Multi-Field Synergy Analysis of Reaction-Absorption Coupling Process and Numerical Simulation for Ethylene Carbonate Synthesis

To improve the productivity of ethylene carbonate from the esterification of urea and ethylene glycol,the synthesis process is enhanced by removing by-product ammonia via bubbling in phosphoric acid solution.Multi-field synergy principle is employed to analyze the chemical absorption process,then numerical simulation is carried out for absorption of single ammonia bubble with the volume of fluid model.The results show that the chemical absorption of ammonia,which controlled by convective mass transfer,is essentially affected by the synergy of velocity and pressure gradient fields.The synergy is measured with mass transfer field synergy number,which is determined by scalar quantities of the two vector fields,and mostly,by their included angle.While the angle gets zero,the field synergy number reaches to the maximum,which leads to a larger mass transfer coefficient.During the bubbling absorption process,ammonia current inside the bubble facilitates forming tiny vortexes to give rise to the optimized ammonia velocity field and to optimize the synergy with pressure gradient field at gas-liquid interface,thus the field synergy number is maximized and the mass transfer efficiency of ammonia is consequently heightened.