Hydrodynamics of the novel three-phase monolith froth reactor

A novel three phase reactor system made with stacks of monolith and a froth feeding mechanism for gas-liquid reactions catalyzed by solid catalysts is gaining acceptance over the traditional three phase reactors due to its superior performance. The rate of reaction inside this reactor is determined by the characteristics of gas-liquid flow through millimeter size square channels of the monolith on the walls of which the catalyst is deposited. Flow visualization experiments revealed the existence of bubble-train flow inside the channels consisting of finite bubbles separated by liquid slugs flowing cocurrently upwards.; Inside the individual channels of the monolith reactor, parameters like bubble and liquid velocities, the thickness of the diffusion layer surrounding the catalyst on the capillary wall and the gas and liquid fractions are determined by the gas and liquid flow rates. Experiments were done with single glass capillaries to determine these parameters for different gas and liquid flow rates. A hydrodynamic model detailing this complex functional relationships on macroscopic flow rates was developed and compared with experimental results.; The flow patterns inside the slug affect the distribution and mixing of the liquid phase and it was determined experimentally by Particle Imaging Velocimetry. The liquid phase was seeded with neutrally buoyant particles, illuminated with a sheet of laser light and the flow field was recorded in a frame of reference moving with the bubbles. This revealed the distinct flow patterns of the liquid phase. The velocity profile was determined and compared with theory. The parameter, recirculation time was defined for the bubble-train flow and the increased radial mass transfer rate for small slugs was explained.; The residence of the liquid phase is another important parameter for the analysis of the monolith reactor. The residence time of the liquid phase in bubble-train flow is determined by the mixing inside the slug and thickness of the film surrounding the bubble. Experimental determination of residence time of the liquid phase was done by conductometric technique. The diffusion model of mass transfer for bubble-train flow was developed considering the details of the flow inside the slug. This model was compared with experimental results. The residence time of the monolith froth reactor was also discussed.