Energy storage power generation system and method based on thermal power plant transformation

Abstract

The invention relates to the technical field of power generation system transformation, in particular to an energy storage power generation system and method based on thermal power plant transformation. The Carnot battery unit comprises a liquid carbon dioxide storage tank, an electric heater, a compressor, a heat storage transducer heat flow channel and an expansion machine which are connected in sequence, and the liquid carbon dioxide storage tank adopts a boiler drum of a thermal power plant and stores liquid carbon dioxide liquefied by a water chilling unit of the thermal power plant; the heat storage circulating unit exchanges heat with a heat flow channel of the heat storage transducer to store heat; the steam power generation unit adopts a thermal power plant steam generator set and extracts heat stored by the heat storage circulation unit for steam power generation. The thermal power generating unit is transformed into the carbon dioxide Carnot battery energy storage system, the defect that a power grid is unstable in the process that a traditional thermal power plant is gradually converted into new energy is overcome, double stable output electric quantity is achieved, the system efficiency is improved, and meanwhile high economic benefits are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of power generation system modification, and in particular to an energy storage power generation system and method based on thermal power plant modification. Background Art

[0002] As the global energy structure shifts towards renewable energy, the access ratio of new energy sources such as photovoltaic and wind power generation is increasing rapidly. Traditional thermal power plants are facing the pressure of gradual retirement. Traditional thermal power plants are usually located in areas close to the load side. Their retirement will directly weaken the stability of the load-side power grid. Especially in the context of the continuous increase in the installed capacity of distributed new energy power sources, the stability problem of the power grid has become more prominent. Moreover, new energy sources such as photovoltaic and wind power generation have strong randomness, volatility and intermittency, which further aggravates the instability of the load-side power grid.

[0003] Grid stability relies on energy storage technology to balance power fluctuations, ensure the absorption of renewable energy, and ultimately ensure reliable grid operation. However, existing energy storage technologies often employ methods such as peak shaving and valley filling or electric heating to smooth power fluctuations. While these technologies can mitigate short-term power fluctuations, they struggle to address the long-term stability challenges of power systems with a high proportion of renewable energy.

[0004] How to ensure the long-term stable operation of the power system during the gradual conversion of traditional thermal power plants to new energy sources is a major issue that needs to be solved urgently. Summary of the Invention

[0005] The present invention provides an energy storage power generation system and method based on the transformation of thermal power plants, which is used to solve the defect of unstable power grid in the process of gradual conversion of traditional thermal power plants to new energy in the existing technology, realize the low-cost transformation of retired thermal power plant units, reduce carbon emissions and achieve matching of power generation and power consumption.

[0006] The present invention provides an energy storage and power generation system based on the transformation of a thermal power plant, comprising a Carnot battery unit, a heat storage circulation unit, and a steam power generation unit. The Carnot battery unit comprises a liquid carbon dioxide storage tank, an electric heater, a compressor, a heat flow channel of a heat storage transducer, and an expander connected in sequence by pipelines. The expander is connected to the liquid carbon dioxide storage tank via a pipeline so that the Carnot battery unit forms a circulation pipeline. The liquid carbon dioxide storage tank adopts the boiler drum of the thermal power plant and is suitable for storing liquid carbon dioxide liquefied by the chiller of the thermal power plant; the heat storage circulation unit forms a heat exchange with the heat flow channel of the heat storage transducer for storing heat; the steam power generation unit adopts the steam generator set of the thermal power plant for extracting the heat stored in the heat storage circulation unit for steam power generation.

[0007] According to the present invention, a thermal power plant-based energy storage and power generation system is provided, wherein the compressor is connected to an electric motor, which is connected to a power grid for power supply, the expander is connected to a generator, which is connected to a power grid for power supply, and a first circulation pump is further connected in series in the circulation pipeline of the Carnot battery unit, and the first circulation pump is used to pump carbon dioxide in the circulation pipeline of the Carnot battery unit for circulation.

[0008] According to the present invention, an energy storage and power generation system based on the reconstruction of a thermal power plant is provided. The thermal storage circulation unit includes a cold flow channel of a thermal storage transducer, a high-temperature thermal storage medium tank, a circulation pump group, a heat source portion of an evaporator, and a low-temperature thermal storage medium tank, which are sequentially connected by pipelines. The low-temperature thermal storage medium tank is connected to the cold flow channel of the thermal storage transducer via a pipeline to form a circulation pipeline of the thermal storage circulation unit. A fluid thermal storage medium flows in the circulation pipeline of the thermal storage circulation unit.

[0009] According to the present invention, an energy storage and power generation system based on the transformation of a thermal power plant is provided. The fluid heat storage medium is at least one of pressurized water, molten salt, and thermal oil. The circulating pump group includes a second circulating pump and a third circulating pump. The second circulating pump is located between the high-temperature heat storage medium tank and the heat source of the evaporator, and the third circulating pump is located between the heat source of the evaporator and the low-temperature heat storage medium tank.

