Liquid air energy storage system coupled with thermochemical energy storage

Abstract

The invention provides a liquid air energy storage system coupled with thermochemical energy storage, and particularly relates to the technical field of energy storage.The liquid air energy storage system coupled with thermochemical energy storage comprises a liquid air energy storage unit and a thermochemical energy storage unit, and the thermochemical energy storage unit comprises a desorption device, a first storage tank, an absorption device and a second storage tank; a first heat exchanger is arranged in the desorption device, a second heat exchanger is arranged in the absorption device, compression heat is efficiently stored through the thermochemical energy storage unit, after the desorption device absorbs the compression heat, a working medium in the desorption device is desorbed, a gas-phase refrigerant and a concentrated solution are formed, and in the peak period of energy consumption, the gas-phase refrigerant and the concentrated solution are separated. By means of the liquid air energy storage system coupled with thermochemical energy storage, peak load shifting of electricity / heat energy can be achieved, the demand for electricity / heat energy on the load side can be quickly and flexibly responded, and the power generation power and the energy efficiency of the system are improved.

Description

Technical Field

[0001] The present invention relates to the field of energy storage technology, and in particular to a liquid air energy storage system coupled with thermochemical energy storage. Background Art

[0002] Energy storage technology is a technology that converts energy in the form of electricity, thermal energy, kinetic energy, etc. into storable energy forms and releases the corresponding energy when needed. Among the existing energy storage technologies, liquid air energy storage technology has the characteristics of large-scale and long-term operation, no geographical restrictions, long life, environmental friendliness, and easy and flexible coupling with energy and chemical processes.

[0003] Liquid air energy storage technology uses renewable energy or off-peak electricity to drive the air during low energy consumption periods. After multi-stage compression, the air is liquefied and stored at normal pressure. During peak electricity consumption periods, the liquid air is pressurized by a pump to release cold energy, expand, and generate electricity. The liquid air energy storage system can not only improve power supply stability, but also provide frequency regulation services for the power system. Currently, in order to reduce the heat loss of compression heat during the intermittent period, high-efficiency insulation measures are required, and thermal oil is usually used as the carrier of compression heat for storage. The high-efficiency insulation measures and the price of thermal oil are very expensive, which limits the effective utilization of compression heat and further hinders the efficiency improvement of the liquid air energy storage system.

[0004] In view of this, the present invention proposes a liquid air energy storage system that can achieve long-term thermal energy storage, has low heat quality loss, is easy to achieve flexible heating, and is conducive to efficient utilization of compression heat. Summary of the Invention

[0005] In order to solve the problem of low compression heat recovery efficiency, the present invention proposes a liquid air energy storage system coupled with thermochemical energy storage.

[0006] The present invention is achieved through the following technical solutions:

[0007] The present invention proposes a liquid air energy storage system coupled with thermochemical energy storage, comprising a liquid air energy storage unit and a thermochemical energy storage unit, wherein:

[0008] The thermochemical energy storage unit includes a desorption device, a first storage tank, an absorption device, and a second storage tank. The desorption device is provided with a first heat exchanger, and the absorption device is provided with a second heat exchanger. One side of the desorption device is respectively connected to the first storage tank, the absorption device, and the second storage tank and is connected back to the desorption device.

[0009] The thermochemical energy storage unit further includes a condensing device, a third storage tank and an evaporating device, and one end of the desorption device is connected to the condensing device, the third storage tank, the evaporating device and the absorbing device in sequence;

[0010] The liquid air energy storage unit includes a compression end and an expansion end, the first heat exchanger is connected to the compression end, and the second heat exchanger is connected to the expansion end.

[0011] Furthermore, the thermochemical energy storage unit further includes a throttling device, which is arranged between the third storage tank and the evaporation device.

[0012] Furthermore, the liquid air energy storage system includes a compressor unit, a third heat exchanger, a cold storage device, a fourth storage tank, a fourth heat exchanger and an expansion unit. The compressor unit is connected to the third heat exchanger, one side of the cold storage device and the inlet end of the fourth storage tank in sequence, and is connected to the other side of the cold storage device, the fourth heat exchanger unit and the expansion unit in sequence from the outlet end of the fourth storage tank.

