Flash-based geothermal energy and solar energy coupled cascade power generation system and method

Abstract

The present invention provides a flash-based geothermal energy and solar energy coupled cascade power generation system and method. The system mainly includes: a gas-liquid separator, an evaporator, a condenser, an expander, a generator, a production well, a reinjection well, a geothermal fluid pump, a solar collector, a heat storage device, a heat transfer medium pump, relevant stop valves and throttle valves. It can operate the system in different modes by controlling the opening and closing of each valve according to different heat source conditions. The present invention realizes the comprehensive utilization of geothermal energy and solar energy, while improving the quality of the working fluid of the system and ensuring the stability of power output.

Description

Technical Field

[0001] The present invention relates to the technical field of flash cycle power generation, and more specifically, to a geothermal energy and solar energy coupled cascade power generation system and method based on flash evaporation. Background Art

[0002] Based on the current energy utilization status and environmental problems, clean energy supply technologies have been vigorously developed, among which geothermal energy flash power generation technology and solar thermal power generation technology have received extensive attention. However, due to the relatively low grade of geothermal fluid, the temperature of the work steam obtained by flash evaporation is relatively low, resulting in generally low power generation efficiency of geothermal energy flash power generation systems. Moreover, for solar energy, its energy flux density is low, and it exhibits unstable and dispersed characteristics due to natural conditions such as day and night alternation, seasonal changes, geographical distribution, and altitude, making the solar thermal power generation system occupy a large area and have obvious intermittency. The respective defects of the two systems seriously hinder their application in engineering practice and urgently need to be improved.

[0003] Therefore, there is an urgent need for a technical solution in the prior art that can stably generate electricity using geothermal energy and solar energy. Summary of the Invention

[0004] In view of the above situation, the problem to be solved by the present invention is how to stably generate electricity by coupling solar energy and geothermal energy under the conditions of relatively low geothermal energy grade and large solar energy intermittency.

[0005] The technical solution for the present invention to solve the technical problem is as follows.

[0006] A geothermal energy and solar energy coupled cascade power generation system based on flash evaporation, including a first-stage gas-liquid separator, an expander, a generator, a geothermal fluid pump, a first-stage evaporator, a second-stage gas-liquid separator, a second-stage evaporator, a third-stage gas-liquid separator, a third-stage evaporator, a second heat transfer medium pump, a condenser, a solar collector, a first heat transfer medium pump, a heat storage device, a first stop valve, a second stop valve, a third stop valve, a fourth stop valve, a throttle valve, and a fifth stop valve;

[0007] The inlet of the solar collector is respectively connected to the outlet of the second stop valve, the inlet of the fourth stop valve, and the outlet of the second heat transfer medium pump, and the outlet of the solar collector is connected to the inlet of the first heat transfer medium pump; the outlet of the first heat transfer medium pump is respectively connected to the inlet of the first stop valve, the outlet of the third stop valve, and the heat source inlet of the first-stage evaporator, and the heat source outlet of the first-stage evaporator is connected to the heat source inlet of the second-stage evaporator;

[0008] The working fluid inlet of the first-stage evaporator is connected to the outlet of the geothermal fluid pump, and the working fluid outlet of the first-stage evaporator is connected to the inlet of the second-stage gas-liquid separator;

[0009] The heat storage device is respectively communicated with the outlet of the first stop valve, the inlet of the second stop valve, the inlet of the third stop valve and the outlet of the fourth stop valve; the inlet of the primary gas-liquid separator is communicated with the production well, the steam outlet of the primary gas-liquid separator is communicated with the second intermediate stage inlet of the expander, and the liquid outlet of the primary gas-liquid separator is respectively communicated with the inlet of the throttle valve and the inlet of the geothermal fluid pump; the outlet of the throttle valve is communicated with the inlet of the fifth stop valve, and the outlet of the fifth stop valve is communicated with the injection well.

[0010] The steam outlet of the secondary gas-liquid separator is communicated with the primary inlet of the expander, and the liquid outlet of the secondary gas-liquid separator is communicated with the working medium inlet of the secondary evaporator; the working medium outlet of the secondary evaporator is communicated with the inlet of the tertiary gas-liquid separator, and the heat source outlet of the secondary evaporator is communicated with the heat source inlet of the tertiary evaporator; the steam outlet of the tertiary gas-liquid separator is communicated with the first intermediate stage inlet of the expander, and the liquid outlet of the tertiary gas-liquid separator is communicated with the working medium inlet of the tertiary evaporator; the working medium outlet of the tertiary evaporator is communicated with the second intermediate stage inlet of the expander, and the heat source outlet of the tertiary evaporator is communicated with the inlet of the second heat transfer medium pump; the expander is connected with the generator, and the outlet of the expander is communicated with the working medium inlet of the condenser; the working medium outlet of the condenser is communicated with the injection well.

