Supercritical carbon dioxide energy storage power generation system coupled with terrestrial heat and technological process thereof

Abstract

The invention discloses a supercritical carbon dioxide energy storage power generation system coupled with terrestrial heat and a technological process thereof. The supercritical carbon dioxide energy storage power generation system coupled with terrestrial heat comprises a shallow low-temperature underground gas storage chamber, a compressor, a deep high-temperature underground gas storage chamber and an expansion machine which are sequentially connected end to end through pipelines. The geothermal coupling supercritical carbon dioxide energy storage power generation system has an energy storage mode and a continuous power generation mode, not only can be used as an energy storage system to play a peak load shifting role on a power grid, but also can be used as a combined heat and power system to continuously supply power or heat or self-charge and supply heat in a switching mode. The system is simple and flexible, efficiently utilizes underground medium and low temperature geothermal energy, and is low in space site selection requirement and high in safety.

Description

Technical Field

[0001] The present application relates to the technical field of supercritical carbon dioxide cycle power generation, and in particular to a geothermal-coupled supercritical carbon dioxide energy storage power generation system and its process flow. Background Art

[0002] With the large-scale use of new energy sources such as wind power and solar energy, the consumption of traditional fossil energy can be slowed down to a certain extent, but at the same time, the intermittent and volatile characteristics of their power generation will have an impact on the power grid and bring new challenges. Energy storage technology is an important means to solve these problems and is of great significance for the optimization and regulation of energy systems. Among them, compression energy storage technology, as a new type of energy storage technology, stores energy by compressing the working medium. During the low electricity consumption period, it can use excess electricity to compress the working medium and store the energy; when the electricity consumption is at a peak, it will be released and the turbine will drive the generator to output electricity. It is a more efficient way of energy utilization.

[0003] Large-scale compressed energy storage technology usually requires a large medium storage space, which occupies a large area and is the main challenge for its current promotion. The developed oil and gas reservoirs have a huge storage volume and are located underground, which does not occupy the ground space, and is an ideal energy storage medium storage space. At the same time, the deep geological space has a high temperature and contains rich geothermal energy, which can also be used as an energy storage medium. The current mainstream energy storage medium is air, but when air is used for underground space energy storage, it has the following shortcomings:

[0004] 1) Air compression consumes a lot of energy and the energy storage conversion efficiency is not high.

[0005] 2) After the air is compressed, its temperature is high, and medium and low temperature geothermal energy cannot be used efficiently.

[0006] 3) Generally, a regenerator or supplementary combustion is required to improve the efficiency of the energy storage system, resulting in more equipment and a complex system.

[0007] 4) Air is oxidizing and may react with underground ores as well as combustible gases in oil and gas reservoirs. This places stringent requirements on the site selection of oil and gas reservoirs and poses great safety risks.

[0008] In this regard, some scholars have found that compared with the critical conditions of air (-141°C, 3.77MPa), the critical conditions of carbon dioxide (31°C, 7.38MPa) are easier to achieve, and supercritical carbon dioxide has good thermophysical properties such as low viscosity, high density, good fluidity, high heat transfer efficiency, low compression energy consumption and low temperature rise, low pipeline corrosion ability, non-polarity, and non-combustibility. Energy storage can be completed using small and simple impeller machinery and heat transfer units. At the same time, carbon dioxide has good thermal stability, non-toxicity, non-flammability, zero ozone consumption, cheap and easy to obtain and other potential environmental protection characteristics in engineering applications. It is very suitable for underground flow, storage and bringing out geothermal heat. Therefore, supercritical carbon dioxide can be used as an energy storage medium in underground space, and geothermal energy can also be efficiently utilized to design a supercritical carbon dioxide cycle energy storage, heating, and power generation integrated system coupled with geothermal heat.

[0009] The patent document with patent application number 201710964845.6 - "A compressed carbon dioxide energy storage system with dual underground gas storage chambers" discloses an energy storage system that uses carbon dioxide as a working medium, uses underground saline water layers as underground gas storage chambers to store carbon dioxide, and uses underground geothermal energy to heat the high-pressure carbon dioxide in the high-pressure gas storage chamber. However, the system still has a heater installed behind the high-pressure gas storage chamber, which requires external heating. The overall energy utilization rate is not high, and the system's operating mode is not easy to adjust.