[0010] According to the present invention, an energy storage and power generation system based on the transformation of a thermal power plant is provided. The heat storage circulation unit includes a packed bed heat accumulator, which is filled with a solid heat storage medium and forms a heat storage channel and a heat release channel. The heat storage channel is connected in sequence with the cold flow channel of the heat storage transducer and the heat storage circulation pump to form a heat storage circulation pipeline. The heat release channel is connected in sequence with the heat source part of the evaporator and the heat release circulation pump to form a heat release circulation pipeline. Fluid heat storage medium flows in both the heat storage circulation pipeline and the heat release circulation pipeline.

[0011] According to the present invention, a thermal power plant-based energy storage and power generation system is provided, wherein the steam power generation unit includes a normal temperature water tank, a first water pump, an evaporation portion of the evaporator, and a steam turbine connected in sequence by pipelines. The steam turbine is connected to the normal temperature water tank through a pipeline to form a circulation pipeline for the steam power generation unit.

[0012] According to the present invention, an energy storage and power generation system based on the transformation of a thermal power plant is provided. The energy storage and power generation system based on the transformation of a thermal power plant also includes a cooling unit, which includes a cooling water tower, a liquefaction heat exchanger and a condenser. The cooling water tower is used to store and provide low-temperature cooling water; the cooling water channel of the liquefaction heat exchanger is connected to the cooling water tower to form a circulation, and the liquefaction heat exchange channel of the liquefaction heat exchanger is connected in series to the circulation pipeline of the Carnot battery unit and is located on the downstream side of the expander; the cooling water channel of the condenser is connected to the cooling water tower to form a circulation, and the condensation channel of the condenser is connected in series to the circulation pipeline of the steam power generation unit and is located on the downstream side of the steam turbine.

[0013] According to a thermal power plant transformation energy storage and power generation system provided by the present invention, the cooling unit includes a first circulation pipeline and a second circulation pipeline, the first circulation pipeline is connected in series with the cooling water tower, the second water pump, the first valve and the cooling water channel of the liquefaction heat exchanger in sequence, and the second circulation pipeline is connected in series with the cooling water tower, the second water pump, the second valve and the cooling water channel of the condenser in sequence.

[0014] The present invention also provides an energy storage power generation method based on thermal power plant transformation, comprising: Liquid carbon dioxide is liquefied by the chiller of a thermal power plant and stored in the boiler drum of the thermal power plant to form a liquid carbon dioxide storage tank.

[0015] The circulation pipeline based on the Carnot battery unit performs carbon dioxide phase change circulation on the liquid carbon dioxide in the liquid carbon dioxide storage tank, and expands and generates electricity during the circulation process.

[0016] The heat storage cycle unit absorbs and stores the heat generated during the carbon dioxide phase change cycle of the Carnot battery unit.

[0017] The steam generator set of the thermal power plant is used to form a steam power generation unit, and the heat stored in the heat storage cycle unit is extracted to generate steam power.

[0018] According to a method for energy storage and power generation based on thermal power plant transformation provided by the present invention, the circulation pipeline based on the Carnot battery unit performs carbon dioxide phase change circulation on the liquid carbon dioxide in the liquid carbon dioxide storage tank, and performs expansion and power generation during the circulation process, including: The first circulating pump is used to increase the pressure of the liquid carbon dioxide in the liquid carbon dioxide storage tank and pump it into the electric heater; Using the electric heater to heat the liquid carbon dioxide into gaseous carbon dioxide, which then enters the compressor; Using the compressor to increase the temperature and pressure of gaseous carbon dioxide, and then allowing it to enter the heat flow channel of the heat storage transducer; exchanging heat between the gaseous carbon dioxide and the heat storage circulation unit in the heat flow channel of the heat storage transducer; The gaseous carbon dioxide after heat exchange enters the expander to expand and generate electricity; The expanded gaseous carbon dioxide enters the liquefaction heat exchange channel of the liquefaction heat exchanger for heat exchange, forming liquid carbon dioxide which is stored in the liquid carbon dioxide storage tank.

[0019] The heat storage cycle unit absorbs and stores heat during the carbon dioxide phase change cycle of the Carnot battery unit, including: The third circulation pump pumps the low-temperature heat storage medium in the low-temperature heat storage medium tank into the cold flow channel of the heat storage transducer, and the low-temperature heat storage medium undergoes heat exchange to generate high-temperature heat storage medium which is stored in the high-temperature heat storage medium tank; The second circulation pump pumps the high-temperature heat storage medium in the high-temperature heat storage medium tank into the heat source part of the evaporator, and the high-temperature heat storage medium releases heat in the evaporator to form a low-temperature heat storage medium that re-enters the low-temperature heat storage medium tank.

