereby.

[0029] As Figure 1 shown, a geothermal-solar dual heat source dynamic matching power generation system is characterized in that it includes a solar heat collection unit, a geothermal well heat extraction unit and a heat storage regulation unit.

[0030] The solar heat collection unit includes a solar collector 25 and a first check valve 27. The low-temperature return water after heat exchange in the heat storage regulation unit flows into the inlet pipeline of the solar collector 25, and the outlet pipeline of the solar collector 25 is connected to the heat storage regulation unit through the first check valve 27.

[0031] The geothermal well heat extraction unit includes a geothermal well 23, an inner sleeve 21, an outer sleeve 22, a geothermal water pump 28 and a stratum 24. The outer sleeve 22 and the inner sleeve 21 are installed in the geothermal well 23, and the outer wall of the geothermal well 23 is in close contact with the outer wall of the outer sleeve. The geothermal well 23 is a dry well without water; the inner sleeve 21 penetrates through the shallow low-temperature geothermal layer, the middle high-temperature geothermal layer and the deep high-temperature geothermal layer of the stratum 24 and communicates with the wellhead and the bottom of the well. A heat extraction water outlet channel is formed inside the inner sleeve 21, and an annular space between the inner sleeve 21 and the outer sleeve 22 forms a geothermal well water inlet channel; the heat extraction water outlet channel is connected to the second inlet 32 of the feed water three-way valve through the geothermal water pump 28, and is connected to the heat storage regulation unit through the feed water three-way valve outlet 33. The geothermal water pump 28 is arranged above the ground surface.

[0032] The heat storage and regulation unit includes a hot water storage tank 34, a return water tank 11, a heat source water pump 1, an evaporator 2, a makeup water three-way valve 14, a makeup water pump 16, and a makeup and return water three-way valve 17. The high-level end of the hot water storage tank 34 is connected to the outlet pipeline of the solar heat collection unit through a feed water three-way valve 30. The low-level end of the hot water storage tank 34 is connected to the hot water inlet 3 of the evaporator 2 through the heat source water pump 1. The hot water outlet 4 of the evaporator 2 is connected to the inlet 8 of the return water three-way valve. After passing through the first outlet 10 of the return water three-way valve and connecting to the first inlet 18 of the makeup and return water three-way valve, it is connected to the inlet pipeline of the solar collector 25 through the outlet 20 of the makeup and return water three-way valve. The working fluid outlet 6 and the working fluid inlet 5 of the evaporator are jointly connected to the generator set 35. The second outlet 9 of the return water three-way valve 7 is connected to the high-level end of the return water tank 11. The low-level end of the return water tank 11 is connected to the inlet 13 of the makeup water three-way valve and is connected to the second inlet 19 of the makeup and return water three-way valve through the second outlet 15 of the makeup water three-way valve and the makeup water pump 16. The first outlet 14 of the makeup water three-way valve is connected to the geothermal well water inlet channel.

[0033] A second check valve 29 is installed on the outlet pipeline of the geothermal water pump 28 to prevent the hot fluid in the solar collector 25 loop from entering the geothermal well heat extraction unit loop through the first inlet 31 of the feed water three-way valve.

[0034] The solar collector 25 is a concentrating parabolic trough collector. A temperature control valve 26 is provided at the front end of the first check valve 27 on the outlet pipeline of the solar collector 25. The temperature control valve 26 controls the constant temperature of the heat transfer working fluid at the outlet of the solar collector 25 according to the change of the irradiation intensity.

[0035] The generator set 35 is an organic Rankine cycle generator set, and the working fluid of the generator set 35 is R245fa or R134a.

[0036] The inner sleeve 21 and the outer sleeve 22 are concentric sleeves. The flow direction of the circulating water in the concentric sleeves is "outward injection and inward discharge". The circulating water has no direct contact with the formation. In the geothermal well heat extraction unit, the circulating water reaches the bottom of the geothermal well through the geothermal well water inlet channel, flows out of the ground after heat exchange with the formation through the heat extraction outlet channel, and is sent to the hot water storage tank 34 by the geothermal water pump 28.

