摘要
为改善间接空冷机组冷端运行特性以实现机组提质增效,该文提出一种新型间接空冷系统,将充满RT35HC材料的相变储热罐与空冷塔及凝汽器串联,实现机组乏汽废热排放的“移峰填谷”。以某600MW超临界间接空冷机组为例,分别建立汽水循环和新型间接空冷系统热力学模型并进行耦合迭代计算,分析机组变工况热力特性并开展热经济性评价。结果表明:将相变储热罐串接在空冷塔下游是一种高效的集成方式,能在高温高负荷下吸收机组乏汽部分废热以减轻空冷塔冷却压力,并在低温低负荷下借助空冷塔将存储的废热排放到环境中。考虑储热罐放热2.5h及匹配蓄热1.05h一个周期,储热罐配置253MW·h热容量对应布置5996m2换热面积可使机组在一个周期内节省标煤近5t,标准煤耗率折算下降3.60g/(k W·h),机组背压变动也缩小近7kPa。算例分析证实了冷端配置储热罐可以很好地提升间接空冷机组的运行经济性,还可减缓机组冷端参数大范围波动。
In order to promote operation characteristics of the cold end of an indirect air-cooled power generating unit and achieve both quality and efficiency improvements for the unit,a novel indirect air-cooled system is proposed in this paper.A phase-change heat storage tank filled with material RT35HC is connected in series with the dry cooling tower and the condenser to realize the“peak-shifting and valley-filling”of waste heat emission of the unit.Taking a 600MW supercritical indirect air-cooled unit as an example,thermodynamic models of the steam-water cycle and the novel indirect air-cooled system are separately established and then coupled for iterative computations,allowing thermal characteristics of the unit to be analyzed and thermo-economic evaluations to be performed under various operating conditions.The results show that it is a reliable integration method of connecting the phase-change heat storage tank in series downstream of the dry cooling tower.In this way,part of waste heat of the unit can be absorbed by the tank to relieve cooling pressure on the dry cooling tower under high ambient temperature and high unit load,and the stored heat can be discharged through the dry cooling tower to the environment under low ambient temperature and low unit load.Considering a complete cycle of 2.5h heat release and 1.05h heat storage,a heat capacity of 253MW·h for the tank requires a heat exchange area of 5996m2.With this configuration,the unit saves roughly 5t of standard coal during one complete cycle,which translates to a reduction in standard coal consumption rate of 3.60g/(kW·h).Besides,the fluctuation in unit backpressure is diminished by 7kPa.The case study confirms that the integration of heat storage tank to the cold end of an indirect air-cooled unit is beneficial to operating economy of the unit,and it helps to reduce the wide fluctuations of thermal parameters as well.
作者
马欢
王柏公
蔡亮
司风琪
MA Huan;WANG Baigong;CAI Liang;SI Fengqi(School of Energy and Environment,Southeast University,Nanjing 210096,Jiangsu Province,China)
出处
《中国电机工程学报》
EI
CSCD
北大核心
2023年第24期9616-9628,共13页
Proceedings of the CSEE
基金
国家自然科学基金项目(52206007,51976031)
中央高校基本科研业务费专项资金项目(2242021R20019)。
关键词
间接空冷机组
储热罐
热力特性
变工况
热经济性评价
indirect air-cooled power generating unit
heat storage tank
thermodynamic characteristic
variable operating condition
thermo-economic evaluation
