Adiabatic-near isothermal supercritical carbon dioxide energy storage system and operation method

Abstract

The invention discloses a supercritical carbon dioxide energy storage system and an operation method. The system is composed of a pre-compression energy storage unit, a double-tank type near-isothermal compression unit, a heat exchange oil unit, an expansion generator set and a storage container. The low-pressure carbon dioxide is primarily pressurized by the pre-compression unit and then enters the double-tank unit to be subjected to near-isothermal compression to form a supercritical state. And low-temperature heat exchange oil generated by the cooler in the compression process and high-temperature heat exchange oil for ethylene cracking gas waste heat recovery are stored together. And during energy release, the supercritical carbon dioxide absorbs the heat of the high-temperature heat exchange oil and then drives the multi-stage expansion machine generator set to do work. The system innovatively couples ethylene waste heat utilization and a double-tank near-isothermal compression technology, adopts carbon dioxide as a working medium to remarkably improve the energy storage density, realizes energy gradient utilization by storing compression heat and industrial waste heat, effectively stabilizes new energy output fluctuation, solves the problems of low energy storage efficiency and industrial waste heat recovery in the prior art, and improves the energy storage efficiency. The method has the advantages of efficient integration and multi-energy cooperation.

Description

Technical Field

[0001] The present invention belongs to the technical field of physical energy storage, and particularly relates to an adiabatic-nearly isothermal supercritical carbon dioxide energy storage system and an operation method thereof. Background Art

[0002] To achieve the carbon emission target, the installed power generation of renewable energy has been increasing year by year. However, renewable energy has significant volatility and intermittency. Energy storage systems can store excess power during low electricity consumption periods and release it during high electricity consumption periods, achieving peak shaving and valley filling to relieve the grid pressure, improve the grid operation efficiency, and enhance the actual utilization rate of renewable energy.

[0003] The double-tank nearly isothermal compressed gas energy storage technology controls the temperature change of the gas within a very small range during the compression process by using a liquid piston to pressurize, thereby achieving a nearly isothermal compression process. The nearly isothermal compressed air energy storage technology does not rely on fossil fuels, has low compression power consumption, a simple structure, high efficiency, and better variable operating conditions characteristics of the water pump compared to the compressor, but has a lower energy density.

[0004] As one of the core processes in the petrochemical industry, the energy utilization efficiency of the cracking process for ethylene production has always been the focus of technological optimization. In the quenching section after the high-temperature cracking reaction, there is a large amount of high-grade heat energy in the system that has not been effectively recovered. These waste heat resources in the form of high-temperature steam or heat carriers are often directly discharged into the environment through cooling towers or heat exchange devices. This extensive heat energy management mode not only causes energy waste but also leads to high comprehensive energy consumption of the device. From the perspective of industrial ecology, the cascade utilization of waste heat resources can reconstruct the energy flow path - by integrating waste heat boilers, organic Rankine cycle power generation, or process preheating systems, the originally wasted heat energy can be converted into the power to drive equipment operation or the heat source for raw material pretreatment. The construction of this energy cycle mode can not only reduce the direct carbon emissions caused by the consumption of fossil fuels but also reduce the carbon intensity per unit product through energy efficiency improvement. While achieving cost reduction and efficiency improvement, it promotes the transformation and upgrading of traditional petrochemical production towards green manufacturing. Currently, with the breakthrough of intelligent thermal system monitoring technology, waste heat recovery is evolving from intermittent retrofit projects to an organic part of the full-process energy efficiency management system. Summary of the Invention

[0005] To solve the uncertainty problems of new energy such as wind and light and the waste heat utilization problem in the quench tower during the ethylene production process, the purpose of the present invention is to provide a supercritical carbon dioxide energy storage system coupled with waste heat utilization in ethylene production and an operation method thereof. Based on the supercritical carbon dioxide energy storage principle, combined with a double-tank nearly isothermal compression device and waste heat utilization in the ethylene production process, using carbon dioxide as the energy storage working medium, it not only improves the energy storage density of the system but also solves the waste heat utilization problem in the ethylene production process and the problems of volatility and intermittency of the output of new energy such as wind and light.