[0011] The cooling water inlet and the cooling water outlet of the condenser are communicated with the external cooling water source.

[0012] The present invention also provides a technical solution, which is specifically as follows.

[0013] A geothermal energy and solar energy coupled cascade power generation system based on flash evaporation, comprising: a primary gas-liquid separator, a first expander, a first generator, a second expander, a second generator, a third expander, a third generator, a geothermal fluid pump, a primary evaporator, a secondary gas-liquid separator, a secondary evaporator, a tertiary gas-liquid separator, a tertiary evaporator, a second heat transfer medium pump, a condenser, a solar collector, a first heat transfer medium pump, a heat storage device, a first stop valve, a second stop valve, a third stop valve, a fourth stop valve, a throttle valve, a fifth stop valve.

[0014] The inlet of the solar collector is respectively communicated with the outlet of the second stop valve, the inlet of the fourth stop valve and the outlet of the second heat transfer medium pump, and the outlet of the solar collector is communicated with the inlet of the first heat transfer medium pump; the outlet of the first heat transfer medium pump is respectively communicated with the inlet of the first stop valve, the outlet of the third stop valve and the heat source inlet of the primary evaporator, and the heat source outlet of the primary evaporator is communicated with the heat source inlet of the secondary evaporator.

[0015] The working medium inlet of the primary evaporator is communicated with the outlet of the geothermal fluid pump, and the working medium outlet of the primary evaporator is communicated with the inlet of the secondary gas-liquid separator.

[0016] The heat storage device is respectively connected to the outlet of the first stop valve, the inlet of the second stop valve, the inlet of the third stop valve and the outlet of the fourth stop valve; the inlet of the first-stage gas-liquid separator is connected to the production well, the steam outlet of the first-stage gas-liquid separator is connected to the inlet of the second expander, and the liquid outlet of the first-stage gas-liquid separator is respectively connected to the inlet of the throttle valve and the inlet of the geothermal fluid pump; the outlet of the throttle valve is connected to the inlet of the fifth stop valve, and the outlet of the fifth stop valve is connected to the reinjection well.

[0017] The steam outlet of the second-stage gas-liquid separator is connected to the inlet of the first expander, and the liquid outlet of the second-stage gas-liquid separator is connected to the working medium inlet of the second-stage evaporator; the working medium outlet of the second-stage evaporator is connected to the inlet of the third-stage gas-liquid separator, and the heat source outlet of the second-stage evaporator is connected to the heat source inlet of the third-stage evaporator; the steam outlet of the third-stage gas-liquid separator is connected to the inlet of the second expander, and the liquid outlet of the third-stage gas-liquid separator is connected to the working medium inlet of the third-stage evaporator; the working medium outlet of the third-stage evaporator is connected to the inlet of the third expander, and the heat source outlet of the third-stage evaporator is connected to the inlet of the second heat transfer medium pump; the outlets of the first expander, the second expander, and the third expander are all connected to the working medium inlet of the condenser; the working medium outlet of the condenser is connected to the reinjection well.

[0018] The first expander is connected to the first generator, the second expander is connected to the second generator, the third expander is connected to the third generator, and the cooling water inlet and outlet of the condenser are connected to the external cooling water source.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] 1. A gas-liquid separator is provided to flash the geothermal fluid from the production well and the outlet of the evaporator to obtain steam that can be used for work, realizing the full recovery and utilization of medium and low-grade thermal energy.

[0021] 2. The solar collector uses solar energy to heat the geothermal fluid to improve its work capacity, thereby improving the system efficiency.

[0022] 3. The heat storage device stores solar heat when the sun is sufficient, and provides heat source for the geothermal flash power generation system when the sun is insufficient or there is no sun, improving the system stability.

[0023] 4. The three solar evaporators fully exchange heat between the saturated liquid separated by each stage of gas-liquid separator and the heat transfer medium, maximizing the thermal utilization efficiency of solar energy.

[0024] 5. The throttle valve throttles a part of the saturated liquid geothermal fluid after flashing in the first-stage gas-liquid separator and directly injects it into the reinjection well, reducing the heat demand of the geothermal fluid and improving the quality of the work steam as much as possible.

