Compressed carbon dioxide energy storage system coupled with groove type heat collector and adsorption type refrigeration

Abstract

The invention relates to a compressed carbon dioxide energy storage system coupled with a trough type heat collector and adsorption type refrigeration. The compressed carbon dioxide energy storage system comprises a storage unit, an acting unit and a heat exchange unit. The storage unit comprises a gaseous carbon dioxide storage device, a compressor, a heat exchanger, a carbon dioxide liquefier and a liquid carbon dioxide storage device which are communicated in sequence; the acting unit comprises a carbon dioxide gasifier, a reheater and a carbon dioxide expansion machine which are sequentially communicated from the liquid carbon dioxide storage device; the heat exchange unit comprises a low-temperature water storage tank, a high-temperature water storage tank, an adsorption type refrigeration device and a medium-temperature water storage tank, low-temperature water in the low-temperature water storage tank enters the high-temperature water storage tank after being heated by the heat exchanger, and high-temperature water in the high-temperature water storage tank enters the adsorption type refrigeration device; cold water produced by the adsorption type refrigeration device enters the carbon dioxide liquefier to achieve liquefaction of carbon dioxide, hot water produced by the adsorption type refrigeration device enters the medium-temperature water storage tank, and hot water in the medium-temperature water storage tank enters the carbon dioxide gasifier to achieve gasification of liquid carbon dioxide.

Description

Technical Field

[0001] This invention relates to the field of energy storage system technology, specifically to a compressed carbon dioxide energy storage system that combines a coupled trough-type solar collector and adsorption refrigeration. Background Technology

[0002] Currently, compressed carbon dioxide energy storage technology has received widespread attention due to its advantages such as environmental friendliness and long storage cycle, but its overall efficiency and economy are still limited by the following technical bottlenecks: 1. Insufficient recovery of waste heat from compression Traditional carbon dioxide energy storage systems generate a large amount of low- to medium-temperature waste heat (typically 80–150°C) during the compression phase. Existing technologies mostly use simple heat exchangers for heat dissipation, failing to effectively recover this waste heat and resulting in significant energy waste. For example, Reference 1 (Energy Storage Science and Technology, 2020) points out that waste heat from carbon dioxide compression accounts for 25%–30% of the system's total energy consumption, and direct emissions lead to an electricity-to-electricity conversion efficiency (RTE) of less than 65%.

[0003] Although some scholars have proposed using waste heat to drive organic Rankine cycle (ORC) power generation, the system is complex and the power generation efficiency is less than 10% in the low temperature range (<100℃), resulting in poor economic efficiency.

[0004] 2. Liquefaction cooling consumes a lot of energy. Some existing carbon dioxide liquefaction technologies rely on mechanical refrigeration, which requires additional electrical energy to drive the compressor, further reducing system efficiency. For example, Reference 2 (Applied Energy, 2021) shows that the traditional liquefaction process accounts for 15% to 20% of the total energy consumption of energy storage, and the investment cost of cryogenic cooling equipment (such as chillers) accounts for more than 30%.

[0005] 3. Insufficient preheating of the working fluid during the expansion stage Existing carbon dioxide energy storage systems mostly use electric heating or gas-fired supplemental combustion to preheat the inlet working fluid of the expander, leading to increased carbon emissions or dependence on external energy sources. For example, Reference 3 (Energy Conversion and Management, 2022) shows that the net efficiency of the system decreases by 5% to 8% under the electric heating preheating mode.

[0006] 4. Poor synergy among renewable energy sources Although some technologies have attempted to combine solar energy (such as some scholars proposing photovoltaic-driven compressors), the cascade utilization of solar energy and waste heat has not been realized, and the photovoltaic-energy storage conversion efficiency is limited (photovoltaic efficiency 15%~20%). Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a compressed carbon dioxide energy storage system that combines a coupled trough-type solar collector and adsorption-type refrigeration.

