基于压缩空气储能的燃煤发电系统性能分析

Performance analysis on a compressed air storage system deeply coupled with coal-fired unit

  • 摘要: 为提升传统燃煤机组运行灵活性,提出一种将绝热压缩空气储能系统与600 MW燃煤机组深度耦合的新型发电系统,通过能量梯级利用实现系统效率提升。建立“冷凝水冷却+抽汽加热”的双向耦合机制:储能阶段采用机组冷凝水冷却压缩空气;释能阶段利用低压汽轮机五号低加前抽汽加热压缩空气,并通过换热回水与回热系统匹配实现能量回收。采用Ebsilon平台构建基于压缩空气储能的新型燃煤发电系统分析模型,提出在不同阶段的多种耦合方案设计,并重点考察储罐压力、入口流量等参数对热耗率、循环效率及㶲损失的影响。研究结果表明:通过压缩空气储能系统与燃煤机组耦合,储罐压力增加时,耦合系统的热耗率逐渐增大,系统循环效率和能量利用系数先增大后减小,系统在10 MPa储罐压力时达最佳性能,循环效率50.66%、能量利用系数47.86%。随着入口空气流量的升高,能量利用系数和热耗率降低,系统循环效率升高。㶲分析是体现系统损耗最直接的方法,在机组额定工况下㶲效率77.39%,最大㶲损失位于节流阀,占比5.69%。负荷降低时系统热耗率增加11%,循环效率下降3.2%,能量利用系数降低6%。不仅优化了压缩空气系统的蓄热和蓄冷装置,实现机组调峰能力提升与投资成本降低的双重效益,还为传统煤电灵活性改造提供了新型技术路径,降低了机组耦合系统的投资成本,并提高了燃煤机组效益。

     

    Abstract: To enhance the operational flexibility of conventional coal-fired units, a novel power generation system that deeply couples adiabatic compressed air energy storage (AA-CAES) with a 600 MW coal-fired unit is proposed, achieving system efficiency improvement through cascade energy utilization. A bidirectional coupling mechanism of “condensate cooling + extraction steam heating” is established: during the energy storage phase, unit condensate is utilized to cool the compressed air; during the energy release phase, extraction steam from the fifth low-pressure heater of the steam turbine is employed to heat the stored compressed air, and energy recovery is realized by matching the heat-exchanged return water with the regenerative system. An analysis model for a new coal-fired power generation system based on compressed air energy storage is constructed based on Ebsilon software, focusing on the effects of storage tank pressure, inlet flow rate, and other parameters on heat rate, cycle efficiency, and exergy loss. The research results indicate that with the integration of the compressed air energy storage system and the coal-fired unit, as the storage tank pressure increases, the heat rate of the coupled system gradually rises, while the system cycle efficiency and energy utilization coefficient initially increase and then decrease, reaching optimal performance at a storage tank pressure of 10 MPa with a cycle efficiency of 50.66% and an energy utilization coefficient of 47.86%. As the inlet air flow rate of the compressor increases, the energy utilization coefficient and heat rate decrease, whereas the system cycle efficiency increases. Analysis is the most direct method to reflect system losses. Under rated conditions, the exergy efficiency is 77.39%, with the maximum exergy loss occurring at the throttle valve, accounting for 5.69%. When the load decreases, the system heat rate increases by 11%, the cycle efficiency decreases by 3.2%, and the energy utilization coefficient drops by 6%. The thermal and cold storage devices of the compressed air system are optimized, achieving dual benefits of enhanced unit peak-shaving capability and reduced investment costs. A new technical pathway is provided for the flexibility retrofitting of traditional coal-fired power, effectively lowering the investment cost of the coupled system and improving the economic performance of coal-fired units.

     

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