[0025] 6. The organic combination of geothermal energy and solar energy reduces the investment cost of the thermal power generation system, improves the system output power and power generation efficiency, and at the same time improves the stability of the heat source. Description of the Drawings

[0026] Figure 1 It is a schematic diagram of the system of Embodiment 1 of the present invention.

[0027] Figure 2 It is a schematic diagram of the system of Embodiment 2 of the present invention.

[0028] Figure 1 Wherein: 1 - primary gas-liquid separator; 2 - expander; 3 - generator; 4 - geothermal fluid pump; 5 - primary evaporator; 6 - secondary gas-liquid separator; 7 - secondary evaporator; 8 - tertiary gas-liquid separator; 9 - tertiary evaporator; 10 - second heat transfer medium pump; 11 - condenser; 12 - production well; 13 - reinjection well; 14 - solar collector; 15 - first heat transfer medium pump; 16 - heat storage device; 17 - first stop valve; 18 - second stop valve; 19 - third stop valve; 20 - fourth stop valve; 21 - throttle valve; 22 - fifth stop valve; 23 - secondary expander; 24 - secondary generator; 25 - tertiary expander; 26 - tertiary generator; 27 - primary expander; 28 - primary generator. Detailed Embodiments

[0029] To make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the following further describes the present invention in detail with reference to specific embodiments and the accompanying drawings. The specific embodiments are only used to further describe the present invention in detail and do not limit the protection scope of the claims of this application.

[0030] Embodiment 1

[0031] This embodiment provides a geothermal energy and solar energy coupled cascade power generation system based on flash evaporation technology (referred to as the system, see Figure 1 ), which is characterized in that the system includes a primary gas-liquid separator 1, an expander 2, a generator 3, a geothermal fluid pump 4, a primary evaporator 5, a secondary gas-liquid separator 6, a secondary evaporator 7, a tertiary gas-liquid separator 8, a tertiary evaporator 9, a second heat transfer medium pump 10, a condenser 11, a production well 12, a reinjection well 13, a solar collector 14, a first heat transfer medium pump 15, a heat storage device 16, a first stop valve 17, a second stop valve 18, a third stop valve 19, a fourth stop valve 20, a throttle valve 21, and a fifth stop valve 22.

[0032] The inlets of the solar collector 14 are respectively communicated with the outlet of the second shut-off valve 18, the inlet of the fourth shut-off valve 20, and the outlet of the second heat transfer medium pump 10; the outlet of the solar collector 14 is communicated with the inlet of the first heat transfer medium pump 15; the outlet of the first heat transfer medium pump 15 is respectively communicated with the inlet of the first shut-off valve 17, the outlet of the third shut-off valve 19, and the heat source inlet of the primary evaporator 5; the heat storage device 16 is respectively communicated with the outlet of the first shut-off valve 17, the inlet of the second shut-off valve 18, the inlet of the third shut-off valve 19, and the outlet of the fourth shut-off valve 20; the inlet of the primary gas-liquid separator 1 is connected to the geothermal fluid from the production well, the steam outlet of the primary gas-liquid separator 1 is communicated with the second intermediate stage inlet of the expander 2, and the liquid outlet of the primary gas-liquid separator 1 is respectively communicated with the inlet of the throttle valve 21 and the geothermal fluid pump 4; the outlet of the throttle valve 21 is communicated with the inlet of the fifth shut-off valve 22, and the outlet of the fifth shut-off valve 22 is connected to the reinjection well 13; the working fluid inlet of the primary evaporator 5 is communicated with the outlet of the geothermal fluid pump 4, the working fluid outlet of the primary evaporator 5 is communicated with the inlet of the secondary gas-liquid separator 6, and the heat source outlet of the primary evaporator 5 is communicated with the heat source inlet of the secondary evaporator 7; the steam outlet of the secondary gas-liquid separator 6 is communicated with the inlet of the expander 2, and the liquid outlet of the secondary gas-liquid separator 6 is communicated with the working fluid inlet of the secondary evaporator 7; the working fluid outlet of the secondary evaporator 7 is communicated with the inlet of the tertiary gas-liquid separator 8, and the heat source outlet of the secondary evaporator 7 is communicated with the heat source inlet of the tertiary evaporator 9; the steam outlet of the tertiary gas-liquid separator 8 is communicated with the first intermediate stage inlet of the expander 2, and the liquid outlet of the tertiary gas-liquid separator 8 is communicated with the working fluid inlet of the tertiary evaporator 9; the working fluid outlet of the tertiary evaporator 9 is communicated with the second intermediate stage inlet of the expander 2, and the heat source outlet of the tertiary evaporator 9 is communicated with the inlet of the second heat transfer medium pump 10; the expander 2 expands to do work to drive the generator 3; the working fluid inlet of the condenser 11 is communicated with the outlet of the expander 2, the working fluid outlet of the condenser 11 is communicated with the reinjection well 13, and the condenser 11 has cooling water inlets and outlets, and the cooling water inlets and outlets are connected to the external cooling water source.