[0010] Therefore, how to improve the technical defects existing in the prior art has always been a problem that ordinary technicians in this field need to solve urgently. Summary of the invention

[0011] The purpose of this application is to provide a geothermal-coupled supercritical carbon dioxide energy storage and power generation system and its process flow, which can collect deep geothermal heat without the need for additional heaters, and can also achieve multi-mode applications of energy storage, power generation, and heating, with better adjustability and higher overall energy efficiency.

[0012] The technical solution provided by the present invention is as follows:

[0013] A geothermal-coupled supercritical carbon dioxide energy storage power generation system comprises: a shallow low-temperature underground gas storage chamber, a compressor, a deep high-temperature underground gas storage chamber and an expander connected end to end via pipelines;

[0014] Wherein, a first shutoff valve is provided between the shallow low-temperature underground gas storage chamber and the compressor, a second shutoff valve is provided between the compressor and the deep high-temperature underground gas storage chamber, a third shutoff valve is provided between the deep high-temperature underground gas storage chamber and the expander, and a fourth shutoff valve is provided between the expander and the shallow low-temperature underground gas storage chamber;

[0015] The geothermal-coupled supercritical carbon dioxide energy storage and power generation system has an energy storage mode and a continuous power generation mode; in the energy storage mode, the first shut-off valve and the second shut-off valve are opened, and the third shut-off valve and the fourth shut-off valve are closed; or, the first shut-off valve and the second shut-off valve are closed, and the third shut-off valve and the fourth shut-off valve are opened;

[0016] In the continuous power generation mode, the first shut-off valve, the second shut-off valve, the third shut-off valve and the fourth shut-off valve are all opened.

[0017] In some embodiments, the energy storage mode has a low power consumption period and a peak power consumption period;

[0018] When the electricity consumption is at a low point, the first and second cut-off valves are opened, and the third and fourth cut-off valves are closed; when the electricity consumption is at a peak point, the first and second cut-off valves are closed, and the third and fourth cut-off valves are opened.

[0019] In some embodiments, the geothermal coupled supercritical carbon dioxide energy storage and power generation system further comprises:

[0020] The cooler is connected between the shallow low-temperature underground gas storage chamber and the compressor through a pipeline, and the first shut-off valve is arranged between the shallow low-temperature underground gas storage chamber and the cooler.

[0021] In some embodiments, the geothermal coupled supercritical carbon dioxide energy storage and power generation system further comprises:

[0022] The waste heat recovery device is connected between the expander and the shallow low-temperature underground gas storage chamber through a pipeline, and the fourth shut-off valve is arranged between the waste heat recovery device and the shallow low-temperature underground gas storage chamber.

[0023] In some embodiments, the pressure of the shallow low-temperature underground gas storage chamber is 7.5MPa-10MPa, and / or the pressure of the deep high-temperature underground gas storage chamber is 15MPa-25MPa.

[0024] In some embodiments, the temperature of the shallow low-temperature underground gas storage chamber is no greater than 45°C, and / or the temperature of the deep high-temperature underground gas storage chamber is greater than 100°C.

[0025] In some embodiments, a pressure regulating valve is provided at one end of the compressor connected to the shallow low-temperature underground gas storage chamber; and a pressure regulating valve is provided at one end of the expander connected to the deep high-temperature underground gas storage chamber.

[0026] In some embodiments, the expander is a variable expansion ratio expander.

[0027] The present application also provides a process flow of geothermal-coupled supercritical carbon dioxide energy storage power generation, which is applicable to the geothermal-coupled supercritical carbon dioxide energy storage power generation system provided in any of the above embodiments, including:

[0028] When the geothermal-coupled supercritical carbon dioxide energy storage power generation system is in energy storage mode, it has a low-consumption period and a peak-consumption period;

[0029] During the off-peak period of electricity consumption, the first shut-off valve and the second shut-off valve are controlled to be opened, and the third shut-off valve and the fourth shut-off valve are closed. The low-temperature and low-pressure supercritical carbon dioxide in the shallow low-temperature underground gas storage chamber enters the deep high-temperature underground gas storage chamber after being pressurized by the compressor, and the excess electrical energy is converted into internal energy and stored in the supercritical carbon dioxide. After the energy storage is completed, the first shut-off valve and the second shut-off valve are controlled to be closed; and,

[0030] During the peak period of electricity consumption, the first shut-off valve and the second shut-off valve are controlled to be closed, and the third shut-off valve and the fourth shut-off valve are opened. The high-temperature and high-pressure supercritical carbon dioxide in the deep high-temperature underground gas storage chamber is expanded and generates electricity by the expander and then enters the shallow low-temperature underground gas storage chamber. After the energy release is completed, the third shut-off valve and the fourth shut-off valve are controlled to be closed;