[0037] The return water tank 11 is installed near the geothermal well head and is used to store the return water required for geothermal well heat extraction and the makeup water for the solar collector.

[0038] The volume of the hot water storage tank 34 is larger than that of the return water tank 11, and it is used to store the heat source water at the same temperature from the geothermal well and the solar collector.

[0039] Under the strong irradiation power generation condition, the return water three-way valve 7, the return water tank 11, the make-up water three-way valve 12, the make-up water pump 16, the make-up and return water three-way valve 17, the solar collector 25, the temperature control valve 26, the first check valve 27, the feed water three-way valve 30, the hot water storage tank 34, the heat source water pump 1 and the evaporator 2 constitute the heat source water circuit for the strong irradiation power generation condition. The specific water flow direction schematic diagram is shown in Figure 3 ;

[0040] In the medium and low irradiation power generation condition, the return water three-way valve 7, the return water tank 11, the make-up water three-way valve 12, the inner sleeve 21, the outer sleeve 22, the geothermal water pump 28, the second check valve 29, the make-up and return water three-way valve 17, the solar collector 25, the temperature control valve 26, the check valve 27, the feed water three-way valve 30, the hot water storage tank 34, the heat source water pump 1 and the evaporator 2 constitute the heat source circuit for the medium and low irradiation power generation condition. The specific water flow direction schematic diagram is shown in Figure 2 ;

[0041] In the geothermal energy power generation condition without irradiation, the return water three-way valve 7, the return water tank 11, the make-up water three-way valve 12, the inner sleeve 21, the outer sleeve 22, the geothermal water pump 28, the second check valve 29, the feed water three-way valve 30, the hot water storage tank 34, the heat source water pump 1 and the evaporator 2 constitute the heat source water circuit for the power generation condition without irradiation. The specific water flow direction schematic diagram is shown in Figure 4 ;

[0042] Specifically, under the optimal output conditions of the geothermal well heat source water flow rate of 20 m 3 / h and the temperature of 110 °C, the strong irradiation intensity DNI = 800 W / m 2 is the lower limit preset value. Taking the medium and low irradiation power generation condition and the strong irradiation power generation condition as examples, the heat source matching and utilization process of the geothermal energy-solar dual heat source dynamic matching power generation system is introduced in detail:

[0043] In the medium and low irradiation power generation condition, that is, the vertical irradiation intensity 0 W / m 2 ≤ DNI ≤ 800 W / m 2When the temperature is low after heat release, the low-temperature return water flows out from the hot water outlet 4 of the evaporator and enters the return water three-way valve 7. Part of the low-temperature return water enters the make-up return water three-way valve 17 through the first outlet 10 of the return water three-way valve. The second inlet 19 of the make-up return water three-way valve is closed. The low-temperature return water enters the solar collector 25 through the outlet 20 of the make-up return water three-way valve. After absorbing heat and rising in temperature, it flows out of the collector and enters the temperature control valve 26. The temperature control valve 26 automatically adjusts the valve opening according to the fluid temperature at the outlet of the solar collector 25 to control the flow rate of the low-temperature return water until the outlet temperature reaches the preset temperature of 110°C. After that, it enters the second inlet 32 of the feed water three-way valve through the check valve 27, and then is mixed with the geothermal water from the first inlet 31 of the feed water three-way valve. The function of the check valve 27 is to prevent the geothermal water from entering the solar heat collection unit. The remaining low-temperature return water flows out from the second outlet 9 of the three-way valve, flows through the pipeline into the return water tank 11. The second outlet 15 of the make-up water three-way valve is closed. The low-temperature return water enters the annular channel formed by the inner sleeve 21 and the outer sleeve 22 from the low position of the return water tank 11 under the suction of the geothermal water pump 23 through the make-up water three-way valve 12. The outer sleeve 22 is in close contact with the well wall of the geothermal well 23. The low-temperature return water continuously absorbs the heat of the formation 24 from top to bottom and reaches the bottom of the geothermal well 23, and then flows to the ground through the internal channel of the inner sleeve 21. The heated geothermal water at 110°C enters the check valve 29 through the geothermal water pump 28 arranged on the ground. The geothermal water pump 28 always maintains a flow rate of 20m 3 / h to maintain a stable geothermal water outlet temperature. The check valve is to prevent the hot water in the solar heat collection unit from entering the geothermal well heat extraction unit. After the high-temperature geothermal water exits the check valve 29, it is mixed with the high-temperature hot water from the second inlet 32 of the feed water three-way valve at the first inlet 31 of the feed water three-way valve and then flows out of the outlet 33 of the feed water three-way valve, and enters the hot water storage tank 34 through the pipeline. The 110°C hot water enters the evaporator 2 from the low position of the water tank through the heat source water pump 1. The output of the heat source water pump is constant and always maintains a flow rate of 20m 3 / h. The water tank stores the high-temperature hot water from the geothermal well heat extraction unit and the solar heat collection unit. After the heat source hot water releases heat in the evaporator, it flows out from the hot water outlet 4 of the evaporator. The organic working fluid absorbs heat in the evaporator 2 and then enters the generator set 35 to realize power output, and thus starts the next cycle.