[0013] Furthermore, the third heat exchanger is connected in parallel with the first heat exchanger, and the fourth heat exchanger is connected in parallel with the second heat exchanger.

[0014] Furthermore, a pressure reducing device is provided between one side of the cold storage device and the inlet end of the fourth storage tank.

[0015] Furthermore, a low-temperature pump is provided between the outlet end of the fourth storage tank and the other side of the cold storage device.

[0016] Furthermore, the compressor unit includes at least one compressor, the expander unit includes at least one expander, a third heat exchanger is provided at the outlet end of each compressor, and a fourth heat exchanger is provided at the inlet end of each expander.

[0017] Furthermore, when the liquid air energy storage unit stores energy, the desorption device desorbs the working fluid inside after absorbing heat and converts it into a gas-phase refrigerant and a concentrated solution. The concentrated solution enters the first storage tank for storage, and the refrigerant enters the condensing device, is condensed into a liquid phase and stored in the third storage tank; when the liquid air energy storage unit releases energy, the refrigerant in the third storage tank flows into the evaporation device to be vaporized, and enters the absorption device under the absorption action, and the concentrated solution in the first storage tank flows out of the first storage tank and enters the absorption device to react with the refrigerant and release heat.

[0018] Beneficial effects of the present invention:

[0019] The liquid air energy storage system coupled with thermochemical energy storage proposed in the present invention recovers compression heat through the thermochemical energy storage unit during low energy consumption. After the desorption device absorbs the compression heat, the working fluid in the desorption device desorbs to form a gas-phase refrigerant and a concentrated solution. During peak energy consumption, the concentrated solution and the refrigerant undergo an absorption reaction to release heat, providing heat for the fourth heat exchanger at the inlet end of the expansion unit. The liquid air energy storage system coupled with thermochemical energy storage proposed in the present invention can achieve peak shaving and valley filling of electricity / heat energy, quickly and flexibly respond to the electricity / heat energy demand on the load side, and improve the system's power generation power and energy efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the liquid air energy storage system coupled with thermochemical energy storage of the present invention;

[0021] In the figure: liquid air energy storage unit 1, compressor unit 101, third heat exchanger 102, cold storage device 103, pressure reduction device 104, fourth storage tank 105, cryogenic pump 106, fourth heat exchanger 107, expansion unit 108, thermochemical energy storage unit 2, first heat exchanger 201, desorption device 202, first storage tank 203, condensing device 204, third storage tank 205, throttling device 206, evaporation device 207, absorption device 208, second heat exchanger 209, second storage tank 210;

[0022] The implementation, functional features and advantages of the present invention will be further described with reference to the accompanying drawings in conjunction with the embodiments. DETAILED DESCRIPTION

[0023] In order to more clearly and completely illustrate the technical solution of the present invention, the present invention is further described below with reference to the accompanying drawings.

[0024] Please refer to Figure 1 The present invention proposes a liquid air energy storage system coupled with thermochemical energy storage, comprising a liquid air energy storage unit 1 and a thermochemical energy storage unit 2, wherein:

[0025] Thermochemical energy storage unit 2 includes a desorption device 202, a first storage tank 203, an absorption device 208, and a second storage tank 210. The desorption device 202 is provided with a first heat exchanger 201, and the absorption device 208 is provided with a second heat exchanger 209. One side of the desorption device 202 is respectively connected to the first storage tank 203, the absorption device 208, and the second storage tank 210 and is connected back to the desorption device 202;

[0026] The thermochemical energy storage unit 2 further includes a condensing device 204, a third storage tank 205 and an evaporating device 207, and one end of the desorption device 202 is connected to the condensing device 204, the third storage tank 205, the evaporating device 207 and the absorbing device 208 in sequence;

[0027] The liquid air energy storage unit 1 includes a compression end and an expansion end. The first heat exchanger 201 is connected to the compression end, and the second heat exchanger 209 is connected to the expansion end.

