The study of evaporation characteristics of the desulfurization wastewater (electrolyte solution) droplet

In this study, the evaporation behavior of a desulfurization wastewater (electrolyte solution) droplet with different solute concentration at different ambient gas temperature, was investigated by hanging on a glass fiber in a hot constant chamber. A high speed camera was used to record the evaporation process of the droplet. The radius change of the droplet in different conditions were given. A fine thermocouple was inserted in the distilled water droplet to record the temperature history during evaporation. A mathematical model was built with consideration of the effects on the concentration of the water activity and the density change. The results showed that concentration in the surface region was higher than that in the uniform concentration model. The uniform concentration was an assumption of less precision for this droplet evaporation calculation. Additionally, for the wastewater solution whose density changed greatly with concentration, the results showed the density change gave the dominated factor affecting the change of the droplet evaporation rate. Finally, the evaporation and crystallization process gave the effect on the surface region of the droplet keeping the solute concentration relatively high. This lead to the lower evaporation rate when adding non-evaporating dissolved solutes at the beginning period of evaporation.