This chapter analyses the requirements for replacing a 122 MWth, 150-t industrial boiler with an equivalent Chemical Looping Combustion (CLC) boiler. The process design of the CLC boiler involved modelling the hydrodynamics of the circulating fluidised bed configuration used for air and fuel reactors. These reactors were scaled up from a 120 kW CLC pilot plant using natural gas fuel and nickel oxide as the oxygen carrier. The fuel and air reactors use a single steam drum that supplies boiler feed water to water-cooled coils that generate saturated steam. The CLC boiler requires about double the volume of the conventional 150-t boiler without carbon capture, and about the same volume as the boiler with carbon capture. The specific volumes of the proposed CLC configuration were 20.75 \({\text{m}}^{3} /{\text{t}}_{{{\text{CO}}_{2} }}\) formed and 21.77 m3/MWh of power generated. A key finding of the design process was the need for multiple air and fuel reactors to accommodate the various firing levels, ranging from 20 to 100% of design capacity, necessary in practical industrial operations. The fuel and air reactors in the proposed configuration are arranged in parallel, with their diameters being approximately 70 and 50% of hypothetical single reactors that processed the entire flow.