Performance assessment of thermochemical CO2/H2O splitting in moving bed and fluidized bed reactors

In this paper, we present the assessment of moving bed reactors and fluidized bed reactors operating in different fluidizing regimes for solar thermochemical redox cycles (STRC) for syngas production. The reduction reactor with a moving bed (MBRED) while the oxidation reactor (OXI) is either a moving bed reactor (MBOXI) or bubbling bed (BBOXI) yields higher performance. It was observed that only water splitting is suitable at 1400 degrees C and 10-3 bar reduction conditions. The higher reduction temperature and pressure improved the efficiency of the CO2/H2O splitting unit. The requirement of the H2/CO ratio drives the gas feed (CO2/H2O) into OXI. To achieve an H2/CO ratio of 1, MBOXI and BBOXI require an equimolar mixture of CO2 and H2O at 1600 degrees C. However, to achieve a similar H2/CO ratio at a lower temperature of 1500 degrees C, the gas feed of the CO2/H2O ratio required is 3. A similar H2/CO ratio is achieved for OXI operating in a turbulent and fast fluidizing, but the selectivity is lower due to lower reaction rates. OXI as a transport bed is least suited based on solid conversion (XOXI), H2/CO, or efficiency. The results are useful in designing the redox reactors for syngas. (c) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved. <comment>Superscript/Subscript Available</comment