Liquid air cold returning type compressed air energy storage power station

Abstract

The invention relates to a liquid air recooling type compressed air energy storage power station, which adopts a novel cold supplement circulation process, a low-temperature expansion machine and a liquid air pressurization recooling technology to form a brand-new air pressure / hydraulic pressure combined high-pressure air conveying technology, and has the advantages of good energy-saving effect, low noise, low energy consumption, low energy consumption and low cost. And liquid oxygen, liquid nitrogen or high-purity nitrogen can be produced as a byproduct, and the expected social and economic benefits are obvious.

Description

Technical Field

[0001] The present invention relates to a liquid-air recooling type compressed air energy storage power station (liquid air refers to liquid air, the same below), and in particular to a liquid-air recooling type compressed air energy storage power station using air separation cryogenic expander technology. Background Art

[0002] Against the backdrop of carbon neutrality, building a new power system with new energy as the main body has become a global consensus. Energy storage will participate in it as a core link and is an important guarantee for maintaining the stability of the power system.

[0003] Since photovoltaic and wind power generation are random and intermittent, and electricity has the characteristics of real-time balance of supply and demand and is difficult to store on a large scale, the large-scale grid-connected photovoltaic and wind power generation will aggravate the dual volatility and uncertainty on both the supply and demand sides of the power system, making system peak regulation difficult and bringing about a series of problems such as abandoned solar and wind power. Energy storage can smooth out the instability of photovoltaic and wind power generation and achieve a dynamic balance of electricity supply and demand.

[0004] In the summer, electricity demand is strong, and the peak-valley electricity price difference continues to expand. In 17 provinces and regions, the peak-valley electricity price difference exceeds 0.7 yuan / kWh, and the economic benefits of industrial and commercial energy storage projects are highlighted. In July 2024, with the arrival of summer, the peak-valley electricity price difference in various regions across the country has widened. A total of 17 regions have a peak-valley electricity price difference of more than 0.7 yuan / kWh. The top three are Guangdong Province (five cities in the Pearl River Delta), Hainan Province, and Jiangsu Province. The largest peak-valley price differences reached 1.27 yuan / kWh, 1.22 yuan / kWh, and 1.14 yuan / kWh, respectively, and the economic benefits of peak-valley arbitrage have been significantly improved. Even in the spring when electricity demand is relatively stable, there are still 16 regions with a peak-valley electricity price difference of more than 0.7 yuan / kWh in March, which effectively guarantees the profitability stability of peak-valley arbitrage of industrial and commercial energy storage systems in the year-round dimension.

[0005] The new energy power supply system will face problems such as mismatch between power supply and demand, and energy storage, virtual power plants, microgrids and other regulatory means are indispensable. Electricity is a dynamic process energy that is not easy to store. It is mainly achieved through the power grid to achieve simultaneous production, transmission and consumption. The power generation method of new energy (such as wind power and solar energy) is greatly affected by weather conditions and has the characteristics of intermittent, volatility and instability. Large-scale application will have an impact on the stability of the power grid. In order to cope with the power generation characteristics of new energy power generation, energy storage, virtual power plants, microgrids and other regulatory means will be widely used in the future. Therefore, the configuration of energy storage is indispensable in the future green power energy system, and the role of new energy storage in promoting the development and consumption of new energy and the safe and stable operation of the power system is gradually emerging.

[0006] Among the technical types of China's new energy storage pilot demonstration projects in December 2023, compressed air energy storage technology types accounted for a relatively high proportion.

[0007] Compressed air energy storage (CAES) is considered to be one of the most promising large-scale energy storage technologies. It has a wide variety of technologies. The types of demonstration projects currently include non-adiabatic, supplementary combustion, advanced adiabatic and constant temperature types. It has the advantages of large energy storage scale, long storage cycle and low environmental pollution.