[0008] This invention is achieved through the following technical solution: a compressed carbon dioxide energy storage system combining a coupled trough solar collector and adsorption refrigeration, comprising a storage unit, a power unit, and a heat exchange unit; the storage unit includes a gaseous carbon dioxide storage device, a compressor, a heat exchanger, a carbon dioxide liquefaction device, and a liquid carbon dioxide storage device connected in sequence; the power unit includes a carbon dioxide vaporizer, a reheater, and a carbon dioxide expander connected in sequence from the liquid carbon dioxide storage device; the heat exchange unit includes a low-temperature water storage tank, a high-temperature water storage tank, an adsorption refrigeration device, and a medium-temperature water storage tank. Low-temperature water in the low-temperature water storage tank is heated by the heat exchanger and then enters the high-temperature water storage tank. High-temperature water in the high-temperature water storage tank enters the adsorption refrigeration device. Cold water produced by the adsorption refrigeration device enters the carbon dioxide liquefaction device to liquefy carbon dioxide. Hot water produced by the adsorption refrigeration device enters the medium-temperature water storage tank. Hot water in the medium-temperature water storage tank enters the carbon dioxide vaporizer to vaporize liquid carbon dioxide.

[0009] As an optimization, carbon dioxide is heated by hot water output from the parabolic trough solar collector as it flows through the reheater.

[0010] As an optimization, multiple compressors and heat exchangers are provided, and the compressors and heat exchangers are arranged alternately in series.

[0011] As an optimization, multiple reheaters and carbon dioxide expanders are provided, and the reheaters and carbon dioxide expanders are arranged alternately in series.

[0012] As an optimization, carbon dioxide enters the carbon dioxide liquefaction unit in a supercritical state.

[0013] As an optimization, the hot water in the medium-temperature water storage tank flows through the carbon dioxide vaporizer and is then cooled by the cooling tower before entering the low-temperature water storage tank.

[0014] As an optimization, the cold water produced by the adsorption refrigeration device can be supplied to external cooling systems.

[0015] As an optimization, the hot water in the medium-temperature water storage tank is used for external heating.

[0016] As an optimization, the carbon dioxide discharged from the carbon dioxide expander is returned to the gaseous carbon dioxide storage device.

[0017] As an optimization, the adsorption refrigeration device adopts a zeolite-water adsorption refrigeration device.

[0018] The beneficial effects of this invention are as follows: By rationally configuring the system, this invention fully utilizes the waste heat from the compression process and couples it with a parabolic trough solar collector to utilize solar energy, achieving combined power, cooling, and heating, thus improving the overall energy utilization efficiency and electro-electricity conversion efficiency of compressed carbon dioxide energy storage. It increases the system's electro-electricity conversion efficiency to over 70%. It reduces cooling energy consumption and eliminates additional power consumption. By utilizing a parabolic trough solar collector to collect and utilize clean energy sources such as solar energy, the overall energy efficiency is improved. It does not introduce fossil fuels, achieving zero-carbon operation of the energy storage process. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the present invention; As shown in the figure: 1. Gaseous carbon dioxide storage device; 2. Compressor; 3. Heat exchanger; 4. Carbon dioxide liquefaction device; 5. Low temperature water storage tank; 6. High temperature water storage tank; 7. Adsorption refrigeration device; 8. Medium temperature water storage tank; 9. Liquid carbon dioxide storage device; 10. Parabolic trough solar collector; 11. Carbon dioxide vaporizer; 12. Reheater; 13. Carbon dioxide expander; 14. Cooling tower; 15. External cooling unit; 16. External heating unit. Detailed Implementation

[0020] To clearly illustrate the technical features of this solution, the following detailed implementation method will be used to explain the solution.

[0021] Example 1: like Figure 1 As shown, the coupled trough type solar collector and adsorption-cooled compressed carbon dioxide energy storage system of the present invention includes a storage unit, a power unit and a heat exchange unit.

[0022] The storage unit includes a gaseous carbon dioxide storage device 1, a compressor 2, a heat exchanger 3, a carbon dioxide liquefaction device 4, and a liquid carbon dioxide storage device 9 connected in sequence. There are multiple compressors 2 and heat exchangers 3, and the compressors 2 and heat exchangers 3 are arranged alternately in series. In this embodiment, there are 5 compressors 2 and 5 heat exchangers 3. The gaseous carbon dioxide is compressed 5 times. After each compression, the temperature is reduced by the heat exchanger 3.

[0023] Carbon dioxide, after five compressions, is in a supercritical state, a special type of fluid. Near the critical point, it exhibits high compressibility; by appropriately increasing the pressure, its density can be brought close to that of a typical liquid. On the other hand, the viscosity of the supercritical state is only 1 / 12 to 1 / 4 that of a typical liquid, but its diffusion coefficient is 7 to 24 times greater, approximating that of a gas.