[0031] When the geothermal-coupled supercritical carbon dioxide energy storage and power generation system is in a continuous power generation mode, the first shut-off valve, the second shut-off valve, the third shut-off valve and the fourth shut-off valve are controlled to open, and the low-temperature and low-pressure supercritical carbon dioxide in the shallow low-temperature underground gas storage chamber enters the deep high-temperature underground gas storage chamber after being pressurized by the compressor, and becomes high-temperature and high-pressure carbon dioxide after absorbing geothermal energy. The high-temperature and high-pressure carbon dioxide becomes low-temperature and low-pressure supercritical carbon dioxide after being expanded and generated by the expander, and re-enters the shallow low-temperature underground gas storage chamber to form a thermodynamic cycle.

[0032] In some embodiments, the process flow of geothermally coupled supercritical carbon dioxide energy storage and power generation further includes: a cooler and a waste heat recovery device;

[0033] The cooler is located between the first shut-off valve and the compressor. When the geothermal-coupled supercritical carbon dioxide energy storage power generation system is in a low-power consumption period or a continuous power generation mode, the low-temperature and low-pressure supercritical carbon dioxide in the shallow low-temperature underground gas storage chamber is first cooled by the cooler and then pressurized by the compressor.

[0034] The waste heat recovery device is located between the expander and the fourth shut-off valve. When the geothermally coupled supercritical carbon dioxide energy storage and power generation system is in peak power consumption or continuous power generation mode, the high-temperature and high-pressure carbon dioxide in the deep high-temperature underground gas storage chamber is expanded and generated electricity by the expander, and then first produces hot water through the waste heat recovery device before entering the shallow low-temperature underground gas storage chamber.

[0035] The technical effects of this application are:

[0036] 1. In this application, supercritical carbon dioxide is used to realize compressed energy storage. The working fluid storage space is small, the requirements for underground space site selection are low, and it is easy to promote. At the same time, a shallow low-temperature underground gas storage chamber and a deep high-temperature underground gas storage chamber are set up. The supercritical carbon dioxide has a low temperature after compression and good flow and heat exchange. After entering the deep high-temperature underground gas storage chamber, a large amount of deep geothermal heat can be brought out. No additional heater is required, which greatly improves the efficiency of the energy storage system, and the electric-to-electric conversion efficiency is greater than 1. Moreover, the geothermal-coupled supercritical carbon dioxide energy storage power generation system in this application has an energy storage mode and a continuous power generation mode. It can be used as an energy storage system to play a role in peak shaving and valley filling for the power grid, and it can also switch modes as a cogeneration system to continuously supply power or heat to the outside or self-charge and heat. It has diverse functions, better adjustability, and higher overall energy efficiency.

[0037] 2. This application is provided with a cooler and a waste heat recovery device. The supercritical carbon dioxide is first cooled by the cooler and then compressed by the compressor, which can reduce the heat generated during compression, thereby reducing the temperature of the supercritical carbon dioxide after compression. The lower temperature can better utilize the lower temperature geothermal energy, and also help reduce energy loss during the compression process and improve the thermal efficiency of the system. Relatively speaking, supercritical carbon dioxide first generates electricity through an expander and then cools down through a waste heat recovery device. The waste heat recovery device can produce hot water, which not only improves the energy utilization efficiency, but also reduces energy consumption and environmental pollution, meeting the requirements of sustainable development. At the same time, it is also conducive to the thermal cycle of the supercritical carbon dioxide energy storage power generation system coupled with geothermal energy, and is highly practical.

[0038] 3. In the present application, one end of the compressor connected to the shallow low-temperature underground gas storage chamber, and one end of the expander connected to the deep high-temperature underground gas storage chamber, are both provided with pressure regulating valves to maintain a stable inlet pressure.

[0039] 4. In the present application, the expander adopts an expander with a variable expansion ratio, which can adjust the output power of the expander and the temperature of carbon dioxide at the outlet of the expander, thereby adjusting the output electrical energy and thermal energy, so that the user can adjust the ratio of electrical energy and thermal energy as needed, and the adjustability is better. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments:

[0041] Figure 1 It is a process flow chart of a geothermal-coupled supercritical carbon dioxide energy storage power generation system provided in one embodiment of the present application.

