(501g) Modelling and Simulations of Methane Heat Exchange Reformer for Fuel Cell Applications

A model for a novel methane heat exchange reformer is presented. The advantages of such a reformer for fuel cell applications are compact foot-print and suitability for small scale use. Steam reformer is modeled as a pseudo homogeneous reactor. Concentration and temperature dependence of viscosity of gas mixture is incorporated in reformer model for better accuracy. Pressure of flue gas and steam reformer is assumed to be constant. Gas is assumed to be an ideal gas. The reactor comprises of two catalyst bed. Feed gas is fed downwards through first catalyst bed where it is heated by convection from both the combustion products and reformed product gas, both flowing countercurrent to the feed. On leaving the first catalyst bed, the partially reformed gas is transferred to the top of second catalyst bed. The gas flowing downwards through second catalyst bed is heated by combustion products and reformed. Resulting model equations are solved numerically, using a finite element method, for each flow arrangement under different operating parameters. From simulation results, the reactor is optimized for best feed composition and inlet temperature which maximize methane conversion and hydrogen to carbon monoxide ratio. It is shown that combination of co-current and countercurrent heat transfer minimizes metal temperatures, an important consideration in high-temperature reformer design.