Operation and Performance Limitations for Solid Oxide Fuel Cells and Gas Turbines in a Hybrid System

Abstract

Temperature limitations of Solid Oxide Fuel Cells (SOFC) in transient single operation and steady-state Hybrid System (HS) operation with Gas Turbines (GT) are presented. For transient SOFC simulations, an unsteady-state SOFC model was developed by upgrading a detailed validated steady-state model. As critical SOFC single operation modes, concerning the risk of material cracking due to exceeding SOFC transient temperature gradients, heat-up and cool-down are investigated. For minimization of transient SOFC temperature gradients at start-up and shut-down, a stepwise heat-up and cool-down procedure is proposed. Concerning HS off-design and part-load operation, the impact of SOFC temperature limitations on the operational window is investigated. Results show a reduced operational window due to exceeding local SOFC temperature gradients, which can be reduced by optimal adaptation of GT to SOFC size.