[0008] Taking non-supplementary compressed air energy storage technology as an example, it mainly relies on air as an energy storage medium, and realizes the storage and release of electrical energy through the process of compressing and releasing compressed air. Jiangsu Jintan Salt Cavern Compressed Air Energy Storage Power Station is the world's first "non-supplementary" compressed air energy storage power station, and it is also the first power generation project in China to use salt cavern resources. The working principle of this compressed air energy storage power generation project is: it uses the surplus period of the power grid (such as at night) to compress the air and inject it into the underground salt cavern for storage, and the heat energy generated during the compression process is also stored in the oil tank. When the power grid needs electricity (such as during the day), the compressed air is released and the heat energy in the oil tank is used for heating, and then enters the turbine to generate electricity. This power station uses salt caverns nearly a thousand meters underground as a container for storing high-pressure air, compresses air to store energy when electricity consumption is low, and releases it to generate electricity at peak times, effectively improving the grid regulation capacity and new energy consumption capacity. The power conversion efficiency of the power station can reach more than 60%, and there is no combustion and no emissions throughout the process, marking a qualitative leap in my country's compressed air energy storage technology from theoretical experiments to engineering applications.

[0009] In 2011, the Institute of Engineering Thermophysics of the Chinese Academy of Sciences took the lead in building the world's first supercritical compressed air energy storage experimental platform (15KW); based on this technology and continuous research, in 2013, the Institute of Engineering Thermophysics built a MW-level advanced compressed air energy storage (integrated supercritical and thermal storage compressed air energy storage system) demonstration project in Langfang, Hebei, with a system efficiency of 52.1%; further, at the end of 2016, a 10MW advanced compressed air energy storage system was built in Bijie, Guizhou, and the system efficiency was further improved to 60%; and the 100MW advanced compressed air energy storage system currently under construction in Zhangjiakou, Hebei, will have a system target efficiency of 70%, and the unit installed cost will be reduced to US$450-750 / kW, which is close to the efficiency and unit installed cost of pumped storage power stations.

[0010] Chinese patents such as CN200910225252.3-Supercritical air energy storage system, CN201210266532.0-Ultra-supercritical air energy storage and release system, CN201911181103.1-A compressed air energy storage system and control method for efficient utilization of low-grade thermal energy, CN202111218542.2-A compressed air energy storage system, CN202410319879.X-A compressed air energy storage and power generation system with low-temperature purification, etc., have conducted in-depth research on compressed air energy storage (CAES) technology and provided a series of technical improvement approaches. Foreign patents such as US201916563055, US202017608697, US202016856627, US202318499686, EP16861931, EP17174145, JP2019089865, JP2020203178, etc. have also improved the compressed air energy storage technology. The above technologies are worth learning, studying and learning from.

[0011] The key equipment of CAES technology, such as compressors, high-pressure gas storage tanks, gas turbine generators and other domestic equipment, has become relatively mature, and the industrial chain is mature. As the capacity of energy storage systems increases, the cost will tend to decrease, and it is expected that CAES technology will usher in a broader application prospect in the future.

[0012] Therefore, the liquid-to-air recooling compressed air energy storage power station that combines a new cooling cycle and energy-saving compressor high-pressure gas transmission technology in CAES is worthy of in-depth study. Summary of the invention

[0013] A liquid-air recooling type compressed air energy storage power station, which realizes the liquefaction of compressed air by a supplementary cooling circuit, the liquid air pressurization and recooling gasification to realize high-pressure gas transmission, and the high-pressure air energy storage in the high-pressure gas storage tank, and the high-pressure air energy release and power generation process in the high-pressure gas storage tank. The process is as follows:

[0014] The liquid air coming out of the liquid storage tank 3 is gasified by the hydraulic pump 4 and the cooling unit 2, and then enters the low-temperature expander 5 to expand and do work to reduce the temperature. The exhaust gas of the low-temperature expander 5 enters the cooling unit 2 to recover the cold and then is discharged. It is then pressurized by the compressor 1 or the compressor 7 and enters the cooling unit 2 to be liquefied and enters the liquid storage tank 3 for storage. The mechanical energy generated by the low-temperature expander 5 is used to drag the brake 6, thereby realizing the compressed air liquefaction process;