[0042] Description of Figure Numbers:

[0043] 1. Shallow low-temperature underground gas storage chamber; 2. Cooler; 3. Compressor; 4. Deep high-temperature underground gas storage chamber; 5. Expander; 6. Waste heat recovery device; 7. First shut-off valve; 8. Second shut-off valve; 9. Third shut-off valve; 10. Fourth shut-off valve; 11. Hot water. DETAILED DESCRIPTION

[0044] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

[0045] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the specific implementation methods of the present application will be described below with reference to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other accompanying drawings and other implementation methods can be obtained based on these drawings without creative work.

[0046] In order to simplify the drawings, only the parts related to the present application are schematically shown in each figure, and they do not represent the actual structure of the product. In addition, in order to simplify the drawings and facilitate understanding, in some figures, only one of the parts with the same structure or function is schematically drawn or marked. In this article, "one" not only means "only one", but also means "more than one".

[0047] It should be further understood that the term “and / or” used in the specification and appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0048] In this document, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0049] In the embodiments shown in the drawings, the indications of directions (such as up, down, left, right, front and back) used to explain the structure and movement of various components of the present application are not absolute but relative. These descriptions are appropriate when these components are in the positions shown in the drawings. If the descriptions of the positions of these components change, the indications of these directions also change accordingly.

[0050] In addition, in the description of the present application, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0051] According to a specific embodiment provided by this application, see Figure 1 , a geothermal-coupled supercritical carbon dioxide energy storage and power generation system, which utilizes supercritical carbon dioxide compression to store energy, can be applied to underground energy storage, geothermal energy utilization, supercritical carbon dioxide cycle power generation and other fields.

[0052] Supercritical carbon dioxide refers to a carbon dioxide fluid with a temperature exceeding 31°C and a pressure exceeding 7.38MPa. It has the characteristics of density close to that of liquid, viscosity close to that of gas, low corrosiveness, non-toxicity, non-flammability, stability, no damage to the ozone layer, and low cost and availability. In addition, supercritical carbon dioxide also has the advantages of low viscosity, high density, good fluidity, high heat transfer efficiency, low compression energy consumption, low temperature rise, low pipeline corrosion ability, non-polarity, and non-combustibility, making it very suitable for underground flow, storage, and removal of geothermal heat.

[0053] This embodiment uses supercritical carbon dioxide as the energy storage medium in the underground space, which can efficiently utilize geothermal energy and greatly improve the efficiency of the energy storage system. In addition, since the carbon dioxide storage space is small, it will not react with underground ore, does not support combustion, and has no risk of detonation, which is safer, has lower requirements for underground space site selection, and is easier to promote.

[0054] In an exemplary embodiment, a geothermal-coupled supercritical carbon dioxide energy storage power generation system includes a shallow low-temperature underground gas storage chamber 1, a compressor 3, a deep high-temperature underground gas storage chamber 4, and an expander 5, which are sequentially connected end to end via pipelines. Among them, a first shutoff valve 7 is provided between the shallow low-temperature underground gas storage chamber 1 and the compressor 3, a second shutoff valve 8 is provided between the compressor 3 and the deep high-temperature underground gas storage chamber 4, a third shutoff valve 9 is provided between the deep high-temperature underground gas storage chamber 4 and the expander 5, and a fourth shutoff valve 10 is provided between the expander 5 and the shallow low-temperature underground gas storage chamber 1.

[0055] The geothermal-coupled supercritical carbon dioxide energy storage power generation system provided in this embodiment has an energy storage mode and a continuous power generation mode. In the energy storage mode, the first shut-off valve 7 and the second shut-off valve 8 are opened, the third shut-off valve 9 and the fourth shut-off valve 10 are closed, and the system starts to store energy; or, the first shut-off valve 7 and the second shut-off valve 8 are closed, the third shut-off valve 9 and the fourth shut-off valve 10 are opened, and the system starts to release energy and generate electricity. In the continuous power generation mode, the first shut-off valve 7, the second shut-off valve 8, the third shut-off valve 9 and the fourth shut-off valve 10 are all opened, and the supercritical carbon dioxide circulates to absorb geothermal heat for continuous power generation.

