(408b) Cold Flow Model Studies of a Counter-Current Moving Bed Syngas Chemical Looping Pilot Unit for High Purity Hydrogen and Electricity Co-Generation with Carbon Capture
The syngas chemical looping (SCL) process developed at the Ohio State University (OSU), which used Fe-based oxygen carrier and a counter-current moving bed reactor design, has the capability of achieving nearly 100% carbon capture and the flexibility of co-generating high purity hydrogen and electricity. A 250 kWth â?? 3 MWth pilot unit operated under 10 atm pressure was designed and operated. The pilot unit consists of three major reactors, the reducer and the oxidizer operated as counter-current moving beds, and the combustor operated as a fluidized bed, to perform reductionâ??oxidation reaction cycles for converting gaseous fuels to highly concentrated discrete streams of hydrogen (H2) and carbon dioxide (CO2). An L-valve is used to transport the solids between the moving bed reactors and the fluidized bed reactor with a controllable solids circulation rate. To investigate the hydrodynamic characteristics and optimize the system design, a one-to-one ratio cold flow model is built and tested. The cold flow model is operated under ambient temperature and pressure with both simulated Geldart Group D particles (glass beads) and actual oxygen carrier particles. The operational conditions of the cold flow model tested are to simulate the expected relative differential pressures and gas-solid flow regimes of the three reactors at operating temperature and pressure. Multiple solid circulation rates and gas processing capacities were tested to understand range of operating conditions achievable in the pilot unit while maintaining proper gas sealing between each reactor and solid circulation rate. The solids circulation rate with respect to the aeration gas flow rate was tested to determine a calibration curve. For solid flow measurement, an iso-kinetic device was designed and tested. To date, over 200 hours of operational results were completed with SCL cold flow model with over 19 test cases completed.