Modelling of gradual internal reforming process over Ni‐YSZ SOFC anode with a catalytic layer

Abstract

Methane appears to be a fuel of great interest for solid oxide fuel cell (SOFC) systems because it can be directly converted into hydrogen by Internal Reforming within the SOFC anode. To cope with carbon formation, a new SOFC cell configuration combining a catalyst layer with a classical anode was developed. The rate of the CH 4 consumption in the catalyst layer (Ir-CGO) was determined experimentally for small values of steam to carbon ratios. This paper proposes a modelling and a simulation, using the CFD-Ace software package, of the behaviour of a SOFC operated in Gradual Internal Reforming (GIR) conditions. This model of SOFC takes into account the kinetics of the steam reforming reaction in the catalyst layer in order to assess the influence of the steam to carbon ratio and the cell polarization. Because the risk of carbon formation is greater under GIR operation, a detailed thermodynamic analysis was carried out. Thermodynamic equilibrium calculations allowed us to predict the conditions of carbon formation occurrence.

Nickel Exsolution‐Driven Phase Transformation from an n=2 to an n=1 Ruddlesden‐Popper Manganite for Methane Steam Reforming Reaction in SOFC Conditions

“…Nevertheless, such high S/C ratios dilute the fuel content and may lead to thermomechanical damages due to large temperature gradients in the anode side (reforming reaction strongly endothermic, while electrochemical reactions are exothermic) and the requirements to produce steam in excess and condense the unreacted products are energetically unfavorable. Therefore, with low S/C ratios, the process needs a small amount of steam at the inlet and the excess is produced in situ by the electrochemical oxidation of the hydrogen obtained during the steam reforming reaction in the anode side; [81,82] this requires the development of specific materials.…”

Catalytic Steam Reforming of Natural Gas over a New Ni Exsolved Ruddlesden‐Popper Manganite in SOFC Anode Conditions

“…Alternatively, the process should be fed with low S/C ratio, considering the in situ production of steam stemming from the electrochemical oxidation of the hydrogen, itself obtained from the steam reforming reaction at the anode. [14,15] Such operation scheme is called Gradual Internal Reforming -GIR (schematized in Figure 1), proposed by Vernoux et al to avoid thermomechanical issues. [16] GIR was experimentally and theoretically demonstrate, resulting in better long-term stability of the cell operating without water excess, but with still insufficient global performance.…”

“…Alternatively, the process should be fed with low S/C ratio, considering the in situ production of steam stemming from the electrochemical oxidation of the hydrogen, itself obtained from the steam reforming reaction at the anode . Such operation scheme is called Gradual Internal Reforming – GIR (schematized in Figure ), proposed by Vernoux et al .…”

Effect of Catalyst Layer and Fuel Utilization on the Durability of Direct Methane SOFC

“…Current developments and technological simplifications based on new principles of operation and original architectures designed in this finality will be presented. In particular the presentation will emphasize on the Gradual Internal Reforming and Electro-catalytic separation principles applied to the design of original anodic systems, and on the demonstration of the reliability of the systems in different pure hydrocarbons or carbon-based fuels (no H 2 O, CO 2 , O 2 or carrier gas addition) [1][2][3][4][5][6]. The effect of the fuel utilization on the limits of carbon deposition will be discussed and the long term durability in pure dry methane will be demonstrated.…”