洁净煤技术

2020, v.26;No.128(04) 147-153

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SCR系统流场优化数值模拟研究
Study on the numerical simulation of flow field optimization in SCR system

王海川;曾祥浩;廖艳芬;田云龙;马晓茜;
WANG Haichuan;ZENG Xianghao;LIAO Yanfen;TIAN Yunlong;MA Xiaoqian;School of Electric Power,South China University of Technology;

摘要(Abstract):

为提高选择性催化还原脱硝系统(SCR)的烟气气流均匀性,进而提高SCR反应器的催化效率、减少催化剂的冲蚀和损耗、提高催化剂使用寿命和提高催化反应反应物的接触程度,针对SCR反应器的流场开展数值模拟以及导流板和整流板的结构优化,基于Realizable k-ε模型和多孔介质模型,通过对全尺寸SCR反应器模型的速度场的模拟,研究导流板结构、整流板数量对于SCR脱硝系统的流场组织和气流均匀性的影响。通过模拟SCR反应器内的颗粒分布,研究飞灰颗粒对流场的影响。通过计算整流板前截面的相对速度偏差和分析不同优化方案下的SCR反应器的速度场,评估导流板和整流板的导流效果,进而确定最佳方案。结果表明:在弧形、直弧形、弧形、直弧直4种导流板方案中,直弧直形导流效果最好,这是因为弧形导流板前的水平直板和竖直直板可以更好地引导气流流动;结合反应器采用斜顶设计的几何特点,基于流场调整导流板形状与速度梯度方向相同,可以显著优化烟气的气流组织,减少转弯处的能量耗散;催化剂层前的整流板可进一步引导气流流动,极大改善气流均匀性;但过多的整流板提高近壁面处的烟气气流阻力,加剧能量耗散和速度不均匀性,反而降低整流板的整流效果。本研究整流板数量15较为合适。经过对导流板和整流板结构及数量的调整,最终可将催化剂上层的速度偏差降至6.68%,符合工业要求。针对烟气颗粒场的分析表明,飞灰颗粒主要沉积在烟道右壁面和上升通道上壁面处;同时,对颗粒沉积处必要的飞灰处理可减少烟气飞灰对于催化剂的冲蚀作用。
In order to improve the flue gas flow uniformity of SCR system,improve the catalytic efficiency of SCR reactor,reduce the erosion and loss of catalyst,increase the service life of catalyst and improve the contact degree of reactants,in this study,the flow field of SCR reactor was simulated and the structure optimization of guide plate and rectifier plate was carried out.The purpose of the study is that through the simulation of velocity field of full scale SCR reactor model,Realizable k-ε model and porous medium model were used to study the effects of diversion plate structure,number of rectifier plates and fly ash deposition on the flow field organization and the air flow uniformity of SCR denitrification system.At the same time,the influence of fly ash particles on the flow field was studied by simulating the particle distribution in the SCR reactor.By calculating the relative velocity deviation of the section in front of the rectifier plate and analyzing the velocity field of SCR reactor under different optimization schemes,the diversion effect of the guide plate and the rectifier plate was evaluated,and then the best scheme was determined.The results show that the " straight arc" guide plate has the best effect among the four kinds of deflector schemes,because the horizontal straight plate and vertical straight plate in front of the arc guide plate can better guide the air flow.According to the geometric characteristics of inclined top design in reactor,the shape optimization of the right guide plate can significantly improve the velocity uniformity,which can significantly optimize the air distribution of flue gas and reduce the energy dissipation at the turning.The rectifier plate in front of the homogeneous catalyst layer can further guide the flow of airflow and greatly improve the uniformity of airflow.However,too many rectifiers increase the gas flow resistance near the wall,aggravate the energy dissipation and velocity inhomogeneity and reduce the rectifying effect of the rectifiers.In this model,the appropriate number of rectifiers is 15.Ultimately,the deviation of upper catalyst velocity is reduced to 6. 68%,which meets the industrial requirements. The analysis of the flue gas particle field shows that the fly ash particles are deposited on the right wall of the flue and the upper wall of the ascending channel,and the necessary fly ash treatment at the particle deposition can reduce the erosion effect of the fly ash on the catalyst.

关键词(KeyWords): SCR烟气脱硝系统;数值模拟;导流板;多孔介质模型;飞灰沉积
SCR flue gas denitration system;numerical simulation;deflector;porous media model;fly ash deposition

Abstract:

Keywords:

基金项目(Foundation): 国家重点研发计划资助项目(2018YFB0605200);; 广东省高效清洁能源利用重点实验室项目(2013A061401005)

作者(Author): 王海川;曾祥浩;廖艳芬;田云龙;马晓茜;
WANG Haichuan;ZENG Xianghao;LIAO Yanfen;TIAN Yunlong;MA Xiaoqian;School of Electric Power,South China University of Technology;

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DOI: 10.13226/j.issn.1006-6772.19082701

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