Search

CN-122014374-A - Compressed air energy storage and coal-fired unit collaborative power generation system

CN122014374ACN 122014374 ACN122014374 ACN 122014374ACN-122014374-A

Abstract

The invention relates to a compressed air energy storage and coal-fired unit collaborative power generation system which comprises a coal-fired power generation system and a compressed air energy storage system coupled with the coal-fired power generation system, wherein in the energy storage process, condensed water of the coal-fired power generation system enters the compressed air energy storage system from a flow dividing valve to absorb compression heat and then returns to a unit from a mixing valve, in the energy release process, the extraction steam of a 5 th-stage turbine enters the compressed air energy storage system from the flow dividing valve to primarily heat high-pressure air, then returns to the unit from the mixing valve, the extraction steam of a 3 rd-stage turbine enters the compressed air energy storage system from the flow dividing valve to further heat the high-pressure air, and returns to the unit from the mixing valve, and meanwhile, the exhaust gas of an expander is recovered by adopting a waste heat recovery heat exchanger to preheat the high-pressure air. The invention obviously improves the operation flexibility and peak shaving capacity of the unit, has good engineering adaptability and economy, and is suitable for the scene of carrying out flexible modification on the coal-fired unit under the high-proportion renewable energy access background.

Inventors

  • LI YANGHAI
  • XU WANBING
  • ZHANG MING
  • HUANG HUI
  • ZHOU MIAO

Assignees

  • 国网湖北省电力有限公司电力科学研究院

Dates

Publication Date
20260512
Application Date
20260123

Claims (10)

  1. 1. The compressed air energy storage and coal-fired unit cooperative power generation system is characterized by comprising a coal-fired power generation system and a compressed air energy storage system coupled with the coal-fired power generation system; The coal-fired power generation system includes: the system comprises a boiler (1), a turbine high-pressure cylinder (2), a diverter valve (3), a turbine medium-pressure cylinder (4), a turbine low-pressure cylinder (5), a generator (6), a condenser (7), a condensate pump (8), a water supply pump (17) and matched heaters and valves; the compressed air energy storage system includes: Heat exchangers (30, 31, 32, 33), motors (34), compressors (35, 36, 37, 38), gas tanks (39), high temperature heat exchangers (50, 51, 52, 53), low temperature heat exchangers (57, 58, 59, 60), waste heat recovery heat exchangers (61), generators (62), expanders (63, 64, 65, 66), and associated valves; In the energy storage process, condensed water of the coal-fired power generation system enters the compressed air energy storage system from the flow dividing valve (9) to absorb compression heat and then returns to the unit from the mixing valve (17), in the energy release process, the 5 th stage turbine extraction steam enters the compressed air energy storage system from the flow dividing valve (14) to carry out preliminary heating on high-pressure air and then returns to the unit from the mixing valve (26), the 3 rd stage turbine extraction steam enters the compressed air energy storage system from the flow dividing valve (18) to carry out further heating on the high-pressure air, returns to the unit from the mixing valve (22), and meanwhile, the waste heat recovery heat exchanger (61) is adopted to recover the exhaust gas of the expander (63) to preheat the high-pressure air.
  2. 2. The system of claim 1, wherein the source of electrical energy for the compressor (34) is off-grid power generated by the coal-fired power generation system during deep peak shaving.
  3. 3. The system of claim 1, wherein the turbine extraction is staged according to energy cascade utilization principles, including low pressure cylinder 5 th stage extraction and medium pressure cylinder 3 rd stage extraction for primary and secondary heating of compressed air, respectively.
  4. 4. The system according to claim 1, characterized in that the heat recovery heat exchanger (61) is used for recovering the remaining heat in the expander exhaust gas and for heating the throttled depressurized high pressure air to achieve preheating of the compressed air and to increase the system thermal efficiency.
  5. 5. The system according to claim 1, characterized in that the compressors (35, 36, 37, 38) in the compressed air energy storage system are arranged in series in a plurality of stages, between which intermediate cooling heat exchangers (30, 31, 32, 33) are arranged for reducing the air temperature in stages and reducing the compression power consumption.
  6. 6. The system according to claim 1, wherein the condensed water in the energy storage stage enters an intermediate heat exchanger in the compressed air energy storage system through a flow dividing valve (9), and after the compressed heat is absorbed, the condensed water flows back to the coal-fired power generation system through a mixing valve (17), so that the heat energy recovery utilization rate is improved.
  7. 7. The system according to claim 1, characterized in that the said expander (63, 64, 65, 66) adopts a multistage series structure in the energy release stage, adapting to compressed air of different pressure levels, realizing efficient staged expansion and driving the generator (62) to output electric power.
  8. 8. The system of claim 1, wherein the energy storage and release process is flexibly switched by arranging a plurality of groups of valves and shunt pipelines, and air compression and expansion paths can be adjusted according to actual load of a coal-fired unit and power grid requirements, so that dynamic conversion and efficient peak shaving of the running state of the system are realized.
  9. 9. The system according to claim 1, wherein the high temperature heat exchangers (50, 51, 52, 53) and the low temperature heat exchangers (57, 58, 59, 60) are configured to compress air temperature rise demand distribution, and the air is heated in multiple stages by steam turbine extraction and expander exhaust waste heat, so as to improve heat-power conversion efficiency.
  10. 10. The system of claim 1, wherein the minimum thermal load of the boiler is maintained stable during peak shaving operation, and the output power is regulated by energy storage and release of the compressed air energy storage system, thereby breaking through the minimum operational load limit of the boiler and enhancing the peak shaving depth and flexibility of the system.