[0044] Strong irradiation power generation condition, that is, the vertical irradiation intensity DNI > 800W / m 2When the temperature is low, the low-temperature return water after heat release flows out from the hot water outlet 4 of the evaporator, enters the return water three-way valve 7. The second outlet 9 of the return water three-way valve is fully closed, and all the return water flows out from the first outlet 10 of the return water three-way valve, and enters the first inlet 18 of the make-up and return water three-way valve through the pipeline. At the same time, the first outlet 14 of the make-up water three-way valve is fully closed. The low-temperature return water stored in the return water tank 11 is sucked by the make-up water pump 16, enters the make-up water three-way valve 12, then enters the make-up water pump 16 through the pipeline, and then enters the second inlet 19 of the make-up and return water three-way valve through the pipeline. It is mixed with the low-temperature return water from the first inlet 18 of the make-up and return water three-way valve in the make-up and return water three-way valve 17, and then enters the solar collector 25 through the pipeline. The solar hot water after absorbing heat and increasing temperature enters the temperature control valve 26. The temperature control valve 26 automatically adjusts the valve opening according to the fluid temperature at the outlet of the solar collector 25 to control the make-up and return water flow until the outlet temperature reaches the preset temperature of 110 °C. Among them, the flow rate of the low-temperature return water after heat exchange in the evaporator 2 is constantly 20 m 3 / h, and the temperature control valve 26 actually only controls the flow rate of the make-up water pump. After that, the first inlet 31 of the feed water three-way valve is closed, and the high-temperature solar hot water enters the second inlet 32 of the feed water three-way valve through the check valve 27, and flows out from the outlet 33 of the feed water three-way valve and enters the hot water storage tank 34. Under the suction of the heat source water pump 1, the 110 °C heat source water enters the evaporator 2 from the hot water storage tank at a flow rate of 20 m 3 / h, flows out from the hot water outlet 4 of the evaporator after heat release, and the organic working fluid enters the power generation unit 35 after absorbing heat in the evaporator 2 to realize power output, and thus starts the next cycle.

[0045] Although the embodiments and drawings of the present invention are disclosed for illustrative purposes, those skilled in the art can understand that: various substitutions, changes and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the content disclosed in the embodiments and drawings.

