Growing energy demand and environmental concern have constantly pressured the energy industry to apply increasingly efficient combustion methods. Knowing this, and in order to take advantage of the great availability of biomass energy resources from agro-industrial processes in Brazil, the US company Brayton Energy designed a cyclonic combustion chamber as a component of an externally fired gas turbine for power generation using pulverized solid biomass fuels. In this study, numerical simulations were performed using Computational Fluid Dynamics (CFD) to evaluate the fluid dynamic design and the combustion process of biomass particles in this horizontal cyclonic combustion chamber. The simulations were performed in ANSYS FLUENT using the turbulence models RNG k-epsilon and SST k-omega. For the combustion simulations, the Species Transport model was used, alongside the combined method finite rate/eddy dissipation for the turbulence and the chemical reaction interactions. The Discrete Phase Model (DPM) was used for the biomass particles tracking and the Discrete Ordinates model (DO) for the radiation representation. The results of the cold-flow simulations show the profile of axial and tangential velocities within the cyclonic chamber and the formation of the recirculation zones. The recirculation zones with the RNG model showed average velocities of - 35 m/s and - 20 m/s, which indicates the possibility of flame formation inside the combustor. The temperatures of fuel particles at the outlet of the biomass feed pipe reached approximately 470 K, which is a suitable temperature and indicates that the particles are ready to devolatilize inside the combustor. Based on the contours of axial velocities inside the combustor, temperature and the release region of the volatile species, it is concluded that the design of the cyclonic chamber allows the formation of the flame inside the combustor and also the complete combustion of the biomass particles, showing that, despite needing some improvements and optimizations, this cyclonic combustion chamber can be an interesting alternative for power generation with pulverized biomass fuel. {[