[0024] Near the critical point (31°C, 7.38 MPa), the high density of supercritical carbon dioxide is close to that of a liquid (approximately 500 kg / m³).3 The concentration of oxygen is much higher than that of air (approximately 1.2 kg / m³ at normal temperature and pressure). 3 For the same energy, the volume of a carbon dioxide storage tank is only 1 / 10 to 1 / 20 that of compressed air, making it suitable for scenarios with limited land. Furthermore, supercritical carbon dioxide has good fluidity.

[0025] Supercritical carbon dioxide enters carbon dioxide liquefaction unit 4 for cooling and liquefaction. The temperature after cooling is 25-30℃, and the liquid carbon dioxide enters liquid carbon dioxide storage unit 9 for storage.

[0026] The working unit includes a carbon dioxide vaporizer 11, a reheater 12, and a carbon dioxide expander 13 connected in sequence from the liquid carbon dioxide storage device 9; that is, the liquid carbon dioxide in the carbon dioxide storage device 9 flows through the carbon dioxide vaporizer 11, the reheater 12, and the carbon dioxide expander 13 in sequence.

[0027] The carbon dioxide vaporizer 11 vaporizes and preheats liquid carbon dioxide. The parabolic trough solar collector 10 heats the water using solar energy. As the carbon dioxide flows through the reheater 12, it is heated by the hot water output from the parabolic trough solar collector 10. The water is then recycled back to the parabolic trough solar collector 10. After being heated by the reheater 12, the gaseous carbon dioxide enters the multi-stage carbon dioxide expander 13 to expand and generate electricity. After completing its work, the exhaust gas pressure is 0.1-0.11 MPa and enters the gaseous carbon dioxide storage device 1.

[0028] Multiple reheaters 12 and carbon dioxide expanders 13 are provided, and the reheaters 12 and carbon dioxide expanders 13 are arranged alternately in series. In this embodiment, there are 3 reheaters 12 and 3 carbon dioxide expanders 13, realizing three heating and three work operations.

[0029] The heat exchange unit includes a low-temperature water storage tank 5, a high-temperature water storage tank 6, an adsorption refrigeration device 7, and a medium-temperature water storage tank 8. The low-temperature water in the low-temperature water storage tank 5 is heated five times by five heat exchangers 3 and then enters the high-temperature water storage tank 6 for storage. The high-temperature water in the high-temperature storage tank 6 enters the adsorption refrigeration device 7. In this embodiment, the adsorption refrigeration device 7 is a zeolite-water adsorption refrigeration device. The working fluid pair used is a zeolite-water working fluid pair. The adsorption-desorption process is reversible, the desorption temperature is 80~150℃, heat is released during adsorption, and heat is absorbed during desorption.

[0030] The cold water produced by the adsorption refrigeration device 7 enters the carbon dioxide liquefaction unit 4 to liquefy carbon dioxide. In addition, the cold water produced by the adsorption refrigeration device 7 can also be connected to the external cooling unit 15 to provide external cooling.

[0031] The hot water produced by the adsorption refrigeration unit 7 enters the medium-temperature water storage tank 8, and the hot water in the medium-temperature water storage tank 8 enters the carbon dioxide vaporizer 11 to realize the vaporization of liquid carbon dioxide.

[0032] The hot water in the medium-temperature water storage tank 8 can also be connected to the external heating unit 16 to provide external heating.

[0033] The hot water in the medium-temperature water storage tank 8 flows through the carbon dioxide vaporizer 11 and is cooled by the cooling tower 14 before entering the low-temperature water storage tank 5. The water heated by the external heating unit 16 is also cooled by the cooling tower 14 before entering the low-temperature water storage tank 5.

[0034] Method of using this invention: During the compression phase, the multi-stage compressor 2 is started to compress carbon dioxide at atmospheric pressure to 13-15 MPa in stages. After each stage of compression, the carbon dioxide is heated and then cooled by the heat exchanger 3. The heat collected by the heat exchanger is stored in the high-temperature water storage tank 6 in the form of hot water. The compressed carbon dioxide in the last stage is in a critical state and enters the carbon dioxide liquefaction unit 4 for liquefaction and cooling to 25-30°C. It is then stored in the liquid carbon dioxide storage device 9.