[0006] To achieve the above object, in a first aspect, the present invention provides an adiabatic-nearly isothermal supercritical carbon dioxide energy storage system, which includes a pre-compression energy storage unit, a double-tank nearly isothermal compression energy storage unit, a heat transfer oil unit, an expansion generator unit, and a carbon dioxide storage container. A low-pressure carbon dioxide storage container, a pre-compression energy storage unit, a double-tank nearly isothermal compression energy storage unit, a supercritical carbon dioxide storage container, and an expansion generator unit are connected in sequence; the expansion unit is connected to the generator, the expansion unit is provided with multiple expanders, and a heat exchanger is provided in front of the inlet of each expander. The outlet of the last-stage expander is connected to the low-pressure carbon dioxide storage tank; in the heat transfer oil unit, a low-temperature heat transfer oil storage tank, an ethylene quench tower, and a high-temperature heat transfer oil storage tank are connected in sequence. The high-temperature heat transfer oil storage tank is connected to the heat exchanger and the low-temperature heat transfer oil storage tank in sequence; the heat transfer oil unit is also connected to the pre-compression energy storage unit, and the motor in the pre-compression energy storage unit is connected to the power output end of the new energy system.

[0007] Further, the pre-compression energy storage unit includes a compressor unit module and a motor. The compressor unit module is provided with multiple compressors. The compressor is connected to the motor. The outlet of each compressor is connected to a cooler. The hot side of the cooler is connected to the compressor. The cold side inlet of the cooler is connected to the low-temperature heat transfer oil storage tank. The cold side outlet of the cooler is connected to the high-temperature heat transfer oil storage tank. A oil pump is provided at the outlet of the low-temperature heat transfer oil storage tank.

[0008] Further, the outlet of the low-temperature heat transfer oil storage tank is connected to the quench oil inlet of the ethylene quench tower, and the quench oil outlet of the ethylene quench tower is connected to the high-temperature heat transfer oil storage tank.

[0009] Further, the double-tank nearly isothermal compression energy storage unit includes a first water-gas co-tank, a second water-gas co-tank, and a water pump; the air inlets of the first water-gas co-tank and the second water-gas co-tank are connected to each other. The water pump is arranged between the first water-gas co-tank and the second water-gas co-tank. The air outlets of the first water-gas co-tank and the second water-gas co-tank serve as the outlet of the double-tank nearly isothermal compression device. The outlet of the double-tank nearly isothermal compression device is connected to the inlet of the supercritical carbon dioxide storage tank through an outlet throttle valve.

[0010] Further, the outlet of the supercritical carbon dioxide storage tank is connected to the expansion generator set through a throttle valve.

[0011] Further, the expansion unit includes a first expander, a second expander, and a third expander. The inlets of the first expander, the second expander, and the third expander are respectively connected to the cold sides of a first heat exchanger, a second heat exchanger, and a third heat exchanger. The hot side inlets of the first heat exchanger, the second heat exchanger, and the third heat exchanger are connected to the high-temperature heat transfer oil storage tank. The hot side outlets of the first heat exchanger, the second heat exchanger, and the third heat exchanger are connected to the low-temperature heat transfer oil storage tank. The outlet of the third expander is connected to the low-pressure carbon dioxide storage tank.

[0012] In a second aspect, the present invention further provides an operation method for the above adiabatic-nearly isothermal supercritical carbon dioxide energy storage system, including a pre-setting stage, an energy storage stage, and an energy release stage; In the pre-setting stage, the liquid levels in the water-gas tanks of the double-tank nearly isothermal compression energy storage unit remain at the same level; In the energy storage stage, the pre-compression energy storage unit compresses carbon dioxide and then enters the double-tank nearly isothermal compression energy storage unit for further compression to the supercritical state and storage; meanwhile, the heat exchange oil in the heat exchange oil unit absorbs the heat generated during the compression process of the pre-compression energy storage unit and stores it, and the heat exchange oil absorbs heat after entering the ethylene quench tower and stores it; In the energy release stage, the supercritical carbon dioxide exchanges heat with the high-temperature heat exchange oil in the heat exchanger and then enters the expansion unit to drive the expander to do work, the expander drives the generator to generate electricity, and the carbon dioxide after doing work enters the low-pressure carbon dioxide storage tank for storage and enters the next cycle.

[0013] Further, in the energy storage stage, in the double-tank nearly isothermal compression energy storage unit, the intake valves of the first water-gas co-tank and the second water-gas co-tank are alternately opened, and the water pump alternately pumps water into the second water-gas co-tank and the first water-gas co-tank, and alternately compresses the carbon dioxide in the second water-gas co-tank and the first water-gas co-tank to the supercritical state and stores it.