[0033] The function of the primary gas-liquid separator 1 is to cause the medium and low-grade geothermal fluid to flash by reducing pressure and expanding volume to obtain steam for doing work.

[0034] The functions of the secondary gas-liquid separator 6 and the tertiary gas-liquid separator 8 are to flash the liquid or two-phase geothermal fluid from the primary evaporator 5 and the secondary evaporator 7 respectively, so as to further improve the system efficiency and output work.

[0035] The primary evaporator 5, the secondary evaporator 7, and the tertiary evaporator 9 use the heat transfer medium to heat the geothermal fluid, and finally produce saturated or superheated steam at the working fluid outlet of the tertiary evaporator 9.

[0036] The heat storage device stores additional solar heat when sunlight is sufficient and provides heat source for geothermal fluid when sunlight is insufficient or there is no sunlight.

[0037] The function of the throttle valve is to throttle part of the saturated liquid geothermal fluid and directly inject it into the reinjection well when sunlight is insufficient or there is no sunlight, so as to reduce the total amount of geothermal fluid and improve the quality of the working steam.

[0038] The control method of the above system includes three working modes. First, when sunlight is sufficient, the heat transfer medium from the solar collector heats the geothermal fluid in each stage of the evaporator and the heat storage medium in the heat storage device respectively, achieving the purpose of energy storage while improving the energy grade of the geothermal fluid. Second, when sunlight is insufficient, the heat transfer medium heated by the solar collector and the heat storage device enters each stage of the evaporator to improve the energy grade of the geothermal fluid. At the same time, the opening of the throttle valve at the liquid outlet of the first-stage gas-liquid separator 1 is controlled to throttle part of the geothermal fluid and inject it into the reinjection well to reduce the total amount of geothermal fluid, prevent the imbalance of the circulation flow rate, and improve the quality of the working steam as much as possible. Third, when there is no sunlight, the solar collector stops operating, and the heat transfer medium is completely heated by the heat storage medium in the heat storage device and sent to each stage of the evaporator to heat the geothermal fluid. Similarly, the opening of the throttle valve 21 at the liquid outlet of the gas-liquid separator is controlled to throttle part of the geothermal fluid and inject it into the reinjection well to reduce the total amount of geothermal fluid.

[0039] When sunlight is sufficient, solar energy stores energy in the heat storage device while heating the geothermal fluid. When sunlight is insufficient, solar thermal energy and solar heat storage heat the geothermal fluid simultaneously, and the throttle valve 21 is opened to throttle and depressurize part of the geothermal fluid to inject it into the reinjection well, thereby reducing the total amount of geothermal fluid and preventing the imbalance of the circulation flow rate. When there is no sunlight, only solar heat storage heats the geothermal fluid, and the throttle valve 21 is opened at the same time.

[0040] The specific steps of each mode are as follows:

[0041] Mode 1:

