THERMODYNAMICS OF PRESSURE SWING ADSORPTION (PSA) IN THE RECOVERY OF RESIDUAL HYDROGEN FROM SOFC ANODE GAS

摘要

In SOFCs, high operating temperatures allow for internal reforming of light hydrocarbons to H_2 and CO. 75-85% of the fuel can be consumed in the stacks. High temperature anode gas exhaust consists of H_2, H_2O, CO and CO_2. The proposed process consists of cooling the exhaust, passing it through a low temperature shift and recovering hydrogen gas. The hydrogen gas is then returned to the anode, thus increasing electrical conversion efficiency. The analysis incorporates a model for pressure swing adsorption (PSA) in H_2-CO_2 separation. An optimization is developed to determine the operating pressure that will incur the least parasitic power loss. State, energy and mass equations are solved numerically to yield curves for optimized electrical conversion efficiencies.