Study on foaming of formulated solvent UDS and improving foaming control in acid natural gas sweetening process

• Process parameters have an effect on foaming performance of UDS solution.
• An increase in CO2 loading enhances foaming tendency.
• A semi-empirical model is proposed to predict the foaming behavior of UDS solution.

The influences of various factors including concentration of solvent, operation temperature, gas flow rate, CO2 loading on foaming tendency of UDS solvent were experimentally investigated under simulated conditions. Foaming tendency test was combined with physical characterization to enhance the understanding of the foaming behavior. It was indicated that the foam height kept increasing while the foam breaking time first rose and then dropped as gas flow rate increased. Foaming tendency increased and eventually decreased with UDS concentration. Moreover, an increase in CO2 loading enhanced foaming tendency. Meanwhile, lower solution temperature resulted in larger foam height and longer breaking time. Surface tension, viscosity, and density of solutions played complex roles in determining foaming tendency and foam stability. A semi-empirical model considering gravitational force, viscous force and surface tension force was found to be able to explain the parametric effects on the foaming of UDS solution and predict its foaming behavior very well. Finally, defoaming agent DF-C was observed to improve the foaming control of UDS system to a satisfactory level.