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化学反应动力学模型的准确性与计算量的矛盾是限制选择性非催化还原(selective non-catalytic reduction,SNCR)数值模拟的主要因素。通过敏感性分析和引入准稳态假设,对包含60个组分、371个基元反应的SNCR详细机制—— A机制进行简化,得到包含28个组分、97个基元反应的骨架机制及最终的包含12种主要组分、8步总包反应的简化机制模型,减小了化学反应速率的计算量。进一步利用柱塞流反应器(plug flow reactor,PFR)模型计算,验证了反应温度、停留时间以及氨氮摩尔比等因素影响下简化模型的准确性,与常用的SNCR两步总包反应模型相比,有显著的改进。在此基础上,将简化机制的化学反应速率计算程序以用户自定义函数的形式加入Fluent软件,用一维几何模型验证了在商业计算流体力学(computational fluid dynamics,CFD)软件平台上使用简化机制进行SNCR反应流数值模拟的可行性,并进一步对沉降炉SNCR过程进行了CFD模拟,研究了温度、扩散、湍流等因素对SNCR的影响,模拟结果与实验吻合良好。
The conflict between the accuracy of the chemical reaction kinetic model and the calculated amount is the main factor that limits the numerical simulation of selective non-catalytic reduction (SNCR). Through the sensitivity analysis and the introduction of the quasi-steady-state hypothesis, the SNCR detailed mechanism-A A mechanism of reaction consisting of 60 components and 371 motifs was simplified and a skeleton mechanism consisting of 28 components and 97 motifs was obtained And finally a simplified mechanism model of 12 main components and 8-step total package reaction, which reduces the calculation of the chemical reaction rate. Furthermore, the model of plug flow reactor (PFR) was used to verify the accuracy of the simplified model under the influence of reaction temperature, residence time and ammonia-nitrogen molar ratio. Compared with the SNCR two-step total reaction model , There is a significant improvement. On this basis, the simplified chemical reaction rate calculation program is added into the Fluent software in the form of a user-defined function, and the one-dimensional geometric model is used to validate the simplified mechanism of the computational fluid dynamics (CFD) software platform The numerical simulation of SNCR flow was carried out. The SNCR process of SNCR was simulated by CFD. The influences of temperature, diffusion and turbulence on SNCR were also studied. The simulation results agree well with the experiment.