The Ohio State University Chemical Looping Processes: 25 Kwth Sub-Pilot Performance Studies for Natural Gas Conversion and 250 Kwth Pilot Unit Developments

The increasing focus on developing alternative fossil fuel conversion technologies is fueled by growing concerns on controlling carbon emissions from traditional technologies in a cost-effective manner. Amongst the newer technologies , chemical looping has been established as a promising candidate exemplified by larger scale demonstrations world-wide. Chemical looping processes utilize metal based oxygen carriers to inherently produce a concentrated CO2 stream coupled with efficient heat-integration which serves to reduce costs and justify potential commercial scale application. The Ohio State University (OSU) has developed multiple product flexible iron-based chemical looping processes for utilizing fossil fuels like coal and natural gas in a unique moving bed reactor design. OSU’s chemical looping technologies are driven by the thermodynamic motivation of using higher oxygen carrying capacity of iron-oxide. This enables the process to enlist the flexibility of converting a variety of fuels like coal , natural gas and biomass to generate electricity , hydrogen , syngas or a combination of products with zero or negative CO2 emissions. The iron-oxide based oxygen carriers have been developed to sustain hundreds of redox cycles without loss in reactivity and structural integrity. Amongst the OSU processes , the Syngas Chemical Looping (SCL) process has been developed for converting gaseous fuels to high purity CO2 and demonstrated for more than 350 hours on a sub-pilot (25 kWth) scale. With support of the Advanced Research Projects Agency – Energy (ARPA-E) of the United States Department of Energy (USDOE) a 250 kWth high-pressure SCL pilot unit is being constructed at the National Carbon Capture Center. The pilot unit is designed to handle a 250 kWth syngas produced from a commercial Kellogg , Brown & Root transport gasifier to generate high purity hydrogen coupled with a concentrated CO2stream. This will validate the chemistry and operational capability on a commercially applicable scale , thereby completing an important step in the pathway to commercialization. This presentation will summarize multiple parametric studies which elucidate the interplay of factors like fuel residence time , oxygen-carrier to fuel ratio and temperature for optimizing the natural gas conversion and thereby the process efficiency in the SCL sub-pilot system. The presentation will also include theoretical reactor modeling studies coupled with an overview and comprehensive commercial techno-economic analyses of other OSU chemical looping technologies. Finally , the design development and the progress of the pilot plant construction will be presented.