In this Ph.D. thesis a system of coupled fluidized bed reactors is modelled and simulated dynamically. Chemical Looping Combustion was used as an exemplary process in both the numerical and the experimental part of this work. For the simulation purpose a novel flowsheeting software was used and models for the needed process units developed and integrated into this software. The needed unit models were three interconnected fluidized bed reactors in circulating and bubbling operation conditions, a cyclone for gas-solid separation and loop seals, which ensured solids transport and gas separation between the reactors. Additionally, lab scale experiments on the reactivity of the used solids, oxygen carrier and solid fuels, were conducted and kinetic parameters extracted. All unit models were connected to a process flowsheet and simulated dynamically. The simulation results were compared to experimental data from a 25 kWth pilot plant operated at the university by the author. It could be shown that a detailed and dynamic simulation of the whole process can be carried out over a time period of more than 45 minutes and the experimental results from start-up, steady state operation and shutdown of the plant were predicted accurately.