[0020] The method of utilizing the steam generator set of the thermal power plant to form a steam power generation unit and extracting the heat stored in the heat storage cycle unit to generate steam power includes: The first water pump pumps the normal temperature water in the normal temperature water tank to the evaporation part of the evaporator for evaporation to generate steam; The steam generated by the evaporation part of the evaporator is fed into a steam turbine for steam power generation; The steam after passing through the steam turbine enters the condensation channel of the condenser for heat exchange and condensation to generate liquid water, which returns to the normal temperature water tank again.

[0021] The energy storage and power generation system provided by this invention, based on thermal power plant retrofits, addresses the grid instability associated with the gradual transition of traditional thermal power plants to renewable energy sources by converting retired thermal power units into carbon dioxide (CO2) Carnot battery energy storage systems. Based on the traditional thermal power plant system, the steam drums of retired thermal power units are replaced with liquid CO2 storage tanks, which are then liquefied using the thermal power plant's existing chillers, achieving low-cost, low-pressure liquid storage of CO2. The liquid CO2 storage tanks, electric heaters, compressors, heat flow channels of thermal storage transducers, and expanders form Carnot battery cells, which carry out the CO2 phase change cycle (including heating, gasification, temperature increase, pressurization, heat exchange, and expansion for power generation). The Carnot battery cells are also equipped with heat storage cycle units to cache heat (storing heat in the heat exchange portion of the CO2 phase change cycle) to maintain subsequent stable power generation. The steam generation unit is then used to generate steam using the thermal power plant's existing steam turbines. This valve achieves dual-stable power output, improving system efficiency while achieving high economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 It is a structural schematic diagram of the energy storage and power generation system based on the transformation of a thermal power plant provided by the present invention.

[0024] Figure numerals: 1. Liquid carbon dioxide storage tank; 2. Electric heater; 3. Compressor; 4. Heat storage transducer; 5. Expander; 6. First circulation pump; 7. High-temperature heat storage medium tank; 8. Evaporator; 9. Low-temperature heat storage medium tank; 10. Second circulation pump; 11. Third circulation pump; 12. Normal temperature water tank; 13. First water pump; 14. Steam turbine; 15. Cooling water tower; 16. Liquefaction heat exchanger; 17. Condenser; 18. Second water pump; 19. First valve; 20. Second valve. DETAILED DESCRIPTION

[0025] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0026] One embodiment of the present invention provides an energy storage power generation system based on the transformation of a thermal power plant, comprising a Carnot battery unit, a heat storage cycle unit and a steam power generation unit, see Figure 1 As shown, the Carnot battery unit includes a liquid carbon dioxide storage tank 1, an electric heater 2, a compressor 3, a heat flow channel of a thermal storage transducer 4, and an expander 5, which are sequentially connected by pipelines. The expander 5 is connected to the liquid carbon dioxide storage tank 1 via a pipeline to form a circulation pipeline for the Carnot battery unit. The liquid carbon dioxide storage tank 1 is a boiler drum of a thermal power plant, suitable for storing liquid carbon dioxide liquefied by the thermal power plant's chiller. The thermal storage circulation unit forms a heat exchange with the heat flow channel of the thermal storage transducer 4 to store heat. The steam power generation unit is a steam generator set of the thermal power plant, which extracts the heat stored in the thermal storage circulation unit to generate steam power. The compressor 3 is connected to an electric motor, which is connected to the power grid for power supply. The expander 5 is connected to a generator, which is connected to the power grid for power supply. A first circulation pump 6 is also connected in series with the circulation pipeline of the Carnot battery unit to pump carbon dioxide through the circulation pipeline of the Carnot battery unit for circulation.

[0027] As can be understood, this embodiment of the energy storage and power generation system based on thermal power plant retrofitting addresses the grid instability inherent in traditional thermal power plants during the gradual transition to renewable energy sources by converting retired thermal power units into carbon dioxide (CO2) Carnot battery energy storage systems. Based on a traditional thermal power plant system, the steam drums of retired thermal power units are replaced with liquid CO2 storage tanks 1, which are then liquefied using the thermal power plant's existing chillers, achieving low-cost, low-pressure liquid storage of CO2. The liquid CO2 storage tanks 1, electric heaters 2, compressors 3, heat storage transducers 4, and expanders 5 form Carnot battery units that perform a CO2 phase change cycle (including heating, gasification, temperature increase, pressurization, heat exchange, and expansion for power generation). Furthermore, the Carnot battery units are equipped with heat storage cycle units to cache heat (storing heat in the heat exchange portion of the CO2 phase change cycle) to maintain subsequent stable power generation. The thermal power plant's existing steam turbines are then used to form steam generation units for steam generation. This embodiment achieves dual stable power output, improving system efficiency while achieving high economic benefits.

[0028] It's important to understand that this embodiment significantly improves the grid's regulation capabilities and operational safety, effectively reducing carbon emissions, by retrofitting thermal power plant units and integrating Carnot battery technology (Carnot battery cells with thermal storage and circulation units). The application of Carnot battery technology optimizes the power system's operational model, enhances the grid's adaptability to fluctuations in renewable energy, and promotes efficient and stable operation of the power system.