[0042] When there is sufficient sunlight, open the first stop valve 17 and the second stop valve 18, and close the third stop valve 19, the fourth stop valve 20, the throttle valve 21 and the fifth stop valve 22. The solar collector 14 heats the heat transfer medium. After the high-temperature heat transfer medium is pressurized by the first heat transfer medium pump 15, a part of it directly enters the primary evaporator 5 to heat the geothermal fluid; another part passes through the first stop valve 17 and enters the heat storage device 16, transferring the heat from the high-temperature heat transfer medium to the heat storage medium. The low-temperature heat transfer medium after heat exchange in the heat storage device 16 flows out through the second stop valve 18, and is mixed with the low-temperature heat transfer medium from the second heat transfer medium pump 10 and then sent to the solar collector 14 together; the geothermal fluid enters the primary gas-liquid separator 1 from the production well 12 for flashing. The saturated gaseous geothermal fluid obtained by flashing flows out from the steam outlet of the primary gas-liquid separator 1; the saturated liquid geothermal fluid flows out from the liquid outlet of the primary gas-liquid separator 1, and is pressurized to the evaporation pressure by the geothermal fluid pump 4 and becomes subcooled liquid; the subcooled liquid geothermal fluid enters the working medium inlet of the primary evaporator 5 and exchanges heat with the heat transfer medium in the primary evaporator 5, turning the geothermal fluid into saturated liquid; the heat transfer medium after heat exchange flows out from the heat source outlet of the primary evaporator 5 and enters the heat source inlet of the secondary evaporator 7; the saturated liquid geothermal fluid flows out from the working medium outlet of the primary evaporator 5 and enters the secondary gas-liquid separator 6 for flashing; the saturated gaseous geothermal fluid obtained by flashing flows out from the steam outlet of the secondary gas-liquid separator 6 and enters the expander 2 through the inlet of the expander 2 to expand and do work; the saturated liquid geothermal fluid flows out from the liquid outlet of the secondary gas-liquid separator 6 and enters the working medium inlet of the secondary evaporator 7, exchanging heat with the heat transfer medium in the secondary evaporator 7, turning the geothermal fluid into a gas-liquid two-phase state; the heat transfer medium after heat exchange flows out from the heat source outlet of the secondary evaporator 7 and enters the heat source inlet of the tertiary evaporator 9; the two-phase geothermal fluid enters the tertiary gas-liquid separator 8 for flashing; the saturated gaseous geothermal fluid obtained by flashing flows out from the steam outlet of the tertiary gas-liquid separator 8 and enters the expander 2 through the first intermediate-stage inlet of the expander 2 to expand and do work; the saturated liquid geothermal fluid flows out from the liquid outlet of the tertiary gas-liquid separator 8 and enters the working medium inlet of the tertiary evaporator 9, exchanging heat with the heat transfer medium in the tertiary evaporator 9, turning the geothermal fluid into saturated gas; the heat transfer medium after heat exchange flows out from the heat source outlet of the tertiary evaporator 9 and enters the inlet of the second heat transfer medium pump 10; the saturated gaseous geothermal fluid is mixed with the saturated gaseous geothermal fluid from the primary gas-liquid separator 1 and then enters the expander 2 through the second intermediate-stage inlet of the expander 2 to expand and do work; the expander drives the generator 3 to generate electricity; the exhaust steam of the expander 2 enters the condenser 11; the gaseous geothermal fluid exchanges heat with the cooling water entering the condenser 11 from the outside. The heat-exchanged low-temperature cooling water becomes high-temperature cooling water and flows out from the cooling water outlet of the condenser 11; the heat-exchanged gaseous geothermal fluid condenses into liquid geothermal fluid, flows out from the working medium outlet of the condenser 7 and is injected into the reinjection well 13.

[0043] Mode 2:

[0044] When the sunlight is insufficient, close the first stop valve 17 and the second stop valve 18, and open the third stop valve 19, the fourth stop valve 20, the throttle valve 21 and the fifth stop valve 22. The solar collector 14 heats the heat transfer medium. After the high-temperature heat transfer medium is pressurized by the first heat transfer medium pump 15, it is mixed with the high-temperature heat transfer medium from the heat storage device 16 and the third stop valve 19 and then enters the primary evaporator 5 together to heat the geothermal fluid; the heat transfer medium after heat exchange is pressurized by the second heat transfer medium pump 10, and part of it enters the heat storage device 16 through the fourth stop valve 20, and the other part is sent to the solar collector 14; the geothermal fluid enters the primary gas-liquid separator 1 from the production well 12 for flashing, and the saturated gaseous geothermal fluid obtained by flashing flows out from the steam outlet of the primary gas-liquid separator 1; the saturated liquid geothermal fluid flows out from the liquid outlet of the primary gas-liquid separator 1, and part of it is pressurized to the evaporation pressure by the geothermal fluid pump 4 and becomes subcooled liquid, and enters the working medium inlet of the primary evaporator 5; the other part is throttled and depressurized by the throttle valve 21 and then mixed with the saturated liquid geothermal fluid from the condenser 11 through the fifth stop valve 22 and then injected into the reinjection well together, so as to reduce the flow rate of the geothermal fluid, relieve the heat exchange burden of the solar collector, and improve the quality of the working steam as much as possible; other steps not involved are the same as those in Mode 1.

