An electric energy storage device based on phase change heat storage

Abstract

The present invention discloses an electric energy storage device based on phase change heat storage, including a supercritical carbon dioxide cycle power generation device for converting heat energy into electric energy through a supercritical carbon dioxide cycle; the electric energy storage device based on phase change heat storage also includes a high-temperature heat accumulator for converting electric energy into heat energy and storing its heat energy in a phase change heat storage material, the high-temperature heat accumulator is arranged on the thermal cycle power generation device, and during the heat release process, the phase change heat storage material transfers heat to the supercritical carbon dioxide working medium. The heat of the phase change heat storage body in the high-temperature heat accumulator of the present invention is absorbed by the supercritical carbon dioxide working medium, which can make it reach a high temperature of more than 1000°C, and the thermal efficiency of the supercritical carbon dioxide cycle can reach more than 63%. The heat energy of the high-temperature heat accumulator is accumulated by electric heating at night when the electricity rate is low, and the heat energy is converted into electric energy through the supercritical carbon dioxide cycle during the day when the electricity rate is high. The energy conversion efficiency of the energy storage device formed can reach more than 60%.

Description

Technical Field

[0001] The present invention relates to the technical field of electric energy storage, and in particular to an electric energy storage device based on phase change heat storage. Background Art

[0002] With the need for energy transformation and development, the proportion of renewable energy connected to the power grid continues to increase, and large-capacity power storage devices are urgently needed. It is estimated that by 2030, my country's energy storage scale will reach 40GW. At the same time, energy storage technology is also developing rapidly, and new advanced energy storage technologies are constantly emerging. In addition to mature pumped storage technology, compressed air energy storage, lead-acid batteries, lithium-ion batteries, flow batteries, flywheel energy storage, supercapacitors, and superconducting energy storage are already in the demonstration stage or have begun commercial applications, and other new energy storage technologies are also being developed.

[0003] In recent years, advanced supercritical carbon dioxide cycle power generation technology has emerged in the field of power generation, which can greatly improve the efficiency of thermal power generation and even exceed the efficiency of advanced gas-steam combined cycle. Supercritical carbon dioxide cycle uses carbon dioxide as a working fluid. Carbon dioxide is chemically inactive, colorless, odorless, non-toxic, safe, cheap, and easy to obtain. It is an excellent natural working fluid. For some metals, such as copper, carbon dioxide does not react with it, which creates conditions for direct contact heat exchange between carbon dioxide and metal phase change heat storage materials, and phase change heat storage materials (copper) have a high energy storage density of up to 50w·h / kg. When operating at a temperature above 1000℃, the thermal efficiency of the supercritical carbon dioxide cycle can reach more than 63%, which can meet the efficiency index requirements of power energy storage. The investment costs of supercritical carbon dioxide cycle and metal phase change heat storage materials are relatively low and economical. Therefore, combining supercritical carbon dioxide cycle with phase change heat storage to form a new type of power energy storage device is of great significance to the development of power energy storage technology. Summary of the invention

[0004] In order to solve the problems existing in the prior art, the purpose of the present invention is to provide an electric energy storage device based on phase change heat storage, which has a reasonable design and simple structure, and can make the heat storage efficiency of the high-temperature heat accumulator reach more than 97%, the thermal efficiency of the supercritical carbon dioxide cycle reach 63%, and the energy conversion efficiency of the energy storage device reach 60%.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] An electric energy storage device based on phase change heat storage, comprising

[0007] A supercritical carbon dioxide cycle power generation device for converting thermal energy into electrical energy through a supercritical carbon dioxide cycle;

[0008] It is characterized in that the electric energy storage device based on phase change heat storage also includes a high-temperature heat accumulator for converting electric energy into thermal energy and storing its thermal energy in a phase change heat storage material. The high-temperature heat accumulator is arranged on a thermal cycle power generation device. During the heat release process, the phase change heat storage material transfers heat to the supercritical carbon dioxide working fluid.

