Liquid air energy storage system coupled with natural resources and Stirling generator set

Abstract

The invention provides a liquid air energy storage system coupled with natural resources and a Stirling generator set, and particularly relates to the technical field of energy storage, the liquid air energy storage system coupled with the natural resources and the Stirling generator set comprises a compression unit, an expansion unit and a phase change unit, wherein the compression unit comprises a compressor unit, a generator unit, a cold source and a hot water tank, the phase change unit comprises a liquefier, a liquid air storage tank, an evaporator, a pressure pump and a preheater, compression heat of a compressor is recycled through the generator unit, power can be generated through heat energy, and the energy utilization rate is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage, and particularly to a liquid air energy storage system that couples natural resources and a Stirling generator set. Background Art

[0002] Industrial energy storage systems include batteries, pumped-storage hydroelectricity, and compressed air energy storage. Battery energy storage has the disadvantages of a short life cycle and high maintenance costs, while pumped-storage hydroelectricity and compressed air energy storage have geographical limitations. The liquid air energy storage system has the advantages of being not restricted by geography and having a high energy storage density. In the liquid air energy storage system, air is used as the working fluid in the charge and discharge processes. During off-peak hours, ambient air is compressed and cooled by the cold energy during the discharge process and stored in a low-temperature liquid air tank under ambient pressure. During peak hours, the stored liquid air is pumped and expanded to generate electricity. Currently, the efficiency of an independent liquid air energy storage system is low.

[0003] The liquid air energy storage system coupled with solar energy can increase the power generation during the discharge process and, compared with an independent liquid air energy storage system, can effectively improve the energy utilization rate. However, when the solar heat storage temperature is relatively high, the compression heat of air cannot be further coupled and utilized during the discharge process and needs to be used separately or discarded, and thus cannot be fully utilized. Summary of the Invention

[0004] In order to solve the problem that the compression heat of air cannot be fully utilized when the solar heat storage temperature is relatively high, the present invention proposes a liquid air energy storage system that couples natural resources and a Stirling generator set.

[0005] The present invention is achieved through the following technical solutions:

[0006] The liquid air energy storage system that couples natural resources and a Stirling generator set proposed by the present invention includes a compression unit, an expansion unit, and a phase change unit, wherein:

[0007] The compression unit includes a compressor set, a generator set, a cold source, and a hot water tank. The compressor set includes a first compressor, a second compressor, and a third compressor. The generator set includes a first generator, a second generator, and a third generator. The first compressor is sequentially connected to the hot end of the first generator, the second compressor, the hot end of the second generator, the third compressor, and the hot end of the third generator. The cold source is respectively connected to the cold end of the first generator, the cold end of the second generator, the cold end of the third generator and is connected to the hot water tank;

[0008] The phase change unit includes a liquefier, a liquid air storage tank, an evaporator, a pressurizing pump and a preheater. The hot end of the third generator is sequentially connected to the liquefier and the liquid air storage tank. One outlet end of the liquid air storage tank is connected to the outside through the liquefier, and the other outlet end is sequentially connected to the pressurizing pump, the evaporator and the preheater.

[0009] The expansion unit includes an expansion unit group and a heater group. The expansion unit group includes a first expander, a second expander and a third expander. The heater group includes a first heater, a second heater and a third heater. The outlet end of the preheater is sequentially connected to the first heater, the first expander, the second heater, the second expander, the third heater and the fourth expander. The outlet end of the fourth expander is sequentially connected to the other inlet end of the preheater and is connected to the outside from the outlet end of the preheater.

[0010] Further, the phase change unit further includes a throttling device, and the throttling device is located between the inlet of the liquefier and the liquid air storage tank.

[0011] Further, the phase change unit further includes a cold storage device, and both ends of the outlet end of the cold storage device are respectively connected in parallel with the evaporator and the liquefier.

[0012] Further, the expansion unit further includes a heat storage device, and both ends of the heat storage device are respectively connected in parallel with the first heater, the second heater and the third heater.

[0013] Further, the expansion unit further includes a solar heat collection device, and both ends of the solar heat collection device are respectively connected in parallel with the heat storage device.