[0056] Specifically, the energy storage mode has a low power consumption period and a peak power consumption period. During the low power consumption period, the first shut-off valve 7 and the second shut-off valve 8 are opened, the third shut-off valve 9 and the fourth shut-off valve 10 are closed, and the low-temperature and low-pressure supercritical carbon dioxide in the shallow low-temperature underground gas storage chamber 1 enters the deep high-temperature underground gas storage chamber 4 after being pressurized by the compressor 3, and the excess electrical energy is converted into internal energy and stored in the supercritical carbon dioxide. When the energy storage is completed, the first shut-off valve 7 and the second shut-off valve 8 are closed, and the third shut-off valve 9 and the fourth shut-off valve 10 continue to remain closed. During the peak power consumption period, the first shut-off valve 7 and the second shut-off valve 8 are closed, and the third shut-off valve 9 and the fourth shut-off valve 10 are opened, and the high-temperature and high-pressure supercritical carbon dioxide in the deep high-temperature underground gas storage chamber 4 enters the shallow low-temperature underground gas storage chamber 1 after being expanded and generated by the expander 5. During this process, the expander 5 outputs electricity to the outside. When the energy release is completed, the third shut-off valve 9 and the fourth shut-off valve 10 are closed, and the first shut-off valve 7 and the second shut-off valve 8 also continue to remain closed.

[0057] Relatively speaking, when in the continuous power generation mode, the first shut-off valve 7, the second shut-off valve 8, the third shut-off valve 9 and the fourth shut-off valve 10 are all opened, and the supercritical carbon dioxide in the shallow low-temperature underground gas storage chamber 1 is pressurized by the compressor 3 to become high-pressure low-temperature supercritical carbon dioxide. After the high-pressure low-temperature supercritical carbon dioxide enters the deep high-temperature underground gas storage chamber 4, it absorbs geothermal energy and becomes high-temperature high-pressure carbon dioxide. After the high-temperature and high-pressure carbon dioxide generates electricity through the expander 5, it becomes low-temperature and low-pressure supercritical carbon dioxide and re-enters the shallow low-temperature underground gas storage chamber 1, and the cycle repeats. During this process, the expander 5 continuously outputs electricity to the outside. The entire continuous power generation process forms a closed thermodynamic cycle, which continuously absorbs geothermal energy and supplies electricity and heat to the outside or the energy storage system self-charges and supplies heat.

[0058] This embodiment sets up a shallow low-temperature underground gas storage chamber 1 and a deep high-temperature underground gas storage chamber 4, supplemented by supercritical carbon dioxide as an energy storage medium. Since supercritical carbon dioxide has a low temperature after compression and good flow and heat transfer properties, it can bring out a large amount of deep geothermal heat after entering the deep high-temperature underground gas storage chamber 4, without the need for additional heaters, which greatly improves the efficiency of the energy storage system, and the electric-to-electric conversion efficiency is greater than 1. In addition, the geothermal-coupled supercritical carbon dioxide energy storage and power generation system in this application also has an energy storage mode and a continuous power generation mode. It can be used as an energy storage system to smooth out the peaks and fill the valleys of the power grid, and it can also switch modes as a combined heat and power system to continuously supply power or heat to the outside or self-charge and heat, realizing the integration of energy storage, heat supply, and power generation, with diverse functions, better adjustability, and higher overall energy efficiency.

[0059] Specifically, see Figure 1 The geothermal-coupled supercritical carbon dioxide energy storage and power generation system also includes a cooler 2, which is connected between the shallow low-temperature underground gas storage chamber 1 and the compressor 3 through a pipeline, and the above-mentioned first shut-off valve 7 is arranged between the shallow low-temperature underground gas storage chamber 1 and the cooler 2.

[0060] In this embodiment, the low-temperature and low-pressure supercritical carbon dioxide in the shallow low-temperature underground gas storage chamber 1 will first flow through the cooler 2 for cooling, and then enter the deep high-temperature underground gas storage chamber 4 after being pressurized by the compressor 3. This can reduce the heat generated during compression, thereby reducing the temperature of the supercritical carbon dioxide after compression, and the flow heat exchange is better. Moreover, the lower temperature also helps to reduce the energy loss during the compression process, further improving the thermal efficiency of the system.

[0061] Furthermore, the geothermally coupled supercritical carbon dioxide energy storage and power generation system also includes a waste heat recovery device 6, which is connected between the expansion machine 5 and the shallow low-temperature underground gas storage chamber 1 through a pipeline, and the fourth shut-off valve 10 is arranged between the waste heat recovery device 6 and the shallow low-temperature underground gas storage chamber 1.

