Abstract: By constructing a multiphysics coupled numerical model, which includes momentum, energy, and mass balance equations, as well as chemical reaction equations, and using porous medium model to characterize catalyst layer, the methane steam reforming (MSR) process in an industrial tube reactor was analyzed in detail in this work. The velocity, temperature, and concentration distributions of the reactant and products in the tube were obtained, which were used to analyze the characteristics of the MSR process, and to illustrate the impacts of tube wall temperature, steam-methane-ratio and inlet velocity on the conversion rate of methane. The results show that the reaction velocity of MSR is very fast at inlet area, and decreases gradually along gas flow direction because of the decreased concentration of reactant gases, which also induces mixture gas flow velocity and temperature become steady. The conversion rate of methane increases with increasing steam-methane-ratio and tube wall temperature, and decreasing reactant gas inlet velocity. The results will be helpful for optimizing the reaction condition of an actual MSR process.

Key words: natural gas, hydrogen production, computer simulation, influence factors, conversion rate, numerical analysis

摘要： 本文通过建立包含动量、能量、质量以及化学反应的多物理场耦合数值模型, 以多孔介质模型表征催化剂层, 对工业转化炉管中的甲烷水蒸气重整制氢过程进行了详细分析。计算得到了转化炉管内甲烷重整过程反应物及产物气体的速度、温度及浓度场分布, 以此分析了甲烷重整制氢过程的反应特性, 并阐明了转化炉管的壁面温度、原料气入口水碳比以及入口速度对甲烷转化率的影响。结果表明:水蒸气重整在转化炉管的入口区域反应迅速, 沿着气体流动方向, 反应速率由于反应物浓度的不断降低而减小, 导致混合气体流动速度和温度也逐渐趋于稳定;水碳比和转化管壁面温度的增加以及原料气体入口流速的降低, 都会提高甲烷的转化率。本文所得到的结论对于优化实际生产中甲烷水蒸气重整制氢反应的工况条件具有一定的参考和借鉴意义。

关键词: 天然气, 制氢, 计算机模拟, 影响因素, 转化率, 数值分析