楼宇型分布式能源系统SCR脱硝数值模拟研究
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摘要
燃气分布式能源系统燃烧产生的氮氧化物难以满足日益严格的环保排放要求;同时,燃气分布式能源系统的结构特点决定其脱硝系统必须紧凑布置。采用Fluent软件对某楼宇型分布式能源站拟建的选择性催化还原脱硝装置进行数值模拟研究,初步引入导流板、整流栅及气流均布板等结构,提出了3种不同的改进方案,定量分析了烟道内的速度场、组分场及温度场的分布规律。结果表明:加装导流板及整流器可有效改善混合器及反应器内流场的均匀性,气流均布板结构促进了第1层催化剂入口断面内流场的均匀性;相比于原方案,改进之后的脱硝装置中NO及NH_3在第1层催化剂层的速度、质量分布及温度的均匀度明显提高,且速度不均匀度为20. 81%,满足预期设计要求。可为楼宇型分布式能源系统脱硝提供参考,同时也可为系统装置后期的优化设计奠定基础。
The nitrogen oxides produced during combustion process of the distributed energy system driven by natural gas are still difficult to satisfy the requirements of China's increasingly stringent environment emission standard. Meanwhile,the layout of denitrification system has to be compact according to the structural of gas distributed energy system. The software Fluent is used to simulate the selective catalytic reduction and denitrification device of a building-type distributed energy station. Flow deflector,aerodynamic grid and airflow distribution board are briefly introduced,and 3 different improvement schemes are proposed. Quantitative analyses on the distribution of velocity,composition and temperature fields in the gas ducts are made. The results show that the flow deflector and aerodynamic grid can effectively improve the uniformity of the flow field in the mixer and the reactor. The airflow distribution board promote the uniformity of the flow field in the inlet of the first catalyst layer. Compared with the original scheme,the uniformity of velocity,mass distribution and temperature uniformity of the NO and NH_3 on the first catalyst layer are improved obviously,and the velocity nonuniformity is only 20. 81%,which satisfied the requirements. The results can provide reference for denitrification of building-type distributed energy system,and set a foundation for the following optimization design.
The nitrogen oxides produced during combustion process of the distributed energy system driven by natural gas are still difficult to satisfy the requirements of China's increasingly stringent environment emission standard. Meanwhile,the layout of denitrification system has to be compact according to the structural of gas distributed energy system. The software Fluent is used to simulate the selective catalytic reduction and denitrification device of a building-type distributed energy station. Flow deflector,aerodynamic grid and airflow distribution board are briefly introduced,and 3 different improvement schemes are proposed. Quantitative analyses on the distribution of velocity,composition and temperature fields in the gas ducts are made. The results show that the flow deflector and aerodynamic grid can effectively improve the uniformity of the flow field in the mixer and the reactor. The airflow distribution board promote the uniformity of the flow field in the inlet of the first catalyst layer. Compared with the original scheme,the uniformity of velocity,mass distribution and temperature uniformity of the NO and NH_3 on the first catalyst layer are improved obviously,and the velocity nonuniformity is only 20. 81%,which satisfied the requirements. The results can provide reference for denitrification of building-type distributed energy system,and set a foundation for the following optimization design.
引文
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[4]陈志锋.燃气内燃机三联供系统烟气脱硝技术分析[J].华电技术,2017,39(1):71-72.
[5]郭甲生,李巡案,徐振华,等.天然气分布式能源系统烟气脱硝方案[J].煤气与热力,2014,34(6):13-15.
[6]侯建鹏. SCR法烟气脱硝系统数值模拟研究[D].西安:西安理工大学,2008.
[7]韩发年,闫志勇. SCR烟气脱硝工艺喷氨混合装置研究进展[J].化工进展,2015,34(12):4151-4157.
[8]STREIFF F,FLEISCHLI M. Static mixing element having deflectors and a mixing device:US,Re. 36969[P]. 2000-11-28[2018-09-27].
[9]潘伶,杨沛山,曹友洪. SCR脱硝反应器烟道内部流场的数值模拟与优化[J].环境工程学报,2015,9(6):2918-2924.
[10]王福军.计算流体动力学分析:CFD软件原理与应用[M].北京:清华大学出版社,2004.