[0062] In this embodiment, after the high-temperature and high-pressure supercritical carbon dioxide is expanded by the expander 5 to generate electricity, it is first cooled by the waste heat recovery device 6 and then enters the shallow low-temperature underground gas storage chamber 1. In this process, the waste heat recovery device 6 can produce hot water 11, which not only improves the energy utilization efficiency, but also reduces energy consumption and environmental pollution, meeting the requirements of sustainable development. In addition, the setting of the waste heat recovery device 6 is also conducive to the thermal cycle of the supercritical carbon dioxide energy storage power generation system coupled with geothermal energy, and has strong practicality.

[0063] Specifically, the pressure of the shallow low-temperature underground gas storage chamber 1, especially the pressure at the cave entrance, is preferably between 7.5MPa and 10MPa. In contrast, the pressure of the deep high-temperature underground gas storage chamber 4, especially the pressure at the cave entrance, is preferably between 15MPa and 25MPa. In addition, the temperature of the shallow low-temperature underground gas storage chamber 1 is preferably not greater than 45°C, and the temperature of the deep high-temperature underground gas storage chamber 4 is preferably greater than 100°C.

[0064] In a preferred embodiment, the compressor 3 is connected to one end of the shallow low-temperature underground gas storage chamber 1, and the expander 5 is connected to one end of the deep high-temperature underground gas storage chamber 4, and both are provided with pressure regulating valves. The pressure regulating valves can flexibly adjust the inlet pressure of the compressor 3 and the expander 5 so that the system can maintain a stable inlet pressure, which is beneficial to the thermal cycle of the geothermal-coupled supercritical carbon dioxide energy storage power generation system.

[0065] Furthermore, the expander 5 adopts an expander 5 with a variable expansion ratio. By adjusting the output power of the expander 5 and the temperature of carbon dioxide at the outlet of the expander 5, the output electrical energy and thermal energy can be adjusted, so that the user can adjust the ratio of electrical energy and thermal energy as needed, and the adjustability is better.

[0066] The geothermal coupled supercritical carbon dioxide energy storage power generation system disclosed in the present application (hereinafter referred to as the system) can efficiently utilize underground medium and low temperature geothermal energy by setting up a shallow low-temperature underground gas storage chamber 1 and a deep high-temperature underground gas storage chamber 4, supplemented by supercritical carbon dioxide as an energy storage medium, and has low spatial site selection requirements and high safety, without the need to set up additional equipment such as heat recovery or supplementary combustion. At the same time, the system is also provided with a plurality of shut-off valves, and the switching between the energy storage mode and the continuous power generation mode can be realized by opening and closing the corresponding shut-off valves as needed, so that the system can be used as an energy storage system to play a role in peak shaving and valley filling for the power grid, and can also switch modes as a combined heat and power system to continuously supply power or heat to the outside or self-charge and heat. In addition, the expander 5 in the present application adopts an expander 5 with a variable expansion ratio. By adjusting the size of its output electric energy and heat energy, the ratio of electric energy to heat energy can be adjusted, the adjustability is better, and the whole system is simpler and more flexible.

[0067] See also Figure 1The present application also discloses a process flow of geothermal-coupled supercritical carbon dioxide energy storage and power generation, which is applicable to the geothermal-coupled supercritical carbon dioxide energy storage and power generation system provided in any of the above embodiments.

[0068] When the system is in the low electricity consumption period, the first shut-off valve 7 and the second shut-off valve 8 are controlled to be opened, and the third shut-off valve 9 and the fourth shut-off valve 10 are closed. At this time, the low-temperature and low-pressure supercritical carbon dioxide in the shallow low-temperature underground gas storage chamber 1 enters the deep high-temperature underground gas storage chamber 4 after being pressurized by the compressor 3, and the excess electrical energy is converted into internal energy and stored in the supercritical carbon dioxide. After the energy storage is completed, the first shut-off valve 7 and the second shut-off valve 8 are controlled to be closed.

[0069] During the peak period of electricity consumption, the first shutoff valve 7 and the second shutoff valve 8 are controlled to be closed, and the third shutoff valve 9 and the fourth shutoff valve 10 are opened. At this time, the high-temperature and high-pressure supercritical carbon dioxide in the deep high-temperature underground gas storage chamber 4 is expanded by the expander 5 to generate electricity and then enters the shallow low-temperature underground gas storage chamber 1. After the energy release is completed, the third shutoff valve 9 and the fourth shutoff valve 10 are controlled to be closed.