[0014] Further, in the energy release stage, the supercritical carbon dioxide sequentially enters the first heat exchanger, the first expander, the second heat exchanger, the second expander, the third heat exchanger, the third expander, and the low-pressure carbon dioxide storage tank, and absorbs the high-temperature heat exchange oil for heat supplement in the first heat exchanger, the second heat exchanger, and the third heat exchanger and then enters the first expander, the second expander, and the third expander to do work respectively.

[0015] Further, in the energy storage stage, the low-temperature heat exchange oil enters the ethylene quench tower and participates in the quenching process after cracking to produce ethylene, absorbs the heat in the cracked gas, and then flows into the high-temperature heat exchange oil storage tank for storage.

[0016] Compared with the prior art, the present invention has at least the following beneficial effects: The present invention combines supercritical carbon dioxide energy storage, uses carbon dioxide as the energy storage working medium, and combines the characteristics of supercritical carbon dioxide with double-tank nearly isothermal compression energy storage to improve the energy storage energy density while taking into account the efficiency; during energy release, a heat exchanger is used to use the waste heat generated in the ethylene production industrial process to supplement heat to the supercritical carbon dioxide, solving the problem of waste of high-temperature waste heat in the process of cracking to produce ethylene; using the waste heat in the process of cracking to produce ethylene to replace traditional fuel for heat supplement reduces carbon emissions and environmental pollution; the heat energy is utilized in a gradient manner by realizing heat supplement in stages during the operation of the expansion unit, thereby improving the efficiency and economy of the entire system. Description of the Drawings

[0017] Figure 1This is a diagram of an adiabatic-nearly isothermal supercritical carbon dioxide energy storage system of the present invention.

[0018] Figure 2 This is a process flow diagram for cracking to produce ethylene.

[0019] Where: 1 - low-pressure carbon dioxide storage tank, 2 - outlet valve of low-pressure carbon dioxide storage tank, 3 - motor, 4 - first compressor, 5 - first cooler, 6 - second compressor, 7 - second cooler, 8 - third compressor, 9 - third cooler, 10 - double-tank nearly isothermal compression unit, 11 - first intake valve, 12 - first high-pressure water-vapor tank, 13 - second intake valve, 14 - water pump, 15 - second high-pressure water-vapor tank, 16 - first exhaust valve, 17 - second exhaust valve, 18 - inlet valve of supercritical carbon dioxide storage tank, 19 - supercritical carbon dioxide storage tank, 20 - supercritical carbon dioxide outlet throttle valve, 21 - low-temperature heat transfer oil storage tank, 22 - first heat transfer oil pump, 23 - ethylene quench tower, 24 - high-temperature heat transfer oil storage tank, 25 - second heat transfer oil pump, 26 - first heat exchanger, 27 - first expander, 28 - second heat exchanger, 29 - second expander, 30 - third heat exchanger, 31 - third expander, 32 - generator, 33 - inlet valve of low-pressure carbon dioxide storage tank. Specific embodiments

[0020] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0021] Please refer to Figure 1, an adiabatic-nearly isothermal supercritical carbon dioxide energy storage system, comprising a pre-compression energy storage unit, a double-tank nearly isothermal compression energy storage unit, a heat exchange oil unit, an expansion generator unit, and a carbon dioxide storage container; along the gas flow direction, a low-pressure carbon dioxide storage container, a pre-compression energy storage unit, a double-tank nearly isothermal compression energy storage unit, a supercritical carbon dioxide storage container, and an expansion generator are connected in sequence, and the motor in the pre-compression energy storage unit is connected to the power output end of the new energy system. Utilizing the high density and low viscosity characteristics of supercritical carbon dioxide, the system can achieve a higher energy storage density under high pressure, while reducing the pipeline transportation resistance, reducing the pumping energy consumption. The double-tank nearly isothermal compression device reduces the heat energy loss in the traditional compression process by effectively controlling the temperature change during the compression process, thereby improving the compression efficiency. Compared with adiabatic compression, the isothermal or nearly isothermal process can significantly reduce the energy loss; the motor of the pre-compression unit is directly connected to the new energy system (such as wind power, photovoltaic), and the excess electric energy can be converted into compressed energy storage during the peak power generation period, solving the problem of abandoned electricity caused by the intermittency of renewable energy and improving the stability of the power grid; the rapid phase change characteristics of supercritical carbon dioxide enable the system to quickly respond to the change of power demand, and quickly release energy through the expansion generator unit when the power generation is insufficient, assisting the power grid in peak shaving; through the heat exchange oil medium, the heat exchange during the compression and expansion processes is effectively managed to maintain nearly isothermal conditions, avoiding the efficiency decline caused by the drastic temperature fluctuation, and at the same time, waste heat recovery may be achieved; the series structure of pre-compression and double compression increases the gas pressure in stages, reduces the single-stage compression ratio, reduces the demand for compression work, and alleviates the mechanical stress of the equipment.

