Pre-Reformer Design and Optimization for Solid Oxide Fuel Cells

Abstract

We have conducted optimization for a flow process consisting typical direct internal reforming Solid Oxide Fuel Cell (SOFC) utilizing syngas with anode off gas recycling. The mass and energy balance analysis for the whole system has been carried out. Mass balance (or molar balance) analysis includes optimization for minimum fuel and oxygen consumption rates corresponding to the temperatures of pre-reformer and SOFC, the steam to carbon ratio inside the pre-reformer, recirculation ratio, and rate of CO2 capture. Studies on the reforming chemical reactions and chemical equilibria are presented. The results include CO2 adsorption in the adsorbent bed as well as recirculation. For the molar balance study, we provided methane consumption rate and overall molar balance. With the energy balance analysis, the temperature distributions in the system are calculated. We have also investigated the total system efficiency based on the first law of thermodynamics. The overall efficiency is defined as the total net power output divided by the lower heating value rate of fuel input. We also provided optimal case design parameters. Thermodynamic efficiency is mainly affected by CO2 adsorption percentage under low steam to carbon ratio region, while efficiency is mainly affected by recirculation rate under high temperature operation. In accordance with our simulation, it is recommended high SOFC temperature, moderate SC ratio, moderate CO2 adsorption and high recirculation operation.