Limits of performance of chemical looping air separation in packed bed coupled with electricity production

Oxyfuel combustion, as a carbon capture method, requires oxygen to be separated from nitrogen. Currently, cryogenic air separation is used for this purpose. An alternative is to use chemical looping, where an oxygen carrier is cycled between reducing and oxidising conditions. In this paper, the feasibility of using packed bed reactors in chemical looping air separation is studied. By introducing a compressor and turbine, oxidisers can be operated at an elevated pressure and the proposed scheme can be viewed as a power-station in its own right, in addition to its more recognised application of producing oxygen for a downstream oxy-fuel combustion. For typical oxygen carriers, a single packed bed reactor is not able to meet the 0.30–0.35 oxygen molar fraction needed for an oxyfuel combustor. Therefore, multiple beds must be used in series or heat must be added radially along the bed length to increase the oxygen molar fraction in the bed.