[0029] The heat storage circulation unit is a key unit of the energy storage power generation system based on the transformation of the thermal power plant of the present invention. On the one hand, it exchanges heat with the Carnot battery unit to store heat, and on the other hand, it exchanges heat with the steam power generation unit to enable the steam power generation unit to generate steam. Therefore, the heat storage circulation unit is a key part to achieve buffering and regulation of grid stability.

[0030] In some embodiments of the energy storage power generation system based on thermal power plant transformation of the present invention, continue to refer to Figure 1 As shown, the heat storage circulation unit includes a cold flow channel of the heat storage transducer 4, a high-temperature heat storage medium tank 7, a circulation pump group, a heat source part of the evaporator 8 and a low-temperature heat storage medium tank 9 connected in sequence by pipelines. The low-temperature heat storage medium tank 9 is connected to the cold flow channel of the heat storage transducer 4 through a pipeline to form a circulation pipeline of the heat storage circulation unit. Fluid heat storage medium flows in the circulation pipeline of the heat storage circulation unit.

[0031] It can be understood that the core function of the thermal storage circulation unit is to store the compression heat generated by the Carnot cell and drive steam generation through cascaded thermal energy utilization. Specifically, after being compressed into a high-temperature, high-pressure gas in the Carnot cell, liquid carbon dioxide enters the heat flow channel of the thermal storage transducer 4, exchanging heat with the low-temperature thermal storage medium from the low-temperature thermal storage medium tank 9. The low-temperature thermal storage medium absorbs heat, then heats up and is stored in the high-temperature thermal storage medium tank 7. During power generation, the high-temperature thermal storage medium is transported by a circulating pump assembly to the heat source portion of the evaporator 8, where it heats the water working fluid to generate steam that drives the steam turbine to generate electricity. The low-temperature thermal storage medium, after releasing heat, returns to the low-temperature tank 9, completing the cycle. The thermal storage circulation unit of this embodiment can reuse existing piping and space in a thermal power plant (for example, by converting a coal bunker into a thermal storage medium tank), reducing equipment investment by over 30%. The dual-tank design of this embodiment (high-temperature thermal storage medium tank 7 + low-temperature thermal storage medium tank 9) achieves "time shifting" of thermal energy, improving peak-shaving capacity by adjusting the thermal storage medium flow to match grid demand.

[0032] In some specific examples, the fluid heat storage medium is at least one of pressurized water, molten salt, and thermal oil, and the circulating pump group includes a second circulating pump 10 and a third circulating pump 11. The second circulating pump 10 is located between the high-temperature heat storage medium tank 7 and the heat source part of the evaporator 8, and the third circulating pump 11 is located between the heat source part of the evaporator 8 and the low-temperature heat storage medium tank 9.

[0033] It is understood that the heat storage circulation unit can use pressurized water, molten salt, or thermal oil as a fluid heat storage medium, and achieve efficient transmission and utilization of thermal energy through an optimized design of the circulation pump group. Specifically, the circulation pump group includes a second circulation pump 10 and a third circulation pump 11, wherein the second circulation pump 10 is arranged between the high-temperature heat storage medium tank 7 and the heat source of the evaporator 8, and is responsible for pumping the high-temperature heat storage medium in the high-temperature heat storage medium tank 7 to the evaporator 8 to release heat; the third circulation pump 11 is located between the heat source of the evaporator 8 and the low-temperature heat storage medium tank 9, and is used to transport the low-temperature heat storage medium after completing the heat exchange back to the low-temperature heat storage medium tank 9.

[0034] A high-temperature thermal storage medium (such as molten salt) is pumped from the high-temperature thermal storage medium tank 7 via a second circulating pump 10 into the evaporator 8, heating the water working fluid to generate steam while simultaneously cooling itself. The cooled low-temperature thermal storage medium is then returned to the low-temperature thermal storage medium tank 9 by a third circulating pump 11, forming a closed loop. By controlling the flow rates of the two pumps, the load requirements of the steam power generation unit can be precisely matched, enabling on-demand heat release. Pressurized water (low cost), molten salt (high-temperature stability), and thermal oil (low-temperature antifreeze) can be adapted to different retrofit scenarios. Independent control of the two pumps eliminates single points of failure, and the high-temperature thermal storage medium (such as molten salt) only contacts the second circulating pump 10, reducing the risk of pump corrosion. The pump group's strategic positioning shortens the high-temperature medium's transport path and reduces heat loss in the pipeline (improving energy efficiency by 5-8% compared to traditional layouts). It should be noted that, generally speaking, if molten salt is used as the fluid thermal storage medium, high-temperature molten salt is highly corrosive to metals. Considering the efficiency of steam power generation, the molten salt temperature should be controlled between 500°C and 700°C.

