The Ohio State University Chemical Looping Processes: 25 Kwth Sub-Pilot Performance Studies for Natural Gas Conversion and 250 Kwth Pilot Unit Developments
- Type: Conference Presentation
- Skill Level:
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.