Influence of swirl intensity on atomization characteristics and dust-reduction using pressure swirl nozzle

Abstract

ABSTRACT Pressure swirl nozzles are widely applied in various mineral industries, and their excellent spray performances have been found to be directly related to dust removal results. In this study, in order to examine the influencing effects of the swirl intensity levels of pressure swirl nozzles on atomization characteristics and dust-reduction efficiency, five spiral guide grooves were added for the purpose of improving the quality of the atomization and dust control. The swirl intensities of pressure swirl nozzles were first theoretically investigated using the established models. The effects of the swirl intensities on the atomization angles and distributions of the atomization sizes were comparatively studied using theoretical calculations, numerical simulations, and experimental methods. A dynamic wind tunnel was built in order to conduct dust-reduction experiments with different swirl intensities. The proximate and ultimate analysis results and the sizes of the coal samples were characterized, and the mechanism of the dust reduction was summarized. The results demonstrated that the applications of spiral guide grooves improved the atomization angles and coverage areas by up to 98.8° and 73%, respectively. At the same time, the enhancements of the swirl intensities were observed to reduce the uniformity index of the distribution sizes,` which significantly decreased the Sauter mean diameter (SMD) from 101.3 μm to 22.1 μm. The atomization results revealed that the increasing of the stagger angles benefited the larger atomization angles and smaller SMD. In addition, the proposed theoretical model had achieved better prediction accuracy. Also, the high atomization quality had obviously improved the dust-reduction ability of the pressure swirl nozzles, with the efficiency of total dust and respirable dust removeable increased by approximately 11.23% and 9.33%, respectively.