A bubble column reactor is a  chemical reactor that belongs to the general class of multiphase reactors, which consists of three main categories: trickle bed reactor (fixed or packed bed), fluidized bed reactor, and bubble column reactor. A bubble column reactor is a very simple device consisting of a vertical vessel filled with water with a gas distributor at the inlet. Due to the ease of design and operation, which does not involve moving parts, they are widely used in the chemical, biochemical, petrochemical, and pharmaceutical industries to generate and control gas-liquid  chemical reactions.
Despite the simple column arrangement, the hydrodynamics of bubble columns is very complex due to the interactions between liquid and gas phases. In recent years, Computational Fluid Dynamics (CFD) has become a very popular tool to design and optimize bubble column reactors.