Claims

1. A geothermal energy-solar energy dual heat source dynamic matching power generation system, characterized by: It includes a solar heat collection unit, a geothermal well heat extraction unit and a heat storage and control unit; The solar thermal collection unit comprises a solar thermal collector (25) and a first check valve (27); low-temperature return water after heat exchange in the heat storage and regulation unit flows into the inlet pipeline of the solar thermal collector (25); and the outlet pipeline of the solar thermal collector (25) is connected to the heat storage and regulation unit via the first check valve (27); The geothermal well heat extraction unit comprises a geothermal well (23), an inner casing (21), an outer casing (22), a geothermal water pump (28) and a stratum (24); the outer casing (22) and the inner casing (21) are installed in the geothermal well (23); the wall of the geothermal well (23) is in close contact with the outer wall of the outer casing; and the geothermal well (23) is a waterless dry well; The inner casing (21) penetrates the shallow low-temperature geothermal layer, the middle high-temperature geothermal layer and the deep high-temperature geothermal layer of the stratum (24) and connects the wellhead and the bottom of the well. The interior of the inner casing (21) forms a heat extraction and water outlet channel. The annular space between the inner casing (21) and the outer casing (22) forms a geothermal well water inlet channel. The heat extraction and water outlet channel is connected to the heat storage control unit through a geothermal water pump (28) and a water supply three-way valve (30). The geothermal water pump (28) is arranged above the ground surface.

2. The geothermal energy-solar energy dual heat source dynamic matching power generation system according to claim 1 is characterized in that: The heat storage control unit comprises a hot water storage tank (34), a return water tank (11), a heat source water pump (1), an evaporator (2), a water replenishment three-way valve (14), a water replenishment pump (16) and a water replenishment and return three-way valve (17); the high-position end of the hot water storage tank (34) is connected to the outlet pipeline of the solar thermal collection unit through a water supply three-way valve (30); the low-position end of the hot water storage tank (34) is connected to the hot water inlet (3) of the evaporator (2) through a heat source water pump (1); the hot water outlet (4) of the evaporator (2) is connected to the hot water outlet (5) of the evaporator (2) through the return water three-way valve (7); The first outlet and the outlet of the replenishment and return water three-way valve (17) are connected to the inlet pipeline of the solar collector (25), the evaporator working fluid outlet (6) and the evaporator working fluid inlet (5) are connected to the generator set (35), the second outlet of the return water three-way valve (7) is connected to the high-position end of the return water tank (11), the low-position end of the return water tank (11) is connected to the inlet of the replenishment and return water three-way valve (17) through the replenishment water three-way valve (12) and the replenishment water pump (16), and the outlet of the replenishment water three-way valve (12) is connected to the water inlet channel of the geothermal well.

3. The geothermal energy-solar energy dual heat source dynamic matching power generation system according to claim 1 is characterized in that: A second check valve (29) is installed on the outlet pipeline of the geothermal water pump (28).

4. The geothermal energy-solar energy dual heat source dynamic matching power generation system according to claim 1 is characterized in that: The solar thermal collector (25) is a concentrating parabolic trough collector. A temperature control valve (26) is provided on the outlet pipeline of the solar thermal collector (25) at the front end of the first check valve (27). The temperature control valve (26) controls the temperature of the heat transfer medium at the outlet of the solar thermal collector (25) to be constant as the radiation intensity changes.

5. The geothermal energy-solar energy dual heat source dynamic matching power generation system according to claim 1 is characterized in that: The generator set (35) is an organic Rankine cycle generator set, and the working fluid of the generator set (35) is R245fa or R134a.

6. The geothermal energy-solar energy dual heat source dynamic matching power generation system according to claim 1 is characterized in that: The inner casing (21) and the outer casing (22) are concentric casings. The flow direction of the circulating water in the concentric casings is "injection outside and outlet inside". The circulating water has no direct contact with the formation. The circulating water in the geothermal well heat extraction unit directly reaches the bottom of the geothermal well through the geothermal well water inlet channel. After exchanging heat with the formation, it flows out of the ground through the heat extraction water outlet channel and is sent to the hot water storage tank (34) by the geothermal water pump (28).

7. The geothermal energy-solar energy dual heat source dynamic matching power generation system according to claim 1 is characterized in that: The return water tank (11) is installed close to the geothermal wellhead.

8. The geothermal energy-solar energy dual heat source dynamic matching power generation system according to claim 1 is characterized in that: The volume of the hot water storage tank (34) is larger than that of the return water tank (11).

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