Modelagem e validação de reator anaeróbio gaslift utilizando fluidodinâmica computacional

Abstract

Due to the great demand for energy resources, it is necessary to search for new energy sources and improve the efficiency of the equipment that depends on it. An alternative is the use of bioreactors to transform organic matter into biogas which has become a viable alternative for obtaining an energy source. As a source of organic matter that can be transformed into biogas, the sugar and alcohol industry and the production of biodiesel generate a large amount of waste, such as vinasse and glycerol. Among the types of bioreactors, the pneumatic stirring ones have the characteristic of using injected gases in their interior in order to provide a better mixture. Gaslift reactors use gases with the absence of oxygen with biogas being the most common. Understanding the behaviour of the fluid inside bioreactors helps the development of improvements increasing the productivity of biogas production. In order to understand the behaviour of the fluid, Computational Fluid Dynamics (CFD) offers tools that allow the analysis of flows, without the need to build a physical bioreactor. For the results to be valid, it is necessary to compare the results obtained computationally and experimentally. The work developed in this study sought to validate and understand the results obtained through CFD techniques, analysing a two-phase gas/liquid flow and validating the results using particle imaging velocimetry (PIV). With the validated results, the bubble diameter was modified between 0.5 and 7.0 mm, maintaining the same inlet flow for both phases. These results showed that bubbles with smaller diameters have velocities lower than those with larger diameters for the gas phase and an increase in the velocity of the liquid phase. It was observed that this influence of the bubble diameter caused a greater mixing, due to the volume of gas trapped in bubbles of smaller diameter. [resumo fornecido pelo autor]