[0028] In this embodiment:

[0029] The desorption device 202 is used to absorb the heat source and generate a desorption reaction to form a gas-phase refrigerant and a concentrated solution;

[0030] The absorption device 208 is used to cause the refrigerant and the concentrated solution to undergo an absorption reaction and provide heat;

[0031] The first storage tank 203 is used to store concentrated solution;

[0032] The second storage tank 210 is used to store the dilute solution;

[0033] The third storage tank 205 is used to store refrigerant;

[0034] The condensing device 204 is used to condense the gas phase refrigerant into the liquid phase;

[0035] The evaporation device 207 is used to vaporize the refrigerant;

[0036] Specifically, during the low energy consumption phase, the compression heat of the compression end of the liquid air energy storage unit 1 is transferred to the first heat exchanger 201, and the first heat exchanger 201 transfers the heat to the desorption device 202. Under the input of the heat source, the working medium in the desorption device 202 is desorbed to form a gas-phase refrigerant and a concentrated solution. The concentrated solution enters the first storage tank 203 for storage, and the refrigerant enters the condensing device 204 to be condensed into a liquid phase and stored in the third storage tank 205. During the peak energy consumption phase, the refrigerant flows out of the third storage tank 205 and flows into the evaporation device 207 to be vaporized. Under the absorption effect, it enters the absorption device 208. At the same time, the concentrated solution also flows out of the first storage tank 203 and enters the absorption device 208. The concentrated solution reacts with the refrigerant to release heat, and the second heat exchanger 209 transfers the heat to the expansion end to provide preheating. Finally, the dilute solution in the absorption device 208 is stored in the second storage tank 210. The present invention utilizes the thermochemical energy storage unit 2 to recover compression heat through desorption reaction and absorption reaction, has the characteristics of fast response speed and can realize efficient storage of thermal energy. Secondly, it can also greatly reduce the amount of heat storage medium and the use of high-efficiency insulation materials in the liquid air energy storage system, thereby reducing the cost of compression heat storage.

[0037] In one embodiment, not only the compression heat in the liquid air energy storage unit 1 can be used as the heat source required by the desorption device 202, but industrial waste heat, solar thermal energy, geothermal energy, etc. can also be used as the heat source required by the desorption device 202, which can also achieve the same effect.

[0038] In one embodiment, the working fluid in the desorption device 202 in the thermochemical energy storage unit 2 can be a working fluid that is environmentally friendly to water systems, such as calcium chloride, lithium chloride, lithium bromide, sodium hydroxide, potassium hydroxide, or an aqueous solution of ammonia.

[0039] Furthermore, the thermochemical energy storage unit 2 further includes a throttling device 206 , which is disposed between the third storage tank 205 and the evaporation device 207 .

[0040] Specifically, the throttling device 206 is used to reduce the pressure of the refrigerant;

[0041] Furthermore, the liquid air energy storage system includes a compressor unit 101, a third heat exchanger 102, a cold storage device 103, a fourth storage tank 105, a fourth heat exchanger 107 and an expansion unit 108. The compressor unit 101 is sequentially connected to the third heat exchanger 102, one side of the cold storage device 103 and the inlet end of the fourth storage tank 105, and is sequentially connected from the outlet end of the fourth storage tank 105 to the other side of the cold storage device 103, the fourth heat exchanger 107 and the expansion unit 108.

[0042] A pressure reducing device 104 is provided between one side of the cold storage device 103 and the inlet end of the fourth storage tank 105;

[0043] A cryogenic pump 106 is provided between the outlet of the fourth storage tank 105 and the other side of the cold storage device 103 .