[0045] Mode 3:

[0046] When there is no sunlight, close the first stop valve 17 and the second stop valve 18, and open the third stop valve 19, the fourth stop valve 20, the throttle valve 21 and the fifth stop valve 22. The high-temperature heat storage medium in the heat storage device 16 heats the heat transfer medium. The high-temperature heat transfer medium enters the primary evaporator 5 through the third stop valve 19 to heat the geothermal fluid; the heat transfer medium after heat exchange is pressurized by the second heat transfer medium pump 10 and sent back to the heat storage device 16; the geothermal fluid enters the primary gas-liquid separator 1 from the production well 12 for flashing, and the saturated gaseous geothermal fluid obtained by flashing flows out from the steam outlet of the primary gas-liquid separator 1; the saturated liquid geothermal fluid flows out from the liquid outlet of the primary gas-liquid separator 1, and part of it is pressurized to the evaporation pressure by the geothermal fluid pump 4 and becomes subcooled liquid, and enters the working medium inlet of the primary evaporator 5; the other part is throttled and depressurized by the throttle valve 21 and then mixed with the saturated liquid geothermal fluid from the condenser 11 through the fifth stop valve 22 and then injected into the reinjection well together, so as to reduce the flow rate of the geothermal fluid, relieve the heat exchange burden of the heat storage device, and ensure the quality of the working steam as much as possible; other steps not involved are the same as those in Mode 1.

[0047] In this system, geothermal fluid at a temperature of 170°C and a mass flow rate of 50 kg / s enters the first-stage gas-liquid separator from the production well to complete the first-stage flash evaporation, and then successively enters the first-stage evaporator, the second-stage gas-liquid separator, the second-stage evaporator, the third-stage gas-liquid separator, and the third-stage evaporator; heat-conducting oil at a temperature of 390°C and a mass flow rate of 150 kg / s enters the first-stage evaporator, the second-stage evaporator, and the third-stage evaporator from the solar collector in sequence to heat the geothermal fluid; the isentropic efficiency of the expander is 85%; the mechanical friction efficiency is 98%; the power generation efficiency is 97%; the temperature of the first-stage flash evaporation is 100°C; the temperature of the second-stage flash evaporation is 140°C; the temperature of the third-stage flash evaporation is 110°C; the temperature of the first-stage evaporation is 200°C; the temperature of the second-stage evaporation is 140°C; the temperature of the third-stage evaporation is 110°C; the steam at each stage expands and does work in the expander, and finally a total power generation of approximately 23,809 kW is generated, which is about 6.8 times higher than the power generation of 3,046 kW obtained by only the work of the first-stage flash steam.

[0048] For the system process of Embodiment 1, Embodiment 2 can also achieve a similar function:

[0049] Embodiment 2

[0050] As Figure 2 shown, Embodiment 2 is a three-stage expansion power generation system derived from Embodiment 1.

[0051] In this embodiment, the process before and after the expansion link of the system is the same as that in Embodiment 1. The difference is that this embodiment adopts a power generation method in which three expanders expand and do work separately. The first expander is connected to the first generator, the second expander is connected to the second generator, the third expander is connected to the third generator, and the cooling water inlet and outlet of the condenser are connected to the external cooling water source.

[0052] The expansion process is as follows: The high-temperature and high-pressure saturated gaseous geothermal fluid flashed from the second-stage gas-liquid separator 6 enters the first-stage expander 27 through the steam outlet of the second-stage gas-liquid separator 6. After expanding and doing work in the first-stage expander 27, the geothermal fluid becomes a low-temperature and low-pressure steam-state geothermal fluid and is discharged; the medium-temperature and medium-pressure saturated gaseous geothermal fluid flashed from the third-stage gas-liquid separator 8 enters the second-stage expander 23 through the steam outlet of the third-stage gas-liquid separator 8. After expanding and doing work in the second-stage expander 23, the geothermal fluid becomes a low-temperature and low-pressure steam-state geothermal fluid and is discharged; the medium-temperature and medium-pressure saturated gaseous geothermal fluid in the third-stage evaporator 9 is discharged through the working medium outlet of the third-stage evaporator 9, and the low-temperature and low-pressure saturated gaseous geothermal fluid flashed from the first-stage gas-liquid separator 1 is discharged through the steam outlet of the first-stage gas-liquid separator 1. The two parts of saturated gaseous geothermal fluid are mixed and then enter the third-stage expander 25. After expanding and doing work in the third-stage expander 25, the geothermal fluid becomes a low-temperature and low-pressure steam-state geothermal fluid and is discharged; the low-temperature and low-pressure steam-state geothermal fluids at the outlets of the three expanders are mixed and then enter the condenser.