[0070] When in the continuous power generation mode, the first shut-off valve 7, the second shut-off valve 8, the third shut-off valve 9 and the fourth shut-off valve 10 are controlled to open, and the low-temperature and low-pressure supercritical carbon dioxide in the shallow low-temperature underground gas storage chamber 1 is pressurized by the compressor 3 and enters the deep high-temperature underground gas storage chamber 4, and becomes high-temperature and high-pressure carbon dioxide after absorbing geothermal energy. The high-temperature and high-pressure carbon dioxide is expanded and generated by the expander 5 to become low-temperature and low-pressure supercritical carbon dioxide, and re-enters the shallow low-temperature underground gas storage chamber 1 to form a thermal cycle.

[0071] In a specific embodiment, the system further includes a cooler 2 and a waste heat recovery device 6 , wherein the cooler 2 is located between the first shut-off valve 7 and the compressor 3 , and the waste heat recovery device 6 is located between the expander 5 and the fourth shut-off valve 10 .

[0072] When the system is in a period of low electricity consumption, the low-temperature and low-pressure supercritical carbon dioxide in the shallow low-temperature underground gas storage chamber 1 is first cooled by the cooler 2, then pressurized by the compressor 3, and then enters the deep high-temperature underground gas storage chamber 4, converting excess electrical energy into internal energy and storing it in the supercritical carbon dioxide.

[0073] During the peak period of electricity consumption, the high-temperature and high-pressure supercritical carbon dioxide in the deep high-temperature underground gas storage chamber 4 is expanded by the expander 5 to generate electricity, and then expands by the expander 5 to generate electricity, and then enters the shallow low-temperature underground gas storage chamber 1. In this process, the expander 5 outputs electricity to the outside, and the waste heat recovery device 6 produces hot water 11.

[0074] When in continuous power generation mode, the low-temperature, low-pressure supercritical carbon dioxide in the shallow low-temperature underground gas storage chamber 1 is first cooled by the cooler 2, then pressurized by the compressor 3, and enters the deep high-temperature underground gas storage chamber 4. After absorbing geothermal heat, it becomes high-temperature, high-pressure carbon dioxide. The high-temperature, high-pressure carbon dioxide is successively generated by the expander 5, and heat is supplied to the waste heat recovery device 6 for cooling, and then becomes low-temperature, low-pressure supercritical carbon dioxide, and re-enters the shallow low-temperature underground gas storage chamber 1. In this process, the expander 5 continuously outputs electricity to the outside, and the waste heat recovery device 6 continuously produces hot water 11. The whole process forms a closed thermal cycle, continuously absorbing geothermal heat and supplying electricity and heat to the outside.

[0075] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0076] It should be noted that the above embodiments can be freely combined as needed. The above are only preferred implementations of this application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of this application, and these improvements and modifications should also be regarded as the protection scope of this application.

Claims

1. A geothermal coupled supercritical carbon dioxide energy storage power generation system, characterized in that: include: A shallow low-temperature underground gas storage chamber, a compressor, a deep high-temperature underground gas storage chamber and an expander connected end to end via pipelines; Wherein, a first shutoff valve is provided between the shallow low-temperature underground gas storage chamber and the compressor, a second shutoff valve is provided between the compressor and the deep high-temperature underground gas storage chamber, a third shutoff valve is provided between the deep high-temperature underground gas storage chamber and the expander, and a fourth shutoff valve is provided between the expander and the shallow low-temperature underground gas storage chamber; The geothermal-coupled supercritical carbon dioxide energy storage and power generation system has an energy storage mode and a continuous power generation mode; in the energy storage mode, the first shut-off valve and the second shut-off valve are opened, and the third shut-off valve and the fourth shut-off valve are closed; or, the first shut-off valve and the second shut-off valve are closed, and the third shut-off valve and the fourth shut-off valve are opened; In the continuous power generation mode, the first shut-off valve, the second shut-off valve, the third shut-off valve and the fourth shut-off valve are all opened.

2. The geothermal coupled supercritical carbon dioxide energy storage power generation system according to claim 1, characterized in that: The energy storage mode has a low power consumption period and a peak power consumption period; When the electricity consumption is at a low point, the first and second cut-off valves are opened, and the third and fourth cut-off valves are closed; when the electricity consumption is at a peak point, the first and second cut-off valves are closed, and the third and fourth cut-off valves are opened.

3. The geothermal coupled supercritical carbon dioxide energy storage power generation system according to claim 1 or 2, characterized in that: Also includes: The cooler is connected between the shallow low-temperature underground gas storage chamber and the compressor through a pipeline, and the first shut-off valve is arranged between the shallow low-temperature underground gas storage chamber and the cooler.