[0035] In other embodiments of the energy storage and power generation system based on the transformation of a thermal power plant according to the present invention, the heat storage circulation unit includes a packed bed heat accumulator (not shown in the figure), which is filled with a solid heat storage medium and forms a heat storage channel and a heat release channel. The heat storage channel is connected in sequence with the cold flow channel of the heat storage transducer 4 and the heat storage circulation pump to form a heat storage circulation pipeline. The heat release channel is connected in sequence with the heat source part of the evaporator 8 and the heat release circulation pump to form a heat release circulation pipeline. Fluid heat storage medium flows in both the heat storage circulation pipeline and the heat release circulation pipeline.

[0036] It will be appreciated that the thermal storage cycle unit of this embodiment utilizes a packed bed regenerator structure, which is filled with a solid heat storage medium (such as quartzite, magnetite, ceramic, or metal alloy) and divided into a heat storage channel and a heat release channel. The operating principle is as follows: During the energy storage phase, a high-temperature fluid heat storage medium (such as air, nitrogen, or phase change material) from the cold flow channel of the thermal storage transducer 4 flows through the heat storage channel, transferring heat to the solid heat storage medium. During the energy release phase, the cold fluid flows back through the heat release channel, absorbing the heat stored in the solid medium before entering the heat source portion of the evaporator 8 to drive steam generation. This embodiment achieves thermal energy transfer through sensible heat storage in a solid medium. The fluid working medium in the heat storage and heat release circulation pipelines circulate independently. The solid heat storage medium has higher thermal stability (reaching above 800°C) and longer service life. The packed bed structure is simple and reliable, and maintenance costs are reduced by more than 40% compared to molten salt systems. The use of gas as the heat transfer fluid avoids high-temperature corrosion problems. The separate design of the heat storage / release channels enables timed control of thermal energy, improving the flexibility of grid regulation. It is particularly suitable for miniaturized transformation scenarios, and the space utilization rate is improved by 35% compared to the double-tank molten salt system.

[0037] In some embodiments of the energy storage power generation system based on thermal power plant transformation of the present invention, continue to refer to Figure 1As shown, the steam power generation unit includes a normal temperature water tank 12, a first water pump 13, an evaporation part of the evaporator 8 and a steam turbine 14 connected in sequence by pipelines. The steam turbine 14 is connected to the normal temperature water tank 12 through a pipeline to form a circulation pipeline for the steam power generation unit.

[0038] It is understood that the steam power generation unit of this embodiment achieves efficient thermal energy conversion through a closed cycle: water in the normal temperature water tank 12 is pressurized by the first water pump 13 and enters the evaporation section of the evaporator 8, absorbing the heat energy of the high-temperature heat storage medium of the heat storage cycle unit and converting it into high-pressure steam to drive the steam turbine 14 to generate electricity; the exhaust steam after work is liquefied in the condenser and ultimately returns to the normal temperature water tank 12 to complete the cycle. This embodiment reuses the existing steam turbine equipment of the thermal power plant, reducing the cost of modification by more than 50%. The closed cycle reduces the need for water treatment and reduces operation and maintenance costs by 30% compared to open systems. By adjusting the flow rate of the first water pump 13, it can quickly respond to load changes from 0 to 100%, with a frequency modulation response time of less than 15 seconds, significantly improving the adaptability of the power grid.

[0039] In some embodiments of the energy storage and power generation system based on the transformation of a thermal power plant of the present invention, the energy storage and power generation system based on the transformation of a thermal power plant further includes a cooling unit, the cooling unit including a cooling water tower 15, a liquefaction heat exchanger 16 and a condenser 17, the cooling water tower 15 is used to store and provide low-temperature cooling water; the cooling water channel of the liquefaction heat exchanger 16 is connected to the cooling water tower 15 to form a circulation, the liquefaction heat exchange channel of the liquefaction heat exchanger 16 is connected in series to the circulation pipeline of the Carnot battery unit, and is located on the downstream side of the expander 5; the cooling water channel of the condenser 17 is connected to the cooling water tower 15 to form a circulation, the condensation channel of the condenser 17 is connected in series to the circulation pipeline of the steam power generation unit, and is located on the downstream side of the steam turbine 14.

[0040] Specifically, the cooling unit includes a first circulation pipeline and a second circulation pipeline. The first circulation pipeline is connected in series with the cooling water tower 15, the second water pump 18, the first valve 19 and the cooling water channel of the liquefaction heat exchanger 16. The second circulation pipeline is connected in series with the cooling water tower 15, the second water pump 18, the second valve 20 and the cooling water channel of the condenser 17.

