灰对煤焦燃烧的动力学研究

Kinetic Study on Ash During Char Combustion

基于表观动力学灰膜缩核模型,本文发展并利用耦合的灰膜与灰渗透本征动力学模型,详细研究焦炭颗粒燃烧特性。氧化反应与气化反应耦合能够高精度预测煤焦颗粒燃烧特性。随灰膜形成比例下降,焦炭颗粒燃烧温度升高,碳燃尽时间缩短;当碳转化率低于80%时,碳转化率主要受灰膜影响,灰渗透影响甚微;但当碳转化率大于80%时,灰膜与灰渗透同时起作用。

On basis of apparent kinetics shrinking core model,a sophisticated intrinsic kinetics model coupled with integrated ash film and ash dilution model is proposed,meanwhile,the char burning properties are studied in detail.Results indicate that gasification reaction must be consisted together with oxidation reaction in order to predict the char burning precisely.With decreased ash fraction forming ash film,the char burning temperature increases,and residence time decreases as a result.When the carbon conversion ratio is below 80%,ash film plays a dominant role,and the effect of ash dilution is slight.While at the last stage,where carbon conversion ratio is above 80%,both the ash film inhibition and ash dilution inhibition play a strong role.