空间受限下SCR宽负荷脱硝高温旁路烟道优化设计  

Optimal design of high temperature bypass flue for wide-load SCR-DeNO_(x)device under limited space

作　　者：张楚城 叶兴联 刘栋栋 苏寅彪 杨丁 罗坤[1] ZHANG Chucheng;YE Xinglian;LIU Dongdong;SU Yinbiao;YANG Ding;LUO Kun(College of Energy Engineering,Zhejiang University,Hangzhou 310027,China;Fujian Longking Co.,Ltd.,Longyan 364000,China)

机构地区：[1]浙江大学能源工程学院,浙江杭州310027 [2]福建龙净环保股份有限公司,福建龙岩364000

出　　处：《洁净煤技术》2022年第7期149-156,共8页Clean Coal Technology

基　　金：国家重点研发计划资助项目(2016YFC0203703)。

摘　　要：随着我国能源结构的转型升级,燃煤电站长时间在中低负荷区间运行,暴露出低负荷下脱硝入口烟温达不到催化剂运行要求的问题,而烟气旁路改造是提高烟温的灵活高效方法。以某600 MW机组宽负荷脱硝烟气旁路改造工程为例,采用数值模拟方法,论述了施工空间受限下的旁路烟道设计难点和流场问题,针对性地提出了优化设计思路。结果表明,经分析得出空间受限条件造成的难点主要有主、旁路烟气之间的混合距离短以及不利于提高氨氮物质的量比的分布均匀性。优化设计后,大幅改善了SCR脱硝系统内部的流场分布均匀性,使得旁路投运与否均满足相关流场技术指标。尤其旁路投运时,首层催化剂入口的氨氮物质的量比分布相对标准偏差由初始方案的20.5%降至3.7%、温度偏差由初始方案的-21.6~51.5℃减小为-13.8~9.5℃。将主路烟道分隔出一部分作为旁路烟道、采取小通道加引流板的回烟口形式、将喷氨混合装置布置于旁路回烟口下游等一系列措施能显著改善流场分布均匀性,对宽负荷脱硝改造工程具有重要借鉴。With the transformation and upgrading of China′s energy structure,more and more coal-fired power plants have been operating in the medium-low load range for a long time,which exposes the problem that the inlet flue gas temperature of SCR-DeNO_(x)can not meet catalyst requirement at low-load operation.And the flue gas bypass modification is a flexible and efficient method to improve the gas temperature.Taking the wide load denitrification gas bypass reconstruction project of a 600 MW unit as an example,the design difficulties and flow field problems of bypass flue under limited construction space were discussed by using the numerical simulation method,and a kind of optimal design ideas were put forward.The results show that:After program analysis,the main difficulties caused by space limitation mainly include two aspects:short mixing distance between main flue gas and by-pass flue gas,and the unfavorable uniformity of NH_(3)/NO_(x)distribution.After program optimization,the flow field distribution in the SCR denitration system is greatly improved,and the relevant flow field technical indexes can be satisfied whether the bypass flue is put into operation or not.Especially when the bypass flue is put into operation,the relative standard deviation of NH_(3)/NO_(x)distribution at inlet of the 1st layer catalyst is decreased from 20.5%under initial plan to 3.7%,and the temperature deviation is reduced from-21.6-51.5℃under initial plan to-13.8-9.5℃.A series of measures such as separating a part of the main flue as the bypass flue,adopting the form of smoke return with small passage and guide plate,and placing the AIG and mixer downstream of the bypass smoke return can significantly improve the flow field distribution uniformity,which is an important reference significance to wide-load SCR-DeNO_(x)project.

关 键 词：SCR脱硝 烟气旁路改造 低负荷运行 温度偏差 流场优化 

分 类 号：X701[环境科学与工程—环境工程]