回转式空气预热器积灰防治改造方案研究  

Study on retrofit solutions for fouling prevention of rotary air preheater

作　　者：王超 高荣泽 王利民 孙浩家 王研凯[1] 李迎春[1] 车得福[2] WANG Chao;GAO Rongze;WANG Limin;SUN Haojia;WANG Yankai;LI Yingchun;CHE Defu(Inner Mongolia Power Research Institute Co.,Ltd.,Hohhot 010010,China;School of Energy&Power Engineering,Xi’an Jiaotong University,Xi’an 710049,China)

机构地区：[1]内蒙古电力科学研究院有限责任公司,内蒙古呼和浩特010010 [2]西安交通大学能源与动力工程学院,陕西西安710049

出　　处：《热力发电》2022年第7期139-148,共10页Thermal Power Generation

基　　金：内蒙古电力科学研究院科技项目(ZC-2020-11)。

摘　　要：回转式空气预热器(空预器)是锅炉系统中重要的换热器之一,该设备中主要发生尾部烟气与一次、二次风之间的换热,从而有效利用烟气中的余热。由于空预器出口附近温度较低,该段经常发生较为严重的积灰与腐蚀,其原因与硫酸氢铵(ABS)的生成密不可分。上游的选择性催化还原(SCR)脱硝设备存在氨逃逸现象,过量的氨与硫氧化物、水在空预器冷端出口附近易生成ABS。目前有4种解决方案,包括安装暖风器(方案1)、热风再循环(方案2)、空气循环风防堵(方案3)及烟气顺流分切防堵(方案4)技术。总结了4种解决方案的优劣,并使用有限差分法量化比较了不同方案,为空预器积灰防治改造提供指导,拓宽了本领域研究的视角。结果表明:方案1中随目标温度的提升,危险区比例下降且冷端壁温提升,但排烟温度会上升;方案2中冷端壁温提升,但危险区比例增大,不利于积灰防治;方案3、4均可有效改善积灰结垢且降低排烟温度,但改造参数对改造效果有较大影响。后2种方案投资成本较高,在条件允许的情况下应优先选择,同时方案4在治理漏风方面的效果更佳。Rotary air preheater is a crucial heat exchanger in boiler system and its main function is to provide a place for heat transfer between hot flue gas and cold primary/secondary air,thus to realize efficient utilization of waste heat in flue gas.Due to relatively low temperature adjacent to the exit of air preheater,serious ash deposition and corrosion usually happens here,which is related to formation of ammonium bisulfate(ABS).Ammonia escapes from the upstream selective catalytic reduction(SCR)device,the excessive ammonia reacts with sulfur oxides and water at outlet of cold end of the air preheater,which is easy to generate ABS.To solve this problem,there are four solutions:installing air heaters(Scheme 1),using hot air recirculation technology(Scheme 2),using air-circulating blocking prevention technology(Scheme 3),and using flue gas downstream cutting blocking prevention technology(Scheme 4).This study summarizes the four solutions,and compares them with the finite difference calculation method to provide guidance for the fouling prevention retrofit.The results show that,with the increase of the target temperature in Scheme 1,the alert ratio decreases and the cold end wall temperature increases,but the exhaust gas temperature increases.In Scheme 2,the wall temperature increases,but the alert ratio increases much,which is not conducive to the fouling control.Both Scheme 3 and Scheme 4 can effectively improve the fouling and reduce the exhaust gas temperature,but the retrofit parameters cast a great influence on the effect.The latter two options cost more investment but should be preferred when conditions permit.Meanwhile,the Scheme 4 is more effective in controlling air leakage.

关 键 词：回转式空气预热器 积灰防治 改造 暖风器 热风再循环 

分 类 号：TK16[动力工程及工程热物理—热能工程]