[0015] During energy storage: after being compressed by the compressor 1, the air enters the cooling unit 2 to be liquefied to obtain liquid air, which is then sent to the liquid storage tank 3. The liquid air in the liquid storage tank 3 is then pressurized by the high-pressure pump 14 and enters the cooling unit 2 to release cold energy to cool the compressed air. The formed high-pressure air 15 is then sent to the high-pressure air storage tank 16 for energy storage;

[0016] When releasing energy: the high-pressure air 15 in the high-pressure gas storage tank 16 is heated by the reheater 17, and then enters the gas turbine 18 to expand and do work, driving the gas turbine generator 19 to generate electricity, and the gas turbine exhaust 21 is discharged; or the high-pressure air 15 in the high-pressure gas storage tank 16 is heated by the reheater 20 and the reheater 17, and then enters the gas turbine 18 to expand and do work, driving the gas turbine generator 19 to generate electricity, and the outlet gas of the gas turbine 18 recovers heat through the reheater 20 to form the gas turbine exhaust 21.

[0017] The liquid air is pressurized and cooled back to gasify to achieve high-pressure gas transmission, which means that the liquid air in the liquid storage tank 3 is pressurized by the high-pressure pump and then enters the cooling unit 2 to release cold energy to cool the compressed air, forming high-pressure air 15 that is transported to the high-pressure gas storage tank 16 for energy storage.

[0018] The cooling unit 2 adopts a shell and tube, plate fin, microchannel or other type of cooling exchanger. Its structure and cooling elements are similar to the shell and tube heat exchanger, plate fin heat exchanger, microchannel or other type of heat exchanger in the traditional air separation process. Multiple cooling exchangers are combined together in series, parallel or series-parallel connection.

[0019] The air compression and cooling process in the liquid-to-air recooling compressed air energy storage power station also includes air purification and purification, which is used to remove solid matter and impurity gases in the air; the air purification and purification equipment is integrated in the compressor 1 and / or the compressor 7 and / or the cold exchange unit 2, or integrated in the connecting pipes of the compressor 1, the compressor 7, and the cold exchange unit 2.

[0020] The brake 6 of the cryogenic expander 5 includes but is not limited to a fan, a liquid pump, a compressor or an air compressor, and is used to recover the expansion work generated by the cryogenic expander 5 .

[0021] The air compressor 1 or compressor 7 is only used for distinction, and in essence they are both air compression and boosting equipment; the same applies to hydraulic pumps or liquid air pumps, and high-pressure pumps.

[0022] The compressed air in the liquid-to-air recooling type compressed air energy storage power station is an isobaric liquefaction process, which means that the raw air entering the cooling unit 2 does not need to be expanded, depressurized and refrigerated like the traditional air separation process. The air coming out of the compressor only has resistance losses along the equipment and pipelines, and can be regarded as an isobaric liquefaction process of air with little pressure change.

[0023] The air purification and purification equipment in the liquid-to-air recooling type compressed air energy storage power station, wherein the purification equipment includes a molecular sieve purifier, a reversible cooler or a stone cooler, etc., should be able to ensure the continuous and normal operation of the process.

[0024] The heat source of the reheater 17 is one or more of the following thermal energies: compression heat generated by a compressor or an air compressor; industrial waste heat or waste heat; solar thermal energy; heat energy released by fuel combustion; geothermal energy; heat energy stored in a heat storage medium; the heat source of the reheater 17 is used to heat the high-pressure air 15.

[0025] A distillation unit 9 is provided: the liquid air coming out of the liquid storage tank 3 is pressurized by the liquid air pump 8 and then enters the distillation unit 9 to produce liquid oxygen 10 and gaseous nitrogen for output.

[0026] A liquefaction unit 11 is provided: the gaseous nitrogen produced from the distillation unit 9 passes through the liquefaction unit 11 to produce liquid nitrogen 12.

[0027] The distillation unit 9 is designed, installed and operated with reference to the distillation tower of the air separation device.

