加入CH4促进选择性非催化还原的CFD模拟研究

在实验研究和机理分析基础上利用计算流体动力学(computational fluid dynamics，CFD)软件Fluent，结合简化的反应机理模型，对沉降炉脱除NOx实验过程进行了模拟研究。模拟结果表明，在较低反应温度(1 073 K)下，喷入的氨基还原剂基本不与烟气中的NOx反应，形成较高的氨泄漏；而在较高的反应温度(1 373 K)下，喷入的氨基还原剂部分被烟气中的氧气氧化为NOx，导致NOx脱除效率较低。加入微量CH4能够促进较低温度下的选择性非催化还原(selective non-catalytic reduction，SNCR)反应，并减少氨泄露。在较高温度下SNCR反应速率加快，仍有部分NH3被氧化为NOx，但总体NOx脱除效率有所提高。模拟结果与实验结果的对比分析表明，采用简化的反应模型和CFD结合可以对常规SNCR反应和加入CH4的脱除NOx反应过程进行较为准确的模拟。

Numerical Investigation on Promoting Selective Non-catalytic Reduction With Methane Additive by Computational Fluid Dynamics

Based on experimental and mechanism research the process of promoting selective non-catalytic reduction (SNCR) with methane additive in a drop tube furnace was investigated by computational fluid dynamics (CFD) software Fluent integrated with simplified reaction dynamics model. The results indicate that the reducing agent ammonia hardly reacts with NOx at low temperature (1 073 K) resulting high ammonia slip. However some ammonia is oxidized into NOx at high temperature (1 373 K) leading to low NOx removal efficiency. Trace CH4 can promote SNCR reaction and reduce ammonia slip at lower temperature. Reduction rate of NOx is accelerated with CH4 additive. Part of ammonia is still oxidized into NOx, but the overall NOx removal efficiency is enhanced at higher temperature. Comparison between simulation results and experimental data shows that combination of simplified reaction dynamics and CFD can give an accurate simulation of traditional SNCR and SNCR process with methane additive.