硅粉氮化输送床内气固反应过程数值模拟  

Numerical simulation of gas solid reaction process in silicon powder nitriding conveying bed

作　　者：尹少武 张朝[1] 康鹏 韩嘉维 王立 YIN Shaowu;ZHANG Chao;KANG Peng;HAN Jiawei;WANG Li(School of Energy and Environmental Engineering,University of Science and Technology Beijing,Beijing 100083,China;Key Laboratory of Energy Saving and Emission Reduction,University of Science and Technology Beijing,Beijing 100083,China)

机构地区：[1]北京科技大学能源与环境工程学院,北京100083 [2]北京科技大学冶金工业节能减排北京市重点实验室,北京100083

出　　处：《化工进展》2022年第5期2256-2267,共12页Chemical Industry and Engineering Progress

基　　金：国家自然科学基金(51106008)。

摘　　要：以单个硅颗粒氮化反应缩核模型为基础,本文建立了硅颗粒在输送床内反应、辐射与对流传热耦合的数学模型,并借助CFD软件FLUENT对输送床内能质传输过程进行了数值模拟,分析了输送床壁面温度、氮气流量、预热温度、硅粉粒径等因素对输送床内温度场和硅粉氮化率的影响。在数值计算域内将单个颗粒反应过程转化为颗粒群整体反应过程,实时监测颗粒粒径及未反应硅颗粒粒径,为数值模拟颗粒流反应提供一种新思路。当壁面温度高于1723K时,输送床内会出现一高温区加速硅粉氮化反应;反应温度越高、颗粒粒径越小,氮化过程越剧烈,硅粉到达完全氮化所需时间越短。模型表明为使粒径为2.5μm的硅粉达到完全氮化且输送床内最高温度不超过氮化硅的分解温度2173K,应控制输送床壁面温度在1773K,氮化时间在170s以上,预热温度在1273K,粉气质量比为0.2,稀释剂比例为0.5~1。Based on the model of the nucleation reduction of single silicon particles,a mathematical coupling model of reaction,radiation and convection heat transfer of silicon particles in the conveying bed was established.With the help of CFD software FLUENT,the process of energy and mass transfer in the conveying bed was numerically simulated,and the effects of wall temperature,nitrogen flow rate,preheating temperature and particle size of silicon powder,powder gas ratio and diluent ratio on the temperature field and conversion rate of silicon powder in the conveying bed were analyzed.In this paper,a method was proposed to transform the reaction process of single particle into the whole reaction process of particle group in the numerical calculation domain,and the particle size and unreacted silicon particle size can be continuously monitored,which provided a new idea for numerical simulation of granular flow reaction.The reaction process of silicon powder in the conveying bed was similar to that of pulverized coal combustion,and a high temperature zone would be formed in the conveying bed to accelerate the nitriding process of silicon powder.The higher the reaction temperature and the smaller the particle size,the more intense the reaction process and the shorter the time required for the silicon powder to reach complete nitriding.The model showed that in order to make the silicon powder with the particle size of 2.5μm react completely and the maximum temperature did not exceed the decomposition temperature of Si;N;at 2173K,the wall temperature of conveying bed should be controlled at 1773K in the nitridation time of above 170s at the preheating temperature of 1273K with the ratio of powder to gas of 0.2 and the diluent ratio between 0.5 and 1.

关 键 词：氮化硅 能质传输 颗粒流 数值模拟 流态化 直接氮化 输送床 

分 类 号：TK124[动力工程及工程热物理—工程热物理]