[0044] In this embodiment:

[0045] The compressor unit 101 is used to compress air;

[0046] The third heat exchanger 102 is used to recover compression heat;

[0047] The cold storage device 103 is used to recover the cold energy after the liquid air is vaporized and provide cold energy for the air liquefaction;

[0048] The fourth storage tank 105 is used to store liquid air;

[0049] The fourth heat exchanger 107 is used to provide heat to the expander inlet air;

[0050] The expander unit 108 is used to expand air and generate power;

[0051] Specifically, during the low energy consumption stage, the compressor unit 101 is driven by renewable energy power or low-valley power to pressurize the air to a high-temperature and high-pressure state. The high-temperature and high-pressure air is heat exchanged to a normal temperature state through the third heat exchanger 102, and then flows through the cold storage device 103 to be further cooled. After obtaining cold energy, it becomes high-pressure and low-temperature air, and then passes through the pressure reduction device 104 to reduce the pressure and liquefy it, and is converted into normal-pressure liquid air and stored in the fourth storage tank 105; during the peak energy consumption stage, the liquid air is pressurized and transported by the low-temperature pump 106, flows through the cold storage device 103 to release the cold energy, and is then reheated and vaporized into normal-temperature and high-pressure air. Finally, it is heated to high-temperature air through the fourth heat exchanger 107, and enters the expansion unit 108 to expand and generate electricity.

[0052] Furthermore, the third heat exchanger 102 is connected in parallel with the first heat exchanger 201 , and the fourth heat exchanger 107 is connected in parallel with the second heat exchanger 209 .

[0053] In this embodiment:

[0054] The third heat exchanger 102 transfers heat to the first heat exchanger 201;

[0055] The fourth heat exchanger 107 is used to absorb heat from the second heat exchanger 209;

[0056] Specifically, the heat exchange medium in the first heat exchanger 201 flows into the third heat exchanger 102 to convect with the high-temperature air, and takes away the compression heat in the air, and finally flows back to the first heat exchanger 201 and provides heat for the desorption device 202. The heat exchange medium in the second heat exchanger 209 enters the fourth heat exchanger 107 and provides heat for the fourth heat exchanger 107, and finally flows back to the second heat exchanger 209.

[0057] Furthermore, the compressor unit 101 includes at least one compressor, the expander unit 108 includes at least one expander, a third heat exchanger 102 is provided at the outlet of each compressor, and a fourth heat exchanger 107 is provided at the inlet of each expander.

[0058] In this embodiment:

[0059] The compressor in the compressor unit 101 and the expander in the expander unit 108 can be connected in parallel or in series;

[0060] Specifically, the number of compressors in the compressor group 101 and the number of expanders in the expander group 108 can be selected according to actual needs, and can be one or more. Each compressor outlet is equipped with a third heat exchanger 102 to recover compression heat, and each expander inlet is equipped with a fourth heat exchanger 107 to utilize the stored compression heat and increase the power generation power of the expander.

[0061] Furthermore, when the liquid air energy storage unit 1 stores energy, the desorption device 202 desorbs the working fluid inside after absorbing heat and converts it into a gas-phase refrigerant and a concentrated solution. The concentrated solution enters the first storage tank 203 for storage, and the refrigerant enters the condensing device 204 to be condensed into a liquid phase and stored in the third storage tank 205; when the liquid air energy storage unit 1 releases energy, the refrigerant in the third storage tank 205 flows into the evaporation device 207 to be vaporized, and enters the absorption device 208 under the absorption action, and the concentrated solution in the first storage tank 203 flows out of the first storage tank 203 and enters the absorption device 208 to react with the refrigerant and release heat.

[0062] Specifically, in the energy consumption low phase (i.e., storing compression heat), the compression heat generated by the air in the liquid air energy storage unit 1 during the compression process is transferred to the heat exchange medium through the third heat exchanger 102. The heat exchange medium enters the first heat exchanger 201 and transfers the heat to the desorption device 202. The working medium in the desorption device 202 desorbs after absorbing the heat to form a gas-phase refrigerant and a concentrated solution. The concentrated solution enters the first storage tank 203 for storage, and the gas-phase refrigerant enters the condensing device 204 to be condensed into a liquid phase and stored in the third storage tank 205. In the energy consumption peak phase (i.e., releasing the compression heat), the heat generated by the compression heat is transferred to the heat exchange medium through the third heat exchanger 102. The heat exchange medium enters the first heat exchanger 201 and transfers the heat to the desorption device 202. The working medium in the desorption device 202 desorbs after absorbing the heat to form a gas-phase refrigerant and a concentrated solution. The concentrated solution enters the first storage tank 203 for storage, and the gas-phase refrigerant enters the condensing device 204 to be condensed into a liquid phase and stored in the third storage tank 205. Heat), the refrigerant in the third storage tank 205 flows out, is depressurized by the throttling device 206 and enters the evaporator 207 to be vaporized, and enters the absorption device 208 under the absorption action. At the same time, the concentrated solution also flows out of the first storage tank 203 and enters the absorption device 208. The refrigerant and the concentrated solution undergo absorption reaction to release heat. The heat exchange medium flows through the second heat exchanger 209 and transfers the heat to the fourth heat exchanger 107 to provide heat for the inlet end of the expander, and the dilute solution after the reaction is stored in the second storage tank 210, so that the dilute solution can enter the desorption device 202 for reaction during the next cycle.