[0022] The heat exchange oil unit includes a low-temperature heat exchange oil storage tank 21, a first heat exchange oil pump 22, a second heat exchange oil pump 25, a first cooler 5, a second cooler 7, a third cooler 9, an ethylene quench tower 23, a high-temperature heat exchange oil storage tank 24, a first heat exchanger 26, a second heat exchanger 28, and a third heat exchanger 30; the low-temperature heat exchange oil storage tank 21 is connected to the first heat exchange oil pump 22, the outlet of the first heat exchange oil pump 22 is connected to the cooling oil inlets of the first cooler 5, the second cooler 7, the third cooler 9, and the ethylene quench tower 23, the oil outlets of the first cooler 5, the second cooler 7, the third cooler 9, and the ethylene quench tower 23 are connected to the high-temperature heat exchange oil storage tank 24, the outlet of the high-temperature heat exchange oil storage tank 24 is connected to the second heat exchange oil pump 25, and the outlet of the second heat exchange oil pump 25 is connected to the low-temperature heat exchange oil storage tank 21 via the first heat exchanger 26, the second heat exchanger 28, and the third heat exchanger 30.

[0023] The pre-compression energy storage unit includes a compressor unit module and a motor. A multi-stage compressor is provided in the compressor unit module. The compressor is connected to the motor. The compressor unit module includes a first compressor 4, a second compressor 6, and a third compressor 8. The low-pressure carbon dioxide storage tank 1 is connected to the inlet of the first compressor 4 through an outlet valve 2. The outlet of the first compressor 4 is connected to the hot-side gas inlet of the first cooler 5. The hot-side gas outlet of the first cooler 5 is connected to the second compressor 6. The outlet of the second compressor 6 is connected to the hot-side gas inlet of the second cooler 7. The hot-side gas outlet of the second cooler 7 is connected to the third compressor 8. The outlet of the third compressor 8 is connected to the hot-side gas inlet of the third cooler 9. The hot-side gas outlet of the third cooler 9 is connected to the double-tank near-isothermal compressed air energy storage unit 10. The power input end of the motor is connected to the new energy power output end.

[0024] The double-tank near-isothermal compressed energy storage unit 10 includes a first water-gas co-tank 12, a second water-gas co-tank 15, and a water pump 14. The gas inlets of the first water-gas co-tank 12 and the second water-gas co-tank 15 are respectively connected to the gas outlet of the third cooler 9 through a first inlet valve 11 and a second inlet valve 13. The gas outlets of the first water-gas co-tank 12 and the second water-gas co-tank 15 are respectively connected to the inlet valve of the supercritical carbon dioxide storage container 18 through a first exhaust valve 16 and a second exhaust valve 17. The water outlet of the first water-gas co-tank 12 is connected to the water inlet of the second water-gas co-tank 15 through the water pump 14. The water outlet of the second water-gas co-tank 15 is connected to the water inlet of the first water-gas co-tank 12 through the water pump 14. Temperature sensors, pressure sensors, and water level gauges are provided in both the first water-gas co-tank 12 and the second water-gas co-tank 15. The supercritical carbon dioxide storage container 19 is connected to the gas inlet of the first heat exchanger 26 through an outlet valve 20. The inlet valve of the supercritical carbon dioxide storage container 18 is a throttle valve. The power input end of the water pump 14 is connected to the new energy power output end.

[0025] Preferably, the operation process in each water-gas co-tank can be divided into a compression process, an exhaust process, and an intake process. Compressing carbon dioxide as the liquid level rises is the compression process; after reaching the specified pressure, it enters the exhaust process; when the liquid level rises to the highest point and then starts to drop, the intake valve is opened to enter the intake process. The three processes cycle to achieve near-isothermal compression of the working medium. The double-tank compression may adopt an alternating working mode, with one tank compressing while the other exhausts, to achieve continuous gas supply, reduce the impact of pressure fluctuations on downstream equipment, and improve operation stability; the supercritical carbon dioxide storage container avoids the gas-liquid phase change interface, reduces the material cost of the storage pressure vessel, and at the same time reduces the energy loss during the gasification process of liquid carbon dioxide.