[0014] Further, one outlet end of the first heater is sequentially connected to the inlet end of the second heater and is connected back to the inlet end of the first heater from one outlet end of the second heater.

[0015] Further, the generator set adopts a Stirling generator.

[0016] Advantages of the present invention:

[0017] (1) The liquid air energy storage system coupling natural resources and Stirling generator sets proposed by the present invention can recover the compression heat of air through the generator set. On the one hand, power generation can be carried out by recovering the air compression heat, which can well improve the energy utilization rate.

[0018] (2) The liquid air energy storage system coupling natural resources and Stirling generator sets proposed by the present invention can make full use of the heat energy of solar energy and the cold energy of seawater. After seawater is used for power generation, it is stored in a hot water tank to provide heat energy for other processes, which can maximize the energy utilization rate.

[0019] (3) The liquid air energy storage system coupling natural resources and a Stirling generator set provided by the present invention has a higher power generation efficiency compared with other heat energy utilization methods such as the organic Rankine cycle and the Kalina cycle that adopt the Stirling cycle. At the same time, it also has higher safety and environmental protection performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a structural diagram of the liquid air energy storage system coupling natural resources and a Stirling generator set of the present invention;

[0021] In the figure: compression unit 1, first compressor 11, second compressor 12, third compressor 13, first generator 14, second generator 15, third generator 16, hot water tank 17, phase change unit 2, liquefier 21, liquid air storage tank 22, throttling device 23, cold storage device 24, pressure pump 25, evaporator 26, preheater 27, expansion unit 3, first heater 31, second heater 32, third heater 33, first expander 34, second expander 35, third expander 36, heat storage device 37, solar collector 38;

[0022] The implementation, functional characteristics and advantages of the present invention will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION OF THE EMBODIMENTS

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

[0024] Please refer to Figure 1 , the present invention provides a liquid air energy storage system coupling natural resources and a Stirling generator set, which includes a compression unit 1, an expansion unit 3 and a phase change unit 2, wherein:

[0025] The compression unit 1 includes a compressor set, a generator set, a cold source and a hot water tank 17. The compressor set includes a first compressor 11, a second compressor 12 and a third compressor 13. The generator set includes a first generator 14, a second generator 15 and a third generator 16. The first compressor 11 is sequentially connected to the hot end of the first generator 14, the second compressor 12, the hot end of the second generator 15, the third compressor 13 and the hot end of the third generator 16. The cold source is respectively connected to the cold end of the first generator 14, the cold end of the second generator 15, the cold end of the third generator 16 and is connected to the hot water tank 17;

[0026] The phase change unit 2 includes a liquefier 21, a liquid air storage tank 22, an evaporator 26, a pressurizing pump 25, and a preheater 27. The hot end of the third generator 16 is sequentially connected to the liquefier 21 and the liquid air storage tank 22. One outlet end of the liquid air storage tank 22 is connected to the outside of the liquefier 21, and the other outlet end is sequentially connected to the pressurizing pump 25, the evaporator 26, and the preheater 27;

[0027] The expansion unit 3 includes an expansion unit and a heater group. The expansion unit includes a first expander 34, a second expander 35, and a third expander 36. The heater group includes a first heater 31, a second heater 32, and a third heater 33. The outlet end of the preheater 27 is sequentially connected to the first heater 31, the first expander 34, the second heater 32, the second expander 35, the third heater 33, and the fourth expander. The outlet end of the fourth expander is sequentially connected to the other inlet end of the preheater 27 and is connected to the outside from the outlet end of the preheater 27.

