Determination of Key Rate Parameters of the Thermal DeNOx Process by Optimization of a Detailed Combustion Kinetic Mechanism

IF 1.5 4区 化学 Q4 CHEMISTRY, PHYSICAL
András György Szanthoffer, Máté Papp, Peter Glarborg, Hamid Hashemi, István Gyula Zsély, Tamás Turányi
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Abstract

The thermal DeNOx process is a widely used NOx emission control technique, but its chemical kinetic description still lacks accuracy. In the present work, two key kinetic parameters of the thermal DeNOx process were investigated: the branching fraction (α) of the NH2 + NO reaction, and the rate coefficient of the unimolecular decomposition of NNH (inverse lifetime of NNH, τNNH). Values of these rate parameters were determined using a mechanism optimization method that utilizes both direct and indirect data and minimizes the value of an error function. Data were collected from the literature and available in data files on the ReSpecTh site (https://ReSpecTh.hu). Indirect experimental data used as optimization targets were NO mole fractions measured in tubular flow reactors. The most recent nitrogen chemistry mechanism of Glarborg and coworkers (2024) was used as the initial mechanism. Inconsistency was found between the indirect experimental data, and therefore mechanism optimization was not feasible using all the indirect data. Using a new algorithm, a consistent subset of indirect data was identified. The optimized value of τNNH (8.5 ∙ 10−11 s) is approximately an order of magnitude smaller than in the initial mechanism (10−9 s), but consistent with theoretical calculations. The posterior uncertainty of τNNH is significantly smaller than its prior uncertainty. The optimized value of the branching fraction is different from its initial value by less than 2%, but due to the very large sensitivity of the simulation results to α, this small change improves the performance of the mechanism noticeably. The width of the posterior uncertainty range of α is approximately half that of its prior uncertainty range, estimated using only direct measurements. This is a significant improvement, but more accurate indirect experimental data are needed to further increase the accuracy of the determination of α.

通过详细的燃烧动力学机理优化确定热脱氧过程的关键速率参数
热脱硝工艺是一种广泛应用的NOx排放控制技术,但其化学动力学描述仍缺乏准确性。本文研究了热脱氮过程的两个关键动力学参数:NH2 + NO反应的分支分数(α)和NNH单分子分解速率系数(NNH逆寿命τNNH)。这些速率参数的值是通过利用直接和间接数据并最小化误差函数值的机制优化方法确定的。数据从文献中收集,并可在ReSpecTh网站(https://ReSpecTh.hu)的数据文件中获得。间接实验数据作为优化目标,是在管流式反应器中测量的NO摩尔分数。本文采用最新的氮化学机制(2024)作为初始机制。间接实验数据之间存在不一致性,因此采用所有间接数据进行机理优化是不可行的。使用一种新的算法,确定了一个一致的间接数据子集。优化后的τNNH值(8.5∙10−11 s)大约比初始机制(10−9 s)小一个数量级,但与理论计算相符。τNNH的后验不确定性显著小于其先验不确定性。优化后的分支分数值与初始值相差不到2%,但由于仿真结果对α的敏感性非常大,这一微小的变化明显提高了机构的性能。α的后验不确定范围的宽度大约是其先前不确定范围的一半,仅使用直接测量估计。这是一个显著的改进,但需要更准确的间接实验数据来进一步提高α测定的准确性。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
CiteScore
3.30
自引率
6.70%
发文量
74
审稿时长
3 months
期刊介绍: As the leading archival journal devoted exclusively to chemical kinetics, the International Journal of Chemical Kinetics publishes original research in gas phase, condensed phase, and polymer reaction kinetics, as well as biochemical and surface kinetics. The Journal seeks to be the primary archive for careful experimental measurements of reaction kinetics, in both simple and complex systems. The Journal also presents new developments in applied theoretical kinetics and publishes large kinetic models, and the algorithms and estimates used in these models. These include methods for handling the large reaction networks important in biochemistry, catalysis, and free radical chemistry. In addition, the Journal explores such topics as the quantitative relationships between molecular structure and chemical reactivity, organic/inorganic chemistry and reaction mechanisms, and the reactive chemistry at interfaces.
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