[0026] The expansion unit includes a first expander 27, a second expander 29, and a third expander 31. The first expander 27, the second expander 29, and the third expander 31 are connected to a generator 32. The inlets of the first expander 27, the second expander 29, and the third expander 31 are respectively connected to the cold-side gas outlets of a first heat exchanger 26, a second heat exchanger 28, and a third heat exchanger 29. The outlet of the third expander 31 is connected to a low-pressure carbon dioxide storage tank 1 through a low-pressure carbon dioxide storage tank inlet valve 33.

[0027] Reference for ethylene production process Figure 2 , successively passing through raw material pretreatment, high-temperature pyrolysis, pyrolysis gas quenching, compression purification, and fractionation and purification. During the pyrolysis gas quenching process, the low-temperature heat exchange oil storage tank is connected to the quench oil inlet of the ethylene quench tower. The quench oil outlet of the ethylene quench tower is connected to the high-temperature heat exchange oil storage tank. The high-temperature pyrolysis gas exchanges heat with the low-temperature heat exchange oil, and the high-temperature pyrolysis gas is cooled to obtain low-temperature pyrolysis gas. The low-temperature heat exchange oil is heated to obtain high-temperature heat exchange oil and enters the high-temperature heat exchange oil storage tank. Based on the above system, the present invention provides an adiabatic-nearly isothermal supercritical carbon dioxide energy storage system and an operation method, as follows: In the preset stage, the liquid levels in the two water-air tanks are kept level by adjusting the water pump 14.

[0028] In the energy storage stage, the outlet valve 2 of the low-pressure carbon dioxide storage tank is opened, and carbon dioxide successively enters a first compressor 4, the hot side of a first cooler 5, a second compressor 6, the hot side of a second cooler 7, a third compressor 8, the hot side of a third cooler 9, and then enters a double-tank nearly isothermal compression energy storage unit 10 for further compression; in the heat exchange oil unit, driven by a first heat exchange oil pump 22, the low-temperature heat exchange oil enters the cold sides of the first cooler 5, the second cooler 7, and the third cooler 9, absorbs the compression heat during the compression process, and is stored in the high-temperature heat exchange oil storage tank 24; at the same time, the low-temperature heat exchange oil enters the ethylene quench tower 23 and participates in the quenching process after cracking to produce ethylene, absorbs the heat in the pyrolysis gas, and then flows into the high-temperature heat exchange oil storage tank 24 for storage.

[0029] In the double-tank near-isothermal compression energy storage unit 10, the first intake valve 11 is opened, and the second intake valve 13, the first exhaust valve 16, and the second exhaust valve 17 are closed. Carbon dioxide enters the first water-vapor compatible tank 12, and the water pump 14 pumps the water in the first water-vapor compatible tank 12 from the bottom into the second water-vapor compatible tank 15. After the carbon dioxide in the second water-vapor compatible tank 15 is compressed to the set pressure, the second exhaust valve 17 is opened to allow the supercritical carbon dioxide to enter the supercritical carbon dioxide storage container 19 for storage. After the gas height in the second water-vapor compatible tank 15 is equal to the clearance height, the first intake valve 11 and the second exhaust valve 17 are closed. Then the second intake valve 13 is opened, and the water pump 14 pumps the water in the second water-vapor compatible tank 15 from the bottom into the first water-vapor compatible tank 12. After the carbon dioxide in the first water-vapor compatible tank 12 is compressed to the set pressure, the first exhaust valve 16 is opened to allow the supercritical carbon dioxide to enter the supercritical carbon dioxide storage container 19 for storage. After the gas height in the first water-vapor compatible tank 12 is equal to the clearance height, the second intake valve 13 and the first exhaust valve 16 are closed. Then the first intake valve 11 is opened, and this cycle continues until the end of the energy storage stage. All the valves in the double-tank near-isothermal compression device 10 are closed, and the double-tank near-isothermal compression device 10 stops working.

