Process simulation on atomization and evaporation of desulfurization wastewater and its application

Abstract

With increasing social concern towards industrial wastewater treatment, desulfurization wastewater evaporation technology is attracting attention in theoretical investigation and showing competitive capability in practical applications by virtue of its low cost and high efficiency. In engineering practice, the selection of nozzle model, evaporation chamber size and flue gas source need to be carefully determined, ideally with comprehensive understanding of the process mechanism. Important factors to be considered include wastewater evaporation characteristics such as evaporation time, distance, and so on, which are difficult to be obtained directly through physical experiments. Numerical simulation can be utilized conveniently for the extraction of such data and further post analysis. In this study, a salt containing droplet evaporation model is combined with a two-way interphase coupling method to investigate the spray evaporation process. Numerical results show that by increasing the injection velocity and the liquid film thickness, and reducing the flue gas velocity, droplets were observed to be more dispersed in the flue, which in turn enhance the evaporability. The velocity difference between the gas-liquid phases is correlated with the gas-phase turbulent kinetic energy. Non-uniform inlet velocity can increase the flow turbulence intensity. This leads to enhanced droplet evaporation performance on one hand, but increased probability of the droplets hitting the wall on the other hand. From this study, we have also observed that the droplet evaporativity increases with the temperature. Finally, an optimal set of parameters are selected from the simulation exercises to achieve an optimal evaporation outcome. These parameters are introduced in large engineering design to guide the selection of the nozzle model and determine the evaporation chamber size.