| In the production and processing of polymers,some small molecule volatiles such as unreacted solvents and monomers will inevitably remain in the polymer,which are not only harmful to health and environment,but also can damage the performance of polymer products,so the process of polymer devolatilization is particularly important.Normally,polymer melts or solutions are generally viscous fluids with poor fluid flow and increased difficulty in diffusion of volatiles,while high viscosity leads to thicker liquid films and high mass transfer resistance,which increases the difficulty of devolatilization.Super gravity rotating packed bed as a new and efficient polymer de-volatilization equipment.It can disperse the polymer fluid into fine micro-elements,which improves the surface renewal rate and increases its gas-liquid contact area,thus achieving the effect of devolatilization.In order to expand the application of supergravity technology in polymer devolatilization,the kinetic factors（Diffusion coefficient）and thermodynamic factors（Henry coefficient）in polymer devolatilization need to be determined experimentally first,and then the efficiency of volatile fraction removal and liquid-phase mass transfer law in a rotating packed bed need to be studied.In this paper,an accurate test device for diffusion coefficient and Henry coefficient of volatile fraction components in viscous fluids was established and related measurements were performed to obtain important basic data for devolatilization;a mixture of dimethyl silicone oil（PDMS）and acetone was used to simulate a viscous fluid with acetone as the volatile substance,and a supergravity rotating packed bed（RPB）was used to study the devolatilization of volatile organic compounds in viscous fluids,and the influence of high gravity factor,liquid viscosity,inlet flow rate,vacuum degree,initial content of acetone and other factors on the volatile component removal efficiency and liquid-phase volume mass transfer coefficient was investigated,and the better process parameters for supergravity viscous fluid volatile removal were determined;the correlation equation between the liquid-phase mass transfer coefficient and the operating and physical parameters was established by the method of dimensionless analysis.The results showed that:（1）The Henry coefficient of acetone increases with the increase of viscosity and temperature,and the growth rate is around 7.117%for viscosity below 10.299 Pa·s,and around3.110%for viscosity between 10.299 and 51.282 Pa·s.The diffusion coefficient of acetone increases with the increase of viscosity and mass fraction,and decreases with the increase of liquid film thickness.When the viscosity is greater than 20 Pa·s,the trend of diffusion coefficient decreases with viscosity.（2）The volatile fraction removal rate increased with the increase of the high gravity factor,but the magnitude of the increase gradually slowed down and leveled off;the volatile fraction removal rate gradually decreased with the increase of the inlet flow rate;the volatile fraction removal rate increased with the increase of the vacuum level and the initial content of acetone in the supergravity rotating packed bed.Supergravity de-volatilization process conditions:supergravity factor of 60,inlet liquid flow rate of 10 L-h-1,vacuum of 0.081 MPa.（3）The liquid-phase volumetric mass transfer coefficient was in the range of 0.24×10-3～5.7×10-3,which increased with the increase of high gravity factor,inlet flow rate,initial content of volatile fraction and vacuum degree,and decreased with the increase of liquid viscosity.The effects of inlet flow rate and liquid viscosity on the liquid-phase volumetric mass transfer coefficient are more obvious.The calculated results of the fitted correlation equation were within 21%error with the experimentally measured data,and the results of the correlation equation were in good agreement with the experimental data results. |
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