[0053] In this embodiment, three different expanders and their corresponding generators can be monitored and controlled separately to improve the reliability of system operation.

[0054] The effects of the inventive concept are not limited to the above effects, and those skilled in the art to which the inventive concept pertains should clearly understand the effects not mentioned from this specification and the drawings.

[0055] The above detailed description illustrates the inventive concept. In addition, the above content describes exemplary embodiments of the inventive concept, and the inventive concept can be used in a variety of other combinations, variations, and environments. That is to say, the inventive concept can be modified and revised as long as it does not depart from the scope of the inventive concept disclosed in the specification, the equivalent scope disclosed in writing, and / or the technical or knowledge scope of those skilled in the art. The written embodiments describe the best state for implementing the technical inspiration of the inventive concept, and various changes can be made according to the specific application field and the purpose of the inventive concept. In view of this, the detailed description of the inventive concept is not intended to limit the inventive concept in the state of the disclosed embodiments, but rather, should be construed as the appended claims including other embodiments.

Claims

1. A flash-based geothermal energy and solar energy coupled cascade power generation system, characterized in that it includes: Primary gas-liquid separator (1), expander (2), generator (3), geothermal fluid pump (4), primary evaporator (5), secondary gas-liquid separator (6), secondary evaporator (7), tertiary gas-liquid separator (8), tertiary evaporator (9), second heat transfer medium pump (10), condenser (11), solar collector (14), first heat transfer medium pump (15), heat storage device (16), first stop valve (17), second stop valve (18), third stop valve (19), fourth stop valve (20), throttle valve (21), fifth stop valve (22); The inlet of the solar collector (14) is respectively communicated with the outlet of the second stop valve (18), the inlet of the fourth stop valve (20), and the outlet of the second heat transfer medium pump (10), and the outlet of the solar collector (14) is communicated with the inlet of the first heat transfer medium pump (15); the outlet of the first heat transfer medium pump (15) is respectively communicated with the inlet of the first stop valve (17), the outlet of the third stop valve (19), and the heat source inlet of the primary evaporator (5), and the heat source outlet of the primary evaporator (5) is communicated with the heat source inlet of the secondary evaporator (7); The working fluid inlet of the primary evaporator (5) is communicated with the outlet of the geothermal fluid pump (4), and the working fluid outlet of the primary evaporator (5) is communicated with the inlet of the secondary gas-liquid separator (6); The heat storage device (16) is respectively communicated with the outlet of the first stop valve (17), the inlet of the second stop valve (18), the inlet of the third stop valve (19), and the outlet of the fourth stop valve (20); the inlet of the primary gas-liquid separator (1) is communicated with the production well (12), the steam outlet of the primary gas-liquid separator (1) is communicated with the second intermediate stage inlet of the expander (2), and the liquid outlet of the primary gas-liquid separator (1) is respectively communicated with the inlet of the throttle valve (21) and the inlet of the geothermal fluid pump (4); the outlet of the throttle valve (21) is communicated with the inlet of the fifth stop valve (22), and the outlet of the fifth stop valve (22) is communicated with the reinjection well (13); The steam outlet of the secondary gas-liquid separator (6) is communicated with the primary inlet of the expander (2), and the liquid outlet of the secondary gas-liquid separator (6) is communicated with the working medium inlet of the secondary evaporator (7); the working medium outlet of the secondary evaporator (7) is communicated with the inlet of the tertiary gas-liquid separator (8), and the heat source outlet of the secondary evaporator (7) is communicated with the heat source inlet of the tertiary evaporator (9); the steam outlet of the tertiary gas-liquid separator (8) is communicated with the first intermediate stage inlet of the expander (2), and the liquid outlet of the tertiary gas-liquid separator (8) is communicated with the working medium inlet of the tertiary evaporator (9); the working medium outlet of the tertiary evaporator (9) is communicated with the second intermediate stage inlet of the expander (2), and the heat source outlet of the tertiary evaporator (9) is communicated with the inlet of the second heat transfer medium pump (10); the expander (2) is connected with the generator (3), and the outlet of the expander (2) is communicated with the working medium inlet of the condenser (11); the working medium outlet of the condenser (11) is communicated with the reinjection well (13). The cooling water inlet and the cooling water outlet of the condenser (11) are communicated with an external cooling water source.

