Determinação do consumo de potência de uma planta piloto de agitação utilizando dados experimentais

Abstract

Industrial processes in several areas depend on an efficient fluid agitation operation, and the system power consumption is an important factor in the design of agitators, mainly referring to economic losses. In addition, the theoretical study of systems subjected to agitation depend on empirical correlations, with this, experimental work in pilot units is widely used as a reference for calculations of power consumption in order to perform scale-up and predict process results in bigger equipment. Thus, this work aims to analyze the influence of agitation system variables on the power consumption of a pilot plant, using the experimental data obtained in the literature. To achieve this objective, the behavior of power consumption was analyzed as a function of the variation of geometric parameters (Di/T, w/Di, and angle of inclination of the blades), and also the power number curves as a function of the Reynolds number. The experimental data were obtained for a 50 L tank, with a configuration of 3 baffles and without baffles, 60 impellers with four straight blades were used, organized in groups of five variations of the width of the impeller blade (w/Di = 0,14; 0,17; 0,20; 0,25 e 0,30), in each group 6 impeller diameter variations were used (Di/T = 0,25; 0,33; 0,40; 0,45; 0,55 e 0,70) and the blade angles were varied twice (45° and 90°), for each adopted configuration. The results showed that power consumption increases with increasing rotational speed, however it was found that this increase depends on the chosen impeller diameter. In addition, the behavior of power consumption established by the literature was graphically proven, the presence of baffles considerably increases the power of the system, as well as the increase in the width of the impeller blades and the expansion of the angle of the blades. The analysis of the power number curves in relation to the Reynolds number showed that the power number of tanks with baffles reaches stability when reaching the turbulent regime, however, for tanks without baffles the power number decreases with the increase of Reynolds, without achieving stability. From the experimental data and the analysis carried out, a didactic worksheet was developed that simulates the behavior of axial and radial flow impellers as a function of the analyzed variables for use as a teaching tool for agitation systems. Paraná. 2010. 154f.