聚集辐照下甲烷水蒸气重整制氢过程参数研究

基于自行设计的小型太阳能热化学反应器,建立了聚集辐照下甲烷水蒸气重整数学模型,该模型耦合导热、对流、辐射以及化学反应动力学,计算得到了反应器内甲烷重整过程反应物及产物的浓度、反应速率及温度场的分布,获得了不同工况参数(孔隙率、气体入口温度、水碳比)对甲烷转化率的影响规律。研究结果表明:甲烷水蒸气重整在多孔区域入口处反应迅速,沿反应器中心线方向,反应速率由于反应物浓度的不断降低而减小,导致混合气体的浓度及温度趋于稳定。孔隙率、水碳比及气体入口温度的增加都会导致甲烷转化率增加。当入口温度为500 K、孔隙率为0.75、水碳比为2.5、入口速度为0.006 m/s时,甲烷的转化率为96%,氢气产率为28%。该研究结果对甲烷水蒸气重整制氢过程参数优化具有一定的参考意义。 

Parameters research for hydrogen production of methane steam reforming under concentrated radiation

In this paper, a mathematical model was developed for the hydrogen production of methane steam reforming under concentrated radiation based on a self-designed solar thermochemical reactor. The model that coupled conduction, convection, thermal radiation and chemical reaction kinetics was adopted to calculate the concentration, reaction rates and temperature of reactant and product in reactor and to investigate the effect of various operating parameters (porosity, gas inlet temperature, steam to methane ratio) on the conversion rate of methane. The research results showed that:Methane steam reforming reacts rapidly at the inlet of porous region. Along the reactor centerline, the reaction rate decreases due to the constant decrease of reactant concentration, which leads to the steady concentration and temperature of the mixed gas. The conversion rate of methane conversion increases as the increasing in porosity, gas inlet temperature and steam to methane ratio. The methane conversion rate was 96%, the hydrogen yield was 28% while the gas inlet temperature, porosity, steam to methane ratio and inlet velocity were 500 K, 0.75,2.5 and 0.006 m/s, respectively. The research results have certain reference significance for parameter optimization for hydrogen production process of methane steam reforming.