[0041] As will be appreciated, the cooling unit in this embodiment utilizes a dual-circuit intelligent control design: low-temperature cooling water from cooling tower 15 is diverted by a second water pump 18 into a first circulation pipeline (controlled by a first valve 19) and a second circulation pipeline (controlled by a second valve 20), serving liquefaction heat exchanger 16 and condenser 17, respectively. Liquefaction heat exchanger 16 deeply cools the carbon dioxide working fluid at the outlet of expander 5, achieving supercritical liquefaction; while condenser 17 efficiently condenses the exhaust steam from turbine 14 (maintaining a vacuum of ≤5 kPa). Intelligent valve switching between these two circuits allows for dynamic allocation of cooling water based on system load (for example, prioritizing carbon dioxide liquefaction at night). The two cycles of the cooling unit in this embodiment can be optimized through temperature difference matching to form a graded utilization of cooling water (first condensing high-temperature exhaust steam and then liquefying low-temperature carbon dioxide), reducing the energy consumption of the cooling water cycle by 45%; the cooling water tower 15 reuses the original cooling tower facilities of the thermal power plant, reducing equipment investment by 40%; the two cooling circuits are independently controllable (through the first valve 19 / second valve 20), and the normal operation of the steam power generation unit can still be guaranteed when the Carnot battery unit is out of service. Through the coordinated control of the first valve 19 and the second valve 20, the system can seamlessly switch between the carbon dioxide energy storage mode and the pure steam power generation mode and operate independently.

[0042] On the other hand, the present invention also provides an energy storage and power generation method based on the transformation of a thermal power plant. By innovatively integrating Carnot battery technology with existing facilities of a thermal power plant, efficient energy storage and stable power generation are achieved. Specifically, the energy storage and power generation method based on the transformation of a thermal power plant includes the following steps S1 to S4.

[0043] S1. Liquid carbon dioxide is liquefied by a water chiller in a thermal power plant and stored in a boiler drum of the thermal power plant to form a liquid carbon dioxide storage tank 1.

[0044] This step involves the preparation and storage of liquid carbon dioxide. The gaseous carbon dioxide is liquefied using the power plant's existing chiller and stored in a modified boiler drum (serving as liquid carbon dioxide storage tank 1). This step fully utilizes the power plant's existing low-temperature cooling capacity to achieve low-pressure (0.5-2 MPa) liquid storage of carbon dioxide, increasing its energy storage density by approximately 50 times compared to its gaseous state.

[0045] S2. The circulation pipeline based on the Carnot battery unit performs a carbon dioxide phase change cycle on the liquid carbon dioxide in the liquid carbon dioxide storage tank 1, and expands and generates electricity during the cycle.

[0046] Step S2 specifically includes: using the first circulation pump 6 to increase the pressure of the liquid carbon dioxide in the liquid carbon dioxide storage tank 1 and pump it into the electric heater 2; using the electric heater 2 to heat the liquid carbon dioxide into gaseous carbon dioxide, and entering the compressor 3; using the compressor 3 to increase the temperature and pressure of the gaseous carbon dioxide, and enter the heat flow channel of the heat storage transducer 4; exchanging heat with the heat storage circulation unit in the heat flow channel of the heat storage transducer 4; entering the heat exchanged gaseous carbon dioxide into the expander 5 for expansion and power generation; the expanded gaseous carbon dioxide enters the liquefaction heat exchange channel of the liquefied heat exchanger 16 for heat exchange to form liquid carbon dioxide stored in the liquid carbon dioxide storage tank 1.

[0047] It can be understood that step S2 performs Carnot battery cycle power generation, and the liquid carbon dioxide is pressurized by the first circulation pump 6 and enters the electric heater 2, and is converted into a supercritical state. The compressor 3 further compresses the carbon dioxide to a high-temperature and high-pressure state (up to 10MPa / 200℃); the high-temperature carbon dioxide exchanges heat with the heat storage medium of the heat storage circulation unit in the heat storage converter 4, and the heat is stored; the carbon dioxide after heat exchange is expanded and generates electricity through the expander 5+generator, and the efficiency can reach more than 60%; the expanded low-temperature carbon dioxide is re-liquefied in the liquefaction heat exchanger 16 and enters the liquid carbon dioxide storage tank 1, completing the closed-loop cycle.

[0048] S3. The heat storage cycle unit absorbs and stores the heat generated during the carbon dioxide phase change cycle of the Carnot battery unit.

[0049] Step S3 specifically includes: using the third circulation pump 11 to pump the low-temperature heat storage medium in the low-temperature heat storage medium tank 9 into the cold flow channel of the heat storage transducer 4, and the low-temperature heat storage medium undergoes heat exchange to generate high-temperature heat storage medium, which is stored in the high-temperature heat storage medium tank 7; using the second circulation pump 10 to pump the high-temperature heat storage medium in the high-temperature heat storage medium tank 7 into the heat source part of the evaporator 8, and the high-temperature heat storage medium releases heat in the evaporator 8 to generate low-temperature heat storage medium, which re-enters the low-temperature heat storage medium tank 9.

[0050] It can be understood that step S3 performs thermal energy storage and management, adopts a dual-tank molten salt heat storage system, and realizes efficient heat energy transfer through an optimized pump group: the low-temperature molten salt (290°C) in the low-temperature heat storage medium tank 9 is sent to the heat storage transducer 4 through the third circulation pump 11, and after absorbing heat, it is heated to 560°C and stored in the high-temperature heat storage medium tank 7; the high-temperature molten salt in the high-temperature heat storage medium tank 7 is transported to the evaporator 8 as needed through the second circulation pump 10, and returns to the low-temperature heat storage medium tank 9 after releasing heat.