[0028] The liquefaction unit 11 is implemented by a conventional compression refrigeration process or a low-temperature expansion machine process.

[0029] In the present application, the compression heat of the outlet gas of the compressor 7 or the air compressor 1 is recovered and utilized through a heat accumulator.

[0030] Equipment and its systems, pipelines, instruments, valves, cold preservation, bypass facilities with regulating functions, etc. not described in this application shall be matched with reference to or in accordance with mature technologies in well-known traditional processes.

[0031] The equipment and pipelines in this application adopt necessary heat recovery and cooling measures.

[0032] Parts not mentioned in this application, such as safety accessories, automatic control, etc., are equipped with existing publicly known technologies, that is, existing mature, reliable and reasonable technical measures are applied to this device.

[0033] Compared with the prior art, the present invention has the following advantages:

[0034] 1. Compared with the existing multi-stage compression and intermediate cooling compressor high-pressure gas transmission compressed air energy storage power station, the high-pressure gas supply technology of air isobaric liquefaction and hydraulic pump pressurization and cooling combined with full low-pressure oxygen production technology can effectively reduce the compression heat power consumption of the compressor and reduce the difficulty of heat recovery of the low-grade compression heat of the compressor. The comprehensive power consumption of high-pressure gas supply is greatly reduced and the noise is low. It is essentially a new energy-saving gas pressure / hydraulic combined high-pressure gas supply type compressed air energy storage power station, and the gas pressure / hydraulic combined high-pressure gas supply unit is suitable for the transformation and upgrading of the gas supply system of the existing compressed air energy storage power station;

[0035] 2. Compared with the existing air compression energy storage power station, the air booster energy storage power station combined with the air pressure / hydraulic combined high-pressure air supply unit not only has obvious power saving effect, but also has the characteristics of co-production of liquid oxygen, nitrogen, and liquid nitrogen, and can flexibly adjust the operation mode according to market conditions to improve the comprehensive benefits of the power station.

[0036] 3. Compared with the existing air compression energy storage power station, this power station has low noise, adopts a new type of cooling circulation loop, and has the characteristics of flexible and convenient adjustment. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a process flow diagram of a liquid-air recooling type compressed air energy storage power station.

[0038] Figure 1 In: 1-compressor, 2-cooling unit, 3-low-pressure liquid storage tank, 4-hydraulic pump, 5-cryogenic expander, 6-brake, 7-compressor, 8-liquid air pump, 9-distillation unit, 10-liquid oxygen, 11-nitrogen liquefaction unit, 12-liquid nitrogen, 13-liquid air, 14-high-pressure pump, 15-high-pressure air, 16-high-pressure gas storage tank, 17-reheater, 18-gas turbine, 19-gas turbine generator, 20-regenerator, 21-gas turbine exhaust. DETAILED DESCRIPTION

[0039] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0040] Embodiment 1:

[0041] like Figure 1 As shown, a liquid-air recooling type compressed air energy storage power station, the power supply process of the power station is as follows:

[0042] The supplementary cooling circuit refers to the liquid air coming out of the liquid storage tank 3, which is gasified by the hydraulic pump 4 and the cooling unit 2, and then enters the low-temperature expander 5 to expand and do work to reduce the temperature. The exhaust gas of the low-temperature expander 5 enters the cooling unit 2 to recover the cold and then is discharged. It is then pressurized by the compressor 1 or the compressor 7 and enters the cooling unit 2 to be liquefied and enters the liquid storage tank 3 for storage. The mechanical energy generated by the low-temperature expander 5 is used to drag the brake 6, thereby realizing the compressed air liquefaction process;

[0043] During energy storage: after being compressed by the compressor 1, the air enters the cooling unit 2 to be liquefied to obtain liquid air, which is then sent to the liquid storage tank 3. The liquid air in the liquid storage tank 3 is then pressurized by the high-pressure pump 14 and enters the cooling unit 2 to release cold energy to cool the compressed air. The formed high-pressure air 15 is then sent to the high-pressure air storage tank 16 for energy storage;

[0044] When releasing energy: the high-pressure air 15 in the high-pressure gas storage tank 16 is heated by the reheater 17, and then enters the gas turbine 18 to expand and do work, driving the gas turbine generator 19 to generate electricity, and the gas turbine exhaust 21 is discharged; or the high-pressure air 15 in the high-pressure gas storage tank 16 is heated by the reheater 20 and the reheater 17, and then enters the gas turbine 18 to expand and do work, driving the gas turbine generator 19 to generate electricity, and the outlet gas of the gas turbine 18 recovers heat through the reheater 20 to form the gas turbine exhaust 21.

