An oxy-fuel mass-recirculating process for H2production with CO2capture by autothermal catalytic oxyforming of methane

Abstract

A new oxy-fuel H2generation process with CO2avoidance is provided. The process utilizes mass recirculation of CO and H2O to the oxyforming reactor. A comparison between non-recirculating and mass-recirculating oxyforming reactor operation is given. Main benefits of mass recirculation are emphasized. The oxyforming reactor is integrated with the H2and CO2separators, fuel cell and O2generator. In the process C/O is equal to 0.5 while C/H determines the temperature level in the reactor. The reaction system includes combustion, steam reforming and water-gas shift reactions. The oxyforming process is found to be mass transport controlled with O2as the limiting reactant. It is emphasized that under MR conditions the decomposition of H2/CO2by water-gas shift reaction is suppressed by means of CO/H2O-enrichment and hence MR conditions allow for higher temperatures beneficial to endothermic steam reforming reaction. Under MR conditions the thermodynamic equilibrium limits are overcome and all reactions are forced to proceed to the completion which enables 100% selectivities to H2and CO2. The effects of operation parameters such as temperature, flow rate, pressure and composition are examined. The derived S-terms enable for the concise interpretation of the effect of pressure on the concentration gradients transverse to the flow. The consistent control algorithm of the oxyforming reactor is provided. © 2010 Professor T. Nejat Veziroglu.