Investigation Of Porous Media Tray Based On Interfacial Wettability

Foam Si C prorous media tray posesses good hydrodynamic performance and mass transfer efficiency.As for distillation tray,the Process Intensification research based on structure design has been extensively investigated,however,the Process Intensification research based on surface and interface properties,in particularly wettability has not yet been reported.This thesis developed surface modification methods to regulate and control interfacial wettability,and thus investigated the change rules of interfacial wettability and the interaction mechanism between distillation tray and test speicies,finally revealed the effect of interfacial wettability on the hydrodynamics(pressure drop,weeping and gas distributuion)of column tray,and conducted preliminary exploration on the application of interfacial-wettability-based catalytic tray in Fischer-Tropsch Reactive Distillation.Here we first analyzed the mechanism of interfacial wettability based on surface and interfacial forces,subsequently analyzed the single bubble behavior,multi-bubble behavior and the gas-liquid two-phase flow inside porous media,and analyzed interfacial wettability effect on the hydrodynamic performance of column tray.Combined with the simplified physical model of foam structure,we revealed the intrinsic mechanism of interfacial wettability on gas-liquid two-phase flow,the new decomposition strategy of column tray's total pressure drop considering interfacial wettability effect is established,and in the meantime the influence rules of interfacial wettability on column trays' hydrodynamics are proposed.Finally we propose that interfacial wettability may be an alternative way to intensify the performance of porous media tray.Based on the above process analysis,we designed the experimental parts to do the systematic validation and obtain quantitative results.Firstly,we developed in situ coating growth method to fabricate superhydrophobic model tray and Janus model tray with static contact angle of 157° based on the hydrophilic model tray with static contact angle of 61°.Also,we developed ex situ coating methods(including sol dip-coating method and spray coating)to design and fabricate porous media trays with different static contact angle(51°,95°,120°,140°,155°),dynamic contact angle(contact angle hysteresis: 32° vs.63°),achieved the controllability of interfacial wettability of column tray.Then a series of stability tests were conducted and confirmed that the coatings are very stable under various conditions.Subsequently,we investigated the hydrodynamics of porous media model tray with simplified physical structure,and preliminarily found the influence rules of static contact angle on column tray's hydrodynamics,namely Janus model tray presents the best overall performance,namely medium pressure drop,the least weeping and the most uniform gas distribution compared with hydrophilic model tray and superhydrophobic model tray.Finally,we investigated the interfacial wettability effect on the hydrodynamic performance of porous media tray,and the results indicate that pressure drop gradually decreases,weeping increases and overall gas distribution becomes more uniform with the increasing contact angle or decreasing contact angle hysteresis and all the experimental results presents the good consistency with the performance criteria concluded from process analysis in Chapter 2.In addition,the merits and technical feasibility of super-repellent porous media tray as catalytic tray in Fischer-Tropsch Reactive Distillation are explored.In summary,the research in this thesis offer a new way to intensify porous media tray,and the new methodology of process equipment design and intensification based on interfacial wettability are established.