Description

Compressed air energy storage and coal-fired unit collaborative power generation system Technical Field The invention belongs to the technical field of compressed air energy storage, and particularly relates to a collaborative power generation system for improving peak shaving capacity by efficient thermal coupling of compressed air energy storage and a coal-fired unit. Background In recent years, development of renewable energy sources has been significantly advanced, but volatility and unpredictability thereof are still main challenges facing current technical development, so that not only is the utilization efficiency of renewable energy sources reduced, but also safe and stable operation of a power grid may be affected, and the reliability of the whole power system is threatened. In order to adapt to new changes brought by renewable energy grid connection, maintain real-time balance of power grid power, ensure safety and stability of a power system, and urgent needs to be regulated by flexible and efficient means. The coal-fired generator set is taken as a main power source of China, accounts for more than half of the total power generation amount of China, and plays a key role in peak regulation and frequency modulation of a power grid. When the renewable energy power generation output is higher, the coal-fired unit needs to deeply participate in peak shaving to cope with power grid fluctuation, power supply stability is guaranteed, and meanwhile stability of operation parameters and safety of equipment are required to be maintained in the frequent load-changing operation process. However, coal-fired units face multiple challenges under deep peak-shaving conditions, including problems of reduced economy, increased pollutant emissions, reduced number of hours of utilization, frequent unit accelerated wear due to power adjustment, and severe unit power generation efficiency degradation caused by long-term off-design operation. Therefore, under the background that the renewable energy power generation duty ratio is continuously increased, the flexible transformation of the existing coal-fired power station is quickened, the peak regulation and frequency modulation capacity of the existing coal-fired power station is improved, and the method becomes a key measure for guaranteeing the stable operation of a power system. The energy storage system can adjust power output when the power supply and demand are not matched, balance the supply and demand requirements of an energy producer and an energy consumer, and effectively solve the impact of renewable energy grid connection on a power grid. The additional energy storage system is added on the basis of the coal-fired unit, so that the energy storage system is an effective means for improving the operation flexibility of the unit. In the energy storage system, the compressed air energy storage technology has the advantages of large scale, low cost, long service life, high operation flexibility and the like, has huge application potential in renewable energy grid connection and peak regulation of an electric power system, and receives wide attention. And the working temperature range of the medium-low temperature compressed air energy storage system is 100-400 ℃, and the medium-low temperature compressed air energy storage system is matched with the working medium temperature of the water supply side and the steam extraction side in the heat recovery system of the coal-fired unit, so that the medium-low temperature compressed air energy storage system has larger coupling potential. The compressed air energy storage system with higher operation flexibility is deeply coupled with the coal-fired unit with stable power generation and limited regulation capacity, so that the operation domain of the coal-fired unit can be effectively widened, the response speed of the unit to load change is accelerated, the flexibility and peak regulation capacity of the unit operation are improved, and the low-load operation time of the coal-fired unit in the peak regulation process is reduced. Meanwhile, by reasonably designing the coupling structure, the efficient transfer and comprehensive utilization of heat can be realized, the overall energy efficiency of the system can be improved, and the investment cost of equipment such as a heat storage tank in the compressed air energy storage system can be effectively reduced, so that the collaborative optimization of the technical performance and the economic benefit is realized. Disclosure of Invention Aiming at the improvement requirement that the existing coal-fired power generation system has insufficient regulation capability in the deep peak regulation process, a coupling system optimization scheme integrating a compressed air energy storage technology and a coal-fired power generation unit is provided, and aims to remarkably improve the peak regulation capability and the operation flexibility of the unit. In the energy storage s