SCR外置烟道飞灰沉积特性与流场优化数值仿真  

Numerical Simulation of Fly Ash Deposition Characteristics and Flow Field Optimization for SCR External Flue

作　　者：李凯 章平衡[1] 孟志浩 曹允宁 徐尧 刘莉 李廉明 LI Kai;ZHANG Pingheng;MENG Zhihao;CAO Yunning;XU Yao;LIU Li;LI Lianming(Jiaxing New Jies Thermal Power Co.,Ltd.,Jiaxing 314016,Zhejiang Province,China;College of Energy Engineering,Zhejiang University,Hangzhou 310027,Zhejiang Province,China)

机构地区：[1]嘉兴新嘉爱斯热电有限公司,浙江省嘉兴市314016 [2]浙江大学能源工程学院,浙江省杭州市310027

出　　处：《发电技术》2025年第1期145-153,共9页Power Generation Technology

基　　金：浙江省科技计划项目(2021C03164)。

摘　　要：【目的】选择性催化还原(selectivecatalytic reduction,SCR)脱硝因脱硝效率高,运行可靠等优点,被广泛应用于锅炉烟气脱硝,然而高灰布置下脱硝烟气尚未进行除尘处理,烟气中的飞灰会使催化剂堵塞并对其产生磨损。为减轻飞灰颗粒对选择性催化还原催化剂的磨损与堵塞,设计并研究了SCR外置烟道对烟气中的飞灰颗粒进行捕集分离。【方法】基于仿真软件及其用户定义函数功能,开展了SCR外置烟道飞灰沉积特性与流场优化的数值仿真。【结果】烟气流速从1 m/s上升至2 m/s时,飞灰沉积率由24.0%下降至1.88%,随着流速的增大,飞灰沉积率快速下降;50μm以下飞灰颗粒难以被捕集,但随着飞灰粒径的增大,飞灰沉积率快速上升,飞灰被SCR外置烟道捕集,脱硝反应器入口流速分布极为不均;在流场分析的基础上,提出脱硝反应器入口流场优化方案,通过导流板的优化设计改善了流场分布,使脱硝反应器入口的速度不均匀系数从93.7%下降至14.7%。【结论】研究结果可为SCR外置烟道现场运行提供可靠的理论指导。[Objectives]Selective catalytic reduction(SCR)denitrification is widely used in denitrification of boiler flue gas due to its high denitrification efficiency and reliable operation.However,under high-ash arrangements,the denitrification flue gas has not yet been de-treated,and fly ash in the flue gas will block the catalyst and cause wear on it.In order to reduce the wear and clogging of fly ash particles on SCR catalysts,an SCR external flue is designed and studied to trap and separate fly ash particles in flue gas.[Methods]Based on simulation software and its user defined function,numerical simulation of fly ash deposition characteristics and flow field optimization for SCR external flue is carried out.[Results]When the flue gas flow rate increases from 1 to 2 m/s,the fly ash deposition rate decreases from 24.0%to 1.88%.Therefore,as the increase of flow rate,the fly ash deposition rate decreases rapidly.It is difficult to trap fly ash particles below 50μm.However,with the increase of the fly ash particle size,the fly ash deposition rate increases rapidly,and the fly ash is trapped by the SCR external flue.The flow velocity distribution at the inlet of the denitrification reactor is extremely uneven.Based on the flow field analysis,an optimization plan for the flow field at the inlet of the denitrification reactor is proposed.The flow field distribution is improved through the optimized design of the guide plate,and the velocity unevenness coefficient at the inlet of the denitrification reactor is reduced from 93.7%to 14.7%.[Conclusions]The research results may provide reliable theoretical guidance for the field operation of SCR external flue.

关 键 词：燃煤电厂 锅炉烟气 选择性催化还原(SCR) 飞灰沉积 流场优化 数值模拟 

分 类 号：TK223[动力工程及工程热物理—动力机械及工程]