[0035] While compression is in progress, the high-temperature water in the high-temperature storage tank 6 enters the adsorption refrigeration unit 7 for cooling, producing 5-10°C cold water, which is used for the carbon dioxide liquefaction cooling of the carbon dioxide liquefaction unit 4 in the aforementioned steps. Excess cooling capacity enters the external cooling supply unit 15, outputting cooling capacity externally and collecting return water. The hot water produced, with a residual temperature of 60-70°C, enters the medium-temperature storage tank 8.

[0036] During the expansion phase, the liquid carbon dioxide in the liquid carbon dioxide storage device 9 first passes through the carbon dioxide vaporizer 11, where it is preheated and vaporized by the hot water output from the medium-temperature water storage tank 8. After being heated by the reheater 12, it enters the multi-stage carbon dioxide expander 13 to expand and perform work. After expansion, the exhaust gas pressure is 0.1-0.11 MPa and it enters the gaseous carbon dioxide storage device 1. The heat source for the reheater 12 comes from the circulating heat supply of the trough collector 10. The outlet water temperature of the trough collector can reach 180℃.

[0037] Excess heat from the medium-temperature water storage tank 8 enters the external heating unit 16, where heat is output and return water is collected. The residual heat water discharged from the external heating unit 16 and the carbon dioxide vaporizer 11 enters the cooling tower 14 for further cooling, reducing the temperature to 20°C, and then enters the low-temperature water storage tank 5 for recycling.

[0038] Example 2: This embodiment uses a 50MW compressed carbon dioxide energy storage system as an example: This embodiment constructs a thermodynamic model of a transcritical carbon dioxide energy storage system based on the MATLAB / Simulink platform, including the heat and mass transfer equations for the compression refrigeration module and the heating expansion module. The system's performance under typical operating conditions is simulated by iteratively solving the energy and mass conservation equations.

[0039] Preliminary parameters: The physical properties of carbon dioxide and water were obtained from the NIST CO2PropertyCalculator database.

[0040] Carbon dioxide inlet parameters: 0.1 MPa, 20℃, flow rate: 406.3 t / h; Cooling water parameters: 0.5Pa, 20℃, flow rate 476.5t / h; Parameters after compression: Carbon dioxide parameters: 15 MPa, 25 °C, liquid state; Water parameters: 0.5 MPa, 131.8℃; Compressor parameters: Five-stage compression, compression ratios Y1~Y4=2.59, Y5=4, considering heat exchanger pressure loss during compression, iterating step by step, compressor efficiency is taken as 0.85; Total input power P1 = 71392KW Adsorption refrigeration parameters: Inlet water temperature 131.8℃, outlet cold water temperature 10℃, COP=0.55, residual temperature after desorption 60℃; The cold water production capacity is 2687t / h, the liquefied return water temperature is 17℃, and the temperature difference is 7℃. When the temperature of the compressed carbon dioxide entering the liquefier is 85℃, the liquefaction consumption is 2635t / h, and the external cooling water supply is 52t / h. The external cooling water supply can be adjusted according to the load. Gasification process parameters: The residual heat water inlet temperature is 60℃, the return water temperature is 40℃, and the water consumption is 311t / h. The carbon dioxide inlet temperature is 25℃, the preheated temperature is 45℃, and the gas flow rate is 406.3t / h. After gasification is completed, the residual heat water tank still has a capacity of 165.5 t / h for external supply, with a supply and return water temperature of 60℃-40℃; Expansion process parameters: The reheated carbon dioxide temperature is 150℃, and the flow rate is 406.3 t / h; Three-stage expansion, with expansion ratios K1=2.95, K2=5.36, K3=8.03, final stage exhaust pressure 0.11MPa, and exhaust temperature 24.3℃; Considering the pressure loss of the reheater, the process is iterated step by step, and the expander efficiency is taken as 0.85; Total power generation W = 50008KW (approximately 50MW) Parabolic trough collector parameters: The water supply temperature is 180℃, the return water temperature is 77.6℃, and the water flow rate is 292.5t / h. Considering the low power consumption of the control system and auxiliary equipment, this system has no additional power input except for the compressor. The system's electrical switching efficiency (RTE) is calculated as follows: MATLAB simulations demonstrate that the system's electro-electric efficiency reaches 70%, higher than the approximately 62% efficiency of some existing compressed carbon dioxide energy storage systems in China. With improvements in compressor and expander efficiency, the system's electro-electric efficiency has significant room for further improvement. Furthermore, the system can provide combined electricity, cooling, and heating, utilizing solar energy and other clean energy sources through parabolic trough solar collectors, thus enhancing overall energy efficiency. It achieves zero-carbon operation of the energy storage process without introducing fossil fuels.