[0009] In a preferred embodiment of the present invention, the high temperature heat accumulator comprises

[0010] - fire-resistant insulation for heat insulation;

[0011] A cylindrical pressure vessel for withstanding the high pressure of supercritical carbon dioxide, the cylindrical pressure vessel being coated on the outer peripheral surface of the fire-resistant insulation layer;

[0012] A phase change heat storage body for storing heat generated by electric heating, wherein the phase change heat storage body is arranged in a space surrounded by a fire-resistant insulation layer, both ends of the phase change heat storage body are provided with power supply ends, and a phase change heat storage material is arranged inside the phase change heat storage body.

[0013] In a preferred embodiment of the present invention, a thermal insulation layer is coated on the outer circumferential surface of the cylindrical pressure vessel.

[0014] In a preferred embodiment of the present invention, the supercritical carbon dioxide cycle power generation device comprises

[0015] A cooler for cooling and liquefying supercritical carbon dioxide;

[0016] A main pump for pressurizing the supercritical carbon dioxide working medium liquefied by the cooler to a set pressure value, wherein the liquid inlet of the main pump is connected to the liquid outlet of the cooler;

[0017] A low-temperature regenerator for heating the supercritical carbon dioxide working medium after being pressurized by the main pump, wherein the high-pressure side inlet of the low-temperature regenerator is connected to the liquid outlet of the main pump, and the low-pressure side outlet of the low-temperature regenerator is connected to the inlet of the cooler;

[0018] a high-temperature regenerator for heating the supercritical carbon dioxide working medium heated by the low-temperature regenerator, wherein the high-pressure side inlet of the high-temperature regenerator is connected to the high-pressure side outlet of the low-temperature regenerator, and the low-pressure side outlet of the high-temperature regenerator is connected to the low-pressure side inlet of the low-temperature regenerator;

[0019] An ultra-high temperature regenerator for heating the supercritical carbon dioxide working medium heated by the high temperature regenerator, wherein the high pressure side inlet of the ultra-high temperature regenerator is connected to the high pressure side outlet of the high temperature regenerator, the low pressure side outlet of the ultra-high temperature regenerator is connected to the low pressure side inlet of the high temperature regenerator, and the high pressure side outlet of the ultra-high temperature regenerator is connected to the inlet of the high temperature heat accumulator;

[0020] A turbine for driving a generator to generate electricity, wherein the inlet of the turbine is connected to the outlet of the high-temperature heat accumulator, and the exhaust port of the turbine is connected to the low-pressure side inlet of the ultra-high-temperature heat regenerator.

[0021] In a preferred embodiment of the present invention, the supercritical carbon dioxide circulation power generation device also includes a bypass compressor for compressing the supercritical carbon dioxide working fluid bypassed from the low-pressure side outlet of the low-temperature regenerator, the inlet of the bypass compressor is connected to the low-pressure side outlet of the low-temperature regenerator, and the outlet of the bypass compressor is connected to the high-pressure side inlet of the high-temperature regenerator.

[0022] In a preferred embodiment of the present invention, the supercritical carbon dioxide circulation power generation device also includes a low-temperature heat accumulator for heating the supercritical carbon dioxide working fluid diverted from the liquid outlet of the main pump, the inlet of the low-temperature heat accumulator is connected to the liquid outlet of the main pump, and the outlet of the low-temperature heat accumulator is connected to the high-pressure side outlet of the low-temperature heat regenerator.

[0023] Compared with the prior art, the heat of the phase change heat storage body in the high-temperature heat accumulator of the present invention is absorbed by the supercritical carbon dioxide working fluid, which can make it reach a high temperature of more than 1000°C. The thermal efficiency of the supercritical carbon dioxide cycle can reach more than 63%. The heat energy of the high-temperature heat accumulator is accumulated through electric heating at night when the electricity rate is low. During the day when the electricity rate is high, the heat energy is converted into electrical energy through the supercritical carbon dioxide cycle. The energy conversion efficiency of the energy storage device formed can reach more than 60%. The device of the present invention integrates existing equipment and technology. Through system optimization configuration, there is no need to redevelop key equipment. The phase change heat storage material can be completely recovered and directly used or sold. The overall investment economy is good. It can be built in industrial facilities with good environmental cooling conditions and waste heat, such as power plants, chemical plants, smelters, etc., and the comprehensive benefits of energy storage will be more prominent by utilizing the cooling equipment, power facilities and management resources of the plant site. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 It is the control principle diagram of the present invention.

