Early CPFD simulation studies on designing a fluidized bed reactor for alumina chlorination showed that the model suffers from high particle outflow and dense phase bed channeling. The present study is aimed to optimize the previous alumina chlorination fluidized bed reactor model through modified geometry, parameter modifications, and improved meshing. To optimize the performance of the reactor, complex geometry with an extended top section was combined with a regular cylindrical reactor. Besides, the gas inlet pattern was changed from an ideal uniform distribution to a non-uniform one. Besides, the reactor’s inlet diameter is reduced, and the value for the particle sphericity and voidage has been updated based on experimental observations. The results show that the new reactor with an extended cross-sectional area on top has a significantly lower particle outflow even with the higher inlet superficial gas velocity. The paper discusses the optimization steps and relevant changes in reactor performances in detail.