携带流反应器上混合过程对添加H2的选择性非催化还原影响研究
Influence of Mixing on the Selective Non-catalytic Reduction Process With H2 Addition in Entrained Flow Reactor
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摘要: 采用柱塞流反应器(plug flow reactor,PFR)模型和Zwietering反应器模型对携带流反应器(entrained flow reactor,EFR)上添加H2的选择性非催化还原(selective non-catalytic reduction,SNCR)反应进行反应动力学计算分析。实验和计算结果表明:采用Miller98机制和Zwietering反应器模型可以较好地描述混合过程对添加H2的SNCR脱硝过程的影响。反应温度低于725℃时,化学反应速率低,反应主要受化学反应速率的控制,混合过程对NO还原反应影响很小。而温度高于725℃时,混合过程对NO还原的影响明显。反应产率分析表明,混合过程对添加H2的SNCR过程影响,主要以反应NH3+H=NH2+H2的途径使NH2活性基团减少,降低了脱硝效率。Abstract: The impact of H2 on the selective non-catalytic reduction（SNCR） reactions in an entrained flow reactor（EFR） was modeled with the plug flow reactor（PFR） and Zwietering models.A detailed kinetic reaction mechanism was used in this work.The simulation results and experimental results show that: the effect of mixing process on SNCR process with H2 addition can be depicted well by the Zwietering model integrated with the Miller98 kinetic mechanism.Below 725 ℃,the reaction rate is lower and the SNCR process is mainly controlled by chemistry,and the mixing process hardly has any effects on the SNCR process.Above 725 ℃,the reaction rate increase,and the SNCR process is limited by the mixing process.After a mechanical analysis of the H2 additive,it is concluded that the mixing process strengthens the NH3 + H = NH2 + H2 reaction;while reducing the important middle radicals（NH2）,which reduces the efficiency of SNCR.
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