CN-122015551-A - Extra-high temperature compressed air energy storage system and method

CN122015551ACN 122015551 ACN122015551 ACN 122015551ACN-122015551-A

Abstract

The invention discloses an extra-high temperature compressed air energy storage system and method, and relates to the technical field of thermal energy engineering. The system comprises a compression energy storage subsystem, an expansion power generation subsystem, a heat regenerator and a molten salt heat storage loop, wherein the compression energy storage subsystem comprises a compressor unit and a heat storage heat exchanger unit, the expansion power generation subsystem comprises a heat release heat exchanger unit and an expansion unit which are operated alternately in time, and the heat storage heat exchanger unit, the heat regenerator and the compressor unit which are used for storing compression heat in the compression process, the heat release heat exchanger unit, the heat regenerator and the expansion unit which are used for releasing heat to heat air in the expansion process can be integrated into the same set of physical equipment set respectively. The invention can realize the ultra-high temperature compression, the heat storage temperature area is perfectly matched with the binary nitrate solar salt, a low-temperature heat storage system is omitted, the problems of low energy storage efficiency, complex system and high cost of the existing compressed air are solved, and the step-type improvement of the efficiency, the simplification of the system and the remarkable reduction of the cost are realized.

Inventors

ZANG JINGUANG
WANG JUNFENG
LIU GUANGXU
DENG GUOLIANG

Assignees

浙江态能动力技术有限公司

Dates

Publication Date: 20260512
Application Date: 20260330

Claims (10)

1. An extra-high temperature compressed air energy storage system, includes compression energy storage subsystem and inflation power generation subsystem of alternate operation in time, its characterized in that: The compression energy storage subsystem comprises a compressor unit for compressing air to high temperature and generating high-temperature compression heat, and a heat storage heat exchanger unit for storing the high-temperature compression heat in a heat storage medium in the compression process; The expansion power generation subsystem comprises an exothermic heat exchanger group and an expansion unit, wherein the exothermic heat exchanger group is used for extracting heat from the heat storage medium to heat air in the expansion process, and the expansion unit is used for expanding the heated air to do work; The heat regenerator is configured to preheat ambient air entering the system and cool the high-pressure air finally cooled by the heat storage heat exchanger set in a compression mode, and preheat normal-temperature high-pressure air from a high-pressure air reservoir and utilize waste heat of exhaust gas after expansion in an expansion mode; the heat storage medium is high-temperature molten salt to form a molten salt heat storage loop.
2. The ultra-high temperature compressed air energy storage system of claim 1, wherein the compressor train is configured to bring its outlet air temperature to 500 ℃ to 600 ℃, the heat storage heat exchanger train is configured to cool air from the compressor to 290 ℃ to 320 ℃, and the heat release heat exchanger train is configured to heat air entering the expander to 470 ℃ to 570 ℃.
3. The ultra-high temperature compressed air energy storage system according to claim 2, wherein the compressor unit comprises five stages of compressors connected in series in sequence, wherein the first four stages of compressors are in constant pressure compression, the fifth stage of compressors is configured to operate in a variable pressure mode, the inlet pressure of the fifth stage of compressors is constant, and the outlet pressure of the fifth stage of compressors increases along with the increase of the pressure in a high-pressure gas storage reservoir of the system.
4. The ultra-high temperature compressed air energy storage system according to claim 3, wherein the outlet pressure of the first four stage compressor is respectively 0.24 to 0.32 MPa, 0.75 to 1.0 MPa, 2.5 to 3.3 MPa and 7.5 to 10.5 MPa, and the inlet pressure of the fifth stage compressor is constantly a predetermined value in the range of 7.8 to 10.5 MPa, from which the outlet pressure is variable-pressure operated to 13 to 18 MPa.
5. The ultra-high temperature compressed air energy storage system of claim 1, wherein the heat storage medium used in the molten salt heat storage circuit is a binary nitrate solar salt.
6. The ultra-high temperature compressed air energy storage system according to claim 1, wherein the heat storage heat exchanger group and the heat release heat exchanger group are the same set of physical heat exchange equipment group and are configured by switching a pipeline and a valve so as to be respectively connected into corresponding air flow paths in a compression mode and an expansion mode.
7. The ultra-high temperature compressed air energy storage system according to claim 1, wherein the regenerator is physically the same set of heat exchange equipment, and the functional conversion between the compression mode and the expansion mode is realized through valve switching.
8. The ultra-high temperature compressed air energy storage system according to claim 1, wherein the multi-stage compressor in the compressor unit and the multi-stage expander in the expander unit are physically the same set of reversible turbomachinery, and the switching of the operation mode is achieved by switching the flow channels and adjusting the internal adjustable guide vanes through the valves.
9. An extra-high temperature compressed air energy storage method, which is characterized in that an extra-high temperature compressed air energy storage system as claimed in any one of claims 1 to 8 is adopted, and the method comprises a compressed energy storage process and an expansion power generation process; the compression energy storage process comprises the following steps: S1, purifying ambient air, and then performing multistage compression to generate high-temperature compressed air with the temperature of 500-600 ℃; s2, introducing the high-temperature compressed air into a heat storage heat exchanger group, cooling the high-temperature compressed air to 290-320 ℃, and storing compression heat in high-temperature molten salt; s3, further cooling the high-pressure air finally cooled in the step S2, and injecting the high-pressure air into a high-pressure air reservoir for storage after pressure transformation and compression; the expansion power generation process comprises the following steps: P1, preheating high-pressure air released from a high-pressure air reservoir; P2, introducing preheated high-pressure air into an exothermic heat exchanger group, and heating the preheated high-pressure air to 470-570 ℃ by utilizing the heat stored by the high-temperature molten salt; and P3, performing multistage expansion work on the heated high-temperature high-pressure air.
10. The method according to claim 9, wherein the ambient air entering the system is preheated by a regenerator during the compression energy storage process, and the high-pressure air finally cooled by the heat storage heat exchanger group is cooled, and the normal-temperature high-pressure air from the high-pressure air reservoir is preheated by the regenerator during the expansion power generation process, and the waste heat of the exhaust gas after expansion is utilized.

