摘要
随着对水资源日益匮乏,以及对直流和蒸发冷却方式引起的环境问题的持续关注,电站空冷技术获得了快速发展。无论直接还是间接空冷系统,翅片管束换热器都是构成空冷系统的主要设备。翅片管束结构形式不同导致的流动传热性能差异是造成空冷系统热力性能优劣的主要因素。现有直接空冷系统采用机械通风强迫对流方式实现冷却空气和汽轮机排汽的热量交换,因此轴流风机气动特性和由数十台风机集群运行产生的集群效应将会显著影响直接空冷系统热力性能。电站间冷系统一般采用自然通风冷却塔,通过冷却塔内外空气密度差产生的浮升力驱动环境空气流经空冷散热器实现热量交换。冷却塔结构形式,以及空冷散热器在冷却塔内外的布局方式是决定间冷系统热力性能的关键因素。由于直接或间接以环境空气作为电站冷端的冷却介质,因此自然环境条件成为影响电站空冷系统运行性能的主要原因之一。本文将对国内外电站空冷技术的研究动态和最新进展进行综述和评论,并预测电站空冷技术的未来发展趋势和应用前景。
An increasing focus on water conservation com- bined with continuing concern on the environmental effects of both once-through and evaporative cooling has resulted in increasing popularity of dry cooling technology. Finned tube heat exchanger is one of the main equipments for either di- rect or indirect dry cooling system. The flow and heat trans- fer characteristics of the finned tube bundles in various geo- metric forms are the key issues to the thermo-hydraulic per- formances of dry cooling system. The forced convection heat transfer is commonly taken to realize the heat rejection from the exhaust steam of turbine to the cooling air for thepresent direct dry cooling system, so the aerodynamic be- havior of the axial flow fan and the cluster effect due to the array of tens of axial flow fans will impose conspicuous im- pacts on the performance of direct dry cooling system. For the indirect dry cooling system, the ambient air is driven to flow through the air-cooled heat exchanger by means of the buoyancy force due to the air density difference between the outside and inside of the natural draught dry-cooling tower, removing the heat rejection from the circulating water. The thermo-hydraulic performances of indirect dry cooling sys- tem are mainly dependent upon the structure of dry-cooling tower, and the air-cooled heat exchanger layout of either horizontal location at the inlet cross section of the tower or vertical arrangement around the circumference at the base of the tower. The ambient air is employed directly or indi- rectly as the coding medium of the exhaust steam, so the ambient condition becomes one of the key issues for the per- formance of dry cooling system in power plants. In this work, the state-of-the-art in dry cooling technologies of power plants will be reviewed and assessed, and the future development trends and application is forecasted.
出处
《现代电力》
北大核心
2013年第3期69-79,共11页
Modern Electric Power
基金
国家重点基础研究发展计划(973计划)项目(2009CB219804)
国家科技支撑计划项目(2011BAA04B02)
关键词
直接空冷系统
间接空冷系统
空冷凝汽器
轴流风机
空冷散热器
空冷塔
翅片管束
环境条件
direct dry cooling system
indirect dry coolingsystem
air-cooled condenser
axial flow fan~ air-cooledheat exchanger
dry-cooling tower
finned tube bundle
am-bient condition