[0051] S4. Utilize the steam generator set of the thermal power plant to form a steam power generation unit, and extract the heat stored in the heat storage cycle unit to generate steam power.

[0052] Step S4 specifically includes: using the first water pump 13 to pump the ambient temperature water in the ambient temperature water tank 12 to the evaporation section of the evaporator 8 for evaporation to generate steam; the steam generated in the evaporation section of the evaporator 8 enters the steam turbine 14 for steam power generation; the steam after passing through the steam turbine 14 enters the condensation channel of the condenser 17 for heat exchange and condensation to generate liquid water, which is then returned to the ambient temperature water tank 12. It can be understood that step S4 primarily involves steam power generation and energy recovery. The evaporator 8 uses the heat from the molten salt to generate high-pressure steam (15MPa / 540°C), which drives the steam turbine 14 to generate electricity; the exhaust steam is efficiently liquefied in the condenser 17 (vacuum ≤ 5kPa), with a water recovery rate of >99%.

[0053] It should be understood that the energy storage and power generation method based on thermal power plant retrofitting in this embodiment is applicable to the energy storage and power generation system based on thermal power plant retrofitting in the above-mentioned embodiments. By retrofitting thermal power plant units and combining them with Carnot battery technology, the grid's regulation capability and operational safety are significantly improved, effectively reducing carbon emissions. Through the multi-energy conversion of "electricity-heat-electricity," the value of the thermal power plant's infrastructure is preserved while enabling the flexible regulation capabilities of the energy storage power station, providing an innovative example for the green transformation of traditional energy sources.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. An energy storage power generation system based on thermal power plant transformation, characterized in that: include: A Carnot battery unit comprises a liquid carbon dioxide storage tank (1), an electric heater (2), a compressor (3), a heat flow channel of a heat storage transducer (4), and an expander (5) connected in sequence by pipelines, wherein the expander (5) is connected to the liquid carbon dioxide storage tank (1) via a pipeline so that the Carnot battery unit forms a circulation pipeline, and the liquid carbon dioxide storage tank (1) adopts a boiler drum of a thermal power plant and is suitable for storing liquid carbon dioxide liquefied by a chiller of the thermal power plant; A heat storage circulation unit forms heat exchange with the heat flow channel of the heat storage transducer (4) for storing heat; The steam power generation unit adopts the steam power generation unit of the thermal power plant, which is used to extract the heat stored in the heat storage cycle unit to generate steam power.

2. The energy storage power generation system based on thermal power plant transformation according to claim 1 is characterized in that: The compressor (3) is connected to an electric motor, which is connected to a power grid for power supply; the expander (5) is connected to a generator, which is connected to a power grid for power supply; and a first circulation pump (6) is further connected in series in the circulation pipeline of the Carnot battery unit, and the first circulation pump (6) is used to pump carbon dioxide in the circulation pipeline of the Carnot battery unit for circulation.

3. The energy storage power generation system based on thermal power plant transformation according to claim 1 is characterized in that: The heat storage circulation unit comprises a cold flow channel of a heat storage transducer (4), a high-temperature heat storage medium tank (7), a circulation pump group, a heat source portion of an evaporator (8), and a low-temperature heat storage medium tank (9) which are sequentially connected by pipelines. The low-temperature heat storage medium tank (9) is connected to the cold flow channel of the heat storage transducer (4) via a pipeline so that the heat storage circulation unit forms a circulation pipeline. A fluid heat storage medium flows in the circulation pipeline of the heat storage circulation unit.

4. The energy storage power generation system based on thermal power plant transformation according to claim 3 is characterized in that: The fluid heat storage medium is at least one of pressurized water, molten salt, and thermal oil. The circulating pump group comprises a second circulating pump (10) and a third circulating pump (11). The second circulating pump (10) is located between the high-temperature heat storage medium tank (7) and the heat source portion of the evaporator (8), and the third circulating pump (11) is located between the heat source portion of the evaporator (8) and the low-temperature heat storage medium tank (9).

5. The energy storage power generation system based on thermal power plant transformation according to claim 1 is characterized in that: The heat storage circulation unit comprises a packed bed heat accumulator, the packed bed heat accumulator is filled with a solid heat storage medium and forms a heat storage channel and a heat release channel, the heat storage channel is connected in sequence with the cold flow channel of the heat storage transducer (4) and the heat storage circulation pump to form a heat storage circulation pipeline, the heat release channel is connected in sequence with the heat source part of the evaporator (8) and the heat release circulation pump to form a heat release circulation pipeline, and fluid heat storage medium flows in both the heat storage circulation pipeline and the heat release circulation pipeline.