[0045] The liquid air is pressurized and cooled back to gasify to achieve high-pressure gas transmission, which means that the liquid air in the liquid storage tank 3 is pressurized by the high-pressure pump and then enters the cooling unit 2 to release cold energy to cool the compressed air, forming high-pressure air 15 that is transported to the high-pressure gas storage tank 16 for energy storage.

[0046] The cooling unit 2 adopts a shell and tube, plate fin, microchannel or other type of cooling exchanger. Its structure and cooling elements are similar to the shell and tube heat exchanger, plate fin heat exchanger, microchannel or other type of heat exchanger in the traditional air separation process. Multiple cooling exchangers are combined together in series, parallel or series-parallel connection.

[0047] The air compression and cooling process in the liquid-to-air recooling compressed air energy storage power station also includes air purification and purification, which is used to remove solid matter and impurity gases in the air; the air purification and purification equipment is integrated in the compressor 1 and / or the compressor 7 and / or the cold exchange unit 2, or integrated in the connecting pipes of the compressor 1, the compressor 7, and the cold exchange unit 2.

[0048] The brake 6 of the cryogenic expander 5 includes but is not limited to a fan, a liquid pump, a compressor or an air compressor, and is used to recover the expansion work generated by the cryogenic expander 5 .

[0049] The air compressor 1 or compressor 7 is only used for distinction, and in essence they are both air compression and boosting equipment; the same applies to hydraulic pumps or liquid air pumps, and high-pressure pumps.

[0050] The liquefaction of compressed air in the liquid-to-air recooling type compressed air energy storage power station is an isobaric liquefaction process: the raw air entering the cooling unit 2 does not need to be expanded, depressurized and refrigerated like the traditional air separation process. The air coming out of the compressor only has resistance losses along the equipment and pipelines, and can be regarded as an isobaric liquefaction process of air with little pressure change.

[0051] The air purification and purification equipment in the liquid-to-air recooling type compressed air energy storage power station, wherein the purification equipment includes a molecular sieve purifier, a reversible cooler or a stone cooler, etc., should be able to ensure the continuous and normal operation of the process.

[0052] The heat source of the reheater 17 is one or more of the following thermal energies: compression heat generated by a compressor or an air compressor; industrial waste heat or waste heat; solar thermal energy; heat energy released by fuel combustion; geothermal energy; heat energy stored in a heat storage medium; the heat source of the reheater 17 is used to heat the high-pressure air 15.

[0053] A distillation unit 9 is provided: the liquid air coming out of the liquid storage tank 3 is pressurized by the liquid air pump 8 and then enters the distillation unit 9 to produce liquid oxygen 10 and gaseous nitrogen for output.

[0054] A liquefaction unit 11 is provided: the gaseous nitrogen produced from the distillation unit 9 passes through the liquefaction unit 11 to produce liquid nitrogen 12.

[0055] The distillation unit 9 is designed, installed and operated with reference to the distillation tower of the air separation device.

[0056] The liquefaction unit 11 is implemented by a conventional compression refrigeration process or a low-temperature expansion machine process.

[0057] In the present application, the compression heat of the outlet gas of the compressor 7 or the air compressor 1 is recovered and utilized through a heat accumulator.

[0058] Parts not mentioned in the present invention, such as safety accessories, instruments, meters, automatic control, etc., are equipped with existing well-known technologies, and existing mature, reliable and reasonable technical measures can be applied to this device.

