Abstract:

The traditional random pore model is based on a simple one step reaction, which is not suitable to describe the complex gas-solid reaction of coke particles in O₂/CO₂ atmosphere. Based on the various carbons in coke and the characteristics of single char combustion in O₂/CO₂ atmosphere, the various char-RPM and the model of pore structure under the complex gas-solid reaction were established. The combustion process of char particles with a diameter of 100 μm in O₂/CO₂ atmosphere was simulated, and the results were calculated and analyzed by FORTRAN. The research showed that the particles in the early stage of combustion had a competitive effect and the gas concentration in the pore was fluctuated. The reason for fluctuation was the competition between chemical reaction and physical diffusion, which can be improved by increasing the O₂ concentration or decreasing the particle size. The various char-RPM proposed in this work had a good adaptability to characterizing the combustion characteristics of char particles in O₂/CO₂ atmosphere.

Key words: O₂/CO₂ atmosphere, porous media, random pore model, single particle char combustion, mass transfer, mesoscale, numerical simulation

摘要：

传统随机孔模型基于简单一步反应建立，不适用于处理O₂/CO₂气氛下焦炭颗粒复杂气固反应。针对此问题，基于焦炭本身具有多种碳基的特点，以及焦炭颗粒在O₂/CO₂气氛下燃烧的特性，建立复杂气固反应下的多种碳基随机孔模型和孔隙结构模型。模拟直径为100 μm的焦炭颗粒在O₂/CO₂气氛下燃烧的过程，使用FORTRAN语言自主编程计算并分析结果。研究表明，燃烧初期颗粒呈现竞争效应，孔隙内部气体浓度产生剧烈波动。波动的生成原因是化学反应与物理扩散之间的竞争，可以通过增加环境氧浓度和减小焦炭颗粒粒径来改善。所提出的多种碳基随机孔模型对于表征O₂/CO₂气氛下焦炭颗粒的燃烧特性有着良好的适应性。

关键词: O₂/CO₂气氛, 多孔介质, 随机孔模型, 单颗粒焦炭燃烧, 传质, 介尺度, 数值模拟