Description

Extra-high temperature compressed air energy storage system and method Technical Field The invention relates to the technical field of thermal energy engineering, in particular to a compressed air energy storage system and method based on ultrahigh-temperature compressed heat storage and release. Background With the continuous rapid increase of the installed capacity of renewable energy sources, compressed Air Energy Storage (CAES) has been developed faster and has entered a large-scale demonstration and promotion stage as an important technological choice for large-scale, long-term energy storage. The technical route is mainly divided into medium temperature and high temperature according to the highest temperature reached in the compression process and the adopted heat storage medium. The outlet temperature of the compression process of the medium temperature technical route is generally not more than 200 ℃, and medium pressure water (or similar liquid medium) is generally adopted as a heat storage medium to store compression heat. The route technology is relatively simple, but is limited by the heat storage temperature, the system 'electricity-electricity' conversion efficiency is generally low, and the efficiency of the current demonstration project is about 65%. The high temperature technical route increases the temperature after compression to a level generally not exceeding 400 ℃ by improving the compression process or equipment, and adopts heat conduction oil or a combination scheme of ternary molten salt (usually potassium nitrate-sodium nitrite-sodium nitrate mixture) +medium-pressure water to store heat in different temperature areas. While efficiency is improved over the medium temperature route, limited to the highest temperature, the system "electricity-to-electricity" conversion efficiency is also often difficult to break through 70%. The system efficiency of the system is obviously lower than that of the pumped storage (the efficiency can reach 75% -85% generally) which is mature in technology, whether the system is a medium-temperature or high-temperature route. The lower conversion efficiency has become a major limiting factor in restricting the large-scale commercial development of compressed air energy storage technologies. The core reason for the lower efficiency is the lack of energy grade (i.e. temperature). According to the Carnot cycle principle, the higher heat storage temperature means that the higher initial temperature can be obtained in the expansion working stage, so that the power generation efficiency is remarkably improved. In addition, in order to cover the wide temperature area from normal temperature to the highest temperature for heat storage, the existing high-temperature route often needs to adopt various heat storage media and complex multi-set heat storage systems, and the complexity, the heat management difficulty and the initial investment cost of the system are increased. Therefore, developing a novel compressed air energy storage system that can break through the existing temperature limit, realize higher operating temperature (for example >500 ℃) and thus achieve subversion efficiency improvement, and simultaneously can simplify the heat storage system and control the cost becomes a technical problem to be solved in the art. The term "ultra-high temperature" as used herein refers to temperatures reached after air is compressed during compression >500 ℃, typically 570-600 ℃ which is significantly higher than the temperatures of conventional high temperature routes. Disclosure of Invention The invention aims to overcome the defects of the prior art and provide an ultrahigh-temperature compressed air energy storage system and an ultrahigh-temperature compressed air energy storage method which are high in system efficiency, high in energy storage density, simplified in heat storage system, high in integration level and remarkable in cost advantage. In order to achieve the above purpose, the invention adopts the following technical scheme: an ultra-high temperature compressed air energy storage system comprises a compressed energy storage subsystem and an expansion power generation subsystem which are operated alternately in time: The compression energy storage subsystem comprises a compressor unit for compressing air to high temperature and generating high-temperature compression heat, and a heat storage heat exchanger unit for storing the high-temperature compression heat in a heat storage medium in the compression process; The expansion power generation subsystem comprises an exothermic heat exchanger group and an expansion unit, wherein the exothermic heat exchanger group is used for extracting heat from the heat storage medium to heat air in the expansion process, and the expansion unit is used for expanding the heated air to do work; The heat regenerator is configured to preheat ambient air entering the system and cool the high-pressure air finally cooled by t