[0059] Although the present invention has been disclosed as above with preferred embodiments, they are not intended to limit the present invention. Anyone familiar with the art can make various changes or modifications without departing from the spirit and scope of the present invention, which also belong to the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the definition of the claims of this application.

Claims

1. A liquid-air cooling compressed air energy storage power station, characterized in that: Liquid air from the liquid storage tank (3) is gasified by the hydraulic pump (4) and the cooling unit (2), and then enters the low-temperature expander (5) to expand and perform work to reduce the temperature. The exhaust gas of the low-temperature expander (5) enters the cooling unit (2) to recover the cold and then is discharged. It is then pressurized by the compressor (1) or the compressor (7) and enters the cooling unit (2) to be liquefied and enters the liquid storage tank (3) for storage. The low-temperature expander (5) drags the brake (6); During energy storage: air is compressed by the compressor (1), enters the cooling unit (2) to be liquefied to obtain liquid air, and is sent to the liquid storage tank (3). The liquid air in the liquid storage tank (3) is pressurized by the high-pressure pump (14), enters the cooling unit (2) to release cold energy, and the formed high-pressure air (15) is sent to the high-pressure air storage tank (16) for energy storage; When releasing energy: the high-pressure air (15) in the high-pressure gas storage tank (16) is heated by the reheater (17), then enters the gas turbine (18) to expand and perform work, driving the gas turbine generator (19) to generate electricity, and the gas turbine exhaust (21) is discharged; or the high-pressure air (15) in the high-pressure gas storage tank (16) is heated by the reheater (20) and the reheater (17), then enters the gas turbine (18) to expand and perform work, driving the gas turbine generator (19) to generate electricity, and the outlet gas of the gas turbine (18) passes through the reheater (20) to form the gas turbine exhaust (21).

2. The liquid-air recooling type compressed air energy storage power station according to claim 1 is characterized in that: The air purification and cleansing equipment in the air compression and cooling process in the liquid-to-air recooling type compressed air energy storage power station is integrated in the compressor (1) and / or the compressor (7) and / or the cold exchange unit (2), or is integrated in the connecting pipes of the compressor (1), the compressor (7) and the cold exchange unit (2).

3. The liquid-air recooling type compressed air energy storage power station according to claim 1 is characterized in that: A distillation unit (9) is provided: liquid air from the liquid storage tank (3) is pressurized by a liquid air pump (8) and then enters the distillation unit (9) to produce liquid oxygen (10) and gaseous nitrogen for output.

4. The liquid-air recooling type compressed air energy storage power station according to claim 3 is characterized in that: A liquefaction unit (11) is provided: the gaseous nitrogen produced by the distillation unit (9) is passed through the liquefaction unit (11) to produce liquid nitrogen (12).

5. The liquid-air recooling type compressed air energy storage power station according to claim 1 is characterized in that: The brake (6) comprises a fan, a liquid pump, a compressor or an air compressor.

6. The liquid-air recooling type compressed air energy storage power station according to claim 2 is characterized in that: The purification equipment includes a molecular sieve purifier, a reversible cooler or a stone cooler.

7. The liquid-air recooling type compressed air energy storage power station according to claim 1 is characterized in that: The heat source of the reheater (78) is one or more of the following thermal energies: compression heat generated by a compressor or an air compressor; industrial waste heat or waste heat; solar thermal energy; thermal energy released by fuel combustion; geothermal energy; and thermal energy stored in a heat storage medium.

8. The liquid-air recooling type compressed air energy storage power station according to claim 1 is characterized in that: The cooling unit (2) adopts a shell and tube type, plate fin type, or microchannel type cooling exchanger.

9. The liquid-air recooling type compressed air energy storage power station according to claim 1, characterized in that: The cooling unit (2) adopts a shell and tube type, plate fin type, or microchannel type cooling exchanger.

10. The liquid-air recooling type compressed air energy storage power station according to claim 9, characterized in that: The coolers in the cool exchange unit (2) are combined together by connecting multiple coolers in series, in parallel, or in series and parallel.

Images