Otimização das variáveis operacionais e de projeto de uma coluna de flotação por Airlift utilizando técnicas de computação fluidodinêmica

Abstract

The oil segment is one of the sectors that move the most capital in the world, in contrast it is one of the ones that generate the most hazardous waste to the environment. Because of this, mitigating policies are applied to these companies in order to circumvent this problem. Thus, the research of processing wastewater treatment technologies are important for the development and reduction of costs in the segment. Among the processes used, dissolved air flotation is one of the most applied physical separation operations. The efficiency of this technique has a strong influence on the hydrodynamics of internal flows. In the literature one can observe works that propose new configurations for a column in order to increase residence times and the contact between droplets and microbubbles. Because it consists of a very complex flow with several interconnected phenomena, the study with fluid dynamics computation becomes fundamental to this analysis for the evaluation of the phenomena that occur within this equipment. In order to evaluate the influence of operational and design variables of a flotation column by Airlift, such as bubble feed rates and effluent; positioning of the effluent feed and the effluent treatment flow from the column. These were evaluated via computational analysis via Ansys CFX 13 package. The main results obtained in this analysis were: The bubble feed rate has the character of improving the efficiency of the column as it is increased, otherwise the effluent feed produces a fall in efficiency with the increase of the speed of this, the feed in countercurrent at the top of the column was shown to be more efficient and the rate of removal of the treated effluent of 50% in relation to the total volumetric flow entering the column was more efficient than the other rates studied.