[0030] During the energy release stage, the supercritical carbon dioxide in the supercritical carbon dioxide storage container 19 enters the first heat exchanger 26 through the outlet throttle valve 20 for heat replenishment, and then enters the first expander 27 to expand and do work. The gas after expansion and work enters the second heat exchanger 28 for heat replenishment and then enters the second expander 29 to do work. The gas after expansion and work enters the third heat exchanger 30 for heat replenishment and then enters the third expander 31 to do work and then enters the low-pressure carbon dioxide storage tank 1; the first expander 27, the second expander 29, and the third expander 31 drive the generator 32 to generate electricity; in the heat exchange oil unit, driven by the second heat exchange oil pump 25, the high-temperature heat exchange oil enters the hot sides of the first heat exchanger 26, the second heat exchanger 28, and the third heat exchanger 30 to exchange heat with the carbon dioxide used for expansion and work on the cold side and then returns to the low-temperature heat exchange oil storage tank 21.

[0031] In summary, an adiabatic-nearly isothermal supercritical carbon dioxide energy storage system and an operation method disclosed by the present invention. The system includes a pre-compression energy storage unit, a double-tank nearly isothermal compression energy storage unit, a heat transfer oil unit, an expansion generator unit, and a carbon dioxide storage container; a low-pressure carbon dioxide storage container, a pre-compression energy storage unit, a double-tank nearly isothermal compression energy storage unit, a supercritical carbon dioxide storage container, and an expansion generator unit are connected in sequence; the pre-compression energy storage unit includes a compressor unit module and a motor. A multi-stage compressor is arranged in the compressor unit module. The compressor is connected to the motor, and the outlet of each stage of the compressor is connected to a cooler; the low-temperature heat transfer oil in the cooler stores the compression heat together with the heat transfer oil that absorbs the remaining heat during the air cooling process of the ethylene cracking gas; the expansion generator unit includes an expansion unit and a generator. The expansion unit is connected to the generator. The expansion unit is provided with a multi-stage expander, and a heat exchanger is arranged in front of the inlet of each stage of the expander to enable supercritical carbon dioxide to absorb the heat stored in the high-temperature heat transfer oil and enter the expander to expand and do work; using carbon dioxide as the energy storage working medium improves the energy storage density and efficiency of the system, solves the problem of waste heat utilization in the ethylene production process, and solves the problems of volatility and intermittency of the output of new energy sources such as wind and light.

[0032] The above content is only to illustrate the technical idea of the present invention and cannot be used to limit the protection scope of the present invention. Any modification made on the basis of the technical solution according to the technical idea proposed by the present invention falls within the protection scope of the claims of the present invention.

Claims

1. An adiabatic-nearly isothermal supercritical carbon dioxide energy storage system, characterized in that, It includes a pre-compression energy storage unit, a double-tank near-isothermal compression energy storage unit, a heat transfer oil unit, an expansion generator unit, and a carbon dioxide storage container. A low-pressure carbon dioxide storage container, a pre-compression energy storage unit, a double-tank near-isothermal compression energy storage unit, a supercritical carbon dioxide storage container, and an expansion generator unit are connected in sequence; the expansion unit is connected to the generator, the expansion unit is provided with multiple expansion machines, a heat exchanger is provided in front of the inlet of each stage of the expansion machine, and the outlet of the last stage of the expansion machine is connected to the low-pressure carbon dioxide storage tank (1); in the heat transfer oil unit, a low-temperature heat transfer oil storage tank (21), an ethylene quench tower (32), and a high-temperature heat transfer oil storage tank (24) are connected in sequence, and the high-temperature heat transfer oil storage tank (24) is connected to the heat exchanger and the low-temperature heat transfer oil storage tank (21) in sequence; the heat transfer oil unit is also connected to the pre-compression energy storage unit, and the motor in the pre-compression energy storage unit is connected to the power output end of the new energy system.

2. The adiabatic-nearly isothermal supercritical carbon dioxide energy storage system according to claim 1, wherein The pre-compression energy storage unit includes a compressor unit module and a motor. Multiple compressors are provided in the compressor unit module. The compressor is connected to the motor. The outlet of each stage of the compressor is connected to a cooler. The hot side of the cooler is connected to the compressor. The cold side inlet of the cooler is connected to the low-temperature heat transfer oil storage tank, and the cold side outlet of the cooler is connected to the high-temperature heat transfer oil storage tank (24). A oil pump is provided at the outlet of the low-temperature heat transfer oil storage tank (21).

3. The adiabatic-nearly isothermal supercritical carbon dioxide energy storage system according to claim 1, wherein The outlet of the low-temperature heat transfer oil storage tank (21) is connected to the quench oil inlet of the ethylene quench tower (23), and the quench oil outlet of the ethylene quench tower (23) is connected to the high-temperature heat transfer oil storage tank (24).

