| 中高温区水合肼SNCR脱硝反应机制和特性研究 |
| 摘要点击 2163 全文点击 1157 投稿时间：2011-10-12 修订日期：2011-12-29 |
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| 中文关键词 选择性非催化还原(SNCR) 水合肼 NOx 温度窗口 敏感性分析 |
| 英文关键词 selective non-catalytic reduction (SNCR) hydrazine NOx temperature window sensitivity analysis |
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| 中文摘要 |
| 研究了水合肼选择性非催化还原法(SNCR)还原烟气中NOx的反应机制并加以实验验证,同时利用敏感性分析找出主导肼SNCR反应进程的基元反应,并分析了各相关因素对水合肼SNCR反应的影响,机制分析显示肼的脱硝反应温度呈双峰特性,峰值温度分别为650℃和975℃, 低温段窗口为597~747℃.实验结果表明水合肼的SNCR双峰温度分别为653℃和968℃,低温段温度窗口为587~707℃,模拟和实验结果中的脱硝效率均呈现显著的双峰值特性.通过模拟计算与实验验证,发现本研究归纳的反应机制能较好地模拟肼的SNCR脱硝过程; 通过敏感性分析确定,在肼的脱硝温度窗口内,最有助于NO脱除的基元反应是N2H4的分解反应,最有助于NO脱除的是NH2基元; 氧气体积分数降低会导致肼的SNCR反应温度窗口向高温侧偏移,这一现象与氨水相反; n(N2H4)/n(NO)的增加会在摩尔比低于2.0时拓宽反应温度窗口并提升脱硝效率.研究表明水合肼拥有比传统脱硝剂更低的温度窗口,在SNCR脱硝工艺中具有良好的应用前景. |
| 英文摘要 |
| The kinetic mechanism of NOx reduction with hydrazine hydrate in selective non-catalytic reduction (SNCR) process was studied and verified by the experimental results, the dominant radicals and reactions were confirmed through sensitivity analysis and key parameters in SNCR process have been obtained. The results of numerical simulation based on the proposed mechanism showed that the effective temperatures for SNCR de-NOx process were bimodal distribution with the optimum temperatures being 650℃ and 975℃ respectively and the lower temperature window fell in the range of 597-747℃; while the experimental results proved the bimodal distribution of effective temperature with peak values being 653℃ and 968℃ respectively and the lower temperature window was within the range of 587-707℃ for hydrazine-based SNCR process. Simulation results and experimental results matched well with respect to reaction behaviors versus temperature. Through sensitivity analysis it had been found that the most effective reaction to reduce NO was the decomposition reaction of N2H4 to NH2 and the most helpful radical was NH2. Compared to ammonia the temperature window of hydrazine-based SNCR process on the lower temperature side is more flexible for application. Decreased O2 concentration would move the temperature window to the right side, which was contrary to that of ammonia; while increased n(N2H4)/n(NO) moved the temperature window to the left side and NOx reduction efficiency was also improved. All of these results showed that hydrazine has lower temperature window than those traditional de-NOx reagents and it will be widely used in application of SNCR as a potential reductant for NOx reduction. |
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