[0028] In this embodiment:

[0029] The compressor unit is used to compress air;

[0030] The generator set is used to generate electricity by absorbing compression heat;

[0031] The cold source is used to provide cold energy for the generator set;

[0032] The hot water tank 17 is used to store thermal energy;

[0033] The liquefier 21 is used for air liquefaction;

[0034] The liquid air storage tank 22 is used to store liquid air;

[0035] The evaporator 26 is used for gasification of liquid air and recovery of cold energy;

[0036] The preheater 27 is used to recover the thermal energy of the expanded air;

[0037] The expansion unit is used for expansion power generation;

[0038] The heater group is used to increase the expansion temperature;

[0039] Specifically, during energy storage, air sequentially passes through the first compressor 11, the first generator 14, the second compressor 12, the second generator 15, the third compressor 13, and the third generator 16. The compressor compresses the air, and at the same time, the generator recovers the thermal energy of the compressed air and generates electricity through the temperature difference using seawater as the cold end of the generator. After absorbing heat, it becomes hot water and is stored in the hot water tank 17 for heating. Subsequently, the air enters the liquefier 21 to be cooled, becomes normal-pressure liquid air through the throttling device 23, and is stored in the liquid air storage tank 22. The gas that has not been converted into liquid air flows out to the outside after recovering the cold energy through the liquefier 21;

[0040] During the energy release stage, the liquid air in the liquid air storage tank 22 is conveyed by a pressurizing pump 25, and cold energy recovery is carried out through an evaporator 26, turning into a gas state. Subsequently, it is preheated by a preheater 27, and then heated by a first heater 31, expanded by a first expander 34, heated by a second heater 32, expanded by a second expander 35, passed through a third heater 33, and expanded by a third heater. The air at the end of the expander enters the preheater 27 to recover heat and preheat the subsequent air;

[0041] In the present invention, the compression heat is utilized by a generator set, which can well recover the compression heat and improve the energy utilization efficiency.

[0042] In one embodiment, the number of compressors, heaters, expanders, and generators in the compressor set, heater set, expander set, and generator set can be selected according to actual conditions, which can be three-stage or more. A generator is connected after each stage of the compressor, and a heater is connected before each stage of the expander. The generator recovers the compression heat and at the same time cools the air at the outlet of the compressor, reducing the electric energy consumed during the energy storage process. The heater heating the working fluid can improve the output power of the expander.

[0043] Furthermore, the phase change unit 2 further includes a throttling device 23, and the throttling device 23 is located between the inlet of the liquefier 21 and the liquid air storage tank 22.

[0044] In this embodiment:

[0045] The throttling device 23 is used to throttle and expand the liquid air to atmospheric pressure;

[0046] Specifically, the liquefied liquid air enters the throttling device 23 for throttling and expanding to atmospheric pressure, and then enters the liquid air storage tank 22 for storage. The throttling device 23 can be a hydraulic turbine or a throttle valve, which can be selected according to actual requirements.

[0047] Furthermore, the phase change unit 2 further includes a cold storage device 24, and the two ends of the outlet end of the cold storage device 24 are respectively connected in parallel with the evaporator 26 and the liquefier 21.

[0048] In this embodiment:

[0049] The cold storage device 24 is used to store and release cold energy;

[0050] Specifically, the cold storage device 24 provides cold energy to the liquefier 21 to liquefy the compressed high-pressure air, and after throttling through the throttling device 23, it is stored in the liquid air storage tank 22. When the liquid air in the liquid air storage tank 22 is released, the cold energy of the liquid air is transferred to the cold storage device 24 through the evaporator 26 for storage, thereby improving the utilization rate of cold energy.

[0051] Further, the expansion unit 3 further includes a heat storage device 37, and both ends of the heat storage device 37 are respectively connected in parallel with the first heater 31, the second heater 32, and the third heater 33;

[0052] The expansion unit 3 further includes a solar heat collection device 38, and both ends of the solar heat collection device 38 are respectively connected in parallel with the heat storage device 37.

[0053] In this embodiment:

[0054] The heat storage device 37 is used to store and release thermal energy;

[0055] Specifically, the solar heat collection device 38 collects solar heat, and then the heat storage device 37 stores the collected thermal energy. Both ends of the heat storage device 37 are respectively connected in parallel with the first heater 31, the second heater 32, and the third heater 33, and respectively provide heat for the first heater 31, the second heater 32, and the third heater 33. The heaters heat the air to increase the energy output of the expander.

