Analysis of a heat recirculating cooler for fuel gas sulfur removal in solid oxide fuel cells

When using conventional fossil fuels, most fuel cell systems require sulfur removal as part of their fuel processing. A novel approach to enable conventional sulfur removal in high-temperature fuel processing is presented. Using established principles from heat-recirculating combustors, it is suggested that high-temperature syngas can be momentarily cooled to conditions that would permit conventional sulfur removal to be carried out at relatively low temperatures. The recirculated heat is then used to heat the gas back to conditions that are minimally less than the original temperature. A model for evaluating the performance of this concept is presented, and calculations suggest that relative to fuel cell applications, reasonable physical dimensions can be expected in actual applications. For high-pressure syngas (i.e., coal gasification), the physical dimensions will rise with the operating pressure.