储能科学与技术 ›› 2023, Vol. 12 ›› Issue (12): 3605-3615.doi: 10.19799/j.cnki.2095-4239.2023.0547

• 复合储热专辑 • 上一篇    下一篇

面向火电厂改造的熔盐卡诺电池储能系统仿真研究

韩瑞(), 廖志荣, 于博旭, 徐超(), 巨星   

  1. 华北电力大学能源动力与机械工程学院,北京 102206
  • 收稿日期:2023-08-18 修回日期:2023-09-07 出版日期:2023-12-05 发布日期:2023-12-09
  • 通讯作者: 徐超 E-mail:15931389164@163.com;mechxu@ncepu.edu.cn
  • 作者简介:韩瑞(1999—),女,硕士研究生,主要研究方向为热泵储热,E-mail:15931389164@163.com
  • 基金资助:
    国家自然科学基金项目(51821004);华北电力大学学科交叉创新专项项目

Simulation study of a molten-salt Carnot battery energy storage system for retrofitting a thermal power plant

Rui HAN(), Zhirong LIAO, Boxu YU, Chao XU(), Xing JU   

  1. School of Energy, Power and Mechanical Engineering, North China Electric Power University, Beijing 102206, China
  • Received:2023-08-18 Revised:2023-09-07 Online:2023-12-05 Published:2023-12-09
  • Contact: Chao XU E-mail:15931389164@163.com;mechxu@ncepu.edu.cn

摘要:

熔盐卡诺电池储能系统将火电厂与储能技术耦合,是实现机组灵活改造的有效途径。该系统可采用新能源场站弃电或者电网低谷电直接或者通过热泵循环间接加热熔盐,将电能转化为高温热能存储,而后高温熔盐和锅炉共同作为热源来驱动汽轮机发电,从而达到减少煤炭使用甚至替代锅炉的目的。为探究部件参数变化对火电厂改造的熔盐卡诺电池储能系统的效率影响规律,本工作首先在Aspen Plus平台中搭建了热泵循环、熔盐蒸发器以及典型600 MW亚临界燃煤机组等模块构成的熔盐卡诺电池储能系统热力学模型。其次,分析了热泵的循环工质、有/无回热以及部件关键参数对热泵制热效率及系统储能特性的影响规律。最后,比较了直接电加热和利用热泵循环加热熔盐的两种不同电转热形式的储能系统变工况效率。研究结果表明,有回热系统的热泵制热系数和储能系统往返效率均高于无回热系统;对于有回热系统,氩气作为热泵循环工质的回热器热负荷最低,然而氮气作为热泵循环工质时,储能系统的往返效率最高。在冷源温度67 ℃、等熵效率0.9和机械效率1.0时,储能系统额定工况的往返效率可达61.46%。此外,在额定工况下,采用热泵的储能系统相比于直接电加热的系统往返效率提高了45.16%。本研究可为火电厂改造的熔盐卡诺电池储能系统的设计和分析提供理论指导。

关键词: 卡诺电池, 火电厂改造, 系统效率, 熔盐储热, 数值模拟

Abstract:

Coupling a thermal power plant and its thermal energy storage through a molten-salt Carnot battery energy storage system is an effective retrofit method. The energy storage system uses the abandoned electric or the power to heat molten salt directly or indirectly through the heat-pump cycle, converting electrical energy into high-temperature thermal energy storage. The high-temperature molten salt and the boiler are subsequently used together as a heat source to drive the steam engine to generate electricity, which achieves the purpose of reducing or replacing the boiler. In this report, the pattern of component parameters influencing the efficiency of a molten-salt Carnot battery energy storage system used in retrofitting a thermal power plant is explored. A thermodynamic model of the molten-salt Carnot battery energy storage system is constructed using the Aspen Plus platform; the model consists of a heat-pump cycle, a molten-salt evaporator, and a typical 600 MW subcritical power block. Influence of the cycling medium, regenerative/nonregenerative properties, and component key parameters on the performance of heat pump and overall system are analyzed. The system efficiencies for the system using electric heating and heat-pump heating are compared under variable operating conditions. The results show that the regenerative storage system has a higher coefficient of heat-pump production and higher round-trip efficiency than that for the nonregenerative system. The regenerative storage system requires the lowest return heater heat by using argon as the heat-pump circulating medium and can achieve the highest round-trip efficiency by using helium as the heat-pump circulating medium. When the cold-source temperature is 67 ℃, isentropic efficiency is 0.9, and mechanical efficiency is 1.0, the round-trip efficiency under the rated working condition can reach 61.46%. In addition, the round-trip efficiency at rated operating conditions of the storage system with the heat pump is 45.16% higher than electric heating. These findings can help in the further design and analysis of molten-salt Carnot battery energy storage systems for retrofitting thermal power plants.

Key words: Carnot battery, coal power plant renovation, system efficiency, molten salt thermal storage, numerical simulation

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