[0056] In one embodiment, the heat storage device 37 and the cold storage device 24 can adopt solid-phase heat storage, such as using a packed bed filled with quartz sand, sand, and industrial slag, using refractory bricks, concrete, etc. as fixed windows, or can also adopt liquid-phase heat storage such as high-pressure water, liquid metal, molten salt, or can also adopt phase change materials or thermochemical heat storage, and can be selected according to actual needs.

[0057] Further, the generator set adopts a Stirling generator.

[0058] In this embodiment:

[0059] The Stirling generator is used to generate electricity by utilizing the temperature difference between thermal energy and cold energy;

[0060] Specifically, the Stirling generator has outstanding advantages such as high efficiency, high reliability, simple structure, long life, and environmental protection. The Stirling generator uses the thermal energy of compressed air and the temperature difference at the cold end to cause the working medium inside the thermal energy Stirling power generation device to be cooled and compressed and absorb heat and expand, driving the cylinder to do piston motion, thereby outputting power to drive the generator to generate electricity. The working fluid of the generator can be selected according to actual conditions, including but not limited to air, helium, hydrogen, nitrogen, etc. The generator can also select other generators or power generation cycles that use temperature difference for power generation, such as the organic Rankine cycle, the Kalina cycle, etc.

[0061] Further, the cold source is seawater.

[0062] Specifically, the cold source of the generator set is seawater. The seawater can also be replaced with other liquids or gases that can provide cold energy, which can be selected according to actual needs. As the cold source, after the seawater is heated, the thermal energy of the seawater can be used for other processes.

[0063] Of course, the present invention can also have many other implementation manners. Based on this implementation manner, other implementation manners obtained by those of ordinary skill in the art without any creative work belong to the scope protected by the present invention.

Claims

1. A liquid air energy storage system coupling natural resources and a Stirling generator set, characterized in that It includes a compression unit, an expansion unit and a phase change unit, where: The compression unit includes a compressor set, a generator set, a cold source and a hot water tank. The compressor set includes a first compressor, a second compressor and a third compressor. The generator set includes a first generator, a second generator and a third generator. The first compressor is sequentially connected to the hot end of the first generator, the second compressor, the hot end of the second generator, the third compressor and the hot end of the third generator. The cold source is respectively connected to the cold ends of the first generator, the second generator and the third generator and is connected to the hot water tank; The phase change unit includes a liquefier, a liquid air storage tank, an evaporator, a pressure pump and a preheater. The hot end of the third generator is sequentially connected to the liquefier and the liquid air storage tank. One outlet end of the liquid air storage tank is connected to the outside through the liquefier, and the other outlet end is sequentially connected to the pressure pump, the evaporator and the preheater; The expansion unit includes an expansion machine set and a heater set. The expansion machine set includes a first expander, a second expander and a third expander. The heater set includes a first heater, a second heater and a third heater. The outlet end of the preheater is sequentially connected to the first heater, the first expander, the second heater, the second expander, the third heater and the fourth expander. The outlet end of the fourth expander is sequentially connected to the other inlet end of the preheater and is connected to the outside from the outlet end of the preheater.

2. The liquid air energy storage system coupling natural resources and a Stirling generator set according to claim 1, wherein The phase change unit further includes a throttling device, and the throttling device is located between the inlet of the liquefier and the liquid air storage tank.

3. The liquid air energy storage system coupling natural resources and a Stirling generator set according to claim 2, wherein The phase change unit further includes a cold storage device, and both ends of the outlet end of the cold storage device are respectively connected in parallel with the evaporator and the liquefier.

4. The liquid air energy storage system coupling natural resources and a Stirling generator set according to claim 1, characterized in that, The expansion unit further includes a heat storage device, and both ends of the heat storage device are respectively connected in parallel with the first heater, the second heater and the third heater.

5. The liquid air energy storage system coupling natural resources and a Stirling generator set according to claim 4, wherein The expansion unit further includes a solar heat collection device, and both ends of the solar heat collection device are respectively connected in parallel with the heat storage device.

6. The liquid air energy storage system coupling natural resources and a Stirling generator set according to claim 1, wherein The generator set uses a Stirling generator.

7. The liquid air energy storage system coupling natural resources and a Stirling generator set according to claim 1, wherein The cold source is seawater.

Images