多重射流燃烧反应器制备纳米二氧化硅颗粒的数值模拟

Numerical Simulation of Preparation of SiO_(2) Nanoparticles in a Multi-jet Combustion Reactor

建立了不同长径比的千吨级工业多重高速射流燃烧反应器三维物理模型,结合可实现k-ε湍流模型、有限速率/涡耗散模型、涡耗散概念化学反应模型、Discrete Ordinate辐射模型、欧拉-拉格朗日离散相模型、氢气19步详细反应机理与空气龄自定义函数对燃烧反应器内燃烧情况进行了多尺度数值模拟。结果表明,随着燃烧反应器长径比的减小,反应器内温度与速度的衰减程度加剧,反应炉内气体到达出口的时间延长,反应器内涡流现象加重;当注入10~40 nm的纳米二氧化硅颗粒时,颗粒在反应器内部的返混程度加剧,停留时间显著延长。上述模拟结果可为工业设计燃烧反应器的几何结构建立理论基础,同时为气相燃烧法制备纳米材料的合成过程提供参考。

A three-dimensional physical model of 1000-ton industrial multi-jet combustion reactor is established with different aspect ratios,which can realize the models of k-εturbulence finite-rate/eddy-dissipation(FR/EDM),eddy-dissipation-concept(EDC),discrete-ordinate radiation(DO),and Euler-Lagrange discrete-phasemethod(DPM),reaction mechanism with 19-step hydrogen and air age user-defined-function(UDF)has been used to simulate the combustion in a flame reactor.The results show that with the decrease of the length-diameter ratio of the combustion reactor,the temperature and velocity in the reactor attenuates,the time for gas in the reactor to reach the outlet prolongs,and the eddy current phenomenon in the reactor aggravates.When 10-40 nm uniformly distributed silica nanoparticles are injected,the back-mixing degree of particles in the reactor increases and the residence time is significantly prolonged.The aboved simulation establishes a theoretical basis for industrial design of combustion reactor geometry and provides a reference for the synthesis of nano materials by gas-phase combustion.