Design and Scheduling of Semibatch Chemical-Looping Reactors

Chemical-looping combustion is explored as a chemical reactor design problem. The continuous operation of fixed bed reactors using gaseous fuels for the purpose of power generation through integration with a combined cycle power plant is studied. The fixed bed reactors are assumed to operate in a semibatch mode composed of reactor modules that are integrated into module trains that comprise the chemical-looping combustion island of the power plant. The scheduling of each reactor train is cast as an optimization problem that maximizes thermodynamic efficiency subject to constraints imposed to each reactor and the entire island. It is shown that when the chemical-looping reactors are arranged cyclically, each feeding to or being fed from another reactor, in an operating scheme that mimics simulated moving bed reactors, the thermodynamic efficiency of the reactor island can be improved. Allowing the reversal of module order in the cyclically arranged reactor modules further improves the overall thermodynamic efficiency (to 84.7%, defined as the fraction of enthalpy sent to the gas turbine of a combined cycle power plant over the total energy output of the reactor), while satisfying constraints imposed for carbon capture, fuel conversion, power plant safety, and oxygen carrier stability.