[0026] Figure 2 It is a schematic longitudinal cross-sectional view of the high temperature heat accumulator of the present invention.

[0027] Figure 3It is a schematic transverse cross-sectional view of the high-temperature heat accumulator of the present invention. DETAILED DESCRIPTION

[0028] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further described below with reference to specific diagrams.

[0029] Reference Figure 1-Figure 3 As shown, the figure shows an electric energy storage device based on phase change heat storage, including a supercritical carbon dioxide cycle power generation device and a high-temperature heat accumulator 600.

[0030] The supercritical carbon dioxide cycle power generation device is used to convert thermal energy into electrical energy through supercritical carbon dioxide circulation. The high-temperature heat accumulator is used to convert electrical energy into thermal energy and store its thermal energy in the phase change heat storage material. The high-temperature heat accumulator is arranged on the thermal cycle power generation device. During the heat release process, the phase change heat storage material transfers heat to the supercritical carbon dioxide working fluid.

[0031] The high-temperature heat accumulator 600 includes a refractory insulation layer 620, a cylindrical pressure vessel 610 and a phase change heat storage body 630. The refractory insulation layer 620 is used for insulation, the cylindrical pressure vessel 610 is used to withstand the high pressure of supercritical carbon dioxide working fluid, and the cylindrical pressure vessel 610 is coated on the outer peripheral surface of the refractory insulation layer 620.

[0032] The phase change heat storage body 630 is used to store heat generated by electrical heating. The phase change heat storage body 630 is arranged in the space surrounded by the fire-resistant insulation layer 620. Both ends of the phase change heat storage body 630 are provided with power supply ends 631 and 632. A phase change heat storage material is arranged inside the phase change heat storage body 630. In this embodiment, the phase change heat storage material is copper.

[0033] The outer peripheral surface of the cylindrical pressure vessel 610 is coated with a heat-insulating layer, which effectively improves the heat-insulating performance of the high-temperature heat accumulator and reduces heat loss.

[0034] The phase change heat storage body 630 contains a phase change heat storage material. During the energy storage and release process, the phase change heat storage material undergoes a phase change, that is, melts and solidifies. The phase change heat storage body 630 is divided into a plurality of open bins, and the gaps between the bins are channels for the circulation and heat exchange of the supercritical carbon dioxide working medium. The refractory insulation layer 620 keeps the temperature of the cylindrical pressure vessel 610 below 150°C.

[0035] The supercritical carbon dioxide circulation power generation device includes a cooler 900, a main pump 100, a low-temperature regenerator 200, a high-temperature regenerator 400, an ultra-high-temperature regenerator 500 and a turbine 700. The cooler 900 is used to cool and liquefy the supercritical carbon dioxide working medium.

[0036] The main pump 100 is used to pressurize the supercritical carbon dioxide working medium liquefied by the cooler 900 to a set pressure value. The liquid inlet of the main pump 100 is connected to the liquid outlet of the cooler 900. The low-temperature regenerator 200 is used to heat the supercritical carbon dioxide working medium after being pressurized by the main pump 100. The high-pressure side inlet of the low-temperature regenerator 200 is connected to the liquid outlet of the main pump 100, and the low-pressure side outlet of the low-temperature regenerator 200 is connected to the inlet of the cooler 900.

[0037] The high-temperature regenerator 400 is used to heat the supercritical carbon dioxide working medium heated by the low-temperature regenerator 200. The high-pressure side inlet of the high-temperature regenerator 400 is connected to the high-pressure side outlet of the low-temperature regenerator 200, and the low-pressure side outlet of the high-temperature regenerator 400 is connected to the low-pressure side inlet of the low-temperature regenerator 200.

