(414d) Investigation of the Effect of Baffles on Axial Mixing and Impregnation in a Double Cone Blender

Discrete Element Method (DEM) simulations coupled with a novel algorithm for fluid transfer were used in combination to model dry catalyst impregnation in a double cone blender with baffles with the goal of improving the mixing and fluid content uniformity in the particle bed. The goals of this work are to understand how baffles affect the mixing process in the presence and absence of fluid impregnation in a rotating vessel and to develop a method to determine the optimum baffle position, number and shape. To increase the extent of axial mixing, baffles that break the line of symmetry along the axis (three along the cylindrical section and two along the conical sections of the double cone) were considered. We also propose and test a new hypothesis centered around the idea that the baffles located in the position of maximum velocity will break the flow and offer best mixing performance.

We locate the baffles in 5 different positions and characterize them by means of the aspect ratio between the fill level and the radius of the double cone. The effect of different properties of the baffles, such as their height, width, angle of inclination and number of baffles with the various process parameters, e.g. fill level, particle size, rotational speed, flow rate on the mixing and impregnation performance were studied. Kramer mixing index based on the distance between the volume centers of an axially segregated system, was calculated to quantify the mixing of the system. Simulation results show that there is an optimal baffle height for low fill levels beyond which the mixing performance, whereas the angle of inclination has little to no effect on the mixing performance. Also, the baffle position affects mixing significantly more at lower fill levels, and an optimum baffle position could be found.