Estudo do desempenho de lavadores de gases do tipo venturi com seção circular

Abstract

In the last years the ambient legislation are becoming more rigid with the objective to minimize the emission of atmospheric pollutants. Thus, the venture scrubbers appear as alternative of equipment with high efficiency of separation in an ample grain sized band and present few operational restrictions and can be used to collect both particulate and gaseous pollutants. In this work it was studied the performance of venturi scrubbers with circular section in different operational conditions of length throat, liquid flow and air velocity and to compare with the results gotten through the models of Calvert (CALVERT et al., 1972), modified Calvert (RIBEIRO, 2005) and Johnstone (JOHNSTONE et al., 1954). The solid used in the experiments was phosphate powder from Patos de Minas (Minas Gerais, Brazil) with a density of (3040Kg/m3) as determined by hot picnometry. The experimental system used in this work it consisted of six venture scrubbers with circular section (three with 23 mm of throat diameter and others three with 33 mm) with injection of liquid through simple orifice located in the throats. The efficiency was valued with two experimental design kind 33 with 27 experiments, one for each throat diameter. It was evaluated the length throat in the levels 66, 99 and 132mm of throat length, the liquid flow in the levels 180, 360 and 540 mL/min and the air velocity in the levels 4, 7 and 10 m/s. Global collection efficiencies was produced with values between 11 and 89% for the first design (33 mm of throat diameters) and values between 20 and 100% for the second design (23 mm of throat diameters). Through the statistical analysis of the results, for the first design, it was verified that, considering a level of significance of 10%, the variables liquid flow, air velocity and the quadratic interaction of throat length had significant influence in the global efficiency collection. For the second design, it was verified that the variables liquid flow, air velocity, interaction between liquid flow and air velocity and the quadratics interactions of liquid flow and air velocity had significant influence in the global efficiency collection. A trend of increase in the removal of particles with the increase of the liquid flow and air velocity was observed. It was verified that when varying the throat diameter of 33mm for 23mm occurred an increase in the global efficiency collection. The predictions of the global efficiency collection models of Calvert, modified Calvert and Johnstone with the gotten values experimentally were observed that the models of Calvert overestimated the values of efficiency in low air velocities and substimated in high air velocities, the modified Calvert model and the Johnstone model substimated the values of efficiency.