[0038] The ultra-high temperature regenerator 500 is used to heat the supercritical carbon dioxide working medium heated by the high temperature regenerator 400. The high pressure side inlet of the ultra-high temperature regenerator 500 is connected to the high pressure side outlet of the high temperature regenerator 400, the low pressure side outlet of the ultra-high temperature regenerator 500 is connected to the low pressure side inlet of the high temperature regenerator 400, and the high pressure side outlet of the ultra-high temperature regenerator 500 is connected to the inlet of the high temperature heat accumulator 600.

[0039] The turbine 700 is used to drive the generator 800 to generate electricity. The inlet of the turbine 700 is connected to the outlet of the high-temperature heat accumulator 600, and the exhaust port of the turbine 700 is connected to the low-pressure side inlet of the ultra-high temperature regenerator 500.

[0040] The supercritical carbon dioxide cycle power generation device also includes a bypass compressor 1000 for compressing the supercritical carbon dioxide working fluid bypassed from the low-pressure side outlet of the low-temperature regenerator. The inlet of the bypass compressor 1000 is connected to the low-pressure side outlet of the low-temperature regenerator 200, and the outlet of the bypass compressor 1000 is connected to the high-pressure side inlet of the high-temperature regenerator 400.

[0041] The supercritical carbon dioxide circulation power generation device also includes a low-temperature heat accumulator 300 for heating the supercritical carbon dioxide working fluid diverted from the liquid outlet of the main pump. The inlet of the low-temperature heat accumulator 300 is connected to the liquid outlet of the main pump 100, and the outlet of the low-temperature heat accumulator 300 is connected to the high-pressure side outlet of the low-temperature regenerator 200.

[0042] The specific working principle of the present invention is as follows:

[0043] Under the energy storage condition, the phase change heat storage material in the phase change heat storage body 630 of the high temperature heat storage device 600 is heated to above the melting point (1083.4°C) during the electric heating energy storage process, and changes from solid to liquid, converting electrical energy into thermal energy. At the same time, low-grade waste heat enters the low temperature heat storage device 300 for collection.

[0044] Under the energy release condition, the supercritical carbon dioxide works in a cycle. The main pump 100 pressurizes the supercritical carbon dioxide working medium to about 25MPa. The supercritical carbon dioxide working medium after pressurization is divided into two paths. One path is heated to about 180°C by the low-temperature regenerator 200, and the other path is heated to about 180°C by the low-temperature heat storage device 300. After the two paths of working medium merge with the working medium from the split compressor 1000, they are heated to about 600°C by the high-temperature regenerator 400, and then heated to about 750°C by the ultra-high temperature regenerator 500, and then enter the high temperature regenerator 500. The warm heat accumulator 600 is heated to 1000°C, then enters the turbine 700 and expands to about 7MPa. The turbine 700 drives the generator 800 to generate electricity. The exhaust of the turbine 700 releases waste heat in turn through the ultra-high temperature regenerator 500, the high temperature regenerator 400 and the low temperature regenerator 200. The low pressure side outlet working fluid of the low temperature regenerator 200 is divided into two paths. One path enters the split compressor 1000 for pressurization and then enters the high temperature regenerator 400. The other path is cooled to 25°C through the cooler 900 and then returns to the main pump 100. The phase change heat storage material in the phase change heat storage body 630 of the high temperature regenerator 600 changes from liquid to solid during the heat release process and releases heat.

[0045] In summary, the heat of the phase change heat storage body in the high-temperature heat accumulator of the present invention is absorbed by the supercritical carbon dioxide working fluid, which can make it reach a high temperature of more than 1000°C, and the thermal efficiency of the supercritical carbon dioxide cycle can reach more than 63%. The heat energy of the high-temperature heat accumulator is accumulated through electric heating at night when the electricity rate is low. During the day when the electricity rate is high, the heat energy is converted into electrical energy through the supercritical carbon dioxide cycle. The energy conversion efficiency of the energy storage device formed can reach more than 60%. The device of the present invention integrates existing equipment and technology, and through system optimization configuration, there is no need to redevelop key equipment. The phase change heat storage material can be completely recovered and directly used or sold. The overall investment economy is good, and it can be built in industrial facilities with good environmental cooling conditions and waste heat, such as power plants, chemical plants, smelters, etc., using the cooling equipment, power facilities and management resources of the plant site, the comprehensive benefits of energy storage will be more prominent.

