Towards a recuperative, stationary operated thermochemical reformer: Experimental investigations on the methane conversion and waste heat recovery

In this article, stationary operated, thermochemical recuperation (TCR) based on internal reforming of methane, using oxy-fuel exhaust gases as both heat source and as reactants, is considered. TCR is a promising technology for effective heat recovery from exhaust gases of oxy-fuel furnaces, which could deliver significant increases in combustion efficiency. In order to quantify and validate the potential of TCR, the influence of the main operational parameters on methane conversion and waste heat recovery was experimentally investigated. The experimental investigations presented here differ from previously published work in the following aspects: (I) A stationary, recuperative lab-scale reformer unit filled with industrial nickel catalyst was used to investigate the influence of the oxy-fuel exhaust gas temperature, the exhaust gas recirculation rate and the addition of oxygen to the reactants on the methane conversion and waste heat recovery. (II) The required energy input for the endothermic reforming reaction is provided solely by the thermal energy of the oxy-fuel exhaust gases. (III) The reactants for fuel reforming were exclusively taken from oxy-fuel exhaust gases, resulting in so-called bi- and tri-reforming of methane, depending on the addition of oxygen. The results showed that a maximum CH₄ conversion rate of 65.6% was achieved, with a substantial increase in the combustion efficiency of 17.9%, confirming the ability of TCR to improve the combustion efficiency of oxy-fuel furnaces. In addition, the effects of different reactor configurations on the methane conversion were investigated.