[0041] Of course, the above description is not limited to the examples above. Technical features not described in this invention can be implemented by or using existing technology, and will not be repeated here. The above embodiments and drawings are only used to illustrate the technical solutions of this invention and are not intended to limit this invention. This invention has been described in detail with reference to preferred embodiments. Those skilled in the art should understand that any changes, modifications, additions or substitutions made by those skilled in the art within the scope of this invention do not depart from the spirit of this invention and should also fall within the scope of protection of the claims of this invention.

Claims

1. A compressed carbon dioxide energy storage system combining a coupled-tank solar collector and adsorption refrigeration, characterized in that: It includes storage units, power units, and heat exchange units; The storage unit includes a gaseous carbon dioxide storage device (1), a compressor (2), a heat exchanger (3), a carbon dioxide liquefaction device (4), and a liquid carbon dioxide storage device (9) connected in sequence. The working unit includes a carbon dioxide vaporizer (11), a reheater (12) and a carbon dioxide expander (13) connected in sequence from the liquid carbon dioxide storage device (9). The heat exchange unit includes a low-temperature water storage tank (5), a high-temperature water storage tank (6), an adsorption refrigeration device (7), and a medium-temperature water storage tank (8). The low-temperature water in the low-temperature water storage tank (5) is heated by the heat exchanger (3) and then enters the high-temperature water storage tank (6). The high-temperature water in the high-temperature water storage tank (6) enters the adsorption refrigeration device (7). The cold water produced by the adsorption refrigeration device (7) enters the carbon dioxide liquefaction device (4) to realize the liquefaction of carbon dioxide. The hot water produced by the adsorption refrigeration device (7) enters the medium-temperature water storage tank (8). The hot water in the medium-temperature water storage tank (8) enters the carbon dioxide vaporizer (11) to realize the vaporization of liquid carbon dioxide.

2. The compressed carbon dioxide energy storage system with coupled trough collector and adsorption refrigeration according to claim 1, characterized in that: When carbon dioxide flows through the reheater (12), it is heated by the hot water output from the trough solar collector (10).

3. The compressed carbon dioxide energy storage system with coupled trough collector and adsorption refrigeration according to claim 1, characterized in that: The compressor (2) and heat exchanger (3) are provided in multiple units, and the compressor (2) and heat exchanger (3) are arranged in series alternately.

4. The compressed carbon dioxide energy storage system with coupled-tank solar collector and adsorption refrigeration according to claim 1, characterized in that: Multiple reheaters (12) and carbon dioxide expanders (13) are provided, and the reheaters (12) and carbon dioxide expanders (13) are arranged alternately in series.

5. The compressed carbon dioxide energy storage system with coupled trough collector and adsorption refrigeration according to claim 1, characterized in that: Carbon dioxide enters the carbon dioxide liquefaction unit (4) in a supercritical state.

6. The compressed carbon dioxide energy storage system with coupled trough collector and adsorption refrigeration according to claim 1, characterized in that: The hot water in the medium-temperature water storage tank (8) flows through the carbon dioxide vaporizer (11) and is then cooled by the cooling tower (14) before entering the low-temperature water storage tank (5).

7. The compressed carbon dioxide energy storage system with coupled trough collector and adsorption refrigeration according to claim 1, characterized in that: The cold water produced by the adsorption refrigeration device (7) is used for external cooling.

8. The compressed carbon dioxide energy storage system with coupled trough collector and adsorption refrigeration according to claim 1, characterized in that: The hot water in the medium-temperature water storage tank (8) is used to supply heat to the outside.

9. The compressed carbon dioxide energy storage system with coupled trough collector and adsorption refrigeration according to claim 1, characterized in that: The carbon dioxide discharged from the carbon dioxide expander (13) is returned to the gaseous carbon dioxide storage device (1).

10. The compressed carbon dioxide energy storage system with coupled trough collector and adsorption refrigeration according to claim 1, characterized in that: The adsorption refrigeration device (7) adopts a zeolite-water adsorption refrigeration device.

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