Estudo sobre o efeito de vibrações axiais sobre a formação e remoção de tortas de filtração gás-sólidos

Abstract

Many studies related to the filtration of gases for the control and recovery of particulate materials have been developed with the aim of making the filtration system, both in the gas filtration operation as in the cleaning operation, more effective, with a longer useful life of the fabric filters and with greater ease of removal of cake filtration, tanking into account the currente laws regarding the emission of pollutants not environment and reduction of maintenance and operation costs. In this context, in order to make the gas filtration operation more efficient, the objective of this work was to adapt a filtration system with vibration motor coupled axially to the gaseous flow that would allow the detachment of the filter cake without the need to stop the operation filtration, and to evaluate the influences of mechanical vibration frequencies in the formation of cakes as the forces of drag on the filter medium, the thickness of cakes filtration, specific resistance of cake, porosity of cake compared with the static system. The manioc starch powder, pure talcum powder and phosphate rock were used as particulates in order to verify the influence of vibration on particulates with different morphologies and granulometric distribution. The surface filtration velocity of the gaseous stream was 10 cm / s at a mass flow rate of 0.183 g / s and the maximum pressure drop was 10000 Pa. The porosities of the cake filtration were determined by correlations found in the literature. The results showed that the frequencies of mechanical vibration 12, 17 and 18Hz influenced the structure of the cake and its removal for the rock phosphate particulate material, whose circularity was of 0.60, causing a formation of thinner of cake filtrantion, more resistant cake filtration and less porous cake filtrantion when compared to the static system. As adhesion forces of material also higher for vibration frequencies than the static system. It was concluded that the mechanical vibrations caused a denser packing of the phosphate rock particles in the filter medium. As for the particulate material, pure talcum powder, , whose circularity was of 0.67, the mechanical vibrations to both the independent system and the intermittent system provide behavior similar to the static system, it is not feasible to use. For the particles of manioc starch, whose circularity approaches a perfect circle, 0.98, for the independent vibration frequency of 12 Hz allowed the formation of cake filtration with greater thicknesses, smaller specific resistances of the cake filtrantion and larger porosities when compared to the static system, as well as lower adhesion force when compared to the static system. This may be related to the appearance of gaps in the cake filtration and the distribution of the particles in the layers of the cake filtration. Finally, the system of independent and intermittent mechanical vibration did not allow the detachment of the filter cake, but influenced the structure of the cake formation.