2. The flash-based geothermal energy and solar energy coupled cascade power generation system is characterized in that Comprising: a primary gas-liquid separator (1), a first expander (27), a first generator (28), a second expander (23), a second generator (24), a third expander (25), a third generator (26), a geothermal fluid pump (4), a primary evaporator (5), a secondary gas-liquid separator (6), a secondary evaporator (7), a tertiary gas-liquid separator (8), a tertiary evaporator (9), a second heat transfer medium pump (10), a condenser (11), a solar collector (14), a first heat transfer medium pump (15), a heat storage device (16), a first stop valve (17), a second stop valve (18), a third stop valve (19), a fourth stop valve (20), a throttle valve (21), a fifth stop valve (22). The inlet of the solar collector (14) is respectively communicated with the outlet of the second stop valve (18), the inlet of the fourth stop valve (20) and the outlet of the second heat transfer medium pump (10), and the outlet of the solar collector (14) is communicated with the inlet of the first heat transfer medium pump (15); the outlet of the first heat transfer medium pump (15) is respectively communicated with the inlet of the first stop valve (17), the outlet of the third stop valve (19) and the heat source inlet of the primary evaporator (5), and the heat source outlet of the primary evaporator (5) is communicated with the heat source inlet of the secondary evaporator (7). The working medium inlet of the primary evaporator (5) is communicated with the outlet of the geothermal fluid pump (4), and the working medium outlet of the primary evaporator (5) is communicated with the inlet of the secondary gas-liquid separator (6). The heat storage device (16) is respectively communicated with the outlet of the first stop valve (17), the inlet of the second stop valve (18), the inlet of the third stop valve (19) and the outlet of the fourth stop valve (20); the inlet of the primary gas-liquid separator (1) is communicated with the production well (12), the steam outlet of the primary gas-liquid separator (1) is communicated with the inlet of the third expander (25), and the liquid outlet of the primary gas-liquid separator (1) is respectively communicated with the inlet of the throttle valve (21) and the inlet of the geothermal fluid pump (4); the outlet of the throttle valve (21) is communicated with the inlet of the fifth stop valve (22), and the outlet of the fifth stop valve (22) is communicated with the reinjection well (13). The steam outlet of the secondary gas-liquid separator (6) is communicated with the inlet of the first expander (27), and the liquid outlet of the secondary gas-liquid separator (6) is communicated with the working medium inlet of the secondary evaporator (7); the working medium outlet of the secondary evaporator (7) is communicated with the inlet of the tertiary gas-liquid separator (8), and the heat source outlet of the secondary evaporator (7) is communicated with the heat source inlet of the tertiary evaporator (9); the steam outlet of the tertiary gas-liquid separator (8) is communicated with the inlet of the second expander (23), and the liquid outlet of the tertiary gas-liquid separator (8) is communicated with the working medium inlet of the tertiary evaporator (9); the working medium outlet of the tertiary evaporator (9) is communicated with the inlet of the third expander (25), and the heat source outlet of the tertiary evaporator (9) is communicated with the inlet of the second heat transfer medium pump (10); the outlets of the first expander (27), the second expander (23) and the third expander (25) are all communicated with the working medium inlet of the condenser (11); the working medium outlet of the condenser (11) is communicated with the reinjection well (13). The first expander (27) is connected to the first generator (28), the second expander (23) is connected to the second generator (24), the third expander (25) is connected to the third generator (26), and the cooling water inlet and the cooling water outlet of the condenser (11) are communicated with an external cooling water source.

3. A control method for a flash-based geothermal energy and solar energy coupled cascade power generation system according to claim 1, characterized in that, It includes the following steps: When there is sufficient sunlight, open the first stop valve (17) and the second stop valve (18), and close the third stop valve (19), the fourth stop valve (20), the throttle valve and the fifth stop valve. When there is insufficient sunlight or no sunlight, close the first stop valve (17) and the second stop valve (18), and open the third stop valve (19), the fourth stop valve (20), the throttle valve (21) and the fifth stop valve (22).

4. A control method for a flash-based geothermal energy and solar energy coupled cascade power generation system according to claim 2, characterized in that, It includes the following steps: When there is sufficient sunlight, open the first stop valve (17) and the second stop valve (18), and close the third stop valve (19), the fourth stop valve (20), the throttle valve (21) and the fifth stop valve (22). When there is insufficient sunlight or no sunlight, close the first shut-off valve (17) and the second shut-off valve (18), and open the third shut-off valve (19), the fourth shut-off valve (20), the throttle valve (21) and the fifth shut-off valve (22).

Images