4. The geothermal coupled supercritical carbon dioxide energy storage power generation system according to claim 1 or 2, characterized in that: Also includes: The waste heat recovery device is connected between the expander and the shallow low-temperature underground gas storage chamber through a pipeline, and the fourth shut-off valve is arranged between the waste heat recovery device and the shallow low-temperature underground gas storage chamber.

5. The geothermal coupled supercritical carbon dioxide energy storage power generation system according to claim 1 or 2, characterized in that: The pressure of the shallow low-temperature underground gas storage chamber is 7.5MPa-10MPa, and / or the pressure of the deep high-temperature underground gas storage chamber is 15MPa-25MPa.

6. The geothermal coupled supercritical carbon dioxide energy storage power generation system according to claim 1 or 2, characterized in that: The temperature of the shallow low-temperature underground gas storage chamber is not greater than 45°C, and / or the temperature of the deep high-temperature underground gas storage chamber is greater than 100°C.

7. The geothermal coupled supercritical carbon dioxide energy storage power generation system according to claim 1 or 2, characterized in that: A pressure regulating valve is provided at one end of the compressor connected to the shallow low-temperature underground gas storage chamber; and a pressure regulating valve is provided at one end of the expander connected to the deep high-temperature underground gas storage chamber.

8. The geothermal coupled supercritical carbon dioxide energy storage power generation system according to claim 1 or 2, characterized in that: The expander is an expander with a variable expansion ratio.

9. A process flow of geothermal-coupled supercritical carbon dioxide energy storage power generation, applicable to the geothermal-coupled supercritical carbon dioxide energy storage power generation system according to any one of claims 1 to 8, characterized in that: include: When the geothermal-coupled supercritical carbon dioxide energy storage power generation system is in energy storage mode, it has a low-consumption period and a peak-consumption period. During the off-peak period of electricity consumption, the first shut-off valve and the second shut-off valve are controlled to be opened, and the third shut-off valve and the fourth shut-off valve are closed. The low-temperature and low-pressure supercritical carbon dioxide in the shallow low-temperature underground gas storage chamber enters the deep high-temperature underground gas storage chamber after being pressurized by the compressor, and the excess electrical energy is converted into internal energy and stored in the supercritical carbon dioxide. After the energy storage is completed, the first shut-off valve and the second shut-off valve are controlled to be closed; and, During the peak period of electricity consumption, the first shut-off valve and the second shut-off valve are controlled to be closed, and the third shut-off valve and the fourth shut-off valve are opened. The high-temperature and high-pressure supercritical carbon dioxide in the deep high-temperature underground gas storage chamber is expanded and generates electricity by the expander and then enters the shallow low-temperature underground gas storage chamber. After the energy release is completed, the third shut-off valve and the fourth shut-off valve are controlled to be closed; When the geothermal-coupled supercritical carbon dioxide energy storage and power generation system is in a continuous power generation mode, the first shut-off valve, the second shut-off valve, the third shut-off valve and the fourth shut-off valve are controlled to open, and the low-temperature and low-pressure supercritical carbon dioxide in the shallow low-temperature underground gas storage chamber enters the deep high-temperature underground gas storage chamber after being pressurized by the compressor, and becomes high-temperature and high-pressure carbon dioxide after absorbing geothermal energy. The high-temperature and high-pressure carbon dioxide becomes low-temperature and low-pressure supercritical carbon dioxide after being expanded and generated by the expander, and re-enters the shallow low-temperature underground gas storage chamber to form a thermodynamic cycle.

10. The process flow of geothermal coupled supercritical carbon dioxide energy storage and power generation according to claim 9, characterized in that: Also includes: cooler and waste heat recovery device; The cooler is located between the first shut-off valve and the compressor. When the geothermal-coupled supercritical carbon dioxide energy storage power generation system is in a low-power consumption period or a continuous power generation mode, the low-temperature and low-pressure supercritical carbon dioxide in the shallow low-temperature underground gas storage chamber is first cooled by the cooler and then pressurized by the compressor. The waste heat recovery device is located between the expander and the fourth shut-off valve. When the geothermally coupled supercritical carbon dioxide energy storage and power generation system is in peak power consumption or continuous power generation mode, the high-temperature and high-pressure carbon dioxide in the deep high-temperature underground gas storage chamber is expanded and generated electricity by the expander, and then first produces hot water through the waste heat recovery device before entering the shallow low-temperature underground gas storage chamber.

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