[0046] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. An electric energy storage device based on phase change heat storage, comprising: A supercritical carbon dioxide cycle power generation device for converting thermal energy into electrical energy through a supercritical carbon dioxide cycle; It is characterized in that The electric energy storage device based on phase change heat storage also includes a high-temperature heat storage device for converting electric energy into heat energy and storing the heat energy in the phase change heat storage material. The high-temperature heat storage device is arranged on the thermal cycle power generation device. During the heat release process, the phase change heat storage material transfers heat to the supercritical carbon dioxide working fluid. The high temperature heat accumulator comprises: - fire-resistant insulation for heat insulation; A cylindrical pressure vessel for withstanding the high pressure of supercritical carbon dioxide, the cylindrical pressure vessel being coated on the outer peripheral surface of the fire-resistant insulation layer; A phase-change heat storage body for storing heat generated by electrical heating, wherein the phase-change heat storage body is arranged in a space surrounded by a fire-resistant heat-insulating layer, two ends of the phase-change heat storage body are provided with power supply ends, and a phase-change heat storage material is arranged inside the phase-change heat storage body; The supercritical carbon dioxide circulation power generation device comprises: A cooler for cooling and liquefying supercritical carbon dioxide; A main pump for pressurizing the supercritical carbon dioxide working medium liquefied by the cooler to a set pressure value, wherein the liquid inlet of the main pump is connected to the liquid outlet of the cooler; A low-temperature regenerator for heating the supercritical carbon dioxide working medium after being pressurized by the main pump, wherein the high-pressure side inlet of the low-temperature regenerator is connected to the liquid outlet of the main pump, and the low-pressure side outlet of the low-temperature regenerator is connected to the inlet of the cooler; a high-temperature regenerator for heating the supercritical carbon dioxide working medium heated by the low-temperature regenerator, wherein the high-pressure side inlet of the high-temperature regenerator is connected to the high-pressure side outlet of the low-temperature regenerator, and the low-pressure side outlet of the high-temperature regenerator is connected to the low-pressure side outlet of the low-temperature regenerator; An ultra-high temperature regenerator for heating the supercritical carbon dioxide working medium heated by the high temperature regenerator, wherein the high pressure side inlet of the ultra-high temperature regenerator is connected to the high pressure side outlet of the high temperature regenerator, the low pressure side outlet of the ultra-high temperature regenerator is connected to the low pressure side inlet of the high temperature regenerator, and the high pressure side outlet of the ultra-high temperature regenerator is connected to the inlet of the high temperature heat accumulator; A turbine for driving a generator to generate electricity, wherein the inlet of the turbine is connected to the outlet of the high-temperature heat accumulator, and the exhaust port of the turbine is connected to the low-pressure side inlet of the ultra-high-temperature heat regenerator.

2. An electric energy storage device based on phase change heat storage as claimed in claim 1, characterized in that: The outer peripheral surface of the cylindrical pressure container is coated with a heat-insulating layer.

3. The power energy storage device based on phase change heat storage as claimed in claim 1, characterized in that: The supercritical carbon dioxide circulation power generation device also includes a bypass compressor for compressing the supercritical carbon dioxide working fluid bypassed from the low-pressure side outlet of the low-temperature regenerator, the inlet of the bypass compressor is connected to the low-pressure side outlet of the low-temperature regenerator, and the outlet of the bypass compressor is connected to the high-pressure side inlet of the high-temperature regenerator.

4. The power energy storage device based on phase change heat storage as claimed in claim 1, characterized in that: The supercritical carbon dioxide circulation power generation device also includes a low-temperature heat accumulator for heating the supercritical carbon dioxide working fluid diverted from the liquid outlet of the main pump, the inlet of the low-temperature heat accumulator is connected to the liquid outlet of the main pump, and the outlet of the low-temperature heat accumulator is connected to the high-pressure side inlet of the low-temperature regenerator.

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