直接空冷系统技术改进及能效提升研究  

Research on Technical Improvement and Energy-Saving Elevating of Direct Air-Cooling System

作　　者：孙玉庆 张新海 柴艳琴 李书芳 SUN Yuqing;ZHANG Xinhai;CHAI Yanqin;LI Shufang(Shanxi Electric Power Engineering Co.,Ltd.,China Energy Engineering Group,Taiyuan 030001,China)

机构地区：[1]中国能源建设集团山西省电力勘测设计院有限公司,太原030001

出　　处：《电力学报》2023年第2期146-155,共10页Journal of Electric Power

基　　金：中国能源建设集团规划设计有限公司科技项目(对空冷风机单元型式及流态特性改善的研究及应用,GSKJ2-S04-2021)。

摘　　要：为实现火电厂“提效-节能降耗”目标,解决常规直接空气冷风系统换热效率低、运行背压高等问题,通过对其排汽管道系统、散热器管束型式及风机组布置方式进行技术改进和能效提升研究,提出了一种新型直接空冷系统布置方案。新方案采用风机低位布置双“A”型散热器空冷布置型式,通过结构应力计算和流场数值模拟,相比常规的空冷系统,可得以下结论:(1)在满足系统结构安全性的前提下,新型排汽管道布置方式的出口至蒸汽分配管入口总阻力压降减少约400 Pa,排汽管道内流量分配更均匀;(2)双小A型散热器管束布置,可缩短管束长度约一半,加快蒸汽冷却,减少不凝结气体的堆积,防冻性能更好;(3)在冷却三角布置标高不变的条件下,将风机下移至钢桁架底部,使风机出口至冷却三角底部之间存在一定空间可对新空气起“导流、梳理”作用,在散热器出口面,同样形成风速带,沿高度方向增大,蒸汽分配管附近高速区域进一步增大,冷却单元的换热效果将进一步得到增强,散热器出口风速优于常规布置,进而使进入冷却三角的空气流动状态稳定,提高冷却三角散热效率。经过某电厂现场应用,其空冷机组夏季运行背压降低约2 kPa,全年平均运行背压降低约0.8 kPa,煤耗减少约1 g/(kW·h),单台机组每年可为电厂节省煤炭费用约276万元(标煤价1 000元/t)。该方案在降低机组背压的同时,可减少膨胀节组合数量、钢结构重量等,也降低了空气侧风阻,缓解了空冷凝汽器的防冻问题。因此,所提方案既可降低设备的一次性投资,又具有在运行费用方面(节省煤耗)的明显优势,可实现电煤的清洁和高效利用,取得良好的社会效益,具有很大的推广价值和广泛的应用前景。In order to achieve the goal of efficiency improvement-energy saving and consumption reduction in thermal power plants and solve the problems of low heat exchange efficiency and high operating back pressure of conventional direct air cooling system,a new type of direct air cooling system layout scheme is proposed by studying the technical improvement and energy efficiency improvement of its exhaust pipe system,radiator tube bundle type and wind turbine layout.The new scheme adopts the air cooling arrangement of double“A”type radiator with low fan arrangement.Through structural stress calculation and flow field numerical simulation,com⁃pared with the conventional air cooling system,the following conclusions can be drawn:(1)Under the premise of meeting the safety of the system structure,the total resistance pressure drop from the outlet of the new ex⁃haust pipe arrangement to the inlet of the steam distribution pipe is reduced by about 400 Pa,and the flow distri⁃bution in the exhaust pipe is more uniform.(2)The arrangement of double small A-type radiator tube bundle can shorten the length of tube bundle by about half,accelerate steam cooling,reduce the accumulation of non-condensable gas,and have better antifreeze performance.(3)Under the condition of the same elevation of the cooling triangle arrangement,the fan is moved down to the bottom of the steel truss,so that there is a certain space between the fan outlet and the bottom of the cooling triangle to guide and comb the new air.On the outlet surface of the radiator,the wind speed zone is also formed,which increases along the height direction,and the high-speed area near the steam distribution tube is further increased.The heat transfer effect of the cooling unit will be further enhanced,and the outlet speed of the radiator is better than that of the conventional arrangement,so that the air flow state entering the cooling triangle is stable and the heat dissipation efficiency of the cooling tri⁃angle is improved.Through the field application of a pow

关 键 词：火电机组 直接空冷系统 排汽管道多列布置 散热器双A布置 风机组低位布置 技术改造 能效提升 

分 类 号：TK26[动力工程及工程热物理—动力机械及工程] TM621[电气工程—电力系统及自动化]