Modeling Chemical Looping Gasification with Agroforestry Residues: Validation against Results in a 20 kWth CLG Unit

Biomass chemical looping gasification (BCLG) represents an innovative process that allows the generation of non-nitrogen-diluted synthesis gas with low tar content and the potential to avoid CO₂ emissions. In this work, a 1.5D macroscopic model for the fuel reactor of a BCLG unit was developed and validated to simulate the performance of the system under different operating conditions. The model was developed as simple as possible in order to have a powerful tool to simulate a large number of conditions in a relatively short period of time with low computing effort. However, it has the required complexity to consider the main processes affecting the reaction of the biomass and the oxygen carrier, such as reactor fluid dynamics and the reaction pathway of biomass in the fuel reactor. The main outputs of the model are presented and validated against results from a 20 kW_th BCLG unit with two biomasses, namely, pine forest residue and wheat straw pellets. The effects of several operating conditions (temperature, solid circulation rate, solid inventory, and gas flow) on the syngas yield and composition were successfully predicted by the model.