单一球团气一固反应体系的非等压模型及其数学解析

PRESSURE DIFFERENCE KINETIC MODEL AND MATHEMATICAL SIMULATION ON A SINGLE PELLET GAS-SOLID REACTION SYSTEM

本文以未反应核缩减模型为基础，建立描述气一固反应的非稳态非等压力学模型。利用实测的动力学参数和经验公式估算结果，数值求解偏微分方程组。计算结果表明，在本文讨论的条件范围内，气体压强在固态产物层内的分布比较均匀，但随反应时间变化比较明显。在多孔介质内不仅气体总量在变化，而且，气体组成也在变化。计算结果进一步揭示，在Ｈ２还原钛铁矿团过程中，限制反应速率的本质原因在于难扩散组分（水蒸汽）的扩散过程。另外，本文还考虑了各主要操作条件对气一固反应的影响规律，并探讨等压模型的近似适用条件。

On the basis of unreacted-core shrinking model,an unsteady state pressure difference kinetic model interpreting gas-solid reaction was developed The governing differential equations were solved numerically with kinetic parameters measured experimentally and those estemated according to empirical correlations.The calculated results reveal that under the calculation conditions,the radial distribution of the total pressure of gaseous species within the sold product layer is almost uniform,however,it varies obviously with reaction time Within the porous medium,not only changes the amount of gases accumulated,but its composition varies as well It is further found out that the very rate-limiting step of the hydrogen reduction of ilmenite pellet is the outward diffusion of aqueous vapor The influence of some important operational parameters on the kinetics of the gas-solid reaction as well as the conditions under which an isobaric kinetic model approximately applies are also discussed