Iron-based syngas chemical looping process and coal-direct chemical looping process development at Ohio State University

Abstract

The increasing demands for energy and concern of global warming are intertwined issues of critical importance. With the pressing need for clean, efficient, and cost-effective energy conversion processes, the chemical looping strategy has evolved as a promising alternative to the traditional carbonaceous fuel conversion processes. Chemical looping processes utilize oxygen carrier particles to indirectly convert carbonaceous fuels while capturing CO2 for sequestration and/or utilization. Throughout its development, multiple oxygen carrier compositions and reactor configurations have been studied and demonstrated. The Ohio State University (OSU) chemical looping technologies have received significant attention over the recent years. OSU’s unique moving-bed chemical looping technologies coupled with iron-based oxygen carrier particles capable of sustaining hundreds of redox cycles have the advantage of converting a variety of carbonaceous fuels, such as natural gas, coal and biomass, to electricity, H2, liquid fuels, or any combination thereof with zero to negative net CO2 emissions. Specifically, two chemical looping processes are being developed and studied, the syngas chemical looping (SCL) and the coal direct chemical looping (CDCL) technologies. Over the past 14years, these processes have developed from a novel concept to successful sub-pilot (25kWth) demonstrations. With the support of the Advanced Research Projects Agency – Energy (ARPA-E) of the US Department of Energy (USDOE), a 250kWth high pressure SCL pilot scale demonstration project was initiated for processing syngas to cogenerate pure H2 and sequestration-ready CO2 from a Kellogg Brown & Root gasifier at the National Carbon Capture Center. A 25kWth CDCL sub-pilot plant has been constructed and demonstrated at OSU with the support from National Energy Technology Laboratory (NETL) of the United States Department of Energy (USDOE). The combined SCL and CDCL operational time at reactive conditions well exceeds 850h. Multiple aspects of the OSU chemical looping development including the oxygen carrier properties, reaction mechanism studies, reactor design and modeling studies, the bench and sub-pilot scale process testing results, energy integration optimization, and techno-economic analyzes are discussed.