4. The adiabatic-nearly isothermal supercritical carbon dioxide energy storage system according to claim 1, wherein The double-tank near-isothermal compression energy storage unit includes a first water-gas co-capacity tank (12), a second water-gas co-capacity tank (15), and a water pump (14); the air inlets of the first water-gas co-capacity tank (12) and the second water-gas co-capacity tank (15) are connected to each other. The water pump (14) is arranged between the first water-gas co-capacity tank (12) and the second water-gas co-capacity tank (15). The air outlets of the first water-gas co-capacity tank (12) and the second water-gas co-capacity tank (15) serve as the outlet of the double-tank near-isothermal compression energy storage unit. The outlet of the double-tank near-isothermal compression energy storage unit is connected to the inlet of the supercritical carbon dioxide storage tank (19) after passing through an outlet throttle valve.

5. The adiabatic-nearly isothermal supercritical carbon dioxide energy storage system according to claim 4, characterized in that, The outlet of the supercritical carbon dioxide storage tank (19) is connected to the expansion generator set through a throttle valve.

6. The adiabatic-near isothermal supercritical carbon dioxide energy storage system according to claim 1, wherein The expansion unit includes a first expansion machine (27), a second expansion machine (29), and a third expansion machine (31). The inlets of the first expansion machine (27), the second expansion machine (29), and the third expansion machine (31) are respectively connected to the cold sides of the first heat exchanger (26), the second heat exchanger (28), and the third heat exchanger (30). The hot side inlets of the first heat exchanger (26), the second heat exchanger (28), and the third heat exchanger (30) are connected to the high-temperature heat transfer oil storage tank (24). The hot side outlets of the first heat exchanger (26), the second heat exchanger (28), and the third heat exchanger (30) are connected to the low-temperature heat transfer oil storage tank (21). The outlet of the third expansion machine (31) is connected to the low-pressure carbon dioxide storage tank (1).

7. The operation method of the adiabatic-nearly isothermal supercritical carbon dioxide energy storage system according to any one of claims 1-6, characterized in that, It includes a preset stage, an energy storage stage, and an energy release stage; In the preset stage, the liquid levels in the water-gas tanks in the double-tank near-isothermal compression energy storage unit remain at the same level; During the energy storage stage, the pre-compression energy storage unit compresses carbon dioxide and then sends it into the double-tank near-isothermal compression energy storage unit for further compression to the supercritical state for storage. At the same time, the heat transfer oil in the heat transfer oil unit absorbs the heat generated during the compression process of the pre-compression energy storage unit and stores it. The heat transfer oil enters the ethylene quench tower (23) to absorb heat and then stores it. During the energy release stage, the supercritical carbon dioxide exchanges heat with the high-temperature heat transfer oil in the heat exchanger and then enters the expansion unit to drive the expander to do work. The expander drives the generator to generate electricity. After doing work, the carbon dioxide enters the low-pressure carbon dioxide storage tank (1) for storage and enters the next cycle.

8. The operating method according to claim 7, characterized in that, During the energy storage stage, in the double-tank near-isothermal compression energy storage unit (10), the intake valves of the first water-gas compatible tank (12) and the second water-gas compatible tank (15) are alternately opened. The water pump (14) alternately pumps water into the second water-gas compatible tank (15) and the first water-gas compatible tank (12), and alternately compresses the carbon dioxide in the second water-gas compatible tank (15) and the first water-gas compatible tank (12) to the supercritical state for storage.

9. The operating method according to claim 7, characterized in that, During the energy release stage, the supercritical carbon dioxide sequentially enters the first heat exchanger (26), the first expander (27), the second heat exchanger (28), the second expander (29), the third heat exchanger (30), the third expander (31), and the low-pressure carbon dioxide storage tank (1). After absorbing the high-temperature heat transfer oil for heat compensation in the first heat exchanger (26), the second heat exchanger (28), and the third heat exchanger (30), it enters the first expander (27), the second expander (29), and the third expander (31) to do work respectively.

10. The operating method according to claim 7, characterized in that During the energy storage stage, the low-temperature heat transfer oil enters the ethylene quench tower (32) and participates in the quenching process after cracking to produce ethylene. After absorbing the heat in the cracked gas, it flows into the high-temperature heat transfer oil storage tank (24) for storage.

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