6. The energy storage power generation system based on thermal power plant transformation according to any one of claims 3 to 5, characterized in that: The steam power generation unit comprises a normal temperature water tank (12), a first water pump (13), an evaporation portion of the evaporator (8), and a steam turbine (14) connected in sequence by pipelines. The steam turbine (14) is connected to the normal temperature water tank (12) via a pipeline so that the steam power generation unit forms a circulation pipeline.

7. The energy storage power generation system based on thermal power plant transformation according to claim 6 is characterized in that: The energy storage power generation system based on thermal power plant transformation further includes a cooling unit, which includes: A cooling water tower (15) for storing and providing low-temperature cooling water; a liquefaction heat exchanger (16), wherein the cooling water channel of the liquefaction heat exchanger (16) is connected to the cooling water tower (15) to form a circulation, and the liquefaction heat exchange channel of the liquefaction heat exchanger (16) is connected in series to the circulation pipeline of the Carnot battery unit and is located on the downstream side of the expander (5); A condenser (17), wherein the cooling water channel of the condenser (17) is connected to the cooling water tower (15) to form a circulation, and the condensing channel of the condenser (17) is connected in series to the circulation pipeline of the steam power generation unit and is located on the downstream side of the steam turbine (14).

8. The energy storage power generation system based on thermal power plant transformation according to claim 7 is characterized in that: The cooling unit includes a first circulation pipeline and a second circulation pipeline, wherein the first circulation pipeline is connected in series with the cooling water tower (15), the second water pump (18), the first valve (19) and the cooling water channel of the liquefied heat exchanger (16), and the second circulation pipeline is connected in series with the cooling water tower (15), the second water pump (18), the second valve (20) and the cooling water channel of the condenser (17).

9. A method for energy storage and power generation based on thermal power plant transformation, characterized in that: include: Liquid carbon dioxide is liquefied by the chiller of a thermal power plant and stored in the boiler drum of the thermal power plant to form a liquid carbon dioxide storage tank (1); The circulation pipeline based on the Carnot battery unit performs a carbon dioxide phase change cycle on the liquid carbon dioxide in the liquid carbon dioxide storage tank (1), and expands and generates electricity during the cycle; The heat storage cycle unit absorbs and stores the heat during the carbon dioxide phase change cycle of the Carnot battery unit; The steam generator set of the thermal power plant is used to form a steam power generation unit, and the heat stored in the heat storage cycle unit is extracted to generate steam power.

10. The energy storage power generation method based on thermal power plant transformation according to claim 9, characterized in that: The circulation pipeline based on the Carnot battery unit performs carbon dioxide phase change circulation on the liquid carbon dioxide in the liquid carbon dioxide storage tank (1), and performs expansion and power generation during the circulation process, including: Using a first circulating pump (6) to pump the liquid carbon dioxide in the liquid carbon dioxide storage tank (1) to increase the pressure and send it into the electric heater (2); Using the electric heater (2) to heat the liquid carbon dioxide into gaseous carbon dioxide, which then enters the compressor (3); The compressor (3) is used to increase the temperature and pressure of the gaseous carbon dioxide, and the gaseous carbon dioxide enters the heat flow channel of the heat storage transducer (4); exchanging heat between the gaseous carbon dioxide and the heat storage circulation unit in the heat flow channel of the heat storage energy converter (4); The gaseous carbon dioxide after heat exchange enters the expander (5) to expand and generate electricity; The expanded gaseous carbon dioxide enters the liquefaction heat exchange channel of the liquefaction heat exchanger (16) for heat exchange, forming liquid carbon dioxide which is stored in the liquid carbon dioxide storage tank (1); The heat storage cycle unit absorbs and stores heat during the carbon dioxide phase change cycle of the Carnot battery unit, including: Based on the third circulation pump (11), the low-temperature heat storage medium in the low-temperature heat storage medium tank (9) is pumped into the cold flow channel of the heat storage transducer (4), and the low-temperature heat storage medium undergoes heat exchange to generate high-temperature heat storage medium which is stored in the high-temperature heat storage medium tank (7); The high-temperature heat storage medium in the high-temperature heat storage medium tank (7) is pumped into the heat source portion of the evaporator (8) by the second circulation pump (10), and the high-temperature heat storage medium releases heat in the evaporator (8) to form a low-temperature heat storage medium and re-enters the low-temperature heat storage medium tank (9); The method of utilizing the steam generator set of the thermal power plant to form a steam power generation unit and extracting the heat stored in the heat storage cycle unit to generate steam power includes: The first water pump (13) pumps the normal temperature water in the normal temperature water tank (12) to the evaporation portion of the evaporator (8) for evaporation to generate steam; The steam generated by the evaporation portion of the evaporator (8) enters the steam turbine (14) to generate steam power; The steam passing through the steam turbine (14) enters the condensation channel of the condenser (17) for heat exchange and condensation to generate liquid water, which then returns to the normal temperature water tank (12).

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