Characteristics of heat transfer and chemical reaction of methane-steam reforming in a porous catalytic medium

Abstract

We did a numerical examination of the heat transfer and chemical reaction characteristics in methane-steam reforming, which is widely used in the petrochemical industry. In fact, the prediction of temperature variation along the reformer tube is essential for methane-steam reforming, as it also causes material failures, such as thermal stress concentration. Thus, the influence of the Reynolds number and the porosity variation of catalysts inside the reformer tube on methane-steam reforming was examined. The commercial code of Fluent (V. 13.0) was used for the current simulation. An axisymmetric reformer tube with porous catalytic medium was modeled and two kinds of porosity, which ranged from 0.35 to 0.50, were adopted. The temperature of the fuel gas and the external heat source were 780.15 K and 1291.55 K, respectively. The standard k-epsilon model and the eddy-dissipation-concept model were employed. In addition, conjugated heat transfer was considered for estimation of the heat transfer from the external heat sources to the reformer tube. The Discrete ordinate (DO) model for radiation effects was also used. It was found that the radial temperature distribution of the high Reynolds number is lower than that of the low Reynolds number. The axial temperature distribution varied because of the heat transfer from the external heat source and the dominant endothermic chemical reactions. The mole fraction of products increased as the Reynolds number decreased. Both radial and axial temperature increased inside the reformer tube as the porosity was denser. However, the effect of porosity variation on the methane-steam reforming could not be distinctively observed in this study.