[0063] Of course, the present invention may have many other implementations. Based on this implementation, other implementations obtained by ordinary technicians in this field without any creative work are all within the scope of protection of the present invention.

Claims

1. A liquid air energy storage system coupled with thermochemical energy storage, characterized in that: It includes liquid air energy storage unit and thermochemical energy storage unit, wherein: The thermochemical energy storage unit includes a desorption device, a first storage tank, an absorption device, and a second storage tank. The desorption device is provided with a first heat exchanger, and the absorption device is provided with a second heat exchanger. One side of the desorption device is respectively connected to the first storage tank, the absorption device, and the second storage tank and is connected back to the desorption device. The thermochemical energy storage unit further includes a condensing device, a third storage tank and an evaporating device, and one end of the desorption device is connected to the condensing device, the third storage tank, the evaporating device and the absorbing device in sequence; The liquid air energy storage unit includes a compression end and an expansion end, the first heat exchanger is connected to the compression end, and the second heat exchanger is connected to the expansion end.

2. The liquid air energy storage system coupled with thermochemical energy storage according to claim 1, characterized in that: The thermochemical energy storage unit further includes a throttling device, which is arranged between the third storage tank and the evaporation device.

3. The liquid air energy storage system coupled with thermochemical energy storage according to claim 1, characterized in that: The liquid air energy storage system includes a compressor group, a third heat exchanger, a cold storage device, a fourth storage tank, a fourth heat exchanger and an expansion group. The compressor group is connected to the third heat exchanger, one side of the cold storage device and the inlet end of the fourth storage tank in sequence, and is connected to the other side of the cold storage device, the fourth heat exchanger group and the expansion group in sequence from the outlet end of the fourth storage tank.

4. The liquid air energy storage system coupled with thermochemical energy storage according to claim 3, characterized in that: The third heat exchanger is connected in parallel with the first heat exchanger, and the fourth heat exchanger is connected in parallel with the second heat exchanger.

5. The liquid air energy storage system coupled with thermochemical energy storage according to claim 3, characterized in that: A pressure reducing device is provided between one side of the cold storage device and the inlet end of the fourth storage tank.

6. The liquid air energy storage system coupled with thermochemical energy storage according to claim 5, characterized in that: A low-temperature pump is provided between the outlet end of the fourth storage tank and the other side of the cold storage device.

7. The liquid air energy storage system coupled with thermochemical energy storage according to claim 3, characterized in that: The compressor unit includes at least one compressor, the expander unit includes at least one expander, a third heat exchanger is provided at the outlet end of each compressor, and a fourth heat exchanger is provided at the inlet end of each expander.

8. The liquid air energy storage system coupled with thermochemical energy storage according to claim 1, characterized in that: When the liquid air energy storage unit stores energy, the desorption device absorbs heat, and the working medium inside desorbs and converts into gas-phase refrigerant and concentrated solution. The concentrated solution enters the first storage tank for storage, and the refrigerant enters the condensing device to be condensed into liquid phase and stored in the third storage tank. When the liquid air energy storage unit releases energy, the refrigerant in the third storage tank flows into the evaporation device to vaporize, and enters the absorption device under the absorption action. The concentrated solution in the first storage tank flows out of the first storage tank and enters the absorption device to react with the refrigerant to release heat.

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