Effect of Operation Conditions on Soot Formation in SOFC Stacks

Abstract

SOFCs can be operated with various fuel types which make them attractive to use for different applications. In many of these applications, carbon containing gases are used as fuel that can cause soot formation in the cells especially during heating upcooling down the SOFC stacks. Experiments have been performed in order to understand the effect of temperature, heating rate and gas composition for carbon containing fuel gas by simulating stack operation parameters. The soot formation phenomenon is studied on the pellets made from anode powders as well as on SOFC one cell stacks. The electrochemical behaviour evaluated by I-Vcharacteristics and impedance spectroscopy and microscopic analysis of the cells confirm soot formation when SOFC stack is fuelled under unfavourable temperature regions and heating rates. However, it is also found that stack can regenerate itself during operation after a small amount of coke has been deposited on the electrode.

Strategies for Carbon and Sulfur Tolerant Solid Oxide Fuel Cell Materials, Incorporating Lessons from Heterogeneous Catalysis

“…It is theoretically possible to regain performance without changing the gas mixture by moving from an operating regime where carbon deposition is favored to one where it is not. Ni/YSZ cells were found to completely regain their initial performance after 24 h under load at 850 °C in a simulated partial oxidation reformate feed, having previously had carbon deposited in the same gas mixture at 650 °C under OCV …”