Javed M Tayyeb, Nimmo W, Gibbs B M
Department of Chemical and Materials Engineering, Pakistan Institute of Engineering and Applied Sciences, P.O. Nilore, Islamabad, Pakistan.
Chemosphere. 2008 Jan;70(6):1059-67. doi: 10.1016/j.chemosphere.2007.07.065. Epub 2007 Sep 12.
An experimental and modeling investigation has been performed to study the effect of process additives, H2 and CO on NO(x) removal from flue gases by a selective non-catalytic reduction process using urea as a reducing agent. Experiments were performed with a flow reactor in which flue gas was generated by the combustion of propane in air at 3% excess oxygen and the desired levels of initial NO(x) (500ppm) were achieved by doping the flame with ammonia. Experiments were performed throughout the temperature range of interest, i.e. from 850 to 1200 degrees C for investigation of the effects of the process additives on the performance of aqueous urea DeNO(x). Subsequently, computational kinetic modeling with SENKIN code was performed to analyze the performance of urea providing a direct comparison of modeling prediction with experimental measurements. With CO addition, a downwards shift of 215 degrees C in the peak reduction temperature from 1125 to 910 degrees C was observed during the experimentation while the kinetic modeling suggests it to be 150 degrees C, i.e. from 1020 to 870 degrees C. The addition of H2 impairs the peak NO(x) reduction but suggests a low temperature application of the process. A downward shift of 250 degrees C in the peak reduction temperature, from 1020 to 770 degrees C, was observed during kinetic modeling studies. The kinetic modeling shows a good qualitative agreement with the experimental observations and reveals additional information about the process.
已开展一项实验与模型研究，以考察工艺添加剂、H2和CO对采用尿素作为还原剂的选择性非催化还原工艺从烟道气中去除NO(x)的影响。实验在流动反应器中进行，其中烟道气通过丙烷在空气中燃烧产生，过量氧气为3%，通过向火焰中添加氨来达到所需的初始NO(x)水平（500ppm）。在整个感兴趣的温度范围内进行实验，即850至1200摄氏度，以研究工艺添加剂对尿素水溶液脱硝性能的影响。随后，使用SENKIN代码进行计算动力学建模，以分析尿素的性能，将模型预测结果与实验测量值进行直接比较。添加CO时，实验过程中观察到峰值还原温度从1125摄氏度向下偏移215摄氏度至910摄氏度，而动力学建模表明偏移为150摄氏度，即从1020摄氏度至870摄氏度。添加H2会削弱NO(x)的峰值还原，但表明该工艺适用于低温。在动力学建模研究中观察到峰值还原温度从1020摄氏度向下偏移250摄氏度至770摄氏度。动力学建模与实验观察结果显示出良好的定性一致性，并揭示了有关该工艺的更多信息。
