摘要
锅炉在低负荷下稳燃性能不足是制约燃煤机组运行灵活性的重要原因,提升煤粉气流初始温度可以直接降低煤粉气流着火热,有效改善锅炉低负荷稳燃性能。对某600 MW等级燃煤机组的仿真计算表明,煤粉气流初始温度提升100℃,锅炉最低稳燃负荷下降约7%额定负荷。采用直吹式制粉系统的燃煤机组,受制于磨煤机安全运行要求,煤粉气流初始温度普遍偏低,存在80℃左右的提升空间。现有的煤粉气流加热方式包括热风混合加热、炉烟混合加热、高温蒸汽加热等。热风混合加热可以将煤粉气流温度提升至200℃左右,但煤粉浓度明显下降,煤粉气流着火热反而有所增加,必须结合煤粉气流浓淡分离技术才能实现锅炉稳燃能力的提升,且热风的混入会引起NO_(x)生成量上升;炉烟混合加热可以将煤粉气流温度提升至200~300℃且通过烟气再循环减少NO_(x)生成,但炉烟的混入降低了煤粉气流中煤粉浓度和氧气含量,对煤粉气流着火不利,同时高温炉烟风机成本高、维护困难;高温蒸汽加热在提升煤粉气流温度的同时实现了机组能量梯级利用,但低压蒸汽加热效果较差,高压蒸汽加热时会产生压力容器管理困难;现有的煤粉气流加热方式均存在一定不足而未能广泛应用。在总结现有技术不足的基础上,提出一种新型的煤粉气流加热系统,该系统采用汽轮机抽汽为热源,采用可以在常压下实现高效换热的导热油为中间换热介质,在磨煤机后的粉管上安装板翅式风粉加热器对煤粉气流进行加热。该煤粉气流加热系统在2个燃煤机组上进行了示范应用,实践证明该系统可以实现60~80℃的煤粉气流温升,将煤粉气流温度由80℃提升至140~160℃。
The insufficient combustion stability of boilers at low loads is an important reason that limits the flexible operation of coal-fired power units.Increasing the initial temperature of the pulverized coal stream can directly reduce the ignition heat of the pulverized coal stream,which can improve the combustion stability of boilers at low loads.The simulation calculations of a 600 MW coal-fired power unit show that the minimum stable combustion load of the boiler can reduce by about 7%while the initial temperature of pulverized coal stream increases by 100℃.Subjected to the requirements of the safe operation of the mill,the initial temperature of the pulverized coal stream is generally low for the coal-fired power unit using the direct blowing pulverizing system.The existing methods for increasing the temperature of pulverized coal stream include hot air mixing,furnace flue gas mixing,and steam heating.With hot air mixing,the temperature of the pulverized coal stream can be increased to about 200℃,but the concentration of pulverized coal decreases significantly,and the ignition heat of the pulverized coal stream increases.The shade separation of pulverized coal stream is necessary for combustion stability of boilers.The NO_(x) concentration increases with hot air mixing.With furnace flue gas mixing,the temperature of the pulverized coal stream can be increased to 200–300℃and the NO_(x) concentration decreases.But the concentrations of pulverized coal and O_(2) decrease significantly,the cost of high-temperature furnace flue fans is high and the maintenance of high-temperature furnace flue fans is difficult.With steam heating,the temperature of pulverized coal stream increases and the energy efficiency increases.However,the heating effect of low-pressure steam is poor,and it is difficult to manage pressure vessels when high-pressure steam is used.The existing pulverized coal stream heating methods have certain deficiencies and have not been widely used.A novel system for pulverized coal stream heating is proposed,turbine extraction steam is used as the heat source,thermal oil is used as the intermediate heat exchange medium,plate-fin heaters on the pipe are used to heat the pulverized coal stream.By practical application on two coal-fired power units,it is proved that the system can increase the temperature of pulverized coal stream by 60-80℃which increases from 80℃to 140–160℃.
作者
张平安
孟晓超
李源
周伟
宗飞飞
刘剑
沈国清
ZHANG Ping’an;MENG Xiaochao;LI Yuan;ZHOU Wei;ZONG Feifei;LIU Jian;SHEN Guoqing(Rundian Energy Science and Technology Co.,Ltd.,Zhengzhou 450018,China;Huaneng Qinbei Power Generation Co.Ltd.,Jiyuan 459012,China;China Resources Power Dengfeng Co.,Ltd.,Zhengzhou 452470,China;China Resources Power Jiaozuo Co.,Ltd.,Jiaozuo 454150,China;School of Energy Power and Mechanical Engineering,North China Electric Power University,Beijing 102206,China)
出处
《洁净煤技术》
北大核心
2025年第S1期196-202,共7页
Clean Coal Technology
基金
华润电力控股有限公司科研资助项目(CRPSR2019016)
中国华能集团有限公司科技资助项目(HNKJ21-HF190)
关键词
燃煤机组
煤粉气流
着火热
高温蒸汽
导热油
coal-fired power unit
pulverized coal stream
ignition heat
turbine extraction steam
thermal oil
作者简介
张平安(1986—),男,河南新乡人,高级工程师,博士。E-mail:safezhanghust@126.com。
