煤焦颗粒燃烧过程中纳米颗粒形成的动力学研究

摘要

On the basis of previous developed intrinsic kinetics model of coal char combustion,a modified model, which couples mineral vaporization,homogeneous nucleation and heterogeneous condensation,is employed to study the formation of nanoparticles under different oxygen contents.As the oxygen content increases,both tempera-ture and the vaporization amount of refractory minerals increase,thus generating many more and greater nanoparti-cles.During the combustion,a couple of mineral vapor molecules nucleate and form a nanoparticle with an initial size of 5,nm.And the nanoparticle can grow up to 20—30,nm at the end of the combustion because of subsequent heterogeneous condensation.The growth of the nanoparticles is mainly at the beginning of combustion and the aver-age diameter of the nanoparticles increases first and then decreases with coal char burnout.%在煤焦颗粒本征动力学模型基础上，耦合矿物质气化-同相成核-异相冷凝沉积模型，研究了氧气体积分数对纳米颗粒动态生成的影响．随氧气体积分数升高，燃烧温度升高，难熔矿物质气化率升高，生成更多、更大的纳米颗粒．燃烧过程中1～2个矿物质蒸气分子同相成核生成一个初始粒径为5,nm左右的纳米颗粒，随后由于异相冷凝沉积，当煤焦颗粒燃尽时，颗粒增大到20～30,nm．颗粒生长主要处于燃烧初期，随煤焦燃尽颗粒平均尺寸先增加后下降．